JP4177931B2

JP4177931B2 - Oxygen sensor

Info

Publication number: JP4177931B2
Application number: JP12312399A
Authority: JP
Inventors: 康司松尾; 聡石川
Original assignee: NGK Spark Plug Co Ltd
Current assignee: NGK Spark Plug Co Ltd
Priority date: 1999-04-28
Filing date: 1999-04-28
Publication date: 2008-11-05
Anticipated expiration: 2019-04-28
Also published as: JP2000314716A

Description

【０００１】
【発明の属する技術分野】
この発明は、例えば内燃機関の排気ガスなど、被測定ガス中の酸素を検出するための酸素センサに関する。
【０００２】
【従来の技術】
このような酸素センサの一形態として、先端部が閉じた中空軸状をなし、内外面にそれぞれ電極層を有する酸素検出素子を備えたものが知られている。近年は自動車産業の隆盛に伴い酸素センサに対する需要も増え、かつ価格低下に対する要望も年々強まりつつある。酸素センサは、自動車用電装部品の中でも部品点数が多く、組立工程の簡略化を如何にして図るかが製造コスト削減の重要な鍵を握っている。そのためには、組立工程の自動化など生産設備側の技術改良も必要であるが、工数削減に有利なセンサ構造を工夫することも重要である。
【０００３】
【発明が解決しようする課題】
例えば、上記タイプの酸素センサにおいては、酸素検出素子の内部電極層及び外部電極層に第一接続金具（内部電極接続金具）及び第二接続金具（外部電極接続金具）がそれぞれ電気的に接続され、両接続金具は酸素検出素子の後方（酸素検出素子の軸方向において先端部とは反対方向）に位置するセラミックセパレータの収容孔へと導かれる。両接続金具を収容孔の第一収容部（内部電極接続金具収容部）及び第二収容部（外部電極接続金具収容部）にそれぞれ前方側（酸素検出素子の軸方向先端部側）から後方側へ挿入して保持するとともに、コネクタを介してそれぞれのリード線に電気的に接続され、出力を取り出すようにしている。
【０００４】
しかし、このような酸素センサでは、上記した組み付け時に両接続金具が各々の収容部からはみ出して互いに接触し、又は他の電気配線等（例えば発熱体の端子部やリード線）に接触しショートしやすい問題があった。また、内燃機関の運転中（例えば自動車の走行中）においても、振動による金具飛び出し及びショートの問題や、繰り返し振動による両接続金具の断線の問題があった。
【０００５】
本発明の課題は、組み付け時及び運転中における両接続金具のショートや断線を防止するセンサ構造を提供することにある。
【０００６】
【課題を解決するための手段及び作用・効果】
上記課題を解決するために、本発明の酸素センサは、
先端部が閉じた中空軸状をなし、内面及び外面にそれぞれ内部電極層及び外部電極層が形成された酸素検出素子と、
該酸素検出素子の後方に配置されるとともに、内部電極層及び外部電極層にそれぞれ電気的に接続される第一接続金具及び第二接続金具をそれぞれ、自身の軸線方向において前方側から後方側へ挿入して保持する第一収容部及び第二収容部と、該両収容部の間に位置して両者を連通する中央連通部とを有する収容孔が形成されたセラミックセパレータとを備え、
両収容部はそれぞれ、中央連通部に面する開口部を有し、該中央連通部とは反対側の奥行き方向に向かって開口部よりも広幅となる横断面形状の隔壁で囲まれた空間として形成され、
両接続金具のうちの少なくとも一方は、開口部より広い幅を有する引出し線部と、該引出し線部から奥行き方向に向けて突設された突出部とを有することを特徴とする。
【０００７】
上記本発明によれば、例えば、引出し線部の左右側縁及び突出部が隔壁内面に接することで、接続金具の引出し線部がその左右側縁及び突出部の計３点で確実に対応する収容部内に保持されるので、組み付け時に接続金具が収容部からはみ出して互いに又は他の電気配線等に接触しショートする不具合が生じにくくなる。また、接触防止のための絶縁被覆も省略でき、部品点数の削減にも貢献する。また、運転中の振動による収容部からの飛び出しに伴うショートも起こりにくくなり、繰り返し振動によって接続金具が断線する不具合も防止ないし抑制できる。
【０００８】
突出部は、収容部内にて圧縮変形することにより、引出し線部の左右側縁を隔壁内面に押しつける向きに弾性的に付勢するものとすることができる。突出部の弾性付勢力により、収容部内にて引出し線部がより安定に保持される。
【０００９】
隔壁は、中央連通部に面する幅狭の開口部と、該中央連通部とは反対側に位置する幅広の底部と、該底部と開口部とを各々その幅方向両側にて連設する傾斜部とから形成されたものとすることができる。引出し線部の左右縁を、対応する傾斜部に当接させる形にて、これをより安定的に保持させることができる。この場合、セラミックセパレータの軸断面において上記収容部は、奥行方向における最大寸法をＤとし、同じくこれと直交する向きにおける最大幅寸法をＷ2として、Ｗ2＞Ｄとすることができる。奥行き寸法よりも幅方向寸法を広くすることで、引出し線部を一層安定的に保持できる他、収容部の奥行方向寸法に対する引出し線部の幅も大きくできるので、開口部からの引出し線部の飛び出し等も一層効果的に防止できる。また、突出部を圧縮弾性変形させる場合には、奥行方向寸法が短くなる分だけ、その弾性変形量を稼ぎやすくなり、収容部内における引出し線部の保持安定性が一層向上する。
【００１０】
次に、引出し線部の左右側縁のうち少なくとも一方を、後方側から前方側へ次第に幅広となる傾斜側縁に形成することができる。これにより、両接続金具の組み付け時に引っかかりが生じにくくなり、スムーズに各々の収容部に挿入できる。また、運転中のねじれの発生も防止することができる。
【００１１】
突出部は、基端部から所定の方向に延び、方向転換部を経て他方の端に至る切目が引出し線部に設けられ、該切目の内側に位置する舌片を奥行き方向に引き起こして形成することができる。この構成によれば、簡単な構造でありながら弾性変形可能な突出部を容易に形成でき、該突出部への弾性付与により引出し線部を各々の収納部の隔壁へ確実に押し当てることができる。この場合、突出部は、軸線方向における後方側に引起こし支点を位置させ、舌片の該引き起こし支点よりも前方側に位置する部分を引起こして形成することができる。これによれば、収容部に軸線方向おいて前方側から後方側へ引出し線部を挿入して組み付ける際に、引き起こされた舌片が、収容部の挿入側となる開口端面縁に引っ掛かったりするトラブルが生じにくくなり、組立をスムースに行うことが可能となる。
【００１２】
【発明の実施の形態】
以下、本発明の実施の形態を図面に示す実施例に基づき説明する。
図１は本発明の酸素センサの内部構造を示し、図２は要部の拡大図である。酸素センサ１は、先端が閉じた中空軸状の固体電解質部材である酸素検出素子２と、酸素検出素子２の中空部２ａに挿入された発熱体３とを備える。酸素検出素子２は、ジルコニア等を主体とする酸素イオン伝導性固体電解質により中空に形成されている。また、この酸素検出素子２の中間部外側には、絶縁性セラミックから形成されたインシュレータ６、７及びタルクから形成されたセラミック粉末８を介して金属製のケーシング１０が設けられている。なお、以下の説明において、酸素検出素子２の軸方向先端部に向かう側（閉じている側）を「前方側」、これと反対方向に向かう側を「後方側」と称する。
【００１３】
ケーシング１０は、酸素センサ１を排気管等の取付部に取り付けるためのねじ部９ｂを有する主体金具９、その主体金具９の後方側開口部に内側が連通するように結合された主筒１４、主体金具９の前方側開口部を覆うように取り付けられたプロテクタ１１等を備える。本発明の酸素センサ１はねじ部９ｂより前方（図１の下方）が排気管等のエンジン内に位置し、それより後方（図１の上方）は外部の大気中に位置して使用される。図２に示すように、酸素検出素子２の外面及び中空部２ａの内面には、そのほぼ全面を覆うように、例えばＰｔあるいはＰｔ合金により多孔質に形成された外部電極層２ｂ及び内部電極層２ｃが設けられている。
【００１４】
主体金具９の後方側の開口部には、前述の主筒１４が絶縁体６との間にリング１５を介して加締められ、この主筒１４に筒状のフィルタアセンブリ１６が外側から嵌合・固定されている。このフィルタアセンブリ１６の後端側開口部はゴム等で構成されたグロメット１７で封止され、またこれに続いてさらに内方にセラミックセパレータ１８が設けられている。そして、それらセラミックセパレータ１８及びグロメット１７を貫通するように、酸素検出素子２用のリード線２０，２１及び発熱体３用のリード線（図示せず）が配置されている。
【００１５】
