Ngk Spark Plug Company, Limited

Yusuke Kawashima

Naoki Nishio

Yusuke Tanahashi

Tatsuya Gozawa

Daisuke Sumoyama

Hiroyuki Hazama

Magoki Shimadate

A spark plug including a center electrode that has a large-diameter portion having an outside diameter that is largest in the center electrode. The large-diameter portion is retained at a rear facing surface in an axial hole of an insulator. A metal shell has a diameter increased portion on a rear end side with respect to the center electrode, the diameter increased portion having an inside diameter that is increased toward the rear end side. The insulator has a first portion which is a portion of the insulator in a region from a rear end of the rear facing surface to a front end of the diameter increased portion. The first portion has a thickness that is the largest in the region, and is disposed at least on an outer periphery of the large-diameter portion.

Spark plug with insulator with particular shape

In the spark plug, an insulator is held by a metal shell via a packing. The packing includes a base material and a metal layer formed on a surface of the base material. In a cross section including the axial line, of distances between end points of the metal layer on a first contact surface of the insulator that contacts with the metal layer and first points which are intersections of the first contact surface and first perpendiculars extending to the first contact surface from first corners at which a first surface and third surfaces of the base material intersect each other is longer than a thickness of the metal layer at a middle position on the third surface that corresponds to half a length measured along the third surface.

Spark plug

Disclosed is a spark plug having a ground electrode in which a weld zone is formed a tip and electrode base. The weld zone has: a back region exposed at an opposite surface of the electrode base; a joint region at which the tip is joined; and a connection region connects the joint region and the back region without being exposed at side surfaces of the electrode base. In a cross section of the ground electrode taken through the side surfaces of the electrode base along a plane passing through the centers of the top and bottom surfaces of the tip, a value of a width of the top surface of the tip being divided by a width of the facing surface of the electrode base is greater than 0.3, and a maximum width of the connection region is larger than a width of the back region.

Spark plug and production method therefor

An electrode tip for a spark plug, wherein Pt is contained as a main component, 7% by mass or more of Rh is contained, and a total content of Pt and Rh is greater than or equal to 95% by mass. The electrode tip includes: a narrow portion having the same cross-sectional shape in a direction of an axis; and a wide portion which is adjacent to the narrow portion and has a cross-sectional area, in a radial direction, which is greater than the narrow portion.

Electrode tip for spark plug, and spark plug

A spark plug comprises a ground electrode including a chip whose one end has a cylinder shape having a diameter A from 0.8 to 1.2 mm and whose main component is a noble metal, and an electrode base material. In the ground electrode, a portion of the other end of the chip is joined to the electrode base material through a fused portion. The spark plug also comprises a chip-and-base-material interface in which the chip and the electrode base material contact each other and which is surrounded by the fused portion. In a cross section passing through a center axis, a distance between an end point Palocated on the chip-and-base-material interface and an end point Palocated on an interface between the chip and the fused portion is equal to or greater than 0.7 times the diameter A.

Growing community of inventors

Kakamigahara, Japan

Yusuke Kawashima