Motor drive device of a vehicle sliding door

A device for moving a vehicle sliding door, comprising:

• a motor;
• a force transmission mechanism to transmit a drive force of the motor to the door;
• sensors determining position of the door;
• and
• a shift clutch for coupling the motor to the force transmission mechanism, wherein application of sufficient force to the door by an operator during motor driven movement either elevates a speed of the door or decouples the force transmission mechanism.

A method for operating a motor drive device, during a movement of a movable vehicle sliding door between an open position and a closed position, comprising:

• ascertaining a preselection made by an operator;
• ascertaining a force required for moving the vehicle sliding door to achieve a predetermined normal speed while using stored sensor output signals;
• comparing a difference of the ascertained required force and the force instantaneously output by the electric motor to the predetermined force threshold value;
• in the case of an ascertained first option of the preselection made by the operator and a difference between the ascertained required force and the force instantaneously output by the electric motor, which lies above the predetermined force threshold value, elevating the speed of the vehicle sliding door to the predetermined, elevated speed value by elevating the transmitted drive force;
• in the case of the ascertained first option of the preselection and in the case of a difference between the ascertained force required for the elevated speed and the force instantaneously output by the electric motor close to zero, activating the electric motor to decelerate the vehicle sliding door to the predetermined normal speed;
• and
• in the case of an ascertained second option of the preselection made by the operator and in the case of a difference between the ascertained required force and the force instantaneously output by the electric motor, which lies above the predetermined force threshold value, activating the shift clutch to decouple the force transmission mechanism and the electric motor.