JPH0245808Y2 - - Google Patents
Info
- Publication number
- JPH0245808Y2 JPH0245808Y2 JP1983068666U JP6866683U JPH0245808Y2 JP H0245808 Y2 JPH0245808 Y2 JP H0245808Y2 JP 1983068666 U JP1983068666 U JP 1983068666U JP 6866683 U JP6866683 U JP 6866683U JP H0245808 Y2 JPH0245808 Y2 JP H0245808Y2
- Authority
- JP
- Japan
- Prior art keywords
- solid electrolyte
- heater
- oxygen concentration
- rod
- exhaust gas
- 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.)
- Expired
Links
- 239000007784 solid electrolyte Substances 0.000 claims description 65
- 239000007789 gas Substances 0.000 claims description 42
- 239000001301 oxygen Substances 0.000 claims description 37
- 229910052760 oxygen Inorganic materials 0.000 claims description 37
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 36
- 239000000919 ceramic Substances 0.000 claims description 18
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 16
- 229910052751 metal Inorganic materials 0.000 claims description 10
- 239000002184 metal Substances 0.000 claims description 10
- 229910052697 platinum Inorganic materials 0.000 claims description 8
- 230000001681 protective effect Effects 0.000 claims description 7
- 238000002955 isolation Methods 0.000 claims 1
- 238000010438 heat treatment Methods 0.000 description 13
- 238000002485 combustion reaction Methods 0.000 description 7
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 238000013021 overheating Methods 0.000 description 4
- 239000000446 fuel Substances 0.000 description 3
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 3
- 229910052721 tungsten Inorganic materials 0.000 description 3
- 239000010937 tungsten Substances 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 230000005856 abnormality Effects 0.000 description 2
- 239000011247 coating layer Substances 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 229910052596 spinel Inorganic materials 0.000 description 2
- 239000011029 spinel Substances 0.000 description 2
- 239000000454 talc Substances 0.000 description 2
- 229910052623 talc Inorganic materials 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910001120 nichrome Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
Description
【考案の詳細な説明】
本考案は、内燃機関より排出される排気ガス中
の酸素濃度を検出するための酸素濃度検出器に係
り、特に有底筒状固体電解質の筒内に棒状加熱器
を配置した加熱器付酸素濃度検出器に関する。[Detailed description of the invention] The present invention relates to an oxygen concentration detector for detecting the oxygen concentration in exhaust gas discharged from an internal combustion engine, and in particular, a rod-shaped heater is installed inside a bottomed cylindrical solid electrolyte cylinder. The present invention relates to an oxygen concentration detector equipped with a heater.
従来、ジルコニア等の酸素イオン伝導性の固体
電解質を用いて、酸素濃淡電池の原理により、自
動車等の内燃機関から排出される排気ガス中の酸
素濃度を検知し、かかる内燃機関の空燃比を制御
することが知られている。そして、この種の酸素
濃度検出器としては、有底筒状のジルコニア固体
電解質の内外面に多孔質の白金電極を付与し、筒
内面の電極を大気と連通して基準酸素濃度の電極
とし、一方筒外面の電極を被測定ガスである排気
ガス中に曝して測定電極としている。そして、そ
れら基準電極と測定電極との間の酸素濃度の差に
基づく起電力を測定することにより、被測定ガス
中の酸素濃度を測定しているのである。 Conventionally, an oxygen ion conductive solid electrolyte such as zirconia is used to detect the oxygen concentration in the exhaust gas emitted from an internal combustion engine such as an automobile and control the air-fuel ratio of the internal combustion engine based on the principle of an oxygen concentration battery. It is known to do. This type of oxygen concentration detector has porous platinum electrodes provided on the inner and outer surfaces of a bottomed cylindrical zirconia solid electrolyte, and the electrode on the inner surface of the cylinder is connected to the atmosphere to serve as an electrode for reference oxygen concentration. On the other hand, the electrode on the outer surface of the cylinder is exposed to exhaust gas, which is the gas to be measured, to serve as a measurement electrode. The oxygen concentration in the gas to be measured is measured by measuring the electromotive force based on the difference in oxygen concentration between the reference electrode and the measurement electrode.
