JP3601520B2

JP3601520B2 - Exhaust manifold assembly structure

Info

Publication number: JP3601520B2
Application number: JP2002081316A
Authority: JP
Inventors: 義正渡辺; 誠横田; 成樹保原; 和久三瓶; 哲高橋
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 1995-04-03
Filing date: 2002-03-22
Publication date: 2004-12-15
Anticipated expiration: 2015-10-30
Also published as: JP2002295252A

Description

【０００１】
【発明の属する利用分野】
本発明は、複数本のパイプを組合わせて溶接したパイプ型エキゾーストマニホルドの集合部の構造に関する。
【０００２】
【従来の技術】
複数本のパイプをパイプ端を成形して集合させ溶接にて一体化させることによりパイプ型エキゾーストマニホルドを構成し、このエキゾーストマニホルドのパイプ集合部の下流側端部を集合管の上流側端部に挿入して溶接接合したエキゾーストマニホルド集合部構造は、たとえば実開平５−１８１９号公報により知られている。
従来のエキゾーストマニホルドの集合部構造は、パイプ集合部がシリンダヘッド端面（エキゾーストマニホルド入口フランジ端面）から比較的近い位置にあるタイプのもの（図８〜１１に示すもので、以下、Ａタイプという）と、パイプ集合部がシリンダヘッド端面（エキゾーストマニホルド入口フランジ端面）から比較的遠い位置にあるタイプのもの（図１２〜１４に示すもので、以下、Ｂタイプという）と、に大別される。
【０００３】
【発明が解決しようとする課題】
従来のエキゾーストマニホルドの集合部構造には、つぎの問題がある。
(i) パイプ集合部の下流側端のパイプ間溶接部には、大きな熱応力がかかること、直交する分離壁の交点は高い温度になること（図１５のマニホルド温度分布参照）、直交する溶接線の重なり点となって溶接品質が悪いこと、の３つの厳しい条件が重なるため、強度上の信頼性を高く保つことが困難である。
(ii)熱応力の緩和を目的として実開平５−１８１９号公報のように直交する分離壁の両方を曲面壁とすると、パイプ集合部の断面剛性が低下して変形が促進してしまい、熱応力緩和の効果を相殺し十分な亀裂発生抑制効果が得られず、場合によっては亀裂発生を早める。
本発明の目的は、強度上の信頼性を向上できるエキゾーストマニホルド集合部構造を提供することにある。
【０００４】
【課題を解決するための手段】
上記目的を達成する本発明は、次の通りである。
（１）複数本のパイプのそれぞれの下流側部分を成形して集合させ溶接にて一体化してエキゾーストマニホルドを形成し、前記エキゾーストマニホルドのパイプ集合部を集合管の上流側端部に挿入し該集合管に相対的に固定したエキゾーストマニホルド集合部構造において、前記エキゾーストマニホルドのパイプ集合部の少なくとも下流側部分を円筒状の中間部材に挿入して該中間部材に溶接にて接合し、該中間部材を前記集合管の上流側部分に挿入して溶接にて固定したことを特徴とするエキゾーストマニホルド集合部構造。
【０００５】
上記（１）の構造では、エキゾーストマニホルドを構成する複数本のパイプの熱膨張差に起因するモーメントが中間部材によって分担されるので、パイプ集合部の下流側端面の溶接部にかかるモーメントが低減され、強度上の信頼性が向上される。
【０００６】
【発明の実施の形態】
本発明は、つぎの(i) 、 (ii)の２つのグループを含む。
(i) 第１のグループ（請求項１に対応するもの）：別体の中間部材を介してパイプ集合部と集合管を溶接しモーメントを中間部材に分担させるもので、本発明の第１実施例を含む。本発明の第１実施例は図１に示されている。
(ii)第２のグループ（請求項２に対応するもの）：ほぼ直交する集合部分離壁の一方のみを曲面壁とするもので、本発明の第２、第３実施例を含む。本発明の第２実施例は図２に示されており、本発明の第３実施例は図３に示されている。
【０００７】
