Reversible flow vane pump with improved porting

摘要

A reversible flow vane pump having a pump case with a pump chamber in which a rotor is mounted. The rotor has outwardly-opening slots which carry vanes which engage a cam ring and with fluid chambers between vanes. The cam ring can be adjusted to positions at either side of a neutral position to provide reversible flow operation between a pair of ports, with variable volume control. The ports are arranged to increase the length of time in which a port communicates with an intervane fluid chamber which is of decreasing volume for increased utilization of fluid being pressurized. A port which functions as an inlet port in a predominant mode of operation of the pump has an extension effective to increase the length of time in which an intervane fluid chamber of increasing volume can be filled with fluid. This port extension is blocked from communication with the intervane fluid chambers by the cam ring when the pump is operating other than in the predominant mode of operation in order to prevent communication between the ports.