JPH09105732A - Contact combustion type gas sensor - Google Patents
Contact combustion type gas sensorInfo
- Publication number
- JPH09105732A JPH09105732A JP26456095A JP26456095A JPH09105732A JP H09105732 A JPH09105732 A JP H09105732A JP 26456095 A JP26456095 A JP 26456095A JP 26456095 A JP26456095 A JP 26456095A JP H09105732 A JPH09105732 A JP H09105732A
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- Prior art keywords
- gas
- platinum
- nickel
- detection element
- gas sensor
- 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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- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、接触燃焼式ガスセ
ンサに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic combustion type gas sensor.
【０００２】[0002]
【従来の技術】従来、ガス器具の不完全燃焼または不点
火を検出するために、可燃性気体の存在を検知する手段
として、接触燃焼式ガスセンサが知られている。前記接
触燃焼式ガスセンサは、半導体表面のガス脱吸着による
半導体の抵抗変化によりガスを検知する半導体式ガスセ
ンサに比較して、そのガス検知特性が長期に亘り安定し
ているため、可燃性ガス、特に一酸化炭素の検知用とし
て広く用いられている。2. Description of the Related Art Conventionally, a catalytic combustion type gas sensor has been known as a means for detecting the presence of combustible gas in order to detect incomplete combustion or misfire of a gas appliance. The catalytic combustion type gas sensor, as compared with a semiconductor type gas sensor that detects a gas by a resistance change of the semiconductor due to gas desorption of the semiconductor surface, since the gas detection characteristics are stable for a long period of time, a flammable gas, particularly It is widely used for detecting carbon monoxide.
【０００３】前記従来の接触燃焼式ガスセンサは、表面
を白金またはパラジウムで被覆した白金線からなる電気
抵抗体をガス検知素子とするものである。このようなガ
ス検知素子は所定温度に保持された状態で可燃性気体が
接触すると、該可燃性気体が前記白金またはパラジウム
を触媒として燃焼し、その燃焼熱により前記電気抵抗体
が加熱され、電気抵抗が変化する。そこで、前記電気抵
抗体に通電しておき、前記前記電気抵抗体の加熱時の電
気抵抗の変化量を検出することにより、可燃性気体の濃
度を検知するものである。The conventional catalytic combustion gas sensor uses a platinum wire whose surface is coated with platinum or palladium as an electric resistance element as a gas detection element. When a combustible gas comes into contact with such a gas detection element while being maintained at a predetermined temperature, the combustible gas burns using the platinum or palladium as a catalyst, and the heat of combustion heats the electric resistor to generate electricity. The resistance changes. Therefore, the electric resistance is energized and the amount of change in the electric resistance when the electric resistance is heated is detected to detect the concentration of the combustible gas.
【０００４】前記接触燃焼式ガスセンサは、前記ガス検
知素子に可燃性気体が接触したときに触媒活性を高めて
燃焼し易くするために、前記ガス検知素子が３００℃以
上の温度に保持されるようになっている。ところが、前
記接触燃焼式ガスセンサは、ガス器具が設置されている
室内でシリコーンオイルを含むヘアスプレーが使用され
たり、該ガス器具のガス配管のシール剤に珪素樹脂が使
用されているときには、ガス検知感度が著しく低下する
との問題がある。In the catalytic combustion type gas sensor, when the combustible gas comes into contact with the gas detecting element, the gas detecting element is kept at a temperature of 300 ° C. or higher in order to enhance the catalytic activity and facilitate combustion. It has become. However, the catalytic combustion type gas sensor detects gas when a hair spray containing silicone oil is used in the room where the gas appliance is installed, or when a silicone resin is used as a sealant for the gas pipe of the gas appliance. There is a problem that the sensitivity is significantly reduced.
【０００５】前記問題は、シリコーンオイル等の低重合
度の珪素樹脂が３００℃以上の温度に保持されている前
記ガス検知素子に接触して、重合反応を起こし、生成し
た高重合度の珪素樹脂あるいは該珪素樹脂がさらに高温
下で酸化されて生成したガラス質の二酸化珪素により前
記触媒の表面が覆われ、前記触媒と前記可燃性気体との
接触が遮断されるためと考えられる。そこで、前記問題
を解決するために、前記接触燃焼式ガスセンサを前記ガ
ス検知素子の温度が３００℃以上にならないようにし
て、使用することが考えられる。The problem is that a low polymerization silicone resin such as silicone oil is brought into contact with the gas detection element held at a temperature of 300 ° C. or higher to cause a polymerization reaction, and a high polymerization silicone resin produced. Alternatively, it is considered that the surface of the catalyst is covered with glassy silicon dioxide produced by further oxidation of the silicon resin at a higher temperature, and the contact between the catalyst and the combustible gas is blocked. Therefore, in order to solve the above problem, it is conceivable to use the catalytic combustion type gas sensor while keeping the temperature of the gas detection element not higher than 300 ° C.
【０００６】しかしながら、表面を白金またはパラジウ
ムで被覆した白金線からなる電気抵抗体をガス検知素子
とする従来の接触燃焼式ガスセンサでは、ガス検知素子
の温度が３００℃未満の低温のときには可燃性ガスの存
在を検知するために十分な電気抵抗の変化量が得られな
いとの不都合がある。[0006] However, in the conventional catalytic combustion type gas sensor which uses an electric resistor made of a platinum wire whose surface is coated with platinum or palladium as a gas detecting element, when the temperature of the gas detecting element is lower than 300 ° C, a combustible gas is generated. However, there is an inconvenience that it is not possible to obtain a sufficient amount of change in electric resistance for detecting the presence of
【０００７】[0007]
【発明が解決しようとする課題】本発明は、かかる不都
合を解消して、ガス検知素子の温度が３００℃未満の低
温のときにも可燃性ガスの存在を検知するために十分な
電気抵抗の変化量が得られる接触燃焼式ガスセンサを提
供することを目的とする。DISCLOSURE OF THE INVENTION The present invention eliminates such inconvenience, and has sufficient electric resistance for detecting the presence of flammable gas even when the temperature of the gas detecting element is low temperature of less than 300.degree. An object of the present invention is to provide a catalytic combustion type gas sensor that can obtain the amount of change.
