JP3385248B2 - Gas sensor - Google Patents
Gas sensorInfo
- Publication number
- JP3385248B2 JP3385248B2 JP31004299A JP31004299A JP3385248B2 JP 3385248 B2 JP3385248 B2 JP 3385248B2 JP 31004299 A JP31004299 A JP 31004299A JP 31004299 A JP31004299 A JP 31004299A JP 3385248 B2 JP3385248 B2 JP 3385248B2
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- Prior art keywords
- gas
- sensor
- gas sensor
- detected
- semiconductor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Description
【０００１】[0001]
【発明の属する技術分野】本発明は、可燃性ガスはじめ
各種ガスの検知及び測定のためのガスセンサに関する。
詳細には、本発明は湿度（水分）の影響を受けることな
くガス濃度を検知及び測定することのできるガスセンサ
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas sensor for detecting and measuring combustible gas and various gases.
More specifically, the present invention relates to a gas sensor capable of detecting and measuring gas concentration without being affected by humidity (moisture).
【０００２】[0002]
【従来の技術】ガスセンサは、外界に存在するガスをと
らえ、そのガスの濃度を電気信号に変換するデバイスで
ある。このガスセンサの中に半導体式センサ、接触燃焼
式センサ、熱伝導度式センサがある。半導体式センサ
は、可燃性ガスおよび還元性ガスに高感度であるため、
これらのガスの比較的低濃度の検知に用いられる。接触
燃焼式センサは原理的に可燃性ガスに感度を有し、爆発
下限界濃度以下の検知に用いられる。熱伝導度式センサ
は、ガスの熱伝導度に依存した出力を持ち、主として％
レベル以上の比較的高濃度のガス検知に用いられる。2. Description of the Related Art A gas sensor is a device that captures a gas existing in the outside world and converts the concentration of the gas into an electric signal. Among these gas sensors, there are semiconductor type sensors, catalytic combustion type sensors, and thermal conductivity type sensors. Since the semiconductor type sensor has high sensitivity to combustible gas and reducing gas,
It is used to detect relatively low concentrations of these gases. The catalytic combustion type sensor is sensitive to combustible gas in principle, and is used to detect the lower explosive limit concentration. The thermal conductivity type sensor has an output that depends on the thermal conductivity of gas, and mainly
It is used to detect relatively high concentrations of gas above the level.
【０００３】半導体式センサは、その構造により大きく
２つのタイプに分けられる。第１のタイプは、図１に示
されるように、ヒータと抵抗値を取り出す電極を兼ねた
金属線フィラメント11に金属酸化物半導体12を塗布・焼
結した検知素子を用いたタイプで、フィラメントは支持
体13、14で保持している。金属線フィラメント11の材質
としては通常白金（Ｐｔ）が用いられる。この検知素子
は図２に示す回路構成で使用される。検知素子21と比較
素子22を直列に接続し、これと並列に対辺抵抗23、24を
接続することにより、いわゆるホイートストン・ブリッ
ジ回路を構成する。ここで、比較素子22としては、通常
検知素子と同じ素子を検知対象ガスに接触させずに（例
えば容器内に密閉する）使用するか、素子表面をガス不
透過性の物質（例えばガラス膜）で覆うか、または固定
抵抗を用いる。また、対辺抵抗23、24は、通常検知素子
21及び比較素子22の抵抗値の100 倍程度の抵抗値の固定
抵抗を用いるが、ホイートストン・ブリッジの平衡を保
つためであり、特に規定するものではない。電源25によ
りこの回路に電流を流し、検知素子を加熱する。加熱さ
れた状態で検知素子21が検知対象ガスに接触すると、金
属酸化物半導体の抵抗値が減少するため、26−27間の電
位差が変化してセンサ出力となる。Semiconductor type sensors are roughly classified into two types depending on their structures. As shown in FIG. 1, the first type is a type that uses a sensing element in which a metal oxide semiconductor 12 is applied and sintered on a metal wire filament 11 that also serves as a heater and an electrode for taking out a resistance value. It is held by supports 13 and 14. Platinum (Pt) is usually used as the material of the metal wire filament 11. This sensing element is used in the circuit configuration shown in FIG. The so-called Wheatstone bridge circuit is configured by connecting the detection element 21 and the comparison element 22 in series, and connecting the opposite side resistors 23 and 24 in parallel with this. Here, as the comparison element 22, the same element as the normal detection element is used without being brought into contact with the gas to be detected (for example, sealed in a container), or the surface of the element is a gas impermeable substance (for example, a glass film). Or use a fixed resistor. In addition, the opposite side resistances 23 and 24 are normal detection elements.
