Drive unit for a hybrid motor vehicle

A method of controlling a drive unit (1) for a hybrid motor vehicle for coupling an internal combustion engine (2) and a dynamoelectric machine (3) to a transmission (4), the drive unit (1) including an input shaft (5) which is connected for rotation with the internal combustion engine (2), an output shaft (7), which is connected to the transmission (4) and to the dynamoelectric machine (3) for driving the output shaft (7) or to be driven thereby and a clutch (8) for connecting the input shaft (5) to the output shaft (7) including means for a centrifugal force-enhanced engagement of the clutch (8) and electrically actuated pulling magnets (14) for initiating engagement of the clutch (8), said method comprising the steps of:

• for starting the internal combustion engine (2), energizing, the dynamoelectric machine (3) and also the pulling magnets (14) so as to close the clutch (8) and provide for rotation of the engine by the dynamoelectric machine (3), deactivating the pulling magnets (14) when the engine (2) speed has reached a threshold value (nGW) and the engine has started to operate,
• during the transition from operation by the internal combustion engine to an operation by the dynamo electric machine, lowering in a first step the speed of the internal combustion engine (2) to the threshold value (nGW) whereby the clutch (8) opens and, in a second step, activating the dynamoelectric machine (3) for driving the output shaft while the engine is shut down,
• for restarting the engine (2) while the dynamoelectric machine is activated, reducing, in a first step, the speed of the dynamoelectric machine (3) to the threshold value (nGW), energizing, in a second step, the pulling magnets (14) for closing the clutch (8) and, when the internal combustion engine has reached the speed of the threshold value (nGW), in a third step, deactivating the pulling magnetic (14).