JP4198555B2

JP4198555B2 - Seal structure

Info

Publication number: JP4198555B2
Application number: JP2003272641A
Authority: JP
Inventors: 義人岡部
Original assignee: KYB Corp
Current assignee: KYB Corp
Priority date: 2003-07-10
Filing date: 2003-07-10
Publication date: 2008-12-17
Anticipated expiration: 2023-07-10
Also published as: JP2005030535A

Description

この発明は、たとえば、ダンパを内蔵するフロントフォーク内に収装のフリーピストンとこのフリーピストンの外周が内周に摺接する筒状部材との間に具現化されるシール部構造の改良に関する。 The present invention relates to, for example, an improvement in a seal portion structure embodied between a free piston accommodated in a front fork incorporating a damper and a cylindrical member whose outer periphery is in sliding contact with the inner periphery.

二輪車の前輪側に架装されて二輪車の前輪への入力を内蔵のダンパで吸収するフロントフォークにあって、内部にフリーピストンを収装することで、ダンパにおける内圧を保障して、フロントフォークの圧縮作動時にダンパによる所定の大きさの反力発生を可能にするとした提案がある（たとえば、特許文献１参照）。 It is a front fork that is mounted on the front wheel side of a motorcycle and absorbs the input to the front wheel of the motorcycle with a built-in damper, and by installing a free piston inside it, the internal pressure in the damper is guaranteed, and the front fork There is a proposal that enables a predetermined reaction force to be generated by a damper during a compression operation (see, for example, Patent Document 1).

それゆえ、この提案によれば、フロントフォークの圧縮作動時にダンパによる所定の反力発生が可能になるから、二輪車における乗り心地を良好に保つことが可能になると言い得るが、その反面、何らかの理由でダンパ内に溜まるいわゆる余剰の油がフロントフォーク内のいわゆるリザーバに流出することを上記のフリーピストンが妨げることが危惧される。 Therefore, according to this proposal, since it is possible to generate a predetermined reaction force by the damper during the compression operation of the front fork, it can be said that it is possible to maintain a good riding comfort in the two-wheeled vehicle, but for some reason, Therefore, there is a concern that the above-mentioned free piston prevents the so-called surplus oil accumulated in the damper from flowing out into a so-called reservoir in the front fork.

そこで、上記の提案では、ダンパ内に余剰の油が溜まる場合には、上記のフリーピストンが後退していわゆる隙間を出現させてこの余剰の油をリザーバに流出させるとしており、これによって、ダンパによる反力が必要以上に大きくならないようにしている。
特開平６‐１４７２４８号公報（特許請求の範囲請求項１，段落０００４，図１） Therefore, in the above proposal, when surplus oil accumulates in the damper, the above-described free piston moves backward to make a so-called gap appear, and this surplus oil flows out to the reservoir. The reaction force is not increased more than necessary.
JP-A-6-147248 (Claims Claim 1, Paragraph 0004, FIG. 1)

しかしながら、上記の提案では、ダンパ内に溜まる余剰の油をリザーバに流出させるについて、フリーピストンが所定のストロークを移動したときに、フリーピストンの内周とこのフリーピストンの内周が対向するロッド体の外周との間に出現する環状隙間、すなわち、ロッド体の縮径部の外周との間に出現する環状隙間を利用するとしているから、言わば瞬時に多量の油を流出させることが困難になり易く、それゆえ、フリーピストンの移動状況によっては、余剰の油を完全に流出させ得ない状態のままフリーピストンが反転して、余剰の油がダンパに閉じ込められることになる危惧がある。 However, in the above proposal, the rod body in which the inner periphery of the free piston and the inner periphery of the free piston face each other when the free piston moves through a predetermined stroke for causing excess oil accumulated in the damper to flow into the reservoir. An annular gap that appears between the outer circumference of the rod body, i.e., an annular gap that appears between the outer circumference of the reduced diameter portion of the rod body, is used. Therefore, depending on the movement state of the free piston, there is a concern that the free piston may reverse while the excess oil cannot be completely discharged, and the excess oil may be trapped in the damper.

そこで、本願の出願人が先に特願２００３−０７９６７９で提案したところであるが、フリーピストンの外周とこのフリーピストンの外周が対向する筒状部材の内周との間に出現する環状隙間、すなわち、筒状部材の膨径された内周との間に出現する環状隙間を利用してダンパ内の余剰の油を流出させる構成の方が流路面積を大きく確保し得ることから好ましいと言い得る。 Therefore, the applicant of the present application previously proposed in Japanese Patent Application No. 2003-079679, but an annular gap that appears between the outer periphery of the free piston and the inner periphery of the cylindrical member facing the outer periphery of the free piston, that is, In addition, it can be said that a configuration in which excess oil in the damper is allowed to flow out by utilizing an annular gap that appears between the expanded inner circumference of the cylindrical member is preferable because a larger flow path area can be secured. .

