GB812912A - Enclosure pressure control mechanism - Google Patents

Abstract

812,912. Fluid-pressure servomotor control systems. NORMALAIR Ltd. Dec. 9, 1955 [Dec. 31, 1954], No. 37833/54. Class 135. Mechanism for controlling the pressure in a pressurized enclosure such as an aircraft cabin comprises a discharge valve d subject to the control of a pressure control apparatus a which has a direct connection through a pipe b and a restriction (not shown) with the pressure source, the valve d having a connection through a bell-crank lever n pivoted at o with a high pressure or demand valve i also connected to the pressure source. The enclosure or cabin pressure enters the housing of the apparatus at h and acts on the exterior of a bellows k secured to the valve d and also in the interior of a bellows g by way of apertures m in the valve i so that the latter is balanced. The apparatus is suitable for use with cabin pressurizing systems in which the pressurizing air is derived from the discharge from other apparatus such as a pilot's pressurized suit &c. If the flow of compressed air to the cabin is adequate to maintain the pressure called for by the apparatus a, the bellows k will be compressed by the cabin pressure and the valve d will open as necessary to limit the pressure in the cabin, but in the event of the flow to the cabin being insufficient the valve D closes and the bell-crank lever n is operated by the bellows k to open the demand valve i to admit air under pressure directly to the cabin. The apparatus is also provided with a hinged, inwardly-opening release valve e and an outwardly opening safety valve f. The demand valve i may, alternatively, be servooperated or remotely controlled by electrical, pneumatic, hydraulic or mechanical means and may be of the tilting, spring-operated, or pistonoperated type. Also, the apparatus a may form part of the discharge valve unit.