GB686549A - Improvements in or relating to plants for supplying conditioned air to an aircraft pressure cabin - Google Patents

Abstract

686,549. Ventilating aircraft. BRISTOL AEROPLANE CO.. Ltd. Dec. 15. 1950 [Dec. 23, 1949], No. 33011/49. Class 137 A pressurized aircraft cabin is supplied with air at the desired temperature, pressure and humidity by a plant comprising a compressor delivering the air to the cabin through a refrigerator unit which includes a cooler of the heat exchanger type, this cooler being so connected that the air can be passed through the unit including its cooler or through the cooler only when the degree of cooling required can be met in this way. In the apparatus shown, the refrigerator unit comprises a cooler and a compressor-turbine expander device. Air for the cabin 1 enters the plant through an opening 19 in the leading edge of the aircraft wing and passes first through a heater 21 which is heated by air passing through a duct 24 around the main engine 7 of the aircraft and through an opening 23, the flow being controlled by a valve 26, the position of which is determined by the cabin temperature, a variable datum thermostat 53 being mounted in the cabin to provide this control. The air passes from the heater 21 into a compressor 6 which is driven by the engine 7 through a variable speed gear 8 controlled by a " neutralengaged " actuator 9, which is remotely operated by a switch 11 in the cabin, and by a ratio selector 10 operated by a switch 13 which is opened or closed by the movement of a capsule 114 in response to changes in altitude, so that the compressor is speeded up as the altitude increases and vice versa. The air flow through the compressor is controlled by a device 14 which actuates an inlet throttle 15 according to delivery pressure and velocity. Such a device is described in Specification 686,547. The air from compressor 6 then passes through a duct 35 to a cooler 28 which is cooled, when the aircraft is in flight, by ram air entering through an opening 19<SP>1</SP> under the control of valve flaps 30, which are moved under the control of the thermostat 53. When the aircraft is grounded, the combustion air for the engine 7 can be sucked through the coooler. If sufficient cooling can be obtained by the use of cooler 28 alone, the air therefrom passes directly through a duct 36 and water separator 37, which is provided with a byepass, the valve 40 of which is under the control of a cabin humidostat 42, through a silencer 38 and non-return valve 2 to the cabin distributer duct 3, the used air escaping from the cabin through a valve 4 controlled by a device 5, which regulates the cabin pressure at the desired value. If more cooling is required, the thermostat 53 causes valves 43 and 44 in the cooler supply and discharge ducts to close. Air then passes through a duct 45 into a compressor 47, through the cooler 28 and a turbine expander 48 which provides the additional cooling to the water separator and cabin, the compressor and turbine being coupled by a shaft 49 in the usual way. Under these conditions the degree of cooling is thermostatically controlled by a valve 51 in a refrigerator by-pass duct 50.