【０００８】[0008]
【課題を解決するための手段】かかる目的を達成するた
めに、本発明の接触燃焼式ガスセンサは、表面を白金ま
たはパラジウムで被覆した金属からなる電気抵抗体をガ
ス検知素子とし、所定温度に保持された該ガス検知素子
に接触した可燃性気体を該白金またはパラジウムを触媒
として燃焼せしめ、該可燃性気体の燃焼熱による該電気
抵抗体の電気抵抗の変化を検出することにより可燃性気
体の濃度を検知する接触燃焼式ガスセンサにおいて、該
電気抵抗体は、鉄またはニッケルであることを特徴とす
る。In order to achieve the above object, the catalytic combustion type gas sensor of the present invention uses an electric resistor made of a metal whose surface is coated with platinum or palladium as a gas detection element and is maintained at a predetermined temperature. The combustible gas in contact with the gas detecting element is burned by using the platinum or palladium as a catalyst, and the change in the electric resistance of the electric resistor due to the combustion heat of the combustible gas is detected to detect the concentration of the combustible gas. In the catalytic combustion gas sensor for detecting, the electric resistor is iron or nickel.
【０００９】かかる手段によれば、電気抵抗体として白
金よりも電気抵抗率の温度による変化率が大きい鉄また
はニッケルを用いるので、該ガス検知素子の温度を３０
０℃未満の低温としたときにも、可燃性ガスの存在を検
知するために十分な電気抵抗の変化を得ることができ
る。According to such means, since iron or nickel, which has a larger rate of change in electric resistivity with temperature than platinum, is used as the electric resistor, the temperature of the gas detecting element is set to 30.
Even when the temperature is lower than 0 ° C., it is possible to obtain a sufficient change in electric resistance for detecting the presence of flammable gas.
【００１０】前記電気抵抗体は細線をコイル状に成形し
て用いられるが、本発明の接触燃焼式ガスセンサでは、
前記電気抵抗体が鉄であるときには、その表面がニッケ
ルで被覆されていて、該ニッケルの被覆上にさらに白金
またはパラジウムが被覆されている構成とすることによ
り、鉄が反復使用によって酸化して抵抗が高くなっても
通電時の発熱による断線を防止することができる。The electric resistor is used by forming a thin wire into a coil shape. In the catalytic combustion type gas sensor of the present invention,
When the electric resistor is iron, the surface of the electric resistor is coated with nickel, and platinum or palladium is further coated on the nickel coating, whereby the iron is oxidized by repeated use and resistance is increased. Even if the temperature rises, it is possible to prevent disconnection due to heat generation during energization.
【００１１】また、本発明の接触燃焼式ガスセンサは、
一酸化炭素、水素及び可燃性気体を検知するセンサであ
るので、都市ガスまたは液化石油ガス（ＬＰＧ）を燃料
とするガス器具の不完全燃焼または不点火を検知するた
めに好適に用いられる。Further, the catalytic combustion type gas sensor of the present invention is
Since it is a sensor for detecting carbon monoxide, hydrogen and combustible gas, it is preferably used for detecting incomplete combustion or misfire of gas appliances using city gas or liquefied petroleum gas (LPG) as fuel.
【００１２】[0012]
【発明の実施の形態】次に、添付の図面を参照しながら
本発明の実施の一形態についてさらに詳しく説明する。
図１（ａ）は本発明の接触燃焼式ガスセンサの回路構成
を示す回路図、図１（ｂ）は図１（ａ）示のガス検知素
子の一部断面を示す斜視図、図２は電気抵抗体となる金
属の電気抵抗率と温度との関係を示すグラフである。BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described in more detail with reference to the accompanying drawings.
1A is a circuit diagram showing a circuit configuration of a catalytic combustion type gas sensor of the present invention, FIG. 1B is a perspective view showing a partial cross section of the gas detection element shown in FIG. 1A, and FIG. It is a graph which shows the relationship between the electrical resistivity of the metal used as a resistor, and temperature.
【００１３】図１（ａ）示のように、本発明の接触燃焼
式ガスセンサ１は、都市ガスまたは液化石油ガス（ＬＰ
Ｇ）を燃料とするガス器具の不完全燃焼または不点火を
検知するために用いられるものであって、その回路構成
は、ガス検知素子２と温度補償素子３とが、他の抵抗４
ａ，４ｂとともにブリッジ５を形成するとともに、ブリ
ッジ５に電力を供給する電源６と、ガス検知素子２で検
知されるガス濃度を示すガス濃度指示メータ７と、検知
されたガスの濃度が所定の基準を超えたときに警報を発
出する警報手段８とを備えている。前記ガス濃度指示メ
ータ７はブリッジ５の固定接点Ａと可動接Ｂとに接続さ
れており、前記警報手段８はガス濃度指示メータ７と並
列に接続されている。As shown in FIG. 1 (a), the catalytic combustion type gas sensor 1 of the present invention comprises a city gas or a liquefied petroleum gas (LP).
G) is used as a fuel for detecting incomplete combustion or misfire of a gas appliance, and its circuit configuration is such that the gas detecting element 2 and the temperature compensating element 3 have different resistances from each other.
The bridge 5 is formed together with a and 4b, the power source 6 for supplying electric power to the bridge 5, the gas concentration indicator 7 for indicating the gas concentration detected by the gas detection element 2, and the concentration of the detected gas are predetermined. An alarm means 8 for issuing an alarm when the standard is exceeded is provided. The gas concentration indicator meter 7 is connected to the fixed contact A and the movable contact B of the bridge 5, and the alarm means 8 is connected in parallel with the gas concentration indicator meter 7.
