Spark plug

Patent metadata

Field	Value
Publication number	US-9325156-B2
Application number	US-201514590075-A
Country	US
Kind code	B2
Filing date	Jan 6, 2015
Priority date	Jan 14, 2014
Publication date	Apr 26, 2016
Grant date	Apr 26, 2016

Abstract

A spark plug wherein an outer diameter of a first face that is a gap foliating face of the center electrode tip is denoted as R 1 , an outer diameter of a second face that is a gap forming face of the ground electrode tip is denoted as R 2 , a length of the gap is denoted as G 1 , and an average distance of a distance between an end in the first direction of the first face and an end in the first direction of the second face and a distance between an end in the second direction of the first face and an end in the second direction of the second face is denoted as G 2 , R 1 <R 2 , 0.5 mm≦R 1 ≦1.1 mm, 0.7 mm≦R 2 ≦1.2 mm, 0.6 mm≦G 1 ≦1.3 mm, and 1.4≦(R 2 /R 1 )×(G 2 /G 1 )≦1.8 are satisfied.

First claim

Having described the invention, the following is claimed:

1. A spark plug comprising:
a center electrode including a center electrode body extending in an axial direction and a center electrode tip joined to a front end of the center electrode body;
an insulator having an axial hole extending in the axial direction, the center electrode being arranged in the axial hole;
a metal shell arranged around an outer circumference of the insulator; and
a ground electrode including a ground electrode body electrically connected to the metal shell and a projection part that is a portion projecting toward the center electrode from an end part of the ground electrode body, the projection part including a ground electrode tip forming a gap between itself and the center electrode tip,
wherein a particular cross section includes a center axis of the center electrode tip,
wherein two directions that are orthogonal to the center axis of the center electrode tip and opposed to each other are denoted as a first direction and a second direction,
wherein an outer diameter of a first face that is a face of the center electrode tip forming the gap is denoted as R 1 ,
wherein an outer diameter of a second face that is a face of the ground electrode tip forming the gap is denoted as R 2 ,
wherein a length of the gap is denoted as G 1 ,
wherein an average distance of a distance between an end in the first direction of the first face and an end in the first direction of the second face and a distance between an end in the second direction of the first face and an end in the second direction of the second face is denoted as G 2 , and
wherein the following is satisfied:
R 2/ R 1>1,
R 1< R 2,
G 2/ G 1>1,
0.5 mm≦ R 1≦1.1 mm,

0.7 mm≦ R 2≦1.2 mm,

1< R 2/ R 1<1.8,
0.6 mm≦ G 1≦1.3 mm, and

1.4 ≦R 2/ R 1 ×G 2/ G 1≦1.8.

2. The spark plug according to claim 1 , wherein R 2 /R 1 ×G 2 /G 1 ≦1.69 is satisfied.

3. The spark plug according to claim 2 , wherein, when a length to the second face from a surface of the ground electrode body on which the projection part is arranged is denoted as T, 0.7 mm≦T≦1.1 mm is satisfied.

4. The spark plug according to any one of claims 1 to 3 ,
wherein the ground electrode body is a bar-shaped member including a base material that is a portion forming at least a part of a surface of the ground electrode body and a core part buried in the base material and having a higher thermal conductivity than the base material, and
wherein, when a length in a longitudinal direction of a portion including the core part of the ground electrode body along a shape of the ground electrode body is denoted as L and a length in the axial direction from a front end of the metal shell to a front end of the ground electrode is denoted as C, 0.98≦L/C≦1.48 is satisfied.

Assignees

• Ngk Spark Plug Co

Inventors

• Ban Kenji
• Kataoka Yoshikazu
• Shimadate Magoki
• Kato Tomoaki

Classifications

• H01T13/32 Primary

  characterised by features of the earthed electrode · CPC title

• H01T13/20

  characterised by features of the electrodes or insulation · CPC title

• H01T13/16

  Means for dissipating heat · CPC title