公开(公告)号：US10340667B2

公开(公告)日：2019-07-02

申请号：US16156337

申请日：2018-10-10

Applicant: NGK SPARK PLUG CO., LTD.

Inventor： Toshinori Takeichi ,  Kuniharu Tanaka ,  Hirokazu Kurono ,  Haruki Yoshida ,  Hironori Uegaki

IPC: H01T13/41 ,  H01T13/34 ,  H01T21/02

Abstract: A spark plug having a resistor disposed between a metal terminal and a center electrode so as to be electrically connected to the metal terminal and the center electrode, wherein the resistor is in contact with an inner circumferential surface of the insulator. On a cross section taken along the axial line so as to include the axial line, in a case where a plurality of points are plotted at predetermined intervals in a direction of the axial line so as to be present on a partial boundary line, within an arbitrary range in the direction of the axial line, of a boundary line between the insulator and the resistor, and a regression line is drawn by a least-squares method with use of the plurality of points, an average value of distances in a direction perpendicular to the regression line between the regression line and the partial boundary line is 0.1 to 0.3 μm.

公开(公告)号：US10305260B2

公开(公告)日：2019-05-28

申请号：US16033661

申请日：2018-07-12

Applicant: NGK SPARK PLUG CO., LTD.

Inventor： Haruki Yoshida ,  Kuniharu Tanaka ,  Toshinori Takeichi ,  Michitaka Yamada ,  Yusuke Nomura

IPC: H01T13/34 ,  H01T13/52 ,  H01T13/46

Abstract: Disclosed is a spark plug including: an insulator having an axial hole formed along an axis of the spark plug; a center electrode disposed in a front end side of the axial hole; and a metal shell fixed around an outer circumference of the insulator, with a front end portion of the insulator protruding frontward from a front end of the metal shell. The front end portion of the insulator consists only of a first section and a second section located adjacent to and frontward of the first section and having an inner diameter larger than that of the first section. The second section has a chamfered area formed on an inner circumferential surface thereof so as to continue to a front end of the insulator.