Abstract:
A valve member includes an axially movable spool valve rotatably mounted in the valve member to cause the way that fluid is communicated between the inlet and outlet ports of the device and the volume chambers thereof. An outer surface of the spool has a configuration to react to fluid pressure to effect the timing between the gear set and the valving of valve member and that the timing therebetween will be adjusted when the spool valve is moved axially. A valve actuator comprising a spring loaded plunger controlled by fluid pressure at the inlet and outlet ports is in physical contact with one end of the valve spool.

Description:
BACKGROUND OF THE INVENTION 
     Spool valving “lags” take place in the volume chambers of a gerotor gear set. By way of example only, as one of the volume chambers becomes a maximum volume transition chamber, the spool valving will continue for one or two more degrees of rotation to communicate high pressure fluid into that volume chamber, the volume of which is not changing. The instantaneous result will be that the volume chamber has begun to shrink while still communicating with high pressure. Then the valving shuts off and the chamber shrinks further, and because of overlap in the valving, with no way to relieve pressure in the chamber, the fluid pressure will rise rapidly creating a pressure pulse or spike in that volume chamber. Such incorrect timing will result in a number of problems in the gerotor, each of which will have a further detrimental effect on volumetric efficiency and motor smoothness. 
     Therefore, the principal object of this invention is to provide a spool valve that is axially movable to cause the way that the oil is communicated between the inlet and outlet of the motor and the volume chambers of the motor to deal with a solution to the problems of valve timing through adjustability of the timing. 
     This and other objects will be apparent to those skilled in the art. 
     SUMMARY OF THE INVENTION 
     The motor of this invention has a small valve transmission shaft between gear set and spool valve, and a port plate between gear set and valve housing. The purpose of the port plate is partly to reduce the tilting angle of the valve transmission shaft, and partly to seal between the volume chambers of the gear set and the bore in the valve housing. The latter of the two occurs, because the bore in the port plate is smaller than the bore in the valve housing. 
     In the valve housing, a spool valve with a shorter length than the length of the bore is arranged. The spool valve is rotated together with the gear set, due to the valve transmission shaft, but is free to move axially. A support rod will keep the valve transmission shaft in position, and a spring acting upon the support rod will force the valve towards the push rod of the valve actuator. 
     The inlet and outlet ports are in connection with individual ring chambers on the spool valve, independently of the axial position of the valve. Through axial connections in the spool valve, oil is communicated from the ring chambers to oil passages in the valve housing, leading to each of the volume chambers. By rotating the spool valve, together with the gear set, oil is communicated between an inlet and an outlet of the motor and the volume chambers of the motor. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a longitudinal sectional view of a motor embodying this invention; 
     FIG. 2 is a sectional view taken on line  2 — 2  of FIG. 1; 
     FIG. 3 is a sectional view taken on line  3 — 3  of FIG. 1; 
     FIG. 4 is a perspective view of a spool valve of this invention; and 
     FIG. 5 is a perspective view of an alternate form of a spool valve of this invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to FIG. 1, a gerotor motor  10  of the spool valve type has an end plate  12  having a well opening  14  which terminates into a center opening  16 . A gear set  18  is mounted within gear assembly  20  which has a center opening  22  communicating with the opening  16  in end plate  12 . 
     A port plate  24  is located immediately adjacent the gear set assembly  20  and has a center opening  26 . 
     A valve housing  28  is located immediately adjacent the port plate  24  and has a center bore  30  which registers with the center opening  26  in port plate  24 . Valve housing  28  has two ports A and B designated by the numerals  32  and  34 , respectively, which extend from the exterior of the housing  28  and communicate with the interior of center bore  30 . 
     A spool valve  36  is slidably longitudinally mounted within bore  30  and has annular ring chambers  38  and  40  which communicate with ports  32  and  34  respectively. An end bore  42  is located on the inner end of spool valve  36 . 
     A valve transmission shaft  44  has its outer end connected to the inner end of dog bone shaft  46  which is spline connected to gear set  18  at the inner end of shaft  46 . The valve transmission shaft  44  extends through the center opening  26  of port plate  24 . The inner end of valve transmission shaft  44  is slidably mounted within the end bore  42  of spool valve  36 . 