しかし、このとき、フリーピストンの外周に形成の環状凹溝内に収装されているシール部材は、その内周を環状凹溝の底に密着させるための絞め代を保障する上で弾性に富む材料で形成されているから、ダンパ内の余剰の油がフリーピストンの外周と筒状部材の内周との間に出現する環状隙間を通過しようとするとき、この余剰の油に起因する圧力がシール部材における内側に作用することもあって、シール部材における外周側が膨径するようにシール部材が押し潰されてシール部材における外周を筒状部材の内周に密着させる状態になり、それゆえ、シール部材の外周と筒状部材の内周との間を上記の油が通過し得ない状況が現出されることになる。 However, at this time, the seal member housed in the annular groove formed on the outer periphery of the free piston is rich in elasticity to ensure a tightening allowance for closely contacting the inner periphery with the bottom of the annular groove. Because it is made of material, when excess oil in the damper tries to pass through the annular gap that appears between the outer periphery of the free piston and the inner periphery of the cylindrical member, the pressure caused by this excess oil is Since it may act on the inner side of the seal member, the seal member is crushed so that the outer peripheral side of the seal member swells, and the outer periphery of the seal member is brought into close contact with the inner periphery of the cylindrical member. A situation will appear where the oil cannot pass between the outer periphery of the seal member and the inner periphery of the cylindrical member.

その結果、ダンパ内で余剰となる油がリザーバに流出し得なくなる危惧があるばかりでなく、上記のシール部材が押し潰された状態にあるまま、すなわち、シール部材の外周が筒状部材の内周に密着した状態のまま、フリーピストンがいわゆる反転して移動することなると、シール部材が本来摺接すべき筒状部材の内周と環状凹溝の外周側縁部との間に挟み込まれる状況になり、したがって、シール部材が破損するなどで、以降シール部材に所定の機能の発揮を期待できなくなる危惧がある。 As a result, not only may there be a risk that excess oil in the damper cannot flow into the reservoir, but the seal member remains in a crushed state, that is, the outer periphery of the seal member remains within the cylindrical member. When the free piston moves so as to be reversed while being in close contact with the circumference, the seal member is sandwiched between the inner circumference of the cylindrical member that should originally slide and the outer circumferential edge of the annular groove. Therefore, there is a concern that the sealing member cannot be expected to exhibit a predetermined function because the sealing member is damaged.

この発明は、このような現状を鑑みて創案されたものであって、その目的とするところは、所定のシール性を保障し得るのはもちろんのこと、シール部材における破損などが回避されて、その恒久的な利用が可能になり、たとえば、ダンパにおける圧力保障を可能にすべくフロントフォーク内に収装されるフリーピストンとこのフリーピストンの外周が内周に摺接する筒状部材との間に具現化するのに最適となるシール部構造の改良に関する。 The present invention was created in view of such a current situation, and the purpose of the invention is to ensure a predetermined sealing property, as well as avoid damage to the sealing member, Permanent use becomes possible, for example, between a free piston housed in a front fork and a cylindrical member whose outer periphery is in sliding contact with the inner periphery so as to enable pressure guarantee in the damper. The present invention relates to an improvement in a seal structure that is optimal for realization.

上記した目的を達成するため、本発明の手段は、一側に膨径部を有する筒状部材と、この筒状部材内に移動可能に収装されてこの筒状部材内を高圧側容室と低圧側容室とに画成する画成部材とを有し、この画成部材の外周に形成した環状凹溝内に収装したシール部材が筒状部材の内周に摺接しているシール構造において、上記画成部材に上記環状凹溝を低圧側容室に連通させる流路を形成し、上記画成部材が上記膨径部方向に移動して上記シール部材が上記膨径部内に到達したときに上記高圧側容室の油を上記環状凹溝より上記流路を介して上記低圧側容室に流出させ、上記環状凹溝の内圧で上記シール部材を膨径させるのを防止することを特徴とする。 In order to achieve the above-described object, the means of the present invention includes a cylindrical member having an enlarged diameter portion on one side and a high-pressure side chamber that is movably accommodated in the cylindrical member. seal and having a bounding member defining on the low pressure side vessel chamber, the seal member which is housed in an annular recessed groove formed in the outer periphery of the bounding member is in sliding contact with the inner periphery of the tubular member In the structure, a flow path for communicating the annular groove with the low-pressure side chamber is formed in the defining member, the defining member moves in the direction of the bulging portion, and the sealing member reaches the bulging portion. The oil in the high-pressure side chamber is caused to flow out from the annular groove to the low-pressure side chamber through the flow path, and the seal member is prevented from expanding by the internal pressure of the annular groove. It is characterized by.

