JP2004125702A

JP2004125702A - Gas sensor

Info

Publication number: JP2004125702A
Application number: JP2002292667A
Authority: JP
Inventors: Takashi Shichida; 七田　貴史; ▲吉▼川　孝哉; Takaya Yoshikawa; Takashi Nakajima; 中島　崇史; Satoshi Ishikawa; 石川　聡; Masaya Ito; 伊藤　正也
Original assignee: NGK Spark Plug Co Ltd
Current assignee: Niterra Co Ltd
Priority date: 2002-10-04
Filing date: 2002-10-04
Publication date: 2004-04-22
Anticipated expiration: 2022-10-04
Also published as: JP3978384B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas sensor capable of protecting gas detection element from moisture and properly placing measured gas in the surrounding area of the gas detection element. <P>SOLUTION: In the gas sensor 1, a protector 4 surrounding a gas detection element 2 is provided with an inner cylinder part 101, an outside cylinder part 102 arranged coaxially at the side wall of the inner cylinder part 101 via an air gap, and a bottom cylinder part 103 arranged at the end in the axial direction of the inner cylinder part 101 and the outside cylinder part 102. The inner cylinder part 101 has an inner side wall 5 and an inner bottom wall 10 connected to the inner side wall 5. The bottom cylinder part 103 has a cylindrical bottom side wall 12 projected from the inner cylinder part 101 and the outer cylinder part 102 to the tip of the protector 4, and a bottom side wall 13. Guiding ports 7 and 8 guiding the measured gas to the inner side wall 5 and an outer side wall 6 are formed. A first discharge port discharging the measured gas is formed on an inner bottom wall 14. A second discharge port 15 discharging the measured gas is formed on a bottom side wall 12. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、酸素センサ、ＮＯ_Ｘセンサ等、被測定ガスに曝した状態で用いられ、内部に収納しているガス検出素子を被測定ガスに含まれている水分などから保護するプロテクタを備えたガスセンサに関する。
【０００２】
【従来の技術】
従来より、自動車のエンジンなどの内燃機関に取り付けられ、排気ガス（被測定ガス）中の特定ガス成分を検出するガスセンサが開発されている。そして、その中の一つとして、例えばジルコニアなどの固体電解質からなるガス検出素子を用い、酸素濃度を検出するガスセンサ（酸素センサ）や酸化窒素ガス濃度を検出するＮＯ_Ｘセンサなどが知られている。
【０００３】
一般的に、この形態のガスセンサは、ガス検出素子に形成されたガス接触部を排気ガスに曝した構造をしており、ヒータを用いてガス検出素子を高温（約３００℃）に加熱して活性化し、排気ガス中の酸素濃度を検出している。
ところで、ガス検出素子は熱衝撃に対して脆いので、高温に加熱された状態のガス検出素子に排気ガス中の水分が付着すると、クラックが発生するなどして破損する虞がある。
【０００４】
このため、ガスセンサにはガス検出素子のガス接触部を覆うプロテクタが装着され、ガス検出素子に水滴が付着しないように保護されている。
そして、このプロテクタは、側面や底面に被測定ガスの導入口と排出口を備え、被測定ガスをプロテクタの導入口から導入してガス検出素子部に導き、ガス検出素子部においてガス成分が測定された後は、排出口より排出するというような被測定ガスの導入と排出を行う。
【０００５】
ところで、前記ガスセンサは、被測定ガスの流れる方向に対してガスセンサの中心軸が必ずしも一定の向きに設置されるものではなく、排気管の形状や排気管周辺の構造に制約を受けてガスセンサの中心軸を傾斜して取り付けることがある。
【０００６】
そのため、被測定ガスの流れる方向に対してガスセンサのセンサ中心軸を傾斜して取り付けても、ガス検出素子を水分の付着から保護でき、且つ、プロテクタ内への被測定ガスの導入と排出口からの被測定ガスの排出を損なうことが無く、被測定ガスのガス成分を検出する応答性と検出精度が優れたガスセンサが求められている。
【０００７】
ガス検出素子を保護、被測定ガス中に含有される水分の除去、被測定ガスの導入と排出等を効果的に行うために、プロテクタを内側筒状部と外側筒状部とからなる二重構造にしたガスセンサがある。
従来のプロテクタが二重構造を有するガスセンサは、内側筒状部の側壁と外側筒状部の側壁が空隙を介し同軸状に配置され、これらの側壁には、被測定ガスの導入口（第一側ガス入口と第二側ガス入口）が形成されている。また、外側筒状部の導入口に、内側筒状部の側壁外面を取り囲む旋回流を発生させるためのガイド体を配置している。これによって、外側筒状部の導入口から導入した被測定ガスは、ガイド体の旋回流を生じさせる機能により、相対的に重い水滴と相対的に軽いガス成分とに分離されることになり、そして、水分が除去された被測定ガスを内側筒状部の導入口から内側筒状部内に流入させてガス検出素子に接触させることにより、被測定ガス中の特定ガス成分を検出する。その後、被測定ガスを内側筒状部の底壁に設けた排出口（第一側ガス出口）を通過させ、外側筒状部の底壁に設けた排出口（第二側ガス出口）から排出させている。（例えば、特許文献１参照）
また、プロテクタが二重構造を有するガスセンサとして、内側筒状部の側壁と外側筒状部の側壁が空隙を介し同軸状に配置され、内側筒状部の先端が外側筒状部より軸方向に突き出して構成されているものもある。そして、内側筒状部の側壁、外側筒状部の側壁、内側筒状部の底壁等には、被測定ガスの流入兼排出開口が複数形成されている。これによって、被測定ガスを流入兼排出開口からプロテクタ内に導入し、プロテクタ内でガス成分を検出した被測定ガスを流入兼排出開口からプロテクタ外へ排出させている。（例えば、特許文献２参照）
ところで、前記ガスセンサは、被測定ガスの流れる方向に対してガスセンサの中心軸が必ずしも一定の向きに設置されるものではなく、排気管の形状や排気管周辺の構造に制約を受けてガスセンサの中心軸を傾斜して取り付けることがある。
