Abstract:
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.

Description:
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. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and further objects and advantages of the invention will become apparent upon the further reading of the detailed description of the preferred embodiment of the invention, taken in conjunction with drawings, wherein: 
     FIG. 1 is a partial cross-sectional view of a differential unit including the adjustable bearing assemblies of the invention; 
     FIG. 2 is an enlarged partial cross-sectional view of one of the bearing assemblies in the differential units; 
     FIG. 3 shows a plan view of an adjusting ring to perform adjustment and locking of bearing preload and backlash characteristics in the differential unit; and 
     FIG. 4 shows a cross-sectional view taken along the line  4 — 4  of FIG.  3 . 
    
    
     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.