JP4221201B2

JP4221201B2 - Engine exhaust gas purification device

Info

Publication number: JP4221201B2
Application number: JP2002274201A
Authority: JP
Inventors: 仁堀川; 壽三輪; 卓弥梶田; 宣好田中
Original assignee: Aisin Takaoka Co Ltd
Current assignee: Aisin Takaoka Co Ltd
Priority date: 2002-09-20
Filing date: 2002-09-20
Publication date: 2009-02-12
Anticipated expiration: 2022-09-20
Also published as: JP2004108311A

Description

【０００１】
【発明の属する技術分野】
本発明は、エンジンからの排気ガスを浄化処理するために触媒を利用するエンジンの排気ガス浄化装置に関する。
【０００２】
【従来の技術】
一般に、車輌用エンジンの排気系統には、エンジン本体から排出される排気ガス中のＨＣ，ＣＯ，ＮＯｘ等を浄化処理するための排気ガス浄化装置が設けられている。排気ガス浄化装置の多くは触媒（触媒物質を担体に担持したもの）を具備するが、触媒には、所定の活性温度に達しなければＨＣ等を有効に浄化できないという特質がある一方、過度に高温の排気に曝され続けると熱劣化を生じるという欠点がある。また、エンジンの排気ガスの側にも、冷間始動時又はアイドリング運転時と中高速回転での高負荷運転時とでは排気ガスの温度（又は排気ガスの持つ熱量）に差があるという事情がある。このため、大小二種類の触媒コンバータを排気系統に配設し、エンジンの運転状況に応じて各触媒コンバータへの排気誘導を制御するようにした排気ガス浄化装置が提案されている。
【０００３】
例えば特開平８−２５４１５８号公報に開示の装置では、排気通路の下流寄り位置に大容量の主触媒コンバータを設けると共に、その主触媒コンバータとエンジンの排気側とを結ぶ上流寄り排気通路を途中で主通路とバイパス通路との二系統に分離し、主通路から完全に独立したバイパス通路の途中に小容量の副触媒コンバータを設けている。そして前記主通路及びバイパス通路の上流側分岐点の近傍に切替弁（具体的には二つの蝶型弁を同軸連結したもの）を設け、その切替弁の操作に応じて、エンジンからの排気ガスを主通路又はバイパス通路のいずれかに選択的に誘導するようにしている。即ち冷間始動時やアイドリング運転時には排気ガスをバイパス通路に導き副触媒コンバータを経由させることで当該副触媒を早期に活性化させ、始動直後からの排気ガス浄化を可能としている。他方、中高速回転での高負荷運転時には、排気ガスを主通路に導き、主通路経由で主触媒コンバータに直接誘導し、その主触媒で排気ガスを浄化処理している。こうしてエンジンがどのような運転状況にあろうとも、触媒による安定的な排気ガス浄化と触媒（特に副触媒）の熱劣化回避とを両立させている（特許文献１参照）。
【０００４】
【特許文献１】
特開平８−２５４１５８号公報（第００２３−００２４段落、図１）
【０００５】
【発明が解決しようとする課題】
ところが、上記従来の排気ガス浄化装置にも次のような欠点がある。例えばアイドリング運転時には、エンジンからの排気ガスをバイパス通路に導いて副触媒コンバータで処理することになるが、その間、バイパス通路から隔離された主通路には排気ガスが流通せず、主通路が冷えてしまう。その後、エンジンの運転状態がアイドリング運転から高負荷運転に変化するに伴い、切替弁によって排気ガスの流通路がバイパス通路から主通路に切り替えられた場合、エンジンからの排気ガスが主通路を通過することで却って冷やされ、その冷えた排気ガスによって主触媒コンバータの温度が一時的に低下し、排気ガス浄化性能が低下するという問題があった。同様に、エンジンが高負荷運転状態にあるときには排気ガスが主通路に流され、その間、主通路から隔離されたバイパス通路には排気ガスが流通せず、バイパス通路及び副触媒コンバータが冷えてしまう。その後、エンジンがアイドリング運転状態に変化するに伴い、切替弁によって排気ガスの流通路が主通路からバイパス通路に切り替えられた場合にも、一旦冷えた副触媒が所定の活性温度に到達するまでの間、排気ガス浄化性能が一時的に低下するという問題があった。
【０００６】
本発明の目的は、二系統化された排気ガスの通路を切替え可能な排気ガス浄化装置において、一方の通路を流れる排気ガスの余熱を利用して他方の通路を予熱又は保温することができ、ガス流通路の切替えに起因する排気ガス浄化性能の一時的な低下を極力防止可能なエンジンの排気ガス浄化装置を提供することにある。また、排気系統の構造を従来よりもコンパクト化したエンジンの排気ガス浄化装置を提供することにある。
【０００７】
【課題を解決するための手段】
本発明（請求項１〜５）は、エンジンからの排気ガスを浄化処理するために主触媒コンバータを利用するエンジンの排気ガス浄化装置であって、エンジンから主触媒コンバータに達する主排気通路の一部を形成するための主配管と、前記主配管を包囲するように設けられて前記主配管との間に軸直交断面が略環状の副排気通路を形成するための筒状ケーシングと、前記筒状ケーシングにおける略環状の副排気通路内に配置された副触媒と、エンジンからの排気ガスを前記主配管を経由する主排気通路又は前記筒状ケーシング内の副排気通路のいずれかに選択的に供給するための切替弁機構とを備えることを前提とするものである。
【０００８】
上述の前提構成によれば、主配管を経由する主排気通路の周囲を主配管の管壁を挟んで副排気通路（及び副触媒）が包囲するという二系統重合構造を採用したので、切替弁機構によるガス流路の選択状況にかかわらず、主排気通路及び副排気通路のうちの一方を流れる排気ガスの熱（余熱）によって、ガスが流れていない他方の排気通路を予熱又は保温することができる（つまり主副排気通路間で熱交換可能）。それ故、切替弁機構によるガス流路の切替え直後にそれまで排気ガスが流れていなかった主排気通路又は副排気通路（及び副触媒）を排気ガスが通過した場合でも、排気ガスの温度低下が回避される。従って、ガス流路の切替え後も直ちにそれぞれの触媒（主触媒コンバータに保持された触媒及び前記副触媒）は所期の排気ガス浄化作用を発揮でき、ガス流通路の切替えに起因する排気ガス浄化性能の一時的な低下を極力防止することができる。更に、前記二系統重合構造の軸直交断面の中心に主配管（主排気通路）を配置しその周囲に副排気通路及び副触媒を配置したので、排気ガス浄化装置の配管構成を従来よりもコンパクト化でき、又、エンジンから主触媒コンバータにいたる主排気通路を極力直線的に（即ち不必要に経路を湾曲させずに）経路設定し易い。このため、エンジンの高負荷運転時、主排気通路に排気ガスを流通させる場合の排気抵抗を低減でき、エンジン性能の向上を図ることができる。
【０００９】
尚、上記切替弁機構は、エンジンと主配管及び筒状ケーシングとの間に配置されることが好ましいが、主配管及び筒状ケーシングと主触媒コンバータとの間に配置されてもよい。また、副触媒の熱容量が前記主触媒コンバータ内に保持された主触媒の熱容量よりも小さいことは好ましい。
【００１０】
請求項１の発明は、エンジンからの排気ガスを浄化処理するために主触媒コンバータを利用するエンジンの排気ガス浄化装置であって、エンジンから主触媒コンバータに達する主排気通路の一部を形成するための主配管と、前記主配管を包囲するように設けられて前記主配管との間に軸直交断面が略環状の副排気通路を形成するための筒状ケーシングと、前記筒状ケーシングにおける略環状の副排気通路内に配置された副触媒と、エンジンからの排気ガスを前記主配管を経由する主排気通路又は前記筒状ケーシング内の副排気通路のいずれかに選択的に供給するための切替弁機構とを備えており、
前記切替弁機構は、前記主配管及び筒状ケーシングの上流側に配置されると共に第１及び第２の弁孔が形成された枠体と、前記枠体の第１弁孔と前記主配管との間に前記主配管を経由する主排気通路の一部となる気密室を区画する第１誘導ハウジングと、前記枠体の第２弁孔と前記筒状ケーシングとの間に前記副排気通路の一部となる気密室を区画する第２誘導ハウジングと、前記第１誘導ハウジング内において第１弁孔を開放する開放位置と第１弁孔を閉塞する閉塞位置との間を切替え配置可能に設けられた第１の弁体と、前記第２誘導ハウジング内において第２弁孔を開放する開放位置と第２弁孔を閉塞する閉塞位置との間を切替え配置可能に設けられた第２の弁体と、前記第１及び第２の弁体のうちの一方が開放位置に配置されるときには他方が閉塞位置に配置されるように両弁体をリンクさせながら配置切替えする弁体リンク機構とを備えており、前記第１誘導ハウジング内には、第１弁孔と主配管とを結ぶ排気ガスの流通経路に対して横方向に後退した退避空間が確保され、その退避空間内に第１弁体の開放位置が設定されており、前記第２誘導ハウジング内には、第２弁孔と筒状ケーシングとを結ぶ排気ガスの流通経路に対して横方向に後退した退避空間が確保され、その退避空間内に第２弁体の開放位置が設定されていることを特徴とする。
【００１１】
この構成によれば、弁体リンク機構により第１及び第２弁体のうちの一方が閉塞位置から開放位置に切替え配置されると、その弁体は対応する誘導ハウジング内の退避空間に退避される。すると、当該弁体は誘導ハウジング内の排気ガス流通経路に居座ることなくそのガス流通経路から完全に退くこととなるため、当該弁体が排気ガス流通の障害物とならず、排気抵抗が低減される。また、各弁体が退避空間内に設定された開放位置に配置される間は少なくとも、弁体が高温の排気ガス流のまっただ中に曝されることがない。それ故、各弁体の配置切替えが断続的に行われることで、各弁体が過熱状態に陥るのを回避できる。
【００１２】
請求項２の発明は、請求項１に記載のエンジンの排気ガス浄化装置において、前記第１及び第２の弁体は、それぞれに対応する弁孔の周縁部に着座可能な皿形の弁体であり、前記弁体リンク機構は、第１誘導ハウジングを貫通する第１の回動軸と、第２誘導ハウジングを貫通する第２の回動軸と、前記第１及び第２の回動軸を同期回動させる機構とを具備しており、前記第１回動軸から延びる第１のアームに前記第１弁体が支持されると共に、前記第２回動軸から延びる第２のアームに前記第２弁体が支持されていることを特徴とする。