【０００８】
そのため、被測定ガスの流れる方向に対してガスセンサのセンサ中心軸を傾斜して取り付けても、ガス検出素子を水分の付着から保護でき、プロテクタ内への被測定ガスの導入と排出口からの被測定ガスの排出を損なうことが無く、被測定ガスのガス成分を検出する応答性と検出精度が優れたガスセンサが求められている。
【０００９】
【特許文献１】
特開２００１−０９９８０７号公報（第４−９頁、第１図、第３図）
【特許文献２】
特表２０００−５１１６４５号公報（第５−６頁、第１図）
【００１０】
【発明が解決しようとする課題】
しかしながら、特許文献１に開示されたガスセンサによれば、内側筒状部に形成された被測定ガスの排出口が外側筒状部の内部に構成され、内側筒状部の底面に設けた排出口から被測定ガスの導入口まで空隙があるので、プロテクタ内の被測定ガスの置換が不十分となり、被測定ガスのガス成分を検出する応答性を損なう場合があるという問題があった。
【００１１】
つまり、外側筒状部の導入口から導入した被測定ガスの一部が、内側筒状部の導入口に入らず外側筒状部の側壁と内側筒状部の側壁との空隙を経由して外側筒状部の排出口から排出されたり、ガス成分が検出され内部筒状部の排出口から排出された被測定ガスが、内側筒状部の側壁と外側筒状部の側壁との空隙を還流して再び内側筒状部の導入口から内側筒状部の内部に流入されたりすることにより、プロテクタ内の被測定ガスの置換が不十分となることがある。
【００１２】
また、特許文献２に開示されているガスセンサによれば、プロテクタの底面に被測定ガスの流入兼排出口を備え、このプロテクタ底面を介したプロテクタの内方にガス検出素子を配設しているので、プロテクタ底面の流入兼排出口から水滴や水分を含有した被測定ガスが流入し易く、ガス検出素子に水滴や水分が付着し、クラックが発生するなどして破損する虞があるという問題があった。
【００１３】
さらに、プロテクタの流入兼排出口を付設した底面が被測定ガス流れ方向に対向するようにセンサ中心軸が傾斜すると、流入兼排出口から水滴や水分を含有したガスが流入し易いという問題があった。
本発明は、こうした問題に鑑みなされたものであり、被測定ガスの流れる方向に対してガスセンサのセンサ中心軸を傾斜して取り付けても、水分や水滴を含んだ被測定ガスがプロテクタ内部に流入することが無く、ガス検出素子を水分の付着から保護でき、プロテクタ内の被測定ガスの導入と排出を損なうことが無く、被測定ガスの置換を良好に行うことができ、被測定ガスのガス成分を検出する応答性と検出精度が優れたガスセンサを提供することを目的とする。
【００１４】
【課題を解決するための手段及び発明の効果】
かかる目的を達成するためになされた請求項１に記載の発明は、軸方向に延びると共に、先端部に被測定ガスに接触させるガス接触部を有するガス検出素子と、
前記ガス接触部を先端から突き出させた状態で前記ガス検出素子の径方向周囲を取り囲むケースと、前記ガス検出素子の前記ガス接触部を覆うように、前記ケースに固定させた有底筒状のプロテクタとを備えたガスセンサであって、前記プロテクタに、内側筒状部と、この内側筒状部の側壁に空隙を介し同軸状に配置した外側筒状部と、前記内側筒状部及び前記外側筒状部から軸方向の先端側に配置した底側筒状部とを備え、前記内側筒状部は、筒状の内側側壁と、当該内側側壁に連結した内側底壁を備え、前記外側筒状部は、筒状の外側側壁と、この外側側壁から前記内側側壁に向かって折曲し内側底壁と又は内側底壁に近接した外側底壁を備え、前記底側筒状部は、前記内側底壁又は前記外側底壁から前記プロテクタの先端に向かう軸方向に突き出した筒状の底側側壁と、この底側側壁の先端部に連結した底側底壁とを備え、前記外側側壁に、被測定ガスを前記外側筒状部に導入するために、複数の外壁ガス導入口を形成し、前記内側側壁に、被測定ガスを前記内側筒状部に導入するために、複数の内壁ガス導入口を形成し、前記内側底壁に、被測定ガスを前記内側筒状部から前記底側筒状部へ排出するために第１の排出口を形成し、前記底側底壁に、被測定ガスを前記底側筒状室からプロテクタ外方へ排出するために第２の排出口を形成したことを特徴とする。
【００１５】
請求項１に記載のガスセンサによれば、被測定ガスの流れる方向に対してガスセンサ中心軸を傾斜して取り付けても、ガス検出素子を水分の付着から保護でき、プロテクタ内の被測定ガスの置換を良好に行うことができ、被測定ガスのガス成分を検出する応答性と検出精度が優れたガスセンサを得ることができる。
【００１６】
つまり、本ガスセンサは、被測定ガスの第１の排出口を備えた内側底壁と、被測定ガスの第２の排出口を備えた底側底壁とを形成し、第２の排出口から流入する被測定ガスが直接ガス検出素子に接触することがないように、内側底壁によって仕切る構成としたので、被測定ガスが第２の排出口から底側筒状部内に流入することがあっても、内側筒状部内への流入を低減できる。また、第２の排出口から流入したガスを内側底壁に当接させることにより、被測定ガス中に含有されている水分を凝縮して分離させ、この被測定ガスが第１排出口から内側筒状部に流入することがあっても、ガス検出素子への水分の付着を低減できる。
【００１７】
次に、請求項２に記載の発明は、請求項１に記載のガスセンサにおいて、前記プロテクタは、前記外側底壁を前記内側底壁の縁端部又は前記内側側壁と連結するとともに、この連結部から前記外側側壁を軸方向の先端に向かって折曲して突き出し、この突き出し部を前記底側側壁としたことを特徴とする。
【００１８】
請求項２に記載のガスセンサによれば、外側底壁を折曲して底側側壁を形成したので、底側側壁を形成するための新たな部品や接合加工工程が不要となり、生産性を向上できる。
次に、請求項３に記載の発明は、請求項１又は請求項２に記載のガスセンサにおいて、前記プロテクタは、前記外側底壁に前記内側側壁が挿通する挿通孔を形成し、この挿通孔より先端側に前記内側側壁を突き出し、この突き出し部を前記底側側壁とし、前記内側底壁を前記底側底壁と空隙を介して対向するように内側側壁内に仕切り板を係合して形成したことを特徴とする。
【００１９】
請求項３に記載のガスセンサによれば、外側底壁の挿通孔に内側側壁を挿通させて突き出し、この突き出し部を底側側壁としたので、底側側壁を形成するための新たな部品や接合加工工程が不要となり、生産性を向上できる。また、内側底壁を、底側底壁と空隙を介して対向するように内側側壁内に仕切り板を係合して形成したので、被測定ガスが第２の排出口から底側筒状部内に流入することがあっても、このガスを仕切り板に当接させ、内側筒状部内への流入を低減できる。また、第２の排出口から流入した被測定ガスを仕切り板に当接させることにより、ガス中に含有されている水分を凝縮して分離させ、この被測定ガスが第１排出口から内側筒状室に流入することがあっても、ガス検出素子への水分の付着を低減できる。
【００２０】
次に、請求項４に記載の発明は、請求項１乃至請求項３の何れか記載のガスセンサにおいて、前記プロテクタは、前記第１排出口と前記第２排出口を、ガスセンサの軸方向で重なり合うことのない位置に配設したことを特徴とする。
請求項４に記載のガスセンサによれば、前記第１の排出口と前記第２の排出口を、軸方向で重なり合うことのない位置にずらして形成したので、第２の排出口から流入した被測定ガスが内側底壁に当接し易く、この被測定ガスの内側筒状部へ流入を防止する効果をより向上できる。また、第２の排出口から流入した被測定ガスが内側底壁に当接し易くなるので、この被測定ガス中に含有している水分を凝縮して分離させる効果が向上し、僅かに被測定ガスが第１排出口から内側筒状部内に流入することがあっても、ガス検出素子に水分が付着することなく、ガス検出素子をより確実に保護できる。
【００２１】
次に、請求項５に記載の発明は、請求項１乃至請求項４の何れか記載のガスセンサにおいて、前記底側筒状部は、前記底側側壁を前記底側底壁に向かって縮径するようにテーパを付けて形成したことを特徴とする。
