Patent ID: 7856999

Claim:
An automatic transmission having at least one hydraulic valve with flow force compensation, said hydraulic valve comprising: a valve body having a valve bore and at least one inlet adapted to provide fluid communication with a source of pressurized hydraulic fluid and at least one outlet adapted to provide a return to said source of pressurized hydraulic fluid; and a valve member slidingly disposed within said valve body, said valve member including a first valve element, a second valve element, a third valve element, a first area of reduced diameter disposed between said first and second valve elements and a second area of reduced diameter disposed between said second and third valve elements, said second valve element having 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 between said at least one inlet and said at least one outlet of said valve body, said metering face including an annular void disposed adjacent 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 metering face of said second valve element such that said frusto-conically shaped area of reduced diameter is blended into the inner diameter of said annular void, said annular void and said frusto-conically shaped area of reduced diameter 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 hydraulic valve to provide a stable and accurate regulation of said pressurized hydraulic fluid.