# US 10,312,669 B2 · Spark plug

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- Number: US 10,312,669 B2
- Document ID: US10312669B2
- Status: Granted
- Kind: B2
- Application number: 16/072,425
- Filed: 2016-10-17
- Published: 2018-12-20
- Granted: 2019-06-04
- Earliest claimed: 2016-01-26
- Assignees: Ngk Spark Plug Co., Ltd.
- Applicants: Ngk Spark Plug Co., Ltd.
- Inventors: Daisuke Sumoyama; Tatsuya Gozawa; Tsutomu Shibata
- Web page: https://patentgrep.com/patent/US10312669B2

## CPC

- H01T 13/39: Selection of materials for electrodes
- C22C 5/04: Alloys based on a platinum group metal
- C22C 30/00: Alloys containing less than 50% by weight of each constituent
- H01T 13/20: characterised by features of the electrodes or insulation
- H01T 13/32: characterised by features of the earthed electrode
- H01T 21/02: of sparking plugs
- H01T: SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES (overvoltage protection circuits H02H)
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## 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.

## Claims

### Claim 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.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 1)

The spark plug according to claim 1, wherein
in the case where D1 represents a distance between the diffusion layer and the discharge surface of the discharge member, and G represents a length of the gap,
D1≥0.1 mm and (D1/G)≥0.1 are satisfied.

### Claim 4 (depends on 1)

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. %.

### Claim 5 (depends on 1)

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. %.

### Claim 6 (depends on 1)

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. %.

### Claim 7 (depends on 4)

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. %.