フィルタアセンブリ１６は、主筒１４（ケーシング１０）に対し後方外側からほぼ同軸的に連結される筒状形態をなすとともに、気体導入孔５２を有する第一フィルタ保持部５１と、同じく気体導入孔５５を有する第二フィルタ保持部との間で、撥水性フィルタ（例えばポリテトラフルオロエチレンの多孔質繊維構造体等）として構成された筒状のフィルタ５３を、フィルタ加締め部５６，５７において挟み付けて保持する構造を有している。一方、グロメット１７は、第一フィルタ保持部５１の後方側開口部に対しその内側に弾性的にはめ込まれ、各リード線２０，２１等を挿通するためのシール側リード線挿通孔９１を有するとともに、それらリード線２０，２１等の外面と第一フィルタ保持部５１の内面との間をシールする。図４は、フィルタアセンブリ１６の組立状態を示している。フィルタアセンブリ１６の第一フィルタ保持部５１は、セラミックセパレータ１８の後方側突出部分を第二部分６２の内側まで進入させてこれを覆うとともに、段付き部６０においてセパレータ側支持部７３に対し、主筒１４とは反対側から波形座金７４を介して当接するように配置される。他方、該第一フィルタ保持部５１の先端側、すなわち第一部分６１において主筒１４（ケーシング１０）に対し外側からこれに重なりを生じるように配置され、その重なり部には、第一フィルタ保持部５１を主筒１４に対し気密状態となるように連結するケーシング加締め部７６が形成されている。
【００１６】
次に、セラミックセパレータ１８には、各リード線２０，２１等を挿通するための複数のセパレータ側リード線挿通孔７２が軸方向に貫通して形成されており、その軸方向中間位置には、外周面から突出する形態でフランジ状のセパレータ側支持部７３が形成されている。そして、図２に示すように、セラミックセパレータ１８は、セパレータ側支持部７３よりも前方側に位置する部分を主筒１４の後端部内側に入り込ませ、セパレータ側支持部７３の前端面７３ａを主筒１４の後端面（主筒側支持部９０）に当接させることにより、セパレータ側支持部７３よりも後方側に位置する部分は主筒１４の外側に突出させた状態で配置される。
【００１７】
酸素検出素子２用の一方のリード線２０は、互いに一体に形成されたコネクタ２３ａ、引出し線部２３ｂ、金具本体部２３ａ及び発熱体把持部２３ｄからなる内部電極接続金具２３（第一接続金具）を経て前述の酸素検出素子２の内部電極層２ｃ（図２）と電気的に接続されている。一方、他方のリード線２１は、互いに一体に形成されたコネクタ３３ａ、引出し線部３３ｂ及び金具本体部３３ｃとを有する外部電極接続金具３３（第二接続金具）を経て、酸素検出素子２の外部電極層２ｂ（図２）と電気的に接続されている。酸素検出素子２は、その内側に配置された発熱体３で加熱することで活性化される。発熱体３は棒状のセラミックヒータであり、抵抗発熱線部（図示せず）を有する発熱部３ａが、＋極側及び−極側の発熱体端子部３ｂ、３ｂに接続されるリード線（図示せず）を経て通電されることにより、酸素検出素子２の先端部（検出部）を加熱する。
【００１８】
図３に示すように、内部電極接続金具２３は、先端側に形成された発熱体把持部２３ｄの内面で発熱体３の外面を把持するとともに、金具本体部２３ｃの外面と酸素検出素子２の内面との接触により内部電極接続金具２３及び発熱体３を軸方向に位置固定する役割を果たす。また引出し線部２３ｂの一端が金具本体部２３ｃの周方向の１ケ所に接続する形で一体化され、さらにその他端にコネクタ２３ａが一体化されている。
【００１９】
発熱体把持部２３ｄは、発熱体３の周囲を包囲するＣ字状の横断面形状を有している。そして、発熱体３を未挿入の状態では該発熱体３の外径よりは少し小さい内径を有し、発熱体３の挿入にともない弾性的に拡径してその摩擦力により発熱体３を把持する。
【００２０】
また、金具本体部２３ｃは、左右両側の縁に鋸刃状の接触部２３ｅがそれぞれ複数形成された板状部分を円筒状に曲げ加工することにより、発熱体３を包囲する形態で形成されている（すなわち、発熱体３が挿通される）。そして、金具本体部２３ｃの外周面及び接触部２３ｅと酸素検出素子２の中空部２ａの内壁面（内部電極層２ｃ内面）との間の摩擦力によって内部電極接続金具２３及び発熱体３を中空部２ａに対し軸線方向に位置決めする役割を果たすとともに、複数の接触部２３ｅの各先端部において内部電極層２ｃ内面と接触・導通するようになっている。
【００２１】
一方、外部電極接続金具３３は、円筒状の金具本体部３３ｃを有するとともに、引出し線部３３ｂの一端が金具本体部３３ｃの周方向の１ケ所に接続する形で一体化され、さらにその他端にコネクタ３３ａが一体化されている。他方、その中心軸線を挟んで引出し線部３３ｂの接続点と反対側には、軸線方向のスリット３３ｅが形成されている。このような金具本体部３３ｃの内側に、酸素検出素子２の後端部がこれを弾性的に押し広げる形で内側から挿入されている。具体的には、酸素検出素子２の外周面後端部には外部側出力取出部としての導電層２ｆが、周方向に沿って帯状に形成されている。外部電極層２ｂは、例えば無電解メッキ等により、酸素検出素子２の係合フランジ部２ｓよりも前端側の要部全面を覆うものとされている。他方、導電層２ｆは、例えば金属ペーストを用いたパターン形成・焼き付けにより形成されるもので、同様に形成される軸線方向の接続パターン層２ｄを介して外部電極層２ｂと電気的に接続されている。
【００２２】
なお、金具本体部３３ｃの酸素検出素子２挿入側の開口部には、例えばその周方向に沿って外向きに開く挿入ガイド部３３ｆを形成しておけば、挿入時の引っ掛かり等が生じにくく、一層スムーズな組付けが可能となる。また、同様の目的で、酸素検出素子２の開口部外縁に面取部２ｇを形成することもできる。
【００２３】
酸素センサ１において、セラミックセパレータ１８の後端面は、軸方向において気体導入孔５２よりも後方側に位置するとともに、グロメット１７とセラミックセパレータ１８との間には所定量の隙間９８が形成されている。また、第一フィルタ保持部５１の内周面とセラミックセパレータ１８の外周面との間にも隙間９２が形成されている。そして、気体導入孔５２からの気体は隙間９２内に供給され、さらにセパレータ側リード線挿通孔７２とリード線との間に形成された隙間Ｋを通ってケーシング１０内に導かれ、酸素検出素子２の内面（内部電極層２ｃ）に導入される。一方、酸素検出素子２の外面にはプロテクタ１１のガス透過口１２を介して導入された排気ガスが接触し、酸素検出素子２には、その内外面の酸素濃度差に応じて酸素濃淡電池起電力が生じる。そして、この酸素濃淡電池起電力を、排気ガス中の酸素濃度の検出信号として内外電極層２ｃ，２ｂ（図２）から接続金具２３、３３及びリード線２０、２１を介して取り出すことにより、排気ガス中の酸素濃度を検出できる。
【００２４】
図５にセラミックセパレータ１８の詳細を示す。セラミックセパレータ１８には、後端部側（図５（ｃ）上端側）から４つのリード線挿通孔７２が、中心軸線Ｏを中心とするピッチ円Ｐに沿って略９０°間隔で貫通されている。また、同図（ｃ）及び（ｄ）に示すように、セラミックセパレータ１８の軸線方向前端（図５では下端）から軸線方向に沿って全長のほぼ中央部（すなわちセパレータ側支持部７３の中間部）に位置する底面１８ｅまで、収容孔７２ａが形成されている。収容孔７２ａは、内部電極接続金具２３の引出し線部２３ｂ、外部電極接続金具３３の引出し線部３３ｂ、＋極側の発熱体端子部３ｂ、−極側の発熱体端子部３ｂ及び発熱体３がそれぞれ挿入される各収容部に隔壁１８ａで区分されている（隔壁１８ａ及び収容孔７２ａの詳細形状は図８で後述する）。引出し線部２３ｂ、３３ｂ及び発熱体端子部３ｂ、３ｂと電気的に接続された４本のリード線２０、２１等が各々のリード線挿通孔７２を経て後方へ引き出される。なお、底面１８ｅは四角柱状の立ち上がりの先端を形成し、周囲に面取りがされているが、これは、例えば次のような事情による。すなわち、セラミックセパレータ１８の焼成前の成形体を金型成形により製造する場合、収容孔７２ａとリード線挿通孔７２とは別体のマンドレルにより形成されることが多い。このとき、底面１８ｅの外周縁には、これらマンドレルの合わせ面が位置し、合わせ面の隙間に粉末が圧入されて成形体にバリが発生することがある。そこで、底面１８ｅの周囲に面取を施しておけば、仮にバリが発生しても、その破片等が底面１８ｅ上に付着して不要な突起等が形成される不具合を生じにくくすることができる。
【００２５】
そして、図５（ｂ）に示すように、外部電極接続金具３３の金具本体部３３ｃの後端縁は、セラミックセパレータ１８の収容孔７２ａの開口側端面（前端面）において、隔壁１８ａの前端面に当接している。一方、内部電極接続金具２３の金具本体部２３ｃの後端縁は、外部電極接続金具３３の金具本体部３３ｃ及びピッチ円Ｐよりも内側にて、隔壁１８ａの前端面に当接している。また、隣接するリード線挿通孔７２，７２の間に形成される隔壁１８ａは、各々ピッチ円Ｐよりも内側に張り出して形成されている。なお、発熱体３の後端部は、収容孔７２ａの前端側から軸心に沿って底面１８ｅ付近まで挿入されており、これにより酸素センサ１の全長が短くなり、センサ寸法のコンパクト化が実現されている。
【００２６】
図６に内部電極接続金具２３（第一接続金具）の詳細を示す。厚さｔの電導性薄板を同図（ｃ）の展開図に示すように打ち抜き、コネクタ２３ａ、引出し線部２３ｂ、金具本体部２３ｃ及び発熱体把持部２３ｄが一体の内部電極接続金具２３を形成する。金具本体部２３ｃは接触部２３ｅとともに酸素検出素子２の内壁面と摩擦力を生じるように円筒状に、発熱体把持部２３ｄは発熱体３の外径より少し小さい内径を有するＣ字状に、コネクタ２３ａは周辺部を起立状にそれぞれ曲げ加工される。
【００２７】
