Ignition plug and ignition device

Patent metadata

Field	Value
Publication number	US-10107252-B2
Application number	US-201615168801-A
Country	US
Kind code	B2
Filing date	May 31, 2016
Priority date	Jun 19, 2015
Publication date	Oct 23, 2018
Grant date	Oct 23, 2018

Abstract

In an ignition plug, the volume V 1 of a portion of an insulator, which projects from a metallic shell to a front side, is equal to or greater than 45 mm 3 ; and an expression 0.18≤V 2/ V 1 ≤0.37 is satisfied, where H is a length along which the insulator projects from the metallic shell to the front side in an axial direction, and V 2 is a volume of a portion of the insulator, which projects from a front end of the insulator along a length H/ 2 in the axial direction.

First claim

The invention claimed is:

1. An ignition plug comprising:
a center electrode extending from a front side to a rear side in an axial direction;
an insulator formed in a bottomed tubular shape and enclosing a front end of the center electrode; and
a metallic shell formed in a tubular shape extending in the axial direction and holding the insulator in a state where the insulator projects to the front side, wherein
a volume V 1 of a portion of the insulator, which projects from the metallic shell to the front side, is equal to or greater than 45 mm 3 , and
an expression 0.18≤V 2 /V 1 ≤0.37 is satisfied,
where H is a length along which the insulator projects from the metallic shell to the front side in the axial direction, and
V 2 is a volume of another portion of the insulator, which projects from a front end of the insulator along a length H/ 2 in the axial direction.

2. The ignition plug according to claim 1 , wherein an expression 0 mm<X−Y≤1.0 mm is satisfied,
where X is an inner diameter of a front hole of the metallic shell and
Y is an outer diameter of a part of the insulator which opposes the front hole.

3. The ignition plug according to claim 1 , wherein
the length H is equal to or less than 9.7 mm,
the insulator includes:
a first outer diameter portion projecting from the metallic shell and having a first outer diameter; and
a second outer diameter portion having a second outer diameter D smaller than the first outer diameter and forming the front side of the insulator with respect to the first outer diameter portion, and

an expression D/L≤0.75 is satisfied, where L is a length of the second outer diameter portion in the axial direction.

4. The ignition plug according to claim 1 , wherein the center electrode includes a portion having an outer diameter that is larger than the rear side of the center electrode in a range of the length H/ 2 in the axial direction starting from the front end of the insulator.

5. The ignition plug according to claim 1 , wherein the insulator includes a portion in which an outer diameter thereof decreases toward the front side in a range of the length H/ 2 in the axial direction starting from the front end of the insulator.

6. An ignition device comprising:
the ignition plug according to claims 1 ; and
a voltage application part that is configured to generate non-equilibrium plasma on a surface of the insulator by applying an AC voltage or multiple pulse voltages to the center electrode.

Assignees

• Ngk Spark Plug Co

Inventors

• Ban Kenji
• Usami Kohei

Classifications

• H01T13/52 Primary

  characterised by a discharge along a surface · CPC title

• H01T13/16

  Means for dissipating heat · CPC title

• F02P9/007 Primary

  by supplementary electrical discharge in the pre-ionised electrode interspace of the sparking plug, e.g. plasma jet ignition · CPC title

• F02P23/04

  Other physical ignition means, e.g. using laser rays · CPC title