【００１４】前記ガス検知素子２は、図１（ｂ）示のよ
うに、金属の細線をコイル状に成形した電気抵抗体９の
表面に、電気メッキ等により形成された白金またはパラ
ジウムの被覆層１０を備えている。本発明の接触燃焼式
ガスセンサ１では、前記電気抵抗体９として、鉄（Ｆ
ｅ）またはニッケル（Ｎｉ）を用いる。As shown in FIG. 1 (b), the gas detecting element 2 has a platinum or palladium coating layer formed by electroplating or the like on the surface of an electric resistor 9 formed by forming a metal thin wire into a coil shape. Equipped with 10. In the catalytic combustion type gas sensor 1 of the present invention, as the electric resistor 9, iron (F
e) or nickel (Ni) is used.
【００１５】鉄及びニッケルは、図２示のように、２０
０℃以上の温度では白金（Ｐｔ）よりも電気抵抗率の温
度による変化が大きいので、３００℃未満の温度で使用
される前記ガス検知素子の前記電気抵抗体９に適してい
る。前記電気抵抗体９に用いる鉄としては、例えば純度
９９．５％のようなものを挙げることができる。また、
前記電気抵抗体９に用いるニッケルとしては、例えば純
度９９．７％のようなものを挙げることができる。Iron and nickel, as shown in FIG.
At a temperature of 0 ° C. or higher, the change in electrical resistivity with temperature is larger than that of platinum (Pt), and thus it is suitable for the electrical resistor 9 of the gas detection element used at a temperature of less than 300 ° C. Examples of iron used for the electric resistor 9 include those having a purity of 99.5%. Also,
Examples of nickel used for the electric resistor 9 include those having a purity of 99.7%.
【００１６】尚、図２示の銅（Ｃｕ）は参考のために示
したものであり、良導体であって、白金よりも電気抵抗
率の温度による変化が小さいので、前記電気抵抗体９と
しては好ましくない。The copper (Cu) shown in FIG. 2 is shown as a reference and is a good conductor, and the change in electric resistivity with temperature is smaller than that of platinum. Not preferable.
【００１７】前記電気抵抗体９が鉄であるときには、反
復使用によって酸化して抵抗が高くなる傾向があるの
で、通電時の発熱による断線を防止するために、その表
面をニッケルで被覆し、該ニッケルの被覆上に前記白金
またはパラジウムを被覆する。前記ニッケルの被覆は安
定であり、表面酸化を防止するので、反復使用しても鉄
の電気抵抗が変化しない。前記電気抵抗体９の鉄に対す
るニッケル被覆は、例えば、無電解メッキにより行う。When the electric resistor 9 is iron, it tends to be oxidized by repeated use to increase the resistance. Therefore, in order to prevent disconnection due to heat generation during energization, its surface is coated with nickel. The platinum or palladium is coated on the nickel coating. The nickel coating is stable and prevents surface oxidation so that the electrical resistance of iron does not change with repeated use. The iron of the electric resistor 9 is coated with nickel by, for example, electroless plating.
【００１８】また、前記鉄の断線を防止するためには、
前記ニッケルの被覆と同様に、鉄の表面に酸化を防止で
きる被膜を構成すればよく、触媒である前記白金または
パラジウムの被覆を、例えば、パラジウムや白金の薄膜
を表面に形成し、さらにその表面に触媒としての白金黒
やパラジウム黒を付着させるようにして形成してもよ
い。In order to prevent the breakage of the iron,
Similar to the nickel coating, it is sufficient to form a coating capable of preventing oxidation on the surface of iron, and the platinum or palladium coating as a catalyst, for example, a thin film of palladium or platinum is formed on the surface, and the surface thereof is further formed. It may be formed by attaching platinum black or palladium black as a catalyst to.
【００１９】次に、前記接触燃焼式ガスセンサ１の作動
について説明する。まず、接触燃焼式ガスセンサ１は、
図示しない外部ヒータ等によりガス検知素子２が所定温
度に保持されている状態で、電源６からブリッジ５に電
力を供給して、ガス検知素子２の前記金属の細線からな
る電気抵抗体９に通電する。ガス検知素子２は前記のよ
うにその表面に白金またはパラジウムの被覆層１０を備
える電気抵抗体９からなるので、前記のように所定温度
に保持されているガス検知素子２に一酸化炭素等の可燃
性気体が接触すると、該可燃性ガスが前記被覆層１０の
白金またはパラジウムを触媒として燃焼し、該可燃性気
体の燃焼熱により電気抵抗体９の抵抗が変化する。Next, the operation of the catalytic combustion type gas sensor 1 will be described. First, the catalytic combustion type gas sensor 1
While the gas detection element 2 is kept at a predetermined temperature by an external heater or the like (not shown), power is supplied from the power supply 6 to the bridge 5 to energize the electric resistor 9 made of the thin metal wire of the gas detection element 2. To do. Since the gas detecting element 2 is composed of the electric resistor 9 having the platinum or palladium coating layer 10 on the surface thereof as described above, the gas detecting element 2 which is maintained at the predetermined temperature as described above is made of carbon monoxide or the like. When the flammable gas comes into contact with the flammable gas, the flammable gas burns using platinum or palladium of the coating layer 10 as a catalyst, and the resistance of the electric resistor 9 changes due to the combustion heat of the flammable gas.