まず、本発明の全実施例に共通する部分の構成、作用を、図８〜図１４を参照して説明する。ただし、図８〜図１１はＡタイプを示し、図１２〜図１４はＢタイプを示す。
本発明実施例のエキゾーストマニホルド集合部構造は、複数本（気筒数と同じ数）のパイプ（ポートともいう、たとえば、ステンレスパイプからなる）６、７、８、９をそれぞれの下流側（排気ガス流れ方向に見て下流側の意味）部分で集合させ溶接にて一体化してエキゾーストマニホルド（パイプ溶接型エキゾーストマニホルド）１０を形成し、このエキゾーストマニホルド１０のパイプ集合部１４をこれと別体の集合管１１の上流側端部に挿入し、集合管１１に相対的に固定（直接または間接的に溶接にて一体化）したものからなる。パイプ集合部１４（ポート集合部ともいう）は、図１１に示すように、パイプ６、７、８、９の下流側部分を各々横断面扇形に成形して、この横断面扇形に成形した部分を扇形のかなめの部分を集合部横断面中心に配し集合部横断面外形が円形となるように集合させ、パイプ集合部１４の下流側端面のパイプ合せ部を溶接にて接合したものからなる。パイプ集合部１４を集合管１１に直接溶接する場合は、集合管１１の上流側端とパイプ集合部１４の外側面とを溶接する。ただし、本発明の第１実施例では、パイプ集合部１４は集合管１１に間接的に、すなわち中間部材を介して、接合される。
【０００８】
エキゾーストマニホルド１０はガスケット１０´を介してシリンダヘッド１に取り付けられる。シリンダヘッド１にはその長手方向に順に、＃１〜＃４気筒の排気ポートが開口している。排気ポート並びの外側に位置する＃１、＃４気筒の排気ポート２、３に接続されるパイプ６、７の、シリンダヘッドからパイプ曲り部までの、シリンダヘッド長手方向と直角方向の距離Ｌ１は、排気ポート並びの内側に位置する＃２、＃３気筒の排気ポート４、５に接続されるパイプ８、９の、シリンダヘッドからパイプ曲り部までの、シリンダヘッド長手方向と直角方向の距離Ｌ２より長い。
【０００９】
上記共通構成部分の作用を、たとえばＡタイプについて、説明すると、機関運転時にパイプ６、７とパイプ８、９の間の熱膨張差が生じ、パイプ集合部１４の、シリンダヘッド長手方向と平行方向に延びる、Ｘ−Ｘ軸まわりのモーメント１２がパイプに生じる。このモーメント１２はパイプ集合部１４の下流側端面のＸ−Ｘ軸方向の溶接部に熱応力を発生させる。Ｙ点は溶接線がクロスするので強度上厳しくなる。エキゾーストマニホルド１０および集合管１１の温度分布は図１５に示すように、溶接線クロス点Ｙでとくに高温である。
【００１０】
つぎに、本発明の各実施例に特有な構成、作用を説明する。
本発明の第１実施例の構成については、図１に示すように、エキゾーストマニホルド１０をエキゾーストマニホルド１０および集合管１１とは別体の中間部材２７を介して、集合管１１に接続する。より詳しくは、パイプ６、７、８、９の各々の下流側部分を横断面扇形に成形し、集合させて溶接にて一体化して横断面外形が円形のパイプ集合部１４を形成する。このパイプ集合部１４の少なくとも下流側部分を円筒状の中間部材２７に挿入し、パイプ集合部下流端と中間部材内周面との間を溶接（溶接部を符号２８で示した）するとともに、中間部材上流端とパイプ集合部外周面との間を溶接（溶接部を符号２９で示した）する。さらに、この中間部材２７を集合管１１の上流側部分に挿入して、集合管１１の上流端と中間部材外周面との間を、溶接部２８と溶接部２９の軸方向中間位置で、溶接（溶接部を符号３０で示した）にて接合する。
【００１１】
本発明の第１実施例の作用については、中間部材２７の下流側は絞り成形の無い開放端であることからパイプ６、７、８、９の下流側端部の外周を中間部材２７の内周面に溶接部２８で溶接することができるため、溶接部２９での溶接と併せて２ヶ所でつなぐことができるので、モーメント１２を中間部材２７で分担することができ、中間部材２７の剛性によりＹ点に作用する熱応力を軽減することができる。さらに、中間部材２７は集合管１１に嵌合され溶接部２８と溶接部２９の中間点で溶接部３０で結合されるため、中間部材２７の剛性はさらに高められることになり、さらなる応力緩和効果が得られる。さらに、別の作用として中間部材２７を接合した時点で各パイプが一体化されるため、そのサブアッシー状態で中間部材２７の端部３１をシール面として洩れ検査を容易に実施でき、また、中間部材２７の下流側は絞り成形の無い開放端であるため洩れ部位の補修が容易にできる。
