Abstract:
A vehicle differential which includes an integral positive displacement pump, along with adjustable fluid controls and a movable surface for holding fluid controls in position, infinitely from full open to full closed, where as relative rotation of differential half-axles and side gears would cause positive displacement pump to force fluid past fluid controls and position of fluid controls would restrict the fluid flow thus effectively limiting the “slip” of the differential.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of PPA
         Ser. No. 60/470, 930 filed May 15, 2003   Ser. No. 60/492, 487 filed Aug. 4, 2003       

   FEDERALLY SPONSORED RESEARCH 
   not applicable 
   SEQUENCE LISTING OR PROGRAM 
   not applicable 
   BACKGROUND OF THE INVENTION 
   This invention relates to any wheel driven vehicle or mobile equipment, more specifically to an improved method of controlling the differential or differentials of a vehicle. 
   To date limited-slip differentials, although having the benefits of increasing overall tractive effort of a vehicle in many conditions, primarily when one wheel contacts a surface with a lower coefficient of friction, also have some draw backs. 
   In the case of a standard limited-slip differential, when turning on dry pavement, while traction is not a concern, the friction that must be overcome between the clutch discs or the road surface and one or more of the vehicle wheels, causes strain and wear on drive-train components along with causing greater energy consumption required to overcome the friction. 
   In the case of a variable differential lock which uses the friction discs to create friction, the amount of locking force is not consistent due to the torque difference required to initially break the bond of the friction discs and the amount of torque required to maintain the slippage not to mention the associated wear to the friction discs. 
   The type of differential lock which uses the combination of friction discs that are compressed by the pumping action of an integral differential pump tend to give a “jerky” sensation when a wheel begins to spin and then locks. Other prior art using an integral pump with a fluid control device does not provide for any make-up or cooling fluid to automatically reenter the loop which makes them impractical. 
   All of these short comings of the prior art are overcome with closed-loop hydraulic adjustable slip differential. Component wear is minimized not eliminated, no high pressure rotating seals are used, the amount of “slip” can be tailored for conditions by operator or maximized when vehicle traction is not a concern there by requiring minimal power when turning. 
   FIELD OF INVENTION 
   This invention relates to an improved differential controlling device which has applications in but not restricted to passenger vehicles, construction and mining equipment and military vehicles. 
   OBJECTS AND ADVANTAGES 
   Accordingly several objects and advantages of my invention are the elimination of “wear” parts within a limited slip differential also giving the operator the ability to adjust the amount of differential “slip” from a maximum to some minimum while traveling at any speed while giving a smooth fluid feel as the locking action occurs within. Unseen internal workings of the differential further provide a method for flushing hot fluid from the mechanism while replenishing with cooling fluid. 
   SUMMARY 
   This invention is basically a limited slip differential, more specifically it is totally hydraulic actuated by use of an internal positive displacement pump which generates a quantity of fluid flow in proportion to the displacement of the pumping mechanism and the difference of rotation speed between the two half-axles. One or more fluid channels in the housing which contains positive displacement pump, direct fluid from the outlet back to the inlet of internal pump. 
   One or more adjustable fluid controls which are also contained within inner housing, will restrict the flow from the outlet of pump by some degree relative to the position maintained by vehicle operator of the internal control surface. 
   The pressure of the fluid generated by the internal pump and fluid control will be the force that to some degree attempts to lock differential axles together. 

   
     DRAWINGS 
     FIG. one is a view from the right hand side of the preferred embodiment of the internal positive displacement pump along with fluid controls, fluid channels and valves. 
     FIG. two is an elevation view in section of the entire apparatus. 
   

   REFERENCE NUMERALS 
   
       
       
         
             1 ) tapered control ring 
             3 ) tapered roller 
             4 ) sun gear 
             5 ) driven gear 
             7 ) regulating check valve 
             8 ) make-up fluid check valve 
             13 ) adjustable fluid control 
             15 ) ring gear 
             16 ) differential inner case 
             17 ) outer pump housing 
             18 ) annular cavity 
             19 ) left hand side gear 
             20 ) pinion gear 
             21 ) right hand side gear 
             22 ) annular manifold 
             23 ) spring 
             24 ) orifice 
         
       
     
