| 摘要 |
PROBLEM TO BE SOLVED: To detect the presence or absence of misfires and knocking through ions near a spark plug with high precision. SOLUTION: A coil T2 applies a voltage to the center electrode of a spark plug P after the spark discharge thereof. When combustion has normally occurred in the cylinder to which the spark plug P is mounted, the voltage is gradually damped by ions generated at the combustion. On the basis of the damping characteristics, a misfire detector circuit 20 detects the presence or absence of misfires. When knocking has been caused at the combustion, the concentration of ions near the spark plug P fluctuates with the result that ionic currents are gradually damped while oscillating. The oscillation of ionic currents results in the oscillation of voltages to be applied to a third resistor R3. On the basis of the oscillation of voltages a knocking detector circuit 30 detects the knocking. |
