WO2020053982A1 - Gas detection device - Google Patents

Gas detection device Download PDF

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Publication number
WO2020053982A1
WO2020053982A1 PCT/JP2018/033775 JP2018033775W WO2020053982A1 WO 2020053982 A1 WO2020053982 A1 WO 2020053982A1 JP 2018033775 W JP2018033775 W JP 2018033775W WO 2020053982 A1 WO2020053982 A1 WO 2020053982A1
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WIPO (PCT)
Prior art keywords
temperature
detection
heating
gas
gas detection
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PCT/JP2018/033775
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French (fr)
Japanese (ja)
Inventor
野中篤
大西久男
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大阪瓦斯株式会社
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Application filed by 大阪瓦斯株式会社 filed Critical 大阪瓦斯株式会社
Priority to PCT/JP2018/033775 priority Critical patent/WO2020053982A1/en
Publication of WO2020053982A1 publication Critical patent/WO2020053982A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid

Definitions

  • the present invention relates to a gas detection device.
  • a gas detection part whose characteristics change due to contact with the detection target gas, a heater part that heats the gas detection part, a heating control unit that controls heating by the heater part, and a detection target gas that measures characteristics of the gas detection part.
  • a gas detection device having a gas detection unit for detecting the pressure.
  • the heating control section controls the heating by the heater portion to heat the gas detection portion to an appropriate temperature according to the type of the gas to be detected, and maintain the temperature.
  • the detection target gas is detected based on the characteristics (electric resistance value, voltage value, etc.) of the gas detection site in.
  • the heater element is maintained at a high temperature (300 to 500 ° C.) to clean the sensor element, and thereafter, the CO can be detected at a low temperature (about 60 to 200 ° C.).
  • the sensor can be operated as a so-called methane / CO one sensor that performs not only cleaning but also methane detection at a high temperature and performs CO detection at a low temperature.
  • the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a gas detection device in which the influence of the ambient temperature is suppressed to reduce variation in CO sensitivity.
  • the characteristic configuration of the gas detection device for achieving the above object is as follows: a gas detection portion whose characteristics are changed by contact with a detection target gas; a heater portion that heats the gas detection portion; and heating by the heater portion.
  • a gas detection device having a heating control unit, a temperature detection unit that detects a temperature of the gas detection site or its surroundings, and a gas detection unit that measures a characteristic of the gas detection site and detects a detection target gas.
  • the heating control section performs a carbon monoxide detection heating operation of controlling the heating by the heater section based on the temperature detected by the temperature detection section and heating the gas detection section to a carbon monoxide detection temperature.
  • the temperature for detecting carbon monoxide is 60 ° C. or more and 200 ° C. or less.
  • the heating operation for detecting carbon monoxide is performed by controlling the heating by the heater portion based on the temperature detected by the temperature detecting portion, and the heating operation is performed regardless of the temperature of the gas detection portion or its surroundings.
  • the temperature of the gas detection site constant at all times, the amount of adsorption (surface coverage) of CO on the surface of the gas detection site (tin oxide) at the time of CO detection by Low drive can be kept constant, Variations in CO sensitivity due to variations in the amount of CO adsorbed can be suppressed.
  • the temperature for detecting carbon monoxide is 60 ° C. or more and 200 ° C. or less, significant sensitivity is exhibited for carbon monoxide, and it has been confirmed by experiments that carbon monoxide can be detected.
  • the gas detection device according to the present invention be configured so that the temperature for detecting carbon monoxide is 100 ° C. or higher and 160 ° C. or lower, because higher CO sensitivity can be exhibited.
  • ⁇ Configuration 3> Another characteristic configuration of the gas detection device according to the present invention is that, before performing the carbon monoxide detection heating operation, the heating control unit controls heating by the heater unit to set the gas detection site to carbon monoxide. It is configured to perform a carbon monoxide detection preparation heating operation of heating to the detection preparation temperature, wherein the carbon monoxide detection preparation temperature is higher than the installation environment temperature and lower than the carbon monoxide detection temperature.
  • the temperature of the installation environment becomes the temperature during Off, but the temperature varies depending on the surrounding environment. And the CO sensitivity varies.
  • the temperature of the gas detection portion during heating is maintained substantially constant regardless of the temperature of the gas detection portion or its surroundings. Therefore, the amount of adsorbed CO (surface coverage) on the surface of the detection layer (tin oxide) at the time of detecting CO in the low drive can be kept almost constant, and the variation in the CO sensitivity due to the variation in the amount of adsorbed CO is greatly reduced. Can be suppressed.
  • ⁇ Configuration 4> Another characteristic configuration of the gas detection device according to the present invention is that the heating control unit performs heating by the heater part based on the temperature detected by the temperature detection unit when performing the heating operation for preparing carbon monoxide detection. In that it is configured to control
  • the heating operation for preparing carbon monoxide detection is performed by controlling the heating by the heater portion based on the temperature detected by the temperature detection portion.
  • the temperature of the gas detection part at the time of heating is always kept constant. Then, the variation of the adsorption amount change behavior after heating due to the variation of the CO adsorption amount at the start of the carbon monoxide detection heating operation is suppressed, and the adsorption amount after the lapse of a predetermined time is reduced when the CO concentration is the same.
  • the adsorption amount at the heating temperature to reach equilibrium before detection, and even in a transient state before the adsorption amount reaches equilibrium, the adsorption amount depends on the CO concentration. Therefore, detection in a transient state (heating for a short time) before reaching equilibrium is possible. Therefore, in addition to suppressing the variation in the CO sensitivity, power saving can be achieved.
  • the heating control unit is configured to perform a heating operation for cleaning to control heating by the heater unit and heat the gas detection unit to a surface cleaning temperature, and the cleaning temperature Is 300 ° C. or more, it is possible to suppress the variation in the CO sensitivity due to the surrounding environment, which is more preferable.
  • FIG. 2 is a schematic diagram showing an outline of a gas detection device. Is a graph showing the relationship between ambient temperature and CO sensitivity. Is a graph showing the relationship between ambient temperature and CO sensitivity.
  • FIG. 2 is a schematic diagram showing a structure of a gas detection device.
  • FIG. 2 is a schematic diagram showing a structure of a gas detection device.
  • the gas detection device 100 includes a sensor element 20, a heating control unit 12, a gas detection unit 13, and a temperature detection unit 14.
  • the sensor element 20 has a gas detection layer 10 (one example of a gas detection part), a catalyst layer 11, and a heater layer 6 (one example of a heater part).
  • the gas detection device 100 heats the gas detection layer 10 to an appropriate temperature according to the type of the gas to be detected by energizing the heater layer 6 by the heating control unit 12, and maintains the temperature.
  • the detection target gas is detected on the basis of the characteristics (electric resistance value, voltage value, etc.) of the gas detection layer 10 in. In the present embodiment, carbon monoxide is assumed as the detection target gas.
  • the catalyst layer 11 is heated by the heater layer 6 to a high temperature, burns an active (combusting) gas at that temperature, and permeates and diffuses a combustible gas inactive at that temperature to the gas detection layer 10. Let it reach. Thereby, by appropriately controlling the heating temperature, the detection accuracy of combustible gas (for example, CH 4 (methane), C 3 H 8 (propane), etc.) is improved. In other words, when detecting a combustible gas such as methane, the catalyst layer 11 burns a reducing gas (a non-detection target gas) such as a hydrogen gas and an alcohol gas other than the detection target gas and causes the gas detection layer 10 to burn the same.
  • a reducing gas a non-detection target gas
  • the sensor element 20 has a diaphragm structure in which an end of the support layer 5 is supported on the silicon substrate 1.
  • the support layer 5 is formed by sequentially laminating the thermal oxide film 2, the Si 3 N 4 film 3, and the SiO 2 film 4.
  • a heater layer 6 is formed on the support layer 5, an insulating layer 7 is formed so as to cover the entire heater layer 6, a pair of bonding layers 8 is formed on the insulating layer 7, and An electrode layer 9 is formed.
  • the heater layer 6 generates heat by energization and heats the gas detection layer 10 and the catalyst layer 11.
  • the sensor element 20 may have a bridge structure, and the heater layer 6 may also serve as an electrode.
  • the gas detection layer 10 is formed between the pair of electrode layers 9 on the insulating layer 7.
  • the gas detection layer 10 is a semiconductor layer containing a metal oxide as a main component.
  • a mixture containing tin oxide (SnO 2 ) as a main component is used as the gas detection layer 10.
  • the electric resistance of the gas detection layer 10 changes due to contact with the gas to be detected.
  • the catalyst layer 11 is formed on the gas detection layer 10 so as to cover the gas detection layer 10.
  • the catalyst layer 11 is configured by supporting a catalyst metal on a carrier mainly composed of a metal oxide. Specifically, it is formed by bonding metal oxides supporting a catalyst metal to each other via a binder.
  • the gas detection layer 10 may be a thin film having a thickness of about 0.2 to 1.6 ⁇ m or a film (thick film) having a thickness exceeding 1.6 ⁇ m.
  • an interference gas (a reducing gas such as ethanol or H 2 (hydrogen) or other miscellaneous gas) that may cause a false detection when detecting a detection target gas is used.
  • a metal that can be a catalyst that can be removed by oxidation is used.
  • the catalyst metal palladium (Pd), platinum (Pt), rhodium (Rh), iridium (Ir), or the like can be used. In the present embodiment, at least one of palladium, platinum, iridium, and rhodium is used. Is used.
  • Alumina (Al 2 O 3 ), zirconium oxide (ZrO 2 ), yttrium oxide (Y 2 O 3 ), cerium oxide (CeO 2 ), lanthanum oxide (La 2 O 3 ), oxidized Titanium (TiO 2 ), hafnium oxide (HfO 2 ), niobium oxide (Nb 2 O 5 ), or tantalum oxide (Ta 2 O 5 ) can be used.
  • binder for binding the carrier fine powder of a metal oxide, for example, zirconium oxide, silica fine powder, silica sol, magnesia and the like can be used. If a small amount is used as a binder, alumina fine powder or alumina sol can be used as long as the function of the catalyst layer 11 is not hindered.
  • Each of the above-mentioned catalyst metals, metal oxides as carriers and binders may be used alone or in combination of two or more.
  • the amount of the catalyst metal contained in the catalyst layer 11 is preferably from 0.3 to 9% by mass with respect to the total mass of the catalyst metal and the carrier, and more preferably with respect to the total mass of the catalyst metal and the carrier. Is preferably 0.5% by mass to 6% by mass.
  • the heating control unit 12 performs a heating operation for energizing the heater layer 6 (operation for heating the gas detection site by the heater site) and a non-heating operation for not energizing the heater layer 6 (stops heating the gas detection site for the heater site). (Non-heating operation).
  • the heating control unit 12 is configured to change the temperature of the heater layer 6, and is configured to be able to heat the temperature of the heater layer 6 to an arbitrary set temperature.
  • the heating control unit 12 receives power supply from a power source such as a battery (not shown), supplies electricity to the heater layer 6 of the sensor element 20, and heats the sensor element 20.
  • the heating temperature that is, the temperature reached by the gas detection layer 10 and the catalyst layer 11 is controlled, for example, by changing the voltage applied to the heater layer 6.
