GB646287A - Improvements in or relating to valve devices for maintaining a constant pressure inside a closed space more particularly in the cabin of an aircraft - Google Patents

Abstract

646,287. Regulating cabin pressure. SOC. NATIONALE DE CONSTRUCTIONS AERONAUTIQUES DU SUD-OUEST. June 5, 1947, Nos. 14925 and 14926. Convention dates, Oct. 26, 1943, and Feb. 16, 1944. [Class 4] [Also in Group XXIX] The pressure in an aircraft cabin 1, Fig. 2, supplied with air by a supercharger, is maintained constant by means of an outlet valve, shown as a balanced double-beat valve 19, which is actuated by a piston 10 closing one end of an auxiliary control chamber 12, the latter being provided with a leak port, and the pressure of the air therein being controlled by a pilot valve loaded by a bellows containing air under a predetermined pressure. Air from the cabin leaks into chamber 12 through a bleed 13 or past the piston. 10, and a constant pressure is maintained in the auxiliary chamber by means of a relief valve 14, the latter being spring- loaded and carried by a bellows containing air under pressure. Valve 19 is also loaded by a light spring 21. The cylinder in which piston 10 operates may be separate from, but in communication with, chamber 12, and a cock may be provided to allow compressed air to flow into the system to close valve 19 positively. The latter may be constituted by a sleeve sliding over a tubular seat provided with a triangular port or a straight or helical row of ports. In a modification, the outlet valve 16, Fig. 10, is actuated by a leaky piston 10 controlled by an auxiliary chamber 12 with relief valve 14. The top of tubular valve 16 is, however, covered in and provided with a valve 30 which, during normal operation, is opened by the pressure in the cabin 1. Should the pressure in the cabin fall too low, valve 30 will close, the air then entrapped in the chamber 31 will leak away to outside atmosphere through the space between valve 16 and its seat, and the pressure in chamber 12, combined with the weight of the valve &c., will close valve 16 against a packing strip 28. In a further modification, the control chamber constituted by chamber 12, Fig. 11, conduit 32, and space 12a, is normally at the pressure of the outside air due to the leakage past piston 35 and out through openings 38, and, under these conditions, the weight of the piston and the outlet valve 33 will lower the latter on to its seat. As soon as the pressure in cabin 1 rises sufficiently to overcome the force due to spring 5 and the pressure of air in capsule 6, valve 3 will open and air at cabin pressure will flow into space 12a to lift the latter and open valve 33.