Patent ID: 7189185
Filing Date: 2007-03-13
Classification: B60W,F16H,Y10T

Abstract:
1. A method for operating a drive train for a motor vehicle, having a drive engine, said drive train including a mechanical 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.