  • the gas detection unit 13 measures the characteristics of the gas detection layer 10 and detects the detection target gas.
  • the gas detection unit 13 measures the resistance value of the gas detection layer 10 by measuring the electric resistance value (electrical characteristic) between the pair of electrode layers 9, and detects the gas to be detected from the change. The concentration of is detected.
  • the temperature detector 14 detects the temperature of the gas detection layer 10 or its surroundings (the temperature around the gas detecting device 100). Specifically, the temperature detection unit 14 is a temperature sensor such as a thermistor. Further, by measuring the resistance value of the heater layer 6, the temperature of the heater layer 6 (substantially equivalent to the temperature of the gas detection layer 10) can be detected. The temperature detected by the temperature detection unit 14 (hereinafter, sometimes referred to as “ambient temperature”) is sent to the heating control unit 12.
  • the operation of the gas detection device 100 configured as described above when detecting a detection target gas will be described.
  • a heating operation for detecting carbon monoxide and a heating operation for cleaning are performed.
  • the heating control unit 12 controls the heating by the heater layer 6 (heater portion) based on the temperature (ambient temperature) detected by the temperature detecting unit 14 to thereby control the gas detection layer 10 (gas detection). This is an operation of heating the catalyst portion 11) and the catalyst layer 11 (catalyst portion) to the temperature for detecting carbon monoxide.
  • the temperature for detecting carbon monoxide is a predetermined temperature of 100 ° C. or more and 160 ° C. or less. For example, the temperature for detecting carbon monoxide is 150 ° C.
  • the heating control unit 12 controls the energization of the heater layer 6 to bring the gas detection layer 10 and the catalyst layer 11 to the temperature for detecting carbon monoxide, and reduce the temperature for 0.05 to 10 seconds. Hold.
  • the gas detection unit 13 measures the resistance value of the gas detection layer 10 and detects the concentration of CO (carbon monoxide) from the value.
  • the power supply to the heater layer 6 by the heating control unit 12 is performed based on the ambient temperature detected by the temperature detection unit 14.
  • the heating control unit 12 controls the heater drive voltage VH applied to the heater layer 6 based on the surrounding temperature.
  • the surrounding temperature of 20 ° C. as a reference temperature
  • the heater driving voltage VH is set relatively low when the surrounding temperature is high
  • the heater driving voltage VH is set relatively high when the surrounding temperature is low. That is, with the ambient temperature of 20 ° C. as the reference temperature, the power for driving the heater is controlled to be relatively low when the ambient temperature is high, and the power for driving the heater is relatively high when the peripheral temperature is low.
  • the temperature of the gas detection layer 10 is controlled to be constant regardless of the surrounding temperature.
  • the heating operation for detecting carbon monoxide is performed by controlling the heating by the heater portion based on the ambient temperature, and the temperature is always kept constant regardless of the ambient temperature.
  • the amount of adsorbed CO (surface coverage) on the surface of the detection layer (tin oxide) at the time of detecting CO in low drive can be kept constant, and the variation in CO sensitivity due to the variation in the amount of adsorbed CO can be suppressed. .
  • the heating control unit 12 controls the heating by the heater layer 6 (heater portion) based on the ambient temperature to clean the surface of the gas detection layer 10 (gas detection portion) and the catalyst layer 11 (catalyst portion). This is an operation of heating to the use temperature and heating and removing the surface adsorbed matter (moisture, dirt, etc.) of the gas detection layer 10 that cannot be completely removed by the Low drive.
  • the surface cleaning temperature is a predetermined temperature of 300 ° C. or more and 500 ° C. or less. For example, the surface cleaning temperature is 400 ° C.
  • the heating control unit 12 controls the energization of the heater layer 6 so that the gas detection layer 10 and the catalyst layer 11 are set to the surface cleaning temperature, and the temperature is set for 0.05 to 0.5 seconds. Hold.
  • the surface adsorbed matter of the gas detection layer 10 such as moisture is removed and the surface is cleaned, and the fluctuation of the CO sensitivity due to the contamination of the surface due to the surrounding environment is suppressed.
  • the power supply to the heater layer 6 by the heating control unit 12 is performed based on the ambient temperature detected by the temperature detection unit 14.
  • the heating control unit 12 controls the heater drive voltage VH applied to the heater layer 6 based on the surrounding temperature.
  • the surrounding temperature For example, with the surrounding temperature of 20 ° C. as a reference temperature, the heater driving voltage VH is set relatively low when the surrounding temperature is high, and the heater driving voltage VH is set relatively high when the surrounding temperature is low. That is, with the ambient temperature of 20 ° C. as the reference temperature, the power for driving the heater is controlled to be relatively low when the ambient temperature is high, and the power for driving the heater is relatively high when the peripheral temperature is low. Is controlled as follows.
  • the heating operation for detecting carbon monoxide and the heating operation for cleaning are repeatedly performed with a pause operation (an operation of stopping power supply to the heater layer 6).
  • the time of each operation can be set and changed as appropriate, and the pause operation can be omitted.
  • the execution frequency of the heating operation for detecting carbon monoxide and the heating operation for cleaning may be the same or different.
  • the frequency of the cleaning operation may be reduced in accordance with the use environment, such as configuring the gas detection device 100 to perform the heating operation for cleaning once each time the heating operation for carbon monoxide detection is performed five times.
  • not only surface cleaning but also methane detection may be performed during the heating operation for cleaning.
  • the gas detection unit 13 measures the resistance value of the gas detection layer 10 during the heating operation for cleaning the surface, and detects the methane concentration from the measured value.
  • FIG. 2 shows the ambient temperature dependence of the CO sensitivity in the heating operation for detecting carbon monoxide when the heater driving power is controlled based on the ambient temperature (Example 1) and when it is not performed (Comparative Example). This is the result.
  • the heater driving method includes a cleaning heating operation (400 ° C., 0.2 seconds), a pause operation (5 seconds), a carbon monoxide detection heating operation (150 ° C., 0.5 seconds), and a pause operation (54. 3 seconds), and the measurement of the CO sensitivity was performed in an environment with a CO concentration of 300 ppm while changing the ambient temperature from 0 ° C. to 50 ° C. The measurement of the CO sensitivity was performed 0.5 seconds after the start of the heating operation for detecting carbon monoxide.
  • the graph of FIG. 2 shows the CO sensitivity at an ambient temperature of 20 ° C. as 1.
  • Example 1 the CO sensitivity decreased as the ambient temperature increased.
  • Example 1 the CO sensitivity did not change even when the ambient temperature changed. From the above results, it was shown that by controlling the heater drive power based on the ambient temperature, the change in the CO sensitivity due to the ambient temperature was suppressed.
  • the heating by the heater layer 6 is controlled to perform the gas detection layer 10 (gas detection portion). And an operation of heating the catalyst layer 11 (catalyst portion) to a temperature for preparing carbon monoxide detection.
  • the carbon monoxide detection preparation temperature is a predetermined temperature that is higher than the installation environment temperature and lower than the carbon monoxide detection temperature. For example, the temperature for preparing carbon monoxide detection is 50 ° C.
  • the heating control unit 12 controls the energization of the heater layer 6 so that the gas detection layer 10 and the catalyst layer 11 are set to the temperature for preparing carbon monoxide detection, and the temperature is set to 0.05 to 20 seconds. Hold. For example, hold for 5 seconds.
  • the execution frequency of the heating operation for carbon monoxide detection and the heating operation for cleaning may be the same or different, but the heating operation for carbon monoxide detection preparation is Always perform immediately before the heating operation for detecting carbon monoxide. Further, not only surface cleaning but also methane detection may be performed during the heating operation for cleaning.
  • the power supply to the heater layer 6 by the heating control unit 12 may be performed based on the ambient temperature detected by the temperature detection unit 14.
  • the heating control unit 12 controls the heater drive voltage VH applied to the heater layer 6 based on the surrounding temperature. For example, with the surrounding temperature of 20 ° C. as a reference temperature, the heater driving voltage VH is set relatively low when the surrounding temperature is high, and the heater driving voltage VH is set relatively high when the surrounding temperature is low. That is, with the ambient temperature of 20 ° C. as the reference temperature, the power for driving the heater is controlled to be relatively low when the ambient temperature is high, and the power for driving the heater is relatively high when the peripheral temperature is low. Is controlled as follows.
  • the heating operation for detecting carbon monoxide is performed immediately after the heating operation for preparing for detecting carbon monoxide is completed.
  • the installation environment temperature is maintained during the off period, but the temperature fluctuates depending on the surrounding environment. Therefore, the amount of CO adsorbed on the detection layer surface during CO detection (depending on the temperature) (The amount of adsorption fluctuates), and the CO sensitivity varies.
  • the amount of adsorbed CO (surface coverage) on the surface of the detection layer (tin oxide) at the time of detecting CO in Low drive can be kept constant, and the amount of adsorbed CO Can be suppressed from varying the CO sensitivity due to the above-mentioned variation.
  • the heating operation for preparing carbon monoxide detection is performed by controlling the heating by the heater portion based on the ambient temperature, the temperature is always kept constant regardless of the ambient temperature. Then, since the amount of CO adsorbed at the start of the heating operation for detecting carbon monoxide does not depend on the temperature, but is determined only by the CO concentration, the behavior of changing the adsorbed amount after heating becomes constant depending on the CO concentration.
  • the change in the amount of adsorption at a predetermined time before reaching the adsorption equilibrium is constant, and the amount of adsorption by the heating operation for carbon monoxide detection reaches equilibrium (the adsorption amount is stable). No need to detect after waiting until), and even in the transient state before the adsorption amount reaches equilibrium, the adsorption amount depends on the CO concentration. Can be detected. Therefore, power saving is also possible.
  • FIG. 3 shows the case where the heater driving power is controlled based on the ambient temperature in the heating operation for detecting carbon monoxide (Example 2), and the heating for preparing for detecting carbon monoxide (the heater portion is controlled based on the ambient temperature). It is the result of measuring the ambient temperature dependency of the CO sensitivity in the case of also performing the (control of heating) operation (Example 3).
  • the heater driving method includes a heating operation for cleaning (400 ° C., 0.2 seconds), a heating operation for carbon monoxide detection preparation (Examples 3 and 5 seconds) or a pause operation (Examples 2 and 5 seconds), carbon monoxide.
  • the heating operation for detection 150 ° C., 0.1 second
  • the pause operation (54.7 seconds) are repeated, and the measurement of the CO sensitivity is performed 0.1 second after the start of the heating operation for carbon monoxide detection.
  • the test was performed by changing the ambient temperature to 0 ° C., 20 ° C., and 50 ° C. under the environment.
  • the graph of FIG. 3 shows the CO sensitivity at an ambient temperature of 20 ° C. as 1. It is known that it takes 0.2 seconds or more for the CO adsorption amount to reach equilibrium after the heating operation for detecting carbon monoxide.
  • Example 2 the CO sensitivity decreased as the ambient temperature increased. This is because the amount of CO adsorbed on the surface of the detection layer (tin oxide) at the start of the heating operation for detecting carbon monoxide varies depending on the ambient temperature. The amount of adsorption varies 0.1 seconds after the start of the heating operation for detecting carbon monoxide (transient state before the amount of adsorbed CO reaches equilibrium), and the amount of adsorption also varies depending on the ambient temperature even at the same CO concentration. it is conceivable that. On the other hand, in Example 3, the CO sensitivity did not change even when the ambient temperature changed.