     Spool valve  36  has a bore segment  48  communicating with end bore  42 . Bore segment  48  terminates in bore segment  50  of a smaller diameter. The numeral  52  designates a piston support for shaft  44  which is slidably mounted within bore segments  48  and  50  and has an inner end that penetrates into the end bore  42 . A piston support head  54  terminates into an elongated stem  56  with the head  54  being slidably mounted within bore segment  48  and with stem  56  being slidably mounted within bore segment  50 . A compression spring  57  is located in bore segment  48  and has an inner end bearing against piston support head  54 , with the other end bearing against the outer end of bore segment  48 . As previously indicated, the stem  565  is slidably mounted around the bore segment  50  and protrudes outwardly from the end of spool valve  36  to engage the inner surface  58  of end cover  60 . 
     A valve actuator  62  is mounted on the end cover  60  and has a valve actuator housing  64 . Opposite flexible cups  66  and  68  are mounted within the outer end of housing  64  and are connected to the outer end of plunger  72 . Spring  70  surrounds the cup  66  and  68  and causes the plunger  72  to normally be in the neutral position shown in FIG. 1 wherein neither of the cups  66  or  68  are in a state of compression or extension. The inner end of plunger  72  engages the outer end  74  of spool valve  36 . The numeral  76  designates the inner end of plunger  72 . 
     Plunger  72  has a center portion  72 A which has its opposite surfaces connected to ports A and B ( 32  and  34  respectively) via ports A 1  and B 1  in valve housing  64 . 
     A plurality of elongated bolts  78  pass through registering holes in members  12 ,  20 ,  24  and  28  and are threadably secured by threaded apertures in end plate  12 . 
     Fluid passages  80 ,  82  and  84  are in registering relation in members  20 ,  24  and  28 . 
     FIG. 2 is a sectional view taken on line  2 — 2  of FIG.  1  and shows the port plate  24 , the center opening  26  therein and the shaft  44 . 
     FIG. 3 is a sectional view taken on line  3 — 3  of FIG.  1  and shows the gear set  18  with star member  86  having a center aperture  88 ; a ring member  90  and conventional rollers. The numeral  92  designates a valve chamber characteristic of gerotor motors. 
     The motor of this invention has a small valve transmission shaft between gear set and spool valve, and a port plate between gear set and valve housing. The purpose of the port plate is partly to reduce the tilting angle of the valve transmission shaft, and partly to seal between the volume chambers of the gear set and the bore in the valve housing. The latter of the two occurs, because the bore in the port plate is smaller than the bore in the valve housing. 
     In the valve housing, a spool valve with a shorter length than the length of the bore is arranged. The spool valve is rotated together with the gear set, due to the valve transmission shaft, but is free to move axially. A support rod will keep the valve transmission shaft in position, and a spring acting upon the support rod will force the valve towards the push rod of the valve actuator. 
     The inlet and outlet ports are in connection with individual ring chambers on the spool valve, independently of the axial position of the valve. Through axial connections in the spool valve, oil is communicated from the ring chambers to oil passages in the valve housing, leading to each of the volume chambers. By rotating the spool valve, together with the gear set, oil is communicated between inlet and outlet of the motor and the volume chambers of the motor. 
     In FIG. 4 a spool valve  36  is shown, which has pure axial connections. Some of them ( 94 ) are “fixed” and are running from one ring chamber  96  and close to the other. Others are running from each ring chamber and close to each other. In one axial position, where the oil passages in the valve housing fits with the center of the spool valve, a given oil passage in the valve housing will connect alternately to A and B ports of the motor. Moving the spool valve  24  axially will change this alternation, and a given oil passage will then connect to the A port three times and then to the B port, or to the B port three times and then to the A port. This gives the same result as that of U.S. Pat. No. 6,033,195, but without a separate valve and with only one connection between valve and each volume chamber. 
     With the spool valve  24  of FIG. 4 placed in the motor of FIG. 1, controlling the valve actuator  62  will control the displacement of the motor. The actuator  62  shown in FIG. 1 will in a no-load position move at the center position. Adding a control fluid to port A will force the actuator to the right, and the left cup-shaped element  66  will follow the valve actuator  62 . The spring  70  is thereby tensioned, and when the control fluid is relived from port A, the actuator is moved to the center position by the spring  70 . 
     An alternate spool valve geometry is shown by the valve  100  in FIG. 5, where the axial connections  102  are cone-shaped. This will have the effect that the timing between gear set  18  and valving will be adjusted when the spool valve  100  is moved axially. The problems described in U.S. Pat. No. 6,126,424 can thus be avoided, as the timing is adjustable. The function only depends on the geometry of the spool valve, in the axial direction. Once again, the invention is the moveable spool valve.