JP3588848B2

JP3588848B2 - Oxygen concentration detector

Info

Publication number: JP3588848B2
Application number: JP04358395A
Authority: JP
Inventors: 勲渡部
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 1995-02-07
Filing date: 1995-02-07
Publication date: 2004-11-17
Anticipated expiration: 2019-11-17
Also published as: JPH08211013A

Description

【０００１】
【産業上の利用分野】
本発明は，自動車用エンジンの空燃比制御等に使用する酸素濃度検出器に関する。
【０００２】
【従来技術】
従来，図２０に示すごとく，筒状のハウジング３と，該ハウジング３内に筒状の絶縁碍子９を介して挿入配置された検出素子４とよりなる酸素濃度検出器（後述の図３参照）がある。上記絶縁碍子９は，上記ハウジング３に設けられた傾斜状受面３２によって支承されるテーパ部９２を有する。
【０００３】
上記絶縁碍子９は環状体であって，セラミック体よりなり，上記傾斜状受面３２と当接するテーパ部９２と，上記検出素子４のツバ部４９を受ける受面９１とを有する。上記テーパ部９２及び受面９１は，金属製のパッキン９１９，９２９において形成されている。
上記ツバ部４９の上方には，図示を略した碍子が配置され，該碍子によって，パッド１４及び粉体１３が，検出素子４，絶縁碍子９及びハウジング３によって形成された空間に配設及び加圧充填されている。
【０００４】
この時，絶縁碍子９には，主として３方向より力が作用する。
即ち，図２１に示すごとく，検出素子４のツバ部４９から，絶縁碍子９の受面９１に対して作用する力であって，酸素濃度検出器の軸芯方向に対して直交する成分が，Ｐ１となる。
【０００５】
もうひとつは，ハウジング３の傾斜状受面３２より絶縁碍子９のテーパ部９２に作用する力であって，上記軸芯方向に対して直交する成分がＰ２となる。
また，もうひとつは，上記粉体１３より絶縁碍子９の上端面９３に作用する力であって，上記軸芯方向に対して直交する成分がＰ３となる。
【０００６】
これらの力は，Ｐ１が絶縁碍子９の外方向，Ｐ２及びＰ３が絶縁碍子９の内方向に作用する。よって，軸芯方向に対して直交する方向ということだけで考えれば上記３つの力は互いに相殺され，絶縁碍子９は力が作用していないのと同様の状態となる。
【０００７】
【解決しようとする課題】
ところで，上記絶縁碍子９にかかる力は，上述のＰ１，Ｐ２，Ｐ３の，軸芯方向に直行する成分の大きさのみを考えれば，相殺され，０となるように考えられる。しかしながら，これらの力は絶縁碍子の軸芯方向に対する作用点が異なるため，実際の絶縁碍子には，これを変形させようとする力が作用している。
【０００８】
この力は，受面９１の近傍を中心に，絶縁碍子９の上端面９３とテーパ部９２とが，絶縁碍子９を「く」の字型に内方向に屈曲するように作用する。
よって，上記酸素濃度検出器においては，例えば，粉体１３等の加圧充填時等に，絶縁碍子９が破損するおそれがある。
【０００９】
このため，上記粉体１３を加圧充填する際，絶縁碍子９の破損を防止するために，より低い圧力によって充填しなくてはならない。よって，上記酸素濃度検出器は，上記粉体１３の充填部分においてシール性が不十分である。
この場合には，酸素濃度検出器における，後述する被測定ガス室及び基準ガス室において，被測定ガスが基準ガス室に混入するおそれがある。
【００１０】
本発明は，かかる問題点に鑑み，絶縁碍子の破損がなく，被測定ガス室及び基準ガス室等のシール性に優れた，酸素濃度検出器を提供しようとするものである。
【００１１】
【課題の解決手段】
本発明は、筒状のハウジングと、該ハウジング内に筒状の絶縁碍子を介して挿入配置された検出素子とよりなる酸素濃度検出器において、
上記検出素子、上記絶縁碍子及び上記ハウジングによって形成された空間には、粉体が加圧充填されており、
上記検出素子はツバ部を有しており、該ツバ部は、上記絶縁碍子に支承されていると共に、上記ツバ部には上記加圧充填された粉体から軸芯方向の力が作用しており、
上記絶縁碍子は、上記ハウジングに設けられた傾斜状受面によって支承されるテーパ部と、上記検出素子の上記ツバ部を受ける受面と、上記粉体が加圧配置されている上端面とを有してなり、かつ、上記テーパ部の内周部分は、上記上端面よりもさらに内周側に位置しており、
上記絶縁碍子における上記受面には、上記ツバ部から軸芯方向の力Ｐ４及び軸芯方向に直交する方向の力Ｐ１が作用し、上記絶縁碍子における上端面には、上記加圧充填された粉体から軸芯方向の力Ｐ６及び軸芯方向に直交する方向の力Ｐ３が作用しており、
上記絶縁碍子における上記テーパ部の外周部分には上記ハウジングの傾斜状受面と当接する当接部を有し、該当接部には、上記ハウジングの上記傾斜状受面から軸芯方向の力Ｐ５及び軸芯方向に直交する方向の力Ｐ２が作用しており、
上記Ｐ５は、上記Ｐ６と上記Ｐ４との合力とバランスしていると共に、上記テーパ部の外周部分の上記当接部に作用点を有しており、
上記絶縁碍子は、上記当接部を介してのみ上記ハウジングの上記傾斜状受面に支承されていることを特徴とする酸素濃度検出器にある。
【００１２】
本発明において最も注目すべきことは，上記絶縁碍子は，上記当接部を介してのみハウジングの傾斜状受面に支承されていることにある。
上記外周部分とは，テーパ部において，酸素濃度検出器の中心である軸芯より最も離れている領域，即ち，テーパ部と絶縁碍子側面との境界となる稜線及び該稜線の近傍の領域である。
【００１３】
そして，上記外周部分の全面が当接部となることが好ましい。この時，絶縁碍子とハウジングとの接触面積が最大となるため，絶縁碍子をハウジングに対して安定配置することができる。また，上記外周部分の一部を当接部とすることもできる。
