| 主权项 |
1. A spark plug comprising:
an insulator having a through hole extending in a direction of an axial line; a center electrode, at least a part of which is inserted into a leading end side of the through hole; a terminal metal fixture, at least a part of which is inserted into a rear end side of the through hole; and a connection portion connecting the center electrode and the terminal metal fixture together in the through hole, wherein the connection portion includes:
a resistor; anda magnetic substance structure including a magnetic substance and a conductor and being disposed on a leading end side or a rear end side of the resistor while being positioned away from the resistor, wherein, among the resistor and the magnetic substance structure, when a member disposed on a leading end side is defined as a first member and a member disposed on a rear end side is defined as a second member, the connection portion further includes:
a first conductive sealing portion that is disposed on a leading end side of the first member and is in contact with the first member;a second conductive sealing portion that is disposed between the first member and the second member and is in contact with the first member and the second member; anda third conductive sealing portion that is disposed on a rear end side of the second member and is in contact with the second member, wherein the magnetic substance structure contains:
(1) a conductive substance as the conductor;(2) an iron-containing oxide as the magnetic substance; and(3) a ceramic containing at least one of silicon (Si), boron (B), and phosphorous (P), and wherein, in a cross-section of the magnetic substance structure including the axial line, when a target region is defined as a rectangular region having the axial line as a center line, a side of 1.5 mm in a direction perpendicular to the axial line, and a side of 2.0 mm in the direction of the axial line,
a region of the conductive substance includes a plurality of grain-shaped regions in the target region,a proportion of a number of grain-shaped regions having a maximum grain size of 200 μm or greater among the plurality of grain-shaped regions is 40% or more, anda proportion of an area of the region of the conductive substance is 35% or greater and 65% or less in the target region. |
