GB2171492A

GB2171492A - Universal joint

Info

Publication number: GB2171492A
Application number: GB08603737A
Authority: GB
Inventors: Daniel Wesley Hazebrook; Steven Charles Hahn
Original assignee: GKN Automotive Components Inc
Current assignee: GKN Driveline North America Inc
Priority date: 1985-02-22
Filing date: 1986-02-14
Publication date: 1986-08-28
Also published as: DE3645139C2; FR2578012B1; FR2578012A1; JPS61192929A; FR2638798B1; DE3606075A1; FR2638798A1; JPH0754855A; CA1323768C; GB2171492B; GB8603737D0

Abstract

A torque transmitting universal joint, which is a constant velocity joint up to a certain angle of articulation, comprising an inner joint member 25 having circumferentially spaced apertures 41, balls 40 received in the apertures for unrestricted rotation therein, adjacent balls abutting one another to provide mutual support, and an outer joint member 26 with internal circumferentially spaced rectilinear grooves 39 in which the balls engage for torque transmission between the joint members. The outer joint member is deformed to retain the inner joint member in driving engagement with it. Also disclosed is a double universal joint with two inner joint members and a common joint outer member. A quickly disconnectable version of the joint has the balls supported by a spring loaded plunger within the inner joint member. <IMAGE>

Description

SPECIFICATION Universal joint This invention relates to a universal joint, for establishing a torque transmitting connection between drive and driven members. More particularly, the invention relates to a universal joint capable of providing constant velocity ratio transmission when the driving and driven members are in high speed operation, and offset or misaligned from one another.

Many forms of universal joint, including inner and outer joint members, are known from the prior art. For example, US Patent 4156354 discloses a joint in which torque is transmitted by roller bodies, possibly in the form of truncated spheres, interposed between inner and outer joint members, the roller bodies occupying planar recesses in the inner joint member for radially slidable engagement relative thereto. Such a construction increases the complexity and size of the joint, requiring close maintenance of surface finish and manufacturing tolerances for satisfactory operation.

Increased friction results from the sliding engagement of the roller bodies with the recesses in the inner joint member, which decreases smoothness of operation of the joint, and yet the joint is relatively expensive to manufacture.

US Patent 2910845 discloses a constant velocity universal joint utilising spherical drive members restrained to rotate about the journals provided on the inner joint member. Such restraint of drive members provides increased friction in the joint, which is undesirable.

It is the object of the present invention to provide an improved constant velocity universal joint, usable for angular and axial misalignment between driving and driven members, having improved smoothness of operation, and able to be made with relatively lower manufacturing costs because of less critical tolerances and surface finishes.

According to the invention, we provide a universal joint for torque transmission comprising: an inner joint member having aperture means therein; a plurality of balls received in said aperture means for unrestricted rotation therein, said balls being arranged in said aperture means so that each of said balls has a portion in abut ment with a portion of at least one other said ball, to provide mutual support therefor; an outer joint member having a plurality of spaced apart rectilinear grooves therein, each of said balls being received in one of said grooves; said inner joint member being capable of articulating relative to said outer joint member; and said balls providing for torque transmission between said joint members when not aligned with one another.

In a joint according to the invention, the combination of unrestricted rotation of the balls in the inner joint member, the mutual support of the balls by one another, and the ability of the balls to move in the grooves in the outer joint member provides for constant velocity torque transmission with a minimum of effort and vibration. The joint will remain a constant velocity joint until it is articulated beyond an angle of approximately eight degrees, which is adequate for a large number of uses of the invention.

The joint is capable of being used as a multiplicity of like joints, to provide for relatively large amounts of offset or misalignment between driving and driven members connected by such joints.

Further, a quickly disconnectable version of joint is shown.

