Control apparatus

Patent metadata

Field	Value
Publication number	US-11384675-B2
Application number	US-201816608243-A
Country	US
Kind code	B2
Filing date	Mar 15, 2018
Priority date	Apr 26, 2017
Publication date	Jul 12, 2022
Grant date	Jul 12, 2022

Abstract

The control section of a control apparatus executes a first control for operating a voltage application section such as to cause a current to flow in a first direction through a gas sensor in a first period, and a second control for operating the voltage application section such as to cause a current to flow in a second direction, opposite to the first direction, through the gas sensor in a second period. The control apparatus changes the length of at least one of the first period and the second period based on a comparison between a first measurement value, which is the absolute value of a value measured by a sweep measurement section during execution of the first control, and a second measurement value, which is the absolute value of a value measured by the sweep measurement section during execution of the second control.

First claim

The invention claimed is:

1. A control apparatus for a gas sensor that measures a gas concentration, the control apparatus comprising:
a voltage application section that applies a voltage to the gas sensor, for measuring the impedance of the gas sensor;
a control section that controls the operation of the voltage application section; and
a sweep measurement section that measures at least one of a current that flows in the gas sensor and a voltage that is applied to the gas sensor, wherein:
the control section performs
a first control which, during a first period, operates the voltage application section such that a current flows through the gas sensor in a first direction, and
a second control which, during a second period, operates the voltage application section such that a current flows through the gas sensor in a second direction that is opposite the first direction; and

the control section changes the length of at least one of the first period and the second period based on a comparison between a first measurement value, which is the absolute value of a value measured by the sweep measurement section during execution of the first control, and a second measurement value, which is the absolute value of a value measured by the sweep measurement section during execution of the second control.

2. The control apparatus according to claim 1 , wherein:
in response to the first measurement value being greater than the second measurement value, the control section changes the length of the second period to become longer; and
in response to the first measurement value being less than the second measurement value, the control section changes the length of the first period to become longer.

3. The control apparatus according to claim 1 , wherein:
in response to the first measurement value being greater than the second measurement value, the control section changes the length of the first period to become shorter; and
in response to the first measurement value being less than the second measurement value, the control section changes the length of the second period to become shorter.

4. The control apparatus according to claim 1 , wherein:
in response to the first period or the second period being changed to become shorter, the sweep measurement section changes the timing at which measurement is performed.

5. The control apparatus according to claim 1 , wherein:
the application of a voltage by the voltage application section and the measurement of current or of voltage by the sweep measurement section are executed repetitively; and
the control section changes the length of at least one of the first period and the second period in the next repetition, based on a comparison between the first measurement value and the second measurement value that are measured in the current repetition.

6. The control apparatus according to claim 1 , further comprising:
a mask setting section that sets, as a period that includes the first period and the second period, a mask period in which the measurement of the gas concentration by the gas sensor is temporarily halted,
wherein the mask setting section changes the length of the mask period, in response to the length of at least one of the first period and the second period being changed.

7. The control apparatus according to claim 1 , wherein:
the control section changes the length of at least one of the first period and the second period in order to effect coincidence between the respective absolute values of the time integral value of a value measured by the sweep measurement section in the first period and the time integral value of a value measured by the sweep measurement section in the second period.

8. The control apparatus according to claim 1 , wherein:
the control section changes the length of at least one of the first period and the second period such as to effect coincidence between a prescribed set value and at least one of the time integral value of a value measured by the sweep measurement section in the first period and the time integral value of a value measured by the sweep measurement section in the second period.

9. The control apparatus according to claim 1 , further comprising:
a heater that heats the gas sensor; and
a sensor temperature estimation section that estimates the temperature of the gas sensor based on the impedance of the gas sensor,
wherein after the temperature which is estimated by the sensor temperature estimation section exceeds a prescribed temperature, the control section commences processing for changing the length of at least one of the first period and the second period.

10. The control apparatus according to claim 1 , further comprising:
a heater that heats the gas sensor, wherein
after a prescribed interval has elapsed since the commencement of energization of the heater, the control section commences processing for changing the length of at least one of the first period and the second period.

11. The control apparatus according to claim 1 wherein:
after application of a voltage by the voltage application section and measurement of current or of voltage by the sweep measurement section have each been repeated a plurality of times, the control section changes the length of at least one of the first period and the second period in next and subsequent iterations, based on a comparison between the average value of the first measurement values and the average value of the second measurement values.

12. The control apparatus according to claim 11 , wherein:
in response to the average value of the first measurement values being greater than the average value of the second measurement values, the control section changes the length of the second period to become longer, in next and subsequent iterations; and
in response to the average value of the first measurement values being less than the average value of the second measurement values, the control section changes the length of the first period to become longer, in next and subsequent iterations.

13. The control apparatus according to claim 11 , wherein:
in response to the average value of the first measurement values being greater than the average value of the second measurement values, the control section changes the length of the first period to become shorter, in next and subsequent iterations; and
in response to the average value of the first measurement values being less than the average value of the second measurement values, the control section changes the length of the second period to become shorter, in next and subsequent iterations.

14. The control apparatus according to claim 1 , further comprising:
a temperature measurement section,
wherein in response to the temperature measured by the temperature measurement section being changed, the control section executes processing for changing the length of at least one of the first period and the second period.

15. The control apparatus according to claim 1 , wherein:
the control section executes processing for changing the length of at least one of the first period and the second period each time a prescribed interval has elapsed.

16. The control apparatus according to claim 1 , wherein:
the application of a voltage by the voltage application section and the measurement of current or of voltage by the sweep measurement section are executed repetitively; and
the control section executes processing for changing the length of at least one of the first period and the second period each time that the number of times of applying voltage by the voltage application section has reached a

Assignees

• Denso Corp
• Mazda Motor

Inventors

• Matsumoto Tooru
• Akimoto Katsuhide
• Masuko Takahito
• Takagi Keita
• Ito Tatsuhiro
• Sato Yuki
• Teramoto Ryo
• Nishio Takafumi

Classifications

• G01N27/62

  by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode · CPC title

• F01N11/007 Primary

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

• G05B23/0205

  by means of a monitoring system capable of detecting and responding to faults · CPC title

• G01N27/02

  by investigating impedance · CPC title

• G01N27/4065

  Circuit arrangements specially adapted therefor · CPC title