| 摘要 |
756,227. Automatic fuel control systems. UNITED AIRCRAFT CORPORATION. Dec. 4, 1953 [Dec. 6, 1952], No. 33766/53. Drawings to Specification. Class 38 (4). Provision is made to ensure that a desired operating signal is produced upon failure of an electric amplifier, e.g. in a system for automatically controlling a turbine jet engine as in Specification 751,007 in which signals from a tachometer generator and from thermocouples responsive to tailpipe temperature are normally applied to a crossover network involving biased rectifiers so that either speed or tailpipe temperature is maintained constant by automatic control of the fuel.supply to the jet engine, which variable is selected by the crossover network to be maintained constant is determined by which signal is calling for the greatest reduction of fuel or which is calling for the least increase of fuel. A thermionic valve amplifier having synchronously chopped input and output which amplifies the D.C. output of the thermocouples is provided with negative feed-back which is delayed by a resistancecapacity network to counteract lag in the thermocouple response. The output impedance of this amplifier is arranged to form with a larger external resistance a potential divider across a source of negative voltage, the effect on the output of the amplifier normally being negligible but on failure of the amplifier, the consequent rise in output impedance produces a substantial negative signal which, being applied to the crossover network, permits a negative underspeed signal to increase fuel supply. Specifications 656,208 and 751,003, [Group XXVI], also are referred to. |
