JP2011099358A

JP2011099358A - Fuel injection valve

Info

Publication number: JP2011099358A
Application number: JP2009253444A
Authority: JP
Inventors: Toyoji Nishiwaki; 豊治西脇; Yoshiharu Nonoyama; 由晴野々山; Hiroaki Nagatomo; 宏明永友
Original assignee: Denso Corp; Nippon Soken Inc
Current assignee: Denso Corp; Soken Inc
Priority date: 2009-11-04
Filing date: 2009-11-04
Publication date: 2011-05-19
Also published as: DE102010043324A1

Abstract

PROBLEM TO BE SOLVED: To obtain a fuel injection valve in which a required suction power (operation energy) can be reduced, a solenoid is reduced in size, a stable position for a balance rod can be determined, and an injection performance is stable. SOLUTION: The fuel injection valve includes a flange part 11a of a balance rod 11 which a position thereof is determined by a compression spring position determining member 5, and a compression spring 10. The fuel injection valve also includes a needle 7 constituted by an integrally molded piece surrounding the balance rod 11 and coupled to a core. A fuel chamber 35 is formed around the needle 7 and a body formed with a sheet surface 16 is provided to a needle tip part. The fuel injection valve further includes a pressure receiving part 19 for applying a fuel pressure of fuel inside the fuel chamber 35, together with an electromagnetic force of the solenoid in a valve opening direction, to the needle 7 by the force or stronger having a total force of a pressing force of the needle 7 in a direction toward the sheet surface by the compression spring 10 and a slide-resistant force of the needle 7. Moreover, relations among a sheet diameter d1, a needle outer diameter d2 and an outer diameter d3 of a large diameter part are set to be d2>d1=d3. COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、エンジン内に燃料を噴射する燃料噴射弁に関するものであり、特に、高い燃料圧での低電流駆動（低エネルギ駆動）において有効な燃料噴射弁に関するものである。 The present invention relates to a fuel injection valve that injects fuel into an engine, and more particularly to a fuel injection valve that is effective in low current driving (low energy driving) at a high fuel pressure.

従来、燃料噴射弁内にニードルを昇降可能に収容し、そのニードルを昇降駆動して噴孔を開閉するようにしている。そのニードルの駆動方式として、特許文献１に知られているような直動タイプがある。直動タイプの燃料噴射弁は、ソレノイドや圧電素子などのアクチュエータによりニードルを直接駆動して、ニードルを引き上げるものである。 Conventionally, a needle is accommodated in a fuel injection valve so as to be movable up and down, and the needle is driven up and down to open and close the nozzle hole. As a driving method of the needle, there is a linear motion type as known in Patent Document 1. The direct-acting type fuel injection valve is configured to pull up the needle by directly driving the needle by an actuator such as a solenoid or a piezoelectric element.

この直動タイプの燃料噴射弁では、図２の（ｄ）に示すように、ソレノイドの非通電時には、圧縮ばねの圧縮ばね力（付勢力）Ｆｓｐｇｄにより、ニードルが、閉弁位置に保持される。この時、噴孔が閉じ、燃料噴射弁による燃料噴射が停止される。 In this direct acting type fuel injection valve, as shown in FIG. 2D, when the solenoid is not energized, the needle is held in the closed position by the compression spring force (biasing force) Fspgd of the compression spring. . At this time, the nozzle hole is closed and fuel injection by the fuel injection valve is stopped.

一方、開弁時は、ソレノイドが通電されると可動コアが、固定コアに吸引され、圧縮ばねの圧縮ばね力Ｆｓｐｇｄに抗して、ニードルが開弁側に移動する。これにより、噴孔が開き、燃料噴射が行われるものである。 On the other hand, at the time of valve opening, when the solenoid is energized, the movable core is attracted to the fixed core, and the needle moves to the valve opening side against the compression spring force Fspgd of the compression spring. Thereby, an injection hole opens and fuel injection is performed.

また、供給された燃料の燃圧力Ｆｐｆｄをニードルで受けるため、開弁するためには、その燃圧力Ｆｐｆｄとニードルの閉弁動作のために付勢される圧縮ばね力Ｆｓｐｇｄ及び摺動抵抗力Ｆｒｄの合力以上の強い電磁吸引力（必要吸引力）Ｆｓｄが必要となる。そのため、ソレノイドが大型化（高エネルギ化）するという問題が有った。 In order to open the valve to receive the fuel pressure Fpfd of the supplied fuel with the needle, the fuel pressure Fpfd and the compression spring force Fspgd and the sliding resistance force Frd biased for the valve closing operation of the needle are required. A strong electromagnetic attraction force (necessary attraction force) Fsd greater than the resultant force is required. Therefore, there has been a problem that the solenoid becomes larger (higher energy).

このような問題に鑑みて、特許文献２に記載の燃料噴射弁が知られている。図３は、従来の特許文献２に記載の燃料噴射弁の縦断面図である。図４は、図３の燃料噴射弁におけるニードルの円錐状先端面周りの拡大図である。 In view of such a problem, a fuel injection valve described in Patent Document 2 is known. FIG. 3 is a longitudinal sectional view of a conventional fuel injection valve described in Patent Document 2. FIG. 4 is an enlarged view around the conical tip surface of the needle in the fuel injection valve of FIG. 3.

この特許文献２の燃料噴射弁は、図３及び図４に示すように、ニードル７に、開弁時にも閉弁時にも、燃料圧による開弁方向及び閉弁方向の力が発生しないものである。 As shown in FIGS. 3 and 4, the fuel injection valve of Patent Document 2 does not generate force in the valve opening direction and the valve closing direction due to the fuel pressure, even when the needle 7 is opened or closed. is there.

即ち、図３のニードル７は、圧縮ばね１０の圧縮ばね力により閉弁せしめられる構造である。また、ソレノイド９を励磁すれば、そのとき発生する電磁吸引力によってニードル７が開弁する。 That is, the needle 7 in FIG. 3 has a structure that can be closed by the compression spring force of the compression spring 10. When the solenoid 9 is excited, the needle 7 is opened by the electromagnetic attractive force generated at that time.

この場合、圧縮ばね１０の圧縮ばね力および摺動抵抗力に打ち勝つだけの電磁吸引力を発生させればよいので、小さな吸引力を発生するだけで充分であり、従って、ソレノイド９として、小型のものを用いることができる（低エネルギ化できる）。 In this case, since it is sufficient to generate an electromagnetic attractive force that can overcome the compression spring force and sliding resistance force of the compression spring 10, it is sufficient to generate a small attractive force. A thing can be used (low energy can be reduced).

具体的には、上記作用効果を得るために、次の構造を採用している。即ち、図４のシート面１６の当接部２０、２１間のシート径ｄ１と、図３の環状段部４０の上方におけるニードル小径部４１の径ｄ２ｓと、バランスロッド受容孔７ａ内の大径部１１ｂの外径ｄ３とが等しく形成されている（ｄ１＝ｄ２ｓ＝ｄ３）。 Specifically, in order to obtain the above-described effects, the following structure is adopted. That is, the sheet diameter d1 between the contact portions 20 and 21 of the seat surface 16 in FIG. 4, the diameter d2s of the needle small diameter portion 41 above the annular step portion 40 in FIG. 3, and the large diameter in the balance rod receiving hole 7a. The outer diameter d3 of the part 11b is formed to be equal (d1 = d2s = d3).

それによって、ニードル７が閉弁していようと、開弁していようと、ニードル７の閉弁方向に作用する燃料圧と、ニードル７の開弁方向に作用する燃料圧とを、常にバランスさせるようにしている。 Accordingly, whether the needle 7 is closed or opened, the fuel pressure acting in the valve closing direction of the needle 7 and the fuel pressure acting in the valve opening direction of the needle 7 are always balanced. I am doing so.

換言すれば、ニードル７が閉弁し、ニードル７が、図４のシート面１６の当接部２０、２１に着座しているときには、ニードル７の先端面周辺部４５（図４）に作用する燃料圧と、図３の各環状段部４０、４６に作用する燃料圧とが等しい。 In other words, when the needle 7 is closed and the needle 7 is seated on the contact portions 20 and 21 of the seat surface 16 in FIG. 4, the needle 7 acts on the peripheral portion 45 (FIG. 4) of the distal end surface of the needle 7. The fuel pressure is equal to the fuel pressure acting on each annular step 40, 46 in FIG.

即ち、ニードル７が閉成し、静止しているときには、ニードル７の先端面周辺部４５（図４）の燃料圧と、各環状断部４０及び４６（図３）の燃料圧とが等しい。また、このとき、ニードル７の先端面中央部５０（図４）と圧力室１７（図３）とには、極めて小さな圧力ではあるが、同じ燃料圧が加わっている。 That is, when the needle 7 is closed and stationary, the fuel pressure at the peripheral portion 45 (FIG. 4) of the tip surface of the needle 7 is equal to the fuel pressure at each of the annular cut portions 40 and 46 (FIG. 3). Further, at this time, the same fuel pressure is applied to the center portion 50 (FIG. 4) and the pressure chamber 17 (FIG. 3) of the tip surface of the needle 7 although the pressure is extremely small.

