AU5689694A - Power driven ratchet wrench - Google Patents

Description

POWER DRIVEN RATCHET WRENCH

--BACKGROUND OF THE INVENTION-- This invention relates to power operated ratchet wrenches. In particular this invention relates to improvements to power operated ratchet wrenches of the type generally described in our earlier International Patent Application No. PCT/AU 91/00005.

In the present specification power operated ratchet wrenches "of the type described" embrace wrenches having:- a drive member configured for non-rotatable engagement with a member to be rotated and an external surface provided with circumferentially spaced pawl abutments; oscillatory translation means for translating drive from a rotary drive shaft to the drive member and including a driving pawl co¬ operating with the pawl abutments; an external housing assembly enclosing the oscillatory translation means and rotary drive shaft therefor and comprising opposed housing portions each having a web part which is apertured to rotatably accommodate a respective bearing land formed at opposite sides of the drive means and which axially constrain the drive means therebetween.

Such power tools are advantageously used in many situations where rapid and continuous rotation of fasteners is required and may be operated by electric, pneumatic, hydraulic or mechanical means. These tools are self-locking and thus nuts, bolts and like fasteners may be readily tightened or loosened and operated manually to apply a required torque which may exceed the torque available by power operation. Accordingly it is important that such tools be robust and able to withstand the normal rigors to which conventional hand tools are subjected.

While such operation can be achieved with our earlier described wrenches the additional torque which may be applied manually is somewhat limited by the robustness of the drive line against which the manually applied torque reacts. Furthermore the cost of manufacturing the accurate housing parts for simple assembly significantly increases th cost of production of our prior proposals. In addition whil our earlier International patent specification describes power operated wrenches having advantages in relation to simplicity, compactness and/or ease of assembly, further features for enhanced usefulness have become apparent.

This invention aims to provide power operated wrenches of the type described which will alleviate at least one of the abovementioned disadvantages and which will be reliable and efficient in use.

With the foregoing in view, this invention in one aspec resides broadly in a power driven wrench assembly of the typ described wherein each housing portion includes a drive shaf supporting portion which is substantially channel shaped in section and the channel shaped portions of the housing are separable along a plane substantially coincident with the axis of the rotary drive shaft and wherein:- the rotary drive shaft is supported by axially spaced bearing shells having opposed external protrusions held captive within recesses opening to the mating face of at least one housing portion. The protrusions may be fully accommodated in recesses formed in one housing portion and b held captive therein by a flat mating surface of the other housing portion. Preferably however the protrusions are eac partially accommodated in respective complementary recesses formed in the opposed housing portions. The bearing shells may have a polygonal outer form so as to provide a plurality of opposed protrusions but preferably the opposed protrusion are in the form of opposed external ribs formed on the bearing shells. It is also preferred that the ribs locate substantially without play within the complementary recesses whereby they locate the opposed housing portions with respec to one another such that simple through fastenings, such as screws or bolts, may be utilised to hold the opposed housing portions together. For this purpose it is preferred that th ribs are substantially rectangular. One of the shells may have a thrust face formed at one end thereof and be adapted to co-operate with a collar on the drive shaft to provide axial location for the drive shaft. Of course this assembly technique may be used in other two part bearing housings. The opposed housing portions are suitably secured together by fastenings passing therethrough, through body portions which extend fully between the mating faces and the outer surfaces of the opposed housing portions and preferably located at opposite sides of bearing shell adjacent the oscillatory drive means.

