| 摘要 |
PURPOSE:To reduce a required break-down voltage to aim at miniaturizing an ignition coil, by providing a second ignition device for applying a high frequency a.c. voltage to the secondary side of the ignition coil during the period from a time which is before the generation of a high voltage on the secondary side of the ignition coil by a predetermined time, to the time of the generation of the high voltage. CONSTITUTION:An ignitor 5 as a first ignition device connected to an ECU 1 is connected to the primary side of a first ignition coil 6 whose secondary side is connected to spark plugs 81 in engine cylinders through a piezoelectric element 7 and a distributor 8. Further, a second ignitor 10 is connected to the ECU 1, and is also connected to the primary side of a second ignition coil 9 whose secondary side is connected to the secondary side of the first ignition coil 6. Further, the second ignitor 10 is arranged such that a high frequency voltage of a high value which does not cause spark plugs 81 to give spark discharge is applied to the spark plugs 81 during the period from the time which is before the generation of a high voltage on the secondary side of the first ignition coil 6 by a predetermined time, to the time of generation of the high voltage.
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