Spark plug

Patent metadata

Field	Value
Publication number	US-9373940-B2
Application number	US-201514707344-A
Country	US
Kind code	B2
Filing date	May 8, 2015
Priority date	May 12, 2014
Publication date	Jun 21, 2016
Grant date	Jun 21, 2016

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.

First claim

Having described the invention, the following is claimed:

1. A spark plug comprising:
an insulator having 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,
wherein the electrical connection part has a conductor including a conductive material and at least one kind of Fe-containing oxide material;
wherein the Fe-containing oxide material contains at least FeO; and
wherein 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.

2. The spark plug according to claim 1 , wherein the conductor further includes an alkaline-containing phase that contains an oxide of an alkali metal and an oxide of at least one kind of element selected from the group consisting of Si, B and P.

3. The spark plug according to claim 2 , wherein the alkali metal is contained in an amount of 0.5 to 6.5 wt % in terms of oxide based on the conductor.

4. The spark plug according to claim 1 , wherein the Fe-containing oxide material further contains a ferrite.

5. The spark plug according to claim 4 , wherein the FeO is contained in an amount of 0.8 to 5.2 wt % based on the Fe-containing oxide material.

6. The spark plug according to claim 1 , wherein the conductor further includes Cu in an amount of 0.03 to 5.4 wt % in terms of divalent Cu oxide.

7. The spark plug according to claim 1 ,
wherein the electrical connection part has a resistor including a conductive material and a glass material, a first conductive seal layer located adjacent to the center electrode and a second conductive seal layer located adjacent to the metal terminal;
wherein the conductor and the resistor are arranged between the first and second conductive seal layers; and
wherein a resistance between the center electrode and the metal terminal is in a range of 3 to 20 kΩ.

Assignees

• Ngk Spark Plug Co

Inventors

• Takaoka Katsuya
• Kurosawa Kazuhiro
• Tanaka Kuniharu
• Yoshida Haruki
• Kurono Hirokazu
• Honda Toshitaka

Classifications

• H01T13/05

  combined with interference suppressing or shielding means · CPC title

• H01T13/04 Primary

  Means providing electrical connection to sparking plugs · CPC title

• H01T13/41

  with interference suppressing or shielding means · CPC title