Ignition device with series gap having shielding case

摘要

An ignition device with a series gap includes a series gap assembly having therein a discharge tube. A shielding case is provided to cover the series gap assembly. The shielding case is made of a conductive material and arranged to be in contact with a cylinder head or an engine block so that electrical continuity is held between the shielding case and the cylinder head or the engine block. Accordingly, the shielding case effectively works to provide a reliable electric shielding between the exterior and interior of the shielding case so that electromagnetic wave caused by sparking of the discharge tube is prevented from leaking outside and an ambient electric field is prevented from affecting a discharge characteristic of the discharge tube.