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Failsafe electronic control systems

  • US 4,718,229 A
  • Filed: 09/30/1986
  • Issued: 01/12/1988
  • Est. Priority Date: 10/30/1985
  • Status: Expired due to Term
First Claim
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1. A fuel control system for a gas turbine aeroengine, including:

  • (a) means for sensing the rotational speed of the engine and producing a speed signal representative thereof,(b) fuel flow metering means for metering the fuel flow to the engine,(c) first, electronic, control means operative in conjunction with the fuel flow metering means to exercise a first and normal control mode over fuel flow to the engine, and(d) second, electronic, control means operative in conjunction with the fuel flow metering means to exercise a second and speed limiting control mode over fuel flow to the engine in response to said speed signal, the arrangement being such that the second control means takes over control of fuel flow from the first control means whenever the speed signal exceeds a predetermined value indicating overspeed and retains such control until the speed signal falls below the predetermined value;

    wherein the fuel control system is adapted to prevent overspeed of the engine due to failure of electronic components when the fuel control system is subjected to higher than normal operating temperatures, the control system further including means for sensing the temperature of the control system and producing a temperature signal representative thereof, and third control means operative to exercise a third and speed limiting failsafe control mode over fuel flow to the engine in response to said temperature signal, the third control means being adapted to irreversibly take over control of fuel flow from the first and second control means if the temperature of the control system exceeds a predetermined value indicative of likely failure of the first and second control means.

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