The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 23, 1993
Filed:
Feb. 07, 1992
Shunkichi Nozaki, Aichi, JP;
Yasuhiko Suzuki, Aichi, JP;
Kazuho Tatematsu, Aichi, JP;
Masakazu Iwai, Aichi, JP;
Kiminori Horiki, Aichi, JP;
NGK Spark Plug Co., Ltd., Nagoya, JP;
Abstract
The invention relates to a ceramic heater for use, e.g., as a glow plug for a diesel engine or as an igniter for an oil or gas burner. The ceramic heater has a nonoxide ceramic body having a heating part and a supporting part and a heating resistor embedded in the heating part of the ceramic body. The material of the heating resistor is W, WC, tungsten alloy or a metal nitride such as TiN or TaN. According to the invention the heating part of the ceramic body is formed of aluminum nitride ceramic, which is high in heat conductivity and resistant to oxidation at high temperatures, at least in a core region in contact with the heating resistor, and the supporting part is formed of silicon nitride ceramic which is low in heat conductivity at least in a surface region. The ceramic body is made by uniting a heating part entirely formed of aluminum nitride ceramic and a supporting part entirely formed of silicon nitride ceramic with interposal of a joint part which is formed of mixed ceramic of aluminum nitride and silicon nitride with a gradient of the proportion of aluminum nitride to silicon nitride, or by thoroughly covering a core formed of aluminum nitride ceramic with silicon nitride ceramic.