The invention will now be described by way of example with reference to the accompanying drawings of which: Figure 1 is a diagrammatic view of a universal joint of the present invention used as a wrench drive; Figure 2 is a diagrammatic view illustrating a universal joint embodying the present invention used in conjunction with a standard ratchet wrench; Figure 3 is a diagrammatic view showing a universal joint embodying the present invention used where an offset between adjoining torque transmitting shafts is present; Figure 4 is a diagrammatic view showing a universal joint embodying the present invention in use where angular misalignment and/or offset between shafts is desired; Figure 5 is a diagrammatic view showing a construction having a multiplicity of universal joints of the present invention connected in series in a cascaded joint;; Figure 6 is a diagrammatic view illustrating a universal joint embodying the present invention being used in a power take-off system; Figure 7 is an end view of a universal joint according to the invention; Figure 8 is a sectional view taken in the direction of the arrows 8-8 of Figure 7; Figure 9 is a sectional view taken in the direction of the arrows 9-9 of Figure 8; Figure 10 is a view similar to that of Figure 7 but showing a version of the present invention having four balls instead of three; Figure 11 is a diagramatic elevation of a single universal joint according to the invention, partly in section and with the inner joint member articulated; Figure 12 is a sectional view taken in the direction of the arrows 12-12 of Figure 11, and showing the universal joint at rest;; Figure 13 is a view as Figure 12, but showing the universal joint under operating conditions with torque applied to the inner joint member in the direction of the arrow; Figure 14 is an elevation, partly in section, of a double universal joint according to the invention; Figure 15 is an elevation partly in section of a single universal joint having the quick-disconnect device of the present invention; and Figure 16 is a view as Figure 15 but showing the operation of the quick-disconnect device.

Referring to Figures 1 through 6, several uses of the present invention are shown. In Figure 1 there is shown a ratchet wrench 23 having a universal joint, generally designated by the numeral 20, included as an integral part thereof. The constant velocity joint 20 may be considered to be of the quick disconnect type, as hereinafter described, with the disconnect device being actuated by a springloaded push button 23a. The joint 20 itself is made up of an outer joint member 22 and an inner joint or pintle member 21. The wrench 23 with the integral inner joint member 21 may be part of a set which includes a multiplicity of different sizes of sockets each of which can interchangeably be assembled to the inner joint member 21 to serve as an outer joint member.It is, of course, also com- templated that other tools, such as screwdriver type tools, pneumatic wrenches and other tools, and electric wrenches and other tools can be constructed with an integral universal joint.

In Figure 2 there is shown a conventional ratchet wrench 27 of the square drive type, the drive being provided through an extension 28 which is square in cross-section, as is known in the art. The extension 28 fits into a socket 29 provided in an outer joint member 26 of a universal joint 24. The universal joint 24 is of the non-quick disconnect type, as hereinafter described, and has an inner joint or pintle member 25. It is also contemplated that the universal joint 24 can be applied to other types of driven tools, such as screwdrivers, pneumatic wrenches and screwdrivers, and electric wrenches and screwdrivers.

In Figure 3 there is shown an application where offset and possible variation in axial spacing exists between the shaft of a motor 30 and the driver shaft of a gear box 31. The motor and gear box are shown joined by a double universal joint 32 embodying the construction used in the present invention.

Figure 4 shows the same motor and gear box as shown in Figure 3 but under a condition where angular misalignment and/or offset is desired. Again, the shaft of the motor 30 and the driveshaft of the gear box 31 are joined by a double universal joint, generally designated by the numeral 32.

Figure 5 shows an application where a substantial offset exists between the shaft of the motor 30 and the driver shaft of the gear box 31. The motor and the gear box are joined by a cascaded series of universal joints 32 embodying the construction used in the present invention.

There is shown in Figure 6 a situation where a universal joint of the present invention is used as a power take-off. A source of power such as a farm tractor or other vehicle is illustrated by the numeral 33, towingly connected to a power actuated attachment 34.

The implement 33 provides a driving force for the operation of the power attachment 34. In this case a quick disconnect, single universal joint 37 is utilised in providing this driving force.