A fixed resistor having a resistance value about 100 times the resistance value of 21 and the comparison element 22 is used, but this is for maintaining the balance of the Wheatstone bridge and is not particularly specified. A current is passed through this circuit by the power supply 25 to heat the sensing element. When the sensing element 21 comes into contact with the gas to be sensed in the heated state, the resistance value of the metal oxide semiconductor decreases, so that the potential difference between 26 and 27 changes and becomes the sensor output.
【０００４】第１のタイプのセンサの別の構造として、
絶縁体基板上に膜体で構成した検知素子を使用する図３
に示すセンサがある。この検知素子は絶縁体基板31上に
金属膜のヒータ32を形成し、そのヒータ32を覆うように
金属酸化物半導体膜33を形成したもので、リード線34、
35で接続する。このセンサの使用方法及び出力の取り出
しは、図２に示している前記のセンサと同じである。As another structure of the first type of sensor,
Using a sensing element composed of a film on an insulating substrate Fig. 3
There is a sensor shown in. In this detection element, a heater 32 made of a metal film is formed on an insulating substrate 31, and a metal oxide semiconductor film 33 is formed so as to cover the heater 32. A lead wire 34,
Connect at 35. The method of using this sensor and taking out the output are the same as those of the sensor shown in FIG.
【０００５】半導体式センサの第２のタイプは、金属酸
化物半導体の抵抗変化を比較素子を用いずに直接取り出
す方式である。このセンサは第１のタイプと異なり、金
属酸化物半導体を加熱するヒータとその抵抗値を取り出
すリード線が別々となっている。このセンサの構造を図
４で示す。絶縁管41の内部にヒータ42を配置し、表面に
抵抗取り出し用の電極43、44およびリード線45、46を形
成する。電極43、44の両者と接触するように金属酸化物
半導体47を絶縁管41の外部に形成する。このセンサを図
５に示す回路に接続して使用する。金属酸化物半導体51
に直列に固定抵抗52を接続し、一定電圧を印加する。ま
た、ヒータ53に電流を流すことにより金属酸化物半導体
51を加熱する。加熱された状態でセンサを検知対象ガス
に接触させると、金属酸化物半導体51の抵抗が減少する
ため、回路に流れる電流が増大し、固定抵抗52の両端す
なわち54−55間の電圧が増大する。この電圧変化をセン
サの出力として取り出す。この第２のタイプの半導体式
センサについても第１のタイプと同様、絶縁体基板上に
ヒータ及び金属酸化物半導体を膜体で構成したセンサも
ある。ただし、この場合はヒータ膜と金属酸化物半導体
膜は電気的に絶縁されている必要がある。The second type of semiconductor sensor is a method of directly taking out the resistance change of a metal oxide semiconductor without using a comparison element. This sensor is different from the first type in that the heater for heating the metal oxide semiconductor and the lead wire for taking out the resistance value thereof are separate. The structure of this sensor is shown in FIG. A heater 42 is arranged inside the insulating tube 41, and electrodes 43 and 44 for taking out resistance and lead wires 45 and 46 are formed on the surface. A metal oxide semiconductor 47 is formed outside the insulating tube 41 so as to come into contact with both the electrodes 43 and 44. This sensor is used by connecting it to the circuit shown in FIG. Metal oxide semiconductor 51
A fixed resistor 52 is connected in series with the resistor and a constant voltage is applied. In addition, by supplying an electric current to the heater 53, the metal oxide semiconductor
Heat 51. When the sensor is brought into contact with the gas to be detected in a heated state, the resistance of the metal oxide semiconductor 51 decreases, so that the current flowing in the circuit increases and the voltage across the fixed resistor 52, that is, 54-55 increases. . This voltage change is taken out as the output of the sensor. Similar to the first type, there is also a second type semiconductor sensor in which a heater and a metal oxide semiconductor are formed as a film on an insulating substrate. However, in this case, the heater film and the metal oxide semiconductor film need to be electrically insulated.
