Patent ID: 7688073

Claim:
A diagnosis device of a capacitor discharge ignition device for an engine that diagnoses the capacitor discharge ignition device for an engine comprising: an ignition power supply portion that repeatedly outputs a capacitor charging voltage of a pulse waveform; an ignition coil; an ignition capacitor connected in series with a primary coil of said ignition coil and charged with an output voltage of said ignition power supply portion through said primary coil; a discharge switch that conducts when receiving an ignition signal and discharges charges accumulated in said ignition capacitor through the primary coil of said ignition coil; and an ignition position control portion that provides an ignition signal to said discharge switch at an ignition position of the engine, said capacitor discharge ignition device for an engine inducing a high voltage for ignition in a secondary coil of said ignition coil by the discharge of the charges accumulated in said ignition capacitor, wherein said diagnosis device comprising: singularity detection means for detecting, as a singularity, a leading edge or a trailing edge of a voltage between output terminals of said ignition power supply portion; singularity counting means for counting the number of singularities detected by said singularity detection means while a crankshaft rotates through a measurement section, which is a section of a certain crank angle determined with reference to a pulse signal obtained by a signal generator that generates a pulse signal at a specific crank angle position of said engine; and diagnosis means for diagnosing an abnormality of said ignition device and a cause of the abnormality by comparing the number of singularities counted by said singularity counting means with the number of times of normal ignition of the engine performed while said crankshaft rotates through said measurement section.