JP3656283B2

JP3656283B2 - Connection structure of branch connection in high-pressure fuel rail

Info

Publication number: JP3656283B2
Application number: JP15981095A
Authority: JP
Inventors: 信夫加藤
Original assignee: Usui Co Ltd
Current assignee: Usui Co Ltd
Priority date: 1994-06-28
Filing date: 1995-06-02
Publication date: 2005-06-08
Anticipated expiration: 2020-06-08
Also published as: JPH0875075A

Description

【０００１】
【産業上の利用分野】
本発明は高圧燃料多岐管またはブロックレールのような高圧燃料レールにおける分岐枝管または分岐金具のような分岐接続体の接続構造に係り、特にディーゼル内燃機関への燃料供給路となる１０００ｋｇｆ／ｃｍ^２以上の高圧燃料レールにおける分岐接続体の接続構造に関する。
【０００２】
【従来の技術】
従来、この種の分岐接続体の接続構造は、本出願人により特開平３−２７３５９９号公報で提案されたが、これは図１１に例示するように、分岐接続体としての分岐枝管１３の内部に流通路１３″を有し、且つ先端部側に設けた押圧頭部１３′を球面１４′となすとともに、該球面に連ってその基部に直線部（円管壁）１４を有し、かつ押圧頭部１３′のなす曲率半径を分岐枝管１３の直径Ｄの０．４Ｄ乃至１０．０Ｄに設定して構成していた。そして高圧燃料本管側の開口傾斜状のそれぞれの受圧座面１２′に当接係合して組付けナットにより締着せしめて接続固定するものであった。
【０００３】
【発明が解決しようとする課題】
従来技術による前記接続構造としては、分岐枝管１３の接続に際して組付けナットによる締着により簡易に接続することができ、また、接続時の分岐枝管１３側の押圧頭部１３′での偏芯を締着につれて自動修正し、受圧座面１２′と円形線接触状態を保持して均一な面圧をもって接続固定することができ、その点満足し得るものではある。しかしながら、超高圧流の繰返し供給並びに加振下での長期の使用に際して直線部１４が剛性に乏しいために、撓みや倒れ等が発生し分岐枝管１３内部の流通路１３″の先端側に潰れに伴う該流通路１３″の狭小化が生じて流過抵抗の増大により正確な燃料噴射制御を阻害し、また不安定な“座り”や組付けナット側の緩みに起因して、未だ長期に亘りその接続を確実となし得ず、洩れを誘発する問題を有する傾向にあった。
【０００４】
本発明は従来技術の有する前記問題に鑑みてなされたものであり、従来技術と同様に接続に際しての分岐接続体側の押圧頭部での偏芯を締着に伴って自動修正する機能を損うことなく、さらに押圧頭部での剛性を高めて機械的強度を充分となしヘタリ等の永久変形を防止するとともに、該頭部の相手受圧座面での“座り”を安定となし、長期に亘り接続固定を確実とすることができ、かつ分岐接続体の流通路の狭小化を防止できる高圧燃料レールにおける分岐接続体の接続構造を提供することを目的とするものである。
【０００５】
【課題を解決するための手段】
前記目的を達成するために、本発明は、燃料レール本管内に軸方向に高圧燃料が流通する流通路が形成されるとともに前記流通路の周壁に軸方向の複数位置において貫孔が形成され、前記貫孔にそれぞれ前記流通路に通じる流路を有する分岐接続体が連設されるよう、前記燃料レール本管の周面方向に拡大開口した受圧座面が形成され、前記受圧座面に前記分岐接続体の端部に形成された押圧頭部を当接係合させて、前記分岐接続体側に組込んだナットを締着することにより、前記分岐接続体を前記燃料レール本管に固定する高圧燃料レールにおける分岐接続体の接続構造において、前記押圧頭部が、先端の球面状の押圧座面と、前記球面状の押圧座面の端部から軸方向に間隔をおいて形成された前記ナットと当接する環状フランジ部と、前記球面状の押圧座面に接するように接続されて形成された、前記環状フランジ部から前記球面状の押圧座面の先端に向って先細りとなる円錐面と、から形成されたことを要旨とし、さらに、前記円錐面と押圧座面のなす球面との環状境界線が前記受圧座面と当接係合するよう構成されたものである。
【０００６】
【作用】
本発明では、分岐接続体の端部に形成されている押圧頭部の先端には球面状の押圧座面が形成されているので、分岐接続体が燃料レールに対して僅かに傾き、例えその傾きが修正されずに保持されたまま組付けられたとしても、押圧座面は回転面からなる受圧座面と円形の線接触状態が保持されて均一な面圧が得られ接触部の気密は確実に保たれる。
【０００７】
一方、分岐接続体が僅かに偏心したり、傾いた状態となったとしても、締付けナットの締付けトルクによりシール面での面圧が上昇する前に押圧座面の球面が受圧座面の回転面を滑動して分岐接続体の偏心や傾きが自動的に修正され、押圧頭部と受圧断面との間に均一な面圧が得られる。
