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Fuel injector failure detection circuit

  • US 5,469,825 A
  • Filed: 09/19/1994
  • Issued: 11/28/1995
  • Est. Priority Date: 09/19/1994
  • Status: Expired due to Term
First Claim
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1. An injector failure detection circuit including at least one injector having a high side and a low side terminal, the circuit comprising:

  • a one shot timer for transmitting a constant voltage state signal output when the injector reaches a set current threshold at a start of an injector current peak time duration;

    a voltage sense comparator for transmitting a low voltage state signal output when the low side terminal of the injector produces a fly-back voltage pulse;

    means for monitoring current of the injector during a rise time duration and the peak time duration, the current monitoring means in communication with the one shot timer;

    means for disconnecting all electrical power supplied to the at least one injector if the injector current fails to reach a peak level during the rise time duration or the fly-back voltage pulse fails to occur at the end of the peak time duration, the disconnection means in communication with the one shot timer and the voltage sense comparator; and

    means for monitoring the fly-back voltage pulse produced by the low side terminal of the injector, the fly-back voltage monitoring means in communication with the injector.

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