Ngk Spark Plug Company, Limited

Sumitomo Electric Industries, Limited

Kozo Amano

Yoshihiro Matsubara

Yoshihiro Nakai

Junichi Kagawa

Masatada Numano

Kazuo Yamazaki

Kenichi Kumagai

Teruyuki Kondo

Wataru Matsutani

Iwao Kunitomo

Yoshiaki Saiki

A spark plug comprising: a cylindrical metal shell; a cylindrical insulator provided in an inner hole of said metal shell; a center electrode provided in a leading end side inner hole of said insulator; and a ground electrode having one end bonded to a leading end side of said metal shell and having another end face forming a spark discharge gap with said center electrode, wherein said ground electrode comprises an electrode material containing from 0.5 to 1.5 wt. % of Si, from 0.5 to 1.5 wt. % of Al, from 0.02 to 1.0 wt. % of at least one of Ti, V, Zr, Nb and Hf, from 0.03 to 0.09 wt. % of C and 95.5 wt. % or more of Ni, and having a specific resistance at 20&#xb0; C. of 25 tincm or less.

Spark plug for internal combustion engine

A spark plug comprising: a cylindrical metal shell; a cylindrical insulator provided in an inner hole of said metal shell; a center electrode provided in a leading end side inner hole of said insulator; and a ground electrode having one end bonded to a leading end side of said metal shell and having another end face forming a spark discharge gap with said center electrode, wherein said ground electrode comprises an electrode material containing from 0.5 to 1.5 wt. % of Si, from 0.5 to 1.5 wt. % of Al, from 0.02 to 1.0 wt. % of at least one of Ti, V, Zr, Nb and Hf, from 0.03 to 0.09 wt. % of C and 95.5 wt. % or more of Ni, and having a specific resistance at 20&#xb0; C. of 25 &#x3bc;&#x3a9;cm or less.

A spark plug in use for an internal combustion engine, includes an insulator placed in a metal shell in a manner to extend its front end beyond the metal shell, a center electrode is placed within an axial bore provided by the insulator, an outer electrode which is welded to a front end of the metal shell is so bent that a firing end of the outer electrode faces a front end of the insulator with a space therebetween to cause surface-spark discharges along a front end surface of the insulator and to cause a semi-surface spark discharge between the center electrode and the outer electrode, the front end of the center electrode is protroacted from a front end of the insulator by at most than 0.5 mm or retracted from the front end of the insulator by at most than 1.0 mm, and the firing end of the outer electrode is in line with the front end surface of the insulator, thereby optimizing a carbon-deposit cleaning performance of the spark plug with the semi-surface spark discharge, according to the invention. In addition, a firing end portion of the center electrode has a slender noble metal tip in a preferred embodiment of the spark plugs of the invention.

Creeping discharge spark plug

In a spark plug having a noble metal layer disposed on a firing end of an electrode, the noble metal layer being laser welded to the firing end of the electrode, and subsequently heat treated to increase a crystallized granulation particle size of the noble metal layer.

Method of making a spark plug including laser welding a noble metal

In a multi-polarity type spark plug for an internal combustion engine, a tubular insulator is supported within a cylindrical metallic shell through which a spark plug is to be attached to an internal combustion engine. A center electrode is placed within the insulator, a front end of the center electrode being directed toward a combustion chamber of the internal combustion engine from a front end of the metallic shell so as to extend beyond a front end of the insulator. First and second ground electrodes are each connected to the front end of the metallic shell, the first ground electrode forming a first vertical spark gap with a front end surface of the center electrode which directly opposes an elevational side of the center electrode, and the second ground electrode forming a second horizontal spark gap with an elevational side of the center electrode. An angle .theta.a is limited as 60.degree..ltoreq..theta.a .ltoreq.150.degree. in which the angle .theta.a is taken when the first ground electrode forms against the second ground electrode with the center electrode as an axial center.

Multi-polarity type spark plug for use in an internal combustion engine

A temperature and pressure detecting type spark plug has a metallic shell having a mounting seat around an outer surface of the shell. The plug further has a center electrode which is placed into a tubular insulator. The center electrode has a hollow portion to enclose a thermocouple to detect a temperature of the front end of the center electrode. An annular pressure sensor is placed at the mounting seat of the metallic shell to detect a pressure within a combustion chamber in a cylinder head. The pressure sensor is arranged to be sandwiched between the mounting seat and the cylinder head when the spark plug is secured to the cylinder head of an internal combustion engine.

Temperature and pressure detecting type spark plug

A spark plug with pressure sensor comprising; a center electrode having a high voltage terminal; an insulator provided around said center electrode to securely support it; a tubular metallic shell provided to support said insulator at its inner side; a pressure sensor having a piezoelectrical element at least enclosed by a casing of a metallic hollow ring; the metallic shell having a diameter-increased portion and a diameter-reduced portion; the casing of the sensor being inserted into the diameter-reduced portion with an inner side of the casing tightly engaging the outer side of the diameter-reduced portion; a mount means having a ring portion and a flange portion; the ring portion tightly inserted into the diameter-reduced portion while the flange portion tightly sandwiching the casing with a step between the diameter-reduced portion and the diameter-increased portion; and the ring portion being welded to said diameter-reduced portion to maintain air-tight relationship between an innerside of the ring portion and outer side of the diameter-reduced portion.

Growing community of inventors

Nagoya, Japan

Kozo Amano