For the purposes of forming a compact ratchet wrench assembly it is preferred that the opposed housing portions be formed as substantially identical housing blanks having finished mating surfaces and recesses for accommodating the protrusions on the bearing shells such that further accurate machining of the blanks is not required for assembly of the housing parts and location of the drive shaft. Preferably the opposed housing blanks and the bearing shells are formed by powder metallurgy techniques and suitably the bearing shells are formed as self lubricating shells. The internal recesses for accommodating the oscillatory drive means and providing clearance about the drive shaft are suitably machined from the housing blank. In another aspect this invention resides broadly in a power driven wrench assembly of the type described wherein the housing assembly supports a ratchet pawl co-operating with the spaced abutments and supported by the external housing assembly independent of the oscillatory translation means whereby the ratchet pawl will lock with a respective abutment on the drive member to transfer drive loads applied manually to the wrench housing directly to the drive member. This removes such loads from the power drive train.

Preferably the oscillatory translation means is of the type including an oscillatory member having a part- cylindrical head band which pivotally locates the oscillatory member about the drive member and a base part supporting the pawl and providing a drive recess for an orbital drive member. Further, it is preferred that the opposed edge portions of the head band and base part form continuous ring portions about the drive member and the driving pawl and the ratchet pawl access the pawl abutments through respective through passages in the oscillatory member disposed between the opposed continuous ring portions.

It is also preferred that each housing portion has internal steps positioned to hold the ratchet pawl in operative alignment with the respective through passage in the oscillatory drive member. It is also preferred that the steps support a pivot pin about which the ratchet pawl oscillates, at least in the direction of the load applied through manual operation of the wrench. Preferably the pivot pin is located in the housing portions outwardly of the steps. The pivot pin may have stepped end portions for positive location within apertures formed through the housing portions or alternatively the apertures may be blind apertures opening into the respective housing portions.

Preferably the drive member is an open socket member whereby either open end may be engaged with a fastener whereby a fastener driven thereby may be rotated in either direction even though the open socket member may be rotated in one direction only relative to the external housing assembly. The housing could include an angled head portion if desired, angled through the engagement between the orbital drive member and the oscillatory member, to facilitate access to fasteners in certain situations. In a further aspect this invention resides broadly in a power wrench assembly of the type described wherein the drive member is an open socket drive member having a polygonal internal surface and a drive socket engaged within said open socket and provided with a radial collar extending outwardly beyond the polygonal surface. The drive socket may extend axially outwardly beyond the radial collar or it may be contained substantially wholly within the confines of the drive member. Alternatively the drive socket may include a pivotable drive mounting located within the drive socket either within or externally of the confines of the open drive socket. The pivotal drive mounting may support a further socket or a drive in the form of a square or a hex drive bar which may be of conventional form.

In yet another aspect this invention resides broadly in a power wrench assembly having drive member adapted for driving a fastener or the like and supported within an external housing assembly supporting drive means for rotating the drive member and wherein the housing assembly supports a ratchet pawl co-operating with spaced abutments on said drive member and supported by the external housing assembly whereby the ratchet pawl will lock with a respective abutment on the drive member to transfer drive loads applied manually to the wrench housing directly to the drive member. The drive means may be of any suitable form such as a spur or bevel gear drive, a fluid drive, a belt drive or a ratchet drive. --BRIEF DESCRIPTION OF THE DRAWINGS--

In order that this invention may be more readily understood and put. into practical effect reference will now be made to the accompanying drawings which illustrate preferred form of wrench of this invention wherein: - Fig. 1 is an exploded view of a wrench according to an embodiment of the invention;

FIG. 2 is a perspective view of the wrench, and FIG. 3 illustrates a further socket member for use with the wrench. —DESCRIPTION OF THE PREFERRED EMBODIMENT—

Fig. 1 illustrates a ratchet wrench 7 having opposed substantially identical housing portions 10a, 10b which may be separated along a medial plane at right angles to the axis 11 of the drive member 12 which is in the form of an open drive socket. The housing 10 is flat sided with the flat side walls or flanges 9 extending substantially parallel to one another and to their planar mating faces 8.