【００１３】
この構成によれば、第１及び第２の弁体を皿形にすると共に、同期回動される第１及び第２の回動軸の各々から延びるアームに各弁体を支持する構成を採用したので、各弁体が対応する弁孔の周縁部に着座したとき（即ち閉塞位置に配置されたとき）の排気ガスのシール性が高められる。
【００１４】
請求項３の発明は、エンジンからの排気ガスを浄化処理するために主触媒コンバータを利用するエンジンの排気ガス浄化装置であって、エンジンから主触媒コンバータに達する主排気通路の一部を形成するための主配管と、前記主配管を包囲するように設けられて前記主配管との間に軸直交断面が略環状の副排気通路を形成するための筒状ケーシングと、前記筒状ケーシングにおける略環状の副排気通路内に配置された副触媒と、エンジンからの排気ガスを前記主配管を経由する主排気通路又は前記筒状ケーシング内の副排気通路のいずれかに選択的に供給するための切替弁機構とを備えており、
前記切替弁機構は、前記主配管及び筒状ケーシングの上流側に配置されると共に、第１及び第２の弁孔が形成された弁孔区画部、並びに、前記両弁孔の中間位置において前記弁孔区画部から突設された支持部及び隔壁部を有する枠体と、前記枠体を覆うと共に、前記第１弁孔と前記主配管とを結ぶ前記主排気通路の一部となる第１の気密室および前記第２弁孔と前記筒状ケーシングとを結ぶ前記副排気通路の一部となる第２の気密室が前記枠体の支持部及び隔壁部を挟んで内部に区画される誘導ハウジングと、前記枠体の支持部に回動可能に支持されると共に前記第１気密室内に延びる第１アーム及び前記第２気密室内に延びる第２アームを有する駆動シャフトと、前記第１アームに支持された前記第１弁孔に対応する第１の弁体と、前記第２アームに支持された前記第２弁孔に対応する第２の弁体とを備え、前記駆動シャフトに対して第１及び第２アームは、第１及び第２の弁体のうちの一方がそれと対応する弁孔を開放する開放位置に配置されるときには、他方がそれと対応する弁孔を閉塞する閉塞位置に配置されるように取り付けられていることを特徴とする。
【００１５】
この構成によれば、共通の駆動シャフトから延びる第１及び第２アームに第１及び第２の弁体をそれぞれ支持すると共に、駆動シャフトに対する第１及び第２アームの取り付け態様を前述のようにしたので、駆動シャフトの回動操作に基づいて、両弁体の配置切替えを同期させながら切替弁機構による主排気通路又は副排気通路の択一的選択が可能となる。また、この構成によれば、切替弁機構をコンパクト化できる。
【００１６】
請求項４の発明は、請求項３に記載のエンジンの排気ガス浄化装置において、前記枠体の隔壁部のそれぞれの側には、前記第１気密室内において第１弁孔と主配管とを結ぶ排気ガスの流通経路に対して隔壁部寄り方向に後退した第１の退避空間、及び、前記第２気密室内において第２弁孔と筒状ケーシングとを結ぶ排気ガスの流通経路に対して隔壁部寄り方向に後退した第２の退避空間が確保され、前記第１の退避空間内に第１弁体の開放位置が設定されると共に、前記第２の退避空間内に第２弁体の開放位置が設定されていることを特徴とする。
【００１７】
この構成によれば、駆動シャフトの回動操作に基づき第１及び第２弁体のうちの一方が閉塞位置から開放位置に切替え配置されると、その弁体は対応する気密室の退避空間に退避される。すると、当該弁体はその気密室内の排気ガス流通経路に居座ることなくそのガス流通経路から完全に退くこととなるため、当該弁体が排気ガス流通の障害物とならず、排気抵抗が低減される。また、各弁体が退避空間内に設定された開放位置に配置される間は少なくとも、弁体が高温の排気ガス流のまっただ中に曝されることがない。それ故、各弁体の配置切替えが断続的に行われることで、各弁体が過熱状態に陥るのを回避できる。
【００１８】
請求項５の発明は、請求項３又は４に記載のエンジンの排気ガス浄化装置において、前記第１及び第２の弁体は、それぞれに対応する弁孔の周縁部に着座可能な皿形の弁体であることを特徴とする。
【００１９】
この構成によれば、第１及び第２の弁体を皿形にしたので、各弁体が対応する弁孔の周縁部に着座したとき（即ち閉塞位置に配置されたとき）の排気ガスのシール性が高められる。
【００２０】
【発明の実施の形態】
以下、本発明の実施形態について図面を参照して説明する。
【００２１】
（基本実施形態）
図１は排気ガス浄化装置の基本実施形態を示す。多気筒のエンジン１０から排出された排気ガスは、各気筒からの排気ガスを集合させる排気マニホルド１１、切替弁機構１２、副触媒コンバータ１３および振動遮断機構１４を経由して主触媒コンバータ１５に達し、主触媒コンバータ１５を通過後はマフラー（図示略）等を経て大気中に放出される。エンジン１０としてはガソリンエンジンを想定するが、ディーゼルエンジンに対しても本発明を適用できる。
【００２２】
切替弁機構１２と主触媒コンバータ１５との間に位置する副触媒コンバータ１３は、その中心に位置する主配管１３ａと、その主配管１３ａを包囲するように設けられた筒状ケーシング１３ｂと、副触媒１６とを備えている。主配管１３ａは、エンジン１０から主触媒コンバータ１５にいたる排気ガスの主たる通路（主排気通路）の途中一部分を担う配管である。主配管１３ａの外周面と筒状ケーシング１３ｂの内周面との間には、主配管１３ａの中心軸線に対する軸直交断面が略環状（より好ましくは円環状）の副排気通路が形成される。即ち、副触媒コンバータ１３は、主排気通路を副排気通路が取り囲む二系統重合配管構造をなしている。前記略環状の副排気通路内には副触媒１６が配置されており、主配管１３ａが副触媒１６の中心を貫通すると共に、主配管１３ａの後端部（出口部）が副触媒１６の後端面から突出する格好となっている（尚、その様子を図２及び図３に拡大して示す）。
【００２３】
図１に示すように、主配管１３ａの入口部と筒状ケーシング１３ｂにおける副排気通路の入口部とは分離され、それぞれの入口部が、当該副触媒コンバータ１３の上流側に位置する切替弁機構１２に接続されている。他方、主配管１３ａの出口部と筒状ケーシング１３ｂにおける副排気通路の出口部とは統合され、共通の出口部として当該副触媒コンバータ１３の下流側に位置する振動遮断機構１４に接続されている。
【００２４】
切替弁機構１２は、排気マニホルド１１で集合されたエンジン１０からの排気ガスを副触媒コンバータ１３内の二つの流通路（即ち主配管１３ａを経由する主排気通路と、筒状ケーシング１３ｂ内の副排気通路）のうちのいずれか一方に選択的（二者択一的）に供給するためのガス流制御機構である。切替弁機構１２についてはいくつかの設計態様があり、各態様については後ほど詳述する。切替弁機構１２は弁駆動制御装置１７と作動連結されている。弁駆動制御装置１７は、例えば吸気系に設けられたスロットルバルブの開度、エンジン回転数、ラジエータの冷却水温度、排気ガス中の酸素濃度、排気ガス温度、各触媒の温度（即ち触媒担体の温度）などのエンジンの運転状態を反映する各種情報に基づいて切替弁機構１２の動作を制御する。
【００２５】
振動遮断機構１４は、副触媒コンバータ１３を通過してきた排気ガスが主触媒コンバータ１５に達するのを許容しつつ、エンジン１０の振動が当該排気ガス浄化装置の配管系を伝わって主触媒コンバータ１５以降の配管系に伝達するのを遮断又は緩和するための緩衝機構である。
【００２６】
主触媒コンバータ１５は、排気ガス中のＨＣ，ＣＯ，ＮＯｘ等を浄化するための触媒物質を担持した通気性セラミックス担体（例えばハニカム構造の円柱状セラミックス担体）を円筒状ケース内に収容して構成されている。
【００２７】
前記副触媒１６も同様に触媒物質を担持した通気性セラミックス担体から構成されているが、その形状は前記副排気通路の形状に適合して軸直交断面が略環状の中央くりぬき円筒体をなしている。副触媒１６は、主触媒コンバータ１５に保持された主触媒よりも小体積とすることで熱容量が相対的に小さくなっている。このため、排気ガスによりもたらされる熱量が少ない場合でも副触媒１６は直ちに昇温して所定の活性温度に迅速に到達できる。
【００２８】
本発明の実施形態は、上記切替弁機構１２の構造上の違いに応じて更に第１実施例、第２実施例及びその他の実施例に細分化される。上述の基本実施形態（図１）は、以下に述べる各実施例に共通の基本構成を示したものである。
【００２９】
（第１実施例）
図２〜図４は第１実施例に従う排気ガス浄化装置の主要部を示し、特に図４は第１実施例の切替弁機構を示す。各図に示すように、副触媒コンバータ１３の上流側に配設された切替弁機構１２は、二つの弁孔が形成された枠体２１と、分岐配管２２と、第１の誘導ハウジング２３と、第２の誘導ハウジング２４と、第１の弁体２５と、第２の弁体２６とを少なくとも備えている。
【００３０】
枠体２１は断面逆「く」の字形をなし、当該枠体２１には第１の弁孔２１ａ及び第２の弁孔２１ｂが形成されている。各弁孔２１ａ，２１ｂは円形状をなし、各弁孔の周縁を区画している枠体２１の肉部（周縁部）は弁座として機能する。分岐配管２２は、排気マニホルド１１からの排気ガスを二方向に分岐する配管であり、一方の分岐が第１の弁孔２１ａに連結され、他方の分岐が第２の弁孔２１ｂに連結されている。
【００３１】
第１の誘導ハウジング２３は、第１の弁孔２１ａを通過したガスを主配管１３ａの入口部に誘導すべく形状設定された中空な被覆材である。第１の誘導ハウジング２３の出口側開口端は主配管１３ａの入口部に接合されると共に、その接合部位の全周を溶接することにより主配管１３ａの入口部に気密連結されている。他方、第１の誘導ハウジング２３の入口側開口端は、第１の弁孔２１ａを取り囲む位置にて枠体２１の一側面に接合されると共に、その接合部位の全体を溶接することにより枠体２１に対し気密連結されている。つまり第１の誘導ハウジング２３は、枠体の第１弁孔２１ａと主配管１３ａの入口部との間に主排気通路の一部となる気密室を区画形成する。この気密室内には、排気ガスの流通経路に対して横方向（図４では下方向）に後退した第１弁体用の退避空間Ｓ１が確保されている。
【００３２】