請求項５に記載のガスセンサによれば、底側側壁を底側底壁に向かって縮径するテーパを付けて形成したので、底側側壁の外周囲を流れる被測定ガスがこのテーパに当接することにより、テーパに沿って底側底壁に向かって流れる。そして、このテーパに沿って被測定ガスの流れが発生することにより、底側底壁に対向するように流れている被測定ガスの向きを回避できるので、被測定ガスが第２の排出口から流入することを抑制できる。また、テーパに沿って流れる被測定ガスによって底側底壁の近傍に負圧が生じるので、この底側側壁に形成した第２の排出口から被測定ガスを速やかに排出でき、プロテクタ内における被測定ガスの置換をより良好にし、被測定ガス中の特定ガス成分を検出する応答速度と検出精度をより向上できる。
【００２２】
次に、請求項６に記載の発明は、請求項１乃至請求項５の何れか記載のガスセンサにおいて、前記底側筒状部は、前記外壁ガス導入口に内側に向けて延出するガイド体を付設したことを特徴とする。
請求項６に記載のガスセンサによれば、外壁ガス導入口に、内側に向けて延出するガイド体を付設したので、外壁ガス導入口から導入した被測定ガス中の水分を凝縮して除去し、比重が軽くなった被測定ガスを内壁ガス導入口に向かって流して、速やかに、内側筒状部内に導入できる。
【００２３】
つまり、このガイド体は、被測定ガスを内側筒状部の外周面を取り囲む状態で旋回流を生じさせる機能を有し、この旋回流に伴い発生する慣性力により、相対的に重い水滴は相対的に軽いガス成分と分離されて、分離された水滴は外側筒状部の内周面に押し付けられる。これにより、被測定ガス中に水滴が含まれる場合にも、その水滴は内側筒状部の内側に侵入しにくく、ガス検出素子を保護する機能が向上する。
【００２４】
【発明の実施の形態】
以下、本発明の実施の形態を図面と共に説明する。
図１は本発明が適用された本発明が適用されたガスセンサの構成を表す断面図、図２は本実施形態のプロテクタの形状を表す断面図と図中のＢ−Ｂ断面図である。
【００２５】
図１、図２において、１はガスセンサであり、このガスセンサ１には、被測定ガスに接触させるガス接触部を有するガス検出素子２と、ガス検出素子２を突き出させた状態で把持するケース３と、ガス検出素子２の周囲を覆うように、ケース２に固定された有底筒状のプロテクタ４とが備えられている。
【００２６】
そして、ガス検出素子２は、ケース３の先端側より配置されるセラミックホルダー６２、タルク粉末６３、セラミックスリーブ６４を介してケース３に固定されている。また、ケース３の後端側外周には、外筒６５が溶接等により固定されている。また、外筒６５の後端側の内側には、ガス検出素子２との電気的接続を、リードフレーム６１を介して外部と行うためのリード線６６が挿通されるセラミックセパレータ６７とグロメット６９とが配置されている。なお、セラミックセパレータ６７は、軸線方向の略中央の外周面に外向きに突出するフランジ部６８が形成され、このフランジ部６８が外筒６５において内向きに突出する形態で形成された外側支持部７０により支持されている。また、グロメット６９は、外筒６５の内側に弾性的に嵌入されている。
【００２７】
プロテクタ４は、内側筒状部１０１と、内側筒状部１０１の側壁に空隙を介し同軸状に配置した外側筒状部１０２と、内側筒状部１０１及び外側筒状部１０２から軸方向の先端側に配置した底側筒状部１０３とを備えている。
外側筒状部１０２は、筒状の外側側壁６と、この外側側壁６から後述の内側側壁５に向かって折曲し内側底壁５及び後述の内側底壁１０に連結した外側底壁６を備えている。そして、この連結部から外側底壁６を軸方向の先端に向かって折曲して突き出し、この突き出し部を後述の底側側壁１２として一体に形成している。
【００２８】
そして、外側筒状部１０２の外側側壁６には、被測定ガスを外側筒状部１０２内に導入するために、内側に向けて延出するガイド体９を付設した外壁ガス導入口８が、円周における４５°間隔で複数形成されている（図２（ｂ）参照）。このガイド体９は、図２に示すごとく、外側側壁１２を、コ字状に切り欠いて、その切り欠け片を外側側壁６の外周の接線に対し、内側に向けて略４５度曲げ加工することにより形成されている。そして、このガイド体９は、被測定ガスを内側側壁６の外周面を取り囲む状態で旋回流を生じさせる機能を有し、この旋回流に伴い発生する慣性力により、相対的に重い水滴と相対的に軽いガス成分とが分離されることになる。そして、外側筒状部１０２の底壁１１には、外側筒状室１０２に溜まった水滴を排出するために水抜き孔１６が複数形成されている。
【００２９】
内側筒状部１０１には、被測定ガスをガス検出素子２の周囲に導入するために、内側側壁５に内壁ガス導入口７が、外壁ガス導入口８よりもケース３に近傍する位置に、ガス検出素子２に対向するように形成されている。この内壁ガス導入口７は、外壁ガス導入口８に対して、円周方向において２２．５°ずらして配置され、円周における４５°間隔で複数形成されている。外壁ガス導入口８に対向する位置における内側側壁５の外周面は、外側側壁６の外周面と平行に形成されている。
【００３０】
また、内側筒状部１０１の内側底壁１０に、被測定ガスを内側筒状部１０１から底側筒状部１０３へ排出するために第１の排出口１４が複数形成されている。この第１の排出口１４は、後述の底側底壁１３に形成した第２の排出口１５とガスセンサ１の軸方向で重なり合うことのないように、第２の排出口１５の外側に形成されている。この内側底壁１０を、内側筒状部１０１と底側筒状部１０３とを仕切るように構成することで、後述の第２排出口１５から浸入した被測定ガスが、内側筒状部１０１内に浸入することのないように抑制できる。
【００３１】
底側筒状部１０２は、前述したように外側底壁６と一体に形成された底側側壁１２と、底側側壁の先端部に連結された底側底壁１３とから形成されている。
底側側壁１１は、底側底壁１３に向かって縮径するようにテーパを付けて形成し、底側側壁１２には、被測定ガスをプロテクタ４の外方に排出するための第２排出口１５が、第１排出口１４とガスセンサ１の軸方向で重なり合うことのないように形成されている。
【００３２】
以下に、前記の構成を有する実施形態のガスセンサの作用効果を記載する。
本実施の形態のガスセンサは、内側筒状部１０１及び外側筒状部１０２から軸方向の先端側に配置した底側筒状部１０３とを備え、内側筒状部１０１の内側底壁１０に第１の排出口１４を形成し、底側筒状部１０３の底側底壁１３に第２の排出口１５を形成したので、被測定ガスが第２の排出口１５から底側筒状部１０３内に流入することがあっても、内側筒状部１０１への流入を低減でき、内側筒状部１０１内に収納されているガス検出素子に水分が接触しないようにより確実に保護できる。
【００３３】
また、第２の排出口１５から流入した被測定ガスが内側底壁１０に当接すると被測定ガス中に含有されている水分が凝縮して分離するので、この被測定ガスが第１排出口１４から内側筒状室１０１内に流入することがあっても、ガス検出素子２に水分が付着することなく、ガス検出素子を保護できる。
【００３４】
また、外側筒状部１０２の底側底面１１に少なくとも一つ以上の水抜き孔１６を形成したので、被測定ガスが外側筒状部１０２内の周壁に接触して発生した凝縮水を、水抜き孔１６を経由してプロテクタ４の外部に除去でき、外側筒状部１０２内に水滴が溜まることなく、内側筒状室１０１内への水滴の浸入を防止できる。
【００３５】
また、底側筒状部１０３の底側側壁１２を底側底壁１３に向かって縮径するようにテーパを付けて形成したので、水滴を含んだ被測定ガスが第２の排出口１５から流入することが無いように防止でき、被測定ガスを底側底壁１３に形成した第２の排出口１５から速やかに排出でき、プロテクタ４内における被測定ガスの置換を良好にし、被測定ガス中のガス成分を検出する応答速度と検出精度を向上できる。
【００３６】
また、外壁ガス導入口８には、内側に向けて延出するガイド体９を付設したので、外壁ガス導入口８から導入した被測定ガスを確実に内側筒状部１０１の内側側壁５の外周面に接触させ、被測定ガス中の水分を凝縮して除去することができる。そして、この被測定ガスは、水分を除去して比重が軽くなっているので、速やかに、内側筒状室１０１内に導入できる。
