Patent ID: 8800399

Claim:
A hydraulic circuit ( 88 ) for an automatic transmission having a plurality of gear sets and synchronizers for coordinating shifts between the gear sets, said hydraulic circuit ( 88 ) comprising: a source of pressurized fluid ( 82 ); a shift actuation valve ( 96 ) including a valve body ( 102 ) having a valve bore ( 106 ) and at least one inlet ( 108 ) in fluid communication with said source of pressurized fluid ( 82 ) and at least one outlet ( 110 ) in fluid communication with at least one synchronizer ( 24 ) for selectively controlling gear engagement, a valve member ( 114 ) moveably supported in said valve bore ( 106 ), a solenoid ( 104 ); said valve member ( 114 ) including at least one valve element ( 122 ) having an outer diameter ( 162 ) and a metering face ( 164 ), said metering face ( 164 ) adapted to control the flow of pressurized fluid between said inlet ( 108 ) and said outlet ( 110 ) of said valve body ( 102 ), said metering face ( 164 ) including a flow force compensating annular void ( 166 ) disposed adjacent said outer diameter ( 162 ) and defined by a lead angle α measured between said outer diameter ( 162 ) and a line ( 168 ) intersecting said outer diameter ( 162 ) and tangential to said annular void ( 166 ); said solenoid ( 104 ) adapted to move said valve member ( 114 ) to produce a flow area through said shift actuation valve ( 96 ) that is a function of the current delivered to said solenoid ( 104 ) to deliver a predetermined amount of pressurized fluid to at least one synchronizer ( 24 ) to selectively control the actuation of the synchronizer ( 24 ) to select a predetermined one of the plurality of gear sets in the transmission.