また，上記当接部には，後述するごとく，パッキン等を介在させ，間接的に当接部と傾斜状受面とを当接させることもできる。いずれにせよ，上記当接部を通じて，傾斜状受面からの力が絶縁碍子に作用する。
【００１４】
また，上記絶縁碍子におけるテーパ部の開き角α（度）と，上記ハウジングにおける傾斜状受面の開き角β（度）との間には，α＞βの関係が成立していることが好ましい（後述の図２参照）。この場合には，確実に絶縁碍子の外周部分のみを当接部とすることができる。
【００１５】
次に，上記絶縁碍子における筒壁の上端面は，該絶縁碍子の軸芯方向で見た時対称形であることが好ましい（後述の図６参照）。即ち，上記上端面は，対称形となる外側上端面と内側上端面とにより構成されている。
【００１６】
これにより，上記絶縁碍子が上端面において受ける力で，軸芯方向に水平な成分は，上記外側上端面における成分と，内側上端面における成分とが打ち消し合い，従来例に示すＰ３に相当する力は０となる。よって，この場合には，絶縁碍子に，従来例において示した内方向に屈曲しようとする力が働かず，絶縁碍子の破損が防止できる。
なお，上記上端面は軸芯方向と直交する平面であることが特に好ましい（後述の図１，図４参照）。この場合にも，従来例に示すＰ３に相当する力は０となる。
【００１７】
上記絶縁碍子はパッキンを介して絶縁碍子の傾斜状受面に支承されていることが好ましい。
上記パッキンは弾性体であるため，傾斜状受面からの力によってパッキン自身が容易に歪むことができる。これにより，パッキンが絶縁碍子にかかる片当たり等の集中荷重の力を吸収することができる。
また，上記パッキンを当接部に貼着することにより，確実に当接部を介して傾斜状受面が絶縁碍子を支承することができる。
【００１８】
上記パッキンはテーパ部又は傾斜状受面のいずれかに一方に設けることができる。上記パッキンをテーパ部に設ける場合には，パッキンの上端面をテーパ部の当接部に対して密着配置する。そして，上記パッキンの外周部分において，ツバ部が傾斜状受面と当接することができる（図１３参照）。
一方，上記パッキンを傾斜状受面に設ける場合には，パッキンの下面を傾斜状受面に対して密着配置することもできる。
【００１９】
また，上記パッキンの形状は，例えば，中央に検出素子を挿通する穴を設けた環状体である。更に，上記パッキンの外径は，ツバ部の外径よりも大きいことが好ましい。この場合には，パッキンが絶縁碍子とハウジングとの間の隙間を封止することができ，酸素濃度検出器の気密性を一層保つことができ，基準ガス室内に被測定ガスが侵入すること等を防止することができる。
なお，上記パッキンは，ニッケル，ステンレス等の耐熱合金を用いるのがよい。
【００２０】
上記当接部は曲面であることが好ましい。これにより，上記当接部にかかる力を分散させ，検出素子にかかる集中応力をより軽減させることができる。
次に，上記当接部は突出部を有することが好ましい（図７）。また，上記絶縁碍子の傾斜状受面は，上記当接部と当接する突出部を有することが好ましい（図８）。また，上記突出部は当接部全体に設けることも，部分的に設けることもできる。
これにより，絶縁碍子とハウジングとが，絶縁碍子のテーパ部の外周部分で確実に当接することができる。
【００２１】
【作用及び効果】
本発明の酸素濃度検出器においては，絶縁碍子はテーパ部における外周部分の当接部を介してのみハウジングの傾斜状受面に支承されている。また，上記外周部分は，上記テーパ部において酸素濃度検出器の中心である軸芯より最も離れた領域であると共に上記テーパ部と上記絶縁碍子の側面との境界である稜線及び該稜線の近傍の領域である。
これにより，後述するごとく，絶縁碍子に，これを屈曲させるようなねじれの力が作用しない。従って，絶縁碍子が破損することがない。
【００２２】
また，上記粉体をより大きな圧力で加圧し，より大きな力で検出素子をハウジングに組付けることができるため，検出素子とハウジングとの間の気密性に優れた酸素濃度検出器を得ることができる。
【００２３】
上記のごとく，本発明によれば，絶縁碍子の破損がなく，被測定ガス室及び基準ガス室等のシール性に優れた，酸素濃度検出器を提供することができる。
【００２４】
【実施例】
実施例１
本発明の実施例にかかる酸素濃度検出器１につき，図１〜図６を用いて説明する。
図１，図２に示すごとく，本例の酸素濃度検出器１は，筒状のハウジング３と，該ハウジング３内に筒状の絶縁碍子２を介して挿入配置された検出素子４とよりなる。
【００２５】
上記絶縁碍子２は，上記ハウジング３に設けられた傾斜状受面３２の外周部分３０によって支承されるテーパ部２２を有し，該テーパ部２２の外周部分には上記ハウジング３の傾斜状受面３２と当接する当接部２０を有する。
そして，上記絶縁碍子２は上記当接部２０を介してのみハウジング３の傾斜状受面３２に支承されている。なお，上記絶縁碍子２の上端面２３は，酸素濃度検出器１の軸芯方向と直交する平面である。
【００２６】
また，図２に示すごとく，上記絶縁碍子２におけるテーパ部２２の開き角α（度）と，上記ハウジング３における傾斜状受面３２の開き角β（度）との間には，α＞βの関係が成立している。
図２，図３に示すごとく，上記検出素子４は絶縁碍子２の受面２１に支承されるツバ部４９を有する。なお，符号４１は上記ツバ部４９における受面２１との当接面である。
【００２７】
また，上記ツバ部４９の上方及び絶縁碍子２の上端面２３には，粉体１３及びパッド１４が碍子１５により加圧配置されている。
即ち，図１〜図３に示すごとく，ハウジング３において，上記粉体１３，パッド１４を所定の位置に配置した後，上記碍子１５を，スペーサー１５９，保護カバー１７１と共に嵌め込む。これにより，粉体１３，パッド１４が下方へ押圧充填及び配置される。
なお，上記検出素子４，絶縁碍子２等は酸素濃度検出器１の軸芯に対し，同軸的にハウジング３内に配置されている。
【００２８】
図３に示すごとく，上記酸素濃度検出器１における検出素子４は，ハウジングの下方に配置された保護カバー１６１，１６２により形成される被測定ガス室１６０内に配置されている。検出素子４は，コップ型の固体電解質４５と，その内側表面に設けた基準電極４５８と外側面に設けた被測定ガス側電極４５９とよりなる。