【００１２】
上記迄の実施例に対して次の変形例にも拡張適用される。
エンジンの構成によって、Ｘ−Ｘ線と直角なＰ−Ｐ線を中心とするモーメント力の作用が大きくなることが考えられる（Ｂタイプ）。その場合は本発明の実施例を９０°回転して応用することにより同様の効果が実現できる。
耐熱性向上のため管端の扇形成形をやめて、円形のままで合流させてもよい。ただし、円形４本を合流させるためには、集合管の管端をそれに沿う形で成形する必要があり、２つ割り、もしくは４つ割りのプレス成形品を溶接して製造する必要があるため部品点数も増え、コスト高になる。また、パイプ端との溶接線も複雑になるため信頼性確保のためさらにコスト高になる。
また、本発明はエキゾーストマニホルドが下流側に延長された長い集合管１１に接続される場合により効果的である。本発明を適用することにより集合管１１の曲げ、及び、管端加工のみで低コストで耐熱性が高いエキゾーストマニホルドを提供できる。
【００１３】
本発明の第２実施例はＡタイプに適用されるものである。本発明の第２実施例の構成については、図２（図９のＡ−Ａ線に沿う断面図）に示すように、エキゾーストマニホルド１０のパイプ集合部１４は、４つのポート（パイプ）６、７、８、９の集合部からなり、ほぼ直交する分離壁３２、３３のうち、シリンダヘッド長手方向と平行なＸ−Ｘ軸に沿った分離壁３２が、パイプ集合部１４の径方向に湾曲しながら延びる曲面壁とされ、他方の分離壁３３が、パイプ集合部１４の径方向にストレートに延びる平面壁とされている。
【００１４】
本発明の第２実施例の作用を説明する前に、Ａタイプのエキゾーストマニホルドにおける熱疲労亀裂の発生のメカニズムをまず説明する。
図８〜図１１に示すＡタイプのエキゾーストマニホルド１０は、前述のように４本のポート（パイプ）６、７、８、９を集合管１１に挿入し、これを溶接、接合して成る。集合部１４はシリンダヘッド端面（エキゾーストマニホルド入口フランジ３４の端面）から比較的近い位置にあるため、集合部１４をはさんでポート６、７が向かい合いポート８、９が向かい合う形状となる。また、拘束部位（入口フランジ３４、エキマニステイボス３５）を結ぶ直線３６に対して集合部位置が大きく張り出すことはない。
このエキゾーストマニホルド１０では、向かい合うポート６、７および８、９が熱膨張することによって発生する力３７、３８が集合部１４に加わり、ポート集合部１４の断面は図５に示すようにつぶれる。この結果、温度が高い中央部３９の溶接部に歪が集中し、亀裂発生の要因となる。また、長いポート６、７と短いポート８、９の間では、長さの差分だけ熱膨張量に差を生じるため、それによる力４０によって図５の断面の押しつぶし変形は促進され、歪の集中度合が増す。
【００１５】
本発明の第２実施例の作用については、集合部断面をつぶす方向と平行な分離壁３２を曲面壁としたので、歪の集中が曲面壁のほぼ全長にわたって分散され、亀裂発生が抑制される。
これに対して、実開平５−１８１９号公報のように分離壁３２、３３を両方とも曲面壁とすれば、集合部中央への歪の集中を曲面壁へ分散する機能はあるが、同時に断面剛性を低下させるため図５の変形を促進してしまう。このため、効果が相殺されてしまい、十分な亀裂発生防止効果が得られない。
本発明の第２実施例では、集合部断面をつぶす方向と直角方向の分離壁３３は平面壁としたので、曲面壁３２によるポート断面剛性の低下は小とされ、図５の変形は促進されず、十分な亀裂発生防止効果がある。
【００１６】
本発明の第３実施例はＢタイプに適用されるものである。本発明の第３実施例の構成については、図３（図１３のＣ−Ｃ線に沿う断面図）に示すように、エキゾーストマニホルド１０のパイプ集合部１４は、４つのポート（パイプ）６、７、８、９の集合部からなり、ほぼ直交する分離壁３２、３３のうち、シリンダヘッド長手方向と直交するＰ−Ｐ軸に沿った分離壁３３が、パイプ集合部１４の径方向に湾曲しながら延びる曲面壁とされ、他方の分離壁３２が、パイプ集合部１４の径方向にストレートに延びる平面壁とされている。
【００１７】
本発明の第３実施例の作用を説明する前に、Ｂタイプのエキゾーストマニホルドにおける熱疲労亀裂の発生のメカニズムをまず説明する。