【００３７】
次に、図３を用いて本発明のガスセンサの、種々の態様を説明する。図３は、プロテクタの詳細形状を断面図で表している。
尚、図３に表した種々の態様のガスセンサは、基本的に上記実施の形態で表したガスセンサ１と同じ構成なので共通と成る構成部分には同一符号を付し、詳細な説明は省略し、特徴と成る部分について説明する。
【００３８】
図３の（ａ）に表したプロテクタ３０は、筒状の外側側壁３６と、この外側側壁３６から内側側壁３５に向かって折曲し内側側壁３５が挿通する挿通孔を形成した外側底壁１１を備え、この挿通孔より先端側に内側側壁３５を突き出し、この突き出し部を底側側壁３２とし、底側側壁３２の先端部に第２の排出口を付設した底側底壁４３を連結し、内側筒状部側壁３５内に第１の排出口３４を形成した仕切り板１７を係合し、この仕切り板１７を内側筒状部１０１の内側底壁とした構成を有する。
【００３９】
（ａ）に表したプロテクタ３０によれば、外側底壁１１の挿通孔より先端側に突き出した内側側壁３５を底側側壁３２としたので、底側側壁３２を形成するために新たな部品や接合加工工程が不要となり、生産性を向上できる。そして、内側筒状部１０１内に水分が浸入しないように、仕切り板１７によって、防止することができる。
【００４０】
次に、図３の（ｂ）に表したプロテクタ４０は、内側筒状部１０１に筒状の内側側壁４５と、第１の排出口１４を付設した内側底壁１０とを備え、外側筒状部１０２に、筒状の外側側壁４６と、この外側側壁４６から内側側壁３６に向かって折曲した外側底壁１１を備え、外側底壁１１の端部を折曲して底側筒状部１０３底壁４３に向かう軸方向に突き出し、この突き出し部を底側筒状部１０３の底側側壁４２とした構成を有する。また、内側底壁１０と外側底底壁１１との間に第１の排出口１４と重なる貫通孔２１を形成した連結板４８を重ねた構成を有する。
【００４１】
（ｂ）に表したプロテクタ４０によれば、外側筒状部１０２の外側底壁１１の端部を折曲して底側筒状部１０３の底側側壁４２を形成したので、底側側壁４２を形成するために新たな部品や接合加工工程が不要となり、生産性を向上できる。また、底側底壁１１と内側底壁１０との間に連結板４８を重ねたので、第２排出口から水分を含んだ非測定ガスが流入しても、内側筒状部１０１に浸入することがないようにより確実に防止できる。
【００４２】
次に図３の（ｃ）に表したプロテクタ５０は、内側筒状部１０１に筒状の内側側壁５５と、第１の排出口１４を付設した内側底壁１０とを備え、外側筒状部１０２に、筒状の外側側壁５６と、この外側側壁４６から内側に向かって折曲し貫通孔２１を付設した外側底壁５４とを備え、貫通孔２１が内側筒状部１０１の内側底壁１０に形成した第１の排出口１４と重なるように、内側底壁１０と外側底壁５４とを重ねた構成を有する。また、外側筒状部１０３は、底側側壁５２と第２の排出口５１を付設した底側底壁５７とを連結して形成し、底側側壁５２の縁端部を外側筒外側底壁１０に沿って折曲して密着した構成を有する。
【００４３】
（ｃ）に表したプロテクタ５０によれば、内側底壁１０と外側底壁５４とを重ねたので、第２排出口５１から水分を含んだ非測定ガスが流入しても、内側筒状部１０１に浸入することがないようにより確実にできる。
尚、本発明の実施の形態によれば、不要なガスが第２の排出口１５から内側筒状部１０１内へ流入することがないように、プロテクタ４に底側筒状部１０３を設け、底側底壁１１と内側底壁１０とからなる二重構造としたが、さらに、内側側壁５内に仕切り板を嵌合させて、三重構造等の多重構造にしてもよい。
【００４４】
また、本発明の実施の形態によれば、外側筒状部１０２の外側側壁６に、外壁ガス導入口８を４５度間隔で均等に形成し、ガイド体９を外壁ガス導入口８の端部から外側側壁６の外周接線方向に対して４５°に曲げて付設したが、このガイド体９の曲げ角度は４５°に限定されるものではなく、ガスセンサの用途や形状、取り付け構造等に応じて曲げ角度を求めても良い。
【００４５】
また、本発明の実施の形態によれば、第１の排出口１４や第２の排出口１５の形状は、内側底壁１０、底側底壁１３の厚み分の孔形状としたが、さらにこの孔をバーリング加工などして外側に突き出すようにしても良い。
【図面の簡単な説明】
【図１】本発明が適用された実施の形態１の、ガスセンサの構成を表す断面図である。
【図２】同実施形態のプロテクタの、詳細形状を表す断面図である。
【図３】本発明が適用された変形例の、プロテクタの形状を表す断面図である。
【符号の説明】
１…ガスセンサ、２…ガス検出素子、３…ケース、４，３０，４０，５０…プロテクタ、５，３５，４５，５５…内側側壁、６，３６，４６，５６…外側側壁、７…内壁ガス導入口、８…外壁ガス導入口、９…ガイド体、１０…内側底壁、１１，５４…外側底壁、１２，３２，４３，５２…底側側壁、１３，３３，４３，５３…底側底壁、１４，３４……第１の排出口、１５，５１…第２の排出口、１６…水抜き孔、１７…仕切り板（内側底壁）、２１…貫通孔、４７…連結板、６１…リードフレーム、６２…セラミックホルダー、６３…タルク粉末、６４…セラミックスリーブ、６５…外筒、６６…リード線、６７…セラミックセパレータ、６８…フランジ部、６９…グロメット、７０…外側支持部１０１…内側筒状部、１０２…外側筒状部、１０３…底側筒状部。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an oxygen sensor, NO _X The present invention relates to a gas sensor having a protector, such as a sensor, which is used in a state exposed to a gas to be measured and protects a gas detection element housed therein from moisture contained in the gas to be measured.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a gas sensor that is attached to an internal combustion engine such as an automobile engine and detects a specific gas component in exhaust gas (gas to be measured) has been developed. As one of them, a gas sensor (oxygen sensor) for detecting an oxygen concentration or a NO for detecting a nitrogen oxide gas concentration using a gas detecting element made of a solid electrolyte such as zirconia is used. _X Sensors and the like are known.
[0003]
Generally, this type of gas sensor has a structure in which a gas contact portion formed on a gas detection element is exposed to exhaust gas, and the gas detection element is heated to a high temperature (about 300 ° C.) using a heater. It is activated and detects the oxygen concentration in the exhaust gas.