  • the amount of adsorbed CO on the surface of the detection layer (tin oxide) at the start of the heating operation for detecting carbon monoxide is constant regardless of the ambient temperature, so that 0.1 seconds after the start of the heating operation for detecting carbon monoxide. It is considered that the amount of adsorbed CO at the time is also constant regardless of the ambient temperature.
  • the heating operation for preparing carbon monoxide detection is performed without controlling the heating by the heater portion based on the ambient temperature, the variation in the CO sensitivity due to the ambient temperature is suppressed as compared with the second embodiment. That has been confirmed.
  • Table 1 shows the results of comparing the CO sensitivity after driving in high humidity (20 ° C. 90% RH) for 100 hours with the frequency of the heating operation for cleaning.
  • the heater driving method includes a heating operation for cleaning (400 ° C., 0.2 seconds), a heating operation for carbon monoxide detection preparation (5 seconds), a heating operation for carbon monoxide detection (150 ° C., 0.1 seconds), a pause. Basically, the operation (54.7 seconds) is repeated as one cycle.
  • ⁇ a> A cleaning heating operation is performed every cycle
  • ⁇ b> A cleaning heating operation is performed once every five cycles
  • ⁇ c> Cleaning is performed.
  • the CO sensitivity is measured 0.1 seconds after the start of the heating operation for detecting carbon monoxide, and is measured immediately after the start of driving in a high humidity environment (only at the initial stage) and after driving for 24 hours in an environment with a CO concentration of 300 ppm (only during measurement) Then, the sensitivity after driving for 100 hours when the initial sensitivity was set to 1 was determined.
  • Surface contamination detection is a method of detecting that the output value in the air atmosphere during the carbon monoxide detection heating operation changes (lower resistance) due to surface contamination (moisture adsorption, dirt, etc.).
  • the structure of the gas detection device 100 is a so-called substrate type shown in FIG. 1, but other structures are also possible.
  • a structure in which the insulating layer 7 covering the heater layer 6 is not provided and the heater layer 6 also functions as the electrode layer 9 is also possible.
  • a structure in which a gas detection portion 23 made of an oxide semiconductor is formed around a coil 22 of an electrode wire 21 serving as an electrode and a heater portion, and a catalyst layer 24 is formed around the gas detection portion 23. is also possible. Further, as shown in FIG.
  • another electrode 33 is disposed at the center of the coil 32 of the electrode wire 31 serving also as an electrode and a heater portion, and a gas detection portion 34 made of an oxide semiconductor is formed around the coil 32.
  • a structure in which the catalyst layer 35 is formed and the catalyst layer 35 is formed therearound is also possible.
  • the heating operation for preparing carbon monoxide detection was performed immediately after the heating operation for cleaning.
  • the heating operation for preparing carbon monoxide detection was performed after a pause operation after the heating operation for cleaning. May be performed.
  • heater layer (heater part) 10 Gas detection layer (gas detection site) 11: catalyst layer (catalyst site) 12: heating controller 13: gas detector 14: temperature detector 21: electrode wire (heater part) 23: gas detection site 24: catalyst layer (catalyst site) 31: Electrode wire (heater part) 34: gas detection part 35: catalyst layer (catalyst part) 100: Gas detector

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Abstract

Provided is a gas detection device with enhanced catalyst region performance and enhanced sensitivity to both methane and CO. This gas detection device 100 comprises: a gas detection layer 10, a heater layer 6, a heating control unit 12 for controlling heating by the heater layer 6, a gas detection unit 13 for detecting a gas to be detected by measuring a characteristic of the gas detection layer 10, and a temperature detection unit 14 for detecting an ambient temperature. By controlling the heating by the heater layer 6 on the basis of the temperature detected by the temperature detection unit 14, the heating control unit 12 carries out a heating operation for carbon monoxide detection in which the gas detection layer 10 and a catalyst layer 11 are heated to a temperature for carbon monoxide detection. The temperature for carbon monoxide detection is from 60°C to 200°C.

Description

ガス検知装置Gas detector
　本発明はガス検知装置に関する。 The present invention relates to a gas detection device.
　検出対象ガスとの接触により特性が変化するガス検知部位と、ガス検知部位を加熱するヒータ部位と、ヒータ部位による加熱を制御する加熱制御部と、ガス検知部位の特性を測定して検出対象ガスを検出するガス検出部とを有するガス検知装置が知られている。このようなガス検知装置においては、加熱制御部によりヒータ部位による加熱を制御することにより、ガス検知部位を検出対象ガスの種類に応じた適切な温度にまで加熱して、この温度を保持した状態におけるガス検知部位の特性（電気抵抗値、電圧値など）に基づいて検出対象ガスを検出する。 A gas detection part whose characteristics change due to contact with the detection target gas, a heater part that heats the gas detection part, a heating control unit that controls heating by the heater part, and a detection target gas that measures characteristics of the gas detection part. There is known a gas detection device having a gas detection unit for detecting the pressure. In such a gas detection device, the heating control section controls the heating by the heater portion to heat the gas detection portion to an appropriate temperature according to the type of the gas to be detected, and maintain the temperature. The detection target gas is detected based on the characteristics (electric resistance value, voltage value, etc.) of the gas detection site in.
　特許文献１のガス検知装置では、ヒータ部位を高温（３００～５００℃）に保持してセンサ素子をクリーニングし、その後、低温（約６０～２００℃）に保持してＣＯを検知することができる。また、高温に保持してクリーニングのみならずメタン検知も行い、低温の状態でＣＯ検知を行ういわゆるメタン／ＣＯワンセンサとして動作させることもできる。 In the gas detection device of Patent Document 1, the heater element is maintained at a high temperature (300 to 500 ° C.) to clean the sensor element, and thereafter, the CO can be detected at a low temperature (about 60 to 200 ° C.). . Further, the sensor can be operated as a so-called methane / CO one sensor that performs not only cleaning but also methane detection at a high temperature and performs CO detection at a low temperature.
特開２０１３－１９０２３２号公報JP 2013-190232 A
　省電力を目的として間欠駆動にてヒータ部位による加熱を制御してＣＯを検知する場合、高温でガス検知部位の表面をクリーニングし、その後休止し、低温でＣＯを検知する、Ｈｉｇｈ－Ｏｆｆ－Ｌｏｗ駆動が一般的である。従来、Ｌｏｗ駆動時には、周囲温度に関係なくヒータ部位に一定の電圧を印加している。すると、ガス検知部位の表面温度は、周囲温度に依存して変動するが、ＣＯの吸着量（表面被覆率）は温度によって異なることから、ガス検知部位（酸化スズ）表面におけるＣＯの吸着量に差が生じて同じＣＯ濃度であっても周囲温度によってＣＯ感度がばらつく原因となる。 When CO is detected by controlling the heating by the heater part by intermittent driving for the purpose of power saving, the surface of the gas detection part is cleaned at a high temperature, then paused, and the CO is detected at a low temperature. High-Off-Low Driving is common. Conventionally, at the time of Low drive, a constant voltage is applied to the heater portion regardless of the ambient temperature. Then, the surface temperature of the gas detection site fluctuates depending on the ambient temperature, but since the amount of adsorbed CO (surface coverage) varies depending on the temperature, the amount of CO adsorbed on the surface of the gas detection site (tin oxide) varies. Even if the CO concentration is the same due to the difference, the CO sensitivity varies depending on the ambient temperature.
　本発明は上述の課題に鑑みてなされたものであり、その目的は、周囲温度の影響を抑制してＣＯ感度のバラツキを低減したガス検知装置を提供することにある。 The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a gas detection device in which the influence of the ambient temperature is suppressed to reduce variation in CO sensitivity.
＜構成１＞
　上記目的を達成するためのガス検知装置の特徴構成は、検出対象ガスとの接触により特性が変化するガス検知部位と、前記ガス検知部位を加熱するヒータ部位と、前記ヒータ部位による加熱を制御する加熱制御部と、前記ガス検知部位またはその周辺の温度を検出する温度検出部と、前記ガス検知部位の特性を測定して検出対象ガスを検出するガス検出部とを有するガス検知装置であって、前記加熱制御部は、前記温度検出部が検出した温度に基づいて前記ヒータ部位による加熱を制御して前記ガス検知部位を一酸化炭素検出用温度に加熱する一酸化炭素検出用加熱動作を行うよう構成され、前記一酸化炭素検出用温度が６０℃以上２００℃以下である点にある。 <Configuration 1>
The characteristic configuration of the gas detection device for achieving the above object is as follows: a gas detection portion whose characteristics are changed by contact with a detection target gas; a heater portion that heats the gas detection portion; and heating by the heater portion. A gas detection device having a heating control unit, a temperature detection unit that detects a temperature of the gas detection site or its surroundings, and a gas detection unit that measures a characteristic of the gas detection site and detects a detection target gas. The heating control section performs a carbon monoxide detection heating operation of controlling the heating by the heater section based on the temperature detected by the temperature detection section and heating the gas detection section to a carbon monoxide detection temperature. In this case, the temperature for detecting carbon monoxide is 60 ° C. or more and 200 ° C. or less.
　上記の特徴構成によれば、一酸化炭素検出用加熱動作が、温度検出部が検出した温度に基づいてヒータ部位による加熱を制御して行われ、ガス検知部位またはその周辺の温度によらず加熱時のガス検知部位の温度を常に一定で保持することにより、Ｌｏｗ駆動でのＣＯ検知時のガス検知部位（酸化スズ）表面におけるＣＯの吸着量（表面被覆率）を一定に保つことができ、ＣＯの吸着量のバラツキによるＣＯ感度のバラツキを抑制することができる。なお、前記一酸化炭素検出用温度が６０℃以上２００℃以下であれば一酸化炭素に対して有意な感度が発現し、一酸化炭素検出が可能であることが実験にて確認されている。 According to the above-mentioned characteristic configuration, the heating operation for detecting carbon monoxide is performed by controlling the heating by the heater portion based on the temperature detected by the temperature detecting portion, and the heating operation is performed regardless of the temperature of the gas detection portion or its surroundings. By keeping the temperature of the gas detection site constant at all times, the amount of adsorption (surface coverage) of CO on the surface of the gas detection site (tin oxide) at the time of CO detection by Low drive can be kept constant, Variations in CO sensitivity due to variations in the amount of CO adsorbed can be suppressed. In addition, when the temperature for detecting carbon monoxide is 60 ° C. or more and 200 ° C. or less, significant sensitivity is exhibited for carbon monoxide, and it has been confirmed by experiments that carbon monoxide can be detected.
＜構成２＞
　本発明に係るガス検知装置は、前記一酸化炭素検出用温度が１００℃以上１６０℃以下であるよう構成すると、より高いＣＯ感度を発現させることができ、さらに好適である。 <Configuration 2>
It is more preferable that the gas detection device according to the present invention be configured so that the temperature for detecting carbon monoxide is 100 ° C. or higher and 160 ° C. or lower, because higher CO sensitivity can be exhibited.
