JP2958094B2 - Gas sensor for external air introduction control of automobiles - Google Patents
Gas sensor for external air introduction control of automobilesInfo
- Publication number
- JP2958094B2 JP2958094B2 JP26976490A JP26976490A JP2958094B2 JP 2958094 B2 JP2958094 B2 JP 2958094B2 JP 26976490 A JP26976490 A JP 26976490A JP 26976490 A JP26976490 A JP 26976490A JP 2958094 B2 JP2958094 B2 JP 2958094B2
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- JP
- Japan
- Prior art keywords
- exhaust gas
- sensitivity
- gas sensor
- 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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Description
【発明の詳細な説明】 ［発明の利用分野］ この発明は自動車の外気導入制御用ガスセンサに関
し、特に経時劣化の防止と高速応答性の確保とに関す
る。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas sensor for controlling the introduction of outside air of an automobile, and more particularly to preventing deterioration with time and ensuring high-speed response.
［従来技術］ 発明者らは、WO3を用いた自動車の外気導入制御用ガ
スセンサを提案した（特願平２−177,982号，特開平４
−65662号公報）。検出目標はガソリン車の排ガスでは
なくディーゼル車の排ガスに置き、排ガスに対する人の
臭いの感覚に検出目標を一致させた。またガスセンサの
材料にはWO3を用い、厚膜と薄膜との双方を検討した
が、感度の初期値の高いWO3薄膜を主に検討した。しか
しWO3への添加物は検討せず、単味のWO3を用いた。[Prior Art] The present inventors have proposed a gas sensor for controlling the introduction of outside air into a vehicle using WO3 (Japanese Patent Application No. 2-177,982, Japanese Patent Application Laid-Open No. HEI 4-177,985).
-65662). The detection target was set to the exhaust gas of a diesel vehicle instead of the exhaust gas of a gasoline vehicle, and the detection target was matched to the sense of human odor to the exhaust gas. In addition, although WO3 was used as the material of the gas sensor, and both a thick film and a thin film were examined, mainly a WO3 thin film having a high initial value of sensitivity was examined. However, additives to WO3 were not examined, and plain WO3 was used.
自動車の外気導入制御用ガスセンサは、外気の汚染を
検出して、外気を車室内に取り入れるか車室内の空気を
循環させるかを決定するためのものである。検出目標と
なるのは主として前方を走行する車両からの排ガスであ
る。ガスセンサの信号処理では基準値を用い、基準値か
らのセンサ出力の変化で外気の汚染を検出する。基準値
の取り出し方には種々のものが提案されているが、主な
ものは、１分間隔でランダムにセンサ出力をサンプリン
グしこれを基準値とする、あるいはセンサ信号の包絡線
を取り出し包絡線上に基準値を求めるものである。いず
れの場合も、センサ信号の絶対値を用いず、基準値に対
する相対値を用いる点が特徴である。基準値を用いるこ
とにより、センサ出力の絶対値自体は重要ではなく、セ
ンサ出力の絶対値が変動しても問題はない。しかし排ガ
スへのセンサの感度（排ガスとの接触の前後での出力の
変化幅）や応答速度は低下してはならない。また自動車
の外気導入制御では外気の汚染を速やかに検出すること
が重要で、高速応答性能が要求される。A gas sensor for controlling the introduction of outside air of an automobile is for detecting contamination of the outside air and determining whether to take the outside air into the vehicle compartment or to circulate the air in the vehicle compartment. The detection target is mainly exhaust gas from a vehicle traveling ahead. In the signal processing of the gas sensor, a reference value is used, and contamination of the outside air is detected based on a change in the sensor output from the reference value. Various methods have been proposed for extracting the reference value. The main method is to randomly sample the sensor output at one-minute intervals and use it as a reference value, or to extract the envelope of the sensor signal and extract it from the envelope. To obtain a reference value. In any case, a feature is that an absolute value of a sensor signal is not used, but a relative value with respect to a reference value is used. By using the reference value, the absolute value of the sensor output itself is not important, and there is no problem even if the absolute value of the sensor output fluctuates. However, the sensitivity of the sensor to exhaust gas (change in output before and after contact with exhaust gas) and the response speed must not be reduced. In addition, in the outside air introduction control of an automobile, it is important to detect contamination of the outside air promptly, and high-speed response performance is required.
