Lost motion mechanism for power liftgate closure system

A power liftgate assembly for moving a liftgate between an open position and a closed position with respect to a motor vehicle having a roof, said power liftgate assembly comprising:

• an elongated bracket fixedly secured to the roof of the motor vehicle, said elongated bracket extending between first and second ends;
• a motor fixedly secured to said elongated bracket, said motor generating a force;
• a slide operatively engaged with said motor for moving along said elongated bracket;
• an articulated bracket connected to said slide for moving with said slide, said articulated bracket including a slot extending therealong providing lost motion between said articulated bracket and said slide allowing manual operation of the liftgate;
• a drive unit operatively connected with said motor for receiving said force thereof and for moving said slide along said elongated bracket;
• and
• an arcuate bracket extending between said articulated bracket and the liftgate for receiving movement of said articulated bracket and moving the liftgate in response thereto upon energizing said motor.

A method for operating a power liftgate assembly for a liftgate of a motor vehicle including a motor, a lead screw driven thereby, a drive nut, a nut switch, an elongated bracket having first and second ends, an articulated bracket having a slot and an arcuate bracket, the method comprising the steps of:

• energizing the motor to generate a rotational force in one direction;
• rotating the lead screw;
• moving the drive nut axially along the lead screw in response to the lead screw rotating;
• moving the articulated bracket and the arcuate bracket to force the liftgate to move using the drive nut;
• identifying when the drive nut reaches one of the first and second ends of the elongated bracket;
• reversing the motor to generate a rotational force in an opposite direction to move the drive nut away from the one of the first and second ends;
• and
• stopping the drive nut at a position along the lead screw adjacent the nut switch.