Adjustment mechanism and adjustment device comprising such adjustment mechanism

An adjustment mechanism for an adjustment device, the adjustment mechanism comprising:

• a main worm gear wheel held in an injection molded plastic housing for rotation relative to each other about a main axis of the main worm gear wheel, the main worm gear wheel being provided with a hollow central axial passage and the housing being provided with at least one opening that is axially aligned with the central axial passage to allow a shaft to extend via the opening through the housing into the central axial passage and to be in supporting engagement with the main worm gear wheel;
• and
• a main worm having at least one circumferential spiral tooth in intermeshing arrangement with teeth on the circumference of the main worm gear wheel, the main worm being held in the housing for rotation about a main axis of the main worm, and being arranged to be driven to rotation relative to the housing about the main axis of the main worm via a drive train powered by an electric motor held in the housing,
• wherein a number of stiffeners is provided between the housing and at least one of the main worm gear wheel and the main worm to lock the intermeshing arrangement of the teeth under torque that is applied between the main worm gear wheel and the housing external to the drive train, and
• wherein the at least some of the stiffeners include an intermediate gear set element held in the housing and included in the drivetrain between the electric motor that powers the drive train and the main worm gear wheel, the intermediate gear set element including a first gear on a side of the motor intermeshing with a second gear on a side of the main worm, the driving efficiency between the gears being less than 50% when the second gear drives the first gear so as to limit rotational movement of the main worm under torque that is applied between the main worm gear wheel and the housing external to the drive train.

An adjustment mechanism for an adjustment device, the adjustment mechanism comprising:

• a main worm gear wheel held in an injection molded plastic housing for rotation relative to each other about a main axis of the main worm gear wheel, the main worm gear wheel being provided with a hollow central axial passage and the housing being provided with at least one opening that is axially aligned with the central axial passage to allow a shaft to extend via the opening through the housing into the central axial passage and to be in supporting engagement with the main worm gear wheel;
• and
• a main worm having at least one circumferential spiral tooth in intermeshing arrangement with teeth on the circumference of the main worm gear wheel, the main worm being held in the housing for rotation about a main axis of the main worm, and being arranged to be driven to rotation relative to the housing about the main axis of the main worm via a drive train powered by an electric motor held in the housing,
• wherein a number of stiffeners is provided between the housing and at least one of the main worm gear wheel and the main worm to lock the intermeshing arrangement of the teeth under torque that is applied between the main worm gear wheel and the housing external to the drive train, and
• wherein the stiffeners comprise a strut that extends from one of a base of the housing or a cover of the housing, and that is held in the other of the base or the cover.