JP2005016585A - Automatic speed change selector valve for two-speed hydraulic motor - Google Patents

Automatic speed change selector valve for two-speed hydraulic motor Download PDF

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JP2005016585A
JP2005016585A JP2003179967A JP2003179967A JP2005016585A JP 2005016585 A JP2005016585 A JP 2005016585A JP 2003179967 A JP2003179967 A JP 2003179967A JP 2003179967 A JP2003179967 A JP 2003179967A JP 2005016585 A JP2005016585 A JP 2005016585A
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spool
speed
hydraulic motor
pressure
diameter
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JP4160862B2 (en
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Makoto Ejiri
誠 江尻
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Nachi Fujikoshi Corp
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Nachi Fujikoshi Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic speed change selector valve for a two-speed hydraulic motor capable of reducing the hysteresis without increasing the diameter of a two-speed spool 10 and without decreasing the diameter of each small diameter spool in switching the high-speed state and the low-speed state of the two-speed hydraulic motor. <P>SOLUTION: The automatic speed change selector valve 7 comprises a hollow two-speed spool 10, a first small diameter spool C and a second small diameter spool B which are attached to both ends of the two-speed spool 10 movably in the axial direction, and a spring 8 between a hollow hole shoulder part 19 of the two-speed spool 10 and the second small diameter spool B. The external pilot pressure Pp is led to outer end parts of the first small diameter spool C and the two-speed spool. The high-pressure port pressure Pab of a hydraulic motor 1 resistant against the external pilot pressure Pp is led to a hollow hole 20 from center ports A and B so as to be constantly applied to each inner surface of the first small diameter spool C and the second small diameter spool B in the two-speed spool 10. The diameter D2 of the second small diameter spool B is set to be larger than the diameter D3 of the first small diameter spool C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】本発明は建設機械用のクローラーを駆動するための２速油圧モータにおいて、モータに作用する負荷の大きさにより低速と高速の切換を自動的に行う２速油圧モータの自動変速切換弁に関する
【０００２】
