Abstract:
A hydraulic rotary device operable as either a hydraulic pump or a hydraulic motor. The end plates  20  and  24  has plurality of grooves  14  and  16  continuously communicating with one of the plurality of pressures and communicating with fluid chambers  17  at the inner edge of a plurality of vanes  23  during a predetermined time in one rotation.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is entitled to the benefit of Provisional Patent Application Ser. No. 60/327,931 filed Oct. 9, 2001. 
     
    
     
       BACKGROUND  
         [0002]    1. Field of Invention  
           [0003]    This invention relates to hydraulic motor or pump, specifically to such motors or pumps of rotary type with vanes, rollers or slippers.  
           [0004]    2. Description of Prior Art  
           [0005]    Hydraulic motors and pumps are commonly used to transmit power. Different designs of pumps were used for this purpose.  
           [0006]    Originally these pumps and motors were designed with only pressurized fluid supplied to fluid chamber at the inner edge of the vane to push against cam ring. Such  
           [0007]    motors and pumps generated significant noise, have low volumetric efficiency and higher frictional losses.  
           [0008]    Thereafter, inventors created several types of motors and pumps. Rotary vane pump with small groove supplying fluid to vanes reduced the radial force during the filling cycle.  
           [0009]    But the pressurized fluid was lost for filling the chamber at the inner edge of the vane. In the place of vanes, slippers and rollers were tried to reduce the friction losses. But the volumetric efficiency remained low since pressurized fluid is spent for pushing the vane against the cam ring. Also the loss is high since fluid leaks from the pressurized fluid chamber at the inner edge of the vane to the lower pressure area in filling chamber during the filling cycle.  
           [0010]    The above losses apply to the motor also. Mechanical output is lower due to the above losses. When used as a hydraulic motor, fluid is lost by leakage since pressurized fluid is admitted to the vanes during the discharging cycle. Also frictional losses remain high since the vanes are continuously rubbing against the cam ring with significant force.  
         SUMMARY  
         [0011]    In accordance with my present invention a higher efficiency motor or pump comprises of valves supplying either higher or lower pressure fluid at the inner edge of the vane during part of the rotation.  
         Objects and Advantages  
         [0012]    Objects and advantages of the present invention are:  
           [0013]    a) to provide higher volumetric efficiency by using lower pressure fluid to fill chamber at inner edge of vane.  
           [0014]    b) to provide lesser friction loss by applying pressurized fluid to push the vane to the outer ring for shorter duration of the cycle.  
           [0015]    c) to create lesser noise since vanes are pushed against the cam ring for a lesser period of time.  
           [0016]    d) to eliminate loss of fluid by leakage from fluid chamber at the inner edge of the vane to working chamber is eliminated during fill cycle by providing lower pressure fluid to the fluid chamber at the inner edge of the vane during the fill cycle.  
       
    
    
     DRAWING FIGURES  
       [0017]    [0017]FIG. 1 shows one end plate with grooves.  
         [0018]    [0018]FIG. 2 shows rotor vanes cam ring and one end plate assembled together.  
         [0019]    [0019]FIG. 3 shows exploded view of end plate  1 , cam ring, rotor, vanes, end plate  2  and shaft. 
     
