System and method of controlling exhaust gas recirculation

• US 6,009,709 A
• Filed: 04/13/1998
• Issued: 01/04/2000
• Est. Priority Date: 03/31/1997
• Status: Expired due to Fees

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Bailey, Brett M.
• Primary Examiner(s): WOLFE JR, WILLIS RAY
• Application Number:
  US09/059,485
• Time in Patent Office: 631 Days
• Field of Search: 123/568.11, 123/568.12, 123/568.17, 123/568.18, 123/568.24, 123/568.26, 123/568.27, 123/568.28, 60/599, 60/605.2
• US Class Current: 60/605.2
• CPC Class Codes: F01N 3/02 for cooling, or for removing solid constituents of, exhaust by means of electric or electrostatic separators F01N3/01 ; mixing air with exhaust in tailpipes F01N13/082, F01N13/20
• CPC Class Codes: F02B 29/0425 Air cooled heat exchangers
• CPC Class Codes: F02B 3/06 with compression ignition compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02
• CPC Class Codes: F02B 33/44 Passages conducting the charge from the pump to the engine inlet, e.g. reservoirs
• CPC Class Codes: F02B 37/16 by bypassing charging air
• 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 26/10 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 26/25 with coolers having bypasses
• CPC Class Codes: F02M 26/27 with air-cooled heat exchangers
• 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 26/43 in which exhaust from only one cylinder or only a group of cylinders is directed to the intake of the engine
• CPC Class Codes: F02M 26/62 in response to fuel pressure
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

An exhaust gas recirculation (EGR) system for a pressure-charged internal engine for use in a high load condition is presented. The disclosed EGR system includes one or more exhaust combustion chambers attached to a recirculation manifold. A pressure sensor is located in an inlet air manifold. Where the pressure in the inlet manifold is above a predetermined level, a flow control device directs recirculation flow through a supply conduit into the inlet manifold. The disclosed embodiment includes an EGR cooling system where cool air in a bleed conduit connecting an inlet conduit to the exhaust manifold exchanges heat with exhaust gas in the supply. A bleed valve in the bleed conduit moves in response to temperature in the supply duct along with the position of the flow control device to prevent condensation in the combustion chambers. The invention also includes methods for controlling EGR system and EGR cooling system.

Claims

1. A system for controlling exhaust gas recirculation in an internal combustion engine, said engine having an inlet manifold, an exhaust manifold, a plurality of combustion chambers, and an air intake pressurizing device being connectable to said inlet manifold, the system comprising:

a recirculation manifold being connectable to at least one of said plurality of combustion chambers;

a pressure sensing device being connectable to said inlet manifold, said pressure sensing device measuring an inlet air pressure; and

a flow control device having a first position and a second position, said flow control device being movable between said first position and said second position, said flow control device being connectable to said recirculation manifold, said inlet manifold and said exhaust manifold, said first position having a flow passage between said recirculation manifold and said inlet manifold, said second position having a flow blockage between said recirculation manifold and said inlet manifold, said flow control device being responsive to said pressure sensing device and being adapted to move from said second position to said first position when the inlet air pressure is above a predetermined level near a maximum boost pressure of said engine, said maximum boost pressure being a function of said engine and being indicative of a high load condition.

2. The system for controlling exhaust gas recirculation as recited in claim 1 further comprising an inlet conduit being connectable between said inlet manifold and said pressure charging device, said pressure sensor being located in said inlet conduit.

3. The system for controlling exhaust as recited in claim 1 further comprising an engine speed sensing device being adapted for measuring an engine speed, said flow control device being responsive with said engine speed sensing device and moving from said second position to said first position where said engine speed is above a predetermined speed.

4. The system for controlling exhaust gas recirculation as recited in claim 3 wherein said predetermined speed is a function of a peak torque of said engine.

5. The system for controlling exhaust gas recirculation as recited in claim 1 further comprising a fuel demand sensing device being adapted to measure a change in fuel demand over time, said exhaust gas flow control device being responsive with said fuel demand sensing device, said flow control device moving from said second position to said first position where said change in fuel demand is below a predetermined fuel demand rate.

6. The system for controlling exhaust gas recirculation in an internal combustion engine as recited in claim 5 wherein said predetermined fuel demand rate indicates a low air fuel ratio acceleration.

