Pump device

Abstract

A fixed capacity pump (P) sucks working oil from a reservoir (R) through a conduit (Rp) and a suction passage (1), and discharges the pressurized working oil into a discharge passage (2) connected to an actuator (A). A choke (21) is disposed in the discharge passage (2), and a flow control valve (F) recirculates a part of the working oil in the discharge passage (2) upstream of the choke (21) to the suction passage (1) according to a pressure loss generated by the choke (21). The characteristic of the choke (21) which significantly increases the flow resistance in a low temperature state makes the flow rate of the recirculated working oil increase, thereby preventing cavitation/noise from occurring in the pump (P) when operated at high speed and in a low temperature state.

Dependencies are inferred from the claim text.