Operation of an internal combustion engine

Patent metadata

Field	Value
Publication number	US-9297327-B2
Application number	US-201313851014-A
Country	US
Kind code	B2
Filing date	Mar 26, 2013
Priority date	Mar 27, 2012
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

Abstract

Methods and systems are provided for accurately measuring an air-fuel-ratio of an engine. During a first condition of decreased scavenging, adjusting fuel injection based on a more-upstream air-fuel ratio, and during a second condition of increased scavenging, adjusting fuel injection based on one or more more-downstream air-fuel ratios and not based on the more-upstream air-fuel ratio. During the first condition, adjusting fuel injection may be further based on the one or more more-downstream air-fuel ratios.

First claim

The invention claimed is:

1. A method for an engine, comprising:
during a first condition comprising decreased scavenging, adjusting fuel injection based on a more-upstream air-fuel ratio; and
during a second condition comprising increased scavenging, stopping monitoring of an emission control device, and adjusting fuel injection based on one or more more-downstream air-fuel ratios and not based on the more-upstream air-fuel ratio.

2. The method of claim 1 , wherein during the first condition, adjusting fuel injection is further based on the one or more more-downstream air-fuel ratios.

3. The method of claim 1 , wherein the engine is boosted via a turbocharger.

4. The method of claim 1 , further comprising increasing valve overlap to increase scavenging and reducing valve overlap to decrease scavenging.

5. The method of claim 4 , further comprising in response to air-fuel fluctuations being greater than a threshold air-fuel fluctuation level,
reducing valve overlap during the second condition to reduce scavenging to the decreased scavenging of the first condition; and then
adjusting fuel injection based on the one or more more-downstream air-fuel ratios and not based on the more-upstream air-fuel ratio.

6. The method of claim 1 , wherein the second condition further comprises engine speeds less than one-third a threshold engine speed and engine loads greater than one-half a threshold engine load.

7. The method of claim 6 , wherein the second condition further comprises engine speeds less than one-quarter the threshold engine speed.

8. The method of claim 6 , wherein the second condition further comprises engine loads greater than three-quarters the threshold engine load.

9. The method of claim 1 , wherein the second condition further comprises engine loads greater than one-half a threshold engine load and a larger valve overlap, and wherein the first condition further comprises engine loads less than one-half a threshold engine load and a smaller valve overlap.

10. The method of claim 1 , wherein adjusting the fuel injection during the second condition comprises adjusting the fuel injection so that an engine cylinder air-fuel equivalent ratio is less than 0.9, and one of the one or more more-downstream air-fuel equivalent ratios is 1.

11. The method of claim 10 , wherein adjusting the fuel injection during the second condition comprises adjusting the fuel injection so that an engine cylinder air-fuel equivalent ratio is less than 0.85, and one of the one or more more-downstream air-fuel equivalent ratios is 1.

12. The method of claim 1 , wherein the more-upstream air-fuel ratio is measured upstream of the emission control device.

13. The method of claim 1 , wherein one of the one or more more-downstream air-fuel ratios is measured downstream of the emission control device.

14. The method of claim 1 , wherein the more-upstream air-fuel ratio and the one or more more-downstream air-fuel ratios are measured by a more-upstream exhaust gas oxygen sensor and one or more more-downstream exhaust gas oxygen sensors, respectively.

15. The method of claim 14 , further comprising in response to an amount of fuel at the more-upstream exhaust gas oxygen sensor being greater than a threshold amount of fuel, adjusting fuel injection based on the one or more more-downstream air-fuel ratios and not based on the more-upstream air-fuel ratio.

16. A method for a fuel-injected, turbocharged engine, comprising:
during a first condition comprising an engine speed greater than one-third a threshold engine speed and a load greater than one-half a threshold load, operating the engine with decreased scavenging and adjusting fuel injection based on a more-upstream air-fuel ratio; and
during a second condition comprising the engine speed less than one-third the threshold engine speed and the load greater than one-half the threshold load, stopping monitoring of an emission control device, and operating the engine with increased scavenging and adjusting fuel injection based on one or more more-downstream air-fuel ratios and not based on the more-upstream air-fuel ratio.

17. The method of claim 16 , wherein operating the engine with increased scavenging comprises operating the engine with increased engine intake and engine exhaust valve overlap, and operating the engine with decreased scavenging comprises operating the engine with decreased engine intake and engine exhaust valve overlap.

18. The method of claim 17 , wherein the more-upstream air-fuel ratio is measured upstream of the emission control device and one of the one or more more-downstream air-fuel ratios is measured downstream of the emission control device.

19. A system, comprising:
an engine;
a more-upstream exhaust gas oxygen sensor;
a more-downstream exhaust gas oxygen sensor;
an emission control device; and
a controller with instructions executable to:
during a first condition comprising decreased scavenging, adjusting fuel injection based on a more-upstream air-fuel ratio; and
during a second condition comprising increased scavenging, stopping monitoring of the emission control device, and adjusting fuel injection based on one or more more-downstream air-fuel ratios and not based on the more-upstream air-fuel ratio.

20. The system of claim 19 , wherein the more-upstream exhaust gas oxygen sensor is positioned upstream of the emission control device, and wherein the more-downstream exhaust gas oxygen sensor is positioned downstream of the emission control device.

Assignees

• Ford Global Tech Llc

Inventors

• Ruhland Helmut Hans
• Breuer Albert
• Lorenz Thomas
• Springer Moritz Klaus

Classifications

• Y02T10/12

  Improving ICE efficiencies · CPC title

• F02D13/0276

  Actuation of an additional valve for a special application, e.g. for decompression, exhaust gas recirculation or cylinder scavenging · CPC title

• F02D2041/001

  for engines with variable valve actuation · CPC title

• F01N11/007

  the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus · CPC title

• F02D41/1441 Primary

  Plural sensors · CPC title