【００２０】そこで、接触燃焼式ガスセンサ１は、ブリ
ッジ５の可動接点Ｂを移動させて、電気抵抗体９の電気
抵抗の変化量をブリッジ５の接点Ａ，Ｂ間の電圧差とし
て検出するようになっている。前記のようにして検出さ
れた電気抵抗体９の電気抵抗変化量はガス濃度に比例す
るので、前記電気抵抗変化量から換算されたガス濃度が
ガス濃度指示メータ７に直接示されるとともに、警報手
段８に出力される。前記警報手段８は、図示しない制御
手段を備えており、検出されたガスの濃度が所定の基準
を超えると、該制御手段が前記ガス器具に不完全燃焼ま
たは不点火が発生したものと判断し、電子音等の聴覚的
手段または光電的表示等の視覚的手段を介して警報を発
出するようになっている。Therefore, the catalytic combustion type gas sensor 1 moves the movable contact B of the bridge 5 so as to detect the amount of change in the electric resistance of the electric resistor 9 as a voltage difference between the contacts A and B of the bridge 5. Has become. Since the electric resistance change amount of the electric resistor 9 detected as described above is proportional to the gas concentration, the gas concentration converted from the electric resistance change amount is directly indicated on the gas concentration indicating meter 7 and an alarm means is provided. 8 is output. The alarm means 8 includes a control means (not shown), and when the detected gas concentration exceeds a predetermined standard, the control means determines that incomplete combustion or misfire has occurred in the gas appliance. An alarm is issued via an auditory means such as electronic sound or a visual means such as a photoelectric display.
【００２１】次に、本発明の実施例及び比較例について
説明する。Next, examples and comparative examples of the present invention will be described.
【００２２】[0022]
【実施例１】図３は接触燃焼式ガスセンサに用いるガス
検知素子のガス検知性能を測定するための実験装置の構
成を示す説明的断面図であり、図４乃至図６は本発明の
実施例及び比較例のガス検知素子における一酸化炭素濃
度と電気抵抗値の変化量との関係を示すグラフであり、
図４は実施例１のガス検知素子の場合、図５は実施例２
のガス検知素子の場合、図６は比較例のガス検知素子の
場合をそれぞれ示す。また、図７乃至図１０は所定の温
度における各実施例及び比較例の接触燃焼式ガスセンサ
の一酸化炭素濃度と電気抵抗値の変化量との関係を示す
グラフであり、図７は２３０℃の場合、図８は３００℃
の場合、図９は３５０℃の場合、図１０は４００℃の場
合をそれぞれ示す。Example 1 FIG. 3 is an explanatory sectional view showing the structure of an experimental apparatus for measuring the gas detection performance of a gas detection element used in a catalytic combustion type gas sensor, and FIGS. 4 to 6 are examples of the present invention. And is a graph showing the relationship between the carbon monoxide concentration and the amount of change in the electrical resistance value in the gas detection element of the comparative example,
FIG. 4 shows the case of the gas detecting element of Example 1, and FIG. 5 shows Example 2
6 shows the case of the gas detection element of Comparative Example. 7 to 10 are graphs showing the relationship between the concentration of carbon monoxide and the amount of change in electric resistance value of the catalytic combustion type gas sensors of Examples and Comparative Examples at a predetermined temperature. In case of Fig.8, 300 ℃
9 shows the case of 350 ° C., and FIG. 10 shows the case of 400 ° C.
【００２３】本実施例では、直径０．１ｍｍ、長さ１０
０ｍｍのコイル状ニッケル線（純度９９．７％）を用意
し、その表面を白金黒で被覆した。In this embodiment, the diameter is 0.1 mm and the length is 10 mm.
A 0 mm coil-shaped nickel wire (purity 99.7%) was prepared, and its surface was covered with platinum black.
【００２４】白金黒による被覆は、電気メッキ法によ
り、次のようにして行った。まず、前記ニッケル線をア
セトン中に浸漬して１分間超音波洗浄して脱脂したの
ち、常温の水に１分間浸漬して水洗した。次に、前記ニ
ッケル線を常温のクロム混酸に１分間浸漬して酸洗した
のち、常温の水に１分間浸漬して水洗した。The coating with platinum black was performed by the electroplating method as follows. First, the nickel wire was immersed in acetone and ultrasonically cleaned for 1 minute to degrease it, and then immersed in water at room temperature for 1 minute and washed with water. Next, the nickel wire was immersed in chromium mixed acid at room temperature for 1 minute to be pickled, and then immersed in water at room temperature for 1 minute to be washed with water.
【００２５】次に、電極を備えた電気メッキ槽にメッキ
液として常温のヘキサクロロ白金酸水溶液を供給し、前
記のようにして洗浄した前記ニッケル線を該メッキ液に
浸漬して、該ニッケル線と前記電極との間に５Ｖの電圧
を印加するとともに０．４〜１５．５ｍＡの電流を３分
間通電する操作を２回行うことにより、前記ニッケル線
の表面を白金黒で被覆した。次に、前記白金黒で被覆さ
れたニッケル線を、常温の水に１分間以上浸漬して水洗
した。Next, a hexachloroplatinic acid aqueous solution at room temperature is supplied as a plating solution to an electroplating tank equipped with electrodes, and the nickel wire washed as described above is immersed in the plating solution to form the nickel wire. The surface of the nickel wire was coated with platinum black by applying a voltage of 5 V between the electrodes and applying an electric current of 0.4 to 15.5 mA for 3 minutes twice. Next, the nickel wire coated with platinum black was immersed in water at room temperature for 1 minute or more and washed with water.
【００２６】次に、電極を備えた電解槽に電解液として
１Ｎ硫酸を供給し、前記白金黒で被覆されたニッケル線
を該電解液に浸漬して、該ニッケル線と前記電極との間
に５Ｖの電圧を印加するとともに０．５〜１５ｍＡの電
流を１分間通電する操作を２回行うことにより、前記ニ
ッケル線を電解洗浄した。Next, 1N sulfuric acid was supplied as an electrolytic solution to an electrolytic cell equipped with an electrode, the nickel wire coated with platinum black was immersed in the electrolytic solution, and between the nickel wire and the electrode. The nickel wire was electrolytically cleaned by applying a voltage of 5 V and applying a current of 0.5 to 15 mA for 1 minute twice.