第２の誘導ハウジング２４は、第２の弁孔２１ｂを通過したガスを筒状ケーシング１３ｂの入口部に誘導すべく形状設定された中空な被覆材である。第２の誘導ハウジング２４の出口側開口端は筒状ケーシング１３ｂの入口部に接合されると共に、その接合部位の全周を溶接することにより筒状ケーシング１３ｂの入口部に気密連結されている。他方、第２の誘導ハウジング２４の入口側開口端は、第２の弁孔２１ｂを取り囲む位置にて枠体２１の一側面に接合されると共に、その接合部位の全体を溶接することにより枠体２１に対し気密連結されている。つまり第２の誘導ハウジング２４は、枠体の第２の弁孔２１ｂと筒状ケーシング１３ｂの入口部との間に副排気通路の一部となる気密室を区画形成する。この気密室内には、排気ガスの流通経路に対して横方向（図４では上方向）に後退した第２弁体用の退避空間Ｓ２が確保されている。
【００３３】
第１の弁体２５は、第１誘導ハウジング２３内にあって枠体の第１弁孔２１ａを開閉するための皿形の弁である。第２の弁体２６は、第２誘導ハウジング２４内にあって枠体の第２弁孔２１ｂを開閉するための皿形の弁である。第１及び第２の弁体２５，２６は、弁体リンク機構を介して前記弁駆動制御装置１７に作動連結されている。図４に示すように弁体リンク機構は、各誘導ハウジング２３，２４を貫通する第１及び第２の回動軸３１，３２と、それぞれの誘導ハウジング内において各回動軸に一体化された第１及び第２のアーム３３，３４と、それぞれの誘導ハウジングの外側において各回動軸に一体化された第１及び第２のレバー３５，３６と、両レバー３５，３６を作動連結するリンクバー３７とを備えている。リンクバー３７は弁駆動制御装置１７内のアクチュエータ（例えば電磁ソレノイド）によって所定方向に往復作動される。即ち、第１及び第２の回動軸３１，３２は、リンクバー３７並びに第１及び第２のレバー３５，３６を介して弁駆動制御装置１７により同期回動される。第１及び第２のレバー３５，３６並びにリンクバー３７は「第１及び第２の回動軸３１，３２を同期回動させる機構」を構成する。
【００３４】
第１及び第２のアーム３３，３４の先端部にはそれぞれ、第１及び第２の弁体２５，２６が固定されている。そして、第１及び第２の回動軸３１，３２に対する第１及び第２のアーム３３，３４の取付け角度は、第１弁体２５が第１誘導ハウジングの退避空間Ｓ１内の開放位置に配置されるときに、第２弁体２６が第２の弁孔２１ｂを完全に閉じる閉塞位置に配置され（図２参照）、第２弁体２６が第２誘導ハウジングの退避空間Ｓ２内の開放位置に配置されるときに、第１弁体２５が第１の弁孔２１ａを完全に閉じる閉塞位置に配置されるように（図３参照）角度設定されている。
【００３５】
次に、第１実施例の排気ガス浄化装置の作用について説明する。
エンジン１０の冷間始動時及びアイドリング運転時（低負荷運転時）には、図３に示すように、弁駆動制御装置１７によって、第１弁体２５は第１弁孔２１ａを閉じる閉塞位置に配置されると共に、第２弁体２６は退避空間Ｓ２内に退避して第２弁孔２１ｂを完全開放する開放位置に配置される。図３の状態では、エンジン１０からの排気ガスは、第２誘導ハウジング２４を経由して副排気通路に進入し、副触媒１６を通過した後、主排気通路に戻り主触媒コンバータ１５に導かれる。
【００３６】
副触媒１６は排気ガスの熱によって迅速に活性温度に到達し、排気ガス中の環境悪化物質（ＨＣ，ＣＯ，ＮＯｘ等）を浄化処理する。この触媒による浄化は、ＨＣ及びＣＯの酸化に起因した発熱反応を伴うため、その反応熱によって副触媒１６を通過した排気ガスは通過前よりも更に高温化する。この更に高温化した排気ガスは主触媒コンバータ１５の予熱（つまり事前暖機）に貢献する。
【００３７】
図３の状態では、排気ガスは主配管１３ａ内を流れないが、主配管１３ａの周囲を取り囲んでいる副排気通路及び副触媒１６を流れる排気ガスの熱が、主配管１３ａの管壁を介して主配管１３ａの内壁側にも伝達される。更には主配管１３ａから第１誘導ハウジング２３へも熱が伝わる。このように、副触媒コンバータ１３の副排気通路を排気ガスが流れることで、その排気ガスの熱が主配管１３ａ及び第１誘導ハウジング２３の内壁にも伝達され、その結果、副触媒コンバータ１３の中心に位置する主排気通路の内壁部が同時に予熱されるという副次的効果がもたらされる。
【００３８】
他方、エンジン１０の中高速回転時（高負荷運転時）には図２に示すように、弁駆動制御装置１７によって、第１弁体２５は退避空間Ｓ１内に退避して第１弁孔２１ａを完全開放する開放位置に配置されると共に、第２弁体２６は第２弁孔２１ｂを閉じる閉塞位置に配置される。図２の状態では、エンジン１０からの排気ガスは、第１誘導ハウジング２３を経由して主配管１３ａ（主排気通路）に進入し、そのままストレートに主触媒コンバータ１５に導かれる。
【００３９】
主触媒コンバータ１５は前記低負荷運転時に予熱されているため、切替弁機構１２による流路切替時には既に活性温度近くにまで達している。また、高負荷運転時のエンジン１０から排出される排気ガスの温度は低負荷運転時よりも一般に高温であることに加えて、主配管１３ａ及び第１誘導ハウジング２３の内壁部が前記低負荷運転時における予熱によって暖められている。それ故、ガス流路が副排気通路から主排気通路に切り替えられた直後でも、エンジン１０からの排気ガスが、第１誘導ハウジング２３及び主配管１３ａからなる主排気通路を通過することで温度を低下させることはなく、高温のまま主触媒コンバータ１５に導かれる。従って、主触媒コンバータ１５は、直ちに排気ガス中の環境悪化物質（ＨＣ，ＣＯ，ＮＯｘ等）を浄化処理することができる。
【００４０】
図２の状態では、排気ガスは副排気通路を流れないが、副触媒コンバータ１３の中心に位置する主配管１３ａを流れる排気ガスの熱が、主配管１３ａの管壁を介して副触媒１６にも伝達される。更には副触媒１６から筒状ケーシング１３ｂ及び第２誘導ハウジング２４へも熱が伝わる。このように、副触媒コンバータ１３の主排気通路を排気ガスが流れることで、その排気ガスの熱が副触媒１６、筒状ケーシング１３ｂ及び第２誘導ハウジング２４にも伝達され、その結果、副触媒コンバータ１３の外周側に位置する副排気通路の内壁部が同時に予熱されるという副次的効果がもたらされる。
【００４１】
この第１実施例によれば、次のイ〜ホのような効果を得ることができる。
イ．切替弁機構１２の下流側に位置する副触媒コンバータ１３をその軸直交断面の中心にある主排気通路が副排気通路によって包囲されるという二重管構造としたので、一方の通路を流れる排気ガスの熱（余熱）を、ガスが流れていない他方の通路の予熱（事前の加熱）に有効利用することができる。その結果、切替弁機構１２によるガス流路の切替え操作に関わりなく、排気ガスが流れない状態にある主排気通路又は副排気通路を常に暖めておくことができる。そして、切替弁機構１２によるガス流路の切替え直後に、それまで排気ガスが流れていなかった主排気通路又は副排気通路を排気ガスが通過した場合でもその排気ガスの温度低下をほぼ防止することができる。それ故、切替弁機構１２によるガス流路の切替え後も直ちに、主触媒コンバータ１５内の主触媒や副触媒１６に所期の排気ガス浄化作用を発揮させることができる。
【００４２】
ロ．副触媒コンバータ１３をその軸直交断面の中心にある主排気通路が副排気通路により包囲されるという二重管構造としたので、従来例（前記特許文献１）のように主通路とバイパス通路とを完全に分離独立させた配管構成の場合に比べて、排気ガス浄化装置を全体的にコンパクト化することができる。
【００４３】
ハ．副触媒コンバータ１３において主排気通路を包囲する副排気通路の内側に副触媒１６を配設したので、エンジンの高負荷運転時に排気ガスを流通させることになる主排気通路（より具体的には、分岐配管２２の入口から第１誘導ハウジング２３を経て主配管１３ａの出口にいたる経路）を極力直線状態に近づけることができる（図２参照）。従って、エンジンの高負荷運転時において前記主排気通路の経路設定が原因となる排気抵抗の増大を回避し、高負荷運転でのエンジン性能の向上を図ることができる。
【００４４】
ニ．切替弁機構１２を構成する第１及び第２誘導ハウジング２３，２４の内部にそれぞれ退避空間Ｓ１，Ｓ２を確保すると共に、第１及び第２の弁体２５，２６がそれぞれ対応する弁孔を完全解放する開放位置を各退避空間Ｓ１，Ｓ２内に設定した。このため、第１及び第２の弁体２５，２６の一方が閉塞位置から開放位置に切替え配置されたときに、その弁体が（主又は副）排気通路から完全に退いて排気通路の内側に居座り続けない。このため、従来例（前記特許文献１）に開示された二つの蝶型弁を同軸連結してなる切替弁とは異なり、開放位置に配置された第１又は第２の弁体２５，２６が排気ガス流通の障害物とならず、排気抵抗が低減される。更には、各弁体２５，２６が開放状態にあるときには、対応する退避空間Ｓ１，Ｓ２に退避させることで、高温の排気ガスの流れのまっただ中に弁体が置かれる時間を短縮することができ、弁体２５，２６が過熱状態に陥るのを回避することができる。
【００４５】
ホ．第１及び第２の弁体２５，２６を皿形とし、枠体２１の各弁座部に面的に着座可能としたので、配管内に設けられる蝶型弁に比べて排気ガスのシール性に優れている。
【００４６】
（第２実施例）
図５〜図７は第２実施例に従う排気ガス浄化装置の切替弁機構１２を示す。各図に示すように副触媒コンバータ１３の上流側に配設される切替弁機構１２は、二つの弁孔が形成された枠体４１と、分岐配管４２と、誘導ハウジング４３と、第１の弁体４５と、第２の弁体４６とを少なくとも備えている。
【００４７】
枠体４１は断面略「Ｔ」字形をなし（図５参照）、当該枠体４１には第１の弁孔４１ａ及び第２の弁孔４１ｂが形成されている。各弁孔４１ａ，４１ｂは円形状をなし、各弁孔の周縁を区画している枠体４１の肉部（弁孔区画部４１ｃ）は弁座として機能する。枠体４１には更に、両弁孔４１ａ，４１ｂの中間位置において弁孔区画部４１ｃから直交方向に延びる支持部４１ｄ及び隔壁部４１ｅが形成されている（図７（Ａ）参照）。支持部４１ｄには、後述する駆動シャフト４７が回動可能に支持される。
【００４８】
図５に示すように、分岐配管４２は、排気マニホルド１１からの排気ガスを二方向に分岐する配管であり、一方の分岐が第１の弁孔４１ａに連結され、他方の分岐が第２の弁孔４１ｂに連結されている。
【００４９】
誘導ハウジング４３は枠体４１を覆う中空な被覆材であって、その前側（入口側）開口端は前記弁孔区画部４１ｃの後面周縁に対して接合されると共に、その接合部の全周を溶接することにより気密連結されている。誘導ハウジング４３の後方側（出口側）には、第１の出口側開口端４３ａと第２の出口側開口端４３ｂとが並設されている。第１の出口側開口端４３ａは主配管１３ａの入口部に接合され、その接合部位の全周を溶接することにより主配管１３ａの入口部に気密連結されている。また、第２の出口側開口端４３ｂは筒状ケーシング１３ｂの入口部に接合され、その接合部位の全周を溶接することにより筒状ケーシング１３ｂの入口部に気密連結されている。
