Patent Abstract:
A differential having pinion bearings supported on the input yoke is provided. The differential includes a housing having an opening through which a pinion shaft extends. The input yoke is disposed about a portion of the pinion shaft and one or both pinion bearing sets are then disposed about the input yoke. This configuration reduces pinion standout and allows for installation of a pre-assembled bearing pack (i.e., without spacers or shims), but does not reduce the length of the splines on the input yoke or bearing capacity.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to vehicle differentials and, in particular, to the location and support of pinion bearings within a differential. 
     2. Disclosure of Related Art 
     Differentials are used in vehicles to allow wheels mounted on either side of a vehicle axle to rotate at different speeds. A conventional differential includes a series of gears disposed within a differential housing that transmit torque from a power input shaft to axle half shafts supporting the wheels. One of these gears is a pinion gear. The differential housing defines an opening through which a pinion shaft extends to support the pinion gear. Bearings are disposed within the opening to allow the pinion shaft to rotate relative to the housing. An input yoke is coupled to the pinion shaft and to the power input shaft to transmit torque from the power input shaft to the pinion shaft. 
     Conventional differentials have several problems. First, the pinion shaft and input yoke extend outwardly from the differential housing for a relatively large distance (“pinion standout”). As a result, the differential requires additional space and the mounting of vehicle suspension components and other vehicle components is made for difficult. Second, installation and proper placement of the pinion bearings often require the use of spacers or shims during assembly thereby increasing assembly time. 
     There is thus a need for a differential for a vehicle that will minimize or eliminate one or more of the above-mentioned deficiencies. 
     SUMMARY OF THE INVENTION 
     The present invention provides a differential for a vehicle. 
     A differential in accordance with the present invention includes a differential housing that defines a first opening. The differential also includes a pinion shaft disposed within the first opening and configured for rotation about an axis extending through the first opening. The differential further includes an input yoke disposed about a least a portion of the pinion shaft. Finally, the differential includes a first bearing set disposed about the input yoke. The differential may also include a second bearing set axially spaced from the first bearing set and also disposed about the input yoke. 
     A differential in accordance with the present invention has several advantages as compared to conventional vehicle differentials. The location of the bearing set(s) on the input yoke shortens the overall length of the pinion shaft while still allowing sufficient engagement between the pinion shaft and input yoke. As a result, pinion standout is reduced. The location of the bearing sets further allows the use of a preassembled bearing pack comprised of the bearing sets and a carrier for the bearing sets for proper positioning of the bearing sets within the differential housing opening. As a result, spacers and/or shims are not required and differential assembly time may be significantly reduced. 
     These and other features and objects of this invention will become apparent to one skilled in the art from the following detailed description and the accompanying drawings illustrating features of this invention by way of example. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view of a differential in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings wherein like reference numerals are used to identify identical components in the various views, FIG. 1 illustrates a differential  10  in accordance with the present invention. Differential  10  is provided to allow wheels (not shown) disposed on either side of the vehicle, and supported on axle half shafts (not shown) extending from differential  10 , to rotate at different speeds. Differential  10  is particularly adapted for use in a heavy truck. It should be understood, however, that the present invention is not limited to use in heavy trucks and may be used in a wide variety of vehicles. Differential  10  may include a housing  12 , a differential gear assembly  14 , a pinion shaft  16 , an input yoke  18 , a carrier  20 , and bearing sets  22 ,  24 . 
     Housing  12  provides structural support for the other components of differential  10 . Housing  12  also protects the other components of differential  10  from foreign objects and elements. Housing  12  may be made from conventional metals and metal alloys such as steel and may include multiple members  26 ,  28 ,  30  that are sized relative to components of differential  10  and coupled together using conventional fasteners (not shown). Member  26  of housing may define an opening  34  at a forward end. Opening  34  may be centered about an axis  36  extending through pinion shaft  16 . 
     Differential gear assembly  14  is provided to allow the wheels supported on either side of the vehicle to rotate at different speeds. Assembly  14  may include a pinion gear  38 , a ring gear  40 , and a conventional bevel gear set (not shown) disposed within a differential carrier (not shown). 
     Pinion gear  38  is provided to transfer torque from pinion shaft  16  to ring gear  40 . Pinion gear  38  may be made from conventional metals and metal alloys and may comprise a hypoid gear. Gear  38  rotates about axis  36 . Gear  38  is disposed about shaft  165  and may be integral therewith or mounted thereto using a conventional spline connection or in other ways customary in the art. Gear  38  may also include a pilot portion  42  extending rearwardly that is supported for rotation by bearings  44  disposed in a pilot web  46  of housing member  26 . 
