公开(公告)号：US10985535B2

公开(公告)日：2021-04-20

申请号：US16936778

申请日：2020-07-23

Applicant: DENSO CORPORATION

Inventor： Hiroshi Araki ,  Naoto Hayashi ,  Hikaru Takashima

IPC: H01T13/34 ,  H01T13/32 ,  H01T13/41 ,  H01T21/02 ,  H01T13/20

Abstract: In a method for manufacturing a spark plug, a space on a proximal end side of a center electrode in a shaft hole of an insulator is filled with first electrically conductive glass powder. A space on the proximal end side of the first electrically conductive glass powder in the shaft hole is filled with resistor composition powder. A space on the proximal end side of the resistor composition powder in the shaft hole is filled with second electrically conductive glass powder. The first electrically conductive glass powder, the resistor composition powder, and the second electrically conductive glass powder are sintered in the shaft hole. Prior to filling of the resistor composition powder, at least one of the insulator and the first electrically conductive glass powder is placed in an uncharged state, or the insulator and the first electrically conductive glass powder are placed in the same charged state.

公开(公告)号：US10933559B2

公开(公告)日：2021-03-02

申请号：US15745208

申请日：2016-07-05

Applicant: DENSO CORPORATION

Inventor： Katsumasa Koeda ,  Hiroshi Araki

IPC: B28B11/24 ,  H01T13/38 ,  C04B35/111 ,  H01T21/02 ,  C04B35/626 ,  B28B3/02 ,  C01F7/02 ,  H01B19/00 ,  H01T13/20 ,  H01B17/56

Abstract: Provided are a molding step (A) of preparing an alumina molded body 11 from a molding raw material which contains an alumina raw material powder having an average particle size of 2 μm to 5 μm and a molding additive, and a sintering step (B) of preparing an alumina molded body 12, which becomes a spark plug insulator 1, by sintering the alumina molded body 11. At the sintering step (B), the alumina molded body 11 is conveyed to a continuous furnace 100 provided with a heating zone Z1 which is heated to 700° C. to 1600° C. by a heating means 401, followed by introducing oxygen gas to control the heating zone Z1 to have a high oxygen atmosphere with an oxygen concentration exceeding 20 mol %.

公开(公告)号：US09954344B2

公开(公告)日：2018-04-24

申请号：US15550458

申请日：2016-02-10

Applicant: DENSO CORPORATION

Inventor： Kenji Hattori ,  Masamichi Shibata ,  Toshiya Nakamura ,  Yasuomi Imanaka ,  Hirofumi Suzuki ,  Hiroshi Araki ,  Tomoyuki Watanabe ,  Shin Hase

IPC: H01T13/41 ,  H01T13/40 ,  H01C13/00 ,  F02P15/00

CPC classification number: H01T13/41 ,  F02P13/00 ,  F02P15/00 ,  H01C13/00 ,  H01T13/20

Abstract: A spark plug 1 includes a cylindrical housing, a cylindrical insulator, a center electrode, a terminal bracket, a ground electrode, and a resistor. The insulator is held on the inside of the housing. The center electrode 4 is held on the inside of the insulator, with a tip end being projected therefrom. The terminal bracket is held on the inside of the insulator, with a base end part and being projected therefrom. The ground electrode forms a spark discharge gap G between itself and the center electrode. The resistor contains carbon and is disposed on the inside of the insulator so as to be located between the center electrode 4 and the terminal bracket. In an axial direction X of the spark plug, the resistor has a higher carbon content in a first region positioned on a tip side, compared to a second region positioned on a base end side.

公开(公告)号：US09831638B2

公开(公告)日：2017-11-28

申请号：US15473685

申请日：2017-03-30

Applicant: DENSO CORPORATION

Inventor： Tomoyuki Watanabe ,  Hiroshi Araki

IPC: H01T13/41 ,  H01T13/39 ,  H01T13/32

CPC classification number: H01T13/41 ,  H01T13/20 ,  H01T13/32 ,  H01T13/39

Abstract: The spark plug has a shaft shaped center electrode, insulator, terminal fitting, ground electrode and resistor. The insulator has an axially penetrating shaft hole, and the center electrode is held in a tip end side of the shaft hole. The terminal fitting has a shaft and a terminal part. The shaft is held in a base end side of the shaft hole. The terminal part is projected from a base end of the shaft hole to a base end side of the spark plug. The ground electrode faces the center electrode in a tip end side of the shaft hole. The resistor is disposed between the center electrode and the terminal fitting in the shaft hole. An axial length L of the resistor is 15 mm≦L≦22.5 mm. An axial length T of the shaft satisfies a relation of 1.25≦T/L.

公开(公告)号：US09583916B2

公开(公告)日：2017-02-28

申请号：US15053256

申请日：2016-02-25

Applicant: DENSO CORPORATION

Inventor： Shota Imada ,  Hirofumi Suzuki ,  Hiroshi Araki

IPC: H01T13/38 ,  C04B35/00

CPC classification number: H01T13/38 ,  C04B35/00 ,  C04B35/111 ,  C04B35/117 ,  C04B2235/3201 ,  C04B2235/3206 ,  C04B2235/3208 ,  C04B2235/3222 ,  C04B2235/3418 ,  C04B2235/3472 ,  C04B2235/3481 ,  C04B2235/5409 ,  C04B2235/80 ,  C04B2235/9669

Abstract: An alumina sintered body has a main phase made of alumina crystals, a first dispersed phase made of MgAl2O4 dispersed in the main phase, and a second dispersed phase made of SiO2 and/or CaO dispersed in the main phase. A content ratio of the main phase is within a range from not less than 98% to less than 98%. The alumina sintered body satisfies a relationship of 100×I2/I1≧5.5%, where I1 indicates a maximum peak height intensity derived from alumina, and I2 indicates a maximum peak height intensity derived from MgAl2O4 in a X-ray diffraction of the alumina sintered body. An area ratio of the second dispersed phase on a surface of the alumina sintered body is not more than 15.2%. A spark plug has a central electrode, a ground electrode and an insulator made of the alumina sintered body having the specific features previously described.

Abstract translation: 氧化铝烧结体具有由氧化铝晶体制成的主相，分散在主相中的分散在MgAl 2 O 4中的第一分散相和分散在主相中的SiO 2和/或CaO制成的第二分散相。 主相的含有率在98％以上且小于98％的范围内。 氧化铝烧结体满足100×I2 /I1≥5.5％的关系，其中I1表示由氧化铝衍生的最大峰高强度，I2表示在氧化铝烧结体的X射线衍射中来自MgAl 2 O 4的最大峰高强度 身体。 第二分散相在氧化铝烧结体表面的面积比不大于15.2％。 火花塞具有中心电极，接地电极和由具有前述具体特征的氧化铝烧结体制成的绝缘体。