INTERNAL COMBUSTION ENGINE WITH AN EXHAUST GAS RECIRCULATION SYSTEM

• US 20020073979A1
• Filed: 12/18/2000
• Published: 06/20/2002
• Est. Priority Date: 12/18/2000
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Mccoy, Steven R., Liang, Cho Y., Lepp, Noel R.
• Granted Patent: US 6,422,220 B1
• Time in Patent Office: Days
• US Class Current: 123/568.18
• CPC Class Codes: F02D 21/08 the other gas being the exhaust gas of engine
• 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 26/07 Mixed pressure loops, i.e. wherein recirculated exhaust gas is either taken out upstream of the turbine and reintroduced upstream of the compressor, or is taken out downstream of the turbine and reintroduced downstream of the compressor
• CPC Class Codes: F02M 26/23 Layout, e.g. schematics
• 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 26/47 the characteristics being temperatures, pressures or flow rates

Abstract

An internal combustion engine system, particularly suitable for a motor vehicle, is provided with an intake manifold, an exhaust manifold and an exhaust gas recirculation rate control system fluidly connected to the exhaust manifold and to the intake manifold. The exhaust gas recirculation rate control system includes at least two critical-flow nozzles, each critical-flow nozzle having an intake end and output end, the intake ends being fluidly coupled to the exhaust manifold; at least one valve, each valve being fluidly coupled with at least one output end; and a control module operatively connected to each valve for controlling exhaust gas flow therethrough. Some advantages of such a system is that the exhaust gas recirculation is accurately provided with an “open-loop” control system, thereby avoiding the use of a feedback system; the flow can be accurately determined under a choked-flow operating conditions; and the system can readily handle different exhaust gas flow rates.

Claims

1. An exhaust gas recirculation rate control system adapted to be fluidly connected to an exhaust manifold and an intake manifold of an internal combustion engine, said exhaust gas recirculation rate control system comprising:

a plurality of critical-flow nozzles, each said critical-flow nozzle having an intake end and an output end, said intake ends being fluidly coupled in parallel and adapted to receive the flow of exhaust gas;

at least one valve, each said valve being fluidly coupled with at least one said output end; and

a control module operatively connected to each said valve for controlling exhaust gas flow therethrough.

2. The exhaust gas recirculation rate control system of claim 1, each said critical-flow nozzle being a venturi nozzle, each said critical-flow nozzle having an upstream region with said intake end, a downstream region with said output end, and a throat fluidly interconnecting said upstream region with said downstream region.

3. The exhaust gas recirculation rate control system of claim 2, each said critical-flow nozzle having a throat area at a connective opening whereat each said throat opens into and connects with said downstream region, said critical-flow nozzles having different respective throat areas.

4. The exhaust gas recirculation rate control system of claim 2, one of said critical-flow nozzles having a first pressure sensor positioned within said upstream region, a second pressure sensor positioned within said downstream region, and a first temperature sensor positioned within said upstream region.

5. The exhaust gas recirculation rate control system of claim 4, each said critical-flow nozzle having a throat area at a connective opening whereat each said throat opens into and connects with said downstream region, said critical-flow nozzles having different respective throat areas, said one of said critical-flow nozzles having a smallest throat area of all of said critical-flow nozzles.

6. The exhaust gas recirculation rate control system of claim 1, said at least one valve being a plurality of valves, each said valve being fluidly coupled with a corresponding said output end.

7. An internal combustion engine system, comprising:

an internal combustion engine having an intake manifold and an exhaust manifold;

an exhaust gas recirculation rate control system fluidly connected to said exhaust manifold and to said intake manifold, said exhaust gas recirculation rate control system comprising;

a plurality of critical-flow nozzles, each said critical-flow nozzle having an intake end and an output end, said intake ends being fluidly coupled in parallel to said exhaust manifold;

at least one valve, each said valve being fluidly coupled with at least one said output end; and

a control module operatively connected to each said valve for controlling exhaust gas flow therethrough.

8. The internal combustion engine system of claim 7, each said critical-flow nozzle being a venturi nozzle, each said critical-flow nozzle having an upstream region with said intake end, a downstream region with said output end, and a throat fluidly interconnecting said upstream region with said downstream region.

