Ngk Spark Plug Company, Limited

Bayerische Motoren Werke Aktiengesellschaft

Junichi Kagawa

Wataru Matsutani

Yoshihiro Matsubara

Kazunori Yokota

Akihiro Toya

Takashi Yamaguchi

Shigeru Miyata

Mitsutaka Yoshida

Kozo Amano

Akio Sakura

Takafumi Oshima

Masato Taniguchi

Mamoru Musasa

Mitsuyoshi Kawamura

Alfred Krappel

Hideki Teramura

Tsuneo Ito

Yasushi Sato

Yoshiaki Saiki

Johannes Guggenmos

Masaaki Murase

Josef Holzmann

Shinichi Nakamura

Toru Hayashi

Hiroaki Mori

Shigeru Nagasaki

Spark plug has a central electrode, an insulator provided exterior to the central electrode, main metallic shell provided exterior to the insulator in such a way that the central electrode protrudes from one end, and a ground electrode coupled at one end to the main metallic shell and which has the other end disposed to face the central electrode, with a chip being secured to either the central electrode or the ground electrode or both to form spark discharge gap g. The chip is made of a metal based on Ir which contains Rh in an amount ranging from 3 to 50 wt (50 wt % being not inclusive).

Spark plug with alloy chip

A spark plug is disclosed, in which a center electrode has, at the end thereof which forms a spark discharge gap, a noble metal chip which has a straight rod portion of 1.0 mm or less in diameter and 0.2 mm or more in length; width of coverage K of a ground electrode on which a rectangular noble metal chip is welded satisfies a relation of &minus;d&lE;K&lE;0.5 mm (where, d represents the diameter of the end face of the center electrode); and width w of a portion of the discharge plane A which falls within a range corresponded to the axial extension of the end face B of the noble metal chip provided on the center electrode satisfies a relation of w<2.1&minus;K (in mm), where K is the foregoing width of coverage.

Spark plug

In order to provide a multielectrode spark plug which is excellent in resistance to fouling and in which the voltage required for producing a spark can be lowered, the tip portion of at least one of plural ground electrodes is positioned by the side of an annular front end face of an insulator to form a semi-creeping spark discharging gap elongating along the surface of the insulator with the tip portion of a center electrode, and the tip portions of the ground other electrodes form aerial spark discharging gaps with the tip portion of the center electrode.

Multielectrode spark plug

A spark plug is provided having a center electrode disposed in a metallic shell through an insulator so that the front end of the center electrode forms a spark gap with an outer electrode. A platinum tip is secured to the outer electrode positioned to oppose the front end of the center electrode. The outer electrode is provided with a heat-conductive core metal cladded with a matrix metal which is made of a nickel-based alloy containing 10-20 wt. % chromium. The platinum tip is welded to the outer electrode to form a welded portion between the platinum tip and the outer electrode and the platinum tip is positioned to terminate slightly short of the core metal so that the distance between a circumferential edge of the welded portion and a front end of the core metal is in the range 0.0 mm-2.0 mm measured lengthwise along direction the outer electrode.

Spark plug having a platinum tip on an outer electrode

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

Spark plug has a central electrode, an insulator provided exterior to the central electrode, main metallic shell provided exterior to the insulator in such a way that the central electrode protrudes from one end, and a ground electrode coupled at one end to the main metallic shell and which has the other end disposed to face the central electrode 3, with a chip being secured to either the central electrode or the ground electrode or both to form spark discharge gap g. The chip is made of a metal based on Ir which contains Rh in an amount ranging from 3 to 50 wt % (50 wt % being not inclusive).

A spark plug including a tubular insulator supported within a metallic shell, and a center electrode provided to axially extend within the insulator. An outer electrode is secured to a front end of the metallic shell so as to extend toward an elevational side of the center electrode. A first spark-erosion resistant noble metal tip is secured to an outer surface of the outer electrode, the outer electrode extending across a front open end of the metallic shell so as to form a spark gap between an extended end of the tip and the elevational side of the center electrode.

Spark plug and a method of making the same for an internal combustion

A method of making a spark plug involves securing an outer electrode to a metallic shell so that at least a portion of the outer electrode is directed inwardly of a front open end of the metallic shell. The outer electrode has an inner surface, an outer surface, and an end surface. A center electrode is supported in an insulator in the metallic shell. A spark-erosion resistant noble metal tip is attached to the outer surface of the outer electrode with a predetermined distance between an elevational side of the center electrode and one end of the spark-erosion resistant noble metal tip.