＜構成３＞
　本発明に係るガス検知装置の別の特徴構成は、前記加熱制御部は、前記一酸化炭素検出用加熱動作を行う前に、前記ヒータ部位による加熱を制御して前記ガス検知部位を一酸化炭素検出準備用温度に加熱する一酸化炭素検出準備用加熱動作を行うよう構成され、前記一酸化炭素検出準備用温度が設置環境温度より高く、前記一酸化炭素検出用温度より低い点にある。 <Configuration 3>
Another characteristic configuration of the gas detection device according to the present invention is that, before performing the carbon monoxide detection heating operation, the heating control unit controls heating by the heater unit to set the gas detection site to carbon monoxide. It is configured to perform a carbon monoxide detection preparation heating operation of heating to the detection preparation temperature, wherein the carbon monoxide detection preparation temperature is higher than the installation environment temperature and lower than the carbon monoxide detection temperature.
　従来のＨｉｇｈ－Ｏｆｆ－Ｌｏｗ駆動によるガス検知装置では、Ｏｆｆの間は設置環境温度となるが、その温度は周囲環境により変動するため、ＣＯ検知時のガス検知部位表面でのＣＯ吸着量に差が生じてＣＯ感度がばらついてしまう。上記の特徴構成によれば、一酸化炭素検出準備用加熱動作を行うことにより、ガス検知部位またはその周辺の温度によらず加熱時のガス検知部位の温度がほぼ一定で保持される。したがって、Ｌｏｗ駆動でのＣＯ検知時の検知層（酸化スズ）表面におけるＣＯの吸着量（表面被覆率）をほぼ一定に保つことができ、ＣＯの吸着量のバラツキによるＣＯ感度のバラツキを大幅に抑制することができる。 In the conventional gas detection device driven by High-Off-Low drive, the temperature of the installation environment becomes the temperature during Off, but the temperature varies depending on the surrounding environment. And the CO sensitivity varies. According to the above-described characteristic configuration, by performing the heating operation for preparing carbon monoxide detection, the temperature of the gas detection portion during heating is maintained substantially constant regardless of the temperature of the gas detection portion or its surroundings. Therefore, the amount of adsorbed CO (surface coverage) on the surface of the detection layer (tin oxide) at the time of detecting CO in the low drive can be kept almost constant, and the variation in the CO sensitivity due to the variation in the amount of adsorbed CO is greatly reduced. Can be suppressed.
＜構成４＞
　本発明に係るガス検知装置の別の特徴構成は、前記加熱制御部は、前記一酸化炭素検出準備用加熱動作を行う際に、前記温度検出部が検出した温度に基づいて前記ヒータ部位による加熱を制御するよう構成される点にある。 <Configuration 4>
Another characteristic configuration of the gas detection device according to the present invention is that the heating control unit performs heating by the heater part based on the temperature detected by the temperature detection unit when performing the heating operation for preparing carbon monoxide detection. In that it is configured to control
　上記の特徴構成によれば、一酸化炭素検出準備用加熱動作が、温度検出部が検出した温度に基づいてヒータ部位による加熱を制御して行われるから、ガス検知部位またはその周辺の温度によらず加熱時のガス検知部位の温度が常に一定で保持される。そうすると、一酸化炭素検出用加熱動作の開始時点でのＣＯ吸着量のバラツキに伴う加熱後の吸着量変化挙動のバラツキを抑制し、所定の時間経過後の吸着量をＣＯ濃度が同じ場合には常に一定とすることで、加熱温度における吸着量が平衡に達するまで待ってから検知する必要がなく、吸着量が平衡に達する前の過渡的な状態であってもＣＯ濃度に依存した吸着量となるため、平衡に達する前の過渡状態（短時間加熱）での検知が可能となる。したがってＣＯ感度のバラツキを抑制することに加えて省電力化も可能となる。 According to the above-described characteristic configuration, the heating operation for preparing carbon monoxide detection is performed by controlling the heating by the heater portion based on the temperature detected by the temperature detection portion. The temperature of the gas detection part at the time of heating is always kept constant. Then, the variation of the adsorption amount change behavior after heating due to the variation of the CO adsorption amount at the start of the carbon monoxide detection heating operation is suppressed, and the adsorption amount after the lapse of a predetermined time is reduced when the CO concentration is the same. By keeping it constant, there is no need to wait for the adsorption amount at the heating temperature to reach equilibrium before detection, and even in a transient state before the adsorption amount reaches equilibrium, the adsorption amount depends on the CO concentration. Therefore, detection in a transient state (heating for a short time) before reaching equilibrium is possible. Therefore, in addition to suppressing the variation in the CO sensitivity, power saving can be achieved.
＜構成５＞
　本発明に係るガス検知装置は、前記加熱制御部は、前記ヒータ部位による加熱を制御して前記ガス検知部位を表面クリーニング用温度に加熱するクリーニング用加熱動作を行うよう構成され、前記クリーニング用温度が３００℃以上であるよう構成すると、周囲環境によるＣＯ感度変動を抑制することができ、より好適である。 <Configuration 5>
In the gas detection device according to the present invention, the heating control unit is configured to perform a heating operation for cleaning to control heating by the heater unit and heat the gas detection unit to a surface cleaning temperature, and the cleaning temperature Is 300 ° C. or more, it is possible to suppress the variation in the CO sensitivity due to the surrounding environment, which is more preferable.
は、ガス検知装置の概要を示す概略図である。FIG. 2 is a schematic diagram showing an outline of a gas detection device. は、周囲温度とＣＯ感度との関係を示すグラフである。Is a graph showing the relationship between ambient temperature and CO sensitivity. は、周囲温度とＣＯ感度との関係を示すグラフである。Is a graph showing the relationship between ambient temperature and CO sensitivity. は、ガス検知装置の構造を示す概略図である。FIG. 2 is a schematic diagram showing a structure of a gas detection device. は、ガス検知装置の構造を示す概略図である。FIG. 2 is a schematic diagram showing a structure of a gas detection device.
　本実施形態に係るガス検知装置１００を図１に基づいて説明する。ガス検知装置１００は、センサ素子２０と、加熱制御部１２と、ガス検出部１３と、温度検出部１４とを有する。センサ素子２０は、ガス検知層１０（ガス検知部位の一例）と、触媒層１１と、ヒータ層６（ヒータ部位の一例）とを有している。 ガ ス The gas detection device 100 according to the present embodiment will be described with reference to FIG. The gas detection device 100 includes a sensor element 20, a heating control unit 12, a gas detection unit 13, and a temperature detection unit 14. The sensor element 20 has a gas detection layer 10 (one example of a gas detection part), a catalyst layer 11, and a heater layer 6 (one example of a heater part).
　ガス検知装置１００は、加熱制御部１２によりヒータ層６への通電を行うことにより、ガス検知層１０を検出対象ガスの種類に応じた適切な温度にまで加熱して、この温度を保持した状態におけるガス検知層１０の特性（電気抵抗値、電圧値など）に基づいて検出対象ガスを検出する。本実施形態では、検出対象ガスとして一酸化炭素を想定している。 The gas detection device 100 heats the gas detection layer 10 to an appropriate temperature according to the type of the gas to be detected by energizing the heater layer 6 by the heating control unit 12, and maintains the temperature. The detection target gas is detected on the basis of the characteristics (electric resistance value, voltage value, etc.) of the gas detection layer 10 in. In the present embodiment, carbon monoxide is assumed as the detection target gas.
　触媒層１１は、ヒータ層６により加熱されて高温となり、その温度において活性のある（燃焼する）ガスを燃焼させ、その温度では不活性な可燃性ガスを透過・拡散させてガス検知層１０へ到達させる。これにより、加熱温度を適切に制御することによって可燃性ガス（たとえば、ＣＨ４（メタン）、Ｃ３Ｈ８（プロパン）等）の検出精度が高められている。換言すれば触媒層１１は、メタン等の可燃性ガスを検出する際に、検出対象ガス以外の水素ガス、アルコールガスなどの還元性ガス（非検出対象ガス）を燃焼させてガス検知層１０に到達しないようにし、ガス検知装置１００にガス選択性を持たせる機能を有するため、メタン等の可燃性ガスを検出する際には必要となる。なお、低温（１６０℃以下）ではＣＯ以外のガスはガス検知層１０においてもその温度域では反応しない（３００℃以上でないと反応しない）ため、ガス検知層１０へ到達したとしても検出されないことから、ＣＯ検知のみを行う際には、触媒層１１は必ずしも必要ではない。 The catalyst layer 11 is heated by the heater layer 6 to a high temperature, burns an active (combusting) gas at that temperature, and permeates and diffuses a combustible gas inactive at that temperature to the gas detection layer 10. Let it reach. Thereby, by appropriately controlling the heating temperature, the detection accuracy of combustible gas (for example, CH 4 (methane), C 3 H 8 (propane), etc.) is improved. In other words, when detecting a combustible gas such as methane, the catalyst layer 11 burns a reducing gas (a non-detection target gas) such as a hydrogen gas and an alcohol gas other than the detection target gas and causes the gas detection layer 10 to burn the same. It is necessary to detect flammable gas such as methane because it has a function of preventing the gas from reaching the gas detector and giving the gas detection device 100 gas selectivity. At low temperatures (160 ° C. or less), gases other than CO do not react in the gas detection layer 10 even in that temperature range (they do not react unless the temperature is 300 ° C. or more). When only CO detection is performed, the catalyst layer 11 is not always necessary.
（センサ素子）
　センサ素子２０は、支持層５の端部がシリコン基板１に支持された、ダイアフラム構造をとる。支持層５は、熱酸化膜２と、Ｓｉ３Ｎ４膜３と、ＳｉＯ２膜４とが順に積層されて形成されている。そして支持層５の上にヒータ層６が形成され、ヒータ層６の全体を覆って絶縁層７が形成され、絶縁層７の上に一対の接合層８が形成され、接合層８の上に電極層９が形成されている。ヒータ層６は通電により発熱してガス検知層１０および触媒層１１を加熱する。センサ素子２０は、ブリッジ構造をとってもよく、ヒータ層６は、電極を兼用してもよい。 (Sensor element)
The sensor element 20 has a diaphragm structure in which an end of the support layer 5 is supported on the silicon substrate 1. The support layer 5 is formed by sequentially laminating the thermal oxide film 2, the Si 3 N 4 film 3, and the SiO 2 film 4. Then, a heater layer 6 is formed on the support layer 5, an insulating layer 7 is formed so as to cover the entire heater layer 6, a pair of bonding layers 8 is formed on the insulating layer 7, and An electrode layer 9 is formed. The heater layer 6 generates heat by energization and heats the gas detection layer 10 and the catalyst layer 11. The sensor element 20 may have a bridge structure, and the heater layer 6 may also serve as an electrode.
　絶縁層７の上の、一対の電極層９の間に、ガス検知層１０が形成されている。ガス検知層１０は、金属酸化物を主成分とする半導体の層である。本実施形態では、ガス検知層１０として酸化スズ（ＳｎＯ２）を主成分とする混合物を用いる。ガス検知層１０は、検出対象ガスとの接触により電気抵抗値が変化する。 The gas detection layer 10 is formed between the pair of electrode layers 9 on the insulating layer 7. The gas detection layer 10 is a semiconductor layer containing a metal oxide as a main component. In the present embodiment, a mixture containing tin oxide (SnO 2 ) as a main component is used as the gas detection layer 10. The electric resistance of the gas detection layer 10 changes due to contact with the gas to be detected.