押圧頭部には、球面状の押圧座面に連って、該押圧座面から軸芯方向に間隔をおいて設けた環状フランジ部まで先端に向って先細りとなった剛性の高い円錐面が形成されているので、機械的強度を増して押圧頭部の撓みや倒れ等を防止し安定な“座り”を確保できるとともに、分岐接続体の流通路の狭小化を防止して適正な流通路径を確保し、燃料の流過抵抗の増大を抑制して正確な燃料噴射制御を可能とすることができる。
組み付けは受圧座面に分岐接続体の押圧頭部を当接係合してナットによる螺合によって、分岐接続体を燃料レールに固定するだけで簡単に行われるが、螺子を継手金具の外周に設けて袋ナットにより螺合するように構成してもよい。
【０００８】
【実施例】
以下、本発明の実施例を図１乃至図１０を参照して説明する。
ここで、図１は一実施例の正面図、図２は図１の一部断面正面図、図３および図４はそれぞれ異なる実施例の要部の説明図、図５は本発明の構成を示す説明図、図６（ａ）乃至（ｃ）は押圧頭部と受圧座面との圧接状態を示す部分拡大断面図、図７は本発明の動作を示す説明図、図８（ａ）および図９はそれぞれさらに他の実施例を示す図２相当図、図８（ｂ）は図８（ａ）で用いるブロックレールの斜視図、図１０はさらに別の実施例を示す図２相当図である。
【０００９】
図１に示すように、燃料レールとして設けられた本管１の軸心方向に直角に分岐接続体としての分岐枝管３が、継手金具４部分において、ナット５によって締着されている。図２に示すように、例えば外径２０ｍｍ、肉厚６ｍｍの比較的肉厚の金属管からなる本管１には流通路１′が形成され、この流通路１′には貫孔２′が形成され、この貫孔２′の端部には本管１の外周面方向に拡大開口した、貫孔２′の軸芯を中心とした回転面、即ち円錐面、回転円弧面、回転楕円面、回転放物線面、回転双曲線面等の形状を有する受圧座面２が形成されている。
本管１に対して受圧座面２を囲繞して継手金具４が設けられ、この継手金具４には螺子孔４′が形成されている。
【００１０】
分岐枝管３の端部には押圧頭部６が形成され、この押圧頭部６には、図３に示すように先端に球面状の押圧座面６′が形成され、また該押圧座面６′から軸芯方向に間隔をおいて半径方向に突出した環状フランジ部３′が形成されている。この押圧座面６′に連って環状フランジ部３′まで先端に向って先細りとなった円錐面６″が形成されている。そして、この円錐面６″は押圧座面６′のなす球面の接線方向に延長している。
なお、フランジ部３′は半径方向に突出させることなく、図４のように円錐面６″から直立するよう形成することもできる。
【００１１】
この実施例においては、図５に示すように特開平３−２７３５９９号と同様押圧座面６′の曲率半径γは分岐枝管３の直径Ｄに対して
０．４Ｄ≦γ≦１０Ｄ …（１）
の範囲に設定してあり、０．４Ｄ未満では締付けナット５の締付けトルクにより押圧座面６′が受圧座面２を突き抜け流通路１′内に突出してしまい、一方１０Ｄを超えると、押圧座面６′の輪郭が直線または円錐形に近くなり下記するような球面による自己修正作用等を期待できないからである。なお、好ましい範囲は０．４Ｄ≦γ≦４Ｄである。
【００１２】
分岐枝管３の押圧頭部６の押圧座面６′を受圧座面２に対接させた状態で、ナット５が螺子孔４′に締着されて、分岐接続体３が本管１に組み付けられ、ナット５の先端部が必要に応じ設けたワッシャ７を介して環状フランジ部３′を押圧するに伴い、図６（ａ）のように押圧座面６′と受圧座面２とが互いに圧接したり、図６（ｂ）のように円錐面６″と受圧座面２とが互いに圧接したりするが、図６（ｃ）のように押圧座面６′と円錐面６″との間の環状境界線６ａと受圧座面２とが互いに高い面圧で圧接することも可能であり、このようにして本管１の流通路１′が分岐枝管３の流路３″によって気密的に分岐されている。換言すると、前記受圧座面２は前記押圧頭部６の円錐面６″と前記押圧座面６′の球面の接線方向に延長する仮想面との間に位置するよう設けられている。
なお、前記環状境界線６ａは、ミクロ的視点では断面尖端状に突出しており、したがって受圧座面２と圧接すると該環状境界線６ａにより面圧が高まり気密効果は一層向上する。
【００１３】
上記実施例では押圧頭部６を直接受圧座面２に当接係合させる場合を示したが、押圧頭部６と受圧座面２との間にインジュウム、銀、銅、真鍮あるいはアルミニウム等からなるシール材を介在させてもよい。
【００１４】
次にこれら実施例において、例え分岐枝管３が軸心χ方向に対し僅かに傾き、かつその傾きが束縛された状態で組付された場合でも、押圧頭部６は回転面からなる受圧座面２と円形の線接触状態を保持するため、本管１に対して分岐枝管３は常に安定位置を保持して均一な面圧が得られ、一方、図７に示すように何らかの原因で分岐枝管３が軸心χ方向から僅かに傾いたり偏心したりすると、締付けナット５の螺合による締付けトルクによって環状フランジ部３′が押圧されてシール面での面圧が上昇する前に押圧頭部６の球面が受圧座面２の回転面を滑動し、このため分岐枝管３の傾きや偏心が所定位置に修正される（自己修正作用）ので、シール面において均一な面圧が得られ燃料洩れを起すことなく確実な超高圧燃料の供給が行われる。
【００１５】
