RATCHET WRENCHES

Abstract

The ratchet mechanism comprises a head portion with a circular central housing, the inner surface adjoining the handle portion having a further recess characterized by a plurality of engagement ramp profiles arranged not unlike low angled gear teeth within the recess arc. A pawl is located within the recess, with a corresponding plurality of engagement ramp profiles abutting the recess engagement ramp profiles and incorporating an inner facing toothed face of similar corresponding pitch and profiles as the drive element teeth in order that they can mechanically mesh into one another when ratchet is operated in the drive direction, the pawl inward force being substantially evenly distributed along the pawl toothed front face by the use of several similar engagement ramp profiles urging all the pawl teeth into the required locking engagement with the drive element simultaneously.

Claims

1. A ratchet wrench comprising: a handle having a head end; a head portion connected to said head end and provided with a circular drive element housing, said head portion having a pawl recess disposed between said drive element housing and said head end; a drive element at least partially housed in said drive element housing and having a toothed portion comprising teeth disposed circumferentially about said drive element; and a pawl located within the pawl recess, the pawl having a plurality of engagement ramp profiles configured to engage respective ramp surfaces provided in said pawl recess and a toothed face facing into said central housing and provided with a plurality of teeth configured to mesh with oppositely disposed teeth of said drive element toothed portion, wherein the arrangement is such that, in use, when a drive force is applied to said handle, a plurality of said engagement ramp profiles engage with the respective ramp surfaces to urge the pawl into locking engagement with the drive element.

2. The ratchet wrench claimed in claim 1, wherein said engagement ramp profiles comprise a first set of engagement ramp profiles inclined in a first direction for engagement with the respective ramp surfaces when, in use, the head portion is rotated in a first direction and a second set of engagement ramp profiles inclined in a second direction for engagement with the respective said ramp surfaces when, in use, the head portion is rotated in a second direction that is opposite to said first direction.

3. The ratchet wrench claimed in claim 1, wherein the said engagement ramp profiles are inclined in one direction so as to be uni-directional whereby the engagement ramp profiles engage the respective ramp surfaces to urge the pawl into locking engagement with said drive element when, in use, said head portion is rotated in first direction but not when said head portion is rotated in a second direction that is opposite to said first direction.

4. The ratchet wrench claimed in claim 1, 2 or 3, wherein said drive element housing is partially defined by an arcuate wall of the head portion, said arcuate wall being configured to be resiliently deformable when in use, said pawl lockingly engages said drive element.

5. The ratchet wrench claimed in any one of the preceding claims, wherein when said pawl lockingly engages said drive element, said toothed face engages said toothed portion of the drive element over a subtended angle in the range 40 to 80 degrees.

6. The ratchet wrench claimed in any one of the preceding claims, wherein the head portion has a height, the drive element housing has a height at least substantially equal to the height of the head portion, the teeth of the drive element toothed portion have a height at least substantially equal to the height of said drive element housing and the teeth of the pawl have a height at least substantially corresponding to the height of the teeth of the drive element.

7. The ratchet wrench claimed in any one of the preceding claims, wherein said drive element teeth have respective radiused tips having a curvature at least substantially corresponding to the curvature of the circular drive element housing.

8. The ratchet wrench claimed in any one of the preceding claims, wherein opposite ends of said drive element are provided respective flanges and said head portion is held between said flanges.

9. The ratchet wrench claimed in claim 8, wherein one said flange is defined an annular member secured in abutting relationship with a plurality of rivet upstands that are integral with the drive element, the annular member having respective countersunk hole to receive the heads of respective rivets engaged in said rive upstands.

10. The ratchet wrench claimed in claim 8 or 9, wherein at least one of said flanges is configured as a thumb when to enable rotation of said drive element by a user.

11. The ratchet wrench claimed in claim 8, 9 or 10 further comprising respective sealing members disposed between the flanges and the drive element.

12. The ratchet wrench claimed in any one of the preceding claims, wherein said pawl is biased into engagement with said drive element by a torsion spring secured to said wrench head.

13. The ratchet wrench claimed in any one of the preceding claims, wherein said engagement ramp profiles and the respective ramp surfaces are configured such that they cannot completely disengage when, in use, the wrench head is rotated in a reverse direction in which said pawl teeth slide over said toothed portion of the drive element.