ところが、上述したように、シート面１６のシート径ｄ１（図３、図４）と、ニードル小径部４１の外径ｄ２ｓとが等しいので、図４の先端面周辺部４５に加わる開弁方向の燃料圧と、各環状段部４０、４６（図３）に加わる閉弁方向の燃料圧とが等しくなっている。また、シート面１６のシート径ｄ１とバランスロッド受容孔７ａ内の大径部１１ｂの外径ｄ３とが等しくなっている。そのために、先端面中央部５０（図４）に加わる開弁方向の燃料圧と、バランスロッド受容孔７ａ（図３）内の圧力室１７に加わる閉弁方向の燃料圧とが等しくなる。 However, as described above, since the seat diameter d1 (FIGS. 3 and 4) of the seat surface 16 is equal to the outer diameter d2s of the needle small diameter portion 41, the valve opening direction applied to the distal end surface peripheral portion 45 of FIG. The fuel pressure and the fuel pressure in the valve closing direction applied to each annular step 40, 46 (FIG. 3) are equal. Further, the seat diameter d1 of the seat surface 16 is equal to the outer diameter d3 of the large diameter portion 11b in the balance rod receiving hole 7a. Therefore, the fuel pressure in the valve opening direction applied to the center portion 50 (FIG. 4) of the tip surface is equal to the fuel pressure in the valve closing direction applied to the pressure chamber 17 in the balance rod receiving hole 7a (FIG. 3).

従って、ニードル７には、燃料圧による開弁方向の力も閉弁方向の力も発生しないことになる。この特許文献２に記載された燃料噴射弁の開弁開始時に、ニードル７に働く外力を示したのが、図２の（ｃ）である。 Therefore, neither force in the valve opening direction nor force in the valve closing direction due to the fuel pressure is generated in the needle 7. FIG. 2C shows an external force acting on the needle 7 when the fuel injection valve described in Patent Document 2 starts to open.

この図２の（ｃ）のように、ニードル７を動かすのに必要な摺動抵抗力Ｆｒｃと、圧縮ばね力Ｆｓｐｇｃに対して、ソレノイド９の必要吸引力Ｆｓｃが、バランスする以上の力を出せば開弁でき、燃料圧は考慮しなくても良いため、ソレノイド９による必要吸引力Ｆｓｃを小さくすることが出来る。従って、上記特許文献２の構造は、ソレノイド９の小型化（低エネルギ化）という点で優れている。 As shown in FIG. 2 (c), the necessary suction force Fsc of the solenoid 9 can be more than balanced against the sliding resistance force Frc necessary for moving the needle 7 and the compression spring force Fspgc. Therefore, the required suction force Fsc by the solenoid 9 can be reduced because the fuel pressure need not be considered. Therefore, the structure of Patent Document 2 is excellent in terms of downsizing (reducing energy) of the solenoid 9.

特開２００３−１１３７５４号公報JP 2003-113754 A 特開２００５−２６４８２２号公報JP 2005-264822 A

ところが、上記特許文献２の技術では、以下の問題がある。第１に、バランスロッド１１の軸方向位置が拘束されていない（バランスロッド１１は上方においてステータコア６０に当接しているが、燃料圧によって宙に浮いている状態であり、下方に動き得る）ため、噴射時に、ニードル７とバランスロッド１１トータルの慣性質量が、噴射空間圧力やエンジン振動などで変化し、噴射量がばらつくという問題がある。 However, the technique of Patent Document 2 has the following problems. First, the axial position of the balance rod 11 is not constrained (the balance rod 11 is in contact with the stator core 60 in the upper part, but is floating in the air due to fuel pressure and can move downward). During injection, there is a problem that the total inertial mass of the needle 7 and the balance rod 11 changes due to injection space pressure, engine vibration, etc., and the injection amount varies.

第２に、可動部品点数が多く、構造が複雑である。かつ、このために、接合部が多く、組み付け性が悪く、組み付け精度も悪く成り易いという問題がある。第３に、ニードルリフト量の調整、あるいは圧縮ばね力を調整する機構が存在しないという問題がある。 Second, the number of moving parts is large and the structure is complicated. For this reason, there are problems that there are many joints, the assembling property is poor, and the assembling accuracy is liable to deteriorate. Thirdly, there is a problem that there is no mechanism for adjusting the needle lift amount or adjusting the compression spring force.

以下、これについて、更に詳述する。先ず、構造が複雑な点について説明すると、図３に示すように、ニードル小径部４１のニードル大径部５５側には、ニードル膨大部５６が形成されている。 This will be described in further detail below. First, the complicated structure will be described. As shown in FIG. 3, a large needle portion 56 is formed on the needle large diameter portion 55 side of the needle small diameter portion 41.

バランスロッド受容孔７ａ内の大径部１１ｂをニードル内部に組み付けるためには、ニードル７をニードル大径部５５とニードル膨大部５６に切り分けないと組み付けられない。よって、部品点数大かつ組み付け性が悪い。 In order to assemble the large diameter portion 11 b in the balance rod receiving hole 7 a inside the needle, the needle 7 cannot be assembled unless it is separated into the needle large diameter portion 55 and the needle enormous portion 56. Therefore, the number of parts is large and the assemblability is poor.

また、ニードル７のニードル小径部４１に連結された可動のコア（吸引板）１２が、上方でステータコア６０に吸引されるが、圧縮ばね１０の圧縮ばね力の調整機構は、特に存在しないことが明らかである。またニードル７のニードルリフト量を調整する機構についても存在していない。 Further, although the movable core (suction plate) 12 connected to the needle small diameter portion 41 of the needle 7 is attracted to the stator core 60 at the upper side, there is no particular mechanism for adjusting the compression spring force of the compression spring 10. it is obvious. There is also no mechanism for adjusting the needle lift amount of the needle 7.

本発明は、このような上記技術に存在する問題点に着目して成されたものであり、その目的は、必要吸引力を直動タイプの燃料噴射弁に比べて小さくでき、ソレノイドが小型に構成でき（低エネルギ）、バランスロッドの安定した位置決めを特別な部材を用いずに行うことが出来、噴射性能が安定する燃料噴射弁を得ることにある。 The present invention has been made by paying attention to such problems existing in the above-described technology, and its purpose is to reduce the required suction force compared to a direct-acting type fuel injection valve, and to reduce the size of the solenoid. It is possible to obtain a fuel injection valve that can be configured (low energy), can perform stable positioning of the balance rod without using a special member, and has stable injection performance.

従来技術として列挙された特許文献の記載内容は、この明細書に記載された技術的要素の説明として、参照によって導入ないし援用することができる。 Descriptions of patent documents listed as prior art can be introduced or incorporated by reference as explanations of technical elements described in this specification.

本発明は上記目的を達成するために、下記の技術的手段を採用する。すなわち、請求項１に記載の発明では、ソレノイドと、該ソレノイドを収容し保持するハウジングと、該ハウジングの内周面に形成された中空ホルダ部材とを備え、中空ホルダ部材内に形成された固定ヨーク部材と、該固定ヨーク部材内に形成された圧縮ばね位置決め部材と、固定ヨーク部材に開弁時のニードルリフトに必要な隙間を介して対向しソレノイドの電磁力にて隙間分だけ開弁方向に移動するコアとを備え、圧縮ばね位置決め部材によって位置が確定するバランスロッドのフランジ部と、該バランスロッドのフランジ部とコアの間に保持された圧縮ばねとを備え、バランスロッドのフランジ部から圧縮ばねの圧縮方向に伸び、フランジ部と反対側の端面において圧力室と対面したバランスロッドと、圧力室に連通する連通孔が形成されシート面に当接して閉弁作用をなしシート面から離間して開弁作用をなす先端部を有すると共に、バランスロッドを包み込みコアに連結されたニードルとを備え、ニードルの周囲に燃料室を形成し、シート面が形成されたボデーを先端部に有するホルダ本体と、ボデーに形成され、開弁時に燃料室と連通し連通孔を介して圧力室に連通する噴孔及びサック室とを備え、圧力室とバランスロッドとニードルとの間の隙間を介してホルダ本体の外部に連通する燃料リターン通路を備え、ニードルは、燃料室から供給された燃料圧によりニードルに開弁方向の力を付与する受圧部を備え、圧縮ばねによるコア及びニードルのシート面方向への押付け力と、開弁時の移動に伴う摺動抵抗力との合力以上の力を、開弁方向へのソレノイドの電磁力と共に受圧部がニードルに付与することを特徴としている。 In order to achieve the above object, the present invention employs the following technical means. In other words, the invention according to claim 1 includes a solenoid, a housing that accommodates and holds the solenoid, and a hollow holder member that is formed on the inner peripheral surface of the housing, and is formed in the hollow holder member. The yoke member, a compression spring positioning member formed in the fixed yoke member, and the fixed yoke member are opposed to each other via a gap necessary for needle lift at the time of valve opening, and the valve opening direction is the amount corresponding to the gap by the electromagnetic force of the solenoid. A balance rod flange portion whose position is fixed by a compression spring positioning member, and a compression spring held between the balance rod flange portion and the core, from the flange portion of the balance rod. A balance rod that extends in the compression direction of the compression spring and faces the pressure chamber on the end surface opposite to the flange, and a communication hole that communicates with the pressure chamber are formed And a valve having a tip portion that contacts the seat surface and closes the seat surface and opens the valve surface, and includes a needle that wraps a balance rod and is connected to the core, and has a fuel chamber around the needle. A holder body having a body with a seat surface formed at the tip, and a nozzle hole and a sac chamber formed in the body and communicating with the pressure chamber through the communication hole when the valve is opened and communicating with the fuel chamber A fuel return passage that communicates with the outside of the holder body through a gap between the pressure chamber, the balance rod, and the needle, and the needle imparts a force in the valve opening direction to the needle by the fuel pressure supplied from the fuel chamber. The electromagnetic force of the solenoid in the valve opening direction is greater than the combined force of the pressing force in the seat surface direction of the core and needle by the compression spring and the sliding resistance force accompanying movement at the time of valve opening. When The pressure receiving portion is characterized by imparting to the needle.

