Patent ID: 6171211
Filing Date: 2001-01-09
Classification: F16H,Y10T

Abstract:
A control valve circuit for an automatic transmission in an automotive vehicle driveline having an engine and traction wheels;multiple-ratio gearing having a torque output shaft connected drivably to the traction wheels;a hydrokinetic unit having an impeller connected to the engine and a turbine connected to a torque input element of the gearing;clutch and brake means for establishing and disestablishing multiple torque flow paths through the gearing including a forward drive clutch selectively connecting the turbine to the torque input element of the gearing;a selectively engageable bypass clutch in the hydrokinetic unit connecting the turbine to the torque input element of the gearing when it is engaged;a main pressure regulator valve means for supplying an engaging hydraulic line pressure to the valve circuit, a line pressure modulator valve in the valve circuit for modulating the line pressure;an engagement valve means in the circuit between the line pressure modulator valve and the forward drive clutch for distributing modulated line pressure to the forward drive clutch when it assumes a first position and for distributing regulated line pressure to the forward drive clutch when it assumes a second position;a bypass clutch control valve means in the valve circuit for distributing actuating pressure to the bypass clutch;a bypass clutch solenoid valve means for developing a pressure signal that activates the engagement valve means to effect modulated line pressure distribution to the forward drive clutch when the engagement valve is in its second position; andan electronic pressure control valve means responsive to driveline operating variables for developing a torque sensitive pressure signal, the line pressure modulator valve means responding to the torque sensitive signal to effect a modulated line pressure that results in slipping engagement of the forward drive clutch when the transmission is operating in a low speed ratio with the engine idling.