Differential unit having an adjustable bearing assembly

A vehicle differential unit including adjustable bearing assemblies has a differential carrier adapted to support a differential case assembly including differential case bearings associated therewith. The differential case bearing assemblies rotatably support the differential case assembly within the carrier of the differential unit. Adjusting rings are provided and supported internally in the differential carrier. The adjusting rings are selectively biased against the bearing assemblies to impart the desired bearing preload and backlash within the differential unit. The adjusting rings replace the use of adjustment shims, and are accessible to permit adjustment if necessary without the need to remove the differential case assembly. The adjusting rings are threadably supported on the carrier and the adjusting rings are further provided with internal splines sized to engage the axle shaft splines to provide an convenient and effective bearing adjustment of the differential unit.

BACKGROUND OF THE INVENTION
 a) Field of the Invention
 The invention relates in general to automotive differential units having an
 adjustable differential carrier and bearing mounting assembly.
 b) Description of Related Art
 Differential units for automotive or similar uses are well-known in the
 prior art, and generally comprise a differential case rotatably mounted in
 a differential carrier by spaced bearing assemblies adapted to accurately
 center the differential case within the differential carrier and
 accurately position the ring gear relative to the drive pinion A problem
 has existed in such differential units with respect to the mounting of the
 bearings for the differential case or rotor so as to provide the desired
 amount of backlash between the pinion and ring gear of the differential
 gear assembly or to eliminate end play of the rotor. Proper engagement of
 the ring gear carried by the differential case with the driving pinion is
 necessary for proper operation, and subsequent wear of the gears or
 bearings will result in misadjustment of backlash, thereby requiring
 adjustment of the bearings. Generally, the prior art differential case
 bearings have been made adjustable by means of adjustment shims used to
 provide preload on the differential case bearings. In the use of such
 adjustment shims, it is often necessary to remove the differential case
 assembly to adjust backlash or bearing preload, which creates additional
 labor and adds cost to such an adjustment procedure.
 There have been several attempts to provide differential units having
 adjustable bearing assemblies, but have heretofore been relatively
 complex. Such constructions have included various tools and gear
 assemblies to effect adjustment of a plurality of shims. Other
 constructions have been found to degrade the structural integrity and
 rigidity of the differential unit in association with the axles of the
 vehicle. It is generally necessary to provide adequate stiffness or
 rigidity for the bearing assemblies in the differential unit, especially
 under heavy load conditions.
 Additionally, prior art bearing mounting assemblies which include an
 adjustment mechanism have generally resulted in a differential unit having
 increased costs associated with either the manufacture of the components
 or the assembly thereof
 SUMMARY OF THE INVENTION
 Based upon the foregoing, there has been found a need to provide a bearing
 mounting assembly associated with a differential unit which facilitates
 easy adjustment of the bearing assembly. It is therefore an object of the
 invention to provide an adjustable bearing assembly for a differential
 unit which overcomes the deficiencies of the prior art and permits
 adjustment of bearing preload and backlash within the differential unit
 without the use of adjustment shims.
 In a preferred form, the differential unit comprises a differential carrier
 adapted to support a differential case assembly including differential
 case bearings associated therewith. The differential case bearing
 assemblies are rotatably supported on the differential case assembly
 relative to the carrier and gears of the differential unit. Adjusting
 rings are threadably engaged with and supported internally of the
 differential carrier. The differential case assembly is installed into the
 carrier. The adjusting rings are selectively biased against the bearing
 assemblies to impart the desired bearing preload and backlash within the
 differential unit. The adjusting rings replace the use of adjustment
 shims, and are accessible to permit adjustment if necessary without the
 need to remove the differential case assembly. The construction of the
 differential unit simplifies manufacturing and gives more rigidity so as
 to maintain proper engagement of the ring and pinion gears.