しかしながら、この起電力は、固体電解質があ
る程度加熱されていないと不安定であり、このた
め内燃機関の排気ガスが低温となるアイドリング
時、あるいは始動直後には、正確な空燃比の制御
ができないという欠点があつた。 However, this electromotive force is unstable unless the solid electrolyte is heated to a certain degree, and for this reason, it is impossible to accurately control the air-fuel ratio during idling or immediately after engine startup, when the exhaust gas of the internal combustion engine is at a low temperature. There were flaws.
この問題を解決するために、発熱線を棒状の絶
縁体表面に巻きつけた加熱器を固体電解質の筒内
部に挿入したり（特開昭54−13396号）、抵抗線コ
イルと熱伝導性の良い絶縁性の粉末を金属製のス
リーブ内に充填した、いわゆるシーズヒーターを
固体電解質の筒内部に挿入（特開昭54−22894号）
して、固体電解質を強制的に加熱することが堤案
されている。 In order to solve this problem, we inserted a heater with a heating wire wrapped around the surface of a rod-shaped insulator into the solid electrolyte tube (Japanese Patent Application Laid-Open No. 13396/1983), and A so-called sheathed heater, which is a metal sleeve filled with powder with good insulating properties, is inserted into a solid electrolyte cylinder (Japanese Patent Application Laid-Open No. 54-22894).
It has been proposed that the solid electrolyte be forcibly heated.
しかしながら、この種の従来の加熱器付酸素濃
度検出器は、内燃機関の排気ガスが高温になつた
場合において、固体電解質が加熱を受け過ぎて、
多孔質白金電極が再結晶して排気ガスとの反応速
度が遅くなつたり、また多孔質白金電極を保護す
るスピネルコーテイング層にクラツクが生じた
り、剥離したりする欠点があり、さらに加熱器自
体も、自己発熱による加熱と排気ガスによる加熱
とが相まつて異常に高温となり、内部の抵抗線が
断線したりする欠点があつたのである。 However, in this type of conventional oxygen concentration detector with a heater, when the exhaust gas of an internal combustion engine becomes high temperature, the solid electrolyte is heated too much.
There are drawbacks such as recrystallization of the porous platinum electrode, which slows down the reaction rate with exhaust gas, and cracks or peeling of the spinel coating layer that protects the porous platinum electrode.Furthermore, the heater itself The heating caused by self-heating and the heating caused by the exhaust gas combined resulted in an abnormally high temperature, which caused the internal resistance wire to break.
ところが、この問題を幾分でも和らげるため
に、加熱器の発熱量を小さく抑えると、排気ガス
が低温である時には加熱不足が生じたり、またエ
ンジン始動時から加熱が行われても、酸素濃度検
出器の起電力が正確に発生するまでに時間がかか
り過ぎる等という、新たな問題が惹起されるので
ある。 However, if the heating value of the heater is kept low in order to alleviate this problem, insufficient heating may occur when the exhaust gas is at a low temperature, or even if heating starts from the time the engine starts, oxygen concentration detection may be difficult. New problems arise, such as the fact that it takes too much time for the electromotive force of the device to be generated accurately.
さらに、エンジン始動時あるいは寒冷時には、
バツテリ電圧が低下して、前記加熱不足の問題に
拍車がかかり、またエンジン回転数が高くなつて
バツテリ電圧が上昇した場合には、排気ガスも高
温になり、加熱器の発熱量も増大して、前記過熱
の問題にも拍車がかかる欠点を有していたのであ
る。 Furthermore, when starting the engine or when it is cold,
The battery voltage decreases, accelerating the problem of insufficient heating, and if the engine speed increases and the battery voltage increases, the exhaust gas also becomes high temperature, and the amount of heat generated by the heater increases. However, the problem of overheating was also exacerbated.