【００２９】
上記固体電解質４５は基準ガス室４５０を有し，該基準ガス室４５０に対面する部分には基準電極４５８が，上記被測定ガス室１６０に対面する部分には被測定ガス側電極４５９が設けてある。
そして，上記基準ガス室４５０内にはヒータ１１が配置されている。
なお，同図において，符号１７２，１７３は外側カバー，１８１，１８２はリード線である。
【００３０】
次に，本例における作用効果につき説明する。
本例の酸素濃度検出器１の絶縁碍子２には，主として３方向より力が作用している。
即ち，図４に示すごとく，検出素子４のツバ部４９より，絶縁碍子２の受面２１に作用する力は，酸素濃度検出器１の軸芯方向に対して直交する成分がＰ１，平行な成分がＰ４である。また，ハウジング３の傾斜状受面３２より絶縁碍子２のテーパ部２２に作用する力で，上記軸芯方向に対して直交する成分がＰ２，平行な成分がＰ５である。
【００３１】
また，加圧充填された粉体１３より絶縁碍子２の上端面２３に作用する力で，上記軸芯方向に対して直交する成分がＰ３，平行な成分がＰ６である。ただし，本例の絶縁碍子２は上端面２３が軸芯方向に直交する平面となっている。よって，Ｐ３成分の大きさは０であり，図示できない（なお，上端面９３が平面でない絶縁碍子９を有する従来例では，図２１に示すごとく，Ｐ３を図示することができる）。
【００３２】
ところで，Ｐ６とＰ４との合力とバランスをとるＰ５は，絶縁碍子２の最も外周部分，即ちＰ６により近い箇所に作用点を持っていることが好ましい。
仮に，図５に示すごとく，絶縁碍子２９におけるテーパ部２２の最も内周部分に当接部が存在する場合には，Ｐ５が絶縁碍子２の内周部分において上方に，Ｐ６が絶縁碍子２の外周部分において下方に作用する。このため，絶縁碍子２には，これを押し曲げようとする力が作用し，破損するおそれがある。
【００３３】
本例の酸素濃度検出器１においては，絶縁碍子２におけるテーパ部２２の開き角α（度）と，上記ハウジング３における傾斜状受面３２の開き角β（度）との間には，α＜βの関係が成立しており，当接部２０が必ず絶縁碍子２の外周部分となる。また，上記当接部２０以外のテーパ部２２は傾斜状受面３２と接触しない。
【００３４】
このため，上記絶縁碍子２で，軸芯方向と平行に作用する力は，Ｐ４，Ｐ５，Ｐ６である。これらの力による，絶縁碍子２を屈強させようとする力は，上述したごとく，作用しない。従って，これらの力によって絶縁碍子２の破損は生じない。
【００３５】
また，上記粉体１３をより大きな圧力で加圧し，より大きな力で検出素子４をハウジング３に組付けることができるため，検出素子４とハウジング３との間の気密性に優れた酸素濃度検出器１を得ることができる。
【００３６】
更に，上記絶縁碍子２で，軸芯方向に直交するよう作用する力は，Ｐ１とＰ２である。Ｐ１とＰ２は両者の距離も短く，従来例に示すごとく絶縁碍子２を屈曲させようとする力が作用しない。従って，これらの力によっても絶縁碍子２の破損が生じない。
【００３７】
従って，本例によれば，絶縁碍子の破損がなく，被測定ガス室及び基準ガス室等のシール性に優れた，酸素濃度検出器を提供することができる。
【００３８】
なお，上記絶縁碍子２の他の例としては，図６に示すごとく，筒壁２５の上端面が，外側上端面２３１と内側上端面２３２とよりなり，両者は軸芯方向にのびる軸２５０に対して対称な形状を有する絶縁碍子２９がある。
図６（ａ）に示す絶縁碍子２９は，外側上端面２３１及び内側上端面２３２は，円弧形状であり，一方，図６（ｂ）に示す絶縁碍子２９は，上記外側上端面２３１及び内側上端面２３２は三角形状である。
【００３９】
上記絶縁碍子２９が上端面において，粉体１３より受ける力で，軸芯方向に水平な成分は，上記外側上端面２３１における成分と，内側上端面２３２における成分とが打ち消し合い，０となる。
このため，図６に示す絶縁碍子２９も，酸素濃度検出器１に組付けた場合に，破損が生じない。
【００４０】
実施例２
本例は，図７に示すごとく，テーパ部２２における当接部２０が突出部２０１を有する酸素濃度検出器１である。
即ち，上記酸素濃度検出器１の絶縁碍子２は，ハウジング３に設けられた傾斜状受面３２によって支承されるテーパ部２２を有し，該テーパ部２２の当接部２０には，上記ハウジング３の傾斜状受面３２における当接部３０と当接する突出部２０１を設けてある。そして，上記突出部２０１は上記当接部２０の全面に，環状に形成されている。
その他は，実施例１と同様である。
【００４１】
本例における酸素濃度検出器１においては，絶縁碍子２とハウジング３とが絶縁碍子２のテーパ部２２の外周部分において確実に当接することができる。
その他，実施例１と同様の作用効果を有する。
【００４２】
実施例３
本例は，図８〜図１０に示すごとく，当接部が突出部２０２を有する酸素濃度検出器の絶縁碍子２である。
即ち，本例の絶縁碍子２は，ハウジングに設けられた傾斜状受面によって支承されるテーパ部２２を有し，該テーパ部２２の当接部には，上記ハウジングの傾斜状受面における当接部と当接する突出部２０２を設けてある。そして，上記突出部２０２は上記当接部の表面に３ヶ所形成されている。
その他は，実施例１と同様である。
【００４３】
本例における絶縁碍子２は，テーパ部２２及びハウジングの傾斜状受面の円筒度等の形状精度が低くてもよく，製造コストが低減できる。
その他，実施例１と同様の作用効果を有する。
【００４４】
実施例４
本例は，図１１に示すごとく，ハウジング３の傾斜状受面３２が突出部３０１を有する酸素濃度検出器１である。
即ち，上記酸素濃度検出器１の絶縁碍子２は，ハウジング３に設けられた傾斜状受面３２によって支承されるテーパ部２２を有し，該テーパ部２２の当接部２０は，上記ハウジング３の傾斜状受面３２における当接部３０に設けられた突出部３０１によって支承されている。なお，上記突出部３０１は上記当接部２０の全面を受けている。
その他は，実施例１と同様である。
【００４５】
