| 摘要 |
451,531. Door operating appliances. PETERS & CO., Ltd.. G. D., and CARDWELL, C. H., Windsor Works, Slough, Buckinghamshire. June 5, 1935, No. 16407. [Class 65 (i)] [See also Group XXVIII] In a double-acting pneumatic or vacuum engine for the operation of doors and the like, provided with means to cushion the motion by restricting the flow of air in a passage communicating with the cylinder, the cushioning means is actuated by means adjustable externally of the engine to vary the point in the piston stroke at which the cushioning becomes effective. The cushioning and control means for an electromagnetically-controlled vacuum engine are shown ; pipes 21, 22 connect the valves to the ends of the cylinders, passage 23 is connected to the vacuum source, and passages 25, 26 are connected to the atmosphere through needle valves (not shown) and valves such as 31 operated by cams such as 39 adjustably fixed on the rockshaft 4 by which the pistons are connected to the doors. In the position shown, with electromagnets 5, 6 de-energized, the pistons are at the left-hand end of their stroke, the vacuum passage 23 being connected to 21 by valve 11 and cut off from 22 by valve 13 while air is cut off from 21 at 11 and supplied to 22 through valve 12. When the electromagnets are energized, both valve elements are depressed, so that 22 is connected to vacuum (23) through valve 13 and 21 is connected to atmospheric passage 25 through valve 11, air entering 25 both through the needle valve and through valve 31 ; after a portion of the stroke, predetermined by the adjustment of cam 39 on rockshaft 4, this cam closes valve 31 so that air can only enter through the needle valve, which gives a restricted passage, and the movement of the engine is consequently slowed down. In the opposite movement, the valve (corresponding to 31) connected to passage 26 is closed after a time to restrict the flow of air to passage 22. In the case of engines in which the piston-rod is directly connected to the doors without the intermediary of any rotary member, the valves 31 are operated by sliding cams adjustably connected to the driving mechanism. In a compressed-air engine, the cam-operated valves may restrict either the entry of pressure air or the exhaust to the atmosphere. In a differential vacuum engine, the cushioning valves mould operate to restrict at appropriate times the connections of the vacuum source to the cylinders to allow pressure to build up in the appropriate cylinder to slow down motion. One of the electromagnets may also act as a relay, operating contacts 17, as described in Specification 438,620. Specification 442,742 also is referred to. |
