Abstract:
A gerotor motor has a housing located adjacent a port plate. The housing has two fluid chambers on opposite sides of a disc valve. The disc valve is in sealing surface engagement with the port plate to prevent fluid from moving between the fluid chambers. The valve assembly has forward and rearward sides and has substantially equal volumes of material removed therefrom so as to balance the port plate against any torsional forces imposed on the valve assembly which might otherwise deflect the valve assembly to interfere with its sealing relationship with the port plate.

Description:
BACKGROUND OF THE INVENTION 
     The disc valve element in a gerotor motor of the disc valve type is pressed against a port plate element. The surface between the disc valve and the port valve forms a sealing surface, so that fluid from high-pressure chambers in the gear set cannot get in touch with fluid from the low-pressure chambers. On the rear of the disc valve is arranged a sealing element, and the surface between the disc valve and the sealing element also forms a sealing surface, so that the high and low pressure chambers do not fluidly connect with each other. The sealing is partly secured by a spring element acting upon the sealing element in the direction of the gear set, partly by accurately adapted areas acted upon by the fluid pressure from high-pressure and low-pressure. 
     Experience and simulation results show that the disc valve element is slightly deformed when the motor is loaded and the pressure increases. Part of the deformation takes place because of torsional forces around the axis of the valve causing the two sealing surfaces to deform and to fail to maintain their intimate contact. This causes a leakage from the high-pressure chamber to the low-pressure chamber. This leakage contributes to a deterioration of the motor efficiency and is therefore not desirable. The torsional forces around the axis of the valve are avoided when the surface mass of the valve material on the front of the valve (where the commutation slots are located) is equal and symmetrical to the mass of material on the rear of the valve. 
     It is therefore a principal object of this invention to provide a means for optimizing the disc valve in a gerotor motor. 
     A further object of the invention is to provide means in a gerotor motor for equalizing torsional forces within a disc valve of the motor to reduce or eliminate distortion and deformation of sealing surfaces in the valves, to overcome fluid leakage. 
     A still further object of this invention is to impose blind slots in the rear side of the valve of a gerotor motor to balance the torsional forces within the valve to reduce distortion of the sealing surfaces and to decrease the fluid loss caused by such distortion. 
     These and other objects will be apparent to those skilled in the art. 
     SUMMARY OF THE INVENTION 
     A gerotor motor has a housing located adjacent a port plate. The housing has two fluid chambers on opposite sides of a disc valve. The disc valve is in sealing surface engagement with the port plate to prevent fluid from moving between the fluid chambers. The valve assembly has forward and rearward sides and has substantially equal volumes of material removed therefrom so as to balance the disc valve against any torsional forces imposed on the valve assembly which might otherwise deflect the valve assembly to interfere with its sealing relationship with the port plate. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a longitudinal sectional view of the gerotor motor of this invention; 
     FIG. 2 is an elevational view of the front end of the disc valve; 
     FIG. 3 is a rear elevational view of the disc valve; 
     FIG. 3A is an enlarged scale sectional view taken on line  3 A— 3 A of FIG. 3; 
     FIG. 4 is a top elevational view of the disc valve; 
     FIG. 5 is a sectional view taken on line  5 — 5  of FIG. 2; and 
     FIG. 6 is a forward perspective view of the disc valve showing the front end thereof. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a gerotor motor  10  with a housing  12  having a center bore  14 . The housing has a typical fluid inlet/outlet port  16 . This is a conventional inlet and outlet system known to those skilled in the art and is not considered an inventive feature of this disclosure. Annular cavity  18  within the housing  12  contains a sealing element  20 . A disc valve  22  is located within a first chamber  24 . A second chamber  26  accommodates spring  28  which bears against sealing element  20  to hold the sealing element in contact with a forward side  46  of the disc valve  22 . A shoulder  30  on the inner end of housing  12  engages port plate  32  (FIG.  1 ). Shaft  34  with an outer end  36  extends through bearing  38  and inwardly through the center bore  14  of the housing  12  to be connected with splines and the like to gear set  40 . 
     End plate  42  is secured to the rearward end of the motor  10  by a plurality of bolts  44  which extend through the end plate  42 , gear set  40 , port plate  32  and thence into a threaded well  45  in housing  12 . As previously indicated, disc valve  22  has a forward side  46  and a rearward side  48  (FIGS. 2 and 3, respectively). Commutation slots  50  are formed in the forward side  46  of the disc valve  22  as best shown in FIG.  2 . 
