An ignition apparatus for an internal combustion engine includes a spark plug, an ignition coil with a voltage connection, and a spring for electrically connecting the spark plug to the voltage connection. A continuous spring wire in the form of external turns extends from an ignition coil-side end of the spring to a spark plug-side end of the spring. The spring wire at the spark plug-side end continues in the form of internal turns within the external turns in a direction toward the ignition coil-side end.

An ignition apparatus for an internal combustion engine includes a spark plug, an ignition coil with a voltage connection, and a spring for electrically connecting the spark plug to the voltage connection. A continuous spring wire in the form of external turns extends from an ignition coil-side end of the spring to a spark plug-side end of the spring. The spring wire at the spark plug-side end continues in the form of internal turns within the external turns in a direction toward the ignition coil-side end.

A corona igniter assembly including an ignition coil assembly, a firing end assembly, and a dielectric compliant member is provided. The dielectric compliant member is compressed between a high voltage insulator of the ignition coil assembly and a ceramic insulator of the firing end assembly. During assembly of the corona igniter assembly, the dielectric compliant member pushes air outwards and forms a hermetic seal between the high voltage insulator and the ceramic insulation. The dielectric compliant member can have a rounded upper surface, which may improve the hermetic seal. Alternatively, or in addition to the rounded surface on the dielectric compliant member, the lower surface of the high voltage insulator can be rounded to push air outwards during assembly and provide a hermetic seal.

A corona igniter assembly including an ignition coil assembly, a firing end assembly, and a dielectric compliant member is provided. The dielectric compliant member is compressed between a high voltage insulator of the ignition coil assembly and a ceramic insulator of the firing end assembly. During assembly of the corona igniter assembly, the dielectric compliant member pushes air outwards and forms a hermetic seal between the high voltage insulator and the ceramic insulation. The dielectric compliant member can have a rounded upper surface, which may improve the hermetic seal. Alternatively, or in addition to the rounded surface on the dielectric compliant member, the lower surface of the high voltage insulator can be rounded to push air outwards during assembly and provide a hermetic seal.

A spark plug, including an insulator, a casing including a sealing surface, and a gasket which rests against the sealing surface, the sealing surface including a plurality of recesses.

This invention is concerning an ignition device for an internal combustion engine, wherein a plug boot has a reduced-inner-diameter portion having an inner diameter size smaller than that of the other portion, a spring has a larger diameter portion having a diameter size larger than that of the other portion, and a plurality of reduced clearances each having a width reduced by the reduced-inner-diameter portion and the larger diameter portion are formed between the spring and the inner wall surface of the plug boot.

This invention is concerning an ignition device for an internal combustion engine, wherein a plug boot has a reduced-inner-diameter portion having an inner diameter size smaller than that of the other portion, a spring has a larger diameter portion having a diameter size larger than that of the other portion, and a plurality of reduced clearances each having a width reduced by the reduced-inner-diameter portion and the larger diameter portion are formed between the spring and the inner wall surface of the plug boot.

In an ignition coil for an internal combustion engine, a spark plug is incorporated which has an insulator including an insulator head that has no corrugation. The ignition coil has a coil body part generating high voltage and a joint part, which holds therein a conducting member electrically connecting the coil body part and a spark plug. The joint part has a plug cap into which the insulator head of the spark plug is inserted and which is formed of an elastic member having a cylindrical shape. The plug cap has a close-contact part whose inner peripheral surface is closely brought into contact with an outer peripheral surface of the insulator. The close-contact part has a tip end-side close-contact part positioned at a tip end side with respect to a middle position in an axial direction, and a base end-side close-contact part positioned at a base end side with respect to the middle position. At least part of the base end-side close-contact part is provided with a strong strained force part that has strained force for fastening the insulator head, the strained force being stronger than strained force of all portions of the tip end-side close-contact part.

In an ignition coil for an internal combustion engine, a spark plug is incorporated which has an insulator including an insulator head that has no corrugation. The ignition coil has a coil body part generating high voltage and a joint part, which holds therein a conducting member electrically connecting the coil body part and a spark plug. The joint part has a plug cap into which the insulator head of the spark plug is inserted and which is formed of an elastic member having a cylindrical shape. The plug cap has a close-contact part whose inner peripheral surface is closely brought into contact with an outer peripheral surface of the insulator. The close-contact part has a tip end-side close-contact part positioned at a tip end side with respect to a middle position in an axial direction, and a base end-side close-contact part positioned at a base end side with respect to the middle position. At least part of the base end-side close-contact part is provided with a strong strained force part that has strained force for fastening the insulator head, the strained force being stronger than strained force of all portions of the tip end-side close-contact part.

A connector plug is described for connecting an ignition coil to a spark plug, comprising an electrical conductor, which has a first end for contacting the ignition coil and a second end for contacting the spark plug, and a protective tube, which surrounds the electrical conductor. In accordance with this disclosure it is proposed that the protective tube has a predetermined bending point with a reduced bending stiffness.