そして、請求項２では、画成部材における環状凹溝と高圧側容室に対向する端面との間の肉厚部に環状凹溝内と高圧側容室との連通を許容する流路が形成されてなるとし、このときにも、上記の流路は、画成部材の移動方向に沿う方向に開穿された連通孔からなるとするのが好ましい。 In the second aspect of the present invention, a flow passage that allows communication between the annular groove and the high-pressure side chamber is formed in a thick portion between the annular groove and the end surface facing the high-pressure side chamber in the defining member. Even at this time, it is preferable that the flow path is formed of a communication hole opened in a direction along the moving direction of the defining member.

また、請求項３では、画成部材における環状凹溝と高圧側容室に対向する端面との間の肉厚部における外周に環状凹溝側と高圧側容室との連通を許容する流路が形成されてなるとし、このとき、上記の流路は、画成部材の移動方向に沿う方向に開穿された連通溝からなるとするのが好ましい。 According to a third aspect of the present invention, there is provided a flow passage that allows communication between the annular groove and the high-pressure side chamber on the outer periphery of the thick portion between the annular groove and the end surface facing the high-pressure chamber in the defining member. In this case, it is preferable that the flow path is formed of a communication groove opened in a direction along the moving direction of the defining member.

本発明によれば、次の効果が得られる。
請求項１の発明によれば、画成部材が筒状部材内を移動してシール部材が筒状部材の膨径部の内側に到達したときに、高圧側容室から画成部材の外周と筒状部材の内周との間を介して環状凹溝内に油が流入するが、シール部材の内周側に作用する環状凹溝内の圧力は流路から低圧側容室に開放されることになり、その結果、上記シール部材を膨径させる圧力作用は生ぜず、当該シール部材が膨径部の内周と画成部材の外周との間に挟み込まれるような自体は発生しない。
したがって、筒状部材における膨径部の内周とシール部材の外周側とを介して上記の油が低圧側容室側に流出することになる。
その結果、シール部材が絞め代を保障する上から弾性に富む材料で形成されて膨径し易い性状を有するとしても、画成部材が筒状部材内をいわゆる反転して移動するときに、シール部材が筒状部材の内周と環状凹溝の外周側縁部との間に挟み込まれる状況にならず、したがって、シール部材に破損などを招来させずして、シール部材における所定の機能を恒久的に発揮させることが可能になる。 According to the present invention, the following effects can be obtained.
According to the invention of claim 1, when the defining member moves in the cylindrical member and the seal member reaches the inside of the expanded diameter portion of the cylindrical member, the outer periphery of the defining member is Oil flows into the annular groove through the space between the inner periphery of the tubular member, but the pressure in the annular groove acting on the inner periphery of the seal member is released from the flow path to the low pressure side chamber. As a result, the pressure action for expanding the sealing member does not occur, and the sealing member itself is not sandwiched between the inner periphery of the expanding portion and the outer periphery of the defining member.
Therefore, the oil flows out to the low-pressure side chamber through the inner circumference of the expanded diameter portion of the cylindrical member and the outer circumference side of the seal member.
As a result, even if the sealing member is formed of a material rich in elasticity from the viewpoint of securing the tightening allowance and has a property of easily expanding, the seal member is moved when the defining member moves in a so-called reverse manner in the cylindrical member. The member is not sandwiched between the inner periphery of the cylindrical member and the outer peripheral side edge of the annular groove, and therefore the predetermined function of the seal member is made permanent without causing damage to the seal member. It is possible to make it manifest.

そして、請求項２および請求項３の発明にあっては、画成部材における高圧側容室に対向する側の肉厚部に流路が形成され、あるいは、肉厚部の外周に流路が形成されてなるから、高圧側容室からの油がこの流路を介して画成部材に形成の環状凹溝内に直接導かれることになり、その分、高圧側容室からの油の低圧側容室への流出効率が向上されることになる。 And in invention of Claim 2 and Claim 3, a flow path is formed in the thick part by the side of the defining member facing the high voltage | pressure side container, or a flow path is formed in the outer periphery of a thick part. Therefore, the oil from the high-pressure side chamber is guided directly into the annular groove formed in the defining member through this flow path. The efficiency of outflow to the side chamber will be improved.