押圧頭部６の押圧座面６′は球面なので、回転面である受圧座面２と円形の線接触をし、分岐枝管３が僅かに傾いたり偏心しても、回転面と円形の線接触は気密性を保持し、かつすでに述べたように自己修正作用によって分岐枝管３の傾きは修正されるので、燃料洩れ状態となることはない。
また、押圧頭部６の押圧座面６′の曲率半径γが（１）式に示す値に設定されているので、押圧頭部６は受圧座面２に対して、最適の範囲において対接し、確実で完全な気密性対接が行われる。
【００１６】
なお、上記実施例では受圧座面２を囲繞するよう継手金具４を設けたものについて説明したが、本発明は図８（ｂ）に示すように燃料レールとして本管１に代えてブロックレール１ａに適用することも可能である。図８に示す実施例では、継手金具４を設けることなく、流通路１′をブロックレール１ａに偏心して穿設し、その厚肉部に流通路１′と連通する貫孔２′、受圧座面２および螺子孔８を設け、この螺子孔８に直接締付けナット５を螺合し、ワッシャ７を介して接続するよう構成したものである。
【００１７】
さらに本発明は図９のような袋ナット５′も使用することができる。この袋ナット５′には中央に円柱状の突出部５′ａが形成されており、袋ナット５′の内周螺子５′ｂを継手金具４の外周の螺子４″に螺合するに伴いこの突出部５′ａによりワッシャ７を介して環状フランジ部３′を下方に押圧して押圧頭部６を受圧座面２に当接係合せしめるものである。
【００１８】
次に、図１０はさらに別の実施例の要部の縦断側面図であり、この実施例では分岐枝管３に代えて分岐接続体が分岐金具３ａで構成されている。この実施例は分岐接続体を曲げ加工するに際し、大きな曲率に伴って生じる他の部品との干渉を避けるために、エルボ等の分岐金具を用いる場合や等圧弁、減衰弁、送出し弁および吐出弁等の機構を内設する分岐金具を使用する場合等を考慮してなされたものである。
図１０の実施例では、分岐金具３ａの一端には前記実施例と同様に押圧頭部６に球面状の押圧座面６′、環状フランジ部３′および該押圧座面と環状フランジ部とに連なる円錐面６″とを有し、ナット５の外周に設けた螺子５″を継手金具４の螺子孔４′に螺合することにより環状フランジ部３′を介して本管１の受圧座面２に分岐金具３ａの接続頭部６を当接係合させている。一方分岐金具３ａの他端にはスリーブ９を介して袋ナット１０を螺合することにより分岐枝管３が接続される構成となっている。
この実施例によると、本管１の長手方向に平行に分岐枝管３を導出することができる。
【００１９】
【発明の効果】
以上詳細に説明したように、本発明によると、押圧座面の球面によって分岐接続体が傾いた状態で組付けられたとしても押圧頭部は受圧座面と円形の線接触状態を保持されて均一な面圧が得られ、一方、分岐接続体の偏心や傾きがあっても、締付けナットの締付けトルクによりシール面での面圧が上昇する前に押圧座面の球面が受圧座面を滑動して分岐接続体の偏心や傾き等は自動的に修正されて均一な面圧を得ることができ、さらに、燃料レールに対して分岐接続体を簡単な操作で気密的に固定することが可能となり、また円錐面を設けて剛性を増したため、ヘタリ等の永久変形が防止できるとともに、受圧座面に対する“座り”が安定し、超高圧燃料流の繰り返し加圧やディーゼル内燃機関の振動に対して燃料の飛散による洩れや接続部の離脱の発生を防止し、さらに分岐接続体の流通路の狭小化を阻止して適正な流通路径を確保し、流過抵抗の増大を抑制して燃料の流れを円滑にし正確な燃料噴射制御を可能にすることができる高圧燃料レールにおける分岐接続体の接続構造を提供することができる。
【図面の簡単な説明】
【図１】本発明の一実施例の正面図である。
【図２】図１の一部断面正面図である。
【図３】本発明の要部の一実施例を示す図である。
【図４】他の実施例の図３相当図である。
【図５】本発明の構成を示す説明図である。
【図６】本発明の圧接状態を示す部分拡大断面図で、（ａ）は押圧座面と受圧座面とが互いに圧接した状態を示す図、（ｂ）は円錐面と受圧座面とが互いに圧接した状態を示す図、（ｃ）は押圧座面と円錐面との間の環状境界線と受圧座面とが互いに圧接した状態を示す図である。
【図７】本発明の動作を示す説明図である。
【図８】本発明の他の実施例を示す図で、（ａ）は図２相当図、（ｂ）は（ａ）に用いるブロックレールの斜視図である。
【図９】さらに他の実施例を示す図２相当図である。
【図１０】さらに別の実施例を示す図２相当図である。
【図１１】従来の高圧燃料レールにおける分岐接続体の接続構造の要部を示す図である。
【符号の説明】
１本管
１ａブロックレール
１′ 流通路
２受圧座面
２′ 貫孔
３分岐枝管
３ａ分岐金具
３′ 環状フランジ部
３″ 流路
４継手金具
４′ 螺子孔
５ナット
５′ 袋ナット
５′ａ突出部
５′ｂ螺子
５″ 螺子
６′ 押圧座面
６″ 円錐面
６ａ環状境界線
７ワッシャ
８螺子孔
９スリーブ９
１０袋ナット１０[0001]
[Industrial application fields]