14. The ratchet wrench claimed in any one of the preceding claims, wherein when, in use, said pawl is in locking engagement with the drive element, said drive element, pawl and drive element housing wall engage so as to form of a pseudo-laminate structure.

15. A ratchet wrench comprising: a handle; a wrench head housing a drive element; and a pawl engageable with teeth provided on said drive element to lock said drive element to said wrench head to permit a torque input to said handle to be transferred to said wrench head, wherein the pawl has a plurality of engagement ramp profiles and said wrench head has respective ramp surfaces engageable with said engagement ramp profiles, and wherein, in use, a plurality of said engagement ramp profiles simultaneously engage the respective ramp surfaces.

16. A ratchet wrench as claimed in claim 15, wherein said drive element has a circumference and said ramp surfaces are inclined in the circumferential direction of said drive element.

17. A ratchet wrench as claimed in claim 16, wherein adjacent said ramp surfaces are inclined so as to be at an angle of less than ninety degrees to one another.

18. A ratchet wrench as claimed in claim 15, 16 or 17, wherein said wrench head has a C-shaped wall that extends about said drive element and is configured to deform when, in use, said pawl locks said drive element to said wrench head.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order that the invention may be well understood, some embodiment thereof, which are given by way of example only, will now be described with reference to the drawing in which:

[0037] FIG. 1 is a perspective view of the ratchet wrench having a switch and a drive element having a spigot for connection with known sockets and the like:

[0038] FIG. 2 is a perspective view of a ratchet wrench having a switch and a fastener receiving drive element:

[0039] FIG. 3 is an exploded perspective view of the ratchet wrench shown in FIG. 1;

[0040] FIG. 4 is a top view of the ratchet wrench of FIG. 1 with the closure washer removed and a part of the handle shown in section;

[0041] FIG. 5 is a view corresponding to FIG. 4 showing the ratchet wrench operated in the reverse direction;

[0042] FIG. 6 is a view corresponding to FIG. 4 showing the ratchet wrench operated in the drive direction;

[0043] FIG. 7 is a close-up view of the circled portion of FIG. 6;

[0044] FIG. 8 is a perspective view of the drive element and pawl of the ratchet wrench of FIG. 1;

[0045] FIG. 9 is a top view of a single direction ratchet wrench with the closure washer removed to reveal the ratchet mechanism;

[0046] FIG. 10 is an exploded perspective view of the drive element, closure washer, single direction pawl and spring; and

[0047] FIG. 11 is a cross-sectional plan view of a prior art ratchet wrench.

DETAILED DESCRIPTION

[0048] There follows a description of embodiments of the invention. It is to be understood that the disclosed embodiments are merely examples of the implementation of the invention, which may be embodied in various other forms. The figures are not necessarily to scale, as some features may be exaggerated to show details of particular components. Therefore, specific structural and functional details disclosed herein are to aid understanding of the invention and not interpreted as being limiting.

[0049] FIGS. 1-10 illustrate the embodiments of a ratchet wrench 1 comprising a head portion 300 having a generally circular drive element housing 312 in which a drive element 200 is at least partially received, an elongate handle 400 having a hand grip end 401 and a head end 402. A pawl recess 306 extends from the inner surface 303 of drive element housing 312 towards the head end 402 of the handle 400. The pawl recess 306 is provided with a plurality of ramp surfaces 307 configured as low angled teeth. A pawl 500 is located within the pawl recess 306.

[0050] The pawl 500 is provided with a plurality of engagement ramp profiles 503 abutting the ramp surfaces 307. The pawl 500 has a toothed face 501 facing into the drive element housing 312. The teeth 502 of the toothed face 501 are configured to mesh with drive element teeth 202 of a circumferentially extending toothed portion 201 of the drive element 200 so that the toothed face 501 can transmit a torque input via the handle 400 to the drive element when a turning force in the drive direction D is applied by a user. The rear face 504 of the pawl is provided with a flange 505 disposed within a recess 309. The recess 309 opens into the pawl recess 306 and is disposed between the pawl recess and the head end 402. The flange 505 defines a biasing face 506 that comprises two end stops 507, 508 disposed at opposite ends of the biasing flange and a guide face 509 disposed between the end stops.

[0051] FIGS. 1 and 2 illustrate two versions of a ratchet wrench 1 having the same ratchet mechanism. The example shown in FIG. 1 has a drive element 200 with a spigot 203 and the example shown in FIG. 2 has a drive element 200 with a fastener operating profile 204 configured to receive and engage a fastener.

