Method and system for controlling an oxygen sensor

Patent metadata

Field	Value
Publication number	US-2019360419-A1
Application number	US-201815988440-A
Country	US
Kind code	A1
Filing date	May 24, 2018
Priority date	May 24, 2018
Publication date	Nov 28, 2019
Grant date	—

Abstract

Methods and systems are provided for adjusting a voltage of a heated oxygen sensor (HEGO) so that the heated oxygen sensor is controlled to a desired temperature as the HEGO ages. In one example, a method generates a requested heated oxygen sensor electrode impedance for control and then adjusts the voltage responsive to the requested heated oxygen sensor electrode impedance for control.

First claim

1 . An operating method for an oxygen sensor, comprising:
adjusting a voltage applied to an oxygen sensor heater while the oxygen sensor is exposed to combustion products of a first rich air-fuel mixture according to a first curve describing a relationship between oxygen sensor electrode impedance and oxygen sensor temperature for the oxygen sensor being exposed to the combustion products of a second rich air-fuel mixture.

2 . The method of claim 1 , further comprising:
adjusting the voltage applied to the oxygen sensor heater while the oxygen sensor is exposed to combustion products of a first lean air-fuel mixture according to a second curve describing a relationship between oxygen sensor electrode impedance and oxygen sensor temperature for the oxygen sensor being exposed to the combustion products of a second lean air-fuel mixture.

3 . The method of claim 2 , where the first curve is derived from a third curve describing a relationship between oxygen sensor electrode impedance and oxygen sensor temperature for an aged oxygen sensor being exposed to combustion products of the second rich air-fuel mixture and a fourth curve describing a relationship between oxygen sensor electrode impedance and oxygen sensor temperature for a new oxygen sensor being exposed to combustion products of the second rich air-fuel mixture.

4 . The method of claim 3 , where the second curve is derived from a fifth curve describing a relationship between oxygen sensor electrode impedance and oxygen sensor temperature for the aged oxygen sensor being exposed to combustion products of the second lean air-fuel mixture and a sixth curve describing a relationship between oxygen sensor electrode impedance and oxygen sensor temperature for a new oxygen sensor being exposed to combustion products of the second lean air-fuel mixture.

5 . The method of claim 1 , further comprising subtracting an actual oxygen sensor electrode impedance from a requested oxygen sensor electrode impedance to adjust the voltage applied to the oxygen sensor heater.

6 . The method of claim 1 , where the first curve is described via a first numeric coefficient and a second numeric coefficient.

7 . The method of claim 2 , where the second curve is described via a first numeric coefficient and a second numeric coefficient.

8 . The method of claim 1 , where the voltage is adjusted during conditions when the oxygen sensor impedance is determined to be stable.

9 . An operating method for an oxygen sensor, comprising:
adjusting a requested oxygen sensor electrode impedance while the oxygen sensor is exposed to combustion products of a first rich air-fuel mixture according to a first curve describing a relationship between oxygen sensor electrode impedance and oxygen sensor temperature for the oxygen sensor being exposed to the combustion products of a second rich air-fuel mixture; and adjusting a voltage applied to a heater of the oxygen sensor according to the requested oxygen sensor electrode impedance.

10 . The method of claim 9 , further comprising subtracting an actual oxygen sensor electrode impedance from the requested oxygen sensor electrode impedance to generate an oxygen sensor electrode impedance error.

11 . The method of claim 10 , further comprising modifying the electrode impedance error via proportional and integral controller gains to generate a proportional and integral controller output.

12 . The method of claim 11 , further comprising adjusting the voltage applied to a heater of the oxygen sensor responsive to the proportional and integral controller output.

13 . The method of claim 9 , further comprising adjusting the requested oxygen sensor electrode impedance while the oxygen sensor is exposed to combustion products of a first lean air-fuel mixture according to a second curve describing a relationship between oxygen sensor electrode impedance and oxygen sensor temperature for the oxygen sensor being exposed to the combustion products of a second lean air-fuel mixture.

14 . The method of claim 9 , further comprising interpolating between a third curve and a fourth curve to generate the first curve.

15 . A hybrid vehicle, comprising:
a powertrain comprising an engine, a motor/generator, a battery, and a transmission coupled to vehicle wheels; a three-way catalyst arranged in an engine exhaust passage; a first heated exhaust gas oxygen (HEGO) sensor arranged downstream of the three-way catalyst in the exhaust passage; a second HEGO sensor arranged upstream of the three-way catalyst in the exhaust passage; a controller including non-transitory memory with instructions stored therein which are executable by the controller to:
adjust a first voltage applied to a heater of the first HEGO responsive to a requested electrode impedance of the first HEGO, the requested electrode impedance generated via a first curve representing an aged oxygen sensor and a second curve representing a new oxygen sensor, and adjust a second voltage applied to a heater of the second HEGO responsive to a requested electrode impedance of the second HEGO, the requested electrode impedance generated via the first curve representing the aged oxygen sensor and the second curve representing the new oxygen sensor.

16 . The hybrid vehicle of claim 15 , further comprising additional instructions to generate a third curve based on the first curve, the second curve, and an actual electrode impedance of the HEGO.

17 . The hybrid vehicle of claim 15 , where generating the third curve includes filtering a numerical interpolation factor that is a basis for generating the third curve.

18 . The hybrid vehicle of claim 17 , further comprising additional instructions to iteratively determining the numerical interpolation factor.

19 . The hybrid vehicle of claim 15 , further comprising additional instructions to determine an electrode impedance when the HEGO is exposed to exhaust gases of a combusted lean air-fuel mixture.

20 . The hybrid vehicle of claim 15 , further comprising additional instructions to determine an electrode impedance when the HEGO is exposed to exhaust gases of a combusted rich air-fuel mixture.

Assignees

• Ford Global Tech Llc

Inventors

• Behr Kenneth
• Yee Zena Yanqing
• Galicia Gladys

Classifications

• F02D41/024

  to increase temperature of the exhaust gas treating apparatus · CPC title

• F02D41/1454

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

• F02D41/1494 Primary

  Control of sensor heater · CPC title

• G01N27/4067

  Means for heating or controlling the temperature of the solid electrolyte · CPC title

• F01N2560/20

  Sensor having heating means · CPC title