図１２〜図１４に示すＢタイプのエキゾーストマニホルド１０も、前述のように４本のポート（パイプ）６、７、８、９を集合管１１に挿入し、これを溶接、接合して成る。集合部１４はシリンダヘッド端面（エキゾーストマニホルド入口フランジ３４の端面）から比較的遠い位置にあるため、集合部１４をはさんでポート６、７、ポート８、９が向かい合う形状とはならない。また、拘束部位（入口フランジ３４、エキマニステイボス３５）を結ぶ直線３６に対して集合部位置が大きく張り出す。
このエキゾーストマニホルド１０では、Ａタイプのような向かい合うポートが集合部１４の断面をつぶす変形は起こりにくく（小さく）、代わって、図６、図７に示すようにエキゾーストマニホルド１０全体が上流端、下流端３４、３５の拘束の中で熱膨張しようとする力４１によってモーメント４２が生じ、集合部断面の内側（流線Ｒ、すなわち軸方向に延びる湾曲した軸線Ｒ、の内側）がシリンダヘッド長手方向と直角方向Ｐ−Ｐに押しつぶされる変形が主体となる。すなわち、Ｂタイプでは、Ａタイプの場合の力、変形と直交する方向に力、変形が生じる。したがって、Ｂタイプではシリンダヘッド１の長手方向と平行な分離壁３３が曲面壁とされるべきである。
【００１８】
本発明の第３実施例の作用については、集合部断面をつぶす方向（Ｂタイプではシリンダヘッドの長手方向と平行な方向）に延びる分離壁３３を曲面壁としたので、歪の集中が曲面壁３３のほぼ全長にわたって分散され、亀裂発生が抑制される。
これに対して、実開平５−１８１９号公報のように分離壁３２、３３を両方とも曲面壁とすれば、集合部中央への歪の集中を曲面壁へ分散する機能はあるが、同時に断面剛性を低下させるため図７の変形を促進してしまう。このため、効果が相殺されてしまい、十分な亀裂発生防止効果が得られない。
本発明の第３実施例では、集合部断面をつぶす方向（Ｐ−Ｐ方向）と直角方向の分離壁３２は平面壁としたので、曲面壁３３によるポート断面剛性の低下は小とされ、図７の変形は促進されず、十分な亀裂発生防止効果がある。
【００１９】
【発明の効果】
請求項１の構造によれば、中間部材を設けたので、熱膨張差に起因するモーメントを中間部材に一部受けもたせることができ、それによってパイプ集合部下流側端面の溶接部にかかるモーメントが低減され、強度上の信頼性が向上される。
【図面の簡単な説明】
【図１】本発明の第１実施例に係るエキゾーストマニホルド集合部構造の側面図である。
【図２】本発明の第２実施例に係るエキゾーストマニホルド集合部構造の（図９のＡ−Ａ線に沿う）断面図である。
【図３】本発明の第３実施例に係るエキゾーストマニホルド集合部構造の（図１３のＣ−Ｃ線に沿う）断面図である。
【図４】Ａタイプのエキゾーストマニホルドの力、モーメントのかかり方と変形を示す、エキゾーストマニホルドの側面図である。
【図５】Ａタイプのエキゾーストマニホルドの力のかかり方と変形を示す、エキゾーストマニホルドの平面図である。
【図６】Ｂタイプのエキゾーストマニホルドの力、モーメントのかかり方と変形を示す、エキゾーストマニホルドの側面図である。
【図７】Ｂタイプのエキゾーストマニホルドの力のかかり方と変形を示す、エキゾーストマニホルドの平面図である。
【図８】Ａタイプのエキゾーストマニホルドの平面図である。
【図９】Ａタイプのエキゾーストマニホルドの正面図である。
【図１０】Ａタイプのエキゾーストマニホルドの側面図である。
【図１１】Ａタイプのエキゾーストマニホルドのパイプ集合部の、図９のＡ−Ａ線に沿う、断面図である。
【図１２】Ｂタイプのエキゾーストマニホルドの平面図である。
【図１３】Ｂタイプのエキゾーストマニホルドの正面図である。
【図１４】Ｂタイプのエキゾーストマニホルドの側面図である。
【図１５】図９で温度分布を示した図である。
【符号の説明】
６、７、８、９パイプ（ポート）
１０エキゾーストマニホルド
１１集合管
１２モーメント
１４パイプ集合部（ポート集合部）
２７中間部材
３２、３３分離壁[0001]
FIELD OF THE INVENTION
The present invention relates to a structure of an assembly portion of a pipe-type exhaust manifold obtained by combining and welding a plurality of pipes.
