JPH048931A - Damper - Google Patents

Abstract

PURPOSE:To quickly generate damping force and thereby lessen delay in response by making up an orifice out of a throttle hole formed in a switch-over valve, and of a needle valve which is fixed on the wall of an auxiliary oil chamber which is faced to the throttle hole while being extended into the throttle hole. CONSTITUTION:An orifice 72 which mutually connects a first and a second auxiliary oil chamber 68 and 70, is made up out of a throttle hole 72a formed in a switch-over valve 66, and a needle valve 72b which is fixed on the wall of the first auxiliary oil chamber 68 faced to the switch-over valve. The switch-over valve 66 quickly starts moving with the pressure of the first auxiliary oil chamber 65 quickly increased. This thereby causes the pressure of the second auxiliary oil chamber 70 to be increased, and consequently causes a plunger 82 to be pressed down, so that oil in the second auxiliary oil chamber 70 to run away to a lower pressure side main oil chamber 54 while speeds are lowered therein. When the opening of the orifice 72 is increased in area with the switch-over valve 66 lowered down, the difference in pressure between the first and the second auxiliary oil chamber 68 and 70 is abruptly decreased, so that the switch-over valve 66 is thereby quickly restored. By this constitution, damping force is quickly generated, and delay in response is thereby lessened.

Description

【発明の詳細な説明】 （産業上の利用分野） 本発明は、リニヤソレノイドの励１ｉｆｉ電流によって
減衰力を制御するようにした減衰器に適用される減衰力
制御装置に関するものである。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a damping force control device applied to a damper that controls damping force using an excitation current of a linear solenoid.

（発明の背景） 自動車や自動二輪車等の車輌に用いられる減衰器では、
走行条件によって減衰力を自由に変更できるのが望まし
い、そこで出願人は、減衰器とコイルばねとを一体化し
たクツションユニットの伸縮量および伸縮速度を検出し
、減衰器のピストンに設けた油路の開閉を、リニヤソレ
ノイドによって制御するものを提案した（例えば特願平
１−１２３３号参照）。(Background of the invention) In attenuators used in vehicles such as automobiles and motorcycles,
It is desirable to be able to freely change the damping force depending on driving conditions, so the applicant detected the amount and speed of expansion and contraction of a cushion unit that integrates a damper and a coil spring, and detected the amount and speed of expansion and contraction of a cushion unit that integrates a damper and a coil spring. A method was proposed in which the opening and closing of the path was controlled by a linear solenoid (see, for example, Japanese Patent Application No. 1-1233).

ここに用いた減衰器は第４図に示す構造のものである。The attenuator used here has the structure shown in FIG.

すなわち、シリンダ内に２つの主油室を１．２を画成す
るピストン３と、このピストン３内に第１・第２副油室
４．５を画成する切換弁６と、これら第１・第２副油室
間４．５に介在するオリフィス７と、前記第２副油室５
内圧によりリニヤソレノイド８の設定圧に抗して低圧側
主油室側１または２へ移動されこの第２副油室５内圧を
減圧するプランジャ９とを備え、前記第１副油室４に高
圧側主油室の油圧を導く一方、前記第２副油室５内圧が
、前記プランジャ９の移動により減圧することにより、
前記切換弁６を移動させて両生油室１．２間の油路を開
き減衰力を制御するようにしたものである。換言すれば
、両生油室１゜２間の油路を開閉する切換弁６を、その
両側の第１．２副油室４．５の差圧により移動させるに
あたり、第２副油室の内圧をリニヤソレノイド設定圧に
より制御できるようにしたものである。That is, a piston 3 defining two main oil chambers 1.2 in the cylinder, a switching valve 6 defining first and second auxiliary oil chambers 4.5 in the piston 3, and a switching valve 6 defining two main oil chambers 1.2 in the cylinder.・The orifice 7 interposed between the second auxiliary oil chambers 4.5 and the second auxiliary oil chamber 5
A plunger 9 is moved to the low-pressure side main oil chamber side 1 or 2 against the set pressure of the linear solenoid 8 by internal pressure to reduce the internal pressure of the second auxiliary oil chamber 5. While introducing the hydraulic pressure of the side main oil chamber, the internal pressure of the second auxiliary oil chamber 5 is reduced by the movement of the plunger 9.
The damping force is controlled by moving the switching valve 6 to open the oil passage between the dual oil chambers 1 and 2. In other words, when moving the switching valve 6 that opens and closes the oil passage between the dual oil chambers 1.2 using the differential pressure between the 1.2 auxiliary oil chambers 4.5 on both sides, the internal pressure of the 2nd auxiliary oil chamber can be controlled by the linear solenoid set pressure.

