Patent GB-428426-A (GB)
Abstract: 428,426. Regulating oompressors. SPERRY GYROSCOPE CO., Inc., Manhattan Bridge Plaza, Brooklyn, New York, U.S.A.- (Assignees of Carlson, B. G.) July 31, 1934, Nos. 22337 and 22338. Convention dates, Aug. 26, 1933 and March 21, 1934. [Class 8 (i)] [See also Group XXIX] A pressure-regulating device for use in a system for supplying air to air-driven instruments such as gyroscope indicators employed on aircraft, comprises a hollow casing having a number of outlets adapted to be connected respectively to a source of air pressure, and to one or more instruments, and a valve device responsive to variations in the pressure-difference between the inside and the outside of the casing and adapted to prevent the pressure-difference at the instrument outlets from exceeding a predetermined amount, the valve device being located between the instrument outlets and the outlet to the source of pressure. In one form, Fig. 3, outlets 17, 20, 23, 26, which may be of different sizes, are provided in the casing 3 for connection to the various instruments, and an outlet 2 is connected to the source of pressure which may be a pump or the intake side of an aircraft engine. A piston 29 subject to atmospheric pressure on its outer face and to the pump pressure and the pressure of a spring 33 on the other face moves across an opening 15 when the difference of pressure exceeds a predetermined amount to prevent the pressuredifference at the outlets 17, 20, 23, 26 from exceeding a certain amount. A spring-pressed valve 6 situated between the outlet 2 and the opening 15 prevents damage to the instruments due to backfiring, and also can have its opening movement adjusted by a set-screw 10 so that its throttling action can be varied for adjusting the operating conditions of the device for various altitudes. In order that the spring pressure on the piston 29 can be caused to increase in a greater proportion than the movement of the piston, three springs 33, 34 and 35 of increasing stiffness are employed. A passage 12 in the casing 3 is connected by a pipe 13 to a vacuum gauge so that the true vacuum created by the pump or engine intake is indicated. A small hole 37 allows air to be supplied to the instruments when the aircraft is on the ground and the suction of the engine is sufficient to cause the opening 15 to be closed. Alternatively, an adjustable pin which prevents sufficient movement of the piston 29 to close the opening 15 completely may be provided. In another construction, Fig. 6, a substantially circular casing 106 is provided and has an outlet 107 to the pump and outlets such as 109 to the instruments to be operated. A diaphragm 111 divides the casing into two chambers 113, 114 which are connected by a small hole 124 leading from the pipe 107. Carried on the diaphragm is a valve 115 pressed downwardly by a spring 117 adjusted by a screwed spindle 119 so that normally it closes an opening 122 to the atmosphere. If the pressure in the casing drops below a certain amount, the valve 115 will lift due to the differential action of the air in the casing on the diaphragm and admit atmospheric air so as to keep the pressure difference at the outlets 109 from falling below a certain amount.