  
   DETAILED DESCRIPTION 
   Preferred Embodiment 
   Illustrated in  FIGS. 1 and 2  are sectional views of the preferred embodiment of the closed loop hydraulic, adjustable-slip differential where, ring gear  15  is fixed to differential inner case  16 , also fixed to  15  and  16  is the outer housing of positive displacement gear pump  17 . Left hand half-axle of vehicle is splined to sun gear  4  along with one side gear  19  ( FIG. 2 ) of differential. Rotation of ring gear  15  would cause rotation of, differential case  16 , applying rotational torque to differential side gears  19  and  21  ( FIG. 2 ) by means of differential pinion gears  20  ( FIG. 2 ). With half axles in place, rotation would be transmitted from side gears  20  ( FIG. 2 ) to half-axles and also to sun gear  4 . In the event that one half-axle would rotate, relative to the other half-axle, rotation of sun gear  4  and driven gears  5  would take place, causing a pumping action within pump housing  17 . The moving fluid would be pushed past fluid controls  13 , causing a differential pressure whereby the magnitude of the pressure would be dependent upon the quantity of flow and the amount of restricting of such flow. 
   The restriction of the flow would be controlled by the position of fluid control  13 , position of fluid control  13  would be determined by position of control ring  1  (FIG.  1 / FIG. 2 ) relative to roller  3  which is attached to body of fluid controls  13 . The control ring  1 , would be positioned and held by hydraulic pressure, where the control ring  1  would have a portion of its body without taper, some portion of which would be inserted and sealed in cavity  18  within outer housing, the hydraulic fluid within the cavity would be supplied from a master cylinder and the quantity would be predetermined by a programmed circuit controlling a stepper motor which in turn would rotate a lead screw driving a piston into the master cylinder, this would allow for predetermined steps for the amount of “slip” desired. 
   Some flushing of the closed hydraulic loop would be desirable, primarily to allow cool fluid in and hot fluid out, this would be achieved by orifice  24 , which would be exposed to the higher pressure fluid within the loop. Fluid leaving the loop would have to be replaced within the loop, this would be accomplished by means of manifold  22  ( FIG. 2 ), held from rotating and sealed to a portion of pump housing  17 , where the cavity within manifold  22  would be simultaneously exposed to sump fluid at the lower portion of manifold,  22  along with porting leading to make up fluid check valves  8 . 
   OPERATION OF INVENTION 
     FIGS. 1 and 2  are cutaway views of the preferred embodiment of the apparatus where ring gear  15  is fixed to differential inner case  16  which contains within pinion gears  20  and side gears  19  and  21 . Right hand half axle is fixed to side gear  21  and left hand half axle is fixed to side gear  19  and sun gear  4 . Outer housing of pump  17  is fixed to differential inner case  16  or manufactured as an integral part thereof. Detail  22  is the annular manifold which is sealed to pump outer housing  17 , where the manifold would be fixed from rotating while allowing housing  17  to rotate within. Detail  18  would be the annular cavity which would be held within or manufactured as a part of differential outer housing where tapered control ring  1  is sealed to annular cavity  18 , but allowed to move into or out of cavity dependent upon the amount of fluid held within cavity  18 . Tapered roller  3 , able to rotate on its axis while being attached to adjustable fluid control  13 , shall rotate with fluid control  13 , pump housing  17 , differential inner case  16  and ring gear  15  while contacting a portion of the inside diameter of tapered control ring  1 . The position of tapered control ring  1  shall determine the position of adjustable fluid control  13  which in turn determines the area of the restriction in the fluid passage way. 
   In an example of the typical operation of the apparatus, ring gear  15  would rotate clockwise (looking from end of right hand half axle) causing housing  16  to rotate along with pinion gears  20 . Gears  20 , being meshed with differential side gears  19  and  21  would also rotate causing right hand and left hand axle to rotate in the same direction as ring gear  15 . When right hand axle requires less torque to rotate, pinion gears  20  will begin to spin on their axis which will allow left hand half axle to slow. As left hand half axle slows also does sun gear  4 , as seen in  FIG. 1 , sun gear  4  is rotating clockwise but at a slower rate than ring gear  15 , and housings  16  and  17 . This causes driven gears  5  ( FIG. 1 ) to spin on their axis&#39;s. With the spaces between gear teeth containing fluid, this fluid will be forced out of the spaces as driven gear teeth mesh with sun gear teeth. The displaced fluid would then be forced through passage which is metered by position of adjustable fluid control  13  where the amount of pressure drop across fluid controls  13  and displacement of gear set  4  and  5  would determine the amount of torque compelling the half axles to rotate at the same rate. As pressure builds across gear set and within internal passage, fluid will begin to pass through upper right and lower left regulating check valves  7  as viewed from  FIG. 1 . The exit side of check valves  7  is directed by channel to a surface of fluid controls  13  whereby pressure axis this surface will urge the metering portion of fluid controls  13  to move outward thereby compressing spring  23  to a point of equilibrium between fluid pressure and spring pressure. The area of the pressure sensing surface of fluid controls  13  is of predetermined quantity to react with the predetermined pressure/coefficient of spring  23 . Along with a predetermined amount of travel of communicating member of fluid controls  13 , pressure/coefficient of spring  23  and surface area of fluid control  13 , a sensitivity and torque range are established to act upon the slip of the differential. Orifice  24  being of predetermined area allows a quantity of pressurized hot fluid to leave the internal loop through the body of fluid controls  13 , this action not only lubricates fluid controls  13  and tapered roller  3  but also flushes heat from the circulating loop. As fluid leaves the loop, either through orifice  24  or through machining clearances, this will cause voids or low pressure within the gear set  4  and  5 . This void or low pressure will then draw replenishing fluid up through the submerged portion of annular manifold  22  ( FIG. 2 ) then on through passages within housing  17  then finally through one or more check valves  8  and back into the gear set. 
   CONCLUSION, RAMIFICATIONS AND SCOPE OF INVENTION 
   Many of the internal workings of the invention may be accomplished by other similar means, for instance, the pumping mechanism may be a gerotor or piston type pump, and also one or more driven gears could be used depending on the required torque. The restricted passages for allowing fluid to leave the loop could be somewhere other than in the fluid controls or there could be none except that some machining tolerances could be large enough to allow sufficient fluid to escape. The adjustable fluid controls could be constructed as floating flow controls. The make-up fluid could be supplied through the annular manifold by a separate pump. Another possible way of positioning the tapered control ring could be external threads on control ring which would mate with internal threads within the carrier housing where rotation of tapered control ring would cause the ring  1  to move toward or away from tapered roller  3 . The ring gear  15  could be a sprocket, pulley or some other drive mechanism, thus the scope of the invention should be determined by the appended claims and their legal equivalents rather than by the examples given.