Dedicated exhaust gas recirculation control systems and methods

• US 9,957,911 B2
• Filed: 02/18/2016
• Issued: 05/01/2018
• Est. Priority Date: 02/18/2016
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company), US Department of Energy (Government of the United States of America)
• Inventors: Sczomak, David P., Narayanaswamy, Kushal, Keating, Edward J.
• Primary Examiner(s): Dallo, Joseph
• Assistant Examiner(s): Wang, Yi-Kai
• Application Number:
  US15/046,580
• Publication Number:
  US 20170241364A1
• Time in Patent Office: 803 Days
• Field of Search: 701103
• CPC Class Codes: F01N 13/009 having two or more separate purifying devices arranged in series
• CPC Class Codes: F01N 13/0093 the purifying devices are of the same type
• CPC Class Codes: F01N 2560/026 for measuring or detecting NOx
• CPC Class Codes: F01N 2900/0416 using the state of a sensor, e.g. of an exhaust gas sensor
• CPC Class Codes: F01N 3/101 Three-way catalysts
• CPC Class Codes: F01N 3/2066 Selective catalytic reduction [SCR]
• CPC Class Codes: F01N 3/2073 with means for generating a reducing substance from the exhaust gases
• CPC Class Codes: F01N 9/00 Electrical control of exhaust gas treating apparatus monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00
• CPC Class Codes: F02D 35/0015 using exhaust gas sensors F02D41/14 takes precedence
• CPC Class Codes: F02D 41/005 according to engine operating conditions
• CPC Class Codes: F02D 41/0052 Feedback control of engine parameters, e.g. for control of air/fuel ratio or intake air amount
• CPC Class Codes: F02D 41/0065 Specific aspects of external EGR control constructional details of EGR system F02M26/00
• CPC Class Codes: F02D 41/008 Controlling each cylinder individually
• CPC Class Codes: F02D 41/1463 of the exhaust gases downstream of exhaust gas treatment apparatus
• CPC Class Codes: F02D 41/3011 according to or using specific or several modes of combustion
• 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 26/15 in relation to engine exhaust purifying apparatus
• 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: F02M 26/71 : Multi-way valves
• CPC Class Codes: Y02A 50/20 : Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 : Engine management systems

Abstract

An engine control system of a vehicle includes a fuel control module that controls fuel injection of a first cylinder of an engine based on a first target air/fuel ratio that is fuel lean relative to a stoichiometric air/fuel ratio and that controls fuel injection of a second cylinder of the engine based on a second target air/fuel ratio that is fuel rich relative to stoichiometry. The first cylinder outputs exhaust to a first three way catalyst (TWC), and the second cylinder outputs exhaust to an exhaust gas recirculation (EGR) valve. An EGR control module controls opening of the EGR valve to: (i) a second TWC that reacts with nitrogen oxides (NOx) in the exhaust and outputs ammonia to a selective catalytic reduction (SCR) catalyst; and (ii) a conduit that recirculates exhaust back to an intake system of the engine.

Claims

1. An engine control system of a vehicle, comprising:

a fuel control module that controls fuel injection of a first cylinder of an engine based on a first target air/fuel ratio that is fuel lean relative to a stoichiometric air/fuel ratio and that controls fuel injection of a second cylinder of the engine based on a second target air/fuel ratio that is fuel rich relative to stoichiometry,

wherein the first cylinder outputs exhaust to a first three way catalyst (TWC), and

wherein the second cylinder outputs exhaust to an exhaust gas recirculation (EGR) valve; and

an EGR control module that controls opening of the EGR valve to;

(i) a second TWC that reacts with nitrogen oxides (NOx) in the exhaust and outputs ammonia to a selective catalytic reduction (SCR) catalyst;

(ii) a conduit that recirculates exhaust back to an intake system of the engine at a location downstream of a compressor of a turbocharger; and

(iii) the first TWC.

2. An engine control system of a vehicle, comprising:

a fuel control module that controls fuel injection of a first cylinder of an engine based on a first target air/fuel ratio that is fuel lean relative to a stoichiometric air/fuel ratio and that controls fuel injection of a second cylinder of the engine based on a second target air/fuel ratio that is fuel rich relative to stoichiometry,

wherein the first cylinder outputs exhaust to a first three way catalyst (TWC), and

wherein the second cylinder outputs exhaust to an exhaust gas recirculation (EGR) valve; and

an EGR control module that controls opening of the EGR valve to;

(i) a second TWC that reacts with nitrogen oxides (NOx) in the exhaust and outputs ammonia to a selective catalytic reduction (SCR) catalyst;

(ii) a conduit that recirculates exhaust back to an intake system of the engine; and

(iii) the first TWC.

3. The engine control system of claim 2 wherein the fuel control module increases the second target air/fuel ratio to lean fueling of the second cylinder when NOx measured using a Nox sensor downstream of the SCR catalyst is less than a target Nox at the Nox sensor.

4. The engine control system of claim 2

wherein, when NOx measured using a Nox sensor downstream of the SCR catalyst is greater than a target Nox at the Nox sensor, the EGR control module:

increases the opening of the EGR valve to the second TWC to increase exhaust flow to the second TWC; and

decreases the opening of the EGR valve to the conduit that directs exhaust back to the intake system to decrease exhaust recirculation back to the intake system.