本考案は、かかる欠点を解決した酸素濃度検出
器であつて、その特徴とするところは、内外面に
多孔質白金電極を有する有底筒状の固体電解質
と、該固体電解質の閉鎖端を排気ガス中に曝す一
方、その筒内を排気ガスより気密に隔離して収納
するハウジングと、前記固体電解質の閉鎖端側の
外周部を取り囲み、排気ガスの導入口を有する金
属製保護カバーと、前記固体電解質の筒内に挿入
される棒状加熱器とを有する加熱器付酸素濃度検
出器において、前記棒状加熱器を、正の抵抗温度
係数を有するセラミツクヒーターとするととも
に、前記固体電解質の内面と棒状加熱器の外面と
の間の間隙を、該棒状加熱器の両側の総計で0.3
mm〜0.7mmとした加熱器付酸素濃度検出器にある。
以下、図示の実施例に基づいて、本考案の構成を
詳細に説明する。 The present invention is an oxygen concentration detector that solves these drawbacks, and its features include a bottomed cylindrical solid electrolyte with porous platinum electrodes on the inner and outer surfaces, and a closed end of the solid electrolyte that is evacuated. a housing that is exposed to the gas but hermetically isolates the inside of the cylinder from the exhaust gas; a metal protective cover that surrounds the outer periphery of the closed end of the solid electrolyte and has an exhaust gas inlet; In an oxygen concentration detector with a heater that has a rod-shaped heater inserted into a cylinder of a solid electrolyte, the rod-shaped heater is a ceramic heater having a positive temperature coefficient of resistance, and the inner surface of the solid electrolyte and the rod-shaped The total gap between the outer surface of the heater and both sides of the rod-shaped heater is 0.3.
Located in an oxygen concentration detector with a heater that measures mm to 0.7 mm.
EMBODIMENT OF THE INVENTION Hereinafter, the structure of this invention will be described in detail based on the illustrated embodiment.
第１図において、有底筒状の固体電解質１は、
排気ガス管（図示せず）内を通る排気ガス（図示
せず）に対して、ハウジング２内にタルク３、金
属製ワツシヤ４、および金属製リング５を用い
て、その筒内が気密に収納され、またかかる固体
電解質１の筒内には棒状加熱器６が同心的に収納
されている。なお、図示はしないが、有底筒状の
固体電解質１の閉鎖端の内外面には、多孔質な白
金電極が、従来と同様にして設けられている。そ
して、かかる有底筒状固体電解質１の閉鎖端側の
外周部には、排気ガスが直接固体電解質１に当た
るのを防ぐための有底筒状の金属製保護カバー７
が設けられ、その上端側がハウジング２の底面に
固着されている。 In FIG. 1, a cylindrical solid electrolyte 1 with a bottom is
A talc 3, a metal washer 4, and a metal ring 5 are used in the housing 2 to airtightly house the exhaust gas (not shown) passing through the exhaust gas pipe (not shown). A rod-shaped heater 6 is concentrically housed within the cylinder of the solid electrolyte 1. Although not shown, porous platinum electrodes are provided on the inner and outer surfaces of the closed end of the bottomed cylindrical solid electrolyte 1 in the same manner as in the prior art. A bottomed cylindrical metal protective cover 7 is provided on the outer periphery of the closed end side of the bottomed cylindrical solid electrolyte 1 to prevent exhaust gas from directly hitting the solid electrolyte 1.
is provided, and its upper end side is fixed to the bottom surface of the housing 2.
また、この金属製保護カバー７には、第３図に
示されるように、その側壁面において金属製保護
カバー７の内側に向かつてルーバー１１が切り起
こされ、排気ガス導入口１２が形成されている。 Further, as shown in FIG. 3, this metal protective cover 7 has a louver 11 cut out toward the inside of the metal protective cover 7 on its side wall surface, and an exhaust gas inlet 12 is formed. There is.
そして、第１図において固体電解質１の筒内に
挿入、配置された棒状加熱器６は、第２図に示さ
れるように、例えばアルミナ質の棒状セラミツク
８の側壁面に、発熱部９と導電部１０を形成する
ようにタングステンを主成分とする抵抗材料（ペ
ースト状）を印刷し、さらにその外表面上に同じ
くアルミナ質の薄板状セラミツク（図示せず）を
巻きつけた後、構成することによつて形成された
セラミツクヒーターであり、ここでは固体電解質
の内径と棒状加熱器６の外径との間隙が、両側総
計で0.5mmとされている。 As shown in FIG. 2, the rod-shaped heater 6 inserted and placed in the cylinder of the solid electrolyte 1 in FIG. A resistive material (paste-like) containing tungsten as a main component is printed to form the portion 10, and a thin plate-shaped ceramic (not shown) made of alumina is further wrapped around the outer surface of the resistive material (paste), and then constructed. This is a ceramic heater formed by the above method, in which the gap between the inner diameter of the solid electrolyte and the outer diameter of the rod-shaped heater 6 is 0.5 mm in total on both sides.
