IGNITION DEVICE, IGNITION PLUG AND ENGINE EMPLOYING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide an engine ignition device capable of making reduction of a required voltage compatible with improvement of ignition performance without any special electrical configuration, an ignition plug and an engine employing the same.SOLUTION: An ignition device 3 is configured to generate spark discharge by applying a voltage to a gap formed from a center electrode 11 and a ground electrode 12. Separately from the center electrode 11, an auxiliary electrode 13 is provided for applying a voltage of the same polarity as the center electrode 11 or a reverse polarity. A voltage which is equal to or lower than the voltage applied between the center electrode 11 and the ground electrode 12 and does not generate spark discharge is applied to the auxiliary electrode 13. The auxiliary electrode 13 is positioned in such a manner that an electric field Ef2 between the auxiliary electrode 13 and the ground electrode 12 or an electric field Ef3 between the auxiliary electrode 13 and the center electrode 11 generated by the applied voltage is spread over the gap. A time of applying the voltage to the auxiliary electrode 13 is controlled to include a time of applying a voltage between the center electrode 11 and the ground electrode 12.