Optimized barrier discharge device for corona ignition

Patent metadata

Field	Value
Publication number	US-11022086-B2
Application number	US-201916656151-A
Country	US
Kind code	B2
Filing date	Oct 17, 2019
Priority date	Oct 19, 2018
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

An insulator for a corona igniter, referred to as a barrier discharge ignition (BDI) device, for use in an internal combustion engine, is provided. A central electrode is disposed in a slot of the insulator and an electrode tip is spaced from a round insulator tip by insulating material. A shell formed of metal surrounds a portion of the insulator. The insulator has a thickness tapering between a shell firing surface and the insulator tip. The tapering insulator thickness is unidirectional and thus does not increase between a start of the taper and the insulator tip. A method of manufacturing an insulator for a corona igniter is also provided. Equations can be used to determine if a taper in the insulator thickness is needed to encourage corona propagation along a core nose projection of the insulator, and if so, the location and size of the taper.

First claim

What is claimed is:

1. A corona igniter, comprising:
an insulator formed of an insulating material, said insulator extending longitudinally along a center axis from an insulator upper end to an insulator tip, said insulator having a thickness extending from an insulator outer surface to an insulator inner surface, said insulator inner surface presenting a slot extending longitudinally along said center axis from said insulator upper end toward said insulator tip, and said insulator outer surface being round at said insulator tip;
a central electrode disposed in said slot of said insulator and extending longitudinally from an electrode upper end to an electrode tip, said electrode tip being spaced from said insulator tip by said insulating material;
a shell formed of metal surrounding a portion of said insulator and extending longitudinally from a shell upper end to a shell firing surface;
said insulator thickness tapering between said shell firing surface and said insulator tip, and said insulator thickness not increasing between a start of the taper and said insulator tip,
said insulator including a core nose projection having a length extending from said shell firing surface to said insulator tip, said taper in said insulator thickness extending along a percentage of said length of said core nose projection, and said percentage of said length being greater than or equal to a calculated percentage defined according to the following equation:

Y
=

-
2.9

⁢
%
×

(

R
CE

R
INS

-

R
CE

)

+

59.56
⁢
%

wherein Y is said percentage of said length of said core nose projection of said insulator,
R CE is a radius of said center electrode, said radius of said center electrode is a distance extending from said center axis to an electrode outer surface, and
R INS is a radius of said insulator, said radius of said insulator is a distance extending from said center axis to said insulator outer surface, and said radius of said insulator is measured along a portion of said insulator wherein said insulator thickness is constant.

2. A corona igniter according to claim 1 , and said insulator outer surface extends radially inwardly toward said insulator inner surface to present said taper in said insulator thickness.

3. A corona igniter, comprising:
an insulator formed of an insulating material, said insulator extending longitudinally along a center axis from an insulator upper end to an insulator tip, said insulator having a thickness extending from an insulator outer surface to an insulator inner surface, said insulator inner surface presenting a slot extending longitudinally along said center axis from said insulator upper end toward said insulator tip, and said insulator outer surface being round at said insulator tip;
a central electrode disposed in said slot of said insulator and extending longitudinally from an electrode upper end to an electrode tip, said electrode tip being spaced from said insulator tip by said insulating material;
a shell formed of metal surrounding a portion of said insulator and extending longitudinally from a shell upper end to a shell firing surface;
said insulator thickness tapering between said shell firing surface and said insulator tip, and said insulator thickness not increasing between a start of the taper and said insulator tip, wherein said insulator thickness is constant along a first portion of said insulator and tapers along a second portion of said insulator extending from said first portion toward said insulator tip, said insulator thickness at said insulator tip relative to said insulator thickness at said first portion being reduced by greater than or equal to a percentage of said insulator thickness at said first portion, said percentage being defined by the following equation:

T
⁢

⁢
%

=

30.3
⁢
%

-

(

45.2
⁢
%
*
P
⁢

⁢
1

)

-

(

0.8
⁢
%
*
P
⁢

⁢
2

)

+

(

4.2
⁢
%
*
P
⁢

⁢
3

)

+

2.5
⁢
%

,

⁢
wherein

P
⁢

⁢
1

=

R
INS

CEP

,

⁢

P
⁢

⁢
2

=

(

R
CE

R

INS
-

R
CE

Assignees

• Tenneco Inc

Inventors

• Burrows John Antony
• Chan Fu Xing
• Lykowski James D

Classifications

• H01T19/00

  Devices providing for corona discharge (for charging electrographic elements G03G15/02) · CPC title

• H01B17/42

  Means for obtaining improved distribution of voltage (capacitor-type lead-through insulators H01B17/28); Protection against arc discharges · CPC title

• H01T13/52 Primary

  characterised by a discharge along a surface · CPC title

• H01T13/50

  having means for ionisation of gap (H01T13/52 takes precedence) · CPC title

• H01T13/36

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