Ngk Spark Plug Company, Limited

Niterra Co., Ltd.

Daisuke Sumoyama

Tsutomu Shibata

Tatsuya Gozawa

Kazuki Ito

Tomoo Tanaka

Tomonori Kanemaru

Takuto Nakada

Osamu Yoshimoto

Takaaki Kikai

Yusuke Kawashima

Masayuki Segawa

Kengo Hattori

Magoki Shimadate

Kaito Nakamura

Tomo-O Tanaka

A spark plug which is reduced in consumption of a discharge member, thereby having a longer service life. This spark plug is provided with: a first electrode that comprises a discharge member; and a second electrode that faces the discharge member, with a spark gap lying therebetween. The discharge member is mainly composed of Ru, while containing 0.5% by mass to 30% by mass of Ni or Co.

Spark plug

A spark plug capable of avoiding a discharge member bonded to a base material from peeling off easily is provided. The spark plug includes: a first electrode including a base material and a discharge member having at least a portion thereof bonded to the base material with a diffusing layer interposed therebetween; and a second electrode facing the discharge member with a spark gap interposed therebetween. The base material contains 50 mass % or more of Ni, 8 mass % or more and 40 mass % or less of Cr, 0.05 mass % or more and 2 mass % or less of Si, 0.01 mass % or more and 2 mass % or less of Al, 0.01 mass % or more and 2 mass % or less of Mn, 0.01 mass % or more and 0.1 mass % or less of C, and 0.001 mass % or more and 0.04 mass % or less of Fe.

In a spark plug, a base material contains 50 mass % or more of Ni, 8 mass % or more and 40 mass % or less of Cr, 0.01 mass % or more and 2 mass % or less of Si, 0.01 mass % or more and 2 mass % or less of Al, 0.01 mass % or more and 2 mass % or less of Mn, 0.01 mass % or more and 0.1 mass % or less of C, and 0.001 mass % or more and 5 mass % or less of Fe. A discharge member contains at least Pt of a P group (Pt, Rh, Ir, and Ru) and Ni. The atomic concentration K of the P group of the discharge member, the atomic concentration L of the P group of the base material, the atomic concentration M of Ni of the discharge member, and the atomic concentration N of Ni of the base material satisfy (K+L)/(M+N)&#x2264;1.14.

A spark plug including a center electrode with a tip welded to a front end portion with a fused portion therebetween. The front end portion contains Ni, Cr, and at least one element selected from a group B consisting of Mn, Si, Al, Ti, rare earth elements, Hf, and Zr. Ni is present in the largest proportion, and Cr is present in the second largest proportion and in an amount of 12% by mass or more. The at least one element selected from the group B is present in a total amount of 0.1% by mass or more. The front end portion satisfies f/e&#x2264;0.15 and m/e&#x2264;0.015, where f is the Fe content, e is the sum of the Cr, Si, and Al contents, and m is the Mo content.

A spark plug comprising: a first electrode including a tip containing 1r as a main material, and a base member to which the tip is joined; and a second electrode opposed to the tip with a spark gap therebetween. The number of crystal grains appearing in a range of 0.25 mmon an arbitrary cross-section of the tip in a first direction connecting the tip and the second electrode within the spark gap, is not less than 20. When a length of each of the crystal grains in the first direction is denoted by Y, and a length of each of the crystal grains in a second direction perpendicular to the first direction is denoted by X, 5 &#x3bc;m&#x2264;X&#x2264;100 &#x3bc;m and Y/X&#x2265;1.5 are satisfied.

Spark plug and manufacturing method therefor

An electrode base material of the spark plug contains not less than 50 wt. % of Ni. A discharge member contains not less than 45 wt. % of Pt, and at least one of Ni and Rh. An intermediate member contains Pt and Ni. In the discharge member, a content of Pt is highest, and a total content of Pt, Rh, and Ni is not less than 92 wt. %. In the intermediate member, a content of one of Pt and Ni is not less than 50 wt. %, a content of Ni is higher than a content of Ni in the discharge member, and a total content of Pt, Rh, and Ni is not less than 85 wt. %. A thickness of the diffusion layer formed between the discharge member and the intermediate member is not less than 0.002 mm and not more than 0.065 mm.

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 having a tip provided on at least one of a center electrode and a ground electrode. The tip includes a body portion, a coating layer, and a high specific resistance layer. The body portion contains mostly Ir. The high specific resistance layer is provided on a side peripheral surface of the body portion, has a Ni content greater than the Ni content of the body portion and less than 50 mass %, and has a thickness of 2 &#x3bc;m or greater and 45 &#x3bc;m or less. The coating layer is provided on a side peripheral surface of the high specific resistance layer, contains 50 mass % or more of Ni, and has a thickness of 3 &#x3bc;m or greater and 20 &#x3bc;m or less. The tip has a specific resistance of 20&#xd7;10&#x3a9;m or less at room temperature.

