CN112757233A - Hammer drill - Google Patents

Abstract

The invention provides a hammer drill. A hammer drill (101) is provided with a motor, a main shaft (31), a drive mechanism (5), a main body case (10), a movable support (18), a first intermediate shaft (41), an intermediate member (63), and a first transmission member (64). The movable support is capable of moving in the front-rear direction integrally with the main shaft and at least a part of a drive mechanism including a motion conversion member (61) in a state where the movable support is biased. The intermediate member is rotatable relative to the first intermediate shaft and immovable in the front-rear direction. The first transmission member is rotatable integrally with the first intermediate shaft and is movable in the front-rear direction between an engagement position at which the first transmission member is engaged with the intermediate member and a separation position at which the first transmission member is separated from the intermediate member. The motion conversion member is rotatable integrally with the interposed member and is movable integrally with the movable support in the front-rear direction with respect to the interposed member. Accordingly, the present invention provides a technique that can contribute to the stability of the power transmission state in the drive mechanism of the hammer drill.

Description

Hammer drill

Technical Field

The present invention relates to a hammer drill capable of performing an operation of linearly driving a tip tool and an operation of rotationally driving the tip tool.

Background

The hammer drill is configured to be capable of performing a hammer action and a drill action, wherein the hammer action is an action of driving the tip tool linearly along the driving axis; the drilling action is an action of rotationally driving the tip tool about the drive axis. Generally, a hammer drill is provided with a switching mechanism for switching a power transmission state in a drive mechanism according to a selected operation mode. For example, in a hammer drill disclosed in japanese patent laid-open publication No. 2016 and 000447, power for hammer operation is transmitted via a rotation transmission member disposed on an intermediate shaft. The rotation transmitting member is disposed so as to be movable in the axial direction of the intermediate shaft. The rotation transmitting member is moved between a position where it engages with the rotating body to which the swing shaft for converting the rotational motion into the linear motion is attached and a position where it does not engage with the rotating body, thereby switching the power transmission state from the intermediate shaft to the rotating body.

Disclosure of Invention

[ problem to be solved by the invention ]

In the hammer drill, the drive mechanism is supported by the housing so as to be movable relative to the housing in a state in which the biasing force of the coil spring is applied. Accordingly, transmission of vibration generated by the drive mechanism to the housing is suppressed. On the other hand, since the drive mechanism also moves relative to the intermediate shaft and the rotation transmitting member supported by the housing, the engagement state between the rotation transmitting member and the rotating body may become unstable.

In view of the above circumstances, an object of the present invention is to provide a technique that can contribute to the stability of the power transmission state in the drive mechanism of the hammer drill.

[ solution for solving problems ]

According to one aspect of the present invention, there is provided a hammer drill including a motor, a final output shaft, a drive mechanism, a housing, a movable support, a first intermediate shaft, an interposed member, and a transmission member.

The motor has a motor shaft. The final output shaft is configured to retain the tip tool in a manner that allows removal of the tip tool. The final output shaft is configured to be rotatable about a drive axis. The driving mechanism is configured to be capable of performing a hammer action and a drill action by the action of the motor. The hammering is an action of linearly driving the tip tool along the driving axis. The drilling action is an action that drives the tip tool in rotation about the drive axis. The drive mechanism includes at least a motion conversion member configured to convert rotational motion into linear motion. The housing is for housing the motor, final output shaft and drive mechanism. The movable support supports at least a part of the drive mechanism including the final output shaft and the motion conversion member in the housing, and is configured to integrally move in the axial direction of the drive axis with respect to the housing in a state of being urged by at least one elastic member.

The first intermediate shaft is supported by the housing so as not to be movable in the axial direction relative to the housing. The first intermediate shaft is configured to rotate about an axis parallel to the drive axis in accordance with rotation of the motor shaft, and to transmit at least power for hammer operation to the motion conversion member. The intermediate member is disposed so as to be rotatable relative to the first intermediate shaft and immovable in the axial direction. The clamping component is clamped between the first intermediate shaft and the motion conversion component. The transmission member is disposed so as to be rotatable integrally with the first intermediate shaft and movable in the axial direction relative to the first intermediate shaft. The transmission member is movable in the axial direction between an engagement position and a disengagement position. The engagement position is a position at which the transmission member is engaged with the interposed member and power can be transmitted from the first intermediate shaft to the interposed member. The separated position is a position where the transmission member is separated from the interposed member and power cannot be transmitted from the first intermediate shaft to the interposed member. The motion conversion member is rotatable integrally with the interposed member and is movable integrally with the movable support in the axial direction relative to the interposed member.

In the hammer drill according to the present invention, at least a part of the drive mechanism including the final output shaft and the motion conversion member is supported by the movable support and is configured to be integrally movable with respect to the housing in the axial direction of the drive axis in a state of being biased by at least one elastic member. Accordingly, transmission of vibration generated by the drive mechanism to the housing is suppressed.

The rotation of the first intermediate shaft is transmitted to the motion conversion member via the transmission member and the interposed member. The transmission state of transmission to the motion conversion member is switched by moving the transmission member in the axial direction between the engagement position and the disengagement position on the first intermediate shaft. The motion conversion member is movable in the axial direction relative to the interposed member, but the interposed member is not movable in the axial direction relative to the first intermediate shaft and, therefore, relative to the housing. Therefore, even if the motion conversion member moves in the axial direction with respect to the housing in accordance with the vibration, the positional relationship between the intermediate member and the transmission member disposed in any one of the engagement position and the disengagement position on the first intermediate shaft is not affected. That is, the power transmission state to the motion conversion member can be stably maintained.

In one aspect of the present invention, the first intermediate shaft may have a spline portion provided on an outer periphery. The transmission member may be engaged with the spline portion of the first intermediate shaft. In this case, the transmission member can be arranged to be rotatable integrally with the first intermediate shaft and to be movable in the axial direction relative to the first intermediate shaft with a simple configuration.

In one aspect of the present invention, the interposed member may have a spline portion provided on an outer periphery thereof. The motion conversion member may be engaged with the spline portion of the interposed member. In this case, the motion conversion member can be arranged to be rotatable integrally with the interposed member and to be movable in the axial direction with respect to the interposed member with a simple configuration.

In this technical scheme, the transmission part can have the first spline portion that can press from both sides the spline portion block that establishes the part. That is, the spline portion of the interposed member may be used for both engagement with the motion conversion member and engagement with the transmission member. In this case, the components can be appropriately engaged with each other with a simple and compact structure.

Also, the first intermediate shaft may have a spline portion provided on an outer periphery. The transmission member may have a second spline portion that engages with the spline portion of the first intermediate shaft. Also, the diameter of the first spline section may be larger than the diameter of the second spline section. That is, the transmission member may be engageable with the intermediate member via the first spline portion, and may be engageable with the first intermediate shaft via the second spline portion. In this case, the first spline portion has a large diameter, so that torque can be transmitted efficiently.

In one aspect of the present invention, the transmission member may be biased to the engagement position. In this case, the engagement state of the transmission member and the interposed member during torque transmission can be maintained more reliably.

In one aspect of the present invention, a gap may be provided between the first intermediate shaft and the interposed member in a radial direction of the first intermediate shaft. The gap may become locally smaller in the axial direction and in the vicinity of the transmission member. In this case, the transmission member can be more smoothly engaged with the interposed member.

In one aspect of the present invention, the intermediate member may be a cylindrical member disposed coaxially with the first intermediate shaft around the first intermediate shaft.

In one aspect of the present invention, the transmission member may be a cylindrical member disposed coaxially with the first intermediate shaft around the first intermediate shaft.

In one aspect of the present invention, the motion conversion member may be supported by the movable support so as to be rotatable about the axis of the first intermediate shaft. The interposed member may be supported by the motion conversion member so as to be movable in the axial direction relative to the motion conversion member.

In one aspect of the present invention, the motion conversion member may include a rotating body and a swing member. The rotating body may be supported by the movable support so as to be rotatable about the axis, and spline-engaged with the interposed member. The swing member may be rotatably mounted on an outer periphery of the rotating body, and configured to swing in accordance with rotation of the rotating body.

In one aspect of the present invention, the transmission member and the interposed member may constitute a first clutch mechanism configured to transmit or cut off power for hammer actuation. The drive mechanism may be configured to transmit power for the drill operation from the first intermediate shaft or a second intermediate shaft provided separately from the first intermediate shaft to the final output shaft. The hammer drill may further include a second clutch mechanism provided on the first intermediate shaft or the second intermediate shaft and configured to transmit or cut off power for the drill operation. In this case, the power for the hammer operation and the power for the drill operation can be cut off by using the first clutch mechanism and the second clutch mechanism, respectively, as necessary.

In one aspect of the present invention, the hammer drill may further include an operation member for switching an operation mode of the hammer drill. The operation member may be configured to be manually operated by a user. Further, the first clutch mechanism and the second clutch mechanism may each be configured to be switched between the power transmission state and the cut-off state in response to an operation of the operating member. In this case, the user can operate the first clutch mechanism and the second clutch mechanism by operating a single operation member and switching the operation mode according to a desired task.

The first intermediate shaft may be configured to transmit only the hammer motion for performing the hammer motion and the drill motion. The second intermediate shaft may be configured to transmit only the drill motion for performing the hammer motion and the drill motion. That is, the first and second countershafts may be specialized for power transmission for hammer action and power transmission for drill action, respectively. Also, the second clutch mechanism may be provided to the second intermediate shaft. In this case, the power transmission from the first intermediate shaft to the first drive mechanism and the power transmission from the second intermediate shaft to the second drive mechanism can be optimized, and the power transmission to the final output shaft can be optimized.

The first intermediate shaft "performs only transmission for executing the hammer action" means that transmission for executing the drill action is not performed, and transmission for the purpose of executing actions other than the drill action is not excluded. Similarly, the meaning of the second intermediate shaft "performing only transmission for performing the drill action" means that transmission for performing the hammer action is not performed, and does not exclude transmission for the purpose of performing actions other than the hammer action.

In one aspect of the present invention, the hammer drill may further include at least one guide shaft extending in parallel with the drive axis in the housing. The at least one guide shaft may be inserted through at least one support hole provided in the movable support and configured to guide relative movement of the movable support in the axial direction.

Drawings

FIG. 1 is a cross-sectional view of a hammer drill.

Fig. 2 is a partially enlarged view of the hammer drill.

FIG. 3 is a cross-sectional view II-II of FIG. 2.

Fig. 4 is a cross-sectional view of a modified example of the bearing support body.

Fig. 5 is a cross-sectional view of V-V of fig. 2.

Fig. 6 is a cross-sectional view of VI-VI of fig. 5.

Fig. 7 is a cross-sectional view of VI I-VI I of fig. 5.

FIG. 8 is a cross-sectional view of VI I-VI I of FIG. 5.

Fig. 9 is a partially enlarged view of fig. 7.

Fig. 10 is a partially enlarged view of fig. 8.

Fig. 11 is a diagram corresponding to fig. 10 and illustrating an operation of the torque limiter.

Fig. 12 is a partial bottom view of the hammer drill with the front housing removed, and shows the mode switching mechanism when the hammer drill mode is selected.

Fig. 13 is a diagram showing the mode switching mechanism when the hammer mode is selected.

Fig. 14 is a diagram showing the mode switching mechanism when the drill mode is selected.

FIG. 15 is a cross-sectional view of XV-XV of FIG. 5.

Fig. 16 is a cross-sectional view of XVI-XVI of fig. 5.

Fig. 17 is a cross-sectional view of XVI-XVI of fig. 5.

Fig. 18 is an explanatory diagram of a method of determining the reference guide axis.

Fig. 19 is an explanatory view of the assembly of the lock plate.

Fig. 20 is an explanatory view of the assembly of the lock plate.

Fig. 21 is an explanatory view of the assembly of the lock plate.

Fig. 22 is a partially enlarged view of fig. 7.

Fig. 23 is a view corresponding to fig. 22 and illustrating an operation of the air-raid preventing mechanism.

Fig. 24 is an explanatory diagram of a modification of the cushion ring.

Fig. 25 is an explanatory diagram of a modification of the cushion ring.

Fig. 26 is an explanatory diagram of a modification of the cushion ring.

Fig. 27 is an explanatory diagram of a modification of the cushion ring.

[ description of reference numerals ]

101, a hammer drill; 10: a main body case; 11: a rear housing; 13: a front housing; 131: a barrel portion; 133: a shoulder portion; 137: a rib; 138: a recess; 15: a bearing support body; 151: an O-shaped ring; 152: an elastomer; 153: an exhaust hole; 154: a filter; 155: a protrusion; 157: a protrusion; 17: a handle; 171: a trigger; 172: a switch; 179: a power line; 18: a movable support; 180: a movable unit; 181: a first shaft penetration insertion part; 182: a second shaft through insertion part; 183: a cylindrical portion; 184: a bearing; 185: a spindle support; 187: a rotating body support portion; 190: a support hole; 191: a first guide shaft; 192: a second guide shaft; 194: a first force application spring; 195: a second force application spring; 197: a buffer member; 2: a motor; 20: a main body portion; 25: a motor shaft; 251: a bearing; 252: a bearing; 255: a pinion gear; 27: a fan; 30: a runaway prevention mechanism; 31: a main shaft; 316: a bearing; 317: a bearing; 32: a tool holder; 321: a small diameter part; 322: a first shoulder; 323: a rear surface; 325: a large diameter portion; 326: a second shoulder; 329: a maximum diameter part; 33: a cylinder; 330: a drill bit is inserted into the hole; 34: a catcher; 341: a catching ring; 343: a ring holding portion; 345: a retainer ring; 35: confinement ring, 36: a guide sleeve; 360: a guide section; 361: a small diameter part; 363: a large diameter portion; 364: a front surface; 37. 371, 372: a buffer ring; 373: an O-shaped ring; 38: a buffer ring; 39: oil sealing; 41: a first intermediate shaft; 411: a bearing; 412: a bearing; 414: a first driven gear; 416: a spline section; 417: a large diameter portion; 42: a second intermediate shaft; 421: a bearing; 422: a bearing; 423: a gear component; 424: a second driven gear; 425: a spline section; 426: a groove; 45: a locking plate; 451: a spring receiving part; 453: an abutting portion; 455: a locking part; 46: a force application spring; 5: a drive mechanism; 6: an impact mechanism; 61: a motion conversion member; 611: a rotating body; 612: a spline section; 614: a bearing; 616: a swinging member; 617: an arm portion; 62: a first clutch mechanism; 63: a clamping member; 631: a spline section; 64: a first transfer member; 641: a first spline section; 642: a second spline portion; 645: a groove; 65: a piston; 67: a ram; 671: a main body portion; 672: a small diameter part; 673: a flange portion; 68: an impact bolt; 681: a large diameter portion; 683: a small diameter part; 684: a small diameter part; 7: a rotation transmission mechanism; 71: a second clutch mechanism; 72: a second transmission member; 721: a first spline section; 722: a second spline portion; 725: a groove; 727: a recess; 73: a torque limiter; 74: a drive side member; 742: a cam recess; 743: a spline section; 75: a driven-side member; 751: a groove; 752: a cam protrusion; 76: a ball bearing; 77: a force application spring; 78: a drive gear; 79: a driven gear; 80: a mode switching mechanism; 800: a mode switching dial; 801: an operation section; 803: a first pin; 805: a second pin; 81: a first switching member; 813: a first engaging portion; 82: a second switching member; 823: a second engaging portion; 83: a first spring; 84: a second spring; 88: a support shaft; 881: a retainer ring; 91: a tip tool; a1: a drive axis; a2: a rotation axis; a3: a rotation axis; a4: an axis of rotation.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, thehammer drill 101 is illustrated as an example of an impact tool. Thehammer drill 101 is a hand-held electric tool used for machining operations such as chipping and drilling operations, and is configured to be capable of performing an operation of linearly driving thetip tool 91 along a predetermined drive axis a1 (hereinafter referred to as a hammer operation) and an operation of rotationally driving thetip tool 91 about a drive axis a1 (hereinafter referred to as a drilling operation).

