Patent ID: 8202061

Claim:
A pump system for supplying pressurized working fluid to a device with working fluid pressure requirements that vary with the operating speed of the device, the system comprising: a pump operated by the device such that the pump operating speed is dependent upon the device operating speed, the pump including a control feature regulating an output pressure of the pump; a regulating valve having a first inlet port and a second inlet port in fluid communication with an output of the pump, a first outlet port in fluid communication with a reservoir of working fluid and a second outlet port in fluid communication with the control feature of said pump, said regulating valve having a reciprocating spool that moves in response to pump operating speed to selectively open and close fluid communication of the first inlet port and the second outlet port, said regulating valve biased to close fluid communication between said first inlet port and the second outlet port and open fluid communication between said first and second outlet ports, wherein the regulating valve includes: a first chamber in fluid communication with the second inlet port selectively receiving pressurized working fluid from the output of the pump to generate a first force corresponding to the output pressure of the pump, which urges the spool to move against the bias; and a second chamber selectively receiving pressurized working fluid from the output of the pump to generate a second force corresponding to the output pressure of the pump, the second force acting with the first force generated in the first chamber to move the spool against the bias; and a controller operable to interrupt fluid communication of the second inlet port to alter output pressure of the pump between a first equilibrium pressure and a higher second equilibrium pressure.