Patent Grant
12048987
The present application claims priority to PCT application PCT/EP2020/062176 filed on Apr. 30, 2020, which is a PCT application of Great Britain patent application no. 1906089.6, filed on Apr. 30, 2020.
The invention relates to dual direction ratchet mechanisms used in screwdrivers and wrenches (often referred to in the United Kingdom as spanners).
Ratchet wrenches may comprise a wrench head that house 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. The driven member may have a circumferentially extending surface provided with a series of teeth that are engageable by the teeth of a pawl that is further located within a recess within the wrench head, the leading edge or edges of the pawl or pawls are generally wedge shaped, as are the ends of the recess that the pawl is situated in. The engagement between the pawl and teeth is such that if the wrench head is turned in a first direction the rotation of the wrench head is transmitted to the driven member in a locking manner as the corresponding pawl wedge shaped leading edge engages the said matching pawl recess end ramp. If the wrench head is turned in a second (opposite) direction the pawl resiliently slides over the teeth on the driven member against a spring used to urge the said pawl against the driven member teeth.
By this means the wrench can apply a torque to an item by turning the wrench head in the first direction and the wrench handle can be repositioned with respect to the item by turning the wrench head in the second direction. Wrenches of this type may be provided with a pair of pawls or a pawl with ramps at either ends, the pawl being selectively engageable with the driven member by means of a switch, the torque applying and handle repositioning directions of the wrench can be reversed by operation of the switch.
The majority of current prior art switchable wrench ratchets incorporate a central drive element portion having a circular toothed circumference which engages a corresponding toothed pawl which is appropriately spring biased in the chosen direction by a switch against two appropriately angled wedge ramp faces formed in the ratchet head housing against which the corresponding pawl wedge shaped outer ramp portions can be resiliently urged. The switch shaft further incorporates a bore containing a spring and plunger, the plunger is in contact with the back of the pawl opposite its front engagement teeth. The plunger, pawl contact area is formed into an arced cam with end walls such that the rotation of the switch with its incumbent spring and plunger urges the plunger against the end wall from one end wall to the other resiliently projecting the particular pawl wedge shaped outer contact portion against the required housing wedge shaped ramp portion in order to provide a suitable locking function when the ratchet is utilized in the chosen drive direction as the wedging of the pawl usefully urges the pawl teeth against the teeth of the drive portion effectively locking the drive portion within the housing. In the chosen reverse or reposition direction the housing wedge shaped ramp is caused to separate from the pawl wedge shaped ramp by the drive element teeth acting upon the pawl teeth, the switch spring and plunger resiliently urging the pawl teeth against the drive portion teeth, the typical ratchet clicking noise is caused by the corresponding teeth disengaging and engaging as they travel over one another in the reverse direction. In the drive direction the pawl as it is projected against its corresponding housing wedge shaped ramp, however the pawl teeth only truly robustly engage at or near the actual wedge shaped end contact areas, hereinafter termed engagement ramps, equivalent to approximately 40 deg. or less of the drive element teeth, the normal point of failure of most ratchets is due to over torque usage, wear or fouling of the ratchet pawl teeth, the more or larger the teeth completely engaged the less the wear or over torque problem.
As correctly illustrated in FIG. 4 U.S. Pat. No. 9,545,705 Hu when a bi-directional pawl is utilized less than half of the pawl teeth completely engage the analogous drive element teeth, furthermore this is also a similar characteristic of single direction ratchets, if the pawl and housing recess engagement ramp angles were to be modified in order to substantially improve the teeth engagement, the pawl would tend to problematically jam against the pawl recess engagement ramp, empirical testing over many years having led to this compromise. The current useable lifecycle of such a ratchet using a prior art pawl is two years in a busy professional automotive workshop environment, the pawl and its spring being classed as a consumable item.
U.S. Pat. No. 6,530,296 Liao discloses a unidirectional ratchet mechanism for a wrench utilizing a sprung ring 30 to urge a plurality of toothed pawl blocks 40 from the confines of their slots 23 evenly spaced around the central fastener drive 20 periphery into the fixed corresponding teeth 13 of the wrench head housing 12. However, the over reliance on the sprung ring 30 to retain the pawl blocks 41 teeth competently engaged with the housing teeth 13 during any high torque use of the wrench is problematic.
