Ngk Spark Plug Company, Limited

Hideki Teramura

Tomoaki Kato

Mamoru Musasa

Kazuyoshi Torii

Wataru Matsutani

Junichi Kagawa

Hiroyuki Kimata

Kiyohiro Kondo

A ground-electrode spark portionis formed from a noble metal which contains Pt as a main component, and is joined to a main metal portion of the ground electrodevia an alloy layer which has a thickness ranging from 0.5 &#x3bc;m to 100 &#x3bc;m and in which the noble metal that constitutes the ground-electrode spark portionand the metal that constitutes the main metal portion of the ground electrodeare alloyed with each other. The ground-electrode spark portionis configured such that a distal end surfacefacing a spark discharge gap g is smaller in diameter than a bottom surfacejoined to the ground electrode; and the distal end surfaceis protrusively located beyond the side surfaceof the ground electrode. When the ground-electrode spark portionis viewed in plane from the distal end surface, a portion of the surface of the ground-electrode spark portionis viewed as a peripheral exposed-region surfacewhich is exposed on the side surfaceof the ground electrodeso as to surround the distal end surface

Spark plug and method for manufacturing the spark plug

A ground-electrode spark portionis formed from a noble metal which contains Pt as a main component, and is joined to a main metal portion of the ground electrodevia an alloy layer which has a thickness ranging from 0.5 &#x3bc;m to 100 &#x3bc;m and in which the noble metal that constitutes the ground-electrode spark portionand the metal that constitutes the main metal portion of the ground electrodeare alloyed with each other. The ground-electrode spark portionis configured such that a distal end surfacefacing a spark discharge gap g is smaller in diameter than a bottom surfacejoined to the ground electrodeand the distal end surfaceis protrusively located beyond the side surfaceof the ground electrode. When the ground-electrode spark portionis viewed in plane from the distal end surfacea portion of the surface of the ground-electrode spark portionis viewed as a peripheral exposed-region surfacewhich is exposed on the side surfaceof the ground electrodeso as to surround the distal end surface

A spark plug used in an automotive internal combustion engine. The spark plug includes a center electrode. An insulator is disposed around the center electrode. A metal main body is disposed around the insulator. A ground electrode has a first end section connected to the metal main body, and a second end section located opposite to the center electrode. Additionally, a tip is formed of an alloy whose main component is Ir. The tip is secured to the ground electrode and serving as a spark consumption-resistant electrode material. The tip has an axis directed to the center electrode. In the spark plug, a molten and solidified section formed of alloy is disposed to fix the tip to the ground electrode. The molten and solidified section includes a surrounding molten and solidified section located surrounding a peripheral surface of a major part of the tip embedded in the ground electrode.

Spark plug having a welded electrode and the method of producing the same

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

A tip portion of a center electrode of a spark plug includes a tapered portion which is tapered such that the diameter reduces axially frontward. A convex portion is formed at an axially intermediate position of the tapered portion so as to project radially outward with respect to an axis The axially measured distance L between the vertex of the convex portion (the convex vertex P) and the tip face D of an insulator is set to less than 0.5 mm. A heat release acceleration metal portion , which is made of Cu or an alloy that contains a predominant amount of Cu, is present at a position located a distance L of 1.5 mm as measured axially rearward from the convex vertex P in order to suppress spark erosion by lowering the temperature of the center electrode The heat release acceleration metal portion is formed such that an electrode base material , which encloses the heat release acceleration metal portion , has a wall thickness W of not less than 0.6 mm as measured at a position located 1.5 mm axially rearward from the convex vertex P.

A gasket for a threaded element such as a spark plug to be screwed into a threaded hole of a support such as a cylinder head is provided. The threaded element has a threaded portion and an annular seat portion. The gasket is installed on the threaded element and compressed between the seat portion and an outer surface of the support around a threaded hole, when the threaded element is screwed into the threaded hole, to provide a seal between the threaded portion and the threaded hole. The gasket is formed from an annular sheet metal and in the form of an annular strip of a cross section including a plurality of bent portions. The cross section is made by a plane including a center axis of the gasket and of a such a bent shape as to enable an imaginary reference line which is located on the above described plane and parallel with the center axis, to cross at least three portions of the cross section. The initial axial size of the gasket, i.e., the height of the gasket before the gasket is compressed, is at least 2.5 mm. When pressure within a proper pressure range is applied to the gasket, i.e., within a proper pressure range from 6 to 12 kgf/mm , a variation &Dgr;&agr; of compressive deformation &agr; of the gasket corresponding to advance or axial movement of the threaded element by at least 0.5 pitch of the thread, i.e., corresponding to movement of the threaded element resulting from at least 0.5 turn is retained.

Captive spark plug gasket

A glow plug includes an inner pole and a ceramic heating rod disposed in and fixed to an outer shell at uppermost and lowermost pole fixed portions A, C and a heating rod fixed portion D. A ratio of L /L is larger than 2, where L is a distance from the lower end of the inner pole to the lower end of the fixed portion C; and L is a distance from the lower end of the inner pole to the lower end of the fixed portion A. A ratio of L /L is smaller than 15, wherein L is a distance from a middle point between the lower end of the inner pole and the upper end of the heating rod to the lower end of the fixed portion C; and L is a distance from the above middle point to the upper end of the fixed portion D.

Growing community of inventors

Mie, Japan

Hideki Teramura