JP2004278401A

JP2004278401A - Engine exhaust-emission cleaning device

Info

Publication number: JP2004278401A
Application number: JP2003070516A
Authority: JP
Inventors: Akinori Wakasa; 章則若狭
Original assignee: Mazda Motor Corp
Current assignee: Mazda Motor Corp
Priority date: 2003-03-14
Filing date: 2003-03-14
Publication date: 2004-10-07

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine exhaust-emission cleaning device in which a catalytic converter is installed solidly and compactly, while preventing occurrence of exhaust gas interference. <P>SOLUTION: In the exhaust-emission cleaning device, a corn member 24 constitutes the upstream side of a catalyst case 22 of an auxiliary catalytic converter 16, and 1st-4th independent exhaust pipes 11-14 are made of pipe members independently conducting exhaust gas from respective cylinders. The downstream end part of the exhaust pipes 11-14 are inserted in the corn member 24. The inside space of the corn member 24 is partitioned into two spaces S1, S2 by means of a 1st partition plate 31. The upstream end part of the 1st partition plate 31 is inserted by a predetermined amount between downstream end parts of the exhaust pipes 11-14. In this case, the upstream end part of the partition plate 31 is inserted by a set of independent exhaust pipes of cylinders, in which exhaust processes are separated, that is, so as to partition the 1st and the 4th independent exhaust pipes 11, 14 and a set of the 2nd and the 3rd independent exhaust pipes 12, 13 to respective sets. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、エンジンの排気浄化装置、詳しくは多気筒エンジンの本体の近傍に触媒コンバータが配置されたエンジンの排気浄化装置に関し、エンジンの排気浄化技術の分野に属する。
【０００２】
【従来の技術】
近年、多気筒エンジンの排気系に排気浄化用の触媒コンバータを配置する場合、該触媒コンバータをエンジン本体に近接配置して浄化効率を高め、かつ、各気筒から排出される排気ガスの干渉を防止して出力向上を図ることが可能な排気マニホールドが提案されており、その一例として、例えば特許文献１に記載のものがある。
【０００３】
この排気マニホールドでは、直列４気筒エンジンの各気筒にそれぞれ連通する４本の分岐管の下流端が、排気行程が連続しない気筒同士の組合せで２本の１次集合管に集合され、さらに該１次集合管の下流端が、１本の第１パイプに集合されている。そして、該第１パイプに内部空間を２つの通路に区画する第１仕切り板が設けられると共に、該第１パイプの下流端に触媒コンバータが連結されている。さらに、該触媒コンバータの下流側に連結された第２パイプに、内部空間を２つの通路に区画する第２仕切り板が設けられている。
【０００４】
これにより、触媒コンバータがエンジン本体に近接して配置されているから、各気筒から排出された高温の排気ガスによって該触媒コンバータにおける排気ガスの浄化が効率的に行われるようになる。その上で、第１及び第２仕切り板で排気ガスが流通する通路を区画したことにより、各気筒から排出された排気ガスは、排気行程が連続しない気筒同士の組合せで触媒コンバータを通過しながら下流側に流通するようになるから、排気干渉が防止されてエンジンの出力向上が図られるようになる。
【０００５】
【特許文献１】
特開平９−２２２０１４号公報（第３頁、図１）
【０００６】
【発明が解決しようとする課題】
ところで、上記のような排気マニホールド構造では、各分岐管と第１パイプとの間に２本の１次集合管が介在するため排気系が長大化・大型化することとなり、排気系のコンパクト化を阻害することがある。
【０００７】
一方、排気系のコンパクト化のため前述したような１次集合管を省略して各分岐管と下流側の触媒コンバータの触媒ケースとを連結する場合において、気筒の熱伸縮等に対する耐久性向上のため、剛性に優れた連結構造が望まれている。
【０００８】
