US8584770B2 - Spindle bearing arrangement for a power tool - Google Patents

Abstract

A power tool with a motor, a housing, a transmission, an output spindle, a front bearing and a rear bearing. The motor has an output shaft. The transmission is disposed in the housing and receives a rotary input from the output shaft. The transmission includes an input planetary stage, which has an input planet carrier, and an output planetary stage. The output spindle is driven by the transmission and has a first end, which extends at least partly through the input planetary stage, and a second end opposite the first end. The front bearing is disposed between the output spindle and the housing to support the second end of the output spindle for rotation about the spindle axis. The rear bearing indirectly supports the first end of the output spindle in the housing for rotation about the spindle axis.

Description

FIELD

The present disclosure relates to a spindle bearing arrangement for a power tool.

BACKGROUND

U.S. Pat. No. 6,431,289 and U.S. patent application Ser. No. 12/610,762 disclose various rotary power tools having an output spindle, which is driven by a planetary-type transmission, and a torque limiting clutch for selectively limiting an output torque of the rotary power tool. While such rotary power tools are satisfactory for their intended purposes, such rotary power tools are nonetheless susceptible to improvement.

SUMMARY

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

In one form, the teachings of the present disclosure provide a power tool having a motor, a housing, a transmission, an output spindle, a first bearing and a second bearing. The motor has an output shaft. The transmission is at least partly disposed in the housing and receives a rotary input from the output shaft. The transmission includes a planet carrier. The output spindle is driven by the transmission and includes a first end, which is supported for rotation about a spindle axis by the planet carrier, and a second end opposite the first end. The first bearing is disposed between the housing and the planet carrier and supports the planet carrier for rotation about the spindle axis. The second bearing is disposed between the housing and the output spindle and is configured to support the output spindle for rotation about the spindle axis at a location proximate the second end.

In another form, the teachings of the present disclosure provide a power tool with a motor, a housing, a transmission, an output spindle, a front bearing and a rear bearing. The motor has an output shaft. The transmission is disposed in the housing and receives a rotary input from the output shaft. The transmission includes an input planetary stage, which has an input planet carrier, and an output planetary stage. The output spindle is driven by the transmission and has a first end, which extends at least partly through the input planetary stage, and a second end opposite the first end. The front bearing is disposed between the output spindle and the housing to support the second end of the output spindle for rotation about the spindle axis. The rear bearing indirectly supports the first end of the output spindle in the housing for rotation about the spindle axis.

In still another form, the present disclosure provides a power tool that includes a motor, a housing, a transmission, an output spindle, a spindle lock and front and rear bearings. The motor has an output shaft. The transmission is disposed in the housing and receives a rotary input from the output shaft. The transmission includes an input planetary stage, which has an input planet carrier, and an output planetary stage. The output spindle is driven by the transmission and is received through the output planetary stage such that the first end extends at least partly through the input planetary stage. The spindle lock is mounted on the output spindle between the first and second ends. The front and rear bearings, which are disposed on opposite sides of the spindle lock, support the output spindle relative to the housing for rotation about a spindle axis.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is a side elevation view of an exemplary tool constructed in accordance with the teachings of the present disclosure;

FIG. 2 is an exploded perspective view of the tool ofFIG. 1;

FIG. 3 is a longitudinal section view of a portion of the tool ofFIG. 1; and

FIGS. 4 through 6 are section views of portions of five other tools constructed in accordance with the teachings of the present disclosure.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

With reference toFIGS. 1 and 2 of the drawings, a power tool constructed in accordance with the teachings of the present disclosure is generally indicated byreference numeral10. As those skilled in the art will appreciate, thepower tool10 may be either a corded (e.g., AC powered) or cordless (e.g., DC battery operated) device, such as a portable screwdriver, impact driver, drill/driver or hammer drill/drill. In the particular embodiment illustrated, thepower tool10 is a cordless screwdriver having ahousing12, amotor assembly14, atransmission assembly16, anoutput spindle18, aspindle lock20, aclutch mechanism22, achuck24, atrigger assembly26 and abattery pack28. Those skilled in the art will understand that several of the components ofpower tool10, such as thechuck24, thetrigger assembly26 and thebattery pack28, are conventional in nature and need not be described in significant detail in this application. Reference may be made to a variety of publications for a more complete understanding of the operation of the conventional features ofpower tool10. One example of such publications is commonly assigned U.S. Pat. No. 5,897,454 issued Apr. 27, 1999, the disclosure of which is hereby incorporated by reference as if fully set forth herein.

