Spark plug

Patent metadata

Field	Value
Publication number	US-10312669-B2
Application number	US-201616072425-A
Country	US
Kind code	B2
Filing date	Oct 17, 2016
Priority date	Jan 26, 2016
Publication date	Jun 4, 2019
Grant date	Jun 4, 2019

Abstract

An electrode base material of the spark plug contains not less than 50 wt. % of Ni. A discharge member contains not less than 45 wt. % of Pt, and at least one of Ni and Rh. An intermediate member contains Pt and Ni. In the discharge member, a content of Pt is highest, and a total content of Pt, Rh, and Ni is not less than 92 wt. %. In the intermediate member, a content of one of Pt and Ni is not less than 50 wt. %, a content of Ni is higher than a content of Ni in the discharge member, and a total content of Pt, Rh, and Ni is not less than 85 wt. %. A thickness of the diffusion layer formed between the discharge member and the intermediate member is not less than 0.002 mm and not more than 0.065 mm.

First claim

Having described the invention, the following is claimed:

1. A spark plug comprising:
a center electrode extending in an axial direction; and
a ground electrode forming a gap between the ground electrode and the center electrode,
wherein at least one of the center electrode and the ground electrode includes:
an electrode base material;
a discharge member having a discharge surface that forms the gap;
an intermediate member disposed between the discharge member and the electrode base material; and
a diffusion layer formed between the discharge member and the intermediate member,
the electrode base material contains not less than 50 wt. % of nickel (Ni),
the discharge member contains not less than 45 wt. % of platinum (Pt), and at least one of nickel and rhodium (Rh),
the intermediate member contains platinum and nickel,
in the discharge member, a content of platinum is highest, and a total content of platinum, rhodium, and nickel is not less than 92 wt. %,
in the intermediate member, a content of one of platinum and nickel is not less than 50 wt. %, a content of nickel is higher than a content of nickel in the discharge member, and a total content of platinum, rhodium, and nickel is not less than 85 wt. %, and
a thickness of the diffusion layer is not less than 0.002 mm and not more than 0.065 mm.

2. The spark plug according to claim 1 , wherein
the thickness of the diffusion layer is not less than 0.005 mm and not more than 0.065 mm.

3. The spark plug according to claim 1 , wherein
in the case where D 1 represents a distance between the diffusion layer and the discharge surface of the discharge member, and G represents a length of the gap,
D 1 ≥0.1 mm and (D 1 /G)≥0.1 are satisfied.

4. The spark plug according to claim 1 , wherein
in the discharge member, a total content of platinum, rhodium, and nickel is not less than 96 wt. %.

5. The spark plug according to claim 1 , wherein
in the intermediate member, a total content of platinum, rhodium, and nickel is not less than 96 wt. %.

6. The spark plug according to claim 1 , wherein
a content of nickel in the intermediate member is higher than a content of nickel in the discharge member by not less than 2.5 wt. %.

7. The spark plug according to claim 4 , wherein
in the discharge member, a total content of platinum and rhodium is not less than 88 wt. %.

Assignees

• Ngk Spark Plug Co

Inventors

• Sumoyama Daisuke
• Gozawa Tatsuya
• Shibata Tsutomu

Classifications

• C22C5/04

  Alloys based on a platinum group metal · CPC title

• H01T13/39 Primary

  Selection of materials for electrodes · CPC title

• H01T21/02

  of sparking plugs · CPC title

• H01T13/32

  characterised by features of the earthed electrode · CPC title

• C22C30/00

  Alloys containing less than 50% by weight of each constituent · CPC title