JP2001124716A - Gas sensor - Google Patents
Gas sensorInfo
- Publication number
- JP2001124716A JP2001124716A JP31004299A JP31004299A JP2001124716A JP 2001124716 A JP2001124716 A JP 2001124716A JP 31004299 A JP31004299 A JP 31004299A JP 31004299 A JP31004299 A JP 31004299A JP 2001124716 A JP2001124716 A JP 2001124716A
- Authority
- JP
- Japan
- Prior art keywords
- gas
- gas sensor
- 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.)
- Granted
Links
- 239000012528 membrane Substances 0.000 claims abstract description 6
- 239000012510 hollow fiber Substances 0.000 claims abstract description 4
- 239000004065 semiconductor Substances 0.000 claims description 50
- 238000001514 detection method Methods 0.000 claims description 34
- 229910044991 metal oxide Inorganic materials 0.000 claims description 22
- 150000004706 metal oxides Chemical class 0.000 claims description 22
- 239000003054 catalyst Substances 0.000 claims description 10
- 238000002485 combustion reaction Methods 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 239000003779 heat-resistant material Substances 0.000 claims description 5
- 239000003014 ion exchange membrane Substances 0.000 claims description 3
- 239000012466 permeate Substances 0.000 abstract 2
- 238000005342 ion exchange Methods 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 109
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 7
- 238000007084 catalytic combustion reaction Methods 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000000758 substrate Substances 0.000 description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 3
- 229910052697 platinum Inorganic materials 0.000 description 3
- 230000000903 blocking effect Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000012212 insulator Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229910000510 noble metal Inorganic materials 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 229910052763 palladium Inorganic materials 0.000 description 2
- 102100028175 Abasic site processing protein HMCES Human genes 0.000 description 1
- 229920003935 Flemion® Polymers 0.000 description 1
- 101001006387 Homo sapiens Abasic site processing protein HMCES Proteins 0.000 description 1
- 108010000178 IGF-I-IGFBP-3 complex Proteins 0.000 description 1
- 229920000557 Nafion® Polymers 0.000 description 1
- 229910006404 SnO 2 Inorganic materials 0.000 description 1
- 101000872823 Xenopus laevis Probable histone deacetylase 1-A Proteins 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910000476 molybdenum oxide Inorganic materials 0.000 description 1
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- PQQKPALAQIIWST-UHFFFAOYSA-N oxomolybdenum Chemical compound [Mo]=O PQQKPALAQIIWST-UHFFFAOYSA-N 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
- 150000003609 titanium compounds Chemical class 0.000 description 1
- 229910001930 tungsten oxide Inorganic materials 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
Landscapes
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Abstract
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。The present invention relates to a gas sensor for detecting and measuring various gases including combustible gas.
More specifically, the present invention relates to a gas sensor capable of detecting and measuring a 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 detects a gas present in the outside world and converts the concentration of the gas into an electric signal. Among these gas sensors, there are a semiconductor sensor, a contact combustion sensor, and a thermal conductivity sensor. Semiconductor sensors are highly sensitive to combustible and reducing gases,
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 for detecting the concentration below the lower explosive limit. Thermal conductivity sensors have an output that depends on the thermal conductivity of the gas,
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。[0003] Semiconductor type sensors are roughly classified into two types according to their structures. As shown in FIG. 1, the first type uses a sensing element obtained by applying and sintering a metal oxide semiconductor 12 to a metal wire filament 11 which also serves as a heater and an electrode for extracting a resistance value. It is held by supports 13 and 14. As a material of the metal wire filament 11, platinum (Pt) is usually used. This sensing element is used in the circuit configuration shown in FIG. A so-called Wheatstone bridge circuit is configured by connecting the detecting element 21 and the comparing 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 contacting the detection target gas (for example, sealed in a container), or the element surface is made of a gas-impermeable substance (for example, a glass film). Cover or use a fixed resistor. The opposite resistors 23 and 24 are usually
A fixed resistor having a resistance value of about 100 times the resistance value of 21 and the comparison element 22 is used, but this is for keeping the balance of the Wheatstone bridge and is not particularly specified. A current is supplied to this circuit by the power supply 25 to heat the sensing element. When the detection element 21 contacts the gas to be detected in a 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,
FIG. 3 using a sensing element composed of a film on an insulating substrate
There is a sensor shown in This sensing element has a metal film heater 32 formed on an insulator substrate 31 and a metal oxide semiconductor film 33 formed so as to cover the heater 32.