【従来の技術】従来技術としての２速油圧モータの自動変速切換弁は例えば特許文献１の図３、図４に記載するものがある。２速モータの低速状態と高速状態を切換えるこの切換弁は、外部からのパイロット圧力を受けて高速側位置へ切換わった状態になっている。油圧モータに作用する負荷が大きくなると、油圧モータの高圧ポートの圧力がシャトル弁を通って切換弁に入って来る。この圧力が、外部からのパイロット圧と対抗しており、所定の圧力以上に大きくなったときに、切換弁は低速側位置に切換わる。又、油圧モータの負荷が小さくなり、シャトル弁を通して切換弁に入って来る圧力が所定の圧力以下になったときに、切換弁は高速位置に切換わるようにされている。この切換弁の２つの切換設定圧力をＰＨｉ→ＬＯ（高速→低速）、ＰＬＯ→Ｈｉ（低速→高速）とすると、ＰＨｉ→ＬＯとＰＬＯ→Ｈｉの切換圧力の設定はスプール（本発明では２速スプールとして示す）内の隔壁で閉じられたスプールの２個の小径穴に収容された２個の丸棒部材（受圧面積調整部材−本発明では小径スプールとして示す）により調整して、ヒステリシスを設けている。これにより、油圧モータの自動変速の圧力変動に起因するハンチングを防止するものである。この従来技術では、低速・高速の設定切換圧力にヒステリシスがある。
【０００３】
【特許文献１】特開２００３−２８１０２号公報 図３、図４
【０００４】
【発明が解決しようとする課題】しかしながら、特許文献１の従来技術では、切換弁の２つの切換設定圧力ＰＨｉ→ＬＯ（高速→低速）とＰＬＯ→Ｈｉ（低速→高速）に大きなヒステリシスがあり、ＰＬＯ→Ｈｉの設定圧力が低く設定されている。切換弁を高速側位置で油圧モータを急駆動させた場合に、油圧モータの圧力が急上昇するために、一担低速側位置に切換わり、次に油圧モータの負荷圧力が下がり高速側位置に戻るが、ＰＬＯ→Ｈｉの切換設定圧力が低いために応答性が悪く、切換弁が低速側から高速側に戻るまでのタイムラグが大きく、スムーズな発進ができない。このため、ＰＨｉ→ＬＯの切換設定圧力はそのままで、ＰＬＯ→Ｈｉの切換設定圧力のみを高くする必要がある。その場合には、スプールの外径を大きくするか、スプリング側の丸棒部材の外径を小さくする必要がある。スプールの外径Ｄ１ を大きくする場合は、弁体が大きくなる。スプリング側の丸棒部材の外径Ｄ２ を小さくする場合は、加工が難しくなる。また、スプリング側の丸棒部材の外径Ｄ２ を小さくすると、ＰＬＯ→Ｈｉの切換設定圧力が大きくなり、それと同時にＰＨｉ→ＬＯの切換設定圧力が大きくなる。そのため、ＰＨｉ→ＬＯを変更せずに、ＰＬＯ→Ｈｉを大きくして、ヒステリシスを小さくする場合、外部パイロット側の丸棒部材の外径Ｄ３ も小さくしなくてはならず、加工が難しくなる。スプール径を大きくする場は弁体が大きくなり、各丸棒部材を小さくする場合は加工が難しくなるなどの課題があった。
【０００５】
本発明の課題はかかる従来技術の課題を解決した、油圧モータの２つの切換圧力（高速→低速、低速→高速）の設定において、ヒステリシスを小さくでき、かつスプール（２速スプール）の径を大きくすることなく、又、各丸棒部材（各小径スプール）の径を小さくすることなくヒステリシスを小さくした２速油圧モータの自動変速切換弁を提供することにある。
【０００６】
【課題を解決する手段】このため本発明によると、２速油圧モータの低速状態と高速状態を切換える自動変切換弁において、前記切換弁はハウジング内に両端が閉じられた大径スプール穴に軸方向に移動可能に嵌合された中空の２速スプールと、２速スプール両端に設けられた第１及び第２の小径スプール穴に軸方向に移動可能に嵌合された第１小径スプールＣ及び第２小径スプールＢと、前記２速スプールの中空穴肩部と前記第２小径スプールＢとの間を離隔する方向に付勢するスプリングと、を有し、前記第１小径スプールＣ及び２速スプールの一方の外方端部には外部パイロット圧力が導かれ、前記外部パイロット圧力と対抗する油圧モータの高圧ポート圧力を常に前記２速スプール内の第１小径スプールＣ及び第２小径スプールＢの各内側面に作用するように前記切換弁のほぼ中央に設けた中央ポートから２速スプールの中央に位置する半径方向穴より中空穴内に導くようにし、前記第２小径スプールＢの径Ｄ２を第１小径スプールＣの径Ｄ３より大にしたことを特徴とする２速油圧モータの自動変速切換弁によって上述した本発明の課題を解決した。
【０００７】
【発明の効果】本発明の構成により、外部パイロット圧力と対抗する油圧モータの高圧ポート圧力を常に前記２速スプール内の第１小径スプールＣ及び第２小径スプールＢの各内側面に作用させたので、２速スプールに作用する圧力の受圧面積は切換弁がどの位置にあっても常に同じであり、切換弁のヒステリシスを小さくすることができる。これにより、２つの切換設定圧力（高速→低速、低速→高速）の設定において、ヒステリシスを小さくでき、特に低速側位置から負荷力が下がり、高速側位置に戻るまでの応答性がよく、油圧モータの発進時などに於いてタイムラグがなく、スムーズな発進が可能となる。かつ主スプールの径を大きくすることなく、又各小径スプールの径を小さくすることなく、ヒステリシスを小さくした２速油圧モータの自動変速切換弁を提供するものとなった。
【０００８】
好ましくは、前記高圧ポート圧力が第１切替設定圧力より高く前記切換弁が低速状態位置にあるときは、前記油圧モータの速度切替コントロールピストンの加圧室はドレンに連通され、前記油圧モータの高圧ポート圧力が第２切替設定圧力より低く前記切換弁が高速状態位置にあるときは、前記油圧モータの速度切替コントロールピストンの加圧室は前記油圧モータの高圧ポート圧力と連通するようにされている。