First, a schematic configuration of thehammer drill 101 will be briefly described with reference to fig. 1. As shown in fig. 1, the outer contour of thehammer drill 101 is mainly formed by thebody housing 10 and thehandle 17 coupled to thebody housing 10.

Themain body case 10 is a hollow body also called a tool main body or an outer shell case, and houses thespindle 31, themotor 2, thedrive mechanism 5, and the like. Thespindle 31 is a long cylindrical member, and has atool holder 32 detachably holding atip tool 91 at one end portion in the axial direction. The long axis of thespindle 31 defines a drive axis a1 of thetip tool 91. Themain body case 10 extends along a drive axis a 1. Thetool holder 32 is disposed in one end portion of themain body case 10 in the extending direction of the drive axis a1 (hereinafter, simply referred to as the drive axis direction).

Thehandle 17 is an elongated hollow body for a user to hold. One end portion in the axial direction of thehandle 17 is coupled to the other end portion (the end portion on the side opposite to the side on which thetool holder 32 is disposed) in the driving axis direction of themain body case 10. Thehandle 17 extends in a direction (more specifically, a direction substantially perpendicular to) intersecting the drive axis a1 so as to protrude from the other end of themain body case 10. In the present embodiment, themain body case 10 and thehandle 17 are integrated by coupling a plurality of components with screws or the like. Apower cord 179 is extended from the protruding end of thehandle 17 to be connectable to an external ac power source. Thehandle 17 includes atrigger 171 that is pushed (pulled) by a user, and aswitch 172 that is turned on in response to the pushing operation of thetrigger 171.

In thehammer drill 101, when theswitch 172 is in the on state, themotor 2 is energized, and thedrive mechanism 5 is driven, thereby performing the hammer operation and/or the drill operation.

The detailed structure of thehammer drill 101 will be described below. In the following description, for convenience, the extending direction of the drive axis a1 (the longitudinal direction of the body case 10) is defined as the front-rear direction of thehammer drill 101. In the front-rear direction, the one end side on which thetool holder 32 is disposed is defined as the front side of thehammer drill 101, and the opposite side (the side to which thehandle 17 is connected) is defined as the rear side. The direction perpendicular to the drive axis a1 and corresponding to the axial direction of thehandle 17 is defined as the vertical direction of thehammer drill 101. In the vertical direction, the side of themain body case 10 to which thehandle 17 is connected is defined as an upper side, and the projecting end side of thehandle 17 is defined as a lower side. In addition, a direction orthogonal to the front-rear direction and the up-down direction is defined as a left-right direction.

First, the structure of themain body case 10 will be described.

As shown in fig. 1, themain body case 10 has a cylindrical front end portion. This cylindrical portion is referred to as acylinder 131. Themain body case 10 is formed in a substantially rectangular box shape except for thecylindrical portion 131. An assist grip (not shown) can be attached to thetube 131. In addition to thegrip 17, the user can also assist in gripping thecylindrical portion 131 to which the assist grip is not attached.

The internal space of themain body case 10 is divided into two regions by abearing support body 15 disposed inside themain body case 10. Thebearing support body 15 is disposed so as to intersect the drive axis a1, is fitted into the inner periphery of themain body case 10, and is held in a fixed state (immovable with respect to the main body case 10) by themain body case 10. The rear region of thebearing support body 15 is mainly a region for accommodating themotor 2. The front region of thebearing support body 15 is mainly a region for accommodating themain shaft 31 and thedrive mechanism 5. Hereinafter, a portion of themain body case 10 corresponding to the housing area of themotor 2 is referred to as arear case 11, and a portion of themain body case 10 corresponding to the housing area of themain shaft 31 and the drive mechanism 5 (including the cylindrical portion 131) is referred to as afront case 13.

Therear case 11 and thefront case 13 are both made of resin (plastic). Therear housing 11 is formed by coupling a plurality of members. On the other hand, thefront housing 13 is a single cylindrical member.

In the present embodiment, thebearing support body 15 is also formed of resin (plastic). This is because the vibration-proof structure described later suppresses transmission of vibration generated by thedrive mechanism 5 to themain body case 10 and thebearing support body 15 fixedly attached to themain body case 10, and therefore thebearing support body 15 is not required to have strength of a metal level. Accordingly, the weight of thehammer drill 101 can be reduced as compared with the case where thebearing support body 15 is formed of metal. As shown in fig. 2, thebearing support body 15 is fitted into the rear end portion of thefront housing 13 so that substantially the entire outer peripheral surface thereof comes into contact with the inner peripheral surface of thefront housing 13.

As will be described in detail later, thebearing support body 15 is a member that supports bearings of various shafts. Therefore, high accuracy is required for the dimension of the outer periphery fitted into themain body case 10. Therefore, when such abearing support body 15 is formed of metal (for example, aluminum alloy), it is preferable to perform machining on a single circle basis for dimensional accuracy. In contrast, in the present embodiment, thebearing support body 15 is formed of resin, thereby increasing the degree of freedom in shape. Specifically, as shown in fig. 3, the sectional shape of thebearing support body 15 in a plane orthogonal to the drive axis a1 is not based on a single circle, but is based on three circles. Therefore, the outer periphery of the bearing support body 15 (i.e., the contact portion with the main body case 10) is not on the circumference of a single circle, but a part of the outer periphery of thebearing support body 15 is overlapped on each of the three circles.

As shown in fig. 2, an annular groove is formed in the outer peripheral surface of the bearingsupport 15 that contacts the inner peripheral surface of themain body housing 10. A rubber O-ring 151 is fitted in the groove. The lubricant is provided in thefront housing 13 that houses thedrive mechanism 5. The O-ring 151 functions as a sealing member that closes the gap between themain body housing 10 and thebearing support body 15, and can prevent the lubricant from leaking into therear housing 11 through the gap between themain body housing 10 and thebearing support body 15. As the sealing member, for example, as shown in fig. 4, instead of the O-ring 151 disposed separately from thebearing support body 15, anelastic body 152 made of a thermoplastic elastomer may be integrally molded on the outer periphery of the resinbearing support body 15. In this case, thebearing support body 15 with theelastic body 152 can be easily assembled to themain body case 10.

As shown in fig. 3 and 5, bearingsupport body 15 is provided with agas discharge hole 153 that communicates the internal space offront housing 13 with the internal space ofrear housing 11 in order to adjust the pressure infront housing 13 to match the pressure inrear housing 11. Afilter 154 is fitted into theexhaust hole 153, and thefilter 154 prevents the lubricant from leaking into therear case 11 through the exhaust hole 153 (see fig. 17).

The internal structure of themain body case 10 will be described below.

First, themotor 2 will be explained. In the present embodiment, an ac motor driven by electric power supplied from an external ac power supply is used as themotor 2. As shown in fig. 1, themotor 2 has amain body portion 20 and amotor shaft 25, wherein themain body portion 20 includes a stator and a rotor; themotor shaft 25 is configured to rotate integrally with the rotor. The stator is fixed to therear housing 11 by screws. In the present embodiment, the rotation axis a2 of themotor shaft 25 extends in parallel with the drive axis a1 at a position lower than the drive axis a 1. A virtual plane VP (hereinafter, referred to as a reference plane VP) (see fig. 3 and 5) including the drive axis a1 and the rotation axis a2 extends in the vertical direction of thehammer drill 101.

Themotor shaft 25 is supported by themain body case 10 via twobearings 251 and 252 so as to be rotatable about a rotation axis a2 with respect to themain body case 10. Thefront bearing 251 is held on the rear surface side of thebearing support body 15, and therear bearing 252 is held by the rear housing 11 (specifically, an inner housing that accommodates themotor 2 in the rear housing 11). Afan 27 for cooling themotor 2 is fixed to a portion of themotor shaft 25 between themain body 20 and thefront bearing 251. The front end of themotor shaft 25 penetrates thebearing support body 15 and protrudes into thefront housing 13. Apinion 255 is fixed to the portion protruding into thefront housing 13.

Next, a power transmission path from themotor shaft 25 to thedrive mechanism 5 will be described.

As shown in fig. 5 and 6, in the present embodiment, thehammer drill 101 has two intermediate shafts (the firstintermediate shaft 41 and the second intermediate shaft 42). Thedrive mechanism 5 is configured to perform a hammer operation by the power transmitted from the firstintermediate shaft 41 and a drill operation by the power transmitted from the secondintermediate shaft 42. That is, the firstintermediate shaft 41 is a shaft dedicated to power transmission for hammer operation. The secondintermediate shaft 42 is a shaft dedicated to power transmission for drill operation.

Both thefirst countershaft 41 and thesecond countershaft 42 extend within thefront housing 13 parallel to the drive axis a1 and the rotational axis a 2. The firstintermediate shaft 41 is supported by themain body case 10 via twobearings 411 and 412 so as to be rotatable about the rotation axis a3 with respect to themain body case 10. Thefront bearing 411 is held by thefront housing 13, and therear bearing 412 is held by the front surface side of thebearing support body 15. Similarly, the secondintermediate shaft 42 is supported by themain body case 10 via twobearings 421 and 422 so as to be rotatable about the rotation axis a4 with respect to themain body case 10. Thefront bearing 421 is held by thefront housing 13, and therear bearing 422 is held by the front surface side of thebearing support body 15. As described above, since the bearing 251 of themotor shaft 25 is also supported by thebearing support body 15, themotor shaft 25, the firstintermediate shaft 41, and the secondintermediate shaft 42 can be arranged with high precision.

The firstintermediate shaft 41 is disposed on the right side with respect to the reference plane VP. Secondintermediate shaft 42 is disposed on the left side with respect to reference plane VP. Accordingly, as compared with the case where the firstintermediate shaft 41 and the secondintermediate shaft 42 are disposed offset to the left or right, a good weight balance in the left-right direction can be achieved.

In addition, on a plane orthogonal to the drive axis a1, an angle formed by a line segment connecting the rotation axis a2 of themotor shaft 25 and the rotation axis A3 of the firstintermediate shaft 41 and a line segment connecting the rotation axis a2 and the rotation axis a4 of the secondintermediate shaft 42 is an obtuse angle.

A first drivengear 414 is fixed to a rear end portion of the firstintermediate shaft 41 adjacent to a front side of thebearing 412. Agear member 423 having a second drivengear 424 is disposed adjacent to the front side of thebearing 422 at the rear end portion of the secondintermediate shaft 42. The first drivengear 414 and the second drivengear 424 are engaged with thepinion 255 of themotor shaft 25. By the above-described arrangement of the rotation axes a2, A3, and a4, the first drivengear 414 and the second drivengear 424 are caused to mesh with thepinion 255 from substantially opposite directions. Therefore, thepinion gear 255 can be restrained from being subjected to a bending load in a specific one direction. In addition, as compared with the case where the first drivengear 414 and the second drivengear 424 are arranged on a straight line with thepinion 255 as the center, it is possible to arrange necessary components reasonably in thefirst countershaft 41 and thesecond countershaft 42 while suppressing an increase in the size of theentire drive mechanism 5 in the straight line direction.

Thegear member 423 is formed in a cylindrical shape and is disposed on the outer peripheral side of the second intermediate shaft 42 (in detail, a drive-side member 74 described later). Further, aspline portion 425 is provided on the outer periphery of the cylindrical front end portion of thegear member 423. Thespline portion 425 has a plurality of splines (external teeth) extending in the direction of the rotation axis a4 (front-rear direction). The rotation of the second driven gear 424 (gear member 423) is transmitted to the secondintermediate shaft 42 via thesecond transmission member 72 and thetorque limiter 73, which will be described later in detail.

As described above, in the present embodiment, two power transmission paths branched from themotor shaft 25 are provided, and these paths are used as a power transmission path dedicated to hammer actuation and a power transmission path dedicated to drill actuation, respectively.

Themain shaft 31 will be explained. Themain shaft 31 is the final output shaft of thehammer drill 101. As shown in fig. 2, thespindle 31 is disposed in thefront housing 13 along the drive axis a1, and is supported by themain body housing 10 so as to be rotatable about the drive axis a1 with respect to themain body housing 10. Themain shaft 31 is configured as an elongated stepped cylindrical member.

The front half of thespindle 31 constitutes atool holder 32 to which thetip tool 91 can be attached and detached. Thetip tool 91 is inserted into thebit insertion hole 330 at the front end of thetool holder 32 so that the long axis thereof coincides with the drive axis a1, and is held in a state of being allowed to move in the axial direction relative to thetool holder 32 and being restricted from rotating about the axis. The rear half of themain shaft 31 constitutes acylinder 33 which slidably holds apiston 65 described later. In the present embodiment, thespindle 31 is a single member in which thetool holder 32 and thecylinder 33 are integrally formed, but may be formed by coupling a plurality of members. Themain shaft 31 is made of iron (or an alloy containing iron as a main component). Themain shaft 31 is supported by abearing 316 held in thecylindrical portion 131 and abearing 317 held by amovable support 18 described later.

Thedriving mechanism 5 will be explained below. As shown in fig. 6 to 8, in the present embodiment, thedrive mechanism 5 includes theimpact mechanism 6 and therotation transmission mechanism 7. Theimpact mechanism 6 is a mechanism for executing a hammer action, and is configured to convert a rotational motion of the firstintermediate shaft 41 into a linear motion and linearly drive thetip tool 91 along the drive axis a 1. Therotation transmission mechanism 7 is a mechanism for executing a drilling operation, and is configured to transmit the rotational motion of the secondintermediate shaft 42 to themain shaft 31 and rotationally drive thetip tool 91 around the drive axis a 1. The details of theimpact mechanism 6 and therotation transmission mechanism 7 will be described in order below.

In the present embodiment, as shown in fig. 6 and 7, theimpact mechanism 6 includes amotion conversion member 61, apiston 65, ahammer 67, and animpact bolt 68.

Themotion conversion member 61 is disposed on the firstintermediate shaft 41, and is configured to convert the rotational motion of the firstintermediate shaft 41 into a linear motion and transmit the linear motion to thepiston 65. In more detail, themotion converting part 61 includes arotating body 611 and a swingingpart 616. Therotating body 611 is supported by themain body case 10 via abearing 614 so as to be rotatable about the rotation axis a3 with respect to themain body case 10. The swingingmember 616 is rotatably attached to the outer periphery of therotating body 611, and configured to swing in the extending direction (front-rear direction) of the rotation axis a3 in accordance with the rotation of therotating body 611. The swingingmember 616 has anarm portion 617 extending upward from therotating body 611.

