Denso Corporation

Yasushi Kawashima

Nobuo Abe

Masamichi Shibata

Ken Hanashi

Hirofumi Suzuki

Toshikazu Shimizu

Tsunetoshi Goto

A gasket for attaching a spark plug to an internal combustion engine, the gasket having an annular portion. The annular portion is annular to surround the spark plug, and has contact surfaces on both axial ends, one of the contact surfaces being to contact the spark plug, the other being to contact the internal combustion engine. The annular portion is composed of copper alloy containing aluminum oxide. The aluminum oxide content of the copper alloy is 0.3 wt % or more, and 0.7 wt % or less.

Gasket for attaching spark plug and ignition system

A spark plug for internal-combustion engines equipped with a center electrode and a ground electrode is provided. In the spark plug, the ground electrode is fixed to a mount fitting, while the ground electrode has a convex portion. The convex portion is made of a part of base materials of the ground electrode where the part is facing the center electrode, and is projected toward the center electrode. The convex portion has a fusion solidification part made of precious metal materials and a part of the base materials melted together and solidified at least on part of an electric discharge surface facing the center electrode.

Spark plug for internal combustion engines and method for manufacturing the spark plug

A spark plug fitted to a cylinder head has a center electrode with a noble metallic tip portion having a sectional area Sbetween 0.07 mmand 0.95 mmand a melting point of 2000&#xb0; C. or more, and a ground electrode with a noble metallic tip portion having a sectional area Sand a melting point of 1700&#xb0; C. or more. The plug has a length H ranging from 6.5 mm and 10 mm between the head and the tip portion of the center electrode, a length G ranging from 1.1 mm and 2.0 mm between the tip portions, a length J between the head and a housing, a length F satisfying J&#x2266;F&#x2266;H&#x2212;1.0 mm between the head and an insulator, and a pocket clearance P satisfying P&#x2267;1.1&#xd7;(G+0.0345&#xd7;S+0.0327&#xd7;S) between the housing and the insulator.

Spark plug for internal combustion engine

A spark plug is provided which is designed to be compact without sacrificing a mechanical strength of a porcelain insulator. The spark plug includes a metal shell having a base end and a top end. The porcelain insulator is made of a hollow cylinder which includes a body and an insulator head. The body is retained within the metal shell. The insulator head extends from the base end of the metal shell in a lengthwise direction of the porcelain insulator and has a length made up of a major body leading to the body of the porcelain insulator and an end portion lying far away from the body. The major body has an outer diameter D, an inner diameter D, and a section modulus Z at a smallest-outer diameter portion thereof which meet relations of 7.1 mm&#x2266;D&#x2266;8.8 mm, D&#x2267;2.8 mm, and Z&#x2267;33 mm.

Spark plug with increased durability

In a spark plug for an internal combustion engine, an insulator is vided at its inside with a center electrode. A tubular housing is disposed to surround an outer periphery of the insulator. An annular space portion is provided between the housing and the outer periphery of the insulator. A powder filling is filled in the annular space portion so as to be formed as a filled portion therein. The powder filling is composed of a plurality of filling grains. 80 weight percent and over of the filling grains, before the powder filling is filled in the annular space, have a range from 100 to 1000 &#x3bc;m in grain diameter, respectively.

Spark plug with powder filling

A spark plug defines a spark gap G in a range of 0.2 mm&lE;G<0.4 mm, between a noble metal chip disposed on a central electrode and an earth electrode. The noble metal chip has a groove portion facing the earth electrode so that a space, which is larger than a sphere having a diameter equal to or larger than 0.4 mm, is provided in the spark gap G. As a result, a flame core having a diameter equal to or larger than 0.4 mm can be held in the space not to be quenched, resulting in high ignition property of the spark plug.

Spark plug having specified spark gap dimensional relationships

A spark plug has an insulator having a through hole extending in an axial direction thereof and an insulator leg portion at an end thereof, a resistor disposed in the through hole, a central electrode disposed in the through hole to face a central electrode side end face of the resistor and protruding from an insulator end face of the insulator leg portion, and a housing holding the insulator. A length between the insulator end face and the central electrode side end face of the resistor is equal to or larger than 1.5 times as large as a length of the insulator leg portion in the axial direction. Accordingly, temperature at a contact portion between the resistor and the central electrode is prevented from being increased, resulting in long life of the spark plug.

Spark plug with specific measured parameters

A hole is formed on a central electrode. A chip has a leg portion. A distal end of the leg portion is entirely united with a bottom surface of the hole by resistance welding. A plurality of fused portions are formed at a boundary between the chip and the central electrode. The fused portions integrate the chip and the central electrode by fusing them together. Each fused portion extends in a radial direction of the chip. The entire periphery of a pointed end of each fused portion penetrates radially inside the outer cylindrical surface of the leg portion of the chip.

Growing community of inventors

Mie-ken, Japan

Yasushi Kawashima