この発明によれば、ニードルが閉弁していようと、開弁していようと、ニードルの閉弁方向に作用する燃料圧と、ニードルの開弁方向に作用する燃料圧とを、常にバランスさせるのではなく、燃料圧によって開弁方向に力が作用するニードルの受圧部を有する。故に、必要吸引力を直動タイプの燃料噴射弁に比べて小さくでき、ソレノイドを小型に構成（低エネルギ化）できる。また、バランスロッドの安定した位置決めに、圧縮ばねの力を活用することにより、バランスロッドの安定した位置決めがなされるので、噴射空間圧力やエンジン振動等でバランスロッドが振動することが抑制でき、噴射弁の噴射性能が安定する。即ち、ニードル７及びバランスロッドの軸方向の動きが抑制でき、噴射時に、ニードルやバランスロッドの慣性質量が、エンジン振動等で変化することが少なく、噴射量が均一に成り易い。かつ、燃料圧によって、開弁方向に力が作用するニードルの受圧部を有することにより、圧縮ばねを比較的強くして、バランスロッドの安定性を更に強化したり閉弁時の応答性を改善したりするか、または、圧縮ばねの大きさを従来程度にしてソレノイドを更に小型化することが任意に出来る。
できる。 According to this invention, regardless of whether the needle is closed or opened, the fuel pressure acting in the needle closing direction and the fuel pressure acting in the needle opening direction are always balanced. Instead, it has a pressure receiving portion of the needle in which a force acts in the valve opening direction by the fuel pressure. Therefore, the required suction force can be made smaller than that of the direct-acting type fuel injection valve, and the solenoid can be made compact (low energy). Moreover, since the balance rod is stably positioned by utilizing the force of the compression spring for stable positioning of the balance rod, it is possible to suppress vibration of the balance rod due to injection space pressure, engine vibration, etc. The injection performance of the valve is stabilized. That is, the axial movement of the needle 7 and the balance rod can be suppressed, and the inertial mass of the needle and the balance rod is less likely to change due to engine vibration or the like during injection, and the injection amount tends to be uniform. In addition, by having a needle pressure-receiving part that exerts a force in the valve opening direction by the fuel pressure, the compression spring is made relatively strong, further enhancing the stability of the balance rod and improving the responsiveness when closing the valve. Or the size of the compression spring can be made as conventional, and the solenoid can be further miniaturized.
it can.

請求項２に記載の発明では、受圧部は、ニードルの噴孔側の先端に形成されたリング状の受圧段差からなることを特徴としている。 The invention according to claim 2 is characterized in that the pressure receiving portion is composed of a ring-shaped pressure receiving step formed at the tip of the needle on the nozzle hole side.

この発明によれば、リング状の受圧段差からなる受圧部によって、均一にニードルに燃料圧を作用させることが出来る。 According to the present invention, the fuel pressure can be uniformly applied to the needle by the pressure receiving portion including the ring-shaped pressure receiving step.

請求項３に記載の発明では、閉弁時にシート面に当接部にて当接するニードルの当接部間の径であるシート径ｄ１からニードルの外径が受圧部を経由して、拡大されたニードルの外径ｄ２を形成しており、バランスロッドは圧力室に対面する大径部を有し、該大径部の外径をｄ３としたとき、シート径ｄ１と、ニードルの外径ｄ２と、バランスロッド大径部の外径ｄ３との関係が、実質的にｄ２＞ｄ１＝ｄ３となることを特徴としている。 In the third aspect of the invention, the outer diameter of the needle is enlarged via the pressure receiving portion from the seat diameter d1, which is the diameter between the contact portions of the needle that contacts the seat surface at the contact portion when the valve is closed. The outer diameter d2 of the needle is formed, and the balance rod has a large diameter portion facing the pressure chamber. When the outer diameter of the large diameter portion is d3, the seat diameter d1 and the outer diameter d2 of the needle And the outer diameter d3 of the large-diameter portion of the balance rod is characterized by substantially satisfying d2> d1 = d3.

この発明によれば、シート径ｄ１とニードルの外径ｄ２との間に、受圧部を必要な大きさで形成することが出来る。 According to the present invention, the pressure receiving portion can be formed in a necessary size between the seat diameter d1 and the outer diameter d2 of the needle.

請求項４に記載の発明では、圧縮ばねによるコアとニードルとをシート面方向に付勢する圧縮ばねの力をＦｓｐｇとし、ニードルの先端部に印加される単位面積あたりの燃料圧力をＦｐｆとし、受圧部のリング状の面積が、（π／４）×{（ｄ２）^２−（ｄ１）^２}で表せるとき、圧縮ばねの力をＦｓｐｇと、受圧部によりニードルに加わる力との関係を、
Ｆｓｐｇ＞Ｆｐｆ×（π／４）{（ｄ２）^２―（ｄ１）^２）}
としたことを特徴としている。 In the invention according to claim 4, the force of the compression spring that urges the core and the needle by the compression spring in the seat surface direction is Fspg, the fuel pressure per unit area applied to the tip of the needle is Fpf, When the ring-shaped area of the pressure receiving portion can be expressed by (π / 4) × {(d2) ² − (d1) ² }, the relationship between the force of the compression spring Fspg and the force applied to the needle by the pressure receiving portion is
Fspg> Fpf × (π / 4) {(d2) ^2- (d1) ² )}
It is characterized by that.

この発明によれば、必要吸引力を直動タイプに比べて小さくでき、かつ、必要吸引力が小さいにも係らず、圧縮ばね力を強化することが出来て、燃料が燃料噴射弁内に充填され燃料圧が印加された場合に、ソレノイドによる吸引力が発生するまで、閉弁を安定して続ける燃料噴射弁を提供できる。 According to the present invention, the required suction force can be reduced as compared with the direct acting type, and the compression spring force can be strengthened even though the required suction force is small, and the fuel is filled in the fuel injection valve. When the fuel pressure is applied, it is possible to provide a fuel injection valve that keeps the valve closed stably until a suction force is generated by the solenoid.

請求項５に記載の発明では、ハウジングの内周面に形成された中空ホルダ部材に、固定ヨーク部材と、該固定ヨーク部材内に形成された圧縮ばね位置決め部材とを備え、固定ヨーク部材は、中空ホルダ部材に圧入またはねじ込みにより結合されたリフト調整部材から成り、圧入またはねじ込みの量が調整されることにより、開弁時のニードルリフトに必要な隙間が設定されることを特徴としている。 In the invention according to claim 5, the hollow holder member formed on the inner peripheral surface of the housing includes a fixed yoke member and a compression spring positioning member formed in the fixed yoke member, The lift adjustment member is joined to the hollow holder member by press-fitting or screwing, and a gap necessary for needle lift at the time of valve opening is set by adjusting the amount of press-fitting or screwing.

この発明によれば、ニードルリフトに必要な隙間を調整して、開弁時にニードルがソレノイド方向に移動するニードルリフト量を設定して燃料噴射特性の均一な燃料噴射弁にすることが出来る。 According to the present invention, it is possible to adjust the gap necessary for the needle lift and set the needle lift amount that the needle moves in the solenoid direction when the valve is opened, thereby obtaining a fuel injection valve having uniform fuel injection characteristics.

請求項６に記載の発明では、圧縮ばね位置決め部材は、圧縮ばね調整部材から成り、固定ヨーク部材内に、圧入またはねじ込みにより結合されており、圧入またはねじ込みの量が調整されることにより、圧縮ばねの圧縮量が設定されることを特徴としている。 In the invention according to claim 6, the compression spring positioning member is composed of a compression spring adjusting member, and is coupled to the fixed yoke member by press-fitting or screwing. By adjusting the amount of press-fitting or screwing, the compression spring positioning member is compressed. The amount of compression of the spring is set.

この発明によれば、圧縮ばねの圧縮力を調整することにより、圧縮ばねの力を調整して、所望の閉弁時応答性を得ることができ、燃料噴射特性の均一な燃料噴射弁にすることが出来る。 According to the present invention, by adjusting the compression force of the compression spring, the force of the compression spring can be adjusted to obtain a desired valve closing response, and the fuel injection valve has uniform fuel injection characteristics. I can do it.