【０００６】接触燃焼式センサは第１のタイプの半導体
式センサの金属酸化物半導体部（図１の12）を燃焼触媒
に代えた接触燃焼素子で構成される。燃焼触媒として
は、通常アルミナ等の担体に貴金属を担持した触媒が使
用できる。接触燃焼素子は第１のタイプの半導体式セン
サと同様、図２の回路で使用される。接触燃焼素子が加
熱された状態で検知対象ガス（可燃性ガス）に接触する
と、触媒表面で燃焼反応が起こり、その燃焼熱により素
子温度が上昇し、素子抵抗が増大する。この結果26−27
間の電位差が変化してセンサ出力となる。The catalytic combustion type sensor is composed of a catalytic combustion element in which the metal oxide semiconductor portion (12 in FIG. 1) of the first type semiconductor type sensor is replaced with a combustion catalyst. As the combustion catalyst, a catalyst obtained by supporting a noble metal on a carrier such as alumina can be usually used. Catalytic combustion elements are used in the circuit of FIG. 2, as are semiconductor sensors of the first type. When the contact combustion element comes into contact with the gas to be detected (combustible gas) in a heated state, a combustion reaction occurs on the catalyst surface, and the heat of combustion raises the element temperature and increases the element resistance. This result 26-27
The potential difference between them changes and becomes the sensor output.
【０００７】熱伝導度式センサは第１のタイプの半導体
式センサの金属酸化物半導体部（図１の12）を被検知ガ
スと反応しない耐熱材に代えた熱伝導度素子で構成され
る。被検知ガスと反応しない耐熱材は、通常ガスと反応
しないガラス、セラミック等を使用することができる。
熱伝導度素子は第１のタイプの半導体式センサと同様、
図２の回路で使用される。熱伝導度素子が加熱された状
態で検知対象ガスに接触すると、検知対象ガスの熱伝導
度に依存して素子の放熱状態が変化するため素子温度が
変化し、それに伴い素子抵抗が変化する。この結果26−
27間の電位差が変化してセンサ出力となる。The thermal conductivity type sensor is composed of a thermal conductivity element in which the metal oxide semiconductor portion (12 in FIG. 1) of the semiconductor sensor of the first type is replaced with a heat resistant material that does not react with the gas to be detected. As the heat-resistant material that does not react with the gas to be detected, glass, ceramic, or the like that does not normally react with the gas can be used.
The thermal conductivity element is similar to the first type semiconductor sensor,
Used in the circuit of FIG. When the thermal conductivity element contacts the gas to be detected in a heated state, the heat dissipation state of the element changes depending on the thermal conductivity of the gas to be detected, so that the element temperature changes and the element resistance changes accordingly. As a result 26-
The potential difference between 27 changes and becomes the sensor output.
【０００８】これらのガスセンサはほとんどの可燃性ガ
ス（還元性ガス）に対して感度を有するが、湿度（水
分）に対しても同様に感度を有するため、湿度の変化に
よって被検知ガスが存在しない場合にもある濃度を指示
したり、ガスが存在する場合でもガスによる出力と湿度
変化による出力が重ね合わさるため検知対象ガスの正確
な濃度を知ることができなかった。Although these gas sensors have sensitivity to most combustible gases (reducing gases), they also have sensitivity to humidity (moisture), so that no gas to be detected exists due to changes in humidity. In some cases, it was not possible to know the exact concentration of the gas to be detected because the output due to the gas and the output due to the change in humidity were superposed even when a certain concentration was indicated.
【０００９】このような問題を解決するため、例えば特
開昭６０−１４１４８号公報には、半導体式ガスセンサ
において、雰囲気湿度の影響を小さくするために検知素
子と同じ金属酸化物半導体を酸化触媒層で覆い、これを
比較素子としたセンサが記載されている。しかしこのγ
−アルミナに担持されたＰｔ、Ｐｄ等の金属触媒から構
成された酸化触媒は経時劣化が激しく、経時安定性、耐
久性に欠けるという問題がある。In order to solve such a problem, for example, in Japanese Patent Laid-Open No. 60-14148, in a semiconductor gas sensor, in order to reduce the influence of atmospheric humidity, the same metal oxide semiconductor as the detection element is used as an oxidation catalyst layer. A sensor which is covered with and is used as a comparison element is described. But this γ
-The oxidation catalyst composed of a metal catalyst such as Pt or Pd supported on alumina has a problem that it deteriorates significantly with time and lacks stability and durability with time.