Connect with 35. The method of using the sensor and extracting 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。[0005] A second type of semiconductor type sensor is a system in which a resistance change of a metal oxide semiconductor is directly taken out without using a comparison element. This sensor differs from the first type in that a heater for heating the metal oxide semiconductor and a lead wire for extracting the resistance value are separate. FIG. 4 shows the structure of this sensor. A heater 42 is arranged inside an 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 be in 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, and a constant voltage is applied. In addition, a 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, the current flowing in the circuit increases, and the voltage between both ends of the fixed resistor 52, that is, the voltage between 54 and 55 increases. . This voltage change is extracted as an output of the sensor. As with the first type, there is also a sensor in which a heater and a metal oxide semiconductor are formed of a film on an insulating substrate, as in the first type. 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 comprises a catalytic combustion element in which the metal oxide semiconductor portion (12 in FIG. 1) of the semiconductor sensor of the first type is replaced with a combustion catalyst. As the combustion catalyst, a catalyst in which a noble metal is supported on a carrier such as alumina can be used. The catalytic combustion element is used in the circuit of FIG. 2, as in the first type of semiconductor type sensor. When the contact combustion element contacts the detection target gas (flammable gas) in a heated state, a combustion reaction occurs on the surface of the catalyst, and the combustion heat increases 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 comprises a thermal conductivity element in which the metal oxide semiconductor portion (12 in FIG. 1) of the first type semiconductor type sensor is replaced with a heat resistant material which 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 semiconductor sensor of the first type.
Used in the circuit of FIG. If the thermal conductivity element contacts the gas to be detected in a heated state, the element temperature changes because the heat radiation state of the element changes depending on the thermal conductivity of the detection target gas, and the element resistance changes accordingly. As a result,
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 are sensitive to most combustible gases (reducing gases), they are also sensitive to humidity (moisture), so that there is no detected gas due to changes in humidity. In some cases, the concentration of the gas to be detected cannot be known because the concentration of the gas is superimposed on the output of the gas even when the gas is present.
【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, Japanese Patent Application Laid-Open No. Sho 60-14148 discloses a semiconductor gas sensor in which the same metal oxide semiconductor as a sensing element is used as an oxidation catalyst layer in order to reduce the influence of atmospheric humidity. And a sensor using this as a comparison element. But this γ
-Oxidation catalysts composed of metal catalysts such as Pt and Pd supported on alumina have a problem that they deteriorate significantly with time and lack 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。Japanese Unexamined Patent Publication (Kokai) No. 63-171352 discloses a method in which molybdenum oxide and tungsten oxide are added to a metal oxide semiconductor.
Japanese Patent Publication No. 305239 describes that a titanium compound is added to a metal oxide semiconductor to improve the humidity dependency of a semiconductor gas sensor. However, any of the means has a sufficient effect 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 to eliminate or reduce the influence of the gas sensor on humidity, but all of them have drawbacks and are not satisfactory.
【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-mentioned drawbacks, and is easy to manufacture.
An object of the present invention is to provide a gas sensor that can accurately measure a gas concentration without being affected by humidity and that has excellent temporal stability.
【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。A gas sensor according to the present invention comprises:
A pair of gas sensing elements are arranged in independent spaces, one space is open to the gas to be detected, and the opening in the other space is covered with a water vapor permeable and gas impermeable film body to be detected. It is characterized by. As the gas detection element,
Thermal conductivity of gas using a semiconductor element that detects gas concentration by resistance change of metal oxide semiconductor, a contact combustion element that detects combustion heat of flammable gas by catalyst, or a heat-resistant material that does not react with the gas to be detected Can be used. That is, the gas sensor of the present invention can be applied to any of a semiconductor gas sensor, a contact combustion gas sensor, and a thermal conductivity gas sensor. As the water-vapor-permeable and gas-impermeable film to be detected, a fluororesin-based ion exchange membrane or a hollow fiber membrane can be used.
【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。In the gas sensor of the present invention, by adopting the above-described configuration, the pair of gas sensing elements is always exposed to the same humidity condition, and is substantially unaffected or ignored by the humidity. It is possible to do it. Further, since the output difference between the pair of gas detection elements is extracted, it is possible to compensate for a change with 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 PREFERRED EMBODIMENTS 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. Each of the pair of gas detection elements 61 preferably has the same configuration. In the case of a semiconductor gas sensor, a metal oxide semiconductor 62 (for example, SnO 2 , ZnO, or the like) that detects the concentration of a gas to be detected by a change in resistance value is used. It is composed of a heater 63 (for example, a platinum wire) for heating this, and this heater 63 also serves as an electrode for extracting 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, or the like) is supported on a carrier such as alumina instead of a metal oxide semiconductor is used.
Used as In the case of a 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. Comparison element 65 is a sensor housing
The opening 67 of 66 is covered with a film body 68 serving as a gas blocking layer that is permeable to water vapor and impermeable to the gas to be detected. Examples of the membrane 68 include a fluororesin-based ion exchange membrane such as Nafion (trademark, manufactured by DuPont), Flemion (trademark, manufactured by Asahi Glass Co., Ltd.), Ac
An iplex (trade name, manufactured by Asahi Kasei Corporation) or the like, or a hollow fiber membrane capable of separating a gas to be detected from water vapor can be used. On the other hand, the opening 67 of the sensor housing 66 of the detection element section 64 is left open, and the opening of the detection element section 64 and the opening of the comparison element section 65 are arranged in the gas ventilation path 69 so as to be exposed to the same detection target gas atmosphere. I 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-mentioned semiconductor type gas sensor, catalytic combustion type gas sensor, or thermal conductivity type 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 unit 21 and the comparison element unit 22 are connected in series, the opposite-side resistors 23 and 24 are connected in parallel with this, 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 a 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 element 48 is open to the gas to be detected, and this is referred to as a detection element 73. The opening of the housing of the other element 48 is covered with a film 74 serving as a gas blocking layer that is permeable to water vapor and impermeable to the gas to be detected. The detection element section 73 and the comparison element section 75 are exposed to the same detection target gas. 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。FIG. 8 and FIG. 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 having no film body 68. FIG. 8 shows the output of Air and the gas to be detected CH 4 (200 ppm) of the semiconductor gas sensor of the present invention, that is, 26-27 in FIG.