9. The internal combustion engine system of claim 8, each said critical-flow nozzle having a throat area at a connective opening whereat each said throat opens into and connects with said downstream region, said critical-flow nozzles having different respective throat areas.

10. The internal combustion engine system of claim 8, one of said critical-flow nozzles having a first pressure sensor positioned within said upstream region, a second pressure sensor positioned within said downstream region, and a first temperature sensor positioned within said upstream region.

11. The internal combustion engine system of claim 10, each said critical-flow nozzle having a throat area at a connective opening whereat each said throat opens into and connects with said downstream region, said critical-flow nozzles having different respective throat areas, said one of said critical-flow nozzles having a smallest throat area of all of said critical-flow nozzles.

12. The internal combustion engine system of claim 7, said at least one valve being a plurality of valves, each said valve being fluidly coupled with a corresponding said output end.

13. The internal combustion engine system of claim 7, including a particulate t rap for filtering particulates from the exhaust gas, said particulate trap including an entrance end fluidly connected to said exhaust manifold and an exit end fluidly coupled to said plurality of critical-flow nozzles.

15. The method of claim 14, including the steps of:

generating an engine speed signal and a load signal in said internal combustion engine;

receiving and processing the engine speed signal and the load signal in said control module; and

determining a desired exhaust gas return rate dependent upon the engine speed signal and the load signal.

16. The method of claim 14, each said critical-flow nozzle being a venturi nozzle, each said venturi nozzle having an upstream region with an intake end, a throat, and a downstream region with an output end, said throat having a throat area A_t at a connective opening whereat said throat opens into and connects with said downstream region;

and

including the steps of;

providing each said venturi nozzle with a different throat area; and

accommodating a different exhaust gas flow rate with each said venturi nozzle.

17. The method of claim 14, each said critical-flow nozzle being a venturi nozzle, each said critical-flow nozzle having an upstream region with an intake end, a throat, and a downstream region with an output end, said throat having a throat area A_t at a connective opening whereat said throat opens into and connects with said downstream region, one of said critical-flow nozzles having a stagnation pressure P_uo and a stagnation temperature T_uo near an upstream entrance of said upstream region thereof;

and

including the step of calculating an actual exhaust gas mass flow rate through said one of said critical-flow nozzles based upon values for the throat area A_t, the stagnation pressure P_uo, and the stagnation temperature T_uo of said one of said critical-flow nozzles.

18. The method of claim 17, including the steps of:

determining a static pressure P_t at said throat of said one of said critical-flow nozzles;

calculating a pressure ratio PR by dividing the static pressure P_t at said throat of said one of said critical-flow nozzles by the stagnation pressure P_uo to determine a pressure ratio PR, whereby a pressure ratio PR less than or equal to a critical pressure ratio PR_c indicates a choked-flow condition at said throat of said one of said critical-flow nozzles.

19. The method of claim 17, including the steps of:

providing each said critical-flow nozzle with a different throat area;

accommodating a different exhaust gas flow rate with each said critical-flow nozzle; and

choosing a critical-flow nozzle with the smallest throat area of all of said critical-flow nozzles as said one of said critical-flow nozzles.

20. The method of claim 19, including the steps of:

providing each said critical-flow nozzle with a valve;

calculating a mass flow rate for each said critical-flow nozzle;

processing an engine speed signal and a load signal received from said internal combustion engine to establish a desired exhaust gas return rate;

determining a combination of said valves that needs to be opened to provide the desired exhaust gas return rate; and

signaling for said combination of said valves to be opened.

14. A method of controlling a rate of recirculation of a flow of an exhaust gas in an exhaust gas recirculation system, comprising the steps of:

providing a plurality of critical-flow nozzles, each said critical-flow nozzle having an intake end and an output end;

fluidly coupling said intake ends in parallel with an exhaust manifold of an internal combustion engine;

fluidly coupling at least one valve with at least one corresponding said output end and with an intake manifold of said internal combustion engine;

operatively connecting a control module to each said valve;

directing the flow of the exhaust gas into said intake ends;

controllably releasing an amount of the exhaust gas through each said valve; and

recirculating the controlled amount of exhaust gas to said intake manifold.