【００２７】次に、前記白金黒で被覆されたニッケル線
を、常温の水に１分間以上浸漬して水洗し、前記ニッケ
ル線に付着している水をアセトンで置換したのち、温風
乾燥した。前記電気メッキにより、前記ニッケル線の表
面には、０．９〜１．１ｍｇの白金黒が付着している。Next, the nickel wire coated with platinum black was immersed in water at room temperature for 1 minute or more to wash with water, the water adhering to the nickel wire was replaced with acetone, and then dried with warm air. . Due to the electroplating, 0.9 to 1.1 mg of platinum black is attached to the surface of the nickel wire.
【００２８】次に、前記白金黒で被覆されたニッケル線
を１０-3トールの減圧下で４００℃に１時間保持する熱
処理を施し、図１（ｂ）示のガス検知素子２を製造し
た。Next, the nickel wire coated with platinum black was subjected to a heat treatment of holding it at 400 ° C. for 1 hour under a reduced pressure of 10 −3 Torr to manufacture a gas detecting element 2 shown in FIG. 1 (b).
【００２９】次に、前記ガス検知素子２のガス検知性能
を図３示の装置を用いて評価した。図３示の装置は、ガ
ス検知素子２を図１（ａ）及び図１（ｂ）示の接触燃焼
式ガスセンサ１に使用することを想定して、所定温度に
保持されたガス検知素子２の一酸化炭素検知性能を測定
するものであって、前記ガス検知素子２を保持する密閉
されたムライト管１１と、ムライト管１１を収容する電
気炉１２とからなる。Next, the gas detection performance of the gas detection element 2 was evaluated using the apparatus shown in FIG. The apparatus shown in FIG. 3 assumes that the gas detection element 2 is used in the catalytic combustion type gas sensor 1 shown in FIGS. 1 (a) and 1 (b), and the gas detection element 2 is maintained at a predetermined temperature. The carbon monoxide detection performance is measured, and includes a sealed mullite tube 11 that holds the gas detection element 2 and an electric furnace 12 that houses the mullite tube 11.
【００３０】ムライト管１１は、一方の口１１ａに可燃
性ガスとしての一酸化炭素導入手段１３と空気導入手段
１４とを備え、他方の口１１ｂに一酸化炭素分析器１５
が接続されている。また、一方の口１１ａには、ガス検
知素子２の温度を測定する温度計１６が接続されてい
る。The mullite tube 11 is provided with a carbon monoxide introducing means 13 and an air introducing means 14 as flammable gas at one port 11a, and a carbon monoxide analyzer 15 at the other port 11b.
Is connected. Further, a thermometer 16 for measuring the temperature of the gas detection element 2 is connected to the one port 11a.
【００３１】電気炉１２は、ＰＩＤ温度コントローラ１
７を備え、炉内の温度を調整できるようになっている。
また、前記ガス検知素子２は、ムライト管１１の口１１
ａ，１１ｂを介して定電流源１８に接続されており、ガ
ス検知素子２と直列に電流計１９，並列に電圧計２０が
接続されている。The electric furnace 12 is a PID temperature controller 1
7 is provided so that the temperature inside the furnace can be adjusted.
Further, the gas detection element 2 is provided with a port 11 of the mullite tube 11.
It is connected to a constant current source 18 via a and 11b, and an ammeter 19 is connected in series with the gas detection element 2 and a voltmeter 20 is connected in parallel.
【００３２】前記ガス検知素子２のガス検知性能は、前
記電気炉１２によりガス検知素子２の温度を２３０℃、
３００℃、３５０℃、４００℃の各温度に保持した状態
で、まず、空気中でガス検知素子２に定電流源１８から
１０ｍＡの一定電流を流したときのガス検知素子２両端
の電圧を電圧計２０で測定することにより、前記各温度
における電気抵抗体９の電気抵抗（Ｒ1 ）を求めた。The gas detection performance of the gas detection element 2 is that the temperature of the gas detection element 2 is 230 ° C. by the electric furnace 12.
With the temperature kept at 300 ° C., 350 ° C., and 400 ° C., first, the voltage across the gas sensing element 2 when a constant current of 10 mA was passed from the constant current source 18 to the gas sensing element 2 in the air was measured. By measuring with a total of 20, the electric resistance (R 1 ) of the electric resistor 9 at each temperature was obtained.
【００３３】次に、前記各温度において、一酸化炭素導
入手段１３及び空気導入手段１４により、一酸化炭素が
それぞれ５００ｐｐｍ、１０００ｐｐｍ、１５００ｐｐ
ｍ、２０００ｐｐｍ、２５００ｐｐｍ混入した空気をム
ライト管１１内に導入し、ムライト管１１内の雰囲気を
各一酸化炭素濃度の空気で十分に置換したのち、流入ガ
スを遮断し、前記と全く同じ方法で前記各一酸化炭素濃
度に対応する電気抵抗体９の電気抵抗（Ｒ2 ）を求め
た。そして、前記各温度ごとに、一酸化炭素が混入した
空気中での電気抵抗体９の電気抵抗（Ｒ2 ）と、一酸化
炭素を含まない空気中での電気抵抗（Ｒ1 ）との差を求
め、一酸化炭素濃度に対応する電気抵抗体９の電気抵抗
変化量（ΔＲ＝Ｒ2 −Ｒ1 、単位：ｍΩ）を求めた。結
果を下記表１及び図４に示す。Next, at each of the above-mentioned temperatures, the carbon monoxide introducing means 13 and the air introducing means 14 respectively add 500 ppm, 1000 ppm and 1500 pp of carbon monoxide.
m, 2000 ppm, 2500 ppm mixed air was introduced into the mullite tube 11, and the atmosphere in the mullite tube 11 was sufficiently replaced with air of each carbon monoxide concentration, and then the inflowing gas was shut off. The electric resistance (R 2 ) of the electric resistor 9 corresponding to each carbon monoxide concentration was obtained. The difference between the electric resistance (R 2 ) of the electric resistor 9 in the air mixed with carbon monoxide and the electric resistance (R 1 ) in the air not containing carbon monoxide for each temperature. Then, the amount of change in electric resistance of the electric resistor 9 (ΔR = R 2 −R 1 , unit: mΩ) corresponding to the carbon monoxide concentration was obtained. The results are shown in Table 1 below and FIG.