発明者は、WO3薄膜を用いたガスセンサの経時特性を
モニタした結果、WO3薄膜ではセンサの感度も応答性能
も経時的に劣化することを見出した。これに対してWO3
の厚膜では経時劣化は小さく、またWO3に特定の添加物
を加えることにより応答性能を改善し得ることが判明し
た。As a result of monitoring the time characteristics of a gas sensor using a WO3 thin film, the inventors have found that the sensitivity and response performance of the WO3 thin film deteriorate with time. WO3
It has been found that the time-dependent deterioration is small in the thick film and the response performance can be improved by adding a specific additive to WO3.
［発明の課題］ この発明の課題は、経時劣化が小さく、かつ高速応答
性を有する、自動車の外気導入制御用ガスセンサを提供
することにある。[Problem of the Invention] An object of the present invention is to provide a gas sensor for controlling the introduction of outside air of an automobile, which has a small deterioration with time and a high-speed response.
［発明の構成］ この発明の自動車の外気導入制御用ガスセンサは、WO
3厚膜にRe,S,Pbからなる群の少なくとも一員の元素を添
加したことを特徴とする。WO3厚膜は、厚さ例えば５〜5
0μｍ、より好ましくは10〜20μｍとし、加えるRe,S,Pb
は金属、酸化物、あるいは塩として存在させる。[Constitution of the Invention] A gas sensor for controlling outside air introduction of an automobile according to the present invention is described in WO
A feature is that at least one member of the group consisting of Re, S, and Pb is added to the three thick films. The WO3 thick film has a thickness of, for example, 5 to 5
0 μm, more preferably 10-20 μm, and added Re, S, Pb
Is present as a metal, oxide, or salt.
WO3の薄膜ではなく厚膜を用いることにより、感度や
応答性能の経時劣化を抑制できる。即ちWO3の薄膜と厚
膜とでは、感度や応答速度の耐久性に大差がある。Re,
S,Pbは、経時劣化を更に抑制しあるいは応答速度を高め
るための添加物である。例えばReやＳは応答速度の低下
の防止に有効で、Pbでは応答速度の初期値が速いととも
に応答性能の劣化も小さい。By using a thick film instead of a thin film of WO3, it is possible to suppress deterioration with time of sensitivity and response performance. That is, there is a great difference in durability between the thin film and the thick film of WO3 in terms of sensitivity and response speed. Re,
S and Pb are additives for further suppressing the deterioration over time or increasing the response speed. For example, Re and S are effective in preventing a decrease in response speed, and Pb has a high initial response speed and a small deterioration in response performance.
［実施例］ ガスセンサの構造 第20図，第21図に、ガスセンサの構造を示す。図にお
いて、２はアルミナ等の基板で、４はWO3厚膜にRe等を
添加したガス感応部、６は補償用のWO3厚膜で材質はガ
ス感応部４と同一あるいはWO3単味の厚膜とし、８は雰
囲気遮断用のガラスコート膜、10,12,14は電極、16はRu
O2等のヒータである。実験では特に示さない限り補償用
のWO3厚膜６を用いず、WO3厚膜のガス感応部４に負荷抵
抗と5Vの直流電源とを接続し、負荷抵抗への出力をセン
サ出力として用いた。[Example] Structure of Gas Sensor FIGS. 20 and 21 show the structure of a gas sensor. In the figure, reference numeral 2 denotes a substrate made of alumina or the like, 4 denotes a gas-sensitive portion obtained by adding Re or the like to a WO3 thick film, 6 denotes a compensation WO3 thick film, the material of which is the same as that of the gas-sensitive portion 4 or a single thick WO3 film. 8 is a glass coat film for shielding the atmosphere, 10, 12, and 14 are electrodes, and 16 is Ru.
It is a heater such as O2. In the experiment, the WO3 thick film 6 for compensation was not used unless otherwise indicated, and a load resistance and a DC power supply of 5 V were connected to the gas sensitive portion 4 of the WO3 thick film, and an output to the load resistance was used as a sensor output.