By the way, since the gas detection element is brittle against thermal shock, if moisture in the exhaust gas adheres to the gas detection element heated to a high temperature, there is a possibility that the gas detection element may be broken due to cracks or the like.
[0004]
For this reason, the gas sensor is equipped with a protector that covers the gas contact portion of the gas detection element, and is protected so that water droplets do not adhere to the gas detection element.
This protector has an inlet and an outlet for the gas to be measured on the side and bottom surfaces. The gas to be measured is introduced from the inlet of the protector and guided to the gas detection element, where the gas components are measured. After that, the gas to be measured is introduced and discharged such as discharged from the discharge port.
[0005]
By the way, the gas sensor is not necessarily installed such that the central axis of the gas sensor is always fixed to the direction in which the gas to be measured flows, and the center of the gas sensor is restricted by the shape of the exhaust pipe and the structure around the exhaust pipe. The shaft may be installed at an angle.
[0006]
Therefore, even if the sensor central axis of the gas sensor is attached at an angle to the direction in which the gas to be measured flows, the gas detection element can be protected from the adhesion of moisture, and the gas to be measured is introduced into the protector and discharged from the outlet. There is a demand for a gas sensor which does not impair the discharge of the gas to be measured and which has excellent responsiveness and detection accuracy for detecting the gas component of the gas to be measured.
[0007]
In order to protect the gas detection element, remove moisture contained in the gas to be measured, and effectively introduce and discharge the gas to be measured, the protector is composed of an inner cylindrical portion and an outer cylindrical portion. There is a gas sensor with a structure.
In a gas sensor in which a conventional protector has a dual structure, a side wall of an inner cylindrical portion and a side wall of an outer cylindrical portion are coaxially arranged with a gap therebetween. Side gas inlet and a second side gas inlet). In addition, a guide body for generating a swirling flow surrounding the outer surface of the side wall of the inner cylindrical portion is disposed at the inlet of the outer cylindrical portion. Thereby, the gas to be measured introduced from the introduction port of the outer cylindrical portion is separated into a relatively heavy water droplet and a relatively light gas component by a function of generating a swirling flow of the guide body, Then, the specific gas component in the measured gas is detected by flowing the measured gas from which moisture has been removed into the inner cylindrical portion through the inlet of the inner cylindrical portion and contacting the gas detection element. Thereafter, the gas to be measured is passed through a discharge port (first gas outlet) provided on the bottom wall of the inner tubular portion, and discharged from a discharge port (second gas outlet) provided on the bottom wall of the outer tubular portion. Let me. (For example, see Patent Document 1)
Further, as a gas sensor in which the protector has a double structure, the side wall of the inner cylindrical portion and the side wall of the outer cylindrical portion are coaxially arranged via a gap, and the tip of the inner cylindrical portion is more axially than the outer cylindrical portion. Some are protruding and configured. A plurality of inflow / outflow openings for the gas to be measured are formed on the side wall of the inner cylindrical portion, the side wall of the outer cylindrical portion, the bottom wall of the inner cylindrical portion, and the like. As a result, the gas to be measured is introduced into the protector from the inlet / discharge opening, and the gas to be measured whose gas component is detected in the protector is discharged from the inlet / discharge opening to the outside of the protector. (For example, see Patent Document 2)
By the way, the gas sensor is not necessarily installed such that the central axis of the gas sensor is always fixed to the direction in which the gas to be measured flows, and the center of the gas sensor is restricted by the shape of the exhaust pipe and the structure around the exhaust pipe. The shaft may be installed at an angle.
[0008]
Therefore, even if the sensor central axis of the gas sensor is mounted at an angle with respect to the direction in which the gas to be measured flows, the gas detection element can be protected from the adhesion of moisture, and the gas to be measured is introduced into the protector and the gas from the exhaust port. There is a need for a gas sensor that does not impair the discharge of the measurement gas and has excellent responsiveness and detection accuracy for detecting the gas component of the gas to be measured.
[0009]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2001-099807 (page 4-9, FIG. 1, FIG. 3)
[Patent Document 2]
Japanese Patent Publication No. 2000-511645 (Pages 5-6, FIG. 1)
[0010]
[Problems to be solved by the invention]
However, according to the gas sensor disclosed in Patent Literature 1, the outlet for the gas to be measured formed in the inner cylindrical portion is formed inside the outer cylindrical portion, and the outlet provided on the bottom surface of the inner cylindrical portion. Since there is a gap from the sample gas to the introduction port of the gas to be measured, the gas to be measured in the protector is insufficiently replaced, and there is a problem that the responsiveness of detecting the gas component of the gas to be measured may be impaired.
[0011]
In other words, a part of the gas to be measured introduced from the inlet of the outer tubular portion does not enter the inlet of the inner tubular portion, but passes through the gap between the sidewall of the outer tubular portion and the sidewall of the inner tubular portion. The gas to be measured discharged from the outlet of the outer cylindrical portion, or the gas component is detected and discharged from the outlet of the inner cylindrical portion, forms a gap between the side wall of the inner cylindrical portion and the side wall of the outer cylindrical portion. The gas to be measured in the protector may be insufficiently replaced due to the reflux and the flow into the inside of the inner tubular portion again from the inlet of the inner tubular portion.
[0012]
Further, according to the gas sensor disclosed in Patent Document 2, the gas inlet / outlet for the gas to be measured is provided on the bottom surface of the protector, and the gas detection element is provided inside the protector via the bottom surface of the protector. Therefore, the gas to be measured containing water droplets and water easily flows in from the inlet / outlet on the bottom surface of the protector, and the water droplets and water adhere to the gas detection element, which may cause cracks and other damages. there were.
[0013]
Further, if the sensor central axis is inclined such that the bottom surface provided with the inlet / outlet of the protector faces the flow direction of the gas to be measured, there is a problem that gas containing water droplets and moisture easily flows in from the inlet / outlet. Was.
The present invention has been made in view of such a problem, and even when the sensor central axis of the gas sensor is attached to be inclined with respect to the flowing direction of the gas to be measured, the gas to be measured including moisture and water droplets flows into the inside of the protector. The gas detection element can be protected from the adhesion of moisture, without impairing the introduction and discharge of the gas to be measured in the protector. It is an object of the present invention to provide a gas sensor having excellent response and detection accuracy for detecting components.
[0014]
Means for Solving the Problems and Effects of the Invention
The invention according to claim 1, which has been made to achieve such an object, has a gas detection element that extends in the axial direction and has a gas contact portion that is in contact with a gas to be measured at a distal end portion,
A case surrounding the radial periphery of the gas detection element with the gas contact portion protruding from the tip, and a bottomed cylindrical shape fixed to the case so as to cover the gas contact portion of the gas detection element. A gas sensor provided with a protector, wherein the protector has an inner tubular portion, an outer tubular portion disposed coaxially through a gap in a side wall of the inner tubular portion, the inner tubular portion, and the outer tubular portion. A bottom-side tubular portion disposed axially distal from the tubular portion, wherein the inner tubular portion includes a tubular inner side wall, and an inner bottom wall connected to the inner side wall; The shape portion includes a cylindrical outer side wall, and an outer bottom wall that is bent from the outer side wall toward the inner side wall and is close to the inner bottom wall or the inner bottom wall. Axial direction from the inner bottom wall or the outer bottom wall to the tip of the protector A cylindrical bottom side wall protruding from the bottom side wall, and a bottom side bottom wall connected to a tip end of the bottom side wall, a plurality of the outer side walls are provided for introducing a gas to be measured into the outer cylindrical portion. Forming an outer wall gas inlet, and forming a plurality of inner wall gas inlets on the inner side wall to introduce the gas to be measured into the inner cylindrical portion, and forming the gas to be measured on the inner bottom wall. A first outlet is formed for discharging from the inner cylindrical portion to the bottom cylindrical portion, and a gas to be measured is discharged from the bottom cylindrical chamber to the outside of the protector on the bottom bottom wall. A second discharge port is formed.