A spark plug having a tip formed of an alloy containing Pt. The tip contains not less than 6 mass % of Rh, at least one element selected from an R group consisting of Rh, Re, Ir, Ru, W, Mo, and Nb, not less than 5 mass % of Ni, and at least one element selected from an N group consisting of Ni, Co, Fe, and Cu. The tip contains Rh most among the elements of the R group, and contains Ni most among the elements of the N group. The total of contents of Pt, Rh, and Ni is not less than 91 mass %, and the total of contents of Pt, the R group, and the N group is not less than 95 mass %. A value obtained by dividing the content of the R group by the content of the N group is not less than 0.7 and not greater than 8.

A spark plug that includes a center electrode and a ground electrode. The center electrode is disposed providing a gap with the center electrode. At least one of the center electrode and the ground electrode includes a tip forming the gap. The tip includes a main body portion and a front surface layer. A composition of the main body portion is Pt as a main constituent and Rh of 5 mass % or more and Ni of 0 mass % or more to less than 8 mass %. The front surface layer is disposed at least at a surface radially outside of an axial line extending in a direction from a center of the main body portion to the gap. The front surface layer contains Ni of 8 mass % or more and has a thickness of 2 &#x3bc;m or more.

A spark plug wherein least one of a center electrode and a ground electrode includes a shaft portion and an electrode tip joined to one surface of the shaft portion. The shaft portion includes a first core formed of a material containing copper and a first outer layer that is formed of a material having higher corrosion resistance than the first core and covers at least part of the first core. The electrode tip includes a second outer layer that is formed of a material containing a noble metal and forms the outer surface of the electrode tip and a second core that is formed of a material having a higher thermal conductivity than the second outer layer and is at least partially covered with the second outer layer.

A spark plug having a center electrode and a ground electrode that form a gap therebetween. At least one of the center electrode and the ground electrode includes a portion formed of a nickel alloy containing nickel as a major component and 20% by mass or more of chromium. In the portion, formed of the nickel alloy, of the electrode, the content of silicon is 0.1% by mass or more, the total content of one or more particular elements selected from the group consisting of rare earth elements is 0.01% by mass or more, and the area percentage of voids in the total area of a cross-section parallel to a longitudinal direction is 1% or less.

At least one of a center electrode and a ground electrode of a spark plug includes an electrode body, an electrode tip, and a welded portion formed between the electrode body and the electrode tip. The electrode tip includes a cover layer that covers at least a side surface of a tip body, and the cover layer is formed of IrAl. On a section formed by cutting the electrode tip near a boundary with the welded portion, an area of the tip body is represented by Sa. An area of a projection on the section of a non-contact portion of an opposite surface of the tip body not in contact with the welded portion is represented by Sb. In this case, Sa&#x2212;Sb corresponds to 35% or more of Sa.

A spark plug comprising a center electrode, a ground electrode disposed on the center electrode across a gap, and a tip joined to an opposed surface of the ground electrode that is opposed to the center electrode, the tip has a discharge layer and a relieving layer, the relieving layer is formed from a Pt&#x2014;Ni alloy and joined to the opposed surface via a diffusion layer, the discharge layer is formed from a Pt&#x2014;Rh alloy and joined via a clad diffusion layer to a side of the relieving layer opposite to a side of the relieving layer at which the ground electrode is joined, and 0.81&#x2266;A/B&#x2266;1.21 is satisfied when an average cross-sectional area of the discharge layer is A mmand an average cross-sectional area of the relieving layer is B mm, and a method for producing the spark plug.

Spark plug and method for producing the same

An object of the present invention is to provide a spark plug which includes, at at least one of a center electrode and a ground electrode, a tip having excellent spark wear resistance in a high temperature environment, thereby having excellent durability. A spark plug includes a center electrode and a ground electrode disposed with a gap provided between the center electrode and the ground electrode. At least one of the center electrode and the ground electrode includes a tip which defines the gap. The tip includes a metal base material containing Ir as a main component, and oxide particles containing at least one of oxides having a perovskite structure represented by general formula ABO(A is at least one element selected from elements in group 2 in a periodic table, and B is at least one element selected from metal elements). When a cross section of the tip is observed, an area proportion of the oxide particles is not lower than 1% and not higher than 13%.

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Nagoya, Japan

Daisuke Sumoyama