ガスセンサの調製 ガスセンサの製造方法を示す。市販のWO3粉体（試薬
特級）を用い、粉砕後に500℃で１時間空気中で焼成
し、WO3粉末とした。WO3粉末を厚さ10〜20μｍに印刷
し、シリカゾルバインダーを数wt％含浸させて700℃で
空気中で焼結した。焼結後のWO3厚膜に硝酸水溶液で添
加物を含浸させ、700℃で再度焼結してガス感応部４や
補償用のWO3厚膜６とした。Ｓの添加は希硫酸の含浸で
行い、Ptを添加する場合には塩化白金酸を用い、Pdに場
合にはPdの王水溶液を用いた。添加物の水溶液はいずれ
も0.03mol/L濃度を原則とし、0.01mol/L〜0.1mol/Lの範
囲で実験した。しかしいずれの添加物でも添加物濃度へ
の依存性は見られず、添加物濃度は重要ではないことが
判明した。実験で用いた含浸法では、0.03mol/Lの濃度
は添加物元素とＷとの原子比で約0.3atm％に相当し、添
加物濃度はＷとの原子比で0.1〜1atm％の範囲に相当す
る。Re等の添加物濃度はＷとの原子比で一般的には0.03
〜10atm％、より具体的には0.05〜5atm％、更に具体的
には0.05〜2atm％とする。Re等の添加物は主として酸化
物として存在すると考えられるが、一部が塩としてある
いは金属に還元されて存在することも考えられる。また
WO3厚膜は部分的に還元されてWO3-xとして存在すること
も考えられる。Preparation of gas sensor A method for manufacturing a gas sensor will be described. A commercially available WO3 powder (special reagent grade) was used, and after pulverization, calcined at 500 ° C. for 1 hour in air to obtain a WO3 powder. WO3 powder was printed to a thickness of 10 to 20 μm, impregnated with silica sol binder by several wt%, and sintered at 700 ° C. in air. The WO3 thick film after sintering was impregnated with an additive with a nitric acid aqueous solution, and was sintered again at 700 ° C. to form a gas sensitive portion 4 and a WO3 thick film 6 for compensation. S was added by impregnation with dilute sulfuric acid. When Pt was added, chloroplatinic acid was used, and when Pd was used, an aqueous solution of Pd was used. The aqueous solution of the additive was in principle used at a concentration of 0.03 mol / L, and the experiment was conducted in the range of 0.01 mol / L to 0.1 mol / L. However, no dependence on the additive concentration was observed for any of the additives, and it was found that the additive concentration was not important. In the impregnation method used in the experiment, the concentration of 0.03 mol / L is equivalent to about 0.3 atm% in atomic ratio between the additive element and W, and the additive concentration is in the range of 0.1 to 1 atm% in atomic ratio with W. Equivalent to. The concentration of additives such as Re is generally 0.03 in atomic ratio with W.
To 10 atm%, more specifically 0.05 to 5 atm%, and more specifically 0.05 to 2 atm%. Additives such as Re are considered to exist mainly as oxides, but may also be present partially as salts or reduced to metal. Also
It is also conceivable that the WO3 thick film is partially reduced and exists as WO3- x .
これとは別に比較例として、真空蒸着でWO3薄膜（膜
厚0.64μｍ）ガスセンサを調製した。Separately, as a comparative example, a WO3 thin film (0.64 μm thick) gas sensor was prepared by vacuum evaporation.
特性 第１図〜第19図に、ガスセンサの特性を示す。各図に
おいて、実線はセンサ特性の初期値を、破線は48日経過
後の特性を示す。図の上部に材料の種類を記入し、いず
れも0.03mol/Lの濃度の溶液で含浸させたものである。
ガスセンサの使用温度はいずれも300℃で、経時変化は
室内で48日間ガスセンサを300℃に加熱した後に測定し
た。図の縦軸はセンサ抵抗Rsを示す。用いたガスはH210
00ppm（可燃性ガス感度の評価用）、NO21ppm（ディーゼ
ル排ガス感度の参考）、ガソリン車からの排ガスをエア
バッグで捕集し5000ppmに希釈したもの（ガソリン排ガ
ス）、ディーゼル車からの排ガスをエアバッグで捕集後
5000ppmに希釈したもの（ディーゼル排ガス）の４種で
ある。ガソリン車の排ガスへの嗅覚は鈍く、ディーゼル
車の排ガスへの嗅覚は鋭いので、センサ感度はディーゼ
ル排ガスに高いことが望まれる。またガソリン排ガスへ
の感度とディーゼル排ガスへの感度との方向は逆で、ガ
ソリン排ガスへの感度はディーゼル排ガスへの感度を鈍
らせるので、ガソリン排ガスへの感度は低いことが望ま
しい。Characteristics FIGS. 1 to 19 show the characteristics of the gas sensor. In each figure, the solid line shows the initial value of the sensor characteristics, and the broken line shows the characteristics after 48 days. The type of material is entered at the top of the figure, and all are impregnated with a solution having a concentration of 0.03 mol / L.