また、本実施例では、かかる棒状加熱器６にお
ける発熱体が、タングステン焼付抵抗体にて形成
され、該加熱器の抵抗温度係数が0.5％／℃とさ
れており、これによつて排気ガスが高温の時に
は、その抵抗値が増大して発熱量が減少し、固体
電解質および棒状加熱器自体の過熱を防止するよ
うになるのである。また、低温時には、抵抗値が
減少して発熱量が増大するので、エンジン始動直
後の酸素濃度検出器の起電力発生までの時間が短
く、またアイドリング時等にも加熱が十分に行わ
れるれるのである。 In addition, in this embodiment, the heating element in the rod-shaped heater 6 is formed of a tungsten baked resistor, and the temperature coefficient of resistance of the heater is set to 0.5%/°C. At high temperatures, the resistance value increases and the amount of heat generated decreases, preventing the solid electrolyte and the rod-shaped heater itself from overheating. In addition, at low temperatures, the resistance value decreases and the amount of heat generated increases, so the time required for the oxygen concentration detector to generate an electromotive force immediately after the engine starts is shortened, and sufficient heating occurs even when idling. be.
第４図は、排気ガス温度TG（℃）と固体電解質
の温度TS（℃）の関係を示すもので、図中、曲線
ａは本考案に従うセラミツクヒーターを用いた場
合、曲線ｂは本考案に従うセラミツクヒーターを
用いた場合とエンジン始動時から起電力発生まで
の時間がほぼ同一となるニクロム線を用いたシー
ズヒーターの場合を示している。そこにおいて、
ガス温度が800℃のときに、本考案に従うセラミ
ツクヒーターを用いた曲線ａでは固体電解質の温
度は800℃、従来のシーズヒーターを用いた曲線
ｂでは950℃であり、それ故本考案のものは排気
ガス温度が高い場合に過熱しないことを示してい
るのである。 Figure 4 shows the relationship between the exhaust gas temperature T G (°C) and the solid electrolyte temperature T S (°C). In the figure, curve a is when the ceramic heater according to the present invention is used, and curve b is This figure shows the case of using a ceramic heater according to the invention and the case of a sheathed heater using nichrome wire, in which the time from engine start to generation of electromotive force is almost the same. There,
When the gas temperature is 800°C, the temperature of the solid electrolyte is 800°C in curve a using the ceramic heater according to the present invention, and 950°C in curve b using the conventional sheathed heater. This shows that it does not overheat when the exhaust gas temperature is high.
また、かかる第４図の測定に用いられた二つの
酸素濃度検出器について、ガス温度を800℃とし
て、連続300時間の経過の後に、それぞれの検出
器内の固体電解質の外観及びヒーターの異常を調
査したところ、従来のシーズヒーターを用いたも
のでは、固体電解質の外表面に付着させたスピネ
ルコーテイング層に亀裂発生が見られ、またヒー
ターは断線したものが70％あつたのに対し、本考
案のものでは、固体電解質およびセラミツクヒー
ターに何の異常も認められなかつた。 Regarding the two oxygen concentration detectors used in the measurements shown in Figure 4, after 300 continuous hours at a gas temperature of 800°C, we confirmed the appearance of the solid electrolyte in each detector and abnormalities in the heater. When we investigated, we found that with conventional sheathed heaters, cracks were observed in the spinel coating layer attached to the outer surface of the solid electrolyte, and 70% of heaters had broken wires, whereas with the present invention No abnormalities were observed in the solid electrolyte or ceramic heater.
