CERAMIC HEATER GLOW PLUG AND METHOD OF MANUFACTURING SAME

摘要

In order to silver braze a ceramic heating element (6), a metallic outer sleeve (8) and an electrode fitting (14) together, optimum conditions are confirmed by tests so as to prevent an occurrence of an electrical short-circuit between the metallic outer sleeve (8) and the electrode fitting (14). An attachment opening (6b)is formed is formed in an end face of the ceramic heating element(6), and one end (14b) of the electrode fitting (14) is inserted into the opening while the ceramic heating element is contained within the metallic outer sleeve (8). A silver brazing filler metal (22) in the form of a wire is coiled and placed on the ceramic heating element in an annular space between the metallic outer sleeve and the electrode fitting. When heated to 900 DEG C in hydrogen ambient, the silver brazing filler metal melts and flows into interstices between the outer peripheral surface of the ceramic heating element and the innner peripheral surface of the metallic outer sleeve and into interstices between the attachment opening in the ceramic heating element and the external surface of the electrode fitting. When an internal diameter X of the metallic outer sleeve and an external diameter Y of the electrode fitting satisfy the relation ship X - Y >/= 1.5mm, there remains no silver brazing filler metal 22 on the ceramic heating element (6), thus preventing a short-circuit from occurring between the metallic outer sleeve and the electrode fitting.