しかしこの場合、高圧側の主油室１または２の油圧は第
１副油室４からオリフィス７を通って第２副油室５に導
かれ、特にこのオリフィス７を介するために第２副油室
５が減圧するのに遅れが生じ、減衰力発生の応答遅れが
あるという問題があった。However, in this case, the hydraulic pressure in the main oil chamber 1 or 2 on the high pressure side is guided from the first auxiliary oil chamber 4 through the orifice 7 to the second auxiliary oil chamber 5. There was a problem in that there was a delay in reducing the pressure in the chamber 5, and there was a response delay in generating the damping force.

第５図の実１ｉ１Ａはこの従来装置の特性を表している
。The symbol 1i1A in FIG. 5 represents the characteristics of this conventional device.

（発明の目的） 本発明はこのような事情に鑑みなされたものであり、第
２副油室の内圧をリニヤソレノイドによる設定圧と平衡
させるようにした場合に、減衰力発生の応答性を良くす
るようにした減衰器を捷供することを目的とする。(Object of the Invention) The present invention was made in view of the above circumstances, and it is an object of the present invention to improve the responsiveness of damping force generation when the internal pressure of the second auxiliary oil chamber is balanced with the set pressure by the linear solenoid. The purpose of this invention is to provide an attenuator designed to do so.

（発明の構成） 本発明によればこの目的は、シリンダ内に２つの主油室
を画成するピストン内に第１・第２副油室を画成する切
換弁と、前記両副油室間に介在するオリフィスと、前記
第２副油室内圧によりリニヤソレノイド設定圧に抗して
低圧側主油室側へ移動されこの第２副油室内圧を減圧す
るプランジャとを備え、前記第１副油室に高圧側主油室
の油圧を導く一方、前記第２副油室内圧が、前記プラン
ジャの移動により減圧することにより、前記切換弁を移
動させて両主油室間の油路を開き減衰力を制御するよう
にした減衰器において、前記オリフィスは、切換弁に形
成した絞り孔と、この絞り孔に対向する前記第１副油室
の壁に固定されてこの絞り孔内に延出するニードル弁と
で形成されていることを特徴とする減衰器により達成さ
れる。(Structure of the Invention) According to the present invention, the object is to provide a switching valve that defines first and second auxiliary oil chambers in a piston that defines two main oil chambers in a cylinder; an orifice interposed therebetween; and a plunger that is moved toward the low-pressure main oil chamber side against the linear solenoid set pressure by the pressure in the second auxiliary oil chamber to reduce the pressure in the second auxiliary oil chamber, and While the hydraulic pressure in the high-pressure side main oil chamber is guided to the auxiliary oil chamber, the pressure in the second auxiliary oil chamber is reduced by the movement of the plunger, thereby moving the switching valve to open the oil passage between the two main oil chambers. In the damper configured to control opening damping force, the orifice is fixed to a throttle hole formed in the switching valve and a wall of the first auxiliary oil chamber facing the throttle hole, and extends into the throttle hole. This is achieved by means of a damper, characterized in that it is formed by a needle valve that discharges the air.

（実施例） 第１図は本発明の一実施例の要部断面図、第２図はその
使用時の概念図と機能ブロック図、第３Ａ〜３Ｅ図はそ
の動作説明図である。(Embodiment) FIG. 1 is a sectional view of a main part of an embodiment of the present invention, FIG. 2 is a conceptual diagram and functional block diagram when the same is used, and FIGS. 3A to 3E are explanatory diagrams of its operation.

第２図において符号１０はモトクロス用自動二輪車であ
り、その後輪１２はリヤアーム１４の後端に保持されて
いる。１６は減衰器１８とコイルばね２２とからなるク
ツションユニットであり、その上端がフレームに軸支さ
れる一方、その下端はリヤアーム１４に直結されここに
下方への復帰力を付与している。In FIG. 2, reference numeral 10 indicates a motocross motorcycle, and a rear wheel 12 is held at the rear end of a rear arm 14. Reference numeral 16 designates a cushion unit consisting of a damper 18 and a coil spring 22, and its upper end is pivotally supported by the frame, while its lower end is directly connected to the rear arm 14 and applies a downward return force thereto.

