JPH0792444B2 - Gas sensitivity detector for gas sensor - Google Patents
Gas sensitivity detector for gas sensorInfo
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- JPH0792444B2 JPH0792444B2 JP5075287A JP5075287A JPH0792444B2 JP H0792444 B2 JPH0792444 B2 JP H0792444B2 JP 5075287 A JP5075287 A JP 5075287A JP 5075287 A JP5075287 A JP 5075287A JP H0792444 B2 JPH0792444 B2 JP H0792444B2
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- gas sensor
- gas
- sensor element
- state
- output voltage
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 この発明は、例えば還元性ガスに反応するSnO2,ZnO,NiO
等の半導体ガスセンサのように，周囲雰囲気のガス濃度
に応じて抵抗が変化するガスセンサの感ガス性検知装置
に関するものである。[Detailed Description of the Invention] [Industrial field of application] The present invention relates to, for example, SnO 2 , ZnO, and NiO that react with reducing gas.
The present invention relates to a gas-sensitive detector for a gas sensor whose resistance changes in accordance with the gas concentration of the surrounding atmosphere, such as the semiconductor gas sensors described above.
第５図は，例えば昭和55年に発行された刊行物「月刊
「計装」昭和55年７月号・８月号・９月号・10月号通巻
第268〜271号別刷」に示されている従来の半導体式のガ
ス濃度センサの回路図であり，第６図は第５図の回路に
使用されるガスセンサ素子を示す図で，例えばトランジ
スタ技術1981年４月号掲載の「半導体ガスセンサ」に示
されているものである。Figure 5 is shown, for example, in the publication "Monthly" Instrumentation "July / August / September / October Volume 268-271 Reprint" published in 1980. FIG. 6 is a circuit diagram of a conventional semiconductor type gas concentration sensor, and FIG. 6 is a diagram showing a gas sensor element used in the circuit of FIG. 5, for example, “Semiconductor gas sensor” published in the April 1981 issue of Transistor Technology. Are shown in.
第５図において，（１）は半導体ガスセンサ素子，
（２）は交流電源，（３）は変圧器,Rは出力素子（抵
抗）,Eはこの出力素子Ｒの出力電圧（両端電圧）であ
る。第６図において，（ａ）（ｂ）はそれぞれSnO2を主
成分とする異なる構造のｎ型半導体ガスセンサ素子を一
部断面で示す斜視図である。第６図（ａ）において，
（101）はSnO2焼結体，（102）（103）はIr−Pd合金線
からなるヒータ兼電極である。第６図（ｂ）において，
（104）（105）は電極，（106）（107）はリード線，
（108）はヒータ，（109）は磁製絶縁チューブである。
第７図は第５図に示す回路構成のガス濃度検知装置に使
用される半導体式ガスセンサ素子の各種ガスに対する感
ガス特性図であり，（ａ）はAir Level（ガスを含まな
い空気中の特性），（ｂ）は一酸化炭素，（ｃ）は水
素，（ｄ）はエタノール，（ｅ）はメタン，（ｆ）はイ
ソブタンの場合を示す。第７図の感ガス特性から明らか
なように，半導体式ガスセンサ素子（１）に吸着した還
元性ガス量に応じて該ガスセンサ素子（１）の電気抵抗
は減少するため，第５図の回路における出力素子Ｒの出
力電圧Ｅは，ガスセンサ（１）の周囲の雰囲気における
ガス濃度に応じた値となる。In FIG. 5, (1) is a semiconductor gas sensor element,
(2) is an AC power supply, (3) is a transformer, R is an output element (resistance), and E is an output voltage (voltage across both ends) of the output element R. 6 (a) and 6 (b) are perspective views each partially showing in cross section an n-type semiconductor gas sensor element having a different structure containing SnO 2 as a main component. In FIG. 6 (a),
(101) is a SnO 2 sintered body, and (102) and (103) are heater-electrodes made of Ir-Pd alloy wire. In FIG. 6 (b),
(104) (105) are electrodes, (106) (107) are lead wires,
(108) is a heater, and (109) is a porcelain insulating tube.