Thehousing12 can include a pair of clamshell housing halves40 only one shown inFIG. 2) that can cooperate to define abody42, ahandle44 and abattery interface46 that can be configured to receive thebattery pack28. Thehandle44 can house thetrigger assembly26 in a conventional manner, while thebody42 can define amotor cavity48 into which themotor assembly14 can be received. Thehousing12 can be configured with an exterior gear case housing (not shown) that can be coupled to a front side of thebody42 and configured to shroud or cover all or portions of thetransmission assembly16 andclutch mechanism22. In the particular example provided, however, the clamshell housing halves40 are configured to shroud or cover thetransmission assembly16 and theclutch mechanism22.

With reference toFIGS. 2 and 3, themotor assembly14 can comprise amotor60 and anadapter plate62. Themotor60 can be any type of motor, such as a DC electric motor, and can include anoutput shaft64. Themotor60 can be received in themotor cavity48 and can be electrically coupled to thetrigger assembly26 and thebattery pack28. Theadapter plate62 can be fixedly coupled to an end of themotor60.

Thetransmission assembly16 can comprise atransmission housing80 and atransmission82. Thetransmission housing80 can be a hollow, generally tubular structure that is configured to house thetransmission82 and portions of theclutch mechanism22. Thetransmission housing80 can be received into themotor cavity48 and can engage the clamshell housing halves40 such that thetransmission housing80 is axially fixed and non-rotatably engaged to thehousing12. Thetransmission housing80 can define a front bearingmount90 and acentral cavity92 having afirst shoulder94, asecond shoulder96 and athird shoulder98.

Thetransmission82 can be a planetary-type transmission having an inputplanetary stage110 and an outputplanetary stage112 that can be received in thecentral cavity92 of thetransmission housing80. It will be appreciated that although the particular transmission depicted and described herein is a two-stage, single speed transmission, the teachings of the present disclosure have application to other types of transmissions, including those that are operable in more than one speed ratio and/or those that comprise fewer or more than two planetary stages (i.e., a single stage planetary transmission or a transmission having at least one planetary stage disposed between the input and outputplanetary stages110 and112). The inputplanetary stage110 can comprise aninput sun gear120, a plurality ofinput planet gears122, aninput planet carrier124 and aninput ring gear126, while the outputplanetary stage112 can comprise anoutput sun gear130, a plurality ofoutput planet gears132, anoutput planet carrier134 and anoutput ring gear136.

Theinput sun gear120 can be mounted on theoutput shaft64 of themotor60 for rotation therewith. Theinput planet gears122 can be meshingly engaged with theinput sun gear120 and theinput ring gear126. Theinput planet carrier124 can comprise acarrier body140 and a plurality ofpins142 that can be mounted to thecarrier body140. Each of the input planet gears122 can be rotatably mounted on a respective one of thepins142. Theinput ring gear126 can be abutted against thefirst shoulder94. Theadapter plate62 can be received in thecentral cavity92 and non-rotatably coupled to thetransmission housing80 to thereby limit rearward axial movement of theinput ring gear126 relative to thetransmission housing80, as well as to inhibit rotation of themotor60 relative to thetransmission housing80.

Theoutput sun gear130 can be coupled to thecarrier body140 of theinput planet carrier124 for rotation therewith. The output planet gears132 can be meshingly engaged with theoutput sun gear130 and theoutput ring gear136. Theoutput planet carrier134 can comprise acarrier body150 and a plurality ofpins152 that can be mounted to thecarrier body150. Each of the output planet gears132 can be rotatably mounted on a respective one of thepins152 of theoutput carrier134. Theoutput ring gear136 can be abutted against thesecond shoulder96 and non-rotatably engaged to thetransmission housing80. In the particular example provided, theoutput ring gear136 includes a plurality ofexternal teeth160 that are engaged to internal teeth162 formed on the interior of thetransmission housing80 proximate thesecond shoulder96.