その結果、この発明によれば、所定のシール性を保障し得るのはもちろんのこと、シール部材における破損などが回避されて、その恒久的な利用を可能にし、たとえば、ダンパにおける圧力保障を可能にすべくフロントフォーク内に収装されるフリーピストンとこのフリーピストンの外周が内周に摺接する筒状部材との間に具現化するのに最適となる。 As a result, according to the present invention, it is possible to guarantee a predetermined sealing property, as well as to prevent damage to the sealing member, and to use it permanently, for example, to ensure pressure in a damper Therefore, it is optimal to be realized between a free piston housed in the front fork and a cylindrical member whose outer periphery is in sliding contact with the inner periphery.

以下に、図示した実施形態に基づいて、この発明を説明する。
本発明の基本構造は、図１、図２に示すように、一側に膨径部２１を有する筒状部材２と、この筒状部材２内に移動可能に収装されてこの筒状部材２内を高圧側容室Ｒ１と低圧側容室Ｒ２とに画成する画成部材としてのフリーピストン１とを有し、このフリーピストン１の外周に形成した環状凹溝１１内に収装したシール部材３が筒状部材２の内周に摺接しているシール構造である。
そして、本発明では、更に、上記フリーピストン２に上記環状凹溝１１を低圧側容室Ｒ２に連通させる流路たる連通孔１３を形成し、上記フリーピストン２が上記膨径部２１方向に移動して上記シール部材３が上記膨径部２１内に到達したときに上記高圧側室の油を上記環状凹溝１１より上記連通孔１３を介して上記低圧側容室Ｒ２に流出させ、上記環状凹溝１１の内圧で上記シール部材３を膨径させるのを防止することを特徴とする。 The present invention will be described below based on the illustrated embodiments .
As shown in FIGS. 1 and 2, the basic structure of the present invention is a cylindrical member 2 having an enlarged diameter portion 21 on one side, and the cylindrical member 2 is movably accommodated in the cylindrical member 2. 2 has a free piston 1 as an defining member that defines a high-pressure side chamber R1 and a low-pressure side chamber R2, and is housed in an annular groove 11 formed on the outer periphery of the free piston 1. This is a seal structure in which the seal member 3 is in sliding contact with the inner periphery of the tubular member 2.
In the present invention, the free piston 2 is further provided with a communication hole 13 as a flow path for communicating the annular groove 11 to the low-pressure side chamber R2 in the free piston 2, and the free piston 2 moves in the direction of the expanded diameter portion 21. When the seal member 3 reaches the inside of the enlarged diameter portion 21, the oil in the high-pressure side chamber flows out from the annular groove 11 into the low-pressure side chamber R2 through the communication hole 13, and the annular recess. It is characterized in that the diameter of the seal member 3 is prevented from expanding due to the internal pressure of the groove 11.

少し説明すると、フロントフォークは、図示しないが、この実施形態では、車輪側チューブとされるアウターチューブ内に車体側チューブとされるインナーチューブが出没可能に挿通されてなり、アウターチューブに対してインナーチューブが出没するこのフロントフォークの伸縮作動時にダンパによって所定の減衰作用を発現するとしている。 To explain a little, the front fork is not shown in the figure, but in this embodiment, an inner tube, which is a vehicle body side tube, is inserted into an outer tube, which is a wheel side tube, so as to be able to protrude and retract. It is assumed that a predetermined damping action is exerted by the damper during the expansion and contraction operation of the front fork in which the tube appears and disappears.

そして、ダンパは、この実施形態では、倒立型に設定されていて、上方側部材となるシリンダ体がインナーチューブの軸芯部に垂設されると共に、下方側部材となるロッド体がアウターチューブの軸芯部に起立されてなるとし、シリンダ体に対してロッド体が出没するこのダンパの伸縮時に減衰バルブによって所定の減衰力を発生するとしている。 In this embodiment, the damper is set upside down, and the cylinder body serving as the upper member is suspended from the shaft core portion of the inner tube, and the rod body serving as the lower member is the outer tube. It is assumed that a predetermined damping force is generated by the damping valve during expansion and contraction of the damper in which the rod body protrudes and retracts with respect to the cylinder body.

