Systems and methods for increasing oxygen levels in an active pre-chamber

1. A method, comprising:

purging gases from a pre-chamber to a cylinder by injecting oxygen into the pre-chamber, including performing a first oxygen injection into the pre-chamber during an intake stroke of the cylinder and performing a second oxygen injection into the pre-chamber during a compression stroke of the cylinder, wherein an amount of the first oxygen injection is greater than an amount of the second oxygen injection; and

reducing a flow of the oxygen from the pre-chamber to the cylinder by directing fuel toward an orifice fluidically coupling the pre-chamber and the cylinder via a cylinder fuel injection event.

2. The method of claim 1 , wherein purging the gases from the pre-chamber to the cylinder includes flowing the gases from the pre-chamber to the cylinder via the orifice based on a pressure difference between the pre-chamber and the cylinder, and the gases are residual gases from a previous combustion event in the pre-chamber.

3. The method of claim 1 , further comprising:

injecting fuel into the pre-chamber during the compression stroke; and

combusting the oxygen and the fuel in the pre-chamber by actuating a pre-chamber spark plug.

4. The method of claim 1 , wherein reducing the flow of the oxygen from the pre-chamber to the cylinder by directing the fuel toward the orifice via the cylinder fuel injection event includes at least partially occluding the orifice with a portion of the fuel from the cylinder fuel injection event, the portion of the fuel from the cylinder fuel injection event flowing from a spray port of a direct fuel injector of the cylinder that is directed at the orifice.

5. The method of claim 1 , wherein the oxygen is included in ambient air, and injecting the oxygen into the pre-chamber comprises injecting the ambient air into the pre-chamber.

6. The method of claim 1 , wherein the oxygen is included in oxygen-enriched air, and injecting the oxygen into the pre-chamber comprises injecting the oxygen-enriched air into the pre-chamber.

7. A method, comprising:

during an intake stroke of a cylinder, performing a first air injection into a pre-chamber to flow residual exhaust gas from the pre-chamber to the cylinder via a pre-chamber opening; and

during a compression stroke of the cylinder, performing a second air injection into the pre-chamber, an amount of the second air injection smaller than an amount of the first air injection, and injecting fuel into the cylinder, a portion of the fuel injected into the cylinder directed at the pre-chamber opening.

8. The method of claim 7 , wherein the intake stroke and the compression stroke are in a same combustion cycle of the cylinder.

9. The method of claim 7 , further comprising, during the compression stroke of the cylinder:

injecting pre-chamber fuel into the pre-chamber after performing the second air injection into the pre-chamber; and

actuating a spark plug of the pre-chamber after both injecting the pre-chamber fuel into the pre-chamber and injecting the fuel into the cylinder.

10. The method of claim 7 , wherein injecting the fuel into the cylinder includes actuating a direct fuel injector coupled to the cylinder for at least one fuel injection event.

11. The method of claim 7 , wherein the portion of the fuel injected into the cylinder directed at the pre-chamber opening at least partially blocks the pre-chamber opening.

12. A system, comprising:

an engine including a plurality of cylinders, each cylinder including a cylinder fuel injector and a pre-chamber of a pre-chamber ignition system, the pre-chamber fluidically coupled to the corresponding cylinder via a pre-chamber opening; and

a controller storing executable instructions in non-transitory memory that, when executed, cause the controller to:

purge gases from the pre-chamber to the corresponding cylinder by performing a first air injection into the pre-chamber during an intake stroke of the corresponding cylinder and performing a second air injection into the pre-chamber during a compression stroke of the corresponding cylinder, a first amount of air injected in the first air injection greater than a second amount of the air injected in the second air injection; and

inject fuel onto the pre-chamber opening via the cylinder fuel injector.

13. The system of claim 12 , wherein the pre-chamber includes a spark plug configured to initiate combustion in the pre-chamber, and wherein the gases purged from the pre-chamber to the corresponding cylinder are residual gases from a previous combustion event in the pre-chamber.

14. The system of claim 13 , wherein the pre-chamber further includes an air injector, and to purge the gases from the pre-chamber to the corresponding cylinder, the controller includes further instructions stored in the non-transitory memory that, when executed, cause the controller to:

actuate the air injector during the intake stroke of the corresponding cylinder to inject the first amount of the air; and

actuate the air injector during the compression stroke of the corresponding cylinder to inject the second amount of the air.

15. The system of claim 14 , wherein the cylinder fuel injector includes a nozzle configured to spray the fuel in a plurality of fuel flow vectors, at least one fuel flow vector of the plurality of fuel flow vectors directed at the pre-chamber opening, and to inject the fuel onto the pre-chamber opening via the cylinder fuel injector, the controller includes further instructions in the non-transitory memory that, when executed, cause the controller to:

actuate the cylinder fuel injector to spray the fuel onto the pre-chamber opening via the at least one fuel flow vector during the compression stroke of the corresponding cylinder.

16. The system of claim 15 , wherein the pre-chamber further includes a pre-chamber fuel injector, and the controller includes further instructions stored in the non-transitory memory that, when executed, cause the controller to:

actuate the pre-chamber fuel injector during the compression stroke of the corresponding cylinder immediately following the intake stroke to inject the fuel into the pre-chamber; and

actuate the spark plug to combust the air and the fuel in the pre-chamber.