[0015]
According to the gas sensor of the first aspect, the gas detection element can be protected from the adhesion of moisture even if the gas sensor central axis is attached to be inclined with respect to the direction in which the gas to be measured flows, and the gas to be measured in the protector is replaced. And a gas sensor having excellent responsiveness and detection accuracy for detecting a gas component of the gas to be measured can be obtained.
[0016]
That is, the present gas sensor forms an inner bottom wall provided with the first outlet of the gas to be measured and a bottom bottom wall provided with the second outlet of the gas to be measured. Since the gas to be measured is separated by the inner bottom wall so that the gas to be measured does not come into direct contact with the gas detection element, the gas to be measured may flow into the bottom-side cylindrical portion from the second discharge port. Even so, the inflow into the inner cylindrical portion can be reduced. Further, the gas contained in the gas to be measured is condensed and separated by bringing the gas flowing in from the second outlet into contact with the inner bottom wall. Even if the gas flows into the cylindrical portion, the adhesion of moisture to the gas detection element can be reduced.
[0017]
Next, according to a second aspect of the present invention, in the gas sensor according to the first aspect, the protector connects the outer bottom wall to an edge of the inner bottom wall or the inner side wall, and connects the outer bottom wall to the inner bottom wall. And the outer side wall is bent and protruded toward the tip in the axial direction, and the protruding portion is used as the bottom side wall.
[0018]
According to the gas sensor of the second aspect, since the bottom side wall is formed by bending the outer bottom wall, a new component for forming the bottom side wall and a joining process are not required, and the productivity is improved. it can.
Next, according to a third aspect of the present invention, in the gas sensor according to the first or second aspect, the protector forms an insertion hole through which the inner side wall passes through the outer bottom wall, and The inner side wall is protruded toward the distal end side, the protruding portion is used as the bottom side wall, and the inner bottom wall is formed by engaging a partition plate in the inner side wall so as to face the bottom side wall via a gap. It is characterized by having done.
[0019]
According to the gas sensor of the third aspect, since the inner side wall is inserted into the insertion hole of the outer bottom wall to protrude and the protruding portion is used as the bottom side wall, a new component or joining for forming the bottom side wall is performed. No processing step is required, and productivity can be improved. Further, since the inner bottom wall is formed by engaging the partition plate in the inner side wall so as to face the bottom side bottom wall with a gap therebetween, the gas to be measured flows from the second discharge port into the bottom side cylindrical portion. This gas is brought into contact with the partition plate even if it flows into the inner cylindrical portion, so that the flow into the inner cylindrical portion can be reduced. Further, by bringing the gas to be measured flowing from the second outlet into contact with the partition plate, water contained in the gas is condensed and separated, and the gas to be measured flows from the first outlet to the inner cylinder. Even if the gas flows into the gas chamber, adhesion of moisture to the gas detection element can be reduced.
[0020]
Next, according to a fourth aspect of the present invention, in the gas sensor according to any one of the first to third aspects, the protector overlaps the first outlet and the second outlet in an axial direction of the gas sensor. It is characterized by being arranged in a position where there is no problem.
According to the gas sensor of the fourth aspect, the first exhaust port and the second exhaust port are formed so as to be shifted from each other so as not to overlap in the axial direction. The measurement gas easily comes into contact with the inner bottom wall, and the effect of preventing the gas to be measured from flowing into the inner cylindrical portion can be further improved. Further, since the gas to be measured flowing from the second outlet is more likely to come into contact with the inner bottom wall, the effect of condensing and separating water contained in the gas to be measured is improved, and the Even if gas flows into the inner cylindrical portion from the first outlet, the gas detection element can be protected more reliably without moisture adhering to the gas detection element.
[0021]
Next, according to a fifth aspect of the present invention, in the gas sensor according to any one of the first to fourth aspects, the bottom cylindrical portion reduces the diameter of the bottom side wall toward the bottom bottom wall. It is characterized in that it is formed so as to be tapered.
According to the gas sensor of the fifth aspect, since the bottom side wall is formed to have a taper whose diameter is reduced toward the bottom side bottom wall, the gas to be measured flowing around the outer periphery of the bottom side wall comes into contact with the taper. Thereby, it flows toward the bottom bottom wall along the taper. Since the flow of the gas to be measured is generated along the taper, the direction of the gas to be measured flowing so as to face the bottom bottom wall can be avoided, so that the gas to be measured flows from the second outlet. Inflow can be suppressed. Further, since the gas to be measured flowing along the taper generates a negative pressure in the vicinity of the bottom bottom wall, the gas to be measured can be quickly discharged from the second discharge port formed in the bottom side wall, and the gas in the protector can be removed. The replacement of the measurement gas can be improved, and the response speed and detection accuracy for detecting the specific gas component in the measurement gas can be further improved.
[0022]
Next, according to a sixth aspect of the present invention, in the gas sensor according to any one of the first to fifth aspects, the bottom-side tubular portion extends inward to the outer wall gas inlet. Is provided.
According to the gas sensor of the sixth aspect, since the outer wall gas inlet is provided with a guide body extending inward, the moisture in the gas to be measured introduced from the outer wall gas inlet is condensed and removed. The gas to be measured whose specific gravity has been reduced can be flowed toward the gas inlet of the inner wall and quickly introduced into the inner cylindrical portion.
[0023]
That is, the guide body has a function of generating a swirling flow in a state surrounding the gas to be measured in the state of surrounding the outer peripheral surface of the inner cylindrical portion. The separated water droplets are separated from the light gas components and pressed against the inner peripheral surface of the outer cylindrical portion. Accordingly, even when a water drop is contained in the gas to be measured, the water drop is unlikely to enter the inside of the inner cylindrical portion, and the function of protecting the gas detection element is improved.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view illustrating a configuration of a gas sensor to which the present invention is applied, and FIG. 2 is a cross-sectional view illustrating a shape of the protector of the present embodiment and a BB cross-sectional view in the drawing.
[0025]
1 and 2, reference numeral 1 denotes a gas sensor. The gas sensor 1 includes a gas detection element 2 having a gas contact portion that comes into contact with a gas to be measured, and a case 3 that holds the gas detection element 2 in a protruded state. And a bottomed cylindrical protector 4 fixed to the case 2 so as to cover the periphery of the gas detection element 2.
[0026]
The gas detection element 2 is fixed to the case 3 via a ceramic holder 62, a talc powder 63, and a ceramic sleeve 64 arranged from the front end side of the case 3. An outer cylinder 65 is fixed to the outer periphery of the rear end side of the case 3 by welding or the like. A ceramic separator 67 and a grommet 69 into which a lead wire 66 for making an electrical connection with the gas detection element 2 to the outside via a lead frame 61 are inserted inside the rear end side of the outer cylinder 65. Is arranged. The ceramic separator 67 has an outwardly projecting flange portion 68 formed on an outer peripheral surface at a substantially central portion in the axial direction, and an outer support portion formed such that the flange portion 68 is formed to project inward in the outer cylinder 65. 70 supported. The grommet 69 is elastically fitted inside the outer cylinder 65.