【００１０】また特開昭６３−１７１３５２号公報に
は、金属酸化物半導体にモリブデン酸化物及びタングス
テン酸化物を添加することにより、さらに特開昭６３−
３０５２３９号公報には、金属酸化物半導体にチタン化
合物を添加することにより、半導体式ガスセンサの湿度
依存性を改良することが記載されているが、いずれの手
段においても湿度対策としては十分な効果が得られてい
ない。Further, in Japanese Patent Laid-Open No. 63-171352, by adding molybdenum oxide and tungsten oxide to a metal oxide semiconductor, it is further disclosed in Japanese Patent Laid-Open No. 63-171352.
Japanese Patent No. 305239 discloses that a titanium compound is added to a metal oxide semiconductor to improve the humidity dependency of a semiconductor gas sensor. However, any means is effective as a measure against humidity. Not obtained.
【００１１】以上のように、ガスセンサの湿度に対する
影響を排除もしくは低減するため、従来より多くの提案
がなされているが、いずれも欠点を有し、十分なもので
はなかった。As described above, many proposals have been made in the past in order to eliminate or reduce the influence of the gas sensor on the humidity, but all of them have drawbacks and are not sufficient.
【００１２】[0012]
【発明が解決しようとする課題】本発明は、上記の欠点
を解決するためになされたものであり、製作が容易で、
湿度の影響を受けることなく正確なガス濃度を測定する
ことができ、さらに経時安定性に優れたガスセンサを提
供することを目的とする。SUMMARY OF THE INVENTION The present invention has been made to solve the above drawbacks and is easy to manufacture and
It is an object of the present invention to provide a gas sensor that can accurately measure a gas concentration without being affected by humidity and that is excellent in stability over time.
【００１３】[0013]
【課題を解決するための手段】本発明のガスセンサは、
１対のガス検知素子をそれぞれ独立した空間内に配置
し、一方の空間を検知対象ガスに開放し、他方の空間の
開口部を水蒸気透過性かつ検知対象ガス不透過性の膜体
で覆うことを特徴とする。前記ガス検知素子としては、
ガス濃度を金属酸化物半導体の抵抗値変化で検知する半
導体素子、可燃性ガスの触媒による燃焼熱を検知する接
触燃焼素子、又は検知対象ガスと反応しない耐熱材を用
いて、ガスの熱伝導度の差による温度変化を検知する熱
伝導素子を用いることができる。すなわち、本発明のガ
スセンサは、半導体式ガスセンサ、接触燃焼式ガスセン
サ、又は熱伝導度式ガスセンサのいずれにも適用するこ
とができる。前記水蒸気透過性かつ検知対象ガス不透過
性の膜体としては、フッ素樹脂系イオン交換膜又は中空
糸膜を用いることができる。The gas sensor of the present invention comprises:
Arranging a pair of gas detection elements in independent spaces, opening one space to the gas to be detected, and covering the opening of the other space with a film that is water vapor permeable and gas impermeable to the gas to be detected. Is characterized by. As the gas detection element,
The thermal conductivity of the gas is measured using a semiconductor element that detects the gas concentration by the resistance change of the metal oxide semiconductor, a contact combustion element that detects the heat of combustion of a combustible gas due to the catalyst, or a heat-resistant material that does not react with the gas to be detected. It is possible to use a heat conduction element that detects a temperature change due to the difference between the two. That is, the gas sensor of the present invention can be applied to any of a semiconductor gas sensor, a catalytic combustion gas sensor, and a thermal conductivity gas sensor. A fluororesin ion exchange membrane or a hollow fiber membrane can be used as the water vapor permeable and gas to be detected impermeable membrane.
【００１４】本発明のガスセンサは、上記のような構成
を採用することにより、１対のガス検知素子が常に同じ
湿度条件にさらされることになり、実質的に湿度の影響
を受けないか又は無視し得る程度となる。また、１対の
ガス検知素子の出力差を取り出しているため、経時的な
変化についても補償することができる。With the gas sensor of the present invention, by adopting the above-mentioned configuration, the pair of gas detecting elements are always exposed to the same humidity condition, and are not substantially affected by humidity or neglected. To the extent possible. Further, since the output difference between the pair of gas detection elements is taken out, it is possible to compensate for a change over time.
