| 摘要 |
A casement ventilator of the type having gas springs (10) connected between a fixed frame (11) and a movable panel (12) hinged thereon to effect opening of the ventilator, pneumatic units (14) also connected between the fixed frame and the movable panel to effect closing of the ventilator, and a latch (15) to lock the ventilator closed urged into automatic locking position by the piston (17) of an air cylinder (18) against the urge of a mechanical spring (19) that serves for releasing the latch and opening of the ventilator when air from a power line (20) to the air cylinder (18) is cut off in response to a signal from a fire alarm and/or a building management system and/or other control system (21), characterized in that the pneumatic units (14) are double-acting, so as to be able to assist the gas springs (10) in the initial opening of the ventilator, and in that an air receiver (22) is charged through a non-return valve (23) from the power line upon closing of the ventilator and provides air for the opening movement of the pneumatic units. Because the pneumatic units (14) assist the gas springs (10) to open the ventilator, including the load of double-glazing (32) of the panel (12) and any snow-plus-wind loading, the rating of the gas springs can be reduced (as compared within existing ventilators of the known kind) and the rating of the pneumatic units can also be reduced because they have to overcome only the lesser force of the gas springs to close the ventilator. Consequently, the diameter of the cylinders (31) of the pneumatic units (14) can be minimised and likewise the size of the fixed frame (11) (in which they are housed), with, therefore, maximising of the effective ventilation area. Because the pneumatic units are required to assist only initial opening of the ventilator, the air receiver (22) does not need to be of large capacity, so it can have such a diameter that it can be accommodated within the fixed frame. |