　ガス検知層１０の上に、ガス検知層１０を覆う形態にて、触媒層１１が形成されている。触媒層１１は、金属酸化物を主成分とする担体に、触媒金属を担持させて構成される。
具体的には、触媒金属を担持した金属酸化物をバインダーを介して互いに結合させて形成される。ガス検知層１０は、厚さが０．２～１．６μｍ程度の薄膜としてもよいし、１．６μｍを越える厚さを有する膜（厚膜）としてもよい。 The catalyst layer 11 is formed on the gas detection layer 10 so as to cover the gas detection layer 10. The catalyst layer 11 is configured by supporting a catalyst metal on a carrier mainly composed of a metal oxide.
Specifically, it is formed by bonding metal oxides supporting a catalyst metal to each other via a binder. The gas detection layer 10 may be a thin film having a thickness of about 0.2 to 1.6 μm or a film (thick film) having a thickness exceeding 1.6 μm.
　触媒金属としては、メタン等の可燃性ガスを検知する際に、検出対象ガスの検出に際して誤検知を引き起こし得る干渉ガス（エタノールやＨ２（水素）等の還元性ガスその他の雑ガス）を、酸化除去できる触媒となる金属を用いる。触媒金属としてパラジウム（Ｐｄ）、白金（Ｐｔ）、ロジウム（Ｒｈ）、イリジウム（Ｉｒ）等が使用可能であるが、本実施形態では、パラジウム、白金、イリジウム、ロジウムのうち少なくとも一つを含むものを用いる。 As the catalytic metal, when detecting a combustible gas such as methane, an interference gas (a reducing gas such as ethanol or H 2 (hydrogen) or other miscellaneous gas) that may cause a false detection when detecting a detection target gas is used. A metal that can be a catalyst that can be removed by oxidation is used. As the catalyst metal, palladium (Pd), platinum (Pt), rhodium (Rh), iridium (Ir), or the like can be used. In the present embodiment, at least one of palladium, platinum, iridium, and rhodium is used. Is used.
　触媒金属を担持する担体としては、アルミナ（Ａｌ２Ｏ３）、酸化ジルコニウム（ＺｒＯ２）、酸化イットリウム（Ｙ２Ｏ３）、酸化セリウム（ＣｅＯ２）、酸化ランタン（Ｌａ２Ｏ３）、酸化チタン（ＴｉＯ２）、酸化ハフニウム（ＨｆＯ２）、酸化ニオブ（Ｎｂ２Ｏ５）、または酸化タンタル（Ｔａ２Ｏ５）を用いることができる。 Alumina (Al 2 O 3 ), zirconium oxide (ZrO 2 ), yttrium oxide (Y 2 O 3 ), cerium oxide (CeO 2 ), lanthanum oxide (La 2 O 3 ), oxidized Titanium (TiO 2 ), hafnium oxide (HfO 2 ), niobium oxide (Nb 2 O 5 ), or tantalum oxide (Ta 2 O 5 ) can be used.
　担体を結合させるバインダーとしては、金属酸化物の微粉末、例えば酸化ジルコニウム、シリカ微粉末、シリカゾル、マグネシア等を用いることができる。バインダーとしての微量の使用であれば、触媒層１１の機能を阻害しない範囲で、アルミナ微粉末またはアルミナゾルを用いることも可能である。 バ イ ン ダ ー As the binder for binding the carrier, fine powder of a metal oxide, for example, zirconium oxide, silica fine powder, silica sol, magnesia and the like can be used. If a small amount is used as a binder, alumina fine powder or alumina sol can be used as long as the function of the catalyst layer 11 is not hindered.
　上述した触媒金属、担体としての金属酸化物、バインダーはいずれも、１種類を単独で使用してもよいし、２種以上を併用することもできる。 も Each of the above-mentioned catalyst metals, metal oxides as carriers and binders may be used alone or in combination of two or more.
　触媒層１１に含有される触媒金属の量は、触媒金属と担体の合計質量に対して０．３～９質量％とするのが好適であり、さらに望ましくは触媒金属と担体の合計質量に対して０．５質量％～６質量％とするのが良い。 The amount of the catalyst metal contained in the catalyst layer 11 is preferably from 0.3 to 9% by mass with respect to the total mass of the catalyst metal and the carrier, and more preferably with respect to the total mass of the catalyst metal and the carrier. Is preferably 0.5% by mass to 6% by mass.
（加熱制御部）
　加熱制御部１２は、ヒータ層６に通電する加熱動作（ヒータ部位によるガス検知部位の加熱をする動作）と、ヒータ層６に通電しない非加熱動作（ヒータ部位によるガス検知部位の加熱を停止する非加熱動作）とを行うよう構成される。また加熱制御部１２は、ヒータ層６の温度を変動させるよう構成されており、ヒータ層６の温度を設定された任意の温度へ加熱することが可能なように構成されている。 (Heating control unit)
The heating control unit 12 performs a heating operation for energizing the heater layer 6 (operation for heating the gas detection site by the heater site) and a non-heating operation for not energizing the heater layer 6 (stops heating the gas detection site for the heater site). (Non-heating operation). The heating control unit 12 is configured to change the temperature of the heater layer 6, and is configured to be able to heat the temperature of the heater layer 6 to an arbitrary set temperature.
　具体的には加熱制御部１２は、図示しない電池等の電源から電源供給を受け、センサ素子２０のヒータ層６に通電して、センサ素子２０を加熱する。加熱する温度、すなわちガス検知層１０および触媒層１１の到達温度は、例えばヒータ層６に印可する電圧を変更することにより、制御される。 Specifically, the heating control unit 12 receives power supply from a power source such as a battery (not shown), supplies electricity to the heater layer 6 of the sensor element 20, and heats the sensor element 20. The heating temperature, that is, the temperature reached by the gas detection layer 10 and the catalyst layer 11 is controlled, for example, by changing the voltage applied to the heater layer 6.
（ガス検出部）
　ガス検出部１３は、ガス検知層１０の特性を測定して検出対象ガスを検出する。本実施形態ではガス検出部１３は、一対の電極層９の間の電気抵抗値（電気的特性）を測定することにより、ガス検知層１０の抵抗値を測定して、その変化から検出対象ガスの濃度を検出する。 (Gas detector)
The gas detection unit 13 measures the characteristics of the gas detection layer 10 and detects the detection target gas. In the present embodiment, the gas detection unit 13 measures the resistance value of the gas detection layer 10 by measuring the electric resistance value (electrical characteristic) between the pair of electrode layers 9, and detects the gas to be detected from the change. The concentration of is detected.
　温度検出部１４は、ガス検知層１０またはその周辺の温度（ガス検知装置１００の周辺温度）を検出する。具体的には温度検出部１４は、サーミスタ等の温度センサである。また、ヒータ層６の抵抗値を計測することによってヒータ層６の温度（ガス検知層１０の温度とほぼ同等）を検出することもできる。温度検出部１４によって検出された温度（以下「周辺温度」と記す場合がある。）は、加熱制御部１２へ送られる。 The temperature detector 14 detects the temperature of the gas detection layer 10 or its surroundings (the temperature around the gas detecting device 100). Specifically, the temperature detection unit 14 is a temperature sensor such as a thermistor. Further, by measuring the resistance value of the heater layer 6, the temperature of the heater layer 6 (substantially equivalent to the temperature of the gas detection layer 10) can be detected. The temperature detected by the temperature detection unit 14 (hereinafter, sometimes referred to as “ambient temperature”) is sent to the heating control unit 12.
（検出対象ガスの検出）
　以上の様に構成されたガス検知装置１００における、検出対象ガスの検出の際の動作について説明する。本実施形態に係るガス検知装置では、一酸化炭素検出用加熱動作と、クリーニング用加熱動作が行われる。 (Detection of gas to be detected)
The operation of the gas detection device 100 configured as described above when detecting a detection target gas will be described. In the gas detection device according to the present embodiment, a heating operation for detecting carbon monoxide and a heating operation for cleaning are performed.
　一酸化炭素検出用加熱動作は、加熱制御部１２が、温度検出部１４が検出した温度（周辺温度）に基づいてヒータ層６（ヒータ部位）による加熱を制御してガス検知層１０（ガス検知部位）および触媒層１１（触媒部位）を一酸化炭素検出用温度に加熱する動作である。一酸化炭素検出用温度は、１００℃以上１６０℃以下の所定の温度である。例えば一酸化炭素検出用温度は、１５０℃である。 In the heating operation for detecting carbon monoxide, the heating control unit 12 controls the heating by the heater layer 6 (heater portion) based on the temperature (ambient temperature) detected by the temperature detecting unit 14 to thereby control the gas detection layer 10 (gas detection). This is an operation of heating the catalyst portion 11) and the catalyst layer 11 (catalyst portion) to the temperature for detecting carbon monoxide. The temperature for detecting carbon monoxide is a predetermined temperature of 100 ° C. or more and 160 ° C. or less. For example, the temperature for detecting carbon monoxide is 150 ° C.
　具体的には、加熱制御部１２が、ヒータ層６への通電を制御して、ガス検知層１０および触媒層１１を一酸化炭素検出用温度にし、０．０５秒～１０秒の間温度を保持する。この間にガス検出部１３がガス検知層１０の抵抗値を測定して、その値からＣＯ（一酸化炭素）の濃度を検出する。 Specifically, the heating control unit 12 controls the energization of the heater layer 6 to bring the gas detection layer 10 and the catalyst layer 11 to the temperature for detecting carbon monoxide, and reduce the temperature for 0.05 to 10 seconds. Hold. During this time, the gas detection unit 13 measures the resistance value of the gas detection layer 10 and detects the concentration of CO (carbon monoxide) from the value.
　一酸化炭素検出用加熱動作において、加熱制御部１２によるヒータ層６への通電は、温度検出部１４が検出した周辺温度に基づいて行われる。具体的には加熱制御部１２は、周辺温度に基づいてヒータ層６へ印加するヒータ駆動電圧ＶＨを制御する。例えば、周辺温度２０℃を基準温度として、周辺温度が高くなると相対的にヒータ駆動電圧ＶＨが低く設定され、周辺温度が低くなると相対的にヒータ駆動電圧ＶＨが高く設定される。つまり、周辺温度２０℃を基準温度として、周辺温度が高くなると相対的にヒータ駆動のための電力が低くなるように制御され、周辺温度が低くなると相対的にヒータ駆動のための電力が高くなるように制御され、周辺温度によらずガス検知層１０の温度が一定となるように制御している。 に お い て In the heating operation for detecting carbon monoxide, the power supply to the heater layer 6 by the heating control unit 12 is performed based on the ambient temperature detected by the temperature detection unit 14. Specifically, the heating control unit 12 controls the heater drive voltage VH applied to the heater layer 6 based on the surrounding temperature. For example, with the surrounding temperature of 20 ° C. as a reference temperature, the heater driving voltage VH is set relatively low when the surrounding temperature is high, and the heater driving voltage VH is set relatively high when the surrounding temperature is low. That is, with the ambient temperature of 20 ° C. as the reference temperature, the power for driving the heater is controlled to be relatively low when the ambient temperature is high, and the power for driving the heater is relatively high when the peripheral temperature is low. The temperature of the gas detection layer 10 is controlled to be constant regardless of the surrounding temperature.
