Laser ignition for gas mixtures

• US 8,181,617 B2
• Filed: 03/28/2008
• Issued: 05/22/2012
• Est. Priority Date: 03/29/2007
• Status: Active Grant

• Current Assignee: Multitorch GmbH
• Original Assignee: Multitorch GmbH
• Inventors: Kuhnert, Dieter, Kettner, Maurice, Maul, Georg
• Primary Examiner(s): HUYNH, HAI H
• Application Number:
  US12/593,119
• Publication Number:
  US 20100147259A1
• Time in Patent Office: 1,516 Days
• Field of Search: 123/260, 123/266, 123/143.B
• US Class Current: 123/143.B
• CPC Class Codes: F02P 13/00 Sparking plugs structurally combined with other parts of internal-combustion engines connection of ignition coil to spark plug connector F02P3/02; with fuel injectors F02M57/06 ; spark plug connector per se H01T13/04 – H01T13/06; predominant aspects of sparking plug, see H01T13/40 – H01T13/44
• CPC Class Codes: F02P 23/04 Other physical ignition means, e.g. using laser rays

Abstract

An ignition device for the ignition of a gas mixture in a main combustion chamber (1), in particular of an internal combustion engine, is proposed, wherein the absorber body (5) is heated by means of a laser (8). A prechamber (10) is located upstream of the absorber body (5) on the combustion chamber inner side (6) in order to improve the ignition behavior.

Claims

1. An ignition device for the ignition of a combustible or explosive gas mixture in a main combustion chamber (1), in particular for the ignition of a fuel-air mixture or a combustion gas-air mixture in an internal combustion engine, comprising

a high temperature-resistant absorber body (5), which is arranged in contact with gas mixture coming from the main combustion chamber (1), with a combustion chamber inner side (6) facing the gas mixture, and

a light guide path for guiding a laser beam (7) onto the absorber body (5) in order to heat the absorber body (5) with the laser beam (7) until an ignition temperature (TZ) required for the ignition of the gas mixture is reached on the combustion chamber inner side (6) of the absorber body (5),

wherein the light guide path up to the absorber body (5) is configured in such a way that the laser beam (7) does not have direct contact with the gas mixture of the main combustion chamber (1),

wherein

a prechamber (10) with at least one overflow opening (11) connecting the prechamber (10) and the main combustion chamber (1) is located upstream of the absorber body (5) on the combustion chamber inner side (6), wherein

the combustion chamber inner side (6) of the absorber body (5) is facing the gas mixture of the prechamber (10) and

the light guide path up to the absorber body (5) is configured in such a way that the laser beam (7) does not have direct contact with the gas mixture of the prechamber (10).

2. The ignition device according to claim 1 wherein the absorber body (5) is designed disk-shaped.

3. The ignition device according to claim 1 wherein the absorber body (5) has a diameter of less than 10 mm, preferably less than 5 mm, particularly preferably less than 2 mm.

4. The ignition device according to claim 1 wherein the material of the absorber body (5) is different from the material of the wall of the prechamber (10) which carries the absorber body (5).

5. The ignition device according to claim 1 wherein the absorber body (5) is made from a material that absorbs the laser light, its combustion chamber outer side (14) facing away from prechamber (10) being sealed off with respect to the combustion chamber inner side (6).

6. The ignition device according to claim 1 wherein the absorber body (5) is made from a ceramic and/or from a tungsten carbide.

7. The ignition device according to claim 1 wherein the absorber body (5) is formed as a preferably deep-black material which absorbs the laser light, which is arranged on the combustion chamber inner side (6) of a window material (15) facing the prechamber (10) and the absorber body (5) is made from a ceramic, in particular a sintered ceramic, preferably of aluminum oxide or aluminum nitride, a metallic material, of carbide, boride, silicide or nitride.

8. The ignition device according to claim 1 wherein the absorber body (5) is formed as a preferably deep-black material which absorbs the laser light, which is arranged on the combustion chamber inner side (6) of a window material (15) facing the prechamber (10) and the window material (15) is formed as a light-conducting rod (16).

9. The ignition device according to claim 1 wherein the absorber body (5) is formed as a preferably deep-black material which absorbs the laser light, which is arranged on the combustion chamber inner side (6) of a window material (15) facing the prechamber (10) and the window material (15) is a tungsten-silicate glass, a borosilicate glass or sapphire.

10. The ignition device according to claim 1 wherein the laser beam (7) is pulsed.

11. The ignition device according to claim 1 wherein the laser (8) is integrated into the ignition device.

12. The ignition device according to claim 1 wherein the ignition device is designed in the form of a spark plug (2) which can be mounted in the wall of a cylinder head (18), said spark plug comprising the absorber body (5), a part of the light path and the prechamber (10).

13. The ignition device according to claim 1 wherein the laser (8) is integrated into the spark plug (2).

14. The ignition device according to claim 1 wherein the prechamber (10) is divided in the axial direction into a front prechamber (12) and a rear prechamber (13), wherein the rear prechamber (13) is positioned farther away from main combustion chamber (1) than the front prechamber (12) and wherein the diameter of the rear prechamber (13) is greater than the diameter of the front prechamber (12).

15. The ignition device according to claim 1 wherein the absorber body (5) is arranged on a projection (19), which projects with an immersion depth into the prechamber (10).

16. An internal combustion engine, in particular a petrol engine or gas engine, characterised in that it comprises an ignition device according to any one of the preceding claims.

17. A method for the ignition of a combustible or explosive gas mixture in a main combustion chamber (1), of a fuel-air mixture or a combustion gas-air mixture in an internal combustion engine, the method comprising

contracting a high temperature-resistant absorber body (5) with a combustion chamber inner side (6) facing the gas mixture with gas mixture coming from the main combustion chamber (1), and

guiding a light beam (7) along a light guide path onto the absorber body (5), wherein the absorber body (5) is heated with the laser beam (7) until an ignition temperature (TZ) required for the ignition of the gas mixture is reached on the combustion chamber inner side (6) of the absorber body (5), the light guide path up to the absorber body (5) being configured in that the laser beam (7) does not have direct contact with the gas mixture of the main combustion chamber (1),

wherein

a prechamber (10) with at least one overflow opening (11) connecting the prechamber (10) and the main combustion chamber (1) is located upstream of the absorber body (5) on the combustion chamber inner side (6),

the combustion chamber inner side (6) of the absorber body (5) is arranged facing the gas mixture of the prechamber (10) and

the light guide path up to the absorber body (5) is configured in order that the laser beam (7) does not have direct contact with the gas mixture of the prechamber (10).