Each housing portion comprises a head portion 13, tail portion 14, and stem portion 15. Each head portion 13 is formed with an internal recess 16 provided with a circular opening 17 disposed with its axis at right angles to the side flanges 9. The stem portion 15 includes an internal bore 18 spaced from a drive shaft 19 extending substantially radially of the open socket member 12 and between the internal recess 16 and the tail portion 14. The recess 16 houses an oscillatory member 20 which translates drive from the drive shaft 19 to the open socket member 12. The oscillatory member 20 includes a cylindrical head band 23, defining a circular chamber which locates rotatably about the open socket member 12, and a rearwardly tapered base part 21 formed with a rearwardly opening part- cylindrical drive recess 22 into which a complementary part- spherical drive member 28 extends. The drive member 28 is provided with an axial bore whereby it locates rotatably on the drive pin 29 formed integrally with the drive shaft 19 and offset to the axis thereof.

The base part 21 also provides a pawl mounting passage 30 located between opposed continuous ring portions 31 which opens inwardly into the circular chamber formed by the head band 23. A drive pawl 32 is pivotally located in the passage 30 and biassed by spring 33 into engagement with the pawl abutments or ratchet teeth 26 formed about the outer surface of the open socket member 12. The drive pawl 32 pivots on a pin 34 located in apertures 35 in the rear side flanges 36 of the base part 21 and the teeth 26 extend between bearing lands 27a and 27b formed at opposite ends of the open socket member 12 whereby the open socket member 12 is supported for rotation by the housing portions 10a, 10b and restrained against axial movement between the opposed flanges 9.

The housing 10 is provided with locating apertures 38 for a pivot pin 39 about which a ratchet pawl 40 pivots. The ratchet pawl 40 extends through a further access passage 41, formed in the base part 21 between the opposed ring portion 31, to engage the ratchet teeth 26. The ratchet pawl 40 wi lock with a respective tooth 26 to transfer drive loads applied manually to the wrench housing directly to the driv member and prevent the applied load being transferred to th drive member 28 and its supporting pin 29 which is maintain relatively small in order to achieve a compact wrench.

In order to locate the ratchet pawl 40 in the passage and to minimise the load path through the pivot pin 39, the internal face of the housing portions 10a and 10b are stepp inwardly at 45, as illustrated, to provide part-circular saddles 46 extending inwardly from the respective apertures 38 and co-operating with outer face portions of the pin 39 which are loaded in reaction to pawl loads. The oscillator member 20 which is cut-away to accommodate the ratchet pawl 40. However the cut-away is minimised as the saddles 46 extend into the zone of the oscillatory member 20 thereby enabling the internal recess in the zone of the oscillatory member 20 to extend to the supported pin 39. Suitable biassing means are provided to bias the ratchet pawl into engagement with the ratchet teeth 26, such as the torsion spring 47.

For assembly the oscillatory member 20 with drive pawl 32 in place may be engaged about the open socket member 12 and placed in one housing portion 10. The ratchet pawl 40 may then be pinned in position in the housing portion 10 an the assembly captured by locating the other housing portion in place. As such assembly of the translation and ratchet mechanism is relatively simple. As illustrated, the drive shaft 19 is supported for rotation at its outer end adjacent the drive pin 29, by a needle roller bearing 49 supported within an associated bearing shell 50, while the inner end of the drive shaft 19 is supported directly by the bearing shell 52. Each shell and 52 is formed as a self-lubricating sintered bearing. Each shell 50 and 52 is also provided with diametrically opposed ribs 53 which taper away from the shell and which are accurately located within complementary recesses 54 formed in the opposed housing portions 10a and 10b.

