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：US09912125B2

公开(公告)日：2018-03-06

申请号：US15272561

申请日：2016-09-22

Applicant: NGK SPARK PLUG CO., LTD.

Inventor： Haruki Yoshida ,  Jumpei Isasa ,  Toshitaka Honda ,  Yutaka Yokoyama ,  Kuniharu Tanaka ,  Nobuyoshi Araki ,  Toshiki Kon

IPC: H01T13/38 ,  H01T13/18 ,  H01T13/60 ,  H01T21/02

CPC classification number: H01T13/38 ,  H01T13/18 ,  H01T13/60 ,  H01T21/02

Abstract: A spark plug includes an insulator, a center electrode, a metallic shell, and a ground electrode. The insulator contains not less than 90.0 mass % and not greater than 98.1 mass % of Al2O3 with respect to a total mass of elements, as reduced to oxides, contained in the insulator, and has a porosity not greater than 5%. Assuming that a porosity of the insulator after a heat treatment is B, a difference (B−A) of the porosities before and after the heat treatment is not greater than 3.5%. In the heat treatment, the insulator is placed in a furnace, and a temperature in the furnace is increased from a room temperature to 1400° C. at a temperature increase rate of 7° C./min and is held at 1400° C. for 30 minutes, and thereafter, the temperature is decreased from 1400° C. to 400° C. at a temperature decrease rate of 10° C. or less per 5 minutes and is decreased to the room temperature.

公开(公告)号：US10193311B2

公开(公告)日：2019-01-29

申请号：US15669536

申请日：2017-08-04

Applicant: NGK Spark Plug Co., LTD.

Inventor： Yutaka Yokoyama ,  Kuniharu Tanaka ,  Nobuyoshi Araki ,  Hirokazu Kurono ,  Toshimasa Saji ,  Yusuke Nomura ,  Jumpei Isasa

IPC: C04B35/10 ,  H01T13/18 ,  H01T13/38 ,  H01B3/12 ,  C04B35/111 ,  C04B35/626 ,  C04B35/634

Abstract: An alumina-based sintered body includes 92 mass % to 96 mass % of Al in terms of an oxide, and at least three elements selected from Group II elements, one of the at least three elements being 1.90 mass % or more of Ba in terms of an oxide. The alumina-based sintered body includes the following phases in a grain boundary phase present between alumina crystal grains: a first crystal phase containing Si and at least one of the Group II elements, and a second crystal phase containing Al and at least one of the Group II elements. In X-ray diffraction of the alumina-based sintered body, the maximum relative intensity of the first crystal phase and the maximum relative intensity of the second crystal phase are both 2 or above relative to the maximum diffraction intensity of the alumina crystal.

公开(公告)号：US09755404B2

公开(公告)日：2017-09-05

申请号：US15265152

申请日：2016-09-14

Applicant: NGK Spark Plug Co., LTD.

Inventor： Jumpei Isasa ,  Haruki Yoshida ,  Yutaka Yokoyama ,  Kuniharu Tanaka ,  Nobuyoshi Araki ,  Toshiki Kon

IPC: H01T13/38

CPC classification number: H01T13/38

Abstract: A spark plug includes an insulator made of an alumina sintered body containing Al2O3 as a principal component and additional components including; an Si component, a Ba component, an Mg component, a Ca component, an Sr component, and a rare earth element component. When the additional components are expressed as oxides including RSiO2, RBaO, RMgO, RCaO, RSrO, and RRE2O3, contents (mass %) of the sub-component satisfy expressions (1) to (6) as follows: (1) 1.0≦RSiO2≦5.0; (2) 0.5≦RBaO≦5.0; (3) 0≦RMgO≦0.18; (4) 0≦RMgO/RBaO≦0.36; (5) 0.3≦(RMgO+RCaO+RSrO)≦1.8; and (6) 0≦RRE2O3≦0.1.

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.