Theoutput spindle18 can be a unitarily formed shaft structure that can be received at least partially through thetransmission82. Theoutput spindle18 can comprise arear end170, afront end172 and ananvil mount174 that can be disposed between the rear andfront ends170 and172. Therear end170 can be generally cylindrically shaped and can extend fully or partly through the inputplanetary stage110 where it can be supported for rotation by an element of thetransmission82. For example, therear end170 can extend through or into at least one of theoutput sun gear130 and thecarrier body140 of theinput planet carrier124 such that theinput planet carrier124 supports therear end170 of theoutput spindle18. Theoutput shaft64 of themotor60 can be received in an appropriatelysized aperture180 in therear end170 of theoutput spindle18.

A suitablerear bearing190, such as a journal bearing or bushing, can be disposed between thetransmission housing80 and thecarrier body140 of theinput planet carrier124 to support theinput planet carrier124 for rotation about aspindle axis200. It will be appreciated that therear bearing190, which can be disposed axially between theinput ring gear126 and theoutput ring gear136, can indirectly support therear end170 of theoutput spindle18 about thespindle axis200.

A suitable front bearing210, such as a ball bearing, can be disposed in the front bearing mount90 between thetransmission housing80 and thefront end172 of theoutput spindle18. Thefront end172 can be configured to transmit rearwardly-directed thrust loads into thefront bearing210 so that they may be transmitted into thetransmission housing80. One or more snap rings or other retaining devices can be employed to limit axial movement of thefront bearing210 on thefront end172 of theoutput spindle18.

Thespindle lock20 can comprise anouter collar220, a plurality of lock pins222, a plurality ofprojections224, which can be integrally formed with thecarrier body150 of theoutput planet carrier134, and ananvil226. Theouter collar220 can be an annular structure that can be received against thethird shoulder98 in thecentral cavity92 and non-rotatably engaged to thetransmission housing80. The lock pins222 can extend longitudinally parallel to thespindle axis200 between theprojections224 and an interior surface of theouter collar220. Theanvil226 can be mounted on theanvil mount174 on theoutput spindle18 such that theanvil226 is coupled to theoutput spindle18 for rotation therewith. Thespindle lock20 is configured to permit theoutput spindle18 to rotatably driven by thetransmission82, but to lock theoutput spindle18 to the transmission housing80 (to thereby inhibit rotation of the output spindle18) when theoutput spindle18 is rotated manually.

Theclutch mechanism22 can include aclutch member250, one ormore engagement assemblies252 and anadjustment mechanism254. Theclutch member250 can be an annular structure that can be fixedly coupled to theinput ring gear126. In the particular example provided, theclutch member250 includes an arcuateclutch face260 that is formed into an axially forward facing side of theinput ring gear126. The outer diameter of theclutch member250 is sized to rotate within the portion of thecentral cavity92 that is proximate thefirst shoulder94 in thetransmission housing80. While theinput ring gear126 and theclutch member250 have been illustrated as a one piece (i.e., unitarily formed) construction, those skilled in the art will understand that they may be constructed otherwise.

In the particular embodiment illustrated, theengagement assemblies252 are disposed 180° apart from one another (only one is shown inFIG. 3 for clarity) and eachengagement assembly252 includes apin member270, afollower spring272 and afollower274. Thepin member270 includes a cylindrical body portion280 having an outer diameter that is sized to slip-fit within anactuator aperture284 that is formed through thetransmission housing80. A first end of thepin member270 can have an end that can be defined by a spherical radius and can be configured to engage theadjustment mechanism254.

Thefollower spring272 can be a compression spring whose outside diameter is sized to slip fit within theactuator aperture284. The forward end of thefollower spring272 can contacts thepin member270, while the opposite end of thefollower spring272 can contact thefollower274. An end portion of thefollower274 can be cylindrical in shape and sized to slip fit within the inside diameter of thefollower spring272. In this regard, the end portion of thefollower274 can act as a spring follower to prevent thefollower spring272 from bending over when it is compressed. Thefollower274 can also include a cylindrically shaped body portion, which can be sized to slip fit within theactuator aperture284, and a tip portion that is configured to extend axially through thefirst shoulder94 and engage theclutch face260. In the particular example illustrated, the tip portion is defined by a spherical radius.

Theadjustment mechanism254 can include asetting collar322 can be shaped in the form of a generally hollow cylinder that is sized to fit and cover a front end of thehousing12. Thesetting collar322 can include an annular face into which anadjustment profile330 is formed. Theadjustment profile330 can be tapered or stepped such that rotation of thesetting collar322 will cause corresponding axial movement of thepin member270, which operates to change the torque setting of theclutch mechanism22 as a result of corresponding compression or extension of thefollower spring272.

