The invention relates to ratchet wrenches (often referred to in the United Kingdom as spanners) and particularly to pass through ratchet wrenches (pass thru in the US).
Known ratchet wrenches may comprise a wrench head that houses a driven member. The driven member may be provided with an aperture shaped to receive an item that is to be driven. For example, the aperture may be a hexagonal aperture sized to receive a particular size of fastener head/nut. Alternatively, the driven member may comprise a spigot that projects from the wrench head to allow the wrench head to be connected to a drive socket or the like. A resilient annular clutch may be disposed between the wrench head and driven member to transmit an applied torque from the wrench head to the driven member. When the wrench handle is turned in the drive direction to apply a torque to a fastener of the like, the clutch is deformed to lock the wrench head to the driven member to transmit the torque. When the wrench handle is turned in the opposite direction, the clutch springs back to allow relative movement of the wrench head and driven member to all repositioning of the wrench handle.
In order to avoid having an overly large wrench head, the resilient annular clutch may be a relatively thin sprung ring, which when subjected to repeated high torques is deformed to such an extent it becomes ineffective.
The annular clutch may have a series of fine teeth on its outer side to engage correspondingly fine teeth on the wrench head. There may for example be at least one hundred teeth on the annular clutch. Since such teeth are relatively fine, even a small amount of deformation of the annular clutch, for example as little as 0.01% makes it particularly likely to fail properly engage the teeth on the wrench head. Manufacturing a relatively thin annular clutch with fine teeth is not straightforward. One potential manufacturing method is metal injection moulding MIM. MIM parts are moulded from metal particles held together with a percentage of plasticiser or wax. The moulded parts are subjected to a very high temperature in a vacuum oven during which the metal particles fuse and the plasticiser is burnt and vacuumed off. Even differences as small as 0.02% in the process produces variations in the finished size that may cause misalignment of the teeth when the annular clutch ring is forced into engagement with the wrench head.
A further problem with such ratchet wrenches is that the ingress of fine dust or grit quickly fouls the ratchet mechanism.
It is an object of the invention to at least partially alleviate one or more of the above-mentioned problems, or to provide an alternative to existing products. Embodiments of the invention may provide a lower profiled pass through ratchet wrench than any other currently available on the market, whilst attaining or exceeding the current torque standards and in particular enabling a more cost effective and reliable product.
The invention provides a ratchet wrench as specified in claim 1.
The invention also includes a ratchet wrench as claimed in claim 17.
The invention also includes a ratchet wrench as claimed in claim 18.
The end of the handle has a biasing profile for interaction with at least one biaser, which may be a spring and ball detent, the biaser acting to provide a direction bias and the initial grip in the required drive direction of the clutch ring upon the drive element. In the rest position of the wrench, the biaser provides a biasing force to provide initial clamping of the clutch ring to obviate any slack or play inherent in normal ratchets.
When the handle is operated in the reverse or reposition direction, the actuator releases its initial or direction biasing force against the abutting clutch actuation face alleviating the biasing springs resilient force partially freeing the clutch inner surface from the drive portion. The action of the drive portion being rotated against any clamping friction of the clutch ring further rotates the clutch outer ramps away from the corresponding housing ramps allowing the clutch ring to expand further, negating the grip of the clutch ring upon the driven member drive surface, usefully allowing the drive portion or shaft to be reversed or repositioned. The magnitude of the clutch engaging spring force is directionally proportionate to that of the detent resilient portion, to that end the clutch ring generally requires to be thin in section and made from resilient material like high grade spring steel. The device is designed such that the clutch ring forms the mid part of an extremely strong laminate like structure, under torque conditions, the resultant compression forces applied to the clutch ring are substantially dissipated around its circumference. The resultant pseudo laminate like construction of the drive, clutch, and housing enables a proportionately far stronger or a thinner lighter device.
The invention may include a ratchet wrench wherein the drive element can usefully have further drive inserts. In one example the drive inner surface could engage and operate say a 19 mm fastener, by the advantageous use of further drive inserts many smaller or larger fastener head sizes and types can be operated utilizing the same ratchet mechanism whilst usefully retaining a low drive portion profile. The inserts in best practice having a sufficient sized through-hole that fasteners operated on say a screwed rod can be usefully operated, the screwed rod protruding through the through-hole during use.
