Engine speed control via the torque converter lockup clutch of a continuously variable drive

A method for controlling engine rotational speed via a torque converter lock-up clutch during the starting and stopping phases of a motor vehicle having a continuously variable transmission, the method comprising the steps of:

• starting the vehicle by disengaging a forward clutch and fully closing the torque converter lock-up clutch while the vehicle is in a standstill position to ensure an asymptotic adjustment between an engine rotational speed and a turbine rotational speed;
• and
• stopping the vehicle by opening the converter lock-up clutch and ensuring that the engine rotational speed does not fall below the turbine speed and substantially equals the turbine rotational speed for as long as possible to provide a moderate defined separation between the engine rotational speed and the turbine rotational speed when stopping.

A method for engine rotational speed control via a torque converter lock-up clutch during the starting and stopping phases of a motor vehicle having a continuously variable transmission combined with other elements of a drive train, the method, comprising the steps of:

• using the closing and opening of the torque converter lock-up clutch as an implicit function defined by a most asymptotic adjustment as possible of the rotational speed gradients of the engine and a turbine when starting and by soft, defined separation of the rotational speed curves of the engine and the turbine when stopping, and
• an optimum comfort is ensured in that when the vehicle stands still a forward clutch is moved to a standstill disengaged mode so that the torque converter lock-up clutch can be fully closed;
• wherein at starting the engine rotational speed is approximated by the torque converter lock-up clutch to a defined trajectory, the engine rotational speed at the end of the trajectory being the same as the turbine rotational speed.