Thepiston 65 is a bottomed cylindrical member, and is disposed in thecylinder 33 of themain shaft 31 so as to be slidable along the drive axis a 1. Thepiston 65 is coupled to thearm portion 617 of the swingingmember 616 by a coupling pin, and reciprocates in the front-rear direction in accordance with the swinging of the swingingmember 616.

Thehammer 67 is an impact member for applying an impact force to thetip tool 91. Thehammer 67 is disposed in thepiston 65 so as to be slidable along the drive axis a 1. The internal space of thepiston 65 on the rear side of thehammer 67 is defined as an air chamber functioning as an air spring. Theimpact pin 68 is an intermediate member that transmits the kinetic energy of theram 67 to thetip tool 91. Theimpact bolt 68 is disposed on the front side of thehammer 67 so as to be movable along the drive axis a1 in thetool holder 32. In the present embodiment, theimpact bolt 68 is slidably held in the front-rear direction by theguide sleeve 36 and theretainer ring 35 disposed in thetool holder 32.

When thepiston 65 moves in the front-rear direction in accordance with the swing of theswing member 616, the air pressure of the air chamber fluctuates, and theram 67 slides in the front-rear direction in thepiston 65 by the air spring. More specifically, when thepiston 65 moves forward, air in the air chamber is compressed to increase the internal pressure. Theram 67 is pushed forward at high speed by the air spring and strikes theimpact bolt 68. Theimpact bolt 68 transfers the kinetic energy of theram 67 to thetip tool 91. Accordingly, thetip tool 91 is linearly driven along the driving axis a 1. On the other hand, when thepiston 65 moves rearward, air in the air chamber expands to lower the internal pressure, and thehammer 67 is pulled rearward. Thetip tool 91 moves rearward together with theimpact pin 68 by being pressed against the workpiece. In this way, the hammer operation is repeated by theimpact mechanism 6.

In the present embodiment, the rotational motion of the firstintermediate shaft 41 is transmitted to the motion conversion member 61 (specifically, the rotating body 611) via thefirst transmission member 64 and theintermediate member 63. Theintermediate member 63 and thefirst transmission member 64 will be described in order below.

As shown in fig. 6 and 9, the interposedmember 63 is a cylindrical member that is disposed coaxially with the firstintermediate shaft 41 around the firstintermediate shaft 41 and is interposed between the firstintermediate shaft 41 and the motion conversion member 61 (specifically, the rotating body 611). Theintermediate member 63 is immovable in the front-rear direction with respect to the firstintermediate shaft 41, and is rotatable about the rotation axis a3 with respect to the firstintermediate shaft 41.

More specifically, the front end portion of the first intermediate shaft 41 (the portion adjacent to the rear side of the front bearing 411) is configured as a maximum diameter portion having the maximum outer diameter. Aspline portion 416 is provided on the outer periphery of the maximum diameter portion. Thespline portion 416 has a plurality of splines (external teeth) extending in the direction of the rotation axis a3 (front-rear direction). Theintermediate member 63 is held between thespline portion 416 and the first drivengear 414 fixed to the rear end portion of the firstintermediate shaft 41 so as not to be movable in the front-rear direction. Further, a portion of the firstintermediate shaft 41 adjacent to the rear side of thespline portion 416 is configured as alarge diameter portion 417, and thelarge diameter portion 417 has a slightly larger outer diameter than a portion thereof on the rear side.

Further, aspline portion 631 extending over substantially the entire length of theintermediate member 63 is provided on the outer periphery of theintermediate member 63. Thespline portion 631 has a plurality of splines (external teeth) extending in the direction of the rotation axis a3 (front-rear direction). Further, thespline portion 631 of theintermediate member 63 has a diameter larger than that of thespline portion 416 of the firstintermediate shaft 41.

On the other hand, aspline portion 612 is formed on the inner periphery of therotating body 611. Thespline portion 612 has splines (internal teeth) that engage with thespline portion 631. Theintermediate member 63 is always spline-engaged with therotating body 611 and is held by therotating body 611. With such a configuration, therotating body 611 is movable in the direction of the rotation axis a3 (front-rear direction) with respect to theintermediate member 63 and the firstintermediate shaft 41, and is rotatable integrally with theintermediate member 63.

Thefirst transmission member 64 is disposed on the firstintermediate shaft 41, is configured to be rotatable integrally with the firstintermediate shaft 41, and is movable in the direction of the rotation axis a3 (front-rear direction) with respect to the firstintermediate shaft 41 and theintermediate member 63.

More specifically, thefirst transmission member 64 is a substantially cylindrical member disposed around the firstintermediate shaft 41, and thefirst spline portion 641 and thesecond spline portion 642 are provided on the inner periphery of thefirst transmission member 64.

Thefirst spline portion 641 is provided at the rear end portion of thefirst transmission member 64. Thefirst spline portion 641 has a plurality of splines (internal teeth) that can engage with thespline portion 631 of theintermediate member 63. As described above, thespline portion 631 of theintermediate member 63 also engages with thespline portion 612 of therotating body 611. That is, thespline portion 631 is effectively used for engagement with two members, i.e., therotating body 611 and thefirst transmission member 64. Thesecond spline portion 642 is provided at the front half portion of thefirst transfer member 64. Thesecond spline portion 642 has a plurality of splines (internal teeth) that are constantly engaged with thespline portion 416 of the firstintermediate shaft 41.

According to such a configuration, as shown by a solid line in fig. 9, when thefirst spline portion 641 is disposed at a position (hereinafter, referred to as an engagement position) where it engages with thespline portion 631 of theintermediate member 63 in the front-rear direction, thefirst transmission member 64 can rotate integrally with theintermediate member 63, that is, power can be transmitted from the firstintermediate shaft 41 to theintermediate member 63. In the present embodiment, the diameter of thefirst spline portion 641 is larger than the diameter of thesecond spline portion 642. In this way, by forming thefirst spline section 641 to have a large diameter, efficient torque transmission is possible.

On the other hand, as shown by the broken line in fig. 9, when thefirst spline section 641 is disposed at a position (hereinafter referred to as a separation position) separated from (not engageable with) thespline section 631, thefirst transmission member 64 does not transmit (cut) power from the firstintermediate shaft 41 to theintermediate member 63.

The diameter of thelarge diameter portion 417 of the firstintermediate shaft 41 is set to be slightly smaller than the inner diameter of the interposedmember 63. Therefore, the gap between the inner periphery of theintermediate member 63 and the outer periphery of thelarge diameter portion 417 of the firstintermediate shaft 41 is small. Accordingly, when thefirst transmission member 64 moves from the disengaged position to the engaged position, thefirst spline portion 641 and thespline portion 631 can be smoothly engaged with each other. On the other hand, a larger gap is secured between the inner periphery of the interposedmember 63 and the outer periphery of the portion other than thelarge diameter portion 417. Accordingly, when the power transmission from the firstintermediate shaft 41 to theintermediate member 63 is interrupted, the co-rotation of the firstintermediate shaft 41 and theintermediate member 63 can be more reliably suppressed.

As described above, in the present embodiment, thefirst transmission member 64 and the interposedmember 63 function as the firstclutch mechanism 62 that transmits or blocks the power for the hammer operation. In the present embodiment, thefirst transmission member 64 is connected to the mode switching mechanism 80 (see fig. 12), and moves between the engagement position and the disengagement position in response to the user operating the mode switching dial 800 (see fig. 2). That is, the firstclutch mechanism 62 switches between the power transmission state and the cut-off state in response to the operation of themode switching dial 800. Themode switching mechanism 80 will be described in detail later.

As shown in fig. 8, in the present embodiment, therotation transmission mechanism 7 includes adrive gear 78 and a drivengear 79. Thedrive gear 78 is fixed to a front end portion (a portion adjacent to the rear side of the front bearing 421) of the secondintermediate shaft 42. The drivengear 79 is fixed to the outer periphery of thecylinder 33 of themain shaft 31 and meshes with thedrive gear 78. Thedrive gear 78 and the drivengear 79 constitute a gear reduction mechanism. As thedrive gear 78 rotates integrally with thesecond counter shaft 42, themain shaft 31 rotates integrally with the drivengear 79. Accordingly, the drill operation is performed in which thetip end tool 91 held by thetool holder 32 is rotationally driven about the driving axis a 1.

Further, as described above, in the present embodiment, the rotational motion of the second drivengear 424 that rotates with the rotation of themotor shaft 25 is transmitted to the secondintermediate shaft 42 via thesecond transmission member 72 and thetorque limiter 73. Hereinafter, thetorque limiter 73 and thesecond transmission member 72 will be described in order.

As shown in fig. 6 and 10, thetorque limiter 73 is a safety clutch mechanism that is disposed on the secondintermediate shaft 42 and is configured to interrupt transmission when the torque acting on the secondintermediate shaft 42 exceeds a threshold value. In the present embodiment, thetorque limiter 73 includes a driving-side member 74, a driven-side member 75,balls 76, and an urgingspring 77.

Thedrive side member 74 is a cylindrical member that is rotatably supported by the rear half of the secondintermediate shaft 42. The second drivengear 424 is rotatably supported by the rear end portion of the driving-side member 74. Therefore, the drivingside member 74 is able to rotate about the rotation axis a4 with respect to the secondintermediate shaft 42 and the second drivengear 424.

Thedrive side member 74 includes a cam recess 742 (refer to fig. 11) and aspline portion 743. Thecam recess 742 is provided at the front end of the drive-side member 74 and has a cam surface inclined in the circumferential direction. Thespline portion 743 is provided on the outer periphery of the drive-side member 74 on the rear side of thecam recess 742, and has a plurality of splines (external teeth) extending in the direction of the rotation axis a4 (front-rear direction).

Driven-side member 75 is a cylindrical member and is disposed around secondintermediate shaft 42 on the front side of driving-side member 74. A plurality ofgrooves 751 extending in the direction of the rotation axis a4 (front-rear direction) are provided in the circumferential direction on the inner periphery of the driven-side member 75. Further, a plurality ofgrooves 426 extending in the direction of the rotation axis a4 (front-rear direction) are provided in the circumferential direction on the outer periphery of the secondintermediate shaft 42. Theballs 76 are rollably accommodated in a track defined by thegrooves 426 and 751. Accordingly, the drivenmember 75 is engaged with the secondintermediate shaft 42 via theballs 76 in the radial direction and the circumferential direction, and is rotatable integrally with the secondintermediate shaft 42. The driven-side member 75 is movable in the front-rear direction with respect to the secondintermediate shaft 42 within a range in which theballs 76 can roll in the track.

The driven-side member 75 has acam protrusion 752 provided at the rear end (see fig. 11). Thecam protrusion 752 has a shape substantially matching thecam recess 742 of the driving-side member 74, and has a cam surface inclined in the circumferential direction. The biasingspring 77 is a compression coil spring, and is disposed in a compressed state between thedrive gear 78 and the drivenmember 75. Therefore, the biasingspring 77 always biases the drivenmember 75 in a direction approaching the drivingmember 74, that is, in a direction (rearward) in which thecam protrusion 752 meshes with thecam recess 742. When thecam protrusion 752 is engaged with thecam recess 742, torque is transmitted from the driving-side member 74 to the driven-side member 75, and the secondintermediate shaft 42 is allowed to rotate. Further, the drivingside member 74 and thegear member 423 are urged rearward via the drivenside member 75, and are held in the rearmost position relative to the secondintermediate shaft 42.

When a load equal to or greater than a threshold value is applied to the secondintermediate shaft 42 via the tool holder 32 (main shaft 31) due to thetip tool 91 being locked or the like while the secondintermediate shaft 42 is rotating, the engagement between thecam protrusion 752 and thecam recess 742 is released as shown in fig. 11. More specifically, thecam protrusion 752 is disengaged from thecam recess 742 and moved to the front end surface of the driving-side member 74 against the biasing force of the biasingspring 77 by the action of thecam protrusion 752 and the cam surface (inclined surface) of thecam recess 742. That is, the driven-side member 75 moves in a direction (forward) away from the driving-side member 74. At this time, the drivenmember 75 is guided by theballs 76 rolling between the secondintermediate shaft 42 and can smoothly move forward. As a result, torque transmission from driving-side member 74 to driven-side member 75 is interrupted, and rotation of secondintermediate shaft 42 is interrupted.

As shown in fig. 6 and 10, thesecond transmission member 72 is disposed on the secondintermediate shaft 42, is configured to be rotatable integrally with the drive-side member 74 of thetorque limiter 73, and is movable in the direction of the rotation axis line a4 (front-rear direction) with respect to the drive-side member 74 and thegear member 423.

More specifically, thesecond transmission member 72 is a substantially cylindrical member disposed around thedrive side member 74, and thefirst spline portion 721 and thesecond spline portion 722 are provided on the inner periphery of thesecond transmission member 72. Thefirst spline portion 721 is provided at the front half portion of thesecond transmission member 72.First spline portion 721 has a plurality of splines (internal teeth) that are constantly engaged withspline portion 743 of drive-side member 74. Thesecond spline portion 722 is provided at the rear end portion of thesecond transmission member 72 and has a larger inner diameter than thefirst spline portion 721. Thesecond spline portion 722 has a plurality of splines (internal teeth) that can engage with thespline portion 425 of thegear member 423.

According to this configuration, as shown by a solid line in fig. 10, when thesecond spline portion 722 is disposed at a position where it engages with thespline portion 425 of the gear member 423 (hereinafter referred to as an engagement position) in the front-rear direction, thesecond transmission member 72 can rotate integrally with thegear member 423. Therefore, the driving-side member 74 spline-engaged with thesecond transmission member 72 can also rotate integrally with thegear member 423. On the other hand, as shown by the broken line in fig. 10, when thesecond spline portion 722 is disposed at a position (hereinafter referred to as a separation position) where it is separated from (cannot be engaged with) thespline portion 425, thesecond transmission member 72 cannot transmit (cut off) power from thegear member 423 to the drive-side member 74.

As described above, in the present embodiment, thesecond transmission member 72 and thegear member 423 function as the secondclutch mechanism 71 that transmits or cuts off the power for the drill operation. In the present embodiment, thesecond transmission member 72 is connected to the mode switching mechanism 80 (see fig. 12) as in the case of thefirst transmission member 64, and moves between the engagement position and the disengagement position in response to the user's operation of the mode switching dial 800 (see fig. 2). That is, the secondclutch mechanism 71 is also switched between the power transmission state and the cut-off state in response to the operation of themode switching dial 800, as in the case of the firstclutch mechanism 62.

Themode switching dial 800 and themode switching mechanism 80 will be described below.

