Continuous adaptation of an intake oxygen sensor for pressure, humidity and aging

Patent metadata

Field	Value
Publication number	US-9784195-B2
Application number	US-201514834719-A
Country	US
Kind code	B2
Filing date	Aug 25, 2015
Priority date	Aug 28, 2014
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

A technique is provided for compensating an untrimmed oxygen (O 2 ) sensor utilized in operation of an exhaust gas recalculation (EGR) system associated with an engine. The technique includes, in one implementation, receiving a measurement from the O 2 sensor at a known pressure, where the O 2 sensor is positioned on an intake side of an engine system. Humidity compensation and pressure compensation are then determined for the O 2 sensor measurement, where the pressure compensation is based in part on the humidity compensation. The EGR system is controlled using the untrimmed O 2 sensor measurement that has been compensated for pressure and humidity.

First claim

What is claimed is:

1. A method for use in compensating a sensor utilized in operation of an exhaust gas recirculation (EGR) system, the method comprising:
receiving, at a controller of an engine system, the controller having one or more processors, a measurement from an untrimmed oxygen (O 2 ) sensor at a known pressure, the untrimmed O 2 sensor positioned on an intake side of the engine system;
determining, at the controller, humidity compensation for the untrimmed O 2 sensor measurement;
determining, at the controller, pressure compensation for the untrimmed O 2 sensor measurement, the pressure compensation based in part on the humidity compensation; and
controlling, by the controller, the EGR system associated with the engine system using the untrimmed O 2 sensor measurement that has been compensated for pressure and humidity;
wherein determining the pressure compensation includes determining, at the controller, the untrimmed O 2 sensor measurement compensated for pressure and humidity (O 2 Corr ) as:

O

2
Corr

=

P
ref

P
sense

×

V
sense

-

V
Offset

V
ref

-

V
Offset

×

(

∝
^

⁢

+

B
^

×

P
sense

)

,

where P ref represents a reference pressure determined at the controller, P sense represents each of the plurality of pressure measurements for each untrimmed O 2 sensor measurement, V sense represents each of a plurality of untrimmed O 2 sensor measurements in terms of voltage, V ref represents a reference voltage of the untrimmed O 2 sensor determined by the controller, V offset represents an offset voltage associated with the untrimmed O 2 sensor, and {circumflex over (B)} and {circumflex over (∝)} represent the respective slope and offset of a best fit error ration line of the plurality of untrimmed O 2 sensor measurements.

2. The method of claim 1 , further comprising determining, at the controller, whether the following enable conditions are satisfied prior to determining the pressure compensation: i) an intake air stream contains only fresh air, and ii) a pressure of the intake air stream at a location of the untrimmed O 2 sensor is substantially steady.

3. The method of claim 2 , wherein determining whether the intake air stream includes only fresh air includes determining whether: i) an EGR valve of an EGR system associated with the engine has been closed for a predetermined period of time; ii) the untrimmed O 2 sensor is above a predetermined temperature; and iii) a purge operation of an evaporative system associated with the engine system is not active.

4. The method of claim 2 , wherein determining pressure compensation for the untrimmed O 2 sensor measurement includes:
receiving, at the controller, the plurality of untrimmed O 2 sensor measurements and corresponding pressure measurements from a pressure sensor proximate the untrimmed O 2 sensor;
compensating, at the controller, each of the plurality of untrimmed O 2 sensor measurements for humidity;
compensating, at the controller, each of the of the plurality of untrimmed O 2 sensor measurements, which have already been compensated for humidity, for partial pressure;
determining, at the controller, an error ratio for each of plurality of untrimmed O 2 sensor measurements that have been compensated for humidity and partial pressure and storing the determined error ratio as a first set of values at the controller; and
determining, at the controller, pressure compensation factors based on the determined error ratio for each of plurality of untrimmed O 2 sensor measurements.

5. The method of claim 4 , wherein determining pressure compensation factors based on the error ratio for each of plurality of untrimmed O 2 sensor measurements includes determining, at the controller, the best fit error ratio line of the first set of values using an ordinary least square estimation method, where the error ratio line includes the slope ({circumflex over (B)}) and the offset ({circumflex over (∝)}).

6. The method of claim 5 , further comprising compensating, at the controller, the untrimmed O 2 sensor measurement, which has been compensated for pressure and humidity, for aging of the untrimmed O 2 sensor.

7. The method of claim 6 , wherein compensating the untrimmed O 2 sensor for aging includes:
identifying, at the controller, a predetermined number of error ratio values that are furthest from the determined best fit error ratio line and discarding the identified predetermined error ratio values;
receiving, at the controller, additional untrimmed O 2 sensor measurements and compensating the same, at the controller, for humidity and pressure; and
determining, at the controller, a revised error ratio best fit line based on first set of values and the additional untrimmed O 2 sensor measurements compensated for humidity and pressure, and revised slope ({circumflex over (B)}) and offset ({circumflex over (∝)}) pressure compensation factors based on the revised error ratio best fit line.

8. The method of claim 7 , further comprising controlling, by the controller, the EGR system using the untrimmed O 2 sensor measurement that has been compensated for pressure, humidity and aging of the untrimmed O 2 sensor.

9. A system for compensating a sensor utilized in operation of an exhaust gas recirculation (EGR) system, the system comprising:
an engine system including an engine, the EGR system, a pressure sensor, a humidity sensor, and an untrimmed oxygen (O 2 ) sensor, the untrimmed O 2 sensor and pressure sensor positioned on an intake side of the engine system; and
a controller configured to:
receive a measurement from the untrimmed O 2 sensor at a known pressure determined from the pressure sensor;
determine humidity compensation for the untrimmed O 2 sensor measurements utilizing input from the humidity sensor;
determine pressure compensation for the untrimmed O 2 sensor measurement, the pressure compensation based in part on the humidity compensation; and
control the EGR system using th

Assignees

• Ismail Ayman M
• Bayer Ethan E
• Bucknell John R
• Fca Us Llc

Inventors

• Ismail Ayman M
• Bayer Ethan E
• Bucknell John R

Classifications

• F02D41/2454

  Learning of the air-fuel ratio control · CPC title

• F02D41/0052

  Feedback control of engine parameters, e.g. for control of air/fuel ratio or intake air amount · CPC title

• F02D2041/1472

  the characteristics being a humidity or water content of the exhaust gases · CPC title

• Y02T10/47

  Cross-Sectional Technologies · mapped topic

• F02M26/46

  for determining the characteristics of gases, e.g. composition · CPC title