Abstract: A spark plug having a connection portion disposed between a metal terminal and a center electrode. The connection portion includes: a magnetic substance formed from a Fe-containing oxide; a conductor which is a wire helically disposed on an outer periphery of the magnetic substance and electrically connected to the metal terminal and the center electrode; and an intermediate member which is in contact with the magnetic substance, the conductor, and an inner peripheral surface of the insulator, is disposed between the magnetic substance and the conductor, and the inner peripheral surface of the insulator, and has lower electrical conductivity than the conductor. The conductor is made of one or more of an oxide conductor, carbon, and a carbon compound.

Abstract: A spark plug having a connection portion disposed in the axial hole and between a metal terminal and a center electrode. The connection portion includes: a magnetic substance formed from a Fe-containing oxide; a conductor helically disposed on an outer periphery of the magnetic substance and electrically connected to the metal terminal and the center electrode; and an intermediate member disposed between the magnetic substance and the conductor, and an inner peripheral surface of the insulator and having lower electrical conductivity than the conductor. The conductor includes a base and a conductive layer disposed on an outer periphery of the base and having higher electrical conductivity than the base, and the conductive layer has a thickness of larger than 0.1 ?m and equal to or smaller than 25 ?m.

Abstract: A spark plug having a connection portion disposed between a metal terminal and a center electrode. The connection portion includes: a magnetic substance formed from a Fe-containing oxide; a conductor which is a wire helically disposed on an outer periphery of the magnetic substance and electrically connected to the metal terminal and the center electrode; and an intermediate member which is in contact with the magnetic substance, the conductor, and an inner peripheral surface of the insulator, is disposed between the magnetic substance and the conductor, and the inner peripheral surface of the insulator, and has lower electrical conductivity than the conductor. The conductor is made of one or more of an oxide conductor, carbon, and a carbon compound.

Abstract: A spark plug having a connection portion disposed in the axial hole and between a metal terminal and a center electrode. The connection portion includes: a magnetic substance formed from a Fe-containing oxide; a conductor helically disposed on an outer periphery of the magnetic substance and electrically connected to the metal terminal and the center electrode; and an intermediate member disposed between the magnetic substance and the conductor, and an inner peripheral surface of the insulator and having lower electrical conductivity than the conductor. The conductor includes a base and a conductive layer disposed on an outer periphery of the base and having higher electrical conductivity than the base, and the conductive layer has a thickness of larger than 0.1 ?m and equal to or smaller than 25 ?m.

Abstract: The present invention allows reduction in high frequency noise of a spark plug. A Fe-containing oxide layer is formed on the surface of a beneath-flange rod-shaped portion, of a metal terminal of the spark plug, between a terminal flange portion and an upper end of a metal shell. The surface area of the Fe-containing oxide layer is not less than 10% of the surface area of the beneath-flange rod-shaped portion.

Abstract: A spark plug has an insulator, a rod-shaped electrode member disposed in an axial hole of the insulator, and a cylindrical magnetic member disposed on an outer circumference of the electrode member within the axial hole. The insulator includes a large inner diameter region, a middle inner diameter region located frontward of the large inner diameter region and having an inner diameter smaller than that of the large inner diameter region, and a small inner diameter region located frontward of the middle inner diameter region and having an inner diameter smaller than that of the middle inner diameter region. The electrode member is retained on a step portion of the insulator between the middle inner diameter region and the small inner diameter region. The magnetic member is positioned in the axial hole at a location within the large inner diameter region.

Abstract: A spark plug has an insulator, a rod-shaped electrode member disposed in an axial hole of the insulator, and a cylindrical magnetic member disposed on an outer circumference of the electrode member within the axial hole. The insulator includes a large inner diameter region, a middle inner diameter region located frontward of the large inner diameter region and having an inner diameter smaller than that of the large inner diameter region, and a small inner diameter region located frontward of the middle inner diameter region and having an inner diameter smaller than that of the middle inner diameter region. The electrode member is retained on a step portion of the insulator between the middle inner diameter region and the small inner diameter region. The magnetic member is positioned in the axial hole at a location within the large inner diameter region.