U.S. Pat. No. 9,140,317 Buchanan denotes a multiple pawl ratchet either one direction or dual direction, in the drive direction the pawls 46 including ramps 62 for interaction with corresponding ramps 44 within the central drive fastener or spigot wheel 134 the pawls 46 being urged into engagement in the drive direction by a sprung split ring 52 with tabs 54, the outer face of the split ring resiliently engages the sidewall 30 of the inner head housing 18. The sprung split ring tabs interact with the pawls to urge them up the ramps into toothed engagement with the correspondingly toothed driven member 134 usefully locking the ratchet in the drive direction.
In the reverse or reposition direction the pawls are driven down and out of contact with their corresponding ramps providing a ratchet like reverse sequence. In the dual direction example, the position of the pawls 376 within their dual ramped slots 330 within the ratchet head housing 316 are defined by the split ring 398 having sprung ends 400 which interact with a switch portion 412 to bias the sprung split ring 398 in the chosen drive direction, the said sprung split ring 398 having tabs located at either end of the corresponding pawls 376 which position the pawls 376 into engagement or disengagement positions as required. The switchable version requires substantial machining of the head portion inner profile and a large, screwed cover plate attached by screws incurring considerable expense in manufacture.
US 2015/0135908 Solar et al. is restricted to a unidirectional ratchet similar in most respects to U.S. Pat. No. 9,140,317 Buchanan, the pawls 18 being biased by a torsional spring ring 14 or separate compression springs as in the prior art.
Ratcheting screwdrivers have an inherent problem of low torque levels and or high reverse to drive angles, U.S. Pat. No. 9,511,484 overcomes the problem of inadequate drive pawl to shaft driven teeth torque by the use of a series of three annular beveled drive and driven gears, in use in the chosen drive direction the driven gear is engaged on the screwdriver shaft, the driven gear has annular beveled teeth on both faces, the required drive gear engaged to the handle portion, is propelled into engagement by a relevant spring, in the reposition or ratchet operation the beveled gear teeth are driven up the slopes of the interacting drive and driven gear teeth against the resilience of the relevant spring allowing a suitable ratchet action to be accomplished. However, this high torque mechanism is extremely complex and expensive both to manufacture and assemble having a minimum of 25-30 parts resulting in a tool with a very niche restricted marketplace, furthermore the use of beveled gear profiles mean that the gears have built in unwanted play as the interacting gears ride up the beveled faces of the opposing drive to driven gears into and out of engagement.
A further problem with prior art ratcheting screwdrivers is their switches are non-intuitive in that the direction defining switches are switches are operated in the opposite direction to the drive required.
It is a further object of the present invention to at least partially alleviate the above mentioned disadvantages, or to provide an alternative to existing products. In particular, to provide a dual direction ratchet with lower engagement angles than any other currently available on the market, or being capable of exceeding the current torque standards, in particular to allow the manufacturer of a more cost effective and reliable product.
