Patent ID: 8132635

Claim:
A motor lock prevention control device for a hybrid electric vehicle, the hybrid electric vehicle having an engine and a motor-generator as a driving power source, driving wheels and a start clutch, the motor-generator being connected to the engine and the driving wheels via shafts, respectively, to output a torque of the motor-generator to the engine and to the driving wheels, the start clutch being disposed between the motor-generator and the driving wheels to change a transmission torque capacity of the start clutch between the motor-generator and the driving wheels, the hybrid electric vehicle being placed into an electric drive mode in which the vehicle is powered by the motor-generator with the engine stopped or a hybrid drive mode in which the vehicle is powered by the engine and the motor-generator upon engagement of the start clutch, the motor lock prevention control device being configured to: judge whether the motor-generator is being energized in such a manner as to cause heat generation in a motor locked state under a drive load operating condition; when the motor-generator is judged as being energized in such a manner as to cause heat generation in the motor locked state under the drive load operating condition, perform motor lock prevention control to induce rotation of the motor-generator by adjusting at least one of the transmission torque capacity of the start clutch and the torque of the motor-generator such that the torque of the motor-generator exceeds the transmission torque capacity of the start clutch; and after inducing said rotation of the motor-generator, while maintaining the transmission torque capacity of the start clutch at a given value, increase the torque of the motor-generator such that a rotational speed of the motor-generator reaches a level corresponding to a motor unlocked state of the motor-generator.