PREIGNITION DETECTOR FOR SPARK IGNITION ENGINE

摘要

PURPOSE:To perform accurate detection by removing a light noise by spark discharge, by providing an optical filter which permits only light having longer wavelength than near-infrared rays have to pass through it selectively. CONSTITUTION:Light generated in a combustion chamber is guided by a flash detection part 101 and its wavelength is selected by an optical filter 107. With wavelength characteristics of transmittivity of the filter 107, light of <=6,500Angstrom is occluded and light by spark discharge is cut to detect only a flash-signal by combustion. Combustion light from the optical guide part 102 of a detector 10 enters a photoelectric converter 18, where it is converted into a voltage signal. On the basis of an upper dead point signal from a crank angle detector 16, a preignition discriminating circuit 20 discriminates the occurrence of preignition from a time difference berween an ignition point signal from a gamma-time delay ignitor 15 and the signal of the photoelectric converter 18.