本例における酸素濃度検出器１は，絶縁碍子２とハウジング３とが絶縁碍子２のテーパ部２２の外周部分において確実に当接することができる。
その他，実施例１と同様の作用効果を有する。
【００４６】
実施例５
本例は，図１２〜図１４に示すごとく，環状のパッキン５を絶縁碍子２のテーパ部２２の下面に設けた酸素濃度検出器１である。
即ち，図１２，図１３は，テーパ部２２の直径よりも大きいパッキン５を設けた酸素濃度検出器１である。上記パッキン５の上面５１は絶縁碍子２のテーパ部２２に対して全面当接している。そして，上記パッキン５の下面５０の外周部分における当接部５０１がハウジング３の傾斜状受面３２と当接する。
【００４７】
また，図１４は，テーパ部２２の直径と同じ大きさのパッキン５９を絶縁碍子３のテーパ部２２に設けた酸素濃度検出器１である。上記パッキン５９は環の外周部分は厚みがあり，内周部分は薄くなっている。上記パッキン５９の上面はテーパ部２２に対して全面当接している。そして，上記パッキン５９の下面５０の外周部分における当接部５９１が傾斜状受面１１と当接する。
その他は，実施例１と同様である。
【００４８】
本例における酸素濃度検出器１は，形状加工の容易なパッキン５９により，目的が達せられることになり，製造コストが安くて済む。
その他，実施例１と同様の作用効果を有する。
【００４９】
実施例６
上記実施例１〜５は，コップ型検出素子を用いた酸素濃度検出器につき例示したが，本例は，図１５〜図１９に示すごとく，積層型の検出素子６を用いた酸素濃度検出器１である。
即ち，本例の酸素濃度検出器１は，図１５に示すごとく，筒状のハウジング３と，該ハウジング３内に筒状の絶縁碍子２を介して挿入配置された，積層型の検出素子６とよりなる。上記積層型の検出素子６は平板状で，ヒータを内蔵している。なお，図１６に示すごとく，上記検出素子６は，大気導入等に用いる細孔６０をその軸方向に有している。
【００５０】
そして，上記絶縁碍子２は，上記ハウジング３に設けられた傾斜状受面３２によって支承されるテーパ部２２を有し，該テーパ部２２の外周部分には上記ハウジング３の傾斜状受面３２と当接する当接部２０を有しており，かつ上記絶縁碍子２は上記当接部２０を介してのみハウジング３における傾斜状受面３２に支承されている。
【００５１】
なお，図１７〜図１９に上記絶縁碍子２を示す。上記絶縁碍子２における，検出素子６の挿入配置部２３０は検出素子６の断面形状と同様に角形である。そして，配置部の内部には検出素子６のツバ部６９を受けるための，角形の受面２１が設けてある。その他は，実施例１と同様である。
その他，実施例１と同様の作用効果を有する。
【図面の簡単な説明】
【図１】実施例１における，酸素濃度検出器の要部断面図。
【図２】実施例１における，酸素濃度検出器の要部断面図。
【図３】実施例１における，酸素濃度検出器の断面図。
【図４】実施例１における，絶縁碍子の説明図。
【図５】実施例１における，破損しやすい絶縁碍子の説明図。
【図６】実施例１における，他の絶縁碍子の断面図。
【図７】実施例２における，酸素濃度検出器の要部断面図。
【図８】実施例３における，酸素濃度検出器の絶縁碍子の側面図。
【図９】実施例３における，絶縁碍子の底面図。
【図１０】実施例３における，絶縁碍子の斜視図。
【図１１】実施例４における，酸素濃度検出器の要部断面図。
【図１２】実施例５における，パッキンを有する酸素濃度検出器の要部断面図。
【図１３】実施例５における，絶縁碍子とパッキンの説明図。
【図１４】実施例５における，その他の酸素濃度検出器の説明図。
【図１５】実施例６における，積層型検出素子を有する酸素濃度検出器の要部断面図。
【図１６】実施例６における，積層型検出素子の斜視図。
【図１７】実施例６における，絶縁碍子の正面図。
【図１８】図１７のＢ−Ｂ線矢視断面図。
【図１９】図１７のＣ−Ｃ線矢視断面図。
【図２０】従来例における，酸素濃度検出器の要部断面図。
【図２１】従来例における，絶縁碍子の説明図。
【符号の説明】
１．．．酸素濃度検出器，
２．．．絶縁碍子，
２０．．．当接部，
２２．．．テーパ部，
３．．．ハウジング，
３２．．．傾斜状受面，
４，６．．．検出素子，[0001]
[Industrial applications]
The present invention relates to an oxygen concentration detector used for air-fuel ratio control of an automobile engine.
[0002]
[Prior art]
Conventionally, as shown in FIG. 20, an oxygen concentration detector comprising a cylindrical housing 3 and a detection element 4 inserted and arranged in the housing 3 via a cylindrical insulator 9 (see FIG. 3 described later). There is. The insulator 9 has a tapered portion 92 supported by the inclined receiving surface 32 provided on the housing 3.
[0003]
The insulator 9 is an annular body, made of a ceramic body, and has a tapered portion 92 in contact with the inclined receiving surface 32 and a receiving surface 91 for receiving the collar portion 49 of the detecting element 4. The tapered portion 92 and the receiving surface 91 are formed by packings 919 and 929 made of metal.
