Patent ID: 7431043

Claim:
An automatic transmission having a pressure regulator with flow force compensation, said pressure regulator comprising: a valve body having a valve bore and a plurality of inlets in fluid communication with a source of pressurized hydraulic fluid and plurality of outlets, one of said plurality of outlets in fluid communication with a return to said source of pressurized hydraulic fluid, and another of said plurality of outlets in fluid communication with a cooling and lubrication circuit; a valve member slidingly disposed within said valve body that includes a first valve element, a second valve element, and a first area of reduced diameter disposed therebetween, said first valve element, said second valve element, and said first area of reduced diameter adapted to selectively provide a flow path of pressurized hydraulic fluid from one of said plurality of inlets to said outlet in fluid communication with said cooling and lubrication circuit; said valve member further including a third valve element, and a second area of reduced diameter disposed between said third valve element and said second valve element, said second valve element including an outer diameter and a metering face disposed on said second valve element juxtaposed to said second area of reduced diameter, said metering face adapted to control the flow of said pressurized hydraulic fluid selectively provided to said outlet in fluid communication with said return to said source of pressurized hydraulic fluid, said metering face including a flow force compensating annular void disposed adjacent to said outer diameter and defined by a lead angle α measured between said outer diameter and a line intersecting said outer diameter and tangential to said annular void; said second area of reduced diameter having a frusto-conical shape that extends from said third valve element toward said second valve element, said frusto-conical shape adapted to provide compensation for the flow forces of said pressurized hydraulic fluid as said pressurized hydraulic fluid passes though said valve body allowing said pressure regulator to provide a stable and accurate regulation of said pressurized hydraulic fluid.