Denso Corporation

Daisuke Shimamoto

Daisuke Tanaka

Naoto Hayashi

Akimitsu Sugiura

Fumiaki Aoki

Masamichi Shibata

Kaori Doi

Shota Kinoshita

Yuya Abe

Yuuki Kawata

Kyosuke Fujita

Syuhei Nakashima

Keisuke Sugita

A spark plug includes: a cylindrical insulator; a center electrode that is held on an inner circumferential side of the insulator and includes a tip-end protruding portion that protrudes from the insulator toward a tip end side; a cylindrical housing that holds the insulator on an inner circumferential side; and a plug cover that is provided in a tip end portion of the housing so as to cover a pre-combustion chamber in which the tip-end protruding portion is arranged. The plug cover is provided with an injection hole that communicates the pre-combustion chamber to the outside. A positioning portion that performs positioning of the housing and the plug cover in a plug circumferential direction is provided in the housing and the plug cover.

Spark plug for internal combustion engine

A spark plug for an internal combustion engine includes a housing, an insulator, a center electrode, a ground electrode, and an auxiliary chamber forming portion. The ground electrode faces the center electrode from an outer peripheral side and forms a discharge gap between the ground electrode and the center electrode. An auxiliary chamber is formed inside the auxiliary chamber forming portion. A distance in an axial direction between the discharge gap and a distal end of the auxiliary chamber is equal to or greater than a maximum wall thickness of the auxiliary chamber forming portion. The auxiliary chamber forming portion includes injection holes. The injection holes are formed in a state where openings on an outer side are located closer to a distal end than openings on the auxiliary chamber side. At least one of the injection holes is an injection hole in the axial direction formed along an axial direction of a plug. When viewed in the axial direction of the spark plug, a center of the axial injection hole is eccentric from a central axis of the spark plug toward the discharge gap.

A spark plug includes a housing, a porcelain insulator, a center electrode, a ground electrode, and a prechamber-defining portion. The prechamber-defining portion has a prechamber formed therein. The prechamber-defining portion has a plurality of spray holes. At least one of the spray holes is an upstream spray hole which is arranged upstream of a plug center axis in a gas flow within a main combustion chamber and designed such that and an angle which an extension in an opening direction makes with an inner wall surface of the prechamber is selected to be larger than 90&#xb0;. A spark gap is formed upstream of a plug center axis in the gas flow within the main combustion chamber.

Internal combustion engine and spark plug

A spark plug includes a housing, an insulator, a center electrode, and an earth electrode. The earth electrode has a gap-forming surface which forms a discharge gap between the gap-forming surface and a tip surface of the center electrode. The insulator includes an insulator protrusion protruding on the tip side of the housing in a plug axial direction. At least one of cross-sections passing through a plug center axis and parallel to the plug axial direction is referred to as an axial parallel cross-section. The outer peripheral surface of the insulator protrusion includes an insulator inclined surface extending inward toward the tip in the plug axial direction, in a straight line or a curve that is convex inward, in the axial parallel cross-section. In the axial parallel cross-section, a virtual straight line passing through both ends of the insulator inclined surface passes through the gap-forming surface.

Spark plug for internal combustion engines

A spark plug includes a ground electrode facing a distal end surface of a center electrode. In a main body of the ground electrode, a first slanted surface is formed at a portion on a side facing the distal end surface and upstream of the center electrode relative to the airflow, a facing portion, a second slanted surface is formed at a portion on a side opposite to the side facing the distal end surface and upstream of the center electrode relative to the airflow, and when T represents a thickness of the main body of the ground electrode and Su represents a distance from a connection between the first slanted surface and the second slanted surface to the facing portion, 2T/16&#x2264;Su&#x2264;8T/16.

Spark plug including a ground electrode having slanted surfaces and a facing portion facing a distal end surface of a center electrode

An ignition apparatus for an internal combustion engine includes a center electrode, a ground electrode, an insulator, a housing, and an insulator protective wall portion. The ground electrode is disposed such that a discharge gap is formed between the ground electrode and the center electrode. The insulator holds the center electrode on an inner side of the insulator. The housing holds the insulator on an inner side of the housing. The insulator protective wall portion is arranged to surround an outer circumference side of a distal end portion of the insulator. A distal end of the insulator protective wall portion is positioned further towards a distal end side than a distal end of the insulator is and further towards a proximal end side than a distal end of the center electrode is. The insulator protective wall portion includes an inward protruding portion that protrudes towards a side surface of the center electrode.

Ignition apparatus for internal combustion engine

In a spark plug, a discharge gap is formed between a ground electrode and a central electrode. The ground electrode has a rod-shaped part and an opposing part. The opposing part faces the central electrode, and has a flat surface part and a slope surface part. The slope surface part is formed on a part of the opposing part in an extending direction of the ground electrode, and formed on the opposing part and gradually separated from the central electrode along a width direction of the opposing part. The spark plug has a ratio V/W within a range of 0.5&#x3c;V/W&#x3c;2.0. V indicates a length of the opposing part measured in a gap formation direction in which the central electrode, the discharge gap and the opposing part are arranged in order. W indicates a length of the opposing part in the ground electrode width direction.

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Kariya, Japan

Daisuke Shimamoto