| 摘要 |
The device has at least one flap which is mounted pivotably over a ventilation opening which is to be closed. This flap can be actuated by a pneumatic-spring arrangement (1) which has a cylinder (10) filled with compressed gas, a piston (15) which is movable in this cylinder (10) and a piston rod (16) connected to the piston (15). In order to tension or release the pneumatic-spring arrangement (1) without subjecting the flap to additional twisting forces, a further piston (5) is provided, which is movable in a further cylinder (2). An inlet (7', 9) for the supply of compressed air opens into the further cylinder (2). The first-mentioned cylinder is connected to the further piston (5) or the further cylinder (2) while the first-mentioned piston (15) is connected to the further cylinder (2) or the further piston, the whole in such a manner that the pneumatic-spring arrangement (1) can, under the action of said compressed air, be extended from a retracted position, in which the flap is closed, into an extended position, in which the flap is open. As a result, there is a greater opening force which remains practically constant over the opening travel. <IMAGE> |