The ribs 53 locate substantially without play within the complementary recesses 54 whereby they act to operatively locate the opposed housing portions with respect to one another and whereby simple through fastenings 55 are utilised to hold the opposed housing portions 10a and 10b together. For this purpose it is preferred that the ends of the ribs extend at right angles to the drive shaft axis. The shell 50 has a thrust face formed at one end thereof which co-operates with a collar 56 on the outer end of the drive shaft 19 to provide axial location for the drive shaft. It will be appreciated that the above described construction facilitates simple and accurate assembly of the housing and drive shaft, requiring only that the shaft 19 with the bearing shells 50 and 52 thereon be located with the ribs 53 in the complementary recesses 54 and the two fastenings 55 inserted and tightened. The opposed housing portions 10a and 10b are formed from identical housing blanks formed accurately by powder metallurgy techniques and have finished mating surfaces 8 and flanges 9 and recesses 54 for accommodating the ribs on the bearing shells 50 and 52. The blanks are machined to form an internal bore 18 which is clear of the drive shaft 19 and to form the internal recess 16 and steps 45 and requisite apertures.

As described the housing portions 10a and 10b are secured together by screws 55. These pass through side sections of the housing portions which are solid from face to face. The tail portion 14 is an open ended spigot 60 surrounding the squared end portion 61 of the drive shaft 19 and is adapted to engage releasably in a convention trigger operated air drive assembly. The internal opening 25 of open socket member 12 is hexagonal in section to allow it to engage with fastening elements having an hexagonal head. Furthermore it may engag with reducer inserts for driving fasteners having smaller heads.

Of particular importance it will be seen that the open socket member 12 is similar in dimension to the ring portion of a conventional ring spanner and that the increase in size of the wrench beyond the open socket member 12 results from small combined radial thickness of the head band 23 and the flanged end part 62. Notwithstanding this the wrench 10 will be relatively robust as the head portion of each housing section 10a and 10b is a channel section which is relatively stiff and able to resist bending loads applied parallel to the axis of the open socket member 12 while the full width side flanges formed integrally with the webs are able to resist torque loads which may be manually applied thereto.

When the wrench 7 is used manually to apply a torque to a fastener in excess of the torque which may be applied by the power operation, the load from the open socket member 12 will be transferred directly to the housing 10 by the ratchet pawl 40 through the relatively small pivot pin 39, which is restrained whereby its bending loads are minimal and as such will provide reliable service. Furthermore the opposed ring portions 31 of oscillatory member will ensure that it remains dimensionally stable, maintaining the drive pawl 32 fully engaged with the ratchet teeth 26 under load.

The housing portions 10 are also formed with external complementary reliefs 63 at the base of the head portion 13 which form guide channels along which a clip 64 may slide from an engaged position at which its leading end 65 overlies the internal opening 25 to a retracted position at which the leading end 65 is spaced rearwardly thereof. In its operative position, the clip 64 prevents the wrench from engaging with a bolt beyond the head thereof. Serrations 66 provided on each flange 9 are engaged by downturned portions 67 of the clip and maintain the clip 64 in its selected position. Such clips 64 may be provided at each side of the wrench 10 if desired. Washers 68 at each side of the socket member 12 provide a frictional restraint of the open socket member 12 and form seals against ingress of foreign matter into the wrench. As illustrated in Fig. 2 the wrench 7 has concealed internal drive components and is adapted for direct engagement of the socket with a hexagon nut or bolt head or the like or with smaller hexagon drive shapes by the use of shell-like adaptor 70. When the wrench 7 is used for direct drive the slide clip 64 may be slid outwardly to overlie the socket 25 to limit passage of a bolt head or nut therethroug to a fully engaged position.

Each adaptor 70 has a radially flanged end 71 which prevents passage of the adaptor 70 through the socket 25 and an internal configuration 73 forming the reduced drive socket. A further socket adaptor 74 is illustrated in Fig. 3. Additionally the adaptors may provide a socket which supports a conventional square or hexagonal drive spigot or pivotable drive for a tandem socket which may be fixedly or interchangeably engaged therewith.

It should also be appreciated that where a preference i indicated in this specification it is to be understood that practical alternatives are embraced within the spirit of the invention. Furthermore, while the above has been given by way of illustrative example of the invention various modifications may be made to the embodiments described without departing from the scope and ambit of the invention as defined in the appended claims.

