Patent ID: 9651046
Date: 2017-05-16
CPC Classifications: F01M,F04C

Claim:
1. A variable capacity vane pump having a control ring for altering the output capacity of the pump, the variable capacity vane pump comprising: a pump casing having a pump chamber therein, the pump casing having an inlet port and an outlet port; vane pump rotor rotatably mounted in the pump chamber; the control ring enclosing the vane pump rotor within the pump chamber, a plurality of vanes operatively engaging the rotor and frictionally engaging the control ring for pumping a fluid from the inlet port, through the pump chamber and to the outlet port, the control ring being moveable within the pump chamber to alter the volumetric capacity of the pump; a variable control chamber defined by the pump casing and the control ring, the control chamber operable to receive pressurized fluid to create a force to bias the control ring toward a position of minimum volumetric capacity of the pumping chambers; a first return spring for biasing the control ring in a direction toward a position of greater volumetric capacity of the pump, the force of the first return spring acting against the force of the control ring to establish a first equilibrium; a second return spring for biasing the control ring in a direction toward a position of greater volumetric capacity of the pump, the force of the second return spring acting against the force of the control ring after the control ring has moved at least a first predetermined amount against the biasing force of the first return spring; and a shaft having a first end coupled to a tab of the control ring and a second end located distal from the first end and the control ring, the second end of the shaft being spaced a predetermined distance from the housing of the pump, wherein the second end of the shaft includes a pretension element coupled at the second end to define a shoulder for trapping the second spring between the tab and the pretension element of the second end of the shaft, and wherein the second spring is located between the control ring and the second end.