[0027]
The protector 4 includes an inner tubular portion 101, an outer tubular portion 102 disposed coaxially on a side wall of the inner tubular portion 101 via a gap, and an axial tip from the inner tubular portion 101 and the outer tubular portion 102. And a bottom cylindrical portion 103 arranged on the side.
The outer cylindrical portion 102 includes a cylindrical outer side wall 6 and an outer bottom wall 6 that is bent from the outer side wall 6 toward an inner side wall 5 described later and connected to the inner bottom wall 5 and an inner bottom wall 10 described later. Have. Then, the outer bottom wall 6 is bent and protruded from the connecting portion toward the tip in the axial direction, and the protruding portion is integrally formed as a bottom side wall 12 described later.
[0028]
An outer wall gas inlet 8 provided with a guide body 9 extending inward to introduce the gas to be measured into the outer cylindrical portion 102 is provided on the outer side wall 6 of the outer cylindrical portion 102. A plurality is formed at 45 ° intervals on the circumference (see FIG. 2B). As shown in FIG. 2, the guide body 9 cuts the outer side wall 12 into a U-shape, and bends the notch piece toward the inside by approximately 45 degrees with respect to a tangent line on the outer periphery of the outer side wall 6. It is formed by this. The guide body 9 has a function of generating a swirling flow in a state where the gas to be measured surrounds the outer peripheral surface of the inner side wall 6. The lighter gas components are separated. A plurality of drain holes 16 are formed on the bottom wall 11 of the outer cylindrical portion 102 for discharging water droplets accumulated in the outer cylindrical chamber 102.
[0029]
In order to introduce the gas to be measured around the gas detection element 2, the inner cylindrical portion 101 has the inner wall gas inlet 7 on the inner side wall 5 at a position closer to the case 3 than the outer wall gas inlet 8. It is formed so as to face the gas detection element 2. The inner wall gas inlets 7 are arranged at a distance of 22.5 ° in the circumferential direction with respect to the outer wall gas inlets 8, and are formed in plural at 45 ° intervals on the circumference. The outer peripheral surface of the inner side wall 5 at a position facing the outer wall gas inlet 8 is formed parallel to the outer peripheral surface of the outer side wall 6.
[0030]
Further, a plurality of first outlets 14 are formed in the inner bottom wall 10 of the inner cylindrical portion 101 to discharge the gas to be measured from the inner cylindrical portion 101 to the bottom cylindrical portion 103. The first discharge port 14 is formed outside the second discharge port 15 so as not to overlap in the axial direction of the gas sensor 1 with a second discharge port 15 formed in the bottom wall 13 described later. ing. By configuring the inner bottom wall 10 so as to partition the inner cylindrical portion 101 and the bottom-side cylindrical portion 103, the gas to be measured entering from a second discharge port 15 described later can be disposed inside the inner cylindrical portion 101. Can be suppressed so as not to infiltrate the air.
[0031]
The bottom cylindrical portion 102 is formed from the bottom side wall 12 formed integrally with the outer bottom wall 6 and the bottom bottom wall 13 connected to the tip of the bottom side wall as described above.
The bottom side wall 11 is formed so as to be tapered so as to decrease in diameter toward the bottom side bottom wall 13, and the bottom side wall 12 is provided with a second discharge port for discharging the gas to be measured to the outside of the protector 4. The outlet 15 is formed so as not to overlap the first discharge port 14 in the axial direction of the gas sensor 1.
[0032]
The operation and effect of the gas sensor according to the embodiment having the above configuration will be described below.
The gas sensor according to the present embodiment includes an inner cylindrical portion 101 and a bottom cylindrical portion 103 disposed at a distal end side in the axial direction from the outer cylindrical portion 102. Since the first outlet 14 is formed and the second outlet 15 is formed in the bottom bottom wall 13 of the bottom cylindrical portion 103, the gas to be measured flows from the second outlet 15 to the bottom cylindrical portion 103. Even if the gas flows into the inner cylindrical portion 101, the flow into the inner cylindrical portion 101 can be reduced, and the gas detection element housed in the inner cylindrical portion 101 can be more reliably protected from contact with moisture.
[0033]
Further, when the gas to be measured flowing from the second outlet 15 comes into contact with the inner bottom wall 10, the water contained in the gas to be measured is condensed and separated. Even if the gas flows from the inside 14 into the inner cylindrical chamber 101, the gas detection element 2 can be protected without moisture adhering to the gas detection element 2.
[0034]
Further, since at least one or more water drain holes 16 are formed in the bottom side bottom surface 11 of the outer cylindrical portion 102, condensed water generated when the gas to be measured comes into contact with the peripheral wall inside the outer cylindrical portion 102 is removed by water. The water can be removed to the outside of the protector 4 through the hole 16, so that water droplets do not accumulate in the outer cylindrical portion 102, so that water droplets can be prevented from entering the inner cylindrical chamber 101.
[0035]
Further, since the bottom side wall 12 of the bottom cylindrical portion 103 is formed so as to be tapered so as to decrease in diameter toward the bottom bottom wall 13, the gas to be measured including water droplets flows from the second outlet 15. The gas to be measured can be prevented from flowing in, the gas to be measured can be quickly discharged from the second discharge port 15 formed in the bottom bottom wall 13, the replacement of the gas to be measured in the protector 4 is improved, and the gas to be measured is improved. It is possible to improve the response speed and detection accuracy for detecting gas components in the gas.
[0036]
In addition, since the outer wall gas inlet 8 is provided with the guide body 9 extending inward, the gas to be measured introduced from the outer wall gas inlet 8 is surely supplied to the outer periphery of the inner side wall 5 of the inner cylindrical portion 101. The moisture in the gas to be measured can be condensed and removed by contact with the surface. Since the specific gravity of the gas to be measured is reduced by removing water, it can be quickly introduced into the inner cylindrical chamber 101.
[0037]
Next, various aspects of the gas sensor of the present invention will be described with reference to FIG. FIG. 3 is a sectional view showing a detailed shape of the protector.
Note that the gas sensors of various aspects shown in FIG. 3 are basically the same in configuration as the gas sensor 1 described in the above embodiment, so that common components are denoted by the same reference numerals, and detailed description thereof will be omitted. The characteristic portion will be described.
[0038]
The protector 30 shown in FIG. 3A has a cylindrical outer side wall 36 and an outer bottom wall 11 which is bent from the outer side wall 36 toward the inner side wall 35 to form an insertion hole through which the inner side wall 35 is inserted. The inner side wall 35 protrudes from the insertion hole to the front end side, the protruding portion is used as the bottom side wall 32, and the bottom side wall 43 provided with the second outlet is connected to the front end of the bottom side wall 32. The partition plate 17 having the first discharge port 34 formed therein is engaged with the inner cylindrical portion side wall 35, and the partition plate 17 is used as the inner bottom wall of the inner cylindrical portion 101.
[0039]
According to the protector 30 shown in (a), since the inner side wall 35 protruding from the insertion hole of the outer bottom wall 11 toward the distal end is used as the bottom side wall 32, a new component or a new component is required to form the bottom side wall 32. A joining process is not required, and productivity can be improved. The partition plate 17 can prevent moisture from entering the inner cylindrical portion 101.
