Spark plug

Abstract

A glaze layer 2d of a spark plug has the following compositions: 1mol percent or less lead composition in the form of PbO; 25-45mol percent silicon composition in the form of silicone dioxide (SiO2); 20-40mol percent boron composition in the form of boron trioxide (B2O3); 5-25mol percent zinc composition in the form of zinc oxide (ZnO); 0.5-15mol percent barium composition in the form of barium oxide (BaO) and / or strontium composition in the form of strontia (SrO); at least one of the three alkali metals of sodium, kalium and lithium, wherein the total amount of the alkali metal composition being 5-10mol percent respectively in the forms of Na2O, K2O and Li2O, and kalium being the most fundamental composition; further one or two or many of the metals of molybdenum, tungsten, nickel, cobalt, iron and manganese respectively in the forms of MoO3, WO3, Ni3O4, Co3O4, Fe2O3 and MnO2, wherein the total amount being 0.5-5mol percent.

Description

[0001] This application is a divisional application of the Chinese invention patent application whose application number is 01122888.1, the application date is May 31, 2001, and the invention name is "spark plug". technical field [0002] The invention relates to a spark plug. Background technique [0003] A spark plug for ignition of an automobile engine generally consists of a metal shell to which a ground electrode is fastened, an insulator made of alumina ceramic and a central electrode placed inside the insulator. The insulator protrudes axially from the rear opening of the metal shell. A terminal metal clamp (terminal) is inserted into the protruding portion of the insulator and connected to the central electrode through a conductive glass seal formed in a glass seal process or a resistor. A high voltage is applied to the terminal metal clamp, causing a spark to be generated in the gap between the ground electrode and the center electrode. [0004] Under some mixed c...

AI Technical Summary

Problems solved by technology

However, the glaze composition described in Japanese Patent JP-A-11-106234 cannot always meet the insulation requirements at high temperatures, especially as the glaze layer formed on the insulator on the spark plug cannot meet high temperature requirements (such as anti-fly arc performance)

[0008] Japanese Patent JP-A-11-106234 relates to the improvement of insulation resistance by using an alkaline glaze containing silicon or boron as a glass skeleton, but fails to recognize the need for close attention to eliminate the thermal expansion of alumina-based ceramics that constitute ceramics as insulators coefficient of thermal expansion and the glaze, the level of improvement in insulation resistance is not always satisfactory

Images