US3845826A - Rotary disconnect for a rotary hammer tool - Google Patents

Abstract

The rotary hammer power tool includes a tappet subjected to rotation and to axial hammering blows simultaneously. The tappet has a first set of clutch teeth and a centrally disposed hammering formation. A tool bit driver is rotatably mounted coaxially with the tappet and has a hexagonal bore adapted to receive a correspondingly shaped shank of a tool element. The driver has a second set of clutch teeth engageable with the first set of clutch teeth thereby to permit the tappet to transfer rotation to the driver. Selection means are engaged with the driver for reciprocating the same axially thereby to engage and disengage the clutch teeth for selectively imparting rotation to the driver and to the tool element received therein.

Description

HAMMER TOOL Inventor: Hanspeter E. Beisch, Buffalo Grove,

Ill.

Assignee: Skil Corporation, Chicago, 111.

Filed: Feb. 23, 1973 Appl. No: 334,988

References Cited I UNITED STATES PATENTS 1/1908 Trott 173/111 8/1967 Schnettler v .7 173/109 10/1968 Worman 173/96 Bronnert 173/110 United States Patent [111 3,845,826

Beisch Nov. 5, 1974 [5 1 ROTARY DISCONNECT FOR A ROTARY 3,720,269 3/1973 Wanner 173/109 x Primary Examiner-Ernest R. Purser Assistant ExaminerWilliam F. Pate, lll Attorney, Agent, or Firm McDougall, Hersh & Scott ABSTRACT The rotary hammer power tool includes a tappet subjected to rotation and to axial hammering blows simultaneously. The tappet has a first set of clutch teeth and a centrally disposed hammering formation. A tool bit driver is rotatably mounted coaxially with the tappet and has a hexagonal bore adapted to receive a correspondingly shaped shank of a tool element. The driver has a second set of clutch teeth engageable with the first set of clutch teeth thereby to permit the tappet to transfer rotation to the driver. Selection means are engaged with the driver for reciprocating the same axially thereby to engage and disengage the clutch teeth for selectively imparting rotation to the driver and to the tool element received therein.

5 Claims, 4 Drawing Figures PATENTEMUV 5l974 SHEE? 2 2 5 v 4/ FIGL 4 ROTARY DISCONNECT FOR A ROTARY HAMMER TOOL BACKGROUND OF THE INVENTION 1. Field of the Invention The field of the invention relates to portable power tools. More particularly, the field of the present invention relates to so-called rotary hammer power tools, i.e., power tools which have the capability of imparting simultaneous rotation and axial hammering blows to a tool element for working on concrete, for example.

2. The Prior Art Rotary hammer power tools of the type referred to are well known in the prior art. These tools are usually powered by either an electric or pneumatic motor and include a rotary output or drive member having a hexagonal bore for receiving the correspondingly shaped shank of a tool element or adapter thereby to impart rotation to the latter. These tools include a hammering mechanism, quite often in the form of a striker which is pneumatically reciprocated and arranged to strike the distal end of the shank of the tool element or adapter thereby to impart axial hammering blows to the latter simultaneously with the aforementioned rotation. Representative prior art tools are shown in Naslund et al. U.S. Pat. No. 3,114,423, McCloud U.S. Pat. No.

3,114,421 and Bassett et al. U.S. Pat. No. 3,270,821, all assigned to the assignee of the present invention.

In the use of power tools of the type under consideration, it isoften required or at least desirable at certain times to impart a hammering action only to the tool element or adapter or to impart rotation only to the tool element. When using the power tools shown in the aforementioned patents, these different modes of oper-- ation are brought about by removing the element or adapter and replacing the same with a different element or adapter. In other words, these power tools are provided with plural different tool elements each specially configured to cooperate with the hammering and rotary components of the power tool for bringing about the desired mode of operation.

In some uses of these rotary hammer power tools, it

. is too time consuming for-the operator to stop the tool,

Finally, the anchor must be hammered in place without rotation. This operation could not be achieved economically and expeditiously if the operator were required to change the tool element each time tobring about the various modes of operation just described.

SUMMARYAND OBJECTS OF THE INVENTION A primary object of the present invention is the provision of a rotary hammer power tool having means for quickly and easily converting the mode of operation from simultaneous hammering and rotation to hammering only and vice versa.

