GB1083573A - Air conditioning apparatus for aircraft - Google Patents

Abstract

1,083,573. Fluid-pressure servomotor systems. BRISTOL SIDDELEY ENGINES Ltd. March 11, 1964 [March 12, 1963; June 20, 1963], Nos. 9793/63 and 24625/63. Heading G3P. [Also in Divisions B1 and F4] An air flow shut off and control valve assembly in the air conditioning system of an aircraft (see Division F4) comprises a shut off valve and a control valve in series in a casing 24 through which pressurized fresh air passes from the left as seen in Fig. 4. A shut off valve member 65 is connected to a piston 66 biased towards the open position by a spring 67 and towards the closed position by the connection of a chamber 68 through openings 69 and 70 with the pressurized air stream. The chamber 71 on the other side of the piston communicates through an opening 72 with the chamber 68. The valve is then open unless a relief passage 73 leading from the chamber 71 is opened by either of valves 73A or 73B (Fig. 5). The valve 73A is opened by energization of a solenoid 73C. The valve 73B is connected to a member 95 forming one end of a bellows diaphragm 96 acted on by a spring 100 and by the pressure in two chambers 98 and 99. The chambers are connected by passages 101 and 102 with the fresh air supply upstream of the shut off valve so that normally the valve 73B is maintained closed by the spring 100. Pressure may be relieved in the passage 101 to open the valve 73B by either of two valves 104 and 105. The valve 104 is opened by an excess temperature device in the conditioned air supply line to the aircraft cabin and the valve 105 is opened by a bellows 41 if the pressure in the conditioned air line exceeds a given value. The member 95 has a stem 106 sliding in a guide 107 provided with apertures locating latching balls 108 which cooperate with a notch 109 in the stem to hold valve 73B open when it has been opened. When the balls enter the notch they release a sleeve 109A which moves under the action of a spring 110 to lock the balls in the notch. To reset the valve 73B a solenoid 111 is energized to move the sleeve back to its original position and to simultaneously operate a valve 113 to relieve pressure in the chamber 99. The control valve of the assembly is controlled from a Venturi 32 in the conditioned air line and comprises a sleeve valve 73a having a piston working in a cylinder 76. Connections 36A and 36B with the Venturi are connected to either side of a diaphragm 89 connected to a relief valve 88 to control the pressure in a bellows 82A thus varying the compression of a spring 83 and the pressure at which a relief valve 81 opens. The datum pressure may be changed by energizing a solenoid 92 to compress a spring 91 acting on the diaphragm 89. Alternatively the arrangement may be such that de-energization of the solenoid produces the higher datum pressure. The solenoid 92 may be arranged to operate if the fresh air flow rate falls below a given value.