Above the flange 49, an insulator (not shown) is arranged, and the insulator arranges and adds a pad 14 and powder 13 in a space formed by the detecting element 4, the insulator 9, and the housing 3. Pressure-filled.
[0004]
At this time, forces act on the insulator 9 mainly from three directions.
That is, as shown in FIG. 21, the force acting on the receiving surface 91 of the insulator 9 from the brim portion 49 of the detecting element 4 and orthogonal to the axis of the oxygen concentration detector is It becomes P1.
[0005]
The other is the force acting on the tapered portion 92 of the insulator 9 from the inclined receiving surface 32 of the housing 3, and the component orthogonal to the axial direction is P2.
The other is a force acting on the upper end surface 93 of the insulator 9 from the powder 13, and a component orthogonal to the axis direction is P 3.
[0006]
Among these forces, P1 acts outward of the insulator 9, and P2 and P3 act inward of the insulator 9. Therefore, if only the direction orthogonal to the axial direction is considered, the above three forces cancel each other out, and the insulator 9 is in a state similar to the state where no force acts.
[0007]
[Problem to be solved]
By the way, the forces acting on the insulator 9 are considered to be canceled out and become zero if only the magnitudes of the components P1, P2, and P3 perpendicular to the axial direction are considered. However, since these forces have different points of action in the axial direction of the insulator, a force that deforms the insulator acts on the actual insulator.
[0008]
This force acts so that the upper end surface 93 and the tapered portion 92 of the insulator 9 bend the insulator 9 inwardly in the shape of a square around the vicinity of the receiving surface 91.
Therefore, in the oxygen concentration detector, the insulator 9 may be damaged, for example, when the powder 13 or the like is filled under pressure.
[0009]
For this reason, when the powder 13 is charged under pressure, it must be filled with a lower pressure in order to prevent damage to the insulator 9. Therefore, the oxygen concentration detector has an insufficient sealing property at the portion where the powder 13 is filled.
In this case, there is a possibility that the measured gas may enter the reference gas chamber in the measured gas chamber and the reference gas chamber described later in the oxygen concentration detector.
[0010]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an oxygen concentration detector which does not damage an insulator and has excellent sealing properties for a gas chamber to be measured and a reference gas chamber.
[0011]
[Means for solving the problem]
The present invention relates to an oxygen concentration detector comprising a cylindrical housing and a detection element inserted and arranged in the housing via a cylindrical insulator,
The space formed by the detection element, the insulator and the housing is filled with powder under pressure,
The detection element has a flange portion, the flange portion, together are supported on the insulator, in the above flange portion acts axial force from the pressure-filled powder Yes,
The insulator includes a tapered portion supported by an inclined receiving surface provided in the housing, a receiving surface for receiving the brim portion of the detection element, and an upper end surface on which the powder is pressed and arranged. And, the inner peripheral portion of the tapered portion is located further inward than the upper end surface,
A force P4 in the axial direction and a force P1 in a direction perpendicular to the axial direction are applied from the flange to the receiving surface of the insulator, and the upper end surface of the insulator is filled with the pressure. A force P6 in the axial direction and a force P3 in the direction perpendicular to the axial direction are acting from the powder,
An outer peripheral portion of the tapered portion of the insulator has an abutting portion that comes into contact with the inclined receiving surface of the housing. The contact portion has a force P5 in the axial direction from the inclined receiving surface of the housing. And a force P2 in a direction orthogonal to the axis direction is acting,
The P5 is balanced with the resultant force of the P6 and the P4, and has an action point on the contact portion of the outer peripheral portion of the tapered portion.
The insulator is in the oxygen concentration sensor, characterized in that it is supported on the inclined receiving surface of the housing only through the contact portion.
[0012]
The most remarkable feature of the present invention is that the insulator is supported on the inclined receiving surface of the housing only through the contact portion.
The outer peripheral portion is a region in the tapered portion that is farthest from the axis, which is the center of the oxygen concentration detector, that is, a ridgeline that is a boundary between the tapered portion and the side surface of the insulator and a region near the ridgeline. .
[0013]
It is preferable that the entire outer peripheral portion be the contact portion. At this time, since the contact area between the insulator and the housing is maximized, the insulator can be stably arranged with respect to the housing. Further, a part of the outer peripheral portion may be used as a contact portion.
Further, as will be described later, a packing or the like may be interposed in the contact portion to indirectly contact the contact portion with the inclined receiving surface. In any case, the force from the inclined receiving surface acts on the insulator through the contact portion.
[0014]
Further, it is preferable that the relationship α> β is established between the opening angle α (degree) of the tapered portion of the insulator and the opening angle β (degree) of the inclined receiving surface of the housing. (See FIG. 2 described below). In this case, only the outer peripheral portion of the insulator can be reliably used as the contact portion.
[0015]
Next, the upper end surface of the cylindrical wall of the insulator is preferably symmetric when viewed in the axial direction of the insulator (see FIG. 6 described later). That is, the upper end surface is constituted by a symmetric outer upper end surface and an inner upper end surface.
[0016]
As a result, the component that is horizontal to the axial center direction due to the force that the insulator receives on the upper end face cancels out the component on the outer upper end face and the component on the inner upper end face, and a force corresponding to P3 shown in the conventional example. Becomes 0. Therefore, in this case, the inward bending force shown in the conventional example does not act on the insulator, and the insulator can be prevented from being damaged.
It is particularly preferable that the upper end surface is a plane orthogonal to the axis direction (see FIGS. 1 and 4 described later). Also in this case, the force corresponding to P3 shown in the conventional example is zero.
[0017]
Preferably, the insulator is supported on an inclined receiving surface of the insulator via a packing.
Since the packing is an elastic body, the packing itself can be easily distorted by the force from the inclined receiving surface. Thereby, the packing can absorb the force of the concentrated load such as the one-sided load applied to the insulator.
In addition, by attaching the packing to the contact portion, the inclined receiving surface can reliably support the insulator via the contact portion.