Another object of the present invention is the provision of a power tool of the type described including a tappet which is subjected simultaneously to rotation and to axial hammering blows and which has a first set of clutch teeth, and a tool bit driver mounted for rotation coaxially with the tappet and having a hexagonal bore for receiving the hexagonal shank of a tool element, which driver has a second set of clutch teeth for engagement with the first set of clutch teeth, and selection means for reciprocating the driver thereby to engage and disengage the first and second sets of clutch teeth for selectively imparting rotation to the driver and a tool element received therein.

Still another object of the present invention is the provision of a power tool according to the foregoing object, wherein such selection means is of simple and inexpensive construction and may be manually operated.

These and other objects and advantages of the present invention will become apparent from the following specification disclosing a preferred embodiment shown in the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a power tool embodying the present invention;

FIG. 2 is an enlarged fragmentary vertical section taken through the power tool of FIG. I and showing the same configured for imparting simultaneous rotation and hammering movements to a tool element;

FIG. 3 is a section similar to FIG. 2, but showing the tool configured for imparting a hammering action only to the tool element; and

FIG. 4 is an enlarged fragmentary vertical section of the power tool of FIG. 1. I

' DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIG. 1, a rotary hammer power tool is generally designated 10 and is seen to include amain housing 11 and anauxiliary housing 12. The tool includes a pistolgrip type handle 13 and anauxiliary handle 14. It will be understood that thepower tool 10 may include any suitable mechanism for imparting simultaneous rotation and hammering to an output member, reference being had to the aforementioned patents assigned to the assignee of the present invention. By way of example only and not by way of limitation, the present invention will be shown and described in association with the rotary hammer mechanism disclosed and claimed in the aforementioned Bassett et al. patent.

Referring momentarily to FIG. 4, the Bassett et al. mechanism includes anelectric motor 16 having an output shaft 17 engaged with a gear train (not shown), which gear train engagesteeth 18 on abarrel 19, the latter being mounted for rotation in thehousing 11 by aball bearing assembly 20. Thebarrel 19 mounts'a nose member 22 for rotation therewith, which nose member has a hexagonally shaped bore 23. Thebarrel 19 also includes asleeve 24 which receives acam element 25. This cam element includes a centralhexagonal bore 26 as well as a series ofcams 27. The Bassett et al. structurefurther includes a hammer integralwitha cam element 28 having a series of earns 29 for engagement with theearns 27. Thecam element 28 is mounted for reciprocal movement only and is part of the hammer; in this respect, theelement 28 includes a centrally disposed hammering formation 30.

According to the Bassett et al. mechanism, the barrel l9 and consequently the member 22 rotate whenever the tool is in operation. Such rotation of the nose member 22 will cause corresponding rotation to a hexagonally shaped tool shank received therein. If such shank has a length for being received within thebore 26 of thecam element 25, the latter will be rotated thereby to bring about operation of the hammer due to the interengagement of theearns 27, 29. For further particulars of this rotary hammer mechanism, reference should be had to the Bassett et al. patent.

The present invention will be seen to include a tappet, generally designated 32, and rotatably received in theauxiliary housing 12. The tappet includes a firstcylindrical portion 33 rotatably and slidably received within abore portion 34 of thehousing 12. The tappet further includes a reduced-in-diametercylindrical portion 35 joining with thecylindrical portion 33 to form anannular shoulder 36. Thetappet portion 35 is rotatably received within abore portion 37 of thehousing 12, which bore portion joins with theportion 34 to define anannular shoulder 38. It will be understood that forward or outward movement of thetappet 32 is limited by abutting engagement of theshoulder 36 with theshoulder 38. Rearward or inward movement of the tappet is limited by abutting engagement of theportion 33 with the nose member 22. Of course, thetappet 32 is mounted for rotation within thebore portions 34, 37.

At this time it should be mentioned that thebore portion 34 includes an annular recess 40 in which an O-ring 41 is received. As will be explained hereinbelow, this O-ring frictionally engages theportion 33 of the tappet to prevent flutter thereof at certain times during the operation of the power tool.

Thetappet 32 includes a hexagonally shapedshank 44 which is received within thebores 23, 26. Thus, rotation is imparted to thetappet 32 by the nose member 22. Since theshank 44 extends into thebore 26, this shank causes rotation of the cam element to bring about operation of the hammering mechanism. When thetappet 32 is in its innermost position, the distal end of theshank 44 will be struck or hammered by the formation on thecam element 28.

Thetappet 32 includes an annular or circumferential series ofclutch teeth 46, each tooth being defined by an inclined surface 47 and asurface 48, the latter being contained in a plane radially disposed with respect to the axis of rotation of the tappet. Thetappet 32 also includes a hammeringsurface 49 centrally disposed with respect to theclutch teeth 46.