 Notably, the axle shaft themselves are used to adjust the adjusting rings,
 whereby the axle shafts are installed to a depth that the shaft spline
 engages with an internal spline of the adjusting ring. Using a spanner
 wrench on shaft flanges, the gear position and bearing preload are
 adjusted by moving the adjusting ring(s). When the correct position is
 achieved, a lock pin is assembled into the carrier and through one of the
 holes of the adjusting ring. The bearing cap joints are torqued at this
 time to thereby provide a securely aligned assembly.

DETAILED DESCRIPTION OF THE INVENTION
 Referring now to the drawings, and more specifically to FIG. 1, a vehicle
 different unit includes a differential housing 10, which is assembled so
 as to be connected to rear wheel axle tubes 12. The differential carrier
 10 is adapted to be secured to the underside of the vehicle. Motive power
 is fed into the differential through a power input pinion 14, which is
 secured on the end of a drive shaft (not shown). The power input pinion
 gear 14 is adapted to mesh with a ring gear 16, which is secured to the
 periphery of a differential rotor or case 18. The ring gear 16, and the
 differential case 18 to which it is attached, are rotated in the
 stationary differential carrier 10 by means of the pinion gear 14. The
 rotary motion of the differential case 18 is imparted to the drive axles
 and wheels (not shown), wherein the drive axles are coupled to an output
 beveled gear set 20 which permit each of the drive axles to be driven at
 different speeds. The differential case assembly 18 is substantially of
 conventional construction, and also includes a plurality of planetary
 gears 22 adapted to mesh with the opposed output gears 20. Efficient
 operation of the differential depends upon the precise centering of the
 differential case assembly 18 in the differential carrier 10 for proper
 meshing engagement of the ring gear 16 with the pinion gear 14. To
 accomplish this, the differential case 18 is rotatably supported in the
 differential carrier 10 by means of infinitely adjustable bearing
 assemblies indicated generally at 24 and 26. The bearing assemblies 24 and
 26 are preferably provided as pre-assembled anti-friction bearing units
 having associated bearing caps 28 adapted to be bolted to a bearing block
 the differential carrier 10.
 Turning to FIG. 2, one of the bearing assemblies of the invention is seen
 more distinctly. As seen in this figure, the plurality of planetary gears
 22 respectively mesh with the opposed output gears 20, which are in turn
 secured to the axle shaft 30 disposed within axle tube 12. Interposed
 between each output gear 20 and an adjacent annular radial wall 19 of the
 differential case 20 is a limited slip clutch 32 of the conventional
 pre-loaded spring type, acting to minimize excessive slipping of one drive
 wheel relative to the other. The differential case 18 terminates at each
 lateral end with a cylindrical hub 34 adapted to be engaged by the inner
 race 36 of the pre-assembled anti-friction bearing unit 24. A tapered or
 wedge shaped outer bearing race 38 is supported by a semi-cylindrical
 bearing cap retainer 28.
 Disposed adjacent to the rear wheel axle tube 12 is an adjusting ring 44.
 The adjusting ring 44 is provided with external threads 45, which are
 adapted to engage internal threads 11 formed on the carrier 10. The
 adjusting ring 44 further comprises internal splines 46 designed to mate
 with the splines 31 provided on the axle 30.
 The adjusting ring 44 is threaded into the carrier 10. The differential
 case 18 and its differential assembly are then installed into the carrier
 10. The bearing caps 28 and bolts 29 are then installed but not torqued.
 The axle shafts 30 are then installed to a depth that the shaft splines 31
 mate with the internal splines 46 of the adjusting ring 44. Using a
 spanner wrench to engage axle shaft flanges (not shown), the ring gear
 position and bearing preload are adjusted by moving the adjusting rings
 44. When the correct position is achieved, the lock pin 49 is assembled
 into the carrier and through one of the holes 47 in the periphery of the
 adjusting ring 44.
