Denso Corporation

Yuji Kaji

Nobuo Abe

Naoto Hayashi

Yasuomi Imanaka

Atsushi Iwami

Tatsuya Oka

Ryo Tamura

Koji Yamanaka

Yuuta Kawashima

A ground electrode for a spark plug includes a ground electrode body arranged to face a center electrode of the spark plug. The ground electrode includes a discharge portion mounted on the ground electrode body to face the center electrode with a spark gap between the discharge portion and the center electrode. The discharge portion is made of a platinum-based alloy of platinum, rhodium, and nickel. A first mass percent of the rhodium contained in the platinum-based alloy of the platinum, the rhodium, and the nickel is within a first range from 2 wt % to 20 wt % inclusive. A second mass percent of the nickel contained in the platinum-based alloy of the platinum, the rhodium, and the nickel being within a second range from 2.5 wt % to 12 wt % inclusive.

Ground electrode for spark plug and spark plug

An ignition system has an ignition plug and an ignition control unit that controls the ignition plug. When an engine is in a predetermined operating state, the ignition control unit performs ignition control after top dead center to perform ignition after the compression top dead center. The ignition system has an airflow support structure that facilitates the flow of airflow through a discharge gap at least after the compression top dead center. The ignition system is configured such that due to the airflow support structure and the timing of the ignition, airflow at a flow rate of 5 m/s or more flows through the discharge gap during a spark period after top dead center, which is the generation period of the discharge spark in the ignition control after top dead center.

Ignition system

A spark plug is provided which includes a hollow cylindrical center electrode disposed inside a metal shell and a ground electrode joined to the metal shell. The ground electrode has an inner peripheral surface facing an outer peripheral surface of the center electrode. At least one of the outer periphery of the center electrode and the inner periphery of the ground electrode has formed therein at least one recess whose ends lies in a center-to-ground electrode facing region where the outer peripheral surface of the center electrode faces the inner peripheral surface of the ground electrode in a radial direction of the center electrode. This decreases voltage required by the spark plug to achieve discharge.

Spark plug having a recess formed in an electrode

A spark plug for an internal combustion engine that can improve bonding strength between a center electrode and a conductive glass is provided. The spark plug includes a housing, an insulator, a center electrode, a ground electrode, and a conductive glass. The center electrode has a locking portion that is locked from a base end side to a step portion formed on an inner peripheral surface of the insulator, and an electrode head that is closer to the base end side than the locking portion is. A concave portion is partially formed on the tip end surface of the electrode head. A concave contour, which is an outer peripheral contour of the concave portion when viewed in a plug axial direction, forms a closed curve which is spaced apart from a head contour, which is an outer peripheral contour of the base end surface of the electrode head, and surrounds a center axis (B) of the center electrode. The concave contour has an outward portion protruding toward the head contour and an inward portion protruding toward the center axis (B) of the center electrode.

Spark plug for internal combustion engine

A spark plug for internal combustion engines is provided which includes a porcelain insulator which is disposed inside a housing and extends outside a front end of the porcelain insulator. An annular ground electrode is secured to a front end portion of the housing. A pocket is created between a nose of the porcelain insulator and the housing. The housing has formed therein a plurality of vent holes which are located outside the ground electrode in a radial direction of the housing and communicate between the pocket and a combustion chamber of the engine. The vent holes include a first vent hole and a second vent hole which are different in opening area from each other, thereby enhancing scavenging of the pocket to ensure the stability of operation of the spark plug.

Growing community of inventors

Kariya, Japan

Yuji Kaji