As shown in fig. 12 to 14, themode switching mechanism 80 is configured to switch the operation mode of thehammer drill 101 in conjunction with themode switching dial 800. In the present embodiment, thehammer drill 101 has three operation modes, i.e., a hammer drill mode, a hammer mode, and a drill mode. The hammer drill mode is an operation mode in which both theimpact mechanism 6 and therotation transmission mechanism 7 are driven to perform a hammer operation and a drill operation. The hammer mode is an operation mode in which the power transmission for the drill operation is cut off by the secondclutch mechanism 71 and only theimpact mechanism 6 is driven, thereby performing only the hammer operation. The drill mode is an operation mode in which only the drill operation is performed by cutting off the power transmission for the hammer operation by the firstclutch mechanism 62 and driving only therotation transmission mechanism 7.

As shown in fig. 2 and 12 to 14, amode switching dial 800 is provided at a lower end portion of the main body housing 10 (specifically, the front housing 13) so as to be externally operable by a user. Themode switching dial 800 includes a disk-shapedoperation portion 801 having a knob, and afirst pin 803 and asecond pin 805 protruding from theoperation portion 801.

Theoperation portion 801 is held by themain body case 10 so as to be rotatable about a rotation axis extending in the vertical direction. A part of theoperation portion 801 is partially exposed to the outside through an opening formed in the lower wall of the main body case 10 (front case 13), and can be rotated by the user. In addition, themode switching dial 800 defines rotational positions corresponding to the hammer drill mode, the hammer mode, and the drill mode, respectively. The user can set the operation mode by disposing themode switching dial 800 at a rotational position corresponding to a desired operation mode. Thefirst pin 803 and thesecond pin 805 protrude upward from the upper surface of theoperation portion 801. Thefirst pin 803 and thesecond pin 805 move on a circle centered on the rotational axis of theoperation portion 801 as themode switching dial 800 rotates.

Themode switching mechanism 80 includes afirst switching member 81, asecond switching member 82, afirst spring 83, and asecond spring 84.

Thefirst switching member 81 has a pair of support holes (not shown) and is supported by asupport shaft 88 inserted through the support holes so as to be movable in the front-rear direction. Thesupport shaft 88 is a shaft fixed to thebearing support 15 and protruding forward from the bearingsupport 15. Thesupport shaft 88 extends in parallel with the firstintermediate shaft 41 and the secondintermediate shaft 42. Aretainer ring 881 is fixed to a central portion of thesupport shaft 88 in the axial direction. Thefirst switching member 81 is supported on the front side of theretainer 881. Thesecond switching member 82 has a pair of support holes (not shown), and is supported by asupport shaft 88 inserted through the support holes so as to be movable in the front-rear direction on the rear side of theretainer 881.

Thefirst switching member 81 and thesecond switching member 82 are engaged with thefirst transmission member 64 and thesecond transmission member 72, respectively. In more detail,annular grooves 645 and 725 are provided on the outer peripheries of thefirst transmission member 64 and thesecond transmission member 72, respectively. Thefirst switching member 81 is engaged with thefirst transmission member 64 via a plate-like first engaging portion 813 (see fig. 14) disposed in thegroove 645. Similarly, thesecond switching member 82 is engaged with thesecond transmission member 72 via a plate-like second engagement portion 823 (see fig. 10) disposed in thegroove 725. Further, thefirst transmission member 64 and thesecond transmission member 72 are rotatable with respect to the first switchingmember 81 and thesecond switching member 82, respectively, in a state where thefirst engagement portion 813 and thesecond engagement portion 823 are engaged with thegrooves 645 and 725, respectively.

Thefirst spring 83 is a compression coil spring, is disposed in a compressed state between thefront housing 13 and the first switchingmember 81, and constantly biases the first switchingmember 81 rearward. Accordingly, thefirst transmission member 64 engaged with the first switchingmember 81 is also always biased to the rearward engagement position. Thesecond spring 84 is a compression coil spring, is disposed in a compressed state between theretainer 881 fixed to thesupport shaft 88 and thesecond switching member 82, and constantly biases thesecond switching member 82 rearward. Accordingly, thesecond transmission member 72 engaged with thesecond switching member 82 is also always biased to the rearward engagement position. The rearmost position of the first switchingmember 81 is a position where the first switchingmember 81 abuts against thestopper 881. The rearmost position of thesecond switching member 82 is a position where thesecond switching member 82 abuts against the front surface of thebearing support body 15.

When themode switching dial 800 is disposed at a rotational position (hereinafter referred to as a hammer drill position) corresponding to the hammer drill mode shown in fig. 12, thefirst pin 803 is disposed at a position adjacent to the rear of the first switchingmember 81 disposed at the rearmost position, and thesecond pin 805 is disposed at a position adjacent to the rear of thesecond switching member 82 disposed at the rearmost position. At this time, thefirst transmission member 64 is disposed at an engagement position (see fig. 9) where thesecond spline portion 642 engages with thespline portion 631 of theintermediate member 63, and the firstclutch mechanism 62 is in a power transmission state. Thesecond transmission member 72 is disposed at an engagement position (see fig. 10) where thesecond spline portion 722 engages with thespline portion 425 of thegear member 423, and the secondclutch mechanism 71 is also in a power transmission state.

When themotor 2 is energized, power is transmitted from themotor shaft 25 to theimpact mechanism 6 via the firstintermediate shaft 41, and the hammer action is performed. At the same time, power is transmitted from themotor shaft 25 to therotation transmission mechanism 7 via the secondintermediate shaft 42, and the drill operation is also performed.

When themode switching dial 800 is rotationally operated from the hammer drill position shown in fig. 12 to a rotational position (hereinafter referred to as a hammer position) corresponding to the hammer mode shown in fig. 13, thesecond pin 805 moves clockwise while abutting against thesecond switching member 82 from behind, and moves thesecond switching member 82 forward against the biasing force of thesecond spring 84. When themode switching dial 800 is disposed at the hammer position, thesecond switching member 82 is disposed at the foremost position. As thesecond switching member 82 moves, thesecond transmission member 72 moves from the engagement position to the disengagement position (see fig. 10), and the secondclutch mechanism 71 is switched to the disengaged state.

On the other hand, thefirst pin 803 moves in the clockwise direction in a bottom view without interfering with the first switchingmember 81 and thesecond switching member 82, and is disposed at a position away from the first switchingmember 81 and thesecond switching member 82. Therefore, during this time, the first switchingmember 81 and the first transmittingmember 64 do not move, and the firstclutch mechanism 62 maintains the power transmitting state unchanged.

Even if themotor 2 is energized, no power is transmitted from themotor shaft 25 to the secondintermediate shaft 42, and therefore, the drilling operation is not performed. On the other hand, since power is transmitted from themotor shaft 25 to theimpact mechanism 6 via the firstintermediate shaft 41, only the hammer action is performed.

When themode switching dial 800 is rotationally operated from the hammer drill position shown in fig. 12 to a rotational position (hereinafter referred to as a drill position) corresponding to the drill mode shown in fig. 14, thefirst pin 803 abuts against the first switchingmember 81 from behind, and moves counterclockwise about the rotational axis of theoperation portion 801 in a bottom view, while moving the first switchingmember 81 forward against the urging force of thefirst spring 83. When themode switching dial 800 is disposed at the drill position, the first switchingmember 81 is disposed at the forefront position. As the first switchingmember 81 moves, thefirst transmission member 64 moves from the engagement position to the disengagement position (see fig. 9), and the firstclutch mechanism 62 is switched to the disengagement state.

On the other hand, thesecond pin 805 does not interfere with the first switchingmember 81 nor with thesecond switching member 82, and is disposed adjacent to thesecond switching member 82 while moving counterclockwise about the rotational axis of the operatingportion 801 in a bottom view. Therefore, during this time, thesecond switching member 82 and thesecond transmission member 72 do not move, and the secondclutch mechanism 71 maintains the power transmission state.

Even if themotor 2 is energized, no power is transmitted from the firstintermediate shaft 41 to themotion conversion member 61, and therefore, the hammer action is not performed. On the other hand, since power is transmitted from themotor shaft 25 to therotation transmission mechanism 7 via the secondintermediate shaft 42, only the drill operation is executed.

As described above, thehammer drill 101 of the present embodiment has two independent intermediate shafts (the firstintermediate shaft 41 and the second intermediate shaft 42) that extend parallel to the drive axis a1 and that respectively transmit power for the hammer action and the drill action. Therefore, the firstintermediate shaft 41 and the secondintermediate shaft 42 can be shortened as compared with the case where a single common intermediate shaft is used for power transmission for the hammer action and the drill action. This makes it possible to shorten theentire hammer drill 101 in the drive axis direction. Further, by shortening the firstintermediate shaft 41 and the secondintermediate shaft 42, the center of gravity of thehammer drill 101 can be brought close to thehand grip 17 coupled to the rear end portion of themain body case 10, and operability can be improved.

Also, the firstintermediate shaft 41 and the secondintermediate shaft 42 are specialized for power transmission for hammer action and power transmission for drill action, respectively. That is, the power transmission path dedicated to the hammer action and the power transmission path dedicated to the drill action are not provided in series but in parallel. Therefore, the power transmission from the firstintermediate shaft 41 to theimpact mechanism 6 and the power transmission from the secondintermediate shaft 42 to therotation transmission mechanism 7 can be optimized, and the power transmission to themain shaft 31 as the final output shaft can be optimized.

Further, since themotion conversion member 61 is mounted on the firstintermediate shaft 41 dedicated to the hammer operation, it is necessary to have a certain length. In contrast, thedrive gear 78 mounted on the secondintermediate shaft 42 dedicated to the drilling operation does not need to have such a long length. Therefore, in the present embodiment, thetorque limiter 73 is disposed so as to effectively utilize the space generated in the secondintermediate shaft 42. The secondintermediate shaft 42 has a lower transmission torque than themain shaft 31 as the final output shaft. Therefore, thetorque limiter 73 can be smaller and lighter than the torque limiter mounted on themain shaft 31. Further, in thetorque limiter 73 of the present embodiment, when thetorque limiter 73 is operated, the driven-side member 75 can be guided in the direction of the rotation axis a4 while theballs 76 roll. This reduces friction between the drivenmember 75 and the secondintermediate shaft 42, thereby stabilizing the operating torque.

In the present embodiment, the firstclutch mechanism 62 and the secondclutch mechanism 71 are provided on the firstintermediate shaft 41 and the secondintermediate shaft 42, respectively. Therefore, the power for the hammer action and the power for the drill action can be cut off separately as needed. Also, the firstclutch mechanism 62 and the secondclutch mechanism 71 are each switched between the power transmission state and the cut-off state in response to an operation of the same operation member (mode switching dial 800). Therefore, the user can operate the firstclutch mechanism 62 and the secondclutch mechanism 71 by operating themode switching dial 800 to switch the operation mode in accordance with a desired operation.

As shown in fig. 6 and 12 to 14, thehammer drill 101 is provided with alock plate 45, and thelock plate 45 is configured to restrict rotation of the secondintermediate shaft 42 in the hammer mode. This is to prevent thetip end tool 91 held to thetool holder 32 from freely rotating during the hammer action.

Thelock plate 45 is configured to engage with thesecond transmission member 72 disposed at the separated position, and to restrict the rotation of thesecond transmission member 72. Thelock plate 45 is a metal elongated member. Thelock plate 45 is held slidably in the front-rear direction by a rib 137 (only a part of which is shown in fig. 5 and 19 to 21) provided in thefront housing 13 in a state biased rearward by the biasingspring 46. The biasingspring 46 is a compression coil spring, and the tip end portion thereof is disposed in a recess 138 (see fig. 19 to 21) provided in thefront housing 13.

Thelock plate 45 includes aspring receiving portion 451, an abuttingportion 453, and an engagingportion 455. Thespring receiving portion 451 is a projection provided at the front end portion of thelock plate 45, and is inserted into the rear end portion of the biasingspring 46. Theabutment portion 453 extends rearward along the inner peripheral surface of thefront housing 13 on the radially outer side of thetorque limiter 73 and thesecond transmission member 72. Thelock plate 45 is biased rearward by the biasingspring 46, and the rear end surface of the abuttingportion 453 is held at a position (initial position) abutting against the front end surface of theprojection 157 projecting forward from the front surface of the bearingsupport 15. The lockingportion 455 is a substantially rectangular portion disposed on the front side of thesecond transmission member 72. On the other hand, a plurality ofconcave portions 727 are provided at the distal end portion of thesecond transmission member 72. Theconcave portions 727 are substantially rectangular concave portions recessed rearward from the front end of thesecond transmission member 72, and are provided at equal intervals in the circumferential direction.

As described above, thesecond transmission member 72 is disposed at the engagement position in the hammer mode and the drill mode. At this time, as shown in fig. 12 and 14, the lockingportion 455 of thelock plate 45 is positioned at a position away forward from thesecond transmission member 72. Therefore, thesecond transmission member 72 can rotate together with the first drivengear 414 without being interfered by thelock plate 45.

On the other hand, as shown in fig. 13, in the hammer mode, thesecond transmission member 72 is disposed at the spaced position forward of the engaged position, and the lockingportion 455 of thelock plate 45 is engaged with one of the plurality ofconcave portions 727 of thesecond transmission member 72. Accordingly, since the rotation of thesecond transmission member 72 is restricted, the rotation of the driving-side member 74, the driven-side member 75, and the secondintermediate shaft 42 is also restricted. Further, the rotation of themain shaft 31 via thedrive gear 78 and the drivengear 79 is also restricted.

Further, when the lockingportion 455 does not face therecess 727 in the process of moving thesecond transmission member 72 from the engagement position to the disengagement position, the front end surface of thesecond transmission member 72 abuts against the lockingportion 455, and thelock plate 45 is moved forward against the biasing force of the biasingspring 46. Then, when thetip tool 91 is rotated and thesecond transmission member 72 is rotated to a position where the lockingportion 455 faces therecess 727 via thespindle 31 and the secondintermediate shaft 42, thelock plate 45 is urged by the urgingspring 46 to move rearward, and the lockingportion 455 engages with therecess 727.

In the present embodiment, thehammer drill 101 is configured to suppress transmission of vibration (particularly, vibration in the drive axis direction (front-rear direction)) generated as thedrive mechanism 5 is driven to thebody case 10 and thehandle 17. Hereinafter, a vibration-proof structure of thehammer drill 101 will be described.

In the present embodiment, as shown in fig. 2, themain shaft 31 and the impact mechanism 6 (specifically, themotion conversion member 61, thepiston 65, thehammer 67, and the impact bolt 68) are disposed inside themain body case 10 so as to be movable in the drive axis direction (front-rear direction) with respect to themain body case 10. More specifically, themovable support 18 is disposed inside themain body case 10, and themovable support 18 is movable in the front-rear direction with respect to themain body case 10 in a state of being biased forward with respect to themain body case 10. Themain shaft 31 and theimpact mechanism 6 are supported by themovable support 18 and are movable integrally with themovable support 18 relative to themain body case 10.

As shown in fig. 5, 7, 15, and 16, themovable support 18 includes aspindle support portion 185, arotor support portion 187, a firstshaft insertion portion 181, and a secondshaft insertion portion 182. In the present embodiment, themovable support 18 is formed as a single member made of metal.