請求項７に記載の発明では、ニードルが、噴孔を備えた先端部からコアに連結された根元部に至るまで同一材料で連続的に一体に形成されていることを特徴としている。 The invention according to claim 7 is characterized in that the needle is continuously and integrally formed of the same material from the tip portion provided with the injection hole to the root portion connected to the core.

この発明によれば、ニードルの構造が接合部の少ないシンプルな構造になり、ニードルの製作ないし組みつけが容易になる燃料噴射弁にすることが出来る。 According to this invention, the structure of the needle has a simple structure with few joints, and the fuel injection valve can be easily manufactured or assembled.

本発明の第１実施形態におけるガソリン直噴エンジン用の燃料噴射弁の縦断面図である。It is a longitudinal cross-sectional view of the fuel injection valve for gasoline direct injection engines in 1st Embodiment of this invention. 上記実施形態における燃料噴射弁の開弁開始時に、ニードルに作用する外力を比較して示すグラフである。It is a graph which compares and shows the external force which acts on a needle at the time of the valve opening start of the fuel injection valve in the said embodiment. 従来の特許文献２に記載の燃料噴射弁の縦断面図である。It is a longitudinal cross-sectional view of the fuel injection valve of the conventional patent document 2. 図３の燃料噴射弁におけるニードルの円錐状先端面周りの拡大図である。FIG. 4 is an enlarged view around a conical tip surface of a needle in the fuel injection valve of FIG. 3.

（第１実施形態）
以下、本発明の第１実施形態について図１および図２を用いて詳細に説明する。図１は、第１実施形態のガソリン直噴エンジン用の燃料噴射弁１の縦断面図である。図１において、図示しないコモンレールから２０ＭＰａ程度の燃料圧で燃料が燃料フィードパイプ２を介して供給されるものである。３は、上部にフランジ部３ａを有する円筒状のプラグであり、ステンレスで構成されている。４は、シールリングであり、ゴムで構成されている。 (First embodiment)
Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2. FIG. 1 is a longitudinal sectional view of a fuel injection valve 1 for a gasoline direct injection engine according to the first embodiment. In FIG. 1, fuel is supplied via a fuel feed pipe 2 at a fuel pressure of about 20 MPa from a common rail (not shown). Reference numeral 3 denotes a cylindrical plug having a flange portion 3a at the top, and is made of stainless steel. Reference numeral 4 denotes a seal ring, which is made of rubber.

５は、圧縮ばね位置決め部材を構成する中空円筒状の圧縮ばね調整部材であり、同じく円筒状のリフト調整部材（固定ヨーク部材ともいう）６内に圧入（またはねじ込み）されている。５ｃは、圧入部（またはねじ込み部）からなる進入量調整部である。この圧入量（進入量）は、後述するように、スプリングから成る圧縮ばね１０の圧縮ばね力の調整を行う作用を成す。 A hollow cylindrical compression spring adjusting member 5 constituting a compression spring positioning member is press-fitted (or screwed) into a cylindrical lift adjusting member (also called a fixed yoke member) 6. Reference numeral 5c denotes an entry amount adjusting unit including a press-fitting portion (or a screwed portion). As will be described later, this press-fitting amount (entry amount) serves to adjust the compression spring force of the compression spring 10 made of a spring.

８は、ハウジングであり、磁性材より成る電磁ステンレスから構成され、内部にソレノイド９が収納され、ソレノイド９が発生する磁束の磁路となるヨークを形成している。ハウジング８の内周には、リフト調整部材６を圧入（またはねじ込み）する圧入部（またはねじ込み部）からなる挿入量調整部６ｃが形成されている。 A housing 8 is made of electromagnetic stainless steel made of a magnetic material. A solenoid 9 is housed inside the housing, and a yoke serving as a magnetic path of magnetic flux generated by the solenoid 9 is formed. On the inner periphery of the housing 8, there is formed an insertion amount adjusting portion 6c comprising a press-fit portion (or screwed portion) into which the lift adjusting member 6 is press-fit (or screwed).

１０は、スプリングからなる圧縮ばねであり、バランスロッド１１のバランスロッドフランジ部１１ａの下端１１ａ１に圧縮ばね１０の一端が保持されている。圧縮ばね１０の他端は、電磁ステンレスからなるコア１２の窪みの底部１２ａに当接している。 Reference numeral 10 denotes a compression spring composed of a spring, and one end of the compression spring 10 is held by a lower end 11 a 1 of the balance rod flange portion 11 a of the balance rod 11. The other end of the compression spring 10 is in contact with the bottom 12a of the hollow of the core 12 made of electromagnetic stainless steel.

また、この圧縮ばね１０の強さは、調節可能であるが、噴孔２５ａ、２５ｂを介して、図示しないエンジンの気筒内の圧力変動が、サック室２６及び連通孔１８を介して圧力室１７に加わったときに、バランスロッド１１の下方向への移動を充分に抑制できる程度の強さに設定されている。 The strength of the compression spring 10 can be adjusted, but pressure fluctuations in the cylinder of the engine (not shown) can be caused by pressure holes 17a and 25b via the sac chamber 26 and the communication hole 18 through the injection holes 25a and 25b. Is set to a strength that can sufficiently suppress the downward movement of the balance rod 11.

コア（可動コア、アーマチャとも呼ばれる）１２は、ソレノイド９に通電されて電磁力が発生したときに、電磁ステンレスからなるリフト調整部材６に吸引される。 A core (also referred to as a movable core or an armature) 12 is attracted to a lift adjustment member 6 made of electromagnetic stainless steel when the solenoid 9 is energized to generate an electromagnetic force.

コア１２の上側端面１２ｂとリフト調整部材６の下端面６ａとの間には、数十ミクロンの微小な隙間Ｇ１が形成されており、この隙間Ｇ１が、ニードル７のニードルリフト量と成る。このニードルリフト量と成る隙間Ｇ１の調整は、ニードル７が閉弁位置にあるときに、コア１２とリフト調整部材６との相対位置を調整することで、可能となっている。このために、上記挿入量調整部６ｃにおいて、リフト調整部材６の中空ホルダ部材（コネクタホルダ部材ともいう）３３への圧入量が調整される。 A small gap G1 of several tens of microns is formed between the upper end face 12b of the core 12 and the lower end face 6a of the lift adjusting member 6, and this gap G1 becomes the needle lift amount of the needle 7. The adjustment of the gap G1 that is the needle lift amount is possible by adjusting the relative position between the core 12 and the lift adjustment member 6 when the needle 7 is in the valve closing position. For this reason, the amount of press-fitting of the lift adjusting member 6 into the hollow holder member (also referred to as a connector holder member) 33 is adjusted in the insertion amount adjusting portion 6c.

圧縮ばね１０の力によって、コア１２は図中下側に押圧され、コア１２と一体に連結されたニードル７も図中下側のボデー１５に形成されたシート面１６（図４と同じ）に押し付けられ、燃料噴射弁１が閉弁状態に成る。 The core 12 is pressed downward in the figure by the force of the compression spring 10, and the needle 7 integrally connected to the core 12 is also on the seat surface 16 (same as FIG. 4) formed on the lower body 15 in the figure. The fuel injection valve 1 is closed by being pressed.

コア１２の下端面１２ｃには、円筒状の突起１２ｄが形成され、この円筒状の突起１２ｄの内部に、中空円筒状のニードル７の根元部が挿入され、図中三角印で模式的に示された溶接部１３によってニードル７と突起１２ｄとが結合されている。尚、この結合は、溶接以外で行っても良い。 A cylindrical projection 12d is formed on the lower end surface 12c of the core 12, and the root portion of the hollow cylindrical needle 7 is inserted into the cylindrical projection 12d. The needle 7 and the protrusion 12d are coupled by the welded portion 13 thus formed. In addition, you may perform this coupling | bonding other than welding.

この溶接部１３の下には、ニードル７に設けられた貫通孔２８が形成されている。この貫通孔２８は、燃料リターンパイプ３１と共に、燃料リターン通路を形成している。ニードル７の下部には、圧力室１７が形成され、連通孔１８がニードル７の下部中央に穿設されている。 A through hole 28 provided in the needle 7 is formed below the welded portion 13. This through hole 28 forms a fuel return passage together with the fuel return pipe 31. A pressure chamber 17 is formed in the lower part of the needle 7, and a communication hole 18 is formed in the lower center of the needle 7.

そして、連通孔１８の周囲のニードル７の周面には受圧部１９（受圧段差１９ともいう）が形成され、ボデー１５のシート面１６にニードル７の先端が当接部２０、２１にて当接している。この様子は、従来の図４と同様である。 A pressure receiving portion 19 (also referred to as a pressure receiving step 19) is formed on the peripheral surface of the needle 7 around the communication hole 18, and the tip of the needle 7 is brought into contact with the seat surface 16 of the body 15 at the contact portions 20 and 21. It touches. This is the same as the conventional FIG.

