Methods and systems for fuel ethanol content determination via an oxygen sensor

Patent metadata

Field	Value
Publication number	US-9404432-B2
Application number	US-201414151574-A
Country	US
Kind code	B2
Filing date	Jan 9, 2014
Priority date	Jan 9, 2014
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

Methods are provided for accurately learning part-to-part variability of an intake or exhaust oxygen sensor. A correction factor is learned based on a sensor reading in dry air conditions, the dry air reading learned by applying a higher reference voltage to the sensor. An ethanol transfer function is then adjusted based on the learned correction factor so as to improve the accuracy of combusted fuel ethanol content estimation.

First claim

The invention claimed is:

1. A method for an engine, comprising:
during selected conditions,
operating an oxygen sensor at a lower reference voltage to generate a first output and at a higher reference voltage to generate a second output; and
adjusting a parameter based on an alcohol content, the alcohol content of fuel combusted in the engine estimated based on each of the first output and a learned correction factor for the sensor based on the second output; where
the second output is indicative of a dry air reading even under different humidity conditions.

2. The method of claim 1 , wherein the lower reference voltage does not dissociate water molecules, and wherein the higher reference voltage dissociates water molecules, and wherein the parameter is a desired engine air-fuel ratio for combustion.

3. The method of claim 1 , wherein the first output includes a first pumping current generated responsive to the operating at the lower reference voltage and wherein the second output includes a second pumping current generated responsive to operating at the higher reference voltage.

4. The method of claim 1 , wherein the first output is indicative of a humid air oxygen reading.

5. The method of claim 1 , wherein the correction factor is a factor that compensates for part-to-part variability of the sensor, and wherein learning the correction factor based on the second output includes learning the correction factor based on a ratio of a reference sensor output relative to the second output.

6. The method of claim 5 , wherein a reference alcohol transfer function of the sensor is based on the reference sensor output.

7. The method of claim 6 , wherein the alcohol content of fuel estimated based on each of the first output and the learned correction factor includes:
adjusting the reference alcohol transfer function of the sensor based on the learned correction factor; and
applying the adjusted alcohol transfer function to the first output of the sensor.

8. The method of claim 1 , wherein the oxygen sensor is a universal exhaust gas oxygen sensor coupled to an exhaust manifold of the engine, upstream of an exhaust catalyst.

9. The method of claim 8 , wherein the selected conditions include engine non-fueling conditions, the engine non-fueling conditions including a deceleration fuel shut-off event, and wherein the higher reference voltage is 950 mV.

10. The method of claim 1 , wherein the oxygen sensor is an intake oxygen sensor coupled to an intake manifold of the engine, upstream of an intake compressor.

11. The method of claim 10 , wherein the selected conditions include EGR being enabled and no purge or crankcase ventilation gases being received in the intake manifold.

12. A method, comprising:
during engine non-fueling conditions,
applying each of a first, lower and second, higher voltage to an exhaust oxygen sensor;
learning a correction factor for the sensor based on a ratio of first and second outputs generated upon applying the first and second voltages, respectively; and
estimating an ethanol content of fuel combusted in the engine by applying the learned correction factor to a transfer function based on the first output; where
the second voltage is selected such that the second output is the same even under different humidity conditions.

13. The method of claim 12 , wherein the engine non-fueling conditions include a deceleration fuel shut-off event, the method further comprising adjusting an engine operating parameter based on the estimated fuel ethanol content, the parameter including an air-fuel ratio for combustion.

14. The method of claim 13 , wherein the first, lower voltage is a voltage that does not dissociate water molecules, and wherein the second, higher voltage is a voltage that partially dissociates water molecules.

15. The method of claim 14 , wherein the first output includes a first pumping current generated responsive to applying the first, lower voltage, the first output indicative of a humid air oxygen amount, and wherein the second output includes a second pumping current generated responsive to applying the second, higher voltage, the second output indicative of a dry air oxygen amount.

16. The method of claim 12 , wherein the exhaust gas oxygen sensor is located upstream of an exhaust catalyst and upstream of an inlet of an EGR passage configured to recirculate exhaust residuals from an exhaust manifold to an intake manifold of the engine.

17. A method, comprising:
while purge and crankcase ventilation gases are not ingested in an engine,
applying each of a first, lower and second, higher voltage to an intake oxygen sensor;
learning a correction factor for the sensor based on a ratio of first and second outputs generated upon applying the first and second voltages, respectively; and
estimating an ethanol content of fuel combusted in the engine by applying the learned correction factor to a transfer function based on the first output, wherein
the second output is indicative of a dry air reading even under different humidity conditions.

18. The method of claim 17 , wherein the first, lower voltage is a voltage that does not dissociate water molecules, and wherein the second, higher voltage is a voltage that dissociates water molecules.

19. The method of claim 18 , wherein the first output includes a first pumping current generated responsive to applying the first, lower voltage, the first output indicative of a humid air oxygen amount, and wherein the second output includes a second pumping current generated responsive to applying the second, higher voltage, the second output indicative of a dry air oxygen amount.

20. The method of claim 17 , wherein the intake oxygen sensor is located upstream of an intake throttle, and downstream of an outlet of an EGR passage configured to recirculate exhaust residuals from an exhaust manifold to an intake manifold of the engine.

Assignees

• Ford Global Tech Llc

Inventors

• Surnilla Gopichandra
• Soltis Richard E
• Makled Daniel A
• Visser Jacobus Hendrik
• Scholl David James

Classifications

• F01N11/007

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

• F02D41/1456

  with sensor output signal being linear or quasi-linear with the concentration of oxygen · CPC title

• F02D2200/0612

  determined by estimation · CPC title

• F02D41/123

  the fuel injection being cut-off · CPC title

• Y02T10/36

  Cross-Sectional Technologies · mapped topic