【００３４】[0034]
【表１】 [Table 1]
【００３５】[0035]
【実施例２】本実施例では、直径０．１ｍｍ、長さ１０
０ｍｍのコイル状鉄線（純度９９．７％）を用意し、そ
の表面を、まずニッケルで被覆し、次いで該ニッケルの
被覆上にさらに白金黒の被覆を施した。Example 2 In this example, the diameter is 0.1 mm and the length is 10 mm.
A 0 mm coiled iron wire (purity 99.7%) was prepared, and the surface thereof was first coated with nickel, and then a platinum black coating was further applied on the nickel coating.
【００３６】ニッケルによる被覆は、無電解メッキ法に
より、次のようにして行った。まず、前記鉄線をアセト
ン中に浸漬して１分間超音波洗浄して脱脂したのち、常
温の水に１分間浸漬して水洗した。次に、前記鉄線を常
温の２０％塩酸に１分間浸漬して酸洗したのち、常温の
水に浸漬して１分間以内で水洗した。The coating with nickel was performed by the electroless plating method as follows. First, the iron wire was immersed in acetone, ultrasonically cleaned for 1 minute to degrease, and then immersed in water at room temperature for 1 minute and washed with water. Next, the iron wire was immersed in 20% hydrochloric acid at room temperature for 1 minute to be pickled, then immersed in water at room temperature and washed within 1 minute.
【００３７】次に、前記鉄線を８０℃の無電解ニッケル
メッキ液中に１時間浸漬して、無電解メッキすることに
より、前記鉄線の表面をニッケルで被覆した。次に、前
記ニッケルで被覆された鉄線を、常温の水に５分間以上
浸漬して水洗し、前記鉄線に付着している水をアセトン
で置換する操作を２分間行ったのち温風乾燥し、ニッケ
ルで被覆された鉄線を得た。前記無電解メッキにより、
前記鉄線の表面には、０．４ｍｇのニッケルが１．２μ
ｍの厚さで平滑に付着している。Next, the surface of the iron wire was coated with nickel by immersing the iron wire in an electroless nickel plating solution at 80 ° C. for 1 hour and performing electroless plating. Next, the iron wire coated with nickel is immersed in water at room temperature for 5 minutes or more to wash with water, and the operation of replacing water adhering to the iron wire with acetone is performed for 2 minutes, followed by drying with warm air, An iron wire coated with nickel was obtained. By the electroless plating,
0.4 mg of nickel is 1.2μ on the surface of the iron wire.
It has a thickness of m and adheres smoothly.
【００３８】次に、前記ニッケルで被覆された鉄線の表
面を、実施例１のニッケル線と全く同一の電気メッキ法
により白金黒で被覆した。前記電気メッキにより、前記
ニッケル被覆上には、０．９〜１．１ｍｇの白金黒が付
着している。Next, the surface of the iron wire coated with nickel was coated with platinum black by the same electroplating method as that of the nickel wire of Example 1. By the electroplating, 0.9 to 1.1 mg of platinum black is attached on the nickel coating.
【００３９】次に、前記ニッケル被覆上にさらに白金黒
の被覆が施された鉄線を１０-3トールの減圧下で４００
℃に１時間保持する熱処理を施した後、４００℃で焼き
鈍しを行って、図１（ａ）示のガス検知素子２を製造し
た。Next, an iron wire further coated with platinum black on the nickel coating was heated to 400 at a reduced pressure of 10 -3 Torr.
After heat treatment of holding at 1 ° C. for 1 hour, annealing was performed at 400 ° C. to manufacture the gas detection element 2 shown in FIG.
【００４０】次に、前記ガス検知素子２のガス検知性能
を、図３示の装置を用い、実施例１と全く同じ方法で評
価した。結果を下記表２及び図５に示す。Next, the gas detection performance of the gas detection element 2 was evaluated by the same method as in Example 1 using the apparatus shown in FIG. The results are shown in Table 2 below and FIG.
【００４１】[0041]
【表２】 [Table 2]
【００４２】[0042]
【比較例】本実施例では、直径０．１ｍｍ、長さ１００
ｍｍのコイル状白金線を用意し、その表面を、実施例１
のニッケル線と全く同一の電気メッキ法により白金黒で
被覆した。前記電気メッキにより、前記白金線の表面に
は、０．９〜１．１ｍｇの白金黒が付着している。Comparative Example In this example, the diameter is 0.1 mm and the length is 100 mm.
mm coil-shaped platinum wire was prepared, and the surface thereof was prepared as in Example 1.
It was coated with platinum black by the same electroplating method as the nickel wire. Due to the electroplating, 0.9 to 1.1 mg of platinum black is attached to the surface of the platinum wire.
【００４３】次に、前記白金黒で被覆された白金線を１
０-3トールの減圧下で４００℃に１時間保持する熱処理
を施し、図１（ａ）示のガス検知素子２を製造した。Next, the platinum wire coated with the platinum black is
Heat treatment was carried out at 400 ° C. for 1 hour under a reduced pressure of 0 −3 Torr to manufacture the gas detection element 2 shown in FIG.
