Patent GB-1161954-A (GB)
Title: Control Apparatus for Equalizing an Engine Operating Condition of a Plurality of Engines
IPC: B64D31/12
Filed: 1967-12-13
Abstract: 1,161,954. Gas turbine power plant. BENDIX CORP. Dec. 13, 1967 [Dec. 21, 1966], No. 56697/67. Headings F1G, F1J and F1Q. [Also in Division G3] In an arrangement for co-ordinating the relative power outputs of two combustion engines each of which is controlled by a fuel control device which is responsive on the one hand to the position of the common engine control lever and on the other hand to a variable fluid-pressure for controlling fuel flow to the corresponding engine, each variable fluid-pressure is controlled by a control system in which two variable conditions representative of the output powers of the two engines are compared for the purpose of generating an output signal representative of the predominance of the variable condition corresponding to the output power of the engine controlled by the corresponding variable fluid-pressure, the output signal being adapted to modify the corresponding variable fluidpressure for reducing the fuel flow to the corresponding engine. Each gas turbine engine 20, 22, Fig. 1, comprises a turbine 30 driving a compressor 26, and a turbine 34 driving the load such as an aircraft propeller. The exhaust gases may be discharged to atmosphere through a nozzle 36. Power sensing devices 142, 146 each giving a fluid-pressure signal representative of the power output of the respective turbine 34 are connected via conduits 140, 144, 150, 152 to power comparing devices 72, 74 belonging to the engines 20, 22 respectively, whereby the power signal for each engine is applied to the bellows 90 of the corresponding device 72 or 74 while the power signal for the other engine is applied to the bellows 92 of that device. The bellows 90, 92 are connected to respective pivoted levers 102, 104, lever 102 carrying a valve member 108 pressed against a valve seat 109 by springs 122, 130. Identical fuel controls 46, 48 for the two engines are connected to a common speed control lever 56. As shown in Fig.2 for the fuel control 46, the lever 56 controls a cam 218 acting on a pivoted abutment 214 for a spring 212. Spring 212 and a further spring 220 act in opposition on a pivoted lever 208 carrying a valve member 206. A pivoted lever 196 carrying another valve member 194 is acted on by the other end of the spring 220 in opposition to governor weights 200 rotated by turbine 30 of engine 20. Governor weights 232 driven by turbine 34 of engine 20 act in opposition to a spring 240 on a pivoted lever 236 carrying a valve member 230. Air at the discharge pressure of the compressor 26 is conveyed via a conduit 70 and a variable restrictor 182 to a chamber 180 vented to atmosphere via a restrictor 185. The restrictor 182 is controlled by capsules 248 responsive to the temperature of, say, the atmosphere. Chamber 180 communicates with a chamber 188 via a restrictor 186 and with a chamber 178 via an adjustable restrictor 184. An evacuated bellows 172 within the chamber 178 is connected by a stem 170 to a bellows 174 which separates the chamber 188 from the chamber 178, the stem being connected by a lever 168 to a throttle valve 164 which controls the fuel supply to engine 20. The pressure drop across the throttle valve 164 is maintained constant by a by-pass valve 166. The governor-operated valve members 194 and 206, 230 control the venting of chambers 178 and 174 are varied in accoratmospheric pressure Pa, whereby the pressures acting on the bellows 172, 174 are varied in accordance with the speeds of the turbines 30, 34 so as to variably position the throttle 164. During acceleration, if, say engine 20 is accelerating faster than engine 22 so that its power exceeds that of engine 22, then the force exerted by bellows 90 of the power comparing device 72 exceeds that exerted by bellows 92 and causes the levers 102, 104 to pivot to move the valve member 108 away from its seat 109, thereby venting the chamber 188 to atmospheric pressure Pa via conduit 138, so that the opening of throttle valve 164 is reduced to limit the acceleration of engine 20 to that of engine 22. When the engines 20, 22 have reached a predetermined power, any further increase in the power of engine 20 causes lever 102 to move against the action of spring 122 to move the valve member 108 away from its seat 109 so that the opening of throttle valve 164 is reduced to limit the maximum power of engine 20.