Dedicated EGR cylinder post combustion injection

Patent metadata

Field	Value
Publication number	US-9534567-B2
Application number	US-201313915445-A
Country	US
Kind code	B2
Filing date	Jun 11, 2013
Priority date	Jun 11, 2013
Publication date	Jan 3, 2017
Grant date	Jan 3, 2017

Abstract

Systems and methods for increasing an amount of fuel injected into a dedicated exhaust gas recirculation (EGR) cylinder in an engine are disclosed. In one example approach, a method comprises, prior to combustion, injecting a first amount of fuel to a dedicated EGR cylinder, and after combustion and during an expansion and/or exhaust stroke, directly injecting a second amount of fuel to the dedicated EGR cylinder.

First claim

The invention claimed is:

1. A method for an engine, comprising:
determining a cold start condition;
if cold start conditions are determined not to be present:
prior to combustion, injecting a first amount of fuel to a dedicated EGR cylinder; and after combustion and during an expansion and/or exhaust stroke directly injecting a second amount of fuel to the dedicated EGR cylinder; and

if cold start conditions are determined to be present:
prior to combustion, injecting a third amount of fuel to the dedicated EGR cylinder; after combustion and at or near exhaust valve opening, directly injecting a fourth amount of fuel to the dedicated EGR cylinder; and maintaining a pre-combustion air fuel ratio of the dedicated EGR cylinder lean during the cold start conditions.

2. The method of claim 1 , wherein the engine is a spark-ignited engine.

3. The method of claim 1 , further comprising maintaining a rich air fuel ratio in the dedicated EGR cylinder if cold start conditions are determined not to be present.

4. The method of claim 1 , further comprising providing EGR from the dedicated EGR cylinder to an intake of the engine and, following directly injecting the second amount of fuel to the dedicated EGR cylinder, discontinuing providing EGR from the dedicated EGR cylinder to the intake.

5. The method of claim 1 , further comprising providing EGR from the dedicated EGR cylinder to all of the cylinders or the remaining engine cylinders.

6. The method of claim 1 , wherein, after injection of the second amount of fuel, a combustion air fuel ratio limit in the dedicated EGR cylinder is exceeded.

7. The method of claim 1 , further comprising reducing an amount of fuel injected into the remaining cylinders after directly injecting the second amount of fuel to the dedicated EGR cylinder.

8. The method of claim 1 , wherein an exhaust of the dedicated EGR cylinder is coupled to an intake of the engine.

9. The method of claim 1 , wherein the third amount is less than the first amount.

10. A method for an engine, comprising:
determining a cold start condition;
during engine cold start conditions:
prior to combustion, injecting a first amount of fuel to a dedicated EGR cylinder;
after combustion and at or near exhaust valve opening, directly injecting a second amount of fuel to the dedicated EGR cylinder, the first and second injections during a common cylinder combustion cycle and repeatedly performed in successive cycles of the dedicated EGR cylinder; and
maintaining a pre-combustion air fuel ratio of the dedicated EGR cylinder lean during the cold start conditions; and

following the cold start conditions:
prior to combustion, injecting a third amount of fuel to the dedicated EGR cylinder; after combustion and at or near exhaust valve opening, directly injecting a fourth amount of fuel to the dedicated EGR cylinder; and
maintaining a rich air fuel ratio in the dedicated EGR cylinder.

11. The method of claim 10 , wherein the cold start conditions comprise an engine temperature less than a threshold temperature.

12. The method of claim 10 , wherein the second amount of fuel is injected to the dedicated EGR cylinder during an expansion and/or exhaust stroke.

13. The method of claim 10 , wherein the engine is a spark-ignited engine.

14. The method of claim 10 , further comprising providing EGR from the dedicated EGR cylinder to all of the cylinders or the remaining engine cylinders.

15. The method of claim 10 , wherein the third amount of fuel is greater than the first amount of fuel and wherein, after injection of the fourth amount of fuel, a combustion air fuel ratio limit in the dedicated EGR cylinder is exceeded.

16. A method for a spark-ignited engine, comprising:
determining a cold start condition;
during engine cold start conditions:
prior to combustion, injecting a first amount of fuel to a dedicated EGR cylinder;
after combustion and at or near exhaust valve opening, directly injecting a second amount of fuel to the dedicated EGR cylinder;
maintaining an air fuel ratio of the dedicated EGR cylinder lean during the cold start conditions; and

following the cold start conditions:
prior to combustion, injecting a third amount of fuel to the dedicated EGR cylinder;
after combustion and at or near exhaust valve opening, directly injecting a fourth amount of fuel to the dedicated EGR cylinder; and
maintaining a rich air fuel ratio in the dedicated EGR cylinder.

17. The method of claim 16 , wherein the cold start conditions comprise an engine temperature less than a threshold temperature.

18. The method of claim 16 , wherein the second amount of fuel and the fourth amount of fuel are injected to the dedicated EGR cylinder during an expansion and/or an exhaust stroke.

19. A method, comprising:
determining a cold start condition;
responsive to a determination of cold start conditions when less than full EGR is desired; prior to combustion, injecting multiple fuel amounts to a dedicated EGR cylinder and maintaining a pre-combustion air fuel ratio of the dedicated EGR cylinder lean; and
responsive to a determination of no cold start, injecting multiple fuel amounts to the dedicated EGR cylinder and maintaining a post-combustion air fuel ratio in the dedicated EGR cylinder rich.

20. The method of claim 19 , wherein the lean pre-combustion air fuel ratio includes burning fuel via a stratified charge injection during a compression stroke of the dedicated EGR cylinder.

Assignees

• Ford Global Tech Llc

Inventors

• Ulrey Joseph Norman
• Ervin James Douglas
• Boyer Brad Alan
• Styles Daniel Joseph
• Mcconville Gregory Patrick
• Ku Kim Hwe

Classifications

• F02M26/05

  High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor · CPC title

• F02M26/43 Primary

  in which exhaust from only one cylinder or only a group of cylinders is directed to the intake of the engine · CPC title

• F02D19/12

  peculiar to engines working with non-fuel substances or with anti-knock agents, e.g. with anti-knock fuel · CPC title

• F02M26/02

  EGR systems specially adapted for supercharged engines · CPC title