A tool bit driver, generally designated 52, is cylindrical in form and is rotatably mounted within thebore portion 37 of theauxiliary housing 12. The tool bit driver includes a through central opening defined by a hexagonal bore 53 and anannular bore 54. The tool bit driver includes an exteriorannular recess 56. Finally, themember 52 includes a circumferential series of clutch teeth 57. These clutch teeth are identical and in opposite hand relation with theclutch teeth 46 on thetappet 32. To this end, each of the teeth 57 includes an inclined surface 58 and a surface 59. the latter being contained in a plane radially disposed with respect to the axis of rotation of thetool bit driver 52.

Theauxiliary housing 12 includes an annular recess receiving a disk-like member 62. This member is rotatably retained in such recess by asnap washer 63. A shift lever or operatingmember 64 is secured to the disk-like member 62, as by means of a threadedfastener 65. It will be understood that the operator of the tool grasps theshift lever 64 for imparting rotation to the disk-like member 62.

Themember 62 mounts a pin 67 eccentrically disposed with respect to its center of rotation. The pin 67 mounts a roller 68 which is received within theannular recess 56 of thetool bit driver 52. It will be apparent that partial rotation of the disk-like member 62 in response to actuation of the shift lever will cause axial reciprocal movement of thetool bit driver 52 thereby to bring about engagement and disengagement of theclutch teeth 46, 57. Preferably, detent means (not shown) are provided to establish the two positions of the shift lever thereby in turn establishing the forward (disengaged) and rearward (engaged) axial positions of thetool bit driver 52.

Referring particularly to FIG. 4, it will be seen that theauxiliary housing 12 includes abore portion 70 communicating with thebore portion 37. Anannular dust seal 71 is mounted at the innermost end of thebore portion 70. Thebore 70 communicates with a transversely disposed bore 72, the latter rotatably receiving anelement 73 of a tool retainer of the type well known to those skilled in the art.

A tool element or adapter, generally designated 75, is fragmentarily shown in FIGS. 2 and 3 and will be seen to include acylindrical portion 76 joining with a reduced-in-diametercylindrical portion 77, the latter cooperating with theretainer element 73 to hold the tool element in place although permitting both rotation and limited axial movement thereof. Thecylindrical portion 77 joins with anothercylindrical portion 78, the latter in turn joining with a hexagonally shapedshank portion 79. This shank portion is received within the hexagonal bore 53 of thetool bit driver 52; accordingly; rotation of the driver will impart corresponding rotation to thetool element 75. When thetool element 75 is in its innermost position, the distal end of theshank portion 79 is arranged to be engaged or abutted by the hammeringformation 49 on thetappet 32.

The operation of the power tool according to the present invention will be explained by first referring to FIG. 2 which shows theshift lever 64 positioned for bringing about engagement of theclutch teeth 46, 57. Since the clutch teeth are engaged, thetappet 32 will transfer rotation to thetool bit driver 52 thereby in turn imparting rotation to thetool element 75. The tool element will be subjected simultaneously to hammering blows due to the engagement between the hammeringformation 49 and the distal end of thetool element shank 79.

If it is desired to impart a hammering action only to thetool element 75, theshift lever 64 is actuated to slide thetool bit driver 52 forwardly thereby disengaging theclutch teeth 46, 57. Accordingly, thetool bit driver 52 will no longer be rotated and consequently rotation will not be imparted to thetool element 75. However, hammering blows will still be imparted to the tool element due to the engagement of the hammeringformation 49 with the distal end of theshank 79. It will be apparent that theshift lever 64 may be actuated while the tool is in operation to engage the clutch teeth as well as to disengage said clutch teeth.

Accordingly, it will be seen that the present invention provides a unique, easy-to-operate means for rapidly converting from simultaneous hammering and rotation to hammering only and vice versa. It should be noted that the engagement between theannular shoulders 36,

38 limits the forwardmost position of thetappet 32 thereby to prevent the latter from causing damage to any parts of the selection means, particularly the pin 67. it also should be noted that when a tool element is not received in thebore 70 or is allowed to occupy its forwardmost or outermost position as determined by theretainer element 73, thetappet 32 will be allowed to move forwardly or outwardly until it is stopped by engagement of theshoulders 36, 38. In this position of thetappet 32, the distal end of theshank 44 is beyond the range of movement of the hammering formation 30 on thecam 28. The O-ring 41 frictionally engages the tappet and acts to minimize fluttering movement of the tappet.

