Double clutch transmission for a hybrid electric vehicle and method for operating the same

A method for controlling a double clutch transmission for a hybrid electric vehicle having an engine and a motor, the double clutch transmission including:

• a main input shaft receiving torque from the engine;
• a first input shaft rotating coaxially with the main input shaft;
• a second input shaft rotating coaxially with the main input shaft and along an exterior circumference of the first input shaft;
• first and second clutches for selectively transmitting torque of the main input shaft to either the first or the second input shaft;
• a drive gear unit including a plurality of drive gears disposed on the first and second input shafts;
• a first output device including a first output shaft disposed parallel to and apart from the first and second input shafts by a predetermined distance and also including a plurality of driven gears and a first output gear thereon, such that torque of drive gears on the first and second input shafts are selectively changed and output;
• a second output device including a second output shaft and a reverse idle shaft disposed parallel to and apart from the first and second input shafts by predetermined distances, a plurality of driven gears, a second output gear, a reverse driven gear disposed on the second output shaft, and a plurality of reverse mediating gears disposed on the reverse idle shaft, such that torque of drive gears on the first and second input shafts are selectively changed and output;
• a differential gear connected to both the first output gear and the second output gear;
• and
• a motor input/output unit for selectively transmitting torque of the motor to the second input shaft through a plurality of gears and a drive gear on the second input shaft;
• the method comprising:
• determining an operation mode among an electric vehicle (EV) mode wherein only a torque of a motor is changed and output, a hybrid electric vehicle (HEV) mode wherein both torque of the motor and an engine are changed and output, and a regenerative braking (RB) mode wherein braking and inertial energy of the hybrid electric vehicle is reclaimed by electric generation of the motor;
• and
• operating the double clutch transmission in accordance with the determined operation mode.