そこで、本発明は、以上の現状に鑑み、排気干渉を防止しつつ、触媒コンバータがコンパクトかつ堅固に配設されたエンジンの排気浄化装置を提供することを課題とする。
【０００９】
【課題を解決するための手段】
上記課題を解決するため、本発明は次のように構成したことを特徴とする。
【００１０】
まず、請求項１に記載の発明は、多気筒エンジンの本体に連結されて各気筒からの排気ガスをそれぞれ独立して案内する複数の独立排気管部と、該独立排気管部の下流端に連結されて内部にモノリス構造の触媒担体を収納した触媒ケースと、該触媒ケースの下流端に連結された下流側排気管部とを有するエンジンの排気浄化装置に関するもので、上記触媒ケースの上流部に、各独立排気管部からそれぞれ排出される各気筒からの排気ガスを排気行程が連続しないもの同士集合させて触媒担体に導入する仕切り壁が設けられていると共に、上記各独立排気管部の下流端部は断面形状が略扇形のパイプ状に形成されて、触媒ケースの略円筒状とされた上流端部に内嵌されており、かつ、上記仕切り壁の上流端部は、排気行程が連続しない気筒に対応する独立排気管部の組ごとに区画するように、独立排気管部のパイプ状下流端部の間に所定量挿入されていることを特徴とする。
【００１１】
この発明によれば、各気筒から触媒ケースの上流端ないし触媒担体の下流端までの区間において、排気行程が連続しない気筒から排出される排気ガス同士が分離されて流通するから、排気干渉が効果的に防止されてエンジンの出力向上が実現される。
【００１２】
また、集合管が介在する従来の構造と異なり、触媒ケースの上流部と仕切り壁とで各独立排気管部からそれぞれ排出される各気筒からの排気ガスを排気行程が連続しないもの同士集合させる構造であるから、排気系の長大化・大型化が回避され、排気系のコンパクト化並びに低コスト化が図られる。
【００１３】
そして、独立排気管部の下流端部が触媒ケースの上流端部に内嵌されると共に、仕切り壁の上流端部が独立排気管部側に所定量挿入される構造であるから、独立排気管部と触媒ケースとの連結部位が堅固な多層構造となり、当該部位の剛性が向上する。したがって、気筒の熱伸縮等に対する耐久性に優れた排気系が実現される。
【００１４】
さらに、独立排気管部に薄肉つまり小熱容量のパイプ部材を用いることができるから、排気ガスが高温状態で触媒担体に導入されることとなり、エンジンの冷間始動時等に触媒担体の昇温が速やかとなって早期活性化が図られる。
【００１５】
次に、請求項２に記載の発明は、上記請求項１に記載の排気浄化装置において、各独立排気管部の下流端部と、触媒ケースの上流端部及び仕切り壁の上流端部とは、それぞれ溶接によって固定されていることを特徴とする。
【００１６】
この発明によれば、各部材が溶接によって固定されることで連結部位は一層堅固となり、当該部位の剛性がさらに向上する。
【００１７】
そして、一般的に厚肉であるため熱容量が大きいフランジを介さない連結方式であるから、排気系における熱容量のいたずらな増加を招くことはない。したがって、エンジンの冷間始動時等に触媒担体の昇温が一層速やかとなってさらなる早期活性化が図られる。
【００１８】
また、請求項３に記載の発明は、上記請求項１または請求項２に記載の排気浄化装置において、触媒ケースの下流部から下流側排気管部にわたり、触媒担体より下流側の内部空間を区画する仕切り壁が上流側の仕切り壁と同じ向きで設けられていることを特徴とする。
【００１９】
この発明によれば、排気系における触媒ケースより下流側の所定箇所まで、排気行程が連続しない気筒から排出される排気ガス同士が分離されて流通するようになるから、排気干渉の防止がより良好に達成される。併せて、排気脈動効果が良好に維持されるメリットもある。
【００２０】
【発明の実施の形態】
以下、本発明の実施の形態に係るエンジンの排気浄化装置について説明する。
【００２１】
この排気浄化装置は直列４気筒エンジンに適用されている。すなわち、図１に示すように、エンジン本体１の上部を構成するシリンダヘッド１ａの一側面に、図示しない第１〜第４気筒に連通する開口を上流端に有した第１〜第４独立排気管１１〜１４が、エンジン取付用フランジ１５を介して連結されている。また、符号Ａで示すように、該独立排気管１１〜１４の下流端に副触媒コンバータ１６が傾斜状態で連結されると共に、符号Ｂで示すように、該副触媒コンバータ１６の下流端に下流側排気管１７が連結されている。そして、該下流側排気管１７の下流端に主触媒コンバータ１８が連結されている。
【００２２】
これにより、各気筒から排出された排気ガスは、各独立排気管１１〜１４に案内されて副触媒コンバータ１６に導入され、該副触媒コンバータ１６によって浄化されたのち、下流側排気管１７に案内されて主触媒コンバータ１８に導入され、該主触媒コンバータ１８によって浄化される。
【００２３】
薄肉のパイプ部材からなる各独立排気管１１〜１４は、一端側つまりエンジン本体１側は略円形断面とされる一方、他端側つまり副触媒コンバータ１６側は略扇形断面となるように形成されており（後述する図３及び図４参照）、エンジン取付用フランジ１５から副触媒コンバータ１６までにわたり、下流側が平面視で気筒列の中央付近に互いに寄り添うように湾曲配置されている。
【００２４】
図１及び図２に示すように、副触媒コンバータ１６は、触媒担体２１と、該触媒担体２１を収納する触媒ケース２２とを有している。
【００２５】
触媒担体２１は、円柱状とされた断面ハニカム状のセラミック製モノリス体で、軸心方向つまり排気ガスの流通方向に沿って平行に延びる多数の細孔を有すると共に、白金等の貴金属成分を含む触媒物質を担持している。また、触媒担体２１の外周面には保持部材２３が巻き付けられている。この保持部材２３はセラミックファイバ等をマット状に成形したもので、固有の耐熱性を有しつつ触媒担体２１を触媒ケース２２内の所定位置に保持する。
【００２６】
