CONTROLLING EXHAUST GAS RECIRCULATION IN A TURBOCHARGED ENGINE SYSTEM

• US 20110010079A1
• Filed: 07/06/2010
• Published: 01/13/2011
• Est. Priority Date: 12/20/2005
• Status: Active Grant

• Current Assignee: BorgWarner Incorporated
• Original Assignee: BorgWarner Incorporated
• Inventors: Joergl, Volker, Mueller, Volker, Shutty, John, Roth, David B.
• Granted Patent: US 8,630,787 B2
• Time in Patent Office: Days
• US Class Current: 701/108
• CPC Class Codes: F02D 35/027 using knock sensors
• CPC Class Codes: F02D 41/0007 for control of turbo-charged or super-charged engines control of the pumps per se F02B37/12
• CPC Class Codes: F02D 41/005 according to engine operating conditions
• 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: 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 26/10 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 26/15 in relation to engine exhaust purifying apparatus
• CPC Class Codes: F02M 26/24 with two or more coolers
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Methods and products for controlling exhaust gas recirculation.

Claims

1. A method of controlling exhaust gas recirculation (EGR) comprising:

determining a target total EGR fraction for compliance with exhaust emissions criteria; and

determining a target high pressure/low pressure EGR ratio to reduce induction temperature within the constraints of the determined target total EGR fraction.

2. The method of claim 1, wherein the target high pressure/low pressure EGR ratio is determined to control engine knock.

3. The method of claim 2, wherein the high pressure/low pressure EGR ratio is adjusted to increase contribution of low pressure EGR to reduce engine knock.

4. A computer program product comprising a computer usable medium including instructions executable by a computer-controlled engine system, wherein the instructions cause the engine system to implement steps comprising:

determining a target total EGR fraction for compliance with exhaust emissions criteria; and

determining a target high pressure/low pressure EGR ratio to reduce induction temperature within the constraints of the determined target total EGR fraction.

5. The product of claim 4, wherein the target high pressure/low pressure EGR ratio is determined to control engine knock.

6. The product of claim 5, wherein the high pressure/low pressure EGR ratio is adjusted to increase contribution of low pressure EGR to reduce engine knock.

7. A product comprising:

a controller to control exhaust gas recirculation (EGR) and configured to;

receive input signals including a target total EGR fraction for compliance with exhaust emissions criteria and at least one other engine system input signal,

determine a target high pressure/low pressure EGR ratio to reduce induction temperature within the constraints of the target total EGR fraction, and

transmit output signals responsive to the target high pressure/low pressure EGR ratio.

8. The product of claim 7, wherein the target high pressure/low pressure EGR ratio is determined to control engine knock.

9. The product of claim 8, wherein the high pressure/low pressure EGR ratio is adjusted to increase contribution of low pressure EGR to reduce engine knock.

10. A method of controlling exhaust gas recirculation (EGR) in a turbocharged engine system including an engine, an induction subsystem in upstream communication with the engine, an exhaust subsystem in downstream communication with the engine, and a high pressure EGR path between the exhaust and induction subsystems upstream of a turbocharger turbine and downstream of a turbocharger compressor, the method comprising:

determining a target total EGR fraction for compliance with exhaust emissions criteria;

providing a target high pressure EGR/low pressure EGR ratio that is adjustable for optimization of other engine system criteria within the constraints of the determined target total EGR fraction, when the method is used in an engine system having high and low pressure EGR paths; and

setting the high pressure EGR/low pressure EGR ratio to 100% high pressure EGR/0% low pressure EGR, when the method is used in an engine system having only the high pressure EGR path.

11. The method of claim 10, wherein the steps further comprise coordinating control of turbocharger boost control and at least one EGR valve to avoid at least one of undershoot or overshoot EGR conditions to achieve increases in engine efficiency.

12. The method of claim 10, wherein the steps further comprise coordinating control of turbocharger boost control and at least one EGR valve to avoid at least one of undershoot or overshoot in boost pressure or exhaust pressure.

13. The method of claim 10 further comprising:

generating high pressure EGR and low pressure EGR setpoints in accordance with the determined target high pressure/low pressure EGR ratio; and

determining target high pressure and low pressure EGR valve and exhaust throttle valve opening percentages corresponding to the high pressure and low pressure EGR setpoints, including using open-loop models with engine load, engine speed, and turbocharger boost pressure as inputs.

14. A computer program product comprising a computer usable medium including instructions executable by a computer-controlled engine system including an engine, an induction subsystem in upstream communication with the engine, an exhaust subsystem in downstream communication with the engine, and at least one EGR path between the exhaust and induction subsystems upstream of a turbocharger turbine and downstream of a turbocharger compressor, wherein the instructions cause the engine system to implement steps comprising:

determining a target total EGR fraction for compliance with exhaust emissions criteria;

providing a target high pressure EGR/low pressure EGR ratio that is adjustable for optimization of other engine system criteria within the constraints of the determined target total EGR fraction, when the computer program product is used in an engine system having high and low pressure EGR paths; and

setting the high pressure EGR/low pressure EGR ratio to 100% high pressure EGR/0% low pressure EGR, when the computer program product is used in an engine system having only one EGR path.

15. The product of claim 14, wherein the steps further comprise coordinating control of turbocharger boost control and at least one EGR valve to avoid at least one of undershoot or overshoot EGR conditions to achieve increases in engine efficiency.

16. The product of claim 14, wherein the steps further comprise coordinating control of turbocharger boost control and at least one EGR valve to avoid at least one of undershoot or overshoot in boost pressure or exhaust pressure.

17. The product of claim 14 wherein the steps further comprise:

generating high pressure EGR and low pressure EGR setpoints in accordance with the determined target high pressure/low pressure EGR ratio; and

determining target high pressure and low pressure EGR valve and exhaust throttle valve opening percentages corresponding to the high pressure and low pressure EGR setpoints, including using open-loop models with engine load, engine speed, and turbocharger boost pressure as inputs.

18. A product comprising:

a controller to control exhaust gas recirculation (EGR) and configured to;

determine a target total EGR fraction for compliance with exhaust emissions criteria;

provide a target high pressure EGR/low pressure EGR ratio that is adjustable for optimization of other engine system criteria within the constraints of the determined target total EGR fraction, when the product is used in an engine system having high and low pressure EGR paths; and

setting the high pressure EGR/low pressure EGR ratio to 100% high pressure EGR/0% low pressure EGR, when the product is used in an engine system having only one EGR path.

19. The product of claim 18, wherein the steps further comprise coordinating control of turbocharger boost control and at least one EGR valve to avoid at least one of undershoot or overshoot EGR conditions to achieve increases in engine efficiency.

20. The product of claim 18, wherein the steps further comprise coordinating control of turbocharger boost control and at least one EGR valve to avoid at least one of undershoot or overshoot in boost pressure or exhaust pressure.

21. The product of claim 18, wherein the steps further comprise:

generating high pressure EGR and low pressure EGR setpoints in accordance with the determined target high pressure/low pressure EGR ratio; and

determining target high pressure and low pressure EGR valve and exhaust throttle valve opening percentages corresponding to the high pressure and low pressure EGR setpoints, including using open-loop models with engine load, engine speed, and turbocharger boost pressure as inputs.