Denso Corporation

Hiroya Ishiguro

Tsunenobu Hori

Ken Hanashi

Satoru Kadowaki

Kenka Tsubota

Hirotaka Aida

Masaya Nakamura

Kozo Takamura

Toshikazu Shimizu

Tomoaki Yonekura

A spark plug for an internal combustion engine has a cylindrical insulator, a center electrode held inside of the insulator, and, a terminal portion held inside of the insulator and electrically connected to the center electrode. The insulator has a insertion portion arranged closer to the base end side than the housing is, the insertion portion being inserted into a cylindrical plug cap. The insertion portion has a non-fit portion formed at the base end of the insulator, and, a fit portion formed to the head end side of the non-fit portion, an outer diameter of the non-fit portion being equal to or smaller than an inner diameter of the plug cap, the fit portion being fitted in the inner periphery surface of the plug cap.

Spark plug for internal combustion engine and ignition system having spark plug

A spark plug includes a main fitting having a first, second, and third portions adjacent to each other. The spark plug further includes an insulator having a first opposing portion with a predetermined portion opposed to the first portion with a first interval, a second opposing portion with a second portion opposing the second portion with a second interval, and a third opposed portion opposed to the third portion. A connecting portion between the second opposing portion is supported by a support portion, and a value obtained by dividing the first interval by a length from the support portion to a rear end portion of the predetermined portion is configured to be smaller than a value obtained by dividing the second interval by a length from the support portion to a rear end portion of the second opposed portion.

Spark plug and semi-finished product thereof

The spark plug has a configuration satisfying the relationships of B&#x2267;0.7A and 0.3 mm&#x2266;A&#x2266;0.6 mm, where B is an axial thickness along the central axis line Q of the weld portion formed between the base material electrode and the noble-metal chip, and A is an axial distance along the central axis line Q between the intersection points Pand X. The intersection point Pis a point at which a phantom axis line radially distant from the central axis line Q by D/2 (D being a diameter of the noble-metal chip) intersects with the boundary line between the weld portion and the noble-metal chip. The intersection point X is a point at which an extension of the contour line of the base material electrode in the vicinity of the weld portion intersects with a boundary line between the weld portion and the base material electrode.

Spark plug for internal combustion engine and method for manufacturing same

A method of manufacturing a spark plug having an attachment fitting, an insulator, a center electrodeand an earth electrode. While fixed to attachment fitting, earth electrodehas a convex partformed by projecting a part of an opposed surfacetoward center electrode, and a concave partformed toward the opposed surfacefrom the earth electrode's back surface. The convex partis disposed so that the extension of a shaft center of the convex partpasses through the area in which the concave partis formed. The relation Ss is realized when an area of an opening of the concave partis set to Sand an average cross-section area of a cross section of the convex partperpendicular to an axial direction of the spark plug is set to s.

Method for manufacturing spark plug for internal-combustion engine

A spark plug for an internal-combustion engine comprises an attachment fitting, an insulator, a center electrodeand an earth electrode. While fixed to the attachment fitting, the earth electrodehas a convex partformed by projecting toward the center electrodea part of the opposed surface, which faces the center electrode, of the earth electrode and a concave partformed toward the opposed surfacefrom the earth electrode's back surfacewhich is the reverse side of the opposed surfaceof the earth electrode. The convex partis disposed so that the extension of a shaft center of the convex partmay pass through the area in which the concave partis formed. A relation of S&#x3e;=s is realized when an area of an opening of the concave partis set to Sand an average cross-section area of a cross section of the convex partperpendicular to an axial direction of the spark plug is set to s.

Spark plug for internal-combustion engine and method for manufacturing the same

In producing a spark plug including a central electrode having a first chip including noble metal and an earth electrode having a second chip including the noble metal, a spark gap being disposed between the first and second chips, a chip including the noble metal. The chip is welded to an end of the central electrode and to an end of the earth electrode. The welded chip is cut to form the first and second chips and the spark gap.

Method of producing a spark plug

An improved structure of a spark plug is provided for improving heat dissipation from an Ir-alloy chip attached to a ground electrode. The Ir-alloy chip works to a sequence of sparks between itself and the tip of a center electrode mounted in a metal shell and is embedded in a center electrode-facing surface of the ground electrode, thereby enhancing the transmission of heat produced in the Ir-alloy chip to the metal shell through the ground electrode.

Growing community of inventors

Kariya, Japan

Hiroya Ishiguro