Corona ignition device with improved electrical performance

Patent metadata

Field	Value
Publication number	US-9970408-B2
Application number	US-201514742064-A
Country	US
Kind code	B2
Filing date	Jun 17, 2015
Priority date	Mar 23, 2012
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

A corona igniter ( 20 ) comprises a central electrode ( 22 ) surrounded by an insulator ( 26 ), which is surrounded by a conductive component. The conductive component includes a shell ( 34 ) and an intermediate part ( 36 ) both formed of an electrically conductive material. An outer surface ( 50 ) of the insulator ( 26 ) presents a lower ledge ( 52 ), and the intermediate part ( 36 ) is typically attached to the insulator ( 26 ) above the lower ledge ( 52 ) prior to inserting the insulator ( 26 ) into the shell ( 34 ). The conductive inner diameter (D g ) is less than an insulator outer diameter (D io ) directly below the lower ledge ( 52 ) such the insulator thickness (t i ) increases toward the electrode firing end ( 40 ). The corona igniter ( 20 ) can be reversed-assembled by inserting an upper end ( 42 ) of the insulator into a firing end ( 56 ) of the shell.

First claim

What is claimed is:

1. A corona igniter for emitting a radio frequency electric field to ionize a fuel-air mixture and provide a corona discharge, comprising:
a central electrode formed of an electrically conductive material for receiving a high radio frequency voltage and emitting the radio frequency electric field;
an insulator formed of an electrically insulating material surrounding said central electrode and extending longitudinally along a center axis from an insulator upper end to an insulator nose end;
said insulator including an insulator outer surface extending from said insulator upper end to said insulator nose end;
said insulator outer surface presenting an insulator outer diameter extending across and perpendicular to said center axis;
said insulator including an insulator body region and an insulator nose region;
said insulator outer surface including a lower ledge extending outwardly away from said center axis between said insulator body region and said insulator nose region;
said lower ledge presenting an increase in said insulator outer diameter;
a conductive component surrounding at least a portion of said insulator body region such that said insulator nose region extends outwardly of said conductive component;
said conductive component including a shell surrounding at least a portion of said insulator body region and extending from a shell upper end to a shell firing end;
said shell presenting a shell inner surface facing said center axis and extending along said insulator outer surface from said shell upper end to said shell firing end;
said conductive component including an intermediate part formed of an electrically conductive material and surrounding a portion of said insulator body region and extending longitudinally from an intermediate upper end to an intermediate firing end;
said intermediate part including an intermediate inner surface facing said center axis and extending longitudinally along said insulator outer surface from said intermediate upper end to said intermediate firing end;
said intermediate inner surface presenting a conductive inner diameter extending across and perpendicular to said center axis;
said conductive inner diameter being less than said insulator outer diameter along a portion of said insulator located between said lower ledge and said insulator nose end; and
said intermediate part being disposed between said insulator upper end and said lower ledge.

2. The corona igniter of claim 1 , wherein said insulator outer surface of said insulator body region presents an upper ledge extending inwardly toward said center axis, and said insulator outer surface presents a recess extending longitudinally from said upper ledge to said lower ledge, and said intermediate part is disposed in said recess.

3. The corona igniter of claim 2 , wherein said insulator outer diameter at said upper ledge is different from said insulator outer diameter at said lower ledge.

4. The corona igniter of claim 1 , wherein said shell inner surface presents a shell inner diameter extending across and perpendicular to said center axis; and said shell inner diameter is greater than or equal to said insulator outer diameter along a portion of said insulator body region.

5. The corona igniter of claim 1 , wherein said insulator presents a thickness between said insulator inner surface and said insulator outer surface; and said thickness increases along a portion of said insulator between said intermediate firing end and said insulator nose end.

6. The corona igniter of claim 1 , wherein said insulator has a length extending from said insulator upper end to said insulator nose end, and said intermediate part extends along not greater than one quarter of said length.

7. The corona igniter of claim 1 , wherein said intermediate part is disposed adjacent said lower ledge.

8. The corona igniter of claim 1 , wherein said insulator outer diameter tapers from said lower ledge along said insulator nose region to said insulator nose end.

9. The corona igniter of claim 1 , wherein said intermediate part is disposed adjacent the shell firing end.

10. The corona igniter of claim 1 , wherein said corona igniter is reversed assembled by inserting said insulator upper end through said shell firing end.

11. The corona igniter of claim 1 , wherein a portion of said insulator extends continuously along said intermediate part, and said insulator is located above said intermediate upper end and below said intermediate firing end.

12. The corona igniter of claim 1 , wherein the insulator outer diameter is less than said conductive inner diameter continuously from said insulator upper end to said lower ledge.

13. A method of forming a corona igniter, comprising the steps of:
providing an insulator formed of an electrically insulating material extending along a center axis from an insulator upper end to an insulator nose end, the insulator including an insulator outer surface extending from the insulator upper end to the insulator nose end and presenting an insulator outer diameter, the insulator outer surface presenting a lower ledge extending outwardly away from the center axis between an insulator body region and an insulator nose region;
disposing an intermediate part formed of an electrically conductive material between the insulator upper end and the lower ledge; and
disposing a shell formed of an electrically conductive material around the intermediate part and the insulator.

14. The method of claim 13 , wherein the shell extends from a shell upper end to a shell firing end, and the step of disposing the shell around the intermediate part and the insulator includes inserting the insulator upper end through the shell firing end.

15. The method of claim 14 , including attaching the intermediate part to the insulator outer surface before inserting the insulator into the shell.

16. The method of claim 15 , wherein the attaching step includes at least one of: casting, sintering, brazing, soldering, diffusion bonding, and attaching by an adhesive.

17. The method of claim 13 , including hermetically sealing the intermediate part to the insulator.

18. The method of claim 13 , wherein the intermediate part presents a conductive inner diameter, the insulator presents an insulator outer diameter, and the conductive inner diameter is less than the insulator outer diameter along a portion of the insulator between the lower ledge and the insulator nose end.

19. The method of claim 18 , wherein the conductive inner diameter is less than the insulator outer diameter along a portion of the insulator between the lower ledge and the insulator upper end.

20. The method of claim 13 , wherein the insulator presents an upper ledge and a recess extending longitudinally from the upper ledge to the lower ledge, and the intermediate part is disposed in the recess.

Assignees

• Fed Mogul Llc

Inventors

• Burrows John Antony
• Miller John E
• Mixell Kristapher I
• Lykowski James D

Classifications

• Y10T29/49002

  Electrical device making · CPC title

• H01T19/00

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

• Y10T29/49227

  Insulator making · CPC title

• H01T19/04

  having pointed electrodes · CPC title

• H01T13/36

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