JPS6358246A - Oxygen sensor - Google Patents
Oxygen sensorInfo
- Publication number
- JPS6358246A JPS6358246A JP20166186A JP20166186A JPS6358246A JP S6358246 A JPS6358246 A JP S6358246A JP 20166186 A JP20166186 A JP 20166186A JP 20166186 A JP20166186 A JP 20166186A JP S6358246 A JPS6358246 A JP S6358246A
- Authority
- JP
- Japan
- Prior art keywords
- titanium oxide
- layer
- electrodes
- oxide layer
- oxygen
- 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.)
- Pending
Links
- 239000001301 oxygen Substances 0.000 title claims abstract description 25
- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 25
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims abstract description 23
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 38
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims abstract description 36
- 239000010410 layer Substances 0.000 claims abstract description 30
- 239000011241 protective layer Substances 0.000 claims abstract description 21
- 239000000758 substrate Substances 0.000 claims abstract description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 abstract description 7
- 239000013078 crystal Substances 0.000 abstract description 7
- 230000015572 biosynthetic process Effects 0.000 abstract description 6
- 238000001514 detection method Methods 0.000 abstract description 5
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 abstract description 4
- 229910052749 magnesium Inorganic materials 0.000 abstract description 4
- 239000011777 magnesium Substances 0.000 abstract description 4
- 230000007423 decrease Effects 0.000 abstract description 2
- 238000010030 laminating Methods 0.000 abstract 1
- 230000001681 protective effect Effects 0.000 abstract 1
- 238000007751 thermal spraying Methods 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 11
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 239000000446 fuel Substances 0.000 description 3
- 229910052697 platinum Inorganic materials 0.000 description 3
- 229910052596 spinel Inorganic materials 0.000 description 3
- 239000011029 spinel Substances 0.000 description 3
- 230000003139 buffering effect Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 150000002926 oxygen Chemical class 0.000 description 2
- 230000004043 responsiveness Effects 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 235000010724 Wisteria floribunda Nutrition 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 231100000989 no adverse effect Toxicity 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
Abstract
Description
【発明の詳細な説明】
〈産業上の利用分野〉
本発明は、電気抵抗変化型の酸化チタン（チタニア）を
用いる酸素センサに関する。この種の酸素センサは、例
えば内燃機関の排気管に装着して該機関に供給される混
合気の空燃比と密接な関係にある排気中の酸素濃度を検
出するもので、空燃比フィードバック制御におけるフィ
ードバック信号の提供などに用いる。DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an oxygen sensor using electrical resistance variable titanium oxide (titania). This type of oxygen sensor is installed, for example, in the exhaust pipe of an internal combustion engine to detect the oxygen concentration in the exhaust gas, which is closely related to the air-fuel ratio of the air-fuel mixture supplied to the engine, and is used in air-fuel ratio feedback control. Used for providing feedback signals, etc.
〈従来の技術〉
従来、酸化チタンを検出素子とする酸素センサとしては
、例えば第２図及び第３図に示すようなものが本出願人
により先に出願されでいる（実願昭６０−０３３３４６
号等参照）。<Prior art> Conventionally, as an oxygen sensor using titanium oxide as a detection element, for example, the one shown in FIGS.
(Refer to No., etc.)
即ち、アルミナ（Ａｊ！ｚｏｚ）の焼結体を基板として
、この基板１の一側に白金（Ｐ Ｌ）製の電極２゜３を
印刷により並設し、これを約１５００℃で焼成する。そ
して、これらの電極２，３を包覆するように酸化チタン
（Ｔ ｉ Ｏ□）を塗布焼結（約１２００℃）し、多孔
性の酸化チタン層４を形成する。これによって、前記電
極２．３の間隙に多孔性の酸化チタンが介在するように
する。また、一方の電極２を電源５の＋側に接続し、他
方の電極３を抵抗６を介して電源５の一側に接続し、前
記抵抗６の両端電圧■。を出力として取り出す。That is, using a sintered body of alumina (Aj!zoz) as a substrate, electrodes 2.3 made of platinum (PL) are printed and arranged in parallel on one side of the substrate 1, and then fired at about 1500°C. Then, titanium oxide (T i O□) is applied and sintered (about 1200° C.) so as to cover these electrodes 2 and 3, thereby forming a porous titanium oxide layer 4. As a result, porous titanium oxide is interposed in the gap between the electrodes 2.3. Further, one electrode 2 is connected to the + side of a power source 5, and the other electrode 3 is connected to one side of the power source 5 via a resistor 6, so that the voltage across the resistor 6 is set to ■. is extracted as output.