【００１５】[0015]
【発明の実施の形態】以下、図面を参照して本発明を説
明する。図６に本発明のガスセンサの構成を示す。１対
のガス検知素子61はいずれも同一の構成からなることが
好ましく、半導体式ガスセンサの場合、検知対象ガス濃
度を抵抗値変化で検知する金属酸化物半導体62（例えば
ＳｎＯ2 、ＺｎＯ等）とこれを加熱するヒータ63（例え
ば白金線）からなり、このヒータ63は抵抗値変化を取り
出す電極も兼ねている。接触燃焼式ガスセンサの場合
は、金属酸化物半導体の代わりにアルミナ等の担体に貴
金属（例えば白金、パラジウム等）を担持した触媒を62
として用いる。熱伝導度式ガスセンサの場合には、金属
酸化物半導体の代わりに検知対象ガスと反応しない耐熱
材を62として用いる。DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings. FIG. 6 shows the configuration of the gas sensor of the present invention. It is preferable that the pair of gas detection elements 61 have the same configuration. In the case of a semiconductor gas sensor, a pair of gas detection elements 61 and a metal oxide semiconductor 62 (for example, SnO 2 , ZnO, etc.) that detects the concentration of a detection target gas by a resistance change It comprises a heater 63 (for example, a platinum wire) for heating this, and this heater 63 also serves as an electrode for taking out a change in resistance value. In the case of a catalytic combustion type gas sensor, a catalyst in which a noble metal (for example, platinum, palladium, etc.) is supported on a carrier such as alumina instead of the metal oxide semiconductor is used.
Used as. In the case of the thermal conductivity type gas sensor, a heat resistant material that does not react with the gas to be detected is used as 62 instead of the metal oxide semiconductor.
【００１６】このガス検知素子61を検知素子部64と比較
素子部65に配置する。比較素子部65はセンサハウジング
66の開口部67を水蒸気透過性かつ検知対象ガス不透過性
であるガス阻止層となる膜体68で覆う。この膜体68とし
ては、フッ素樹脂系イオン交換膜、例えばNafion（商
標、DuPont社製）、Flemion(商標、旭ガラス社製）、Ac
iplex(商標、旭化成社製）等、又は検知対象ガスと水蒸
気とを分離することができる中空糸膜を用いることがで
きる。一方、検知素子部64のセンサハウジング66の開口
部67は開放にしておき、そして検知素子部64と比較素子
部65の開口部が同じ検知対象ガス雰囲気にさらされるよ
うにガス通気路69に配置する。The gas detection element 61 is arranged in the detection element section 64 and the comparison element section 65. The comparison element part 65 is a sensor housing.
An opening 67 of 66 is covered with a film body 68 which is a gas blocking layer which is permeable to water vapor and impermeable to the gas to be detected. As the membrane 68, a fluororesin ion exchange membrane such as Nafion (trademark, manufactured by DuPont), Flemion (trademark, manufactured by Asahi Glass Co., Ltd.), Ac
It is possible to use iplex (trademark, manufactured by Asahi Kasei Co., Ltd.) or the like, or a hollow fiber membrane capable of separating the gas to be detected and water vapor. On the other hand, the opening 67 of the sensor housing 66 of the detection element unit 64 is left open, and is arranged in the gas ventilation path 69 so that the openings of the detection element unit 64 and the comparison element unit 65 are exposed to the same detection target gas atmosphere. To do.
【００１７】このようにして構成した検知素子を、上記
の半導体式ガスセンサ、接触燃焼式ガスセンサ、又は熱
伝導度式ガスセンサに応じた回路に組み込む。例えば、
半導体式ガスセンサの場合、図２に示すような回路に接
続する。すなわち、検知素子部21と比較素子部22を直列
に接続し、これと並列となるように対辺抵抗23及び24を
接続し、この回路に直流電源25を接続する。出力は図中
の26−27間の電位差を測定することにより得られる。The sensing element thus constructed is incorporated in a circuit corresponding to the above semiconductor gas sensor, catalytic combustion gas sensor or thermal conductivity gas sensor. For example,
In the case of a semiconductor gas sensor, it is connected to a circuit as shown in FIG. That is, the detection element section 21 and the comparison element section 22 are connected in series, the opposite side resistors 23 and 24 are connected in parallel with the detection element section 21, and the DC power supply 25 is connected to this circuit. The output is obtained by measuring the potential difference between 26 and 27 in the figure.