２６はクツションユニット１６のストローク、すなわち
後記ピストン５２の位置Ｘを検出するためのポテンショ
メークである。このポテンショメータ２６はフレームに
取付けられ、リヤアーム１４の上下動はこのポテンショ
メータ２６にリンク３０．３２によって伝えられる。ポ
テンショメータ２６が出力するピストン位置信号Ｘは図
示しない入力インターフェースを介して制御装置３４に
送られる。26 is a potentiometer for detecting the stroke of the cushion unit 16, that is, the position X of the piston 52, which will be described later. This potentiometer 26 is mounted on the frame, and the vertical movement of the rear arm 14 is transmitted to this potentiometer 26 by links 30, 32. The piston position signal X output by the potentiometer 26 is sent to the control device 34 via an input interface (not shown).

次に減衰器１８を説明する。第１図において５０はシリ
ンダ、５２はこのシリンダ５０内に２つの主油室５４．
５６を画成するピストンである。ピストン５２はピスト
ンロッド５８の上端に螺着されたソレノイドケース６０
と、このソレノイドケース６０に上方から螺着されたピ
ストンボデー６２と、このピストンボデー６２の上端に
螺着されたキャップ６４とを有する。ピストンポデー６
２内には切換弁６６が収容され、この切換弁６６がピス
トンポデー６２内に第１副油室６８と第２副油室７０と
を画成する。この切換弁６６には両側油室６８．７０間
に介在するオリフィス７２が設けられている。また切換
弁６６はばね７４によって第１副油室６８方向に付勢さ
れている。第１副油室６８には各主油室５４．５６から
チエツク弁７６．７８を介して高圧側の主油室５４また
は５６の油圧が導かれる。Next, the attenuator 18 will be explained. In FIG. 1, 50 is a cylinder, and 52 is two main oil chambers 54 within this cylinder 50.
A piston defining 56. The piston 52 has a solenoid case 60 screwed onto the upper end of the piston rod 58.
A piston body 62 is screwed onto the solenoid case 60 from above, and a cap 64 is screwed onto the upper end of the piston body 62. pistonpode 6
A switching valve 66 is housed in the piston pod 62, and this switching valve 66 defines a first sub-oil chamber 68 and a second sub-oil chamber 70 within the piston pod 62. This switching valve 66 is provided with an orifice 72 interposed between oil chambers 68 and 70 on both sides. Further, the switching valve 66 is biased toward the first auxiliary oil chamber 68 by a spring 74 . The hydraulic pressure of the main oil chamber 54 or 56 on the high pressure side is introduced to the first auxiliary oil chamber 68 from each main oil chamber 54,56 via a check valve 76,78.

オリフィス７２は、切換弁６６に設けた絞り孔７２ａと
、第１副油室６８の壁に固定されこの絞り孔７２ａ内に
延出するニードル弁７２ｂとで形成されている。このニ
ードル弁７２ｂは、第１図に示す切換弁６６の復帰位置
で絞り孔７２ａをほぼ塞ぐ一定径の円筒部と、その先端
側で先端にもかって次第に縮径するテーパ一部とを有す
る。この結果、切換弁６６がその復帰位置から所定量下
降するまではオリフィス７２の開口面積は増加せず、そ
の後その開口面積が次第に増加する。The orifice 72 is formed by a throttle hole 72a provided in the switching valve 66 and a needle valve 72b fixed to the wall of the first sub-oil chamber 68 and extending into the throttle hole 72a. This needle valve 72b has a cylindrical portion with a constant diameter that substantially closes the throttle hole 72a at the return position of the switching valve 66 shown in FIG. 1, and a tapered portion that gradually reduces in diameter toward the tip. As a result, the opening area of the orifice 72 does not increase until the switching valve 66 descends a predetermined amount from its return position, and then the opening area gradually increases.

８０はリニヤソレノイドであってソレノイドケース６０
に収容されている。このソレノイド８０は励磁電流に対
応して略一定の上向きの圧力をプランジャ８２に付与す
るものである。80 is a linear solenoid, and the solenoid case 60
is housed in. This solenoid 80 applies a substantially constant upward pressure to the plunger 82 in response to the excitation current.