セラミックセパレータ１８の内部電極接続金具収容部７２ｂ（第一収容部）に挿入される引出し線部２３ｂは、コネクタ２３ａに連なる上部２３ｌ、金具本体部２３ｃに連なる下部２３ｎ及びその両者をつなぐ中央部２３ｍから構成され、次のような形状を有している。上部２３ｌから中央部２３ｍにかけては両側で緩やかに幅が広がる拡大縁部２３ｋ（傾斜側縁）が形成され、中央部２３ｍはその幅ｗが下方（前方）ほど広くなる傾斜縁部２３ｔ（傾斜側縁）をもち、中央部２３ｍと下部２３ｎとの間及び下部２３ｎと金具本体部２３ｃとの間には両側から幅が縮小する縮小縁部２３ｓ及び２３ｓ’がそれぞれ設けられている。さらに中央部２３ｍには、上部が開口し下方に方向転換部を有する（図では上向きコ字状）切目２３ｈ’が打ち抜きの際にあらかじめ中心線に沿い長さｌ、幅ｗ’にわたって設けられており、曲げ加工後金具本体部２３ｃの曲げ方向とは反対側へ切目２３ｈ’の舌片を開口上部中心に下部を角度θ1だけ引起こして突出部２３ｈを形成する。引出し線部２３ｂがセラミックセパレータ１８の内部電極接続金具収容部７２ｂに挿入されたとき、中央部２３ｍの左右の拡大縁部２３ｋ又は傾斜縁部２３ｔが接続金具収容部７２ｂを形成する隔壁１８ａの一部分に係合するとともに、突出部２３ｈの下端部が隔壁１８ａの他の部分に係合する（図８参照）。
【００２８】
図７に外部電極接続金具３３（第二接続金具）の詳細を示す。厚さｔの電導性薄板を同図（ｃ）の展開図に示すように打ち抜き、コネクタ３３ａ、引出し線部３３ｂ及び金具本体部３３ｃが一体の外部電極接続金具３３を形成する。金具本体部３３ｃは酸素検出素子２の後端部外径より少し小さい内径を有する円筒状に、コネクタ３３ａは周辺部を起立状にそれぞれ曲げ加工される。中心軸線を挟んで引出し線部３３ｂの接続点と反対側には、軸線方向のスリット３３ｅが形成される。金具本体部３３ｃの酸素検出素子２挿入側の開口部には、周方向に沿って挿入ガイド部３３ｆが外向きに開いて形成される。
【００２９】
セラミックセパレータ１８の外部電極接続金具収容部７２ｃ（第二収容部）に挿入される引出し線部３３ｂは、コネクタ３３ａに連なる上部３３ｌ、金具本体部３３ｃに連なる下部３３ｎ及びその両者をつなぐ中央部３３ｍから構成され、次のような形状を有している。上部３３ｌから中央部３３ｍにかけては両側で緩やかに幅が広がる拡大縁部３３ｋ（傾斜側縁）が形成され、中央部３３ｍはその幅ｗが下方（前方）ほど広くなる傾斜縁部３３ｔ（傾斜側縁）をもち、中央部３３ｍと下部３３ｎとの間には両側から幅が縮小する縮小縁部３３ｓが設けられている。さらに中央部３３ｍには、上部が開口し下方に方向転換部を有する（図では上向きコ字状）切目３３ｈ’が打ち抜きの際にあらかじめ中心線に沿い長さｌ、幅ｗ’にわたって設けられており、曲げ加工後の金具本体部３３ｃの曲げ方向とは反対側へ切目３３ｈ’の舌片を開口上部中心に下部を角度θ1だけ引起こして突出部３３ｈを形成する。引出し線部３３ｂがセラミックセパレータ１８の外部電極接続金具収容部７２ｃに挿入されたとき、中央部３３ｍの左右の拡大縁部３３ｋ又は傾斜縁部３３ｔが接続金具収容部７２ｃを形成する隔壁１８ａの一部分に係合するとともに、突出部３３ｈの下端部が隔壁１８ａの他の部分に係合する（図８参照）。なお、図７（ａ）で示されるように、外部電極接続金具３３の引出し線部３３ｂ及びコネクタ３３ａは金具本体部３３ｃの中心線に対して傾斜角θ2を有している。このように内部電極接続金具２３にはない傾斜角θ2を付与する理由は、セラミックセパレータ１８への挿入時に、外部電極接続金具３３の浮きを防止し、酸素検出素子２への挿入をよりスムーズなものとするためである。
【００３０】
図８は図２におけるＣ−Ｃ横断面図及びその拡大図で、収容孔７２ａと両接続金具２３、３３との位置関係を示す。セラミックセパレータ１８には軸方向に貫通して４つのセパレータ側リード線挿通孔７２が形成されているが、セラミックセパレータ１８の前半部においては収容孔７２ａと内部において重なり合っている。収容孔７２ａは、内部電極接続金具２３（第一接続金具）及び外部電極接続金具３３（第二接続金具）をそれぞれ前方側から後方側へ挿入して保持する内部電極接続金具収容部７２ｂ（第一収容部）及び外部電極接続金具収容部７２ｃ（第二収容部）と、＋極側及び−極側発熱体端子３ｂ、３ｂをそれぞれ前方側から後方側へ挿入して保持する発熱体端子収容部７２ｄ、７２ｄと、これら４つの収容部の間に位置して４者を連通する中央連通部７２ｅとから形成されている。両接続金具収容部７２ｂ、７２ｃ及び両発熱体端子収容部７２ｄ、７２ｄは互いに中央連通部７２ｅを挟んで向かい合う状態にありピッチ円Ｐに沿って略９０゜間隔で並ぶセパレータ側リード線挿通孔７２と同様の位置関係を有するとともに、前端部側からみて各収容部に対応する各挿通孔が重なり合う（含まれる）状態となっている。中央連通部７２ｅは図８の実施例の場合発熱体収容部を兼ねており、発熱体３が底面１８ｅの手前まで挿入され、酸素センサ１のコンパクト化に貢献している。
【００３１】
内部電極接続金具収容部７２ｂは、中央連通部７２ｅに面する幅狭の開口部１８ｄと、中央連通部７２ｅとは反対側の外周方向（奥行き方向）に広がる幅広の底部１８ｂと、開口部１８ｄから底部１８ｂへとその開口幅（壁間距離）を徐々に広くして両者を連設する傾斜部１８ｃとからなる隔壁１８ａで囲まれた空間として形成されている（図８（ｂ）参照）。内部電極接続金具収容部７２ｂは全体として、一部が中央連通部７２ｅに開口された貝殻状あるいはオムスビ状を呈しており、楕円にも近い形状を有している。その奥行方向最大寸法Ｄは、これと直交する幅方向最大寸法ｗ2よりも小さく設定されている。
【００３２】
内部電極接続金具収容部７２ｂに内部電極接続金具２３を挿入したとき、ちょうど引出し線部２３ｂが収容部７２ｂ内に留まることになる（図２参照）。このとき中央部２３ｍの幅ｗが開口部１８ｄの幅（最小幅）Ｗ1よりも大きく、また底部１８ｂの幅（最大幅）Ｗ2よりも小さいので、拡大縁部２３ｋ又は傾斜縁部２３ｔが隔壁１８ａの傾斜部１８ｃに接当して収容部７２ｂの前端部から後方側へ（紙面の手前から背後方向へ）移動する。収容部７２ｂの前端部で引出し線部２３ｂを挿入する際、引出し線部２３ｂから底部１８ｂへ向けて突設された突出部２３ｈが底部１８ｂの外周部分で押圧されることで反発力（バネ力）を生み、引出し線部２３ｂは拡大縁部２３ｋ又は傾斜縁部２３ｔの両側縁と突出部２３ｈの下縁（前縁）の３点で確実に支持されるので、組み付け時に内部電極接続金具２３がその収容部７２ｂからはみ出して、外部電極接続金具３３やその他の電気配線等に接触しショートする不具合が生じにくくなる。また、接触防止のための絶縁被覆の必要もなくなる。さらに、運転中の振動による収容部７２ｂからの飛び出しに伴うショートも起こりにくくなり、繰り返し振動によって接続金具２３が断線する事も防止できる。
【００３３】
図８（ｂ）で、最大幅Ｗ2／最小幅Ｗ1＝１．６〜２．３、全奥行（最大奥行）Ｄ／有効奥行ｄ＝１．６〜２．２程度が望ましい。図示のようにＤ／ｄ＝２すなわちピッチ円近傍に引出し線部２３ｂが位置する状態であると接続金具２３からリード線２０への電気的接続に無理がかからず断線の恐れも少なくなる。ここまでは内部電極接続金具収容部７２ｂと内部電極接続金具２３についてのみ説明してきたが、外部電極接続金具収容部７２ｃと外部電極接続金具３３の関係についても同様であるから説明は省略する。ただし、図８（ａ）のようにすべて対称にする必要はなく、たとえば外部電極接続金具収容部７２ｃを発熱体端子収容部７２ｄのように少し角張った断面形状にしたり、外部電極接続金具３３の引出し線部３３ｂ及び突出部３３ｈを、内部電極接続金具２３の引出し線部２３ｂ及び突出部２３ｈとは異なる形状や大きさにしたりするなど、本発明の範囲内で適宜変更しても勿論差し支えない。このような変更を加えたときは結線ミスの未然防止にもなる。また発熱体端子収容部７２ｄ、７２ｄについては本発明を実施してもしなくてもよい。
【００３４】
以下、酸素センサ１の製造方法について説明する。まず、図９（ａ）に示すように、セラミックセパレータ１８に金属弾性部材７４を外挿する。そして、図４に示す如く予め組み立てておいたフィルタアセンブリ１６の前方側にセラミックセパレータ１８、内部電極接続金具２３、外部電極接続金具３３及び発熱体３等を、後方側にグロメット１７等を組み付ける。このとき、両接続金具２３，３３のコネクタ２３ａ，３３ａに接続されたリード線２０、２１及び＋極側と−極側の発熱体端子部３ｂ、３ｂに接続されたリード線（図示せず）は、それぞれセラミックセパレータ１８のセパレータ側リード線挿通孔７２に挿通され、さらに第一フィルタ保持部５１の後端側開口部に嵌め込まれたグロメット１７のシール側リード線挿通孔９１を経て後方側に延出されている。セラミックセパレータ１８を前方側へ移動して、収容孔７２ａの前端部で引出し線部２３ｂ、３３ｂを挿入する際、引出し線部２３ｂ、３３ｂから隔壁１８ａ（底部１８ｂ）へ向けて突設された突出部２３ｈ、３３ｈが隔壁１８ａ（底部１８ｂ）の外周部分で押圧されることで反発力（バネ力）を生み、引出し線部２３ｂ、３３ｂは拡大縁部２３ｋ、３３ｋ又は傾斜縁部２３ｔ、３３ｔの両側縁と突出部２３ｈの下縁（前縁）の３点で確実に支持される。
【００３５】
続いて、図９（ｂ）に示すように、フィルタアセンブリ１６を、グロメット１７のシール側リード線挿通孔９１内にてリード線２０，２１等を滑らせながら、段部６０の内面がリング状の金属弾性部材７４に当たる位置まで移動させ、セラミックセパレータ１８の外側に被せる。例えば、リード線２０，２１等の束の上をフィルタアセンブリ１６を多少傾けて滑らせても、第一フィルタ保持部５１の開口部内縁とリード線２０，２１等との間にはゴム製のグロメット１７が介在しているので、開口縁にてリード線２０，２１等の外被が削られる心配がない。
【００３６】
この状態で、図９（ｃ）に示すように、防護カバー６４及び第一フィルタ保持部５１の第二部分６２の後端側重なり部を周方向に沿って内側のグロメット１７に向けて加締めることにより、グロメット加締部６７を形成する。他方、酸素検出素子２は主筒１４内に予め組み付けておく。
【００３７】