[0052] Optionally a direction setting switch 600 is provided. The switch 600 comprises an operating lever 601 which may be similar to operating levers of prior art switches and a switch axle 602 disposed for rotation within a switch bore 310 provided in the head portion 300. The switch axle 602 is provided with a blind cross bore 603 that houses a pressing member 604 and a biasing spring 607 that biases the pressing member outwardly with respect to the open end of the cross bore 603. The pressing member 604 is a sliding fit in the cross bore 603. The pressing member 604 comprises a shaft 605 disposed within the spring 607 and an operating face 606 disposed externally of the cross bore 603. The operating lever 601 of the switch 600 is disposed within a switch lever recess 311 defined in the head portion 300. The switch lever 601 is rotatable back and forth in the switch lever recess 311 to move the pressing member 604 between the end stops 507, 508 in order to bias the engagement ramp profiles 503 of the pawl 500 against the ramp surfaces 307 in the pawl recess 306 in order to set a clock or anti-clockwise drive direction D. The pawl 500 is resiliently urged into pawl engagement PE with the drive element 200 by the biasing spring 607 and pressing member 604 resiliently acting against the pawl biasing face 506.

[0053] In the reverse, or reposition, direction R, the pawl 500 is propelled in the pawl disengagement direction PD so that the drive element teeth 202 can slide over the pawl teeth 502 against the biasing force of the switch spring 607. As shown in FIGS. 9 and 10, when the ratchet mechanism is configured as an un-switched, or single direction, mechanism, the pawl 510 may be resiliently urged into engagement PE with the drive element teeth 202 by a low-cost torsion type spring 515 positionally retained by a suitable pin 516. One end 517 of the spring 515 acts against the undercut sidewall of the recess 309 and the opposing end 518 acts against a biasing face 514 of a rearwardly facing flange 513 of the pawl. In the reverse, or reposition, direction R, the pawl 510 is propelled in the pawl disengagement direction PD allowing the drive element teeth 202 to slide over the teeth 502 of the pawl 510 against the biasing force of the torsion spring 515.

[0054] FIG. 3 is an exploded perspective view of the ratchet wrench 1 of FIG. 1. The parts shown include the handle 400 and its hand grip end 402, the head portion 300, head portion outer surface 301, housing wall 302, inner surface 303, pawl recess 306, pawl recess dual direction engagement ramp profiles 307, recess 309, switch bore 310 and switch arm recess 311. The drive element 200 has a circumferentially extending toothed portion 201 having teeth 202, a spigot 203, retaining flange 205, sealing ring groove 206, seal 207, flange 208, thumbwheel profile 210, retaining screws 214 and screw holes 215. The pawl 500 toothed face 501 having teeth 502, dual direction engagement ramp surfaces 503, rear face 504, flange 505, biasing face 506, first and second end stops 507, 508 and the guide face 508 between. The switch 600 with its operating lever 601, axle 602, pressing member 604 and biasing spring 607.

[0055] Referring to FIG. 6, the ratchet wrench 1, a potential width reduction of the housing wall 302 of the head portion 300 is shown. The housing wall 302 may be made from suitable spring steel in order to provide a resiliently deformable wall portion 305. When the ratchet wrench 1 is operated in the drive direction D, the pawl 500 is driven in the pawl engagement PE direction so that the pawl engagement ramp profiles 503 (FIGS. 1 and 2 versions) or 511 (FIGS. 9 and 10 version) are pressed against the pawl recess ramp surfaces 307 (FIGS. 1 and 2 versions) or 308 (FIGS. 9 and 10 version) so that the toothed face 501 of the pawl 500 is driven inwardly with respect to the drive element housing 312 against the circumferentially extending drive element toothed portion 201 to lock the drive element 200 within the head portion 300. The drive element 200 is configured so as to be capable of limited lateral movement against the inner surface 303 of the drive element housing 312 so that the drive element teeth 202 can firmly engage the inner surface 303 of the central housing 312 opposite the pawl recess 306 (see FIG. 7). When a force is applied to hand grip end 401 of the handle 400 in the drive direction D, the inward force IF exerted by the drive element 200 may deform the resiliently deformable wall portion 305 of the head portion 300 inwardly upon the toothed portion 201 of the drive element 200 resulting in a superior clamping force CF action between the drive element and the abutting portion of the housing wall 302. The teeth 202 of the drive element 200 may have substantially flat tips 211 as an aid to the clamping force CF gripping action provided between the drive element toothed portion 201 and the housing inner surface 303 of the housing resiliently deformable wall portion 305, so that the drive element 200, pawl 500 and head portion housing wall 302 form of a pseudo-laminate structure when utilized in the drive direction D. This structure provides an inherently stronger ratchet mechanism and wrench head portion size-for-size compared to prior art wrench head portions, thus permitting superior torque transmission by relatively smaller head portions 300. The pseudo-laminate like structure of the drive element 200, pawl 500 and drive element housing 312 enables the provision of a proportionately far stronger or a thinner lighter wrench head. Furthermore, the head portion 300 strength is enhanced by the fact that the main locking forces IF, CF are directed inwards onto the inherently strong circular drive element toothed portion 201. A further aid to locking engagement between the housing inner surface 303 and the drive element toothed portion 201 is obtained by the teeth 202 having tips that are radiused so as to be near flat and having the same profile as the inner surface 303 of the drive element housing 312.

