Abstract:
This invention is directed to a wheel end assembly for engaging and disengaging the wheel end of a vehicle that is convertible between four-wheel and two-wheel drive. The invention is further directed to clutch ring engagement at the inboard end of a wheel hub whereat a retention feature retains the support bearings for the wheel hub on the vehicle suspension and whereat, independent of the retention feature, the clutch ring is operable directly between the wheel hub and axle.

Description:
FIELD OF THE INVENTION 
     This invention relates to the conversion of a vehicle wheel from passive to driven drive as when converting a vehicle between two-wheel and four-wheel, and more particularly it relates to the manner of providing selective clutch ring engagement as between a vehicle&#39;s axle and a wheel hub for achieving the conversion. 
     BACKGROUND OF THE INVENTION 
     A common arrangement for a two-wheel/four-wheel drive vehicle is with the two rear wheels in permanent drive and the front wheels convertible as between passive where the drive train is disconnected from the front wheels (the front wheels passively roll on a roadway as the vehicle is driven by the rear wheels), and driven where the front propellor shaft and front axles are connected to the front wheels so as to be driven by the vehicle engine. 
     To achieve the conversion it has been common to extend the front wheel axles into and through the wheel hubs to the outboard side of the wheel whereat a clutch ring is axially moved between engagement with one of the axle and wheel hub and, alternatively, engagement with both. A more recent improvement to the conversion process is the reconfiguration of the wheel hub to provide a mounting for the wheel hub to the vehicle frame or suspension that exposes a hub portion inboard of the wheel and adjacent an axle portion, e.g., at the CV joint. A clutch ring and actuator at this inboard end provide the desired engagement/disengagement of the wheel hub and drive axle. See the commonly owned U.S. Pat. No. 5,740,895. 
     A further consideration to the mounting arrangement is the bearings that provide rotation as between the vehicle frame (suspension) and the wheel hub. These bearings are placed under axial compression and locked to prevent undesired operating clearances. This axial compression and locking is desirably provided at the internal end, i.e., whereat the clutch ring engagement is provided. Prior designs for achieving both have involved the provision of a coupler that is rotatably fixed to the inboard end of the wheel hub adjacent the support bearings, and in cooperation with the coupler, a lock mechanism providing both axial compression and locked engagement of the coupler against the bearing. The coupler includes external splines adjacent and matched to splines on the axle which are selectively engaged by a clutch ring to thereby engage and disengage the axle from the wheel hub. 
     BRIEF DESCRIPTION OF THE INVENTION 
     It is an objective of the present invention to separate the features of clutch ring engagement and bearing compression while simplifying the manner of clutch ring actuation. 
     In a preferred embodiment, the wheel bearings are mounted to the outer diameter of an inwardly extended portion of the wheel hub (sometimes referred to as the spindle portion of the wheel hub) and the inboard end of the spindle portion is turned or roll formed directly against the inner race of the bearings to apply both the desired compression and lock the bearings in the compressed condition. 
     The wheel hub is cylindrical and the inner diameter of the spindle portion, intermediate the ends, is fitted with bearings that provide rotatable support for the axle. The inner diameter at the extreme inboard end of the spindle portion is configured to have a spaced apart relation with the axle and the spaced apart interfaces of the spindle portion and axle are provided with splines. A clutch ring resides in the spacing and is axially slidable (via an actuator) relative to the splines to produce the desired engagement and disengagement as between the spindle portion of the wheel hub and axle. It is to be noted that the bearing retention is provided at the exterior wall of the cylindrical spindle portion and the clutch ring engagement is independently provided at the interior wall. 
     The invention will be more fully appreciated upon reference to the following detailed description having reference to the accompanying drawings. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 schematically illustrates a vehicle chassis convertible between two-wheel and four-wheel drive; 
     FIG. 2 is a section view of a wheel end illustrating a preferred embodiment of the present invention wherein the clutch ring is shown in the position of engagement; 
     FIG. 3 is a view of that portion of FIG. 2 illustrating the components of engagement but showing the clutch ring in the position of disengagement; and 
     FIG. 4 illustrates the engagement components in exploded view. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to FIG. 1, illustrated is a chassis including an engine  10  connected to a transmission  12 , connected to a rear propellor shaft  14  connected to a rear differential  16  connected to rear axles  18  which drive rear wheels  20 . 
     Also connected to the transmission  12  is a transfer case  22  connected to a front propellor shaft  24  connected to a front differential  26  for driving front axles  28  and front wheels  30 . A control represented by dash line box  32  is connected to the transfer case  22  for engaging/disengaging the front propellor shaft from the transfer case and thus the engine  10 . 