図１中のｄ１は、当接部２０、２１間の直径であるシート径ｄ１を表している。この当接によって、燃料フィードパイプ２から供給された図示しないコモンレールからの燃料が遮断されており、燃料噴射弁１は閉弁状態である。 In FIG. 1, d 1 represents a sheet diameter d 1 that is a diameter between the contact portions 20 and 21. By this contact, fuel from a common rail (not shown) supplied from the fuel feed pipe 2 is shut off, and the fuel injection valve 1 is in a closed state.

そして、ニードル７が上方にリフトし、シート面１６からニードル７が離れると、ボデー１５に形成された噴孔２５ａ、２５ｂから燃料が噴射される。連通孔１８の先端には、ボデー１５との間にサック室２６が形成され、このサック室２６は、連通孔１８を介して圧力室１７と連通している。 When the needle 7 is lifted upward and the needle 7 is separated from the seat surface 16, fuel is injected from the injection holes 25 a and 25 b formed in the body 15. A sac chamber 26 is formed at the tip of the communication hole 18 with the body 15, and the sac chamber 26 communicates with the pressure chamber 17 through the communication hole 18.

ニードル７のバランスロッド受容孔７ａ内には、バランスロッド１１が、クリアランスを介して摺動可能に挿入されており、このバランスロッド１１の下端には、径が拡大した大径部１１ｂ（ピストン部）が存在する。この大径部１１ｂの上方には、バランスロッド１１の小径部１１ｃが大径部１１ｂと一体に連続して形成され、バランスロッド１１の小径部１１ｃは、上方でバランスロッドフランジ部１１ａに一体化されている。このバランスロッド１１は、冷間鍛造及び切削で形成されている。 A balance rod 11 is slidably inserted into the balance rod receiving hole 7a of the needle 7 via a clearance. A large diameter portion 11b (piston portion) having an enlarged diameter is provided at the lower end of the balance rod 11. ) Exists. Above the large diameter portion 11b, a small diameter portion 11c of the balance rod 11 is formed integrally and continuously with the large diameter portion 11b, and the small diameter portion 11c of the balance rod 11 is integrated with the balance rod flange portion 11a above. Has been. The balance rod 11 is formed by cold forging and cutting.

ニードル７の外径は、図１中、ｄ２で表されている。また、バランスロッド１１の大径部１１ｂの外径はｄ３（ニードル７の内周とバランスロッド１１間のクリアランスを無視すれば、実質的にニードル７の内径に等しい）で表されている。ホルダ本体３０やボデー１５は、通常のステンレスで形成され、ホルダ本体３０には、上述の燃料フィードパイプ２が挿入され、また、燃料リターンパイプ３１がホルダ本体３０に挿入されている。圧力室１７に蓄積された燃料は、ニードル７とバランスロッド１１の微小隙間を介して貫通孔２８から燃料リターンパイプ３１内に連通している。 The outer diameter of the needle 7 is represented by d2 in FIG. The outer diameter of the large diameter portion 11b of the balance rod 11 is represented by d3 (substantially equal to the inner diameter of the needle 7 if the clearance between the inner periphery of the needle 7 and the balance rod 11 is ignored). The holder main body 30 and the body 15 are made of ordinary stainless steel. The above-described fuel feed pipe 2 is inserted into the holder main body 30, and the fuel return pipe 31 is inserted into the holder main body 30. The fuel accumulated in the pressure chamber 17 communicates with the fuel return pipe 31 from the through hole 28 through a minute gap between the needle 7 and the balance rod 11.

また、コネクタホルダ３３の下端面３３ａと、ホルダ本体３０の円筒状上端面３０ａとの間に、リング状のホルダパイプ３４が形成されている。このホルダパイプ３４は、非磁性体のステンレスで構成され、ソレノイド９で発生した磁束が、リークせずに有効にコア１２とリフト調整部材６とに流れ、充分な電磁吸引力が発生するようにされている。 A ring-shaped holder pipe 34 is formed between the lower end surface 33 a of the connector holder 33 and the cylindrical upper end surface 30 a of the holder body 30. The holder pipe 34 is made of non-magnetic stainless steel so that the magnetic flux generated by the solenoid 9 can effectively flow into the core 12 and the lift adjusting member 6 without leaking, and a sufficient electromagnetic attractive force can be generated. Has been.

そして、上記シート径ｄ１と、バランスロッド１１の大径部１１ｂの外径ｄ３と、ニードル７の外径ｄ２の関係は、数式１の様になる。 The relationship between the seat diameter d1, the outer diameter d3 of the large diameter portion 11b of the balance rod 11, and the outer diameter d2 of the needle 7 is expressed by Equation 1.

（数式１）ｄ２＞ｄ１＝ｄ３
即ち、バランスロッド１１の大径部１１ｂの外径ｄ３と、シート径ｄ１が等しく、このシート径ｄ１もしくはバランスロッド１１の大径部１１ｂの外径ｄ３よりも、ニードル７の外径ｄ２が大きくされている。なお、ｄ１＝ｄ３の寸法は厳密に一致する必要は無く、１割程度の誤差は許容される。 (Formula 1) d2> d1 = d3
That is, the outer diameter d3 of the large diameter portion 11b of the balance rod 11 is equal to the seat diameter d1, and the outer diameter d2 of the needle 7 is larger than the seat diameter d1 or the outer diameter d3 of the large diameter portion 11b of the balance rod 11. Has been. Note that the dimensions of d1 = d3 do not need to be exactly the same, and an error of about 10% is allowed.

図１に示すように、シート径ｄ１と同じ直径でニードル７の先端側壁面が図１中、上方向に立ち上がり、受圧段差１９の幅だけニードル７の外径ｄ２が大きく構成されている。これによって、燃料フィードパイプ２を介してコモンレールから供給された燃料圧は、受圧段差１９に加わり、ニードル７及びコア１２を、燃料圧で上方に押し上げる働きを成す。 As shown in FIG. 1, the tip side wall surface of the needle 7 has the same diameter as the seat diameter d 1 and rises upward in FIG. 1, and the outer diameter d 2 of the needle 7 is increased by the width of the pressure receiving step 19. As a result, the fuel pressure supplied from the common rail via the fuel feed pipe 2 is applied to the pressure receiving step 19, and the needle 7 and the core 12 are pushed upward by the fuel pressure.

なお、受圧段差１９は、急に直角に曲がる段差でなくても良く、徐々に外径が拡大していく傾斜面やスロープ面であっても良く、要は、燃料圧でニードル７を図１中上方に持ち上げる受圧部１９を構成する形状であれば良い。 Note that the pressure receiving step 19 does not have to be a step that bends suddenly at a right angle, and may be an inclined surface or a slope surface whose outer diameter gradually expands. Any shape may be used as long as the pressure receiving portion 19 is lifted upward in the middle.

（閉弁時）
そして、図１の様に、ニードル７が閉弁し、ニードル７がシート面１６に着座しているときには、上述の様に、ニードル７の先端面周辺部の受圧段差１９に燃料圧が加わる。また、このとき、ニードル７の先端面中央部（サック室２６に対面する部分）と、圧力室１７には極めて小さな圧力ではあるが、連通路１８を介して同じ燃料圧が加わっている。 (When valve is closed)
As shown in FIG. 1, when the needle 7 is closed and the needle 7 is seated on the seat surface 16, the fuel pressure is applied to the pressure receiving step 19 around the distal end surface of the needle 7 as described above. At this time, the same fuel pressure is applied to the central portion of the tip surface of the needle 7 (the portion facing the sac chamber 26) and the pressure chamber 17 through the communication path 18 although the pressure is extremely small.

上述したように、シート面１６のシート径ｄ１と、ニードル７の外径ｄ２と、大径部１１ｂの外径ｄ３を比較したときに、ｄ２＞ｄ１＝ｄ３の関係であるため、ニードル７の先端面周辺部の受圧段差（受圧部）１９に加わる開弁方向の燃料圧が、圧縮ばね１０の閉弁方向の押し付け力に対向するようになる。 As described above, when the seat diameter d1 of the seat surface 16, the outer diameter d2 of the needle 7 and the outer diameter d3 of the large diameter portion 11b are compared, the relationship of d2> d1 = d3 is established. The fuel pressure in the valve-opening direction applied to the pressure-receiving step (pressure-receiving part) 19 around the tip end surface opposes the pressing force of the compression spring 10 in the valve-closing direction.

なお、シート径ｄ１と、バランスロッド１１の大径部１１ｂの外径ｄ３とが等しいので、サック室２６に対面するニードル７の先端面中央部に加わる開弁方向の燃料圧と、大径部１１ｂの下面に対向する圧力室１７に加わる閉弁方向の燃料圧（圧力室１７内の圧力）とが等しくなる。 Since the seat diameter d1 and the outer diameter d3 of the large diameter portion 11b of the balance rod 11 are equal, the fuel pressure in the valve opening direction applied to the central portion of the tip surface of the needle 7 facing the sack chamber 26, and the large diameter portion The fuel pressure in the valve closing direction (pressure in the pressure chamber 17) applied to the pressure chamber 17 facing the lower surface of 11b becomes equal.

