Control of engine EGR with backpressure control valve

Patent metadata

Field	Value
Publication number	US-10077722-B2
Application number	US-201213556709-A
Country	US
Kind code	B2
Filing date	Jul 24, 2012
Priority date	Jul 24, 2012
Publication date	Sep 18, 2018
Grant date	Sep 18, 2018

Abstract

A method of controlling engine internal exhaust gas recirculation may include estimating a flow restriction through a diesel particulate filter in an exhaust system of an engine assembly and adjusting a backpressure control valve in the exhaust system downstream of the diesel particulate filter based on the flow restriction. A controlled amount of internal exhaust gas recirculation may be provided to the engine assembly based on adjusting the backpressure control valve.

First claim

What is claimed is:

1. A method comprising:
estimating a flow restriction through a diesel particulate filter in an exhaust system of an engine assembly;
adjusting a backpressure control valve in the exhaust system downstream of the diesel particulate filter based on the flow restriction; and
providing a controlled amount of internal exhaust gas recirculation to the engine assembly based on an adjustment of the backpressure control valve.

2. The method of claim 1 , wherein the providing the controlled amount of internal exhaust gas recirculation to the engine assembly includes an exhaust valve for a combustion chamber being open during an intake stroke of the combustion chamber with the amount of internal exhaust gas recirculation being controlled by a pressure differential between the exhaust system and an intake system of the engine assembly provided by an adjustment of the backpressure control valve.

3. The method of claim 2 , wherein the engine assembly includes a turbocharger in communication with the intake and exhaust systems and an EGR line extending from the exhaust system at a location between the turbocharger and the backpressure control valve to the intake system to provide additional communication between the intake and exhaust systems.

4. The method of claim 1 , wherein providing a controlled amount of internal exhaust gas recirculation to the engine assembly includes opening the backpressure control valve to reduce a flow restriction through the backpressure control valve when the flow restriction through the diesel particulate filter increases.

5. The method of claim 1 , wherein estimating the flow restriction through the diesel particulate filter includes estimating a soot level in the diesel particulate filter.

6. The method of claim 5 , wherein estimating the soot level in the diesel particulate filter includes referencing a soot model and adjusting the backpressure control valve includes increasing opening of the backpressure control valve as the soot level increases.

7. The method of claim 6 , further comprising determining an estimated backpressure control valve position based on the estimated soot level, determining a correction factor for the estimated backpressure control valve position based on engine speed and adjusting the backpressure control valve position based on the estimated backpressure control valve position and the correction factor.

8. The method of claim 7 , further comprising determining an actual air flow rate into the engine assembly and a target air flow rate at current engine operating conditions and adjusting the backpressure control valve based on a difference between the actual air flow rate and the target air flow rate to provide an air flow rate to the engine assembly within a predetermined threshold of the target air flow rate.

9. The method of claim 8 , wherein the providing the controlled amount of internal exhaust gas recirculation to the engine assembly includes an exhaust valve for a combustion chamber being open during an intake stroke of the combustion chamber with the amount of internal exhaust gas recirculation being controlled by a pressure differential between the exhaust system and an intake system of the engine assembly provided by the adjusting the backpressure control valve.

10. An engine assembly comprising:
an engine structure defining a combustion chamber and intake and exhaust ports in communication with the combustion chamber;
an intake system in communication with the intake port;
an exhaust system including:
an exhaust conduit in communication with the exhaust port;
a diesel particulate filter located in the exhaust conduit; and
a backpressure control valve located in the exhaust conduit downstream of the diesel particulate filter;

an internal exhaust gas recirculation system selectively providing internal exhaust gas recirculation; and
a control module in communication with the backpressure control valve and adapted to estimate a flow restriction through the diesel particulate filter, adjust the backpressure control valve position based on the flow restriction and provide a controlled amount of internal exhaust gas recirculation to the engine assembly based on the adjusted backpressure control valve position.

11. The engine assembly of claim 10 , further comprising a valvetrain assembly including an intake valve located in the intake port, an intake valve lift mechanism engaged with the intake valve, an intake cam lobe engaged with the intake valve lift mechanism and defining an intake lift region adapted to open the intake valve, an exhaust valve located in the exhaust port, an exhaust valve lift mechanism engaged with the exhaust valve, and a first exhaust cam lobe engaged with the exhaust valve lift mechanism and defining an EGR lift region at least partially rotationally aligned with the intake lift region and adapted to open the exhaust valve, the exhaust valve lift mechanism being operable in first and second modes, the first mode including the exhaust valve being opened when the EGR lift region engages the exhaust valve lift mechanism and the second mode including the exhaust valve lift mechanism maintaining the exhaust valve in a closed position when the EGR lift region engages the exhaust valve lift mechanism.

12. The engine assembly of claim 11 , wherein the controlled amount of internal exhaust gas recirculation includes the exhaust valve being open during an intake stroke of the combustion chamber with the amount of internal exhaust gas recirculation being controlled by a pressure differential between the exhaust system and an intake system of the engine assembly provided by the adjusted backpressure control valve position.

13. The engine assembly of claim 12 , further comprising:
an EGR line extending from the exhaust conduit at a location downstream of the diesel particulate filter to the intake system and providing communication between the intake and exhaust systems; and
a turbocharger in communication with the exhaust conduit and the intake port and driven by exhaust gas flowing through the exhaust conduit with the turbocharger being in communication with the exhaust conduit at a location upstream of the EGR line.

14. The engine assembly of claim 10 , wherein the control module is adapted to open the backpressure control valve to reduce a flow restriction through the backpressure control valve when the flow restriction through the diesel particulate filter increases.

15. The engine assembly of claim 14 , wherein the estimated flow restriction through the diesel particulate filter includes an estimated soot level in the diesel particulate filter.

16. The engine assembly of claim 10 , wherein the control module includes a soot model for estimating a soot level in the diesel particulate filter, the control module adapted to increase opening of the backpressure control valve as the soot level increases.

17. The engine assembly of claim 16 , wherein the control module is adapted to determine an estimated backpressure control valve position based on the estimated soot level, determine a correction factor for the estimated backpressure control valve position based on engine speed and adjust the backpressure control valve position based on the estimated backpressure control valve position and the correction factor.

18. The engine assembly of claim 17 , further comprising a mass air flow sensor in communication with the control module that provides an actual air flow rate into the engine assembly to the control module, the control module being adapted to determine a target air

Assignees

• Dean Charles
• Gonzalez Delgado Manuel Angel
• Lucido Michael J
• Gm Global Tech Operations Llc

Inventors

• Dean Charles
• Gonzalez Delgado Manuel Angel
• Lucido Michael J

Classifications

• F01L13/0036

  the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction · CPC title

• F02M26/25

  with coolers having bypasses · CPC title

• F02M26/01

  Internal exhaust gas recirculation, i.e. wherein the residual exhaust gases are trapped in the cylinder or pushed back from the intake or the exhaust manifold into the combustion chamber without the use of additional passages · CPC title

• F02M26/06

  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 title

• Y02T10/18

  Cross-Sectional Technologies · mapped topic