Methods and systems for open loop and closed loop control of an exhaust gas recirculation system

Patent metadata

Field	Value
Publication number	US-10156194-B2
Application number	US-201815964525-A
Country	US
Kind code	B2
Filing date	Apr 27, 2018
Priority date	Nov 5, 2015
Publication date	Dec 18, 2018
Grant date	Dec 18, 2018

Abstract

Methods and systems are provided for estimating exhaust gas recirculation (EGR) flow in an engine including an EGR system. In one example, a method may include operating the EGR system in an open loop feed forward mode based on an intake carbon di oxide sensor output above a threshold engine load and/or when a manifold absolute pressure (MAP) is above a threshold pressure, and operating the EGR system in a closed loop feedback mode based on a differential pressure sensor output when the engine load decreases below the threshold load and/or when the MAP decreases below the threshold pressure.

First claim

The invention claimed is:

1. A method for an engine, comprising:
estimating an exhaust gas recirculation (EGR) mass flow based on a differential pressure sensor output when an engine load is below a threshold;
estimating the EGR mass flow based on an intake carbon dioxide sensor output when the engine load is above the threshold and independent of the differential pressure sensor output; and
adjusting a spark timing based on the estimated EGR mass flow.

2. The method of claim 1 , wherein an EGR valve is in a fully open position when the engine load is above the threshold.

3. The method of claim 2 , further comprising turning off EGR system diagnostics when the engine load is above the threshold.

4. The method of claim 1 , further comprising, during a first transition from a first load below the threshold to a second load above the threshold, estimating the EGR mass flow independent of the differential pressure sensor output and based on the intake carbon dioxide sensor output.

5. The method of claim 4 , wherein, during the transition, an EGR valve is ramped open to a fully open position.

6. The method of claim 1 , further comprising, during a second transition from the second load above the threshold to the first load below the threshold, estimating the EGR mass flow independent of the differential pressure sensor output and based on the intake carbon dioxide sensor output.

7. The method of claim 6 , wherein an EGR valve is ramped closed from a fully open position to a less open position, the less open position based on a desired EGR flow at the second load.

8. The method of claim 1 , wherein the EGR is a high pressure EGR (HP EGR).

9. The method of claim 8 , wherein the engine is a V-engine; and wherein the HP EGR is on only one bank of the engine.

Assignees

• Ford Global Tech Llc

Inventors

• Gates Freeman Carter
• Pulay Kirk
• Russ Stephen George

Classifications

• F02P5/1516

  with means relating to exhaust gas recirculation, e.g. turbo · CPC title

• F02P5/15

  Digital data processing · CPC title

• F02P5/045

  combined with electronic control of other engine functions, e.g. fuel injection (in general F02D37/02) · CPC title

• F02M26/53

  using electric actuators, e.g. solenoids · CPC title

• F02M26/47

  the characteristics being temperatures, pressures or flow rates · CPC title