GB797025A - Air pressure regulating and shut-off valve - Google Patents

Abstract

797,025. Fluid-pressure servomotor-control systems. BENDIX AVIATION CORPORATION. Jan. 19, 1956 [March 24, 1955], No. 1883/56. Class 135. Energization of a solenoid valve 26 closes a branch line 25 from a main duct 2 to an outer bellows 28, the inner bellows 32 being both coupled to the latter and normally at atmospheric pressure, and vents the bellows conduit 27 whereupon they collapse and move a piston valve 21 to the right, thus opening the top of a cylinder 15 to atmosphere via a port 17 and admitting air from line 25 upstream of the valve 26 to the bottom of the cylinder through a port 19, so elevating a spring-loaded piston 8, which through a piston-rod 12 and linkage 9, 10, opens a butterfly valve 7 in the duct 2 and allows air to flow to a starter turbine 4. The cylinder 15 has a dashpot 20. As the pressure builds up it effects a leftward movement of the inner bellows 32, after traversing a line 35, until the piston valve 21 is returned to the position shown, closing both ports 17, 19; at the same time the piston spring 16, which normally keeps the butterfly valve closed, progressively returns the latter towards the closed position until the desired flow to the turbine is attained. If the pressure in the line increases beyond this value the bellows 32 moves the piston valve to the left of the neutral position, thus venting the lower part of the cylinder 15 and admitting pressure air to the top thereof, so forcing the piston 8 downwards and further closing the butterfly valve 7 to reduce the pressure of air supplied to the turbine. As the pressure in line 35 changes, the piston valve will oscillate over ports 17, 19 to regulate the air pressure supplied to the turbine. Should line 35 break, excessive air pressure downstream of the butterfly valve 7 will act over a line 36 to move a piston 37 against a spring 38 and supply the inner bellows 32 via a channel 39. Upon de-energizing the valve 26 the outer bellows 28, connected to line 25, moves the pilot valve to cause downward movement of the piston 8, so closing the butterfly valve.