Abstract:
The present invention provides an axle assembly for a motor vehicle including an axle housing, a differential assembly supported in the axle housing with a differential bearing, a bearing insert, an adjuster sleeve and a lock ring. The bearing insert is coupled to the axle housing. The adjuster sleeve is rotatably coupled to the bearing insert in a pre-installed position. The adjuster sleeve is adapted to engage the differential bearing and impart a preload force thereon. The lock ring is disposed between the bearing insert and the adjuster sleeve in an installed position. The lock ring precludes relative movement between the bearing insert and the adjuster sleeve thereby maintaining a desired preload on the differential bearing.

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to differentials for use in automotive drivelines and, more particularly, to an arrangement and method for setting a differential bearing preload. 
   BACKGROUND OF THE INVENTION 
   Some automotive drive axles include a differential assembly including a gear set which is supported within a differential housing to facilitate relative rotation between a pair of output shafts. The gear set typically includes a pair of helical side gears that are splined to the ends of axle shafts. The helical side gears are meshed with paired sets of helical pinions generally supported on a cross pin coupled to the differential housing. In response to speed differentiation between the output shafts, 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 differential housing to frictionally limit the speed differentiation and proportionally deliver torque between the output shafts. 
   In addition, many automotive drive axles include a hypoid gear set for changing the direction of power transmission from an axis parallel to the direction of vehicle travel to an axis perpendicular thereto. The hypoid gear set includes a ring gear coupled to the differential housing and a pinion gear journally supported within the axle housing. To facilitate proper function of the drive axle assembly, the differential is mounted on a pair of slidable differential bearings. 
   In one arrangement, a sleeve and insert assembly is pressed into the axle housing outboard of the differential bearing. The sleeve typically includes castle extensions formed on an outer face for engagement with an adjustment tool. The sleeve is rotatably driven relative to the insert with the adjustment tool and toward the differential bearing. The differential bearing preload and hypoid gear backlash are then measured. The sleeve may be adjusted accordingly to achieve a desired measurement. Once the desired preload and backlash are set, a clip is positioned in engagement with adjacent castles on the sleeve to lock the sleeve relative to the axle housing and, consequently, maintain the desired bearing preload and backlash. The clip is typically held in a cast pocket in the axle housing by grease prior to deflection. Once deflected, the clip is retained on a first end by adjacent castles on the sleeve and retained on an opposite end between the axle housing pocket and insert. 
   While the aforementioned arrangement has been useful in retaining the differential bearings at the desired location, the assembly process is complicated and time consuming due to the alignment of the clip relative to adjacent castle extensions. Furthermore, the step of deflecting the clip can be difficult and may require an installer to back-off or further tighten the adjuster sleeve to align respective castles on the adjuster sleeve for receipt of the clip. In the event that the adjuster sleeve needs to be backed-off or tightened, the bearing preload or hypoid gear backlash may consequently be moved to a less desirable measurement. Therefore, a need exists to provide an improved arrangement for setting bearing preload and gear set backlash. 
   SUMMARY OF THE INVENTION 
   The present invention provides an axle assembly for a motor vehicle including an axle housing, a differential assembly supported in the axle housing with a differential bearing, a bearing insert and a lock ring. The bearing insert is coupled to the axle housing. An adjuster sleeve is rotatably coupled to the bearing insert in a pre-installed position. The adjuster sleeve is adapted to engage the differential bearing and impart a preload force thereon. The lock ring is press-fit between the bearing insert and the adjuster sleeve in an installed position. The lock ring precludes relative movement between the bearing insert and the adjuster sleeve thereby maintaining a desired preload on the differential bearing. 
   According to other features, an outer diameter of the bearing insert forms a press-fit between an inner diameter defined by an opening in the axle housing. The adjuster sleeve includes a plurality of slots defined around a raised wall extending radially around an outboard surface for accepting teeth of an adjustment tool during installation. The bearing insert includes inner serrations defined around an inner diameter. The adjuster sleeve includes outer serrations defined around an outer diameter. The lock ring engages the inner and outer serrations in an installed position. 
   Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 

   
     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 an exemplary axle assembly equipped with the bearing adjuster lock assembly of the present invention; 
       FIG. 2  is a perspective view of the axle assembly of  FIG. 1  shown with the axle housing removed for illustrative purposes; 
       FIG. 3  is an exploded perspective view of the adjuster lock assembly of the present invention; 
       FIG. 4  is a sectional view taken along line  4 — 4  of  FIG. 1  shown with the adjuster sleeve and insert of the adjuster lock assembly press-fit into the axle housing prior to setting bearing preload and gear set backlash; 
       FIG. 5  is a sectional view of the adjuster sleeve and insert of  FIG. 4  shown with an installation tool rotatably advancing the sleeve into the bearing assembly to set a preload on the bearing and gear set backlash; 
       FIG. 6  is a sectional view of the adjuster lock assembly shown in a locked position; 
       FIG. 7  is a plan view of the lock ring of the adjuster lock assembly of the present invention; 
       FIG. 8  is a plan view of a lock ring according to a second configuration of the present invention; and 
       FIG. 9  is a plan view of a lock ring according to a third configuration of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
   With initial reference to  FIGS. 1 and 2 , a differential bearing adjuster lock assembly constructed in accordance with the teachings of an embodiment of the present invention is generally identified at reference numeral  10 . The adjuster lock assembly  10  is shown operatively associated with an exemplary drive axle assembly  12 . 
