A Fluid Servo Control Device

摘要

1,150,599. Gas turbine engine fuel systems. BENDIX CORP. Dec. 5, 1966 [Dec.13, 1965], No. 54349/66. Heading F1G. [Also in Division G3] A fluid-pressure servomotor system for actuating the fuel valve of a gas turbine engine, comprises proportional and integrating mechanisms actuating the controllable member in response to an error input signal and means responsive to at least one condition of operation of the engine to vary the respective gains of the mechanisms. In the preferred embodiment, the position of a piston 66 having a restricted by-pass 78 is connected to the fuel metering valve and follows the movement of a valve 84 resting on a lever 102 actuated both by a piston 108 forming the output member of the integrating mechanism and by further levers 114 and 124 forming part of the proportional mechanism. A valve 156 controls the supply of fluid to the piston 108 and is connected together with the lever 124 to a stem 148 which may be shifted through a lever 196 and a cam mechanism 192 by a speed request signal from a throttle lever 60 and through a cam mechanism 194 by an engine speed signal from a servomotor 96 which moves the cam axially. A servomotor 98 rotates the cam to compensate for the effect of engine temperature. A speed anticipation signal, provided by axial movement of a piston 134, causes expansion of a bellows 130 connected to the lever 124. A servomotor 234 rotates the valve 156 to vary the rate of flow for a given valve displacement and thus the gain of the integrating mechanism while a servomotor 256 shifts a fulcrum 116 for the lever 114 to vary the gain of the proportional mechanism. Both servomotors are responsive to compressor discharge pressure. When the throttle 60 is rotated to change speed, the lever 102 allows a follower 86 to be pushed by a spring 92 into engagement with an acceleration cam 88. This determines the position of the valve 84 and hence of the piston 66 while the valve 156 causes the piston 108 to move at a rate dependent on the position of the servomotor 234. As the engine approaches the selected speed, the servomotor 96 causes the cam 194 to act through a follower 204 and the lever 196 to lift the stem 148 returning the valve 156 to its null position and the follower 86 to a position clear of the cam 88.