[0056] FIGS. 3, 8 and 10 show the drive element toothed portion 201 will be substantially the same height as the head portion housing wall 302. The depth, or height of the toothed face 501 of the pawl 500 is also is substantially the same as the height of the head portion housing wall 302, thereby further maximising the pawl 500 to drive element tooth 202 to pawl tooth 502 engagement contact area.

[0057] The drive element 200 is retained in the drive element housing 312 between two relatively thin flanges 205, 208 (best seen in FIG. 3). Preferably, one of the retaining flanges 205 is integral with the drive element 200. The other flange 208 is defined by a closure washer releasably secured to the drive element 200 by screws 214 that engage in screw holes 215 provided in the drive element. The configuration of the parts is such as to allow the drive element 200 to move laterally within the drive element housing 312 according to the specified tolerances. The use of screws 214 to secure the flange 208 to the drive element 200 allows it to be conveniently removed in order to access or service the ratchet mechanism.

[0058] FIG. 10 further illustrate how the flange 208 may be secured against one another by rivet upstands 212 incorporated within the drive element mating surface 216, the closure washer 208 preferably having countersunk holes 217 for the retention of the splayed rivet head 212. By incorporating the rivet fixing 212 within the drive element mating face 216 and thereby virtually obviating the chance of a separate rivet 212 or screw 214 coming loose from the drive element 200 the ratchet wrench is ideal for use in the aerospace industry as the incidence of foreign objects being left in problem areas is further reduced. The rivet protrusions 212 could be further usefully enhanced by the use of central holes 213 for the ease of precision splaying during the production process.

[0059] FIGS. 3, 8 and 10 further illustrate the ratchet wrench 1, which can be completely sealed in order to prevent harmful moisture or detritus ingress. The drive element 200 is retained in the head portion 300 between two flanges 205, 208. The flanges 205, 208 retain the drive element 200 within the drive element housing 312 whilst usefully allowing the drive element 200 to move laterally according to the allowed tolerances. The inner surface of the flanges 205, 208 may be provided with respective grooves 206, 209 near their periphery, in which an appropriate seal 207 can be located. The seals 207 usefully act against the upper and lower smooth flat housing faces 313 outwith the pawl recess 306, in order to provide an efficient method of preventing detritus or moisture damaging the wrench head. A further groove 608 and seal 609 can be located within the switch axle 602 of the switch 600 in order to advantageously complete the sealing action when a switch 600 is fitted.

[0060] FIGS. 5, 6, 9 and 10 further illustrate the ratchet mechanism 1, whereas the said engagement ramp profiles 308, 511 are single toothed or shark fin like profiled in order that the ratchet action can be utilized in only one direction whereas no switch 600 function is required. Furthermore when the present invention is utilized as a un-switched or single direction ratchet the pawl 510 can be resiliently urged into pawl engagement PE between the said pawl 510 and the drive element teeth 202 by a low cost torsion type spring 515 positionally retained by a suitable pin 518, one end of the said spring 518 resiliently acting against the undercut sidewall 309, the opposing end of the said spring usefully resiliently acting against the pawl rear protrusion 513 biasing face 514. In the reverse or reposition direction R the said pawl 510 is propelled in the pawl disengagement direction PD whereas the drive element teeth 202 can resiliently slide over the said pawl 510 teeth 502.