[0002]
[Prior art]
A pipe-type exhaust manifold is constructed by forming a plurality of pipes, forming pipe ends, and integrating them by welding.The downstream end of the pipe assembly of the exhaust manifold is connected to the upstream end of the collecting pipe. An exhaust manifold assembly structure inserted and welded is known, for example, from Japanese Utility Model Laid-Open No. 5-1819.
A conventional exhaust manifold assembly structure is of a type in which a pipe assembly is located relatively close to a cylinder head end face (exhaust manifold inlet flange end face) (shown in FIGS. 8 to 11, hereinafter referred to as an A type). And the type in which the pipe collecting portion is located relatively far from the end face of the cylinder head (the end face of the exhaust manifold inlet flange) (shown in FIGS. 12 to 14, hereinafter referred to as B type).
[0003]
[Problems to be solved by the invention]
The conventional exhaust manifold assembly has the following problems.
(i) A large thermal stress is applied to the pipe-to-pipe weld at the downstream end of the pipe assembly, the intersection of the orthogonal separation walls is at a high temperature (see the manifold temperature distribution in FIG. 15), and the orthogonal welding is performed. It is difficult to maintain high reliability in strength because the three severe conditions of poor welding quality at the line overlap point overlap.
(ii) If both of the orthogonal separation walls are curved walls as in Japanese Utility Model Application Laid-Open No. 5-1819 for the purpose of relaxing thermal stress, the sectional rigidity of the pipe collecting portion is reduced and deformation is accelerated, and the heat is reduced. The effect of stress relaxation is canceled out, and a sufficient crack generation suppressing effect cannot be obtained, and in some cases, crack generation is accelerated.
An object of the present invention is to provide an exhaust manifold assembly structure that can improve the reliability in strength.
[0004]
[Means for Solving the Problems]
The present invention that achieves the above object is as follows.
(1) The downstream portions of the plurality of pipes are formed, assembled, and integrated by welding to form an exhaust manifold, and the pipe assembly of the exhaust manifold is inserted into the upstream end of the collecting pipe. in a relatively fixed exhaust manifold collecting portion structure collecting pipe, wherein at least a downstream portion of the pipe collecting part of the exhaust manifold was inserted into the cylindrical intermediate member is joined by welding to the intermediate member, the intermediate member exhaust manifold collecting portion structure characterized in that fixed in insert and welded to the upstream portion of the collecting tube.
[0005]
In the structure of the above (1), since the moment caused by the difference in thermal expansion between the plurality of pipes constituting the exhaust manifold is shared by the intermediate member, the moment applied to the weld at the downstream end face of the pipe assembly is reduced. The reliability on strength is improved .
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention includes the following two groups (i) and (ii) .
(i) First group (corresponding to claim 1): A first group of the present invention in which a pipe collecting portion and a collecting pipe are welded through a separate intermediate member to share a moment with the intermediate member. Including examples. A first embodiment of the present invention is shown in FIG.
(ii) Second group (corresponding to claim 2): Only one of the gathering part separation walls which is substantially orthogonal is a curved wall, and includes the second and third embodiments of the present invention. A second embodiment of the present invention is shown in FIG. 2, and a third embodiment of the present invention is shown in FIG.
[0007]
First, the configuration and operation of a portion common to all embodiments of the present invention will be described with reference to FIGS. 8 to 11 show the A type, and FIGS. 12 to 14 show the B type.
In the exhaust manifold assembly structure of the embodiment of the present invention, a plurality of (same as the number of cylinders) pipes (also referred to as ports, for example, made of stainless steel pipes) 6, 7, 8, and 9 are respectively connected to the downstream side (exhaust gas). (Meaning on the downstream side in the flow direction) is assembled at a portion and integrated by welding to form an exhaust manifold (pipe welding type exhaust manifold) 10, and a pipe assembly 14 of the exhaust manifold 10 is assembled separately from this. It is inserted into the upstream end of the pipe 11 and relatively fixed (directly or indirectly integrated by welding) to the collecting pipe 11. As shown in FIG. 11, the pipe collecting portion 14 (also referred to as a port collecting portion) is formed by forming the downstream portions of the pipes 6, 7, 8, and 9 into sector-shaped cross-sections, respectively. The fan-shaped key portion is arranged at the center of the cross section of the collecting portion, the cross section of the collecting portion is assembled into a circular shape, and the pipe joining portion on the downstream end face of the pipe collecting portion 14 is joined by welding. . When the pipe collecting part 14 is directly welded to the collecting pipe 11, the upstream end of the collecting pipe 11 and the outer surface of the pipe collecting part 14 are welded. However, in the first embodiment of the present invention, the pipe collecting portion 14 is joined to the collecting pipe 11 indirectly, that is, via an intermediate member.