The invention provides a fastening tool ratchet mechanism comprising:
The invention provides a ratchet mechanism comprising a central drive element. A head portion having a central chamber in which said drive element is received, an elongate handle or operating member having a hand gripping end and a levered head portion end. The head portion having a generally circular central chamber, the inner surface of which adjoining the handle portion having a further recess or connection undercut for the connection to the direction biasing switch by the resilient switch plunger. The head portion chamber further having modular inserts in the form of preferably three layers, two outer fixed ramped profile layers, with a sequential actuating layer capable of limited rotation between the fixed layers. The actuating layer resiliently propelled in the chosen clockwise or anticlockwise direction by in one example a known ratchet switch incorporating a sprung plunger whose engagement face acts against the said actuating layer chosen direction profile. The fixed ramped profile layer having outer locking notches which mechanically engage with the corresponding head portion locking profiles, the said fixed profile further utilizing ramped profiles within its central profile, preferably three sets of generally equally spaced opposing direction pawls are situated within said corresponding ramped profiles. The middle sequential actuating layer has preferably close contact engagement and disengagement profiles at either end of its pawl recesses, these said profiles project in the chosen direction the incumbent pawls against the corresponding fixed layer ramped profiles in the chosen clockwise or anticlockwise drive direction whilst simultaneously disengaging the pawls facing in the opposite direction, the said pawls outer ramped profile acting against the corresponding fixed layer pawl ramped profile in the chosen drive direction, the drive engaged pawls teeth forced into engagement with the drive element teeth in order to drive as required the same, the opposing disengaged pawls simultaneously propelled as required from drive element contact into the further recess formed within the wide end of the fixed layer ramped profiles, further effected by the reclining shape of the opposing pawl and drive element teeth. When utilized in the reverse or reposition direction the actuating layer with its incumbent pawls, resiliently circumferentially rotating against the said resilient sprung plunger, further allowing the pawl teeth engaged within the drive element teeth to resiliently slide over one another during the reposition action.
The present invention is characterized by the use of a mid-located, sequentially actuating layer, in the preferred iteration being both planar and ring like in construction in order that it can be stamped or fine blanked in manufacture instead of using expensive machining.
The present invention utilizes a preferably mid located, sequentially actuating layer, characterized by the actuation layer having a biasing protrusion incorporating a sprung plunger transfer profile with directional profiles incorporated at its outer ends.
The present invention utilizes a preferably mid located, sequentially actuating layer incorporating a biasing protrusion, which is further characterized by inwardly relieved scallops usefully forming plunger contact retaining indents within their directional profiles, further usefully preventing the switch from disengaging from its ordained operating position particularly when the present invention is rapidly utilized in the reverse or reposition direction.
The present invention is further characterized by the use of top and bottom or outer located, fixed ramped profile layers, in the preferred iteration being both flat and ring like in construction in order that they can be easily stamped or fine blanked in manufacture instead of using expensive machining. These modular inserts are robustly held in position within the head portion chamber by the use of location notches in conjunction with corresponding locking profiles within the head portion inner profile. One of the said notches is preferably distinctly larger than the others, the orientation notch, in order to provide a method of correct assembly orientation of the said fixed ramped profile layers within the said chamber location profile.
The present invention is even further characterized by having engagement and disengagement profiles at either end of its actuating layer pawl recesses preferably in close contact with the pawl engagement and disengagement faces, these said profiles project in the chosen direction the incumbent pawls against the corresponding fixed layer ramped profiles in the chosen clockwise or anticlockwise drive direction whilst simultaneously disengaging the pawls facing in the opposite direction, the engaged pawls teeth engaging with the drive element teeth in order to drive as required the same.
The present invention is even further characterized whereas the actuating layer is resiliently propelled in the chosen clockwise or anticlockwise direction by a sprung plunger whose engagement face acts against the said actuating layer chosen direction profile, when utilized in the reverse or reposition direction the actuating layer with its incumbent pawls, resiliently circumferentially rotating back against the said resilient sprung plunger, further allowing the pawl teeth engaged within the drive element teeth to resiliently slide over one another during the reposition or reverse action. In one example the sprung plunger is incorporated within a known dual direction ratchet switch having a direction lever.
The present invention is even further characterized whereas the actuating layer is resiliently propelled in the chosen clockwise or anticlockwise direction by a sprung plunger whose engagement face acts against the said actuating layer chosen direction profile, when utilized in the reverse or reposition direction the actuating layer with its incumbent pawls, resiliently circumferentially rotating back against the said resilient sprung plunger, further allowing the pawl teeth engaged within the drive element teeth to resiliently slide over one another during the reposition or reverse action. In a further example the sprung plunger is incorporated within an intermediate rocker switch positionally controlled by in one example a direction biasing control ring.
The present invention is even further characterized by the use of at least two sets of pawls within their corresponding pawl recesses, the utilized drive pawls are arranged to sequentially engage at the same time, the actuating layer engagement profiles acting simultaneously upon the pawl first biasing faces, robustly engaging the pawl teeth within the drive element teeth during the drive sequence, whilst simultaneously disengaging the pawls facing in the opposite direction.