触媒ケース２２は、上流部を構成するコーン部材２４と下流部を構成する本体部材２５とを有している。コーン部材２４は、上流側に向かって次第に径が小さくなるコーン状とされている。また、本体部材２５は、略円筒状とされた円筒部２５ａと下流側に向かって次第に径が小さくなるコーン部２５ｂとからなり、円筒部２５ａに保持部材２３を介して触媒担体２１を収納している。なお、コーン部材２４と本体部材２５とはそれぞれ２分割体とされ、溶接によってそれぞれ一体化されている。さらに、符号Ｃで示すように、コーン部材２４の下流端部と本体部材２５の上流端部との接続には、一般的な溶接継手構造が適用されている。
【００２７】
そして、コーン部材２４には、該コーン部材２４の概ね全長にわたる内部空間を２つの空間Ｓ１，Ｓ２に区画する第１仕切り板３１が設けられている。この第１仕切り板３１は、外形がコーン部材２４の内周面に概ね沿うと共に下流端部が触媒担体２１の上流側端面の近傍まで延びる形状とされている。
【００２８】
第１仕切り板３１の下流端部と触媒担体２１の上流側端面との間には、隙間ｇ１が設けられている。この隙間ｇ１は第１仕切り板３１の熱伸縮を考慮して設けられたもので、該第１仕切り板３１が、排気干渉の防止のため触媒担体２１の上流側の空間を２つの空間Ｓ１，Ｓ２に極力区画し、かつ、熱膨張時にも触媒担体２１の上流側端面に当接して損傷させないような、最小限の寸法に設定されている。
【００２９】
次に、第１〜第４独立排気管１１〜１４と触媒ケース２２の上流部を構成するコーン部材２４との特徴的な連結構造について説明する。
【００３０】
まず、符号Ａで示すように、各独立排気管１１〜１４の下流端部は、コーン部材２４の上流端部に所定量だけ内嵌されている。すなわち、図３及び図４に示すように、コーン部材２４の略円筒状とされた上流端部に、第１〜第４独立排気管１１〜１４のそれぞれ略扇形の下流端部が概ね隙間なく挿入されている。
【００３１】
さらに、本実施の形態に係るエンジンの点火順序は一般的な第１気筒、第３気筒、第４気筒、第２気筒の順であることから、第１仕切り板３１の上流端部は、排気行程が連続しない第１及び第４気筒に対応する第１及び第４独立排気管１１，１４を流通する排気ガスと、第２及び第３気筒に対応する第２及び第３独立排気管１２，１３を流通する排気ガスとを区画して集合するように、第１及び第４独立排気管１１，１４の組と第２及び第３独立排気管１２，１３の組との間に所定量挿入されている。つまり、第１及び第４独立排気管１１，１４の下流側は空間Ｓ１に連通する一方、第２及び第３独立排気管１２，１３の下流側は空間Ｓ２に連通するようになる（図１及び図２参照）。
【００３２】
そして、図３において符号Ｄで示すように、各独立排気管１１〜１４の外周面とコーン部材２４の上流側端面との溶接、及び、図４において符号Ｅで示すように、各独立排気管１１〜１４の下流側端面とコーン部材２４の内周面との溶接により、該独立排気管１１〜１４は触媒ケース２２に固定されている。
【００３３】
また、図４において符号Ｆ，Ｆで示すように、隣接する第１及び第４独立排気管１１，１４、そして、第２及び第３独立排気管１２，１３は、下流側端面を介した溶接によって固定されている。
【００３４】
さらに、符号Ｇ，Ｇで示すように、第１仕切り板３１の両側面と各独立排気管１１〜１４の下流側端面との溶接により、該第１仕切り板３１は各独立排気管１１〜１４ひいては触媒ケース２２に固定されている。
【００３５】
次に、図１及び図２に符号Ｂで示すように、本体部材２５のコーン部２５ｂの下流端部に下流側排気管１７の上流端部が所定量内嵌され、コーン部２５ｂの下流側端面と下流側排気管１７の外周面との溶接により、下流側排気管１７は触媒ケース２２に固定されている。
【００３６】
そして、図１、図２、及び図５に示すように、下流側排気管１７には、該下流側排気管１７の大部分の内部空間を所定範囲にわたって２つの空間Ｓ１′，Ｓ２′に区画する第２仕切り板３２が設けられている。この第２仕切り板３２は前述した第１仕切り板３１と同じ向きで配設され、かつ、外形が下流側排気管１７の内周面と本体部材２５のコーン部２５ｂの内周面とに概ね沿うと共に、上流端部が触媒担体２１の下流側端面の近傍まで延びる形状とされ、両側端面を介して下流側排気管１７に溶接によって固定されている。なお、第２仕切り板３２の下流端部位置は、排気脈動効果を良好に維持可能に設定されている。
【００３７】
また、第２仕切り板３２の上流端部と触媒担体２１の下流側端面との間には、隙間ｇ２が設けられている。この隙間ｇ２は、前述した第１仕切り板３１の場合の隙間ｇ１と同様の理由に基いて設けられている。
【００３８】
次に、この排気浄化装置の作用を説明する。
【００３９】
各気筒から排出された排気ガスは、各気筒に対応する第１〜第４独立排気管１１〜１４によってそれぞれ案内され、副触媒コンバータ１６の触媒ケース２２の上流部を構成するコーン部材２４まで分離されて流通する。
【００４０】
そして、コーン部材２４の内部の空間Ｓ１において、排気行程が連続しない気筒に対応するもの同士である第１独立排気管１１と第４独立排気管１４とから排出される排気ガスが１つに集合される一方、同じく空間Ｓ２において、排気行程が連続しない気筒に対応するもの同士である第２独立排気管１２と第３独立排気管１３とから排出される排気ガスが集合される。２つに集合された排気ガスは、第１仕切り板３１によって区画された空間Ｓ１，Ｓ２に沿ってそれぞれ良好に分離された状態でさらに下流側に流通する。
【００４１】
次いで、コーン部材２４の内部は触媒担体２１の上流側端面の近傍まで第１仕切り板３１によって２つの空間Ｓ１，Ｓ２に区画されているから、排気ガスがその流通方向に沿って平行に延びる多数の細孔を有する触媒担体２１を通過する場合にも、排気ガスは排気行程が連続しない気筒に対応するもの同士の組合せで良好に２つに分離された状態でさらに下流側に流通する。
【００４２】