Thesetting collar322 can include a contoured outer surface that can permit the user of thetool10 to comfortably rotate both thesetting collar322 to set theadjustment profile330 at a position corresponding to a desired torque setting of theclutch mechanism22.

During the operation of thetool10, an initial drive torque is transmitted by theoutput shaft64 of themotor60 to the inputplanetary stage110, causing the input planet gears122 to rotate. Rotation of the input planet gears122 creates a first intermediate torque that is applied against theinput ring gear126. A clutch torque applied by theclutch mechanism22 resists the first intermediate torque to thereby prevent theinput ring gear126 from rotating within thetransmission housing80 such that the first intermediate torque is applied to theinput planet carrier124 and the remainder of thetransmission82 so as to multiply the first intermediate torque in a predetermined manner according to the reduction ratio of thetransmission82.

A portion of anotherpower tool10aconstructed in accordance with the teachings of the present disclosure is schematically illustrated inFIG. 4. In the example provided, thetransmission82aincludes an inputplanetary stage110a, an intermediateplanetary stage500, and an outputplanetary stage112a. Theoutput spindle18aextends through thetransmission82asuch that therear end170aof theoutput spindle18ais received through or into at least one of an intermediate sun gear504 (which is associated with the intermediate planetary stage500) and thecarrier body140aof theinput planet carrier124asuch that theinput planet carrier124asupports therear end170aof theoutput spindle18a. Therear bearing190acan be disposed between thetransmission housing80aand an element of thetransmission82alocated rearwardly of the final or output stage of thetransmission82a(i.e., rearwardly of the outputplanetary stage112a). In the particular example provided, the rear bearing190ais disposed between thetransmission housing80aand thecarrier body140aof theinput planet carrier124ato support theinput planet carrier124afor rotation about thespindle axis200a. As with the previous example, the front bearing210ais received in a front bearing mount90aformed in atransmission housing80aand cooperates to alignfront end172aof theoutput spindle18ato thespindle axis200a.

In the particular example provided, thetransmission82ais a two-speed, three-stage planetary-type transmission in which aring gear510 associated with the intermediateplanetary stage500 is movable between a first position (shown), in which thering gear510 is meshingly engaged to the planet gears520 and a toothedexterior surface522 of theplanet carrier524 of the intermediateplanetary stage500, and a second position in which thering gear510 is translated axially rearwardly so as to non-rotatably engage therear bearing190aand disengage the toothedexterior surface522 of theplanet carrier524 of the intermediateplanetary stage500. Moreover, theclutch mechanism22ais configured to resist rotation of theoutput ring gear136a.

A portion of anotherpower tool10bconstructed in accordance with the teachings of the present disclosure is schematically illustrated inFIG. 5. This example is generally similar to that ofFIGS. 1-3, except that a pair ofmotor bearings600 support theoutput shaft64b(relative to thehousing12b) on opposite sides of themotor60b, theoutput spindle18bextends into theinput sun gear120b, theoutput shaft64bof themotor60bdoes not extend into therear end170bof theoutput spindle18b, and therear bearing190bis received between theinput sun gear120band therear end170bof theoutput spindle18b(rather than between thecarrier body140bof theinput planet carrier124band thetransmission housing80b).

A portion of anotherpower tool10cconstructed in accordance with the teachings of the present disclosure is schematically illustrated inFIG. 6. This example is generally similar to that ofFIGS. 1-3, except that a pair ofmotor bearings600 support theoutput shaft64c(relative to thehousing12c) on opposite sides of themotor64cand therear bearing190cis received between theoutput shaft64cof themotor60cand therear end170cof the output spindle18c(rather than between thecarrier body140cof theinput planet carrier124cand thetransmission housing80c).

The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.

Claims (20)

What is claimed is:

1. A power tool comprising:

a motor having an output shaft;

a housing;

a transmission in the housing and receiving a rotary input from the output shaft, the transmission comprising a planet carrier;

an output spindle driven by the transmission, the output spindle comprising a first end, which is supported for rotation about the spindle longitudinal axis by the planet carrier, and a second end opposite the first end, the second end extending from the housing and being adapted to drive a chuck into which a tool bit is removably received;

a first bearing engaging the housing and the planet carrier, the first bearing supporting the planet carrier for rotation about the spindle axis; and

a second bearing engaging the housing and the output spindle, the second bearing being configured to support the output spindle for rotation about the spindle longitudinal axis at a location nearer to the second end than the first end of the output spindle.