The present invention is even further characterized by the use of at least three sets of pawls within their corresponding pawl recesses, the utilized drive pawls can be arranged to sequentially engage at the same time causing the actuating layer engagement profiles to act simultaneously upon the pawl first biasing faces, robustly engaging the pawl teeth into the drive element teeth during the drive sequence, the drive element thereby gripped in a manner by the three operated pawls similar to a three jaw chuck reducing the requirement for robust axle bearing surfaces within the closure portions. This configuration results in an extremely robust dual direction ratchet mechanism, this arrangement further provides a superior amount of pawl teeth to be capable of full engagement within the drive element teeth during the drive sequence yet with the correct ramped profile angles chosen, effortlessly disengage the pawl ramp profiles from their corresponding fixed pawl recess ramped profiles in the reverse or reposition direction. The pawl ramp profiles having a suitable gap from the pawl recess engagement ramp profiles during the reverse or reposition action to allow the pawl teeth to adequately disengage from the drive element teeth.
The present invention is even further characterized by the use of at least two but preferably three sets of pawls within their corresponding pawl recesses, the utilized drive and disengaged pawls arranged to sequentially engage whereas each actuating layer pawl recesses, engagement and disengagement profiles sets are located in one example, one third of a tooth out from the corresponding said corresponding sets causing the actuating layer engagement profiles to act to robustly fully engage the pawl teeth of only one pawl, into the drive element teeth during the drive sequence.
The six pawls divided into three sets of pawls, and each of the three sets is clocked differently to the drive element such that when the drive pawl of one set is engaged with the drive element teeth, one or other of the pawl set drive teeth is only partially engaged (e.g., one third of the pawl tooth arc engaged) and the remaining set pawl drive teeth are partially disengaged (e.g., one third of the pawl tooth arc disengaged). This arrangement can provide a coarse tooth pattern of for example 72 teeth to be utilized whilst providing a drive teeth equivalent to 72 times 3 or 216 equivalent toothed dual direction ratchet. As the angle between reverse and drive can be problem when used in situations where there is a restricted handle levered portion arc this is a significant enhancement over prior art dual direction ratcheting screwdrivers, ratchet wrenches or socket drives.
The present invention is even further characterized by the provision of a direction biasing switch which may be similar to that in the prior art, the switch axle capable of rotation within the head portion switch bore, the switch axle having a further blind cavity cross bore for the sliding fit of the plunger cylinder and its outwardly biasing switch spring, the switch being rotatable within an arc allowing said sprung plunger to be switched as required between the actuating layer biasing direction profiles in order to bias in the required direction the actuating layer pawl engagement ramp profiles against the pawl first biasing faces in order to provide clock or anti-clockwise drive directions.