[0018]
The packing may be provided on one of the tapered portion and the inclined receiving surface. When the packing is provided on the tapered portion, the upper end surface of the packing is disposed in close contact with the contact portion of the tapered portion. Then, in the outer peripheral portion of the packing, the brim portion can contact the inclined receiving surface (see FIG. 13).
On the other hand, when the packing is provided on the inclined receiving surface, the lower surface of the packing may be arranged in close contact with the inclined receiving surface.
[0019]
The shape of the packing is, for example, an annular body provided with a hole for inserting the detection element in the center. Further, the outer diameter of the packing is preferably larger than the outer diameter of the collar portion. In this case, the packing can seal the gap between the insulator and the housing, the airtightness of the oxygen concentration detector can be further maintained, and the gas to be measured enters the reference gas chamber. Can be prevented.
The packing is preferably made of a heat-resistant alloy such as nickel and stainless steel.
[0020]
It is preferable that the contact portion has a curved surface. Thereby, the force applied to the contact portion can be dispersed, and the concentrated stress applied to the detection element can be further reduced.
Next, it is preferable that the contact portion has a protrusion (FIG. 7). Further, it is preferable that the inclined receiving surface of the insulator has a protruding portion which comes into contact with the contact portion (FIG. 8). Further, the projecting portion can be provided on the entire contact portion or can be provided partially.
Thus, the insulator and the housing can be reliably contacted at the outer peripheral portion of the tapered portion of the insulator.
[0021]
[Action and effect]
In the oxygen concentration detector of the present invention, the insulator is supported on the inclined receiving surface of the housing only through the contact portion of the outer peripheral portion of the tapered portion. Further, the outer peripheral portion is a region which is farthest from the axis which is the center of the oxygen concentration detector in the tapered portion, and a ridge line which is a boundary between the tapered portion and the side surface of the insulator and a vicinity of the ridge line. Area.
As a result, as described later, a torsional force for bending the insulator does not act on the insulator. Therefore, the insulator is not damaged.
[0022]
Also, since the powder can be pressurized with a larger pressure and the detecting element can be assembled to the housing with a larger force, it is possible to obtain an oxygen concentration detector having excellent airtightness between the detecting element and the housing. it can.
[0023]
As described above, according to the present invention, it is possible to provide an oxygen concentration detector which is free from breakage of the insulator and has excellent sealing properties for the gas chamber to be measured and the reference gas chamber.
[0024]
【Example】
Example 1
An oxygen concentration detector 1 according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIGS. 1 and 2, the oxygen concentration detector 1 of the present embodiment includes a cylindrical housing 3 and a detection element 4 inserted and arranged in the housing 3 via a cylindrical insulator 2. .
[0025]
The insulator 2 has a tapered portion 22 supported by an outer peripheral portion 30 of an inclined receiving surface 32 provided on the housing 3, and an inclined receiving surface of the housing 3 is provided on an outer peripheral portion of the tapered portion 22. 32 has a contact portion 20 that comes into contact therewith.
The insulator 2 is supported on the inclined receiving surface 32 of the housing 3 only through the contact portion 20. The upper end surface 23 of the insulator 2 is a plane orthogonal to the axis of the oxygen concentration detector 1.
[0026]
As shown in FIG. 2, the angle α (degree) between the tapered portion 22 of the insulator 2 and the angle β (degree) of the inclined receiving surface 32 of the housing 3 is α> β. Is established.
As shown in FIGS. 2 and 3, the detecting element 4 has a brim portion 49 supported on the receiving surface 21 of the insulator 2. Reference numeral 41 denotes a contact surface of the collar portion 49 with the receiving surface 21.
[0027]
The powder 13 and the pad 14 are pressurized by the insulator 15 above the flange 49 and on the upper end surface 23 of the insulator 2.
That is, as shown in FIGS. 1 to 3, after the powder 13 and the pad 14 are arranged at predetermined positions in the housing 3, the insulator 15 is fitted together with the spacer 159 and the protective cover 171. As a result, the powder 13 and the pad 14 are pressed and filled downward and arranged.
The detecting element 4, the insulator 2, and the like are arranged in the housing 3 coaxially with the axis of the oxygen concentration detector 1.
[0028]
As shown in FIG. 3, the detection element 4 of the oxygen concentration detector 1 is disposed in a measured gas chamber 160 formed by protective covers 161 and 162 disposed below the housing. The detection element 4 includes a cup-shaped solid electrolyte 45, a reference electrode 458 provided on the inner surface thereof, and a measured gas side electrode 459 provided on the outer surface thereof.
[0029]
The solid electrolyte 45 has a reference gas chamber 450, a reference electrode 458 is provided at a portion facing the reference gas chamber 450, and a measured gas side electrode 459 is provided at a portion facing the measured gas chamber 160. is there.
The heater 11 is disposed in the reference gas chamber 450.
In the figure, reference numerals 172 and 173 denote outer covers, and reference numerals 181 and 182 denote lead wires.
[0030]
Next, the operation and effect of this embodiment will be described.
Forces mainly act on the insulator 2 of the oxygen concentration detector 1 of this embodiment from three directions.
That is, as shown in FIG. 4, the force acting on the receiving surface 21 of the insulator 2 from the brim portion 49 of the detecting element 4 is such that the component orthogonal to the axial direction of the oxygen concentration detector 1 is P1, The component is P4. The component acting on the tapered portion 22 of the insulator 2 from the inclined receiving surface 32 of the housing 3 is P2, and the component parallel to the axis is P5.
[0031]
In addition, a force acting on the upper end surface 23 of the insulator 2 from the powder 13 filled with the pressure is P3 in a component orthogonal to the axial direction and P6 in a parallel component. However, the insulator 2 of the present embodiment is a plane whose upper end surface 23 is orthogonal to the axial direction. Therefore, the magnitude of the P3 component is 0 and cannot be illustrated (note that in the conventional example having the insulator 9 whose upper end surface 93 is not flat, P3 can be illustrated as shown in FIG. 21).