7. The system for controlling exhaust gas recirculation as recited in claim 1 further comprising a fuel delivery sensing device being adapted for measuring a fuel supplied to said plurality of combustion chambers;

said exhaust gas flow control device being responsive with said fuel delivery sensing device, said flow control device moving from said second position to said first where said fuel supplied exceeds a predetermined fuel delivery requirement.

8. The system for controlling exhaust gas recirculation as recited in claim 7 wherein said fuel delivery sensing device measures a fuel injection duration to determine said fuel supplied to said plurality of combustion chambers.

9. The system for controlling exhaust gas recirculation as recited in claim 1, further comprising:

an inlet conduit being connectable to said inlet manifold and to said air inlet pressurizing device;

an aftercooler being connectable to said inlet conduit downstream of said air inlet pressurizing device, said aftercooler reducing the inlet air temperature;

a bleed conduit being connectable to said exhaust manifold and to said inlet conduit downstream of said aftercooler;

a supply conduit connecting said recirculation manifold and said inlet manifold;

an EGR heat exchanger thermally coupling said supply conduit to said bleed conduit;

a bleed control device being connectable to said bleed conduit, said bleed control device having a first bleed position and a second bleed position, said first bleed position having a flow passage between said inlet conduit; and

a temperature sensor being connectable to said supply conduit downstream of said EGR heat exchanger, said bleed control device being responsive to said temperature sensor so as to prevent condensation in said engine by moving between said first bleed position and said second bleed position to maintain said EGR heat exchanger at a predetermined temperature range.

10. The system for controlling exhaust gas recirculation as recited in claim 9 further comprising a temperature sensor being connectable to said supply conduit downstream of said EGR heat exchanger and to said electronic controller, said electronic controller manipulating bleed control device to prevent condensation in said engine by moving between said first bleed position and said second bleed position to maintain said EGR heat exchanger at a set temperature.

11. A method for controlling exhaust gas recirculation in an internal combustion engine, said engine having an inlet manifold, an exhaust manifold, and a pressurizing device, the method comprising the steps:

sensing an inlet air pressure in said inlet manifold;

allowing flow between said exhaust manifold and said inlet manifold where said inlet air pressure is above a predetermined pressure level, said predetermined pressure level being near a maximum boost pressure of said engine, said maximum boost pressure being a function of said engine and being indicative of a high load condition.

12. The method for controlling exhaust gas recirculation in an internal combustion engine as recited in claim 11 further comprising the steps:

sensing an engine speed; and

allowing flow between said exhaust manifold and said inlet manifold where said engine speed is above a predetermined speed.

13. The method for controlling exhaust gas recirculation in an internal combustion engine as recited in claim 11 further comprising the steps:

sensing a change in fuel demand over time;

allowing flow between said exhaust manifold and said inlet manifold where said change in fuel demand over time is above a predetermined fuel demand rate.

14. The method for controlling exhaust gas recirculation in an internal combustion engine as recited in claim 11 further comprising the steps:

sensing a fuel supplied to said combustion chamber;

allowing flow between said exhaust manifold and said inlet manifold where said fuel supplied to said combustion chambers is above a predetermined fuel delivery requirement.

15. A method for controlling exhaust gas recirculation cooling in an internal combustion engine, said engine having an inlet manifold, an exhaust manifold, a supply conduit, a pressurizing device, a temperature sensor, and a recirculation cooling system, said exhaust manifold being connectable to said inlet manifold by said supply conduit, said exhaust gas recirculation cooling system having a bleed conduit, bleed valve, and EGR heat exchanger, the method comprising the steps:

sensing an inlet air pressure in an inlet manifold, said inlet manifold being connectable to a combustion chamber;

allowing flow between an exhaust manifold and said inlet manifold through a supply conduit where said inlet air pressure is above a predetermined pressure level; and

cooling supply conduit where said flow control device is allowing fluid flow between said exhaust manifold and said inlet manifold, said cooling provided by using a cooled inlet air stream.

16. The method for controlling exhaust gas recirculation cooling in an internal combustion engine as recited in claim 15 further comprising the steps:

sensing a gas temperature in said supply conduit downstream of said recirculation cooling system;

controlling cooling to maintain a predetermined temperature in said supply conduit.