Thespindle support portion 185 is formed in a substantially cylindrical shape and configured to support a portion of thespindle 31. Abearing 317 is held inside thespindle support 185. Thespindle support portion 185 supports the rear portion of thecylinder 33 via abearing 317 so as to be rotatable about a drive axis a 1. Further, as described above, themain shaft 31 is supported by thebearing 316 and thebearing 317 so as to be rotatable about the drive axis a1 with respect to themain body case 10. Theother bearing 316 is held in thecylinder 131, and supports the rear portion of thetool holder 32 so as to be rotatable about the drive axis a1 and movable in the front-rear direction.

Therotor support portion 187 is a portion formed in a substantially cylindrical shape, and is connected to a lower portion of the right end portion of thespindle support portion 185. Abearing 614 is fixed to therotor support 187 by a screw. The rotatingbody support portion 187 supports therotating body 611 via thebearing 614 so as to be rotatable about the rotation axis a 3.

As described above, by supporting themain shaft 31 and therotating body 611 by themovable support 18, theswing member 616 attached to therotating body 611, thepiston 65 disposed in themain shaft 31, thehammer 67, and theimpact bolt 68 are also supported by themovable support 18. Therefore, themovable support 18, themain shaft 31, and theimpact mechanism 6 constitute amovable unit 180 as a component that is integrally movable in the front-rear direction with respect to themain body case 10.

The firstshaft insertion portion 181 and the secondshaft insertion portion 182 are disposed on the right and left sides of thespindle support portion 185, respectively, symmetrically with respect to the reference plane VP. The firstshaft insertion portion 181 has a pair ofcylindrical portions 183. The pair ofcylindrical portions 183 are provided on the same shaft so as to be separated in the front-rear direction. Abearing 184 is fitted into eachcylindrical portion 183. In the present embodiment, a cylindrical oilless bearing is used as thebearing 184. The secondshaft insertion portion 182 has the same structure as the firstshaft insertion portion 181. That is, the secondshaft insertion portion 182 has a pair ofcylindrical portions 183 to whichbearings 184 are fixed.

As shown in fig. 5 and 15, the movable support 18 (movable unit 180) is supported by themain body case 10 by thefirst guide shaft 191 and thesecond guide shaft 192 so as to be movable in the front-rear direction with respect to themain body case 10. Thefirst guide rail 191 and thesecond guide rail 192 are disposed symmetrically with respect to the reference plane VP, and extend parallel to the drive axis a1 (in the front-rear direction) in the upper portion of thefront housing 13. Thefirst guide shaft 191 and thesecond guide shaft 192 have their respective front end portions fixedly held by thefront housing 13 and their rear end portions fixedly held by the bearingsupport 15. Therefore, the first andsecond guide shafts 191 and 192 cannot move relative to themain body housing 10.

In the present embodiment, thefirst guide shaft 191 and thesecond guide shaft 192 are each formed of iron (or an alloy containing iron as a main component). Thefirst guide shaft 191 and thesecond guide shaft 192 are slidably inserted through a pair of front andrear bearings 184 of the firstshaft insertion portion 181 and the secondshaft insertion portion 182, respectively. That is, the inner peripheral surface of thebearing 184 defines the support holes 190 of thefirst guide shaft 191 and thesecond guide shaft 192. With such a configuration, the movable support 18 (movable unit 180) can be moved in the front-rear direction with respect to themain body housing 10 while being guided by thefirst guide shaft 191 and thesecond guide shaft 192.

In addition, as described above, the firstintermediate shaft 41 for hammer action and the secondintermediate shaft 42 for drill action are supported by thebearings 411 and 421 held in thefront housing 13 and thebearings 412 and 422 held in thebearing support body 15, respectively, so as not to be movable in the front-rear direction with respect to themain body housing 10. Therefore, the movable support 18 (movable unit 180) is also movable in the front-rear direction with respect to the firstintermediate shaft 41 and the secondintermediate shaft 42.

In the present embodiment, themovable support 18 supports themain shaft 31 and theimpact mechanism 6 and receives a load during the hammer operation, and therefore is formed of an aluminum alloy or a magnesium alloy in order to achieve both strength and weight reduction. On the other hand, the bearing 184 that slides on thefirst guide shaft 191 and thesecond guide shaft 192 is formed of a material that is more excellent in lubrication than themovable support 18. Further, the portions of themovable support 18 that define the support holes 190 of thefirst guide shaft 191 and the second guide shaft 192 (i.e., the portions that slide on thefirst guide shaft 191 and the second guide shaft 192) need not be thebearings 184. For example, only the cylindrical portion defining thesupport hole 190 may be formed integrally with the other portion of themovable support 18, and may be made of a material different from the other portion (for example, iron or an alloy containing iron as a main component).

Afirst biasing spring 194 and asecond biasing spring 195 are disposed behind the firstshaft insertion portion 181 and the secondshaft insertion portion 182, respectively. Thefirst urging spring 194 and thesecond urging spring 195 are both compression coil springs, are externally fitted to thefirst guide shaft 191 and thesecond guide shaft 192, respectively, and are disposed in a compressed state between themovable support 18 and the bearingsupport 15. More specifically, the front end of thefirst biasing spring 194 abuts against the rear end of thecylindrical portion 183 on the rear side of the first throughhole 181 via a washer. The rear end of thefirst biasing spring 194 is fitted into a spring receiving portion provided on the front surface of thebearing support body 15. Similarly, the front end of thesecond biasing spring 195 abuts against the rear end of thecylindrical portion 183 on the rear side of the secondshaft insertion portion 182 via a washer. The rear end of thesecond biasing spring 195 is fitted into a spring receiving portion provided on the front surface of thebearing support body 15.

With such a configuration, thefirst biasing spring 194 and thesecond biasing spring 195 always bias the movable support 18 (movable unit 180) forward. Therefore, when no external force is applied to the movable support 18 (movable unit 180) in the rearward direction, the firstshaft insertion portion 181 and the frontcylindrical portion 183 of the secondshaft insertion portion 182 are held at the foremost position (initial position) in contact with theshoulder portion 133 provided in thefront housing 13 in themovable support 18. That is, theshoulder 133 functions as a stopper that prevents the movable support 18 (movable unit 180) from further moving forward.

On the other hand, as shown in fig. 5 and 17, a pair of left andright cushion members 197 are provided on the front surface side of thebearing support portion 15 as stoppers for restricting further rearward movement of the movable support portion 18 (movable unit 180). More specifically, a pair of left and rightcylindrical protrusions 155 are provided on the front surface of thebearing support body 15 symmetrically with respect to the reference plane VP. Theprojection 155 projects forward so as to face the upper end portion of the movable support 18 (specifically, a portion adjacent to the firstshaft insertion portion 181 and the secondshaft insertion portion 182 on the reference plane VP side). Eachcushion member 197 is made of cylindrical rubber and fitted to eachprojection 155.

Thecushion member 197 protrudes forward from the front end of theprotrusion 155 in a state where no external force is applied. When the movable support 18 (movable unit 180) is located at the foremost position (position in fig. 17), thebuffer member 197 is located at a position rearward away from themovable support 18. Thebuffer member 197 is configured to come into contact with themovable support 18 from the rear when the movable support 18 (the movable unit 180) moves rearward relative to themain body case 10 and thefirst biasing spring 194 and the second biasing spring 195 (see fig. 15) are compressed by a predetermined amount.

In addition, in the present embodiment, thefirst guide shaft 191 and thesecond guide shaft 192 as shown in fig. 5 and 15 each have a circular cross section but have different diameters. More specifically, the diameter of thesecond guide shaft 192 on the left side is slightly smaller than the diameter of thefirst guide shaft 191 on the right side with respect to the reference plane VP. On the other hand, the total of fourcylindrical portions 183 and thebearings 184 of the first and secondshaft insertion portions 181 and 182 have the same configuration. That is, the diameter of thesupport hole 190 of thefirst guide shaft 191 is the same as the diameter of thesupport hole 190 of thesecond guide shaft 192.

Therefore, the clearance formed between the outer peripheral surface of thesecond guide shaft 192 positioned on the left side with respect to the reference plane VP and the inner peripheral surfaces of the pair ofbearings 184 of the secondshaft insertion portion 182 is slightly larger than the clearance formed between the outer peripheral surface of thefirst guide shaft 191 positioned on the right side with respect to the reference plane VP and the inner peripheral surfaces of the pair ofbearings 184 of the firstshaft insertion portion 181. That is, the distance from thesecond guide shaft 192 is slightly larger than the distance from thefirst guide shaft 191. Thefirst guide shaft 191 and the bearing 184 of the firstshaft insertion portion 181 are set to have higher dimensional accuracy, and thefirst guide shaft 191 and the bearing 184 of the firstshaft insertion portion 181 are configured to be fitted with each other with almost no gap.

When it is desired to fit both thefirst guide shaft 191 and thesecond guide shaft 192 into the respective support holes 190 with as little clearance as possible, assembly may become difficult due to errors in thefirst guide shaft 191, thesecond guide shaft 192, and/or the respective support holes 190. In contrast, according to the configuration of the present embodiment as described above, by forming the gap between thefirst guide shaft 191 and thebearing 184 with high accuracy, the guide function of themovable support 18 can be maintained well, and the assembly can be facilitated.

Further, the guide shaft (hereinafter referred to as a reference guide shaft) corresponding to a smaller pitch (higher dimensional accuracy) of thefirst guide shaft 191 and thesecond guide shaft 192 is preferably determined in consideration of an influence on the engagement of thedrive gear 78 and the driven gear 79 (see fig. 8) when themovable unit 180 rotates. More specifically, assuming that themovable unit 180 turns by the same angle about the respective axes of thefirst guide shaft 191 and thesecond guide shaft 192, it is preferable to select a guide shaft that makes the change in the center distance of the drive axis a1 of themain shaft 31 and the rotation axis a4 of the second intermediate shaft 42 (the shortest distance between the drive axis a1 and the rotation axis a4) smaller. This is because when themovable unit 180 rotates, it is difficult to affect the engagement between thedrive gear 78 and the drivengear 79.

Hereinafter, a method of determining the reference guide axis will be specifically described with reference to fig. 18. Fig. 18 shows common tangents T of the pitch circles C1 and C2 and the pitch circles C1 and C2 of thedrive gear 78 and the driven gear 79 (refer to fig. 8) on a plane orthogonal to the drive axis a1 and the rotation axis a4, respectively, when thedrive gear 78 and the drivengear 79 are in a proper meshed state. Further, the point P is a point on the drivengear 79, and at this time, the point P coincides with a node point of thedrive gear 78 and the drivengear 79.

As described above, thedrive gear 78 is provided on the secondintermediate shaft 42 that is not movable in the axial direction and the radial direction with respect to themain body case 10. On the other hand, the drivengear 79 provided on themain shaft 31 is a part of themovable unit 180. Therefore, the drivengear 79 moves relative to thedrive gear 78 about the axis of the reference guide shaft in accordance with the rotation of themovable unit 180. At this time, when the point P on the drivengear 79 moves in the extending direction of the common tangent T with respect to thedrive gear 78, the change in the center distance is small, and the meshing is less likely to be affected. On the contrary, when the point P moves in a direction substantially orthogonal to the common tangent T, the center distance changes greatly as the amount of movement thereof increases, and the engagement may be released or may become too deep.

As described above, as indicated by reference symbol S in fig. 18, the reference guide shaft is preferably disposed on the opposite side of thedrive gear 78 on a straight line L passing through the rotation axis a4 of thedrive gear 78 and the drive axis a1 as the rotation axis of the drivengear 79. In addition, in the case where neither thefirst guide shaft 191 nor thesecond guide shaft 192 is on the straight line L, it is preferable to use one of thefirst guide shaft 191 and thesecond guide shaft 192, which is closer to the straight line L, as the reference guide shaft. Specifically, an angle α formed by a line segment connecting the axis of thefirst guide shaft 191 and the drive axis a1 and a straight line L and an angle β formed by a line segment connecting the axis of thesecond guide shaft 192 and the drive axis a1 and the straight line L are compared on a plane orthogonal to the drive axis a1 and the rotation axis a 4. A guide axis corresponding to the smaller one of the angle α and the angle β may be set as the reference axis.

In the present embodiment, the drive axis a1 and the first andsecond guide rails 191 and 192 are arranged on a straight line on a plane orthogonal to the drive axis a1 and the rotation axis a 4. Therefore, the angle α 1 and the angle β 1 are the same. Therefore, the change in the center distance when themovable unit 180 rotates is the same regardless of which of thefirst guide shaft 191 and thesecond guide shaft 192 is determined as the reference guide shaft. Therefore, thesecond guide shaft 192 may be used as the reference shaft instead of thefirst guide shaft 191. On the other hand, for example, when the positions of thefirst guide shaft 191 and thesecond guide shaft 192 are changed to the positions indicated by the broken lines in fig. 18, theangle α 2 is smaller than theangle β 2. Therefore, in this case, thefirst guide shaft 191 is preferably used as the reference guide shaft.

Further, in the present embodiment, thefirst guide shaft 191 and thesecond guide shaft 192 have different diameters from each other, but thefirst guide shaft 191 and thesecond guide shaft 192 may have the same diameter. In this case, the clearances (pitches) corresponding to thefirst guide shaft 191 and thesecond guide shaft 192 can be made different by making the inner diameters of the pair ofbearings 184 of the firstshaft insertion portion 181 different from the inner diameters of the pair ofbearings 184 of the secondshaft insertion portion 182. Alternatively, the first andsecond guide shafts 191 and 192 may have different diameters from each other, and the pair ofbearings 184 of the first and secondshaft insertion parts 181 and 182 and the pair ofbearings 184 may have different inner diameters from each other.

In addition, in the present embodiment, a method of facilitating the assembly of thelock plate 45 is employed when assembling the internal structure to thefront housing 13. Hereinafter, a method of assembling thelock plate 45 will be described with reference to fig. 19 to 21. In the present embodiment, thefront housing 13 including thecylinder portion 131 is configured as a single cylindrical member. Further, thelock plate 45 is positioned at the initial position by fitting thebearing support body 15 into the rear end portion of thefront housing 13. Therefore, after the biasingspring 46 is fitted into therecess 138, the lockingplate 45 and the biasingspring 46 may be disengaged when the opening at the rear end of thefront housing 13 is directed downward before the worker fits into the bearingsupport 15 by merely inserting thespring support portion 451 into the biasingspring 46 and engaging the lockingplate 45 with therib 137.

Therefore, in the present embodiment, as shown in fig. 19, first, thespring support portion 451 is fixed by press fitting into the rear end portion of the biasingspring 46. Thelock plate 45 is fitted forward along therib 137, and the front end portion of the biasingspring 46 is fixed by press-fitting into therecess 138 of thefront housing 13. Accordingly, thelock plate 45 is temporarily fixed to thefront housing 13 by the biasingspring 46. Therefore, even if the operator moves the rear end of thefront housing 13 downward, thelock plate 45 and the biasingspring 46 do not fall off.

As shown in fig. 20, the operator inserts thefirst guide shaft 191 and thesecond guide shaft 192 into the firstshaft insertion portion 181 and the secondshaft insertion portion 182, respectively, to support themovable unit 180. The operator fits the distal ends of thefirst guide shaft 191 and thesecond guide shaft 192 into a recess provided in the front housing 13 (see fig. 15), and fits thebearing support body 15 into the rear end of thefront housing 13 while compressing the O-ring 151.