The present invention relates to a connection structure of a branch connection body such as a branch branch pipe or a branch fitting in a high pressure fuel rail such as a high pressure fuel manifold or a block rail, and more particularly 1000 kgf / cm ² serving as a fuel supply path to a diesel internal combustion engine. The present invention relates to the connection structure of the branch connection body in the above high-pressure fuel rail.
[0002]
[Prior art]
Conventionally, a connection structure of this kind of branch connection body has been proposed by the present applicant in Japanese Patent Laid-Open No. 3-273599. This is illustrated in FIG. A pressing head 13 ′ having a flow passage 13 ″ inside and a pressing head 13 ′ provided on the tip end side is formed as a spherical surface 14 ′, and a linear portion (circular tube wall) 14 is provided at the base of the spherical surface. In addition, the radius of curvature formed by the pressing head 13 'is set to 0.4D to 10.0D, which is the diameter D of the branch branch pipe 13. And each of the pressure receiving pressures on the inclined side of the high-pressure fuel main pipe is inclined. The bearing surface 12 ′ is abutted and engaged, and is fastened and fixed by an assembly nut.
[0003]
[Problems to be solved by the invention]
The connection structure according to the prior art can be easily connected by fastening with an assembly nut when connecting the branch branch pipe 13, and the bias head 13 'on the side of the branch branch pipe 13 at the time of connection is also offset. The core is automatically corrected as it is tightened, and the pressure receiving seat surface 12 'can be kept in contact with the circular line and connected and fixed with a uniform surface pressure, which is satisfactory. However, since the straight portion 14 has poor rigidity when it is repeatedly supplied with an ultrahigh pressure flow and used for a long time under vibration, the straight portion 14 is bent and collapsed, and is collapsed to the front end side of the flow passage 13 ″ inside the branch branch pipe 13. As a result, the flow passage 13 ″ is narrowed to prevent accurate fuel injection control due to an increase in the flow resistance, and due to unstable “sitting” and loosening of the assembly nut, However, there was a tendency that the connection could not be made reliably and had a problem of inducing leakage.
