Spark plug

Patent metadata

Field	Value
Publication number	US-10063036-B2
Application number	US-201615264971-A
Country	US
Kind code	B2
Filing date	Sep 14, 2016
Priority date	Sep 16, 2015
Publication date	Aug 28, 2018
Grant date	Aug 28, 2018

Abstract

A spark plug includes an insulator having an axial hole formed therethrough in the direction of an axis of the spark plug, a center electrode disposed in a front side of the axial hole and a metal shell disposed around an outer circumference of the insulator and having a collar-shaped tool engagement portion and a crimp portion located on a rear side of the tool engagement portion and reduced in diameter toward the rear, wherein the crimp portion of the metal shell is made of a carbon steel material having a grain size number equal to or greater than No. 11 as measured according to JIS G 0551.

First claim

Having described the invention, the following is claimed:

1. A spark plug comprising:
an insulator having an axial hole formed therethrough in a direction of an axis of the spark plug;
a center electrode disposed in a front side of the axial hole; and
a metal shell disposed around an outer circumference of the insulator and including a collar-shaped tool engagement portion and a crimp portion located on a rear side of the tool engagement portion and reduced in diameter toward a rear in the direction of the axis,
wherein the crimp portion of the metal shell is made of a carbon steel material having a grain size number in a range from No. 11 to No. 18 as measured according to JIS G 0551.

2. The spark plug according to claim 1 , wherein the carbon steel material has a mean lineal grain length of 0.01 mm or smaller where the mean lineal grain length is an arithmetic mean value of lengths of crystal grains situated on a line segment parallel to the axis of the spark plug.

3. The spark plug according to claim 1 , wherein the carbon steel material has an intercepted grain number greater than or equal to 200 as measured according to JIS G 0551.

4. The spark plug according to claim 1 , wherein the carbon steel material contains Fe as a main component, 0.03 to 0.3 mass % of C, 0.3 to 0.9 mass % of Mn, 0.1 to 0.8 mass % of Si and 0.001 to 0.1 mass % of S.

5. The spark plug according to claim 2 , wherein about 200 of the crystal grains are situated on the line segment.

6. The spark plug according to claim 1 , wherein the carbon steel material has an intercepted grain number in a range of 200 to 500 as measured according to JIS G 0551.

Assignees

• Ngk Spark Plug Co

Inventors

• Kozakai Yohei
• Nagasawa Satoshi
• Suzuki Akira

Classifications

• H01T13/20 Primary

  characterised by features of the electrodes or insulation · CPC title

• H01T13/39

  Selection of materials for electrodes · CPC title

• H01T13/36

  characterised by the joint between insulation and body, e.g. using cement · CPC title

• H01T13/02 Primary

  Details · CPC title

• H01T13/12

  Means on sparking plugs for facilitating engagement by tool or by hand · CPC title