Referring now to Figures 7 and 8, a universal joint according to the invention comprises an outer joint member 26 with a socket 29 provided in one end thereof to receive the ratchet wrench 27 shown in Figure 2, or any other device to be driven. Immediately adjacent the socket 29 is an enlarged portion 38 having three rectilinear circumferentially spaced internal grooves 39. The grooves 39 may be spaced equally around the circumference, and have a part-cylindrical shape, i.e. arcuate section in a plane extending transversely through the outer joint member 26, to receive three spherical balls 40. The enlarged portion 38 of the outer joint member 26 receives an inner joint member, generally designated by the numeral 25. Before assembly the three balls 40 are inserted in apertures 41 provided in a generally spherical head portion 42 of the inner joint member 25.The inner joint member 25 having the balls 40 inserted therein is then, in turn, inserted into the enlarged portion 38 of the outer joint member 26 until the head portion 42 of the inner joint member 25 contacts a position element 44. Slight additional force is then applied and circumferentially spaced parts 45 of the outer joint member are deformed, by staking or otherwise, a distance sufficient to prevent removal of the inner joint member 25.

Several considerations are important when the dimensions of the universal joint are considered. The apertures 41 in the head portion 42 of the inner joint member 25 must be such as to allow free rotation of the balls 40 and ball-to-ball contact between adjacent balls.

The dimension across the grooves 39 of the outer joint member 26 must be such that when the inner joint member 25 is axially aligned with the outer joint member 26 there is a rolling plunge fit between the balls 40 and the rectilinear grooves 39.

The position element 44 is preferably made of resilient material such as duro nitrile or the like, and the relationship between it and the deformations 45 must be such that the element 44 exerts enough pressure against the head portion 42 of the inner joint member 25 such that the member, when articulated, will be able to hold any angle at which it is placed under its own weight. This feature conforms to a Society of Automotive Engineers standard. One source for the duro nitrile material used to make the position element is Goshen Rubber Company. If desired, an aperture 46 may be provided in the position element 44.

In addition, the deformations 45 must be such as to keep all the balls 40 in the rectilinear grooves 39 when the inner joint member 25 is at its full angular articulation. The deformed areas are to allow no free axial movement, and they are not to interfere with the rotation of the inner joint member when it is at an angle of up to thirty degrees from the outer joint member 26.

It can be seen that with this construction there is ball-to-ball contact between adjacent balls 40, and that torque is transmitted between the joint members by the balls 40.

A version of joint according to the present invention utilising four balls may be constructed as shown in Figure 10, and used when large amounts of torque are to be transmitted. As before, there is a plurality (in this case four) of rectilinear grooves 39 equally spaced around the internal circumference of the enlarged portion 38 of the outer joint member 26. The apertures 41 in the inner joint member 25 must meet the same requirements as before, and the four apertures 41 are provided at right angles to each other.

In this case the cross-section of the inner joint member 25 is reduced, so that some material is left to strengthen the inner joint member at the centre thereof, as indicated by the numeral 25a, and ball-to-ball contact between adjacent balls 40 is still maintained. It can be easily seen that versions of the present invention having more than four roller balls may be provided.

As shown in Figure 8, to provide for easy attachment of the inner joint member or pintle 25 to a socket, not shown, or other device for receiving torque from the universal joint, the inner joint member 25 is provided with a standard ball detent in the form of a ball bearing 50 and spring 51.

Referring now to Figure 11, there is shown a version of the universal joint having a different outer member configuration from that above described. The socket 29 thereof is not shown for ease of illustration. As before, the outer joint member 26 has an enlarged portion 38 having a plurality of spaced rectilinear grooves 39 in which balls 40 are received.

The grooves 39 are preferably cylindrical in transverse section as in the case of the universal joint illustrated in Figures 7 and 8. The balls 40 are received in apertures in the head portion 42 of the inner joint member 25. It can be seen that as the inner joint member is articulated the plane of torque transmission is no longer perpendicular to the axis of the outer joint member. The balls 40 pull away from the grooves 39. This is possible because of the unrestricted rotation and linear translation (movement) of the balls 40 in the apertures in the inner joint member.