[0004]
The present invention has been made in view of the above-described problems of the prior art, and as in the prior art, the function of automatically correcting the eccentricity at the pressing head on the side of the branch connector upon connection with the fastening is impaired. In addition, the rigidity at the pressing head is further increased to ensure sufficient mechanical strength and prevent permanent deformation such as settling, and stable "sitting" on the mating pressure bearing surface of the head is achieved for a long time. It is an object of the present invention to provide a connection structure for a branch connection body in a high-pressure fuel rail that can reliably secure the connection and prevent the flow path of the branch connection body from being narrowed.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has a flow passage in which high-pressure fuel flows in the axial direction in the fuel rail main pipe, and through holes are formed at a plurality of positions in the axial direction on the peripheral wall of the flow passage. A pressure receiving seat surface that is enlarged and opened in the circumferential direction of the fuel rail main pipe is formed so that a branched connection body having a flow path that communicates with the flow passage is connected to the through hole, and the pressure receiving seat surface is provided with the pressure receiving seat surface. The branch connection body is fixed to the fuel rail main pipe by abutting and engaging the pressing head formed at the end of the branch connection body and fastening the nut incorporated on the branch connection body side. In the connection structure of the branch connection body in the high-pressure fuel rail, the pressing head is formed with a spherical pressing seat surface at the tip and an end spaced from the end of the spherical pressing seat surface in the axial direction. An annular flange that contacts the nut and the front Is formed by connecting in contact with the spherical pressing seat surface, and summarized in that the conical surface that tapers toward from said annular flange portion to the distal end of the spherical pressing seat surface, formed from, Furthermore, an annular boundary line between the conical surface and the spherical surface formed by the pressing seat surface is configured to abut and engage with the pressure receiving seat surface.
[0006]
[Action]
In the present invention, since the spherical pressing seat surface is formed at the tip of the pressing head formed at the end of the branch connector, the branch connector is slightly inclined with respect to the fuel rail. Even if the pressure seat is assembled without being corrected, the pressing seat surface maintains a circular line contact state with the pressure receiving seat surface, which is a rotating surface, and a uniform surface pressure is obtained, and the air tightness of the contact portion is Securely kept.
[0007]
On the other hand, even if the branch connector is slightly decentered or inclined, the spherical surface of the pressure seat surface becomes the rotational surface of the pressure-receiving seat surface before the surface pressure on the seal surface rises due to the tightening torque of the tightening nut. , The eccentricity and inclination of the branch connection body are automatically corrected, and a uniform surface pressure is obtained between the pressing head and the pressure receiving section.
The pressing head has a highly rigid conical surface that is tapered toward the tip from the pressing seat surface to an annular flange portion that is spaced from the pressing seat surface in the axial direction along the spherical pressing seat surface. Since it is formed, it can increase the mechanical strength to prevent bending and falling of the pressing head and ensure a stable “sitting”, and prevent the narrowing of the flow path of the branch connection body and the appropriate flow path diameter. Can be ensured, and an increase in fuel flow resistance can be suppressed to enable accurate fuel injection control.
Assembly is done simply by abutting and engaging the pressing head of the branch connector to the pressure-receiving seat surface and screwing the nut to the fuel rail by screwing with a nut. It may be configured to be provided and screwed with a cap nut.
[0008]
【Example】
Embodiments of the present invention will be described below with reference to FIGS.
Here, FIG. 1 is a front view of one embodiment, FIG. 2 is a partially sectional front view of FIG. 1, FIGS. 3 and 4 are explanatory views of main parts of different embodiments, and FIG. 5 is a configuration of the present invention. 6 (a) to 6 (c) are partially enlarged sectional views showing the press contact state between the pressing head and the pressure receiving seat surface, FIG. 7 is an explanatory view showing the operation of the present invention, FIG. 8 (a) and FIG. FIG. 9 is a view corresponding to FIG. 2 showing another embodiment, FIG. 8B is a perspective view of the block rail used in FIG. 8A, and FIG. 10 is a view corresponding to FIG. is there.