そして、減衰バルブは、この実施形態では、ロッド体の先端に連設されてシリンダ体内で移動するピストン部に配在され、また、シリンダ体のボトム部の内側に配在のベースバルブ部に配在されてなるとし、シリンダ体内にピストン部で画成される伸側油室と圧側油室とが連通するときに、また、圧側油室とベースバルブ部越えのいわゆるリザーバ側とが連通するときに、それぞれが所定の大きさの減衰力を発生するとしている。 In this embodiment, the damping valve is disposed in the piston portion that is connected to the tip of the rod body and moves in the cylinder body, and is disposed in the base valve portion that is disposed inside the bottom portion of the cylinder body. When the expansion side oil chamber and the pressure side oil chamber defined by the piston portion communicate with each other in the cylinder body, and when the pressure side oil chamber and the so-called reservoir side beyond the base valve portion communicate with each other In addition, each of them generates a damping force having a predetermined magnitude.

ちなみに、ダンパの外側、すなわち、アウターチューブおよびインナーチューブの内側は、リザーバとされていて、ダンパ内で余剰となる油が、すなわち、上記のベースバルブ部に連通する後述の高圧側容室Ｒ１からの油が同じく後述の低圧側容室Ｒ２およびこの低圧側容室Ｒ２に連通する後述の膨径空部Ｒを介して流入することを許容している（図２参照）。 Incidentally, the outside of the damper, that is, the inside of the outer tube and the inner tube is used as a reservoir, and excess oil in the damper, that is, from a high-pressure side chamber R1, which will be described later, communicates with the base valve portion. The oil is allowed to flow in through a low pressure side chamber R2 and a later-described expanded diameter cavity R communicating with the low pressure side chamber R2 (see FIG. 2).

ところで、この発明におけるシール部構造は、図１および図２に示すように、筒状部材２と、フリーピストン１と、シール部材３とを有してなるとしており、筒状部材２は、フリーピストン１による高圧側容室Ｒ１と低圧側容室Ｒ２の画成を可能にすると共に低圧側容室Ｒ２に連通する膨径空間Ｒを形成する膨径部２１を有してなるとしている。 By the way, as shown in FIGS. 1 and 2, the seal portion structure in the present invention includes a cylindrical member 2, a free piston 1, and a seal member 3, and the cylindrical member 2 is free. The piston 1 has an expanded diameter portion 21 that enables the high-pressure side chamber R1 and the low-pressure side chamber R2 to be defined and forms an expanded space R that communicates with the low-pressure side chamber R2.

そして、フリーピストン１は、上記の筒状部材２の内側に移動可能に収装されてこの筒状部材２内を高圧側容室Ｒ１と低圧側容室Ｒ２とに画成し、シール部材３は、上記のフリーピストン１の外周に形成の環状凹溝１１内に収装されてその外周が筒状部材２の内周に摺接するとしている。 The free piston 1 is movably accommodated inside the tubular member 2 and defines the inside of the tubular member 2 into a high-pressure side chamber R1 and a low-pressure side chamber R2. Is accommodated in an annular groove 11 formed on the outer periphery of the free piston 1, and the outer periphery is in sliding contact with the inner periphery of the cylindrical member 2.

少し説明すると、筒状部材２は、この実施形態にあって、図示しないが、前記したダンパにおけるシリンダ体を構成するボトム部、すなわち、ベースバルブ部を内側に有するボトム部に一体に連設されて、インナーチューブに液密状態に連結される部位からなるとしている。 To explain a little, the cylindrical member 2 is integrally connected to the bottom portion constituting the cylinder body in the above-described damper, that is, the bottom portion having the base valve portion on the inside, although not shown, in this embodiment. In this case, it is formed of a portion connected to the inner tube in a liquid-tight state.

そして、筒状部材２がダンパにおけるシリンダ体のボトム端に一体に連設される部位であるとすれば、前記したように、ダンパがベースバルブ部を有することから、上記の高圧側容室Ｒ１は、ベースバルブ部とこれに対向するフリーピストン１との間に画成されることになる。 If the cylindrical member 2 is a portion integrally connected to the bottom end of the cylinder body in the damper, as described above, the damper has the base valve portion, and thus the high-pressure side chamber R1 described above. Is defined between the base valve portion and the free piston 1 opposed thereto.

それに対して、低圧側容室Ｒ２は、フリーピストン１の背後側に画成されることになり、このとき、図１には示さないが、この低圧側容室Ｒ２が筒状部材２における膨径部２１（図２参照）の内側たる膨径空間Ｒ（図２参照）が連通するとしている。 In contrast, the low-pressure side chamber R2 is defined behind the free piston 1, and at this time, the low-pressure side chamber R2 is not shown in FIG. It is assumed that the expansion space R (see FIG. 2) which is the inside of the diameter portion 21 (see FIG. 2) communicates.