次に動作を第３Ａ〜３Ｄ図により説明する。減衰器１８
の圧縮時（第３Ａ、３Ｂ図）において、圧縮初期には（
第３Ａ図）チエツク弁７６から高圧側主油室５４の作動
油が第１副油室６８に入る。この時絞り孔７２ａとニー
ドル弁７２ｂとの間隙面積、すなわちオリフィス７２の
開口面積は十分に小さいから、第１副油室６８の油圧は
切換弁６６の上面に十分に作用してこれを直接押し下げ
ようとする。このため第２副油室７０内の作動油が圧縮
されて昇圧し、プランジャ８２をリニヤソレノイド８０
の圧力に抗して押し下げる。プランジャ８２が下降すれ
ば、第２副油室７０の圧力がチエツク弁８４を経て低圧
側の主油室５６に逃げ、第１．２副油室６８．７０間に
差圧が発生する。この差圧はオリフィス７２の絞り孔７
２ａがニードル弁７２ｂで閉じられているので従来装置
（第４図）に比べて大きく、切換弁６６は急激に下降す
る。この結果、第３Ｂ図のように高圧側主油室５４が油
路８８．９０を介して低圧側主油室５６に連通し、作動
油が低圧側主油室５６に流れる。切換弁６６が所定量以
上下降するとオリフィス７２の開口面積がニードル弁７
２ａのテーパー部分の作用により急激に増加し、両側油
室６８．７０間の差圧が減る。このため切換弁６６は速
やかに上昇復帰して油路８８．９０を遮断し、減衰力を
安定化させる。すなわち第１図の状態になる６以上のよ
うに圧縮中は切換弁６６は上下動を繰り返しながら作動
油を断続している。Next, the operation will be explained with reference to FIGS. 3A to 3D. Attenuator 18
When compressing (Figures 3A and 3B), at the beginning of compression (
(FIG. 3A) The hydraulic oil in the high pressure side main oil chamber 54 enters the first sub oil chamber 68 from the check valve 76. At this time, since the area of the gap between the throttle hole 72a and the needle valve 72b, that is, the opening area of the orifice 72, is sufficiently small, the oil pressure in the first auxiliary oil chamber 68 sufficiently acts on the upper surface of the switching valve 66 and directly pushes it down. try Therefore, the hydraulic oil in the second auxiliary oil chamber 70 is compressed and the pressure increases, and the plunger 82 is moved into the linear solenoid 80.
Press down against the pressure. When the plunger 82 descends, the pressure in the second auxiliary oil chamber 70 escapes to the main oil chamber 56 on the low pressure side via the check valve 84, and a pressure difference is generated between the first and second auxiliary oil chambers 68 and 70. This differential pressure is
2a is closed by the needle valve 72b, it is larger than the conventional device (FIG. 4), and the switching valve 66 descends rapidly. As a result, as shown in FIG. 3B, the high-pressure side main oil chamber 54 communicates with the low-pressure side main oil chamber 56 via the oil passage 88.90, and the hydraulic oil flows into the low-pressure side main oil chamber 56. When the switching valve 66 descends by a predetermined amount or more, the opening area of the orifice 72 changes to the needle valve 7.
The pressure increases rapidly due to the action of the tapered portion 2a, and the differential pressure between the oil chambers 68 and 70 on both sides decreases. Therefore, the switching valve 66 quickly returns to its upward position to shut off the oil passages 88 and 90, thereby stabilizing the damping force. That is, during compression as shown in the state 6 and above in FIG. 1, the switching valve 66 repeatedly moves up and down while supplying the hydraulic oil on and off.

伸長中の動作は作動油が通るチエツク弁７６が７８に、
また８４が８６に変わるのみで他は全く同様であるから
、その説明は繰り返さない（第３Ｃ１３Ｄ図）。During the extension operation, the check valve 76 through which hydraulic oil passes is changed to 78.
Also, since the rest is exactly the same except that 84 is changed to 86, the explanation thereof will not be repeated (Fig. 3C13D).

このようにオリフィス７２をニードル弁７２ｂで閉じる
ことにより、第２副油室７０の油圧は直接切換弁６６に
押されて高められ、しかも差圧も大きくできることから
切換弁６６の応答性が格段に向上し、第５図の破ＩＩＪ
９Ｂに示すような特性を持つことになる。By closing the orifice 72 with the needle valve 72b in this way, the oil pressure in the second auxiliary oil chamber 70 is directly pushed by the switching valve 66 and is increased, and the differential pressure can also be increased, so the responsiveness of the switching valve 66 is significantly improved. improved, breaking IIJ in Figure 5
It will have the characteristics shown in 9B.

