GB475699A - Improvements in or relating to vacuum or compressed air systems for aircraft apparatus - Google Patents

Abstract

475,699. Fluid - actuated valves. BRONZAVIA SOC. ANON. Nov. 26, 1936, No. 32394. Convention date, Dec. 10, 1935. [Class 135] In a vacuum or compressed-air system for actuating one or more instruments, apparatus, or machines on an aircraft by virtue of the pressure difference between the system and the surrounding atmosphere, regulating means are provided to vary this pressure difference in accordance with the pressure of the surrounding air to ensure correct operation of the apparatus at high altitudes. In Fig. 1, various apparatus 2 are actuated by suction from a chamber 3 which is maintained at a desired vacuum by a pump or the like 4 working at a predetermined normal rate, the degree of vacuum being regulated by an air-admission device A which is shown more fully in Fig. 2 as a balanced valve 6 controlled by a barometric capsule 7. Thus, at high altitudes the capsule 7 expands and tends to close the valve 6 to provide an increased degree of vacuum in the chamber 3 for operation of the various apparatus. In the arrangement shown in Fig. 5, the vacuum in the chamber 3 is regulated independently of the rate of operation of the pump 4 by means of a diaphragm 11 carrying a valve seating 9 and moving against a spring 10 to regulate an air-admission opening between the seating 9 and a valve member 8, the position of which is regulated by a barometric capsule 12. This arrangement thus provides a constant pressure or vacuum regulation of the chamber 3 which is modified in accordance with the surrounding air pressure to give an increased pressure or degree of vacuum at higher altitudes.