Abstract:
A vacuum locking hub system is provided for a four-wheel drive vehicle that includes a cartridge-type assembly that allows the vacuum locking hub system to be inserted into the wheel as a cartridge unit for ease of assembly. The vacuum locking hub system has a compact construction allowing it to be substantially received within the wheel hub, thus reducing system mass and unit length.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a locking hub system for a vehicle, and more particularly to a vacuum actuated locking hub cartridge with reduced assembly length and improved assembly, installation and sealing capabilities. 
   BACKGROUND AND SUMMARY OF THE INVENTION 
   Vehicles having four-wheel drive capabilities that are designed for on-road and off-road use typically provide optional engagement/disengagement of two of the four wheels. The wheels to be disengaged are necessarily provided with a driveline from the vehicle powertrain wherein for on-road use and to avoid unnecessary energy consumption and wearing of the out-of-service driveline components, hub locks are provided for disconnecting the axles from the wheels of the vehicle. The original hub lock devices were manually actuated. A driver/operator would stop the vehicle, engage the transfer case disconnect system and then manually turn a dial located in each wheel hub to activate the hub lock to disconnect the wheels from the axles. 
   Subsequently, mechanisms have been developed to automatically activate the hub locks. Automatic locking hubs for four-wheel drive vehicles are now available in many different design configurations. Such configurations include direct manual clutch engagement, remote vacuum clutch engagement, and remote pressure clutch engagement. The systems of the previous designs include complex designs requiring numerous parts involved that render the device expensive to produce and/or are complex to assemble. The present invention requires fewer parts for more efficient production, a more compact package of components for easier assembly to the vehicle, and reduced unsprung mass. 
   The vacuum locking hub assembly of the present invention includes a body member having an annular base portion secured to an inner drive gear. The inner drive gear includes internal splines in engagement with the external splines of the axle shaft and a plurality of exterior clutch teeth. A clutch ring surrounds the inner drive gear and includes internal clutch teeth with the clutch ring being slidable relative to the inner drive gear for moving the internal clutch teeth into and out of engagement with the exterior clutch teeth of the inner drive gear. A piston is received in the body member and is disposed against the clutch ring for causing driving movement of the clutch ring. A diaphragm is attached to the body member by a retainer and acts against the piston for driving the piston. The inner drive gear, clutch ring, piston, and diaphragm are all held together by the body member as a cartridge unit. 
   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 cross-sectional view of a vacuum actuated hub clutch mechanism applied to a spindle according to the principles of the present invention; 
       FIG. 2  is an exploded sectional view illustrating the assembly of the vacuum actuated hub clutch mechanism according to the principles of the present invention; 
       FIG. 3  is a detailed cross-sectional view of the vacuum actuated hub clutch mechanism according to the principles of the present invention; and 
       FIG. 4  is a detailed cross-sectional view of the seal arrangement for the vacuum actuated hub clutch mechanism according to the principles 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 reference to  FIG. 1 , a wheel hub assembly  10  is shown including a vacuum locking hub system  12  that couples a wheel  14  to the axle shaft  16 . The wheel  14  is fixedly mounted to a wheel hub  18  which is rotatably supported on the axle shaft  16 . It will be understood that the axle  16  and wheel hub  18  can be coupled or uncoupled to one another by the vacuum locking hub system  12 . 
   The wheel hub  18  is supported by a knuckle  20 . A bearing assembly  22  is disposed between knuckle  20  and wheel hub  18 . Wheel hub  18  includes an inboard end portion  24  which receives either a bearing adjusting nut  26  (as shown in  FIG. 1 ) which is disposed against the bearing assembly  22  or a roll form retention system (as shown in  FIG. 2 ). The bearing assembly  22  includes an outer race portion  28  having an outwardly extending flange portion  28 A that is fastened to the knuckle  20  by fasteners  30 . 
   The wheel hub  18  includes a radially extending flange portion  32  to which a brake rotor  34  and wheel  14  are fastened by fasteners  36 . The wheel hub  18  includes a bore  38  extending therethrough for receiving the axle shaft  16  therein. The bore  38  includes an outboard portion  40  having internal splines  42 . A bearing assembly  44  is provided on an inboard end  46  of the bore  38  between the axle shaft  16  and wheel hub  18 . The bore  38  includes a shoulder portion  48  and the axle shaft  16  includes a recessed groove  50  which receives an axle retaining ring  52  which abuts against the shoulder  48  of the bore  38  for retaining the axle shaft  16  in the bore  38 . The axle shaft  16  includes external splines  54  on an outboard end thereof. 