Abstract: Disclosed is a spark plug capable of suppressing high-frequency noise by improving the material of an electrical connection part between a center electrode and a metal terminal within an axial hole of an insulator. A spark plug has an electrical connection part arranged in an axial hole of an insulator to establish electrical connection between a center electrode and a metal terminal. The electrical connection part includes a conductor having a first crystal phase formed of a Fe-containing oxide and a second crystal phase formed of a conductive metal oxide of perovskite crystal structure.

Abstract: A connection structure between a center electrode and a metal terminal of a spark plug having a composite part that contains a plurality of secondary particles each formed of a plurality of primary particles of iron-containing oxide as a magnetic substance, and a conductive material coating the plurality of secondary particles. The iron-containing oxide includes at least one of an oxide represented by M1+AOFe2?AO3 (where ?0.5?A?0.5; and M is at least one kind of element selected from the group consisting of Mn, Fe, Co, Ni, Cu, Mg, Zn and Ca) and an oxide represented by Q3Fe5O12 (where Q is at least one kind of element selected from the group consisting of Y, Lu, Yb, Tm, Er, Ho, Dy, Tb, Gd and Sm). In cross section, an average particle size of the primary particles is 0.5 ?m to 100 ?m, an average particle size of the secondary particles is 0.5 mm to 2.0 mm, and a porosity of the inside of the secondary particles is 5% or lower.

Abstract: A spark plug includes a cylindrical metallic shell having a ground electrode at a forward end of the cylindrical metallic shell, a cylindrical insulator held in the metallic shell, a center electrode disposed in the insulator, a resistor element disposed in the insulator and having a forward end located rearward of a rear end of the center electrode, a forward-end-side electrically conductive seal layer disposed in the insulator to be located between the center electrode and the resistor element, and a rear-end-side electrically conductive seal layer disposed in the insulator to be located rearward of the resistor element. The forward end of the resistor element is located forward of the rear end of the metallic shell, and the rear end of the resistor element is located rearward of the rear end of the metallic shell.

Abstract: A spark plug includes a cylindrical metallic shell having a ground electrode at a forward end of the cylindrical metallic shell, a cylindrical insulator held in the metallic shell, a center electrode disposed in the insulator, a resistor element disposed in the insulator and having a forward end located rearward of a rear end of the center electrode, a forward-end-side electrically conductive seal layer disposed in the insulator to be located between the center electrode and the resistor element, and a rear-end-side electrically conductive seal layer disposed in the insulator to be located rearward of the resistor element. The forward end of the resistor element is located forward of the rear end of the metallic shell, and the rear end of the resistor element is located rearward of the rear end of the metallic shell.

Abstract: Disclosed is a spark plug capable of suppressing high-frequency noise by improving the material of an electrical connection part between a center electrode and a metal terminal within an axial hole of an insulator. A spark plug has an electrical connection part arranged in an axial hole of an insulator to establish electrical connection between a center electrode and a metal terminal. The electrical connection part includes a conductor having a first crystal phase formed of a Fe-containing oxide and a second crystal phase formed of a conductive metal oxide of perovskite crystal structure.

Abstract: A connection portion connecting a center electrode and a terminal metal fixture together in a through hole of the insulator includes a resistor and a 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. The connection portion further includes a first conductive sealing portion, a second conductive sealing portion and a third conductive sealing portion. The first conductive sealing portion is disposed on a leading end side of a first member and is in contact therewith. The second conductive sealing portion is disposed between the first member and a second member and is in contact with the first and second members. The third conductive sealing portion is disposed on a rear end side of the second member and is in contact therewith.

Abstract: A connection portion connecting a center electrode and a terminal metal fixture together in a through hole of the insulator includes a resistor and a magnetic substance structure including a magnetic substance and a conductor. The connection portion further includes a first conductive sealing portion, a second conductive sealing portion and a third conductive sealing portion. The first conductive sealing portion is disposed on a leading end side of a first member and is in contact therewith. The second conductive sealing portion is disposed between the first member and a second member and is in contact with the first member and the second member. The third conductive sealing portion is disposed on a rear end side of the second member and is in contact therewith.

