Background Art Runout or wobble in the road wheels of an automotive vehicle detracts from the handling of the vehicle and the performance of its brakes.

Preloaded bearings at the road wheels eliminate one source of runout and further enhance the stiffness of the wheel mounting. In this regard, a road wheel of a vehicle typically rotates on two bearings, each of which has the capacity to transfer both radial and axial loads-single row tapered roller or angular contact bearings for example. The arrangement lends itself to adjustment-indeed, adjustment between a condition of endplay and reload. When bearings operate in endplay, internal clearances exist within them and this can contribute to runout. The bearings should operate in preload to eliminate at least one source of runout and to improve the tilting stiffness of the mounting. But too much preload can damage the bearings and rob the vehicle of power. Thus, wheel bearings must be adjusted or set with a good measure of precision.

Owing to the precision with which wheel bearings must be set, the manufacturers of automotive vehicles prefer to leave that aspect of production to the suppliers of the bearings. They have responded with a variety of wheel ends provided with preset bearings. In such a wheel end, at least one of the races must initially be separate from other components of the assembly to accommodate installation and adjustment of the bearings, but afterwards the initially separate race must be clamped in position to hold the wheel end and its bearings together and to maintain the

proper setting for the bearings. Some manufacturers roll form a portion of the hub against the initially separate race, which produces a highly compact and light weight assembly at a reasonable cost.

Where the hub mounts a driven wheel, the hub must accommodate a constant velocity (CV) joint in order to transfer torque from a drive shaft to the driven wheel. But the roll-formed end on the hub interferes with the CV joint, making it difficult to obtain an adequate coupling between the CV joint and the hub, particularly for some vehicles such as light trucks. The absence of a roll-formed end allows for a more effective transfer of torque, but in this arrangement, the CV joint abuts the initially separate bearing race and holds it in place and the entire bearing-and indeed wheel end- together. Thus, when the CV joint is not present, the bearing and hub assembly may come apart.

Summary of the Invention The present invention resides in a wheel end including a housing, a hub provided with a spindle that extends into the housing, and an antifriction bearing that enables the hub to rotate relative to the housing.

The bearing includes an inner race that is located around the spindle and is secured in position by a retaining ring that is located between the race and a formation on the spindle. The invention also resides in a process for unitizing a wheel end with the ring.

Brief Description of Drawings Fig. 1 is a longitudinal sectional view of a unitized wheel end coupled with a CV joint, all in accordance with and embodying the present invention; Fig. 2 is an enlarged sectional view of the wheel end; and Fig. 3 is a fragmentary sectional view of a loose ring form and a roll- forming tool for deforming it into a groove in a hub that forms part of the wheel end.

Best Mode for Carrying Out the Invention Referring now to the drawings, a wheel end A includes (Fig. 1) a hub B and a housing C into which the hub B extends, and in addition an antifriction bearing D which enables the hub B to rotate relative to the housing C about an axis X of rotation. The hub B may be coupled to a constant velocity (CV) joint E for transferring torque from a drive or half shaft F to the hub B and thence to a wheel G that is mounted on the hub B.

The CV joint E accommodates displacement, both vertical and pivotal, between the hub B and drive shaft F without disrupting the transfer of torque. The wheel end A is highly compact, light in weight, and has the capacity to transfer a large amount of torque to the road wheel G, given its size. It is further unitized so that it remains together before and during installation on an automotive vehicle and even during the operation of the vehicle.

Considering the housing C first (Fig. 2), it may take the form of a suspension system member, such as a steering knuckle, or a separate component bolted to a suspension system member. Whatever its form, it has bores 2 and counterbores 4 that open out of its ends. The bores 2 end at shoulders.

The hub B extends (Fig. 2) through the bores 2 and out of the outboard counterbore 4 where it lies beyond the outboard face of the housing C. To this end, the hub B has a spindle 8 which extends into the bores 2 and counterbores 4 of the housing C, with its centerline and axis coincident with the axis X, and a flange 10 at the outboard end of the spindle 8. Indeed, the spindle 8 and flange 10 are formed integral as a single forging or casting. Externally, the spindle 8 has a tapered raceway 12 that leads up to a rib 14 that is adjacent to the flange 10. Both the raceway 12 and rib 14 form part of the bearing D. At its opposite or inboard end the spindle 8 has a bearing seat 16 which leads away from a shoulder 18 and opens onto an external spline 20 that leads out to the inboard end

of the spindle 8. In diameter, the spline 20 does not exceed that of the bearing seat 16. Opening out of the spline 20 remote from the inboard end of the spindle 8 is an annular groove 22 (Figs. 2 & 3) of generally rectangular cross section. As such, the groove 22 has distinct corners. The groove 22, particularly its radially directed surface closest to the inboard end of the spindle 8, which surface is actually the end of the spline 20, forms an annular formation on the spindle 8. While the formation need not be radially directed, it should be oriented at a substantial angle to the axis X, such as an oblique undercut at perhaps 70° with respect to the axis X.

