| 摘要 |
1,157,962. Ventilating aircraft. PLESSEY CO. Ltd. 28 Sept., 1966 [8 Oct., 1965], No. 42738/65. Heading F4V. [Also in Division F1] The invention relates to an air supply system in which air is tapped for example from two different points of a compressor of a gas turbine engine for use for aircraft cabin pressurization. The air tapped from one point of the compressor is at a pressure greater than the required air pressure and that tapped from the other point is at a pressure less than the required air pressure. The air at the higher pressure is passed to an air turbine while that at the lower pressure is supplied to an air compressor driven by the air turbine, the air discharging from the turbine and that discharging from the compressor being mixed and thence supplied to the point of use. In the embodiment shown a chamber 5 is provided and an assembly comprising a rotor 1 and shaft 2 is rotatably mounted therein. The rotor 1 comprises a centrifugal air compressor 3 and an air turbine 10. High pressure air tapped from the engine compressor is supplied through line 7 and passes by way of a control unit 8 through lines 13 to nozzles 9 which direct it on to the air turbine. Lower pressure air tapped from the engine compressor passes through duct 4 to the air compressor 3, the air delivered by the compressor and that discharged from the turbine mixing in the chamber 5 and then passing through line 6 to the point of use. The control system for the turbine comprises a piston 11 disposed in a cylinder 12 the axial position of the piston determining the number of lines 13 and hence turbine inlet nozzles 9 through which high pressure air may flow. The piston 11 is connected to a piston 14 disposed in a cylinder 15, the piston 14 being subject at its right-hand side to pressure of the high pressure air in line 7 so that the pistons 11 and 14 are pressure balanced. The rod connecting the pistons 11 and 14 is connected to a control piston 16 disposed within a cylinder 17, one side of the piston being subject to ambient pressure and the other side being subject to pressure within the chamber 5. The excess of chamber pressure over atmospheric pressure thus tends to move the piston 11 to the left against the loading of spring 18, so as to cut off the number of turbine nozzles 9, so that less air is tapped through the line 7 and the power of the turbine 10 is reduced. Thus the pressure within the chamber 5 and so the air supplied to the cabin is reduced. |
