Ngk Spark Plug Company, Limited

Hiroshi Ono

Yoshihiro Matsubara

Makoto Yamaguchi

Kazumasa Yoshida

Akio Kokubu

Kazuya Iwata

Shunsuke Gotou

Shoichiro Ito

Masanori Ootubo

There is provided an energization control apparatus for a glow plug in an engine, including a post-start glow section to control energization of a resistance heater of the glow plug by a battery after start of the engine. The post-start glow section is configured to evaluate revolution stability of the engine and control the energization of the resistance heater according to a first control pattern when the engine revolution stability is higher than or equal to a threshold level and according to a second control pattern that achieves a higher temperature of the sheath heater than the first control pattern when the engine revolution stability is lower than the threshold level.

Glow plug energization control apparatus and method

An ignition system has a spark plug and a positive voltage applying unit. The spark plug includes a central electrode, a porcelain insulator for holding the central electrode, a main metallic shell for holding the porcelain insulator, and a ground electrode electrically connected to the main metallic shell. The positive voltage applying unit applies a positive voltage to the central electrode of the spark plug in comparison with the ground electrode, so that an ignition high voltage is applied between the central electrode and the ground electrode. In the spark plug, a spark discharge gap is formed between the ground electrode and a distal end portion of the central electrode. The ground electrode is positioned so that a rear edge of a mating face opposed to a peripheral side of the central electrode is positioned in the side of the distal end of the central electrode in comparison with an end face of the porcelain insulator.

Ignition system

In a spark plug for use for an internal combustion engine, an elongated insulator is provided in which a center electrode is supported. A cylindrical metal shell is provided in which the insulator is supported, and a ground electrode extends from the metal shell to form a spark gap with a front end of the center electrode. The front end of the center electrode has a tapered-off step section whose front end surface has a spark erosion resistant portion, and having a boundary between a columnar portion of the center electrode and the tapered-off step section. The boundary of the tapered-off step section is located within a front end surface of the insulator, and a front end surface of the tapered-off step section is positioned outside of the front end surface of the insulator. The front end of the center electrode forms a conoidal configuration having an apex angle formed at the center of the center electrode, circumscribing a front periphery of the insulator while maintaining an apex angle of 110 degrees or less.

Spark plug in use for an internal combustion engine

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Nagoya, Japan

Hiroshi Ono