[0009]
As shown in FIG. 1, a branch branch pipe 3 as a branch connection body perpendicular to the axial direction of the main pipe 1 provided as a fuel rail is fastened by a nut 5 at a joint fitting 4 portion. As shown in FIG. 2, a flow passage 1 'is formed in the main pipe 1 made of a relatively thick metal tube having an outer diameter of 20 mm and a thickness of 6 mm, for example, and a through hole 2' is formed in the flow passage 1 '. At the end of this through hole 2 ′, a rotating surface centering on the axis of the through hole 2 ′, ie, a conical surface, a rotating arc surface, a rotating ellipsoid, which is enlarged and opened toward the outer peripheral surface of the main pipe 1 is formed. A pressure receiving seat surface 2 having a shape such as a rotating parabolic surface, a rotating hyperbolic surface or the like is formed.
A joint fitting 4 is provided surrounding the pressure-receiving seat surface 2 with respect to the main pipe 1, and a screw hole 4 ′ is formed in the joint fitting 4.
[0010]
A pressing head 6 is formed at the end of the branch branch pipe 3, and a spherical pressing seat surface 6 'is formed at the tip of the pressing head 6 as shown in FIG. An annular flange portion 3 ′ protruding in the radial direction at an interval in the axial direction from 6 ′ is formed. A conical surface 6 "tapering toward the tip is formed to the annular flange portion 3 'continuously with the pressing seat surface 6'. The conical surface 6" is a spherical surface formed by the pressing seat surface 6 '. It extends in the tangential direction.
The flange portion 3 'can be formed so as to stand upright from the conical surface 6 "as shown in FIG. 4 without protruding in the radial direction.
[0011]
In this embodiment, as shown in FIG. 5, the radius of curvature γ of the pressing seat surface 6 ′ is 0.4D ≦ γ ≦ 10D (1) with respect to the diameter D of the branch branch pipe 3 as in Japanese Patent Laid-Open No. 3-273599. )
In the range of less than 0.4D, the pressing seat surface 6 'protrudes through the pressure receiving seat surface 2 due to the tightening torque of the tightening nut 5, and protrudes into the flow passage 1'. This is because the contour of the surface 6 'is close to a straight line or a conical shape, and the self-correcting action by the spherical surface as described below cannot be expected. A preferred range is 0.4D ≦ γ ≦ 4D.
[0012]
In a state where the pressing seat surface 6 ′ of the pressing head 6 of the branch branch pipe 3 is in contact with the pressure receiving seat surface 2, the nut 5 is fastened to the screw hole 4 ′ and the branch connector 3 is attached to the main pipe 1. As shown in FIG. 6A, the pressing seat surface 6 'and the pressure-receiving seat surface 2 are brought together as the tip end portion of the nut 5 presses the annular flange portion 3' through a washer 7 provided as necessary. The conical surface 6 ″ and the pressure-receiving seat surface 2 are in pressure contact with each other as shown in FIG. 6B, but the pressing seat surface 6 ′ and the conical surface 6 ″ as shown in FIG. 6C. It is also possible for the annular boundary line 6a and the pressure-receiving seat surface 2 to be brought into pressure contact with each other with a high surface pressure. In this way, the flow passage 1 'of the main pipe 1 is formed by the flow path 3 "of the branch branch pipe 3. In other words, the pressure-receiving seat surface 2 extends temporarily in a tangential direction between the conical surface 6 ″ of the pressing head 6 and the spherical surface of the pressing seat surface 6 ′. It is provided so as to be positioned between the surfaces.
Note that the annular boundary line 6a protrudes in a tip-like shape from a microscopic viewpoint. Therefore, when the pressure receiving seat surface 2 is pressed, the surface pressure is increased by the annular boundary line 6a, and the airtight effect is further improved.
[0013]
In the above-described embodiment, the pressing head 6 is directly contacted and engaged with the pressure-receiving seat surface 2, but between the pressing head 6 and the pressure-receiving seat surface 2 is made of indium, silver, copper, brass, aluminum, or the like. A sealing material may be interposed.
[0014]
Next, in these embodiments, even when the branch branch pipe 3 is assembled with a slight inclination with respect to the axial center χ direction and the inclination is constrained, the pressing head 6 has a pressure receiving seat made of a rotating surface. In order to maintain the circular line contact state with the surface 2, the branch branch pipe 3 always maintains a stable position with respect to the main pipe 1 to obtain a uniform surface pressure. On the other hand, as shown in FIG. When the branch branch pipe 3 is slightly tilted or decentered from the axial center χ direction, the annular flange portion 3 ′ is pressed by the tightening torque due to the screwing of the tightening nut 5 and pressed before the surface pressure on the seal surface rises. The spherical surface of the head 6 slides on the rotational surface of the pressure-receiving seating surface 2, so that the inclination and eccentricity of the branch branch pipe 3 are corrected to predetermined positions (self-correcting action), so that a uniform surface pressure is obtained on the sealing surface. Therefore, the ultra-high pressure fuel can be reliably supplied without causing fuel leakage.
