Patent ID: 8382626

Claim:
A hydraulic control system for actuating at least one torque transmitting device in a powertrain, the powertrain having an engine and a transmission, the hydraulic control system comprising: a source of pressurized hydraulic fluid powered by the engine; an actuator for selectively actuating the at least one torque transmitting device; a relay valve in communication with the actuator, the relay valve moveable between a first position and a second position wherein the relay valve prevents communication between the source of pressurized hydraulic fluid and the actuator when in the first position and wherein the relay valve allows communication between the source of pressurized hydraulic fluid and the actuator when in the second position; an accumulator for storing and releasing the hydraulic fluid, the accumulator in communication with the actuator and the source of pressurized hydraulic fluid; a first control device disposed between the accumulator and the source of pressurized hydraulic fluid, the first control device having an open condition for allowing fluid communication between the accumulator and the source of pressurized hydraulic fluid and a closed condition for preventing fluid communication between the accumulator and the source of pressurized hydraulic fluid; a second control device disposed between the accumulator and the actuator, the second control device having an open condition for allowing fluid communication between the accumulator and the actuator and a closed condition for preventing fluid communication between the accumulator and the actuator; wherein the accumulator is charged with the hydraulic fluid when the engine is on and the first control device is open, wherein the accumulator stores the hydraulic fluid when the first control device and the second control device are closed, and wherein the accumulator releases the hydraulic fluid when the second control device is open and the relay valve is in the first position.