Torque transmission device and spanner

Abstract

 A torque transmission device (10) comprises a drive assembly and a member (20) to be driven thereby. The driven member (20) defines at least one cam face (28). The drive assembly comprises a first part (32,40) urgeable in a first direction, and a second part (15) movable relative to the first part (32,40). When the first part (32,40) is urged in the first direction, movement of the second part (15) in the first direction engages the first part (32,40) between the, or each, cam face (28) and the second part (15) to drive the driven member (20) in the first direction. When the second part (15) is moved in a second direction, the first part (32,40) is substantially disengaged from the, or each, cam face, whereby the drive assembly can move relative to the driven member (20).

Description

[0001] The present invention relates to a torque transmission device and, in a second aspect, to a spanner incorporating such a device.

[0002] Ratchet spanners are well known. These can be switched between screwing and unscrewing modes, in each of which torque can be transmitted in one rotational sense, while rotation of the body of the spanner in the other rotational sence produces little torque, because the ratchet mechanism allows relative rotation of parts of the spanner. However, particularly when such a spanner is new, there may be quite a degree of resistance in the ratchet mechanism so that the parts are reluctant to rotate relative to one another. On the other hand, the teeth tend to wear out or become loose so that in an aged ratchet spanner, the mechanism becomes unreliable. The ratchet mechanism also tends to be rather bulky.

[0003] It is an object of this invention to obviate and/or mi-tigate these disadvantages.

[0004] According to this invention there is provided a torque transmission device comprising a drive assembly and a driven member, the driven member defining at least one cam face which the drive assembly can engage, whereby the drive assembly can be urged in a first direction, and when said drive means is moved in said first direction the drive means engages the, or each, cam face to drive the driven member in said first direction, and when said drive assembly is moved in a second direction the drive assembly is substantially disengaged from the, or each, cam face whereby the drive assembly can move relative to the driven member.

[0005] Preferably, the drive assembly can be selectively urged in said first or second direction. When said drive assembly is urged in said second direction movement of said drive assembly in said second direction engages said drive assembly with the or each cam face to drive said driven member in said second direction, and when said drive assembly is moved in said first direction, the drive assembly is substantially disengaged from said driven member whereby the drive assembly can move relative to the driven member.

[0006] Alternatively, the drive assembly can be so arranged to be urged only in said first direction whereby the driven member can be driven only in said first direction. The driven member may comprise an insert movable between a first position in which the drive assembly can drive said insert in said first direction, and a second position in which the drive assembly can drive the insert in said second direction. Preferably, when the insert is in said first position, part of the insert may project from said drive assembly on one side thereof, and when said insert is in the second position, part of the insert may project from the drive assembly on the opposite side thereof.

[0007] Preferably, the drive assembly comprises roller means and may define at least one engagement surface whereby when the drive means is moved in said first direction the roller means can be wedged between the, or each, cam face and the, or each, engagement surface to move said driven member in said first direction.

[0008] Resilient urging means may be provided to urge said roller means towards engagement with the, or each, cam face and the, or each, engagement surface. The resilient urging means may comprise at least one pair of resilient urging members to urge the rollers in said first or second direction.

[0009] Alternatively, the resilient urging means may comprise at least one resilient urging member adapted to urge the driven member only in said first direction.

[0010] The driven member may include a cam drive unit which may comprise a cam member to define the, or each, cam face, and the drive assembly may comprise an engagement member to define the, or each, engagement surface. The engagement member may define a single engagement surface which is preferably of substantially circular cross section and may surround the cam member. Preferably, the cam member defines a plurality of cam faces which may be arranged symmetrically around the cam member. The roller means may comprise a plurality of rollers whereby each roller is associated with a respective one of said cam faces.

[0011] The, or each, cam face may be substantially planar may be extended substantially parallel to a tangent to the substantially circular engagement surface.

[0012] The drive assembly may further include a carrier adapted to carry the rollers. In a first embodiment, the resilient urging means may comprise first and second res-ilient urging members adapted to act on said carrier to urge the carrier in opposite directions. Switching means may be provided to urge selectively each of said first and second resilient urging members to cause said urging members to urge said carrier in a selected one of said opposite directions to urge each of said rollers towards a selected end of respective cam faces.

[0013] In said first embodiment, the resilient urging members may comprise two compression springs which may be raised in an elongate recess in said carrier preferably at opposite ends of said recess. The switching means may comprise a lever arranged in said recess between said compression springs. The lever may be movable in opposite directions along the recess to compress a respective one of said compression springs. The recess may be arranged substantially parallel to a target to the substantially circular engagement surface.

