Patent ID: 8239110

Claim:
A method of operating a drivetrain of a motor vehicle, the drivetrain comprising a drive aggregate formed as a hybrid drive comprising an internal combustion engine and an electric machine, and a transmission being connected between the drive aggregate and a drive output, the drivetrain also comprises a pressure reservoir system with at least one pressure reservoir and at least one pressure generator which is powered by the internal combustion engine, by which the at least one pressure reservoir is filled, the method comprising the steps of: ascertaining whether the motor vehicle is either driving or stationary; measuring an actual pressure in the at least one pressure reservoir of the pressure reservoir system; comparing a value of the actual pressure in the pressure reservoir system with a first threshold value, if the motor vehicle is driving; comparing the value of the actual pressure in the pressure reservoir system with a second threshold value, if the motor vehicle is stationary; defining the second threshold value as being lower than the first threshold value; when the motor vehicle is driving and the value of the actual pressure is higher than the first threshold value, permitting stopping of the internal combustion engine; when the motor vehicle is driving and the value of the actual pressure is lower than the first threshold value, preventing stopping of the internal combustion engine; when the motor vehicle is stationary and the value of the actual pressure is higher than the second threshold value, permitting stopping of the internal combustion engine; and when the motor vehicle is stationary and the value of the actual pressure is lower than the second threshold value, preventing stopping of the internal combustion engine.