【００１８】図４に示す構造の検知素子を用いる場合に
は、図７に示す回路に接続する。一方の素子48のハウジ
ング71の開口部72は検知対象ガスに開放とし、これを検
知素子部73とする。他方の素子48のハウジングの開口部
は水蒸気透過性かつ検知対象ガス不透過性であるガス阻
止層となる膜体74で覆い、これを比較素子75とする。こ
の検知素子部73と比較素子部75を同じ検知対象ガスにさ
らす。検知素子部73と比較素子部75のガス出力はそれぞ
れＶｄ及びＶｒで出力され、オペアンプによって出力差
Ｖｃが得られる。When the sensing element having the structure shown in FIG. 4 is used, it is connected to the circuit shown in FIG. The opening 72 of the housing 71 of one of the elements 48 is open to the gas to be detected, and this is referred to as a detection element section 73. The opening of the housing of the other element 48 is covered with a film 74 that is a gas blocking layer that is permeable to water vapor and impermeable to the gas to be detected. The detection element unit 73 and the comparison element unit 75 are exposed to the same gas to be detected. The gas outputs of the detection element unit 73 and the comparison element unit 75 are output as Vd and Vr, respectively, and the output difference Vc is obtained by the operational amplifier.
【００１９】[0019]
【実施例】上記図６のようにして構成した本発明の半導
体式ガスセンサと、膜体68を設けない従来の半導体式ガ
スセンサについて湿度依存性を図８及び図９に示す。図
８は本発明の半導体式ガスセンサのAir 及び検知対象ガ
スＣＨ4(200ppm) の出力、すなわち図２における26−27
間の電位差を示している。図９は従来の半導体式ガスセ
ンサ（比較素子として固定抵抗を使用）のAir 及び検知
対象ガスＣＨ4 の出力である。相対湿度50％のときのセ
ンサ出力を基準とし、相対湿度を変化させたときの出力
差をプロットした。図９に示すように、従来の半導体式
ガスセンサでは、相対湿度の変化によってセンサ出力は
大きく変動しているが、図８に示すように、本発明の半
導体式ガスセンサのAir 出力は湿度の影響をほとんど受
けず、湿度に無関係に０を示し、ＣＨ4 出力において
も、湿度による影響は受けなかった。EXAMPLE FIGS. 8 and 9 show the humidity dependence of the semiconductor gas sensor of the present invention constructed as shown in FIG. 6 and the conventional semiconductor gas sensor without the film 68. FIG. 8 shows the outputs of Air and the detection target gas CH 4 (200 ppm) of the semiconductor gas sensor of the present invention, that is, 26-27 in FIG.
The potential difference between the two is shown. FIG. 9 shows outputs of Air and a detection target gas CH 4 of a conventional semiconductor gas sensor (using a fixed resistance as a comparison element). Based on the sensor output when the relative humidity was 50%, the output difference when the relative humidity was changed was plotted. As shown in FIG. 9, in the conventional semiconductor gas sensor, the sensor output fluctuates greatly due to changes in relative humidity. However, as shown in FIG. 8, the Air output of the semiconductor gas sensor of the present invention is affected by humidity. Almost no effect, indicating 0 regardless of humidity, and CH 4 output was not affected by humidity.
【００２０】次に、上記の本発明の半導体式ガスセンサ
と従来の半導体式ガスセンサを屋外に設置し、約６か月
間フィールド試験を行った。この結果を図10に示す。図
10は、センサ出力を検知対象ガスであるＣＨ4 濃度に換
算した値を示し、屋外空気を連続的に通気したときの指
示値Air(ゼロ）、及び検知対象ガス(200ppm ＣＨ4)を定
期的に通気させたときのセンサの指示値を示す（○と
●）。また、センサ周辺の気温及び相対湿度の変化も併
せて示している。この図10に示すように、従来の半導体
式ガスセンサのAir 指示値、すなわちゼロ点は、気温及
び相対湿度の変化に伴って変化しており、それに伴って
ＣＨ4 換算の指示値も変化している。これに対して、本
発明の半導体式ガスセンサではAir 指示値及びＣＨ4 指
示値共に気温及び相対湿度の影響を受けることなく非常
に安定した指示値を示している。Next, the semiconductor gas sensor of the present invention and the conventional semiconductor gas sensor were installed outdoors, and a field test was conducted for about 6 months. The result is shown in FIG. Figure
10 indicates the value obtained by converting the sensor output into the concentration of CH 4 that is the detection target gas, and indicates the indicated value Air (zero) when continuously ventilating the outdoor air and the detection target gas (200 ppm CH 4 ) periodically. Indicates the indicated value of the sensor when ventilated to (○ and ●). In addition, changes in temperature and relative humidity around the sensor are also shown. As shown in FIG. 10, the indicated air value of the conventional semiconductor gas sensor, that is, the zero point, changes with changes in temperature and relative humidity, and the indicated value in CH 4 conversion also changes accordingly. There is. On the other hand, in the semiconductor gas sensor of the present invention, both the indicated value of Air and the indicated value of CH 4 show very stable indicated values without being affected by the temperature and relative humidity.