FIG. 7 is a gas-sensing characteristic diagram for various gases of the semiconductor gas sensor element used in the gas concentration detecting device having the circuit configuration shown in FIG. ) And (b) are carbon monoxide, (c) is hydrogen, (d) is ethanol, (e) is methane, and (f) is isobutane. As is apparent from the gas-sensing characteristics of FIG. 7, the electric resistance of the gas sensor element (1) decreases according to the amount of reducing gas adsorbed on the semiconductor gas sensor element (1), so that the circuit of FIG. The output voltage E of the output element R has a value corresponding to the gas concentration in the atmosphere around the gas sensor (1).
ガス濃度検知に使用される半導体ガスセンサ素子（１）
は，一般的には,250℃以上に加熱して用いるため，有機
物による汚染は少ないが，長期間の使用によつてガスセ
ンサ素子温度における蒸発残分や塵埃の堆積が起り，徐
々に感度が低下する。また，半導体ガスセンサには，ガ
ス選択性や感ガス性を向上させるために各種の触媒が用
いられているが，この触媒も経年変化によつて触媒能が
落ち，十分な性能が得られなくなる。更に，強い衝撃が
加わつたり，腐食性ガスに触れてリード線（106）（10
7）や電極部（102）（103），（104）（105）で断線し
た場合や、単に電気的接続が十分でなかつた場合も，ガ
スセンサは正常な動作をしない。前述のようなガスセン
サを用いているガス濃度検知装置，例えばガス漏れ警報
器は、周囲雰囲気中にガス漏れが発生して危険な状態と
なつてこの危険状態を報告しなければならないにも拘ら
ず応答せず，報知動作しないという問題点がある。Semiconductor gas sensor element used for gas concentration detection (1)
In general, since it is heated to 250 ° C or higher, it is less contaminated by organic substances, but due to long-term use, evaporation residue and dust accumulation at the gas sensor element temperature occur, and the sensitivity gradually decreases. To do. Further, various catalysts are used in the semiconductor gas sensor in order to improve gas selectivity and gas sensitivity, but this catalyst also loses its catalytic ability due to aging, and sufficient performance cannot be obtained. In addition, the leads (106) (10
The gas sensor does not operate normally even if the wire is disconnected at 7) or the electrode parts (102) (103), (104) (105), or if the electrical connection is simply insufficient. A gas concentration detecting device using a gas sensor as described above, for example, a gas leak alarm, must report this dangerous state even though it has become a dangerous state due to gas leakage in the surrounding atmosphere. There is a problem that it does not respond and does not notify.
この発明はこのような従来の問題点を解決するためにな
されたもので，ガスセンサの性能低下や，リード線等の
断線，接触不良等によるガスーセンサの動作不能状態を
検知できるガスセンサの感ガス性検知装置を得ることを
目的とする。The present invention has been made to solve such a conventional problem, and is capable of detecting a gas sensor's gas-sensitive detection capable of detecting an inoperable state of the gas sensor due to performance deterioration of the gas sensor, disconnection of lead wires, poor contact, etc. The purpose is to obtain the device.
この発明に係るガスセンサの感ガス性検知装置は，周囲
雰囲気中のガス濃度に応じて抵抗が変化するガスセンサ
素子加熱用ヒータへの通電状態を，通常通電状態及び無
通電或いは通電量減少の非通常通電状態に繰り返し制御
する通電制御手段，前記ガスセンサ素子に接続されこの
ガスセンサ素子の抵抗変化によってその出力電圧が変化
する出力手段，及び，前記通常通電状態時の前記出力手
段の出力電圧Eoと，前記非通常通電状態から前記通常電
通状態に切換った後に過渡的に発生する前記ガスセンサ
素子の抵抗変化による前記出力手段の出力電圧Emとを比
較し,Em/Eoが所定値外となった場合に出力する比較手段
を備えたものである。A gas-sensitive detector for a gas sensor according to the present invention is configured such that a heater for heating a gas sensor element whose resistance changes according to a gas concentration in an ambient atmosphere is normally energized or non-energized or non-normally energized. An energization control means for repeatedly controlling the energized state, an output means connected to the gas sensor element, the output voltage of which changes according to a resistance change of the gas sensor element, and an output voltage Eo of the output means in the normal energized state, When the output voltage Em of the output means due to the resistance change of the gas sensor element that occurs transiently after switching from the non-normal energization state to the normal energization state is compared and Em / Eo is out of a predetermined value, A comparison means for outputting is provided.
