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:
Mar. 06, 2018
Filed:
Sep. 22, 2016
Ngk Spark Plug Co., Ltd., Nagoya-shi, Aichi, JP;
Haruki Yoshida, Tajimi, JP;
Jumpei Isasa, Nishikasugai-gun, JP;
Toshitaka Honda, Nagoya, JP;
Yutaka Yokoyama, Kasugai, JP;
Kuniharu Tanaka, Komaki, JP;
Nobuyoshi Araki, Nagoya, JP;
Toshiki Kon, Komaki, JP;
NGK SPARK PLUG CO., LTD., Nagoya, JP;
Abstract
A spark plug includes an insulator, a center electrode, a metallic shell, and a ground electrode. The insulator contains not less than 90.0 mass % and not greater than 98.1 mass % of AlOwith respect to a total mass of elements, as reduced to oxides, contained in the insulator, and has a porosity not greater than 5%. Assuming that a porosity of the insulator after a heat treatment is B, a difference (B−A) of the porosities before and after the heat treatment is not greater than 3.5%. In the heat treatment, the insulator is placed in a furnace, and a temperature in the furnace is increased from a room temperature to 1400° C. at a temperature increase rate of 7° C./min and is held at 1400° C. for 30 minutes, and thereafter, the temperature is decreased from 1400° C. to 400° C. at a temperature decrease rate of 10° C. or less per 5 minutes and is decreased to the room temperature.