Sensor control apparatus and gas detection system

Patent metadata

Field	Value
Publication number	US-10139359-B2
Application number	US-201514965457-A
Country	US
Kind code	B2
Filing date	Dec 10, 2015
Priority date	Dec 12, 2014
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

In a sensor control apparatus of a gas detection system, a multiplexer having received an instruction from a digital computation section outputs analog signals in the order of, for example, “signal 1 , signal 2 , signal 1 , signal 3 , signal 1 , signal 4 .” By outputting the analog signals while classifying each of them as a high occurrence-frequency signal which is high in output frequency or a low occurrence-frequency signal which is low in output frequency, the multiplexer can increase the sampling frequency of signal (analog signal of Vs+-COM voltage) which is the high occurrence-frequency signal. The sensor control apparatus can increase the sampling frequency in AD conversion of signal to a digital value, while suppressing an increase in the cost of an AD conversion section.

First claim

What is claimed is:

1. A sensor control apparatus for controlling a gas sensor including a detection cell which produces an electromotive force corresponding to a particular component contained in an object gas and an oxygen pump cell which performs pumping in or pumping out of oxygen in accordance with a pump current supplied to the oxygen pump cell, the sensor control apparatus comprising:
a multiplexer configured to receive as input a plurality of analog signals, including at least the electromotive force of the detection cell, classify each of the plurality of analog signals as either a high occurrence-frequency signal or a low occurrence-frequency signal, and output the plurality of analog signals one by one in a predetermined order in an all signal output period during which all of the plurality of analog signals are output, with each high occurrence frequency signal output two or more times in the all signal output period and each low occurrence-frequency signal output once in the all signal output period;
an analog-to-digital conversion section configured to convert the plurality of analog signals output from the multiplexer to digital values, including at least a digital value of the electromotive force;
a supply control value computation section configured to digitally compute a supply control value for the pump current supplied to the oxygen pump cell on the basis of the digital value of the electromotive force; and
a digital-to-analog conversion section configured to generate the pump current supplied to the oxygen pump cell on the basis of a digital signal representing the supply control value for the pump current,
wherein, the multiplexer classifies at least the electromotive force as a high occurrence-frequency signal.

2. The sensor control apparatus according to claim 1 , wherein the multiplexer outputs the electromotive force of the detection cell as the high occurrence-frequency signal at constant intervals.

3. The sensor control apparatus according to claim 1 , wherein the multiplexer classifies a signal regarding a potential difference between a reference potential of the sensor control apparatus and a potential of at least one electrode terminal selected from two electrode terminals of the oxygen pump cell and two electrode terminals of the detection cell as a low occurrence-frequency signal.

4. The sensor control apparatus according to claim 2 , wherein the multiplexer classifies a signal regarding a potential difference between a reference potential of the sensor control apparatus and a potential of at least one electrode terminal selected from two electrode terminals of the oxygen pump cell and two electrode terminals of the detection cell as a low occurrence-frequency signal.

5. The sensor control apparatus according to claim 1 , further comprising:
a first filter section configured to digitally extract a first filter signal from the digital signal representing the supply control value for the pump current such that components of the digital signal whose frequencies are higher than a predetermined first cut-off frequency are attenuated; and
a second filter section configured to digitally extract a second filter signal from the first filter signal such that components of the first filter signal whose frequencies are higher than a predetermined second cut-off frequency are attenuated,
wherein the digital-to-analog conversion section generates the pump current supplied to the oxygen pump cell on the basis of the first filter signal, and the second filter section outputs to an external apparatus the second filter signal as a pump current signal for detection of the particular component contained in the object gas.

6. The sensor control apparatus according to claim 2 , further comprising:
a first filter section configured to digitally extract a first filter signal from the digital signal representing the supply control value for the pump current such that components of the digital signal whose frequencies are higher than a predetermined first cut-off frequency are attenuated; and
a second filter section configured to digitally extract a second filter signal from the first filter signal such that components of the first filter signal whose frequencies are higher than a predetermined second cut-off frequency are attenuated,
wherein the digital-to-analog conversion section generates the pump current supplied to the oxygen pump cell on the basis of the first filter signal, and the second filter section outputs to an external apparatus the second filter signal as a pump current signal for detection of the particular component contained in the object gas.

7. The sensor control apparatus according to claim 3 , further comprising:
a first filter section configured to digitally extract a first filter signal from the digital signal representing the supply control value for the pump current such that components of the digital signal whose frequencies are higher than a predetermined first cut-off frequency are attenuated; and
a second filter section configured to digitally extract a second filter signal from the first filter signal such that components of the first filter signal whose frequencies are higher than a predetermined second cut-off frequency are attenuated,
wherein the digital-to-analog conversion section generates the pump current supplied to the oxygen pump cell on the basis of the first filter signal, and the second filter section outputs to an external apparatus the second filter signal as a pump current signal for detection of the particular component contained in the object gas.

8. The sensor control apparatus according to claim 4 , further comprising:
a first filter section configured to digitally extract a first filter signal from the digital signal representing the supply control value for the pump current such that components of the digital signal whose frequencies are higher than a predetermined first cut-off frequency are attenuated; and
a second filter section configured to digitally extract a second filter signal from the first filter signal such that components of the first filter signal whose frequencies are higher than a predetermined second cut-off frequency are attenuated,
wherein the digital-to-analog conversion section generates the pump current supplied to the oxygen pump cell on the basis of the first filter signal, and the second filter section outputs to an external apparatus the second filter signal as a pump current signal for detection of the particular component contained in the object gas.

9. The sensor control apparatus according to claim 5 , wherein the first cut-off frequency is higher than the second cut-off frequency.

10. The sensor control apparatus according to claim 6 , wherein the first cut-off frequency is higher than the second cut-off frequency.

11. The sensor control apparatus according to claim 7 , wherein the first cut-off frequency is higher than the second cut-off frequency.

12. The sensor control apparatus according to claim 8 , wherein the first cut-off frequency is higher than the second cut-off frequency.

13. A gas detection system comprising:
a gas sensor including a detection cell which produces an electromotive force corresponding to a particular component contained in an object gas and an oxygen pump cell which performs pumping in or pumping out of oxygen in accordance with a pump current supplied to the oxygen pump cell; and
a sensor control apparatus for controlling the gas sensor, the sensor control apparatus including:
a multiplexer configured to receive as input a plurality of analog signals, including at least the electromotive force of the detection cell, classify ea

Assignees

• Ngk Spark Plug Co

Inventors

• Higuchi Yuzo
• Uemura Tomonori

Classifications

• G01N33/0036 Primary

  specially adapted to detect a particular component (physical analysis of gaseous biological material G01N33/497) · CPC title

• G01N27/045 Primary

  Circuits (measuring resistance per se G01R27/00, e.g. G01R27/22) · CPC title

• G01N27/4065

  Circuit arrangements specially adapted therefor · CPC title

• F02D41/1454

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

• F02D2041/281

  between sensors and control unit · CPC title