Method for operating a drive train in a motor vehicle

A method for operating a drive train for a motor vehicle, having a drive engine, said drive train including a mechanical, in particular continuously variable, transmission with an operating piston (23), and a hydrodynamic torque converter (1) with a pump wheel (5) and a turbine wheel (7) disposed in the drive train ahead of the transmission, the torque converter (1) having a converter lockup clutch (17) which acts between the pump wheel (5) and turbine wheel (7) and can be closed by means of a working pressure acting on the operating piston (23), and an increased internal pressure, which also acts on the operating piston (23) and counteracts the working pressure of the converter lockup clutch (17), and which is produced in the torque converter (1) under overrun conditions, said method comprising the steps of:

• monitoring at least one operational variable of the motor vehicle while the converter lockup clutch (17) is closing, reducing the rotational speed ratio (55, 57) of the turbine wheel (7) with respect to the pump wheel (5) in accordance with the operational variable by changing one of the engine speed and the transmission ratio (59, 61), and monitoring the transmission ratio (59, 61) (indirectly or directly) as an operational variable.