Power steering pump with balanced porting

A balanced vane hydraulic pump for use in an automotive power stearing system, comprising:

• a pump housing including a first housing section and a second housing section, the first housing section including a wishbone-shaped gallery for delivery of low pressure fluid to inlet window regions of the pump, and the second housing section having a high pressure gallery;
• a pressure plate located within the housing and having a recessed region connected to the wishbone-shaped gallery for delivery of low pressure fluid with smooth fluid velocity transition;
• a pump drive shaft extending to the first housing section and into the pressure plate;
• a cam ring, located within the pump housing, having a machined inner surface of generally oval shape;
• a rotor generally disposed in a central location within the cam ring, having a plurality of slots in which vanes may move while rotating in unison with the rotor;
• a plurality of vanes, with one vane slidably arranged in each of the slots of the rotor so as to be able to bear against the inner surface of the cam ring during operation of the pump;
• spring means, located within the pump housing, for biasing against the pressure plate;
• and
• low pressure passage means, formed in the pump housing and the pressure plate, for providing ports and concourses to deliver low pressure hydraulic fluid to four inlet window locations adjacent to two pressure sectors of the cam ring located on opposite sides of the drive shaft.

A balanced vane hydraulic pump for use in an automotive power steering system, comprising:

• a pump housing including a first housing section and a second housing section, said first housing section including a substantially symmetrical wishbone-shaped gallery for balanced delivery of low pressure fluid to inlet window regions of the pump;
• a pressure plate located within one of said housing sections, the pressure plate having a recessed region which forms part of the symmetrical wishbone-shaped gallery;
• a pump drive shaft extending to the first housing section and within the pressure plate;
• a cam ring, located within the pump housing, having a machined inner surface of generally oval shape;
• a rotor generally disposed in a central location within the cam ring, having a plurality of slots in which vanes may move while rotating in unison with the rotor;
• a plurality of vanes, with one vane slidably arranged in each of the slots of the rotor so as to be able to bear against the inner surface of the cam ring during operation of the pump assembly;
• spring means, located within the pump housing, for biasing against the pressure plate;
• and
• a thrust plate located on the shaft side of the cam ring, the thrust plate having a recessed region which forms part of the symmetrical wishbone-shaped gallery which is operable as an inlet port for balancing low pressure fluids, a blind high pressure window for receiving high pressure fluid, and an undervane porting system which communicates with the undervane holes within the rotor.