Variable displacement vane pump with pressure balanced vane

摘要

A radially pressure balanced vane pump includes a housing that defines an inlet port and a discharge port. A cam block disposed within the housing defines a continuous inner surface. A plurality of vanes are supported within rotor slots and rotated above a shaft. Each vane includes a vane tip having a radius with a centerline offset from the centerline of the vane. A pressure biasing the vane into contact with the cam block is distributed over the vane tip radius. Further, the vanes are biased into contact with the inner surface of the cam block by communication of discharge pressure under the vane. The vane tip radius along with the pressure balance between under vane and under vane discharge pressure provide for the use of low cost and easily fabricated ductile steels.