a door, front and rear carrier units connected to lower portions of a window pane and slidably engaged with the front and rear guide rails, and an electric drive unit installed in a lower part of the door to drive the front and rear carrier units and thus the window pane to move upward and downward along the front and rear guide rails. The drive unit comprises an electric motor, a drum driven by the motor and a cable wire put around the drum. The cable wire extends around the front and rear guide rails and has two portions secured to the front and rear carrier units. When the motor is energized to run, the front and rear carrier units and thus the window pane are moved upwardor downward along the front and rear guide rails.
When, in case of a sashless door, the door is in its closed position with its window pane kept fully raised, a peripheral portion of the window pane is pressed against a weather strip fixed to a vehicle body thereby to achieve a water tight sealing therebetween.
As is known, under a high speed cruising of motor vehicles, a reduced pressure zone is inevitably produced around an outside surface of the window pane. Production of such reduced pressure zone biases the window pane to incline outward increasing the possibility of lowering the air-tightness between the window pane and the weather strip.
In order to suppress or minimize such undesirable outward inclination of the window pane, various measures have been put into practical