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Knock sensing apparatus with fail indicator for use in an internal combustion engine

  • US 4,418,567 A
  • Filed: 10/09/1980
  • Issued: 12/06/1983
  • Est. Priority Date: 10/19/1979
  • Status: Expired due to Term
First Claim
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1. Apparatus for furnishing a knock signal indicative of knocking in an internal combustion engine comprisingsensing means (1;

  • 43, 44, 45,

         38) for sensing mechanical oscillations in the internal combustion engine and furnishing sensing output signals corresponding thereto, said sensing output signals constituting said knock signal in the presence of engine knocking;

    control circuit means (12) for generatinga first gating signal defining a measuring phase (22) during which the sensing output signals are measured for presence of said knock signal, anda second gating signal defining a test phase (23) during which the sensing output signals are measured to determine proper operation of the sensing means and generating "fail" signals if said measurement determines improper operation of the sensing means,includingcomparator means (4,

         9) for comparing, during said test phase, said sensing output signals to(a) a first reference signal indicative of a predetermined minimum level, and(b) to a second reference signal indicative of a predetermined maximum level, andswitch means (3,

         5) controlled by said gating signals and connecting, during said test phase, the sensing output signals to the comparator means.

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