It will be apparent that the hammering action will be provided only when thetappet 32 is forced inwardly to bring the distal end of theshank 44 within the range of reciprocal hammering movement of the formation 30. The operator causes theshank 44 to be brought into hammering engagement by the formation 30 by urging the power tool against the work. This result obtains since the distal end of theshank portion 79 of the tool element abuts the hammeringformation 49 on thetappet 32 thereby to force the latter inwardly so as to be hammered by the formation 30. Consequently, the operator controls the hammering action and may bring about a cessation of hammering simply by withdrawing the power tool a short distance from the work which will allow the distal end of theshank 44 to move beyond the range of reciprocal hammering action of the formation 30. Thus, it is apparent that in the use of the power tool according to the present invention, three different modes of operation, i.e., simultaneous hammering and rotation, rotation only and hammering only, may be quickly and easily achieved without changing the tool element or adapter.

The engagement ofthe sets ofclutch teeth 46, 57 serves to transfer rotation only from thetapPet 32 to thetool bit driver 52. This result is obtained since thefaces 48, 59 of the respective sets of clutch teeth which engage each other are contained in planes radially disposed with respect to the axis of rotation of the tappet and tool bit driver. As noted in FIG. 2, when such faces of the clutch teeth are engaged, the inclined faces or surfaces 47, 58 of the clutch teeth are in spaced relation; these inclined surfaces of the clutch teeth are never brought into engagement with each other. Thus, hammering blows are not transmitted to thetool bit driver 52 or any parts of the selection means constituted primarily by theshift lever 64.

l claim:

1. In a rotary hammer power tool of the type having an output member in the form of a tappet which is adapted to be subjected to rotation and to axial hammering blows simultaneously, the improvement comprising:

a. said tappet having a first set of clutch teeth and 0ppositely extending, centrally disposed, first and second hammering formations;

b. a rotary tool bitdriver and wall means mounting the same for rotation coaxially with said tappet, said wall means also permitting axial reciprocal movement of said driver, which driver has a centrally disposed, axial, through bore and a second set of clutch teeth adapted for engagement with said first set of clutch teeth thereby to permit said tappet to transfer rotation to said driver;

c. a tool element having a shank received in said bore of said driver with the distal end thereof in abutting engagement with said first hammering formation blows to the tool element;

d. connection means on said driver and said shank for transferring rotation of the former to the latter and permitting axial reciprocal movement of said driver relative to said tool element and vice versa;

e. selection means engaged with said driver for reciprocating the same axially thereby to engage and disengage said first and second sets of clutch teeth for selectively imparting rotation to said driver and to the tool element therein;

f. said power tool having a reciprocal hammering element arranged to engagesaid second hammering formation thereby to impart hammering blows to said tappet;

g. other wallmeans rotatably mounting said tappet and including an abutment surface; and

h. said tappet having an abutment element arranged to abut said abutment surface thereby to establish the forwardmost position of said tappet, which tappet is out of the range of the movement of said thereby permitting the tappet to impart hammering hammering element when the former is in said forwardmost position thereof, said tappet being moved inwardly and into the range of movement of said hammering element by the engagement of the distal end of said shank with said first hammering formation.

2. The improvement according to claim 1 further defined by, said first and second clutch teeth engaging each other only at respective surfaces contained in planes radially disposed with respect to the axis of rotation of said tappet and driver, the surfaces on said first clutch teeth being slidably engaged withthe surfaces on said second clutch teeth whereby said tappet transfers rotational forces only to said driver.

3. The improvement according to claim 1 wherein said connection means are defined by a multi-surface configuration of said bore and a correspondingly shaped cross-section of the shank of said tool element.

4. The improvement according to claim 1 wherein said selection means includes a manually operated rotary member mounted by said wall means and having a pin eccentric with respect to the center of rotation thereof, and scotch-yoke means on said driver and engaged with said pin.

5. In a rotary hammer power tool of the type having a motor and a drive train for rotating a nose member and for actuating a hammering mechanism, the improvement comprising:

a. a tappet and first wall means rotatably mounting the same in co-axial relationship with said nose member;

b. first connection means on said nose member and said tappet for transferring rotation of the former to the latter;

c. said tappet having a first hammering formation cooperating with said hammering mechanism such that the tappet is subjected to simultaneous hammering and rotation in one axial position and to rotation only in another axial position;

d. abutment means adjacent said first wall means and adapted to be engaged by said tappet thereby to limit axial movement of the latter and to establish said positions of the tappet;

e. said tappet having a second hammering formatio and a first clutch formation;

f. a rotary tool bit driver and second wall means mounting the same for rotation co-axially with said tappet, other abutment means permitting limited axial movement of said driver;

g. said driver having a centrally disposed, axial,

through bore and a second clutch formation arranged for engagement with said first clutch formation thereby to permit said tappet to transfer rotation to said driver;

h. a tool element having a shank received in said bore of said driver with the distal end thereof in abutting second connection means on said driver and on said shank for transferring rotation of the former to the latter and permitting axial movement of the driver relative to the tool element and vice versa; and