[0015]
Since the pressing seat surface 6 ′ of the pressing head 6 is a spherical surface, it makes circular line contact with the pressure receiving seat surface 2 that is the rotating surface, and even if the branch branch pipe 3 is slightly tilted or eccentric, it makes circular contact with the rotating surface. The airtightness is maintained, and the inclination of the branch branch pipe 3 is corrected by the self-correcting action as described above, so that no fuel leakage occurs.
Further, since the radius of curvature γ of the pressing seat surface 6 ′ of the pressing head 6 is set to the value shown in the expression (1), the pressing head 6 contacts the pressure receiving seat surface 2 in the optimum range. A reliable and complete hermetic interview is performed.
[0016]
In the above embodiment, the joint metal fitting 4 is provided so as to surround the pressure-receiving seat surface 2, but the present invention replaces the main pipe 1 as a fuel rail with a block rail 1a as shown in FIG. 8 (b). It is also possible to apply to. In the embodiment shown in FIG. 8, the flow passage 1 ′ is eccentrically drilled in the block rail 1 a without providing the joint fitting 4, and a through hole 2 ′ communicating with the flow passage 1 ′ is formed in the thick portion thereof, and the pressure receiving seat. The surface 2 and the screw hole 8 are provided, and the tightening nut 5 is screwed directly into the screw hole 8 and connected via the washer 7.
[0017]
Furthermore, the present invention can also use a cap nut 5 'as shown in FIG. The cap nut 5 'is formed with a cylindrical protrusion 5'a at the center, and the inner peripheral screw 5'b of the cap nut 5' is screwed to the outer screw 4 "of the fitting 4. The projecting portion 5'a presses the annular flange portion 3 'downward through the washer 7 so that the pressing head 6 is brought into contact with and engaged with the pressure receiving seat surface 2.
[0018]
Next, FIG. 10 is a longitudinal side view of a main part of still another embodiment. In this embodiment, a branch connection body is constituted by a branch fitting 3a instead of the branch branch pipe 3. In this embodiment, when bending a branch connector, in order to avoid interference with other parts caused by a large curvature, a branch fitting such as an elbow is used, an isobaric valve, a damping valve, a delivery valve, and a discharge. This is made in consideration of the case of using a branch metal fitting with a mechanism such as a valve.
In the embodiment of FIG. 10, at one end of the branch fitting 3a, a spherical pressing seat surface 6 ', an annular flange portion 3', and the pressing seat surface and the annular flange portion are formed on the pressing head 6 in the same manner as in the previous embodiment. The pressure receiving seating surface of the main pipe 1 through the annular flange portion 3 ′ by screwing a screw 5 ″ provided on the outer periphery of the nut 5 into the screw hole 4 ′ of the fitting 4. 2, the connection head 6 of the branch fitting 3a is brought into abutment. On the other hand, the branch branch pipe 3 is connected to the other end of the branch fitting 3 a by screwing a cap nut 10 through a sleeve 9.
According to this embodiment, the branch branch pipe 3 can be led out parallel to the longitudinal direction of the main pipe 1.
[0019]
【The invention's effect】
As described above in detail, according to the present invention, even if the branch connector is assembled in a tilted state by the spherical surface of the pressing seat surface, the pressing head is maintained in a circular line contact state with the pressure receiving seat surface. Uniform surface pressure can be obtained. On the other hand, even if the branch connector is eccentric or inclined, the spherical surface of the pressure seat slides on the pressure-receiving seat surface before the surface pressure on the seal surface increases due to the tightening torque of the tightening nut. The eccentricity and inclination of the branch connector can be automatically corrected to obtain a uniform surface pressure. Furthermore, the branch connector can be hermetically fixed to the fuel rail with a simple operation. In addition, since the conical surface is provided to increase rigidity, permanent deformation such as settling can be prevented, and “sitting” with respect to the pressure-receiving seat surface is stable, and against repeated pressurization of ultrahigh-pressure fuel flow and vibration of the diesel internal combustion engine Leakage and connection due to fuel scattering Prevents separation and prevents narrowing of the flow path of the branch connection body to ensure an appropriate flow path diameter, suppresses increase in flow resistance, smoothes the fuel flow, and performs accurate fuel injection control. It is possible to provide a connection structure for a branch connection in a high-pressure fuel rail that can be made possible.
