Sparkplug assembly with prechamber volume

Patent metadata

Field	Value
Publication number	US-9995202-B2
Application number	US-201615229821-A
Country	US
Kind code	B2
Filing date	Aug 5, 2016
Priority date	Aug 5, 2016
Publication date	Jun 12, 2018
Grant date	Jun 12, 2018

Abstract

A sparkplug assembly having a prechamber volume is operatively associated with the combustion chamber of an internal combustion engine such that the prechamber volume is in fluid communication with the combustion chamber. To purge exhaust gasses from the prechamber volume prior to ignition, the sparkplug assembly is operatively associated with a high-pressure air/fuel source that directs a pressurized air/fuel purge charge to the prechamber volume. The pressurized air/fuel purge charge may be at stoichiometric conditions. The high-pressure air/fuel source is configured to direct the pressurized air/fuel purge charge during at least a portion of the compression stroke to maintain a largely stoichiometric mixture of air and fuel in the prechamber volume.

First claim

We claim:

1. A sparkplug assembly for an internal combustion engine comprising:
a prechamber shell enclosing a prechamber volume, the prechamber shell including a distal end cap configured for placement in a combustion chamber and having a plurality of ports disposed therein;
an ignition element including an electrode disposed in the prechamber volume;
a high-pressure air/fuel source in fluid communication with the prechamber volume, the high-pressure air/fuel source being connected to an air line and a fuel line to receive air and fuel and mix the air and fuel to create a pressurized air/fuel purge charge, the high-pressure air/fuel source being configured to introduce the pressurized air/fuel purge charge into the prechamber volume during a compression stroke in the combustion chamber to purge gases from the prechamber volume into the combustion chamber and being further configured to cease introducing the pressurized air/fuel purge charge prior to activation of the ignition element.

2. The sparkplug assembly of claim 1 , wherein the prechamber volume has a volume geometry extending between a cap region proximate the distal end cap and a plug region proximate the ignition element, the high-pressure air/fuel source in fluid communication with the plug region.

3. The sparkplug assembly of claim 2 , wherein the high-pressure air/fuel source is configured to produce the pressurized air/fuel purge charge at a stoichiometric condition.

4. The sparkplug assembly of claim 3 , wherein the high-pressure air/fuel source is operatively associated with an electrically actuated valve disposed in a high-pressure channel communicating with the prechamber volume, the electrically actuated valve selectively actuated by an electronic controller to selectively introduce and cease introduction of the pressurized air/fuel purge charge.

5. The sparkplug assembly of claim 1 , further comprising an electronic controller operatively associated with the ignition element and the high-pressure air/fuel source, the electronic controller configured to direct the pressurized air/fuel purge charge into the prechamber volume prior to applying an ignition charge to the ignition element.

6. A method of conducting a combustion cycle in a combustion chamber comprising:
conducting an intake stroke during which a piston moveably disposed in the combustion chamber moves to a bottom dead center position;
introducing a pressurized air/fuel purge charge from a high-pressure air/fuel source into a prechamber volume associated with a sparkplug assembly disposed partially in the combustion chamber, thereby purging gasses from the prechamber volume to the combustion chamber;
conducting a compression stroke during which the piston moves toward a top dead center position;
maintaining introduction of the pressurized air/fuel purge charge into the prechamber volume to continue purging residual gasses from the prechamber volume to the combustion chamber;
ceasing introduction of the pressurized air/fuel purge charge prior to the piston reaching the top dead center position; and
igniting the pressurized air/fuel purge charge in the prechamber volume.

7. The method of claim 6 , further comprising preparing the pressurized air/fuel purge charge to be approximately at stoichiometric conditions.

8. The method of claim 7 , further comprising partially backfilling the prechamber volume with a mixture of air, fuel, and EGR from combustion chamber after ceasing introduction of the pressurized air/fuel purge charge.

9. The method of claim 8 , wherein the mixture of air, fuel, and EGR is approximately at stoichiometric conditions.

10. The method of claim 9 , wherein the prechamber volume contains by volume approximately 70% of the pressurized air/fuel purge charge and approximately 30% of the mixture of air, fuel, and EGR from the combustion chamber.

11. The method of claim 10 , wherein the pressurized air/fuel purge charge does not include EGR.

12. The method of claim 11 , wherein fuel of the mixture of air, fuel, and EGR and of the pressurized air/fuel purge charge is selected from a group comprising of liquid natural gas and compressed natural gas.

13. The method of claim 7 , further comprising monitoring a combustion parameter associated with combustion in the combustion chamber.

14. The method of claim 13 , further comprising adjusting, based on the combustion parameter, at least one of a timing of ceasing introduction of the pressurized air/fuel purge charge with respect to the position of the piston relative to the top dead center position, and a ratio of air to fuel of the pressurized air/fuel purge charge.

15. The method of claim 14 , wherein the combustion parameter is selected from a group consisting of coefficient of variance (COV) of indicated mean effective pressure, cylinder pressure, cylinder temperature, and exhaust gas composition.

16. An internal combustion engine comprising:
a combustion chamber having a piston reciprocally movable therein between a top dead center position and a bottom dead center position;
a sparkplug assembly operatively associated with the combustion chamber, the sparkplug assembly including a prechamber volume delineated by a prechamber shell and in fluid communication with the combustion chamber via a plurality of ports disposed through the prechamber shell, the sparkplug assembly further including an ignition element having an electrode disposed in the prechamber volume; and
a high-pressure air/fuel source operatively associated with the sparkplug assembly and in fluid communication with the prechamber volume, the high-pressure air/fuel source being connected to an air line and a fuel line to receive air and fuel and mix the air and fuel to create a pressurized air/fuel purge charge, the high-pressure air/fuel source being configured to direct the pressurized air/fuel purge charge to the prechamber volume as the piston moves through a compression stroke from the bottom dead center position to the top dead center position to purge gasses from the prechamber volume into the combustion chamber.

17. The internal combustion engine of claim 16 , further comprising an EGR system for introducing EGR to the combustion chamber, and the pressurized air/fuel purge charge does not include EGR.

18. The internal combustion engine of claim 17 , wherein a mixture of air, fuel, and EGR are presented in the combustion chamber prior to the compression stroke.

19. The internal combustion engine of claim 18 , wherein the pressurized air/fuel purge charge directed from the high-pressure air/fuel source is at stoichiometric conditions and the mixture of air, fuel and EGR are approximately at stoichiometric conditions.

20. The internal combustion engine of claim 18 , wherein the high-pressure air/fuel source is configured to cease directing the pressurized air/fuel purge charge to the prechamber volume during the compression stroke.

Assignees

• Caterpillar Inc

Inventors

• Willi Martin
• Kim Charlie

Classifications

• F02B19/18

  Transfer passages between chamber and cylinder · CPC title

• F02B19/1004 Primary

  details of combustion chamber, e.g. mounting arrangements · CPC title

• F02D41/3005

  Details not otherwise provided for · CPC title

• F02P13/00

  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 title

• Y02T10/12

  Improving ICE efficiencies · CPC title