Patent ID: 7949457

Claim:
A control apparatus for an internal combustion engine, comprising: a crankshaft provided in the internal combustion engine; a crank angle detection unit that is provided in the internal combustion engine and that outputs a crank signal each time the crankshaft rotates by a predetermined angle; a generator that rotates in synchronization with the rotation of the crankshaft and that outputs alternating voltage signals with one-phase; and a control unit, to which the alternating voltage signals are input, that ascertains ignition timings based on the crank signals, performs ignition control so as to spark the internal combustion engine at the ignition timings, performs polarity determination processing in which the control unit determines a polarity of the alternating voltage signal each predetermined cycle and determines a current polarity determination result when the polarities are identical over predetermined times, and performs reverse rotation detection processing in which the control unit obtains the current polarity determination result each time the crank signal is detected so that the control unit ascertains a polarity cycle of the alternating voltage signals and in which the control unit determines that the crankshaft is in reverse rotation and stops the ignition control when the ignition timing has arrived and the polarity cycle does not coincide with a polarity cycle at the time the crankshaft is in forward rotation.