. selection means engaged with said driver for shifting the same axially thereby to engage and disengage said first and second clutch formations for selectively imparting rotation to said driver and to the tool element therein.

Claims (5)

1. In a rotary hammer power tool of the type having an output member in the form of a tappet which is adapted to be subjected to rotation and to axial hammering blows simultaneously, the improvement comprising: a. said tappet having a first set of clutch teeth and oppositely extending, centrally disposed, first and second hammering formations; b. a rotary tool bit driver and wall means mounting the same for rotation coaxially with said tappet, said wall means also permitting axial reciprocal movement of said driver, which driver has a centrally disposed, axial, through bore and a second set of clutch teeth adapted for engagement with said first set of clutch teeth thereby to permit said tappet to transfer rotation to said driver; c. a tool element having a shank received in said bore of said driver with the distal end thereof in abutting engagement with said first hammering formation thereby permitting the tappet to impart hammering blows to the tool element; d. connection means on said driver and said shank for transferring rotation of the former to the latter and permitting axial reciprocal movement of said driver relative to said tool element and vice versa; e. selection means engaged with said driver for reciprocating the same axially thereby to engage and disengage said first and second sets of clutch teeth for selectively imparting rotation to said driver and to the tool element therein; f. said power tool having a reciprocal hammering element arranged to engage said second hammering formation thereby to impart hammering blows to said tappet; g. other wall means rotatably mounting said tappet and including an abutment surface; and h. said tappet having an abutment element arranged to abut said abutment surface thereby to establish the forwardmost position of said tappet, which tappet is out of the range of the movement of said hammering element when the former is in said forwardmost position thereof, said tappet being moved inwardly and into the range of movement of said hammering element by the engagement of the distal end of said shank with said first hammering formation.

2. The improvement according to claim 1 further defined by, said first and second clutch teeth engaging each other only at respective surfaces contained in planes radially disposed with respect to the axis of rotation of said tappet and driver, the surfaces on said first clutch teeth being slidably engaged with the surfaces on said second clutch teeth whereby said tappet transfers rotational forces only to said driver.

3. The improvement according to claim 1 wherein said connection means are defined by a multi-surface configuration of said bore and a correspondingly shaped cross-section of the shank of said tool element.

4. The improvement according to claim 1 wherein said selection means includes a manually operated rotary member mounted by said wall means and having a pin eccentric with respect to the center of rotation thereof, and scotch-yoke means on said driver and engaged with said pin.

5. In a rotary hammer power tool of the type having a motor and a drive train for rotating a nose member and for actuating a hammering mechanism, the improvement comprising: a. a tappet and first wall means rotatably mounting the same in co-axial relationship with said nose member; b. first connection means on said nose member and said tappet for transferring rotation of the former to the latter; c. said tappet having a first hammering formation cooperating with said hammering mechanism such that the tappet is subjected to simultaneous hammering and rotation in one axial position and to rotation only in another axial position; d. abutment means adjacent said first wall means and adapted to be engaged by said tappet thereby to limit axial movement of the latter and to establish said positions of the tappet; e. said tappet having a second hammering formation and a first clutch formation; f. a rotary tool bit driver and second wall means mounting the same for rotation co-axially with said tappet, other abutment means permitting limited axial movement of said driver; g. said driver having a centrally disposed, axial, through bore and a second clutch formation arranged for engagement with said first clutch formation thereby to permit said tappet to transfer rotation to said driver; h. a tool element having a shank received in said bore of said driver with the distal end thereof in abutting engagement with said second hammering formation on the tappet thereby to allow alternate positioning of the tappet in said positions thereof and to allow the transmission of hammering blows from the tappet to the tool element when the former occupies said one axial position thereof; i. second connection means on said driver and on said shank for transferring rotation of the former to the latter and permitting axial movement of the driver relative to the tool element and vice versa; and j. selection means engaged with said driver for shifting the same axially thereby to engage and disengage said first and second clutch formations for selectively imparting rotation to said driver and to the tool element therein.

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