Fuel system protection in a multi-fuel internal combustion engine

Patent metadata

Field	Value
Publication number	US-9624864-B2
Application number	US-201514678694-A
Country	US
Kind code	B2
Filing date	Apr 3, 2015
Priority date	Oct 9, 2012
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

A method of protecting a direct injection fuel injector in a multi-fuel engine, the method includes selectively operating the multi-fuel engine with a directly injected fuel introduced through the direct injection fuel injector and a second fuel; when fuelling the multi-fuel engine with the second fuel, selectively commanding a fuel system protection technique when determining that the direct injection fuel injector requires cooling, an age of directly injected fuel is above a predetermined value, transmission status has changed, an engine shutdown event has occurred and a global positioning system signal indicates an engine shutdown event will occur; wherein the fuel system protection technique includes commanding that the directly injected fuel be a portion of total fuel consumed and reducing quantities of the second fuel that is injected so that total fuel consumed equals a desired amount of fuel measured on an energy basis.

First claim

What is claimed is:

1. A method of protecting a direct injection fuel injector in a multi-fuel engine, said method comprising:
selectively operating said multi-fuel engine with at least one of a directly injected fuel introduced through said direct injection fuel injector and a second fuel;
when fuelling said multi-fuel engine with said second fuel, selectively commanding a fuel system protection technique when determining that at least one of said direct injection fuel injector requires cooling based on a temperature model for said direct injection fuel injector, an age of directly injected fuel is above a predetermined value, transmission status has changed, an engine shutdown event has occurred and driving pattern recognition predicts a shutdown event will occur;
wherein said fuel system protection technique comprises commanding that said directly injected fuel be a portion of total fuel consumed and reducing quantities of said second fuel that is injected so that total fuel consumed equals a desired amount of fuel measured on an energy basis.

2. The method of claim 1 , wherein said multi-fuel engine comprises a plurality of cylinders, said fuel system protection technique comprises:
(a) co-fuelling a cylinder corresponding to an ignition firing event with said directly injected fuel and said second fuel;
(b) fuelling cylinders corresponding to a predetermined number of subsequent ignition firing events with said second fuel; and
(c) repeating steps (a) and (b).

3. The method of claim 2 , further comprising selecting a co-fuelling fuel ratio.

4. The method of claim 2 , further comprising selecting a cylinder skip parameter.

5. The method of claim 4 , further comprising:
selecting a random number; and
modifying said cylinder skip parameter based on a function of said random number.

6. The method of claim 5 , wherein said cylinder skip parameter is modified after co-fuelled ignition firing events.

7. The method of claim 1 , wherein said multi-fuel engine comprises a plurality of cylinders, further comprising:
co-fuelling at least a portion of said plurality of cylinders with said second fuel and said directly injected fuel;
delaying introduction of said directly injected fuel when a quantity of said directly injected fuel to introduce in an injection event is below a predetermined value;
integrating said quantity of said directly injected fuel; and
introducing said directly injected fuel when an integrated quantity is greater than said predetermined value.

8. The method of claim 7 , further comprising adjusting a second fuel quantity to introduce into said cylinder when introduction of said directly injected fuel into said multi-fuel engine is delayed.

9. The method of claim 7 , further comprising adjusting a second fuel quantity to introduce into said cylinder when at least said minimum quantity of directly injected fuel is introduced into said cylinder.

10. The method of claim 1 , wherein when said multi-fuel engine at least operates with said second fuel, said fuel system protection technique comprises:
selecting an enriched air-fuel ratio;
selecting a co-fuelling fuel ratio; and
introducing or increasing a quantity of said directly injected fuel into said cylinder to operate at said enriched air-fuel ratio.

11. The method of claim 1 , where said second fuel is a second directly injected fuel.

12. The method of claim 1 , wherein said second fuel is a fumigated fuel.

13. The method of claim 1 , wherein said second fuel comprises at least one of methane and natural gas.

14. The method of claim 1 , wherein said directly injected fuel comprises one of gasoline and ethanol-gasoline blends.

15. An apparatus for protecting a fuel system in a multi-fuel engine comprising:
a direct fuel injector for introducing a directly injected fuel into a combustion chamber of said multi-fuel engine;
a second injector for introducing a second fuel;
an electronic controller programmed to:
selectively operate said multi-fuel engine with at least one of said directly injected fuel and said second fuel;
when fuelling said multi-fuel engine with said second fuel, selectively command a fuel system protection technique when determining that at least one of said direct injection fuel injector requires cooling based on a temperature model for said direct injection fuel injector, an age of directly injected fuel is above a predetermined value, transmission status has changed, an engine shutdown event has occurred and driving pattern recognition predicts an engine shutdown event will occur;

wherein said electronic controller commands said fuel system protection technique comprising that said directly injected fuel be a portion of total fuel consumed and reduce quantities of said second fuel that is injected so that total fuel consumed equals a desired amount of fuel measured on an energy basis.

16. The apparatus of claim 15 , further comprising a fumigation system for introducing a fumigated fuel upstream of an intake valve of said combustion chamber; wherein said second fuel is said fumigated fuel and said second injector introduces said fumigated fuel.

17. The apparatus of claim 15 , wherein said multi-fuel engine comprises a plurality of cylinders and each cylinder having a combustion chamber, said electronic controller is further programmed to:
(a) co-fuel a cylinder corresponding to an ignition firing event with said directly injected fuel and said second fuel;
(b) fuel cylinders corresponding to a predetermined number of subsequent ignition firing events with said second fuel; and
(c) repeat steps (a) and (b).

18. The apparatus of claim 15 , wherein said multi-fuel engine comprises a plurality of cylinders, said electronic controller is further programmed to:
co-fuel at least a portion of said plurality of cylinders with said second fuel and said directly injected fuel;
delay introduction of said directly injected fuel when a quantity of said directly injected fuel to introduce in an injection event is below a predetermined value;
integrate said quantity of said directly injected fuel; and
introduce said directly injected fuel when an integrated quantity is greater than said predetermined value.

19. The apparatus of claim 15 , wherein when said multi-fuel engine at least operates with said second fuel, said electronic controller is further programmed to:
select an enriched air-fuel ratio;
select a co-fuelling fuel ratio; and
introduce or increase a quantity of said directly injected fuel into said cylinder to operate at said enriched air-fuel ratio.

20. The apparatus of claim 15 , where said directly injected fuel is at least one of gasoline and ethanol, and said second fuel is at least one of methane and natural gas.

Assignees

• Westport Power Inc

Inventors

• Dunn Mark E
• Wu Ning
• Zhang Dehong
• Karimi-Sharif Hamed
• Bzymek Raymond

Classifications

• F02D41/38

  of the high pressure type · CPC title

• F02D19/0647

  the gaseous fuel being liquefied petroleum gas [LPG], liquefied natural gas [LNG], compressed natural gas [CNG] or dimethyl ether [DME] · CPC title

• F02D2041/224

  Diagnosis of the fuel system · CPC title

• F02D19/0692

  Arrangement of multiple injectors per combustion chamber · CPC title

• F02D19/081

  Adjusting the fuel composition or mixing ratio; Transitioning from one fuel to the other · CPC title