Mid-cycle fuel injection strategies

Patent metadata

Field	Value
Publication number	US-9482168-B2
Application number	US-201514738838-A
Country	US
Kind code	B2
Filing date	Jun 13, 2015
Priority date	Dec 20, 2012
Publication date	Nov 1, 2016
Grant date	Nov 1, 2016

Abstract

A method and apparatus are disclosed for introducing a gaseous fuel into a combustion chamber of an internal combustion engine. The method includes dividing the engine map into three distinct operating regions, with different operating modes in each region. When the engine is operating in a low load region, gaseous fuel is introduced to the combustion chamber during an intake stroke before an intake valve associated with the combustion chamber closes. When the engine is operating in a high load low-speed region, gaseous fuel is directly injected into the combustion chamber during a compression stroke after the intake valve is closed. When the engine is operating in a high load high-speed region, a split injection strategy is employed with a first portion of the gaseous fuel introduced into the charge before the intake valve closes and a second portion being injected after the intake valve is closed.

First claim

What is claimed is:

1. A method for introducing a gaseous fuel into a combustion chamber of an internal combustion engine comprises:
(a) dividing an engine map into a first region, a second region, and a third region, wherein said engine operates in a first mode is in said first region, a second mode in said second region, and a third mode in said third region:
(i) wherein said first region is a predetermined low load range and said first mode comprises
introducing said gaseous fuel to said combustion chamber during an intake stroke before an intake valve closes;

(ii) wherein said second region is a predetermined high load low-speed range and said second mode comprises
injecting said gaseous fuel directly into said combustion chamber after said intake valve closes; and;

(iii) wherein said third region is a predetermined high load high-speed range and said third mode comprises
(1) introducing a first portion of said gaseous fuel into said combustion chamber during said intake stroke before said intake valve closes; and
(2) injecting a second portion of said gaseous fuel directly into said combustion chamber after said intake valve closes.

2. The method of claim 1 , further comprising:
(b) introducing said gaseous fuel upstream of said intake valve such that it is inducted into said combustion chamber along with intake air, when said gaseous fuel is introduced during said intake stroke.

3. The method of claim 1 , further comprising:
(b) closing said intake valve before bottom dead center during said intake stroke.

4. The method of claim 1 , further comprising:
(b) closing said intake valve before bottom dead center during said intake stroke;
(c) increasing intake manifold air pressure such that an increased amount of oxygen is inducted into said combustion chamber before said intake valve closes; and
(d) timing for start of injection for injecting said gaseous fuel directly into said combustion chamber is between 180 and 210 crank angle degrees before top dead center.

5. The method of claim 1 , further comprising:
(b) closing said intake valve after bottom dead center during said compression stroke, wherein this timing for closing said intake valve is associated with said first mode when said engine is operating in said first region.

6. The method of claim 1 wherein one of said second and said third regions are divided by a fixed predetermined engine speed and said second and third regions are divided by a predetermined power demarcation line.

7. The method of claim 1 wherein when injecting said gaseous fuel directly into said combustion chamber, said gaseous fuel is supplied to a fuel injector with an injection pressure between 20 and 40 bar.

8. The method of claim 1 , further comprising:
(b) compressing said gaseous fuel to said injection pressure when said gaseous fuel is stored in gaseous form; and
(c) pumping said gaseous fuel to said injection pressure when said gaseous fuel is stored in liquefied form,
wherein when injecting said gaseous fuel directly into said combustion chamber, said gaseous fuel is supplied to a fuel injector with an injection pressure between 20 and 40 bar.

9. The method of claim 1 wherein when injecting said gaseous fuel directly into said combustion chamber, timing for end of injection is between 65 and 200 crank angle degrees before top dead center.

10. The method of claim 1 wherein when injecting said gaseous fuel directly into said combustion chamber, timing for start of injection is between 150 and 210 crank angle degrees before top dead center.

11. The method of claim 1 , wherein said gaseous fuel is natural gas.

12. A method for introducing a gaseous fuel into a combustion chamber of an internal combustion engine comprising:
(b) introducing said gaseous fuel into said combustion chamber during an intake stroke in a first region of an engine map associated with operating said internal combustion engine;
(c) introducing said gaseous fuel into said combustion chamber during a compression stroke in a second region of said engine map after an intake valve associated with said combustion chamber closes; and
(d) introducing said gaseous fuel into said combustion chamber during both said intake stroke and said compression stroke in a third region of said engine map, wherein said first region is a low load region of said engine map, said second region is a high load region of said engine map below at least one of a predetermined power level and a predetermined speed, and said third region is a high load region of said engine map above said at least one of said predetermined power level and said predetermined speed.

13. The method of claim 12 , wherein one of in said first region said gaseous fuel is introduced upstream of said intake valve and in said first region said gaseous fuel is directly introduced into said combustion chamber.

14. The method of claim 12 , wherein in said second region said gaseous fuel is directly introduced into said combustion chamber.

15. The method of claim 12 , wherein one of in said third region said gaseous fuel is introduced to said combustion chamber upstream of said intake valve during said intake stroke and directly introduced into said combustion chamber during said compression stroke and in said third region said gaseous fuel is directly introduced to said combustion chamber during said intake stroke and said compression stroke.

16. The method of claim 12 , wherein said engine map is defined by a first engine parameter along an x-axis and a second engine parameter along a y-axis.

17. The method of claim 16 , wherein said first engine parameter is engine speed, and said second engine parameter is one of torque and fuel quantity per cycle.

18. An apparatus for introducing a gaseous fuel into a combustion chamber of an internal combustion engine comprising:
(a) a fuel injection apparatus for introducing said gaseous fuel into a charge for said internal combustion engine, said fuel injection apparatus comprising:
(i) a direct fuel injector for injecting said gaseous fuel directly into said combustion chamber;
(ii) a controller programmed to actuate said fuel injection apparatus according to three modes, to:
(1) introduce gaseous fuel into said charge during an intake stroke while an intake valve associated with said combustion chamber is open, when said internal combustion engine is operating in a first mode, defined by a predetermined low load range;
(2) actuate said direct fuel injector to inject said gaseous fuel directly into said combustion chamber after said intake valve is closed, when said internal combustion engine is operating in a second mode, defined by a predetermined high load low-speed range; and
(3) split fuel injection into two pulses whereby a first portion of said gaseous fuel is introduced into said charge during an intake stroke while said intake valve is open, and a second portion is introduced by actuating said direct fuel injection to inject said fuel directly into said combustion chamber after said intake valve is closed, when said internal combustion engine is operating in a third mode defined by a predetermined high load high-speed range.

19. The apparatus of claim 18 wherein said fuel injection apparatus further comprises:
(iii) a port fuel injector associated with a port leading into said combustion chamber for introducing said gaseous fuel upstream of said intake valve whereby it is inducted into said combustion chamber with the intake charge.

20. The apparatus of claim 18 wherein said

Assignees

• Westport Power Inc

Inventors

• Dunn Mark E
• Welch Alan B

Classifications

• F02M21/0278

  Port fuel injectors for single or multipoint injection into the air intake system · CPC title

• F02M21/0284

  Arrangement of multiple injectors or fuel-air mixers per combustion chamber · CPC title

• F02M21/0215

  Mixtures of gaseous fuels; Natural gas; Biogas; Mine gas; Landfill gas · CPC title

• 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

• 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