この発明のガスセンサの感ガス性検知装置は，ガスセン
サ素子の温度が通常加熱温度より低い場合はガスセンサ
素子によるガス吸着量が多いが応答性は鈍く，通常加熱
温度より高い場合は逆にガス吸着量は少ないが応答性が
良い性質を持つていることを利用したもので，センサ素
子加熱用ヒータの電源を一旦切つて無通電状態として，
或いは通電量を減少してセンサ素子の温度を下げた後に
再通電した場合，低温時に吸着した多くのガス量に対応
して，つまり，清浄雰囲気中においてもセンサ素子の無
通電時間が，長いとそれに応じて，再通電直後に過渡的
な出力電圧の上昇（センサ素子の電気抵抗の減少）が生
じるが，劣化したガスセンサ素子ではこのような過渡的
な出力電圧の上昇（センサ素子の電気抵抗の減少）の現
象が現れないか，または鈍いため，この違いをとらえて
正常な感度を持つたガスセンサか否かを検知できる。The gas-sensitive detector of the gas sensor according to the present invention has a large gas adsorption amount by the gas sensor element when the temperature of the gas sensor element is lower than the normal heating temperature, but the response is slow, and conversely when the temperature of the gas sensor element is higher than the normal heating temperature. This is because the sensor element heating heater is turned off once to turn it off.
Alternatively, when the energization amount is decreased to lower the temperature of the sensor element and then re-energized, it corresponds to a large amount of gas adsorbed at a low temperature, that is, the non-energization time of the sensor element is long even in a clean atmosphere. Correspondingly, a transient increase in output voltage (reduction in electrical resistance of the sensor element) occurs immediately after re-energization, but in a deteriorated gas sensor element, such transient increase in output voltage (increase in electrical resistance of the sensor element). Since the phenomenon of “decrease” does not appear or is dull, it is possible to detect this difference and detect whether or not the gas sensor has normal sensitivity.
第１図はこの発明の一実施例によるガスセンサの感ガス
性検知装置の動作フロー兼ブロツク図，第２図はガスセ
ンサ素子加熱用ヒータへの通電とガスセンサ出力電圧の
測定タイミングを示す説明図，第３図は第１図の機能を
実行するための全体回路構成を示すブロツク図，第４図
はガスセンサ素子への通電を停止した後再通電した場合
の出力電圧と経過時間との関係を示す図である。FIG. 1 is an operation flow / block diagram of a gas-sensing detector for a gas sensor according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing energization of a heater for heating a gas sensor element and measurement timing of a gas sensor output voltage. FIG. 3 is a block diagram showing the overall circuit configuration for executing the function of FIG. 1, and FIG. 4 is a diagram showing the relationship between the output voltage and the elapsed time when the gas sensor element is de-energized and then re-energized. Is.