【００２１】半導体式ガスセンサは安価で長寿命であ
り、高感度であるため早期漏洩を検知できる特徴を有し
ており、定置式の可燃性ガス等の漏洩検知警報器用セン
サとして普及している。従来の半導体式ガスセンサでは
周囲の気温、湿度の変化に依存して指示を示すことか
ら、警報濃度はゼロ点指示値の変化幅よりも大きな値に
設定しなければならなかった。例えば、図10に示す従来
のセンサのゼロ点指示値はＣＨ4 換算で最大180ppmまで
変化している。このとき警報濃度設定が180ppm以下であ
る場合、検知対象ガスであるＣＨ4 が存在しないにもか
かわらず周囲の気温、湿度の影響によって警報を発する
ことになり、誤警報となる。しかしながら、本発明の半
導体式ガスセンサは、図10に示すように気温、湿度の影
響を受けず、検知対象ガスを精度よく検出することがで
きると共に、ゼロ点指示値がほとんど変化しないため、
警報濃度を従来よりも低い値（例えば100ppm）に設定す
ることが可能となり、さらなるガス漏洩の早期発見が可
能になる。The semiconductor type gas sensor is inexpensive, has a long service life, and has high sensitivity, so that it has the characteristic of being able to detect an early leak. Since the conventional semiconductor gas sensor gives an indication depending on changes in ambient temperature and humidity, the alarm concentration must be set to a value larger than the change width of the zero point instruction value. For example, the zero point indication value of the conventional sensor shown in FIG. 10 changes up to 180 ppm in terms of CH 4 . At this time, if the alarm concentration setting is 180 ppm or less, an alarm will be issued due to the influence of ambient temperature and humidity even if CH 4 which is the detection target gas does not exist, resulting in a false alarm. However, the semiconductor gas sensor of the present invention, as shown in FIG. 10, is not affected by the temperature and humidity, and it is possible to detect the gas to be detected accurately, and the zero point instruction value hardly changes,
It is possible to set the alarm concentration to a lower value (for example, 100 ppm) than before, and it is possible to detect further gas leaks early.
【００２２】[0022]
【発明の効果】本発明のガスセンサは、湿度の影響を実
質的に受けず、信頼性の高いガス検知及び測定を可能に
する。The gas sensor of the present invention is substantially unaffected by humidity and enables highly reliable gas detection and measurement.
【図１】従来のガスセンサの検知素子の構成を示す断面
図である。FIG. 1 is a cross-sectional view showing a configuration of a detection element of a conventional gas sensor.
【図２】ガスセンサの回路図である。FIG. 2 is a circuit diagram of a gas sensor.
【図３】従来のガスセンサの検知素子の構成を示す斜視
図である。FIG. 3 is a perspective view showing a configuration of a detection element of a conventional gas sensor.
【図４】従来のガスセンサの検知素子の構成を示す部分
断面図である。FIG. 4 is a partial cross-sectional view showing a configuration of a detection element of a conventional gas sensor.
【図５】ガスセンサの回路図である。FIG. 5 is a circuit diagram of a gas sensor.
【図６】本発明のガスセンサの構成を示す断面図であ
る。FIG. 6 is a cross-sectional view showing the configuration of the gas sensor of the present invention.
【図７】ガスセンサの回路図である。FIG. 7 is a circuit diagram of a gas sensor.
【図８】本発明のガスセンサの相対湿度変化に対するセ
ンサ出力の変化を示すグラフである。FIG. 8 is a graph showing changes in sensor output with respect to changes in relative humidity of the gas sensor of the present invention.
【図９】従来のガスセンサの相対湿度変化に対するセン
サ出力の変化を示すグラフである。FIG. 9 is a graph showing changes in sensor output with respect to changes in relative humidity of a conventional gas sensor.