そして、図１０（ａ）に示すように、発熱体３を先端側から酸素検出素子２の中空部２ａ内に挿入し、フィルタアセンブリ１６の第一フィルタ保持部５１を主筒１４に被せ、セラミックセパレータ１８を酸素検出素子２の後端部に向けて軸線方向に接近させる。これにより、外部電極接続金具３３の金具本体部３３ｃと、内部電極接続金具２３の金具本体部２３ｃとが、酸素検出素子２の開口部に位置決めされた形となる。そして、その状態でセラミックセパレータ１８の前端面（図５の隔壁１８ａの下端面）に、両金具本体部３３ｃ、２３ｃの後端縁を当接させつつ、セラミックセパレータ１８を酸素検出素子２に向けて軸線方向にさらに接近させる。
【００３８】
これにより、図２に示すように、酸素検出素子２の後端部が金具本体部３３ｃの内側に相対的に押し込まれるとともに、金具本体部２３ｃは酸素検出素子２の内側に押し込まれる。このとき、両金具本体部３３ｃ，２３ｃの後端縁はセラミックセパレータ１８の前端面に当接しているので、軸線方向の押込力による引出し線部３３ｂ，２３ｂの挫屈といった不具合を生じることなく、スムーズな組立てが可能となっている。
【００３９】
そして、図１０（ｂ）において、第一フィルタ保持部５１と主筒１４とを軸線方向に加圧して金属弾性部材７４を圧縮変形させ、その状態で第一フィルタ保持部５１と主筒１４とにケーシング加締部７６を形成して両者を結合することにより組立てが終了する。
【００４０】
本発明に係る収容孔７２ａと両接続金具２３、３３との位置関係について次のような変更が考えられる。
▲１▼収容孔７２ａは、セラミックセパレータ１８の前半部においてのみ、軸方向に貫通して設けられている４つのセパレータ側リード線挿通孔７２と内部において重なり合う状態で形成された例を示したが、収容孔７２ａはセラミックセパレータ１８の軸方向（前後方向）全長にわたり形成されていてもよい。
▲２▼隔壁１８ａは、軸方向（前後方向）に傾斜を有していてもよい。このときの傾斜は後方側から前方側へ次第に拡大するものとし、引出し線部２３ｂ、３３ｂの拡大縁部２３ｋ、３３ｋ及び傾斜縁部２３ｔ、３３ｔと同じ向きである。隔壁１８ａの傾斜は、セラミックセパレータ１８製造の際の型抜きテーパをそのまま利用するか型抜きテーパの勾配を少し大きくして適用することができる。隔壁１８ａ又は引出し線部２３ｂ、３３ｂへ傾斜（直線状か曲線状かを問わない）を設けることにより、引出し線部１８ａの収容孔７２ａへの挿入がスムーズに行える。
▲３▼中央連通部７２ｅが発熱体収容部に兼用される例、及び収容孔７２ａに発熱体端子収容部７２ｄ、７２ｄが含まれる例を示したが、これらに限定されない（図１１（ａ）参照）。
▲４▼両接続金具収容部７２ｂ、７２ｃの形状は、貝殻状に限らず、直線で囲われた台形状、円形状、楕円状、その他の曲線状又はこれらの組み合わせでもよい。セラミックセパレータ１８を貫通するセパレータ側リード線挿通孔７２を前端部側においてほぼそのまま両接続金具収容部７２ｂ、７２ｃとして利用することも可能である（図１１（ａ）参照）。
▲５▼隔壁１８ａと引き出し線部２３ｂ、３３ｂとは点（線）接触よりも面接触にすれば、保持がより安定する（図１１（ｂ）参照）。
【００４１】
図１１は主な変更例を示す。図１１（ａ）では、セラミックセパレータ１８を貫通するセパレータ側リード線挿通孔７２を前端部側においてほぼ円形のまま両接続金具収容部７２ｂ、７２ｃとして利用するとともに、収容孔７２ａに発熱体端子収容部７２ｄ、７２ｄが含まれない例を示した。隔壁１８ａの肉厚を充分にとることができ強度・耐久性に優れる。図１１（ｂ）では、隔壁１８ａの傾斜部１８ｃの両側に幅Ｗ’、深さＤ’の浅い溝１８ｆ、１８ｆを設けるとともに、底部１８ｂにも幅Ｗ”、深さＤ”の浅い溝１８ｇを設けてある。引出し線部２３ｂ、３３ｂは溝１８ｆ、１８ｆを、突出部２３ｈ、３３ｈは溝１８ｇをそれぞれガイドとして収容部７２ｂ、７２ｃにがたつきなく挿入でき、保持力も大きい。なお、溝１８ｆと１８ｇはいずれか一方のみ設けてもよい。幅ｗの異なる引出し線部２３ｂ、３３ｂに対応するためには両側の溝１８ｆ、１８ｆをそれぞれ階段状に形成するとよい。幅ｗ’の異なる突出部２３ｈ、３３ｈに対応するためには溝１８ｇの幅Ｗ”を少し広めに取っておけばよい。
【００４２】
さらに本発明に係る引出し線部２３ｂ、３３ｂ及び突出部２３ｈ、３３ｈの形状についても次のような変更が考えられる。
▲１▼両接続金具２３、３３のうちいずれか一方にのみ本発明を適用すること、または引出し線部及び突出部の形状を互いに異ならせて適用することは可能である。
▲２▼引出し線部２３ｂ、３３ｂの傾斜縁部２３ｔ、３３ｔ及び拡大縁部２３ｋ、３３ｋはなくてもよく、あるいは左右のうち片側だけ設けてもよく、その形状も直線状、曲線状等を問わない。
▲３▼突出部２３ｈ、３３ｈの形状について、切目を用いずプレスや絞りで一体的に膨出部を設けたり、あるいは別体の突出部をハンダ付したりしてもよい（図１２（ｄ）参照）。
▲４▼突出部２３ｈ、３３ｈの引起こし形態について、多段折れや曲線（面）状折れ、左右方向への引起こし等も可能である（図１２（ａ）（ｂ）（ｃ）参照）。
▲５▼突出部２３ｈ、３３ｈの切目２３ｈ’、３３ｈ’について、コ字状以外にＵ字状等の変更が可能である。
【００４３】
図１２は主な変更例を示す。図１２（ａ）は、傾斜角θ1の第一突出部２３ｈ1と傾斜角θ1'の第二突出部２３ｈ1'を二段折れ状に設けたもので、第二突出部２３ｈ1'の接触面積がより広くなり、引出し線部２３ｂの保持が安定する。
同（ｂ）は、曲線状の突出部２３ｈ2を設けた例でバネ効果により保持力が増す。
同（ｃ）は、中心線上にＩ字状の切目を設け、２枚の矩形状舌片を左右に押し開いて突出部２３ｈ3とした例である。切目をＴ字状又は逆Ｔ字状とし、２枚の三角形状舌片を左右に押し開くようにしてもよい。また、切目をコ字状とし、左右いずれか一方に押し開いてもよい。同（ｄ）は、プレス等により突出部２３ｈ4を一体的に膨出させた例を示す。
【図面の簡単な説明】
【図１】本発明の酸素センサの縦断面図。
【図２】図１の酸素センサの要部を示す縦断面図。
【図３】セラミックセパレータへの組み付け状態を示す分解斜視図。
【図４】組立状態のフィルタアセンブリの部分縦断面図。
【図５】セラミックセパレータの平面図、底面図、Ａ−Ａ縦断面図及びＢ−Ｂ縦断面図。
【図６】内部電極接続金具の左側面図、正面図及び展開図。
【図７】外部電極接続金具の正面図、右側面図及び展開図。
【図８】図２におけるＣ−Ｃ横断面図及びその拡大図。
【図９】図１の酸素センサの組立方法の一例を示す工程説明図。
【図１０】図９に続く工程説明図。
【図１１】図８の変更例を示し、（ａ）は第１変更例のＣ−Ｃ横断面図、（ｂ）は第２変更例のＣ−Ｃ横断面拡大図。
【図１２】図６の突出部の変更例を示し、（ａ）は第１変更例の正面図、（ｂ）は第２変更例の正面図、（ｃ）は第３変更例の斜視図、（ｄ）は第４変更例の斜視図。
【符号の説明】
１酸素センサ
２酸素検出素子
２ａ中空部
２ｂ外部電極層
２ｃ内部電極層
１８セラミックセパレータ
１８ａ隔壁
１８ｂ底部
１８ｃ傾斜部
１８ｄ開口部
２３内部電極接続金具（第一接続金具）
２３ｂ引出し線部
２３ｈ突出部
２３ｈ’切目
２３ｔ傾斜縁部（傾斜側縁）
３３ｋ拡大縁部（傾斜側縁）
３３外部電極接続金具（第二接続金具）
３３ｂ引出し線部
３３ｈ突出部
３３ｈ’切目
３３ｔ傾斜縁部（傾斜側縁）
３３ｋ拡大縁部（傾斜側縁）
７２ａ収容孔
７２ｂ内部電極接続金具収容部（第一収容部）
７２ｃ外部電極接続金具収容部（第二収容部）
７２ｅ中央連通部
Ｄ収容部の最大奥行寸法
Ｗ2 収容部の最大幅寸法[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oxygen sensor for detecting oxygen in a gas to be measured such as an exhaust gas of an internal combustion engine.
[0002]
[Prior art]
As one form of such an oxygen sensor, a sensor having an oxygen detecting element having a hollow shaft shape with a closed tip and electrode layers on the inner and outer surfaces is known. In recent years, with the rise of the automobile industry, the demand for oxygen sensors has increased, and the demand for price reduction has been increasing year by year. The oxygen sensor has a large number of parts among electric parts for automobiles, and how to simplify the assembly process is an important key for reducing the manufacturing cost. To that end, it is necessary to improve the technology on the production equipment side, such as automation of the assembly process, but it is also important to devise a sensor structure that is advantageous for man-hour reduction.