[0008]
The exhaust manifold 10 is attached to the cylinder head 1 via a gasket 10 '. Exhaust ports of # 1 to # 4 cylinders are opened in the cylinder head 1 in the longitudinal direction. The distance L1 in the direction perpendicular to the longitudinal direction of the cylinder head from the cylinder head to the pipe bend of the pipes 6, 7 connected to the exhaust ports 2, 3 of the # 1, # 4 cylinders located outside the exhaust port arrangement is The distance L2 in the direction perpendicular to the cylinder head longitudinal direction from the cylinder head to the pipe bend of the pipes 8, 9 connected to the exhaust ports 4, 5 of the # 2, # 3 cylinders located inside the exhaust port arrangement. Longer.
[0009]
The operation of the common components will be described with respect to, for example, the A type. When the engine is operating, a difference in thermal expansion between the pipes 6, 7 and the pipes 8, 9 occurs, and the pipe assembly 14 extends in a direction parallel to the longitudinal direction of the cylinder head. , A moment 12 about the XX axis is generated in the pipe. The moment 12 generates a thermal stress in the welded portion in the XX axis direction on the downstream end surface of the pipe assembly 14. Since the welding line crosses the Y point, the strength becomes severe. As shown in FIG. 15, the temperature distribution of the exhaust manifold 10 and the collecting pipe 11 is particularly high at the welding line cross point Y.
[0010]
Next, the configuration and operation unique to each embodiment of the present invention will be described.
In the configuration of the first embodiment of the present invention, as shown in FIG. 1, the exhaust manifold 10 is connected to the collecting pipe 11 via an intermediate member 27 separate from the exhaust manifold 10 and the collecting pipe 11. More specifically, the downstream portion of each of the pipes 6, 7, 8, and 9 is formed into a fan shape in cross section, assembled, and integrated by welding to form a pipe assembly 14 having a circular cross section. At least the downstream side portion of the pipe collecting portion 14 is inserted into the cylindrical intermediate member 27, and the downstream end of the pipe collecting portion and the inner peripheral surface of the intermediate member are welded (the welded portion is indicated by reference numeral 28). Welding is performed between the upstream end of the intermediate member and the outer peripheral surface of the pipe collecting portion (the welded portion is indicated by reference numeral 29). Further, the intermediate member 27 is inserted into the upstream portion of the collecting pipe 11 so that the intermediate portion 27 is welded between the upstream end of the collecting pipe 11 and the outer peripheral surface of the intermediate member at an axially intermediate position between the welding portions 28 and 29. (The weld is indicated by reference numeral 30).
[0011]
Regarding the operation of the first embodiment of the present invention, since the downstream side of the intermediate member 27 is an open end without drawing, the outer circumferences of the downstream ends of the pipes 6, 7, 8, 9 are divided into the intermediate member 27. Since the peripheral surface can be welded at the welded portion 28, the moment 12 can be shared by the intermediate member 27, and the rigidity of the intermediate member 27 can be shared. Thereby, the thermal stress acting on the Y point can be reduced. Further, since the intermediate member 27 is fitted into the collecting pipe 11 and joined at the welded portion 30 at an intermediate point between the welded portion 28 and the welded portion 29, the rigidity of the intermediate member 27 is further increased, and a further stress relaxation effect is obtained. Is obtained. Further, since the pipes are integrated when the intermediate member 27 is joined as another operation, the leakage inspection can be easily performed with the end 31 of the intermediate member 27 as a sealing surface in the sub-assembled state. Since the downstream side of the member 27 is an open end where no drawing is performed, it is possible to easily repair a leak site.
[0012]
The above-described embodiment is extended to the following modified example.
Depending on the configuration of the engine, it is conceivable that the action of the moment force about the PP line perpendicular to the XX line increases (B type). In that case, a similar effect can be realized by applying the embodiment of the present invention by rotating it by 90 °.
In order to improve heat resistance, the fan end shape at the pipe end may be stopped and the pipes may be joined in a circular shape. However, in order to join four circular shapes, it is necessary to form the pipe end of the collecting pipe along the shape thereof, and it is necessary to weld and manufacture a two-part or four-part press-formed product. The number of parts increases and the cost increases. Further, since the welding line with the pipe end is complicated, the cost is further increased to ensure reliability.
Further, the present invention is more effective when the exhaust manifold is connected to the long collecting pipe 11 extended to the downstream side. By applying the present invention, it is possible to provide an exhaust manifold having low heat resistance and high heat resistance only by bending the collecting pipe 11 and processing the pipe end.