The operating temperature of each gas sensor was 300 ° C., and the change with time was measured after heating the gas sensor to 300 ° C. for 48 days in a room. The vertical axis of the figure indicates the sensor resistance Rs. The gas used was H210
00ppm (for evaluation of flammable gas sensitivity), NO21ppm (reference for diesel exhaust gas sensitivity), exhaust gas from gasoline vehicles collected by airbag and diluted to 5000ppm (gasoline exhaust gas), exhaust gas from diesel vehicles in airbag After collecting
There are four types, which are diluted to 5000 ppm (diesel exhaust gas). Since the sense of smell of exhaust gas from gasoline vehicles is dull and the sense of smell to exhaust gas from diesel vehicles is sharp, it is desired that the sensor sensitivity be high for diesel exhaust gas. Further, the sensitivity to gasoline exhaust gas is opposite to the direction to diesel exhaust gas, and the sensitivity to gasoline exhaust gas degrades the sensitivity to diesel exhaust gas.
図に示したセンサを表１に示す。 Table 1 shows the sensors shown in the figure.
発明者はこれ以外に、Pt類似の材料としてPdとRhを添
加したが、結果はPtに類似でディーゼル排ガス感度を低
下させガソリン排ガス感度を増加させた。またＶ以外に
Fe,Co,Mn等の遷移金属を添加したが、同様にディーゼル
感度を低下させガソリン感度を増加させた。一方加えた
Re,S,Pbはいずれも触媒活性の低い材料で、触媒活性の
低いものの方が添加物として好ましい。 The inventor also added Pd and Rh as Pt-like materials, but the result was similar to Pt, which reduced diesel exhaust gas sensitivity and increased gasoline exhaust gas sensitivity. In addition to V
The addition of transition metals such as Fe, Co, and Mn also reduced diesel sensitivity and increased gasoline sensitivity. Meanwhile added
Re, S, and Pb are all materials having low catalytic activity, and those having low catalytic activity are preferable as additives.
図から明らかなように、WO3薄膜は経時的にディーゼ
ル排ガスに低感度化し、かつ応答速度も低下する。これ
に対しWO3厚膜の経時劣化は小さいが、無添加のもの
（第14図）ではディーゼル排ガスへの応答速度の低下と
低感度化とが生じた。WO3/Re（第４図）ではディーゼル
排ガスへの高感度化と高速応答化とが見られ、WO3/S
（第６図）では低感度化が生じるが高速応答化により感
度の低下以上の効果が得られる。WO3/Pb（第８図）では
僅かな低感度化が生じるが、感度低下の程度が小さい。
更に参考用のWO3/Ru（第10図）でのディーゼル感度は安
定である。発明者は添加物濃度を0.01mol/L水溶液から
0.1mol/L水溶液の範囲で変化させたが、結果に添加物濃
度依存性は小さく、0.03mol/Lの場合と類似の結果が得
られた。As is clear from the figure, the WO3 thin film has a low sensitivity to diesel exhaust gas over time, and the response speed also decreases. On the other hand, although the deterioration with time of the WO3 thick film was small, in the case where it was not added (FIG. 14), the response speed to the diesel exhaust gas was lowered and the sensitivity was lowered. In WO3 / Re (Fig. 4), high sensitivity and high-speed response to diesel exhaust gas are seen, and WO3 / S
In FIG. 6, the sensitivity is reduced, but the effect more than the reduction in sensitivity is obtained by the high-speed response. In WO3 / Pb (FIG. 8), a slight decrease in sensitivity occurs, but the degree of sensitivity decrease is small.
Furthermore, the diesel sensitivity in WO3 / Ru for reference (FIG. 10) is stable. The inventors increased the additive concentration from 0.01 mol / L aqueous solution.
Although the results were varied in the range of 0.1 mol / L aqueous solution, the results showed little dependence on the additive concentration, and similar results to the case of 0.03 mol / L were obtained.
