Variable displacement pump systems

Abstract

A variable displacement pump can include a rotor having a plurality of vanes, and a cam ring surrounding the rotor and vanes. The vanes can be configured to extend from the rotor and contact an inner cam surface of the cam ring. The pump can also include one or more radial actuators configured to apply a radial force to the cam ring to control a position of the cam ring and the pumping action.

What is claimed is: 
     
         1 . A variable displacement pump, comprising:
 a rotor having a plurality of vanes;   a cam ring surrounding the rotor and vanes, the vanes configured to extend from the rotor and contact an inner cam surface of the cam ring; and   one or more radial actuators configured to apply a radial force to the cam ring to control a position of the cam ring and the pumping action.   
     
     
         2 . The pump of  claim 1 , wherein the one or more radial actuators are or include an electromechanical actuator. 
     
     
         3 . The pump of  claim 1 , further comprising a controller configured to directly control the one or more radial actuators to achieve a desired pumping action. 
     
     
         4 . The pump of  claim 1 , further comprising one or more biasing members configured to provide an opposing force to a direction of force applied by the one or more radial actuators to bias the cam ring in a bias direction. 
     
     
         5 . The pump of  claim 4 , wherein the bias direction is a maximum pumping action direction. 
     
     
         6 . The pump of  claim 4 , further comprising an alignment shaft for each biasing member. 
     
     
         7 . The pump of  claim 4 , wherein the one or more radial actuators are configured to apply the radial force in a radial direction that intersects a rotational axis of the rotor, and the one or more biasing members are configured to apply the opposing force in an opposite direction of the radial direction which also intersects the rotational axis of the rotor. 
     
     
         8 . The pump of  claim 7 , wherein the one or more radial actuators and the one or more biasing members are positioned on an opposite side of the cam ring 180 degrees apart. 
     
     
         9 . The pump of  claim 7 , wherein the one or more radial actuators and the one or more biasing members are positioned on a same side of the cam ring. 
     
     
         10 . The pump of  claim 7 , wherein the one or more biasing members includes a plurality of biasing members. 
     
     
         11 . The pump of  claim 10 , wherein one or more of the plurality of biasing members are positioned on an opposite side of the cam ring 180 degrees apart from the one or more radial actuators, and wherein one or more of the plurality of the biasing members are positioned on a same side of the cam ring as the one or more radial actuators and are aligned with the one or more radial actuators. 
     
     
         12 . The pump of  claim 7 , wherein the one or more radial actuators include a plurality of radial actuators. 
     
     
         13 . The pump of  claim 12 , wherein the plurality of radial actuators are aligned axially on a single side of the cam ring such that the radial force from each radial actuator passes through the rotational axis of the rotor. 
     
     
         14 . The pump of  claim 12 , wherein the one or more biasing members includes one or more biasing members disposed between at least two of the plurality of actuators on a same side of the cam ring. 
     
     
         15 . A fuel system for an aircraft, comprising:
 a variable displacement pump, comprising:
 a rotor having a plurality of vanes; 
 a cam ring surrounding the rotor and vanes, the vanes configured to extend from the rotor and contact an inner cam surface of the cam ring; and 
 one or more radial actuators configured to apply a radial force to the cam ring to control a position of the cam ring and the pumping action. 
   
     
     
         16 . The system of  claim 15 , wherein the one or more radial actuators are or include an electromechanical actuator. 
     
     
         17 . The system of  claim 15 , further comprising a controller configured to directly control the one or more radial actuators to achieve a desired pumping action. 
     
     
         18 . The system of  claim 15 , further comprising one or more biasing members configured to provide an opposing force to a direction of force applied by the one or more radial actuators to bias the cam ring in a bias direction. 
     
     
         19 . The system of  claim 18 , wherein the bias direction is a maximum pumping action direction. 
     
     
         20 . The system of  claim 18 , further comprising an alignment shaft for each biasing member.