【００５０】
図５に示すように、誘導ハウジング４３の内部は、そこに収容される枠体の支持部４１ｄ及び隔壁部４１ｅを挟んで二つの気密室に区画されている。即ち、第１の出口側開口端４３ａに対応する誘導ハウジング４３の片側半部、枠体の支持部４１ｄ及び隔壁部４１ｅによって、枠体の第１弁孔４１ａと主配管１３ａの入口部とを結ぶ主排気通路の一部となる第１の気密室が区画形成されている。また、第２の出口側開口端４３ｂに対応する誘導ハウジング４３の片側半部、枠体の支持部４１ｄ及び隔壁部４１ｅによって、枠体の第２の弁孔４１ｂと筒状ケーシング１３ｂの入口部とを結ぶ副排気通路の一部となる第２の気密室が区画形成されている。そして、誘導ハウジング４３内を二分する隔壁部４１ｅの各側面は、第１及び第２の弁孔４１ａ，４１ｂの各内端から所定距離ｈだけオフセットしている。こうして、隔壁部４１ｅの第１気密室側には、第１弁孔４１ａと第１の出口側開口端４３ａとを結ぶ排気ガス流路に対して前記オフセット距離ｈだけ隔壁部寄り方向に後退した第１弁体用の退避空間Ｓ１が確保されている。また、隔壁部４１ｅの第２気密室側には、第２弁孔４１ｂと第２の出口側開口端４３ｂとを結ぶ排気ガス流路に対して前記オフセット距離ｈだけ隔壁部寄り方向に後退した第２弁体用の退避空間Ｓ２が確保されている。
【００５１】
第１及び第２の弁体４５，４６はそれぞれ、枠体の第１弁孔４１ａ，４１ｂを開閉するための皿形の弁である。これらの弁体４５，４６は、弁体リンク機構を介して前記弁駆動制御装置１７に作動連結されている。特に図６及び図７（Ｂ）に示すように、弁体リンク機構は、前記支持部４１ｄに回動可能に支持された駆動シャフト４７と、そのシャフトに一体化された第１アーム４８及び第２アーム４９とを備えている。駆動シャフト４７は弁駆動制御装置１７内のアクチュエータ（例えばモータ）に作動連結されており、そのアクチュエータによって正逆方向に回動される。
【００５２】
第１及び第２のアーム４８，４９はそれぞれ前記第１及び第２の気密室内に延びており、各アームの先端部には、それぞれ第１及び第２の弁体４５，４６が固定されている。共通の駆動シャフト４７に対する第１及び第２のアーム４８，４９の取付け角度は、第１弁体４５が前記退避空間Ｓ１内に設定された開放位置に配置されるときに、第２弁体４６が第２の弁孔４１ｂを完全に閉じる閉塞位置に配置されると共に（図５参照）、第２弁体４６が前記退避空間Ｓ２内に設定された開放位置に配置されるときに、第１弁体４５が第１の弁孔４１ａを完全に閉じる閉塞位置に配置されるように角度設定されている。
【００５３】
次に、第２実施例の排気ガス浄化装置の作用について説明する。
エンジン１０の冷間始動時及びアイドリング運転時（低負荷運転時）には、弁駆動制御装置１７によって、第１弁体４５は第１弁孔４１ａを閉じる閉塞位置に配置されると共に、第２弁体４６は退避空間Ｓ２内に退避して第２弁孔４１ｂを完全開放する開放位置に配置される（図示略）。この状態では、エンジン１０からの排気ガスは、第２弁孔４１ｂ及び誘導ハウジング４３の第２の出口側開口端４３ｂを経由して筒状ケーシング１３ｂ内の副排気通路に進入し、副触媒１６を通過した後、主排気通路に戻り主触媒コンバータ１５に導かれる。この場合における副触媒コンバータ１３及び主触媒コンバータ１５での作用は前記第１実施例と同じである。
【００５４】
エンジン１０の中高速回転時（高負荷運転時）には、図５に示すように、弁駆動制御装置１７によって、第１弁体４５は退避空間Ｓ１内に退避して第１弁孔４１ａを完全開放する開放位置に配置されると共に、第２弁体４６は第２弁孔４１ｂを閉じる閉塞位置に配置される。この状態では、エンジン１０からの排気ガスは、第１弁孔４１ａ及び誘導ハウジング４３の第１の出口側開口端４３ａを経由して主配管１３ａ（主排気通路）に進入し、そのままストレートに主触媒コンバータ１５に導かれる。この場合における副触媒コンバータ１３及び主触媒コンバータ１５での作用は前記第１実施例と同じである。
【００５５】
この第２実施例によれば、前記第１実施例における前記イ、ロ及びハと同様の効果を得ることができる。それに加えて以下の効果を得ることができる。
【００５６】
切替弁機構１２を構成する誘導ハウジング４３の内部において枠体の隔壁部４１ｅの両側にそれぞれ退避空間Ｓ１，Ｓ２を確保すると共に、第１及び第２の弁体４５，４６がそれぞれに対応する弁孔を完全開放する開放位置を各退避空間Ｓ１，Ｓ２内に設定した。このため、第１及び第２の弁体４５，４６の一方が閉塞位置から開放位置に切替え配置されたときに、その弁体が（主又は副）排気通路から完全に退いて排気通路の内側に居座り続けない。このため、従来例（前記特許文献１）に開示された二つの蝶型弁を同軸連結してなる切替弁とは異なり、開放位置に配置された第１又は第２の弁体４５，４６が排気ガス流通の障害物とならず、排気抵抗が低減される。更には、各弁体４５，４６が開放状態にあるときには、対応する退避空間Ｓ１，Ｓ２に退避させることで、高温の排気ガスの流れのまっただ中に弁体が置かれる時間を短縮することができ、弁体４５，４６が過熱状態に陥るのを回避することができる。
【００５７】
第１及び第２の弁体４５，４６を皿形とし、枠体の弁孔区画部４１ｃの各弁座部に面的に着座可能としたので、配管内に設けられる蝶型弁に比べて排気ガスのシール性に優れている。また、各弁体４５，４６を各アーム４８，４９に支持すると共にそれらのアームを共通の駆動シャフト４７で駆動する構成としたので、ガス流速等の大きさに応じて駆動シャフト４７の回動駆動力を適宜設定することができ、各弁体が弁座部に着座した場合のバルブ座面圧を適正化し易い。
【００６０】
【発明の効果】
以上詳述したように本発明の排気ガス浄化装置によれば、二系統化された排気ガスの通路（主及び副排気通路）を切替え可能な排気ガス浄化装置において、一方の通路を流れる排気ガスの余熱を利用して他方の通路を予熱又は保温することができ、ガス流通路の切替えに起因する排気ガス浄化性能の一時的な低下を極力防止することができる。また、排気系統の構造を従来よりもコンパクト化することができる。
【図面の簡単な説明】
【図１】排気ガス浄化装置の基本実施形態の概要を示す図。
【図２】第１実施例の排気ガス浄化装置の主要部を示す断面図。
【図３】第１実施例の排気ガス浄化装置の主要部を示す断面図。
【図４】第１実施例の切替弁機構を示す断面図。
【図５】第２実施例の切替弁機構を示す断面図。
【図６】図５のＸ−Ｘ線での断面図。
【図７】（Ａ）は第２実施例の切替弁機構を構成する枠体の概略斜視図、（Ｂ）は同切替弁機構を構成する弁体リンク機構の概略斜視図。
【符号の説明】
１０…エンジン，１２…替弁機構，１３…触媒コンバータ，１３ａ…主配管，１３ｂ…筒状ケーシング，１５…主触媒コンバータ，１６…副触媒，２１…枠体，２１ａ…第１の弁孔，２１ｂ…第２の弁孔，２３…第１誘導ハウジング，２４…第２誘導ハウジング，２５…第１の弁体，２６…第２の弁体，３１，３２…第１及び第２の回動軸，３３，３４…第１及び第２のアーム，４１…枠体，４１ａ…第１の弁孔，４１ｂ…第２の弁孔，４１ｃ…弁孔区画部，４１ｄ…支持部，４１ｅ…隔壁部，４３…誘導ハウジング，４５…第１の弁体，４６…第２の弁体，４７…駆動シャフト，４８，４９…第１及び第２のアーム，Ｓ１…第１弁体用の退避空間，Ｓ２…第２弁体用の退避空間。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine exhaust gas purification device that uses a catalyst to purify exhaust gas from an engine.
[0002]
[Prior art]
In general, an exhaust system of a vehicle engine is provided with an exhaust gas purification device for purifying HC, CO, NOx, etc. in exhaust gas discharged from the engine body. Many exhaust gas purification devices have a catalyst (a catalyst material supported on a carrier), but the catalyst has a characteristic that it cannot effectively purify HC or the like unless it reaches a predetermined activation temperature. There is a drawback that thermal deterioration occurs when exposed to high temperature exhaust. There is also a situation on the exhaust gas side of the engine that there is a difference in the temperature of the exhaust gas (or the amount of heat that the exhaust gas has) between cold start or idling operation and high load operation at medium and high speed rotation. is there. For this reason, an exhaust gas purifying apparatus has been proposed in which two types of large and small catalytic converters are arranged in an exhaust system and exhaust induction to each catalytic converter is controlled in accordance with the operating state of the engine.
