EXHAUST GAS RECIRCULATION IN A HOMOGENEOUS CHARGE COMPRESSION IGNITION ENGINE

• US 20080092861A1
• Filed: 10/23/2006
• Published: 04/24/2008
• Est. Priority Date: 10/23/2006
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Rodman, Anthony, Hardy, William L., Hergart, Carl-Anders, Liechty, Michael P., Duffy, Kevin P., Kieser, Andrew J.
• Granted Patent: US 7,377,270 B2
• Time in Patent Office: Days
• US Class Current: 123/568.12
• CPC Class Codes: F01N 13/0097 the purifying devices are arranged in a single housing
• CPC Class Codes: F01N 13/107 More than one exhaust manifold or exhaust collector
• CPC Class Codes: F01N 2430/00 Influencing exhaust purification, e.g. starting of catalytic reaction, filter regeneration, or the like, by controlling engine operating characteristics
• CPC Class Codes: F01N 2560/025 for measuring or detecting O2, e.g. lambda sensors
• CPC Class Codes: F01N 2560/026 for measuring or detecting NOx
• CPC Class Codes: F01N 2560/14 having more than one sensor of one kind
• CPC Class Codes: F01N 3/023 using means for regenerating the filters, e.g. by burning trapped particles by electrically controlling the supply of combustible mixture or its constituents only F02D41/0235
• CPC Class Codes: F01N 3/035 with catalytic reactors , e.g. catalysed diesel particulate filters
• CPC Class Codes: F02B 2275/14 Direct injection into combustion chamber
• CPC Class Codes: F02B 29/0412 Multiple heat exchangers arranged in parallel or in series
• CPC Class Codes: F02B 29/0425 Air cooled heat exchangers
• CPC Class Codes: F02B 29/0468 Water separation or drainage means
• CPC Class Codes: F02B 37/004 with exhaust drives arranged in series
• CPC Class Codes: F02B 37/013 with exhaust-driven pumps arranged in series
• CPC Class Codes: F02B 37/025 Multiple scrolls or multiple gas passages guiding the gas to the pump drive
• CPC Class Codes: F02D 15/00 Varying compression ratio
• CPC Class Codes: F02D 41/0065 Specific aspects of external EGR control constructional details of EGR system F02M26/00
• CPC Class Codes: F02D 41/3035 a mode being the premixed charge compression-ignition mode
• CPC Class Codes: F02D 9/02 concerning induction conduits throttle valves, or arrangements thereof in conduits F02D9/08
• CPC Class Codes: F02M 26/05 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 Class Codes: F02M 26/06 : Low pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust downstream of the turbocharger turbine and reintroduced into the intake system upstream of the compressor
• CPC Class Codes: F02M 26/08 : for engines having two or more intake charge compressors or exhaust gas turbines, e.g. a turbocharger combined with an additional compressor
• CPC Class Codes: F02M 26/10 : having means to increase the pressure difference between the exhaust and intake system, e.g. venturis, variable geometry turbines, check valves using pressure pulsations or throttles in the air intake or exhaust system
• CPC Class Codes: F02M 26/15 : in relation to engine exhaust purifying apparatus
• CPC Class Codes: F02M 26/24 : with two or more coolers
• CPC Class Codes: F02M 26/35 : with means for cleaning or treating the recirculated gases, e.g. catalysts, condensate traps, particle filters or heaters
• CPC Class Codes: F02M 26/38 : with two or more EGR valves disposed in parallel
• CPC Class Codes: F02M 26/43 : in which exhaust from only one cylinder or only a group of cylinders is directed to the intake of the engine
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 : Engine management systems

Abstract

A homogeneous charge compression ignition engine operates by injecting liquid fuel directly in a combustion chamber, and mixing the fuel with recirculated exhaust and fresh air through an auto ignition condition of the fuel. The engine includes at least one turbocharger for extracting energy from the engine exhaust and using that energy to boost intake pressure of recirculated exhaust gas and fresh air. Elevated proportions of exhaust gas recirculated to the engine are attained by throttling the fresh air inlet supply. These elevated exhaust gas recirculation rates allow the HCCI engine to be operated at higher speeds and loads rendering the HCCI engine a more viable alternative to a conventional diesel engine.

