Drive mechanism for a down draft vent system

Abstract

The invention relates to a drive mechanism for a down draft vent system (8) comprising a retractable down draft vent screen (10) which can be moved between an extended and a retracted position by means of a drive motor (3). The drive mechanism (1) is characterised in that the drive motor (3) is a synchronous motor with a reversing circuit (31, 32, 7) for load-dependent reversal of the driving direction. The present invention can thus provide a safety function against jamming of objects since the drive motor (3) reverses automatically when the load is fairly large.

Description

The present invention is explained again hereinafter with reference to the appended drawings.

In the figures:

FIG. 1: is a schematic circuit diagram of an embodiment of the drive mechanism according to the invention;

FIG. 2: is a schematic functional diagram of an embodiment of the down draft vent system;

FIGS. 3 a and 3b: show a schematic perspective view of a down draft vent system with a drive mechanism according to the invention and a detailed view of the drive mechanism; and

FIG. 4: is a view from below of a down draft vent system with a drive mechanism according to the invention.

Claims

1-10. (canceled)

11. A drive mechanism for a down draft vent system, the down draft system having a retractable down draft vent screen movable between an extended position and a retracted position by means of a drive motor, the drive mechanism comprising: a synchronous drive motor for driving movement of a retractable down draft vent screen between an extended position and a retracted position, the synchronous motor including a reversing circuit for load-dependent reversal of the driving direction of the retractable down draft vent screen.

12. The drive mechanism according to claim 11, wherein the synchronous drive motor includes two pairs of windings connected in parallel and at least one interrupt element in the supply line to the two pairs of windings.

13. The drive mechanism according to claim 12, wherein the interrupt element is a capacitor.

14. The drive mechanism according to claim 11, wherein the synchronous drive motor is an AC motor.

15. The drive mechanism according to claim 11 and further comprising at least one actuating element, the at least one actuating element being operable to transmit a driving force from the synchronous drive motor to thereby effectuate driving movement of the down draft vent screen and the at least one actuating element is spring-mounted in at least one direction of movement of the down draft vent screen.

16. The drive mechanism according to claim 15, wherein the actuating element is fixed to the down draft vent screen by means of at least one spring.

17. The drive mechanism according to claim 11, wherein the down draft vent screen is horizontally aligned and the synchronous drive motor is operable to drive the retractable down draft vent screen horizontally between its extended position and its retracted position.

18. The drive mechanism according to claim 15 and further comprising two interrupt switches actuated by means of the at least one actuating element.

19. The drive mechanism according to claim 18, wherein the interrupt switches are fixed to the component of the down draft vent system on which the at least one actuating element is spring-mounted.

20. The drive mechanism according to claim 19, wherein the at least one actuating elements has inclined planes at its ends and a recess and the at least one of the interrupt switches engages in the recess on the at least one actuating elements.