Denso Corporation

Kenka Tsubota

Ken Hanashi

Keiji Kanao

Tsunenobu Hori

Satoru Kadowaki

Hiroya Ishiguro

Hirotaka Aida

A spark plug includes a tubular metal shell, an insulator, a cylindrical center electrode, and a ground electrode. The ground electrode has an inclined portion, a straight portion, and a bend between the inclined and straight portions. The inclined portion extends obliquely with respect to the axial direction of the center electrode from a base end of the ground electrode, which is joined to an end of the metal shell, to the bend that is positioned closer to the center electrode in the radial direction of the center electrode than the base end. The straight portion extends substantially parallel to the axial direction of the center electrode from the bend to a tip end of the ground electrode. The straight portion has an inner side surface facing the side surface of an end portion of the center electrode through a spark gap in the radial direction of the center electrode.

Spark plug for internal combustion engine and manufacturing method thereof

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

Spark plug for internal combustion engine

Growing community of inventors

Chiryu, Japan

Kenka Tsubota