Patent ID: 7559319
Filing Date: 2009-07-14
Classification: F02P

Abstract:
1. An ignition coil apparatus for an internal combustion engine provided with a cylinder having a plurality of spark plugs, the apparatus comprising: a coil member having a primary coil and a secondary coil; a switching unit that serves to selectively supply and interrupt a primary current for the primary coil; a bias unit that is charged with a voltage generated in the primary coil as a bias voltage upon interruption of the primary current; an ionic current detection unit that detects, as an ionic current, ions generated by the combustion of an air fuel mixture in the cylinder; a first diode that serves to protect the ionic current detection unit; and a second diode that serves to prevent the bias voltage from being discharged at the instant when the primary current is started to be supplied to the primary coil; wherein the primary coil has one end thereof connected to a battery, and at the same time the other end thereof connected to the switching unit; the secondary coil has a first end and a second end thereof connected to the plurality of spark plugs, respectively, through individual high voltage output terminals; the first diode has an anode thereof connected to the bias unit; the first diode has a cathode thereof connected between the first end of the secondary coil, at which a high voltage of a positive polarity is generated upon interruption of the primary current, and a high voltage output terminal at a side of the first end side of the secondary coil; the second diode has an anode thereof connected to the first end of the secondary coil; and the second diode has a cathode thereof connected to a junction between the first diode and the high voltage output terminal at a side of the first end of the secondary coil.