Variable displacement pump

Abstract

A variable displacement vane pump includes a housing, an expandable vane control ring, a rotor, a plurality of vanes, slider ring, and biasing means. The expandable vane control ring defines a gap. The plurality of vanes may be slidably disposed in the rotor. The slider ring is pivotally affixed to the housing via a pivot. The slider ring may form a plurality of pumping chambers with the expandable vane control ring, the rotor and the vanes. The distal end of each vane in the plurality of vanes is configured to abut and slide along an inner surface of the slider ring while the rotor rotates and the expandable vane control ring is configured to temporarily contract when intermittent friction is experienced between the inner surface and any vane in the plurality of vanes—so that the plurality of vanes continuously slide along an inner surface of the slider ring.

What is claimed is: 
     
         1 . A variable displacement vane pump comprising:
 a housing defining inlet and discharge ports;   an expandable vane control ring defining a gap and an expandable diameter;   a rotor driven by the drive shaft and coaxially aligned a drive shaft;   a plurality of vanes slidably disposed in the rotor, the plurality of vanes and the rotor being disposed within the expandable vane control ring;   a slider ring pivotally affixed to the housing via a pivot, the slider ring defining a displacement control region with a first portion of the housing, the slider ring  16  cooperating with the expandable vane control ring, the rotor, and the plurality of vanes to form a plurality of pumping chambers that are successively connected to the inlet and discharge ports;   a biasing means acting on the slider ring and urging the slider ring in a first direction via a first force; and   a control unit configured to generate a varying input working fluid pressure via an input working fluid flow to the displacement control region thereby generating a second force on the slider ring about the pivot means in a second direction opposite to the first direction, the second force configured to vary relative to the first force so as vary each pumping chamber and vary the expandable diameter of the expandable vane control ring by pivoting the slider ring while the rotor rotates via the drive shaft.   
     
     
         2 . The variable displacement vane pump as defined in  claim 1  wherein the gap of the expandable vane control ring decreases when the expandable diameter of the expandable vane control ring decreases. 
     
     
         3 . The variable displacement vane pump as defined in  claim 2  wherein the gap of the expandable vane control ring increases when the expandable diameter of the expandable vane control ring increases. 
     
     
         4 . The variable displacement vane pump as defined in  claim 3  wherein the expandable vane control ring defines a plurality of tabs configured to prevent a vane in the plurality of vanes from engaging with the gap. 
     
     
         5 . The variable displacement vane pump as defined in  claim 4  wherein a tab is defined at each end of the expandable vane control ring. 
     
     
         6 . The variable displacement vane pump as defined in  claim 5  wherein an aperture is defined in each tab disposed at each end of the expandable vane control ring. 
     
     
         7 . The variable displacement vane pump as defined in  claim 6  wherein the aperture is configured to engage with an assembly tool aid. 
     
     
         8 . The variable displacement vane pump as defined in  claim 3  wherein an aperture is defined proximate to each end of the expandable vane control ring. 
     
     
         9 . A variable displacement vane pump comprising:
 a housing;   an expandable vane control ring defining a gap and an expandable diameter;   a rotor being coaxially aligned with a drive shaft and driven by the drive shaft;   a plurality of vanes slidably disposed in the rotor;   a slider ring pivotally affixed to the housing via a pivot, the slider ring cooperating with the expandable vane control ring, the rotor, and the vanes to form a plurality of pumping chambers; and   a biasing means acting on the slider ring and urging the slider ring in a first direction via a first force;   wherein a distal end of each vane in the plurality of vanes abuts and slides along an inner surface of the slider ring while the rotor rotates within the slider ring and the expandable vane control ring is configured to temporarily contract when an intermittent friction is experienced between the inner surface and any vane in the plurality of vanes—so that the plurality of vanes continuously slide along an inner surface of the slider ring.   
     
     
         10 . The variable displacement vane pump as defined in  claim 9  wherein the gap of the expandable vane control ring decreases when the expandable diameter of the expandable vane control ring decreases. 
     
     
         11 . The variable displacement vane pump as defined in  claim 10  wherein the gap of the expandable vane control ring increases when the expandable diameter of the expandable vane control ring increases. 
     
     
         12 . The variable displacement vane pump as defined in  claim 11  wherein the expandable vane control ring defines a plurality of tabs configured to prevent a vane in the plurality of vanes from engaging with the gap. 
     
     
         13 . The variable displacement vane pump as defined in  claim 12  wherein a tab is defined at each end of the expandable vane control ring. 
     
     
         14 . The variable displacement vane pump as defined in  claim 13  wherein an aperture is defined in each tab disposed at each end of the expandable vane control ring. 
     
     
         15 . The variable displacement vane pump as defined in  claim 14  wherein the aperture is configured to engage with an assembly tool aid. 
     
     
         16 . The variable displacement vane pump as defined in  claim 11  wherein an aperture is defined proximate to each end of the expandable vane control ring.