次に制御装置３４を第２図に基づき説明する。Next, the control device 34 will be explained based on FIG.

この制御装置３４は後記電流制御手段１１０の部分を除
いてデジタル演算装置で構成される。This control device 34 is constituted by a digital arithmetic device except for a portion of a current control means 110 which will be described later.

１００は前記ポテンショメータ２６の位置信号χに基づ
いて、ピストン位置Ｘを求めるピストン位置演算手段で
ある。すなわちポテンショメータ２６にはリンク３０．
３２を介してリヤアームの揺動が伝えられるため、ピス
トン位置Ｘとポテンショメータ２６出力電圧とは比例し
ない、ピストン位置演算手段１００はこの関係を修正し
て正しいピストン位置Ｘを求めるものである。Reference numeral 100 denotes a piston position calculation means for calculating the piston position X based on the position signal χ of the potentiometer 26. That is, the potentiometer 26 has a link 30.
32, the piston position X is not proportional to the output voltage of the potentiometer 26. The piston position calculation means 100 corrects this relationship to find the correct piston position X.

１０２はピストン速度演算手段であり、例えばピストン
位置Ｘの時間微分によりピストン速度Ｖを求める。１０
４はＲＯＭなどの半導体メモリで構成されたメモリ手段
である。このメモリ手段１０４は圧縮時と伸び時に対し
て、最適減衰力Ｆをピストン位置Ｘとピストン速度Ｖの
関数として決めるマツプを記憶するものである。減衰特
性は車種や走行条件などによって変更し得るものであり
、ピストン速度Ｘの増加に対し減衰力が減少する特性な
ど、従来のオリフィス制御では得られない種種の特性を
予めメモリしておいて走行条件に応じて好ましい特性を
選択して用いるようにすることも可能である。なお１０
６は補正手段であり、作動油の温度などによってマツプ
の内容を補正するデータを記憶する。１０８は減衰力演
算手段であり、ピストン位置Ｘとピストン速度■に対す
る最適減衰力Ｆをメモリ手段１０４のマツプに基づいて
求める。102 is a piston speed calculation means, which calculates the piston speed V by, for example, time differentiation of the piston position X. 10
Reference numeral 4 denotes a memory means composed of a semiconductor memory such as a ROM. This memory means 104 stores maps that determine the optimum damping force F as a function of the piston position X and the piston speed V for compression and expansion. The damping characteristics can be changed depending on the vehicle type, driving conditions, etc., and it is possible to memorize in advance various characteristics that cannot be obtained with conventional orifice control, such as the characteristic that the damping force decreases as the piston speed increases. It is also possible to select and use preferable characteristics depending on the conditions. Note 10
Reference numeral 6 denotes a correction means, which stores data for correcting the contents of the map based on the temperature of hydraulic oil and the like. 108 is a damping force calculating means, which calculates the optimum damping force F for the piston position X and the piston speed (2) based on the map in the memory means 104.

１１０は最適減衰力を得るようにリニヤソレノイド８０
の励磁電流をパルス幅制御（ＰＷＭ）する電流制御手段
である。この手段１１０により所定のデユーティ比の断
続する電流がソレノイド８０に供給され、ソレノイド８
０の圧力が制御される。この結果減衰器１８の減衰力は
ほぼリアルタイムにマツプで決まる最適値に制御され、
圧縮時と伸び時で異なる減衰力特性となるように管理す
ることができる。110 is a linear solenoid 80 to obtain the optimum damping force.
This is a current control means that performs pulse width control (PWM) on the excitation current. This means 110 supplies an intermittent current with a predetermined duty ratio to the solenoid 80.
0 pressure is controlled. As a result, the damping force of the attenuator 18 is controlled almost in real time to the optimum value determined by the map.
It is possible to manage the damping force so that it has different damping force characteristics during compression and extension.

