Dynamic EGR concentration estimation method for a motor vehicle engine

• US 20020066442A1
• Filed: 12/01/2000
• Published: 06/06/2002
• Est. Priority Date: 10/12/2000
• Status: Active Grant

• Current Assignee: Delphi Technologies Ip Limited (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Muller, Martin, Schreurs, Bart Hubert, Olin, Peter M.
• Granted Patent: US 6,481,423 B2
• Time in Patent Office: Days
• US Class Current: 123/568.11
• CPC Class Codes: F02D 41/0072 Estimating, calculating or determining the EGR rate, amount or flow sensors in EGR systems F02M26/45
• CPC Class Codes: G01N 33/0011 Sample conditioning in general G01N1/28
• CPC Class Codes: G01N 33/0018 by diluting a gas
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An improved method of dynamically estimating the concentration of recirculated exhaust gases in air/fuel mixture of an internal combustion engine equipped with an exhaust gas recirculation (EGR) system. The EGR concentration at engine intake ports is separately estimated with static and dynamic models, and the EGR concentration for control purposes is determined by adjusting the result of the dynamic model based on a deviation of the dynamic model from the static model. This method provides the total EGR concentration, but can alternatively provide the inert EGR concentration through the inclusion of an exhaust inert ratio model.

Claims

1. A method of estimating a concentration of recirculated exhaust gas at an intake port of an internal combustion engine comprising the steps of:

estimating a first concentration of recirculated exhaust gas in an intake manifold plenum of said engine using a dynamic model of air and exhaust gas mixing in said intake manifold plenum based on air and exhaust gas flow estimates, and delaying said first concentration to form an estimate of said concentration of recirculated exhaust gas at said intake port;

estimating a second concentration of recirculated exhaust gas in said intake manifold plenum using a steady-state model of said concentration based on an estimate of exhaust gas flow into said intake manifold plenum and an estimate of total gas flow through said intake manifold plenum; and

compensating said estimate of the concentration of recirculated exhaust gas at said intake port for error in said air and exhaust gas flow estimates by adjusting said first concentration based on a deviation of said first concentration from said second concentration.

2. The method of claim 1, wherein compensating said first concentration includes the steps of:

adjusting said first concentration in proportion to said deviation; and

adjusting said first concentration in proportion to an integral of said deviation.

3. The method of claim 1, wherein said dynamic model is based on said air and exhaust gas flow estimates, and a temperature, pressure and volume of gases in said intake manifold plenum.

4. The method of claim 1, including the steps of:

estimating an inert fraction corresponding to a concentration of inert gas in said recirculated exhaust gas; and

estimating said first and second concentrations based on said inert fraction so that the delayed first concentration represents a concentration of inert recirculated exhaust gas at said intake port.

5. The method of claim 1, including the steps of:

estimating an inert fraction corresponding to a concentration of inert gas in said recirculated exhaust gas; and

estimating a concentration of inert recirculated exhaust gas at said intake port according to a product of said delayed first concentration and said inert fraction.

6. The method of claims 4 or 5, wherein said inert fraction is estimated based on an estimated air/fuel ratio of the engine relative a stoichiometric air/fuel ratio.

7. A method of estimating a concentration of recirculated exhaust gas entering a combustion chamber of an internal combustion engine comprising the steps of:

estimating a dynamic concentration of recirculated exhaust gas in an intake manifold plenum of the engine using a dynamic model of air and exhaust gas mixing based on air and exhaust gas flow estimates, a volume of said intake manifold plenum, and a measured pressure and temperature of gases in said intake manifold plenum;

estimating a steady-state concentration of recirculated exhaust gas in said intake manifold plenum using a steady-state model based on an estimate of exhaust gas flow into said intake manifold plenum and an estimate of total gas flow entering said combustion chamber;

adjusting said dynamic concentration based on a deviation of said dynamic concentration from said steady-state concentration, thereby to compensate said dynamic concentration for error in said air and exhaust gas flow estimates;

integrating the adjusted dynamic concentration to form an estimate of the recirculated exhaust gas concentration in said intake manifold plenum; and

delaying the estimate of the recirculated exhaust gas concentration in said intake manifold plenum to form an estimate of the recirculated exhaust gas concentration entering said combustion chamber.

8. The method of claim 7, wherein adjusting said dynamic concentration includes the steps of:

adjusting said dynamic concentration in proportion to said deviation; and

adjusting said dynamic concentration in proportion to an integral of said deviation.

9. The method of claim 7, wherein gases in said intake manifold plenum pass through an intake runner to said combustion chamber, and the estimate of the recirculated exhaust gas concentration in said intake manifold plenum is delayed in proportion to a ratio of a volume of said intake runner to a volume of said combustion chamber.

10. The method of claim 7, including the steps of:

estimating an inert fraction corresponding to a concentration of inert gas in said recirculated exhaust gas; and

estimating said dynamic and steady-state concentrations based on said inert fraction so that said delayed estimate represents a concentration of inert recirculated exhaust gas entering said combustion chamber.

11. The method of claim 7, including the steps of:

estimating an inert fraction corresponding to a concentration of inert gas in said recirculated exhaust gas; and

estimating a concentration of inert recirculated exhaust gas entering said combustion chamber according to a product of said estimate of the recirculated exhaust gas concentration entering said combustion chamber and said inert fraction.

12. The method of claims 10 or 11, wherein said inert fraction is estimated based on an estimated air/fuel ratio of the engine relative a stoichiometric air/fuel ratio.