Claims (16)

- -CLAIMS- -

1. A power driven wrench assembly of the type described, wherein each housing portion includes a drive shaft supporting portion which is substantially channel shaped in section and the housing portions are separable along a plane substantially coincident with the axis of the rotary drive shaft, and wherein:- the rotary drive shaft is supported by axially spaced bearing shells having opposed external protrusions held captive within recesses opening to the mating face of at least one housing portion.

2. A power driven wrench assembly as claimed in claim 1, wherein the protrusions are each partially accommodated in respective complementary recesses formed in the opposed housing portions.

3. A power driven wrench assembly as claimed in claim 1 or claim 2, the bearing shells have opposed protruding external ribs closely accommodated in the respective complementary recesses.

4. A power driven wrench assembly as claimed in claim 3, wherein the ribs locate substantially without end play within the complementary recesses.

5. A power driven wrench assembly as claimed in claim 4, wherein one of the bearing shells has a thrust face formed at one end thereof and the drive shaft is provided with a collar which bears against the thrust face.

6. A power driven wrench assembly as claimed in claim 4 or claim 5, wherein the opposed housing portions be formed as substantially identical housing blanks having finished mating faces and recesses for accommodating the opposed protruding external ribs.

7. A power driven wrench assembly as claimed in claim 6 wherein the opposed housing portions and the bearing shells are formed by powder metallurgy techniques, the bearing

5 shells being formed as self lubricating shells.

8. A power driven wrench assembly of the type described wherein the housing assembly supports a ratchet pawl co¬ operating with the spaced abutments and supported by the external housing assembly independent of the oscillatory

10 translation means whereby the ratchet pawl will lock with a respective abutment on the drive member to transfer drive loads applied manually to the wrench housing directly to the drive member.

9. A power driven wrench assembly as claimed in claim 8, 15 wherein the oscillatory translation means is of the type including an oscillatory member having a part-cylindrical head band which pivotally locates the oscillatory member about the drive member and a base part supporting the pawl and providing a drive recess for an orbital drive member an 20 wherein, the opposed edge portions of the head band and base part form continuous ring portions.

10. A power driven wrench assembly as claimed in claim 9, wherein the driving pawl and the ratchet pawl access the paw abutments through respective through passages in the

25 oscillatory member disposed between the opposed continuous ring portions.

11. A power driven wrench assembly as claimed in claim 10, wherein each housing portion is stepped inwardly adjacent th ratchet pawl to provide opposed pawl positioning lands.

30 12. A power driven wrench assembly as claimed in claim 11, wherein the ratchet pawl is supported for pivotal motion about a pivot pin extending through the opposed pawl positioning lands.

13. A power driven wrench assembly as claimed in claim 12, wherein the opposed pawl positioning lands provide part- circular saddles supporting outer face portions of the pivot pin.

14. A power driven wrench assembly of the type described wherein: - the housing assembly supports a ratchet pawl co¬ operating with the spaced abutments and supported by the external housing assembly independent of the oscillatory translation means whereby the ratchet pawl will lock with a respective abutment on the drive member to transfer drive loads applied manually to the wrench housing directly to the drive member, and wherein: each housing portion includes a drive shaft supporting portion which is substantially channel shaped in section and the housing portions are separable along a plane substantially coincident with the axis of the rotary drive shaft; the rotary drive shaft is supported by axially spaced bearing shells having opposed external protrusions held captive within recesses opening to the mating face of at least one housing portion.

15. A power driven wrench assembly as claimed in claim 14, wherein the drive member is an open socket drive member having a polygonal internal surface and able to accommodate a drive socket therein and provided with a radial collar extending outwardly beyond the polygonal surface.

16. A power driven wrench assembly as claimed in claim 15, wherein said housing portions are formed by powder metallurgy with mating faces having recesses formed therein and configured to provide the complementary recesses upon machining a clearance passage for the drive shaft.