In a further utilization of the present invention the dual direction ratchet is incorporated into a screwdriver using a switch ring to determine the drive direction of the said ratchet. In the first aspect, the present invention provides a dual direction, ratcheting screwdriver, comprising a handle portion with a proximal end and a distil end, the handle proximal end robustly incorporates the housing encapsulated ratchet mechanism with its outer facing direction biasing switch ring within its profile. The housing is connected to the drive element portion, of the rotatable elongate shaft of the screwdriver in order to transmit motion and torque to the elongate shaft as required, in the direction required. The housing having a central chamber in which the said drive element portion of the elongate shaft is received. The preferably die cast housing having a generally circular central chamber, the inner surface of which, adjoining the direction biasing switch ring direction ascertaining groove, has a connection slot for the required outward connection to the direction biasing ring switch, by the intermediate rocker switch housing, which further incorporates axles capable of positional rotation within corresponding molded axle shaped formations located within the housing wall. The rocker switch elongate housing further incorporates a resilient sprung plunger within its related bore. The said housing chamber having in one example for ease of manufacture, modular inserts in the form of preferably three layers, two outer fixed ramped profile layers with a sequential actuating layer capable of limited rotation between the fixed layers. The fixed ramped profile layer having locking notches on their periphery which mechanically engage with the corresponding housing chamber locking profiles, the said fixed ramped profile layer, further utilizing ramped profiles within their central profile, preferably three sets of equally spaced opposing direction pawls are situated within said corresponding ramped profiles. The middle sequential actuating layer has engagement and disengagement profiles at either end of its pawl recesses, these said profiles project in the chosen direction the incumbent pawls against the corresponding fixed layer ramped profiles in the chosen clockwise or anticlockwise drive direction whilst simultaneously disengaging the pawls facing in the opposite direction, the said pawls outer ramped profile acting against the corresponding fixed layer pawl ramped profile in the chosen drive direction causing the engaged pawls teeth to engage with the drive element teeth in order to drive as required the same. In order to activate the screwdriver in the chosen direction the operator rotates the switch ring into its required position, thereby swiveling the switch ring rocker around its axles whereby the actuating layer is resiliently propelled in the chosen clockwise or anticlockwise direction by the said ring switch rocker internal sprung plunger, the sprung plunger engagement face acting against the said actuating layer chosen direction profile. Utilized in the reverse or reposition direction the actuating layer with its incumbent pawls, resiliently circumferentially rotating against the said resilient sprung plunger, further allowing the pawl teeth engaged within the drive element teeth to resiliently slide over one another during the reverse or reposition action. In order to ensure the continuance of the chosen switched direction the housing can further employ a bore with a sprung ball detent which can act against a suitable indent within the switch ring as a locator.
The present invention is even further characterized by the provision of a direction biasing switch whereas in order to activate the screwdriver in the chosen direction the operator rotates the known switch ring into its required position, characterized by the incorporation of an intermediate switch ring rocker which can usefully swivel around its axles propelled by the interaction of its actuating profile with the switch ring ascertaining recess, whereby the actuating layer is resiliently propelled in the chosen clockwise or anticlockwise direction by the said ring switch rocker internal sprung plunger, the sprung plunger engagement face acting against the said actuating layer chosen direction profile.
While one or more preferred embodiments of the preferred invention have been described above, it should have been understood that any and all equivalent realizations of the present invention are included within the scope and spirit thereof The embodiments depicted are presented by way of example only and are not intended as limitations upon the present invention. Thus, it should be understood by those of ordinary skill in this art that the present invention is not limited to these embodiments since modifications can be made. Therefore, it is contemplated that any and all such embodiments are included in the present invention as may fall within the scope of appended claims.
The features, advantages, and objects of the embodiments of the present invention will become more apparent from the detailed description as set forth below, when taken in conjunction with the drawings in which like referenced characters identify correspondingly throughout, and wherein:
Following is a listing of the various components used in the best mode preferred embodiment and alternative embodiments. For the ready reference of the reader the reference numerals have been arranged in ascending numerical order.
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various forms. The figures are not necessarily to scale, 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 and as one skilled in the art to variously employ the invention.
Further shown in
The six pawls 500 divided into three sets of pawls, set A 506, set B 507 and set C 508, and each of the said three sets 507, 508 and 509 is clocked differently to the drive element teeth 202 such that when the drive pawl 507, 508 or 509 of one set is engaged with the drive element teeth 202, one or other of the pawl set drive teeth 502 is only partially engaged (e.g., one third of the pawl tooth 502 arc engaged) and the remaining set pawl drive teeth 502 are partially disengaged (e.g., one third of the pawl tooth arc disengaged).
Although certain example methods and apparatus have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus, and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1906089 | Apr 2019 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/062176 | 4/30/2020 | WO |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2020/221913 | 11/5/2020 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6253646 | Chang | Jul 2001 | B1 |
| 8806986 | Chen | Aug 2014 | B2 |
| 10456893 | Westerman | Oct 2019 | B2 |
| 10668600 | Ye | Jun 2020 | B1 |
| 10730168 | Solar | Aug 2020 | B2 |
| Number | Date | Country | |
|---|---|---|---|
| 20220219293 A1 | Jul 2022 | US |
