Patent ID: 8056536
Filing Date: 2011-11-15
Classification: F02P

Abstract:
1. An ignition device for an internal combustion engine comprising: an exciter coil that is provided in an AC generator that rotates in synchronism with the internal combustion engine, and generates an AC voltage once for one rotation of a crankshaft of said internal combustion engine, the AC voltage having a half wave of a positive voltage and a half wave of first and second negative voltages generated before and after the half wave of the positive voltage; an ignition capacitor provided on a primary side of an ignition coil and charged to one polarity by said positive voltage; a discharge switch that conducts when receiving an ignition signal and discharges charges accumulated in said ignition capacitor through a primary coil of said ignition coil; a power supply circuit that charges a power supply capacitor with the first and second negative voltages of said exciter coil to generate a control DC voltage; and an ignition control portion that controls an ignition position of said internal combustion engine using a microprocessor that operates using the DC voltage output by said power supply circuit as a power supply voltage, wherein said ignition control portion comprises: counting operation start means for causing a timer to start a counting operation when an output of said power supply circuit is established and said microprocessor starts operation; negative voltage determination means for determining whether a negative voltage output by said exciter coil is a first negative voltage or a second negative voltage when the negative voltage is detected; and start time ignition control means for arithmetically operating time required for said internal combustion engine to rotate from a crank angle position where said second negative voltage is detected to an ignition position suitable at the start of said engine at a rotational speed calculated from time between detection of said first negative voltage and detection of the second negative voltage when said internal combustion engine is at the start, as ignition position detecting counting data, when said second negative voltage is detected, and controlling a generation position of said ignition signal so that the ignition position of said internal combustion engine is set in a crank angle position suitable at the start by immediately starting measurement of the arithmetically operated ignition position detecting counting data, said start time ignition control means is comprised so as to determine, when a negative voltage is initially detected after the commencement of a start operation of said internal combustion engine, whether said initially detected negative voltage is the first negative voltage or the second negative voltage, and when determining that the negative voltage is the second negative voltage, arithmetically operate said ignition position detecting counting data regarding a measurement value of said timer as the time between detection of said first negative voltage and detection of the second negative voltage.