If the available voltage is sufficient, the wider spark gap is the better the ignitability becomes.Hence, automobiles with cleaner exhaust gases are usually equipped with spark plugs with
1.1 mm spark gaps, combined with a strong power source.
The VX type spark plug has an extremely fine center electrode tip made of Platinum, so the required voltage is lower than a conventional plug and better ignition can be obtained. In spite of the fine center electrode, the Platinum tip gives long life
This spark plug’s center electrode has a 90° V-groove parallel with the ground electrode where there is little flame extinguishing effect(electrode acts to absorb the heat of the flame). It also reduces the electrode surface bordering the flame to alleviate the flame extinguishing effect, resulting in better ignitability. In addition, the 90° groove in the center electrode enhances the potential gradient which
makes it easier to cause a spark.
The heating coil a n d regulating coil(where applicable) are enclosed in a tube made from heat resistant alloy and magnesium oxide powder is packed between the coil and tube(sheath). The coil is therefore not directly exposed to the combustion process and the shock waves produced by the rapid expansion of the gases. Because of the protection afforded by the tube, carbon produced by the combustion process cannot build up on the heating coil and cause a short-circuit.
The ceramic glow plug has a special high melting point heating coil enclosed in New Ceramic (silicon nitride). Silicon Nitride has very good thermal conductivity and therefore preheating time is shortened. It also has the ability to withstand extremely fast heating times over long service periods. Compared to the sheathed metal type the ceramic glow plug has greater heat resistance and durability.