[0003]
[Problems to be solved by the invention]
For example, in the above type of oxygen sensor, a first connection fitting (internal electrode connection fitting) and a second connection fitting (external electrode connection fitting) are electrically connected to the internal electrode layer and the external electrode layer of the oxygen detection element, respectively. Both the connection fittings are led to the ceramic separator housing hole located behind the oxygen detection element (in the direction opposite to the tip in the axial direction of the oxygen detection element). Both connection fittings are rearward from the front side (the front end side in the axial direction of the oxygen detection element) on the first accommodation portion (internal electrode connection fitting accommodation portion) and the second accommodation portion (external electrode connection fitting accommodation portion) of the accommodation hole, respectively. Are inserted and held, and are electrically connected to respective lead wires via connectors to take out outputs.
[0004]
However, in such an oxygen sensor, when the above-described assembly is performed, both connection fittings protrude from the respective accommodating portions and come into contact with each other, or contact with other electric wirings (for example, terminal portions and lead wires of the heating element) to cause a short circuit. There was an easy problem. Further, even during the operation of the internal combustion engine (for example, while a car is running), there are problems of metal protrusion and short circuit due to vibration, and disconnection of both connection metal parts due to repeated vibration.
[0005]
The subject of this invention is providing the sensor structure which prevents the short circuit and disconnection of both connection metal fittings at the time of an assembly | attachment and driving | operation.
[0006]
[Means for solving the problems and actions / effects]
In order to solve the above problems, the oxygen sensor of the present invention is
An oxygen detection element having a hollow shaft shape with a closed tip, and an inner electrode layer and an outer electrode layer formed on the inner surface and the outer surface, respectively,
A first connection fitting and a second connection fitting that are arranged behind the oxygen detection element and are electrically connected to the internal electrode layer and the external electrode layer, respectively, from the front side to the rear side in the direction of their own axes. A ceramic separator in which a housing hole having a first housing portion and a second housing portion to be inserted and held, and a central communication portion located between the two housing portions and communicating with each other is formed;
Each of the housing portions has an opening facing the central communication portion, and is a space surrounded by a partition wall having a cross-sectional shape that is wider than the opening portion in the depth direction opposite to the central communication portion. Formed,
At least one of the connection fittings is characterized by having a lead line portion having a width wider than the opening and a projecting portion projecting from the lead line portion in the depth direction.
[0007]
According to the present invention described above, for example, the left and right side edges and the projecting part of the lead line part are in contact with the inner surface of the partition wall, so that the lead line part of the connecting metal can reliably correspond to the left and right side edges and the projecting part. Since it is held in the housing portion, it is difficult to cause a problem that the connection fitting protrudes from the housing portion during assembly and contacts with each other or other electric wirings to cause a short circuit. In addition, the insulation coating for preventing contact can be omitted, which contributes to the reduction of the number of parts. In addition, short-circuiting due to jumping out of the housing due to vibration during operation is less likely to occur, and the problem of disconnection of the connection fitting due to repeated vibration can be prevented or suppressed.
[0008]
The projecting portion can be elastically biased in a direction in which the left and right side edges of the lead wire portion are pressed against the inner surface of the partition wall by compressing and deforming in the housing portion. Due to the elastic biasing force of the protruding portion, the lead wire portion is more stably held in the accommodating portion.
[0009]
The partition wall includes a narrow opening facing the central communication part, a wide bottom located on the opposite side of the central communication part, and an inclination that connects the bottom part and the opening on both sides in the width direction. It can be formed from the part. This can be more stably held in such a manner that the left and right edges of the lead-out line part are brought into contact with the corresponding inclined part. In this case, in the axial cross section of the ceramic separator, the housing portion can satisfy W2> D, where D is the maximum dimension in the depth direction and W2 is the maximum width dimension in the direction orthogonal thereto. By making the width direction dimension wider than the depth dimension, the leader line part can be held more stably, and the width of the leader line part with respect to the depth direction dimension of the housing part can be increased, so that the leader line part from the opening part Jumping out can be prevented more effectively. Moreover, when compressing elastically deforming a protrusion part, it becomes easy to earn the elastic deformation amount to the extent that the depth direction dimension becomes short, and the holding | maintenance stability of the leader line part in an accommodating part improves further.
[0010]
Next, at least one of the left and right side edges of the leader line portion can be formed on an inclined side edge that gradually becomes wider from the rear side to the front side. Thereby, it becomes difficult to generate | occur | produce a catch at the time of the assembly | attachment of both connection metal fittings, and it can insert in each accommodating part smoothly. In addition, the occurrence of twist during operation can be prevented.
[0011]
The projecting portion extends in a predetermined direction from the base end portion, and a cut line extending from the direction changing portion to the other end is provided in the lead-out line portion, and a tongue piece positioned inside the cut is formed in the depth direction. be able to. According to this configuration, it is possible to easily form an elastically deformable protruding portion with a simple structure, and by reliably applying elasticity to the protruding portion, the lead wire portion can be reliably pressed against the partition wall of each storage portion. . In this case, the protruding portion can be formed by raising the fulcrum on the rear side in the axial direction and raising the portion of the tongue piece located on the front side of the raising fulcrum. According to this, when the lead wire portion is inserted and assembled from the front side to the rear side in the axial direction in the housing portion, the raised tongue piece is caught on the opening end surface edge on the insertion side of the housing portion. Troubles are less likely to occur and assembly can be performed smoothly.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples shown in the drawings.
FIG. 1 shows the internal structure of the oxygen sensor of the present invention, and FIG. 2 is an enlarged view of the main part. The oxygen sensor 1 includes an oxygen detection element 2 that is a hollow shaft-shaped solid electrolyte member with a closed tip, and a heating element 3 inserted into the hollow portion 2 a of the oxygen detection element 2. The oxygen detection element 2 is formed hollow with an oxygen ion conductive solid electrolyte mainly composed of zirconia or the like. Further, a metal casing 10 is provided outside the intermediate portion of the oxygen detecting element 2 via insulators 6 and 7 made of insulating ceramic and ceramic powder 8 made of talc. In the following description, the side (closed side) toward the tip end in the axial direction of the oxygen detection element 2 is referred to as “front side”, and the side toward the opposite direction is referred to as “rear side”.
[0013]
The casing 10 includes a metal shell 9 having a threaded portion 9b for attaching the oxygen sensor 1 to an attachment portion such as an exhaust pipe, and a main cylinder 14 coupled so that the inside communicates with a rear side opening of the metal shell 9. The protector 11 etc. which were attached so that the front side opening part of the metal shell 9 may be covered are provided. The oxygen sensor 1 of the present invention is used in such a manner that the front side (lower side in FIG. 1) of the screw portion 9b is located in the engine such as an exhaust pipe, and the rear side (upper side in FIG. 1) is located in the outside atmosphere. . As shown in FIG. 2, an outer electrode layer 2b and an inner electrode layer are formed on the outer surface of the oxygen detecting element 2 and the inner surface of the hollow portion 2a so as to cover almost the entire surface, for example, by Pt or a Pt alloy. 2c is provided.
[0014]
In the opening on the rear side of the metal shell 9, the aforementioned main cylinder 14 is crimped via a ring 15 between the insulator 6 and a cylindrical filter assembly 16 is fitted to the main cylinder 14 from the outside.・ It is fixed. The opening on the rear end side of the filter assembly 16 is sealed with a grommet 17 made of rubber or the like, and a ceramic separator 18 is further provided inward. Then, lead wires 20 and 21 for the oxygen detection element 2 and lead wires (not shown) for the heating element 3 are arranged so as to penetrate the ceramic separator 18 and the grommet 17.
[0015]
The filter assembly 16 has a cylindrical shape that is substantially coaxially connected to the main cylinder 14 (casing 10) from the rear outer side, the first filter holding part 51 having the gas introduction hole 52, and the gas introduction hole 55. A cylindrical filter 53 configured as a water repellent filter (for example, a polytetrafluoroethylene porous fiber structure) is sandwiched between the second filter holding portions having the filter crimping portions 56 and 57. Structure. On the other hand, the grommet 17 is elastically fitted inside the rear opening of the first filter holding portion 51 and has a seal-side lead wire insertion hole 91 for inserting each lead wire 20, 21 and the like. The space between the outer surfaces of the lead wires 20 and 21 and the inner surface of the first filter holding portion 51 is sealed. FIG. 4 shows the assembled state of the filter assembly 16. The first filter holding portion 51 of the filter assembly 16 allows the rear-side protruding portion of the ceramic separator 18 to enter and cover the inside of the second portion 62, and at the stepped portion 60 to the separator-side support portion 73. It arrange | positions so that it may contact | abut via the corrugated washer 74 from the opposite side to the pipe | tube 14. FIG. On the other hand, the first filter holding part 51 is arranged so as to overlap the main cylinder 14 (casing 10) from the outside at the front end side of the first filter 61, that is, the first part 61. A casing caulking portion 76 that connects 51 to the main cylinder 14 so as to be in an airtight state is formed.
[0016]
Next, the ceramic separator 18 is formed with a plurality of separator-side lead wire insertion holes 72 through which the lead wires 20, 21 and the like are inserted in the axial direction. A flange-like separator-side support portion 73 is formed so as to protrude from the outer peripheral surface. Then, as shown in FIG. 2, the ceramic separator 18 has a portion located on the front side of the separator-side support portion 73 inserted inside the rear end portion of the main cylinder 14, and the front end surface 73 a of the separator-side support portion 73 is formed. By contacting the rear end surface of the main cylinder 14 (main cylinder side support part 90), the portion located on the rear side of the separator side support part 73 is arranged in a state of protruding to the outside of the main cylinder 14.
