A dual spark plug may include: a cap plug formed of an insulation material; an upper body formed of an insulation material and coupled with the cap plug; a lower body integrally formed with the upper body and provided at an outer side of the upper body; a pair of plug center electrodes provided inside the cap plug; a pair of upper center electrodes provided inside the upper body and electrically connected with the pair of plug center electrodes; insulation caps provided to wrap the pair of plug center electrodes, respectively; and a pair of ground electrodes extended from opposite sides of the lower body and disposed at a predetermined distance from the pair of upper center electrodes, respectively.

A spark plug includes a terminal electrode extending in an axial direction of the spark plug. The terminal electrode has an end in the axial direction, and has a recess formed in the end of the terminal electrode. The recess has a bottom surface and an identifier on the bottom surface. The recess has a side surface parallel to the axial direction.

A spark plug includes a terminal electrode extending in an axial direction of the spark plug. The terminal electrode has an end in the axial direction, and has a recess formed in the end of the terminal electrode. The recess has a bottom surface and an identifier on the bottom surface. The recess has a side surface parallel to the axial direction.

A spark plug includes a terminal electrode extending in an axial direction of the spark plug. The terminal electrode has an end in the axial direction, and has a recess formed in the end of the terminal electrode. The recess has a bottom surface and an identifier on the bottom surface. The recess has a side surface parallel to the axial direction.

A spark plug includes a terminal electrode extending in an axial direction of the spark plug. The terminal electrode has an end in the axial direction, and has a recess formed in the end of the terminal electrode. The recess has a bottom surface and an identifier on the bottom surface. The recess has a side surface parallel to the axial direction.

A contacting device of a voltage transmission device of an ignition device of a large engine, whose cylinders have piston diameters of at least 140 mm having a first spring portion for the electrical contacting of a cable contacting piece of the voltage transmission device and a second spring portion for the electrical contacting of a spark plug connection of a spark-plug of the ignition device. The second spring portion tapers in a direction of its end, which comes to lie against the spark-plug connector of the spark-plug. The spark-plug connector of the spark-plug interacting with the contacting device includes a trough into which the contacting device can be introduced with a spring portion.

A contacting device of a voltage transmission device of an ignition device of a large engine, whose cylinders have piston diameters of at least 140 mm having a first spring portion for the electrical contacting of a cable contacting piece of the voltage transmission device and a second spring portion for the electrical contacting of a spark plug connection of a spark-plug of the ignition device. The second spring portion tapers in a direction of its end, which comes to lie against the spark-plug connector of the spark-plug. The spark-plug connector of the spark-plug interacting with the contacting device includes a trough into which the contacting device can be introduced with a spring portion.

In at least some implementations, a coupler for a spark plug includes a body formed from an electrically conductive material and including a first connecting portion defining a first cavity, and a second connecting portion defining a second cavity spaced from the first cavity, and the body includes an intermediate portion physically and electrically coupling the first connection portion and the second connecting portion. In at least some implementations, the first connecting portion is formed from a wire coiled to define the first cavity within the coil. In at least some implementations, the second connecting portion is formed from a wire coiled to define the second cavity within the coil.

In at least some implementations, a coupler for a spark plug includes a body formed from an electrically conductive material and including a first connecting portion defining a first cavity, and a second connecting portion defining a second cavity spaced from the first cavity, and the body includes an intermediate portion physically and electrically coupling the first connection portion and the second connecting portion. In at least some implementations, the first connecting portion is formed from a wire coiled to define the first cavity within the coil. In at least some implementations, the second connecting portion is formed from a wire coiled to define the second cavity within the coil.

The present invention relates to a spark plug extension body connecting an ignition coil with a spark plug for a spark ignited internal combustion engine, as well as a method for providing such a spark plug extension body for reduction of partial electrical discharges in the spark plug extension body. In conventional spark plug extensions are coil springs used as electrical conductor against the spark plug terminal and/or ignition coil terminal. These coil springs cause Corona effects and short circuiting requiring replacement of the spark plug extension. With the invention the entire electrical conductor (CR.sub.u, 64, CR.sub.L) is in a rod like form and at least both ends (CR.sub.u, CR.sub.L) of the electrical conductor (CR.sub.u, 64, CR.sub.L) are made as a monolith in a flexible and electrically conducting polymeric material, preferably electrically conducting rubber.