Patent ID: 8858390

Claim:
A method of operating a drive train of a motor vehicle for a crawling start of the motor vehicle in which the drive train comprises a hybrid drive with a combustion engine ( 2 ) and an electric motor ( 3 ); a clutch ( 4 ) is positioned between the combustion engine ( 2 ) and the electric motor ( 3 ); a transmission ( 5 ) is positioned between the hybrid drive and an output ( 6 ); the drive includes either a transmission internal starting element ( 9 ) or a transmission external starting element ( 7 ) along with a brake pedal ( 11 ) and an accelerator pedal ( 10 ), the method comprising the steps of: initiating the crawling start of the motor vehicle, with the drive train being in a starting condition in which the clutch ( 4 ), which is positioned between the combustion engine ( 2 ) and the electric motor ( 3 ), is disengaged, and the brake pedal ( 11 ) is activated and the accelerator pedal ( 10 ) is unactivated, and the combustion engine ( 2 ) of the hybrid drive is turned off; either bringing the starting element ( 7 , 9 ) to filling pressure or maintaining the filling pressure of the starting element ( 7 , 9 ) either by deactivation or after deactivation of the brake pedal ( 11 ); immediately thereafter bringing the electric motor ( 3 ) of the hybrid drive, which is operated in a rotational speed controlled mode, to a rotational speed that is higher by a defined slippage rotational speed than a transmission side rotational speed of the transmission ( 5 ); further engaging the starting element ( 7 , 9 ) to create torque at the output ( 6 ) for the crawling start, when the slippage is reached; and continually operating the electric motor ( 3 ) in the rotation speed controlled mode to maintain the slippage for the crawl starting.