（開弁時）
一方、ニードル７が上方にリフトして、開弁すると、燃料室３５内の高圧燃料が、サック室２６に導入され、更に、連通路１８を介して圧力室１７に導入される。この結果、燃料室３５内、サック室２６内およびバランスロッド受容孔７ａ内の圧力室１７の燃料圧は同じ燃料圧となる。 (When valve is opened)
On the other hand, when the needle 7 lifts upward and opens, the high-pressure fuel in the fuel chamber 35 is introduced into the sac chamber 26 and further introduced into the pressure chamber 17 via the communication path 18. As a result, the fuel pressures in the pressure chambers 17 in the fuel chamber 35, the sac chamber 26, and the balance rod receiving hole 7a become the same fuel pressure.

よって、このとき、シート径ｄ１と同じ直径を持つニードル７の円錐状先端面に加わる開弁方向の燃料圧と、バランスロッド受容孔７ａ内の圧力室１７に加わる閉弁方向の燃料圧とが等しくなる。その結果、受圧段差（受圧部）１９に加わり、ニードル７及びコア１２を、燃料圧で上方に押し上げる力のみが、圧縮ばね１０の押し下げ力に対向して、開弁方向に働き、ソレノイド９の電磁吸引力を補助（アシスト）する。 Therefore, at this time, the fuel pressure in the valve opening direction applied to the conical tip surface of the needle 7 having the same diameter as the seat diameter d1 and the fuel pressure in the valve closing direction applied to the pressure chamber 17 in the balance rod receiving hole 7a are obtained. Will be equal. As a result, the pressure receiving step (pressure receiving portion) 19 is added, and only the force that pushes up the needle 7 and the core 12 upward with the fuel pressure acts in the valve opening direction opposite to the pressing force of the compression spring 10. Assist the electromagnetic attractive force.

上記第１実施形態の燃料噴射弁１と、特許文献２に係る燃料噴射弁との相違点は、次の点である。先ず、上記第１実施形態の燃料噴射弁１では、燃料圧を完全に相殺（キャンセル）せず、受圧段差（受圧部）１９の働きで、燃料圧を若干開弁方向へ働かせる構造を採用している。また、バランスロッド１１周りのニードル７を、特別な複数の部品を追加せずに形成している。 The difference between the fuel injection valve 1 of the first embodiment and the fuel injection valve according to Patent Document 2 is as follows. First, the fuel injection valve 1 of the first embodiment employs a structure in which the fuel pressure is slightly canceled in the valve opening direction by the action of the pressure receiving step (pressure receiving portion) 19 without completely canceling (cancelling) the fuel pressure. ing. Further, the needle 7 around the balance rod 11 is formed without adding a plurality of special parts.

即ち、図１のニードル７は、コア１２に結合されている中空円筒形の同一金属材料が連続して成る一体成型品であり、複数部品を結合したものではない。また、圧力室１７からコア１２まで同一内径ｄ３のバランスロッド受容孔７ａを有している。 That is, the needle 7 in FIG. 1 is an integrally molded product formed by continuously forming the same metal material in the form of a hollow cylinder coupled to the core 12, and is not a combination of a plurality of components. Further, a balance rod receiving hole 7 a having the same inner diameter d 3 is provided from the pressure chamber 17 to the core 12.

また、リフト調整部材６内に、圧縮ばね調整部材５を圧入する圧入量を調整することで、バランスロッドフランジ部１１ａを圧力室１７側に押し下げる量、即ち、圧縮ばね１０の圧縮ばね力の調整を可能としている。また、閉弁したときの、コア１２の上側端面１２ｂとリフト調整部材６の下端面６ａとの相対位置を調整することで、微小な隙間Ｇ１からなるニードルリフト量の調整を可能としている。 Further, by adjusting the amount of press-fitting of the compression spring adjustment member 5 into the lift adjustment member 6, the amount of pressing the balance rod flange portion 11 a toward the pressure chamber 17 side, that is, adjustment of the compression spring force of the compression spring 10 is adjusted. Is possible. Further, by adjusting the relative position between the upper end surface 12b of the core 12 and the lower end surface 6a of the lift adjusting member 6 when the valve is closed, the needle lift amount including the minute gap G1 can be adjusted.

次に、受圧段差１９の働きにより、燃圧力がニードル７を押し上げるように働くので、この燃圧力が、ソレノイド９の電磁吸引力の方向と一致し、圧縮ばね１０及び摺動抵抗力に抗してニードル７を上方に押し上げる。 Next, since the fuel pressure works to push up the needle 7 by the action of the pressure receiving step 19, this fuel pressure coincides with the direction of the electromagnetic attracting force of the solenoid 9, and resists the compression spring 10 and the sliding resistance force. To push the needle 7 upward.

即ち，ソレノイド９による必要吸引力は、この必要吸引力と、受圧段差１９に加わる燃圧力の合計が圧縮ばね１０の力と摺動抵抗力の合力以上になれば、ニードル７が上方にリフトされることになる。そして、電磁吸引力がなくなると、圧縮ばね１０の力により、ニードル７がボデー１５のシート面１６に押付けられて閉弁する。 That is, the necessary suction force by the solenoid 9 is lifted upward if the sum of the necessary suction force and the fuel pressure applied to the pressure receiving step 19 is equal to or greater than the resultant force of the compression spring 10 and the sliding resistance force. Will be. When the electromagnetic attractive force disappears, the needle 7 is pressed against the seat surface 16 of the body 15 by the force of the compression spring 10 to close the valve.

また、圧縮ばね１０の圧縮ばね力をＦｓｐｇとし、燃料フィードパイプ２からニードル７の周囲に供給される単位面積当たりの燃圧力をＦｐｆとし、上述のシート径ｄ１、シート径ｄ１から受圧段差１９を介して更に外径が大きくなったニードル７の外径をｄ２とした場合に、受圧段差１９のリング状の面積は、
（π／４）×（ｄ２）^２−（π／４）×（ｄ１）^２、即ち、
（π／４）×{（ｄ２）^２−（ｄ１）^２} で表される。 Further, the compression spring force of the compression spring 10 is Fspg, the fuel pressure per unit area supplied from the fuel feed pipe 2 to the periphery of the needle 7 is Fpf, and the pressure receiving step 19 is determined from the above-described seat diameter d1 and seat diameter d1. When the outer diameter of the needle 7 whose outer diameter is further increased through d2 is d2, the ring-shaped area of the pressure receiving step 19 is
(Π / 4) × (d2) ² − (π / 4) × (d1) ² , that is,
(Π / 4) × {(d2) ² − (d1) ² }

この受圧段差１９のリング状の面積に、単位面積当たりの燃圧力Ｆｐｆが印加されると、ニードル７を開弁方向に押し上げる力が発生する。よって、燃圧力が印加されたときに自然に燃料噴射弁１が開弁してしまわないようにするために、圧縮ばね力Ｆｓｐｇと、上記押し上げる力との関係を、数式２の様にする必要がある。 When the fuel pressure Fpf per unit area is applied to the ring-shaped area of the pressure receiving step 19, a force for pushing up the needle 7 in the valve opening direction is generated. Therefore, in order to prevent the fuel injection valve 1 from opening naturally when the fuel pressure is applied, the relationship between the compression spring force Fspg and the pushing-up force needs to be expressed by Equation 2. There is.

（数式２）Ｆｓｐｇ＞Ｆｐｆ×（π／４）{（ｄ２）^２―（ｄ１）^２）}
これによって、燃料が供給され、受圧段差１９に燃料圧が作用して、ニードル７を押し上げるように作用する力Ｆｐｆ×（π／４）{（ｄ２）^２―（ｄ１）^２）}が受圧段差１９に働いても、圧縮ばね１０の圧縮ばね力Ｆｓｐｇの方が大きいため、ニードル７はボデー１５のシート面１６に押付けられ、安定して閉弁状態にある。 (Formula 2) Fspg> Fpf × (π / 4) {(d2) ² − (d1) ² )}
As a result, fuel is supplied and the pressure Fp × (π / 4) {(d2) ² − (d1) ² )} acting so as to push up the needle 7 when the fuel pressure acts on the pressure receiving step 19 is the pressure receiving step. 19, the compression spring force Fspg of the compression spring 10 is larger, so that the needle 7 is pressed against the seat surface 16 of the body 15 and is stably closed.

そして、ソレノイド９の電磁吸引力が、受圧段差１９に加わっている燃料圧と同じ方向、即ち、上方に作用すると、電磁吸引力と受圧段差１９の燃圧力とが、上記圧縮ばね力と摺動抵抗力に打ち勝って、リフト調整部材６の下端面６ａとコア１２の上側端面１２ｂに形成された隙間（ニードルリフト量）Ｇ１分だけ、コア１２並びにニードル７が上方にリフトされ、ニードル７周囲の燃料がサックス室２６と連通すると共に、噴孔２５ａ、２５ｂから燃料がエンジン内に噴射される。 When the electromagnetic attraction force of the solenoid 9 acts in the same direction as the fuel pressure applied to the pressure receiving step 19, that is, upward, the electromagnetic attraction force and the fuel pressure at the pressure receiving step 19 slide with the compression spring force. Overcoming the resistance force, the core 12 and the needle 7 are lifted upward by a gap (needle lift amount) G1 formed between the lower end surface 6a of the lift adjusting member 6 and the upper end surface 12b of the core 12, and the periphery of the needle 7 The fuel communicates with the saxophone chamber 26, and the fuel is injected into the engine from the injection holes 25a and 25b.