なお、上記の膨径部２１には、この膨径部２１の肉厚を貫通する連通孔２２が開穿されていて、この膨径部２１の内側と外側との連通を許容しており、それゆえ、高圧側容室Ｒ１から低圧側容室Ｒ２に流出した油がこの連通孔２２を介して膨径部２１の外側に流出し得ることになる。 In addition, a communication hole 22 that penetrates the wall thickness of the expanded diameter portion 21 is opened in the expanded diameter portion 21, and communication between the inside and the outside of the expanded diameter portion 21 is allowed. Therefore, the oil that has flowed out of the high-pressure side chamber R1 into the low-pressure side chamber R2 can flow out of the enlarged diameter portion 21 through the communication hole 22.

ちなみに、膨径部２１の外側、すなわち、筒状部材２の外側は、前記したように、ダンパの外側たるフロントフォークの内側に画成されるリザーバとされている。 Incidentally, the outer side of the expanded diameter portion 21, that is, the outer side of the cylindrical member 2, is a reservoir defined inside the front fork, which is the outer side of the damper, as described above.

なお、この筒状部材２がダンパにおけるシリンダ体のボトム部に一体に連設されるとする場合には、多くの場合に、シリンダ体の形成時にこの筒状部材に相当する部位が併せて形成され、このとき、この実施形態にあっては、上記の膨径部２１も併せて形成されるであろう。 When the cylindrical member 2 is integrally connected to the bottom portion of the cylinder body in the damper, in many cases, a portion corresponding to the cylindrical member is formed at the time of forming the cylinder body. At this time, in this embodiment, the above-mentioned expanded diameter portion 21 will also be formed.

一方、このシール部構造にあっては、フリーピストン１における環状凹溝１１と低圧側容室Ｒ２に対向する端面との間の肉厚部１２に環状凹溝１１内と低圧側容室Ｒ２との連通を許容する流路たる連通孔１３が形成されていて、フリーピストン１が筒状部材２内を移動してシール部材３が筒状部材２の膨径部２１に到達したときに、シール部材３における外周が筒状部材２における膨径部２１の内周から離脱して環状凹溝１１内の低圧側容室Ｒ２への連通を許容するとしている。 On the other hand, in this seal portion structure, the annular groove 11 and the low-pressure side chamber R2 are formed in the thick portion 12 between the annular groove 11 in the free piston 1 and the end surface facing the low-pressure side chamber R2. When the free piston 1 moves in the tubular member 2 and the seal member 3 reaches the expanded diameter portion 21 of the tubular member 2, the communication hole 13 is formed. It is assumed that the outer periphery of the member 3 is separated from the inner periphery of the enlarged diameter portion 21 of the tubular member 2 to allow communication with the low-pressure side chamber R2 in the annular groove 11.

すなわち、フリーピストン１が筒状部材２内を移動してシール部材３が筒状部材２の膨径部２１の内側に到達したときに、高圧側容室Ｒ１からフリーピストン１の外周と筒状部材２の内周との間を介して環状凹溝１１内に流入した油が、図２中に破線矢印ａで示すように、シール部材３の内周と環状凹溝１１の底との間となる漏れ隙間を介して連通孔１３に流入し、この連通孔１３から低圧側容室Ｒ２に流出する。この際、シール部材３の内周側に作用する環状凹溝１１内の圧力は連通孔１３から低圧側容室Ｒ２に開放されることになり、その結果、上記シール部材を膨径させる圧力作用は生ぜず、当該シール部材が膨径部の内周と画成部材の外周との間に挟み込まれるような自体は発生しない。
したがって、筒状部材２における膨径部２１の内周とシール部材３の外周側とを介して上記の油が低圧側容室Ｒ２側に流出することになる。
その結果、シール部材３が絞め代を保障する上から弾性に富む材料で形成されて規制がなくなれば膨径し易い性状を有するとしても、フリーピストン１が筒状部材２内をいわゆる反転して移動するときに、シール部材３が筒状部材２の内周と環状凹溝１１の外周側縁部との間に挟み込まれる状況にならず、したがって、シール部材３に破損などを招来させずして、シール部材３における所定の機能を恒久的に発揮させることが可能になる。 That is, when the free piston 1 moves in the cylindrical member 2 and the seal member 3 reaches the inside of the expanded diameter portion 21 of the cylindrical member 2, the outer periphery of the free piston 1 and the cylindrical shape are formed from the high-pressure side chamber R1. The oil that has flowed into the annular groove 11 through the space between the inner periphery of the member 2 is between the inner periphery of the seal member 3 and the bottom of the annular groove 11, as indicated by a broken line arrow a in FIG. 2. It flows into the communicating hole 13 through the leakage gap and flows out from the communicating hole 13 to the low-pressure side chamber R2 . At this time, the pressure in the annular groove 11 acting on the inner peripheral side of the seal member 3 is released from the communication hole 13 to the low-pressure side chamber R2, and as a result, the pressure action that expands the diameter of the seal member. The seal member is not sandwiched between the inner periphery of the enlarged diameter portion and the outer periphery of the defining member.
Therefore, the oil flows out to the low-pressure side chamber R <b> 2 side through the inner periphery of the enlarged diameter portion 21 in the cylindrical member 2 and the outer periphery side of the seal member 3.
As a result, even if the seal member 3 is formed of a material rich in elasticity from the viewpoint of securing the tightening allowance and has the property of being easily expanded if there is no restriction, the free piston 1 reverses the inside of the cylindrical member 2 so-called. When moving, the seal member 3 is not sandwiched between the inner periphery of the tubular member 2 and the outer peripheral side edge of the annular groove 11, and therefore the seal member 3 is not damaged. Thus, the predetermined function of the seal member 3 can be made permanent.