そして、触媒担体２１の下流側端面近傍から下流側に向かって所定位置まで、本体部材２５のコーン部２５ｂの内部及び下流側排気管１７の内部は第１仕切り板３１と同じ向きで設けられた第２仕切り板３２によって２つの空間Ｓ１′，Ｓ２′に区画されているから、これらの空間Ｓ１′，Ｓ２′は、前述した上流側の空間Ｓ１，Ｓ２にそれぞれ連通することになる。すなわち、排気ガスは触媒担体２１を通過後も引き続き良好に２つに分離された状態で空間Ｓ１′，Ｓ２′を流通したのち、第２仕切り板３２の下流端部以降の箇所で１つに集合されて下流側の主触媒コンバータ１８に導入される。
【００４３】
このようにして、第１及び第２仕切り板３１，３２の配設により、排気系における副触媒コンバータ１６の下流側の所定箇所まで、排気行程が連続しない気筒から排出される排気ガス同士が分離されて流通するようになるから、所定の排気脈動効果が維持された上で、排気干渉が良好に防止されることになり、エンジンの出力向上が実現される。
【００４４】
その場合、集合管が介在する従来の構造と異なり、触媒ケース２２の上流部を構成するコーン部材２４と第１仕切り板３１とで各独立排気管１１〜１４からそれぞれ排出される各気筒からの排気ガスを排気行程が連続しないもの同士集合させる構造であるから、排気系の長大化・大型化が回避され、排気系のコンパクト化並びに低コスト化が図られる。
【００４５】
また、各独立排気管１１〜１４とコーン部材２４との連結に際し、各独立排気管１１〜１４の略扇形の下流端部は、コーン部材２４の略円筒状の上流端部に所定量内嵌されている。また、第１仕切り板３１の上流端部が第１及び第４独立排気管１１，１４の組と第２及び第３独立排気管１２，１３の組との間に所定量挿入されている。そして、各独立排気管１１〜１４は溶接によって触媒ケース２２に固定されると共に、第１仕切り板３１は溶接によって各独立排気管１１〜１４ひいては触媒ケース２２に固定されている。
【００４６】
すなわち、各独立排気管１１〜１４と触媒ケース２２との連結部位には、図３及び図４に符号Ｈで示すように、略円筒状の上流端部を有するコーン部材２４と略扇形の下流端部を有する各独立排気管１１〜１４とからなる２層構造、及び、符号Ｉで示すように、第１及び第４独立排気管１１，１４の組と第２及び第３独立排気管１２，１３の組とで第１仕切り板３１を挟持してなる３層構造等の溶接を介した堅固な多層構造が実現され、連結部位の剛性が効果的に向上する。したがって、気筒の熱伸縮等に対する耐久性に優れる排気系が実現される。
【００４７】
また、薄肉つまり小熱容量のパイプ部材からなる第１〜第４独立排気管１１〜１４によって各気筒から排出される排気ガスを副触媒コンバータ１６に案内することにより、排気ガスが高温状態で触媒担体２１に導入されるから、例えばエンジンの冷間始動時等に触媒担体２１の昇温が速やかとなって早期に活性化され、浄化性能が向上する。
【００４８】
さらに、一般的に厚肉であるため熱容量が大きいフランジを介して各独立排気管１１〜１４を触媒ケース２２に連結する方式ではないから、排気系における熱容量のいたずらな増加を招くことはない。したがって、触媒担体２１の昇温が一層速やかとなってさらに早期活性化が図られる。
【００４９】
そして、副触媒コンバータ１６の早期活性化により排気ガスは速やかに昇温されるため、この昇温された排気ガスは後段の主触媒コンバータ１８の浄化性能を向上することになる。
【００５０】
なお、上記実施の形態では、本発明は直列４気筒エンジンに適用されていたが、これに限定されることはなく、直列６気筒エンジン等、幅広い多気筒エンジンにも適用可能である。
【００５１】
また、上記実施の形態では、図４において符号Ｆ…Ｆで示すように、第１仕切り板３１の上流端は各独立排気管１１〜１４の下流端に溶接によって固定されていたが、この溶接を省略して第１仕切り板３１を第１及び第４独立排気管１１，１４の組と第２及び及び第３独立排気管１２，１３の組とで挟み込んで保持するようにしてもよい。
【００５２】
また、上記実施の形態では、触媒ケース２２において、コーン部材２４と本体部材２５とはそれぞれ２分割体であったが、一体物であってもよい。そして、コーン部材２４と本体部材２５とは溶接によって接続されていたが、図６に符号Ｊで示すように、コーン部材２４′の下流端部と本体部材２５′の上流端部とを所定形状に折曲加工し、これらの端部を係合させた上で、かしめ加工によって接続してもよい。さらに、コーン部材と本体部材とが一体化された触媒ケースを用いてもよい。
【００５３】
【発明の効果】
以上説明したように、本発明は、排気干渉を防止しつつ、触媒コンバータがコンパクトかつ堅固に配設されたエンジンの排気浄化装置を提供する。すなわち、本発明は多気筒エンジンの本体の近傍に触媒コンバータが配置されたエンジンの排気浄化装置に関し、エンジンの排気浄化技術の分野に広く好適である。
【図面の簡単な説明】
【図１】本発明の実施の形態に係るエンジンの排気浄化装置を示す概略側面図である。
【図２】図１のＷ−Ｗ線による矢視図である。
【図３】図１のＸ−Ｘ線による断面図である。
【図４】図１のＹ−Ｙ線による断面図である。
【図５】図１のＺ−Ｚ線による断面図である。
【図６】触媒ケースにおけるコーン部材と本体部材との別なる接続構造を示す要部断面図である。
【符号の説明】
１エンジン本体
１１〜１４第１〜第４独立排気管（独立排気管部）
１７下流側排気管（下流側排気管部）
２１触媒担体
２２触媒ケース
３１第１仕切り板（仕切り壁）
３２第２仕切り板（仕切り壁）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exhaust gas purifying apparatus for an engine, and more particularly to an exhaust gas purifying apparatus for an engine in which a catalytic converter is arranged near a main body of a multi-cylinder engine, and belongs to the field of engine exhaust purifying technology.