2. The power tool ofclaim 1, wherein the output shaft is received in the first end of the output spindle.

3. The power tool ofclaim 1, wherein a diameter of the first end is smaller than a diameter of a portion of the output shaft engaged by the first bearing.

4. The power tool ofclaim 1, further comprising a torque clutch that can cooperate with the transmission to limit an output torque of the power tool.

5. The power tool ofclaim 4, wherein the transmission further comprises a ring gear and wherein the torque clutch comprises a follower member that is biased into engagement with the ring gear to resist rotation of the ring gear relative to the housing.

6. The power tool ofclaim 4, wherein the torque clutch is disposed between the first and second ends of the output spindle.

7. The power tool ofclaim 1, wherein a spindle lock is mounted to the output spindle between the first and second ends.

8. The power tool ofclaim 7, wherein the spindle lock is mounted to a portion of the output spindle having a diameter that is different than a diameter of the first end and a diameter of the second end.

9. The power tool ofclaim 1, wherein the transmission comprises an output planetary stage and another planetary stage that is disposed between the motor and the output planetary stage, the planet carrier being associated with the another planetary stage.

10. The power tool ofclaim 1, wherein the transmission is a single speed transmission.

11. The power tool ofclaim 1, wherein the transmission includes a member that is movable between a first position and a second position, wherein the transmission operates in a first speed ratio to transmit rotary power when the member is in the first position, and wherein the transmission operates in a second, different speed ratio to transmit rotary power when the member is in the second position.

12. The power tool ofclaim 11, wherein the member is movable along a longitudinal axis of the transmission.

13. The power tool ofclaim 12, wherein the member is non-rotatably engaged to the first bearing when the member is in the first position.

14. The power tool ofclaim 13, wherein the member is a ring gear.

15. A power tool comprising:

a motor having an output shaft;

a housing;

a transmission in the housing and receiving a rotary input from the output shaft, the transmission comprising a planet carrier;

a chuck;

an output spindle driven by the transmission, the output spindle comprising a first end, which is supported for rotation about the spindle longitudinal axis by the planet carrier, and a second end opposite the first end, the second end being mounted to the chuck;

a first bearing engaging the housing and the planet carrier, the first bearing supporting the planet carrier for rotation about the spindle axis; and

a second bearing engaging the housing and the output spindle, the second bearing being configured to support the output spindle for rotation about the spindle longitudinal axis at a location nearer to the second end than the first end of the output spindle;

wherein the transmission includes a member that is movable between a first position and a second position, wherein the transmission operates in a first speed ratio to transmit rotary power when the member is in the first position, and wherein the transmission operates in a second, different speed ratio to transmit rotary power when the member is in the second position;

wherein the member is movable along a longitudinal axis of the transmission;

wherein the member is non-rotatably engaged to the first bearing when the member is in the first position; and

wherein the first bearing comprises a first set of teeth and wherein the member comprises a second set of teeth that are engageable to the first set of teeth.

16. The power tool ofclaim 12, wherein the movable member is disposed between the first and second ends of the output spindle.

17. A power tool comprising:

a motor having an output shaft;

a housing;

a transmission in the housing and receiving a rotary input from the output shaft, the transmission comprising an input stage and a planet carrier;

a chuck;

an output spindle driven by the transmission, the output spindle having a first end, which extends at least partly through the input stage, and a second end opposite the first end, the second end directly driving the chuck, the output spindle consisting of a single, continuous shaft member that extends between and includes the first and second ends;

a front bearing that engages the output spindle and the housing to support the second end of the output spindle for rotation about the spindle longitudinal axis; and

a rear bearing received in the housing and supporting an element of the transmission for rotation in the housing, the element of the transmission receiving the first end of the output spindle therein such that the rear bearing indirectly supports the first end of the output spindle in the housing for rotation about the spindle longitudinal axis.

18. The power tool ofclaim 17, wherein the first end of the output spindle is journally received into an element of the transmission.

19. The power tool ofclaim 17, wherein the element of the transmission comprises at least one of the planet carrier and a sun gear.

20. The power tool ofclaim 17, wherein a spindle lock is mounted to the output spindle between the first and second ends.

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