Variable displacement sliding vane pump

Abstract

A variable displacement sliding vane pump comprising a pump body, inlet and outlet ports formed in said pump body, a drive shaft rotatably mounted in said pump body, a rotor driven by said drive shaft and co-axially aligned therewith, a plurality of radially extending vanes slidably disposed in said rotor, a pivot disposed in said pump body, a slide pivotally disposed on said pivot in said pump body and having a central axis eccentric to the axis of said rotor, a plurality of fluid chambers defined by said rotor, said vanes, and said slide that are successively connected to said inlet and outlet ports, a spring acting on said slide to urge said slide in one direction, a first chamber and a second chamber, each suitable for receiving a fluid pressure and each disposed between said pump body and an outer surface of said slide, the first chamber in fluid communication with a pump outlet discharge pressure, and a valve operable to selectively pressurize and depressurize the second chamber.

1 . A variable displacement sliding vane pump comprising: 
 a pump body;    inlet and outlet ports in said pump body;    a drive shaft rotatably mounted in said pump body;    a rotor driven by said drive shaft;    a plurality of radially extending vanes slidably disposed in said rotor;    a pivot disposed in said pump body;    a slide pivotally disposed on said pivot and having a central axis eccentric to the axis of said rotor;    a plurality of fluid chambers defined by said rotor, said vanes, and said slide that are successively connected to said inlet and outlet ports;    a spring acting on said slide to urge said slide in one direction;    a first chamber and a second chamber, each for receiving a fluid pressure and each disposed between said pump body and an outer surface of said slide;    the first chamber connected to a pump outlet discharge pressure; and    a valve operable to selectively pressurize the second chamber to a fluid pressure greater than an atmospheric ambient pressure condition.    
   
   
       2 . The variable displacement pump as in  claim 1  further comprising a second spring acting in parallel with the spring.  
   
   
       3 . The variable displacement sliding vane pump as in  claim 1 , wherein the valve is electric and controlled by an engine ECU.  
   
   
       4 . The variable displacement sliding vane pump as in  claim 1 , wherein the pump outlet discharge flow rate decreases upon depressurization of the second chamber.  
   
   
       5 . The variable displacement sliding vane pump as in  claim 1 , wherein the second chamber is pressurized to a pressure greater than atmospheric ambient pressure for engine speeds less than a predetermined engine speed and is depressurized to an atmospheric ambient pressure for engine speeds greater than said predetermined engine speed.  
   
   
       6 . The variable displacement sliding vane pump as in  claim 1 , wherein the first chamber and the second chamber are both in fluid communication with a pump output discharge pressure.  
   
   
       7 . A variable displacement sliding vane pump comprising: 
 a pump body;    inlet and outlet ports in said pump body;    a drive shaft rotatably mounted in said pump body;    a rotor driven by said drive shaft and co-axially aligned therewith;    a plurality of radially extending vanes slidably disposed in said rotor;    a pivot disposed in said pump body;    a slide pivotally disposed on said pivot in said pump body and having a central axis eccentric to the axis of said rotor;    a plurality of fluid chambers defined by said rotor, said vanes, and said slide that are successively connected to said inlet and outlet ports;    a spring acting on said slide to urge said slide in one direction;    a first chamber and a second chamber, each in fluid communication with a pump discharge oil pressure and each disposed between the pump body and an outer surface of said slide; and    a valve operable at a predetermined pump speed wherein the second chamber is selectively switched between an ambient atmospheric pressure and an pump discharge oil pressure.    
   
   
       8 . A variable displacement sliding vane pump comprising: 
 a pump body;    inlet and outlet ports formed in said pump body;    a drive shaft rotatably mounted in said pump body;    a rotor driven by said drive shaft and co-axially aligned therewith;    a plurality of radially extending vanes slidably disposed in said rotor;    a pivot disposed in said pump body;    a slide pivotally disposed on said pivot in said pump body and having a central axis eccentric to the axis of said rotor;    a plurality of fluid chambers defined by said rotor, said vanes, and said slide that are successively connected to said inlet and outlet ports;    a spring acting on said slide to urge said slide in one direction;    a first chamber and a second chamber, each suitable for receiving a fluid pressure and each disposed between said pump body and an outer surface of said slide;    the first chamber in fluid communication with a pump outlet discharge pressure; and    a valve operable to selectively pressurize and depressurize the second chamber.    
   
   
       9 . The variable displacement sliding vane pump as in  claim 8 , wherein the second chamber is pressurized to a pressure greater than atmospheric ambient pressure for engine speeds less than a predetermined engine speed and is depressurizeable to an atmospheric ambient pressure for engine speeds greater than said predetermined engine speed.  
   
   
       10 . The variable displacement sliding vane pump as in  claim 8 , wherein the second chamber is pressurizeable up to approximately a pump outlet discharge pressure.