The potential difference between them is shown. Figure 9 is a Air and output of the detection target gas CH 4 in the conventional semiconductor gas sensor (using the fixed resistance as compared 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 greatly fluctuates due to a change in relative humidity. However, as shown in FIG. 8, the air output of the semiconductor gas sensor of the present invention is affected by the humidity. It was hardly affected, showed 0 regardless of humidity, and the 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 performed for about 6 months. The result is shown in FIG. Figure
Reference numeral 10 denotes a value obtained by converting the sensor output into the concentration of CH 4, which is a detection target gas, and the indication value Air (zero) when outdoor air is continuously ventilated and the detection target gas (200 ppm CH 4 ) are periodically determined. The values indicated by the sensor when air was ventilated are shown (○ and ●). Also, changes in temperature and relative humidity around the sensor are shown. As shown in FIG. 10, Air indicated value of the conventional semiconductor gas sensor, i.e. zero is changed with changes in temperature and relative humidity, and also changes indicated value of the CH 4 conversion with it I have. On the other hand, in the semiconductor gas sensor of the present invention, both the indicated air value and the indicated CH 4 value are very stable without being affected by the temperature and the 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。Semiconductor gas sensors are inexpensive, have a long service life, and have a feature of being able to detect early leakage due to their high sensitivity, and are widely used as stationary type sensors for detecting a flammable gas or the like. In a conventional semiconductor gas sensor, an instruction is given depending on changes in ambient temperature and humidity, and therefore, the alarm concentration has to 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 is changing up 180ppm in CH 4 conversion. At this time, if the alarm concentration setting is 180 ppm or less, an alarm is issued due to the influence of the ambient temperature and humidity even though CH 4 as the detection target gas does not exist, and an erroneous alarm is issued. However, the semiconductor gas sensor of the present invention is not affected by the temperature and humidity as shown in FIG. 10 and can accurately detect the detection target gas, and the zero point indicated value hardly changes.
The alarm concentration can be set to a lower value (for example, 100 ppm) than before, and further early detection of gas leakage becomes possible.
【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 free from the influence of 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 illustrating 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 illustrating 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 a change in sensor output with respect to a change 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 a change in sensor output with respect to a change 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 according to the present invention and a conventional gas sensor.
It is a graph which shows the result of a 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 ... comparison element 23, 24 ... opposite side resistance 25 ... power supply 31 ... insulator Substrates 32, 42, 53, 63 ... heater 41 ... insulating tube 52 ... fixed resistor 64, 73 ... sensing element 65 ... comparison element 66, 71 ... sensor housing 68, 74 ... membrane 69 ... gas vent
───────────────────────────────────────────────────── フロントページの続き (72)発明者 中村 仁 神奈川県川崎市中原区宮内４丁目９番35号 光明理化学工業株式会社研究所内 Ｆターム(参考） 2G046 AA01 AA02 AA19 BA01 BA02 BA03 BB02 BE02 BF01 DB05 DC12 EB01 FA01 FB02 FE39 FE48 2G060 AA01 AB03 AB17 AB18 AB20 AB21 AE19 AF07 AF09 AG11 BA01 BA03 BA05 BB02 BB05 BB12 BB15 BD04 HA04 HB06 HC04 HC07 KA01 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Jin Nakamura 4-9-35 Miyauchi, Nakahara-ku, Kawasaki-shi, Kanagawa F-term in the laboratory of Komei Rika Kogyo Co., Ltd. 2G046 AA01 AA02 AA19 BA01 BA02 BA03 BB02 BE02 BF01 DB05 DC12 EB01 FA01 FB02 FE39 FE48 2G060 AA01 AB03 AB17 AB18 AB20 AB21 AE19 AF07 AF09 AG11 BA01 BA03 BA05 BB02 BB05 BB12 BB15 BD04 HA04 HB06 HC04 HC07 KA01
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 independent spaces, and one space is opened to a gas to be detected.
A gas sensor, wherein an opening of the other space is covered with a water-permeable and gas-impermeable film body 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 said 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 comprises 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 impermeable to the detection object is a fluororesin-based 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 impermeable to the detection object is a hollow fiber membrane.
Priority Applications (1)
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|---|---|---|---|
| JP31004299A JP3385248B2 (en) | 1999-10-29 | 1999-10-29 | Gas sensor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31004299A JP3385248B2 (en) | 1999-10-29 | 1999-10-29 | Gas sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2001124716A true JP2001124716A (en) | 2001-05-11 |
| JP3385248B2 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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