Auburn Hills, Mich. -- Ann Heiser was attending a company picnic when the topic of manually opening and closing minivan liftgates surfaced.

"Several small-statured women were discussing the challenges of reaching up and closing their minivan liftgates," said Heiser. "Some said they used umbrella handles to reach up and close the liftgate and one woman explained how she actually tied a cord to the inside handle of her liftgate in order to pull it shut."

Lucky for millions of future minivan owners around the world, Heiser works for DaimlerChrysler Corporation, the world's largest manufacturer of minivans. Heiser, a senior administrative assistant at DaimlerChrysler's Liberty and Technical Affairs Division in Rochester Hills, Mich., brought the issue to the attention of the division's vice president, Tom Moore, who immediately authorized a power liftgate study and task force.

"After reviewing a variety of concept drawings and design approaches, we discovered a solution and yet another minivan first," said Moore. "An electric-powered device was chosen to operate the liftgate not only for its simplicity and low cost, but also because it fit into the existing structure of our minivans. After conducting market research, minivan platform engineers quickly embraced this mechanism and worked to enhance and refine the technology into today's design."

Powered by an electric motor, opening or closing the liftgate takes approximately four seconds. Push buttons on the key fob and in the overhead console operate the power liftgate. The power liftgate includes an obstacle detection feature that works in both opening and closing directions. In order to alert people in the vicinity of the opening or closing liftgate, a "beep" from a tone generator in the light bar sounds for two seconds before the liftgate starts to open or close. The beeping continues during the first two seconds of movement.

As with the power sliding doors, the mechanism detects resistance to movement and reverses to avoid damage to the door or the obstruction. In addition, pinch sensors attached to the sides of the liftgate opening detect the presence of hands or other objects that offer too little closing resistance to be detected by the primary obstacle detection system.

  Autoworld.com

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