Internally, the spindle 8 has a threaded bore 24 that generally lies within the bearing seat 16.

The flange 10 (Fig. 2) extends radially from the outboard end of the spindle 8 and obscures the outboard counterbore 4 and the surrounding face of the housing C. The flange 10 has a machined face 30 that is presented away from the housing C and threaded studs 32 which project axially beyond the face. In addition, the flange 10 has a wheel pilot 34 which projects axially beyond the machined face 30. The road wheel G fits over the studs 32 where it is backed by the machined face 30 of the flange 10. Typically, a brake disk is interposed between the machined face 30 and the wheel G. The pilot 34 serves to center the wheel G with respect to the hub B so that its center coincides with the axis X. Within the pilot 34 the hub B is hollow-indeed, it is hollow throughout its length with its region of least diameter being the threaded bore 24 of the spindle 8.

The raceway 12 and rib 14, aside from being on the spindle 8, form part of the bearing D-indeed, an inner race. In addition, the bearing D has an outer race which takes the form of two cups 40 that are pressed into the bores 2 of the housing C and against the shoulders at the ends of those bores 2, there being interference fits between the exterior surfaces of the cups 40 and the surfaces of the bores 2. Each cup 40 has a tapered raceway 42 that is presented inwardly toward the axis X and further tapers

downwardly toward space between the two cups 40. The raceway 42 for the outboard cup 40 is presented toward and tapers in the same direction as the raceway 12 on the spindle 8. Between the two raceways 12 and 42 at the outboard end of the spindle 8 are rolling elements in the form of tapered rollers 44 arranged in a single row. The rollers 44 are on apex, meaning that the conical envelopes in which the side faces of the rollers 44 lie have their apices at a common point along the axis X. The tapered outboard raceways 12 and 42 also have the apices of their conical envelopes at the same point. To maintain the proper separation between the rollers 44, the rollers 44 are fitted with a cage 46 which also serves to hold the rollers 44 around the spindle 8 before the hub B is installed in the housing C.

Completing the bearing D is a cone 50 and another row of rolling elements, also in the form of tapered rollers 52, together with a cage 54 that is located within the row of rollers 52. The cone 50, which forms an initially separate inner race, fits around the bearing seat 16 and has a tapered raceway 56 which is presented outwardly away from the axis X and toward the raceway 42 on the inboard cup 40. The two inboard raceways 42 and 56 tapered in the same direction, which is opposite to the direction in which the outboard raceways 12 and 42 taper, and the apices of their conical envelopes lie at a common point along the axis X. While the raceway 56 forms much of the exterior surface of the cone 50, the interior surface lies along a cone bore 58, the size of which produces a slight interference fit with the bearing seat 16. Beyond the small end of its raceway 56 the cone 50 has a front face 60 which is perpendicular to the axis X. Here the cone 50 abuts the shoulder 18 on the spindle 8. At the large end of its raceway 56 the cone 50 has a thrust rib 62 which leads out to a back face 64 that is for the most part perpendicular to the axis X. The back face 64 merges into the cone bore 58 at a chamfer 66 which lies at about 45° with respect to the axis X. The chamfer 66 surrounds the groove 22 in the spindle 8 or at least

the back half of the groove 22. Like the rollers 44 of the outboard row, the rollers 52 of the inboard row are on apex. The cage 54, in addition to maintaining the proper spacing between the rollers 52 of the inboard row, also holds the rollers 52 around the cone 50 when the cone 50 is detached from the spindle 8.

The axial position of the cone 50 along the spindle 8 determines the setting for the bearing D, and that setting should be one of slight reload.

When set to reload, the bearing D has no internal clearances and radial and axial free motion between the hub B and housing C does not exist. To this end, the cone 50 at its front face 60 is ground to a position which provides the bearing D with the correct setting.