    
     Reference Numerals in Drawings  
       [0020]    [0020] 11  fluid outlet  
         [0021]    [0021] 12  fluid inlet  
         [0022]    [0022] 13  passage from fluid outlet to groove  
         [0023]    [0023] 14  groove supplying high pressure fluid  
         [0024]    [0024] 15  passage from fluid inlet to groove  
         [0025]    [0025] 16  groove supplying low pressure fluid  
         [0026]    [0026] 17  fluid chamber at the inner edge of the vane  
         [0027]    [0027] 18  part of high pressure fluid groove  
         [0028]    [0028] 19  part of low pressure fluid groove  
         [0029]    [0029] 20  end plate  1   
         [0030]    [0030] 21  cam ring  
         [0031]    [0031] 22  rotor  
         [0032]    [0032] 23  vane  
         [0033]    [0033] 24  end plate  2   
         [0034]    [0034] 25  shaft  
       DESCRIPTION  
       [0035]    A preferred embodiment of the variable flow vane pump is illustrated in FIG. 3 (Exploded view of two end plates, cam ring, rotor, vanes and shaft) and FIG. 1 (End plate). The pump has a rotor  22  with slots to hold the vanes  23 . Vanes  23  are positioned to slide in radial direction during operation. A cam ring  21  surrounds the vanes. Two end plates  20  and  24  are positioned sandwiching a rotor  22  and a cam ring  21 . The rotor  22  is attached to a shaft  25  that turns the rotor  22  and vanes  23 .  
         [0036]    A groove supplying low pressure fluid  16  and a groove supplying high pressure fluid  14  are formed on the end plate. The width of the grooves  16  and  14  are made sufficient to allow fluid easily. Pumping cycle is the duration of the rotation when fluid chamber volume is reduced and displaces fluid to outlet. The length and location of the groove  14  is made to contact the fluid chamber at the inner edge of the vanes during the pumping cycle. A passage from fluid outlet to groove  13  terminates in a groove  14  and leads to a fluid outlet  11 .  
         [0037]    Filling cycle is the duration of the rotation when fluid chamber volume is increased and fluid flows in from the inlet. The length and location of the groove  16  is made to contact the fluid chamber at the inner edge of the vanes during the filling cycle. Passage from fluid inlet to groove  15  terminates in groove  16  and leads to the fluid inlet  12 .  
       Additional Embodiments  
       [0038]    There are various possibilities with regard to the use of improved efficiency pump or motor with currently known enhancements such as variable flow motors and pumps-or incorporate other control devices.  
       Alternative Embodiments  
       [0039]    a) There are various possibilities with regard to the construction of a rotary hydraulic pump with higher efficiency. Passage  13  and  15  shown in FIG. 1 can be substituted with holes or passages in a different manner to connect to fluid inlet and fluid outlet.  
         [0040]    b) Grooves supplying fluid to the fluid chamber at the inner edges of the vanes may be formed on either one of the end plates or both.  
         [0041]    The duration of the valve opening and closing may be increased or decreased. Vanes can be substituted with rollers or slippers for the same result. Springs may be used to push the vane against the cam ring for improving sealing between vanes and cam ring. The pump can also be used as a hydraulic motor by operating with fluid under pressure as input to result in rotating motion as output.  
       Advantages  
       [0042]    From the description above, a number of advantages of my hydraulic pump become evident:  
         [0043]    a) Fluid under pressure is applied to the vanes for only part of the cycle resulting in less friction from vanes rubbing against cam ring.  
         [0044]    b) During the filling cycle, vanes move outward with centrifugal force filling the fluid chamber at the inner edge of the vane with low pressure fluid, thus eliminating the waste of high pressure fluid for filling this chamber.  
         [0045]    c) Loss of fluid by leakage from fluid chamber at the inner edge of the vane to working chamber is eliminated during fill cycle because fluid in the fluid chamber and the working chamber are at low pressure during the fill cycle.  
         [0046]    d) During pumping cycle fluid in the fluid chamber at the inner edge of the vane is pumped to the outlet of the pump thereby increasing the volumetric efficiency.  
       Operation  
       [0047]    The manner of using the improved efficiency hydraulic pump or motor is identical to that for hydraulic vane pumps in present use. Namely, when used as a vane pump the shaft is rotated to pump fluid. When used as a hydraulic vane motor, pressurized fluid is used to generate mechanical work. Hydraulic vane pumps in present use work by providing only pressurized fluid to the fluid chamber at the inner edge of the vane  17  to move the vanes and seal against the cam ring  21 .  
         [0048]    Depending on the direction of the rotation of the rotor, pumping cycle is the period when the vane  17  is pushed in by the cam ring  21 . filling cycle is the period when the vane  17  is pushed out to contact the cam ring  21 .  
         [0049]    The improved efficiency vane pump provides fluid at lower pressure at the chamber  17  during the fill cycle. Fluid at higher pressure is provided at the chamber  17  to create seal between vanes  23  and the cam ring  21  during the pumping cycle.  
         [0050]    This is accomplished by the proper positioning of groove  14  and groove  16 . When assembled together, part of the high pressure groove  18  communicates with chamber  17  thereby providing pressurized fluid for sealing the vane  23  against cam ring  21 . The size and location of the groove  14  is chosen to communicate with all the chambers  17  of the vanes necessary to provide pumping action. The size and location of the groove  16  is chosen to communicate with all the chambers  17  of the vanes during the filling cycle.  
       Conclusion, Ramifications, and Scope  
       [0051]    Accordingly the reader will see that the improved vane pump has high volumetric efficiency. Allowing lower pressure fluid to fill the chamber at the inner edge of the vanes result in savings of fluid at high pressure.  
         [0052]    Also leakage of fluid at high pressure is eliminated from the chamber at the inner edge of the vanes to lower pressure fluid during the filling cycle. Lower pressure at the inner edge of the vanes reduces the contact force on the vanes against the cam ring during filling cycle. Lower sliding force of vanes results in reduced frictional losses.  
         [0053]    Although the description above contains many specifications, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. For example the pump can have rollers or spring loaded vanes or other shapes with grooves etc; the lower pressure at the fluid chamber at the inner edge of the vane can be at an intermediate pressure between input and output pressure. Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.