[Brief description of the drawings]
FIG. 1 is a front view of an embodiment of the present invention.
2 is a partial cross-sectional front view of FIG. 1. FIG.
FIG. 3 is a diagram showing an embodiment of the main part of the present invention.
FIG. 4 is a view corresponding to FIG. 3 of another embodiment.
FIG. 5 is an explanatory diagram showing a configuration of the present invention.
6A and 6B are partially enlarged sectional views showing a pressure contact state of the present invention, in which FIG. 6A is a view showing a state in which a pressing seat surface and a pressure receiving seat surface are in pressure contact with each other, and FIG. 6B is a view showing a conical surface and a pressure receiving seat surface; The figure which shows the state which mutually pressed-contacted, (c) is a figure which shows the state which the annular boundary line between a press seat surface and a conical surface, and the pressure-receiving seat surface mutually press-contacted.
FIG. 7 is an explanatory diagram showing the operation of the present invention.
8A and 8B are diagrams showing another embodiment of the present invention, in which FIG. 8A is a view corresponding to FIG. 2 and FIG. 8B is a perspective view of a block rail used in FIG.
FIG. 9 is a view corresponding to FIG. 2, showing still another embodiment.
FIG. 10 is a view corresponding to FIG. 2, showing still another embodiment.
FIG. 11 is a diagram showing a main part of a connection structure of a branch connection body in a conventional high-pressure fuel rail.
[Explanation of symbols]
1 Main pipe 1a Block rail 1 'Flow path 2 Pressure-receiving seat surface 2' Through hole 3 Branch branch pipe 3a Branch fitting 3 'Annular flange 3 "Channel 4 Joint fitting 4' Screw hole 5 Nut 5 'Cap nut 5'a Projection 5′b Screw 5 ″ Screw 6 ′ Pressing seat surface 6 ″ Conical surface 6a Annular boundary 7 Washer 8 Screw hole 9 Sleeve 9
10 Cap nut 10

Claims

燃料レール本管内に軸方向に高圧燃料が流通する流通路が形成されるとともに前記流通路の周壁に軸方向の複数位置において貫孔が形成され、前記貫孔にそれぞれ前記流通路に通じる流路を有する分岐接続体が連設されるよう、前記燃料レール本管の周面方向に拡大開口した受圧座面が形成され、前記受圧座面に前記分岐接続体の端部に形成された押圧頭部を当接係合させて、前記分岐接続体側に組込んだナットを締着することにより、前記分岐接続体を前記燃料レール本管に固定する高圧燃料レールにおける分岐接続体の接続構造において、前記押圧頭部が、先端の球面状の押圧座面と、前記球面状の押圧座面の端部から軸方向に間隔をおいて形成された前記ナットと当接する環状フランジ部と、前記球面状の押圧座面に接するように接続されて形成された、前記環状フランジ部から前記球面状の押圧座面の先端に向って先細りとなる円錐面と、から形成されたことを特徴とする高圧燃料レールにおける分岐接続体の接続構造。A flow passage through which high-pressure fuel flows in the axial direction in the fuel rail main pipe is formed, and through holes are formed at a plurality of positions in the axial direction on the peripheral wall of the flow passage, and the flow paths respectively lead to the flow passages. A pressure receiving seat surface that is enlarged and opened in the circumferential direction of the fuel rail main pipe is formed so that a branch connection body having the following structure is continuously provided, and a pressure head formed on an end portion of the branch connection body on the pressure receiving seat surface In the connection structure of the branch connection body in the high-pressure fuel rail that fixes the branch connection body to the fuel rail main pipe by tightening the nut assembled on the side of the branch connection body by abutting and engaging the part, The pressing head includes a spherical pressing seat surface at the tip, an annular flange portion that contacts the nut formed at an axial distance from an end of the spherical pressing seat surface, and the spherical shape. Connect so that it touches the pressing seat The formed connection structure of the branch connector in the high-pressure fuel rail, characterized in that the conical surface that tapers toward from said annular flange portion to the distal end of the spherical pressing seat surface, formed from.

前記円錐面と押圧座面のなす球面との環状境界線が前記受圧座面と当接係合することを特徴とする請求項１に記載の高圧燃料レールにおける分岐接続体の接続構造。2. The connection structure for a branch connector in a high-pressure fuel rail according to claim 1, wherein an annular boundary line between the conical surface and the spherical surface formed by the pressing seat surface abuts on and engages with the pressure receiving seat surface.