　本実施形態のガス検知装置１００では、一酸化炭素検出用加熱動作が、周辺温度に基づいてヒータ部位による加熱を制御して行われ、周囲温度によらず温度を常に一定で保持することにより、Ｌｏｗ駆動でのＣＯ検知時の検知層（酸化スズ）表面におけるＣＯの吸着量（表面被覆率）を一定に保つことができ、ＣＯの吸着量のバラツキによるＣＯ感度のバラツキを抑制することができる。 In the gas detection device 100 of the present embodiment, the heating operation for detecting carbon monoxide is performed by controlling the heating by the heater portion based on the ambient temperature, and the temperature is always kept constant regardless of the ambient temperature. The amount of adsorbed CO (surface coverage) on the surface of the detection layer (tin oxide) at the time of detecting CO in low drive can be kept constant, and the variation in CO sensitivity due to the variation in the amount of adsorbed CO can be suppressed. .
　クリーニング用加熱動作は、加熱制御部１２が、周辺温度に基づいてヒータ層６（ヒータ部位）による加熱を制御してガス検知層１０（ガス検知部位）および触媒層１１（触媒部位）を表面クリーニング用温度に加熱して、Ｌｏｗ駆動では除去しきれないガス検知層１０の表面吸着物（水分、よごれなど）を加熱除去する動作である。表面クリーニング用温度は、３００℃以上５００℃以下の所定の温度である。例えば表面クリーニング用温度は、４００℃である。 In the heating operation for cleaning, the heating control unit 12 controls the heating by the heater layer 6 (heater portion) based on the ambient temperature to clean the surface of the gas detection layer 10 (gas detection portion) and the catalyst layer 11 (catalyst portion). This is an operation of heating to the use temperature and heating and removing the surface adsorbed matter (moisture, dirt, etc.) of the gas detection layer 10 that cannot be completely removed by the Low drive. The surface cleaning temperature is a predetermined temperature of 300 ° C. or more and 500 ° C. or less. For example, the surface cleaning temperature is 400 ° C.
　具体的には、加熱制御部１２が、ヒータ層６への通電を制御して、ガス検知層１０および触媒層１１を表面クリーニング用温度にし、０．０５秒～０．５秒の間温度を保持する。この動作により、水分等のガス検知層１０の表面吸着物を除去し表面をクリーニングして、周囲環境による表面の汚れによるＣＯ感度の変動を抑制する。 Specifically, the heating control unit 12 controls the energization of the heater layer 6 so that the gas detection layer 10 and the catalyst layer 11 are set to the surface cleaning temperature, and the temperature is set for 0.05 to 0.5 seconds. Hold. By this operation, the surface adsorbed matter of the gas detection layer 10 such as moisture is removed and the surface is cleaned, and the fluctuation of the CO sensitivity due to the contamination of the surface due to the surrounding environment is suppressed.
　クリーニング用加熱動作において、加熱制御部１２によるヒータ層６への通電は、温度検出部１４が検出した周辺温度に基づいて行われる。具体的には加熱制御部１２は、周辺温度に基づいてヒータ層６へ印加するヒータ駆動電圧ＶＨを制御する。例えば、周辺温度２０℃を基準温度として、周辺温度が高くなると相対的にヒータ駆動電圧ＶＨが低く設定され、周辺温度が低くなると相対的にヒータ駆動電圧ＶＨが高く設定される。つまり、周辺温度２０℃を基準温度として、周辺温度が高くなると相対的にヒータ駆動のための電力が低くなるように制御され、周辺温度が低くなると相対的にヒータ駆動のための電力が高くなるように制御される。 In the heating operation for cleaning, the power supply to the heater layer 6 by the heating control unit 12 is performed based on the ambient temperature detected by the temperature detection unit 14. Specifically, the heating control unit 12 controls the heater drive voltage VH applied to the heater layer 6 based on the surrounding temperature. For example, with the surrounding temperature of 20 ° C. as a reference temperature, the heater driving voltage VH is set relatively low when the surrounding temperature is high, and the heater driving voltage VH is set relatively high when the surrounding temperature is low. That is, with the ambient temperature of 20 ° C. as the reference temperature, the power for driving the heater is controlled to be relatively low when the ambient temperature is high, and the power for driving the heater is relatively high when the peripheral temperature is low. Is controlled as follows.
　本実施形態では、一酸化炭素検出用加熱動作およびクリーニング用加熱動作は、休止動作（ヒータ層６への通電を停止する動作）を挟んで繰り返し行われる。なお、それぞれの動作の時間は適宜設定・変更が可能であり、休止動作は省略することも可能である。また、一酸化炭素検出用加熱動作とクリーニング用加熱動作の実行頻度は等しくてもよいし、異なっていてもよい。例えば、一酸化炭素検出用加熱動作を５回行う都度、クリーニング用加熱動作を１回行うようガス検知装置１００を構成するなど、使用環境に応じてクリーニング動作の頻度を減らしてもよい。また、クリーニング用加熱動作時に表面クリーニングのみならずメタン検出を行ってもてもよい。その場合は、表面クリーニング用加熱動作時にガス検出部１３がガス検知層１０の抵抗値を測定して、その値からメタンの濃度を検出する。 In the present embodiment, the heating operation for detecting carbon monoxide and the heating operation for cleaning are repeatedly performed with a pause operation (an operation of stopping power supply to the heater layer 6). The time of each operation can be set and changed as appropriate, and the pause operation can be omitted. Further, the execution frequency of the heating operation for detecting carbon monoxide and the heating operation for cleaning may be the same or different. For example, the frequency of the cleaning operation may be reduced in accordance with the use environment, such as configuring the gas detection device 100 to perform the heating operation for cleaning once each time the heating operation for carbon monoxide detection is performed five times. Further, not only surface cleaning but also methane detection may be performed during the heating operation for cleaning. In that case, the gas detection unit 13 measures the resistance value of the gas detection layer 10 during the heating operation for cleaning the surface, and detects the methane concentration from the measured value.
　図２は、一酸化炭素検出用加熱動作において、周辺温度に基づくヒータ駆動電力の制御を行った場合（実施例１）と行わない場合（比較例）の、ＣＯ感度の周囲温度依存性を測定した結果である。なお、ヒータ駆動方法は、クリーニング用加熱動作（４００℃，０．２秒）、休止動作（５秒）、一酸化炭素検出用加熱動作（１５０℃、０．５秒）、休止動作（５４．３秒）を繰り返し、ＣＯ感度の測定は、ＣＯ濃度３００ｐｐｍの環境下で周囲温度を０℃から５０℃まで変化させて行った。また、ＣＯ感度の測定は、一酸化炭素検出用加熱動作開始０．５秒後に行った。図２のグラフは、周囲温度２０℃でのＣＯ感度を１として示している。 FIG. 2 shows the ambient temperature dependence of the CO sensitivity in the heating operation for detecting carbon monoxide when the heater driving power is controlled based on the ambient temperature (Example 1) and when it is not performed (Comparative Example). This is the result. The heater driving method includes a cleaning heating operation (400 ° C., 0.2 seconds), a pause operation (5 seconds), a carbon monoxide detection heating operation (150 ° C., 0.5 seconds), and a pause operation (54. 3 seconds), and the measurement of the CO sensitivity was performed in an environment with a CO concentration of 300 ppm while changing the ambient temperature from 0 ° C. to 50 ° C. The measurement of the CO sensitivity was performed 0.5 seconds after the start of the heating operation for detecting carbon monoxide. The graph of FIG. 2 shows the CO sensitivity at an ambient temperature of 20 ° C. as 1.
　比較例では、周囲温度が上昇するとＣＯ感度が減少した。一方、実施例１では、周囲温度が変化してもＣＯ感度は変化しなかった。以上の結果から、周辺温度に基づくヒータ駆動電力の制御を行うことにより、周囲温度によるＣＯ感度変化が抑制されることが示された。 で は In the comparative example, the CO sensitivity decreased as the ambient temperature increased. On the other hand, in Example 1, the CO sensitivity did not change even when the ambient temperature changed. From the above results, it was shown that by controlling the heater drive power based on the ambient temperature, the change in the CO sensitivity due to the ambient temperature was suppressed.
（第２実施形態）
　本実施形態に係るガス検知装置１００では、一酸化炭素検出用加熱動作とクリーニング用加熱動作に加えて、一酸化炭素検出準備用加熱動作が実行される。 (2nd Embodiment)
In the gas detection device 100 according to the present embodiment, in addition to the heating operation for detecting carbon monoxide and the heating operation for cleaning, a heating operation for preparing for detecting carbon monoxide is executed.
　一酸化炭素検出準備用加熱動作は、加熱制御部１２が、一酸化炭素検出用加熱動作を行う前に、ヒータ層６（ヒータ部位）による加熱を制御してガス検知層１０（ガス検知部位）および触媒層１１（触媒部位）を一酸化炭素検出準備用温度に加熱する動作である。一酸化炭素検出準備用温度は、設置環境温度より高く、一酸化炭素検出用温度より低い所定の温度である。例えば一酸化炭素検出準備用温度は、５０℃である。 In the heating operation for preparing carbon monoxide detection, before the heating control unit 12 performs the heating operation for detecting carbon monoxide, the heating by the heater layer 6 (heater portion) is controlled to perform the gas detection layer 10 (gas detection portion). And an operation of heating the catalyst layer 11 (catalyst portion) to a temperature for preparing carbon monoxide detection. The carbon monoxide detection preparation temperature is a predetermined temperature that is higher than the installation environment temperature and lower than the carbon monoxide detection temperature. For example, the temperature for preparing carbon monoxide detection is 50 ° C.
　具体的には、加熱制御部１２が、ヒータ層６への通電を制御して、ガス検知層１０および触媒層１１を一酸化炭素検出準備用温度にし、０．０５秒～２０秒の間温度を保持する。例えば、５秒保持する。なお、先に示した実施形態と同様、一酸化炭素検出用加熱動作とクリーニング用加熱動作の実行頻度は等しくてもよいし、異なっていてもよいが、一酸化炭素検出準備用加熱動作は、必ず一酸化炭素検出用加熱動作の直前に行う。また、クリーニング用加熱動作時に表面クリーニングのみならずメタン検出を行ってもよい。 Specifically, the heating control unit 12 controls the energization of the heater layer 6 so that the gas detection layer 10 and the catalyst layer 11 are set to the temperature for preparing carbon monoxide detection, and the temperature is set to 0.05 to 20 seconds. Hold. For example, hold for 5 seconds. Note that, similarly to the above-described embodiment, the execution frequency of the heating operation for carbon monoxide detection and the heating operation for cleaning may be the same or different, but the heating operation for carbon monoxide detection preparation is Always perform immediately before the heating operation for detecting carbon monoxide. Further, not only surface cleaning but also methane detection may be performed during the heating operation for cleaning.
