Combined wing bearing and full circular bearing yoke connection for universal joint

A structure for connecting the cross member of a universal joint to two yokes includes at least a pair of wing bearings bolted to one of the yokes. Preferably, the other yoke utilizes full circular bores to receive the other two shafts of the cross member. The wing bearings include structure which ensures a secure connection to the yoke. In particular, a locator finger extends radially inwardly from the yoke and over the wing bearing and shaft. In this way, the distance between a reaction plane between the yoke and wing bearing and the centerline of the shaft within the wing bearing is reduced. This reduces a force moment on the shaft. In other features of this invention, the use of the full circular bore for one of the yokes allows the universal joint manufacturer to fully assemble the first yoke to the cross member, and ship that assembled yoke and cross member to the vehicle manufacturer. The vehicle manufacturer must only then assemble the yoke to its drive shaft, and bolt the two wing bearings to a second yoke. In this way, the vehicle manufacturer has no responsibility to properly lubricate the bearings in the universal joint. Thus, the bearings may be properly lubricated by the universal joint manufacturer, and should remain properly lubricated for the expected life of the universal joint.

BACKGROUND OF THE INVENTION
 The present invention relates to universal joints and to connection
 assemblies between a yoke and the shafts of a universal joint cross
 member.
 Modern vehicles are often equipped with universal joints that comprise a
 cross member having four shafts or trunnions. Bearings are mounted on each
 shaft, and two yokes are mounted onto opposed pairs of shafts. The yokes
 are mounted at positions spaced 90.degree. relative to each other and are
 each connected to drive shafts. This arrangement allows rotation to be
 transmitted through varying angles between the drive shafts, through
 varying angles. This type of universal joint is particularly popular in
 heavy duty vehicles such as trucks.
 Universal joint assemblies experience a great deal of stress and vibration
 and are exposed to a hostile environment on the underside of a vehicle.
 Thus, the connection between the yoke and the bearings should be secure
 and stable. Proper functioning of a universal joint also requires adequate
 lubrication between the bearings and the shafts. The universal joint
 designs utilized in the past have not always achieved these goals for yoke
 and cross member connections.
 Conventionally, universal joints have utilized yokes that have full
 circular or cylindrical bores to receive a bearing and shaft. The full
 circular bore surrounds and supports the bearing during operation of the
 universal joint. Typically, the two shafts on the cross member are
 inserted within the bores in the yoke. The bearings are then inserted
 radially inwardly through the outer end of the bore and onto the shafts.
 One problem with this arrangement is that since the bearings are inserted
 through the bores in the yoke after insertion of the shafts, the universal
 joint manufacturer has been unable to finally mount the bearings on the
 cross member shafts. Rather, the bearings must be mounted on the shaft at
 the vehicle assembly line. Typically, the assemblers at the vehicle
 assembly line are not as skilled in proper lubrication or assembly of
 universal joint bearings as assemblers at the universal joint
 manufacturer. For that reason, there has sometimes been improper
 lubrication or assembly of universal joints assembled on the assembly
 line.
 To address this problem, universal joints have been developed wherein the
 cross member may be preassembled with its bearings already attached. In
 one prior art universal joint, the cross member shaft and bearing lay in a
 half-circle bore in the yoke. Metal straps surround the bearing and are
 connected to the yoke with bolts. This prior art assembly requires tight
 dimensional control.
 In another prior art design, the bearing is connected to the yoke with
 bolts. The mounting bolts in this universal joint connection may become
 loose due to the high force moments. With either type of assembly, small
 locators on the bearing may be used to transmit rotation between the
 bearing and yoke. The small locators are placed relatively far from the
 centerline of the shaft. The locator provides a good deal of the reaction
 surface for torque transmission, and the distance from the shaft
 centerline results in relatively high force moments.
 SUMMARY OF THE INVENTION
 In a disclosed embodiment of the present invention, wing bearings support
 two shafts of a cross member and are bolted to a yoke. The yoke includes
 two opposed brackets, each having two arms forming a part-circular surface
 to receive the wing bearing and cross member shaft. The arms extend around
 more than 90.degree. of the bearing's outer periphery to provide a secure
 engagement between the yoke and bearing. The bearing includes a depression
 on an outer wall of the bearing cup. The yoke bracket includes a locator
 finger extending between the arms of the yoke bracket, and located in the
 bearing depression. Preferably, the fingers extend radially inwardly to
 overlay the needle bearings, and at least a portion of the shaft is
 received in the wing bearing. The extension places the finger relatively
 close to the center axis of the shaft, minimizing the moment.
