Patent ID: 7310575

Claim:
A knock sensor signal processing apparatus for operating on a knock sensor signal that is produced from a knock sensor of a internal combustion engine having a plurality of cylinders, to perform filter processing of said knock sensor signal and detect occurrence of knocking in a cylinder based on results of said filter processing, comprising an A/D (analog-to-digital) converter, an A/D converter control circuit for controlling said A/D converter to convert said knock sensor signal to successive A/D values at fixed periodic intervals, compensation value calculation means for performing a compensation coefficient updating operation of controlling said A/D converter to convert a DC reference voltage having a known voltage level to a corresponding A/D value and calculating a compensation coefficient based on said A/D value, compensation means for utilizing said compensation coefficient to apply compensation to each of said A/D values of said knock sensor signal, to obtain successive compensated A/D values, and a digital filter for performing filter processing of said successive compensated A/D values; wherein; said A/D converter control circuit is adapted to control said A/D converter to perform said A/D conversions of said knock sensor signal at predetermined periodic intervals during each of respective knock judgement intervals for respective cylinders, and said compensation value calculation means is adapted to perform said compensation coefficient updating operation during an interval between a termination of said successive knock sensor signal A/D conversions within a first one of said knock judgement intervals and a commencement of said successive knock sensor signal A/D values conversions within an immediately succeeding one of said knock judgement intervals, with a compensation coefficient obtained by said updating operation being applied in compensating said knock sensor signal A/D values derived in said succeeding knock judgement interval.