Systems and methods for catalyst heating during cold-start with an active pre-chamber

Patent metadata

Field	Value
Publication number	US-11255284-B2
Application number	US-202016801561-A
Country	US
Kind code	B2
Filing date	Feb 26, 2020
Priority date	Feb 26, 2020
Publication date	Feb 22, 2022
Grant date	Feb 22, 2022

Abstract

Methods and systems are provided for operating a cylinder of an engine including a pre-chamber ignition system during a cold start condition. In one example, a method may include performing a post-injection in the cylinder, and then performing a pre-chamber combustion during an exhaust stroke of the cylinder. In this way, a temperature of a catalyst of the engine may be increased, which may decrease vehicle emissions during the cold start condition.

First claim

The invention claimed is:

1. A method, comprising:
during a cold start condition, injecting a first amount of post-injection fuel in a pre-chamber and a second amount of post-injection fuel in a cylinder during an exhaust stroke of the cylinder to heat a catalyst, the first amount based on an air-fuel ratio (AFR) of a first pre-chamber air-fuel mixture and the second amount based on an AFR of a first cylinder air-fuel mixture;
combusting the first pre-chamber air-fuel mixture in the pre-chamber during a compression stroke of the cylinder to ignite the first cylinder air-fuel mixture; and
combusting a second pre-chamber air-fuel mixture in the pre-chamber, including the first amount of post-injection fuel, during the exhaust stroke of the cylinder to ignite the second amount of post-injection fuel injected in the cylinder.

2. The method of claim 1 , wherein combusting an air-fuel mixture in the pre-chamber of the cylinder includes:
delivering air for the air-fuel mixture via a pre-chamber air injector;
delivering fuel for the air-fuel mixture via a pre-chamber fuel injector; and
igniting the air-fuel mixture via a pre-chamber spark plug.

3. The method of claim 1 , wherein injecting the second amount of post-injection fuel in the cylinder during the exhaust stroke of the cylinder includes delivering fuel for a post injection via a cylinder fuel injector.

4. The method of claim 1 , wherein the AFR of exhaust gas from each combustion cycle is substantially stoichiometric.

5. The method of claim 1 , wherein the AFR of the first pre-chamber air-fuel mixture is rich relative to the AFR of the first cylinder air-fuel mixture.

6. The method of claim 1 , wherein the cold start condition is indicated following a threshold number of engine cycles after an engine start.

7. The method of claim 1 , wherein the cold start condition is indicated responsive to a number of crankshaft revolutions after an engine start increasing above a threshold number of crankshaft revolutions after the engine start.

8. The method of claim 1 , wherein the cold start condition is indicated responsive to a catalyst temperature of the catalyst decreasing below a threshold catalyst temperature.

9. A method, comprising:
responsive to an engine start, operating a cylinder with a first pre-chamber air-fuel ratio (AFR) and a first cylinder AFR during a compression stroke of the cylinder; and
responsive to exceeding a threshold number of engine cycles after the engine start, operating the cylinder with a second pre-chamber AFR and a second cylinder AFR during the compression stroke of the cylinder, the second cylinder AFR based on the second pre-chamber AFR, the second pre-chamber AFR rich relative to the first pre-chamber AFR, and the second cylinder AFR lean relative to the first cylinder AFR; wherein
operating the cylinder with the second pre-chamber AFR and the second cylinder AFR during the compression stroke includes:
producing a first air-fuel mixture in the pre-chamber by injecting a first amount of fuel in the pre-chamber and injecting a first amount of air in the pre-chamber during an intake stroke of the cylinder, the first amount of fuel and the first amount of air determined based on the second pre-chamber AFR;
producing a second air-fuel mixture in the cylinder by injecting a second amount of fuel in the cylinder during the intake stroke of the cylinder, the second amount of fuel based in part on the second cylinder AFR;
igniting the first air-fuel mixture in the pre-chamber via a spark plug to generate flames during the compression stroke of the cylinder; and
igniting the second air-fuel mixture in the cylinder via the flames from the pre-chamber during the compression stroke of the cylinder.

10. The method of claim 9 , wherein the second pre-chamber AFR is rich relative to stoichiometry, and the second cylinder AFR is lean relative to stoichiometry.

11. The method of claim 9 , further comprising:
responsive to exceeding the threshold number of engine cycles after the engine start, injecting a third amount of fuel in the cylinder and operating the pre-chamber with a third pre-chamber AFR during an exhaust stroke of the cylinder, the third amount of fuel based on the second pre-chamber AFR, the second cylinder AFR, and the third pre-chamber AFR.

12. The method of claim 11 , wherein operating the pre-chamber with the third pre-chamber AFR during the exhaust stroke of the cylinder includes:
determining the third pre-chamber AFR based in part on the second pre-chamber AFR;
producing a third air-fuel mixture in the pre-chamber by injecting a fourth amount of fuel in the pre-chamber and injecting a second amount of air in the pre-chamber during the exhaust stroke of the cylinder, the fourth amount of fuel and the second amount of air determined based on the third pre-chamber AFR; and
injecting a second amount of air in the pre-chamber during an exhaust stroke of the cylinder, the second amount of air determined based on the second pre-chamber AFR and the second cylinder AFR.

13. The method of claim 9 , wherein an AFR of exhaust gas from operating the cylinder with the second pre-chamber AFR and the second cylinder AFR is stoichiometric.

14. A system, comprising:
an engine including a plurality of cylinders, each cylinder including a pre-chamber of a pre-chamber ignition system and a fuel injector, wherein each pre-chamber comprises a spark plug and at least one unrestricted opening fluidly coupling an interior of the pre-chamber to an interior of a cylinder;
an emissions control device coupled in an exhaust passage of the engine; and
a controller storing executable instructions in non-transitory memory that, when executed, cause the controller to:
operate each cylinder with a first pre-chamber AFR and a first cylinder AFR during a compression stroke, the first cylinder AFR based on the first pre-chamber AFR;
ignite a first air-fuel mixture in a corresponding pre-chamber via the spark plug to initiate combustion of a second air-fuel mixture in the cylinder during the compression stroke of each cylinder;
operate each cylinder with a second pre-chamber AFR and a second cylinder AFR during an exhaust stroke via a post-injection into each of the pre-chamber and the cylinder, responsive to at least one of an indication of a cold start condition and a temperature of the emissions control device below a threshold temperature of the emissions control device to heat the emissions control device, the second pre-chamber AFR and the second cylinder AFR based on the first pre-chamber AFR and the first cylinder AFR;
inject an amount of fuel in the cylinder during the exhaust stroke of the cylinder; and
ignite a third air-fuel mixture in the corresponding pre-chamber via a spark plug during the exhaust stroke of each cylinder.

15. The system of claim 14 , wherein the amount of fuel is determined based in part on the first pre-chamber AFR, the first cylinder AFR, and the second pre-chamber AFR.

16. The system of claim 14 , wherein the first cylinder AFR is lean relative to stoichiometry, and the first pre-chamber AFR is rich relative to stoichiometry.

Assignees

• Ford Global Tech Llc

Inventors

• Glugla Chris Paul
• Czekala Michael Damian
• Shelby Michael

Classifications

• F02D41/3094

  the fuel injection being effected by at least two different injectors, e.g. one in the intake manifold and one in the cylinder · CPC title

• Y02T10/40

  Engine management systems · CPC title

• F01N2900/1602

  Temperature of exhaust gas apparatus · CPC title

• F02B19/12

  with positive ignition (engines with non-timed positive ignition, and with incandescent chambers F02B9/08) · CPC title

• F02D41/405

  with post injections · CPC title