公开(公告)号：US12095233B1

公开(公告)日：2024-09-17

申请号：US18567541

申请日：2022-06-14

Applicant: NITERRA CO., LTD.

Inventor： Noriyuki Tamura ,  Haruki Yoshida ,  Hiroki Shimada ,  Tomoya Kukino ,  Takuto Koba ,  Kengo Fujimura

IPC: H01T13/34

CPC classification number: H01T13/34

Abstract: A spark plug 1 of the present invention includes: an insulator 2 made from an alumina-based sintered body; a center electrode being a bar-like electrode inserted in the insulator 2 and having, on a rear end side of the center electrode, a diameter-enlarged portion enlarged in a radial direction and engaged with an inner wall of the insulator; and a conductive sealing material provided on the rear end side of the center electrode 3 inside the insulator. In a mirror-polished surface obtained by mirror-polishing a cut surface obtained by cutting the insulator in a direction perpendicular to the axial line direction, at a position 2 mm from a portion having a maximum diameter of the diameter-enlarged portion to the rear end side along the axial line direction, when 20 observation regions each being 192 μm×255 μm are set so as to each overlap a reference position being a center position between an inner peripheral surface and an outer peripheral surface of the insulator and so as not to overlap each other, an average of a proportion (porosity) of pores included in each observation region is not greater than 3.5% and, with respect to a variation in the proportion (porosity), when a standard deviation is defined as σ, σ is not greater than 0.36.

公开(公告)号：US12249809B2

公开(公告)日：2025-03-11

申请号：US18616670

申请日：2024-03-26

Applicant: Niterra Co., Ltd.

Inventor： Hiroki Shimada ,  Haruki Yoshida ,  Kengo Fujimura ,  Takuto Koba

IPC: H01T13/38

Abstract: When a force to bend a spark plug insulator is applied to the spark plug insulator to fracture the spark plug insulator, for a range including a starting point of the fracture out of two ranges into which a fracture surface created by the fracture is divided by a plane which is a plane perpendicular to a direction of the force and includes the axial line, an average of areas of particles appearing in a planar image of the range is 4.4 μm2 or larger and 8.0 μm2 or smaller, and a maximum area of the particles is 600 μm2 or smaller. The particles include large particles having an area of 60 μm2 or larger and 600 μm2 or smaller, and, as the large particles, 0.1 particles/mm2 or more are present per unit area of the planar image.