A standard motor-vehicle door latch has a housing mounted on the door edge and formed with a recess into which is engageable a bolt projecting from the edge of the respective door opening. A fork is pivotal in the housing between a latching position engaging around the bolt and holding it solidly in the recess and a freeing position permitting the bolt to enter and leave the recess. A latch pawl engageable with the fork can retain it in the latched position. The latch pawl in turn is controlled via appropriate levers which can therefore operate the latch to allow the door to be opened. When the latch is used on a side door, inside and outside actuating mechanisms are provided, and when on a trunk or hatch, an inside release and outside lock cylinder can operate the pawl.
In a power-assist system the bolt is movable between end positions perpendicular to the closing and opening direction of the respective door (which term is here intended to cover a trunk lid or hatch). Thus once the pawl engages around the bolt the door is in a partially closed position and subsequent inward movement of the bolt pulls this partly closed door into the fully closed position.
A thus equipped door is opened manually simply by actuating the appropriate mechanism to pull back the latch pawl. If, however, it is desired to open the door electrically, as is for instance convenient with a trunk latch, there are substantial problems. The fact that the servoactuator that moves the door bolt between its end positions is located in the door post or at the edge of the door opening and the latch pawl is in the latch itself which is mounted on the door requires that a separate actuator be provided in order to have power-assisted opening of the latch in addition to power-assisted closing.
USPTO Backgrounds
USPTO Backgrounds