Exhaust humidity sensor

Patent metadata

Field	Value
Publication number	US-9410466-B2
Application number	US-201213706194-A
Country	US
Kind code	B2
Filing date	Dec 5, 2012
Priority date	Dec 5, 2012
Publication date	Aug 9, 2016
Grant date	Aug 9, 2016

Abstract

Embodiments for adjusting engine operating parameters based on output from an exhaust humidity sensor are provided. One example method for an engine comprises based on a dew point of exhaust gas, adjusting an exhaust gas sensor heater configured to heat an exhaust gas sensor disposed in an exhaust passage of the engine, the dew point based on output from a humidity sensor disposed in the exhaust passage.

First claim

The invention claimed is:

1. A method for an engine, comprising:
based on a dew point of exhaust gas, adjusting an exhaust gas sensor heater configured to heat an exhaust gas sensor disposed in an exhaust passage of the engine, the dew point based on output from a humidity sensor disposed in the exhaust passage, and
adjusting a fuel injection amount based on output from the humidity sensor,
wherein the dew point is determined based on relative humidity of the exhaust gas determined by the humidity sensor, exhaust gas temperature, and exhaust gas pressure.

2. The method of claim 1 , wherein adjusting the exhaust gas sensor heater further comprises deactivating the exhaust gas sensor heater if the dew point is greater than a temperature of the exhaust gas sensor.

3. The method of claim 1 , wherein adjusting the exhaust gas sensor heater further comprises activating the exhaust gas sensor heater if the dew point is less than a temperature of the exhaust gas sensor and exhaust gas temperature is below a threshold.

4. The method of claim 1 , further comprising adjusting exhaust gas temperature based on output from the humidity sensor.

5. A method for an engine, comprising:
determining a light-off temperature of a catalyst disposed in an exhaust passage of the engine based on exhaust gas water content measured by a humidity sensor disposed in the exhaust passage downstream of the catalyst; and
during engine cold start conditions,
predicting an amount of water to be released from the catalyst when the catalyst reaches light-off temperature;
setting the light-off temperature as an exhaust gas temperature at which the predicted amount of water is released from the catalyst; and
adjusting engine operating parameters to increase exhaust gas temperature above the light-off temperature.

6. The method of claim 5 , further comprising determining that the predicted amount of water has been released from the catalyst based on output from the humidity sensor.

7. The method of claim 5 , wherein the predicted amount of water to be released from the catalyst is estimated based on an amount of exhaust gas constituents stored in the catalyst during cold start conditions.

8. The method of claim 5 , wherein adjusting engine operating parameters to increase exhaust gas temperature further comprises adjusting air-fuel ratio.

9. The method of claim 5 , wherein adjusting engine operating parameters to increase exhaust gas temperature further comprises retarding spark timing.

10. A method performed by an electronic controller in combination with an engine and one or more sensors, comprising:
adjusting via the electronic controller a measured exhaust gas water content based on water storage and release in a catalyst, the exhaust gas water content measured by a humidity sensor disposed in an exhaust passage of the engine; and
adjusting a fuel injection amount injected by an injector based on the adjusted exhaust gas water content.

11. The method of claim 10 , wherein the catalyst is positioned upstream of the humidity sensor, and wherein the water storage and release is determined based on an amount of water produced during combustion and catalyst temperature.

12. The method of claim 11 , wherein the amount of water produced during combustion is estimated based on intake air humidity, air-fuel ratio, and fuel composition.

13. The method of claim 12 , wherein the fuel composition is determined based on output from the humidity sensor.

14. The method of claim 10 , wherein adjusting the measured exhaust gas water content further comprises, if water is being released from the catalyst, decreasing the measured exhaust gas water content by an amount of released water.

15. The method of claim 10 , wherein adjusting the measured exhaust gas water content further comprises, if water is being stored in the catalyst, increasing the measured exhaust gas water content by an amount of stored water.

16. The method of claim 10 , wherein adjusting the fuel injection amount further comprises increasing the fuel injection amount if the adjusted exhaust gas water content is greater than a threshold, and decreasing the fuel injection amount if the adjusted exhaust gas water content is less than the threshold.

17. The method of claim 12 , wherein the humidity sensor is a first humidity sensor, and further comprising determining the intake air humidity based on output from a second humidity sensor disposed in an intake passage of the engine.

18. The method of claim 10 , further comprising determining a dew point of exhaust gas based on the adjusted exhaust gas water content and adjusting an exhaust gas sensor heater configured to heat an exhaust gas sensor disposed in the exhaust passage of the engine based on the dew point of the exhaust gas.

19. The method of claim 18 , wherein adjusting the exhaust gas sensor heater further comprises deactivating the exhaust gas sensor heater if the dew point is greater than a temperature of the exhaust gas sensor.

20. The method of claim 18 , wherein adjusting the exhaust gas sensor heater further comprises activating the exhaust gas sensor heater if the dew point is less than a temperature of the exhaust gas sensor and exhaust gas temperature is below a threshold.

21. The method of claim 10 , comprising:
determining a light-off temperature of the catalyst based on exhaust gas water content measured by the humidity sensor; and
during cold start conditions, adjusting engine operating parameters to increase exhaust gas temperature above the light-off temperature.

22. The method of claim 21 , wherein determining the light-off temperature further comprises:
during engine cold start conditions, predicting an amount of water to be released from the catalyst when the catalyst reaches light-off temperature; and
setting the light-off temperature as an exhaust gas temperature at which the predicted amount of water is released from the catalyst.

23. The method of claim 22 , further comprising determining that the predicted amount of water has been released from the catalyst based on output from the humidity sensor.

24. The method of claim 23 , wherein the predicted amount of water to be released from the catalyst is estimated based on an amount of exhaust gas constituents stored in the catalyst during cold start conditions.

25. The method of claim 10 , further comprising determining an amount of water stored in the catalyst based on engine load and catalyst temperature, and determining an amount of water released from the catalyst based on catalyst temperature, an amount of water previously stored in the catalyst, and mass flow of exhaust through the catalyst.

26. The method of claim 10 , further comprising adjusting spark timing of a spark plug based on the adjusted exhaust gas water content.

Assignees

• Ford Global Tech Llc

Inventors

• Surnilla Gopichandra
• Soltis Richard E
• Visser Jacobus Hendrik
• Smith Stephen B
• Clark Timothy

Classifications

• F02D41/1454

  the characteristics being an oxygen content or concentration or the air-fuel ratio · CPC title

• G01N19/10

  Measuring moisture content, e.g. by measuring change in length of hygroscopic filament; Hygrometers · CPC title

• F01N2560/02

  the means being an exhaust gas sensor · CPC title

• F01N2560/026

  for measuring or detecting NOx · CPC title

• F01N2560/028

  for measuring or detecting humidity or water · CPC title