このように、酸素濃度検出器に正の抵抗温度係
数を有するセラミツクヒーターを用いた場合、エ
ンジン始動直後にはヒーターの抵抗値が極めて小
さいため、大きな発熱量が得られ、以て固体電解
質の加熱が急速に行われ、起電力が速やかに発生
するのであり、そして、アイドリング時のように
ガス温度が低いときには、未だ抵抗値が低いた
め、発熱量が大きく、それ故固体電解質を十分に
加熱できることとなる。また、ガス温度が高温に
なつたときは、抵抗値は著しく増大するため（ガ
ス温度800℃で、室温時の約５倍）、固体電解質お
よびヒーターが過熱されることがないのである。
このような発熱量の制御機能をもつた正の抵抗温
度係数を有するセラミツクヒーターの抵抗温度係
数は、内燃機関用の酸素濃度検出器に適用する場
合において、0.3％／℃以上とするのが望ましく、
そしてセラミツクヒーターの発熱体を印刷する際
のペースト中の金属粉末の種類、ガラスフリツト
の量、等を適宜選択することにより、そのような
正の抵抗温度係数が所望の値に調整され得るので
ある。 In this way, when a ceramic heater with a positive temperature coefficient of resistance is used in the oxygen concentration detector, the resistance of the heater is extremely small immediately after the engine starts, so a large amount of heat is generated, which is used to heat the solid electrolyte. is carried out rapidly, and an electromotive force is generated quickly. Furthermore, when the gas temperature is low, such as when idling, the resistance value is still low, so the calorific value is large, and therefore the solid electrolyte can be sufficiently heated. becomes. Furthermore, when the gas temperature becomes high, the resistance value increases significantly (at a gas temperature of 800°C, about five times that at room temperature), so the solid electrolyte and heater are not overheated.
It is desirable that the temperature coefficient of resistance of a ceramic heater with a positive temperature coefficient of resistance that has a function of controlling the amount of heat generated is 0.3%/°C or more when applied to an oxygen concentration detector for an internal combustion engine. ,
By appropriately selecting the type of metal powder in the paste, the amount of glass frit, etc. when printing the heating element of the ceramic heater, such a positive temperature coefficient of resistance can be adjusted to a desired value.
次に、本考案において棒状加熱器の外面と固体
電解質の内面との間の間隙を、該棒状加熱器の両
側の総計で0.3mm〜0.7mmに限定する理由を述べ
る。 Next, the reason why the gap between the outer surface of the rod-shaped heater and the inner surface of the solid electrolyte is limited to 0.3 mm to 0.7 mm in total on both sides of the rod-shaped heater in the present invention will be described.
棒状加熱器の外面（外径）と固体電解質の内面
（内径）との間の間隙は、一般に大きい程、製造
時の組立が容易であるが、その間隙が大きくなる
と、棒状加熱器と固体電解質との距離が大きくな
り、熱抵抗体としての空気層が厚くなるため、同
一発熱量の棒状加熱器の場合には、その間隙が大
きい程、固体電解質の温度が低くなり、従つて、
排気ガスの温度が低いアイドリング時等において
は、固体電解質の加熱が不十分となり、起電力が
不安定となるとともに、エンジン始動時から固体
電解質が十分に加熱され得ず、酸素濃度検出器が
排気ガス中の酸素濃度に対応する起電力を発生す
るまでの時間が遅くなる。これを改善するため
に、棒状加熱器の発熱量を増大すると、排気ガス
が高温になつた際、固体電解質および棒状加熱器
自体の過熱が惹起されやすく、固体電解質に設け
られている白金電極の寿命および棒状加熱器自体
の寿命も短くなる。 In general, the larger the gap between the outer surface (outer diameter) of the rod-shaped heater and the inner surface (inner diameter) of the solid electrolyte, the easier the assembly during manufacturing. As the distance from
When the exhaust gas temperature is low, such as during idling, the solid electrolyte is insufficiently heated and the electromotive force becomes unstable, and the solid electrolyte is not heated sufficiently from the time the engine is started, and the oxygen concentration detector detects the exhaust gas. The time required to generate an electromotive force corresponding to the oxygen concentration in the gas is delayed. In order to improve this problem, if the calorific value of the rod-shaped heater is increased, when the exhaust gas becomes high temperature, the solid electrolyte and the rod-shaped heater itself tend to overheat. The lifespan and the lifespan of the bar heater itself are also shortened.