[0040]
Next, the protector 40 shown in FIG. 3B is provided with a cylindrical inner side wall 45 on the inner cylindrical portion 101 and the inner bottom wall 10 provided with the first discharge port 14, and the outer cylindrical portion 101 has the outer cylindrical shape. The portion 102 includes a cylindrical outer side wall 46 and an outer bottom wall 11 bent from the outer side wall 46 toward the inner side wall 36, and an end of the outer bottom wall 11 is bent to form a bottom side cylindrical portion. The projection 103 projects in the axial direction toward the bottom wall 43, and this projection is used as the bottom side wall 42 of the bottom cylindrical portion 103. Further, a connecting plate 48 having a through-hole 21 overlapping the first outlet 14 is provided between the inner bottom wall 10 and the outer bottom bottom wall 11.
[0041]
According to the protector 40 shown in (b), since the end of the outer bottom wall 11 of the outer cylindrical portion 102 is bent to form the bottom side wall 42 of the bottom cylindrical portion 103, the bottom side wall 42 is formed. No new parts or joining processing steps are required to form the slab, and productivity can be improved. Further, since the connecting plate 48 is overlapped between the bottom bottom wall 11 and the inner bottom wall 10, even if a non-measurement gas containing moisture flows in from the second outlet, it enters the inner cylindrical portion 101. This can be more reliably prevented from occurring.
[0042]
Next, the protector 50 shown in FIG. 3C includes an inner cylindrical portion 101 having a cylindrical inner side wall 55 and an inner bottom wall 10 provided with a first discharge port 14, and an outer cylindrical portion. 102, a cylindrical outer side wall 56 and an outer bottom wall 54 which is bent inward from the outer side wall 46 and provided with the through hole 21, wherein the through hole 21 is formed on the inner bottom wall of the inner cylindrical portion 101. It has a configuration in which the inner bottom wall 10 and the outer bottom wall 54 are overlapped with each other so as to overlap the first discharge port 14 formed in the bottom wall 10. Further, the outer cylindrical portion 103 is formed by connecting the bottom side wall 52 and the bottom bottom wall 57 provided with the second discharge port 51, and connects the edge of the bottom side wall 52 to the outer cylindrical outer bottom wall. It has a configuration that is bent along and closely adheres to the cable.
[0043]
According to the protector 50 shown in (c), since the inner bottom wall 10 and the outer bottom wall 54 are overlapped with each other, even if the non-measurement gas containing moisture flows in from the second discharge port 51, the inner cylindrical portion is formed. It can be made more reliable so that it does not enter the base 101.
According to the embodiment of the present invention, the protector 4 is provided with the bottom-side cylindrical portion 103 so that unnecessary gas does not flow into the inner cylindrical portion 101 from the second outlet 15. Although a double structure consisting of the bottom side bottom wall 11 and the inside bottom wall 10 is employed, a partition plate may be fitted into the inside side wall 5 to form a multiple structure such as a triple structure.
[0044]
Further, according to the embodiment of the present invention, the outer wall gas inlets 8 are formed uniformly on the outer side wall 6 of the outer cylindrical portion 102 at 45 ° intervals, and the guide body 9 is formed at the end of the outer wall gas inlet 8. The guide 9 is bent at an angle of 45 ° with respect to the outer circumferential tangential direction of the outer side wall 6 from the direction of the arrow. The bending angle may be determined.
[0045]
Further, according to the embodiment of the present invention, the shape of the first outlet 14 and the second outlet 15 is a hole shape corresponding to the thickness of the inner bottom wall 10 and the bottom bottom wall 13. This hole may be projected outward by burring or the like.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of a gas sensor according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating a detailed shape of the protector according to the embodiment.
FIG. 3 is a sectional view illustrating a shape of a protector according to a modified example to which the present invention is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Gas sensor, 2 ... Gas detection element, 3 ... Case, 4, 30, 40, 50 ... Protector, 5, 35, 45, 55 ... Inner side wall, 6, 36, 46, 56 ... Outer side wall, 7 ... Inner wall gas Inlet, 8: outer wall gas inlet, 9: guide body, 10: inner bottom wall, 11, 54: outer bottom wall, 12, 32, 43, 52 ... bottom side wall, 13, 33, 43, 53 ... bottom Side bottom wall, 14, 34 first discharge port, 15, 51 second discharge port, 16 drain hole, 17 partition plate (inner bottom wall), 21 through hole, 47 connection plate Reference numerals 61, lead frame, 62, ceramic holder, 63, talc powder, 64, ceramic sleeve, 65, outer cylinder, 66, lead wire, 67, ceramic separator, 68, flange portion, 69, grommet, 70, outer support portion 101: inner cylindrical portion, 102: outer cylindrical portion , 103 ... bottom cylindrical portion.

Claims

A gas detection element that extends in the axial direction and has a gas contact portion that is in contact with the gas to be measured at the distal end portion,
A case surrounding a radial direction periphery of the gas detection element in a state where the gas contact portion protrudes from a tip,
A bottomed cylindrical protector fixed to the case so as to cover the gas contact portion of the gas detection element,
A gas sensor comprising:
The protector has an inner tubular portion, an outer tubular portion disposed coaxially through a gap in a side wall of the inner tubular portion, and an axially distal end from the inner tubular portion and the outer tubular portion. And a bottom-side tubular portion arranged,
The inner cylindrical portion includes a cylindrical inner side wall and an inner bottom wall connected to the inner side wall,
The outer cylindrical portion includes a cylindrical outer side wall, an outer bottom wall bent from the outer side wall toward the inner side wall, and an inner bottom wall or an inner bottom wall,
The bottom-side tubular portion has a cylindrical bottom side wall protruding in the axial direction from the inner bottom wall or the outer bottom wall toward the tip of the protector, and a bottom bottom connected to a tip of the bottom side wall. With a wall,
On the outer side wall, a plurality of outer wall gas inlets are formed to introduce the gas to be measured into the outer cylindrical portion,
On the inner side wall, a plurality of inner wall gas inlets are formed to introduce the gas to be measured into the inner cylindrical portion,
A first outlet is formed on the inner bottom wall for discharging the gas to be measured from the inner cylindrical portion to the bottom cylindrical portion,
A second discharge port was formed in the bottom bottom wall to discharge the gas to be measured from the bottom cylindrical chamber to the outside of the protector,
A gas sensor, characterized in that:

The protector connects the outer bottom wall to an edge of the inner bottom wall or the inner side wall, and bends and projects the outer side wall from the connection portion toward a tip in the axial direction. The gas sensor according to claim 1, wherein the bottom side wall is formed.

The protector forms an insertion hole through which the inner side wall is inserted into the outer bottom wall, protrudes the inner side wall toward the distal end side from the insertion hole, sets the protruding portion to the bottom side wall, and sets the inner bottom wall to 2. The gas sensor according to claim 1, wherein a partition plate is engaged with the inner side wall so as to face the bottom side bottom wall via a gap.

4. The gas sensor according to claim 1, wherein the protector has the first discharge port and the second discharge port arranged at positions that do not overlap in the axial direction of the gas sensor. 5.

The gas sensor according to any one of claims 1 to 4, wherein the bottom cylindrical portion is formed by tapering the bottom side wall so as to reduce the diameter toward the bottom bottom wall. .

The gas sensor according to any one of claims 1 to 5, wherein the bottom-side tubular portion is provided with a guide body that extends inward at the outer wall gas inlet.