Apparatus and method for fuelling a flexible-fuel internal combustion engine

Patent metadata

Field	Value
Publication number	US-9856837-B2
Application number	US-201414272469-A
Country	US
Kind code	B2
Filing date	May 7, 2014
Priority date	Nov 22, 2011
Publication date	Jan 2, 2018
Grant date	Jan 2, 2018

Abstract

A flexible-fuel internal combustion engine apparatus comprises a combustion chamber, an intake valve, a first fuel injector, a second fuel injector, and a computer. The intake valve is operable to admit an intake charge into the combustion chamber. The first fuel injector injects a gaseous fuel directly into the combustion chamber. The second fuel injector injects a liquid fuel into the intake charge upstream of the intake valve. The computer is operatively connected with the first fuel injector and the second fuel injector to actuate injection of fuel respectively therefrom. The computer is programmed to command a gaseous-to-liquid fuel ratio as a function of at least one operating parameter from a group comprising gaseous fuel pressure, gaseous fuel mass, engine speed, engine torque, inlet air temperature, inlet air humidity, knock detection, operating history, torque command, and emissions.

First claim

What is claimed is:

1. An apparatus for delivering two fuels to a combustion chamber of an internal combustion engine, the apparatus comprising:
(a) a first fuel system comprising a first fuel supply and a first fuel pressure regulator operatively connected with said first fuel supply, said first fuel supply comprising a source of a gaseous fuel;
(b) a first fuel injector for directly injecting said gaseous fuel into said combustion chamber, said first fuel injector operatively connected with said first fuel pressure regulator;
(c) a second fuel system comprising a second fuel supply, a fuel pump operatively connected with said second fuel supply and a second fuel pressure regulator operatively connected with said fuel pump, said second fuel supply comprising a source of a liquid fuel;
(d) a second fuel injector for injecting said liquid fuel upstream of an intake valve operative to admit an intake charge into said combustion chamber, said second fuel injector operatively connected with said second fuel pressure regulator; and
(e) a computer operatively connected with said first fuel injector and said second fuel injector to actuate injection of fuel respectively therefrom, said computer programmed to:
(i) command a gaseous-to-liquid fuel ratio as a function of inputs comprising at least one of gaseous fuel storage pressure, gaseous fuel injection pressure, gaseous fuel mass, engine speed, engine torque, inlet air temperature, inlet air humidity, intake air manifold pressure, intake air mass, knock detection, operating history, torque command, and emissions;
(ii) select a gaseous-fuel operating mode whenever a quantity of gaseous fuel is above an upper threshold whereby only gaseous fuel is employed in said gaseous fuel operating mode for the full load capacity of said engine and select a liquid-fuel operating mode when the quantity of gaseous fuel is below the upper threshold;
(iii) selectively actuate the first fuel injector to inject the gaseous fuel during the gaseous-fuel operating mode, the gaseous-to-liquid fuel ratio being mathematically undefined during the gaseous-fuel operating mode; and
(iv) selectively actuate the second fuel injector to inject the liquid fuel during the liquid-fuel operating mode, the gaseous-to-liquid fuel ratio being zero during the liquid-fuel operating mode.

2. The apparatus of claim 1 , wherein said gaseous fuel is selected from the group consisting of natural gas and methane.

3. The apparatus of claim 1 , wherein said liquid fuel is selected from the group consisting of gasoline and ethanol/gasoline blends.

4. The apparatus of claim 1 , wherein said first fuel pressure regulator is a single-step regulator.

5. The apparatus of claim 1 , wherein said first fuel pressure regulator is one of a continuously variable pressure regulator and a multi-step regulator.

6. The apparatus of claim 1 , wherein said first fuel pressure regulator regulates said gaseous-fuel injection pressure between 10 bar and 300 bar.

7. The apparatus of claim 1 , wherein said first fuel pressure regulator regulates said gaseous-fuel injection pressure between 10 bar and 40 bar.

8. The apparatus of claim 1 , wherein said first fuel pressure regulator regulates said gaseous-fuel injection pressure between 10 bar and 20 bar.