 In another feature of the invention, the wing bearing includes a shoulder
 projecting from the periphery of the bearing. A yoke receiving the bearing
 has a mating surface disposed between the bracket arms. The shoulder
 contacts the mating surface to provide a secure connection between the
 bearing and the yoke, and inhibit rotation of the bearing in the yoke. In
 a preferred embodiment, the yoke also includes a lip extending beyond the
 mating surface, and between the bracket arms to overlay a top portion of
 the shoulder.
 The inventive universal joint preferably combines one yoke having the prior
 art full circular bore mounting two shafts and a second yoke utilizing the
 above-described wing bearings which are bolted to the yoke. The universal
 joint manufacturer may preassemble a yoke having full circular bores onto
 two of the shafts of the cross member with its associated bearings. In
 this way, the universal joint manufacturer is able to insure proper
 lubrication of those bearings. The universal joint manufacturer may then
 mount the wing bearings onto the other two shafts of the cross member. The
 yoke and assembled cross member may then be shipped to the vehicle
 manufacturer. When the vehicle manufacturer assembles the drive line of
 the vehicle, the assembler at the vehicle assembly line need only bolt the
 wing bearings to a second yoke. Thus, the benefits of the full circular
 bore are obtained for two of the shafts, and the benefits of utilizing a
 wing bearing are obtained for the other two shafts.
 In a method of assembling a universal joint utilizing the present
 invention, the universal joint assembler mounts a conventional first yoke
 having full circular bores onto two of the shafts. Wing bearings are
 mounted on the other two shafts. That assembled yoke is then transported
 to the vehicle assembler. The vehicle assembler assembles the drive line
 to include the first yoke, and bolts the wing bearings onto a second yoke.
 In this way, the assembler at the vehicle assembly line is not required to
 provide any lubrication for the bearings.
 With this inventive solution, applicant has developed universal joints that
 require no maintenance lubrication. By insuring the proper lubrication is
 provided at the initial assembly, no routine lubrication maintenance is
 required. Thus, once assembled, the universal joint will be permanently
 lubricated for its expected life.
 These and other features of the present invention will be best understood
 from the following specification and drawings, of which the following is a
 brief description.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
 Universal joint 20 is illustrated in FIG. 1, and incorporates two yokes 22
 and 24 and a cross member 26. Yokes 22 and 24 are each received on two
 opposing shafts of cross member 26.
 The connection between yoke 22 and cross member 26 is conventional. As
 shown in FIG. 2, yoke 22 includes a pair of opposing arms 25 each having a
 bracket 29 defining a full circular bore 32. The bracket 29 defines a full
 circular bore 32 by surrounding the bore over 360.degree. as shown in FIG.
 2. The method of connecting shafts 28 to yoke 22 includes inserting shafts
 28 into bores 32. Bearings 34 are then mounted onto shafts 28 by inserting
 a receiving cup of bearing 34 radially inwardly into bores 32, and onto
 shafts 28. Rings 36 are then snapped over a face 31 of bearing 34
 retaining bearing 34 in bore 32.
 The connection between yoke 24 and cross member 26 utilizes wing bearings
 38, as described further below. Although, the disclosed embodiment shows
 only one yoke utilizing wing bearings, it should be understood that some
 of the benefits disclosed in this application may apply to universal
 joints where both yokes use wing bearings. Yokes 22 and 24 are each
 connected to drive shafts 23.
 Cross member 26 includes two pairs of shafts 28 and 30. The shafts in each
 pair are spaced 180.degree. from the other. Shafts 28 are spaced
 90.degree. from shafts 30. A wing bearing 38 is mounted onto each shaft
 30. Wing bearing 38 has a bearing receiving cup 40 and a pair of opposed
 wings 42, each having a bolt hole 44. Wing bearings 38 also include a
 depression 46 formed on an outer face.
 Yoke 24 includes two opposed brackets 50 which each receive a wing bearing
 38. Bracket 50 includes a pair of arms 52, which each include a threaded
 bore 54. A finger 56 extends between arms 52 of each bracket 50. A mating
 surface 62 is disposed between bracket arms 52 adjacent locator finger 56.