5. The engine control system of claim 2

wherein, when NOx measured using a Nox sensor downstream of the SCR catalyst is less than a target Nox at the Nox sensor, the EGR control module:

decreases the opening of the EGR valve to the second TWC to decrease exhaust flow to the second TWC; and

increases the opening of the EGR valve to the conduit that directs exhaust back to the intake system to increase exhaust recirculation back to the intake system.

6. The engine control system of claim 2 wherein the fuel control module decreases the second target air/fuel ratio to richen fueling of the second cylinder when an air/fuel ratio measured using a sensor in the conduit is greater than a target air/fuel ratio at the sensor.

7. The engine control system of claim 2 wherein the fuel control module increases the second target air/fuel ratio to lean fueling of the second cylinder when an air/fuel ratio measured using a sensor in the conduit is less than a target air/fuel ratio at the sensor.

8. The engine control system of claim 2 further comprising a throttle control module that, when an air/fuel ratio measured using a sensor in the conduit is greater than a target air/fuel ratio at the sensor, decreases an opening of a throttle valve that regulates flow from an intake manifold into the second cylinder,

wherein the throttle valve does not regulate flow from the intake manifold into the first cylinder.

9. The engine control system of claim 2 further comprising a throttle control module that, when an air/fuel ratio measured using a sensor in the conduit is less than a target air/fuel ratio at the sensor, increases an opening of a throttle valve that regulates flow from an intake manifold into the second cylinder,

wherein the throttle valve does not regulate flow from the intake manifold into the first cylinder.

10. The engine control system of claim 2 wherein:

the first TWC includes one or more materials that provide an oxygen storage capacity of at least a predetermined capacity that is greater than zero; and

the second TWC has an oxygen storage capacity of approximately zero.

20. The engine control system of claim 2 wherein the fuel control module decreases the second target air/fuel ratio to richen fueling of the second cylinder when NOx measured using a Nox sensor downstream of the SCR catalyst is greater than a target Nox at the Nox sensor.

11. An engine control method for a vehicle, comprising:

controlling fuel injection of a first cylinder of an engine based on a first target air/fuel ratio that is fuel lean relative to a stoichiometric air/fuel ratio,

wherein the first cylinder outputs exhaust to a first three way catalyst (TWC);

controlling fuel injection of a second cylinder of the engine based on a second target air/fuel ratio that is fuel rich relative to stoichiometry,

wherein the second cylinder outputs exhaust to an exhaust gas recirculation (EGR) valve; and

controlling opening of the EGR valve to;

(i) a second TWC that reacts with nitrogen oxides (NOx) in the exhaust and outputs ammonia to a selective catalytic reduction (SCR) catalyst; and

(ii) a conduit that recirculates exhaust back to an intake system of the engine; and

(iii) the first TWC.

12. The engine control method of claim 11 further comprising decreasing the second target air/fuel ratio to richen fueling of the second cylinder when NOx measured using a NOx sensor downstream of the SCR catalyst is greater than a target NOx at the NOx sensor.

13. The engine control method of claim 11 further comprising increasing the second target air/fuel ratio to lean fueling of the second cylinder when NOx measured using a NOx sensor downstream of the SCR catalyst is less than a target NOx at the NOx sensor.

14. The engine control method of claim 11 further comprising, when NOx measured using a NOx sensor downstream of the SCR catalyst is greater than a target NOx at the NOx sensor:

increasing the opening of the EGR valve to the second TWC to increase exhaust flow to the second TWC; and

decreasing the opening of the EGR valve to the conduit that directs exhaust back to the intake system to decrease exhaust recirculation back to the intake system.

15. The engine control method of claim 11 further comprising, when NOx measured using a NOx sensor downstream of the SCR catalyst is less than a target NOx at the NOx sensor:

decreasing the opening of the EGR valve to the second TWC to decrease exhaust flow to the second TWC; and

increasing the opening of the EGR valve to the conduit that directs exhaust back to the intake system to increase exhaust recirculation back to the intake system.

16. The engine control method of claim 11 further comprising:

decreasing the second target air/fuel ratio to richen fueling of the second cylinder when an air/fuel ratio measured using a sensor in the conduit is greater than a target air/fuel ratio at the sensor; and

increasing the second target air/fuel ratio to lean fueling of the second cylinder when the air/fuel ratio measured using the sensor in the conduit is less than the target air/fuel ratio at the sensor.

17. The engine control method of claim 11 further comprising, when an air/fuel ratio measured using a sensor in the conduit is greater than a target air/fuel ratio at the sensor, decreasing an opening of a throttle valve that regulates flow from an intake manifold into the second cylinder,

wherein the throttle valve does not regulate flow from the intake manifold into the first cylinder.

18. The engine control method of claim 11 further comprising, when an air/fuel ratio measured using a sensor in the conduit is less than a target air/fuel ratio at the sensor, increasing an opening of a throttle valve that regulates flow from an intake manifold into the second cylinder,

wherein the throttle valve does not regulate flow from the intake manifold into the first cylinder.

19. The engine control method of claim 11 wherein:

the first TWC includes one or more materials that provide an oxygen storage capacity of at least a predetermined capacity that is greater than zero; and

the second TWC has an oxygen storage capacity of approximately zero.