[0017]
One lead wire 20 for the oxygen detection element 2 has an internal electrode connection fitting 23 (first connection fitting) comprising a connector 23a, a lead wire portion 23b, a metal fitting main body portion 23a, and a heating element gripping portion 23d formed integrally with each other. Then, it is electrically connected to the internal electrode layer 2c (FIG. 2) of the oxygen detecting element 2 described above. On the other hand, the other lead wire 21 is connected to the outside of the oxygen detection element 2 through an external electrode connection fitting 33 (second connection fitting) having a connector 33a, a lead wire portion 33b, and a fitting main body portion 33c formed integrally with each other. The electrode layer 2b (FIG. 2) is electrically connected. The oxygen detection element 2 is activated by heating with the heating element 3 disposed inside thereof. The heating element 3 is a rod-shaped ceramic heater, and a heating wire 3a having a resistance heating wire part (not shown) is connected to the + pole side and-pole side heating element terminal parts 3b and 3b (see FIG. The tip part (detection part) of the oxygen detection element 2 is heated by being energized through (not shown).
[0018]
As shown in FIG. 3, the internal electrode connection fitting 23 holds the outer surface of the heating element 3 with the inner surface of the heating element holding portion 23 d formed on the distal end side, and the outer surface of the fitting main body portion 23 c and the oxygen detection element 2. It plays a role of fixing the position of the internal electrode fitting 23 and the heating element 3 in the axial direction by contact with the inner surface. Further, one end of the lead wire portion 23b is integrated so as to be connected to one place in the circumferential direction of the metal fitting main body portion 23c, and the connector 23a is further integrated at the other end.
[0019]
The heating element gripping portion 23d has a C-shaped cross-sectional shape that surrounds the periphery of the heating element 3. When the heating element 3 is not inserted, the heating element 3 has an inner diameter slightly smaller than the outer diameter of the heating element 3 and elastically expands as the heating element 3 is inserted, and grips the heating element 3 by its frictional force. To do.
[0020]
Further, the metal fitting main body portion 23c is formed in a form surrounding the heating element 3 by bending a plate-like portion in which a plurality of saw blade-like contact portions 23e are formed on both left and right edges into a cylindrical shape. (That is, the heating element 3 is inserted). Then, the internal electrode connection fitting 23 and the heating element 3 are hollowed by the frictional force between the outer peripheral surface of the metal fitting main body 23c and the contact portion 23e and the inner wall surface (inner surface of the internal electrode layer 2c) of the hollow portion 2a of the oxygen detection element 2. It plays the role of positioning in the axial direction with respect to the portion 2a, and is in contact with and electrically connected to the inner surface of the internal electrode layer 2c at each tip portion of the plurality of contact portions 23e.
[0021]
On the other hand, the external electrode connection fitting 33 has a cylindrical fitting main body portion 33c and is integrated in such a manner that one end of the lead wire portion 33b is connected to one place in the circumferential direction of the fitting main body portion 33c, and further to the other end. The connector 33a is integrated. On the other hand, an axial slit 33e is formed on the side opposite to the connection point of the lead line portion 33b across the central axis. The rear end portion of the oxygen detection element 2 is inserted into the metal fitting main body portion 33c from the inside in such a manner as to elastically push it. Specifically, a conductive layer 2 f as an external output extraction portion is formed in a strip shape along the circumferential direction at the rear end portion of the outer peripheral surface of the oxygen detection element 2. The external electrode layer 2b covers the entire surface of the main part on the front end side of the engagement flange portion 2s of the oxygen detection element 2 by, for example, electroless plating. On the other hand, the conductive layer 2f is formed, for example, by pattern formation / baking using a metal paste, and is electrically connected to the external electrode layer 2b via the axially formed connection pattern layer 2d. Yes.
[0022]
In addition, if an insertion guide portion 33f that opens outward along the circumferential direction is formed in the opening portion of the metal fitting main body portion 33c on the oxygen detection element 2 insertion side, for example, a hook at the time of insertion hardly occurs, Smoother assembly becomes possible. For the same purpose, the chamfered portion 2g can be formed on the outer edge of the opening of the oxygen detecting element 2.
[0023]
In the oxygen sensor 1, the rear end surface of the ceramic separator 18 is positioned behind the gas introduction hole 52 in the axial direction, and a predetermined amount of gap 98 is formed between the grommet 17 and the ceramic separator 18. . A gap 92 is also formed between the inner peripheral surface of the first filter holding part 51 and the outer peripheral surface of the ceramic separator 18. Then, the gas from the gas introduction hole 52 is supplied into the gap 92, and further introduced into the casing 10 through the gap K formed between the separator-side lead wire insertion hole 72 and the lead wire, and the oxygen detection element. 2 is introduced into the inner surface of 2 (internal electrode layer 2c). On the other hand, the exhaust gas introduced through the gas permeation port 12 of the protector 11 is in contact with the outer surface of the oxygen detection element 2, and the oxygen concentration cell is activated in accordance with the oxygen concentration difference between the inner and outer surfaces of the oxygen detection element 2. Electric power is generated. Then, the oxygen concentration cell electromotive force is extracted from the inner and outer electrode layers 2c and 2b (FIG. 2) through the connection fittings 23 and 33 and the lead wires 20 and 21 as an oxygen concentration detection signal in the exhaust gas. The oxygen concentration in the gas can be detected.
[0024]
FIG. 5 shows details of the ceramic separator 18. In the ceramic separator 18, four lead wire insertion holes 72 from the rear end side (the upper end side in FIG. 5C) are penetrated along the pitch circle P centered on the central axis O at approximately 90 ° intervals. Yes. Further, as shown in FIGS. 3C and 3D, the central portion of the ceramic separator 18 is almost centered along the axial direction from the front end in the axial direction (the lower end in FIG. 5) (that is, the intermediate portion of the separator-side support portion 73). The housing hole 72a is formed up to the bottom surface 18e located at (1). The housing hole 72a includes the lead wire portion 23b of the internal electrode connection fitting 23, the lead wire portion 33b of the external electrode connection fitting 33, the positive electrode side heating element terminal portion 3b, the negative electrode side heating element terminal portion 3b, and the heating element 3. Are partitioned by partition walls 18a (detailed shapes of the partition walls 18a and the storage holes 72a will be described later with reference to FIG. 8). The four lead wires 20, 21 and the like electrically connected to the lead wire portions 23b, 33b and the heating element terminal portions 3b, 3b are drawn out rearward through the lead wire insertion holes 72. Note that the bottom surface 18e forms a square columnar rising tip and is chamfered around, for example, due to the following circumstances. That is, when the molded body before firing of the ceramic separator 18 is manufactured by die molding, the accommodation hole 72a and the lead wire insertion hole 72 are often formed by separate mandrels. At this time, the mating surfaces of these mandrels are located on the outer peripheral edge of the bottom surface 18e, and powder may be press-fitted into the gap between the mating surfaces to generate burrs in the molded body. Therefore, if chamfering is performed around the bottom surface 18e, even if burrs are generated, it is possible to make it difficult to cause a problem that fragments or the like adhere to the bottom surface 18e to form unnecessary protrusions. .
[0025]
As shown in FIG. 5B, the rear end edge of the metal body 33c of the external electrode connection metal 33 is the front end surface of the partition wall 18a at the opening side end surface (front end surface) of the accommodating hole 72a of the ceramic separator 18. Abut. On the other hand, the rear end edge of the metal body portion 23c of the internal electrode connection fitting 23 is in contact with the front end surface of the partition wall 18a inside the metal fitting body portion 33c and the pitch circle P of the external electrode connection fitting 33. Further, the partition walls 18 a formed between the adjacent lead wire insertion holes 72, 72 are formed so as to protrude inward from the pitch circle P. The rear end portion of the heating element 3 is inserted from the front end side of the accommodation hole 72a to the vicinity of the bottom surface 18e along the axis, thereby reducing the overall length of the oxygen sensor 1 and realizing a compact sensor size. Has been.
[0026]
FIG. 6 shows details of the internal electrode connection fitting 23 (first connection fitting). A conductive thin plate having a thickness t is punched out as shown in the developed view of FIG. 4C, and the connector 23a, the lead wire portion 23b, the metal fitting main body portion 23c, and the heating element holding portion 23d form an integrated internal electrode connecting metal fitting 23. To do. The metal fitting main body portion 23c is cylindrical so as to generate frictional force with the inner wall surface of the oxygen detecting element 2 together with the contact portion 23e, and the heating element gripping portion 23d is C-shaped having an inner diameter slightly smaller than the outer diameter of the heating element 3. The connectors 23a are each bent at an upright position.
[0027]
The lead wire portion 23b inserted into the internal electrode connection fitting housing portion 72b (first housing portion) of the ceramic separator 18 has an upper portion 23l connected to the connector 23a, a lower portion 23n connected to the metal fitting main body portion 23c, and a central portion 23m connecting them. And has the following shape. From the upper part 23l to the central part 23m, an enlarged edge part 23k (inclined side edge) is formed which gradually increases in width on both sides, and the central part 23m has an inclined edge part 23t (inclined side) whose width w increases downward (forward). Reducing edge portions 23 s and 23 s ′ whose width is reduced from both sides are provided between the central portion 23 m and the lower portion 23 n and between the lower portion 23 n and the metal fitting main body portion 23 c. Further, in the central portion 23m, an incision 23h 'having an upper opening and a lower direction change portion (upward U-shaped in the figure) is provided in advance over the length l and width w' along the center line at the time of punching. After bending, the protruding portion 23h is formed by raising the tongue of the cut 23h 'to the opposite side of the bending direction of the metal fitting main body portion 23c with the opening θ being the center of the upper portion of the opening and the angle θ1. When the lead wire portion 23b is inserted into the internal electrode connection fitting housing portion 72b of the ceramic separator 18, the left and right enlarged edge portions 23k or the inclined edge portions 23t of the central portion 23m form a part of the partition wall 18a that forms the connection fitting housing portion 72b. And the lower end of the protrusion 23h engages with the other part of the partition wall 18a (see FIG. 8).
[0028]
FIG. 7 shows details of the external electrode connection fitting 33 (second connection fitting). The conductive thin plate having a thickness t is punched out as shown in the development view of FIG. 4C, and the connector 33a, the lead wire portion 33b, and the metal fitting main body portion 33c form an integrated external electrode connection fitting 33. The metal fitting main body 33c is bent into a cylindrical shape having an inner diameter slightly smaller than the outer diameter of the rear end portion of the oxygen detecting element 2, and the connector 33a is bent in a standing manner at the periphery. An axial slit 33e is formed on the side opposite to the connection point of the lead line portion 33b across the central axis. An insertion guide portion 33f is formed to open outward along the circumferential direction in the opening of the metal fitting main body portion 33c on the oxygen detection element 2 insertion side.