 As shown in FIG. 3, bolts 58 pass through wing bearing bolt holes 44 and
 are threadably received in threaded bores 54 to secure wing bearing 38,
 and thus shaft 30 to yoke 24. Finger 56 of bracket 50 is received in
 depression 46 of wing bearing 38. During assembly of universal joint 20,
 finger 56 helps to properly locate wing bearing 38 in bracket 50 of yoke
 24.
 Finger 56 also provides a main contact surface to transmit forces between
 the yoke and bearing during rotation. That is, a main reaction plane of
 the forces between the yoke and bearing during rotation is defined at the
 finger 56. In prior art wing bearings, the reaction plane has been spaced
 radially outwardly from the nominal outer periphery of the needle bearing
 surfaces. As such, a relatively large force moment is created between that
 reaction plane and the centerline of the shaft. This is undesirable. With
 applicant's invention of finger 56 extending radially inwardly over the
 wing bearings 38, the force moment has been greatly reduced.
 As shown in FIG. 4, bearing 38 includes a shoulder 60 which projects from a
 periphery and between wings 42. Shoulder 60 spans at least 45.degree.
 around the periphery of wing bearing 38, as measured from the centerline
 of shaft 30. Preferably, shoulder 60 spans between 90.degree. and
 120.degree. around the periphery of bearing 38. In one embodiment,
 shoulder 60 spans approximately 100.degree. around the periphery of
 bearing 38. Bearing 38 is received between bracket arms 52, and shoulder
 60 contacts mating surface 62 of bracket 50. Mating surface 62 helps align
 bearing 38 and also cooperates with mating surface 62 to prevent bearing
 38 from rotating in bracket 50, thereby reducing forces which tend to
 loosen the bolts 58.
 Bracket arms 52 extend forward of bracket 50 and at least partially
 surround shafts 30 to provide additional stability. The distance between
 arms 52 and the centerline of shaft 30 is significantly reduced.
 Preferably, ends 63 of arms 52 are spaced by at least 90.degree. measured
 about the periphery of shaft 30. Thus, the arms 52 surround wing bearing
 38, providing a secure connection.
 Lip 64 extends between bracket arms 52 and outwardly of mating surface 62
 to overlay a top portion of shoulder 60 of wing bearing 38. Lips 64 of
 opposed brackets 50 provide additional vibrational stability to the
 universal joint 20 by constraining wing bearings 38.
 Finger 56 extends into depression 46, which extends over needle bearings
 66, and at least a portion of shaft 30 to provide additional stability as
 described above. By extending over needle bearings 66 and at least a
 portion of shaft 30, finger 56 reduces the distance between the reaction
 plane and the centerline of shaft 30 and finger 56.
 There are mating surfaces shown at 70 between the bearing and the yoke.
 Those mating surfaces 70 and the finger 56 and depression 46 are the only
 machined surfaces. The bearings and yokes are otherwise as forged or cast.
 Surfaces 70 provide additional guidance.
 In a method of assembling a universal joint according to the present
 invention, a cross member 26 is initially inserted into a yoke 25 that has
 full circular bores 32. Bearings 34 are then moved inwardly through the
 bore 32 to secure the cross member 26 within yoke 25. Rings 36 are then
 driven inwardly through the bore 32 to secure bearings 34 within their
 respective bores 32.
 Wing bearings 38 are mounted on the shafts 30 of cross member 26. The
 assembled yoke 25 and cross member 26 may then be shipped. At a vehicle
 assembly line, vehicle assemblers need only bolt the wing bearings 38 to
 the second yoke 24. The vehicle assembler need not remove any bearing from
 the cross member, and further must only bolt one set of bearings to a
 yoke. The yoke 25 utilizes the prior art full circular bores 32, which
 provide a very secure and desirable connection. At the same time, since
 the assembler need not add any bearings onto the shafts 28 or 30, the
 vehicle assembler is not involved in the lubrication of the universal
 joint bearing. For that reason, the universal joint manufacturer may
 insure proper lubrication of the bearing, and may lubricate the bearing
 such that maintenance and routine further lubrication of the universal
 joint should not be necessary during the expected life of the universal
 joint. This is a valuable benefit.
 A preferred description of this invention has been disclosed; however, a
 worker of ordinary skill in the art would recognize that certain
 modifications would come within the scope of this invention. For that
 reason, the following claims should be studied to determine the true scope
 and content of this invention.