その結果、シール部材３が絞め代を保障する上から弾性に富む材料で形成されて規制がなくなれば膨径し易い性状を有するとしても、フリーピストン１が筒状部材２内をいわゆる反転して移動するときに、シール部材３が筒状部材２の内周と環状凹溝１１の外周側縁部との間に挟み込まれる状況にならず、したがって、シール部材３に破損などを招来させずして、シール部材３における所定の機能を恒久的に発揮させることが可能になる。 As a result, even if the seal member 3 is formed of a material rich in elasticity from the viewpoint of securing the tightening allowance and has the property of being easily expanded if there is no restriction, the free piston 1 reverses the inside of the tubular member 2 so-called. When moving, the seal member 3 is not sandwiched between the inner periphery of the tubular member 2 and the outer peripheral side edge of the annular groove 11, and therefore the seal member 3 is not damaged. Thus, the predetermined function of the seal member 3 can be made permanent.

以上からすれば、このシール部構造にあっては、高圧側容室Ｒ１から環状凹溝１１内に流入した油が当初にシール部材３の内周と環状凹溝１１の底との間となる漏れ隙間を通過するようになれば足りるから、このシール部材３の内周側の流れを阻害しない限りにおいて、図３に示すように、フリーピストン１における環状凹溝１１と高圧側容室Ｒ１に対向する端面との間の肉厚部１４に環状凹溝１１と高圧側容室Ｒ１との連通を許容して、高圧側容室Ｒ１からの油の環状凹溝１１への流入を許容する流路たる連通孔１５を設けるとしても良く、また、図４に示すように、上記の肉厚部１４の外周に高圧側容室Ｒ１からの油の環状凹溝１１への誘導を許容する流路たる連通溝１６を設けるとしても良いと言い得る。 In view of the above, in this seal portion structure, the oil that has flowed into the annular groove 11 from the high-pressure side chamber R1 initially becomes between the inner periphery of the seal member 3 and the bottom of the annular groove 11. Since it suffices to pass through the leakage gap, as long as the flow on the inner peripheral side of the seal member 3 is not obstructed, as shown in FIG. 3, the annular groove 11 and the high-pressure side chamber R1 in the free piston 1 A flow allowing the annular groove 11 and the high-pressure side chamber R1 to communicate with the thick portion 14 between the opposing end surfaces, and allowing the oil to flow into the annular groove 11 from the high-pressure side chamber R1. A communication hole 15 may be provided, and as shown in FIG. 4, a flow path that allows the oil from the high-pressure side chamber R <b> 1 to be guided to the annular groove 11 on the outer periphery of the thick portion 14. It can be said that the communication groove 16 may be provided.

ちなみに、このとき、上記の連通孔１５および連通溝１６は、その軸線方向が前記の連通孔１３における軸線方向と一致していなくても良いことはもちろんである。 Incidentally, at this time, it goes without saying that the axial direction of the communication hole 15 and the communication groove 16 does not have to coincide with the axial direction of the communication hole 13.