In this process, the abuttingportion 453 of thelock plate 45 abuts against theprojection 157 of thebearing support body 15. At this time, the urgingspring 46 is in an uncompressed state. After that, thebearing support body 15 presses thelock plate 45 via theprojection 157, compresses the biasingspring 46, and moves the biasingspring 46 forward along therib 137. When thebearing support body 15 reaches the predetermined position shown in fig. 21, the assembly of thelock plate 45 is completed. In this way, the worker can easily assemble thelock plate 45 to thefront housing 13 and the bearingsupport 15.

Further, the method of temporarily fixing thelock plate 45 is not limited to the above method. Although not shown in detail, thelock plate 45 may be configured to hold the biasingspring 46 in a compressed state, for example. Thelock plate 45 may be temporarily fixed to thefront housing 13 by pressing and fixing the distal end portion of the biasingspring 46 to a locking piece provided on thefront housing 13.

Further, for example, the lockingplate 45 may be temporarily fixed using a rubber pin. In this case, a holding recess for a rubber pin is provided inside the rear end portion of thefront housing 13. The holding recess is provided to abut the rubber pin against the rear end of thelock plate 45 at a position rearward of the initial position. The operator fits the front end portion of the biasingspring 46 into therecess 138, and further fits thespring support portion 451 of thelock plate 45 into the rear end portion of the biasingspring 46. After that, the lockingplate 45 is temporarily fixed by fitting the rubber pin into the holding recess. When thebearing support body 15 is fitted to a predetermined position of thefront housing 13, thelock plate 45 is pressed forward from the position where it abuts against the rubber pin, and is disposed at the initial position.

The operation of thehammer drill 101 according to the present embodiment will be described below.

When the user presses theoperation trigger 171 to turn on theswitch 172, themotor 2 is energized to drive thedrive mechanism 5. In more detail, as described above, theimpact mechanism 6 and/or therotation transmission mechanism 7 are driven to perform the hammer action and/or the drill action in response to the action mode set via themode switching dial 800.

In the hammer drill mode and the hammer mode in which the hammer is operated, when thetip tool 91 is pressed against a workpiece to perform a machining operation, vibration in the driving axis direction (the front-rear direction) is mainly generated in theimpact mechanism 6 due to a force of theimpact mechanism 6 driving thetip tool 91 and a reaction force from the workpiece of an impact force of thetip tool 91. By this vibration, themovable unit 180 moves in the front-rear direction along thefirst guide shaft 191 and thesecond guide shaft 192 with respect to themain body housing 10, and thefirst urging spring 194 and thesecond urging spring 195 expand and contract (elastically deform). Accordingly, the vibration of themovable unit 180 is absorbed, thereby reducing the vibration transmitted to themain body case 10 and thehandle 17.

When themovable unit 180 moves rearward due to vibration and thefirst biasing spring 194 and thesecond biasing spring 195 are compressed by a predetermined amount, thebuffer member 197 held by thebearing support portion 15 collides with themovable support portion 18, and further rearward movement of themovable unit 180 is restricted. Accordingly, collision of the bearingsupport 15 with themovable support 18 is prevented. Since thecushion member 197 is made of rubber, the impact caused by the collision between themovable support 18 and thecushion member 197 is reduced by elastic deformation of the rubber.

During the machining operation, the user continuously presses thehandle 17 and themain body case 10 forward toward the workpiece in order to maintain the state in which thetip end tool 91 is pressed against the workpiece. Therefore, themovable unit 180 tends to be maintained in a state of being disposed at a position rearward of the foremost position shown in fig. 15. Therefore, in the present embodiment, no buffer member is disposed on theshoulder 133 for restricting the forward movement of themovable support 18. However, a buffer member similar to thebuffer member 197 may be disposed on theshoulder 133.

As shown in fig. 9, in the hammer drill mode and the hammer mode, thefirst transmission member 64 is disposed at the engagement position (position indicated by a solid line), is spline-engaged with theintermediate member 63, and transmits the rotation of the firstintermediate shaft 41 to theintermediate member 63. Therotating body 611 as a part of themovable unit 180 is movable with respect to themain body case 10 in a range between a most forward position shown by a solid line and a most rearward position shown by a broken line as it vibrates. As described above, therotating body 611 is spline-engaged with theintermediate member 63 held immovably in the front-rear direction. Therefore, therotating body 611 moves in the front-rear direction along the splines with respect to theintermediate member 63 while rotating integrally with theintermediate member 63. In contrast, since theintermediate member 63 and thefirst transmission member 64 do not move relative to each other in the front-rear direction, the engagement state between theintermediate member 63 and thefirst transmission member 64 is not affected by the relative movement of themovable unit 180 in the front-rear direction. Therefore, the power transmission state from the firstintermediate shaft 41 to the motion conversion member 61 (specifically, the rotating body 611) can be stably maintained.

In the hammer drill mode in which the drill operation is performed in addition to the hammer operation, themain shaft 31 as a part of themovable unit 180 also moves in the front-rear direction with respect to themain body case 10 in accordance with the vibration. Therefore, as shown in fig. 10, the drivengear 79 provided on the outer periphery of thecylinder 33 is movable in the front-rear direction with respect to thedrive gear 78 between a position shown by a solid line and a position shown by a broken line, in which thedrive gear 78 is not movable in the front-rear direction with respect to themain body case 10. In contrast, in the present embodiment, the length of thedrive gear 78 in the front-rear direction is set so as to cover the movement range of the drivengear 79. Therefore, the drivengear 79 is also always meshed with thedrive gear 78 and rotates during the movement of themain shaft 31.

Even in the drill mode in which only the drill operation is performed, when themovable unit 180 moves in the front-rear direction with respect to themain body case 10, as described above, the vibration transmitted to themain body case 10 and thehandle 17 is reduced by the expansion and contraction of the first and second urging springs 194 and 195. Further, similarly to the hammer drill mode, the rotation is transmitted from thesecond counter shaft 42 to themain shaft 31 via thedrive gear 78 and the drivengear 79 without being affected by the relative movement of themovable unit 180 in the forward and backward direction.

Further, in the hammer drill mode and the drill mode in which the drill action is performed, when a load of a threshold value or more is applied to the secondintermediate shaft 42 during the drill action, as described above, thetorque limiter 73 operates to cut off the torque transmission in the power transmission path dedicated to the drill action, thereby stopping the drill action.

In the hammer drill mode and the hammer mode in which the hammer operation is performed, it is preferable that thehammer 67 does not strike theimpact bolt 68 when thetip tool 91 is not attached to thetool holder 32 or when thetip tool 91 is not pressed against the workpiece, that is, when a load is not applied (hereinafter, referred to as an unloaded state). Therefore, thehammer drill 101 of the present embodiment is provided with the idle runningprevention mechanism 30 to promptly stop the impact of thehammer 67 on theimpact bolt 68 when in the unloaded state. The air-hammer prevention mechanism 30 will be explained below.

The air-crash prevention mechanism 30 of the present embodiment is a mechanism configured as follows: when the reciprocation of thepiston 65 continues in the idling state, the displacement timing of thestriker 68 is shifted to catch thehammer 67. First, the detailed structure of thehammer 67 and theimpact bolt 68 will be described.

As shown in fig. 7, thehammer 67 includes a cylindricalmain body 671 and asmall diameter portion 672 having a diameter smaller than that of themain body 671 and protruding forward from themain body 671. Thebody portion 671 has a diameter substantially equal to the inner diameter of thepiston 65. An O-ring for hermetically sealing between theram 67 and thepiston 65 is attached to an outer peripheral portion of thebody portion 671. Aflange portion 673 is provided at the tip of thesmall diameter portion 672. Theimpact bolt 68 is configured as a cylindrical member having alarge diameter portion 681, andsmall diameter portions 683 and 684, wherein thelarge diameter portion 681 is provided at a substantially central portion in the axial direction, and thesmall diameter portions 683 and 684 are provided at the front side and the rear side of thelarge diameter portion 681, respectively.

On the other hand, as shown in fig. 22, therunaway prevention mechanism 30 includes acatcher 34 disposed inside thecylinder 33, atool holder 32, a restrictingring 35 disposed inside thetool holder 32, aguide sleeve 36, and acushion ring 37.

Thecatcher 34 is configured to catch and hold thehammer 67 in an unloaded state. Thecatcher 34 includes a catchingring 341 and aring holding part 343. Thering holder 343 is a metal cylindrical member, and is fitted into the front end of thecylinder 33 and held slidably in the front-rear direction. However, the final position of thecatcher 34 is defined by aretainer ring 345 fixed inside thecylinder 33. The catchingring 341 is an O-ring and is fitted into the rear end portion of thering holder 343. Thecatch ring 341 of the present embodiment is made of rubber.

In the present embodiment, thetool holder 32 is formed in a stepped cylindrical shape. The inner diameter of thetool holder 32 is smallest at the front portion having thebit insertion hole 330, and gradually increases toward the rear. Hereinafter, a portion of thetool holder 32 connected to the rear side of the front portion and having an inner diameter larger than that of thebit insertion hole 330 is referred to as a small-diameter portion 321. A portion connected to the rear side of small-diameter portion 321 and having an inner diameter larger than that of small-diameter portion 321 is referred to as large-diameter portion 325. A portion connected to the rear side of thelarge diameter portion 325 and having an inner diameter larger than that of thelarge diameter portion 325 is referred to as amaximum diameter portion 329. Further, themaximum diameter portion 329 is a rear end portion of thetool holder 32. That is, thecylinder 33 is connected to the rear side of themaximum diameter portion 329.

Inside thetool holder 32, afirst shoulder 322 is provided at a boundary portion between the small-diameter portion 321 and the large-diameter portion 325. Therear surface 323 of thefirst shoulder 322 is configured as a conical surface (tapered surface) having a diameter slightly increasing toward the rear. In addition, asecond shoulder 326 is provided at a boundary portion between thelarge diameter portion 325 and themaximum diameter portion 329. The rear surface of thesecond shoulder 326 is configured as a plane orthogonal to the drive axis a 1.

Theretainer ring 35 is a metal annular member, and is fitted into themaximum diameter portion 329 of thetool holder 32 and held slidably in the front-rear direction. Thestopper ring 35 functions as a stopper portion that abuts against thelarge diameter portion 681 of theimpact bolt 68 from behind, and restricts further rearward movement of theimpact bolt 68. Theretainer ring 35 also functions as a guide portion that is disposed around the small-diameter portion 684 of theimpact bolt 68 and guides the sliding movement of the small-diameter portion 684. Therefore, therestriction ring 35 has an inner diameter substantially equal to thesmall diameter portion 684, and has an inner peripheral surface of a shape matching the rear portion of thelarge diameter portion 681.

Further, acushion ring 38, which is an annular elastic body, is interposed between thestopper ring 35 and thering holding portion 343 of thecatcher 34 in the front-rear direction. Thecushion ring 38 of the present embodiment is made of rubber, and is disposed between theretainer ring 35 and thering holder 343 coaxially with thetool holder 32 in a compressed state. Accordingly, thelimiter ring 35 and thering holder 343 are biased in the direction away from each other, and are always held at the foremost position in abutment with the rear surface of thesecond shoulder 326 and the rearmost position in abutment with thestopper 345, respectively.

Theguide sleeve 36 is a metallic cylindrical member configured to slidably hold theimpact bolt 68 along the drive axis a 1. More specifically, the front half of theguide sleeve 36 is disposed around thesmall diameter portion 683 on the front side of theimpact bolt 68, and constitutes aguide portion 360 that guides the sliding movement of thesmall diameter portion 683. Further, theguide portion 360 also functions as a restricting portion that abuts against thelarge diameter portion 681 of theimpact bolt 68 from the front, thereby restricting further forward movement of theimpact bolt 68. Therefore, theguide portion 360 has an inner diameter substantially equal to thesmall diameter portion 683, and the inner peripheral surface of the rear end portion of theguide portion 360 has a shape matching the front portion of thelarge diameter portion 681. Further, the rear half of theguide sleeve 36 has an inner diameter larger than thelarge diameter portion 681.

Theguide sleeve 36 is disposed in thelarge diameter portion 325 of thetool holder 32, and is held slidably in the front-rear direction. The outer diameter of theguide sleeve 36 is smaller only at the front end portion than at other portions, and the other portions are uniform. Hereinafter, the distal end of theguide sleeve 36 is referred to as asmall diameter portion 361, and a portion having a substantially uniform outer diameter on the rear side of thesmall diameter portion 361 is referred to as alarge diameter portion 363. Thefront surface 364 of thelarge diameter portion 363 is configured as a conical surface (tapered surface) whose diameter slightly increases toward the rear.

Thecushion ring 37 is an annular elastic body, and is disposed coaxially with thetool holder 32 in the front-rear direction between the tool holder 32 (specifically, a surface defining the front end of the small diameter portion 321) and the front end surface of theguide sleeve 36, that is, the front end surface of thesmall diameter portion 361. The outer diameter of thebuffer ring 37 is substantially equal to the inner diameter of the small-diameter portion 321 of thetool holder 32. The inside diameter of thecushion ring 37 is larger than the outside diameter of thesmall diameter portion 683 of theimpact bolt 68. Therefore, thecushion ring 37 is held in a state of being separated radially outward from theimpact plug 68 in thesmall diameter portion 321.

In the present embodiment, anoil seal 39 is disposed in the tip end portion of thesmall diameter portion 321 of thetool holder 32, and theoil seal 39 is used to prevent lubricant from leaking out of themain shaft 31 or to prevent foreign matter from entering themain shaft 31. The front end of thecushion ring 37 abuts against a gasket disposed on the rear side of theoil seal 39. The rear end of thecushion ring 37 abuts against theguide sleeve 36. However, the front end of thecushion ring 37 may directly abut against the inner peripheral surface of thetool holder 32. A washer may be disposed on the front side of theguide sleeve 36, and the rear end of thecushion ring 37 may abut against the washer.

Thecushion ring 37 of the present embodiment is made of rubber, and is disposed between the gasket and the distal end surface of theguide sleeve 36 in a slightly compressed state. Accordingly, theguide bush 36 is biased rearward with respect to thetool holder 32, and the rear end surface of theguide bush 36 is always held at a position (hereinafter referred to as an initial position) in contact with the front end surface of therestriction ring 35 disposed at the most forward position. At this time, the front surface 364 (conical surface) of thelarge diameter portion 363 of theguide sleeve 36 is spaced rearward from the rear surface 323 (conical surface) of thefirst shoulder portion 322 of thetool holder 32. That is, there is a gap between thefront surface 364 of thelarge diameter portion 363 and therear surface 323 of thefirst shoulder portion 322.

