Gas sensor control device

Patent metadata

Field	Value
Publication number	US-9518954-B2
Application number	US-26536308-A
Country	US
Kind code	B2
Filing date	Nov 5, 2008
Priority date	Nov 5, 2007
Publication date	Dec 13, 2016
Grant date	Dec 13, 2016

Abstract

A gas sensor control device for controlling a gas sensor, the gas sensor including a gas sensor element that includes a cell including a pair of electrodes and a solid electrolyte, the gas sensor control device including a circuit board connectable to the gas sensor. The circuit board has mounted thereon a voltage control unit mounted on the circuit board and configured to control a voltage developed across a pair of electrodes of the cell to a constant voltage; a temperature detecting unit mounted on the circuit board and configured to detect a temperature of the circuit board; and a voltage correcting unit mounted on the circuit board and configured to apply a correction voltage to the voltage control unit compensating for a temperature-dependent variation in the constant voltage based on the temperature detected by the temperature detecting unit.

First claim

What is claimed is:

1. A gas sensor control device for controlling a gas sensor, said gas sensor comprising a gas sensor element including a cell comprising a solid electrolyte and a pair of electrodes disposed on the solid electrolyte for detecting concentration of a specific gas component, said gas sensor control device comprising:
a circuit board electrically connectable to the gas sensor via an electrical conductor;
a voltage control unit mounted on the circuit board and configured to control a voltage developed across the pair of electrodes of the cell to a constant voltage;
a temperature detecting unit mounted on the circuit board and configured to detect a temperature of the circuit board; and
a voltage correcting unit mounted on the circuit board and configured to apply a correction voltage to the voltage control unit compensating for a temperature-dependent variation in the level of the constant voltage based on the temperature detected by the temperature detecting unit,
wherein the gas sensor element comprises a plurality of the cells including a first cell and a second cell,
wherein said gas sensor further comprises a plurality of the voltage control units comprising a first voltage control unit and a second voltage control unit connected to the first cell and the second cell, respectively, the first voltage control unit and the second voltage control unit configured to maintain the voltage developed across the pair of electrodes of the first cell and developed across the second cell to first and second constant voltages, respectively, and
wherein the voltage correcting unit is configured to apply the correction voltage to only one of the first voltage control unit and the second voltage control unit based on the temperature detected by the temperature detecting unit, the correction voltage compensating a temperature-dependent variation in a voltage difference between the voltage developed across the pair of electrodes of the first cell and the voltage developed across the pair of electrodes of the second cell, and
an inter-terminal voltage difference is maintained constant regardless of a temperature variation of the circuit board.

2. The gas sensor control device according to claim 1 ,
wherein the gas sensor element is an NO x sensor element comprising:
first, second and third solid electrolyte layers in sequential order spaced apart from one another, said first solid electrolyte being exposed to an atmosphere outside of the gas sensor element and said second and third solid electrolyte layers being laminated in the gas sensor element;
a first measurement chamber defined between the first solid electrolyte and the second solid electrolyte;
a second measurement chamber in communication with the first measurement chamber;
an oxygen concentration detecting cell comprising: a detection electrode contacting the second solid electrolyte and exposed to the first measurement chamber; and a reference electrode paired with the detection electrode and exposed to a reference atmosphere, the oxygen concentration detecting cell being configured to generate an electromotive force in response to the concentration of oxygen in the first measurement chamber;
a first pumping cell comprising: a first inner pump electrode contacting the first solid electrolyte and exposed to the first measurement chamber; and an electrode paired with the first inner pump electrode, the first pumping cell configured to pump oxygen into or out of a gas to be measured introduced into the first measurement chamber such that the electromotive force generated in the oxygen concentration detecting cell is maintained at a first constant voltage; and
a second pumping cell comprising: a second inner pump electrode contacting the third solid electrolyte and exposed to the second measurement chamber; and a second outer pump electrode paired with the second inner pump electrode and disposed outside the second measurement chamber, wherein a current flows through the second pumping cell in response to NO x concentration in the second measurement chamber when a second constant voltage is applied across the second inner pump electrode and the second outer pump electrode,
wherein the first cell and the second cell correspond to the oxygen concentration detecting cell and the second pumping cell, respectively, and
wherein the voltage correcting unit applies the correction voltage to the first voltage control unit connected to the oxygen concentration detecting cell.

3. The gas sensor control device according to claim 1 ,
wherein the gas sensor element is an NO x sensor element comprising:
a first solid electrolyte exposed to an atmosphere outside of the gas sensor element;
a second solid electrolyte layer laminated in the gas sensor element and spaced apart from the first solid electrolyte;
a first measurement chamber defined between the first solid electrolyte and the second solid electrolyte;
a second measurement chamber in communication with the first measurement chamber;
an oxygen concentration detecting cell comprising: a detection electrode contacting the first solid electrolyte and exposed to the first measurement chamber; and a reference electrode paired with the detection electrode and exposed to a reference atmosphere, the oxygen concentration detecting cell being configured to generate an electromotive force in response to the concentration of oxygen in the first measurement chamber;
a first pumping cell comprising: a first inner pump electrode contacting the first solid electrolyte and exposed to the first measurement chamber; and an electrode paired with the first inner pump electrode, the first pumping cell configured to pump oxygen into or out of a gas to be measured introduced into the first measurement chamber such that the electromotive force generated in the oxygen concentration detecting cell is maintained at a first constant voltage; and
a second pumping cell comprising: a second inner pump electrode contacting the second solid electrolyte and exposed to the second measurement chamber; and a second outer pump electrode paired with the second inner pump electrode and disposed outside the second measurement chamber, wherein a current flows through the second pumping cell in response to NO x concentration in the second measurement chamber when a second constant voltage is applied across the second inner pump electrode and the second outer pump electrode,
wherein the first cell and the second cell correspond to the oxygen concentration detecting cell and the second pumping cell, respectively, and
wherein the voltage correcting unit applies the correction voltage to the first voltage control unit connected to the oxygen concentration detecting cell.

4. The gas sensor control device according to claim 1 , wherein the gas sensor comprises a heater configured to heat the gas sensor element,
wherein the gas sensor control device further comprises a heater control unit configured to control a current supplied to the heater, and
wherein the temperature detecting unit is disposed on the circuit board closer to the voltage control unit than the heater control unit.

5. The gas sensor control device according to claim 1 , further comprising:
a storage unit in which correction values corresponding to the correction voltage are stored in association with the temperature.

6. The gas sensor control device according to claim 5 , wherein correction values are stored in the storage unit for each of predetermined temperature ranges.

Assignees

• Ishiguro Yasuhiro
• Abe Satoru
• Kobayashi Akihiro
• Sumi Takayuki
• Ngk Spark Plug Co

Inventors

• Ishiguro Yasuhiro
• Abe Satoru
• Kobayashi Akihiro
• Sumi Takayuki

Classifications

• G01N27/4175 Primary

  Calibrating or checking the analyser · CPC title