[0014] In this first embodiment, the carrier may be in the form of a selector cage, preferably being cylindrical in configuration and may be provided with a plurality of recesses to receive a respective one of the rollers. The carrier may be formed of a suitable plastics material, for example nylon. The carrier is preferably arranged between the engagement surface and the cam member.

[0015] A cover may be provided for said carrier. The cover may define an elongate slot through which said lever may project.

[0016] In a second embodiment, the resilient urging means comprises a pair of resilient urging members for each roller to urge the respective rollers in opposite directions towards one end of each respective cam surface. The apparatus may further include detent means whereby the carrier can be moved to a position in selected one of said of opposite directions and by said detent means at said position. The detent means may comprise a catch member mounted on the cam member and a recess on the carrier. The catch member may comprise a spring and a ball.

[0017] In a third embodiment, the rollers and the resilient urging means are mounted on the cam member, and the resilient urging means may comprise a resilient urging member for each roller. The cam member may include a plurality of walls each extending transversely to a respective one of the cam faces whereby each roller is urged by a respective resilient urging member along the respective cam surface towards the engagement surface.

[0018] In the third embodiment, the cam member may include an insert received in a bore through the cam member, the insert being movable between first and second positions in which a portion of the insert projects outwardly from opposite sides of the cam member in, respectively,each of said positions.

[0019] Each resilient urging member may be in the form of a spring, for example, a compression spring.

[0020] Some embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings in which:

Fig. 1 is a sectional view of a spanner embodying the present invention;

Fig. 2a,b and c are perspective views of the cam drive, selector and top cover of the spanner of Fig. 1;

Fig. 3 a,b,c and d are views of components of a second embodiment: Fig. 3a is a perspective view of a cam drive unit; Figs. 3b and c are top perspective and bottom plan views of a selector cage; and Fig. 3d is a view equivalent to Fig. 1;

Fig. 4 is a view like Fig. 1 but showing a third embodiment;

Fig. 5 is a section of V-V in Fig. 3, also showing a spanner socket; and

Fig. 6 is a perspective view of the drive member of the third embodiment.

[0021] Fig. 1 shows a spanner 10 having a body providing an arm 12 and a head 14 in which there is a cavity in which is mounted a hardened ring 15 defining an engagement surface 17. The ring 15 is fixed to with the body, and provides a bearing and housing for receiving a drive assembly 16, and a driven member 20. The driven member 20 includes a drive shaft 18 and a cam drive unit 21. The drive shaft 18 will, be coupled to a component which it is desired to turn by means of the spanner. The drive shaft 18 is integral and coaxial with the cam drive unit 21, which has a thrust flange 22 having an axial face 24 from which projects a cam member 26 having the form of a pentagonal prism, with five cam faces 28 perpendicular to the face 24 of the thrust flange. The cam member 26 is smaller than the flange 22, so that, seen in plan, it is entirely surrounded by the flange surface 24. A mounting shaft 30 projects above the cam member 26.

[0022] Five cylindrical rollers 32 are located with end faces on the thrust flange face 24, with their cylindrical faces in contact with respective cam faces 28. A carrier in the form of a selector cage 34, which may be injection moulded, suitably from nylon, has the form of a shallow cup having a flat base 36 with a central aperture 38 dimensioned to allow passage of the shaft 30; and a cylindrical skirt 40 having five equi-spaced openings 42. These are dimensioned so that the skirt 40 can straddle the five rollers 32, thus maintaining them at equal angular spacings. The rollers 32 are dimensioned so that, when they are in contact with intermediate regions of the cam faces 28, they are spaced from the ring 15, but if they travel towards either adjacent vertex, they come in contact with the ring, as shown in Fig. 1.

[0023] The top cover 44 is a disc with a central openign 46 by which it is engagable on the shaft 30. It has an elongated opening 48 in which a lever 50 is slidably mounted. The lever 50 projects downwardly, into a recess 52 in the face of the selector cage 36. This recess 52 is likewise elongate, in a direction parallel to a tangent. At each end it houses a compression spring 54. The lever 50 is movable between positions at extreme ends of the slot 48 so as to compress selectively either of the springs 54, whereby the case 34 is lightly urged to rotate in either direction to a small extent.

[0024] In use, the lever 50 is moved to the appropraite position so that the selector cage 36 moves the rollers 32 towards one end of their respective cam faces 28, where they are lightly urged by one of the springs 54 into the narrowing gap between their respective cam face and the ring 13. If torque is applied between the spanner body 10 and the drive shaft 18 in a sense tending to drive the rollers 32 more tightly into their narrowing gaps, the ring 15 acts as if it were rotationally fixed with the cam drive unit 16, because of the wedging of the rollers 32 between the ring 15 and the cam member 26. But the cam unit can rotate freely relative to the spanner body in the reverse direction.