図２は、開弁開始時に、ニードル７に作用する外力を比較して示すグラフである。図２において、上方に、開弁するための電磁吸引力（必要吸引力）等の開弁力をとり、下方に圧縮ばね等による閉弁力を示している。 FIG. 2 is a graph showing a comparison of external forces acting on the needle 7 at the start of valve opening. In FIG. 2, the valve opening force such as an electromagnetic attraction force (necessary attraction force) for opening the valve is taken upward, and the valve closing force by a compression spring or the like is shown below.

ここで、比較例として示す直動タイプの特許文献１の燃料噴射弁では、図２の（ｄ）に示すように、開弁開始時にソレノイドに必要とされる必要吸引力Ｆｓｄは、ニードル７をシート面１６に押付けようとする燃圧力Ｆｐｆｄ、圧縮ばね力Ｆｓｐｇｄ、及び摺動抵抗力Ｆｒｄに打ち勝つだけの必要吸引力Ｆｓｄが作用して、初めて、ニードル７が上方に移動する。 Here, in the fuel injection valve of Patent Document 1 of the direct acting type shown as a comparative example, as shown in FIG. The needle 7 moves upward only after the necessary suction force Fsd that overcomes the fuel pressure Fpfd, the compression spring force Fspgd, and the sliding resistance force Frd to be pressed against the seat surface 16 acts.

また、特許文献２に示された燃料噴射弁では、コモンレールから供給された燃圧力が、ニードル７に相殺されて作用するため、燃料圧はキャンセル状態にあり、図２の（ｃ）に示すように、圧縮ばね力Ｆｓｐｇｃと摺動抵抗力Ｆｒｃの合計に打ち勝つだけのソレノイド９の電磁吸引力、即ち、必要吸引力Ｆｓｃがあれば、開弁を開始することが出来る。即ち、特許文献２では、特許文献１に比べて、ソレノイド９の必要吸引力Ｆｓｃを小さくすることが出来るが、上述した問題点を有する。 Further, in the fuel injection valve disclosed in Patent Document 2, the fuel pressure supplied from the common rail acts against the needle 7 so that the fuel pressure is in a canceled state, as shown in FIG. In addition, if there is an electromagnetic attractive force of the solenoid 9 that can overcome the total of the compression spring force Fspgc and the sliding resistance force Frc, that is, the required attractive force Fsc, the valve opening can be started. That is, in Patent Document 2, the required suction force Fsc of the solenoid 9 can be reduced as compared with Patent Document 1, but has the above-described problems.

ここで、上記第１実施形態の燃料噴射弁１の開弁開始時に、ニードル７に働く外力の関係は、図２の（ａ）または（ｂ）の様になる。先ず、図２の（ｂ）について説明する。ニードル７をシート面１６に押付けて閉弁させようとする圧縮ばね力Ｆｓｐｇｂと摺動抵抗力Ｆｒとに打ち勝つだけの、受圧段差１９に加わる燃圧力Ｆｐｆとソレノイド９の必要吸引力Ｆｓｂがあれば、ニードル７を開弁方向に動かすことが出来る。即ち、この第１実施形態では、ソレノイド９の電磁吸引力Ｆｓｂをアシストするように受圧段差１９の燃圧力Ｆｐｆが作用する。 Here, when the fuel injection valve 1 of the first embodiment starts to open, the relationship of the external force acting on the needle 7 is as shown in FIG. 2 (a) or (b). First, (b) of FIG. 2 will be described. If there is a fuel pressure Fpf applied to the pressure receiving step 19 and a necessary suction force Fsb of the solenoid 9 that can overcome the compression spring force Fspgb and the sliding resistance force Fr that press the needle 7 against the seat surface 16 to close the valve. The needle 7 can be moved in the valve opening direction. That is, in the first embodiment, the fuel pressure Fpf of the pressure receiving step 19 acts so as to assist the electromagnetic attractive force Fsb of the solenoid 9.

これによって、必要吸引力Ｆｓｂを、図２の（ｃ）の特許文献２の必要吸引力Ｆｓｃと同じとした場合は、圧縮ばねＦｓｐｇｂを圧縮ばね力Ｆｓｐｇｃより強くすることが出来、圧縮ばね力Ｆｓｐｇｂを強くすることにより、閉弁応答特性が改善出来る。また、図１のニードル７の位置及びニードル７内部に収納されたバランスロッド１１の位置が安定することになるため、燃料噴射特性がエンジン振動等でばらつくことがない。 Thus, when the required suction force Fsb is the same as the required suction force Fsc of Patent Document 2 in FIG. 2C, the compression spring Fspgb can be made stronger than the compression spring force Fspgc, and the compression spring force Fspgb The valve closing response characteristic can be improved by strengthening. Further, since the position of the needle 7 in FIG. 1 and the position of the balance rod 11 housed in the needle 7 are stabilized, the fuel injection characteristic does not vary due to engine vibration or the like.

換言すれば、圧縮ばね力が強いほど、ニードル７をシート面１６側に押付ける力が強く、良好な閉弁応答性が得られ、かつバランスロッド１１の圧力室１７側への移動阻止力の余裕度を向上させることができる。 In other words, the stronger the compression spring force, the stronger the force that presses the needle 7 against the seat surface 16 side, the better valve closing response is obtained, and the movement blocking force of the balance rod 11 toward the pressure chamber 17 side is increased. The margin can be improved.

また、図２の（ｃ）の特許文献２のものと同程度の圧縮ばね力Ｆｓｐｇａを付与するだけでよければ、究極、図２の（ａ）に示すように、必要吸引力Ｆｓａを更に小さい最小限の必要吸引力とすることも出来る。なお、図２の（ａ）、（ｂ）のＦｒは、上記第１実施形態の燃料噴射弁１の開弁開始時に作用する摺動抵抗力である。 Further, if it is only necessary to apply a compression spring force Fspga of the same level as that of Patent Document 2 in FIG. 2C, the required suction force Fsa is further reduced as shown in FIG. The minimum required suction force can also be achieved. Note that Fr in FIGS. 2A and 2B is a sliding resistance acting when the fuel injection valve 1 of the first embodiment starts to open.

更に、図１のシート径ｄ１と、バランスロッド１１の大径部１１ｂの外径ｄ３と、ニードル７の外径ｄ２の関係は、上記数式１の（ｄ２＞ｄ１＝ｄ３）の様にしている。この構成にすることで、ニードル７の内径を、バランスロッド１１の大径部１１ｂの外径ｄ３とほぼ（実質的に）等しい、圧力室１７からコア１２まで均一な肉厚とすることができ、それにより、ニードル７を複数部品に分割することなく、組付けすることが可能となる。 Furthermore, the relationship between the seat diameter d1 of FIG. 1, the outer diameter d3 of the large diameter portion 11b of the balance rod 11, and the outer diameter d2 of the needle 7 is as shown in the above equation 1 (d2> d1 = d3). . With this configuration, the inner diameter of the needle 7 can be made to have a uniform thickness from the pressure chamber 17 to the core 12 that is substantially (substantially) equal to the outer diameter d3 of the large diameter portion 11b of the balance rod 11. Thereby, the needle 7 can be assembled without being divided into a plurality of parts.

従って、ニードル７の部品点数を減らし、かつ、ニードル７の組付性を改善することが出来る（図１の上方よりの一方向組付けが可能になる）。また、バランスロッド１１をバランスロッドフランジ部１１ａを有する形状にして圧縮ばね１０の上端を押さえ込む特異な構成にして、バランスロッド１１の位置決めを行っている。 Therefore, the number of parts of the needle 7 can be reduced and the assemblability of the needle 7 can be improved (one-way assembly from above in FIG. 1 is possible). In addition, the balance rod 11 is positioned by making the balance rod 11 into a shape having a balance rod flange portion 11 a and pressing the upper end of the compression spring 10.

つまり、通常、この種の燃料噴射弁に使用されている圧縮ばね１０を、バランスロッド１１の位置決めに活用できることに着眼し、バランスロッド１１を特別な部品の追加なしで安定して位置決めしている。また、圧縮ばね１０の力が強いほど、バランスロッド１１が、図１の下方に下がりにくく、上記安定した位置決めが行われるが、図２の（ｂ）で説明したように、図２の（ｃ）に比べて、同じソレノイド１０の必要吸引力であれば、燃圧力Ｆｐｆが開弁方向にアシスト（助勢）されることにより、より強い圧縮ばね力の採用が可能となっている。 That is, the compression spring 10 normally used in this type of fuel injection valve can be utilized for positioning of the balance rod 11, and the balance rod 11 is stably positioned without adding special parts. . Further, as the force of the compression spring 10 is stronger, the balance rod 11 is less likely to be lowered downward in FIG. 1 and the above-described stable positioning is performed. As described with reference to FIG. ), The fuel pressure Fpf is assisted (assisted) in the valve opening direction so that a stronger compression spring force can be used.