　一酸化炭素検出準備用加熱動作において、加熱制御部１２によるヒータ層６への通電は、温度検出部１４が検出した周辺温度に基づいて行われてもよい。具体的には加熱制御部１２は、周辺温度に基づいてヒータ層６へ印加するヒータ駆動電圧ＶＨを制御する。例えば、周辺温度２０℃を基準温度として、周辺温度が高くなると相対的にヒータ駆動電圧ＶＨが低く設定され、周辺温度が低くなると相対的にヒータ駆動電圧ＶＨが高く設定される。つまり、周辺温度２０℃を基準温度として、周辺温度が高くなると相対的にヒータ駆動のための電力が低くなるように制御され、周辺温度が低くなると相対的にヒータ駆動のための電力が高くなるように制御される。 In the heating operation for preparing for detection of carbon monoxide, the power supply to the heater layer 6 by the heating control unit 12 may be performed based on the ambient temperature detected by the temperature detection unit 14. Specifically, the heating control unit 12 controls the heater drive voltage VH applied to the heater layer 6 based on the surrounding temperature. For example, with the surrounding temperature of 20 ° C. as a reference temperature, the heater driving voltage VH is set relatively low when the surrounding temperature is high, and the heater driving voltage VH is set relatively high when the surrounding temperature is low. That is, with the ambient temperature of 20 ° C. as the reference temperature, the power for driving the heater is controlled to be relatively low when the ambient temperature is high, and the power for driving the heater is relatively high when the peripheral temperature is low. Is controlled as follows.
　本実施形態に係るガス検知装置１００では、一酸化炭素検出準備用加熱動作が終了した直後に、一酸化炭素検出用加熱動作が行われる。従来のＨｉｇｈ－Ｏｆｆ－Ｌｏｗ駆動によるガス検知装置では、Ｏｆｆの間は設置環境温度となるが、その温度は周囲環境により変動するため、ＣＯ検知時の検知層表面でのＣＯ吸着量（温度によって吸着量は変動する）に差が生じてＣＯ感度がばらついてしまう。一酸化炭素検出準備用加熱動作を行うことにより、Ｌｏｗ駆動でのＣＯ検知時の検知層（酸化スズ）表面におけるＣＯの吸着量（表面被覆率）を一定に保つことができ、ＣＯの吸着量のバラツキによるＣＯ感度のバラツキを抑制することができる。そして本実施形態では、一酸化炭素検出準備用加熱動作が、周辺温度に基づいてヒータ部位による加熱を制御して行われるから、周囲温度によらず温度が常に一定で保持される。そうすると、一酸化炭素検出用加熱動作の開始時点でのＣＯ吸着量は温度には依存せず、ＣＯ濃度のみによって決定されるため、加熱後の吸着量変化挙動はＣＯ濃度に依存して一定となり、周囲温度によるバラツキが抑制されるため、吸着平衡に達する前の所定の時間経過時点での吸着量変化は一定となり、一酸化炭素検出用加熱動作による吸着量が平衡に達する（吸着量が安定する）まで待ってから検知する必要がなく、吸着量が平衡に達する前の過渡的な状態であってもＣＯ濃度に依存した吸着量となるため、平衡前の過渡状態（短時間加熱）での検知が可能となる。したがって省電力化も可能となる。 で は In the gas detection device 100 according to the present embodiment, the heating operation for detecting carbon monoxide is performed immediately after the heating operation for preparing for detecting carbon monoxide is completed. In the conventional high-off-low drive gas detection device, the installation environment temperature is maintained during the off period, but the temperature fluctuates depending on the surrounding environment. Therefore, the amount of CO adsorbed on the detection layer surface during CO detection (depending on the temperature) (The amount of adsorption fluctuates), and the CO sensitivity varies. By performing the heating operation for preparing carbon monoxide detection, the amount of adsorbed CO (surface coverage) on the surface of the detection layer (tin oxide) at the time of detecting CO in Low drive can be kept constant, and the amount of adsorbed CO Can be suppressed from varying the CO sensitivity due to the above-mentioned variation. In the present embodiment, since the heating operation for preparing carbon monoxide detection is performed by controlling the heating by the heater portion based on the ambient temperature, the temperature is always kept constant regardless of the ambient temperature. Then, since the amount of CO adsorbed at the start of the heating operation for detecting carbon monoxide does not depend on the temperature, but is determined only by the CO concentration, the behavior of changing the adsorbed amount after heating becomes constant depending on the CO concentration. Since the variation due to the ambient temperature is suppressed, the change in the amount of adsorption at a predetermined time before reaching the adsorption equilibrium is constant, and the amount of adsorption by the heating operation for carbon monoxide detection reaches equilibrium (the adsorption amount is stable). No need to detect after waiting until), and even in the transient state before the adsorption amount reaches equilibrium, the adsorption amount depends on the CO concentration. Can be detected. Therefore, power saving is also possible.
　図３は、一酸化炭素検出用加熱動作において、周辺温度に基づくヒータ駆動電力の制御を行う場合（実施例２）と、さらに、一酸化炭素検出準備用加熱（周辺温度に基づいてヒータ部位による加熱を制御）動作も行う場合（実施例３）の、ＣＯ感度の周囲温度依存性を測定した結果である。ヒータ駆動方法は、クリーニング用加熱動作（４００℃，０．２秒）、一酸化炭素検出準備用加熱動作（実施例３、５秒）または休止動作（実施例２、５秒）、一酸化炭素検出用加熱動作（１５０℃、０．１秒）、休止動作（５４．７秒）を繰り返し、ＣＯ感度の測定は、一酸化炭素検出用加熱動作開始０．１秒後に行い、ＣＯ濃度３００ｐｐｍの環境下で周囲温度を０℃、２０℃および５０℃に変化させて行った。図３のグラフは、周囲温度２０℃でのＣＯ感度を１として示している。なお、一酸化炭素検出用加熱動作後にＣＯ吸着量が平衡に達するまでに０．２秒以上必要であることがわかっている。 FIG. 3 shows the case where the heater driving power is controlled based on the ambient temperature in the heating operation for detecting carbon monoxide (Example 2), and the heating for preparing for detecting carbon monoxide (the heater portion is controlled based on the ambient temperature). It is the result of measuring the ambient temperature dependency of the CO sensitivity in the case of also performing the (control of heating) operation (Example 3). The heater driving method includes a heating operation for cleaning (400 ° C., 0.2 seconds), a heating operation for carbon monoxide detection preparation (Examples 3 and 5 seconds) or a pause operation (Examples 2 and 5 seconds), carbon monoxide. The heating operation for detection (150 ° C., 0.1 second) and the pause operation (54.7 seconds) are repeated, and the measurement of the CO sensitivity is performed 0.1 second after the start of the heating operation for carbon monoxide detection. The test was performed by changing the ambient temperature to 0 ° C., 20 ° C., and 50 ° C. under the environment. The graph of FIG. 3 shows the CO sensitivity at an ambient temperature of 20 ° C. as 1. It is known that it takes 0.2 seconds or more for the CO adsorption amount to reach equilibrium after the heating operation for detecting carbon monoxide.
　実施例２では、周囲温度が上昇するとＣＯ感度が減少した。これは、一酸化炭素検出用加熱動作の開始時点での検知層（酸化スズ）表面におけるＣＯ吸着量が、周囲温度によってばらつくため、一酸化炭素検出用加熱動作開始後のＣＯ吸着量変化挙動も周囲温度によってばらつき、一酸化炭素検出用加熱動作開始０．１秒後（ＣＯ吸着量が平衡に達する前の過渡状態）の吸着量も、同じＣＯ濃度であっても周囲温度によってばらついてしまうためと考えられる。一方、実施例３では、周囲温度が変化してもＣＯ感度は変化しなかった。これは、一酸化炭素検出用加熱動作の開始時点での検知層（酸化スズ）表面におけるＣＯ吸着量が周囲温度によらず一定であるため、一酸化炭素検出用加熱動作開始０．１秒経過時点でのＣＯ吸着量も周囲温度によらず一定であるためと考えられる。なお、図示しないが、周辺温度に基づいてヒータ部位による加熱を制御せずに一酸化炭素検出準備用加熱動作をする場合でも、周囲温度によるＣＯ感度変動は、実施例２と比べて抑制されることが確認されている。以上の結果から、一酸化炭素検出準備用加熱動作を行うことにより、０．１秒程度の短時間加熱での検知を行う場合でも周囲温度によるＣＯ感度変化が抑制されることから、より省電力な駆動での検知が可能となることが示された。 で は In Example 2, the CO sensitivity decreased as the ambient temperature increased. This is because the amount of CO adsorbed on the surface of the detection layer (tin oxide) at the start of the heating operation for detecting carbon monoxide varies depending on the ambient temperature. The amount of adsorption varies 0.1 seconds after the start of the heating operation for detecting carbon monoxide (transient state before the amount of adsorbed CO reaches equilibrium), and the amount of adsorption also varies depending on the ambient temperature even at the same CO concentration. it is conceivable that. On the other hand, in Example 3, the CO sensitivity did not change even when the ambient temperature changed. This is because the amount of adsorbed CO on the surface of the detection layer (tin oxide) at the start of the heating operation for detecting carbon monoxide is constant regardless of the ambient temperature, so that 0.1 seconds after the start of the heating operation for detecting carbon monoxide. It is considered that the amount of adsorbed CO at the time is also constant regardless of the ambient temperature. Although not shown, even when the heating operation for preparing carbon monoxide detection is performed without controlling the heating by the heater portion based on the ambient temperature, the variation in the CO sensitivity due to the ambient temperature is suppressed as compared with the second embodiment. That has been confirmed. From the above results, by performing the heating operation for preparing carbon monoxide detection, even when the detection is performed by heating for a short time of about 0.1 second, the change in the CO sensitivity due to the ambient temperature is suppressed. It has been shown that detection with a simple drive is possible.
