VANE PUMP USING LINE PRESSURE TO DIRECTLY REGULATE DISPLACEMENT

摘要

A variable displacement vane pump includes at least two regulation chambers to provide a regulating force to the cam ring to counter the force applied to the cam ring by a regulating spring and reduce pulsation in the output working fluid from the pump. A first regulation chamber is part of the pump outlet and is in fluid communication with the outlet port of the pump via a passage which allows the pump to be fabricated from a diecast process or the like. A second regulation chamber is connected to the first chamber via an orifice which reduces the pressure of working fluid supplied from the first chamber to the second. The pump outlet need not overlie the pump outlet. Further, a pump with an inlet port with a relatively large initial cross-sectional flow area inhibits cavitation of the working fluid when the pump is operated at higher operating speeds.