As Figure 12 shows, when the constant velocity universal joint is at rest one of the balls 40 pulls substantially out of the groove 39, while the remainder of the balls 40 are held in the grooves by gravity. However, as shown in Figure 13, as soon as the joint starts to rotate, because of circumferential forces, the balls 40 all assume positions aproximately equidistant from the axis of rotation of the inner joint member 25 and all are slightly out of the grooves 39. As can be seen, each ball contacts its respective groove at approximately the same position T as the other balls and grooves. It is believed that the moment arm from the centre of rotation to the point T, for the present invention, is smaller than any of the previously discussed prior art devices thereby providing for more efficient and smoother torque transmission.This feature, coupled with the unrestricted rotation of the balls as the joint is rotated, provides for lower frictional forces also, making the present joint a substantial advance over the prior art.

The present invention may be embodied in a double universal joint which can be seen in Figure 14. The joint comprises a driveshaft, generally designated by the numeral 55; a barrel race, which constitutes the outer member of two joints making up the double joint and is generally designated by the numeral 56; and a driver, generally designated by the numeral 57. The driveshaft 55 and driver 57 constitute the inner members of the two joints.

The driveshaft 55 has a squared off extension portion 54 for ease of attachment to other devices, and is provided with the standard detent ball 58 which is spring-loaded as described hereinbefore. Of course, the extension portion 54 could also be round, and this would be the preferred configuration in the case of a universal joint intended to be connected to the drive shaft of a motor, for example. In any case, a head portion 63 of the driveshaft is similar to that of the inner member of a single joint above described in that it has a plurality of apertures 67 spaced equidistantly around the head portion to receive a plurality of balls 65. As before, there is ball-to-ball contact between adjacent balls 65 as in the single joint. A head portion 64 of driver 57 is of the same configuration.To assemble the double joint, the driveshaft 55 is inserted into the barrel race 56 and one of a pair of identical end caps 61, which was placed over the head portion 63 of the driveshaft 55 before the balls 65 were inserted, is press-fitted onto outer surface 53 of barrel 56. A position pad 62 is then inserted, and a second identical end cap is placed over the head portion 64 of the driver 57, further balls 65 are placed in identical apertures 67, and then the end cap 61 is press-fitted onto the barrel 56. In the illustrated embodiment there are three roller balls 65 in the driveshaft and the driver and, therefore, there will be three equally spaced rectilinear grooves 66 in the barrel 56. As before, the dimensions across the grooves are of importance.When the axis of the driveshaft and/or driver are in alignment with the axis of the barrel the dimensions across the roller balls 65 and the rectilinear grooves 66 must be such as to provide a rolling plunge fit.

Likewise, the dimension of the position pad 62 is important. As before, this position pad is preferably made of resilient material, such as duro nitrile, and must be of a sufficient dimension such that when the end caps 61 are in place it exerts sufficient force against the head portion 63 of the driveshaft and the head portion 64 of the driver 57 so that the driver and the driveshaft will hold any angle at which they are placed, under their own weight. If desired, a hole 70 may extend through the position pad 62. To complete the construction, a socket 59 having a standard detent 60 is provided in the driver 57.

In embodiments where a quick-disconnect version of a constant velocity universal joint is required, the version of the invention shown in Figures 15 and 16 may be used. For ease of illustration, there is shown a version of the universal joint of the present invention having two balls, but it should be understood that versions having three or four balls, such as those just described, or any practical number, may also be constructed in this manner.

In the quick-disconnect universal joint shown in Figures 15 and 16, there is an outer joint member 75 having a plurality of part-cylindrical rectilinear grooves 79 in which balls 83 are received, the balls occupying apertures in inner joint member 77. Deformations 76 are provided for retaining the inner joint member as previously described, but in this instance the inner joint member 77, because of its construction, can permit balls 83 to move inwardly toward the centre of the joint a distance sufficient to clear the deformations 76.

This is accomplished by having the inner drive member hollow in construction and provided with a plunger 81 having an inclined surface 81a against which the balls 83 rest. The plunger 81 is received in the hollow interior of the inner drive member 77 and is retained in its retracted position by a compression spring 82 which is shown in its normally extended position in Figure 5. The spring 82 is retained between a bearing portion 85 on the interior of the inner joint member and a land 87 provided on the plunger 81, so that when the plunger is pushed in a direction toward the outer joint member 75, the spring 82 will compress allowing the plunger to move axially towards the outer joint member, and the balls 83 to move towards the axis of the plunger.