[0003]
For example, in the apparatus disclosed in Japanese Patent Application Laid-Open No. 8-254158, a large-capacity main catalytic converter is provided at a position near the downstream side of the exhaust passage, and an upstream exhaust passage connecting the main catalytic converter and the exhaust side of the engine is provided on the way. A sub-catalyst converter having a small capacity is provided in the middle of a bypass passage that is separated into two systems of a main passage and a bypass passage and is completely independent from the main passage. A switching valve (specifically, two butterfly valves are coaxially connected) is provided in the vicinity of the upstream branch point of the main passage and bypass passage, and exhaust gas from the engine is operated in accordance with the operation of the switching valve. Is selectively guided to either the main passage or the bypass passage. That is, at the time of cold start or idling operation, exhaust gas is guided to the bypass passage and passed through the sub catalytic converter to activate the sub catalyst at an early stage, thereby enabling exhaust gas purification immediately after the start. On the other hand, during high-load operation at medium and high speed rotation, exhaust gas is guided to the main passage, directly guided to the main catalytic converter via the main passage, and the exhaust gas is purified by the main catalyst. In this way, stable exhaust gas purification by the catalyst and avoidance of thermal deterioration of the catalyst (particularly, the secondary catalyst) are compatible with each other regardless of the operating state of the engine (see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-8-254158 (paragraph 0023-0024, FIG. 1)
[0005]
[Problems to be solved by the invention]
However, the conventional exhaust gas purification device has the following drawbacks. For example, during idling operation, exhaust gas from the engine is guided to the bypass passage and processed by the sub-catalytic converter, but during that time, exhaust gas does not flow through the main passage isolated from the bypass passage, and the main passage cools. End up. Thereafter, when the operating state of the engine changes from idling operation to high load operation, when the exhaust gas flow passage is switched from the bypass passage to the main passage by the switching valve, the exhaust gas from the engine passes through the main passage. Therefore, there was a problem that the temperature of the main catalytic converter was temporarily lowered by the cooled exhaust gas, and the exhaust gas purification performance was lowered. Similarly, when the engine is in a high load operation state, the exhaust gas flows into the main passage, and during that time, the exhaust gas does not flow through the bypass passage isolated from the main passage, and the bypass passage and the sub-catalytic converter are cooled. . Thereafter, as the engine changes to the idling operation state, even when the exhaust gas flow passage is switched from the main passage to the bypass passage by the switching valve, the sub-catalyst once cooled until the predetermined activation temperature is reached. During this time, there was a problem that the exhaust gas purification performance was temporarily lowered.
[0006]
An object of the present invention is to provide an exhaust gas purifying apparatus capable of switching between two exhaust gas passages, and can preheat or keep the other passage using the residual heat of the exhaust gas flowing through the one passage. An object of the present invention is to provide an engine exhaust gas purification device capable of preventing a temporary decrease in exhaust gas purification performance due to switching of a gas flow path as much as possible. It is another object of the present invention to provide an engine exhaust gas purifying apparatus having a more compact exhaust system structure than before.
[0007]
[Means for Solving the Problems]
  The present invention (claims 1-5)Is an exhaust gas purification device for an engine that uses a main catalytic converter to purify exhaust gas from the engine, and a main pipe for forming a part of the main exhaust passage that reaches the main catalytic converter from the engine; A cylindrical casing provided so as to surround the main pipe and forming a sub-exhaust passage having a substantially annular cross section between the main pipe and the main pipe; and a substantially annular sub-exhaust passage in the cylindrical casing A sub-catalyst disposed therein, and a switching valve mechanism for selectively supplying exhaust gas from the engine to either the main exhaust passage via the main pipe or the sub-exhaust passage in the cylindrical casing. PreparationIt is assumed that.
[0008]
  Assumption aboveAccording to the configuration, since the secondary exhaust passage (and the secondary catalyst) surrounds the main exhaust passage that passes through the main piping with the pipe wall of the main piping sandwiched, the gas by the switching valve mechanism is adopted. Regardless of the selection status of the flow path, the other exhaust passage where no gas flows can be preheated or kept warm by the heat (residual heat) of the exhaust gas flowing through one of the main exhaust passage and the sub exhaust passage (that is, Heat exchange is possible between main and sub exhaust passages). Therefore, even if the exhaust gas passes through the main exhaust passage or the sub exhaust passage (and the sub catalyst) where the exhaust gas has not flowed immediately after the switching of the gas flow path by the switching valve mechanism, the temperature of the exhaust gas is reduced. Avoided. Accordingly, immediately after switching the gas flow path, each catalyst (the catalyst held in the main catalytic converter and the sub catalyst) can exhibit the desired exhaust gas purification action, and the exhaust gas purification caused by the switching of the gas flow path. A temporary decline in performance can be prevented as much as possible. In addition, the main piping (main exhaust passage) is arranged at the center of the cross-axis cross section of the two-line polymerization structure, and the auxiliary exhaust passage and the auxiliary catalyst are arranged around it, so the piping configuration of the exhaust gas purification device is more compact than before. In addition, it is easy to route the main exhaust passage from the engine to the main catalytic converter as linearly as possible (that is, without unnecessarily curving the route). For this reason, during high engine load operation, exhaust resistance when exhaust gas is circulated through the main exhaust passage can be reduced, and engine performance can be improved.
[0009]
  The aboveThe switching valve mechanism is preferably arranged between the engine and the main pipe and the cylindrical casing, but may be arranged between the main pipe and the cylindrical casing and the main catalytic converter. Moreover, it is preferable that the heat capacity of the sub catalyst is smaller than the heat capacity of the main catalyst held in the main catalyst converter.
[0010]
  Claim 1The invention ofAn exhaust gas purification apparatus for an engine that uses a main catalytic converter to purify exhaust gas from the engine, the main piping for forming a part of the main exhaust passage reaching the main catalytic converter from the engine, A cylindrical casing provided so as to surround the main pipe and forming a sub-exhaust passage having a substantially annular cross section between the main pipe and the main pipe, and a substantially annular sub-exhaust passage in the cylindrical casing A sub-catalyst disposed, and a switching valve mechanism for selectively supplying exhaust gas from the engine to either the main exhaust passage via the main pipe or the sub-exhaust passage in the cylindrical casing. And
  The switching valve mechanism is arranged on the upstream side of the main pipe and the cylindrical casing and has a first and second valve holes formed therein; the first valve hole of the frame body; and the main pipe; Between the first induction housing that defines an airtight chamber that is a part of the main exhaust passage that passes through the main pipe, and the second exhaust hole between the second valve hole of the frame and the cylindrical casing. A second guide housing that defines a part of the hermetic chamber, and an open position that opens the first valve hole and a closed position that closes the first valve hole in the first guide housing are provided so as to be switchable. And a second valve provided to be switchable between an open position for opening the second valve hole and a closed position for closing the second valve hole in the second guide housing. A body and one of the first and second valve bodies is disposed in an open position Has a valve body link mechanism that switches the arrangement while linking both valve bodies so that the other is located at the closed position, and connects the first valve hole and the main pipe in the first guide housing. A retreat space that is retracted laterally with respect to the exhaust gas flow path is secured, and an opening position of the first valve body is set in the retreat space.And saidIn the second induction housing, a retreat space that is retracted in the lateral direction with respect to the exhaust gas flow path connecting the second valve hole and the cylindrical casing is secured, and the open position of the second valve body is located in the retreat space. Is set.
[0011]
According to this configuration, when one of the first and second valve bodies is switched from the closed position to the open position by the valve body link mechanism, the valve body is retracted to the corresponding retracting space in the guide housing. The Then, since the valve body does not stay in the exhaust gas flow path in the induction housing and completely retreats from the gas flow path, the valve body does not become an obstacle to the exhaust gas flow, and the exhaust resistance is reduced. The Further, while each valve body is disposed at the open position set in the retreat space, at least the valve body is not exposed to the hot exhaust gas flow. Therefore, it is possible to avoid each valve body from falling into an overheated state by intermittently switching the arrangement of each valve body.
[0012]
  Claim 2The invention ofClaim 1In the exhaust gas purifying apparatus for an engine according to claim 1, the first and second valve bodies are dish-shaped valve bodies that can be seated on the peripheral portions of the corresponding valve holes, and the valve body link mechanism includes: A first rotation shaft penetrating the first induction housing; a second rotation shaft penetrating the second induction housing; and a mechanism for synchronously rotating the first and second rotation shafts. The first valve body is supported by a first arm extending from the first rotation shaft, and the second valve body is supported by a second arm extending from the second rotation shaft. It is characterized by that.
[0013]
According to this configuration, the first and second valve bodies are made into a dish shape, and a configuration is adopted in which each valve body is supported by an arm extending from each of the first and second rotating shafts that are rotated synchronously. As a result, the sealing performance of the exhaust gas when each valve body is seated on the peripheral edge of the corresponding valve hole (that is, when it is disposed at the closed position) is enhanced.
[0014]
  Claim 3The invention ofAn exhaust gas purification apparatus for an engine that uses a main catalytic converter to purify exhaust gas from the engine, the main piping for forming a part of the main exhaust passage reaching the main catalytic converter from the engine, A cylindrical casing provided so as to surround the main pipe and forming a sub-exhaust passage having a substantially annular cross section between the main pipe and the main pipe, and a substantially annular sub-exhaust passage in the cylindrical casing A sub-catalyst disposed, and a switching valve mechanism for selectively supplying exhaust gas from the engine to either the main exhaust passage via the main pipe or the sub-exhaust passage in the cylindrical casing. And
  The switching valve mechanism is disposed on the upstream side of the main pipe and the cylindrical casing, and has a valve hole partition portion in which first and second valve holes are formed, and the intermediate position between the two valve holes. A frame body having a support portion and a partition wall portion projecting from the valve hole partitioning portion, and a first cover which covers the frame body and becomes a part of the main exhaust passage connecting the first valve hole and the main pipe. And a second airtight chamber which is a part of the sub exhaust passage connecting the second valve hole and the cylindrical casing is partitioned inside with the support portion and the partition wall portion of the frame interposed therebetween A drive shaft having a housing, a first arm that is rotatably supported by the support portion of the frame body and extends into the first hermetic chamber, and a second arm that extends into the second hermetic chamber, and the first arm A first valve body corresponding to the supported first valve hole; A second valve body corresponding to the second valve hole supported by the arm, and the first and second arms with respect to the drive shaft are one of the first and second valve bodies. When it arrange | positions in the open position which open | releases a corresponding valve hole, it is attached so that the other may be arrange | positioned in the obstruction | occlusion position which obstruct | occludes the valve hole corresponding to it.
[0015]
According to this configuration, the first and second valve bodies are respectively supported by the first and second arms extending from the common drive shaft, and the manner of attaching the first and second arms to the drive shaft is as described above. As a result, based on the turning operation of the drive shaft, the main exhaust passage or the sub exhaust passage can be selectively selected by the switching valve mechanism while synchronizing the switching of the arrangement of both valve bodies. Further, according to this configuration, the switching valve mechanism can be made compact.
