Oxygen sensor and oxygen sensor control device

Patent metadata

Field	Value
Publication number	US-9732657-B2
Application number	US-201013993734-A
Country	US
Kind code	B2
Filing date	Dec 24, 2010
Priority date	Dec 24, 2010
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

In this invention, an EMF oxygen sensor is subjected to an activation process applying unidirectional voltage between an atmosphere electrode and an exhaust electrode thereof. A control device controlling the oxygen sensor in which a voltage was applied with the atmosphere electrode being positive, additionally applies unidirectional voltage between the electrodes to make the atmosphere electrode positive, for example, when the oxygen sensor was used under an environment in which the air-fuel ratio of the internal combustion engine was rich relative to the theoretical air-fuel ratio. Conversely, a control device controlling the oxygen sensor in which a voltage was applied to make the atmosphere electrode negative, additionally applies unidirectional voltage between the electrodes to make the atmosphere electrode negative, for example, when the oxygen sensor was used under an environment in which the air-fuel ratio was lean relative to the theoretical air-fuel ratio.

First claim

The invention claimed is:

1. An oxygen sensor controller for an electromotive force-type oxygen sensor disposed in an exhaust passage of an internal combustion engine, the oxygen sensor comprising:
a solid electrolyte;
an atmosphere electrode that is disposed on one face side of the solid electrolyte and contacts with atmosphere when disposed in the exhaust passage; and
an exhaust electrode that is disposed on a face on an opposite side to the one face of the solid electrolyte and contacts with exhaust gas when disposed in the exhaust passage,
the oxygen sensor being configured to be subjected to an activation process that applies a unidirectional voltage between the atmosphere electrode and the exhaust electrode, and
the oxygen sensor controller being configured to:
apply a voltage in the same direction as the unidirectional voltage between the atmosphere electrode and the exhaust electrode in accordance with operating state of the internal combustion engine;
detect a continuation time of rich operation that is a time in which an air-fuel ratio is rich relative to a theoretical air-fuel ratio during a predetermined operation period of the internal combustion engine;
set a voltage application time period in accordance with the continuation time of rich operation; and
in accordance with the voltage application time period set in accordance with the continuation time of rich operation, apply the unidirectional voltage between the atmosphere electrode and the exhaust electrode to make the atmosphere electrode positive and make the exhaust electrode negative.

2. An oxygen sensor controller for an electromotive force-type oxygen sensor disposed in an exhaust passage of an internal combustion engine, the oxygen sensor comprising:
a solid electrolyte;
an atmosphere electrode that is disposed on one face side of the solid electrolyte and contacts with atmosphere when disposed in the exhaust passage; and
an exhaust electrode that is disposed on a face on an opposite side to the one face of the solid electrolyte and contacts with exhaust gas when disposed in the exhaust passage,
the oxygen sensor being configured to be subjected to an activation process that applies a unidirectional voltage between the atmosphere electrode and the exhaust electrode, and
the oxygen sensor controller being configured to:
apply a voltage in the same direction as the unidirectional voltage between the atmosphere electrode and the exhaust electrode in accordance with operating state of the internal combustion engine;
detect a continuation time of lean operation that is a time in which an air-fuel ratio is lean relative to a theoretical air-fuel ratio during a predetermined operation period of the internal combustion engine;
set a voltage application time period in accordance with the continuation time of lean operation; and
in accordance with the voltage application time period set in accordance with the continuation time of lean operation, apply the unidirectional voltage between the atmosphere electrode and the exhaust electrode to make the atmosphere electrode negative and make the exhaust electrode positive.