先ず，これら第１図〜第３図による詳細な説明の前に，
この発明の原理を具体的に説明する。この発明及びこの
発明の実施例では、ガスセンサ素子を加熱するヒータへ
の通電を停止したり，通電量を減らして非通常通電状態
とし，ガズセンサ素子の温度を下げ，再度正常通電（通
常通電状態）する動作を繰り返し行なう機能を持つてい
る。この正常通電開始直後は，ガスセンサ素子の温度が
一度低下したことにより，ガスセンサ素子表面への吸着
分子量が増加しているため，過渡的にガスセンサ素子の
電気抵抗が減少する。このガスセンサ素子の電気抵抗の
減少量は，ガスセンサ素子の温度を低下させたときの温
度と時間，ガスセンサ素子の感度に大きく影響されるの
で，ガスセンサ素子の温度低下時の温度と時間とを固定
条件とすれば，ガスセンサ素子の電気抵抗の減少量から
ガスセンサ素子の感度を自動的に知ることができる。ま
た，この発明及びこの発明の実施例は，半導体ガスセン
サ素子の温度が，通常通電状態での通常加熱温度より低
い場合はガスセンサ素子のガス吸着量は多いが，対ガス
応答性は鈍く，前記通常加熱温度より高い場合は逆にガ
ス吸着量は少ないが対ガス応答性が良い性質を利用した
もので，ガスセンサ素子加熱用のヒータ電源を一旦切つ
て無通電状態とし或いは通電量を減少してガスセンサ素
子の温度を下げた後に再通電した場合，再通電直後に，
低温時に吸着した多くのガス量に対応して過渡的に高い
出力電圧を発生することを応用したものである。第４図
はSnO2系の半導体ガスセンサ素子を使用して,A無通電状
態120分,B同30分,C同５分,D同１分，それぞれAIRレベル
（ガスの存在しない正常空気の状態）で室温で放置した
後に再度通電した場合の第３図，第５図の回路における
アナログ出力電圧を測定したもので，清浄雰囲気におい
ても無通電時間が長ければそれに応じて，再通電後の過
渡的な出力電圧の上昇（ガスセンサ素子の電気抵抗値の
減少）が見られる。これが、劣化したガスセンサ素子で
は前述のような過渡的な現象が現れないか，または鈍い
ため，この違いをとらえて正常な感度を持つたガスセン
サ素子か否かを区別し，不良品の場合には不良であるこ
とを表示または警報を発することにより，ガスセンサの
良否を検知できるのである。First, before the detailed description with reference to FIGS. 1 to 3,
The principle of the present invention will be specifically described. In the present invention and the embodiment of the present invention, the energization of the heater for heating the gas sensor element is stopped, or the energization amount is reduced to bring the gas sensor element into the non-normal energization state, the temperature of the gas sensor element is lowered, and the normal energization is resumed (normal energization state) It has a function to repeat the operation to do. Immediately after the start of normal energization, the temperature of the gas sensor element once drops, and the amount of adsorbed molecules on the surface of the gas sensor element increases, so that the electrical resistance of the gas sensor element transiently decreases. Since the amount of decrease in the electric resistance of the gas sensor element is greatly affected by the temperature and time when the temperature of the gas sensor element is lowered and the sensitivity of the gas sensor element, the temperature and time when the temperature of the gas sensor element is lowered are fixed conditions. Then, the sensitivity of the gas sensor element can be automatically known from the amount of decrease in the electrical resistance of the gas sensor element. Further, in the present invention and the embodiment of the present invention, when the temperature of the semiconductor gas sensor element is lower than the normal heating temperature in the normal energized state, the gas adsorption amount of the gas sensor element is large, but the gas responsiveness is low, On the contrary, when the temperature is higher than the heating temperature, the gas adsorption amount is small but the gas response is good. When re-energizing after lowering the element temperature, immediately after re-energizing,
This is an application of generating a transiently high output voltage corresponding to a large amount of gas adsorbed at a low temperature. Fig. 4 shows that using a SnO 2 type semiconductor gas sensor element, A non-energized state for 120 minutes, B for 30 minutes, C for 5 minutes, D for 1 minute, AIR level (normal air without gas) ) Was measured at the analog output voltage in the circuit of Fig. 3 and Fig. 5 when it was re-energized after it was left at room temperature. The increase in output voltage (decrease in electric resistance of the gas sensor element) is observed. This is because the deteriorated gas sensor element does not show the above transient phenomenon or is blunt. Therefore, by grasping this difference, it is distinguished whether or not the gas sensor element has a normal sensitivity. It is possible to detect whether the gas sensor is good or bad by displaying a defect or issuing an alarm.
以下，第１図〜第３図によつてこの発明の一実施例を詳
しく説明する。An embodiment of the present invention will be described in detail below with reference to FIGS.