Method of making a spark plug for an internal combustion engine

In a spark plug, a cylindrical metallic shell has a tubular insulator in which a columnar center electrode is place, a front end of the center electrode extending beyond the insulator. A nobel metal portion is thermally bonded to an outer wall of the front end of the center electrode by means of laser beams so as to form a spark gap between the noble metal portion and a ground electrode which is extended from the metallic shell. The noble metal portion has a molten alloy layer in which the center electrode is melted into the noble metal portion, and a diffused alloy layer in which the noble metal portion is diffused into the center electrode, so that the molten alloy layer forms a spark discharge surface against a front end of the ground electrode.

Spark plug having a noble metal electrode portion

In a spark plug including a cylindrical metallic shell having an insulator in which a center electrode is placed, a front end of which somewhat extends beyond the insulator, a noble metal portion is bonded to an outer side wall of the front end of the center electrode by means of laser beams so as to form a spark gap between the noble metal portion and a ground electrode which is depended from the metallic shell. The noble metal portion has a molten alloy layer in which the center electrode is melted into the noble metal portion, and a diffused alloy layer in which the noble metal portion is diffused into the center electrode.

Spark plug and a method of making of same

In an electrode for a spark plug, an elongated blank metal is made of a nickel-based alloy and including a front surface. A firing tip is provided from a slug made of a noble metal, the slug being concentrically placed on the front surface of the elongated blank metal and laser beam welded to thermally melt the entire slug and thereby produce a thermal weld, so that the front surface of the elongated blank metal is partly fused together with the slug to form a melted portion with the front surface and the slug so as to contain the front surface within the melted portion in the range of 0.5 wt % to 80.0 wt %.

Electrode for a spark plug in which a firing tip is laser welded to a

A method of manufacturing a spark plug electrode, wherein a composite column is provided to have a heat-conductor core embedded in a metallic clad by means of extrusion. A firing tip is provided from a slug which is made of a noble metal. The slug is concentrically placed on an end surface of the metallic clad, and a laser beam welding is applied on the slug to thermally melt the entire the slug so that the end surface of the metallic clad is partly fused into the slug in the range of 0.5 wt % to 80.0 wt %.

Method of manufacturing a spark plug electrode

In a misfire detector device for use in internal combustion engine, an electrical interrupter circuit on-off actuates a primary current flowing through a primary circuit of an ignition coil to induce a spark plug voltage. A check diode is provided in a secondary circuit of the ignition coil to prevent a current flowing back to the ignition coil. The spark plug has a center electrode, a front end of which is projected from an insulator, and an outer surface area of the projected front end being 25 mm.sup.2 or more. A spark plug voltage detector circuit detects an attenuation time length of a spark plug voltage waveform presented subsequent to a predetermined time period occurring after an end of a spark action of the spark plug. On the basis of the attenuation time length, a distinction circuit determines whether a misfire occurs in a cylinder of an internal combustion engine.

Misfire detector device for use in an internal combustion engine

In a misfire detector device for use in internal combustion engine, an electrical interrupter circuit on-off actuates a primary current flowing through a primary circuit of an ignition coil to induce a sparkplug voltage which is applied to a multi-electrode type spark plug. A check diode or a series gap is provided in a secondary circuit of the ignition coil so as to prevent a current flowing back to the ignition coil. A sparkplug voltage detector circuit detects an attenuation time length of a sparkplug voltage waveform presented subsequent to a predetermined time period after an end of a spark action of the spark plug. On the basis of the attenuation time length, a distinction circuit determines whether a misfire occurs in a cylinder of an internal combustion engine.

In a multi-gap type spark plug for an internal combustion engine, the spark plug has a cylindrical metallic shell into which a tubular ceramic insulator is enclosed. The insulator has a tapered front leg portion, a front end of which extends beyond that of the metallic shell. A center electrode is enclosed into the insulator, having at a front end thereof, a filing tip extending beyond that of the insulator. A plurality of L-shaped outer electrodes each having a vertical piece and lateral piece, the vertical piece depending from the front end of the metallic shell to surround the front end of the insulator, while the lateral piece having an inner surface arranged in parallel with a front end surface of the insulator, and having an end tip terminated to oppose an outer surface of the firing tip through a spark gap established therebetween. A vertical distance between the front end surface of the insulator and the inner surface of the lateral piece of each outer electrode is determined to be within a dimension ranging from 0.3 mm to 1.2 mm.

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Nagoya, Japan

Junichi Kagawa