Patent Abstract:
A differential assembly includes a differential housing defining a chamber and a pair of aligned openings communicating with the chamber. A pair of output shafts extend through the openings in the differential housing and include end segments located within the chamber. A pair of side gears are positioned within the chamber and fixed to the end segments of the output shaft. Paired sets of pinions are rotatably mounted within the differential housing and placed in meshed engagement with each other and with one of the side gears. A retention assembly interconnects the end segments and includes a spacer having a web positioned between and walls partially encompassing the end segments. The retention assembly includes a ring surrounding the spacer to selectively retain and allow removal of clips engaged with the end segments.

Full Description:
FIELD OF THE INVENTION 
   The present invention relates to differentials for use in automotive drivelines and, more particularly, to an axle shaft retention assembly for a helical gear differential. 
   BACKGROUND OF THE INVENTION 
   Differentials of the type used in automotive drivelines generally include a planetary gearset supported within a differential housing to facilitate relative rotation (i.e., speed differentiation) between a pair of output shafts. In helical gear differentials, the gearset typically includes helical side gears fixed to the end of the output shafts that are meshed with paired sets of helical pinions journalled in gear pockets formed in the differential housing. Since the gear pockets are parallel to the rotary axis of the differential housing, the pinions rotate on axes that are parallel to the common axis of the output shafts and the side gears. In response to speed differentiation between the output shafts, the torque transmitted through meshed engagement of the side gears and pinions generates thrust forces that are exerted by the gear components against the wall surface of the gear pockets and other thrust surfaces within the differential housing to frictionally limit such speed differentiation and proportion torque between the output shafts. 
   One problem associated with some conventional helical gear differentials is axial separation of the output shafts within the differential housing relative to the side gears. A related problem involves maintaining a proper spacial relationship between the ends of the output shafts. Most typically, C-clip retainers mounted in grooves are utilized for retaining the ends of the output shafts in relation to the side gears. In addition, it is also known to install spacers (i.e., pins, blocks, thrust plates, etc.) in the differential housing between the terminal ends of the output shafts. Due to limited access to the gearset, however, such spacers may be difficult to install within the differential housing. Examples of known spacer and clip arrangements in helical differentials are shown in U.S. Pat. Nos. 4,495,835, 4,512,221, 5,221,238, 5,554,081, 5,671,640 and 5,984,823. 
   SUMMARY OF THE INVENTION 
   Thus, it is an object of the present invention to provide a retention assembly for use in a helical differential which is superior to conventional C-clip retention and spacing devices in terms of function and simplified assembly. 
   The present invention is directed to a differential comprising a housing defining a chamber and a pair of aligned apertures. A pair of output shafts having end segments extending through the aligned apertures in the housing are positioned in the chamber. A gearset is operable to transfer rotary power from the housing to the output shafts while permitting speed differentiation between the output shafts. The gearset is retained in the chamber and includes a pair of side gears drivingly engaged with the end segments of the output shafts. A retention assembly is positioned within the chamber and is operable to maintain the axial position of the end segments of the output shafts. The retention assembly includes a ring having windows, a spacer having recesses and a fastener, the recesses being in receipt of the end segments, the spacer being rotatable within the ring to align the recesses with the windows to allow a pair of clips to pass therethrough and into engagement with the end segments. The fastener is operable to interconnect the ring and the spacer when the recesses are out of alignment with the windows thereby capturing the pair of clips within the recesses of the spacer. 

   
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood however that the detailed description and specific examples, while indicating a preferred embodiment of the invention, is intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
       FIG. 1  is a perspective view of a differential assembly equipped with the retention assembly of the present invention; 
       FIG. 2  is an end view of the differential assembly shown in  FIG. 1 ; 
       FIG. 3  is a sectional view taken generally along line  3 - 3  of  FIG. 2  with the axle shafts removed; 
       FIG. 4  is a sectional view taken generally along line  4 - 4  of  FIG. 2 ; 
       FIG. 5  is an exploded perspective view of the retention assembly of the present invention; 
       FIG. 6  is a perspective view of the retention assembly at a first assembly stage; 
       FIG. 7  is a perspective view of the retention assembly at a second assembly stage; and 
       FIG. 8  a perspective view of the retention assembly at a final assembly stage. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   With reference to  FIGS. 1-8 , a shaft retention mechanism for use with a differential assembly  10  will be described. Differential assembly  10  will be described in sufficient detail to describe the structure and function of the shaft retention mechanism. In particular, differential assembly  10  is of the helical parallel-axis type used in motor vehicle driveline applications. However, it is to be understood that the shaft retention mechanism of the present invention is applicable for use with many variants of differential assembly  10  and, as such, the particular structure shown is intended merely to be exemplary in nature. 