Claims

1. A method of operating an engine, comprising the steps of:

mixing high and low pressure exhaust from upstream and downstream, respectively, of a turbocharger via a venturi connection;

supplying a mixture of exhaust and fresh air to a combustion chamber of the engine;

injecting liquid fuel into the combustion chamber prior to an auto-ignition condition of the fuel;

mixing the fuel with the exhaust/air mixture in the combustion chamber;

compressing the fuel/air/exhaust mixture through an auto-ignition condition of the fuel;

increasing a proportion of exhaust gas supplied to the combustion chamber by throttling a fresh air supply passage.

3. The method of claim 1 including a step of compressing a mixture of fresh air and low pressure exhaust in the turbocharger prior to mixing with the high pressure exhaust.

4. The method of claim 3 including trapping particles in the low pressure exhaust prior to mixing with fresh air;

cooling the low pressure exhaust prior to mixing with fresh air;

trapping particles in the high pressure exhaust prior to mixing with the mixture of low pressure exhaust and fresh air;

cooling the high pressure exhaust prior to mixing with the mixture of low pressure exhaust and fresh air; and

cooling the mixture of low pressure exhaust, high pressure exhaust and fresh air.

5. The method of claim 1 wherein the injecting step is performed in a shower head spray pattern that includes spray plumes at a plurality of angles with respect to an injector centerline.

6. The method of claim 1 wherein the injecting step is performed during a compression stroke of the combustion chamber.

7. The method of claim 1 including a step of adjusting a relative ratio of low to high pressure exhaust recirculated to the combustion chamber.

8. The method of claim 1 wherein the turbocharger is a first turbocharger;

and

channeling exhaust from the first turbocharger to a second turbocharger;

the low pressure exhaust is from an outlet from the second turbocharger.

2. (canceled)

9-12. -12. (canceled)

13. An engine comprising:

an engine housing having at least one combustion chamber disposed therein;

a fuel injector positioned for direct injection of liquid fuel into each combustion chamber;

an exhaust passage extending between the engine housing and a turbocharger;

a high pressure exhaust gas recirculation passage connected to the exhaust passage;

at least one outlet from the turbocharger with a first branch connected to a low pressure exhaust gas recirculation passage, and a second branch connected to a tail pipe;

a fresh air supply passage connected to the low pressure exhaust gas recirculation passage;

a venturi connection fluidly connecting the low pressure exhaust gas recirculation passage with the high pressure exhaust gas recirculation passage;

a throttle control valve positioned in the fresh air supply passage; and

an engine controller configured to inject fuel prior to an auto-ignition of the fuel and then to compress a mixture of fuel with air and exhaust gas in the combustion chamber to the auto-ignition condition of the fuel, and configured increase a proportion of exhaust gas supplied to the combustion chamber by actuating the throttle control valve.

14. The engine of claim 13 wherein the turbocharger is a first turbocharger;

and

a second turbocharger arranged in series with the first turbocharger.

15. The engine of claim 14 wherein each of the low pressure and high pressure exhaust gas recirculation passages includes a respective particle trap;

and

a cooler positioned downstream from the venturi connection.

16. The engine of claim 13 wherein the fuel injector has a shower head nozzle with outlets oriented at a plurality of different angles with respect to an injector centerline.

18. The engine of claim 13 including a first control valve positioned in the low pressure exhaust gas recirculation passage;

and

a second control valve positioned in the high pressure exhaust gas recirculation passage.

19. The engine of claim 18 wherein the exhaust gas recirculation system includes a cooler positioned downstream from the venturi connection for cooling a mixture of exhaust from the low pressure exhaust gas recirculation passage and the high pressure exhaust gas recirculation passage.

17. (canceled)