[0032]
Incidentally, it is preferable that P5, which balances the resultant force of P6 and P4, has an action point at the outermost peripheral portion of the insulator 2, that is, a portion closer to P6.
As shown in FIG. 5, if an abutting portion exists at the innermost peripheral portion of the tapered portion 22 of the insulator 29, P5 is located above the inner peripheral portion of the insulator 2 and P6 is located at the inner peripheral portion of the insulator 2. Acts downward at the outer periphery. For this reason, there is a possibility that a force acting to push and bend the insulator 2 acts on the insulator 2 and the insulator 2 may be damaged.
[0033]
In the oxygen concentration detector 1 of this embodiment, the angle α (degree) between the tapered portion 22 of the insulator 2 and the angle β (degree) of the inclined receiving surface 32 of the housing 3 is α. <Β is established, and the contact portion 20 is always the outer peripheral portion of the insulator 2. Further, the tapered portion 22 other than the contact portion 20 does not contact the inclined receiving surface 32.
[0034]
For this reason, the forces acting in the insulator 2 in parallel with the axial direction are P4, P5, and P6. As described above, these forces do not act to cause the insulator 2 to flex. Therefore, the insulator 2 is not damaged by these forces.
[0035]
Further, since the powder 13 can be pressurized with a larger pressure and the detection element 4 can be assembled to the housing 3 with a larger force, the oxygen concentration detection with excellent airtightness between the detection element 4 and the housing 3 can be achieved. Vessel 1 can be obtained.
[0036]
Further, forces acting on the insulator 2 so as to be orthogonal to the axial direction are P1 and P2. The distance between P1 and P2 is short, and no force acts to bend the insulator 2 as shown in the conventional example. Therefore, the insulator 2 is not damaged by these forces.
[0037]
Therefore, according to the present embodiment, it is possible to provide an oxygen concentration detector which is free from breakage of the insulator and has excellent sealing properties for the gas chamber to be measured and the reference gas chamber.
[0038]
As another example of the insulator 2, as shown in FIG. 6, the upper end surface of the cylindrical wall 25 is composed of an outer upper end surface 231 and an inner upper end surface 232, and both are formed on a shaft 250 extending in the axial direction. There is an insulator 29 having a symmetrical shape.
In the insulator 29 shown in FIG. 6A, the outer upper end surface 231 and the inner upper end surface 232 are arc-shaped, while the insulator 29 shown in FIG. 6B has the outer upper end surface 231 and the inner upper surface. The end face 232 has a triangular shape.
[0039]
With the force received by the powder 13 on the upper end surface of the insulator 29, the component horizontal in the axial direction is zero because the component on the outer upper end surface 231 and the component on the inner upper end surface 232 cancel each other out.
Therefore, when the insulator 29 shown in FIG. 6 is assembled to the oxygen concentration detector 1, no damage occurs.
[0040]
Example 2
In this example, as shown in FIG. 7, the contact portion 20 of the tapered portion 22 is the oxygen concentration detector 1 having the protruding portion 201.
That is, the insulator 2 of the oxygen concentration detector 1 has the tapered portion 22 supported by the inclined receiving surface 32 provided on the housing 3, and the abutting portion 20 of the tapered portion 22 includes the housing 2. A projection 201 is provided to be in contact with the contact portion 30 of the third inclined receiving surface 32. The projecting portion 201 is formed in an annular shape on the entire surface of the contact portion 20.
Others are the same as the first embodiment.
[0041]
In the oxygen concentration detector 1 according to the present embodiment, the insulator 2 and the housing 3 can reliably contact with each other at the outer peripheral portion of the tapered portion 22 of the insulator 2.
In addition, the third embodiment has the same functions and effects as those of the first embodiment.
[0042]
Example 3
This example is an insulator 2 of an oxygen concentration detector having a protruding portion 202 as a contact portion, as shown in FIGS.
That is, the insulator 2 of this embodiment has the tapered portion 22 supported by the inclined receiving surface provided on the housing, and the abutting portion of the tapered portion 22 has a contact portion on the inclined receiving surface of the housing. A protruding portion 202 that comes into contact with the contact portion is provided. The protrusions 202 are formed at three locations on the surface of the contact portion.
Others are the same as the first embodiment.
[0043]
In the insulator 2 in this example, the tapered portion 22 and the inclination accuracy of the inclined receiving surface of the housing may have low shape accuracy, and the manufacturing cost can be reduced.
In addition, the third embodiment has the same functions and effects as those of the first embodiment.
[0044]
Example 4
This example is an oxygen concentration detector 1 in which the inclined receiving surface 32 of the housing 3 has a projection 301 as shown in FIG.
That is, the insulator 2 of the oxygen concentration detector 1 has the tapered portion 22 supported by the inclined receiving surface 32 provided on the housing 3, and the contact portion 20 of the tapered portion 22 is Are supported by a protruding portion 301 provided on the abutting portion 30 of the inclined receiving surface 32. The protruding portion 301 receives the entire surface of the contact portion 20.
Others are the same as the first embodiment.
[0045]
In the oxygen concentration detector 1 according to the present embodiment, the insulator 2 and the housing 3 can reliably contact each other at the outer peripheral portion of the tapered portion 22 of the insulator 2.
In addition, the third embodiment has the same functions and effects as those of the first embodiment.
[0046]
Example 5
This example is the oxygen concentration detector 1 in which the annular packing 5 is provided on the lower surface of the tapered portion 22 of the insulator 2 as shown in FIGS.
That is, FIGS. 12 and 13 show the oxygen concentration detector 1 provided with the packing 5 larger than the diameter of the tapered portion 22. The upper surface 51 of the packing 5 is in full contact with the tapered portion 22 of the insulator 2. Then, the contact portion 501 on the outer peripheral portion of the lower surface 50 of the packing 5 contacts the inclined receiving surface 32 of the housing 3.
[0047]
FIG. 14 shows an oxygen concentration detector 1 in which a packing 59 having the same size as the diameter of the tapered portion 22 is provided on the tapered portion 22 of the insulator 3. In the packing 59, the outer peripheral portion of the ring is thick and the inner peripheral portion is thin. The upper surface of the packing 59 is in full contact with the tapered portion 22. Then, the contact portion 591 on the outer peripheral portion of the lower surface 50 of the packing 59 contacts the inclined receiving surface 11.
