Patent ID: 8352135

Claim:
A method for operating a hybrid drive train of a motor vehicle, said drive train including an internal combustion engine ( 11 ), a transmission ( 15 , 115 ), a first clutch (NAK) arranged between the internal combustion engine ( 11 ) and the transmission ( 15 , 115 ), for transmitting an engine torque directly to the transmission ( 15 , 115 ) an electric machine ( 28 ), means for connecting the electric machine ( 28 ) to the drive train including a second clutch (KM) for connecting the electric machine to the internal combustion engine ( 11 ) without the interposition of the first clutch (NAK), and a third clutch (KE) for connecting the electric machine ( 28 ) to the transmission ( 15 , 115 ) without the interposition of the first clutch (NAK), said method comprising the steps of: transmitting selectively, in a high-torque driving mode, a part of the torque of the internal combustion engine ( 11 ) via the second clutch (KM), the electric machine ( 28 ) and the third clutch (KE) to the transmission ( 15 , 115 ), in order to assist the first clutch (NAK) or in the event of a fault being detected in the first clutch (NAK), connecting the internal combustion engine ( 11 ) to the transmission ( 15 , 115 ) by connecting the electric machine ( 28 ) by means of the second clutch (KM) to the internal combustion engine ( 11 ) and by means of the third clutch (KE) to the transmission ( 15 , 115 ).