[0002]
[Prior art]
In recent years, when a catalytic converter for purifying exhaust gas is arranged in the exhaust system of a multi-cylinder engine, the catalytic converter is arranged close to the engine body to improve purification efficiency and prevent interference of exhaust gas discharged from each cylinder. An exhaust manifold capable of improving the output has been proposed, and an example thereof is disclosed in Patent Document 1 as an example.
[0003]
In this exhaust manifold, the downstream ends of the four branch pipes respectively communicating with the respective cylinders of the in-line four-cylinder engine are gathered into two primary collecting pipes in a combination of cylinders whose exhaust strokes are not continuous. The downstream end of the next collecting pipe is collected into one first pipe. A first partition plate for dividing the internal space into two passages is provided in the first pipe, and a catalytic converter is connected to a downstream end of the first pipe. Further, a second partition plate that partitions the internal space into two passages is provided in a second pipe connected to the downstream side of the catalytic converter.
[0004]
Thus, since the catalytic converter is disposed close to the engine body, the exhaust gas in the catalytic converter is efficiently purified by the high-temperature exhaust gas discharged from each cylinder. In addition, since the first and second partition plates partition the passage through which the exhaust gas flows, the exhaust gas discharged from each cylinder passes through the catalytic converter in a combination of cylinders whose exhaust strokes are not continuous. Since the fuel flows downstream, exhaust interference is prevented and the output of the engine is improved.
[0005]
[Patent Document 1]
JP-A-9-222014 (page 3, FIG. 1)
[0006]
[Problems to be solved by the invention]
By the way, in the exhaust manifold structure as described above, since two primary collecting pipes are interposed between each branch pipe and the first pipe, the exhaust system becomes large and large, and the exhaust system is made compact. May be inhibited.
[0007]
On the other hand, in the case where the primary collecting pipe as described above is omitted to reduce the size of the exhaust system and each branch pipe is connected to the catalyst case of the downstream catalytic converter, the durability of the cylinder against thermal expansion and contraction is improved. Therefore, a connection structure having excellent rigidity is desired.
[0008]
In view of the above situation, an object of the present invention is to provide an exhaust gas purifying apparatus for an engine in which a catalytic converter is arranged compactly and firmly while preventing exhaust interference.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention is characterized in that it is configured as follows.
[0010]
First, the invention according to claim 1 includes a plurality of independent exhaust pipe portions connected to a main body of a multi-cylinder engine and independently guiding exhaust gas from each cylinder, and a plurality of independent exhaust pipe portions at downstream ends of the independent exhaust pipe portions. The present invention relates to an exhaust gas purifying apparatus for an engine having a connected catalyst case containing a catalyst carrier having a monolith structure therein, and a downstream exhaust pipe connected to a downstream end of the catalyst case. In addition, a partition wall is provided for introducing the exhaust gas from each cylinder discharged from each independent exhaust pipe portion to the catalyst carrier in which the exhaust strokes are not continuous, and the partition wall for introducing the exhaust gas from each cylinder to the catalyst carrier is provided. The downstream end is formed in a pipe shape having a substantially fan-shaped cross section, is fitted inside the substantially cylindrical upstream end of the catalyst case, and the upstream end of the partition wall has an exhaust stroke. For discontinuous cylinders So as to divide for each set of independent exhaust pipe section which is characterized in that it is inserted a predetermined amount between the pipe-shaped downstream end of the independent exhaust pipe section.
[0011]
According to the present invention, in the section from each cylinder to the upstream end of the catalyst case or the downstream end of the catalyst carrier, the exhaust gases discharged from the cylinders whose exhaust strokes are not continuous are separated and flow, so that the exhaust interference is effective. And the output of the engine is improved.
[0012]
Also, unlike the conventional structure in which a collecting pipe is interposed, a structure in which exhaust gas from each cylinder discharged from each independent exhaust pipe portion is gathered at the upstream portion of the catalyst case and the partition wall, when the exhaust process is not continuous. Therefore, it is possible to prevent the exhaust system from becoming longer and larger, and to reduce the size and cost of the exhaust system.
[0013]
The downstream end of the independent exhaust pipe is fitted inside the upstream end of the catalyst case, and the upstream end of the partition wall is inserted into the independent exhaust pipe by a predetermined amount. The connecting portion between the portion and the catalyst case has a solid multilayer structure, and the rigidity of the portion is improved. Therefore, an exhaust system having excellent durability against thermal expansion and contraction of the cylinder is realized.
[0014]
Further, since a thin wall member, that is, a pipe member having a small heat capacity can be used for the independent exhaust pipe portion, the exhaust gas is introduced into the catalyst carrier in a high temperature state, and the temperature of the catalyst carrier rises during a cold start of the engine. It is prompt and early activation is achieved.
[0015]
Next, according to a second aspect of the present invention, in the exhaust gas purifying apparatus according to the first aspect, the downstream end of each independent exhaust pipe, the upstream end of the catalyst case, and the upstream end of the partition wall are different from each other. , Each being fixed by welding.
[0016]
According to the present invention, since the members are fixed by welding, the connecting portion is further solidified, and the rigidity of the portion is further improved.
[0017]
And since it is a connection method which does not interpose a flange which has a large heat capacity because it is generally thick, it does not cause an unnecessary increase in the heat capacity in the exhaust system. Therefore, the temperature of the catalyst carrier rises more quickly at the time of cold start of the engine and the like, and further early activation is achieved.
[0018]
According to a third aspect of the present invention, in the exhaust gas purification apparatus according to the first or second aspect, an internal space downstream of the catalyst carrier is defined from a downstream portion of the catalyst case to a downstream exhaust pipe portion. The partition wall is provided in the same direction as the partition wall on the upstream side.