第３図において，（１）はガスセンサで，例えばSnO2系
の半導体ガスセンサ素子等が使用される。（２）は交流
電源，（３）は変圧器，（４）はガスセンサ素子（１）
の出力電圧をアナログからデジタル信号に変換するA/D
変換器，（５）はA/D変換器（４）の出力信号を処理す
る入力回路，（６）は内部に時計機能を持ち前記入出力
回路（５）からの信号を演算処理する中央処理装置（CP
U），（７）はこの中央処理装置（６）の直流電源，
（８）は中央処理装置（６）からの出力信号を他の部分
へ送る信号に変換する出力回路，（９）は前記出力回路
（８）からの信号によりガスセンサ素子（１）のヒータ
電源を開閉するスイツチ，（10）は中央処理装置（６）
で得た出力電圧信号を記憶するメモリ（記憶装置），
（11）はガスセンサ素子（１）に異常があつた場合に出
力回路（８）から信号で動作する報知器で，例えば警報
ブサー，表示ランプ等である。In FIG. 3, (1) is a gas sensor, for example, a SnO 2 based semiconductor gas sensor element or the like is used. (2) is an AC power supply, (3) is a transformer, (4) is a gas sensor element (1)
A / D that converts analog output voltage from analog to digital signal
Converter, (5) is an input circuit that processes the output signal of the A / D converter (4), (6) is a central processing unit that has a clock function inside and that processes the signal from the input / output circuit (5) (CP
U) and (7) are DC power supplies of this central processing unit (6),
(8) is an output circuit for converting the output signal from the central processing unit (6) into a signal to be sent to another part, and (9) is a heater power supply for the gas sensor element (1) according to the signal from the output circuit (8). Switch to open and close, (10) central processing unit (6)
A memory (memory device) for storing the output voltage signal obtained in
Reference numeral (11) is an alarm that operates by a signal from the output circuit (8) when the gas sensor element (1) is abnormal, and is, for example, an alarm buzzer or a display lamp.
次に，第１図〜第３図によつて動作を説明する。通常の
ガス検知状態（通常通電状態）を１ヶ月断続する（通常
運転ステツプ（12））と，中央処理装置（６）からの命
令があり,A/D変換器（４），入力回路（５）を介して出
力素子Ｒの出力電圧Ｅを測定（出力電圧測定ステツプ
（13））し，この値をEoとしてメモリ（10）に記憶させ
る（記憶ステツプ（14））。次に出力回路（８）を介し
てスイツチ（９）を開としてガスセンサ素子（１）のヒ
ータの発熱を停止（ヒータOFFステツプ（15）させ，非
通常通電状態として該ヒータの温度を下げ,1分後，再び
出力回路（８）を介してスイツチ（９）を閉（ヒータON
ステツプ（16））とし，ガスセンサ素子（１）のヒータ
に再通電して通常通電状態とし該ヒータを再加熱する。
前記非通常通電状態による前記ガスーセンサ素子（１）
の低温時に空気等の周囲雰囲気中の水分など有感ガスが
ガスセンサ素子（１）の表面に多量に吸着する。前記再
通電開始から25秒後，中央処理装置（６）よりA/D変換
器（４），入力回路（５）を介して出力素子Ｒの出力電
圧Ｅを再度測定（出力電圧測定ステツプ（17））し，こ
の値をEmとしメモリ（10）に記憶する（記憶ステツプ
（18））。そしてメモリ（10）より前記非通常通電状態
に入る前の出力電圧Eoを読み,Em/Eoを求め，この値が1.