If the outer radiuses of the drive teeth have minimal radius, their locking engagement with the smooth section of the clutch ring will be measurably enhanced.
The size and shape of the housing ramps and clutch transmission ramps may be chosen to ensure that they cannot completely disengage from one another when the ratchet wrench is used in the reverse direction.
In order to achieve utmost drive tooth contact with the inner sidewall of the clutch ring, it is desirable that the innermost circumferential profile of both the toothed section, and smooth section of the clutch sidewall are identical. To that end, the clutch's inner smooth section profile is substantially the same as the inner height of the teeth of the toothed section, a further aid being the tops of the outer toothed wall of the drive portion are preferably radiused or near flat topped, the “flat top” being substantially the same circumferential profile as the inner sidewall of the clutch's smooth section.
If the outer tips of the drive teeth have a minimal radius, their locking engagement with the smooth section of the clutch inner sidewall will be measurably enhanced.
The operating angle of the housing ramps and the clutch transmission ramps may be between eight and thirty degrees.
Having a partially toothed engagement portion between the clutch inner surface and the toothed outer surface of the drive element may substantially reduce the problem of the clutch ring elongation and the problem of tooth mismatch due to manufacturing difficulties, thereby reducing the manufacturing and warranty costs.
The parts of the wrench head may be constructed in a quasi-laminate manner. This structure may provide an inherently stronger mechanism, thus permitting superior torque and useful head size reduction. Laminates are inherently stronger than similar thickness materials due to the utilisation of using metal grain structures in dissimilar grain directions (cross grain).
A match between the clutch toothed portion, and the clutch smooth portion profiles as they mesh with the drive toothed profile when operated in the drive direction ensures a pseudo laminate-like construction. The housing ramps also match the transmission ramps in a similar manner. The drive ramps may equalise the compression and stresses imparted upon the clutch ring and drive element in an inward direction i.e. compression in the drive direction. When the wrench is operated in the reverse or reposition direction, the clutch transmission ramps move down the housing ramps within the confines of the housing ramp walls and the clutch transmission ramp shoulders which limit the closing of the gap created when they abut. This permits clutch ring expansion into the gap, which provides delamination during the reverse action allowing the now lightly engaged clutch toothed portion to effortlessly traverse the drive teeth.
Embodiments of the invention allow the housing depth to be reduced, allowing the operation of the ratchet in situations unavailable to other prior art ratchet wrenches, whilst still passing the relevant torque standards.
When the wrench head is at rest, the clutch toothed portion is already biased into the corresponding drive teeth by the at least one biaser in order to provide as far as possible instantaneous engagement or meshing with the drive teeth when the wrench head is turned in the drive direction.
The housing enclosure strength may be enhanced by the use of protrusions and recesses placed strategically around the housing aperture. The protrusions or their corresponding recesses can be on either housing face, fitting snugly into one another they provide the housing with the ability to be substantially reduced in profile yet retain strength and robustness.
The housing strength may be enhanced by the fact that the main locking forces are directed inwards upon the extremely strong drive element circumference, further reducing the need for thick housing walls.
The housing may comprise top and bottom housing portions secured against one another by a snap ring type retainer within a retaining clip channel within the drive element. The drive element may have a retaining flange. Alternatively, or additionally, the top and bottom housings may be secured to one another by rivet upstands incorporated within the top or bottom housing portions, the opposing housing portion having a countersunk hole for the retention of the rivet head profile. By incorporating the rivet fixing within the housing moulding and thereby virtually obviating the chance of a separate rivet or screw coming loose from the head portion the device is ideal for use in the aerospace industry as the incidence of foreign objects being left in problem areas is further reduced.
The top and bottom housings can be produced as mirror copies of one another to reduce costs and inventory. One housing portion may have housing closure holes and the other mating housing closure protrusions. The manufacturing method in one example may be by precision metal injection moulding MIM. The fixings could be rivets within countersunk holes, the rivets having centre holes for the ease of precision splaying.
The housing may comprise the top and bottom housing portion and these and the clutch ring and drive element may be produced by metal injection moulding MIM. This process allows the parts to be mass produced in great numbers with great precision. The drive teeth can easily be over 120 in number whilst the profiles of the teeth remain accurate.
