Patent ID: 7095306

Claim:
An ignition coil comprising: a cylindrical portion that includes a primary coil and a secondary coil, the secondary coil being wound coaxially with respect to the primary coil; and an ion current detecting device that detects ion current, wherein the cylindrical portion is capable of being inserted into a plughole of an internal combustion engine, the cylindrical portion has a tip end in an axial direction of the cylindrical portion, the tip end of the cylindrical portion has a plug mounting hole, into which a sparkplug is mounted, the plug mounting hole accommodates a high voltage terminal that electrically connects with the secondary coil, the plug mounting hole accommodates a coil spring that makes contact with the high voltage terminal, the cylindrical portion has a base end portion in one end with respect to the axial direction of the cylindrical portion, the base end portion of the cylindrical portion includes at least one flange portion, the at least one flange portion outwardly protrudes in a radial direction of the cylindrical portion, and the at least one flange portion has a plurality of bolt insertion holes, through which a bolt is respectively inserted.