それゆえ、この図３および図４に示す実施形態の場合には、高圧側容室Ｒ１からの油が上記の連通孔１５および連通溝１６を介して環状凹溝１１内に直接導かれることになり、その分、高圧側容室Ｒ１からの油の低圧側容室Ｒ２への流出効率が向上されることになる。 Therefore, in the case of the embodiment shown in FIGS. 3 and 4, the oil from the high-pressure side chamber R <b> 1 is directly guided into the annular groove 11 through the communication hole 15 and the communication groove 16. Accordingly, the efficiency of oil flow from the high-pressure side chamber R1 to the low-pressure side chamber R2 is improved.

前記したところは、画成部材がフリーピストン１からなるとしたが、この発明が意図するところからすれば、図示しないが、画成部材がピストンロッドに連設されたピストンであっても良く、その場合における作用効果も異ならないこともちろんである。 In the above description, the defining member is composed of the free piston 1, but from the viewpoint of the present invention, although not shown, the defining member may be a piston connected to the piston rod. Of course, the effect of the case is not different.

この発明によるシール部構造を原理的に示す図である。It is a figure which shows in principle the seal part structure by this invention. 図１のシール部構造の作動状態を図１と同様に示す図である。It is a figure which shows the operating state of the seal | sticker part structure of FIG. 1 similarly to FIG. 他の実施形態によるシール部構造を図１と同様に示す図である。It is a figure which shows the seal | sticker part structure by other embodiment similarly to FIG. さらに他の実施形態によるシール部構造を図１と同様に示す図である。It is a figure which shows the seal | sticker part structure by other embodiment similarly to FIG.

符号の説明Explanation of symbols

１画成部材としてのフリーピストン
２筒状部材
３シール部材
１１環状凹溝
１２、１４肉厚部
１３、１５流路たる連通孔
１６流路たる連通溝
２１膨径部
２２連通孔
Ｒ膨径空間
Ｒ１高圧側容室
Ｒ２低圧側容室 DESCRIPTION OF SYMBOLS 1 Free piston as defining member 2 Cylindrical member 3 Seal member 11 Annular groove 12, 14 Thick part 13, 15 Communication hole which is flow path
16 channels of communication groove 21 expanded diameter portion 22 communication hole
R upset spatial R1 pressure side vessel chamber R2 the low pressure side vessel chamber

Claims

一側に膨径部を有する筒状部材と、この筒状部材内に移動可能に収装されてこの筒状部材内を高圧側容室と低圧側容室とに画成する画成部材とを有し、この画成部材の外周に形成した環状凹溝内に収装したシール部材が筒状部材の内周に摺接しているシール構造において、上記画成部材に上記環状凹溝を低圧側容室に連通させる流路を形成し、上記画成部材が上記膨径部方向に移動して上記シール部材が上記膨径部内に到達したときに上記高圧側容室の油を上記環状凹溝より上記流路を介して上記低圧側容室に流出させ、上記環状凹溝の内圧で上記シール部材を膨径させるのを防止することを特徴とするシール部構造 A cylindrical member having an enlarged diameter portion on one side, and a defining member that is movably accommodated in the cylindrical member and defines the inside of the cylindrical member into a high-pressure side chamber and a low-pressure side chamber the a, in the sealing structure sealing member that is accommodated in an annular recessed groove formed in the outer periphery of the bounding member is in sliding contact with the inner periphery of the tubular member, the low pressure of the annular groove in the bounding member A flow path communicating with the side chamber is formed, and when the defining member moves in the direction of the enlarged diameter portion and the seal member reaches the inside of the enlarged diameter portion, the oil in the high-pressure side chamber is removed from the annular recess. A seal portion structure that prevents the seal member from flowing out from the groove through the flow path to the low-pressure side chamber and expanding the seal member with the internal pressure of the annular groove.

画成部材における環状凹溝と高圧側容室に対向する端面との間の肉厚部に環状凹溝内と高圧側との連通を許容する流路が形成されてなる請求項１に記載のシール部構造 The flow path which permits the communication between the inside of an annular groove and a high voltage | pressure side is formed in the thick part between the annular groove and the end surface which opposes a high voltage | pressure side container in an defining member. Seal structure

画成部材における環状凹溝と高圧側容室に対向する端面との間の肉厚部における外周に環状凹溝側と高圧側容室との連通を許容する流路が形成されてなる請求項１に記載のシール部構造 A flow passage that allows communication between the annular groove and the high-pressure side chamber is formed on the outer periphery of the thick portion between the annular groove and the end surface facing the high-pressure chamber in the defining member. 1. Seal part structure according to