In order to further reduce the overall working depth of the wrench head, the depth of the inserts can be of a reduced height compared to known inserts. The use of reduced height square drive inserts with compatible low profile sockets would greatly increase capability of the ratchet wrench to work in restricted access areas.
The housing depth for a ¼ inch square drive may be less than 8 mm.
The housing depth for a ¼ inch square drive may be less than 7 mm.
The housing depth for a ¼ inch square drive may be less than 6 mm.
The housing depth for a ⅜ inch square drive may be less than 11 mm.
The housing depth for a ⅜ inch square drive may be less than 10 mm.
The housing depth for a ⅜ inch square drive may be less than 9 mm.
The housing depth for a ⅜ inch square drive may be less than 8 mm.
The housing depth for a ½ inch square drive may be less than 12 mm.
The housing depth for a ½ inch square drive may be less than 11 mm.
The housing depth for a ½ inch square drive may be less than 10 mm.
In order that the invention may be well understood, some embodiments, which are given by way of example only, will now be described with reference to the drawings, in which:
The drawings are not necessarily to scale and, some features may be exaggerated to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as being limiting, but merely as a basis for the claims.
The clutch portion 500 having a said generally smooth inner surface 504 with in best practice a said toothed 501 tail portion 506 and a said outer surface 507 with said ramp like protrusions 502 corresponding to said like ramps 206 within the said inner surface of the housing 208. When the said handle or drive shaft 30 is further operated in the said drive or locking direction D the said partially toothed 501 and smooth 504 inner surface 508 of the said clutch 500 having initially resiliently clamped the corresponding said toothed 401 profile of the said circumferential surface 405 of the said driven member 400 in order that when additional torque is applied in the said drive direction D to the said handle 30 or drive shaft (not shown) the said clutch portion 500 is further urged inwards as the said clutch ramp protrusions 502 usefully engage the corresponding said inner housing ramps 206, further propelling the said inner surface 508 of the said clutch ring 500 inwards upon the said outer surface 405 of the said central drive portion 400 and if required its said drive insert 408 enabling the said engaged fastener 80 to be robustly driven. In order to optimise the said clutch 500 initial said inner surface 508 grip upon the corresponding said drive portion 400 said outer circumference 405 the said toothed portion 501 of the said clutch 500 has said teeth 510 which interlock with the similar pitch and profile of the said drive teeth 401.
Operating the handle 30 in said reverse or reposition direction R the said actuator 34 releases its initial or direction biasing force clamping the said clutch inner surface 508 upon the said drive element circumference 405 provided by the said detent resilient portion 60,61 acting to free the said clutch ring 500 from the said drive portion outer circumference 405. The action of the said drive portion 400 being rotated against the clamping friction of the said clutch ring 500 further rotates the said clutch outer ramps 502 away from the said corresponding housing ramps 206 allowing the said clutch ring 500 to expand negating the grip of the said clutch ring 500 upon the said driven member drive surface 405 usefully allowing the said drive portion 400 to be said reversed or repositioned R. The magnitude of the clutch 500 engaging spring force is directionally proportionate to that of the detent resilient portion 60, to that end the clutch ring 500 generally requires to be thin in section and made from resilient material like high grade spring steel. The ratchet wrench 1 is designed such that the said clutch ring 500 forms the mid part of an extremely strong laminate like structure, under torque conditions the resultant compression forces applied to the said clutch ring 500 are substantially dissipated around its said circumference 507. The resultant pseudo laminate like construction of the said drive 400, clutch 500 and housing 201, 202 enables a proportionately far stronger or alternately a thinner lighter device.
The invention expressly comprises a “pass thru” ratchet wrench 1 wherein the said drive element 400 can have further drive inserts 408 fitted. In one example the said drive inner surface 412 could engage and operate say a 19 mm fastener, by the advantageous use of further said drive inserts 408 many said further fastener head sizes 410 and types can be operated utilising the same said ratchet wrench 1 whilst usefully retaining a low said housing 200 profile.
Number | Date | Country | Kind |
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1519500.1 | Nov 2015 | GB | national |
Filing Document | Filing Date | Country | Kind |
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PCT/GB2016/053445 | 11/4/2016 | WO | 00 |