The initially separate cone 50 is maintained on the spindle 8 by a retaining ring 70 which fits into the groove 22 of the spindle end also into the chamfer 66 of the cone 50. The ring 70 projects out of the groove 22 and into the chamfer 66, so that the cone 50 cannot be displaced axially away from the shoulder 18. Thus, the cone 50 is captured between the shoulder 18 and the retaining ring 70. The retaining ring 70 is formed from a metal, preferably a steel, that has been worked into the groove 22.

The bearing D is protected at each of its ends by seals 72 which fit into the counterbores 4 of the housing C. The outboard seal 72 establishes dynamic fluid barriers along the back face of the flange 10 and along the nearby rib 14. The inboard seal 72 establishes dynamic fluid barriers around the thrust rib 62 of the cone 50.

To install the hub B in the housing C, the cups 40 of the bearing D are pressed into the bores 2 of the housing C. Next, the outboard rollers 44 and cage 46 are placed along the raceway 42 of the outboard cup 40 using, if desired, the procedure set forth in U. S. patent application Serial No. 10/125, 309 of T. Rybkoski, R. Miller, and R. Hacker filed 17 April 2002 and entitled"Method of Assembling a Package Bearing and Assembly Tool Therefor". Once the outboard rollers 44 and cage 46 are in place, the

outboard seal 72 is pressed into the outboard counterbore 4 of the housing C. Then the spindle 8 of the hub B is inserted into the housing C. It advances through the rollers 44 of the outboard row until its raceway 12 encounters the rollers 44.

After the hub B is rotated to insure that the rollers 44 of the outboard row seat against the raceway 42 of the outboard cup 40 and the raceway 12 and rib 14 on the hub B, measurements are taken from the shoulder 18 on the hub B and the raceway 42 of the inboard cup 40 to determine the proper axial extension for the cone 50, that is to say, the location for its front face 60. The cone 50, if necessary, is thereupon ground at its front face 60 to match that location. Once the cone 50 is properly dimensioned, it is advanced over the spline 20 on the spindle 8 and pressed onto the bearing seat 16. Here its front face 60 is presented opposite to the shoulder 18 on the spindle 8. The chamfer 66 at the back face 64 of the cone 50 locates around the groove 22 in the spindle 8. Indeed, the chamfer 66 and the groove 22 form an annular pocket that opens generally away from the cone 50.

Thereafter, a ring form 74 (Fig. 3) having an inside diameter slightly larger than the spline 20 on the spindle 8, is advanced over the spline 20 and against the chamfer 66 on the cone 50. The ring form 74 may have a circular cross-section, but whatever its cross section, in area it generally equals that ultimately desired for the retaining ring 70. The ring form 74 should be formed from a metal, preferably steel, that is more malleable than the steel of the cone 50 and spindle 8. To render the ring form 74 malleable, it may be heated, such as by induction heating, to elevate its temperature. The loose ring form 74 becomes the retaining ring 70 by plastically deforming it into the groove 22. To this end, a roll-forming tool 76, which may have swaging balls 78 that rotate in sockets, is brought against the loose ring form 74 while the hub B rotates in the housing C.

The rotation enables the outboard rollers 44 to seat against their raceways

12 and 42 and the inboard rollers 52 to seat against their raceways 56 and 42. The force imparted by the swaging balls 78 of the roll forming tool 76 plastically deforms the ring form 74 into the pocket formed by the chamfer 66 and the groove 22, causing it to acquire the shape of the chamfer 66 and the groove 22. The deformation of the ring form 74 to create the ring 70 leaves the ring 70 work hardened. Moreover, the force drives the cone 50 still farther over the spindle 8, causing its front face 60 to abut the shoulder 18 on the spindle 8. In so doing, the bearing D enters reload. And the retaining ring 70 that derives from the loose ring form 74 holds the bearing D in reload, and keeps the cone 50 from moving off the spindle 8. In short, the retaining ring 70 holds the bearing D together, and the bearing D unitizes the wheel end A. The unitized wheel end A may be shipped or stored and later installed on an automotive chassis without the risk of coming apart. The wheel end A may also be placed in service with only the ring 70 unitizing it.

After the retaining ring 70 is in place, the inboard seal 70 is installed into the inboard counterbore 4 and around the thrust rib 62 of the cone 50.