Because of the dimensions of the plunger, the balls 83 move inwardly sufficiently to clear the deformations 76, thus allowing the disassembly of the inner joint member 77 from the outer joint member 75, as illustrated in Figure 16.

Thus, by abandoning prior art techniques, which require the rotation of the balls to be restricted, a novel constant velocity universal joint is provided. It should be understood that the invention is not limited to the foregoing embodiments, and that many changes and modifications can readily be made by one skilled in the art without departing from the scope of the claims appended hereto.

Claims

1. A universal joint for torque transmission comprising: an inner joint member having aperture means therein; a plurality of balls received in said aperture means for unrestricted rotation therein, said balls being arranged in said aperture means so that each of said balls has a portion in abutment with a portion of at least one other said ball, to provide mutual support therefor; an outer joint member having a plurality of spaced apart rectilinear grooves therein, each of said balls being received in one of said grooves; said inner joint member being capable of articulating relative to said outer joint member; and said balls providing for torque transmission between said joint members when not aligned with one another.

2. A joint according to Claim 1 further comprising means to maintain said inner joint member in driving engagement with said outer joint member.

3. A joint according to Claim 2, wherein said means to maintain said inner joint member in driving engagement with said outer joint member comprises a deformed portion of said outer joint member.

4. A joint according to Claim 3, comprising a plurality of deformations spaced circumferentially about said outer joint member.

5. A joint according to any one of the preceding claims, further comprising friction means, for establishing a frictional resistance to relative articulation between said joint members.

6. A joint according to Claim 5, wherein said friction means comprises a position element, within said outer joint member and abutting said inner joint member.

7. A joint according to Claim 6 wherein said position element is of a resilient material.

8. A joint according to any one of the preceding claims wherein said balls are circumferentially equidistantly spaced about the joint.

9. A joint according to any one of the preceding claims wherein each of said grooves is of part-cylindrical configuration.

10. A joint according to any one of the preceding claims wherein said plurality of balls consists of three balls.

11. A joint according to any one of Claims 1 to 9 wherein said plurality of balls consists of four balls.

12. A joint according to Claim 2 wherein said means to maintain said inner joint member in driving engagement with said outer joint member comprises an end cap fitted to said outer joint member.

13. A double universal joint comprising two joints according to any one of the preceding claims, said joints having a common outer joint member and respective inner joint members at the ends thereof.

14. A double universal joint according to Claim 13, as appendant to Claim 6 or Claim 7, comprising a single position element abutting both said inner joint members.

15. A quickly disconnectable universal joint for transmitting torque, comprising in combination: a hollow inner joint member; aperture means in said inner joint member; a spring mounted plunger mounted interior of said inner joint member; a plurality of balls received in said aperture means for unrestricted movements therein, and supported by said plunger; and an outer joint member having groove means therein to receive said balls.

16. A joint according to Claim 15, further comprising means to maintain said inner joint member in driving engagement with said outer joint member.

17. A joint according to Claim 16 wherein when said plunger means mounted in said inner joint is actuated, said balls are able to move inwardly toward each other and disengage said means to maintain said inner joint member in driving engagement with said outer joint member.

18. A joint according to Claim 17 wherein said means to maintain said inner joint member in driving engagement with said outer joint member includes a plurality of deformations about the circumference of said outer joint member.

19. A joint according to any of Claims 15 to 18 wherein said plurality of balls are circumferentially equidistantly spaced about said joint.

20. A joint according to any of Claims 15 to 19 wherein said groove means comprises a plurality of circumferentially spaced rectilinear grooves.

21. A tool drive comprising a universal joint according to any one of the preceding claims.

22. A power take-off system comprising a universal joint according to any one of the preceding claims.

23. A universal joint substantially as hereinbefore described with reference to Figures 7 to 9, or Figure 10, or Figures 11, 12 and 13, or Figure 14, or Figures 15 and 16, of the accompanying drawings.

24. A universal joint according to any one of the preceding claims, used in a torquetransmitting device substantially as hereinbefore described with reference to any one of Figures 1 to 6 of the accompanying drawings