Abstract: A connection portion connecting a center electrode and a terminal metal fixture together in a through hole of the insulator includes a resistor and a 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. The connection portion further includes a first conductive sealing portion, a second conductive sealing portion and a third conductive sealing portion. The first conductive sealing portion is disposed on a leading end side of a first member and is in contact therewith. The second conductive sealing portion is disposed between the first member and a second member and is in contact with the first and second members. The third conductive sealing portion is disposed on a rear end side of the second member and is in contact therewith.

Abstract: A connection portion connecting a center electrode and a terminal metal fixture together in a through hole of the insulator includes a resistor and a magnetic substance structure including a magnetic substance and a conductor The connection portion further includes a first conductive sealing portion, a second conductive sealing portion and a third conductive sealing portion. The first conductive sealing portion is disposed on a leading end side of a first member and is in contact therewith. The second conductive sealing portion is disposed between the first member and a second member and is in contact with the first member and the second member. The third conductive sealing portion is disposed on a rear end side of the second member and is in contact therewith.

Abstract: A spark plug having an insulator with a through hole formed therein in a direction of an axis, a center electrode disposed in a front side of the through hole, a metal terminal disposed in a rear side of the through hole, an electrical connection part arranged in the through hole to establish electrical connection between the center electrode and the metal terminal and a metal shell holding therein the insulator. The electrical connection part has a conductor including a conductive material and at least one kind of Fe-containing oxide material. The Fe-containing oxide material contains at least FeO. The conductor satisfies a relationship of 0.06?S1/(S1+S2)?0.46 where, in a cross section taken along the axis, S1 is an area occupied by the conductive material and S2 is an area occupied by the Fe-containing oxide material.

Abstract: A spark plug including an insulator having an axial hole, a center electrode held at one end side and a terminal electrode held at the other end side of the axial hole, an electrical connection portion electrically connecting the center electrode and the terminal electrode inside the axial hole, wherein the electrical connection portion includes a conductor including a ceramic phase and a metal wire having a spiral structure portion, wherein the metal wire has a wire diameter of 0.1 mm or greater and 0.5 mm or smaller, and wherein the spiral structure portion of the metal wire is configured such that an outer diameter thereof is 1.0 mm or greater and 3 mm or smaller, a pitch thereof is 0.3 mm or greater and 1 mm or smaller, and a height thereof is 8 mm or greater and 30 mm or smaller.

Abstract: A spark plug including an insulator having an axial hole, a center electrode held at one end side and a terminal electrode held at the other end side of the axial hole, an electrical connection portion electrically connecting the center electrode and the terminal electrode inside the axial hole, wherein the electrical connection portion includes a conductor including a ceramic phase and a metal wire having a spiral structure portion, wherein the metal wire has a wire diameter of 0.1 mm or greater and 0.5 mm or smaller, and wherein the spiral structure portion of the metal wire is configured such that an outer diameter thereof is 1.0 mm or greater and 3 mm or smaller, a pitch thereof is 0.3 mm or greater and 1 mm or smaller, and a height thereof is 8 mm or greater and 30 mm or smaller.

Abstract: A spark plug having an insulator with a through hole formed therein in a direction of an axis, a center electrode disposed in a front side of the through hole, a metal terminal disposed in a rear side of the through hole, an electrical connection part arranged in the through hole to establish electrical connection between the center electrode and the metal terminal and a metal shell holding therein the insulator. The electrical connection part has a conductor including a conductive material and at least one kind of Fe-containing oxide material. The Fe-containing oxide material contains at least FeO. The conductor satisfies a relationship of 0.06?S1/(S1+S2)?0.46 where, in a cross section taken along the axis, S1 is an area occupied by the conductive material and S2 is an area occupied by the Fe-containing oxide material.