9. The apparatus of claim 1 , wherein said second fuel pressure regulator regulates said liquid-fuel injection pressure between 2 bar and 10 bar.

10. The apparatus of claim 1 , wherein said second fuel pressure regulator regulates said liquid-fuel injection pressure between 2 bar and 6 bar.

11. The apparatus of claim 1 , wherein said computer is further programmed to shut-off said internal combustion engine after idling for a predetermined idle-time threshold.

12. The apparatus of claim 1 , wherein said computer is further programmed to actuate said first fuel injector to introduce a stratified fuel charge in said combustion chamber during cold-start of said internal combustion engine resulting in at least one of reduced emissions and improved stability.

13. The apparatus of claim 1 , wherein said gaseous fuel is injected no less than 40 degrees before top dead center during a compression stroke associated with said combustion chamber during said gaseous-fuel operating mode.

14. The apparatus of claim 1 , wherein said gaseous fuel is injected no less than 60 degrees before top dead center during a compression stroke associated with said combustion chamber during said gaseous-fuel operating mode.

15. The apparatus of claim 1 , wherein said computer is further programmed to select one of said gaseous-fuel operating mode and said liquid-fuel operating mode as a function of inputs comprising at least one of gaseous-fuel storage pressure, gaseous-fuel mass, liquefied gaseous-fuel level, liquefied gaseous-fuel volume, liquefied gaseous-fuel mass, and gaseous fuel injection pressure.

16. The apparatus of claim 1 , wherein said computer is further programmed to selectively actuate said first fuel injector after said intake valve closes.

17. The apparatus of claim 1 , wherein said computer is further programmed to selectively actuate said first fuel injector to start injecting gaseous fuel while said intake valve is open.

18. The apparatus of claim 1 , wherein when a predetermined condition is detected during said gaseous-fuel operating mode, said computer is further programmed to mathematically define said gaseous-to-liquid fuel ratio and to selectively actuate said second fuel injector for periodic injection of liquid fuel.

19. The apparatus of claim 18 , wherein said predetermined condition is at least one of a lubricate-time threshold, a cool-time threshold, a clean-time threshold, and a liquid-fuel-cycle-time threshold, and said predetermined condition is detected when at least one of said thresholds is met or exceeded.

20. The apparatus of claim 18 , wherein said computer is further programmed to selectively actuate said second fuel injector during said gaseous-fuel operating mode as a function of inputs comprising at least one of average crank rotational speed, gaseous fuel consumed, average torque, inlet temperature, mass air flow, engine temperature, coolant temperature, and time since said second fuel supply was filled.

21. The apparatus of claim 1 , wherein when a predetermined condition is detected during said liquid-fuel operating mode said computer is further programmed to command a gaseous-to-liquid fuel ratio greater than zero and to selectively actuate said first fuel injector for periodic injection of gaseous fuel.

22. The apparatus of claim 21 , wherein said predetermined condition is a threshold level of engine knock, and said apparatus further comprises an engine knock sensor, said computer programmed responsive to an output of said engine knock sensor to selectively actuate said first fuel injector during said liquid-fuel operating mode when said output meets or exceeds said threshold level of engine knock.

23. The apparatus of claim 21 , wherein said predetermined condition is a threshold level of emissions, and said apparatus further comprises an emissions sensor, said computer programmed responsive to an output of said emissions sensor to selectively actuate said first fuel injector during said liquid-fuel operating mode when said output meets or exceeds said threshold level of emissions.

24. The apparatus of claim 1 , wherein said computer is further programmed to select a dual-fuel operating mode when

Assignees

• Westport Power Inc

Inventors

• Dunn Mark E
• Lapetz John M
• Welch Alan B

Classifications

• F02D19/0628

  Determining the fuel pressure, temperature or flow, the fuel tank fill level or a valve position · CPC title

• 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

• Y02T10/36

  Cross-Sectional Technologies · mapped topic

• F02D19/0642

  at least one fuel being gaseous, the other fuels being gaseous or liquid at standard conditions · CPC title

• F02D35/027

  using knock sensors · CPC title