更に、かかる酸素センサでは、機関の排気温度が低いと
きのセンサの動作特性等を向上させるために、基板ｌ内
に白金のヒータ７を埋設して酸化チタン層４を加熱でき
るようにしている。８はヒータ７の電源を示す。Furthermore, in this oxygen sensor, a platinum heater 7 is embedded in the substrate 1 to heat the titanium oxide layer 4 in order to improve the sensor's operating characteristics when the engine exhaust temperature is low. 8 indicates a power source for the heater 7.
この酸素センサによると、電極２，３間に介在する酸化
チタン層４の抵抗値が酸素濃度によって変化するので、
この抵抗値変化（電圧■。の変化）を測定することによ
って、被検出気体の酸素濃度を検出することができる。According to this oxygen sensor, the resistance value of the titanium oxide layer 4 interposed between the electrodes 2 and 3 changes depending on the oxygen concentration.
By measuring this change in resistance (change in voltage), the oxygen concentration of the gas to be detected can be detected.
〈発明が解決しようとする問題点〉
ところで、かかる従来の酸素センサによると、周囲温度
等の影響によって特に被検出気体の酸素濃度が高いとき
に、第４図に示すように一側の電極３の周囲に酸化チタ
ンの大きな結晶粒９が形成されることがあり、これによ
り、電極３と酸化チタン層４との接触抵抗が増大し、セ
ンサの検出出力の低下を招くという問題があった。<Problems to be Solved by the Invention> By the way, according to such a conventional oxygen sensor, when the oxygen concentration of the gas to be detected is particularly high due to the influence of the ambient temperature, etc., as shown in FIG. Large crystal grains 9 of titanium oxide may be formed around the titanium oxide layer 4, which increases the contact resistance between the electrode 3 and the titanium oxide layer 4, causing a problem in that the detection output of the sensor decreases.
本発明は上記問題点に鑑みなされたものであり、電極周
囲に酸化チタンの大きな結晶粒が形成されることを阻止
して、酸化チタン層と電極間の接触抵抗の増大を防ぐよ
うにした酸素センサを提供することを目的とする。The present invention has been made in view of the above-mentioned problems, and the present invention has been developed to prevent the formation of large crystal grains of titanium oxide around the electrode, thereby preventing an increase in the contact resistance between the titanium oxide layer and the electrode. The purpose is to provide sensors.
く問題点を解決するための手段〉
そのため本発明では、酸化チタン層を覆う多孔質の保護
層を設けるようにした。Means for Solving the Problems> Therefore, in the present invention, a porous protective layer covering the titanium oxide layer is provided.
〈作用〉
このように保護層を設けるようにすれば、酸化チタン層
が直接被検出気体と接触することがないため、たとえ被
検出気体の酸素濃度が高（とも、この高濃度の酸素によ
る悪影響が保護層によって緩衝されると共に、保護層に
よって周囲温度等の影響を和らげることができ、酸化チ
タンの大きな結晶粒が電極周囲に形成されることを回避
できるものである。<Function> By providing a protective layer in this way, the titanium oxide layer does not come into direct contact with the gas to be detected, so even if the gas to be detected has a high oxygen concentration (even if the oxygen concentration in the gas to be detected is high, there is no adverse effect due to this high concentration of oxygen). is buffered by the protective layer, and the protective layer can alleviate the effects of ambient temperature and the like, and can avoid the formation of large crystal grains of titanium oxide around the electrode.
