Engine condensation control system and method

Patent metadata

Field	Value
Publication number	US-9879626-B1
Application number	US-201615264724-A
Country	US
Kind code	B1
Filing date	Sep 14, 2016
Priority date	Sep 14, 2016
Publication date	Jan 30, 2018
Grant date	Jan 30, 2018

Abstract

A system and method for controlling condensation formation in an engine having EGR and forced induction includes a controller for determining a water vapor mass fraction of an exhaust stream based on a water vapor mass fraction of an intake stream and water vapor from combustion. An estimated condensation temperature (CT) is determined for a current EGR level based on the water vapor mass fractions and is compared to an intake stream temperature upstream of the compressor inlet. The controller commands the current EGR level as a maximum EGR level upon determining the intake stream temperature is less than the CT, and an increase in the current EGR level upon determining the intake stream temperature is greater than the CT. An air charge temperature (ACT) of the forced induction system may be controlled based on utilizing a target ACT as the CT to be controlled by a coolant pump.

First claim

What is claimed is:

1. A system for controlling condensation formation in an engine system having an exhaust gas recirculation system and a forced induction system including a compressor, the system comprising:
a controller in communication with the engine system, the EGR system and one or more temperature and pressure sensors, the controller configured to:
determine a water vapor mass fraction of an intake air stream at a location upstream of an inlet of the compressor;
determine a water vapor mass fraction of an exhaust air stream based on the determined water vapor mass fraction of the intake air stream and water vapor from a combustion event;
determine a current EGR level, a temperature of the intake air stream at the location upstream of the compressor inlet;
determine, for the current EGR level, an estimated condensation temperature based at least in part on the determined water vapor mass fractions for the intake air stream and the exhaust air stream;
compare the determined intake air stream temperature to the estimated condensation temperature; and
command i) the current EGR level as a first maximum EGR level upon determining the determined intake air stream mixture temperature is less than or equal to the estimated condensation temperature, and ii) an increase in the current EGR level by a predetermined amount upon determining that the intake air stream mixture temperature is greater than the estimated condensation temperature.

2. The system of claim 1 , wherein commanding the current EGR level as the maximum EGR level includes commanding an EGR valve of the EGR system to maintain its current position, and wherein commanding an increase in the current EGR level includes commanding the EGR valve to open an additional predetermined amount.

3. The system of claim 1 , wherein the controller is further configured to determine a partial pressure of water vapor in the intake air stream at the location upstream of the compressor inlet; and wherein the controller is configured to determine the water vapor mass fraction based on the determined partial pressure of water vapor in the intake air stream.

4. The system of claim 1 , further comprising a charge air cooler (CAC), wherein the controller is further configured to:
determine an overall air charge temperature (ACT) and a local (CAC) temperature; and
determine, based on the determined ACT and CAC temperatures, second and third maximum EGR levels before condensation begins in the CAC.

5. The system of claim 4 , wherein the controller is further configured to:
compare the first, second and third determined maximum EGR levels;
select the minimum of the first, second and third maximum EGR levels as the selected current EGR level; and
control an EGR valve of the engine system to provide the selected current EGR level.

6. The system of claim 5 , wherein the controller is configured to utilize the determined ACT and CAC temperatures as dew point temperatures and determine the second and third maximum EGR levels based on using the determined ACT and CAC temperatures as dew point temperatures.

7. The system of claim 1 , further comprising a low temperature radiator circuit coolant pump in fluid communication with a charge air cooler of the forced induction system.

8. The system of claim 7 , wherein the controller is configured to:
determine a target air charge temperature (ACT) and use the determined target ACT as an estimated dew point temperature; and
control the coolant pump to control a temperature of the air in the charge air cooler to the target ACT.

9. A method for controlling condensation formation in an engine system having an exhaust gas recirculation system and a forced induction system including a compressor, the method comprising:
determining, at a controller, a water vapor mass fraction of an intake air stream at a location upstream of an inlet of the compressor;
determining, at the controller, a water vapor mass fraction of an exhaust air stream based on the determined water vapor mass fraction of the intake air stream and water vapor from a combustion event;
determining, at the controller and for a current EGR level, a temperature of the intake air stream mixture at the location upstream of the compressor inlet;
determining, at the controller and for the current EGR level, an estimated condensation temperature based at least in part on the determined water vapor mass fractions for the intake air stream and the exhaust air stream;
comparing, at the controller, the determined intake air stream temperature to the estimated condensation temperature; and
commanding, by the controller, i) the current EGR level as a first maximum EGR level upon determining the determined intake air stream mixture temperature is less than or equal to the estimated condensation temperature, and ii) an increase in the current EGR level by a predetermined amount upon determining that the intake air stream mixture temperature is greater than the estimated condensation temperature.

10. The method of claim 9 , wherein commanding the current EGR level as the maximum EGR level includes commanding an EGR valve of the engine system to maintain its current position, and wherein commanding an increase in the current EGR level includes commanding the EGR valve to open an additional predetermined amount.

11. The method of claim 9 , further comprising determining, at the controller, a partial pressure of water vapor in the intake air stream at the location upstream of the compressor inlet; and wherein the water vapor mass fraction is determined based on the determined partial pressure of water vapor in the intake air stream.

12. The method of claim 9 , further comprising:
determining an overall air charge temperature (ACT) and a local charge air cooler (CAC) temperature; and
determining, based on the determined ACT and CAC temperatures, second and third maximum EGR levels before condensation begins in the CAC.

13. The method of claim 12 , further comprising:
comparing the first, second and third determined maximum EGR levels; and selecting the minimum of the first, second and third maximum EGR levels as the current EGR level.

14. The method of claim 13 , wherein determining the second and third maximum EGR levels includes using the determined ACT and CAC temperatures as dew point temperatures and determining the second and third maximum EGR levels using the ACT and CAC temperatures as dew point temperatures.

Assignees

• Mavalankar Drushan
• Bayer Ethan E
• Bucknell John R
• Theru Sangeeta
• Fca Us Llc

Inventors

• Mavalankar Drushan
• Bayer Ethan E
• Bucknell John R
• Theru Sangeeta

Classifications

• F02M35/10222

  Exhaust gas recirculation [EGR]; Positive crankcase ventilation [PCV]; Additional air admission, lubricant or fuel vapour admission · CPC title

• F02D41/0077 Primary

  Control of the EGR valve or actuator, e.g. duty cycle, closed loop control of position (EGR valve position sensor F02M26/48) · CPC title

• F02D2200/0414

  Air temperature · CPC title

• F02M35/1038 Primary

  for temperature or pressure · CPC title

• F02D41/0072

  Estimating, calculating or determining the EGR rate, amount or flow (sensors in EGR systems F02M26/45) · CPC title