Transmission with torque converter disconnect clutch and engine braking friction clutch

A transmission for a hybrid vehicle, the transmission comprising:

• a housing;
• a transmission input member rotatably supported by the housing;
• a torque converter having a pump and a turbine, wherein the turbine is connected to the transmission input member for transferring torque therebetween;
• a lock-up clutch selectively operable to connect the pump and the turbine for rotation together;
• a cover connected to and rotatable with the pump and at least partially defining an interior of the torque converter;
• a torque converter input member passing through the cover and configured for attachment to a crankshaft of an engine;
• a one way clutch disposed within the interior of the torque converter and interconnecting the torque converter input member and the cover, wherein the one way clutch is operable to communicate a drive torque from an engine between the torque converter input member and the cover, and wherein the engine brake friction clutch is operable to communicate a braking torque between the cover and the torque converter input member;
• an engine brake friction clutch disposed within the interior of the torque converter, and selectively interconnecting the torque converter input member and the cover in torque communication, wherein the engine brake friction clutch is controlled to an engaged position to communicate torque between the torque converter input member and the cover, and wherein the engine brake friction clutch is controlled to a disengaged position to disconnect torque communication between the torque converter input member and the cover;
• an electric device coupled to the pump and operable to supply torque to the pump;
• and
• a control system operable to send a control signal to the engine brake friction clutch to move the engine brake friction clutch between its engaged position and its disengaged position, wherein the control system includes:
• a first fluid circuit for supplying a first fluid control signal at a first fluid pressure to an apply side of the lock-up clutch;
• a second fluid circuit for supplying a second fluid control signal at a second fluid pressure to a release side of the lock-up clutch and to an apply side of the engine brake friction clutch;
• an exhaust fluid circuit for exhausting fluid from a release side of the engine brake friction clutch;
• and
• wherein the engine brake friction clutch is controlled between its engaged position and its disengaged position by the second fluid pressure of the second fluid control signal.

A method of controlling a transmission of a hybrid vehicle, the transmission including a torque converter having a pump and a turbine, a torque converter input member connected to a crankshaft of an engine and passing through a cover of the pump into an interior of the torque converter, a lock-up clutch selectively interconnecting the pump and the turbine, and an engine brake friction clutch disposed within the interior of the torque converter and selectively interconnecting the cover and the torque converter input member, the method comprising:

• providing a hydraulic control system for controlling the transmission, the hydraulic control system including:
• a first fluid circuit for supplying a first fluid control signal to an apply side of the lock-up clutch at a first fluid pressure,
• a second fluid circuit for supplying a second fluid control signal to a release side of the lock-up clutch and an apply side of the engine brake friction clutch at a second fluid pressure;
• an exhaust fluid circuit for exhausting fluid from a release side of the engine brake friction clutch at an exhaust fluid pressure;
• and
• controlling the operation of the engine brake friction clutch by varying the first fluid pressure of the first fluid control signal and the second fluid pressure of the second fluid control signal used to control the lock-up clutch.