Exhaust gas recirculation system for an internal combustion engine

• US 5,802,846 A
• Filed: 03/31/1997
• Issued: 09/08/1998
• 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:
  US08/828,685
• Time in Patent Office: 526 Days
• Field of Search: 123/568, 123/569, 123/570, 123/571, 60/278, 60/279, 60/605.2, 60/606, 60/320
• US Class Current: 60/278
• 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

A constant rate exhaust gas recirculation (EGR) system for a pressure-charged internal combustion engine is provided. The disclosed exhaust gas recirculation system includes one or more exhaust gas diversion ports, one or more EGR diversion valves each of which is operatively associated with a selected combustion chamber for diverting a flow of exhaust gas from the selected combustion chambers via an exhaust gas recirculation conduit to the intake air circuit of the pressure-charged internal combustion engine. The disclosed embodiment of the constant rate EGR system also includes a bypass conduit for diverting a flow of intake air to the exhaust manifold and an EGR cooler disposed in operative association with the recirculation conduit and the bypass conduit and adapted for cooling the volume of recirculated exhaust gas in the recirculation conduit while concurrently heating the intake air in the bypass conduit.

Claims

1. An exhaust gas recirculation system in a pressure-charged internal combustion engine, said pressure-charged internal combustion engine including an intake air circuit having an intake air pressurizing device, an intake manifold, an exhaust manifold, a plurality of combustion chambers, said exhaust gas recirculation system comprising:

an exhaust gas recirculation conduit for diverting a flow of exhaust gas from at least one selected combustion chamber to said intake air circuit at a location downstream of said intake air pressurizing device;

at least one exhaust gas recirculation diversion valve interposed between said selected combustion chamber and said exhaust gas recirculation conduit;

a controller operatively associated with said exhaust gas recirculation diversion valve and adapted for selectively diverting said flow of exhaust gas from said selected combustion chamber to said exhaust gas recirculation conduit; and

an intake air bypass conduit in fluid communication with said intake air circuit for selectively transporting a flow of intake air from said intake circuit to said exhaust manifold.

2. The exhaust gas recirculation system of claim 1 further including a particulate trap disposed in operative association with said exhaust gas recirculation conduit for cleansing said flow of recirculation exhaust gas in said exhaust gas recirculation conduit.

3. The exhaust gas recirculation system of claim 1, wherein said intake air bypass conduit being on fluid communication with said exhaust manifold proximate said selected combustion chamber.

4. The exhaust gas recirculation system of claim 3 further including an exhaust gas recirculation recuperator disposed in operative associaton with said intake air bypass conduit and adapted for heating said flow of intake air in said intake air bypass conduit wherein said heated flow of intake air replaces said recirculated exhaust gas in said exhaust manifold.

5. The exhaust gas recirculation system of claim 1 wherein said exhaust gas recirculation diversion valve is movable between a first position wherein said flow of exhaust gas from said selected combustion chamber is diverted to said exhaust gas recirculation conduit and a second position wherein said flow of exhaust gas from said selected combustion chamber is in flow communication with exhaust gas from other said plurality of combustion chambers in said exhaust manifold.

6. The exhaust gas recirculation system of claim 5 wherein said exhaust gas recirculation diversion valve is movable between said first position, said second position, and an intermediate position wherein a first portion of said flow of exhaust gas from said selected combustion chamber is diverted to said exhaust gas recirculation conduit and a remaining portion of said flow of exhaust gas from said selected combustion chamber is in flow communication with exhaust gas from other said plurality of combustion chambers in said exhaust manifold.

7. The exhaust gas recirculation system of claim 6 wherein said exhaust gas diversion valve is disposed in said exhaust manifold proximate to said combustion chamber.

8. The exhaust gas recirculation system of claim 1 further including an exhaust gas recirculation cooler disposed in operative association with said exhaust gas recirculation conduit and adapted for cooling said flow of recirculated exhaust gas in said exhaust gas recirculation conduit.

9. The exhaust gas recirculation system of claim 8 wherein said air intake pressurizing device includes a compressor and a gas driven turbine, said gas driven turbine adapted to receive exhaust gas from said exhaust manifold to drive said compressor thereby pressurizing said intake air in said intake circuit.

10. The exhaust gas recirculation system of claim 1 wherein said exhaust gas recirculation cooler is further adapted for heating said intake air in said intake air bypass conduit.

11. The exhaust gas recirculation system of claim 1 wherein said exhaust gas recirculation cooler is a heat exchanger for transferring heat from said recirculated exhaust gas to said flow of intake air in said intake air bypass conduit thereby cooling said recirculated exhaust gas and concurrently heating said flow of intake air in said intake air bypass conduit.

12. A method of recirculating exhaust gas in a pressure-charged internal combustion engine, said pressure-charged internal combustion engine including an intake air circuit with an intake air pressurizing device, said pressure-charged internal combustion engine further including an intake manifold, an exhaust manifold, and a plurality of combustion chambers, the method of recirculating exhaust gas comprising the steps of:

(a) diverting a flow of exhaust gas from a selected number of combustion chambers to a recirculation conduit; and

(b) transporting said diverted flow of exhaust gas in said recirculation conduit to said intake air circuit at a location downstream of said intake air pressurizing device; and

(c) replacing said divert flow of exhaust gas with a flow of replacement air.

13. The method of recirculating exhaust gas as set forth in claim 12 wherein said step of replacing said diverted flow of exhaust gas is by diverting a flow of intake air to said exhaust manifold.

14. The method of recirculating exhaust gas as set forth in claim 13 further comprising the step of cooling said diverted flow of exhaust gas using said diverted flow of intake air.

15. The method of recirculating exhaust gas as set forth in claim 14 further comprising the step of cleansing said diverted flow of exhaust gas prior to said cooling step.

16. The method of recirculating exhaust gas as set forth in claim 14 further comprising the step of heating said diverted flow of intake air using said diverted flow of exhaust gas wherein the step of heating said diverted flow of intake air being concurrent with the step of cooling said diverted flow of exhaust gas.

17. The method of recirculating exhaust gas as set forth in claim 16 wherein said air intake pressurizing device includes an exhaust gas driven turbine, said method further includes the step of driving said turbine with any exhaust gas remaining in said exhaust manifold together with said diverted flow of intake air.