さらに、間隙が大きいと、固体電解質に対する
棒状加熱器の配置位置に偏心が生じやすく、この
ため棒状加熱器に近い固体電解質部分が、排気ガ
スの高温時に異常な過熱を受けることにより、白
金電極の劣化が促進され、そして、排気ガスが低
温の時には、棒状加熱器より遠い部分の固体電解
質の加熱が不十分となる問題を生じる。 Furthermore, if the gap is large, eccentricity tends to occur in the placement position of the rod-shaped heater with respect to the solid electrolyte, and as a result, the solid electrolyte part near the rod-shaped heater receives abnormal overheating at the high temperature of the exhaust gas, and the platinum electrode Deterioration is accelerated, and when the exhaust gas is at a low temperature, a problem arises in that the solid electrolyte in the portion farther from the rod heater is insufficiently heated.
従つて、固体電解質と棒状加熱器との間隙はは
小さい方が、少ない発熱量で固体電解質を十分に
加熱できるとともに、高温での過熱が少ないので
あり、そして固体電解質の劣化、セラミツクヒー
ターの劣化を勘案すると、前記間隙（総計）は
0.7mm以下とするのが良いのである。 Therefore, the smaller the gap between the solid electrolyte and the rod-shaped heater, the more the solid electrolyte can be sufficiently heated with less heat generation, and there will be less overheating at high temperatures, which will prevent deterioration of the solid electrolyte and ceramic heater. Taking into account, the gap (total) is
It is better to set it to 0.7 mm or less.
また、かかる間隙の下限を0.3mmとするのは、
これ以下であると、固体電解質筒内の基準空気の
流通が悪く、例えば何らかの原因で基準空気の酸
素濃度を低下させるようなガスが侵入した際、筒
内の空気流通が悪いと、回復するのに極めて長時
間を要し、酸素濃度検出器の発生する起電力が不
安定となるからである。 In addition, the lower limit of this gap is set to 0.3 mm because
If it is less than this, the flow of the reference air inside the solid electrolyte cylinder is poor. For example, if a gas that lowers the oxygen concentration of the reference air enters for some reason, it will be difficult to recover if the air flow inside the cylinder is poor. This is because it takes an extremely long time and the electromotive force generated by the oxygen concentration detector becomes unstable.
因みに、第５図及び第６図は、そのような間隙
と固体電解質温度または固体電解質の筒内雰囲気
置換時間との関係を示すが、それらの結果からし
ても、かかる間隙を0.3〜0.7mmとするのが有効な
のである。即ち、第５図は、第１図に示される如
き酸素濃度検出器の構成において、筒状固体電解
質１と棒状加熱器６との間の間隙（棒状加熱器の
両側の総計）を種々異ならしめたときの固体電解
質１の温度変化を示しているが、そこにおいて、
そのような間隙が0.3mmよりも小さくなると、排
気ガスが高温であるときの固体電解質温度の上昇
が激しく、一方該間隙が0.7mmよりも大きくなる
と、排気ガスが低温であるときの固体電解質温度
の低下が大となるのである。また、第６図は、筒
状固体電解質１の内部先端に0.01c.c.のガソリンを
入れて基準雰囲気（空気）を変化させた後、酸素
濃度検出器の起電力が安定になるまでの時間、換
言すれば基準大気が固体電解質１内に充分に流通
して、その内部雰囲気が大気にて置換されるまで
の時間を、各種の間隙の場合について計測した結
果を示すものであるが、この結果においても、そ
のような間隙が0.3mmよりも小さくなると、固体
電解質１の内部雰囲気の置換時間が長なり、応答
性、測定の精度・信頼性等に問題を惹起すること
となるのである。 Incidentally, FIGS. 5 and 6 show the relationship between such a gap and the solid electrolyte temperature or solid electrolyte cylinder atmosphere replacement time, and from those results, it is clear that such a gap is 0.3 to 0.7 mm. It is effective to do so. That is, FIG. 5 shows the configuration of the oxygen concentration detector as shown in FIG. 1, in which the gap between the cylindrical solid electrolyte 1 and the rod-shaped heater 6 (total of both sides of the rod-shaped heater) is varied. It shows the temperature change of solid electrolyte 1 when
When such a gap is smaller than 0.3 mm, the solid electrolyte temperature increases sharply when the exhaust gas is hot, while when the gap is larger than 0.7 mm, the solid electrolyte temperature increases when the exhaust gas is cold. This results in a large decrease in In addition, Figure 6 shows the time it takes for the electromotive force of the oxygen concentration detector to become stable after changing the reference atmosphere (air) by putting 0.01cc of gasoline into the internal tip of the cylindrical solid electrolyte 1, in other words. This shows the results of measuring the time required for the reference atmosphere to sufficiently flow into the solid electrolyte 1 and for the internal atmosphere to be replaced by the atmosphere for various gaps. However, if such a gap becomes smaller than 0.3 mm, the time required to replace the internal atmosphere of the solid electrolyte 1 becomes long, causing problems in response, measurement accuracy, reliability, etc.