     Concentric annular grooves  52  and  54  are formed in the rearward side  48  of the disc valve  22  as best shown in FIGS. 3 and 3A. An annular sealing shoulder  56  appears between the outer groove  52  and the inner groove  54 . The shoulder  56  serves as the sealing surface against the sealing element  20 . 
     Blind slots  58  and  60  are formed in the rearward side  48  of disc valve  22  as best shown in FIG.  3 . The volume of blind slots  58  and  60  are substantially equal to the volumes of the commutating slots  50  on the other side of the valve disc  22 . The location of the blind slots  58  and  60  are shown in the most desired location, although some variation from the location shown in FIG. 3 could be entertained without defeating the use and function of this invention. With reference to FIGS. 4 and 5, the center axis and plane is designated by the numeral  62 . The disc valve  22  with the blind slots  58  and  60  will still be deformed when the motor is loaded, but the torsion about the axis  62  will be considerably reduced. This deformation has practically no influence on the tightness, and consequently, the motor efficiency will be improved. 
     When pressure is applied to the motor inlet/outlet  16 , it will tend to deflect the disc element  22  from its symmetrical unloaded position shown in FIGS. 4 and 5 to downwardly or upwardly concave positions of axis  22  (i.e., plane  62 ) when the torsional forces around the axis  22  caused by high fluid pressure in chamber  24  is present. The torsional forces causing the “bending” of plane  62  will be in an opposite direction when torsional forces around the plane  62  acts on the disc valve  22  when chamber  26  contains the higher fluid pressure. 
     The two annular grooves  52  and  54  are used in the prior art but they are not used in conjunction with the blind slots  58  and  60  which serve to balance the mass of material on opposite sides of plane  62 . The torsional forces around the axis or plane  62  will be reduced because the mass of material of the disc valve is more balanced on opposite sides of the plane  62 . Again, this is because of the symmetry of material on opposite sides of the plane  62  afforded by the blind slots  58  and  60 , which have a volume substantially equal to the volume of commutating slots  50 . 
     The two annular grooves  52  and  54  on opposite sides of the disc valve  22  do not allow an indiscriminate location of these blind spots to be located. Care must be exercised that the blind slots do not interconnect the grooves  52  and  54 . 
     First and second fluid chambers  24  and  26  are spaced apart from one another in the housing  12  around shaft  34 . Fluid is communicated with the gear set  40  through a disc valve  22 . The rotating disc valve  22  controls the fluid communication with the fluid chambers  24  and  26  to optimally expand and contract the fluid pressure in the gear set  40 . The disc valve  22  has a first surface that engages the port plate  32  to form a first sealing surface and engages a sealing element  20  in the housing  12  to form a second sealing surface. Commutating slots  50  are formed in the first sealing surface and blind slots  58  and  60  are formed in the second surface and balance the mass of material existing on opposite sides of a plane passing through the disc valve  22  in a direction perpendicular to a longitudinal axis of the disc valve  22 , to enhance fluid sealing conditions created at the sealing surfaces. 
     In operation, high pressure fluid enters one of the ports  16  and flows to one of the fluid chambers, e.g. fluid chamber  24  radially outside the disc valve  22 . The high pressure fluid in fluid chamber  24  enters the commutating slots  50  which open onto the radial outside of the disc valve and flows through passages  61  in port plate  32  to the high-pressure chambers of gear set  40 . High pressure fluid from fluid chamber  24  also enters blind slots  58  in the disc valve  22 . Low pressure fluid from the low-pressure chambers of gear set  40  returns through passages  61  to commutating slots  50  which open towards the radial inside of disc valve  22  and flows into the fluid chamber  26 . The low pressure fluid in fluid chamber  26  also enters blind slots  60  in the disc valve  22 . From the fluid chamber  26  the fluid exits the other port  16 . 
     It is therefore seen that the described blind slots  58  and  60  serve to balance the mass of the disc valve  22  about axis and plane  62 , thus reducing the amount of distortion of the disc valve and reducing the amount of leakage that may occur with respect to the sealing engagement of shoulder  56  with the sealing element  20 , and with respect to the sealing engagement of forward side  46  with port plate  32 . It is thus seen that this invention will achieve at least all of its stated objectives.