Spark plug with heatable insulator for cold starts

摘要

A spark plug (1) has an insulator (14) to hold the central electrode (12) together with the hexagonal nut on the threaded collar (15a) and earth electrode (13). However, at least part of the insulator may be heated. It is necessary for cold start operation, and the insulator is raised to a temperature of at least 100 degC. For this purpose, there is an integral heating wire (17) whose ends (17a) are connected to the ignition switch. The heating wire is embedded up to the nose of the insulator, where it projects into the combustion chamber.