【図１０】本発明のガスセンサと従来のガスセンサの６
か月間のフィールド試験の結果を示すグラフである。FIG. 10 shows a gas sensor of the present invention and a conventional gas sensor 6
It is a graph which shows the result of the field test for a month.
11…フィラメント 12、33、47、51、62…金属酸化物半導体 13、14…支持体 21、61、48…検知素子 22、75…比較素子 23、24…対辺抵抗 25…電源 31…絶縁体基板 32、42、53、63…ヒータ 41…絶縁管 52…固定抵抗 64、73…検知素子部 65…比較素子部 66、71…センサハウジング 68、74…膜体 69…ガス通気路 11 ... filament 12, 33, 47, 51, 62 ... Metal oxide semiconductor 13, 14 ... Support 21, 61, 48 ... Sensing element 22, 75 ... Comparative element 23, 24 ... Opposite side resistance 25 ... Power 31 ... Insulator substrate 32, 42, 53, 63 ... Heater 41 ... Insulation tube 52 ... Fixed resistance 64, 73 ... Sensing element section 65 ... Comparison element section 66, 71 ... Sensor housing 68, 74 ... Membrane body 69 ... Gas vent
フロントページの続き (56)参考文献 特開 平８−82610（ＪＰ，Ａ) 特開 昭62−118247（ＪＰ，Ａ) 特開 平４−131756（ＪＰ，Ａ) 実開 平４−15057（ＪＰ，Ｕ) 実開 昭57−198056（ＪＰ，Ｕ) (58)調査した分野(Int.Cl.7，ＤＢ名) G01N 27/00 - 27/49 Continuation of the front page (56) Reference JP-A-8-82610 (JP, A) JP-A-62-118247 (JP, A) JP-A-4-131756 (JP, A) Actual Kaihei 4-15057 (JP , U) Actual development 57-198056 (JP, U) (58) Fields investigated (Int.Cl. 7 , DB name) G01N 27/00-27/49
Claims (6)
空間内に配置し、一方の空間を検知対象ガスに開放し、
他方の空間の開口部を水蒸気透過性かつ検知対象ガス不
透過性の膜体で覆うことを特徴とするガスセンサ。1. A pair of gas detection elements are arranged in respective independent spaces, and one of the spaces is opened to a gas to be detected,
A gas sensor, characterized in that the opening of the other space is covered with a film that is permeable to water vapor and impermeable to the gas to be detected.
らなる、請求項１記載のガスセンサ。2. The gas sensor according to claim 1, wherein the gas detection element is made of a metal oxide semiconductor.
請求項１記載のガスセンサ。3. The gas detection element is composed of a combustion catalyst,
The gas sensor according to claim 1.
ない耐熱材からなる、請求項１記載のガスセンサ。4. The gas sensor according to claim 1, wherein the gas detection element is made of a heat-resistant material that does not react with the gas to be detected.
過性の膜体がフッ素樹脂系イオン交換膜である、請求項
１〜４のいずれか１項に記載のガスセンサ。5. The gas sensor according to claim 1, wherein the water vapor permeable and gas to be detected impermeable film body is a fluororesin ion exchange membrane.
過性の膜体が中空糸膜である、請求項１〜４のいずれか
１項に記載のガスセンサ。6. The gas sensor according to claim 1, wherein the water vapor permeable and gas to be detected impermeable membrane is a hollow fiber membrane.
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|---|---|---|---|
| JP31004299A JP3385248B2 (en) | 1999-10-29 | 1999-10-29 | Gas sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31004299A JP3385248B2 (en) | 1999-10-29 | 1999-10-29 | Gas sensor |
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| Publication Number | Publication Date |
|---|---|
| JP2001124716A JP2001124716A (en) | 2001-05-11 |
| JP3385248B2 true JP3385248B2 (en) | 2003-03-10 |
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|---|---|---|---|
| JP31004299A Expired - Lifetime JP3385248B2 (en) | 1999-10-29 | 1999-10-29 | Gas sensor |
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| CN110568028A (en) * | 2019-10-18 | 2019-12-13 | 安徽伯华氢能源科技有限公司 | Hydrogen sensor |
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| JP7084886B2 (en) * | 2019-01-31 | 2022-06-15 | 日本特殊陶業株式会社 | Gas sensor |
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