[0019]
According to the present invention, the exhaust gas discharged from the cylinders whose exhaust strokes are not continuous is separated and circulates to a predetermined position on the downstream side of the catalyst case in the exhaust system. Is achieved. At the same time, there is an advantage that the exhaust pulsation effect is favorably maintained.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an exhaust gas purifying apparatus for an engine according to an embodiment of the present invention will be described.
[0021]
This exhaust gas purification device is applied to an in-line four-cylinder engine. That is, as shown in FIG. 1, first to fourth independent exhaust having an opening at an upstream end communicating with first to fourth cylinders (not shown) on one side surface of a cylinder head 1 a constituting an upper portion of the engine body 1. The pipes 11 to 14 are connected via an engine mounting flange 15. Further, as shown by reference numeral A, the auxiliary catalytic converter 16 is connected to the downstream end of the independent exhaust pipes 11 to 14 in an inclined state, and as shown by reference numeral B, the downstream end of the auxiliary catalytic converter 16 is connected to the downstream end of the auxiliary catalytic converter 16. The side exhaust pipe 17 is connected. A main catalytic converter 18 is connected to a downstream end of the downstream side exhaust pipe 17.
[0022]
As a result, the exhaust gas discharged from each cylinder is guided to the respective independent exhaust pipes 11 to 14 and introduced into the sub-catalyst converter 16, purified by the sub-catalyst converter 16, and then guided to the downstream-side exhaust pipe 17. Then, it is introduced into the main catalytic converter 18 and purified by the main catalytic converter 18.
[0023]
Each of the independent exhaust pipes 11 to 14 made of a thin pipe member is formed such that one end side, that is, the engine body 1 side has a substantially circular cross section, while the other end side, that is, the sub-catalyst converter 16 side has a substantially fan-shaped cross section. 3 (see FIG. 3 and FIG. 4 described later), and from the engine mounting flange 15 to the sub-catalyst converter 16, the downstream side is curved and arranged so as to be close to each other near the center of the cylinder row in plan view.
[0024]
As shown in FIGS. 1 and 2, the sub-catalyst converter 16 has a catalyst carrier 21 and a catalyst case 22 for accommodating the catalyst carrier 21.
[0025]
The catalyst carrier 21 is a cylindrical monolithic ceramic monolith body having a honeycomb shape, has a large number of pores extending parallel to the axial direction, that is, along the flow direction of exhaust gas, and contains a noble metal component such as platinum. It carries a catalytic substance. A holding member 23 is wound around the outer peripheral surface of the catalyst carrier 21. The holding member 23 is formed by molding a ceramic fiber or the like into a mat shape, and holds the catalyst carrier 21 at a predetermined position in the catalyst case 22 while having inherent heat resistance.
[0026]
The catalyst case 22 has a cone member 24 forming an upstream portion and a main body member 25 forming a downstream portion. The cone member 24 has a cone shape whose diameter gradually decreases toward the upstream side. The main body member 25 includes a substantially cylindrical cylindrical portion 25a and a cone portion 25b whose diameter gradually decreases toward the downstream side. The catalyst member 21 is stored in the cylindrical portion 25a via the holding member 23. ing. The cone member 24 and the main body member 25 are each divided into two parts, and are integrated by welding. Further, as shown by reference numeral C, a general welded joint structure is applied to the connection between the downstream end of the cone member 24 and the upstream end of the main body member 25.
[0027]
The cone member 24 is provided with a first partition plate 31 that divides an internal space over substantially the entire length of the cone member 24 into two spaces S1 and S2. The first partition plate 31 has such a shape that its outer shape is substantially along the inner peripheral surface of the cone member 24 and its downstream end extends to near the upstream end surface of the catalyst carrier 21.
[0028]
A gap g1 is provided between the downstream end of the first partition plate 31 and the upstream end surface of the catalyst carrier 21. This gap g1 is provided in consideration of the thermal expansion and contraction of the first partition plate 31, and the first partition plate 31 divides the space on the upstream side of the catalyst carrier 21 into two spaces S1, in order to prevent exhaust interference. The dimension is set as small as possible so as to partition as much as possible into S2 and to prevent the catalyst carrier 21 from being damaged by contacting the upstream end face even during thermal expansion.
[0029]
Next, a description will be given of a characteristic connection structure between the first to fourth independent exhaust pipes 11 to 14 and the cone member 24 constituting the upstream portion of the catalyst case 22.
[0030]
First, as indicated by reference numeral A, the downstream ends of the respective independent exhaust pipes 11 to 14 are fitted inside the upstream end of the cone member 24 by a predetermined amount. That is, as shown in FIGS. 3 and 4, the substantially cylindrical downstream ends of the first to fourth independent exhaust pipes 11 to 14 are substantially free of gaps at the substantially cylindrical upstream end of the cone member 24. Has been inserted.
[0031]
Furthermore, since the ignition sequence of the engine according to the present embodiment is the general order of the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder, the upstream end of the first partition plate 31 has the exhaust end. Exhaust gas flowing through the first and fourth independent exhaust pipes 11 and 14 corresponding to the first and fourth cylinders whose strokes are not continuous, and second and third independent exhaust pipes 12 and 14 corresponding to the second and third cylinders. A predetermined amount is inserted between the set of the first and fourth independent exhaust pipes 11 and 14 and the set of the second and third independent exhaust pipes 12 and 13 so that the exhaust gas flowing through the exhaust pipe 13 is divided and collected. Have been. That is, the downstream sides of the first and fourth independent exhaust pipes 11 and 14 communicate with the space S1, while the downstream sides of the second and third independent exhaust pipes 12 and 13 communicate with the space S2 (FIG. 1). And FIG. 2).
