Spark plug for internal combustion engine, includes shaded zone on insulator foot in region of intermediate space, to provide shaded zone in radial direction

摘要

The spark plug is designed to avoid build-up of carbon black which arises during ignition and forming an extensive layer which if not removed or prevented could lead to a shunt. The insulator foot (20) in the region of the intermediate space is provided with a contour or shaped-zone (30) at at least one point, and has a 'shaded' region (A) with reference to the axial direction.