[0025] Fig. 3 shows another form of torque transmission device for use in a spanner. Components corresponding to those in the first embodiment are given the same reference numberals but raised by 100. Once again there is a cam drive unit 116 having a thrust flange 122 from which projects a cam member 126. A shaft 130 projects from the cam member 126. In this embodiment the cam member 126 has three cam faces 128 and 120° intervals, separated by non-camming portions 129. Adjacent one of these portions, the axial face 124 of the thrust flange bears a detent device involving a ball 180 urged upwardly by a spring 182.

[0026] The selector cage 134 has the shape of a shallow cup with an opening 138 in its base 136, and a cylindrical wall 140. The cylindrical wall 140 is dimensioned to embrace an array of three rollers 132 that engage respective cam faces 128. Inside the base 136 there are three pairs of compression springs 154 symmetrically arranged so that each pair embraces a respective roller 132. The inner face also has ribs or recesses arranged to define three locations 184 for the detent ball 180. In use, the selector cage 140 engages the cam unit 126 and the three rollers. The shaft 130 extends through the opening 138. It has an annular groove so that the assembly can be locked together by means of a circlip. The selector cage 134 is mounted in the correct orientation so that the detent ball 180 is one of the detent recesses 184. If it is in the central recess, the pairs of springs are symmetrically located with respect to the three cam faces. The selector cage 134 can then be rotated in either direction (facilitated by finger grips 190 on its outer face), so that the detent ball 180 clicks into one of the outer detent recesses. In either of these configurations, one spring of each pair urges its associated roller to move in one sense relative to its cam surface, with effects which will be understood from the preceding description of the first embodiment.

[0027] Figs. 4-6 show a further embodiment, incorporating a one-way sprag clutch linkage. A spanner 210 has a head 214 with a cavity housing a hardened ring 215 within which a drive assembly 216 is rotatably mounted. This includes insert 218 which is in the form of a cuboidal block. This is slidably received in a square-section hole 300 passing through a cam drive unit 20. The block is longer than the thickness of the drive unit 220 and head 214, so it can be displaced to project from either side. Its projecting end can engage a spanner socket member 302 of conventional type.

[0028] The cam drive unit 220 includes a thrust flange 222 having an axial face 224 and a cam member 226 which provides a plurality of cam faces 228, each of which defines a plane that, in one direction, approaches the inner circumference of the ring 215. In the embodiment shown, three cam faces 228 are provided. Thus there are tapering cavities between the cam surfaces and the ring. Rollers 232 are located in respective cavites; they stand on the axial face 224 and can roller along respective cam faces 228. Springs 254 are arranged between the rollers 232 and transversely walls 233 extending transversley from the cam faces 228 urging them towards the narrow ends. Rotation of the ring 215 clockwise as seen in Fig. 4 moves the rollers away from the narrow ends, so that the ring can rotate relative to the cam member. Rotation in the other sense locks the ring and cam member together. In Fig. 4 the insert 218 is in a first position and, as viewed in Fig. 4, the spanner can crank the insert 218 in an anticlockwise sense, and can be used for anticlockwise driving a socket spanner 302 connected to the insert 218. If the insert 218 is pushed through the drive unit 220 to a second position so it projects at the other side and engages the socket spanner 302, the socket spanner 302 can now be driven in the clockwise direction.

[0029] Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

1. A torque transmission device comprising a drive assembly and a member to be driven thereby, the driven member defining at least one cam face, and the drive assembly being characterised by a first part urgeable in a first direction and a second part movable relative to the first part, whereby when the first part is urged in said first direction, movement of the second part in said first direction engages the first part between the, or each, cam face and the second part to drive the driven member in said first direction, and when said second part is moved in a second direction the first part is substantially disengaged from the, or each, cam face whereby the drive assembly can move relative to the driven member.

2. A torque transmission device according to Claim 1 characterised in that said first part of the drive assembly can be selectively urged in said first or second direction, whereby when said first part is urged in said second direction movement of said second part in said second direction engages said first part between the, or each, cam face and the second part to drive said driven member in said second direction, and when said second part is moved in said first direction, the first part is substantially disengaged from said driven member whereby the drive assembly can move relative to the driven member.

3. A torque transmission device according to Claim 1 characterised in that the first part is urgeable only in said first direction whereby the driven member can be driven only in said first direction.

4. A torque transmission device according to Claim 3 characterised in that the driven member comprises an insert movable between a first position in which the drive assembly can drive said insert in said first direction, and a second position in which the drive assembly can drive the insert in said second direction.