なお、本考案において用いられるセラミツクヒ
ーターは、先に述べた棒状セラミツクに印刷・焼
付けして発熱部を形成せしめたものの他、正の抵
抗温度係数の大きいタングステン、あるいはニツ
ケル、白金等の発熱線をセラミツク中に埋設した
ものでも良く、更にその他の手法で得られたもの
であつても何等差支えないが、その発熱部を、固
体電解質の排気ガスに曝される部分のみに配置す
るように構成するのが良い。 In addition to the ceramic heater used in the present invention, in addition to the above-mentioned one in which the heating part is formed by printing and baking on the bar-shaped ceramic, heating wires made of tungsten, nickel, platinum, etc., which have a large positive temperature coefficient of resistance, are used. It may be buried in ceramic or obtained by other methods, but the heat generating part should be arranged only in the part of the solid electrolyte that is exposed to the exhaust gas. It's good.
以上詳記のように、本考案に従う酸素濃度検出
器は、棒状加熱器として、正の抵抗温度係数を有
するセラミツクヒーターを用い、さらに固体電解
質の内面と棒状加熱器の外面との間隙を、該棒状
加熱器の両側の総計で0.3mm〜0.7mmとすることに
より、排気ガスが低温である場合においても固体
電解質が十分り加熱され、エンジン始動時から起
電力が発生するまでの時間が極めて短く、また排
気ガスが高温の時には固体電解質、棒状加熱器の
過熱が少なく、さらに、固体電解質筒内での大気
の流通も良く、安定な起電力が長時間得られ、信
頼性の高い酸素濃度検出器であつて、内燃機関の
空燃比を制御するための酸素濃度検出器として、
産業上極めて有用である。 As described in detail above, the oxygen concentration detector according to the present invention uses a ceramic heater having a positive temperature coefficient of resistance as the rod-shaped heater, and further increases the gap between the inner surface of the solid electrolyte and the outer surface of the rod-shaped heater. By setting the total thickness on both sides of the rod-shaped heater to 0.3 mm to 0.7 mm, the solid electrolyte is sufficiently heated even when the exhaust gas is at a low temperature, and the time from engine startup to generation of electromotive force is extremely short. In addition, when the exhaust gas is at high temperature, the solid electrolyte and rod-shaped heater are not overheated, and the air circulation inside the solid electrolyte cylinder is also good, allowing stable electromotive force to be obtained for a long time and highly reliable oxygen concentration detection. As an oxygen concentration detector for controlling the air-fuel ratio of an internal combustion engine,
It is extremely useful in industry.
第１図は本考案の加熱器付酸素濃度検出器の一
実施例を示す断面図であり、第２図は本考案の加
熱器付酸素濃度検出器に用いられる棒状加熱器の
一具体例を示す説明図、さらに第３図は本考案の
加熱器付酸素濃度検出器に用いられる金属製保護
カバーの一具体例を示す斜視説明図、第４図は、
従来の加熱器付酸素濃度検出器と本考案の加熱器
付酸素濃度検出器の排気ガス温度に対する固体電
解質の温度の関係を示すグラフである。第５図
は、固体電解質と棒状加熱器との間の間隙と固体
電解質温度との関係を示すグラフであり、第６図
は、そのような間隙と固体電解質の内部雰囲気置
換時間との関係を示すグラフである。
１：有底筒状固体電解質、２：ハウジング、
３：タルク、４：ワツシヤ、５：リング、６：棒
状加熱器、７：保護カバー、８：棒状セラミツ
ク、９：発熱部、１０：導電部、１１：ルーバ
ー、１２：排気ガス導入口。
FIG. 1 is a sectional view showing an embodiment of the oxygen concentration detector with a heater of the present invention, and FIG. 2 is a sectional view showing a specific example of the rod-shaped heater used in the oxygen concentration detector with a heater of the present invention. Further, FIG. 3 is a perspective explanatory view showing a specific example of a metal protective cover used in the oxygen concentration detector with heater of the present invention, and FIG.