〈実施例〉
以下に本発明の一実施例を図面に基づいて説明する。尚
、従来例と同一要素には同一符号を付して説明を省略す
る。<Example> An example of the present invention will be described below based on the drawings. Incidentally, the same elements as those in the conventional example are given the same reference numerals and the explanation thereof will be omitted.
第１図に示すように、酸化チタン層４の外周面を覆うよ
うにマグネシウムスピネルを溶射して第１の保護層１０
を形成してあり、更にこの第１の保護層１０を覆うよう
にＴ−アルミナを溶射して第２の保護層１１を形成しで
ある。これらの第１及び第２の保護層１０．１１は何れ
も多孔質であるため、被検出気体はこれらの保護層１０
．１１を介して酸化チタン層４に到達する。As shown in FIG. 1, a first protective layer 10 is formed by thermally spraying magnesium spinel so as to cover the outer peripheral surface of the titanium oxide layer 4.
A second protective layer 11 is formed by thermally spraying T-alumina to cover the first protective layer 10. Since both the first and second protective layers 10.11 are porous, the gas to be detected flows through these protective layers 10.11.
．． The titanium oxide layer 4 is reached through the titanium oxide layer 11.
かかる構成の酸素センサによれば、前記のように被検出
気体が酸化チタン層４と直接接触するものではないため
、周囲の環境変化が酸化チタン層４に与える影響を緩和
できる。具体的には、例えば被検出気体の酸素濃度が高
い場合でも、この高濃度酸素に直接曝されることなく、
保護層１０．１１それぞれの小孔を通過してから酸化チ
タン層４に到達するため、酸化チタン層４が高濃度酸素
に直接曝される場合に比べて悪影響を回避できる。また
、酸化チタン層′４が保護層１０．１１によって覆われ
るため、周囲の温度が直接酸化チタン層４に影響するこ
とがない。従って、電極３の周囲に酸化チタンの大きな
結晶粒が形成されることを抑止でき、酸化チタン層４と
電極３との接触抵抗が増大することなく、安定した検出
出力を得ることができる。According to the oxygen sensor having such a configuration, since the gas to be detected does not come into direct contact with the titanium oxide layer 4 as described above, the influence of changes in the surrounding environment on the titanium oxide layer 4 can be alleviated. Specifically, for example, even if the oxygen concentration of the gas to be detected is high, it can be used without being directly exposed to this high concentration of oxygen.
Since the titanium oxide layer 4 is reached after passing through the small holes in each of the protective layers 10 and 11, adverse effects can be avoided compared to when the titanium oxide layer 4 is directly exposed to high concentration oxygen. Furthermore, since the titanium oxide layer '4 is covered by the protective layer 10.11, the ambient temperature does not directly affect the titanium oxide layer 4. Therefore, formation of large crystal grains of titanium oxide around the electrode 3 can be suppressed, and a stable detection output can be obtained without increasing the contact resistance between the titanium oxide layer 4 and the electrode 3.
また、本実施例では、比表面積の大きなＴ−アルミナ（
比表面積１０〜５００ｍ／ｇ）を外側の保護層１１とし
、更にその内側に比表面積の小さなマグネシウムスピネ
ル（比表面積０．１〜ｂ保護層１０として設けるように
しであるため、酸素センサの応答性を確保した上で良好
に周囲の環境変化による悪影響を緩和できる。即ち、周
囲の影響を極力避けるために比表面積の小さい材料を厚
くして被覆し保護層とした場合には、被検出気体が酸化
チタン層４に到達し難くなるため、被検出気体の酸素濃
度変化に対する応答遅れが発生する惧れがある。しかし
ながら、本実施例のように、まず比表面積の大きなγ−
アルミナによっである程度の緩衝作用を行わせ、その後
に比表面積の小さなマグネシウムスピネルによって充分
な緩衝作用を行わせるようにすれば、応答性を悪化させ
ることなく周囲環境による悪影響を良好に緩和すること
が可能となるものである。In addition, in this example, T-alumina (T-alumina) with a large specific surface area (
Since the outer protective layer 11 has a specific surface area of 10 to 500 m/g, and the protective layer 10 of magnesium spinel with a small specific surface area (specific surface area of 0.1 to b) is provided inside, the responsiveness of the oxygen sensor is improved. In other words, if a protective layer is made of a thick material with a small specific surface area in order to avoid the influence of the surrounding environment as much as possible, the gas to be detected can be Since it becomes difficult to reach the titanium oxide layer 4, there is a risk that a delay in response to changes in the oxygen concentration of the gas to be detected may occur.However, as in this example, first, the γ-
If alumina provides a certain degree of buffering effect, and then magnesium spinel, which has a small specific surface area, provides a sufficient buffering effect, the negative effects of the surrounding environment can be effectively alleviated without deteriorating responsiveness. is possible.