[0013]
The second embodiment of the present invention is applied to the A type. Regarding the configuration of the second embodiment of the present invention, as shown in FIG. 2 (a cross-sectional view taken along the line AA in FIG. 9), the pipe collecting portion 14 of the exhaust manifold 10 has four ports (pipes) 6, Among the separating walls 32 and 33 which are formed of the collecting portions 7, 8 and 9 and which are substantially orthogonal to each other, the separating wall 32 along the XX axis parallel to the longitudinal direction of the cylinder head is curved in the radial direction of the pipe collecting portion 14. The other separation wall 33 is a flat wall that extends straight in the radial direction of the pipe assembly 14.
[0014]
Before describing the operation of the second embodiment of the present invention, the mechanism of generation of thermal fatigue cracks in an A-type exhaust manifold will be described first.
The A-type exhaust manifold 10 shown in FIGS. 8 to 11 is formed by inserting four ports (pipes) 6, 7, 8, and 9 into the collecting pipe 11 and welding and joining them as described above. Since the collecting part 14 is located relatively close to the end face of the cylinder head (the end face of the exhaust manifold inlet flange 34), the ports 6, 7 face each other with the collecting part 14 therebetween, and the ports 8, 9 face each other. In addition, the position of the gathering portion does not greatly protrude with respect to the straight line 36 connecting the restraining portions (the inlet flange 34 and the exhaust manifold boss 35).
In the exhaust manifold 10, forces 37 and 38 generated by thermal expansion of the facing ports 6, 7 and 8, 9 are applied to the collecting portion 14, and the cross section of the port collecting portion 14 is collapsed as shown in FIG. As a result, strain concentrates on the welded portion of the central portion 39 where the temperature is high, which causes cracks. Further, a difference in the amount of thermal expansion occurs between the long ports 6 and 7 and the short ports 8 and 9 by the difference in length, so that the crushing deformation of the cross section in FIG. The degree increases.
[0015]
Regarding the operation of the second embodiment of the present invention, since the separation wall 32 parallel to the direction in which the cross section of the gathering portion is crushed is a curved wall, the concentration of strain is dispersed over substantially the entire length of the curved wall, and the occurrence of cracks is suppressed. .
On the other hand, if both the separation walls 32 and 33 are curved walls as in Japanese Utility Model Application Laid-Open No. 5-1819, the function of dispersing the concentration of strain at the center of the gathering portion to the curved walls is provided, but at the same time, the cross section is increased. Since the rigidity is reduced, the deformation of FIG. 5 is promoted. For this reason, the effects are offset, and a sufficient crack generation preventing effect cannot be obtained.
In the second embodiment of the present invention, since the separation wall 33 in the direction perpendicular to the direction in which the cross section of the gathering portion is crushed is a flat wall, the reduction in the rigidity of the port section due to the curved wall 32 is reduced, and the deformation in FIG. And has a sufficient crack prevention effect.
[0016]
The third embodiment of the present invention is applied to the B type. Regarding the configuration of the third embodiment of the present invention, as shown in FIG. 3 (a cross-sectional view along the line CC in FIG. 13), the pipe collecting portion 14 of the exhaust manifold 10 has four ports (pipes) 6, Among the separating walls 32 and 33 which are formed of the collecting portions 7, 8 and 9 and which are substantially orthogonal to each other, the separating wall 33 along the PP axis which is orthogonal to the longitudinal direction of the cylinder head is curved in the radial direction of the pipe collecting portion 14. The other separation wall 32 is a flat wall that extends straight in the radial direction of the pipe assembly 14.
[0017]
Before describing the operation of the third embodiment of the present invention, the mechanism of generation of thermal fatigue cracks in a B-type exhaust manifold will be described first.
The B-type exhaust manifold 10 shown in FIGS. 12 to 14 is also formed by inserting the four ports (pipes) 6, 7, 8, and 9 into the collecting pipe 11 and welding and joining them as described above. Since the collecting part 14 is located relatively far from the end face of the cylinder head (the end face of the exhaust manifold inlet flange 34), the ports 6, 7, and the ports 8, 9 do not face each other with the collecting part 14 interposed therebetween. In addition, the position of the gathering portion protrudes greatly with respect to the straight line 36 connecting the restraining portions (the inlet flange 34 and the exhaust manifold boss 35).