【００４４】次に、前記ガス検知素子２のガス検知性能
を、図３示の装置を用い、実施例１と全く同じ方法で評
価した。結果を下記表３及び図６に示す。Next, the gas detection performance of the gas detection element 2 was evaluated by the same method as in Example 1 using the apparatus shown in FIG. The results are shown in Table 3 below and FIG.
【００４５】[0045]
【表３】 [Table 3]
【００４６】前記表１〜３及び図４〜６のデータから、
前記各実施例及び比較例のガス検知素子２によれば、電
気抵抗体９の電気抵抗変化量は一酸化炭素の濃度にほぼ
対応して、一酸化炭素の濃度が低ければ電気抵抗変化量
も小さく、一酸化炭素の濃度が高ければ電気抵抗変化量
も大きくなっており、接触燃焼式ガスセンサに使用でき
ることが明らかである。From the data of Tables 1 to 3 and FIGS.
According to the gas detection elements 2 of the respective examples and comparative examples, the amount of change in electric resistance of the electric resistor 9 substantially corresponds to the concentration of carbon monoxide, and if the concentration of carbon monoxide is low, the amount of change in electric resistance is also small. If the carbon monoxide is small and the concentration of carbon monoxide is high, the electric resistance change amount is also large, and it is clear that it can be used for a catalytic combustion type gas sensor.
【００４７】前記表１〜３及び図４〜６のデータを前記
各温度別にして、図７〜１０にまとめた。図７から、前
記実施例１及び実施例２のガス検知素子２によれば、２
３０℃という３００℃未満の温度に維持されているとき
でも、２５００ｐｐｍ以下の一酸化炭素に対して、電気
抵抗体９が白金からなるガス検知素子２（比較例）より
大きな電気抵抗の変化量が得られることが明らかであ
る。従って、前記実施例１及び実施例２のガス検知素子
２によれば、珪素樹脂の重合反応が進行しにくい温度範
囲で、一酸化炭素等の可燃性気体を検知することができ
る。The data of Tables 1 to 3 and FIGS. 4 to 6 are summarized in FIGS. From FIG. 7, according to the gas detecting elements 2 of the first and second embodiments,
Even when the temperature is maintained at 30 ° C., which is lower than 300 ° C., the amount of change in electrical resistance larger than that of the gas detection element 2 (comparative example) in which the electrical resistor 9 is platinum is 2500 ppm or less of carbon monoxide. It is clear that it can be obtained. Therefore, according to the gas detection element 2 of the first and second embodiments, a combustible gas such as carbon monoxide can be detected in a temperature range in which the polymerization reaction of the silicon resin is unlikely to proceed.
【００４８】また、図８乃至図１０から、前記実施例１
及び実施例２のガス検知素子２によれば、３００℃に維
持されているときの１０００ｐｐｍ以下の一酸化炭素に
対する場合を除いて、前記比較例のガス検知素子２より
大きな電気抵抗の変化量が得られることが明らかであ
る。Further, from FIG. 8 to FIG.
Also, according to the gas detecting element 2 of Example 2, a larger amount of change in electric resistance than that of the gas detecting element 2 of Comparative Example is obtained except for the case of carbon monoxide of 1000 ppm or less when maintained at 300 ° C. It is clear that it can be obtained.
【００４９】尚、前記各実施例では、電気抵抗体９を白
金（白金黒）で被覆しているが、パラジウムで被覆する
ようにしてもよい。Although the electric resistor 9 is coated with platinum (platinum black) in each of the above embodiments, it may be coated with palladium.
【図１】図１（ａ）は本発明の接触燃焼式ガスセンサの
回路構成を示す回路図、図１（ｂ）は図１（ａ）示のガ
ス検知素子の一部断面を示す斜視図。FIG. 1 (a) is a circuit diagram showing a circuit configuration of a catalytic combustion gas sensor of the present invention, and FIG. 1 (b) is a perspective view showing a partial cross section of the gas detection element shown in FIG. 1 (a).
【図２】電気抵抗体となる金属の電気抵抗率と温度との
関係を示すグラフ。FIG. 2 is a graph showing the relationship between the electric resistivity of a metal serving as an electric resistor and temperature.
【図３】ガス検知素子のガス検知性能を測定する装置の
構成を示す説明的断面図。FIG. 3 is an explanatory sectional view showing a configuration of an apparatus for measuring gas detection performance of a gas detection element.
【図４】本発明の実施例１のガス検知素子における一酸
化炭素濃度と電気抵抗値の変化量との関係を示すグラ
フ。FIG. 4 is a graph showing the relationship between the carbon monoxide concentration and the amount of change in electric resistance value in the gas detection element according to the first embodiment of the present invention.
【図５】本発明の実施例２のガス検知素子における一酸
化炭素濃度と電気抵抗値の変化量との関係を示すグラ
フ。FIG. 5 is a graph showing the relationship between the carbon monoxide concentration and the amount of change in electric resistance value in the gas detection element of Example 2 of the present invention.
【図６】従来のガス検知素子２における一酸化炭素濃度
と電気抵抗値の変化量との関係を示すグラフ。FIG. 6 is a graph showing the relationship between the carbon monoxide concentration and the amount of change in electric resistance value in the conventional gas detection element 2.
【図７】ガス検知素子を２３０℃に維持したときの一酸
化炭素濃度と電気抵抗値の変化量との関係を示すグラ
フ。FIG. 7 is a graph showing the relationship between the carbon monoxide concentration and the amount of change in electric resistance when the gas detection element is maintained at 230 ° C.
【図８】ガス検知素子を３００℃に維持したときの一酸
化炭素濃度と電気抵抗値の変化量との関係を示すグラ
フ。FIG. 8 is a graph showing the relationship between the carbon monoxide concentration and the amount of change in electric resistance value when the gas detection element is maintained at 300 ° C.