[0016]
  Claim 4The invention ofClaim 3In the exhaust gas purifying apparatus for an engine according to claim 1, on each side of the partition wall portion of the frame body, the partition wall portion with respect to the exhaust gas flow path connecting the first valve hole and the main pipe in the first hermetic chamber A first evacuation space retracted in the direction toward the side, and a second evacuation space receded in the direction closer to the partition wall with respect to the flow path of the exhaust gas connecting the second valve hole and the cylindrical casing in the second airtight chamber. And the opening position of the first valve body is set in the first retraction space, and the opening position of the second valve body is set in the second retraction space. .
[0017]
According to this configuration, when one of the first and second valve bodies is switched from the closed position to the open position based on the rotation operation of the drive shaft, the valve body is placed in the retreat space of the corresponding hermetic chamber. Evacuated. Then, since the valve body does not stay in the exhaust gas flow path in the hermetic chamber and completely retreats from the gas flow path, the valve body does not become an obstacle to the exhaust gas flow, and the exhaust resistance is reduced. The Further, while each valve body is disposed at the open position set in the retreat space, at least the valve body is not exposed to the hot exhaust gas flow. Therefore, it is possible to avoid each valve body from falling into an overheated state by intermittently switching the arrangement of each valve body.
[0018]
  Claim 5The invention ofClaim 3 or 4In the exhaust gas purifying apparatus for an engine according to claim 1, the first and second valve bodies are dish-shaped valve bodies that can be seated on the peripheral portions of the corresponding valve holes.
[0019]
According to this configuration, since the first and second valve bodies are dish-shaped, the exhaust gas when each valve body is seated on the peripheral edge of the corresponding valve hole (that is, when the valve body is disposed at the closed position). Sealability is improved.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0021]
(Basic embodiment)
FIG. 1 shows a basic embodiment of an exhaust gas purification device. Exhaust gas discharged from the multi-cylinder engine 10 reaches the main catalyst converter 15 via the exhaust manifold 11, the switching valve mechanism 12, the sub-catalyst converter 13, and the vibration isolation mechanism 14 that collect the exhaust gas from each cylinder. After passing through the main catalytic converter 15, it is discharged into the atmosphere through a muffler (not shown). Although a gasoline engine is assumed as the engine 10, the present invention can be applied to a diesel engine.
[0022]
The sub-catalytic converter 13 located between the switching valve mechanism 12 and the main catalytic converter 15 includes a main pipe 13a located at the center thereof, a cylindrical casing 13b provided so as to surround the main pipe 13a, And a catalyst 16. The main pipe 13 a is a pipe that bears a part of the main passage (main exhaust passage) of the exhaust gas from the engine 10 to the main catalytic converter 15. Between the outer peripheral surface of the main pipe 13a and the inner peripheral surface of the cylindrical casing 13b, a sub-exhaust passage having an axially orthogonal cross section with respect to the central axis of the main pipe 13a is formed in a substantially annular shape (more preferably an annular shape). That is, the sub-catalytic converter 13 has a two-system overlapping piping structure in which the main exhaust passage is surrounded by the sub-exhaust passage. A sub-catalyst 16 is disposed in the substantially annular sub-exhaust passage, the main pipe 13a passes through the center of the sub-catalyst 16, and the rear end (outlet part) of the main pipe 13a is located behind the sub-catalyst 16. The appearance protrudes from the end face (note that this is shown enlarged in FIGS. 2 and 3).
[0023]
As shown in FIG. 1, the switching valve mechanism in which the inlet portion of the main pipe 13 a and the inlet portion of the auxiliary exhaust passage in the cylindrical casing 13 b are separated and each inlet portion is located upstream of the auxiliary catalytic converter 13. 12 is connected. On the other hand, the outlet part of the main pipe 13a and the outlet part of the auxiliary exhaust passage in the cylindrical casing 13b are integrated and connected as a common outlet part to the vibration isolating mechanism 14 located downstream of the auxiliary catalytic converter 13. .
[0024]
The switching valve mechanism 12 allows the exhaust gas from the engine 10 assembled in the exhaust manifold 11 to flow into two flow passages in the sub-catalytic converter 13 (that is, the main exhaust passage via the main pipe 13a and the sub-passage in the cylindrical casing 13b. This is a gas flow control mechanism for selectively supplying to either one of the exhaust passages). There are several design aspects of the switching valve mechanism 12, and each aspect will be described in detail later. The switching valve mechanism 12 is operatively connected to the valve drive control device 17. For example, the valve drive control device 17 is configured to open the throttle valve provided in the intake system, engine speed, radiator cooling water temperature, oxygen concentration in exhaust gas, exhaust gas temperature, catalyst temperature (that is, catalyst carrier temperature). The operation of the switching valve mechanism 12 is controlled based on various types of information reflecting the engine operating state such as (temperature).
[0025]
The vibration isolation mechanism 14 allows the exhaust gas that has passed through the sub-catalyst converter 13 to reach the main catalyst converter 15, while the vibration of the engine 10 is transmitted through the piping system of the exhaust gas purification device and thereafter the main catalyst converter 15. It is a buffer mechanism for blocking or mitigating transmission to the piping system.
[0026]
The main catalytic converter 15 is configured by accommodating a breathable ceramic carrier (for example, a cylindrical ceramic carrier having a honeycomb structure) carrying a catalytic material for purifying HC, CO, NOx and the like in exhaust gas in a cylindrical case. Has been.
[0027]
The sub-catalyst 16 is also composed of a gas-permeable ceramic carrier carrying a catalytic substance. The shape of the sub-catalyst 16 conforms to the shape of the sub-exhaust passage and forms a central hollow cylinder with a substantially annular cross section perpendicular to the axis. Yes. The sub-catalyst 16 has a smaller volume than the main catalyst held in the main catalyst converter 15 so that the heat capacity is relatively small. For this reason, even when the amount of heat provided by the exhaust gas is small, the sub-catalyst 16 can immediately rise in temperature and quickly reach a predetermined activation temperature.
[0028]
The embodiment of the present invention is further subdivided into a first example, a second example, and other examples according to the structural difference of the switching valve mechanism 12. The above-described basic embodiment (FIG. 1) shows a basic configuration common to the embodiments described below.
[0029]
(First embodiment)
2 to 4 show the main part of the exhaust gas purifying apparatus according to the first embodiment, and particularly FIG. 4 shows the switching valve mechanism of the first embodiment. As shown in each figure, the switching valve mechanism 12 disposed on the upstream side of the sub-catalytic converter 13 includes a frame body 21 having two valve holes, a branch pipe 22, a first induction housing 23, The second guide housing 24, the first valve body 25, and the second valve body 26 are provided at least.
[0030]
The frame body 21 has an inverted “<” shape in cross section, and the frame body 21 is formed with a first valve hole 21a and a second valve hole 21b. Each valve hole 21a, 21b has a circular shape, and the meat part (peripheral part) of the frame body 21 defining the peripheral edge of each valve hole functions as a valve seat. The branch pipe 22 is a pipe that branches the exhaust gas from the exhaust manifold 11 in two directions. One branch is connected to the first valve hole 21a, and the other branch is connected to the second valve hole 21b. Yes.
[0031]
The first guide housing 23 is a hollow covering material whose shape is set so as to guide the gas that has passed through the first valve hole 21a to the inlet of the main pipe 13a. The outlet-side opening end of the first guide housing 23 is joined to the inlet portion of the main pipe 13a, and is hermetically connected to the inlet portion of the main pipe 13a by welding the entire circumference of the joint portion. On the other hand, the opening end on the inlet side of the first guide housing 23 is joined to one side surface of the frame body 21 at a position surrounding the first valve hole 21a, and the entire body is welded to weld the frame body. 21 is hermetically connected. That is, the first guide housing 23 defines an airtight chamber that becomes a part of the main exhaust passage between the first valve hole 21a of the frame body and the inlet portion of the main pipe 13a. A retreat space S1 for the first valve body that is retracted in the lateral direction (downward in FIG. 4) with respect to the exhaust gas flow path is secured in the hermetic chamber.
[0032]
The second induction housing 24 is a hollow covering material whose shape is set so as to guide the gas that has passed through the second valve hole 21b to the inlet of the cylindrical casing 13b. The outlet side opening end of the second induction housing 24 is joined to the inlet portion of the cylindrical casing 13b, and is hermetically connected to the inlet portion of the cylindrical casing 13b by welding the entire circumference of the joining portion. On the other hand, the opening end on the inlet side of the second guide housing 24 is joined to one side surface of the frame body 21 at a position surrounding the second valve hole 21b, and the whole joint portion is welded to form the frame body. 21 is hermetically connected. That is, the second induction housing 24 defines an airtight chamber that becomes a part of the auxiliary exhaust passage between the second valve hole 21b of the frame body and the inlet portion of the cylindrical casing 13b. A retreat space S2 for the second valve body that is retracted in the lateral direction (upward in FIG. 4) with respect to the exhaust gas flow path is secured in the hermetic chamber.
[0033]
The first valve body 25 is a dish-shaped valve in the first induction housing 23 for opening and closing the first valve hole 21a of the frame body. The second valve body 26 is a dish-shaped valve in the second induction housing 24 for opening and closing the second valve hole 21b of the frame body. The first and second valve bodies 25 and 26 are operatively connected to the valve drive control device 17 via a valve body link mechanism. As shown in FIG. 4, the valve body link mechanism includes first and second rotating shafts 31 and 32 penetrating the guide housings 23 and 24, and first and second rotating shafts integrated with the respective rotating shafts in the respective guide housings. The first and second arms 33, 34, the first and second levers 35, 36 integrated with the rotary shafts outside the respective guide housings, and the link bar 37 for operatively connecting the levers 35, 36. And. The link bar 37 is reciprocated in a predetermined direction by an actuator (for example, an electromagnetic solenoid) in the valve drive control device 17. That is, the first and second rotating shafts 31 and 32 are synchronously rotated by the valve drive control device 17 via the link bar 37 and the first and second levers 35 and 36. The first and second levers 35 and 36 and the link bar 37 constitute a “mechanism for synchronously rotating the first and second rotating shafts 31 and 32”.
[0034]
First and second valve bodies 25 and 26 are fixed to the distal ends of the first and second arms 33 and 34, respectively. The mounting angle of the first and second arms 33 and 34 with respect to the first and second rotating shafts 31 and 32 is such that the first valve body 25 is disposed at the open position in the retreat space S1 of the first guide housing. When this is done, the second valve body 26 is disposed in a closed position that completely closes the second valve hole 21b (see FIG. 2), and the second valve body 26 is in an open position in the retreat space S2 of the second guide housing. The angle is set so that the first valve body 25 is disposed at the closed position where the first valve hole 21a is completely closed (see FIG. 3).
[0035]
Next, the operation of the exhaust gas purification apparatus of the first embodiment will be described.
