| 摘要 |
PROBLEM TO BE SOLVED: To provide a sparkplug capable of preventing lateral spark by manufacturing an insulator inhibiting eccentricity of a shaft hole by reducing torsion of a support pin used in a manufacturing process of the insulator. SOLUTION: From a sample of a plurality of insulators of different product dimensions, a calculation formula 0.01×(0.141×A-0.140×D-0.285×B-6.124×C+1.105×E+17.527) is drawn in which dimensions of respective parts of the insulators, in other words, a whole length A, an outer diameter B of a rear side barrel part, an inner diameter C of a large diameter part, a length D of the large diameter part and an inner diameter E of a small diameter part are used as parameters by a statistical analysis using a using multiple regression analysis. If the insulator is designed so that an assumed value of a thickness deviation quantity of the insulator calculated by the formula becomes less than 0.07, lateral spark of the sparkplug manufactured by using the insulator can be prevented. COPYRIGHT: (C)2008,JPO&INPIT
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