INTERNAL COMBUSTION ENGINE IGNITION COIL

摘要

This internal combustion engine ignition coil is fitted with a spark plug having an insulator provided with an insulator head portion having no corrugation. This ignition coil has a coil main body portion for generating a high voltage, and a joint portion holding therein a conduction member for connecting electrically the coil main body portion to the spark plug. The joint portion has a plug cap comprising an elastic member having a cylindrical shape, and allows the insulator head portion of the spark plug to be inserted therein. The plug cap has a tight-contact portion whereof the inner peripheral surface is brought into tight contact with the outer peripheral surface of the insulator. The tight-contact portion has a forward end side tight-contact portion that is more to the forward end side than a central position in the axial direction, and a base end side tight-contact portion that is more to the base end side than the central position. In at least a portion of the base end side tight-contact portion, a strong straining force portion is formed, wherein the straining force squeezing the insulator head portion is stronger than the straining force in any position in the forward end side tight-contact portion.