公开(公告)号：US10424901B2

公开(公告)日：2019-09-24

申请号：US16095788

申请日：2017-05-25

Applicant: NGK SPARK PLUG CO., LTD.

Inventor： Jumpei Isasa ,  Seiji Nakano ,  Hirokazu Kurono ,  Kuniharu Tanaka ,  Yutaka Yokoyama ,  Haruki Yoshida ,  Shun Kondo

IPC: H01T13/32 ,  H01T13/20 ,  H01T13/06

Abstract: Provided is a spark plug capable of ensuring fouling resistance with a simple configuration. An insulator includes a step portion formed on an outer circumferential surface thereof. A center electrode is arranged in an axial hole of the insulator. A cylindrical metal shell having a shelf portion formed on an inner circumferential surface thereof is arranged radially outside the insulator. The insulator further includes a front end portion located frontward of the step portion. An outer circumferential surface of the front end portion has an arithmetic average roughness of 0.5 μm or smaller in a circumferential direction. A recess is formed with a depth of 3 to 20 μm in at least part of an end surface and the outer circumferential surface of the front end portion so as to extend from the front toward the rear.

公开(公告)号：US10586627B2

公开(公告)日：2020-03-10

申请号：US16015967

申请日：2018-06-22

Applicant: NGK SPARK PLUG CO., LTD.

Inventor： Haruki Yoshida ,  Kuniharu Tanaka ,  Shun Kondo ,  Yutaka Yokoyama ,  Yusuke Nomura ,  Michitaka Yamada

IPC: H01B3/12 ,  C04B35/117 ,  H01T13/38 ,  H01T13/60 ,  C04B35/111

Abstract: The spark plug includes an insulator made from an alumina-based sintered body, and the insulator contains 90 to 98 wt % of an Al component in oxide equivalent. The insulator contains 1 to 5 wt % of an Si component, 0.1 to 1 wt % of an Mg component, 2 wt % or less of a Ca component, 0.3 to 6 wt % of a Ba component, and 0.11 to 5 wt % of a rare earth component, in oxide equivalent. In analysis using a scanning transmission electron microscope with a probe diameter of an electron beam set at 1 nm, Si and a rare earth element are detected at a crystal grain boundary having a thickness of 15 nm or less, and an alkaline earth metal at the crystal grain boundary is less than a detection limit.

公开(公告)号：US09653888B2

公开(公告)日：2017-05-16

申请号：US15272807

申请日：2016-09-22

Applicant: NGK SPARK PLUG CO., LTD.

Inventor： Yutaka Yokoyama ,  Kuniharu Tanaka ,  Katsuya Takaoka ,  Shun Kondo ,  Nobuyoshi Araki ,  Toshiki Kon ,  Haruki Yoshida ,  Jumpei Isasa ,  Hirokazu Kurono ,  Hironori Uegaki ,  Toshimasa Saji ,  Yusuke Nomura

IPC: H01T13/38

CPC classification number: H01T13/38 ,  H01T13/60

Abstract: A spark plug including an insulator containing not less than 92 mass % and not greater than 96 mass % of Al component in terms of oxide, wherein the insulator is formed from an alumina sintered body comprising alumina crystal and a grain boundary phase present between crystal grains of the alumina crystal. Assuming that mass contents of an Si component, an Mg component, a Ba component, and a Ca component in terms of oxide are represented by MSiO2, MMgO, MBaO, and MCaO, respectively, and a sum of MSiO2, MMgO, MBaO, and MCaO is represented by Mt, the grain boundary phase contains these components so as to satisfy conditions (1) to (4) as follows: (1) 0.17≦MSiO2/Mt≦0.47; (2) 0.005≦MMgO/Mt≦0.07; (3) 0.29≦MBaO/Mt≦0.77; (4) 0.03≦MCaO/Mt≦0.19.