3. An oxygen sensor controller for an electromotive force-type oxygen sensor disposed in an exhaust passage of an internal combustion engine, the oxygen sensor comprising:
a solid electrolyte;
an atmosphere electrode that is disposed on one face side of the solid electrolyte and contacts with atmosphere when disposed in the exhaust passage; and
an exhaust electrode that is disposed on a face on an opposite side to the one face of the solid electrolyte and contacts with exhaust gas when disposed in the exhaust passage,
the oxygen sensor being configured to be subjected to an activation process that applies a unidirectional voltage between the atmosphere electrode and the exhaust electrode, and
the oxygen sensor controller being configured to:
apply a voltage in the same direction as the unidirectional voltage between the atmosphere electrode and the exhaust electrode in accordance with operating state of the internal combustion engine,
detect a rich operating state that is a state in which an operating state of the internal combustion engine is in a predetermined high speed and high load operating range and in which an air-fuel ratio is in a rich amount increasing range, and
when the rich operating state is detected, apply the unidirectional voltage between the atmosphere electrode and the exhaust electrode to make the atmosphere electrode positive and make the exhaust electrode negative.

4. An oxygen sensor controller for an electromotive force-type oxygen sensor disposed in an exhaust passage of an internal combustion engine, the oxygen sensor comprising:
a solid electrolyte;
an atmosphere electrode that is disposed on one face side of the solid electrolyte and contacts with atmosphere when disposed in the exhaust passage; and
an exhaust electrode that is disposed on a face on an opposite side to the one face of the solid electrolyte and contacts with exhaust gas when disposed in the exhaust passage,
the oxygen sensor being configured to be subjected to an activation process that applies a unidirectional voltage between the atmosphere electrode and the exhaust electrode, and
the oxygen sensor controller being configured to:
apply a voltage in the same direction as the unidirectional voltage between the atmosphere electrode and the exhaust electrode in accordance with operating state of the internal combustion engine;
detect when an operating state of the internal combustion engine in which the oxygen sensor is disposed is a fuel-cut operation state, and
when the fuel-cut operation state is detected, apply the unidirectional voltage between the atmosphere electrode and the exhaust electrode to make the atmosphere electrode negative and make the exhaust electrode positive.

5. The oxygen sensor controller according to claim 1 , wherein the unidirectional voltage is a voltage in a range which does not cause blackening with respect to the solid electrolyte.

6. The oxygen sensor controller according to claim 1 , wherein the oxygen sensor controller is configured to:
detect or estimate an element resistance of the oxygen sensor; and
control a size of the unidirectional voltage or an application time period of the unidirectional voltage in accordance with the element resistance.

7. The oxygen sensor controller according to claim 2 , wherein the unidirectional voltage is a voltage in a range which does not cause blackening with respect to the solid electrolyte.

8. The oxygen sensor controller according to claim 2 , wherein the oxygen sensor controller is configured to:
detect or estimate an element resistance of the oxygen sensor; and
control a size of the unidirectional voltage or an application time period of the unidirectional voltage in accordance with the element resistance.

9. The oxygen sensor controller according to claim 3 , wherein the unidirectional voltage is a voltage in a range which does not cause blackening with respect to the solid electrolyte.

10. The oxygen sensor controller according to claim 3 , wherein the oxygen sensors controller is configured to:
detect or estimate an element resistance of the oxygen sensor; and
control a size of the unidirectional voltage or an application time period of the unidirectional voltage in accordance with the element resistance.

11. The oxygen sensor controller according to claim 4 , wherein the unidirectional voltage is a voltage in a range which does not cause blackening with respect to the solid electrolyte.

12. The oxygen sensor controller according to claim 4 , wherein the oxygen sensor controller i

Assignees

• Aoki Keiichiro
• Sasaki Takanori
• Hayashita Go
• Toyota Motor Co Ltd

Inventors

• Aoki Keiichiro
• Sasaki Takanori
• Hayashita Go

Classifications

• F01N11/007 Primary

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

• F02D41/123

  the fuel injection being cut-off · CPC title

• F02D41/1476

  Biasing of the sensor · CPC title

• F02D41/1454

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

• G01N27/407 Primary

  for investigating or analysing gases {(G01N27/411 takes precedence)} · CPC title