During cold start of the engine 10 and idling operation (low load operation), as shown in FIG. 3, the valve drive control device 17 causes the first valve body 25 to be in a closed position where the first valve hole 21a is closed. At the same time, the second valve body 26 is disposed in the open position where the second valve body 26 is retracted into the retreat space S2 and the second valve hole 21b is completely opened. In the state of FIG. 3, the exhaust gas from the engine 10 enters the auxiliary exhaust passage via the second induction housing 24, passes through the auxiliary catalyst 16, returns to the main exhaust passage, and is guided to the main catalytic converter 15. .
[0036]
The sub-catalyst 16 quickly reaches the activation temperature due to the heat of the exhaust gas, and purifies the environmentally deteriorating substances (HC, CO, NOx, etc.) in the exhaust gas. Since the purification by the catalyst involves an exothermic reaction due to the oxidation of HC and CO, the exhaust gas that has passed through the sub-catalyst 16 is heated to a higher temperature than before the passage due to the reaction heat. This further increased exhaust gas contributes to preheating (that is, prewarming) of the main catalytic converter 15.
[0037]
In the state of FIG. 3, the exhaust gas does not flow through the main pipe 13a, but the heat of the exhaust gas flowing through the sub exhaust passage and the sub catalyst 16 surrounding the main pipe 13a passes through the pipe wall of the main pipe 13a. To the inner wall side of the main pipe 13a. Further, heat is transmitted from the main pipe 13 a to the first induction housing 23. As described above, when the exhaust gas flows through the sub exhaust passage of the sub catalytic converter 13, the heat of the exhaust gas is also transmitted to the main pipe 13a and the inner wall of the first induction housing 23. A secondary effect is brought about in that the inner wall of the main exhaust passage located in the center is preheated simultaneously.
[0038]
On the other hand, as shown in FIG. 2, when the engine 10 rotates at a medium to high speed (during high load operation), the first valve body 25 is retracted into the retreat space S <b> 1 by the valve drive control device 17. The second valve body 26 is disposed at a closed position for closing the second valve hole 21b. In the state of FIG. 2, the exhaust gas from the engine 10 enters the main pipe 13 a (main exhaust passage) via the first induction housing 23 and is directly led to the main catalytic converter 15.
[0039]
Since the main catalytic converter 15 is preheated during the low load operation, it has already reached near the activation temperature when the flow path is switched by the switching valve mechanism 12. Further, the temperature of the exhaust gas discharged from the engine 10 during the high load operation is generally higher than that during the low load operation. In addition, the main pipe 13a and the inner wall portion of the first induction housing 23 have the low load operation. It is warmed by preheating in time. Therefore, even immediately after the gas flow path is switched from the sub exhaust passage to the main exhaust passage, the exhaust gas from the engine 10 passes through the main exhaust passage composed of the first induction housing 23 and the main pipe 13a so that the temperature is increased. The temperature is not lowered and is led to the main catalytic converter 15 at a high temperature. Therefore, the main catalytic converter 15 can immediately purify environmentally deteriorating substances (HC, CO, NOx, etc.) in the exhaust gas.
[0040]
In the state of FIG. 2, the exhaust gas does not flow through the sub exhaust passage, but the heat of the exhaust gas flowing through the main pipe 13a located at the center of the sub catalyst converter 13 is transferred to the sub catalyst 16 via the pipe wall of the main pipe 13a. Is also transmitted. Further, heat is transmitted from the sub catalyst 16 to the cylindrical casing 13 b and the second induction housing 24. As described above, when the exhaust gas flows through the main exhaust passage of the sub-catalytic converter 13, the heat of the exhaust gas is also transmitted to the sub-catalyst 16, the cylindrical casing 13b, and the second induction housing 24, and as a result, the sub-catalyst. A secondary effect is achieved in that the inner wall portion of the auxiliary exhaust passage located on the outer peripheral side of the converter 13 is preheated simultaneously.
[0041]
According to the first embodiment, the following effects i) to e) can be obtained.
I. Since the sub-catalyst converter 13 located downstream of the switching valve mechanism 12 has a double pipe structure in which the main exhaust passage at the center of the cross section perpendicular to the axis is surrounded by the sub-exhaust passage, the exhaust gas flowing through one of the passages This heat (residual heat) can be effectively used for preheating (preliminary heating) of the other passage where no gas flows. As a result, regardless of the gas flow path switching operation by the switching valve mechanism 12, it is possible to always warm the main exhaust passage or the sub exhaust passage in which the exhaust gas does not flow. Immediately after the switching of the gas flow path by the switching valve mechanism 12, even if the exhaust gas passes through the main exhaust passage or the sub exhaust passage where the exhaust gas has not flowed until then, the temperature drop of the exhaust gas is almost prevented. Can do. Therefore, immediately after the switching of the gas flow path by the switching valve mechanism 12, the intended exhaust gas purification action can be exerted on the main catalyst and the sub catalyst 16 in the main catalytic converter 15.
[0042]
B. Since the sub-catalytic converter 13 has a double-pipe structure in which the main exhaust passage at the center of the cross section perpendicular to the axis is surrounded by the sub-exhaust passage, the main passage, the bypass passage, Compared to the case of a pipe configuration in which the exhaust gas purification devices are completely separated and independent, the exhaust gas purification device can be made compact overall.
[0043]
C. Since the sub-catalyst 16 is disposed inside the sub-exhaust passage that surrounds the main exhaust passage in the sub-catalyst converter 13, the main exhaust passage (more specifically, The path from the inlet of the branch pipe 22 through the first induction housing 23 to the outlet of the main pipe 13a can be made as close to a straight line as possible (see FIG. 2). Accordingly, it is possible to avoid an increase in exhaust resistance caused by the route setting of the main exhaust passage during high load operation of the engine, and to improve engine performance during high load operation.
[0044]
D. The retreat spaces S1 and S2 are secured in the first and second guide housings 23 and 24 constituting the switching valve mechanism 12, respectively, and the corresponding valve holes are completely formed in the first and second valve bodies 25 and 26, respectively. An opening position to be released was set in each of the evacuation spaces S1 and S2. For this reason, when one of the first and second valve bodies 25, 26 is switched from the closed position to the open position, the valve body is completely retracted from the (main or sub) exhaust passage, and inside the exhaust passage. Do not stay in For this reason, unlike the switching valve formed by coaxially connecting the two butterfly valves disclosed in the conventional example (Patent Document 1), the first or second valve bodies 25 and 26 disposed in the open position are provided. Exhaust resistance is reduced without becoming an obstacle to exhaust gas flow. Furthermore, when the valve bodies 25 and 26 are in the open state, the time for which the valve bodies are placed in the middle of the flow of the high-temperature exhaust gas can be shortened by retracting to the corresponding retreat spaces S1 and S2. The valve bodies 25 and 26 can be prevented from falling into an overheated state.
[0045]
E. Since the first and second valve bodies 25 and 26 are dish-shaped and can be seated on each valve seat portion of the frame body 21, the sealing performance of exhaust gas compared to the butterfly valve provided in the pipe Is excellent.
[0046]
(Second embodiment)
5 to 7 show the switching valve mechanism 12 of the exhaust gas purifying apparatus according to the second embodiment. As shown in each figure, the switching valve mechanism 12 disposed on the upstream side of the sub-catalytic converter 13 includes a frame body 41 having two valve holes, a branch pipe 42, a guide housing 43, and a first housing. At least a valve body 45 and a second valve body 46 are provided.
[0047]
The frame 41 has a substantially “T” cross section (see FIG. 5), and the frame 41 is formed with a first valve hole 41 a and a second valve hole 41 b. Each valve hole 41a, 41b has a circular shape, and the meat part (valve hole partitioning part 41c) of the frame body 41 partitioning the periphery of each valve hole functions as a valve seat. The frame body 41 further includes a support portion 41d and a partition wall portion 41e extending in the orthogonal direction from the valve hole partitioning portion 41c at an intermediate position between the valve holes 41a and 41b (see FIG. 7A). A drive shaft 47 described later is rotatably supported by the support portion 41d.
[0048]
As shown in FIG. 5, the branch pipe 42 is a pipe that branches the exhaust gas from the exhaust manifold 11 in two directions. One branch is connected to the first valve hole 41 a, and the other branch is the second branch. It is connected to the valve hole 41b.
[0049]
The guide housing 43 is a hollow covering material that covers the frame body 41, and its front side (inlet side) opening end is joined to the rear surface peripheral edge of the valve hole partitioning part 41c, and the entire circumference of the joint part. It is airtightly connected by welding. A first outlet-side opening end 43a and a second outlet-side opening end 43b are juxtaposed on the rear side (exit side) of the guide housing 43. The first outlet-side opening end 43a is joined to the inlet portion of the main pipe 13a, and is hermetically connected to the inlet portion of the main pipe 13a by welding the entire circumference of the joint portion. The second outlet side opening end 43b is joined to the inlet portion of the cylindrical casing 13b, and is hermetically connected to the inlet portion of the cylindrical casing 13b by welding the entire circumference of the joined portion.
[0050]
As shown in FIG. 5, the inside of the guide housing 43 is partitioned into two airtight chambers with the support portion 41d and the partition wall portion 41e of the frame housed therein. That is, the first valve hole 41a of the frame body and the inlet portion of the main pipe 13a are connected by the half of one side of the guide housing 43 corresponding to the first outlet side opening end 43a, the frame support portion 41d and the partition wall portion 41e. A first hermetic chamber is formed as a part of the main exhaust passage to be connected. Further, the second valve hole 41b of the frame body and the inlet portion of the cylindrical casing 13b are formed by one half of the guide housing 43 corresponding to the second outlet side opening end 43b, the frame support portion 41d and the partition wall portion 41e. A second airtight chamber is formed as a part of the sub exhaust passage connecting the two. Each side surface of the partition wall 41e that bisects the inside of the guide housing 43 is offset from the inner ends of the first and second valve holes 41a and 41b by a predetermined distance h. Thus, the partition wall 41e is retracted in the direction closer to the partition wall by the offset distance h with respect to the exhaust gas flow path connecting the first valve hole 41a and the first outlet side opening end 43a. A evacuation space S1 for the first valve body is secured. Further, the partition wall portion 41e is retracted in the direction closer to the partition wall by the offset distance h with respect to the exhaust gas flow path connecting the second valve hole 41b and the second outlet side opening end 43b on the second airtight chamber side. A retreat space S2 for the second valve body is secured.
[0051]
The first and second valve bodies 45 and 46 are dish-shaped valves for opening and closing the first valve holes 41a and 41b of the frame body, respectively. These valve bodies 45 and 46 are operatively connected to the valve drive control device 17 via a valve body link mechanism. In particular, as shown in FIGS. 6 and 7B, the valve body link mechanism includes a drive shaft 47 rotatably supported by the support portion 41d, a first arm 48 integrated with the shaft, and a first arm 48. 2 arms 49. The drive shaft 47 is operatively connected to an actuator (for example, a motor) in the valve drive control device 17, and is rotated in the forward and reverse directions by the actuator.
