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Idling rpm feedback control method having fail-safe function for abnormalities in the functioning of the throttle valve opening detecting means of an internal combustion engine

  • US 4,491,109 A
  • Filed: 04/27/1983
  • Issued: 01/01/1985
  • Est. Priority Date: 05/07/1982
  • Status: Expired due to Term
First Claim
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1. An idling rpm feedback control method adapted to control a supplementary air quantity control means for regulating the quantity of supplementary air being supplied to an internal combustion engine having an intake passage and a throttle valve arranged therein, with means for detecting the throttle valve opening, in a feedback manner responsive to the difference between actual engine rpm and desired idling rpm, when at least one predetermined operating parameter of said engine including at least the opening value of said throttle valve satisfies a predetermined idle operating condition of the engine, the method comprising the steps of:

  • (1) setting beforehand an abnormal value of an output signal indicative of said opening value of said throttle valve from said throttle valve opening detecting means, said abnormal value having a value which is not yielded when said throttle valve opening detecting means is operating in a normal operating condition irrespective of an actual opening value of said throttle valve;

    (2) determining whether or not said output signal indicative of said opening value of said throttle valve has said abnormal value; and

    (3) supplying a maximum quantity of supplementary air to said engine by operating said supplementary air quantity control means to an operating limit thereof, when it is determined in said step (2) that said output signal indicative of said opening value of said throttle valve has said abnormal value, said maximum quantity of supplementary air being set at a value which makes it possible for the engine to sustain operation thereof even if the engine is subjected to a maximum load thereon that can be applied to the engine at idling.

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