尚、本実施例においては、保護層を第１及び第２保護層
１０．１１の２重構成としたが、保護層は１層のみでも
良く、また材質も本実施例に示したものに限るものでは
ないことは明らかである。In this example, the protective layer has a double structure of the first and second protective layers 10.11, but the protective layer may be only one layer, and the material is limited to those shown in this example. It is clear that it is not a thing.
〈発明の効果〉
以上説明したように本発明によると、電極の周囲に酸化
チタンの大きな結晶粒が形成されることを阻止すること
ができるため、酸化チタン層と電極との接触抵抗の増大
を未然に防止し、安定した検出出力を得ることができる
ようになるという効果がある。<Effects of the Invention> As explained above, according to the present invention, it is possible to prevent the formation of large crystal grains of titanium oxide around the electrode, thereby preventing an increase in the contact resistance between the titanium oxide layer and the electrode. This has the effect of preventing such occurrences and making it possible to obtain stable detection outputs.
第１図は本発明の一実施例を示す断面図、第２図は従来
例を示す概略構成図、第３図は第２図のｍ−ｍ断面図、
第４図は第３図の部分拡大図である。
ｌ・・・アルミナ製基板 ２，３・・・電極４・・・
酸化チタン層 １０・・・第１の保護層１１・・・第
２の保護層
特許出願人 日本電子機器株式会社
代理人 弁理士 笹 島 富二誰
第１図
トｌFIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a schematic configuration diagram showing a conventional example, and FIG. 3 is a sectional view taken along the line m-m in FIG. 2.
FIG. 4 is a partially enlarged view of FIG. 3. l... Alumina substrate 2, 3... Electrode 4...
Titanium oxide layer 10...First protective layer 11...Second protective layer Patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fuji Sasashima Who Figure 1
Claims (1)
化チタン層を積層してなり、前記並設した電極間に介在
する酸化チタン層の電気抵抗変化に基づいて酸素濃度を
検出する構成の酸素センサにおいて、前記酸化チタン層
を覆う多孔質の保護層を設けたことを特徴とする酸素セ
ンサ。A pair of electrodes are arranged in parallel on one side of the substrate, and a titanium oxide layer is laminated on the pair of electrodes, and the oxygen concentration is adjusted based on the change in electrical resistance of the titanium oxide layer interposed between the parallel electrodes. An oxygen sensor configured to detect oxygen, characterized in that a porous protective layer covering the titanium oxide layer is provided.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20166186A JPS6358246A (en) | 1986-08-29 | 1986-08-29 | Oxygen sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20166186A JPS6358246A (en) | 1986-08-29 | 1986-08-29 | Oxygen sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6358246A true JPS6358246A (en) | 1988-03-14 |
Family
ID=16444800
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20166186A Pending JPS6358246A (en) | 1986-08-29 | 1986-08-29 | Oxygen sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6358246A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2019191123A (en) * | 2018-04-27 | 2019-10-31 | 新コスモス電機株式会社 | Chlorofluorocarbon gas sensor |
-
1986
- 1986-08-29 JP JP20166186A patent/JPS6358246A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2019191123A (en) * | 2018-04-27 | 2019-10-31 | 新コスモス電機株式会社 | Chlorofluorocarbon gas sensor |
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