The CV joint E (Fig. 1) not only transfers torque from the drive shaft F to the wheel hub B, but further provides an extra measure of assurance that the wheel end A remains unified. To this end, the CV joint E has a shell 80 provided with a semispherical section 82 and a smaller end portion 84 which extends axially from the semispherical section 82. While the semispherical section 82 is larger then the inboard counterbore 4 and lies generally beyond the housing C, the axially directed end portion 84 projects into the outboard counterbore 4 and over the external spline 20 on the spindle 8. Here the end portion 84 at its very end abuts the squared off portion of the back face 64 on the cone 50. Moreover, the axially extended end portion 84 has an internal spline 86 which mates with and engages the external spline 20

on the spindle 8. Also, the end portion 84 has a shoulder 88 located behind the spline 86. The semispherical portion 82 has arcuate ways 90.

The drive shaft F extends into the semispherical section 84 and is fitted with a drive element 92 that is provided with arcuate ways 94 which are located opposite the arcuate ways 90 in the shell 80. The drive element 92 and the shell 80 are coupled together through balls 96 which occupy the opposed ways 90 and 94, and the balls 96 are maintained in a row by a cage 98. Thus, torque applied to the shaft F is transferred to the shell 80 through the balls 96, yet the shaft F need not remain aligned with the axis X of the hub B and bearing D.

The end face of the axially directed end portion 84 on the shell 80 of the CV joint E remains firmly against the back face 64 of the cone 50, owing to a connector 100 which is engaged with the spindle 8 of the hub B. The connector 100 includes a threaded end 102 which extends into the hollow interior of the spindle 8 where its threads engage the threads of the threaded bore 24. The connector 100 has flange 104 which extends from the threaded end 102 beyond the inboard end of the spindle 8 and lies behind the shoulder 88 in the end portion 84 of the CV joint E. Finally, the connector 100 has a socket 106 which opens axially out of its threaded end 102 and into the hollow interior of the spindle 8. The socket 106 is configured such that it can be engaged by a wrench extended through the hollow interior of the spindle 8. When the socket 106 is engaged and the connector 100 is turned in the proper direction, the flange 104 bears against the shoulder 88 in the shell 80 of the CV joint E and drives the end portion 84 of the shell 80 firmly against the back face 64 of the cone 50.

This insures that the front face 60 of the cone 50 remains against the shoulder 18 on the spindle 8 and that the bearing D maintains the correct setting, preferably reload.

While the ring form 74 may be plastically deformed into the groove 22 behind the cone 50 by means of roll forming, it may also be plastically

deformed into the groove 22 simply by applying an axially directed force against it in the absence of relative rotation between the deforming tool and the hub B. Also, the retaining ring 70 need not be the product of a plastic deformation at all. Instead, it may take the form of a hardened snap ring or circlip having an inside diameter less than the spline 20 at the end of the spindle 8, but including a slight gap so that it can be expanded to pass over the spline 20 and then snap into the groove 22. When a hardened snap ring serves as the retaining ring 70, the chamfer 66 on the back face 64 of the cone 50 may have to be ground to insure that the ring 70 fits into the groove 22 between the back of the groove 22 and the chamfer 66 on the cone. The grinding of the chamfer 66 may occur when the front face 60 of the cone 50 is ground. In any event, the retaining ring 70, whether it be roll formed, simply pressed, or snapped into the groove 22, should fit snugly between the chamfer 66 on the cone 50 and the back of the groove 22 which is in effect the end of the spline 20. In other words, the retaining ring 70, irrespective of how it is fitted to the groove 22, should be compressed between the chamfer 66 on the cone 50 and the formation that forms the back of the groove 22. This state of compression insures that the front face 60 of the cone 50 remains against the shoulder 18 of the spindle 8, so that the bearing D maintains the correct setting. Moreover, the chamfer 66 insures that the ring 70 remains in the groove 22, since its bevel urges the ring 70 inwardly toward the axis X.

The housing C need not be a suspension system component in and of itself. Instead, it may be a separate component that is bolted or otherwise secured to the suspension system component. Also, the two cups 40 of the bearing D may be integrated into a single double cup, that is to say, a single cup having the two outer raceways 42 located in it. By the same token, the two outer raceways 42 may be formed directly on the housing C itself. Conversely, the outboard inner raceway 12 and its thrust

rib 14 may be on a separate cone fitted over the spindle 8 with the front face of that cone serving as the shoulder 18.

Moreover, the wheel end A may be used as a mounting for a nondriven wheel G, in which event the spline 20 at the end of the spindle 8 is not necessary, nor of course, is the CV joint E. In the absence of the CV joint E, the ring 70 itself will keep the wheel end A unitized, but to provide an extra measure of securement, a backing element may be threaded into the bore 24 of the spindle 8 and turned down against the back face 54 of the cone 50.