また、上述したように、図１のリフト調整部材６内に圧縮ばね調整部材５を圧入する圧入量を調整することで、圧縮ばね１０の圧縮ばね力の調整を可能としている。また、閉弁したときのコア１２とリフト調整部材６との相対位置を調整することで、ニードルリフト量Ｇ１の調整を可能としている。 Further, as described above, the compression spring force of the compression spring 10 can be adjusted by adjusting the amount of press-fitting of the compression spring adjustment member 5 into the lift adjustment member 6 of FIG. Further, the needle lift amount G1 can be adjusted by adjusting the relative position between the core 12 and the lift adjusting member 6 when the valve is closed.

（その他の実施形態）
本発明は上述した実施形態にのみ限定されるものではなく、次のように変形または拡張することができる。例えば、上述の第１実施形態では、ガソリン直噴エンジン用の燃料噴射弁に本発明を適用したが、ディーゼルエンジン用の燃料噴射弁に適用することも出来る。 (Other embodiments)
The present invention is not limited to the above-described embodiments, and can be modified or expanded as follows. For example, in the first embodiment described above, the present invention is applied to a fuel injection valve for a gasoline direct injection engine. However, the present invention can also be applied to a fuel injection valve for a diesel engine.

また、図１の圧縮ばね調整部材５は、パイプのような中空部材でなくても良い。更に、コネクタホルダ３３は、図示しないソレノイド通電用のコネクタを保持するが、これを単なる円筒形等の中空ホルダ部材とし、コネクタはハウジング８側に設けても良い。 Further, the compression spring adjusting member 5 in FIG. 1 may not be a hollow member such as a pipe. Further, the connector holder 33 holds a solenoid energizing connector (not shown), but this may be a simple cylindrical holder member, and the connector may be provided on the housing 8 side.

また、圧縮ばね１０（図１）は、単純なコイル状のスプリング以外の種々のばね形状を採用することが出来る。また、図１のリング状のホルダパイプ３４は省略して空間部分にしたり、樹脂等の非磁性体を充填したりすることが出来る。 The compression spring 10 (FIG. 1) can employ various spring shapes other than a simple coil spring. Further, the ring-shaped holder pipe 34 shown in FIG. 1 can be omitted to form a space portion or filled with a non-magnetic material such as resin.

また、図１の固定ヨーク部材６をなすリフト調整部材６は、底部を有する逆Ｕ字状の形状であってもよい。そして、この底部に非パイプ材からなる棒状の圧縮ばね調整部材５を打ち込んで、圧縮ばねの変形量（圧縮量）を調整しても良い。 Further, the lift adjusting member 6 forming the fixed yoke member 6 of FIG. 1 may have an inverted U-shape having a bottom. Then, a rod-shaped compression spring adjusting member 5 made of a non-pipe material may be driven into this bottom portion to adjust the deformation amount (compression amount) of the compression spring.

１燃料噴射弁
２燃料フィードパイプ
３プラグ
４シールリング
５圧縮ばね調整部材（圧縮ばね位置決め部材）
６リフト調整部材（固定ヨーク部材）
７ニードル
７ａバランスロッド受容孔
８ハウジング
９ソレノイド
１０スイッチプリン部（圧縮ばね）
１１バランスロッド
１１ａバランスロッドフランジ部
１１ｂ大径部
１１ｃ小径部
１２コア
１５ボデー
１６シート面
１７圧力室
１８連通孔
１９受圧段差（受圧部）
２０、２１当接部
２６サック室
２５ａ、２５ｂ噴孔
２８貫通孔
３０ホルダ本体
３１燃料リターンパイプ
３３コネクタホルダ（中空ホルダ部材）
３４ホルダパイプ
３５燃料室
ｄ１当接部間の径であるシート径
ｄ２ニードルの外径
ｄ３大径部の外径
Ｇ１ニードルリフト量と成る隙間
Ｆｓｐｇａ、Ｆｓｐｇｂ圧縮ばね力
Ｆｐｆ単位面積当たりの燃圧力
Ｆｒ摺動抵抗力
Ｆｓａ、Ｆｓｂソレノイドの必要吸引力 DESCRIPTION OF SYMBOLS 1 Fuel injection valve 2 Fuel feed pipe 3 Plug 4 Seal ring 5 Compression spring adjustment member (compression spring positioning member)
6 Lift adjustment member (fixed yoke member)
7 Needle 7a Balance rod receiving hole 8 Housing 9 Solenoid 10 Switch pudding part (compression spring)
11 Balance rod 11a Balance rod flange portion 11b Large diameter portion 11c Small diameter portion 12 Core 15 Body 16 Seat surface 17 Pressure chamber 18 Communication hole 19 Pressure receiving step (pressure receiving portion)
20, 21 Contact portion 26 Suck chamber 25a, 25b Injection hole 28 Through hole 30 Holder body 31 Fuel return pipe 33 Connector holder (hollow holder member)
34 Holder pipe 35 Fuel chamber d1 Seat diameter which is the diameter between the contact parts d2 Needle outer diameter d3 Large diameter outer diameter G1 Needle lift amount gap Fspga, Fspgb Compression spring force Fpf Fuel pressure per unit area Fr Sliding resistance force Fsa, Fsb Solenoid required suction force

Claims

A solenoid, a housing that accommodates and holds the solenoid, and a hollow holder member formed on the inner peripheral surface of the housing;
The fixed yoke member formed in the hollow holder member, the compression spring positioning member formed in the fixed yoke member, and the fixed yoke member opposed to each other through a gap necessary for needle lift when the valve is opened. A core that moves in the valve opening direction by the gap by the electromagnetic force of the solenoid,
A flange portion of a balance rod whose position is determined by the compression spring positioning member, and a compression spring held between the flange portion of the balance rod and the core,
A balance rod extending from the flange portion of the balance rod in the compression direction of the compression spring and facing the pressure chamber on the end surface opposite to the flange portion, and a communication hole communicating with the pressure chamber are formed to contact the seat surface. Having a tip portion that performs a valve closing action and is spaced apart from the seat surface to perform a valve opening action, and includes a needle that encloses the balance rod and is connected to the core,
A fuel body is formed around the needle, and a holder main body having a body with a seat surface formed at a tip thereof is formed on the body, and communicates with the fuel chamber when the valve is opened via the communication hole. A nozzle hole and a sac chamber communicating with the pressure chamber;
A fuel return passage communicating with the outside of the holder body through a gap between the pressure chamber, the balance rod, and the needle;
The needle includes a pressure receiving portion that applies a force in a valve opening direction to the needle by a fuel pressure supplied from the fuel chamber,
The electromagnetic force of the solenoid in the valve opening direction is equal to or greater than the resultant force of the pressing force of the core and the needle in the seat surface direction by the compression spring and the sliding resistance force accompanying the movement at the time of valve opening. The fuel injection valve, wherein the pressure receiving portion is applied to the needle together with force.

2. The fuel injection valve according to claim 1, wherein the pressure receiving portion includes a ring-shaped pressure receiving step formed at a tip of the needle on the nozzle hole side.

When the valve is closed, the outer diameter of the needle is increased from the seat diameter d1, which is the diameter between the contact portions of the needle that contacts the seat surface at the contact portion, via the pressure receiving portion. The balance rod has a large-diameter portion facing the pressure chamber, and when the outer diameter of the large-diameter portion is d3, the seat diameter d1 and the outer diameter d2 of the needle And the outer diameter d3 of the large diameter portion of the balance rod substantially satisfies d2> d1 = d3.

The force of the compression spring that urges the core and the needle in the seat surface direction by the compression spring is Fspg,
When the fuel pressure per unit area applied to the tip of the needle is Fpf, and the ring-shaped area of the pressure receiving portion can be expressed by (π / 4) × {(d2) ² − (d1) ² }, The relationship between the force of the compression spring, Fspg, and the force applied to the needle by the pressure receiving portion,
Fspg> Fpf × (π / 4) {(d2) ^2- (d1) ² )}
The fuel injection valve according to claim 3, wherein

A hollow holder member formed on an inner peripheral surface of the housing includes the fixed yoke member and a compression spring positioning member formed in the fixed yoke member, and the fixed yoke member is press-fitted into the hollow holder member. Or a lift adjusting member coupled by screwing, wherein the clearance necessary for needle lift when the valve is opened is set by adjusting the amount of press-fitting or screwing. The fuel injection valve according to any one of 4.

The compression spring positioning member is composed of a compression spring adjustment member, and is coupled to the fixed yoke member by press-fitting or screwing, and the amount of compression of the compression spring is adjusted by adjusting the amount of press-fitting or screwing. The fuel injection valve according to any one of claims 1 to 5, wherein the fuel injection valve is set.

The said needle is integrally formed continuously from the same material from the front-end | tip part provided with the nozzle hole to the root part connected with the said core, It is any one of Claim 1 thru | or 6 characterized by the above-mentioned. The fuel injection valve described in 1.