The sectional shape of thecushion ring 37 in a plane including the drive axis a1 is a substantially octagonal shape that is long in the drive axis direction (front-rear direction). That is, the dimension (maximum length) of thecushion ring 37 in the front-rear direction is larger than the dimension (maximum thickness) in the thickness direction. In addition, the sectional shape of thecushion ring 37 in a plane orthogonal to the drive axis a1 is not uniform in the front-rear direction. Therefore, as thecushion ring 37 expands and contracts (elastically deforms) in the front-rear direction, the contact area between thecushion ring 37 and theguide sleeve 36 changes. More specifically, thecushion ring 37 has a small contact area with theguide sleeve 36 at the stage of starting compression, and the contact area increases as compression progresses. Thecushion ring 37 having such a shape is easily deformed at the stage of starting compression, and becomes less likely to be deformed as compression proceeds. Further, as compared with the case where theguide bush 36 has a uniform cross section in the front-rear direction, the guide bush is easily deformed in the front-rear direction, and the amount of deformation in the front-rear direction, that is, the amount of movement of theguide bush 36 can be ensured to be relatively large.

The operation of the air-hammer prevention mechanism 30 will be described below.

In a state where thetip tool 91 is pressed against the workpiece and a load is applied (hereinafter, referred to as a load state), as shown in fig. 22, theimpact plug 68 is pressed by thetip tool 91 to a position where thelarge diameter portion 681 abuts against thestopper ring 35 from the front. The rear end of theimpact pin 68 is disposed in the rear end portion of thering holder 343. When themotor 2 is driven in this state, thehammer 67 strikes theimpact bolt 68 as described above. Thelarge diameter portion 681 of theimpact plug 68 transmits the kinetic energy of thehammer 67 to thetip tool 91 without colliding with the guide sleeve 36 (guide portion 360), thereby linearly driving thetip tool 91. In this case, thecushion ring 38 can alleviate the impact when theimpact bolt 68 rebounds rearward.

When the user releases the pressing of the workpiece, thetip tool 91 moves forward from the rearmost position shown in fig. 22. In this state, when the driving of thepiston 65 is continued, as shown in fig. 23, theimpact bolt 68 struck by thehammer 67 moves forward relative to theguide sleeve 36, and thelarge diameter portion 681 collides with theguide portion 360 from behind. Accordingly, theguide sleeve 36 moves forward relative to thetool holder 32 while compressing thecushion ring 37, and thefront surface 364 of thelarge diameter portion 363 collides with therear surface 323 of thefirst shoulder portion 322.

Theimpact bolt 68 rebounds due to the reaction force from theguide sleeve 36, and can be struck again by thehammer 67 pushed out by the reciprocation of thepiston 65. However, due to the absorption of the impact by thecushion ring 37 and the movement of theguide sleeve 36 relative to thetool holder 32, the timing of the displacement of the impact pin 68 (rebound cycle) is disturbed. Therefore, a deviation occurs between the rebound period of theimpact bolt 68 and the reciprocation period of thehammer 67. As a result, as shown by the broken line in fig. 23, when thesmall diameter portion 672 of thehammer 67 enters thecatcher 34, theflange portion 673 is caught by thecatch ring 341, and the reciprocation of thehammer 67 is stopped.

In the idle-run-out prevention mechanism 30 of the present embodiment, thecushion ring 37 is disposed between thetool holder 32 and the distal end surface of theguide sleeve 36 in the front-rear direction (drive axis direction). Accordingly, as compared with a configuration in which an elastic body is disposed between thetool holder 32 and theguide sleeve 36 in the radial direction, it is possible to suppress an increase in the diameter of thetool holder 32, and to realize theanti-rattling mechanism 30 that is compact in the radial direction. By using such arunaway prevention mechanism 30, the distance (so-called center height) from the drive axis a1 to the outer surface of the main body case 10 (specifically, the cylindrical portion 131), particularly, to the upper surface can be suppressed, and the usable range of thehammer drill 101 in a narrow space (for example, a corner surrounded by a wall) can be expanded. As described above, thecylindrical portion 131 is a portion that can be gripped by a user during a machining operation. Therefore, by reducing the diameter of thecylindrical portion 131, the user can easily grip thecylindrical portion 131.

Theguide bush 36 is biased rearward by thecushion ring 37, and abuts against thestopper ring 35 disposed rearward of theguide bush 36. Therefore, theguide sleeve 36 can be stably held between thecushion ring 37 and therestriction ring 35, and thecushion ring 37 elastically deforms while moving forward together with theguide sleeve 36, thereby absorbing the impact.

In theanti-rattle mechanism 30, the structure of thecushion ring 37 may be appropriately changed. For example, instead of thebuffer ring 37, abuffer ring 371 shown in fig. 24 or abuffer ring 372 shown in fig. 25 and 26 may be employed. Thecushion ring 371 in fig. 24 is a cylindrical elastic body, and has a dimension in the axial direction larger than a dimension in the thickness direction, as in thecushion ring 37. The outer edges of the front and rear end portions of thebuffer ring 371 are chamfered. Therefore, the outer edges of the front and rear end portions of thecushion ring 371 can be prevented from being damaged by being sandwiched (bitten) between the washer and thetool holder 32 and between theguide sleeve 36 and thetool holder 32. Thecushion ring 372 in fig. 25 and 26 is a generally wave-shaped annular member having front and rear direction irregularities. Like thecushion ring 37, thecushion ring 372 is an elastic body having a dimension in the front-rear direction larger than that in the thickness direction and a cross-sectional shape in a plane orthogonal to the drive axis a1 that is not uniform in the front-rear direction, and is easily deformed in the front-rear direction.

Further, for example, as shown in fig. 27, a plurality of O-rings 373 may be provided side by side in the front-rear direction instead of thesingle cushion ring 37. Although fig. 27 shows two O-rings 373, three or more O-rings 373 may be arranged according to the space in the small-diameter portion 321. O-ring 373 is a single member and is an elastic body having a relatively small amount of deformation in the front-rear direction. In contrast, by using a plurality of O-rings 373, the amount of deformation in the front-rear direction of the entire plurality of O-rings 373 can be increased as compared with the case of using a single O-ring. Further, the plurality of O-rings 373 may all have the same structure, or may have different diameters in their respective cross sections.

The correspondence between the components of the above-described embodiment and the components of the present invention is described below. However, the components of the embodiment are merely examples, and do not limit the components of the present invention. Thehammer drill 101 is an example of a "hammer drill". Themotor 2 and themotor shaft 25 are examples of a "motor" and a "motor shaft", respectively. Themain shaft 31 is an example of a "final output shaft". The drive axis a1 is an example of a "drive axis". Thedrive mechanism 5 and themotion conversion mechanism 61 are examples of a "drive mechanism" and a "motion conversion mechanism", respectively. Themain body case 10 is an example of a "case". Themovable support 18 is an example of a "movable support". Thefirst biasing spring 194 and thesecond biasing spring 195 are examples of "at least one elastic member". The firstintermediate shaft 41 is an example of a "first intermediate shaft". The interposedmember 63 is an example of an "interposed member". Thefirst transmission member 64 is an example of a "transmission member".

Thespline portion 416 is an example of a "spline portion" of the "first intermediate shaft". Thespline section 631 is an example of a "spline section" of the "interposed member". Thefirst spline portion 641 and thesecond spline portion 642 exemplify a "first spline portion" and a "second spline portion" of the "transmission member", respectively. Therotating body 611 and the swingingmember 616 are examples of a "rotating body" and a "swinging member", respectively. The firstclutch mechanism 62 and the secondclutch mechanism 71 are examples of a "first clutch mechanism" and a "second clutch mechanism", respectively.Second countershaft 42 is one example of a "second countershaft". The mode switching dial 800 (operation portion 801) is an example of an "operation member". Thefirst guide shaft 191 and thesecond guide shaft 192 are examples of "guide shafts", respectively. Thesupport hole 190 is an example of a "support hole".

The above embodiments are merely examples, and the hammer drill according to the present invention is not limited to the illustrated configuration of thehammer drill 101. For example, the following exemplary modifications may be added. In addition, only one or a plurality of these modifications can be adopted in combination with thehammer drill 101 described in the embodiment or the structural features described in each of the claims.

Thehammer drill 101 may be configured to operate not by an external ac power source but by electric power supplied from a rechargeable battery. In this case, for example, a battery mounting portion to which a battery can be attached and detached is provided at the lower end portion of thehandle 17 in place of thepower supply line 179. Themotor 2 may be a dc motor instead of an ac motor, or may be a brushless motor instead of a motor having brushes.

The structures (shape, structural members, material, etc.) of themain body case 10 and thehandle 17 can be appropriately changed. For example, themain body case 10 may be formed by coupling half-divided bodies divided in the left-right direction instead of being divided in the front-rear direction.

The vibration-proof structure provided in themain body case 10 is not limited to the one exemplified in the above embodiment. For example, the number of guide shafts supporting themovable unit 180 is not limited to two, and may be one, or may be three or more. The position and support structure of the guide shaft, and the structures (shape, material, etc.) of themovable support 18 and the bearingsupport 15 may be appropriately changed. For example, in the above embodiment, thefirst guide shaft 191 is inserted through the pair of front andrear bearings 184 of the firstshaft insertion portion 181, and supports themovable support 18 at two locations. Similarly, thesecond guide shaft 192 is inserted through a pair of front andrear bearings 184 of the secondshaft insertion portion 182, and supports themovable support 18 at two locations. However, thefirst guide shaft 191 and thesecond guide shaft 192 may support themovable support 18 through one portion.

Thefirst biasing spring 194 and thesecond biasing spring 195 may be replaced with other types of springs (e.g., a tension coil spring or a torsion spring) or elastic members other than springs (e.g., rubber or a synthetic resin having elasticity (e.g., a urethane foam)), and the cushioningmember 197 interposed between the movable support 18 (movable unit 180) and themain body case 10 or the bearingsupport 15 may be formed of, for example, a synthetic resin having elasticity (e.g., a urethane foam) instead of rubber, or may be omitted. The number of the biasing members and the cushion members of themovable support 18 may be one, or three or more.

The arrangement of the first countershaft 41 (rotation axis A3) and the second countershaft 42 (rotation axis a4) with respect to the motor shaft 25 (rotation axis a2), and the arrangement of the first countershaft 41 (rotation axis A3) and the second countershaft 42 (rotation axis a4) with respect to the main shaft 31 (drive axis a1) are not limited to the arrangement exemplified in the above-described embodiment. For example, the rotation axis A3 and the rotation axis a4 may be arranged on a straight line with the rotation axis a2 interposed therebetween in a plane orthogonal to the drive axis a 1. Further, in contrast to the above-described embodiment, thefirst countershaft 41 and thesecond countershaft 42 may be disposed on the left and right sides with respect to the drive axis a1 (or the reference plane VP), respectively.

Further, the power for the hammer operation and the drill operation may be transmitted from one intermediate shaft to theintermediate member 63 and the drivengear 79 of themain shaft 31. That is, a single intermediate shaft may be shared for transmitting power for both hammer and drill actions. In this case, it is sufficient to provide the firstclutch mechanism 62 for transmitting or cutting off the power for the hammer action and the second clutch mechanism for transmitting or cutting off the power for the hammer action on a single intermediate shaft. In this case, as the structure of the intermediate shaft and the secondclutch mechanism 71, for example, the structure disclosed in japanese patent laid-open publication No. 2016-.

The driven-side member 75 of thetorque limiter 73 and the secondintermediate shaft 42 may be, for example, spline-engaged without theballs 76. Can be as follows: instead of the driven-side member 75, the driving-side member 74 is movable on the secondintermediate shaft 42. Thetorque limiter 73 may be omitted, or may be provided in themain shaft 31.

In themode switching mechanism 80, the shapes and the arrangements of the first switchingmember 81, thesecond switching member 82, thefirst spring 83, and thesecond spring 84, and the interlocking manner with themode switching dial 800 can be appropriately changed. For example, the first switchingmember 81 for switching the firstclutch mechanism 62 and thesecond switching member 82 for switching the secondclutch mechanism 71 may be configured to move by different operation members. The operation member associated with themode switching mechanism 80 is not limited to a rotary dial, and may be a slide-type operation lever, for example. The first andsecond springs 83 and 84 may be other kinds of springs (e.g., a tension coil spring or a torsion spring), and the first andsecond switching members 81 and 82 may not necessarily be urged. Further, on the left side where the secondintermediate shaft 42 and therotation transmission mechanism 7 are disposed with respect to the reference plane VP, there is a vacant space larger than on the right side where the firstintermediate shaft 41 and theimpact mechanism 6 are disposed. Therefore, themode switching mechanism 80 may be provided on the left side portion of themain body case 10 by using the space.

Theanti-runaway mechanism 30 may be omitted, or other types of anti-runaway mechanisms may be provided.

In view of the gist of the present invention and the above-described embodiments, the following embodiments are constructed. The following embodiments can be used in combination with thehammer drill 101 and the modification described above or the structural features described in each of the embodiments.

[ means 1]

The transmission member is provided with a transmission member that transmits the rotation of the motor to the engagement position.

Thefirst spring 83 is an example of the "urging member" of the present embodiment.

[ means 2]

Further comprising a switching mechanism configured to switch the operation mode in conjunction with the operation member,

the switching mechanism includes a first switching member and a second switching member, wherein,

the first switching member is configured to switch the first clutch mechanism between the power transmission state and the disengaged state in response to movement of the operating member in response to the manual operation;

the second switching member moves in response to the manual operation, switching the second clutch mechanism between the power transmitting state and the cut-off state.

Themode switching mechanism 80, the first switchingmember 81, and thesecond switching member 82 are examples of the "switching mechanism", "first switching member", and "second switching member" in the present embodiment, respectively.

[ means 3]

The first switching member is configured to move the transmission member between the engagement position and the release position by moving in response to the manual operation.

[ means 4]

The operating member has a first contact portion and a second contact portion, wherein the first contact portion is configured to contact the first switching member and move the first switching member; the second contact portion is configured to contact a second switching member and move the second switching member.

Thefirst pin 803 and thesecond pin 805 are examples of the "first contact portion" and the "second contact portion" in the present embodiment, respectively.

[ means 5]

The first switching member and the second switching member are movably supported by a single support member.

Thesupport shaft 88 is an example of the "support member" in the present embodiment.

[ means 6]

The damping device further includes at least one damping member interposed between the housing and the movable support in the axial direction.

Further, the followingembodiments 7 to 21 are constructed with the object of providing a technique that can contribute to the compactness of the idle driving prevention mechanism in the impact tool. Any one of the followingmodes 7 to 21 may be used alone, or two or more of them may be used in combination. Alternatively, at least one of the followingembodiments 7 to 21 can be used in combination with at least one of the structural features described in thehammer drill 101, the above-described modifications, aspects, and the respective claims of the embodiment.

[ means 7]

An impact tool configured to linearly drive a tip tool,

comprising a piston, a cylindrical tool holder, a percussion mechanism, an intermediate piece, a cylindrical sleeve and at least one elastomer body, wherein,

the piston is configured to reciprocate along a drive axis defining a front-rear direction of the impact tool;

the tool holder is provided at a distal end portion of the impact tool and configured to hold the tip tool slidably along the drive shaft;

the striker is configured to reciprocate along the drive axis by an air spring in accordance with the reciprocation of the piston;

the intermediate member is disposed between the impact member and the tip tool held by the tool holder in the front-rear direction, and is configured to transmit the kinetic energy of the impact member to the tip tool;

the sleeve is disposed in the tool holder so as to be slidable in the front-rear direction,

the at least one elastic body is disposed between the tool holder and the front end surface of the sleeve in the front-rear direction,

the intermediate member includes a small diameter portion and a large diameter portion having a diameter larger than the small diameter portion,

the sleeve holds the small diameter portion of the intermediate member slidably along the drive axis and is configured to be able to abut against the large diameter portion from the front,

the tool holder and the sleeve have a first abutment portion and a second abutment portion respectively capable of abutting each other,

the first abutting portion and the second abutting portion are separated from each other in the front-rear direction when a forward force is not applied to the sleeve, and abut against each other when a forward force is applied to the sleeve via the intermediate member.

