Federal-mogul Ignition Gmbh

Mario Dittmann

Werner Niessner

Alexander Schenk

Anko Ernst

Udo Sander

The invention relates to a spark plug for a gas-fired internal combustion engine, and Includes a metallic body, with an insulator fastened in the body. A central electrode, leads through the insulator and includes a protruding end of a precious metal alloy. An annular ground electrode is fastened to the body and surrounds the end of the central electrode which, at the inside thereof facing the central electrode is provided with a precious metal or with a precious metal alloy. The mutually facing surfaces of the central electrode and ground electrode formed by the precious metal or the precious metal alloy are coaxially disposed cylinder surfaces. A cap is provided and attached to the body and which, after installation of the spark plug into a combustion chamber of the internal combustion engine, shields the central electrode and the ground electrode from the combustion chamber. Together with the body of the spark plug, the central electrode forms an ante-chamber, in which the central electrode and the ground electrode are disposed. The cap having at least one opening, which enables a gas exchange between the ante-chamber and the space outside of the ante-chamber. According to the invention, a deviation of the cylinder surfaces from the ideal cylinder geometry is less than +&#x2212;20 &#x3bc;m, and a deviation of the positions of the axes of the cylinder surfaces from their ideal coaxial position is less than +&#x2212;50 &#x3bc;m.

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Friedrichshafen, Germany

Mario Dittmann