[0052]
The first and second arms 48 and 49 extend into the first and second hermetic chambers, respectively, and first and second valve bodies 45 and 46 are fixed to the distal ends of the arms, respectively. Yes. The mounting angle of the first and second arms 48 and 49 with respect to the common drive shaft 47 is such that when the first valve body 45 is disposed at the open position set in the retreat space S1, the second valve body 46 is provided. Is disposed at the closed position for completely closing the second valve hole 41b (see FIG. 5), and the first valve body 46 is disposed at the open position set in the retreat space S2. The angle is set so that the valve body 45 is disposed at a closed position that completely closes the first valve hole 41a.
[0053]
Next, the operation of the exhaust gas purification apparatus of the second embodiment will be described.
During cold start of the engine 10 and idling operation (during low load operation), the valve drive control device 17 causes the first valve body 45 to be disposed at a closed position where the first valve hole 41a is closed, and the second The valve body 46 is disposed in an open position (not shown) that retracts into the retreat space S2 and completely opens the second valve hole 41b. In this state, the exhaust gas from the engine 10 enters the auxiliary exhaust passage in the cylindrical casing 13b via the second valve hole 41b and the second outlet side opening end 43b of the induction housing 43, and the auxiliary catalyst 16 Is passed to the main exhaust passage and is guided to the main catalytic converter 15. In this case, the operation of the sub catalytic converter 13 and the main catalytic converter 15 is the same as that of the first embodiment.
[0054]
When the engine 10 is rotating at high speed (during high load operation), the first valve body 45 is retracted into the retreat space S1 by the valve drive control device 17 as shown in FIG. The second valve body 46 is disposed at the closed position where the second valve hole 41b is closed, while being disposed at the fully open position. In this state, the exhaust gas from the engine 10 enters the main pipe 13a (main exhaust passage) via the first valve hole 41a and the first outlet side opening end 43a of the guide housing 43, and is straightened as it is. Guided to the catalytic converter 15. In this case, the operation of the sub catalytic converter 13 and the main catalytic converter 15 is the same as that of the first embodiment.
[0055]
According to the second embodiment, it is possible to obtain the same effects as the above-mentioned (a), (b) and (c) in the first embodiment. In addition, the following effects can be obtained.
[0056]
Inside the guide housing 43 constituting the switching valve mechanism 12, retreat spaces S1 and S2 are secured on both sides of the partition wall 41e of the frame body, and the first and second valve bodies 45 and 46 correspond to the corresponding valves. An opening position for completely opening the hole was set in each of the evacuation spaces S1 and S2. For this reason, when one of the first and second valve bodies 45, 46 is switched from the closed position to the open position, the valve body is completely retracted from the (main or sub) exhaust passage and the inside of the exhaust passage. Don't stay in For this reason, unlike the switching valve formed by coaxially connecting the two butterfly valves disclosed in the conventional example (Patent Document 1), the first or second valve bodies 45 and 46 disposed in the open position are provided. It does not become an obstacle to the exhaust gas flow, and the exhaust resistance is reduced. Furthermore, when each valve body 45, 46 is in an open state, the time for which the valve body is placed in the middle of the flow of high-temperature exhaust gas can be shortened by retracting to the corresponding retreat spaces S1, S2. The valve bodies 45 and 46 can be prevented from falling into an overheated state.
[0057]
Since the first and second valve bodies 45 and 46 are dish-shaped and can be seated on each valve seat portion of the valve hole partitioning portion 41c of the frame body, compared to the butterfly valve provided in the pipe Excellent exhaust gas sealing performance. Further, since the valve bodies 45 and 46 are supported by the arms 48 and 49 and the arms are driven by the common drive shaft 47, the rotation of the drive shaft 47 according to the magnitude of the gas flow velocity or the like. The driving force can be set as appropriate, and it is easy to optimize the valve seat pressure when each valve element is seated on the valve seat.
[0060]
【The invention's effect】
As described above in detail, according to the exhaust gas purifying apparatus of the present invention, in the exhaust gas purifying apparatus capable of switching the two exhaust gas passages (main and sub exhaust passages), the exhaust gas flowing in one passage The other passage can be preheated or kept warm by using the remaining heat, and a temporary deterioration of the exhaust gas purification performance due to switching of the gas flow passage can be prevented as much as possible. Further, the structure of the exhaust system can be made more compact than before.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of a basic embodiment of an exhaust gas purification device.
FIG. 2 is a cross-sectional view showing a main part of the exhaust gas purifying apparatus according to the first embodiment.
FIG. 3 is a cross-sectional view showing a main part of the exhaust gas purification apparatus of the first embodiment.
FIG. 4 is a cross-sectional view showing a switching valve mechanism of the first embodiment.
FIG. 5 is a cross-sectional view showing a switching valve mechanism of a second embodiment.
6 is a cross-sectional view taken along line XX in FIG.
7A is a schematic perspective view of a frame constituting the switching valve mechanism of the second embodiment, and FIG. 7B is a schematic perspective view of a valve body link mechanism constituting the switching valve mechanism.
[Explanation of symbols]
  DESCRIPTION OF SYMBOLS 10 ... Engine, 12 ... Replacement valve mechanism, 13 ... Catalytic converter, 13a ... Main piping, 13b ... Cylindrical casing, 15 ... Main catalytic converter, 16 ... Sub catalyst, 21 ... Frame, 21a ... First valve hole, 21b ... second valve hole, 23 ... first guide housing, 24 ... second guide housing, 25 ... first valve body, 26 ... second valve body, 31, 32 ... first and second rotations 1st and 2nd arm, 41 ... Frame body, 41a ... 1st valve hole, 41b ... 2nd valve hole, 41c ... Valve hole partition part, 41d ... Support part, 41e ... Partition , 43 ... induction housing, 45 ... first valve body, 46 ... second valve body, 47 ... drive shaft, 48, 49 ... first and second arms, S1 ... retraction space for the first valve body , S2... Retreat space for the second valve body.

Claims

An engine exhaust gas purification device that uses a main catalytic converter to purify exhaust gas from an engine,
Main piping for forming part of the main exhaust passage from the engine to the main catalytic converter;
A cylindrical casing provided so as to surround the main pipe and forming a sub-exhaust passage having a substantially annular cross section between the main pipe and the axis orthogonal to the main pipe;
A sub-catalyst disposed in a substantially annular sub-exhaust passage in the cylindrical casing;
A switching valve mechanism for selectively supplying exhaust gas from the engine to either the main exhaust passage via the main pipe or the sub exhaust passage in the cylindrical casing ,
The switching valve mechanism is
A frame that is arranged on the upstream side of the main pipe and the cylindrical casing and in which the first and second valve holes are formed;
A first induction housing that divides an airtight chamber serving as a part of a main exhaust passage passing through the main pipe between the first valve hole of the frame and the main pipe;
A second induction housing that divides an airtight chamber serving as a part of the auxiliary exhaust passage between the second valve hole of the frame and the cylindrical casing;
A first valve body provided in a switchable arrangement between an open position for opening the first valve hole and a closed position for closing the first valve hole in the first guide housing;
A second valve body provided so as to be switchable between an open position for opening the second valve hole and a closed position for closing the second valve hole in the second guide housing;
A valve body link mechanism that switches the arrangement while linking both valve bodies so that when one of the first and second valve bodies is disposed in the open position, the other is disposed in the closed position. ,
In the first induction housing, a retreat space retracted laterally with respect to the exhaust gas flow path connecting the first valve hole and the main pipe is secured, and the open position of the first valve body is located in the retreat space. Is set,
In the second induction housing, a retreat space that is retracted laterally with respect to the exhaust gas flow path connecting the second valve hole and the cylindrical casing is secured, and the second valve body is opened in the retreat space. An exhaust gas purification device for an engine, characterized in that a position is set.

The first and second valve bodies are dish-shaped valve bodies that can be seated on the peripheral edge portions of the corresponding valve holes, and the valve body link mechanism has a first rotation that passes through the first guide housing. A moving shaft; a second rotating shaft penetrating the second guide housing; and a mechanism for synchronously rotating the first and second rotating shafts, and extending from the first rotating shaft. The first valve body is supported by a first arm, and the second valve body is supported by a second arm extending from the second rotation shaft. Engine exhaust gas purification device.

An engine exhaust gas purification device that uses a main catalytic converter to purify exhaust gas from an engine,
Main piping for forming part of the main exhaust passage from the engine to the main catalytic converter;
A cylindrical casing provided so as to surround the main pipe and forming a sub-exhaust passage having a substantially annular cross section between the main pipe and the axis orthogonal to the main pipe;
A sub-catalyst disposed in a substantially annular sub-exhaust passage in the cylindrical casing;
A switching valve mechanism for selectively supplying exhaust gas from the engine to either the main exhaust passage via the main pipe or the sub exhaust passage in the cylindrical casing,
The switching valve mechanism is
It is arranged upstream of the main pipe and the cylindrical casing, and has a valve hole partition part formed with first and second valve holes, and protrudes from the valve hole partition part at an intermediate position between the two valve holes. A frame having a support part and a partition part provided;
The secondary exhaust that covers the frame and connects the first valve hole and the main pipe and connects the first valve chamber and the cylindrical casing. A guide housing in which a second hermetic chamber serving as a part of the passage is partitioned inside with the support portion and the partition wall portion of the frame interposed therebetween;
A drive shaft having a first arm that is rotatably supported by the support portion of the frame and extends into the first hermetic chamber; and a second arm that extends into the second hermetic chamber;
A first valve body corresponding to the first valve hole supported by the first arm;
A second valve body corresponding to the second valve hole supported by the second arm,
When the first and second arms are arranged in an open position where one of the first and second valve bodies opens the corresponding valve hole with respect to the drive shaft, the other corresponds to the corresponding valve hole. An exhaust gas purifying device for an engine, wherein the exhaust gas purifying device is mounted so as to be disposed at a closed position where the engine is closed.

On each side of the partition wall portion of the frame body, a first retreat space receding in a direction closer to the partition wall portion with respect to the exhaust gas flow path connecting the first valve hole and the main pipe in the first hermetic chamber, In addition, a second evacuation space that is retracted in the direction closer to the partition wall portion with respect to the exhaust gas flow path connecting the second valve hole and the cylindrical casing in the second airtight chamber is secured, and the interior of the first evacuation space is 4. The engine exhaust gas according to claim 3, wherein an opening position of the first valve body is set in the second evacuation space, and an opening position of the second valve body is set in the second retreat space. Purification equipment.

5. The engine exhaust gas purification according to claim 3, wherein each of the first and second valve bodies is a dish-shaped valve body that can be seated on a peripheral portion of a valve hole corresponding to each of the first and second valve bodies. apparatus.