In this exhaust manifold 10, deformation such that the facing port such as the A type crushes the cross section of the collecting portion 14 is unlikely to occur (small), and instead, as shown in FIGS. A moment 42 is generated by the force 41 that is about to expand thermally due to the restraint of the ends 34, 35, and the inside of the cross section of the gathering portion (the inside of the streamline R, that is, the curved axis R extending in the axial direction) is in the longitudinal direction of the cylinder head. And the deformation that is crushed in a direction perpendicular to the direction P-P. That is, in the B type, a force and a deformation are generated in a direction orthogonal to the force and the deformation in the case of the A type. Therefore, in the B type, the separation wall 33 parallel to the longitudinal direction of the cylinder head 1 should be a curved wall.
[0018]
Regarding the operation of the third embodiment of the present invention, since the separation wall 33 extending in the direction of crushing the cross section of the collecting portion (in the B type, the direction parallel to the longitudinal direction of the cylinder head) is a curved wall, the concentration of strain is reduced. 33 are distributed over almost the entire length, and crack generation is suppressed.
On the other hand, if both the separation walls 32 and 33 are curved walls as in Japanese Utility Model Application Laid-Open No. 5-1819, the function of dispersing the concentration of strain at the center of the gathering portion to the curved walls is provided, but at the same time, the cross section is increased. Since the rigidity is reduced, the deformation of FIG. 7 is promoted. For this reason, the effects are offset, and a sufficient crack generation preventing effect cannot be obtained.
In the third embodiment of the present invention, since the separation wall 32 in the direction perpendicular to the direction in which the cross section of the gathering portion is crushed (PP direction) is a flat wall, the reduction in the port cross-sectional rigidity due to the curved wall 33 is small. The deformation of No. 7 is not promoted, and there is a sufficient crack generation preventing effect.
[0019]
【The invention's effect】
According to the structure of the first aspect, since the intermediate member is provided, the moment caused by the difference in thermal expansion can be partially received by the intermediate member, whereby the moment applied to the welded portion on the downstream end face of the pipe collecting portion is reduced. And strength reliability is improved .
[Brief description of the drawings]
FIG. 1 is a side view of an exhaust manifold assembly structure according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view (along line AA in FIG. 9) of an exhaust manifold assembly structure according to a second embodiment of the present invention.
FIG. 3 is a sectional view (along line CC of FIG. 13) of an exhaust manifold assembly structure according to a third embodiment of the present invention.
FIG. 4 is a side view of the exhaust manifold showing the force and moment applied and deformation of the A type exhaust manifold.
FIG. 5 is a plan view of the exhaust manifold, showing how the type A exhaust manifold is applied and deformed.
FIG. 6 is a side view of the exhaust manifold showing the force, moment applied, and deformation of the B-type exhaust manifold.
FIG. 7 is a plan view of the exhaust manifold, showing how the type B exhaust manifold is applied and deformed.
FIG. 8 is a plan view of an A type exhaust manifold.
FIG. 9 is a front view of an A type exhaust manifold.
FIG. 10 is a side view of an A type exhaust manifold.
11 is a cross-sectional view of the pipe assembly of the A-type exhaust manifold, taken along line AA of FIG. 9;
FIG. 12 is a plan view of a type B exhaust manifold.
FIG. 13 is a front view of a type B exhaust manifold.
FIG. 14 is a side view of a type B exhaust manifold.
FIG. 15 is a diagram showing a temperature distribution in FIG. 9;
[Explanation of symbols]
6, 7, 8, 9 pipe (port)
10 Exhaust manifold 11 Collecting pipe 12 Moment 14 Pipe collecting part (port collecting part)
27 Intermediate members 32, 33 Separation wall

Claims

The respective downstream portions of the plurality of pipes are formed, assembled and integrated by welding to form an exhaust manifold, and the pipe manifold of the exhaust manifold is inserted into the upstream end of the manifold and inserted into the manifold. In the relatively fixed exhaust manifold collecting part structure, at least the downstream part of the pipe collecting part of the exhaust manifold is inserted into a cylindrical intermediate member, and the downstream end of the pipe collecting part and the intermediate member inner peripheral surface are formed. Between, and between the upstream end of the intermediate member and the outer peripheral surface of the pipe collecting part, the pipe collecting part is joined to the intermediate member by welding, and the intermediate member is inserted into the upstream part of the collecting pipe. In the middle of the weld between the downstream end of the pipe assembly and the inner peripheral surface of the intermediate member, and the weld between the upstream end of the intermediate member and the outer peripheral surface of the pipe aggregate, and Collecting pipe Exhaust manifold collecting portion structure upstream end, characterized by being fixed by welding to the collecting pipe.