3より小さいかどうか判定（判定ステツプ（19）する。
小さければ，ガスセンサ素子（１）の感度が鈍つていた
り，ガスセンサ素子（１）への通電用ヒータの断線等の
異常を示すものであるため，出力回路（８）を介して報
知器（11）を動作させて異常表示あるいは異常警報（ス
テツプ（20））し，点検や，ガスセンサ素子（１）の交
換を促す。Em/Eo≧1.3ならば。ガスセンサ素子（１）は
正常に動作しているものと判断し,1ヶ月間は正常運転
（通常通電状態）を行わせ,1ヶ月後は，前述の不良検出
プログラム通り、正常か否かの判定を行うというサイク
ルを繰り返し行う。これによつてガスセンサの自動的な
定期点検が行え，本来検出すべきガス漏れ状態等におい
て，ガスセンサの不良によつて警報を発しないような危
険な事態を回避することができる。Next, the operation will be described with reference to FIGS. There is an instruction from the central processing unit (6) when the normal gas detection state (normal energization state) is interrupted for one month (normal operation step (12)), A / D converter (4), input circuit (5) The output voltage E of the output element R is measured (output voltage measurement step (13)) via the above) and this value is stored in the memory (10) as Eo (storage step (14)). Next, the switch (9) is opened via the output circuit (8) to stop the heat generation of the heater of the gas sensor element (1) (heater OFF step (15), and the heater is lowered to the non-normal energization state to After a minute, the switch (9) is closed again via the output circuit (8) (heater ON
In step (16), the heater of the gas sensor element (1) is re-energized to bring it into a normal energized state and the heater is reheated.
The gas sensor element (1) according to the non-normally energized state
When the temperature is low, a large amount of sensitive gas such as water in the ambient atmosphere is adsorbed on the surface of the gas sensor element (1). Twenty-five seconds after the start of reenergization, the central processing unit (6) again measures the output voltage E of the output element R via the A / D converter (4) and the input circuit (5) (output voltage measurement step (17 )) And store this value in the memory (10) as Em (memory step (18)). Then, read the output voltage Eo before entering the non-normal energization state from the memory (10) and obtain Em / Eo. This value is 1.
It is determined whether it is less than 3 (determination step (19).
If it is small, it means that the sensitivity of the gas sensor element (1) is low, or an abnormality such as a disconnection of a heater for energizing the gas sensor element (1) is indicated. Therefore, the alarm (11) is output via the output circuit (8). ) Is operated to display an abnormality or give an alarm (step (20)) to prompt inspection and replacement of the gas sensor element (1). If Em / Eo ≧ 1.3. It is judged that the gas sensor element (1) is operating normally, the normal operation (normal energization state) is performed for 1 month, and after 1 month, it is judged whether it is normal according to the above defect detection program. Repeat the cycle of performing. As a result, it is possible to perform an automatic periodic inspection of the gas sensor, and avoid a dangerous situation where an alarm is not issued due to a defect in the gas sensor in a gas leak state or the like that should be detected.
なお，前述の実施例では，通常通電状態の運転期間（点
検間隔）を１ヶ月，ヒータOFF（非通常通電状態）時間
を１分，再通電後出力電圧（Em）測定時間を30秒とし,E
m/Eoの判定基準を1.3としたが，使用雰囲気やガス検知
の重要性に応じて変更設定することが必要である。ま
た，ガスセンサ素子の不良を知らせる報知は，ガス漏れ
を知らせる本来の警報とは音色，音量，報知形態の相違
等で区別できるようにするのがよい。更に，ガスセンサ
素子（１）のヒータへの通電は，非通常通電状態時には
必ずしも停止しなくても，通電量を減少するようにして
もよい。In the above-described embodiment, the operation period (check interval) in the normal energization state is 1 month, the heater OFF (non-normal energization state) time is 1 minute, and the output voltage (Em) measurement time after reenergization is 30 seconds. E
The m / Eo criterion was set to 1.3, but it needs to be changed and set according to the usage atmosphere and the importance of gas detection. Further, it is preferable that the notification notifying that the gas sensor element is defective can be distinguished from the original warning notifying the gas leakage by the timbre, the volume, the difference in the notification form, and the like. Further, the energization of the heater of the gas sensor element (1) does not necessarily have to be stopped in the non-normal energization state, but the energization amount may be reduced.