[0032]
Then, as shown by reference numeral D in FIG. 3, welding of the outer peripheral surfaces of the respective independent exhaust pipes 11 to 14 and the upstream end surface of the cone member 24, and as shown by reference numeral E in FIG. The independent exhaust pipes 11 to 14 are fixed to the catalyst case 22 by welding the downstream end faces of the individual pipes 11 to 14 and the inner peripheral surface of the cone member 24.
[0033]
Further, as shown by reference numerals F and F in FIG. 4, the adjacent first and fourth independent exhaust pipes 11 and 14 and the second and third independent exhaust pipes 12 and 13 are welded through the downstream end surface. Has been fixed by.
[0034]
Further, as indicated by reference numerals G and G, the first partition plate 31 is welded to the downstream end surfaces of the respective independent exhaust pipes 11 to 14 so that the first partition plate 31 is separated from the respective independent exhaust pipes 11 to 14. Consequently, it is fixed to the catalyst case 22.
[0035]
Next, as shown by reference numeral B in FIGS. 1 and 2, a predetermined amount of the upstream end of the downstream exhaust pipe 17 is fitted into the downstream end of the cone 25 b of the main body member 25, and the downstream end of the cone 25 b is inserted. The downstream exhaust pipe 17 is fixed to the catalyst case 22 by welding the end face to the outer peripheral surface of the downstream exhaust pipe 17.
[0036]
As shown in FIGS. 1, 2 and 5, the downstream exhaust pipe 17 divides most of the internal space of the downstream exhaust pipe 17 into two spaces S1 'and S2' over a predetermined range. A second partition plate 32 is provided. The second partition plate 32 is disposed in the same direction as the above-described first partition plate 31, and has an outer shape substantially along the inner peripheral surface of the downstream exhaust pipe 17 and the inner peripheral surface of the cone portion 25 b of the main body member 25. The upstream end extends along the downstream end surface of the catalyst carrier 21 and is fixed to the downstream exhaust pipe 17 via both end surfaces by welding. In addition, the downstream end position of the second partition plate 32 is set such that the exhaust pulsation effect can be favorably maintained.
[0037]
A gap g2 is provided between the upstream end of the second partition plate 32 and the downstream end surface of the catalyst carrier 21. The gap g2 is provided for the same reason as the gap g1 in the case of the first partition plate 31 described above.
[0038]
Next, the operation of the exhaust gas purification device will be described.
[0039]
Exhaust gas discharged from each cylinder is guided by first to fourth independent exhaust pipes 11 to 14 corresponding to each cylinder, and is separated to a cone member 24 constituting an upstream portion of the catalyst case 22 of the sub-catalytic converter 16. It has been distributed.
[0040]
Then, in the space S1 inside the cone member 24, the exhaust gas discharged from the first independent exhaust pipe 11 and the fourth independent exhaust pipe 14, which correspond to the cylinders whose exhaust strokes are not continuous, is collected into one. On the other hand, in the space S2, the exhaust gas discharged from the second independent exhaust pipe 12 and the third independent exhaust pipe 13 corresponding to the cylinders whose exhaust strokes are not continuous is collected. The two exhaust gases flow further downstream in a well separated state along the spaces S1 and S2 defined by the first partition plate 31.
[0041]
Next, since the inside of the cone member 24 is divided into two spaces S1 and S2 by the first partition plate 31 up to the vicinity of the upstream end surface of the catalyst carrier 21, a large number of exhaust gases extend in parallel along the flow direction. Also, when passing through the catalyst carrier 21 having the fine pores, the exhaust gas flows further downstream in a state where the exhaust gas is well separated into two by a combination of those corresponding to the cylinders whose exhaust strokes are not continuous.
[0042]
The interior of the cone portion 25b of the main body member 25 and the interior of the downstream exhaust pipe 17 are provided in the same direction as the first partition plate 31 from the vicinity of the downstream end surface of the catalyst carrier 21 to a predetermined position toward the downstream side. Since the two partitions S1 'and S2' are partitioned by the second partition plate 32, these spaces S1 'and S2' communicate with the upstream spaces S1 and S2, respectively. That is, the exhaust gas flows through the spaces S1 'and S2' in a state where the exhaust gas continues to be well separated into two even after passing through the catalyst carrier 21, and then becomes one at the downstream end of the second partition plate 32 and thereafter. They are collected and introduced into the downstream main catalytic converter 18.
[0043]
In this way, the arrangement of the first and second partition plates 31 and 32 separates exhaust gases discharged from the cylinders whose exhaust strokes are not continuous up to a predetermined position downstream of the sub-catalytic converter 16 in the exhaust system. As a result, the predetermined exhaust pulsation effect is maintained and exhaust interference is well prevented, thereby improving the output of the engine.
[0044]
In this case, unlike the conventional structure in which the collecting pipe is interposed, the cone member 24 and the first partition plate 31 that constitute the upstream portion of the catalyst case 22 use the first partition plate 31 to separate the exhaust gas from each of the cylinders discharged from each of the independent exhaust pipes 11 to 14. Since the exhaust gas has a structure in which the exhaust gas is not continuous, the exhaust system can be prevented from becoming longer and larger, and the exhaust system can be made more compact and lower in cost.
[0045]
When connecting the independent exhaust pipes 11 to 14 and the cone member 24, a substantially fan-shaped downstream end of each of the independent exhaust pipes 11 to 14 is fitted into the substantially cylindrical upstream end of the cone member 24 by a predetermined amount. Have been. The upstream end of the first partition plate 31 is inserted between the pair of the first and fourth independent exhaust pipes 11 and 14 and the pair of the second and third independent exhaust pipes 12 and 13 by a predetermined amount. Each of the independent exhaust pipes 11 to 14 is fixed to the catalyst case 22 by welding, and the first partition plate 31 is fixed to each of the independent exhaust pipes 11 to 14 and further to the catalyst case 22 by welding.