   Differential assembly  10  includes a housing assembly  12  which defines an internal chamber  14 . Housing assembly  12  includes a main drum  16  and an end cap  18  which is secured to a radial flange  20  of drum  16  by a plurality of bolts (not shown) installed through aligned mounting bores  22 . As is known, a ring or bevel gear can be fixed to radial flange  20  on housing assembly  12  to transfer rotary power (i.e., drive torque) thereto. Housing assembly  12  defines a pair of axially aligned openings  24  and  26  in communication with chamber  14  and which are adapted to receive and rotatably support the end segments of a pair of output shafts, hereinafter referred to as axle shafts  28   a  and  28   b . The end segment of axle shafts  28   a ,  28   b  includes a corresponding recessed annular groove  30   a ,  30   b  which separates a button-like end pad  32   a ,  32   b  from an externally-splined segment  34   a ,  34   b . End pads  32   a ,  32   b  have a corresponding circular peripheral surface  36   a ,  36   b , an outer face surface  38   a ,  38   b , and an inner face surface  40   a ,  40   b . The outer diameter of end pads  32   a ,  32   b  is shown to be slightly smaller than the outer diameter of splined segment  34   a ,  34   b  on shafts  28   a ,  28   b . As will be detailed, a retention assembly  42  is installed between end pads  32   a ,  32   b  to maintain the axial spacing between shafts  28   a  and  28   b  and prevent axial separation thereof. 
   Differential assembly  10  includes a planetary gearset which is operable for transferring drive torque from housing assembly  12  to axle shafts  28   a ,  28   b  in a manner facilitating speed differential therebetween. The helical gearset is mounted in chamber  14  and includes a pair of side gears  44   a ,  44   b  having internal splines  46   a ,  46   b  meshed with externally splined segments  34   a ,  34   b  on a corresponding one of the axle shafts  28   a ,  28   b . In addition, side gears  44   a ,  44   b  include axial hubs  45   a ,  45   b  which are retained in corresponding annular sockets  47   a ,  47   b  formed in drum  16  and end cap  18  of housing assembly  12 . C-shaped retainers, or C-clips  48   a ,  48   b , are retained in aligned grooves  30   a ,  30   b  for restraining the axle shafts from moving outboard. 
   The helical gearset also includes a series of first pinions  50  journally supported in pockets  52  formed in raised hub segments  54  of drum  16 , and a series of second pinions  56  journally supported in pockets  58  also formed in hub segments  54  of drum  16 . Pockets  52  and  58  are formed in paired sets such that they communicate with each other and with chamber  14 . In addition, pockets  52  and  58  are aligned to be substantially parallel to the rotational axis of shafts  28   a ,  28   b . When assembled, first pinions  50  mesh with side gear  44   a  while second pinions  56  mesh with side gear  44   b . Additionally, the paired sets are arranged such that one of first pinions  50  also meshes with one of second pinions  56 . Windows  60  are formed in drum  16  between hub segments  54  and are provided for permitting access to the gearset within chamber  14 . 
   In accordance with the present invention, retention assembly  42  is provided for maintaining side gears  44   a ,  44   b  and axle shafts  28   a ,  28   b  in axially spaced relation relative to each other while preventing unintentional release of C-clips  48   a ,  48   b  from grooves  30   a ,  30   b . Retention assembly  42  includes a ring  62 , a spacer  64 , C-clips  48   a ,  48   b  and a fastener  66 . As best shown in  FIG. 5 , ring  62  is substantially cylindrically shaped having an inner cylindrical surface  68  and an outer cylindrical surface  70  extending from a first end face  72  to a second end face  74 . Outer cylindrical surface  70  is interrupted by a plurality of scallops  76 . Scallops  76  function to prevent ring  62  from rotating within housing assembly  12 . An elongated slot  78  radially extends through ring  62  to provide an access aperture for fastener  66  as will be described in greater detail hereinafter. A counterbore  80  is formed in one portion of outer cylindrical surface  70  in communication with elongated slot  78  to provide a seat for a washer  82  used in conjunction with fastener  66 . A pair of windows  84   a  and  84   b  are formed within ring  62  to provide access for C-clips  48   a  and  48   b . Window  84   a  extends from inner cylindrical surface  68  to outer cylindrical surface  70  for an arc length long enough to clear the height of C-clip  48   a . Window  84   b  is similarly sized, shaped and positioned as a feature removed from second end face  74 . 