[0029]
The lead wire portion 33b inserted into the external electrode connecting metal fitting housing portion 72c (second housing portion) of the ceramic separator 18 has an upper portion 33l continuous with the connector 33a, a lower portion 33n continuous with the metal fitting main body portion 33c, and a central portion 33m connecting both of them. And has the following shape. From the upper part 33l to the central part 33m, an enlarged edge part 33k (inclined side edge) is formed which gradually increases in width on both sides, and the central part 33m has an inclined edge part 33t (inclined side) whose width w increases downward (forward). A reduced edge portion 33s having a width from both sides is provided between the central portion 33m and the lower portion 33n. Further, the central portion 33m is provided with a notch 33h ′ having an opening at the top and a direction changing portion at the bottom (upwardly U-shaped in the drawing) along the center line for a length l and a width w ′ at the time of punching. Then, the protruding portion 33h is formed by raising the tongue piece of the notch 33h 'to the opposite side of the bending direction of the metal fitting main body portion 33c after bending, and lowering the lower portion by an angle θ1 at the center of the upper portion of the opening. When the lead wire portion 33b is inserted into the external electrode connection fitting housing portion 72c of the ceramic separator 18, the left and right enlarged edge portions 33k or the inclined edge portions 33t of the central portion 33m form a part of the partition wall 18a that forms the connection fitting housing portion 72c. And the lower end of the protrusion 33h engages with the other part of the partition wall 18a (see FIG. 8). As shown in FIG. 7A, the lead wire portion 33b and the connector 33a of the external electrode connection fitting 33 have an inclination angle θ2 with respect to the center line of the fitting main body portion 33c. As described above, the reason why the inclination angle θ2 is not provided in the internal electrode connection fitting 23 is that the external electrode connection fitting 33 is prevented from floating when inserted into the ceramic separator 18 and the insertion into the oxygen detection element 2 is smoother. This is for the purpose.
[0030]
FIG. 8 is a cross-sectional view taken along the line CC in FIG. 2 and an enlarged view thereof, and shows the positional relationship between the receiving hole 72a and the connection fittings 23 and 33. Four separator-side lead wire insertion holes 72 are formed in the ceramic separator 18 so as to penetrate in the axial direction. However, in the front half of the ceramic separator 18, the ceramic separator 18 overlaps the accommodation hole 72 a inside. The accommodation hole 72a is an internal electrode connection fitting housing portion 72b (first fitting) for inserting and holding the internal electrode connection fitting 23 (first connection fitting) and the external electrode connection fitting 33 (second connection fitting) from the front side to the rear side. 1 housing portion) and external electrode connection fitting housing portion 72c (second housing portion), and heating element terminal housing for inserting and holding the positive electrode side and the negative electrode heating element terminals 3b and 3b from the front side to the rear side, respectively. It is formed from the part 72d and 72d, and the center communication part 72e which is located between these four accommodating parts and connects 4 persons. Both connecting metal fitting housing parts 72b and 72c and both heating element terminal housing parts 72d and 72d are in a state of facing each other across the central communication part 72e, and are arranged on the separator side lead wire insertion holes 72 along the pitch circle P at approximately 90 ° intervals. In addition, the insertion holes corresponding to the receiving portions are overlapped (included) as viewed from the front end side. In the case of the embodiment of FIG. 8, the central communication portion 72e also serves as a heating element housing portion, and the heating element 3 is inserted to the front of the bottom surface 18e, contributing to the compactness of the oxygen sensor 1.
[0031]
The internal electrode fitting housing 72b includes a narrow opening 18d facing the central communication portion 72e, a wide bottom 18b extending in the outer peripheral direction (depth direction) opposite to the central communication portion 72e, and an opening 18d. The opening width (distance between walls) is gradually increased from the bottom 18b to the bottom 18b, and is formed as a space surrounded by a partition wall 18a including an inclined portion 18c that continuously connects the two (see FIG. 8B). . The internal electrode connection fitting housing part 72b as a whole has a shell shape or a mussel shape in which a part is opened in the central communication part 72e, and has a shape close to an ellipse. The depth direction maximum dimension D is set smaller than the width direction maximum dimension w2 orthogonal thereto.
[0032]
When the internal electrode connection fitting 23 is inserted into the internal electrode connection fitting accommodation portion 72b, the lead wire portion 23b remains in the accommodation portion 72b (see FIG. 2). At this time, since the width w of the central portion 23m is larger than the width (minimum width) W1 of the opening 18d and smaller than the width (maximum width) W2 of the bottom portion 18b, the enlarged edge portion 23k or the inclined edge portion 23t becomes the partition wall 18a. It moves in contact with the inclined portion 18c from the front end portion of the accommodating portion 72b to the rear side (from the front side of the sheet to the rear side). When inserting the lead wire portion 23b at the front end portion of the accommodating portion 72b, a repulsive force (spring force) is caused by pressing the protruding portion 23h projecting from the lead wire portion 23b toward the bottom portion 18b at the outer peripheral portion of the bottom portion 18b. ) And the lead wire portion 23b is securely supported at the three points of the side edges of the enlarged edge portion 23k or the inclined edge portion 23t and the lower edge (front edge) of the projecting portion 23h. However, it is less likely to cause a short circuit due to protruding from the housing portion 72b and coming into contact with the external electrode connection fitting 33 or other electric wiring. In addition, there is no need for an insulating coating for preventing contact. Furthermore, short-circuiting due to jumping out of the accommodating portion 72b due to vibration during operation is less likely to occur, and disconnection of the connection fitting 23 due to repeated vibration can be prevented.
[0033]
In FIG. 8B, it is desirable that the maximum width W2 / minimum width W1 = 1.6 to 2.3, the total depth (maximum depth) D / the effective depth d = 1.6 to 2.2. As shown in the figure, when D / d = 2, that is, the lead wire portion 23b is located in the vicinity of the pitch circle, the electrical connection from the connection fitting 23 to the lead wire 20 is not forced and the risk of disconnection is reduced. Up to this point, only the internal electrode connection fitting housing portion 72b and the internal electrode connection fitting 23 have been described. However, since the relationship between the external electrode connection fitting housing portion 72c and the external electrode connection fitting 33 is the same, the description thereof is omitted. However, it is not necessary to make them all symmetrical as shown in FIG. 8A. For example, the external electrode connection fitting housing portion 72c has a slightly square cross section like the heating element terminal housing portion 72d, Of course, the lead wire portion 33b and the protrusion portion 33h may be appropriately changed within the scope of the present invention, such as having a shape and size different from those of the lead wire portion 23b and the protrusion portion 23h of the internal electrode connection fitting 23. . When such a change is made, it also prevents a connection mistake. Further, the present invention may or may not be implemented for the heating element terminal accommodating portions 72d and 72d.
[0034]
Hereinafter, a method for manufacturing the oxygen sensor 1 will be described. First, as shown in FIG. 9A, the metal elastic member 74 is extrapolated to the ceramic separator 18. Then, as shown in FIG. 4, the ceramic separator 18, the internal electrode connection fitting 23, the external electrode connection fitting 33, the heating element 3 and the like are assembled on the front side of the filter assembly 16 assembled in advance, and the grommet 17 and the like are assembled on the rear side. At this time, lead wires 20 and 21 connected to the connectors 23a and 33a of the connection fittings 23 and 33, and lead wires (not shown) connected to the positive pole side and negative pole side heating element terminals 3b and 3b. Are inserted through the separator-side lead wire insertion hole 72 of the ceramic separator 18, and further to the rear side through the seal-side lead wire insertion hole 91 of the grommet 17 fitted into the rear end side opening of the first filter holding portion 51. It has been extended. When the ceramic separator 18 is moved to the front side and the lead wire portions 23b and 33b are inserted at the front end portion of the accommodation hole 72a, the protrusion protruding from the lead wire portions 23b and 33b toward the partition wall 18a (bottom portion 18b). The portions 23h and 33h are pressed at the outer peripheral portion of the partition wall 18a (bottom portion 18b) to generate a repulsive force (spring force), and the lead wire portions 23b and 33b are formed on the enlarged edge portions 23k and 33k or the inclined edge portions 23t and 33t. It is reliably supported at the three points of the side edges and the lower edge (front edge) of the protrusion 23h.
[0035]
Subsequently, as shown in FIG. 9B, the inner surface of the step portion 60 is ring-shaped while the filter assembly 16 is slid on the lead wires 20, 21, etc. in the seal-side lead wire insertion hole 91 of the grommet 17. The metal elastic member 74 is moved to a position where it contacts the outer surface of the ceramic separator 18. For example, even if the filter assembly 16 is slid slightly on the bundle of the lead wires 20 and 21 and the like, the rubber made between the inner edge of the opening of the first filter holding portion 51 and the lead wires 20 and 21 etc. Since the grommet 17 is interposed, there is no fear that the outer sheath of the lead wires 20, 21 and the like is cut off at the opening edge.
[0036]
In this state, as shown in FIG. 9C, the protective cover 64 and the rear end overlapping portion of the second portion 62 of the first filter holding portion 51 are caulked toward the inner grommet 17 along the circumferential direction. Thereby, the grommet caulking portion 67 is formed. On the other hand, the oxygen detection element 2 is assembled in the main cylinder 14 in advance.
[0037]
Then, as shown in FIG. 10 (a), the heating element 3 is inserted into the hollow portion 2a of the oxygen detecting element 2 from the front end side, and the first filter holding portion 51 of the filter assembly 16 is covered on the main cylinder 14, and the ceramic The separator 18 is approached in the axial direction toward the rear end portion of the oxygen detection element 2. Thereby, the metal fitting main body portion 33 c of the external electrode connecting metal fitting 33 and the metal fitting main body portion 23 c of the internal electrode connecting metal fitting 23 are positioned in the opening of the oxygen detection element 2. Then, in this state, the ceramic separator 18 is directed toward the oxygen detection element 2 while the rear end edges of the metal fitting main body portions 33c and 23c are in contact with the front end face of the ceramic separator 18 (the lower end face of the partition wall 18a in FIG. 5). To make it closer in the axial direction.