     It will be understood that with the front propellor shaft connected to the transmission via control  32 , the front wheels are driven by the engine for four-wheel drive. When the propellor shaft  24  and only the propellor shaft is disconnected from the transmission  12 , the wheels  30  are nevertheless driven through engagement with the road surface. The axles  28 , differential  26  and propellor shaft  24  are then driven by the rotation of the wheels  30 . This unnecessary wear of the drive components and loss of power consumption is preferably avoided by providing a secondary disconnect at the wheel hub of the wheels  30 . The wheel hub of the right front wheel hub is illustrated in FIG. 2 as indicated by view lines  2 — 2  in FIG.  1 . 
     Reference is now made to FIG.  2 . In FIG. 2, item  34  is a section of the wheel rim by which the wheel  30  (not shown in FIG. 2) is mounted, i.e., bolted (bolts or studs  36 ) to the wheel hub  38 . As shown, the wheel hub  38  is provided with a cylindrical inboard segment  40  sometimes referred to as a spindle portion or spindle. The spindle is mounted to a vehicle knuckle  42  via a bearing pack  44  including an inner race  46 . The inner race is abutted at its outboard end against a shoulder  48  of the wheel hub and the extreme inboard end  50  of the spindle portion  40  is roll formed and controllably pressed against the inboard end of inner race  46  to provide the desired compressive retention of the bearing pack  44 . 
     An axle portion  52  extended from CV joint  54  extends into the wheel hub  38  to be supported therein by bearings  56 ,  58 . The configuration of axle  52  and the spindle portion  40  at the inward end thereof provides a cylindrical space represented by arrows  60 . Fitted into the space  60  is a clutch ring  62  including an inboard flange  64  protruded from the spindle end  40 . 
     A pneumatic actuator  66  is mounted to the knuckle  42  and controlled via air line  68  to expand and contract an annular chamber  70  for axial movement of fork  72 . Fork  72  and actuator  66  are rotatably fixed via its mounting to the knuckle  42 . The fork  72  is configured so as to engage flange  64  of clutch ring  62  for axial movement of the flange but providing a bearing relationship for relative rotation (in a manner well known to the art) to permit rotation of the clutch ring  62  with axle  52  and spindle  40 . As will be explained, the axial movement of the clutch ring provides the desired engagement/disengagement as between the wheel hub  38  (and thus the wheel  30 ), with the CV joint  54  (and thus axle  28 ). 
     As noted in FIG. 4 (but also referring to FIG.  2 ), the clutch ring  62  is provided with an inner diameter having splines  74  that are continuous, and an outer diameter having splines  76  that are axially spaced spline segments. Axle  52  is provided with splines  78  that mesh with splines  74  of clutch ring  62  to provide permanent engagement rotatively but permitting axial sliding movement. The spindle portion  40  is provided with spaced spline segments  80  that are matched to the spline segments  76  of the clutch ring  62 . In the axial position of the clutch ring shown in FIG. 2, the spline segments  76  (of clutch ring  62 ) and spline segments  80  (of spindle portion  40 ) are in overlapping relation and force common rotation as between the clutch ring and spindle. Because splines  74  of the clutch ring and splines  78  of the axle are permanently engaged rotatively, the axle and wheel portion are engaged rotatively. 
     In FIG. 3, the clutch ring has been axially shifted whereat the splines  76  of the clutch ring are positioned axially in between the spline segments  80  of the spindle portion  40  to thereby permit relative rotation as between the clutch ring and spindle and thus permit relative rotation as between the wheel hub and axle. 
     In operation, the annular air chamber  70  of the actuator  66  is expanded or contracted through an air pressure differential directed through line  68 , e.g., a negative differential from the intake manifold. An annular actuator of the type herein contemplated is illustrated in the afore mentioned U.S. Pat. No. 5,740,895 and in greater detail in commonly owned application for patent Ser. No. 09/310,887. With expansion of the air chamber  70  (urged by spring  82 ) as indicated in FIG. 2, the fork  72  is moved outboard and similarly moves clutch ring  62  outboard to achieve meshing of spline segments  76 ,  80 . With contraction of the air chamber  70  (via negative pressure differential), the spring  82  is compressed and the fork  72  is moved inboard and moves clutch ring  62  inboard to intersperse the spline segments  76 ,  80  as illustrated in FIG.  3 . 
     It will be appreciated that the compression of the inner race  46  is achieved directly by the out turned (roll formed) end  50  of the spindle. Such compression can be achieved by other means, however, e.g., a nut and nut lock device. It will also be appreciated that a coupler is not required as is typical in prior devices and instead the clutch ring acts directly between the spindle and the axle at the inner diameter of the spindle. Fewer parts and a more compact package of the actuator and clutch ring Is achieved. The package is sealed against contaminants by the seats  86  and  88  as shown in FIG.  2 . Numerous variations will be suggested to those skilled in the art without departing from the invention. The invention is to be determined from the appended claims and specifically 35 USC §112 ¶6 is not intended for any of the claims.