自動車の外気導入制御用ガスセンサは、風や周囲の温
湿度等の変化でノイズを生じる。これらを補償するに
は、補償用のWO3厚膜６をガラス被覆８で外気から遮断
し補償片とすれば良い。第22図に実車走行でのガス感応
部４の出力V1と、補償片で補償済みの出力V1/V2を示
す。V2は補償片に接続した負荷抵抗への出力である。図
の矢印が乗員が臭いを感じた時点を示し、未補償の出力
V1では種々の緩慢なノイズが生じているのに対し、補償
済みの出力V1/V2ではノイズは少なく出力はクリアであ
る。A gas sensor for controlling the introduction of outside air of an automobile generates noise due to changes in wind, ambient temperature and humidity, and the like. In order to compensate these, the WO3 thick film 6 for compensation may be shielded from the outside air by the glass coating 8 to form a compensation piece. FIG. 22 shows the output V1 of the gas sensing unit 4 in actual vehicle running and the output V1 / V2 already compensated by the compensation piece. V2 is an output to the load resistor connected to the compensation piece. The arrow in the figure indicates the time when the occupant felt the smell, and the output was uncompensated
While various slow noises occur in V1, the noise is small and the output is clear in the compensated output V1 / V2.
［発明の効果］ この発明の自動車の外気導入制御用のガスセンサは、 （１） ディーゼル排ガスに高感度でガソリン排ガスに
低感度であり、人の嗅覚が鋭いディーゼル排ガスを高感
度で検出できる、 （２） ガソリン排ガスへの感度は低く、ガソリン排ガ
スとディーゼル排ガスとが共存しても、ディーゼル排ガ
スを検出できる、 （３） 感度や応答性能の経時劣化が小さい、 との効果が得られる。[Effects of the Invention] The gas sensor for controlling the introduction of outside air into a vehicle according to the present invention is capable of: (1) Highly sensitive detection of diesel exhaust gas, which has high sensitivity to diesel exhaust gas and low sensitivity to gasoline exhaust gas, 2) The sensitivity to gasoline exhaust gas is low, and even if gasoline exhaust gas and diesel exhaust gas coexist, diesel exhaust gas can be detected. (3) Sensitivity and response performance are not deteriorated with time.
第１図〜第８図は実施例の特性図、 第９図〜第19図は従来例の特性図、 第20図は実施例のガスセンサの平面図、 第21図はその断面図、 第22図は実車走行での実施例の特性図である。 1 to 8 are characteristic diagrams of the embodiment, FIGS. 9 to 19 are characteristic diagrams of the conventional example, FIG. 20 is a plan view of the gas sensor of the embodiment, FIG. 21 is a cross-sectional view thereof, and FIG. The figure is a characteristic diagram of the embodiment in actual vehicle running.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭60−202345（ＪＰ，Ａ) 特開 平２−126146（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) G01N 27/12 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-202345 (JP, A) JP-A-2-126146 (JP, A) (58) Fields investigated (Int. Cl. 6 , DB name) G01N 27/12
Claims (1)
一員の元素を添加した自動車の外気導入制御用ガスセン
サ。1. A gas sensor for controlling the introduction of outside air of an automobile in which at least one element selected from the group consisting of Re, S and Pb is added to a WO3 thick film.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26976490A JP2958094B2 (en) | 1990-10-08 | 1990-10-08 | Gas sensor for external air introduction control of automobiles |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26976490A JP2958094B2 (en) | 1990-10-08 | 1990-10-08 | Gas sensor for external air introduction control of automobiles |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04145354A JPH04145354A (en) | 1992-05-19 |
| JP2958094B2 true JP2958094B2 (en) | 1999-10-06 |
Family
ID=17476823
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP26976490A Expired - Fee Related JP2958094B2 (en) | 1990-10-08 | 1990-10-08 | Gas sensor for external air introduction control of automobiles |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2958094B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040213701A1 (en) * | 2001-11-14 | 2004-10-28 | Akiyoshi Hattori | Gas sensor and production method for gas sensor |
| DE112005000250B4 (en) * | 2004-01-27 | 2015-12-24 | H2Scan Corp. | Gas sensor with an integrated reference device |
| US7827852B2 (en) * | 2007-12-20 | 2010-11-09 | General Electric Company | Gas sensor and method of making |
| CN109799270B (en) * | 2019-02-18 | 2022-05-13 | 江门市润宇传感器科技有限公司 | Sensitive membrane capable of effectively improving response performance to ethanol gas |
-
1990
- 1990-10-08 JP JP26976490A patent/JP2958094B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04145354A (en) | 1992-05-19 |
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