SPARK PLUG

• Main Authors: NAKADA TAKUTO, SUMOYAMA DAISUKE
• Format: Patent
• Language: English; Japanese
• Published: 28.12.2016
• Subjects: BASIC ELECTRIC ELEMENTS; CORONA DEVICES; ELECTRICITY; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARK GAPS; SPARKING PLUGS

PROBLEM TO BE SOLVED: To provide a durable spark plug.SOLUTION: A chip 4 provided on at least one of a center electrode 4 and a ground electrode includes a body portion 41, a covering layer 43, and a high resistivity layer 42. The main part contains the most amount of Ir and contains Rh or Pt at 2 mass% or more. When a metal element having a crystal structure different from the crystal structure of Ir, Rh, and Pt at room temperature is defined as the group A element, the group A element is not contained or the total content of the group A element is 24 mass% or less and the total content of the group A elements excluding Ru is less than 7 mass%. The high specific resistance layer is provided on the side peripheral surface of the main body portion, and the Ni content is higher than the Ni content rate of the main body portion, is less than 50 mass%, and its own thickness is 2 μm or more and 45 μm or less. The coating layer is provided on the side peripheral surface of the high resistivity layer and contains Ni of 50 mass% or more, its own thickness is 3 μm or more and 20 μm or less. The specific resistance of the chip at room temperature is 20×10Ωm or less.SELECTED DRAWING: Figure 2 【課題】耐久性に優れたスパークプラグを提供する。【解決手段】中心電極４と接地電極の少なくとも一方に設けられたチップ４が本体部４１と被覆層４３と高比抵抗層４２とを含む。本体部はＩｒを最も多く含有し、かつＲｈ又はＰｔを2質量％以上含有し、Ｉｒ、Ｒｈ、及びＰｔの室温での結晶構造とは異なる結晶構造を有する金属元素をＡ群元素としたとき、前記Ａ群元素を含有しないか、或いは前記Ａ群元素の合計含有率が24質量％以下、かつＲｕを除くＡ群元素の合計含有率が7質量％未満である。高比抵抗層は本体部の側周面に設けられ、Ｎｉの含有率が本体部のＮｉ含有率より多く、50質量％未満であり、自身の厚さが2μｍ以上45μｍ以下である。被覆層は高比抵抗層の側周面に設けられ、Ｎｉを50質量％以上含有し、自身の厚さが3μｍ以上20μｍ以下であり、前記チップの室温における比抵抗が20×10−８Ωｍ以下である。【選択図】図２