   Spacer  64  is a substantially cylindrical member having an outer surface  86  extending from a first end face  88  to a second end face  90 . Spacer  64  includes first and second recesses  92   a  and  92   b  sized and shaped for receipt of the end segments of axle shafts  28   a ,  28   b  as well as C-clips  48   a ,  48   b . Recess  92   a  is substantially “C” shaped having a substantially planar first land  94   a  spaced apart from a substantially planar second land  96   a . An arc-shaped portion  98   a  interconnects first land  94   a  and second land  96   a . Recess  92   b  is similarly sized and shaped to include a first land  94   b  and a second land  96   b  interconnected by an arc-shaped portion  98   b  (not shown). A web  100  separates recess  92   a  and recess  92   b . Web  100  includes a substantially planar first surface  102  positioned substantially parallel to and spaced apart from a second substantially planar surface  104 . A plurality of apertures  106  radially inwardly extend into spacer  64  from outer surface  86 . Apertures  106  are circumferentially spaced apart from one another and positioned along a plane midway between first end face  88  and second end face  90 . Apertures  106  provide an installer of retention assembly  42  a method to rotate spacer  64  while spacer  64  is positioned within ring  62 . A pin or other lever arm (not shown) is inserted through elongated slot  78  of ring  62  and into one of apertures  106  to apply a torque to spacer  64  and rotate the spacer relative to ring  62 . Spacer  64  includes a threaded aperture  108  radially inwardly extending from outer surface  86  along an axis aligned with recesses  92   a  and  92   b . Threaded aperture  108  enters from the side of spacer  64  where the open ends of recesses  92   a ,  92   b  are not present. 
     FIGS. 6-8  depict the order of operations performed to retain axle shafts  28   a  and  28   b  to the differential assembly  10  using retention assembly  42 . It should be appreciated that ring  62  and spacer  64  are axially installed within chamber  14  during an initial build phase of differential assembly  10 . The differential assembly  10  is then rotatably mounted within a transaxle or rear axle carrier. Ring  62  and spacer  64  remain captive within chamber  14  and are not removed from the differential assembly while the differential assembly is captured within a carrier housing (not shown). 
   To retain axle shafts  28   a  and  28   b  to differential assembly  10 , each axle shaft is inserted within its respective housing assembly opening  24 ,  26  and into chamber  14 . Axle shafts  28   a  and  28   b  are translated until outer face surfaces  38   a  and  38   b  contact first surface  102  and second surface  104  of web  100 . At this time, recesses  92   a  and  92   b  of spacer  64  must be aligned with windows  84   a  and  84   b  of ring  62 . If this condition does not presently exist, the installer inserts a rod through elongated slot  78  into one of apertures  106  formed within spacer  64  to rotate spacer  64  and align recesses  92   a ,  92   b  with windows  84   a ,  84   b . Once the recesses and windows have been aligned, C-clip  48   a  is translated through window  84   a  and recess  92   a  into groove  30   a  of axle shaft  28   a . Similarly, C-clip  48   b  is translated through window  84   b  and into recess  92   b  while entering groove  30   b  of axle shaft  28   b . At this time, axle shafts  28   a  and  28   b  are restrained from movement along their rotational axes by web  100  and the end faces of side gears  44   a ,  44   b.    
   To maintain the proper position of C-clips  48   a  and  48   b , spacer  64  is rotated approximately 180 degrees to capture the C-clips within ring  62 . As previously described, spacer  64  may be rotated relative to ring  62  through use of a pin and apertures  106 . Once spacer  64  is properly positioned relative to ring  62 , threaded aperture  108  will be aligned with elongated slot  78  and counterbore  80 . At this time, the user threadably engages fastener  66  with threaded aperture  108  to restrict spacer  64  from rotating relative to ring  62 . The assembly process may be reversed to allow removal of axle shafts  28   a ,  28   b  from differential assembly  10 . 
   Furthermore, the foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations may be made therein without department from the spirit and scope of the invention as defined in the following claims.

Technology Classification (CPC): 5