SPARK PLUG

• Main Authors: KUKI HIROAKI, FUKUZAWA REIMON
• Format: Patent
• Language: English; Japanese
• Published: 21.01.2016
• Subjects: BASIC ELECTRIC ELEMENTS; BLASTING; COMBUSTION ENGINES; CORONA DEVICES; ELECTRICITY; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES; HEATING; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS; IGNITION, OTHER THAN COMPRESSION IGNITION, FORINTERNAL-COMBUSTION ENGINES; LIGHTING; MECHANICAL ENGINEERING; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARK GAPS; SPARKING PLUGS; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES; WEAPONS

PROBLEM TO BE SOLVED: To simultaneously achieve improvement of voltage resistance, suppression of central electrode oxidation and suppression of lateral spark.SOLUTION: A spark plug includes an insulator including a shaft hole extending along an axial line, and a central electrode inserted into the shaft hole. The insulator includes: a first columnar part; a truncated conical shape part which is formed at a front end side of the first columnar part and of which the outer diameter is reduced toward a front end side; and a second columnar part which is formed at the front end side of the truncated conical shape part. A diameter C of the central electrode is equal to or shorter than 2.2 mm. A total I of a volume of the truncated conical shape part and a volume of the second columnar part, a volume E of the central electrode from a rear end position of the truncated conical shape part to a front end position of the second columnar part in an axial direction and the diameter C satisfy I/E≥4.2333C-19.79C+24.869. 【課題】耐電圧性の向上と、中心電極の酸化の抑制と、横飛火の抑制とを同時に達成すること。【解決手段】スパークプラグは、軸線に沿って延びる軸孔を有する絶縁体と、軸孔内に挿入された中心電極とを備える。絶縁体は、第１円柱部と、１円柱部の先端側に形成され、先端側に向かって外径が縮小する円錐台形状部と、円錐台形状部の先端側に形成された第２円柱部とを備える。中心電極の直径Ｃは２．２ｍｍ以下である。円錐台形状部の体積および第２円柱部の体積の合計Ｉ、軸線方向における円錐台形状部の後端位置から第２円柱部の先端位置までの中心電極の体積Ｅ、並びに、直径Ｃが、Ｉ／Ｅ≧４．２３３３Ｃ２−１９．７９Ｃ＋２４．８６９を満たす。【選択図】図２