| 摘要 |
PURPOSE:To protect a glow plug from external force and a thermal shock and to improve its strength, by so constituting that a bar form ceramic heating element is wrapped up with a cylindrical insulator and a metalized layer of a heat resistant metal is formed on an exposed part of the insulator at the tip of the heating element. CONSTITUTION:A heating element 5 made of a bar form electrically conductive ceramic sintered body is inserted into a cylindrical insulator 6 made of a sintered silicon carbide or silicon nitride and a metallic tube 2 and a center shaft 4 are combined with each other. Then, gaps among the metallic tube 2, the heating element 5 and the center shaft 4 are filled with insulating powder 8. Then, the circumference of the sintered body 6 and the tip of the heating element 51 are metallized with a heat resistant metal for finishing to a predetermined form. Then, the metallic tube is soldered to metal fittings 1. Then, hermetically sealed with glass seal 9 after a gap between the metal fittings 1 and the center shaft 4 is filled with the powder 8. With this constitution, the improvement of strength can be contrived without applying directly an external force and a thermal shock to a ceramic heating element. |