   As particularly shown in  FIGS. 1 and 2 , the drive axle assembly  12  is illustrated to generally include an axle housing  14  for rotatably mounting a hypoid gear set including a pinion gear  16  and a ring gear  18  drivingly interconnected to a differential assembly  20 . The differential assembly  20  functions to transfer power to a pair of axle shafts (not shown) while compensating for any difference in axle shaft speed rotation as may occur during a turn or other steering maneuver. In order to compensate for a differential in axle shaft rotational speed, the differential assembly  20  includes a pair of pinion gears  22  and a pair of side gears  24  drivingly interconnected to the axle shafts. To facilitate proper function of the axle assembly  12 , the differential assembly  20  is rotatably mounted on a pair of differential bearings  28 . The bearings are contained in machined cylindrical bores. Each carrier half includes one bore. 
   With continued reference to  FIGS. 1 and 2 , and further reference to  FIGS. 3–6 , the adjuster lock assembly  10  will be further described. The adjuster lock assembly  10  is provided to assure optimum differential bearing preload and proper pinion gear to ring gear engagement. The adjuster lock assembly  10  generally includes a bearing adjuster insert  32 , a bearing adjuster sleeve  34  and a bearing adjuster lock ring  36 . The bearing adjuster insert  32  forms a press-fit with an opening  40  defined in the axle housing  14  and remains fixed relative to housing  14  ( FIG. 4 ). The bearing adjuster sleeve  34  has threads  44  formed on an outer diameter that interface with threads  46  formed on an inner diameter of the bearing adjuster insert  32  ( FIG. 3 ). As will be described in greater detail, rotation of the sleeve  34  relative to the insert  32  forces the differential bearing  28  laterally. As a result, bearing preload and hypoid gear set backlash may be set. Once the desired bearing preload and backlash are set, the bearing adjuster lock ring  36  is press-fit into an annular receiving pocket  48  (as best illustrated in  FIG. 4 ) defined between the insert  32  and the sleeve  34  to lock the angular position of the sleeve  34  relative to the insert  32 . 
   With particular reference now to  FIGS. 3 and 4 , the insert  32  will be described in greater detail. The insert  32  defines an outer diameter having a first portion  50  and a stepped second portion  52 . The first portion  50  includes a plurality of serrations  56  formed thereon for facilitating a press-fit with the opening  40  ( FIG. 4 ) in the axle housing  14 . The stepped second portion  52  cooperatively seats on a land  60  formed on the axle housing  14 . As explained, once the insert  32  is press-fit into the axle housing  14 , it is precluded from rotating. The insert  32  further defines a serrated portion  64  on the inner diameter adjacent to the threaded portion  46 . The threaded portion  46  cooperates with the threads  44  on the sleeve  34  and allows the sleeve  34  to advance therealong. The serrated portion  64  on the inner diameter of the insert  32  provides a mating surface for receiving an outer diameter of the lock ring  36 . 
   With reference now to  FIGS. 3–6 , the sleeve  34  will be described in greater detail. As described, the sleeve  34  functions to force the differential bearing  28  laterally and set a desired differential bearing preload and hypoid gear set backlash. The sleeve  34  generally includes a main body portion  70  and a flange portion  72 . The main body portion  70  includes the threads  44  formed thereon. An inboard face  74  ( FIG. 4 ) of the flange portion  72  is adapted to engage an outboard face  76  of the differential bearing  28 . The main body portion  70  includes a raised wall  80  defining a series of slots  82  ( FIG. 3 ). The slots  82  are formed entirely through the raised wall  80  and terminate into portions of the main body portion  70 . The slots  82  are adapted to accept fingers  84  of an installation tool  88  ( FIG. 5 ). The installation tool  88  is used to impart rotational movement onto the sleeve  34  causing the sleeve  34  to move laterally relative to the insert  32  along the respective threaded portions  44  and  46 . 
   A series of raised wall portions  90  collectively form the raised wall  80  and are defined between the respective slots  82 . The raised wall portions  90  each define a radial length L 1  that is greater than a radial length L 2  defined by the slots  82  ( FIG. 3 ). As a result, the raised wall portions  90  provide a robust structure to impart rotational force during bearing preload and gear set backlash adjustments. In the exemplary sleeve  34 , the radial length of the raised wall portions  90  and the slots  82  define a ratio of about 3:1. It is appreciated that other ratios may be similarly employed. 