 Using the axle shaft splines to adjusting bearing preload has been found to
 simplify manufacture of the differential unit. In the invention, the
 internal threading within the differential carrier 10 is easily performed,
 and the construction allows a hardened steel adjusting ring 44 to be used
 in association with the carrier 10. This simplifies manufacture and
 facilitates proper load bearing in the adjusting ring 44 to maintain the
 desired structural integrity. For adjustment, the adjusting ring 44 will
 be rotated so as to thread into or out of the carrier 10 for selective
 adjustment of its position relative to differential housing 10. The
 adjusting ring 44 includes an outer flange portion 48 having a contact
 surface 50 associated therewith, which is adapted to engage the tapered
 bearing race 38. The adjusting ring 44 therefore provides the load bearing
 structure supporting differential case 18 within carrier 10.
 The adjusting ring 44 is shown more distinctly in FIGS. 3 and 4, wherein it
 is seen that ring 44 is a cylindrical member having a center aperture 52
 through which a vehicle drive axle extends. The threaded external surface
 45 provides the engagement surface for securing the adjusting ring 44 to
 the interior of carrier 10 as previously described.
 Through a combination of casting and machining tolerances, it will be
 unlikely that the axial location of the differential rotor or case 18 will
 be properly positioned, and various problems will thus be encountered.
 Upon engagement of the bearing retaining cap 28 to seat the bearing
 assemblies, end play of the differential case 18 within the differential
 housing 10 will be observed along with possibly inaccurate axial
 positioning of the differential case resulting in improper engagement of
 the ring gear 16 with the pinion gear 14. For this reason, each
 anti-friction bearing assembly 24 and 26 of the differential unit may be
 adjustable to permit proper centering, and the application of a
 preselected preload on the differential case bearings. The bearing
 assemblies will also permit adjustment if necessary when preloading forces
 start to drop due to wear. Although in the preferred embodiment, both
 bearing assemblies 24 and 26 will be adjustable by means of an adjusting
 ring 44 and associated structure, adjustment may be provided for only one
 of the bearing assemblies 24 and 26 if desired.
 By means of the contact surface 50 of adjusting ring 44, the location of
 the tapered bearing race 38 is infinitely adjustable so as to provide the
 desired bearing preload and backlash in the differential unit. It is also
 seen in FIG. 3, that the adjusting ring 44 includes a plurality of
 lightening holes or oil apertures 54 provided therein, which reduce the
 weight of the adjusting rings 44 and permit oils to flow to and from the
 bearings 24, 26 and axles 30. Further, the adjusting ring 44 includes a
 plurality of apertures 47 (12 shown in FIG.3) to allow adjustment and
 locking of the adjustment ring 44 in the desired position. The apertures
 47 are spaced to allow any desired incremental change in the position of
 adjustment ring 44.
 It should be evident that upon threading of adjusting ring 44 outwardly
 from the axle tube 12 into the carrier 10, additional loading force is
 imparted to the outer bearing race 38. The tapered design of bearing race
 38 essentially provides a ramp upon which the bearings of the assembly are
 carried. Upon the inward urging of the tapered bearing race 38, adjustment
 of the differential case bearing preload and backlash can be achieved. The
 inner race 36 of the bearing assemblies 24 and 26 is pressed onto a
 reduced end portion of the differential case 18 and against a thrust
 shoulder such that the bearing assembly will carry the thrust loads of the
 differential case in a single direction. The adjusting ring 44 will in
 turn carry the thrust load placed upon the bearing assembly to a great
 extent. As the internal threaded engagement of the adjusting ring 44
 within carrier 10 allows hardened steel parts to be used, these loads are
 better accommodated in this construction. It should be understood that the
 differential case bearing assembly at the opposite end of the differential
 case 18 as seen in FIG. 2, is identical to the bearing assembly as
 described, except that it will be reversed to carry a thrust load in the
 opposite direction as desired. By proper positioning of the bearing
 assemblies in the differential unit, end play between the differential
 case 18 and differential carrier 10 will be eliminated, and the
 differential case 18 may be centered in the carrier 10 for proper
 engagement of the ring gear 16 with pinion gear 14 during assembly of the
 differential case 18 to differential carrier 10.