In the impact tool of the present aspect, when the tip tool is not attached to the tool holder or the tip tool is not pressed against the workpiece, the large diameter portion of the intermediate member receiving the kinetic energy of the impact member collides with the sleeve from behind when the piston continues to reciprocate. Accordingly, the sleeve moves forward relative to the tool holder while compressing the at least one elastic body, and the second contact portion of the sleeve collides with the first contact portion of the tool holder. At this time, the timing of displacement (rebound period) of the intermediate member is disturbed due to the absorption of the impact by at least one elastic body provided between the front end surface of the sleeve and the tool holder and the movement of the sleeve relative to the tool holder. Accordingly, a deviation occurs between the rebound period of the intermediate member and the reciprocation period of the impact member, thereby ending the impact of the impact member on the intermediate member. In this way, in the impact tool of the present embodiment, the tool holder, the socket, and the at least one elastic body constitute the anti-hammering mechanism.

In this aspect, at least one elastic body is disposed between the tool holder and the distal end surface of the sleeve in the front-rear direction (drive axis direction). Accordingly, as compared with a structure in which the elastic body is disposed radially between the tool holder and the sleeve, an increase in diameter of the tool holder can be suppressed, and therefore, a rattling prevention mechanism that is compact in the radial direction can be realized. Accordingly, the distance from the drive axis to the outer surface of the housing (so-called center height) can be suppressed, and the usable range of the impact tool in a narrow space (for example, a corner surrounded by a wall) can be expanded.

[ means 8]

The impact tool according tomode 7, wherein,

the sleeve includes a small diameter portion and a large diameter portion, wherein the small diameter portion includes the front end surface; the large diameter portion is connected to a rear side of the small diameter portion and has an outer diameter larger than the small diameter portion.

That is, at least one elastic body may be disposed between the tool holder and the distal end surface of the small diameter portion.

[ means 9]

The impact tool according to claim 8, wherein,

a shoulder is provided on the interior of the tool holder,

the first abutment is a rear surface of the shoulder,

the second abutment portion is a front surface of the large diameter portion.

In the embodiments 8 and 9, the at least one elastic body and the first abutting portion and the second abutting portion can be arranged appropriately.

[ means 10]

The impact tool according to any one ofaspects 7 to 9, wherein the impact tool further comprises a tool body,

further comprising a stopper disposed on a rear side of the sleeve and configured to be brought into contact with the large diameter portion of the intermediate member from behind to restrict rearward movement of the intermediate member,

the sleeve is urged by the at least one elastic body into abutment with the stop.

According to this aspect, the sleeve can be stably held between the at least one elastic body and the stopper, and the at least one elastic body can absorb the impact by elastically deforming while the sleeve moves forward.

[ means 11]

The impact tool according to any one ofaspects 7 to 10, wherein the impact tool further comprises a tool body,

the dimension of the at least one elastic body in the front-rear direction is larger than the dimension in the wall thickness direction.

According to this aspect, the amount of deformation in the front-rear direction can be increased compared to the thickness direction.

[ means 12]

The impact tool according to any one ofaspects 7 to 11, wherein the impact tool further comprises a tool body,

a sectional shape of the at least one elastic body in a plane orthogonal to the drive axis is uneven in the front-rear direction.

According to this aspect, at least one elastic body can be provided with a portion that is easily deformable in the front-rear direction.

[ means 13]

The impact tool according toclaim 12, wherein,

the at least one elastic body is formed in a ring shape and has the front-rear direction irregularities.

[ means 14]

The impact tool according tomode 12 or 13, wherein,

the at least one elastic body is configured such that a contact area with the sleeve changes with elastic deformation.

[ means 15]

The impact tool according to any one ofaspects 7 to 14, wherein the impact tool further comprises a tool body,

at least one of the front end portion and the rear end portion of the at least one elastic body is chamfered.

According to this aspect, it is possible to prevent at least one elastic body from being damaged by being sandwiched between the tool holder and the sleeve or between the tool holder and a member disposed in the tool holder.

[ means 16]

The impact tool according to any one ofaspects 7 to 15, wherein the impact tool further comprises a tool body,

the at least one elastic body includes a plurality of elastic bodies arranged in the front-rear direction.

According to this aspect, the amount of deformation in the front-rear direction can be increased as a whole of the plurality of elastic bodies.

[ means 17]

The tool holder has a minimum diameter portion at a front end portion thereof, the minimum diameter portion having an insertion hole into which the tip tool is inserted,

the at least one elastic body is disposed between a shoulder at a rear end of the minimum diameter portion and the sleeve.

[ means 18]

The at least one elastic body is located away from the intermediate member in a radial direction of the tool holder.

[ means 19]

There is also an oil seal disposed within the tool holder,

the at least one elastic body is disposed between the oil seal and the front end surface of the sleeve.

[ means 20]

The impact tool further includes a catcher disposed behind the stopper and capable of catching a front end of the impact member.

[ means 21]

The catcher includes an annular elastic body and a holding member, wherein the elastic body is capable of catching a leading end portion of the impact member; the holding member holds the annular elastic body.

The correspondence between the respective components of the above-described embodiments and the respective components ofembodiments 7 to 21 is shown below. However, the components of the embodiment are only examples, and are not limited to the components ofembodiments 7 to 21. Thehammer drill 101 is an example of an "impact tool". Thepiston 65 is an example of a "piston". The drive axis a1 is an example of a "drive axis". Thetool holder 32 is an example of a "tool holder". Thehammer 67 is an example of an "impact piece". Theimpact bolt 68 is an example of an "intermediate piece". Theguide sleeve 36 is an example of a "sleeve". Each of the cushion rings 37, 371, and 372 is an example of "at least one elastic body". The plurality of O-rings 373 is an example of "a plurality of elastic bodies". Thefirst shoulder 322 of thetool holder 32 and itsrear surface 323 are examples of a "shoulder" and a "first abutment", respectively. The small-diameter portion 361 and the large-diameter portion 363 of theguide sleeve 36 are examples of a "small-diameter portion" and a "large-diameter portion", respectively. Thefront surface 364 of thelarge diameter portion 363 is one example of the "second abutment portion". Thelimit ring 35 is an example of a "stopper". Theoil seal 39 is an example of an "oil seal". Thecatcher 34 is an example of a "catcher". The catchingring 341 and thering holding portion 343 are examples of an "annular elastic body" and a "holding member", respectively.

The impact tool according to any ofembodiments 7 to 21 is not limited to thehammer drill 101 described in the above embodiments. For example, the following exemplary modifications may be added. At least one of these modifications can be adopted in combination with at least one of the structural features described in thehammer drill 101, the above-described modifications, aspects, and the respective aspects of the embodiment.

For example, in the above-described embodiment, thehammer drill 101 capable of performing a hammer action and a drill action is illustrated as an example of the impact tool. However, any of the embodiments 9 to 23 can be applied to any impact tool as long as the air spring that reciprocates theram 67 along the drive axis a1 is configured to transmit the kinetic energy of theram 67 to the tip tool via theimpact plug 68. Therefore, the impact tool may be, for example, an electric hammer capable of only performing a hammer action, or may be a hammer drill having only a hammer drill mode and a hammer drill mode.

Themain body case 10, its internal mechanism, vibration-proof structure, and the like may be appropriately modified or omitted. Hereinafter, usable modifications are exemplified. However, the changes that can be adopted are not limited to these examples.

For example, the main shaft 31 (tool holder 32), themotor 2, and thedrive mechanism 5 may be housed in thebody housing 10 that is L-shaped in side view. In this case, typically, themotor 2 is disposed such that the rotation axis a2 of themotor shaft 25 intersects the drive axis a 1. In theimpact mechanism 6, a crank mechanism using a crankshaft may be used as the motion conversion member instead of the swingingmember 616. Further, power can be transmitted from the common one intermediateshaft striking mechanism 6 androtation transmission mechanism 7.

Thehammer drill 101 may be configured to operate not by an external ac power source but by electric power supplied from a rechargeable battery. In this case, for example, a battery mounting portion to which a battery can be attached and detached is provided at the lower end portion of thehandle 17 instead of the power supply line. Themotor 2 may be a dc motor instead of an ac motor, or may be a brushless motor instead of a motor having brushes.

In the air-raid preventing mechanism 30, the configurations of thetool holder 32 and theguide sleeve 36 may be changed as appropriate as long as therear surface 323 of thefirst shoulder portion 322 and thefront surface 364 of thelarge diameter portion 363 are configured to be separated from each other in the front-rear direction when no forward force is applied to theguide sleeve 36, and to be in contact with each other when a forward force is applied to theguide sleeve 36 via theimpact bolt 68. For example, thefront surface 364 of thelarge diameter portion 363 of theguide sleeve 36 may be disposed further rearward. The rear half portion of theguide portion 360 may be configured to slidably guide thelarge diameter portion 681 of theimpact bolt 68.

The material and shape of the elastic body disposed between thetool holder 32 and the distal end surface of theguide sleeve 36 may be different from those of the cushion rings 37, 371, 372, and the O-rings 373. The elastic body may be formed not of rubber but of, for example, a synthetic resin having elasticity (for example, a polyurethane foam). The elastic body does not necessarily need to be formed in a cylindrical shape (ring shape), and a plurality of elastic bodies may be arranged around theimpact pin 68.

The configuration and arrangement of the restrictingring 35 and thecatcher 34 may be appropriately changed or omitted.

Claims (15)

1. A hammer drill is characterized in that the hammer drill is provided with a hammer drill body,

comprising a motor, a final output shaft, a drive mechanism, a housing, a movable support, a first intermediate shaft, an interposed member, and a transmission member,

the motor has a motor shaft;

the final output shaft is configured to hold the tip tool so that the tip tool can be detached, and is arranged so as to be rotatable about a drive axis;

the driving mechanism is configured to be capable of performing a hammer action as an action of driving the tip tool linearly along the driving axis and a drill action as an action of driving the tip tool to rotate around the driving axis by an action of the motor, and the driving mechanism includes at least a motion conversion member configured to convert a rotational motion into a linear motion;

the housing is used for accommodating the motor, the final output shaft and the driving mechanism;

a movable support that supports the final output shaft and at least a part of the drive mechanism including the motion conversion member in the housing, the movable support being configured to move in an axial direction of the drive axis relative to the housing integrally with the final output shaft and at least a part of the drive mechanism in a state of being urged by at least one elastic member;

the first intermediate shaft is supported by the housing so as to be immovable in the axial direction relative to the housing, is configured to rotate about an axis parallel to the drive axis in accordance with rotation of the motor shaft, and transmits at least power for operating the hammer to the motion conversion member;

the intermediate member is disposed so as to be rotatable with respect to the first intermediate shaft and immovable in the axial direction, and is interposed between the first intermediate shaft and the motion conversion member;

the transmission member is disposed so as to be rotatable integrally with the first intermediate shaft and movable in the axial direction relative to the first intermediate shaft,

the transmission member is movable in the axial direction between an engagement position at which the transmission member is engaged with the interposed member and power can be transmitted from the first intermediate shaft to the interposed member and a release position at which the transmission member is engaged with the interposed member and power can be transmitted from the first intermediate shaft to the interposed member; the separation position is a position at which the transmission member is separated from the interposed member and power cannot be transmitted from the first intermediate shaft to the interposed member,

the motion conversion member is rotatable integrally with the interposed member and is movable integrally with the movable support in the axial direction with respect to the interposed member.

2. The hammer drill according to claim 1,

the first intermediate shaft has a spline portion provided on an outer periphery,

the transmission member is engaged with the spline portion of the first intermediate shaft.

3. Hammer drill according to claim 1 or 2,

the clamping member has a spline portion provided on an outer periphery thereof,

the motion conversion member is engaged with the spline portion of the interposed member.

4. The hammer drill according to claim 3,

the transmission member has a first spline section engageable with the spline section of the intermediate member.

5. Hammer drill according to claim 4,

the first intermediate shaft has a spline portion provided on an outer periphery,

the transmission member has a second spline portion that engages with the spline portion of the first intermediate shaft,

the diameter of the first spline portion is larger than the diameter of the second spline portion.

6. Hammer drill according to any one of claims 1 to 5,

the transmission member is biased to the engagement position.

7. Hammer drill according to any one of claims 1 to 6,

a gap is provided between the first intermediate shaft and the interposed member in a radial direction of the first intermediate shaft,

the gap becomes locally smaller in the axial direction and in the vicinity of the transmission member.

8. The hammer drill according to any one of claims 1 to 7,

the intermediate member is a cylindrical member disposed coaxially with the first intermediate shaft around the first intermediate shaft.

9. Hammer drill according to any one of claims 1 to 8,

the transmission member is a cylindrical member disposed coaxially with the first intermediate shaft around the first intermediate shaft.

10. Hammer drill according to any one of claims 1 to 9,

the motion conversion member is supported by the movable support so as to be rotatable about the axis of the first intermediate shaft,

the interposed member is supported by the motion conversion member so as to be movable in the axial direction relative to the motion conversion member.

11. The hammer drill according to claim 10,

the motion conversion part includes a rotating body and a swing part, wherein,

the rotating body is supported by the movable support so as to be rotatable about the axis, and is spline-engaged with the interposed member;

the swing member is rotatably attached to an outer periphery of the rotating body, and configured to swing in accordance with rotation of the rotating body.

12. Hammer drill according to any one of claims 1 to 10,

the transmission member and the interposed member constitute a first clutch mechanism configured to transmit or cut off power for the hammer operation,

the drive mechanism is configured to transmit power for the drill action from the first intermediate shaft or a second intermediate shaft provided separately from the first intermediate shaft to the final output shaft,

the hammer drill further includes a second clutch mechanism provided on the first intermediate shaft or the second intermediate shaft and configured to transmit or cut off power for the drill operation.

13. The hammer drill according to claim 12,

further comprising an operation member configured to be manually operated by a user for switching an operation mode of the hammer drill,

the first clutch mechanism and the second clutch mechanism are each configured to be switched between a power transmission state and a cut-off state in response to an operation of the operating member.

14. Hammer drill according to claim 12 or 13,

the first intermediate shaft is configured to transmit only the hammer motion for performing one of the hammer motion and the drill motion,

the second intermediate shaft is configured to transmit only the drill motion of the hammer motion and the drill motion,

the second clutch mechanism is disposed on the second intermediate shaft.

15. Hammer drill according to any one of claims 1 to 14,

further having at least one guide shaft extending within the housing parallel to the drive axis,

the at least one guide shaft is inserted through at least one support hole provided in the movable support and configured to guide relative movement of the movable support in the axial direction.

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