Sensor control apparatus, sensor control system, and sensor control method

Patent metadata

Field	Value
Publication number	US-9297778-B2
Application number	US-201213418903-A
Country	US
Kind code	B2
Filing date	Mar 13, 2012
Priority date	Mar 14, 2011
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

Abstract

A sensor control apparatus is disclosed, including a preliminary control for supplying a constant current to a second oxygen pump cell of a gas sensor for a constant period of time so as to control to a constant level the amount of oxygen pumped out from a second measurement chamber (S 40 to S 50 ). At the beginning of drive control (S 55 to S 80 ), oxygen is pumped back into the second measurement chamber. During the pumping back operation, an NO X concentration correspondence value has a large time course change and is not stable. The NO X concentration correspondence value is corrected using correction data common among gas sensors, wherein the timing for applying the correction data is adjusted by making use of an application time determined in accordance with individual differences of each gas sensor.

First claim

What is claimed is:

1. A sensor control apparatus for controlling a gas sensor including a first measurement chamber into which an object gas is introduced, a first oxygen pump cell having a first solid electrolyte layer and paired first electrodes provided on an inside and outside, respectively, of the first measurement chamber, a second measurement chamber in communication with the first measurement chamber, and a second oxygen pump cell having a second solid electrolyte layer and paired second electrodes provided on an inside and outside, respectively, of the second measurement chamber, the sensor control apparatus comprising:
a drive control section programmed to perform drive control for adjusting an oxygen concentration of the object gas introduced into the first measurement chamber by supplying an electric current to the first oxygen pump cell and for applying an operating voltage to the second oxygen pump cell;
a preliminary control section programmed to perform, before start of the drive control, preliminary control which supplies a constant current to the second oxygen pump cell over a constant period of time, to thereby control to a constant level an amount of oxygen pumped out from the second measurement chamber to outside of the second measurement chamber;
a calculation section programmed to calculate a concentration correspondence value which represents a concentration of a specific gas contained in the object gas, on the basis of the magnitude of current flowing through the second oxygen pump cell to which the operating voltage is applied after the start of the drive control;
a storage medium for storing, as correction data common among a plurality of the gas sensors, pattern data which represents a pattern of a time course change in the concentration correspondence value after the drive control is started after the preliminary control which has been set in advance is executed, which pattern data is obtained under a condition where both the preliminary control and the drive control are performed in the presence of a reference gas;
a determination section programmed to determine a timing for applying the correction data; and
a correction section programmed to correct the concentration correspondence value by applying the correction data to the concentration correspondence value at the timing determined by the determination means,
said correction data being applied when the determination section determines that a pattern of a time course change exhibited by the concentration correspondence value after the start of the drive control approximately coincides with the pattern of the time course change represented by the correction data.

2. The sensor control apparatus as claimed in claim 1 , wherein
the storage medium stores an application time which is determined for the gas sensor on an individual basis and represents a time between the start of the drive control and the timing for applying the correction data, the application time being used to apply the correction data such that the pattern of the time course change in the concentration correspondence value after the drive control is started after execution of the preliminary control, both controls being performed in the presence of the reference gas, approximately coincides with the pattern of the time course change represented by the correction data; and
the determination means determines that the timing for applying the correction data has come when the application time elapses after the start of the drive control.

3. The sensor control apparatus as claimed in claim 1 , wherein
the storage medium further stores control conditions of the sensor control apparatus which are determined for the gas sensor on an individual basis and which relate to adjustment of the amount of pumped out oxygen, the control conditions being determined such that the concentration correspondence value after the drive control is started after execution of the preliminary control, both controls being performed in the presence of the reference gas, falls within a target range; and
the preliminary control section executes the preliminary control under the control conditions.

4. The sensor control apparatus as claimed in claim 3 , wherein the control conditions include at least one of constant current and constant time determined for the gas sensor on an individual basis.

5. A sensor control system comprising a gas sensor and a sensor control apparatus as claimed in claim 1 , wherein the gas sensor is controlled by the sensor control apparatus.

6. A sensor control method which is performed in a sensor control apparatus for controlling a gas sensor including a first measurement chamber into which an object gas is introduced, a first oxygen pump cell having a first solid electrolyte layer and paired first electrodes provided on an inside and outside, respectively, of the first measurement chamber, a second measurement chamber in communication with the first measurement chamber, and a second oxygen pump cell having a second solid electrolyte layer and paired second electrodes provided on an inside and outside, respectively, of the second measurement chamber, the sensor control method comprising:
a drive control step of performing drive control for adjusting an oxygen concentration of the object gas introduced into the first measurement chamber by supplying electric current to the first oxygen pump cell and for applying an operating voltage to the second oxygen pump cell;
a preliminary control step of performing, before start of the drive control, preliminary control which supplies a constant current to the second oxygen pump cell over a constant period of time, to thereby control to a constant level an amount of oxygen pumped out from the second measurement chamber to the outside of the second measurement chamber;
a calculation step of calculating a concentration correspondence value which represents a concentration of a specific gas contained in the object gas, on the basis of the magnitude of current flowing through the second oxygen pump cell to which the operating voltage is applied after the start of the drive control;
a determination step of determining a timing for applying correction data, such that a pattern of a time course change exhibited by the concentration correspondence value after the start of the drive control approximately coincides with a pattern of a time course change represented by the correction data, the correction data being pattern data which is stored in storage means of the sensor control apparatus commonly among a plurality of the gas sensors and which represents a pattern of a time course change in the concentration correspondence value after the drive control is started after the preliminary control which has been set in advance is executed, which pattern data is obtained under a combination where both the preliminary control and the drive control are performed in the presence of the reference gas;
and
a correction step of correcting the concentration correspondence value by applying the correction data to the concentration correspondence value on the basis of the timing determined by the determination step.

7. A sensor control method as claimed in claim 6 , wherein
the storage means stores an application time which is individually determined for the gas sensor and represents a time between the start of the drive control and the timing for applying the correction data, the application time being used to apply the correction data such that the pattern of the time course change in the concentration correspondence value after the drive control is started after execution of the preliminary control, both controls being performed in the presence of the reference gas, approximately coincides with the pattern of the t

Assignees

• Onogi Hirotaka
• Kato Kenji
• Teramoto Satoshi
• Ngk Spark Plug Co

Inventors

• Onogi Hirotaka
• Kato Kenji
• Teramoto Satoshi

Classifications

• G01N27/4074 Primary

  for detection of gases other than oxygen · CPC title