【図９】ガス検知素子を３５０℃に維持したときの一酸
化炭素濃度と電気抵抗値の変化量との関係を示すグラ
フ。FIG. 9 is a graph showing the relationship between the carbon monoxide concentration and the amount of change in electric resistance when the gas detection element is maintained at 350 ° C.
【図１０】ガス検知素子を４００℃に維持したときの一
酸化炭素濃度と電気抵抗値の変化量との関係を示すグラ
フ。FIG. 10 is a graph showing the relationship between the carbon monoxide concentration and the amount of change in electric resistance value when the gas detection element is maintained at 400 ° C.
１…接触燃焼式ガスセンサ、 ２…ガス検知素子、 ９
…電気抵抗体、 １０…白金またはパラジウム。1 ... Contact combustion type gas sensor, 2 ... Gas detection element, 9
… Electric resistors, 10… Platinum or palladium.
Claims (3)
属からなる電気抵抗体をガス検知素子とし、所定温度に
保持された該ガス検知素子に接触した可燃性気体を該白
金またはパラジウムを触媒として燃焼せしめ、該可燃性
気体の燃焼熱による該電気抵抗体の電気抵抗の変化を検
出することにより可燃性気体の濃度を検知する接触燃焼
式ガスセンサにおいて、 該電気抵抗体は、鉄またはニッケルであることを特徴と
する接触燃焼式ガスセンサ。1. An electric resistor made of a metal whose surface is coated with platinum or palladium is used as a gas detection element, and a combustible gas contacted with the gas detection element maintained at a predetermined temperature is burned with the platinum or palladium as a catalyst. In the contact combustion gas sensor for detecting the concentration of the combustible gas by detecting the change in the electric resistance of the electric resistor due to the combustion heat of the combustible gas, the electric resistor is iron or nickel. A catalytic combustion type gas sensor characterized by:
れている鉄であって、該ニッケルの被覆上に白金または
パラジウムが被覆されていることを特徴とする請求項１
記載の接触燃焼式ガスセンサ。2. The electric resistor is iron whose surface is coated with nickel, and platinum or palladium is coated on the nickel coating.
The catalytic combustion type gas sensor described.
または不点火を検知することを特徴とする請求項１また
は請求項２記載の接触燃焼式ガスセンサ。3. The catalytic combustion gas sensor according to claim 1, wherein the gas sensor detects incomplete combustion or misfire of a gas appliance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07264560A JP3078485B2 (en) | 1995-10-12 | 1995-10-12 | Contact combustion type gas sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07264560A JP3078485B2 (en) | 1995-10-12 | 1995-10-12 | Contact combustion type gas sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09105732A true JPH09105732A (en) | 1997-04-22 |
| JP3078485B2 JP3078485B2 (en) | 2000-08-21 |
Family
ID=17404983
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP07264560A Expired - Fee Related JP3078485B2 (en) | 1995-10-12 | 1995-10-12 | Contact combustion type gas sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3078485B2 (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001021437A (en) * | 1999-07-12 | 2001-01-26 | Sanyo Electric Co Ltd | Gas leak sensor and absorption refrigerator mounted it |
| JP2007057267A (en) * | 2005-08-22 | 2007-03-08 | Fis Inc | Gas detector |
| JP2007519905A (en) * | 2004-01-16 | 2007-07-19 | アドバンスド テクノロジー マテリアルズ，インコーポレイテッド | Apparatus and method for detecting a target gas species in a semiconductor processing system |
| WO2007097025A1 (en) * | 2006-02-27 | 2007-08-30 | Fis Inc. | Hydrogen gas sensor |
| JP2009042097A (en) * | 2007-08-09 | 2009-02-26 | Seiko Npc Corp | Hydrogen gas sensor |
| JP2012037413A (en) * | 2010-08-09 | 2012-02-23 | Fis Inc | Sensing element and contact combustion type gas sensor |
| JP5044540B2 (en) * | 2006-02-27 | 2012-10-10 | エフアイエス株式会社 | Hydrogen gas sensor |
| JP2016114435A (en) * | 2014-12-12 | 2016-06-23 | 日本写真印刷株式会社 | Contact combustion type hydrogen gas sensor element and contact combustion type hydrogen gas sensor |
-
1995
- 1995-10-12 JP JP07264560A patent/JP3078485B2/en not_active Expired - Fee Related
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001021437A (en) * | 1999-07-12 | 2001-01-26 | Sanyo Electric Co Ltd | Gas leak sensor and absorption refrigerator mounted it |
| JP2007519905A (en) * | 2004-01-16 | 2007-07-19 | アドバンスド テクノロジー マテリアルズ，インコーポレイテッド | Apparatus and method for detecting a target gas species in a semiconductor processing system |
| JP2007057267A (en) * | 2005-08-22 | 2007-03-08 | Fis Inc | Gas detector |
| JP4575862B2 (en) * | 2005-08-22 | 2010-11-04 | エフアイエス株式会社 | Gas detector |
| WO2007097025A1 (en) * | 2006-02-27 | 2007-08-30 | Fis Inc. | Hydrogen gas sensor |
| WO2007099933A1 (en) * | 2006-02-27 | 2007-09-07 | Fis Inc. | Hydrogen gas sensor |
| JP5044540B2 (en) * | 2006-02-27 | 2012-10-10 | エフアイエス株式会社 | Hydrogen gas sensor |
| JP2009042097A (en) * | 2007-08-09 | 2009-02-26 | Seiko Npc Corp | Hydrogen gas sensor |
| JP2012037413A (en) * | 2010-08-09 | 2012-02-23 | Fis Inc | Sensing element and contact combustion type gas sensor |
| JP2016114435A (en) * | 2014-12-12 | 2016-06-23 | 日本写真印刷株式会社 | Contact combustion type hydrogen gas sensor element and contact combustion type hydrogen gas sensor |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3078485B2 (en) | 2000-08-21 |
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