Control of an internal combustion engine with reference to a combustion chamber sensor

Claim 1

Corrective monitoring system for an internal combustion engine, comprising: a first sensor (20) in a combustion chamber of said engine for producing an electrical signal indicative of the extent of combustion in said chamber; a second sensor responsive to the passage of a reference mark on a rotary part of said engine for producing electrical reference mark signals synchronized with engine shaft revolution; means for deriving first and second timing gate signals (A,B) from said reference mark signal respectively designating successive time intervals which are fixed in time with reference to said reference mark signal; first threshold switch means (27) arranged to be connected to the output of said first sensor during the presence of said first timing gate signal (A) for comparing the signal of said first sensor with a first reference signal value; second threshold switch means (28) arranged to be connected to the output of said first sensor during the presence of said second timing gate signal (B) for comparing the signal of said first sensor to a second reference signal value, and logic circuit means connected to the respective outputs of said first and second threshold switch means for recognizing normal combustion, slow combustion and lack of combustion in engine cycles respectively beginning with individual reference mark signals, and having outputs connected to a control device of said engine for modifying engine operating conditions according to whether normal combustion, slow combustion or combustion failure is recognized by said logic circuit means, said logic circuit means being so constituted as to recognize a slow combustion condition when said second threshold switch means responds to a signal of said first sensor reaching said second reference signal value and to recognize a failure of combustion when neither said first threshold switch means nor said second threshold switch means response to a rise of said signal of said sensor reaching respectively said first and said second reference signal values.