[0038]
Thereby, as shown in FIG. 2, the rear end portion of the oxygen detection element 2 is relatively pushed into the inside of the metal fitting main body portion 33 c, and the metal fitting main body portion 23 c is pushed into the inside of the oxygen detection element 2. At this time, since the rear end edges of the metal fitting main body portions 33c and 23c are in contact with the front end surface of the ceramic separator 18, there is no problem such as buckling of the lead wire portions 33b and 23b due to the pushing force in the axial direction. Smooth assembly is possible.
[0039]
10B, the first filter holding portion 51 and the main tube 14 are pressurized in the axial direction to compress and deform the metal elastic member 74, and in this state, the first filter holding portion 51 and the main tube 14 The assembly is completed by forming the casing crimping portion 76 and joining them together.
[0040]
The following changes can be considered for the positional relationship between the accommodation hole 72a and the connection fittings 23 and 33 according to the present invention.
(1) Although the accommodation hole 72a is formed only in the front half portion of the ceramic separator 18, it is formed so as to overlap with the four separator-side lead wire insertion holes 72 provided in the axial direction. The housing hole 72a may be formed over the entire length of the ceramic separator 18 in the axial direction (front-rear direction).
(2) The partition wall 18a may be inclined in the axial direction (front-rear direction). The inclination at this time gradually increases from the rear side to the front side, and is in the same direction as the enlarged edge portions 23k and 33k and the inclined edge portions 23t and 33t of the lead-out line portions 23b and 33b. The inclination of the partition wall 18a can be applied by using the die cutting taper as it is when manufacturing the ceramic separator 18 or by slightly increasing the gradient of the die cutting taper. By providing the partition wall 18a or the lead wire portions 23b and 33b with an inclination (whether linear or curved), the lead wire portion 18a can be smoothly inserted into the receiving hole 72a.
(3) Although the example in which the central communication portion 72e is also used as the heating element accommodating portion and the example in which the accommodating hole 72a includes the heating element terminal accommodating portions 72d and 72d are shown, the present invention is not limited to these (FIG. 11A). reference).
{Circle around (4)} The shapes of the connecting fitting housing portions 72b and 72c are not limited to a shell shape, and may be a trapezoidal shape surrounded by a straight line, a circular shape, an elliptical shape, other curved shapes, or a combination thereof. The separator-side lead wire insertion hole 72 penetrating the ceramic separator 18 can also be used as both of the connection fitting housing portions 72b and 72c on the front end side (see FIG. 11A).
(5) If the partition wall 18a and the lead wire portions 23b and 33b are in surface contact rather than point (line) contact, the holding becomes more stable (see FIG. 11B).
[0041]
FIG. 11 shows a main modification. In FIG. 11A, the separator-side lead wire insertion hole 72 penetrating the ceramic separator 18 is used as both connection fitting accommodating portions 72b and 72c while remaining substantially circular on the front end side, and the heating element terminal is accommodated in the accommodation hole 72a. An example in which the parts 72d and 72d are not included is shown. The partition wall 18a can have a sufficient thickness and is excellent in strength and durability. In FIG. 11B, shallow grooves 18f and 18f having a width W ′ and a depth D ′ are provided on both sides of the inclined portion 18c of the partition wall 18a, and a shallow groove 18g having a width W ″ and a depth D ″ is also provided on the bottom portion 18b. Is provided. The lead-out wire portions 23b and 33b can be inserted into the housing portions 72b and 72c with the grooves 18f and 18f as guides, and the protrusions 23h and 33h can be inserted into the housing portions 72b and 72c as a guide, and the holding force is large. Only one of the grooves 18f and 18g may be provided. In order to correspond to the leader line portions 23b and 33b having different widths w, the grooves 18f and 18f on both sides are preferably formed in a stepped shape. In order to correspond to the protrusions 23h and 33h having different widths w ′, the width W ″ of the groove 18g may be set a little wider.
[0042]
Further, the following changes can be considered for the shapes of the lead wire portions 23b and 33b and the protruding portions 23h and 33h according to the present invention.
(1) It is possible to apply the present invention to only one of the connection fittings 23 and 33, or to apply the lead wire portion and the protruding portion in different shapes.
(2) The inclined edge portions 23t and 33t and the enlarged edge portions 23k and 33k of the leader line portions 23b and 33b may not be provided, or only one of the left and right sides may be provided, and the shape thereof may be linear, curved, or the like. It doesn't matter.
(3) As for the shape of the projecting portions 23h and 33h, a bulging portion may be provided integrally with a press or a diaphragm without using a cut, or a separate projecting portion may be soldered (FIG. 12 (d) )reference).
{Circle around (4)} The protruding portions 23h, 33h can be raised in multiple stages, curved (plane), left and right, etc. (see FIGS. 12A, 12B, and 12C).
(5) The cuts 23h 'and 33h' of the projecting portions 23h and 33h can be changed to a U shape or the like in addition to the U shape.
[0043]
FIG. 12 shows a main modification. In FIG. 12A, the first protrusion 23h1 having the inclination angle θ1 and the second protrusion 23h1 ′ having the inclination angle θ1 ′ are provided in a two-stage fold shape, and the contact area of the second protrusion 23h1 ′ is further increased. It becomes wide and the holding | maintenance of the leader line part 23b is stabilized.
The same (b) is an example in which a curved projection 23h2 is provided, and the holding force is increased by the spring effect.
The figure (c) is an example in which an I-shaped cut is provided on the center line, and two rectangular tongue pieces are pushed open to the left and right to form a protrusion 23h3. The cut may be T-shaped or inverted T-shaped, and the two triangular tongues may be pushed open to the left and right. Also, the cut may be U-shaped and pushed open to the left or right. The same (d) shows an example in which the protrusion 23h4 is integrally bulged by a press or the like.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an oxygen sensor of the present invention.
FIG. 2 is a longitudinal sectional view showing a main part of the oxygen sensor of FIG.
FIG. 3 is an exploded perspective view showing an assembled state of the ceramic separator.
FIG. 4 is a partial longitudinal sectional view of the filter assembly in an assembled state.
FIG. 5 is a plan view, bottom view, AA longitudinal sectional view, and BB longitudinal sectional view of a ceramic separator.
FIG. 6 is a left side view, a front view, and a development view of an internal electrode connection fitting.
FIG. 7 is a front view, a right side view, and a development view of an external electrode connection fitting.
8 is a cross-sectional view taken along the line CC in FIG. 2 and an enlarged view thereof.
9 is a process explanatory view showing an example of a method for assembling the oxygen sensor of FIG. 1; FIG.
FIG. 10 is a process explanatory diagram following FIG. 9;
11A and 11B show a modification example of FIG. 8, in which FIG. 11A is a CC cross-sectional view of the first modification example, and FIG. 11B is a CC cross-sectional enlarged view of the second modification example;
12A and 12B show a modified example of the protruding portion of FIG. 6, wherein FIG. 12A is a front view of the first modified example, FIG. 12B is a front view of the second modified example, and FIG. 12C is a perspective view of the third modified example. , (D) is a perspective view of a fourth modified example.
[Explanation of symbols]
1 Oxygen sensor
2 Oxygen detection element
2a Hollow part
2b External electrode layer
2c Internal electrode layer
18 Ceramic separator
18a Bulkhead
18b bottom
18c Inclined part
18d opening
23 Internal electrode connection bracket (first connection bracket)
23b Lead wire part
23h Protrusion
23h 'cut
23t inclined edge (inclined side edge)
33k Enlarged edge (tilt side edge)
33 External electrode connection bracket (second connection bracket)
33b Lead wire part
33h Protrusion
33h 'cut
33t inclined edge (inclined side edge)
33k Enlarged edge (tilt side edge)
72a receiving hole
72b Internal electrode connection fitting housing part (first housing part)
72c External electrode connection fitting housing part (second housing part)
72e Central communication part
D Maximum depth of housing
Maximum width of W2 housing

Claims

An oxygen detection element having a hollow shaft shape with a closed tip, and an inner electrode layer and an outer electrode layer formed on the inner surface and the outer surface, respectively,
A first connection fitting and a second connection fitting that are arranged behind the oxygen detection element and are electrically connected to the internal electrode layer and the external electrode layer, respectively, from the front side to the rear side in the direction of the axis thereof A ceramic separator in which a housing hole having a first housing portion and a second housing portion to be inserted and held, and a central communication portion located between the two housing portions and communicating with each other is formed;
Each of the housing parts has an opening facing the central communication part, and is surrounded by a partition wall having a cross-sectional shape that is wider than the opening part in the depth direction opposite to the central communication part. Formed as a space,
At least one of the connection fittings has an extraction line portion having a width wider than the opening, and a protrusion protruding from the extraction line portion in the depth direction. Sensor.

The oxygen sensor according to claim 1, wherein the left and right side edges of the lead-out line portion and the protrusion are in contact with the inner surface of the partition wall, and the lead-out line portion is held in a corresponding accommodating portion.

3. The oxygen sensor according to claim 2, wherein the projecting portion is elastically biased in a direction in which left and right side edges of the lead-out wire portion are pressed against the inner surface of the partition wall by compressing and deforming in the housing portion. .

The partition wall connects the narrow opening facing the central communication portion, the wide bottom located on the opposite side of the central communication portion, and the bottom and the opening on both sides in the width direction. The oxygen sensor according to claim 1, wherein the oxygen sensor is formed from an inclined portion to be provided.

2. The oxygen sensor according to claim 1, wherein in the axial section of the ceramic separator, the housing portion has a maximum dimension in the depth direction of D, and a maximum width dimension in a direction orthogonal thereto is W 2> D. .

3. The oxygen sensor according to claim 2, wherein at least one of the left and right side edges of the lead-out line portion is formed on an inclined side edge that gradually becomes wider from the rear side toward the front side in the axial direction.

The projecting portion extends in a predetermined direction from the base end portion, and a cut line extending from the direction changing portion to the other end is provided in the lead-out line portion, and a tongue piece located inside the cut is caused in the depth direction. The oxygen sensor according to claim 1, wherein the oxygen sensor is formed.

The oxygen sensor according to claim 7, wherein the protruding portion is formed by raising a fulcrum on the rear side in the axial direction and raising a portion of the tongue piece located on the front side of the raising fulcrum.