 In the assembly operation, drive axles 30 of the vehicle are installed to
 an adjustment depth wherein the external splines 31 of the shaft 30,
 normally designed to engage the side gears 20 during operation, engage
 internal splines 46 of the adjusting ring 44. The adjusting rings 44 are
 initially fully retracted along the carrier 10 on both sides of the
 differential unit, to allow assembly of the differential case 18 within
 the differential carrier 10. The differential case assembly 18 is placed
 in the carrier 10 with the tapered differential case bearings assembled on
 both sides thereof The bearing caps 28 are then mounted and the bolts 29
 are installed, but not completely tightened, to seat the bearing
 assemblies between differential case 18 and carrier 10. The adjusting ring
 44 may then be rotated so as to be tightened against the anti-friction
 bearing assembly 24 on the ring gear 16 side of the differential case
 assembly 18, until there is no backlash between the pinion gear 14 and
 ring gear 16. The opposite adjusting ring 44 will then be tightened
 against the opposite differential case bearing assembly until the required
 backlash between pinion gear 14 and ring gear 16 is achieved. The bearing
 caps 28 may then be tightened to the required torque to maintain the
 centered position of differential case assembly 18 relative to
 differential carrier 10. After proper positioning and centering of the
 differential case assembly, the bearing caps 28 are fully torqued and the
 locking bolt 49 is installed into the carrier 10 through the appropriate
 aperture 47 of the adjusting ring 44. At this point, adjustment of the
 bearing preload and backlash is effected, and end play between the
 differential case assembly 18 and differential carrier 10 is eliminated.
 Proper meshing of the pinion gear 14 with ring gear 16 will allow maximum
 transmission of rotary motive power to the drive axles and wheels of the
 vehicle.
 An advantage of the differential unit construction including the adjustable
 bearing assemblies is found in the ability to adjust the preload on the
 bearing assemblies without removal of the differential case assembly 18.
 For example, if backlash increases due to wear of the pinion gear 14 or
 ring gear 16, the preloading force on the differential case bearings is
 also reduced and requires adjustment for proper functioning of the
 differential. To accomplish such adjustment, the locking bolt or pin 49 is
 removed and the axle shafts 30 are withdrawn to an intermediate position
 causing engagement of the axle shaft splines 31 with the internal splines
 46 of the adjusting ring 44. By rotating the axle shaft 30, the adjusting
 ring 44 opposite the ring gear 16 may then be loosened slightly by
 rotating the adjustment ring 44 through the threaded engagement with the
 carrier 10. The adjusting ring 44 on the ring gear 16 side of the
 differential case assembly 18 may then be tightened against the bearing
 assembly 24 of the differential case assembly. Such adjustment is
 continued until there is no backlash between the pinion gear 14 and ring
 gear 16 similar to initial assembly of the differential case assembly 18
 with the differential carrier 10. The opposed adjusting ring 44 associated
 with bearing assembly 26 may then be tightened against the bearing
 assembly until the required backlash between pinion gear 14 and ring gear
 16 is achieved. The bearing caps 28 may then be tightened to the required
 torque and the locking pin 49 replaced in their interengaging position
 with an aperture 47 of the adjusting rings 44.
 From the foregoing description, it should be apparent that the invention
 permits rapid, convenient and accurate mounting of the differential case
 assembly of a vehicle differential unit in the proper axial position
 relative to the differential housing so as to eliminate end play of the
 differential case assembly and impart the desired bearing preload in the
 differential unit. In this way, proper intermeshing engagement of the ring
 gear carried by the differential case assembly with the power input pinion
 gear may be effected while introducing the desired amount of backlash
 between these gears. The construction of the invention allows adjustment
 of the bearing preload and backlash without removal of the differential
 case assembly, so as to greatly simplify initial as well as subsequent
 adjustments of the bearing assemblies.
 Although only one preferred embodiment has been shown and described herein,
 various modifications or alternative embodiments not specifically
 mentioned herein are contemplated and would be recognized by those skilled
 in the art. Therefore, the invention is only to be limited by the scope of
 the invention as defined in the appended claims.