Patent ID: 6688999
Filing Date: 2004-02-10
Classification: F16H

Abstract:
A method for controlling a drive train of a motor vehicle having a drive assembly (1) and a continuously variable automatic transmission (3) with a variable speed gear (V), the method comprising the steps of:providing an electronic control unit (15) and an emergency device for controlling at least the continuously variable automatic transmission (3); in an event of failure of the electronic control unit (15), activating the emergency device; in the event of failure of the electronic control unit (15), interrupting a frictional connection between the drive assembly (1) and the continuously variable automatic transmission (3) before the emergency driving mode is made available through the emergency device and re-establishing the frictional connection by a constant pressure/force ratio in the variable speed gear (V), providing a valve (44) for interrupting the frictional connection between the drive assembly (1) and the continuously variable automatic transmission (3), and arranging the valve (44) in a pressure feed line (45) to a clutch arrangement of a forward/reverse driving unit (9) which can be switched, via an emergency program pressure (PNOT), to a position that interrupts the pressurizing medium flow to the clutch arrangement; and actuating the valve (44) dependent upon the emergency program pressure (PNOT), a pressure (PKV) in the pressure feed line (45) to the clutch arrangement of the forward/reverse driving unit (9), a main pressure (PDH) and a pressure control pressure (PEDS).