Dual clutch control system for integral torque converter and retarder and method thereof

A method of operating a transmission system, the transmission system including a fluid-coupling device having an input coupled to an impeller, an output coupled to a turbine, and a stator disposed between the impeller and the turbine, an electro-hydraulic control system having a flow valve disposed in fluid communication with the input and the output of the fluid-coupling device that is movable between at least a first position and a second position, at least one trim valve system fluidly coupled to the flow valve, and a solenoid disposed in fluid communication with the flow valve that is electrically controllable between an energized state and a de-energized state, a clutch disposable in fluid communication with the flow valve that is controllable between an applied position and an unapplied position, and a control circuit coupled to the at least one trim valve system and the solenoid, the method comprising:

• de-energizing, by the control circuit, the solenoid to cause operation of the flow valve in the first position;
• fluidly coupling, by the flow valve, the at least one trim valve system with the clutch to cause operation of the clutch in the applied position when the flow valve is in the first position;
• coupling, by the clutch, the stator to ground when the clutch is in the applied position;
• and
• reducing an output speed of an output of the transmission system when the stator is coupled to the ground.

A method of operating a transmission system, the transmission system including a fluid-coupling device having an input coupled to an impeller, an output coupled to a turbine, and a stator disposed between the impeller and the turbine, an electro-hydraulic control system having a flow valve disposed in fluid communication with the input and the output of the fluid-coupling device that is movable between at least a first position and a second position, at least one trim valve system fluidly coupled to the flow valve, and a solenoid disposed in fluid communication with the flow valve that is electrically controllable between an energized state and a de-energized state, a clutch disposable in fluid communication with the flow valve that is controllable between an applied position and an unapplied position, a second clutch disposable in fluid communication with the flow valve, and a control circuit coupled to the at least one trim valve system and the solenoid, the method comprising:

• energizing, by the control circuit, the solenoid to cause operation of the flow valve in the second position;
• allowing bi-directional rotation of the stator when the solenoid is energized;
• fluidly coupling, by the flow valve, the at least one trim system to the second clutch to cause application of the second clutch;
• coupling, by the second clutch, the impeller and the turbine to one another in a lockup state;
• and
• modulating, by the control circuit, a fluid pressure provided to the second clutch to slip the second clutch to reduce any vibrations from being transmitted by the output of the fluid-coupling device to an output of the transmission system.