Patent GB-762035-A (GB)
Title: Device for controlling balanced air-discharge valves, intended for controlling pressure variations in an enclosed space, more especially in an aircraft cabin
IPC: B64D13/04
Filed: 1954-06-24
Abstract: 762,035. Fluid-pressure servomotor-control systems. SOC. NATIONALE DE CONSTRUCTIONS AERONAUTIQUES DU SUD-OUEST. June 24, 1954 [June 25, 1953], No. 18605/54. Class 135. A device for supplying a control pressure to one side of an actuator for a pressure-balanced outlet valve of a pressurized enclosure such as an aircraft cabin, the other side of the actuator being exposed to enclosure pressure, is arranged to give a controlled rate of change of enclosure pressure until a selected pressure is reached and thereafter to maintain that pressure subject to a limitation of the differential between the controlled pressure and atmospheric pressure. A fluid-tight chamber 4, Fig. 2, is separated by two movable partitions 5, 5<SP>1</SP> from compartments 3, 31 in which the partitions control orifices 35, 35<SP>1</SP> for the flow of air from the enclosure to outlets 44, 44<SP>1</SP> incorporating restrictions 45, 451 and leading to atmosphere through a conduit 29, the compartments communicating with a third compartment 52 through means 48, 48<SP>1</SP>, 49 for adjusting the flow between them so that the pressure in the third compartment is intermediate that in the compartments 3, 3<SP>1</SP>, the third compartment communicating through a capillary tube 60 with the fluid-tight chamber 4, and the control pressure for the outlet valve (not shown) being tapped from one of the compartments 3, 3<SP>1</SP>, as shown, from the compartment 3, being passed through a conduit 61, valve 30 and conduit 8. The diaphragms 5, 51 actuate resilient blade valves 36, 36<SP>1</SP> coacting with the orifices 35, 35<SP>1</SP> and are adjustably loaded by springs 37, 40 and 37<SP>1</SP>, 40<SP>1</SP> so that the diaphragm 5 is in balance when the pressure in the compartment 3 is below that in the chamber 4 by a certain amount and the diaphragm 5<SP>1</SP> is in balance when the pressure in the compartment 3<SP>1</SP> is above that in the chamber 4 by the same amount. There is thus a flow from the compartment 3<SP>1</SP> to the compartment 3 through a conduit 47<SP>1</SP>, restrictions 48<SP>1</SP>, 48, adjustable restriction 49, and conduit 47. Ducts 51, 51<SP>1</SP> lead to the compartment 52 where they are controlled by closure members at each end of a rocking member 57 pivoted at 54 and connected at 55 with a barometric capsule 56 which is adjustably anchored by a helical cam 58. For a controlled decrease of pressure in the enclosure the capsule 56 is adjusted downwardly to close the duct 51<SP>1</SP> and open the duct 51. The pressure in the chamber 4, and consequently in the compartments 3, 3<SP>1</SP>, is thus gradually reduced due to flow through the capillary tube from the chamber 4 to the compartment 52, which is at the pressure of the duct 51, until the selected enclosure pressure is reached when expansion of the capsule 56 controls both ducts 51, 51<SP>1</SP> to maintain a constant pressure in the compartment 52. For increasing the enclosure pressure the bellows is initially adjusted upwardly to open the duct 51<SP>1</SP> and close the duct 51. The adjustment of the restriction 49 determines the rate of change of enclosure pressure. The valve 30 normally interconnects ports 62, 63, 64, the port 63 leading to a valve comprising a spring-loaded piston 66 or diaphragm, Fig. 12, subject, in opposition to the spring, to the control pressure transmitted to the actuator of the outlet valve and, assisting the spring, to atmospheric pressure. An excessive pressure differential causes movement of the piston or diaphragm to connect the port 63 with atmosphere to lower the control pressure. Other settings of the valve 30 isolate the conduit 8 from the port 62 or from both ports 62, 63 and connect it with a conduit 19 which is subject to enclosure pressure so that the outlet valve may be operated manually with or without the control by the valve 25. Also the valve may close the port 64 for checking the. fluid-tightness of the conduit 8 &c. A constructional form of the chamber 52 and its associated parts is shown in Figs. 8, 9 and consists of two blade valves 89, 89<SP>1</SP> coacting with orifices 53, 53<SP>1</SP> and actuated by the rocking member 57 which is pivoted on screws 90 on a support 91 and engaged by a pointed screw 55 by which the capsule 56 is fixed to a resilient blade 86. The lower part of the capsule is also fixed to a resilient blade 85 which has an extension 56a engaged by the adjusting means.