It is a graph showing the relationship between the temperature of the solid electrolyte and the exhaust gas temperature of a conventional oxygen concentration detector with a heater and an oxygen concentration detector with a heater of the present invention. FIG. 5 is a graph showing the relationship between the gap between the solid electrolyte and the rod-shaped heater and the solid electrolyte temperature, and FIG. 6 is a graph showing the relationship between the gap and the internal atmosphere replacement time of the solid electrolyte. This is a graph showing. 1: Bottomed cylindrical solid electrolyte, 2: Housing,
3: Talc, 4: Washer, 5: Ring, 6: Rod-shaped heater, 7: Protective cover, 8: Rod-shaped ceramic, 9: Heat generating part, 10: Conductive part, 11: Louver, 12: Exhaust gas inlet.
Claims (1)
固体電解質と、該固体電解質の閉鎖端を排気ガ
ス中に曝す一方、その筒内を排気ガスより気密
に隔離して収納するハウジングと、前記固体電
解質の閉鎖端側の外周部を取り囲み、排気ガス
の導入口を有する金属製保護カバーと、前記固
体電解質の筒内に挿入される棒状加熱器とを有
する加熱器付酸素濃度検出器において、前記棒
状加熱器を、正の抵抗温度係数を有するセラミ
ツクヒーターとするとともに、前記固体電解質
の内面と棒状加熱器の外面との間の間隙を、該
棒状加熱器の両側の総計で0.3mm〜0.7mmとした
ことを特徴とする加熱器付酸素濃度検出器。 (2) 前記セラミツクヒーターの抵抗温度係数が、
0.3％／℃以上であることを特徴とする実用新
案登録請求の範囲第１項記載の加熱器付酸素濃
度検出器。[Claims for Utility Model Registration] (1) A bottomed cylindrical solid electrolyte having porous platinum electrodes on its inner and outer surfaces, and a closed end of the solid electrolyte exposed to exhaust gas, while the inside of the cylinder is exposed to exhaust gas. a housing to be housed in airtight isolation; a metal protective cover surrounding the outer periphery of the closed end of the solid electrolyte and having an exhaust gas inlet; and a rod-shaped heater inserted into the cylinder of the solid electrolyte. In the oxygen concentration detector with a heater, the rod-shaped heater is a ceramic heater having a positive temperature coefficient of resistance, and the gap between the inner surface of the solid electrolyte and the outer surface of the rod-shaped heater is An oxygen concentration detector with a heater, characterized in that the total length on both sides of the heater is 0.3 mm to 0.7 mm. (2) The temperature coefficient of resistance of the ceramic heater is
The oxygen concentration detector with a heater according to claim 1 of the utility model registration claim, characterized in that the oxygen concentration is 0.3%/°C or more.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6866683U JPS59175169U (en) | 1983-05-09 | 1983-05-09 | Oxygen concentration detector with heater |
| US06/604,973 US4578174A (en) | 1983-05-09 | 1984-04-27 | Oxygen sensor with heater |
| DE3416948A DE3416948C2 (en) | 1983-05-09 | 1984-05-08 | Oxygen sensor with heating device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6866683U JPS59175169U (en) | 1983-05-09 | 1983-05-09 | Oxygen concentration detector with heater |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59175169U JPS59175169U (en) | 1984-11-22 |
| JPH0245808Y2 true JPH0245808Y2 (en) | 1990-12-04 |
Family
ID=30198836
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6866683U Granted JPS59175169U (en) | 1983-05-09 | 1983-05-09 | Oxygen concentration detector with heater |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59175169U (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS502992A (en) * | 1973-05-09 | 1975-01-13 |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH019001Y2 (en) * | 1981-05-11 | 1989-03-10 |
-
1983
- 1983-05-09 JP JP6866683U patent/JPS59175169U/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS502992A (en) * | 1973-05-09 | 1975-01-13 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59175169U (en) | 1984-11-22 |
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