   The sleeve  34  defines an outer diameter having a serrated portion  92  collectively formed on the raised wall portions  90 . The serrated portion  92  provides a mating surface for receiving an inner diameter of the lock ring  36 . A ledge  96  is defined at a transition between the main body portion  70  and the raised wall  80  and provides a lateral seat for the lock ring  36  in an installed position. It is noted that the slots  82  extend into the main body portion  70  a distance beyond the ledge  96  ( FIGS. 3 and 4 ). As a result, access between an installed lock ring and a terminal surface  98  of a slot  82  may be gained to forceably remove a lock ring  36  from engagement between the sleeve  34  and the insert  32 . 
   Referring now to  FIGS. 3–7  the lock ring  36  will be further described. The lock ring  36  may comprise a stamped metal material or alternatively comprise molded powdered metal. The material is preferably softer than that of the insert and sleeve and may be aluminum. As explained, the lock ring  36  is operable to be press-fit between the outer diameter of the sleeve  34  (at the serrated portions  92 ) and the inner diameter of the insert  32  (at the serrated portion  64 ) as shown in  FIG. 6 . The insert  32  and the sleeve  34  are comprised of materials harder than that of the lock ring  36 . In one example, the insert  32  and the sleeve  34  are comprised of powdered metal. The lock ring  36  includes deformable gripping surfaces on an inner diameter  104  and an outer diameter  106  for the respective serrations  64  and  92  of the insert  32  and the sleeve  34  in an installed position. As a result, the respective serrations  64  and  92  of the insert  32  and the sleeve  34 , respectively, bite into the lock ring  36  to further enhance a locked condition ( FIG. 6 ). Alternatively, lock ring  36  may be press-fit into smooth bores formed on an insert and a sleeve in lieu of serrations  64  and  92 . Once the lock ring is press-fit between the insert  32  and the sleeve  34 , the sleeve  34  is precluded from rotation by the mechanical interlock described. Consequently, build variation in gear lash and differential bearing preload is reduced, due to no required sleeve rotational alignment. 
   With particular reference to  FIG. 7 , a series of extension portions  110  are shown formed around the inner and outer diameters  104  and  106  of the lock ring  36 . A complementary series of relief portions  112  are formed opposite the extension portions  110 . During installation of the lock ring  36 , the extension portions  110  partially deflect toward the relief portions  112 . The alternating extension portion  110  and relief portion  112  configuration facilitates secure engagement of the lock ring  36  to the insert  32  and the sleeve  34 . The alternating extension/relief configuration accommodates for manufacturing variation in component size and alignment. 
   The lock ring  36  presents a repeatable pattern on its inner and outer diameter  104  and  106 , respectively. In this way, the lock ring  36  may be arbitrarily advanced into the annular receiving pocket  48 . Installation of the lock ring  36  does not require any alignment, additional fasteners or secondary movement relative to the sleeve  34  or insert  32 . As a result, once the sleeve  34  is advanced to a position such that the desired bearing preload and gearset backlash are set, the lock ring  36  may be immediately installed. 
   Turning now to  FIGS. 8 and 9 , lock rings  136  and  236  according to additional configurations are shown. Lock ring  136  includes a series of teeth  140  arranged around an inner diameter  144 . The teeth are configured to be accepted in the complimentary slots  82  of the sleeve  34  in an installed position. An outer diameter  146  includes a series of extension portions  150  and relief portions  152  arranged thereon. While the inner diameter  144  is shown as having a substantially uniform radius between adjacent teeth  140 , the inner diameter may alternatively include extension and relief portions as described in relation to lock ring  36 . The lock ring  136  is adapted to be press-fit into the annular smooth bore embodiment of the pocket  48  defined by the insert  32  and the sleeve  34 . 
   Lock ring  236  includes an outer ring member  240 , an inner ring member  244  and an intermediate portion  246 . The inner and outer rings  240  and  244  may be comprised of similar materials as described in relation to lock ring  36 . The intermediate portion  246  is securably attached between the outer and inner ring members  240  and  244 . The intermediate portion  246  is comprised of a compliant material such as rubber for example. The lock ring  236  is adapted to be press-fit into the annular pocket  48  defined by the insert  32  and the sleeve  34 . The compliant properties of the intermediate portion  246  encourage the outer ring member  240  to be biased outwardly into the smooth bore  64  of the insert  32  and the inner ring member  244  to be biased inwardly into the smooth bore  92  of the sleeve  34 . In another configuration, the inner and outer ring members  240  and  244  may define a unitary piece without the intermediate portion  246 . 
   While the invention has been described in the specification and illustrated in the drawings with reference to various embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined in the claims. Furthermore, the mixing and matching of features, elements and/or functions between various embodiments is expressly contemplated herein so that one of ordinary skill in the art would appreciate from this disclosure that features, elements and/or functions of one embodiment may be incorporated into another embodiment as appropriate, unless described otherwise above. Moreover, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this invention, but that the invention will include any embodiments falling within the foregoing description and the appended claims.