     Ring gear  40  is provided to transfer torque from pinion gear  38  to the bevel gear set and is conventional in the art. Ring gear  40  may also be made from conventional metals and metal alloys and may also comprise a hypoid gear. Gear  40  is affixed to the carrier or may be integral therewith. 
     The bevel gear set (not shown) is provided to transfer torque from ring gear  40  to the axle half shafts supporting the vehicle wheels. The bevel gear set is conventional in the art. 
     Pinion shaft  16  is provided to transmit power from a power input shaft (not shown) to pinion gear  38  and is conventional in the art. Pinion shaft  16  may include a first portion  48  having a first diameter, a second portion  50  having a second diameter greater than the first diameter and a tapered portion  52  joining portions  48 ,  50 . Pinion shaft  16  may include a plurality of splines  54  extending axially along portion  48  from a forward end of shaft  16  to tapered portion  52 . Pinion shaft  16  may also include a threaded shank  56  extending from a forward end of shaft  16  and integral therewith. 
     Input yoke  18  is provided to transmit power from a power input shaft (not shown) to pinion shaft  16 . Yoke  18  may be coupled to the power input shaft through a conventional universal joint (not shown) and is configured for rotation about axis  36 . Yoke  18  includes a generally cylindrical body  58  with a circular flange  60  radiating outwardly from body  58  at a forward end of body  58 . Body  58  defines a bore  62  sized to receive pinion shaft  16  and extends axially along shaft  16  to the rearward end of shaft  16  such that one axial end of yoke  18  is proximate pinion gear  38 . Yoke  18  may include a plurality of splines  64  configured for engagement with splines  54  of pinion shaft  16 . In accordance with the present invention, splines  64  may be disposed radially inwardly of bearing set  22 . Yoke  18  may be retained on shaft  16  by a nut  66  and a washer (not shown) disposed about stud  56  of shaft  16 . 
     Carrier  20  is provided to position and support bearing sets  22 ,  24  within opening  34  of housing  12  and may be made from conventional metals or metal alloys. Carrier  20  is generally cylindrical in shape and is sized to be received within opening  34  of housing  12 . Carrier  20  includes a radially outwardly extending flange  68  at a forward end that abuts a shoulder  70  formed in housing  12  upon installation of carrier  20  within opening  34 . Carrier  20  may be held within opening  34  by a cap  72  that is fastened to member  26  of housing  12  using conventional fasteners (not shown). Carrier  20  is disposed about axis  36  and defines a bore  74  configured to receive bearing sets  22 ,  24 . A radially inwardly extending flange  76  within bore  74  defines a pair of shoulders  78 ,  80  and helps enable proper positioning of bearing sets  22 ,  24  without the need for spacers or shims. 
     Bearings sets  22 ,  24  are provided to allow rotation of input yoke  18  and pinion shaft  16  relative to carrier  20  and housing  12 . Bearing sets  22 ,  24  are conventional in the art and may comprise tapered roller bearings. Each bearing set  22 ,  24  includes a cone  82 ,  84 , respectively, defining an inner bearing race and a cup  86 ,  88 , respectively, defining an outer bearing race. Cone  82  of bearing set  22  is in engagement with a shoulder  90  defined in input yoke  18  and cup  86  of bearing set  22  is in engagement with shoulder  78  of carrier  20 . Cone  84  of bearing set  24  is in engagement with pinion gear  38  while cup  88  of bearing set  24  is in engagement with shoulder  80  of carrier  20 . In accordance with the present invention, bearing sets  22 ,  24  are disposed about input yoke  18  between yoke  18  and carrier  20 . In particular, cones  82 ,  84  are supported on body  58  of yoke  18 . The relative location of bearing sets  22 ,  24  and input yoke  18  result in a significant improvement as compared to conventional differentials. In particular, yoke  18  is moved forward in differential  10  thereby enabling a reduction in pinion standout, but still allowing yoke  18  to maintain proper engagement with pinion shaft  16  because the lengths of splines  54 ,  64  are not reduced. Further, bearing capacity remains the same in the inventive differential. 
     While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it is well understood by those skilled in the art that various changes and modifications can be made in the invention without departing from the spirit and scope of the invention.

Technology Classification (CPC): 5