Others are the same as the first embodiment.
[0048]
The purpose of the oxygen concentration detector 1 in this example can be achieved by the packing 59 whose shape can be easily processed, and the manufacturing cost can be reduced.
In addition, the third embodiment has the same functions and effects as those of the first embodiment.
[0049]
Example 6
The first to fifth embodiments have exemplified the oxygen concentration detector using the cup-type detection element. However, as shown in FIGS. 15 to 19, the present embodiment relates to the oxygen concentration detector using the stacked detection element 6. It is one.
That is, as shown in FIG. 15, the oxygen concentration detector 1 according to the present embodiment has a cylindrical housing 3 and a laminated detection element 6 inserted and disposed in the housing 3 with the cylindrical insulator 2 interposed therebetween. And The laminated detection element 6 has a flat plate shape and incorporates a heater. As shown in FIG. 16, the detection element 6 has pores 60 used for introducing air into the atmosphere in the axial direction.
[0050]
The insulator 2 has a tapered portion 22 supported by an inclined receiving surface 32 provided on the housing 3, and an outer peripheral portion of the tapered portion 22 is provided with the inclined receiving surface 32 of the housing 3. The insulator 2 is supported on the inclined receiving surface 32 of the housing 3 only through the contact portion 20.
[0051]
17 to 19 show the insulator 2 described above. The insertion arrangement part 230 of the detection element 6 in the insulator 2 is square like the cross-sectional shape of the detection element 6. Further, a rectangular receiving surface 21 for receiving the brim portion 69 of the detection element 6 is provided inside the disposition portion. Others are the same as the first embodiment.
In addition, the third embodiment has the same functions and effects as those of the first embodiment.
[Brief description of the drawings]
FIG. 1 is a sectional view of a main part of an oxygen concentration detector according to a first embodiment.
FIG. 2 is a sectional view of a main part of the oxygen concentration detector according to the first embodiment.
FIG. 3 is a cross-sectional view of the oxygen concentration detector according to the first embodiment.
FIG. 4 is an explanatory diagram of an insulator according to the first embodiment.
FIG. 5 is an explanatory view of an insulator that is easily damaged in the first embodiment.
FIG. 6 is a sectional view of another insulator according to the first embodiment.
FIG. 7 is a sectional view of a main part of an oxygen concentration detector according to a second embodiment.
FIG. 8 is a side view of the insulator of the oxygen concentration detector according to the third embodiment.
FIG. 9 is a bottom view of the insulator according to the third embodiment.
FIG. 10 is a perspective view of an insulator according to a third embodiment.
FIG. 11 is a sectional view of a main part of an oxygen concentration detector according to a fourth embodiment.
FIG. 12 is a sectional view of a main part of an oxygen concentration detector having a packing in a fifth embodiment.
FIG. 13 is an explanatory view of an insulator and a packing in the fifth embodiment.
FIG. 14 is an explanatory diagram of another oxygen concentration detector according to the fifth embodiment.
FIG. 15 is a sectional view of a main part of an oxygen concentration detector having a stacked detection element according to a sixth embodiment.
FIG. 16 is a perspective view of a stacked detection element according to a sixth embodiment.
FIG. 17 is a front view of an insulator according to a sixth embodiment.
FIG. 18 is a cross-sectional view taken along line BB of FIG. 17;
FIG. 19 is a sectional view taken along line CC of FIG. 17;
FIG. 20 is a sectional view of a main part of an oxygen concentration detector in a conventional example.
FIG. 21 is an explanatory view of an insulator in a conventional example.
[Explanation of symbols]
1. . . Oxygen concentration detector,
2. . . Insulator,
20. . . Abutment,
22. . . Tapered part,
3. . . housing,
32. . . Inclined receiving surface,
4,6. . . Detection element,

Claims

In an oxygen concentration detector comprising a cylindrical housing and a detection element inserted and arranged in the housing via a cylindrical insulator,
The space formed by the detection element, the insulator and the housing is filled with powder under pressure,
The detection element has a flange portion, the flange portion, together are supported on the insulator, in the above flange portion acts axial force from the pressure-filled powder Yes,
The insulator includes a tapered portion supported by an inclined receiving surface provided in the housing, a receiving surface for receiving the brim portion of the detection element, and an upper end surface on which the powder is pressurized. And, the inner peripheral portion of the tapered portion is located further inward than the upper end surface,
The force P4 in the axial direction and the force P1 in the direction perpendicular to the axial direction act on the receiving surface of the insulator from the flange portion, and the upper end surface of the insulator is filled with the pressure. A force P6 in the axial direction and a force P3 in the direction perpendicular to the axial direction are acting from the powder,
An outer peripheral portion of the tapered portion of the insulator has a contact portion that comes into contact with the inclined receiving surface of the housing, and the contact portion has a force P5 in the axial direction from the inclined receiving surface of the housing. And a force P2 in a direction orthogonal to the axis direction is acting,
The P5 is balanced with the resultant force of the P6 and the P4, and has an action point on the contact portion of the outer peripheral portion of the tapered portion.
The insulator, the oxygen concentration sensor, characterized in that it is supported on the inclined receiving surface of the housing only through the contact portion.

2. The oxygen concentration detector according to claim 1, wherein the upper end surface of the insulator is a plane substantially orthogonal to an axial direction.

2. The oxygen concentration detector according to claim 1, wherein the upper end surface of the cylindrical wall of the insulator is symmetric when viewed in a cross section in the axial direction of the insulator.

The oxygen concentration detector according to any one of claims 1 to 3, wherein the detection element is supported on an inclined receiving surface of the insulator via a packing.

The oxygen concentration detector according to any one of claims 1 to 4, wherein the contact portion has a curved surface.

The oxygen concentration detector according to claim 1, wherein the contact portion has a protrusion.

The oxygen concentration detector according to any one of claims 1 to 6, wherein the inclined receiving surface of the housing has a protruding portion that comes into contact with the contact portion.