この発明は前述のように，周囲雰囲気中のガス濃度に応
じて抵抗が変化するガスセンサ素子加熱用ヒータへの通
電状態を，通常通電状態及び無通電或いは通電量減少の
非通常通電状態に繰り返し制御する通電制御手段，前記
ガスセンサ素子に接続されこのガスセンサ素子の抵抗変
化によってその出力電圧が変化する出力手段，及び，前
記通常通電状態時の前記出力手段の出力電圧Eoと，前記
非通常通電状態から前記通常通電状態に切換った後に過
渡的に発生する前記ガスセンサ素子の抵抗変化による前
記出力手段の出力電圧Emとを比較し,Em/Eoが所定値外と
なった場合に出力する比較手段を備えたものであるの
で，例えばガス漏れ警報器等に使用されているガスセン
サ素子の感度低下やリード線の断線等の不良状態を自動
検知でき，例えば不良であればこれを報じ，人為的な点
検や交換を促す等ができる効果がある。As described above, the present invention repeatedly controls the energized state of the heater for heating the gas sensor element, the resistance of which changes according to the gas concentration in the ambient atmosphere, to the normal energized state and the non-normally energized state in which the energization amount is decreased or the energization amount is decreased. Energization control means, output means connected to the gas sensor element, the output voltage of which changes according to the resistance change of the gas sensor element, and output voltage Eo of the output means during the normal energization state, and from the non-normal energization state A comparison means for comparing the output voltage Em of the output means due to the resistance change of the gas sensor element that occurs transiently after switching to the normal energization state and outputting when Em / Eo is out of a predetermined value Since it is equipped with such a device, it is possible to automatically detect a defective state such as a decrease in sensitivity of a gas sensor element used in a gas leak alarm device or disconnection of a lead wire. If there is any, it has the effect of reporting this and urging artificial inspection and replacement.
第１図〜第３図はこの発明の一実施例を示す図で，第１
図はガスセンサの感ガス性検知装置の動作フロー兼ブロ
ツク図，第２図はガスセンサ素子加熱用ヒータへの通電
とガスセンサ出力電圧の側定タイミングを示す説明図，
第３図は第１図の機能を実行するための全体回路構成を
示すブロツク図，第４図はガスセンサ素子への通電を停
止した後再通電した場合の出力電圧と経過時間との関係
を示す図，第５図は従来のガス検知回路を示す図であ
り，この発明を適用できるガス検知回路の一例でもあ
る。第６図は第５図の回路に使用されるガスセンサ素子
を一部断面で示す斜視図で，（ａ）はヒータ兼電極をSn
O2で一体に焼結したもの，（ｂ）は外側にSnO2焼結対が
施された絶縁チューブ内にヒータを挿入したものを示
す。第７図は各種ガス雰囲気中でのガス濃度とガスセン
サ素子の抵抗値との関係を示す図である。 図において，（１）はガスセンサ，（６）（８）（９）
（10）はガスセンサ素子への通電状態を制御する通電制
御手段を構成する中央演算処置装置，出力回路，スチツ
チ，メモリである。（５）（６）（10）がガスセンサ素
子の抵抗変化度合を判定する判定手段を構成する入力回
路，中央演算処理装置，メモリである。（12）は通常運
転ステツプ，（13）は出力電圧測定ステツプ，（14）は
記憶ステツプ，（15）はヒータOFFステツプ，（16）は
ヒータONステツプ，（17）が出力電圧測定ステツプ，
（18）は記憶ステツプ，（19）はEm/Eo＜1.3の判定ステ
ツプである。 なお，各図中同一符号は同一又は相当部分を示す。1 to 3 are views showing an embodiment of the present invention.
Fig. 2 is an operation flow and block diagram of the gas-sensitive detector of the gas sensor. Fig. 2 is an explanatory diagram showing the energization of the heater for heating the gas sensor element and the side timing of the gas sensor output voltage.
FIG. 3 is a block diagram showing the overall circuit configuration for executing the function of FIG. 1, and FIG. 4 shows the relationship between the output voltage and the elapsed time when the gas sensor element is de-energized and then re-energized. 5 and 5 are views showing a conventional gas detection circuit, which is also an example of a gas detection circuit to which the present invention can be applied. FIG. 6 is a perspective view showing a partial cross section of the gas sensor element used in the circuit of FIG. 5, and FIG. 6 (a) shows a heater / electrode as Sn.