   The vacuum locking hub system  12  is provided as a cartridge unit that is inserted in the outboard end  40  of bore  38 . The vacuum locking hub system  12 , as best illustrated in  FIG. 3 , includes a body member  60  which holds the vacuum locking hub system  12  together as a cartridge unit. The body member  60  includes an annular base portion  62  which is secured to an inner drive gear  64  by a rear retaining ring  66  and an outboard washer  68 . The inner drive gear  64  includes internal splines  70  which engage the external splines  54  on the outboard end of axle shaft  16 . The inner drive gear  64  further includes two sets of axially spaced exterior clutch teeth  72 ,  74 . A clutch ring  76  is disposed around the inner drive gear  64  and includes two sets of interior axially spaced clutch teeth  78 ,  80 . The axially spaced interior clutch teeth  78 ,  80  of clutch ring  76  are engagable with the exterior axially spaced clutch teeth  72 ,  74  on the inner drive gear  64 . The clutch ring  76  includes exterior splines  82  which are engaged with the interior splines  42  provided in the outboard end  40  of the bore  38  of wheel hub  18 . 
   A piston  84  is axially movable inside body member  60  and is disposed directly against the clutch ring  76 . A diaphragm  86  is supported by the body member  60  and disposed against the piston  84 . The diaphragm  86  is secured to a radially outwardly extending flange portion  88  of the body member  60 , by a metal retainer  90  that pinches an outer flange of the diaphragm  86  against the flange portion  88  of body member  60 . An O-ring seal  92  is provided around the retaining ring  90  for providing a seal between the outer flange  88  of body member  60  and the bore  38  of wheel hub  18 , as best shown in  FIG. 4 . A cap  96  is mounted to an end face  98  of the wheel hub  18  by threaded fasteners  100  which are received in holes  102  provided in the cap  96  and threaded bores  104  provided in the end face  98  of the wheel hub  18 . The cap  96  includes a shoulder portion  106  (best shown in  FIG. 2 ) which presses against the flange portion  88  of body member  60  for securing the vacuum locking hub system  12  within the bore  38  of wheel hub  18 . A vent  97  is preferably provided in the cap  96  to prevent negative pressure build up between the diaphragm assembly  86  and the cap  96 . 
   In operation, a vacuum passage  110  is provided in the knuckle  20  for communicating a vacuum between the axle shaft  16  and wheel hub  18  to the vacuum locking hub system  12  to cause the diaphragm  86  to move axially inward, thus causing the piston  84  to move inward for pushing clutch ring  76  such that internal clutch teeth sets  78 ,  80  engage with external clutch teeth sets  72 ,  74  of inner drive gear  64  for providing a driving connection between the spindle  16  and wheel hub  18 . A spring  112  is supported by the body  60  and biases clutch ring  76  to a disengaged position when the vacuum is discontinued. 
   The body  60  holds all of the components of the vacuum locking hub system  12  together as a cartridge to be installed as a unit into the wheel hubs  18 . An assembler slides the vacuum locking hub cartridge  12  into the wheel end bore  38  by aligning the internal splines  70  of inner drive gear  64  with external splines  54  of axle shaft  16 . Then, the assembler aligns the external splines  82  of the clutch ring  76  with the internal splines  42  of wheel hub  18 . The cap  96  is then placed on the wheel hub  18  and mounting screws  100  are installed. The O-ring seal  92  is trapped between the vacuum locking hub cartridge  12  and the bore  38  of the wheel hub  18 . The O-ring seal  92  holds the vacuum and prevents contamination from entering the wheel end. A seal  120  is provided between the knuckle  20  and axle shaft  60  ( FIG. 1 ) while additional seals  122 ,  124  on opposite ends of the bearing assembly  22  further prohibit escape of vacuum pressure from the vacuum chamber. 
   With the vacuum locking hub cartridge  12 , according to the present invention, the cartridge  12  is very easily assembled on the wheel end. In addition, the compact construction of the vacuum locking hub cartridge  12  allows it to be substantially received within the bore  38  of the locking hub  18  thereby reducing the size and weight of the locking hub system. 
   The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.