（発明の効果） 本発明は以上のように、第１および第２副油室をつなぐ
オリフィスを、切換弁に形成した絞り孔と、これに対向
する第１副油室の壁に固定したニードル弁とで形成した
ものであるから、第１副油室の圧力が速やかに上昇し切
換弁が速やかに移動を開始する。このため第２副油室の
圧力が上昇してプランジャを押し下げ、第２副油室の油
な低圧側主油室に逃がしここを減圧する。このため切換
弁は速やかに下降し、両主油室間の油路が開いて油が流
れる。また切換弁が下降してオリフィスの開口面積が増
加すると第１．２副油室間の差圧が急激に減少し切換弁
は速やかに復帰する。このようにして減衰力が速やかに
発生し、応答の遅れが少なくなる。(Effects of the Invention) As described above, the present invention provides an orifice that connects the first and second auxiliary oil chambers through a throttle hole formed in the switching valve and a needle fixed to the wall of the first auxiliary oil chamber facing thereto. Since the switching valve is formed with a valve, the pressure in the first auxiliary oil chamber quickly rises, and the switching valve quickly starts moving. As a result, the pressure in the second auxiliary oil chamber increases, pushing down the plunger, causing oil to escape to the low-pressure side main oil sac of the second auxiliary oil chamber, thereby reducing the pressure there. Therefore, the switching valve quickly descends, and the oil passage between the two main oil chambers opens, allowing oil to flow. Further, when the switching valve is lowered and the opening area of the orifice increases, the differential pressure between the first and second sub-oil chambers decreases rapidly, and the switching valve returns quickly. In this way, damping force is generated quickly and response delay is reduced.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明の一実施例の要部断面図、第２図はその
使用時の概念図と機能ブロック図、第３Ａ〜３Ｅ図は動
作説明図、第４図は従来装置の要部断面図、第５図は減
衰特性図である。 １８・・・減衰器、　　　　　５２・・・ピストン、５
４．５６・・・主油室、　６６・・・切換弁、６８．７
０・・・第１、第２副油室 ７２・・・オリフィス、　　　７２ａ・・・絞り孔、７
２ｂ・・・ニードル弁、　　８２・・・プランジャ。 特許出願人　ヤマハ発動機株式会社 代理′人弁理士山田文雄Fig. 1 is a cross-sectional view of a main part of an embodiment of the present invention, Fig. 2 is a conceptual diagram and functional block diagram when using the same, Figs. 3A to 3E are explanatory diagrams of operation, and Fig. 4 is a main part of a conventional device. The cross-sectional view and FIG. 5 are attenuation characteristic diagrams. 18... Attenuator, 52... Piston, 5
4.56...Main oil chamber, 66...Switching valve, 68.7
0... First and second sub oil chambers 72... Orifice, 72a... Throttle hole, 7
2b... Needle valve, 82... Plunger. Patent applicant Fumio Yamada, patent attorney representing Yamaha Motor Co., Ltd.

Claims (2)

【特許請求の範囲】[Claims] （１）シリンダ内に２つの主油室を画成するピストン内
に第１・第２副油室を画成する切換弁と、前記両副油室
間に介在するオリフィスと、前記第２副油室内圧により
リニヤソレノイド設定圧に抗して低圧側主油室側へ移動
されこの第２副油室内圧を減圧するプランジャとを備え
、前記第１副油室に高圧側主油室の油圧を導く一方、前
記第２副油室内圧が、前記プランジャの移動により減圧
することにより、前記切換弁を移動させて両主油室間の
油路を開き減衰力を制御するようにした減衰器において
、 前記オリフィスは、切換弁に形成した絞り孔と、この絞
り孔に対向する前記第１副油室の壁に固定されてこの絞
り孔内に延出するニードル弁とで形成されていることを
特徴とする減衰器。(1) A switching valve that defines two main oil chambers in the cylinder and first and second sub-oil chambers in the piston, an orifice interposed between the two sub-oil chambers, and the second sub-oil chamber. and a plunger that is moved to the low-pressure main oil chamber side against the linear solenoid set pressure by the oil chamber pressure to reduce the pressure in the second auxiliary oil chamber, and the hydraulic pressure of the high-pressure side main oil chamber is transferred to the first auxiliary oil chamber. while the pressure in the second auxiliary oil chamber is reduced by the movement of the plunger, the switching valve is moved to open the oil passage between the two main oil chambers and control the damping force. In the above, the orifice is formed of a throttle hole formed in the switching valve and a needle valve fixed to the wall of the first auxiliary oil chamber facing the throttle hole and extending into the throttle hole. An attenuator featuring: （２）ニードル弁は、前記切換弁の復帰位置で前記絞り
孔をほぼ塞ぎ、先端部が先端に向って縮径するテーパー
状に形成されている請求項（１）の減衰器。(2) The attenuator according to claim 1, wherein the needle valve substantially closes the throttle hole at the return position of the switching valve, and has a tapered tip whose diameter decreases toward the tip.