Spark plugs with multiple-ground electrodes

Why spark plugs with multiple-ground electrodes?

In each ignition event molecules are taken away from the electrode material. This phenomenon is called spark erosion. Due to this continuous process material is worn away and spark gap increases.

However, this increase is permissible only within certain limits because the necessary ignition voltage, which mainly depends on the spark gap, increases too much and misfiring can occur. However misfiring with modern engines is not permissible at all, as this would induce increased emissions, reduced engine performance, and damage to the catalytic converter.

In order to increase the service life of a spark plug materials of higher erosion resistance (platinum etc.) can for example be used, or the material quantity (2, 3, or 4 ground electrodes) can be altered. The target of both measures is to ensure the service life of the spark plug and the operational reliability of the engine over a long period of time.

The demands of the automotive industry on suppliers have increased tremendously in recent years, because the increase of maintenance intervals is a decisive buying criterion.

While during the 60`s exchange periods of 5-10,000 km were specified, today spark plugs are being used with a running performance of 60,000 km.

In order to solve this conflict of aims, between operational reliability, long service life, and cost effectiveness NGK produced spark plugs with multiple electrodes. Being one of the first suppliers, NGK has been delivering these spark plugs to renowned German automotive manufacturers (BMW, VW/Audi) for installation in series production. The technological co-operation on the basis of partnership between the automotive manufacturers and NGK resulted in high-tech spark plugs offering the end consumer solid advantages: Reduction in operating costs, improved protection of the environment, and increased operational reliability.