5. A torque transmission device according to Claim 4 characterised in that when the insert is in said first position, part of the insert may project from said drive assembly on one side thereof, and when said insert is in the second position, part of the insert may project from the drive assembly on the opposite side thereof.

6. A torque transmission device according to any preceding claim characterised in that the first part comprises roller means and the second defines at least one engagement surface whereby when the first part is urged in one of said first or second directions and the second part is moved respectively in said first or second direction the roller means is wedged between the, or each, cam face and the, or each, engagement surface to move said driven member in said respective first or second direction.

7. A torque transmission device according to Claim 6 characterised in that resilient urging means is provided to urge said first part towards engagement with the, or each, cam face and the, or each, engagement surface.

8. A torque transmission device according to Claim 7 characterised in that the resilient urging means comprises at least one pair of resilient urging members to urge the roller means in said first or second direction.

9. A torque transmission device according to Claim 7 characterised in that the resilient urging means comprises at least one resilient urging member adapted to urge said first part only in said first direction.

10. A torque transmission device according to any of Claims 6 to 9 characterised in that the driven member includes a cam drive unit comprising a cam member to define the, or each, cam face, and the drive assembly comprises an engagement member to define the, or each, engagement surface.

11. A torque transmission device according to Claim 10 characterised in that the engagement member defines a single engagement surface which is of substantially circular cross section and surrounds the cam member.

12. A torque transmission device according to Claim 10 or 11 characterised in that the cam member defines a plurality of cam faces which are arranged symmetrically around the cam member.

13. A torque transmission device according to Claim 8 to 11 characterised in that the, or each, cam face is substantially planar and extends substantially parallel to a tangent to the substantially circular engagement surface.

14. A torque transmission device according to any of Claims 6 to 13 characterised in that the roller means comprises a plurality of rollers whereby each roller is associated with a respective one of said cam faces.

15. A torque transmission device according to Claim 14 characterised in that the drive assembly further includes a carrier adapted to carry the rollers.

16. A torque transmission device according to Claim 15 insofar as it is dependent upon Claims 12 and 13 characterised in that the resilient urging means comprise first and second resilient urging members adapted to act on said carrier to urge the carrier in opposite directions.

17. A torque transmission device according to Claim 16 characterised in that switching means is provided to urge selectively each of said first and second resilient urging members to cause said urging members to urge said carrier in a selected one of said opposite directions to urge each of said rollers towards a selected end of respective cam faces.

18. A torque transmission device according to Claim 17 characterised in that the resilient urging members comprise two compression springs which are received in an elongate recess in said carrier at opposite ends of said recess.

19. A torque transmission device according to Claim 18 characterised in that the switching means comprises a lever arranged in said recess between said compression springs, the lever being movable in opposite directions along the recess to compress a respective one of said compression springs.

20. A torque transmission device according to any of Claims 15 to 19 characterised in that the carrier is in the form of a selector cage, being cylindrical in configuration and being provided with a plurality of recesses to receive a respective one of the rollers.

21. A torque transmission device according to any of Claims 19 to 20 characterised in that the carrier is formed of a suitable plastics material, and is arranged between the engagement surface and the cam member.

22. A torque transmission device according to Claim 15 insofar as it is dependent upon Claims 8 and 9 characterised in that the resilient urging means comprises a pair of resilient urging members for each roller to urge the respective rollers in opposite directions towards one end of each respective cam surface.

23. A torque transmission device according to Claim 22 characterised in that detent means to hold the carrier in position when said carrier is moved in a selected one of said of opposite directions.

24. A torque transmission device according to Claim 23 characterised in that the detent means comprises a catch member mounted on the cam member and a recess on the carrier.

25. A torque transmission device according to Claim 24 characterised in that the catch member comprises a spring having a ball attached thereto for engagement in the recess.

26. A torque transmission device according to Claim 14 characterised in that the rollers and the resilient urging means are mounted on the cam member, and the resilient urging means comprises a resilient urging member for each roller.

27. A torque transmission device according to Claim 26 characterised in that the cam member includes a plurality of walls each extending transversely to a respective one of the cam faces, whereby each roller is urged by a respective resilient urging member away from the respective wall along the respective cam surface towards the engagement surface.

28. A torque transmission device according to Claim 26 or 27 characterised in that an insert received in a bore through the cam member, the insert being movable between first and second positions in which a portion of the insert projects outwardly from opposite sides of the cam member in, respectively, each of said positions.

29. A torque transmission device according to Claims 26, 27 or 28 characterised in that each resilient urging member may be in the form of a spring, for example, a compression spring.

Drawing