O 2 in those sintered together, (b) shows a material obtained by inserting a heater into the insulating tube SnO 2 sintered pair is applied to the outside. FIG. 7 is a diagram showing the relationship between the gas concentration in various gas atmospheres and the resistance value of the gas sensor element. In the figure, (1) is a gas sensor, (6) (8) (9)
Reference numeral (10) is a central processing unit, an output circuit, a switch, and a memory which constitute an energization control means for controlling the energization state of the gas sensor element. (5), (6), and (10) are an input circuit, a central processing unit, and a memory that constitute a determination unit that determines the degree of resistance change of the gas sensor element. (12) is a normal operation step, (13) is an output voltage measurement step, (14) is a memory step, (15) is a heater OFF step, (16) is a heater ON step, (17) is an output voltage measurement step,
(18) is a memory step, and (19) is a judgment step of Em / Eo <1.3. In the drawings, the same reference numerals indicate the same or corresponding parts.
Claims (3)
化するガスセンサ素子加熱用ヒータへの通電状態を，通
常通電状態及び無通電或いは通電量減少の非通常通電状
態に繰り返し制御する通電制御手段，前記ガスセンサ素
子に接続されこのガスセンサ素子の抵抗変化によってそ
の出力電圧が変化する出力手段，及び，前記通常通電状
態時の前記出力手段の出力電圧Eoと，前記非通常通電状
態から前記通常通電状態に切換った後に過渡的に発生す
る前記ガスセンサ素子の抵抗変化による前記出力手段の
出力電圧Emとを比較し,Em/Eoが所定値外となった場合に
出力する比較手段を備えていることを特徴とする感ガス
性検知装置。1. An energization control for repeatedly controlling an energized state to a heater for heating a gas sensor element whose resistance changes according to a gas concentration in an ambient atmosphere, to a normal energized state and a non-energized state with no energized state or a reduced energized amount. Means, output means connected to the gas sensor element, the output voltage of which changes according to the resistance change of the gas sensor element; output voltage Eo of the output means during the normal energization state; and normal energization from the non-normal energization state It is provided with a comparison means for comparing with the output voltage Em of the output means due to the resistance change of the gas sensor element which occurs transiently after switching to the state and when Em / Eo is out of a predetermined value. A gas-sensitive detection device characterized in that
し制御が１年に１回以上自動的に行なわれることを特徴
とする特許請求の範囲第１項記載のガスセンサの感ガス
性検知装置。2. The gas-sensing detector for a gas sensor according to claim 1, wherein the repetitive control of the normally energized state and the non-normally energized state is automatically performed at least once a year.
いは表示することを特徴とする特許請求の範囲第１項又
は第２項に記載のガスセンサの感ガス性検知装置。3. A gas-sensing detector for a gas sensor according to claim 1 or 2, wherein an alarm or display is made when Em / Eo is out of a predetermined value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5075287A JPH0792444B2 (en) | 1987-03-05 | 1987-03-05 | Gas sensitivity detector for gas sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5075287A JPH0792444B2 (en) | 1987-03-05 | 1987-03-05 | Gas sensitivity detector for gas sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63215959A JPS63215959A (en) | 1988-09-08 |
| JPH0792444B2 true JPH0792444B2 (en) | 1995-10-09 |
Family
ID=12867570
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5075287A Expired - Lifetime JPH0792444B2 (en) | 1987-03-05 | 1987-03-05 | Gas sensitivity detector for gas sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0792444B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4830714B2 (en) * | 2006-08-17 | 2011-12-07 | 富士電機株式会社 | Anomaly detection method for thin film gas sensor |
| JP5065097B2 (en) * | 2008-03-03 | 2012-10-31 | 大阪瓦斯株式会社 | Gas detection device and gas detection method |
-
1987
- 1987-03-05 JP JP5075287A patent/JPH0792444B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63215959A (en) | 1988-09-08 |
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