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AssigneeNgk Spark Plug Co., Ltd.
InventorsKenichi Nishikawa, Yutaka Tanaka, Toshitaka Honda, Makoto Sugimoto
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In a spark plug (100), the resistor composition constituting a resistor (15) contains semiconductive ceramic particles, offering a superior load life characteristic. Also, the value of (.alpha.2-.alpha.1)/.alpha.1 >=-0.30, where a value of electric resistance between a terminal (13) and a center electrode (3) is .alpha.1 at 20.degree. C. and .alpha.2 at 150.degree. C., so that deterioration of the radio frequency noise prevention performance at high temperatures can be effectively suppressed. The resistor composition contains semiconductive ceramic particles whose temperature coefficient of electric resistance shows a positive value, or a negative value of relatively small absolute value, (e.g., TiO.sub.2 particles having a rutile type crystalline structure, titanate or zirconate of alkali earth metal elements, titanium suboxide, etc.), or titanium metal. Thus, the invention provides a resistor-incorporated spark plug which is enabled to offer a stable load life characteristic even when a high load acts thereon, and which is unlikely to deteriorate in the radio frequency noise prevention performance even under high temperatures.
A resistor-incorporated spark plug in which a through hole is formed along an axis of an insulator, a terminal is fixed to one end side of the through hole while a center electrode is fixed to the other end side of the through hole, and in which a resistor made of a resistor composition principally comprising a conductive material, glass particles and ceramic particles other than glass is placed between the terminal and the center electrode within the through hole,
A resistor-incorporated spark plug in which with respect to a through hole which is formed along an axis of an insulator, a terminal is fixed to one end side of the through hole while a center electrode is fixed to the other end side of the through hole, and in which a resistor is made of a resistor composition principally comprising a conductive material, glass particles and ceramic particles other than glass is placed between the terminal and the center electrode within the through hole,
A resistor-incorporated spark plug in which a through hole is formed along an axis of an insulator, a terminal is fixed to one end side of the through hole while a center electrode is fixed to the other end side of the through hole, and in which a resistor is made of a resistor composition principally comprising a conductive material, glass particles and ceramic particles other than glass is placed between the terminal and the center electrode within the through hole,
A resistor-incorporated spark plug in which a through hole is formed along an axis of an insulator, a terminal is fixed to one end side of the through hole while a center electrode is fixed to the other end side of the through hole, and in which a resistor is made of a resistor composition principally comprising a conductive material, glass particles and ceramic particles other than glass is placed between the terminal and the center electrode within the through hole,
A resistor-incorporated spark plug in which a through hole is formed along an axis of an insulator, a terminal is fixed to one end side of the through hole while a center electrode is fixed to the other end side of the through hole, and in which a resistor made of a resistor is composition principally comprising a conductive material, glass particles and ceramic particles other than glass is placed between the terminal and the center electrode within the through hole,
Dependencies are inferred from the claim text.