GB754120A - Air conditioning, and auxiliary electric and pneumatic power supply equipment and system - Google Patents

Abstract

754,120. Gas turbine plant. GARRETT CORPORATION. May 5, 1953 [June 30, 1952], No. 12432/53. Class 110(3) [Also in Groups X, XXIX and XXXIV] The gas turbine 10 of the aircraft airconditioning plant described in Specification 754,189 [Group X] drives a compressor, the outlet of which is connected to a valve-controlled duct to provide one selectable source of combustion air to the gas turbine; another selectable source of combustion air being through another valvecontrolled duct from a separate source of compressed air. The fuel feed and combustion air control for the gas turbine 10, is shown in Fig. 2. The air supply conduit 14 leading to the combustion chamber 15 is controlled by a damper 81 which is positioned by the movements of a piston 85 caused by differences in oil-pressure in pipes 91, 92. The liquid fuel supply from the pipe 100 is regulated by a bleed-off valve 99 which is controlled by a spring-loaded diaphragm 102 according to the oil-pressure in the pipe 103. The turbine control is effected by apparatus responsive to speed and load variations, and to pressure or temperature variations of combustion air and combustion products. The speed and load apparatus is associated with a gear wheel 55 driven by a pinion 54 on the turbine shaft and driving a power take-off shaft 56 through a compression spring 57 which is arranged between a bar 58 on the wheel 55 and a crank arm 59 on the shaft 56. A cylinder 68 is secured to the wheel 55, the cylinder having an oil-bleed vent 69 which is covered to a greater or lesser extent by the bar 58, depending on the load on the shaft 56, the vent being closed more as the load increases. A head 64 carries a tubular shaft on which spaced discs or valves 62, 63 are mounted to control the passage of high pressure oil, which is supplied to the casing 61 between the valves 62, 63, to the pipe lines 91, 92 and to the spaces 79, 80, the valves being underlapped to permit .a slight flow past their peripheries. A piston 70 within the cylinder 68 has a hollow piston rod 71 which passes through the tubular shaft and carries a piston 72 which is responsive to difference in pressure on different sides of the piston as produced by the pressure drop through a restricted droop orifice 106 and a restricted speed orifice 108, a bleed valve 109 being provided to adjust speed changes and a bleed valve 110 for adjusting droop. The position taken by the piston 72 determines the pressure of a droop control spring 74 on the head 64 and participates in determining the position of the head and thus the valves 62, 63. The head is further acted upon by a spring 73 which acts in opposition to a weight 65 which is pivoted to the cylinder 68 at 67 and is connected to the head by a flexible strap 66. The weight, in accordance with speed changes, moves the head and contributes to the positioning of the valves 62, 63. Provision is made for stopping the turbine if there is overspeed, or reverse torque caused by a tendency of the shaft 56 to drive the turbine, or damage to bearings. This is effected by venting the pipe 90 causing the spring 89 to force the plunger 88 against the end of the rod 86 and thereby admitting pressure from the pipe 92 to the back of the plunger. This causes the damper 81 to close. The venting of the pipe 90 may be caused by bearing failure which would result in lack of resistance to oil flow along pipe 122; by opening of valve 75 centrifugally on overspeed, thus venting the space 79, or by opening the valve 75 by a cam-like member 78 on the shaft 56 in the event of overdrive. The oil pressure in the pipe 103 acts on diaphragm 102 and determines the setting of the bleed valve 99, the action of the oil pressure being modified by an element 112 sensitive to temperature and pressure of the combustion air which compounds the action of the spring 111 with the variable action of the spring 114. The combustion products act upon a temperature regulator 115 having a valve 116 which controls the bleed from an oil supply from the pipe 90, the pressure of which is determined by a restricted orifice 119. Thus a variable pressure, determined by temperature of combustion products, produces an action of the bellows 117 which further modifies the action of the spring 111 by being connected through the arm 120 and a tension spring 121 with the diaphragm.