　表１は、高湿（２０℃９０％ＲＨ）中にて１００時間駆動後のＣＯ感度を、クリーニング用加熱動作の頻度によって比較した結果である。ヒータ駆動方法は、クリーニング用加熱動作（４００℃，０．２秒）、一酸化炭素検出準備用加熱動作（５秒）、一酸化炭素検出用加熱動作（１５０℃、０．１秒）、休止動作（５４．７秒）を１サイクルとして繰り返すことを基本とし、＜ａ＞クリーニング用加熱動作を毎サイクル行うもの、＜ｂ＞クリーニング用加熱動作を５サイクルに１回行うもの、＜ｃ＞クリーニング用加熱動作を表面汚染検知（後述）時のみ行うもの、＜ｄ＞クリーニング用加熱動作を行わないもの、の４通りで比較した。ＣＯ感度の測定は、一酸化炭素検出用加熱動作開始０．１秒後に行い、ＣＯ濃度３００ｐｐｍの環境下（測定時のみ）で高湿中での駆動開始直後（初期）と２４時間駆動後に測定し、初期の感度を１とした時の１００時間駆動後の感度を求めた。また、表面汚染検知とは、一酸化炭素検出加熱動作における空気雰囲気中での出力値が、表面の汚染（水分吸着や汚れ等）によって変化（低抵抗化）することを検知する方法であり、具体的には、出力値が１０％変化（ＣＯ検知と判定する出力変化よりも小さい）した場合に表面汚染検知とした。クリーニングを行わない場合または、５サイクルに１回の低頻度であると、表面汚染によって感度が大きく低下してしまうが、表面汚染検知時のみにクリーニングを行う場合は、感度低下が僅かしか見られなかった。このことから、クリーニング用加熱動作を毎サイクル行わず表面汚染検知時のみに行うことで、表面汚染による感度低下を最小限に抑制しつつ、クリーニング頻度低減による省電力化を実現できる。 Table 1 shows the results of comparing the CO sensitivity after driving in high humidity (20 ° C. 90% RH) for 100 hours with the frequency of the heating operation for cleaning. The heater driving method includes a heating operation for cleaning (400 ° C., 0.2 seconds), a heating operation for carbon monoxide detection preparation (5 seconds), a heating operation for carbon monoxide detection (150 ° C., 0.1 seconds), a pause. Basically, the operation (54.7 seconds) is repeated as one cycle. <a> A cleaning heating operation is performed every cycle, <b> A cleaning heating operation is performed once every five cycles, and <c> Cleaning is performed. The comparison was made in four ways: one in which the heating operation for cleaning was performed only when surface contamination was detected (described later), and one in which the heating operation for cleaning was not performed. The CO sensitivity is measured 0.1 seconds after the start of the heating operation for detecting carbon monoxide, and is measured immediately after the start of driving in a high humidity environment (only at the initial stage) and after driving for 24 hours in an environment with a CO concentration of 300 ppm (only during measurement) Then, the sensitivity after driving for 100 hours when the initial sensitivity was set to 1 was determined. Surface contamination detection is a method of detecting that the output value in the air atmosphere during the carbon monoxide detection heating operation changes (lower resistance) due to surface contamination (moisture adsorption, dirt, etc.). Specifically, when the output value changed by 10% (smaller than the output change determined to be CO detection), surface contamination detection was performed. If cleaning is not performed or the frequency is low once every 5 cycles, the sensitivity is greatly reduced due to surface contamination. However, if cleaning is performed only when surface contamination is detected, the sensitivity is slightly reduced. Did not. Thus, by performing the cleaning heating operation only at the time of surface contamination detection without performing each cycle, it is possible to minimize the reduction in sensitivity due to surface contamination and to achieve power saving by reducing the cleaning frequency.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
（他の実施形態）
＜１＞上述の実施形態では、ガス検知装置１００の構造は、図１に示されるいわゆる基板型であるが、他の構造も可能である。例えば、ヒータ層６を覆う絶縁層７が設けられず、ヒータ層６が電極層９を兼ねる構造も可能である。また、例えば図４に示すように、電極とヒータ部位とを兼ねる電極線２１のコイル２２の周囲に、酸化物半導体からなるガス検知部位２３を形成し、その周囲に触媒層２４を形成する構造も可能である。また図５に示すように、電極とヒータ部位とを兼ねる電極線３１のコイル３２の中心に、別の電極３３を配置して、コイル３２の周囲に、酸化物半導体からなるガス検知部位３４を形成し、その周囲に触媒層３５を形成する構造も可能である。 (Other embodiments)
<1> In the above embodiment, the structure of the gas detection device 100 is a so-called substrate type shown in FIG. 1, but other structures are also possible. For example, a structure in which the insulating layer 7 covering the heater layer 6 is not provided and the heater layer 6 also functions as the electrode layer 9 is also possible. Further, for example, as shown in FIG. 4, a structure in which a gas detection portion 23 made of an oxide semiconductor is formed around a coil 22 of an electrode wire 21 serving as an electrode and a heater portion, and a catalyst layer 24 is formed around the gas detection portion 23. Is also possible. Further, as shown in FIG. 5, another electrode 33 is disposed at the center of the coil 32 of the electrode wire 31 serving also as an electrode and a heater portion, and a gas detection portion 34 made of an oxide semiconductor is formed around the coil 32. A structure in which the catalyst layer 35 is formed and the catalyst layer 35 is formed therearound is also possible.
＜２＞また上述の実施例においては、一酸化炭素検出準備用加熱動作は、クリーニング用加熱動作の直後に行ったが、クリーニング用加熱動作後に休止動作を挟んで一酸化炭素検出準備用加熱動作を行ってもよい。 <2> In the above-described embodiment, the heating operation for preparing carbon monoxide detection was performed immediately after the heating operation for cleaning. However, the heating operation for preparing carbon monoxide detection was performed after a pause operation after the heating operation for cleaning. May be performed.
　なお上述の実施形態（他の実施形態を含む、以下同じ）で開示される構成は、矛盾が生じない限り、他の実施形態で開示される構成と組み合わせて適用することが可能であり、また、本明細書において開示された実施形態は例示であって、本発明の実施形態はこれに限定されず、本発明の目的を逸脱しない範囲内で適宜改変することが可能である。 Note that the configurations disclosed in the above-described embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with the configurations disclosed in other embodiments, as long as no contradiction occurs. The embodiment disclosed in the present specification is an exemplification, and the embodiment of the present invention is not limited to this, and can be appropriately modified without departing from the object of the present invention.
６　　　　：ヒータ層（ヒータ部位）
１０　　　：ガス検知層（ガス検知部位）
１１　　　：触媒層（触媒部位）
１２　　　：加熱制御部
１３　　　：ガス検出部
１４　　　：温度検出部
２１　　　：電極線（ヒータ部位）
２３　　　：ガス検知部位
２４　　　：触媒層（触媒部位）
３１　　　：電極線（ヒータ部位）
３４　　　：ガス検知部位
３５　　　：触媒層（触媒部位）
１００　　：ガス検知装置 6: heater layer (heater part)
10: Gas detection layer (gas detection site)
11: catalyst layer (catalyst site)
12: heating controller 13: gas detector 14: temperature detector 21: electrode wire (heater part)
23: gas detection site 24: catalyst layer (catalyst site)
31: Electrode wire (heater part)
34: gas detection part 35: catalyst layer (catalyst part)
100: Gas detector

Claims (5)

  1. 　検出対象ガスとの接触により特性が変化するガス検知部位と、
    　前記ガス検知部位を加熱するヒータ部位と、
    　前記ヒータ部位による加熱を制御する加熱制御部と、
    　前記ガス検知部位またはその周辺の温度を検出する温度検出部と、
    　前記ガス検知部位の特性を測定して検出対象ガスを検出するガス検出部とを有するガス検知装置であって、
    　前記加熱制御部は、
    　前記温度検出部が検出した温度に基づいて前記ヒータ部位による加熱を制御して前記ガス検知部位を一酸化炭素検出用温度に加熱する一酸化炭素検出用加熱動作を行うよう構成され、前記一酸化炭素検出用温度が６０℃以上２００℃以下であるガス検知装置。     A gas detection site whose characteristics change due to contact with the detection target gas,
    A heater portion for heating the gas detection portion;
    A heating control unit that controls heating by the heater part,
    A temperature detection unit that detects the temperature of the gas detection site or its surroundings,
    A gas detection device having a gas detection unit that detects a gas to be detected by measuring characteristics of the gas detection site,
    The heating control unit,
    The heating unit controls the heating by the heater unit based on the temperature detected by the temperature detection unit, and performs a carbon monoxide detection heating operation of heating the gas detection unit to a carbon monoxide detection temperature. A gas detector having a carbon detection temperature of 60 ° C or more and 200 ° C or less.
  2. 　前記一酸化炭素検出用温度が１００℃以上１６０℃以下である請求項１に記載のガス検知装置。 The gas detection device according to claim 1, wherein the temperature for detecting carbon monoxide is 100 ° C or higher and 160 ° C or lower.
  3. 　前記加熱制御部は、前記一酸化炭素検出用加熱動作を行う前に、前記ヒータ部位による加熱を制御して前記ガス検知部位を一酸化炭素検出準備用温度に加熱する一酸化炭素検出準備用加熱動作を行うよう構成され、前記一酸化炭素検出準備用温度が設置環境温度よりも高く、前記一酸化炭素検出用温度より低い請求項１または２に記載のガス検知装置。 The heating control unit controls heating by the heater unit and heats the gas detection unit to a temperature for preparing carbon monoxide detection before performing the heating operation for detecting carbon monoxide. 3. The gas detection device according to claim 1, wherein the gas detection device is configured to perform an operation, wherein the temperature for preparing carbon monoxide detection is higher than an installation environment temperature and lower than the temperature for detecting carbon monoxide. 4.
  4. 　前記加熱制御部は、前記一酸化炭素検出準備用加熱動作を行う際に、前記温度検出部が検出した温度に基づいて前記ヒータ部位による加熱を制御するよう構成される請求項３に記載のガス検知装置。 The gas according to claim 3, wherein the heating control unit is configured to control heating by the heater part based on a temperature detected by the temperature detection unit when performing the heating operation for preparing for carbon monoxide detection. Detection device.
  5. 　前記加熱制御部は、前記ヒータ部位による加熱を制御して前記ガス検知部位を表面クリーニング用温度に加熱するクリーニング用加熱動作を行うよう構成され、前記表面クリーニング用温度が３００℃以上である請求項１から４のいずれか１項に記載のガス検知装置。 The heating control unit is configured to perform a heating operation for cleaning by controlling heating by the heater unit to heat the gas detection unit to a surface cleaning temperature, and the surface cleaning temperature is 300 ° C. or more. The gas detection device according to any one of claims 1 to 4.
PCT/JP2018/033775 2018-09-12 2018-09-12 Gas detection device WO2020053982A1 (en)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4223432A1 (en) * 1991-08-14 1993-02-18 Siemens Ag Gas sensor for use in IC engine exhaust gas analysers - has a thermoelement as a temp. probe on a common carrier substrate
JP2002350390A (en) * 2001-05-24 2002-12-04 Matsushita Electric Ind Co Ltd Gas detecting device
JP2003172718A (en) * 2001-12-06 2003-06-20 Daikin Ind Ltd Gas detector
JP2005083840A (en) * 2003-09-05 2005-03-31 Osaka Gas Co Ltd Gas detector and gas detection method
JP2007024509A (en) * 2005-07-12 2007-02-01 Fuji Electric Fa Components & Systems Co Ltd Thin film gas sensor
JP2008256472A (en) * 2007-04-03 2008-10-23 Nec Tokin Corp Gas detector
US20090084158A1 (en) * 2007-10-01 2009-04-02 Scott Technologies, Inc. Gas measuring device and method of operating the same

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4223432A1 (en) * 1991-08-14 1993-02-18 Siemens Ag Gas sensor for use in IC engine exhaust gas analysers - has a thermoelement as a temp. probe on a common carrier substrate
JP2002350390A (en) * 2001-05-24 2002-12-04 Matsushita Electric Ind Co Ltd Gas detecting device
JP2003172718A (en) * 2001-12-06 2003-06-20 Daikin Ind Ltd Gas detector
JP2005083840A (en) * 2003-09-05 2005-03-31 Osaka Gas Co Ltd Gas detector and gas detection method
JP2007024509A (en) * 2005-07-12 2007-02-01 Fuji Electric Fa Components & Systems Co Ltd Thin film gas sensor
JP2008256472A (en) * 2007-04-03 2008-10-23 Nec Tokin Corp Gas detector
US20090084158A1 (en) * 2007-10-01 2009-04-02 Scott Technologies, Inc. Gas measuring device and method of operating the same

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