Methods and systems for emissions control in a dual fuel engine

Patent metadata

Field	Value
Publication number	US-9932912-B2
Application number	US-201113041254-A
Country	US
Kind code	B2
Filing date	Mar 4, 2011
Priority date	Mar 4, 2011
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

Abstract

Various methods and systems are provided for an engine with an exhaust gas treatment system. In one example, under a first condition, a first fuel is delivered for combustion in the engine. Under a second condition, a second fuel is delivered for combustion in the engine, the second fuel different than the first fuel. Under a third condition, the first fuel is delivered as a reductant for the exhaust gas treatment system.

First claim

The invention claimed is:

1. A method for treatment of an exhaust gas in a dual fuel engine, comprising:
under a first condition, delivering a first fuel for combustion in the dual fuel engine;
under a second condition, delivering a second fuel for combustion in the dual fuel engine, where the second fuel is different than the first fuel, and wherein the first condition comprises a temperature of a cylinder of the dual fuel engine being above a first threshold temperature, and the second condition comprises the temperature of the cylinder being above a second threshold temperature, where the first threshold temperature is lower than the second threshold temperature, wherein the second threshold temperature corresponds to a temperature below which the second fuel ignites; and
under a third condition, delivering the first fuel as a reductant for the treatment of the exhaust gas.

2. The method of claim 1 , wherein the first fuel is delivered to one or more cylinders of the dual fuel engine by direct injection during an intake stroke of an engine cycle, and wherein the third condition includes when a nitrogen oxide conversion efficiency decreases below a threshold value.

3. The method of claim 1 , wherein, during the second condition, the second fuel is delivered to one or more cylinders of the dual fuel engine by direct injection.

4. The method of claim 3 , wherein delivering the first fuel as a reductant includes delivering the first fuel to the one or more cylinders of the dual fuel engine during an exhaust stroke of an engine cycle.

5. The method of claim 1 , wherein, during the second condition, the first fuel is delivered to one or more cylinders of the dual fuel engine by port injection during an intake stroke of an engine cycle.

6. The method of claim 5 , wherein delivering the first fuel as a reductant includes delivering the first fuel by port injection to the one or more cylinders of the dual fuel engine during positive valve overlap while the dual fuel engine is boosted.

7. The method of claim 5 , wherein delivering the first fuel as a reductant includes delivering the first fuel by an injector positioned upstream of a selective catalytic reduction catalyst in the exhaust gas treatment system.

8. The method of claim 5 , wherein the exhaust gas treatment system is positioned upstream of an exhaust gas recirculation inlet.

9. The method of claim 1 , wherein the first threshold temperature corresponds to a temperature at which the first fuel can mix with the intake air in the cylinder at an instantaneous pressure of the cylinder such that the first fuel is not ignited and premixing of the first fuel and intake air occurs.

10. A method for treatment of an exhaust gas in a dual fuel engine, comprising:
under a first condition, delivering a first fuel directly into a cylinder of the dual fuel engine for combustion in the dual fuel engine during an intake stroke of an engine cycle;
under a second condition, delivering a second fuel in the cylinder of the dual fuel engine for combustion in the dual fuel engine during a compression stroke of the engine cycle, where the second fuel is different than the first fuel, and wherein the first condition comprises a temperature of the cylinder being above a first threshold temperature, and the second condition comprises the temperature of the cylinder being above a second threshold temperature, where the first threshold temperature is lower than the second threshold temperature, wherein the second threshold temperature corresponds to a temperature below which the second fuel ignites; and
under a third condition, delivering the first fuel in the cylinder of the dual fuel engine as a reductant for a selective catalytic reduction catalyst in the exhaust gas treatment system during an exhaust stroke of the engine cycle.

11. The method of claim 10 , wherein the first fuel is delivered by a first direct injector in the cylinder.

12. The method of claim 10 , wherein the second fuel is delivered by a second direct injector in the cylinder.

13. The method of claim 10 , wherein the selective catalytic reduction catalyst is positioned upstream of a turbine of a turbocharger.

14. The method of claim 10 , wherein the third condition includes nitrogen oxide conversion efficiency below a threshold value.

15. The method of claim 10 , wherein the third condition includes an amount of reductant stored in the selective catalytic reduction catalyst less than a threshold amount.

16. The method of claim 10 , wherein the first fuel is ethanol and the second fuel is diesel.

17. The method of claim 10 , wherein the first threshold temperature corresponds to a temperature at which the first fuel can mix with the intake air in the cylinder at an instantaneous pressure of the cylinder such that the first fuel is not ignited and premixing of the first fuel and intake air occurs.

18. A system for a dual fuel engine, comprising:
a first fuel system for ethanol fuel;
a second fuel system for diesel fuel;
a selective catalytic reduction catalyst positioned in an exhaust passage of the dual fuel engine;
a controller configured to, during a single cylinder cycle, deliver a first injection of the ethanol fuel for combustion in the dual fuel engine under a first condition, deliver the diesel fuel under a second condition, and deliver a second injection of the ethanol fuel during an exhaust stroke of the cycle as a reductant for the selective catalytic reduction catalyst, and wherein the first condition comprises a temperature of a cylinder of the dual fuel engine being above a first threshold temperature, and the second condition comprises the temperature of the cylinder being above a second threshold temperature, where the first threshold temperature is lower than the second threshold temperature, wherein the second threshold temperature corresponds to a temperature below which the diesel fuel ignites.

19. The system of claim 18 , wherein the dual fuel engine is positioned in a locomotive, and the dual fuel engine is a V-12 four-stroke engine.

20. The system of claim 18 wherein the cylinder includes a first direct injector and a second direct injector, the first injector delivering the first and second injection of the ethanol and the second injector delivering the diesel fuel, and wherein the second injection of ethanol is delivered during valve overlap.

21. The method of claim 18 , wherein the first threshold temperature corresponds to a temperature at which the ethanol can mix with the intake air in the cylinder at an instantaneous pressure of the cylinder such that the ethanol is not ignited and premixing of the ethanol and intake air occurs.

Assignees

• Walker David James
• Joshi Narendra
• Klingbeil Adam
• Gen Electric

Inventors

• Walker David James
• Joshi Narendra
• Klingbeil Adam

Classifications

• F02D41/0025

  Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures · CPC title

• F02D19/0689

  for in-cylinder direct injection · CPC title

• F01N2560/026

  for measuring or detecting NOx · CPC title

• Y02T10/20

  Cross-Sectional Technologies · mapped topic

• F01N2610/03

  the substance being hydrocarbons, e.g. engine fuel · CPC title