[0046]
That is, as shown by reference numeral H in FIGS. 3 and 4, a cone member 24 having a substantially cylindrical upstream end and a substantially fan-shaped downstream portion are provided at a connection portion between each of the independent exhaust pipes 11 to 14 and the catalyst case 22. A two-layer structure composed of the independent exhaust pipes 11 to 14 having ends, and as shown by I, a set of the first and fourth independent exhaust pipes 11 and 14 and the second and third independent exhaust pipes 12 , 13 realizes a solid multilayer structure through welding, such as a three-layer structure in which the first partition plate 31 is sandwiched, and the rigidity of the connecting portion is effectively improved. Therefore, an exhaust system having excellent durability against thermal expansion and contraction of the cylinder is realized.
[0047]
In addition, the exhaust gas discharged from each cylinder is guided to the sub-catalyst converter 16 by the first to fourth independent exhaust pipes 11 to 14 made of a pipe member having a small thickness, that is, a small heat capacity. Since the catalyst carrier 21 is introduced into the catalyst carrier 21, the temperature of the catalyst carrier 21 is quickly increased, for example, at the time of a cold start of the engine, and activated quickly, so that the purification performance is improved.
[0048]
Furthermore, since the independent exhaust pipes 11 to 14 are not connected to the catalyst case 22 via a flange having a large heat capacity due to a generally thick wall, the heat capacity in the exhaust system does not increase unnecessarily. Therefore, the temperature of the catalyst carrier 21 rises more quickly, and the activation is achieved earlier.
[0049]
Since the temperature of the exhaust gas is quickly raised by the early activation of the sub-catalyst converter 16, the heated exhaust gas improves the purification performance of the subsequent main catalytic converter 18.
[0050]
In the above-described embodiment, the present invention is applied to an in-line four-cylinder engine. However, the present invention is not limited to this, and is applicable to a wide range of multi-cylinder engines such as an in-line six-cylinder engine.
[0051]
Further, in the above-described embodiment, the upstream end of the first partition plate 31 is fixed to the downstream end of each of the independent exhaust pipes 11 to 14 by welding, as shown by reference numerals FF in FIG. May be omitted and the first partition plate 31 may be sandwiched and held between the set of the first and fourth independent exhaust pipes 11 and 14 and the set of the second and third independent exhaust pipes 12 and 13.
[0052]
Further, in the above-described embodiment, in the catalyst case 22, the cone member 24 and the main body member 25 are each a two-piece body, but may be an integral body. Although the cone member 24 and the main body member 25 were connected by welding, as shown by reference numeral J in FIG. 6, the downstream end of the cone member 24 'and the upstream end of the main body member 25' were formed in a predetermined shape. May be bent, and these ends may be engaged, and then connected by caulking. Further, a catalyst case in which the cone member and the main body member are integrated may be used.
[0053]
【The invention's effect】
As described above, the present invention provides an exhaust gas purifying apparatus for an engine in which a catalytic converter is compactly and firmly disposed while preventing exhaust interference. That is, the present invention relates to an exhaust gas purifying apparatus for an engine in which a catalytic converter is arranged near a main body of a multi-cylinder engine, and is widely suitable in the field of engine exhaust purifying technology.
[Brief description of the drawings]
FIG. 1 is a schematic side view showing an exhaust gas purifying apparatus for an engine according to an embodiment of the present invention.
FIG. 2 is a view taken along line WW of FIG. 1;
FIG. 3 is a sectional view taken along line XX of FIG. 1;
FIG. 4 is a sectional view taken along line YY of FIG. 1;
FIG. 5 is a sectional view taken along line ZZ in FIG. 1;
FIG. 6 is a sectional view of a main part showing another connection structure between the cone member and the main body member in the catalyst case.
[Explanation of symbols]
1 Engine main bodies 11 to 14 First to fourth independent exhaust pipes (independent exhaust pipe section)
17 Downstream exhaust pipe (downstream exhaust pipe section)
21 Catalyst carrier 22 Catalyst case 31 First partition (partition wall)
32 2nd partition (partition wall)

Claims

A plurality of independent exhaust pipe sections connected to the main body of the multi-cylinder engine and independently guiding exhaust gas from each cylinder, and a catalyst carrier having a monolith structure internally connected to a downstream end of the independent exhaust pipe section. An exhaust purification device for an engine having a stored catalyst case and a downstream exhaust pipe connected to a downstream end of the catalyst case, wherein the exhaust gas is discharged from each independent exhaust pipe to an upstream portion of the catalyst case. A partition wall is provided to collect the exhaust gas from each cylinder that does not have a continuous exhaust stroke and to introduce the exhaust gas into the catalyst carrier, and the downstream end of each of the independent exhaust pipe sections has a pipe having a substantially fan-shaped cross section. And is fitted inside the substantially cylindrical upstream end of the catalyst case, and the upstream end of the partition wall is provided with an independent exhaust pipe portion corresponding to a cylinder whose exhaust stroke is not continuous. Partition by pairs Sea urchin, the exhaust purification device for an engine, characterized in that it is inserted a predetermined amount between the pipe-shaped downstream end of the independent exhaust pipe section.

The exhaust gas purifying apparatus for an engine according to claim 1, wherein the downstream end of each independent exhaust pipe, the upstream end of the catalyst case, and the upstream end of the partition wall are fixed by welding. .

The partition wall that partitions the internal space downstream of the catalyst carrier from the downstream part of the catalyst case to the downstream exhaust pipe part is provided in the same direction as the partition wall on the upstream side. Item 3. An engine exhaust purification device according to Item 2.