【０００９】
【発明の実施の形態】図１は本発明の実施の形態の２速油圧モータの自動変速切換弁が低速側位置にあるときの概略断面図を含む油圧回路図、図２は同切換弁が高速側位置にあるときの概略断面図を含む油圧回路図を示す。
図１に示すように、２速油圧モータ１の低速状態と高速状態を切換える自動変切換弁７は、点線で一部を示すハウジング４内に両端がプラグ５、６により閉じられた大径スプール穴１５に軸方向に移動可能に嵌合された中空の２速スプール１０と、２速スプール１０両端に設けられた第１及び第２の小径スプール穴 １６、１７に軸方向に移動可能に嵌合された第１小径スプールＣ及び第２小径スプールＢと、２速スプール１０の中空穴肩部１９と第２小径スプールＢとの間を離隔する方向に付勢するスプリング８と、を有する。第１小径スプールＣ及び２速スプールの一方の外方端部にはパイロット圧力室２１が形成され、外部パイロット圧力Ｐｐが導かれ、外部パイロット圧力Ｐｐと対抗する油圧モータ１の高圧ポート圧力 Ｐａｂを常に２速スプール１０内の第１小径スプールＣ及び第２小径スプールＢの各内側面に作用するように、切換弁７のほぼ中央に設けた中央ポート Ａ．Ｂから２速スプール１０の中央に位置する半径方向穴１８より中空穴内２０に油圧モータ１の高圧ポート圧力 Ｐａｂを導くようにし、第２小径スプールＢの径Ｄ２を第１小径スプールＣの径Ｄ３より大にしたものである。高圧ポート圧力 Ｐａｂが第１切替設定圧ＰＨｉ→ＬＯより高く切換弁７が低速状態位置にあるときは油圧モータ１の速度切替コントロールピストン２の加圧室はドレンポートＤＲに連通され、高圧ポート圧力 Ｐａｂが第２切替設定圧ＰＬＯ→Ｈｉより低く切換弁７が高速状態位置にあるときは油圧モータ１の速度切替コントロールピストン２の加圧室は油圧モータ１の高圧ポート圧力 Ｐａｂと連通するようにされている。
【００１０】
次に作動について説明すると、図１は油圧モータ１に作用する負荷高圧ポート圧力 Ｐａｂが第１切替設定圧ＰＨｉ→ＬＯより高く、切換弁７が低速側位置にある場合を示し、油圧ポンプ１３の圧油は、方向切替弁１２、高圧ポートの圧力 Ｐａｂが、カウンターバランス弁１１を通って中央ポート Ａ．Ｂから２速スプール１０の半径方向穴１８より中空穴内２０に流入し、スプールＢを図１でみて右方向へ、スプールＣを同左方向へ押し付けている。これにより、２速スプール１０に作用する力は、Ｆａｂ ＝Ｐａｂ ×π／４（Ｄ２ ２ −Ｄ３ ２ ）となり、Ｄ２ ＞Ｄ３ であるから、２速スプール１０を左方向へ押す力となる。一方外部パイロット圧力Ｐｐは２速スプール１０の左端ポートＰｐからパイロット圧力室２１に導かれており、２速スプール１０に作用する力はＦｐ＝Ｐｐ・π／４×（Ｄ１ ２ −Ｄ３ ２ ）となり、Ｄ１ ＞Ｄ３ であるから、２速スプール１０を右方向へ押す力となる。又スプリング８は２速スプール１０を左方向へ押す力 Ｆｓｐとなっている。図１の場合は、油圧モータ１に作用する負荷が大きく（＝ Ｐａｂが大きい）、２速スプール１０に作用する力Ｆｐ＜Ｆａｂ ＋Ｆｓｐ となり２速スプール１０が左方向へ押し付けられる。この時油圧モータ１のコントロールピストン２の加圧室内圧力 Ｐｃｐはシャトル弁３を介して切換弁７のポート Ａ’’又はポート Ｂ’’からＤＲポートへ通じており、油圧モータ１は低速側位置になる。
【００１１】
図２は油圧モータ１に作用する高圧ポート圧力 Ｐａｂが第２切替設定圧ＰＬＯ→Ｈｉより低く切換弁７が高速側位置にある場合を示し、高圧ポート圧力 Ｐａｂが、カウンターバランス弁１１を通って中央ポート Ａ．Ｂから２速スプール１０の半径方向穴１８より中空穴内２０に流入する。高速側位置にある２速スプール１０に作用する力Ｆｐ＝Ｆａｂ ＋Ｆｓｐ となり、２速スプール１０が右へ押し付けられている。この時コントロールピストン２内圧力 Ｐｃｐはシャトル弁３を介して切換弁７のポート Ａ’’又はポート Ｂ’’から、Ａ’ポート又はポートＢ’へ通じている。これにより、油圧モータ１の高圧ポートの圧力 Ｐａｂである負荷圧力Ｐ’ａ 又はＰ’ｂ が切換弁７とシャトル弁３を通してコントロールピストン２へ流入し、１点鎖線で示すように、油圧モータ１は高速側位置となる。以上より２速スプール１０に作用する力のつり合い式は常に、「Ｆｐ＝Ｆａｂ ＋Ｆｓｐ 」で表され、切換弁のヒステリシスはスプリング定数と２速スプール１０の図示しないオーバーラップ量により設けられるが、いずれも微少であり、従来技術で問題となるタイムラグがなく、２つの切換圧力（高速→低速、低速→高速）の設定において油圧モータ１のスムーズな発進が可能となる。
【００１２】
〔発明の実施の形態の効果〕本発明の実施の形態によれば、高圧ポートの圧力 Ｐａｂを常に２速スプール内の第１小径スプールＣ及び第２小径スプールＢの各内側面に作用させたので、２速スプール１０に作用する圧力の受圧面積は切換弁がどの位置にあっても常に同じであり、２つの切換設定圧力（高速→低速、低速→高速）の設定において、２速スプール１０（主スプール）の径を大きくすることなく、又、各小径スプール（各丸棒部材）の径を小さくすることなく切換弁のヒステリシスを小さくすることができる。これにより、特に低速側位置から油圧モータの負荷圧力が下がり、高速側位置に戻るまでの応答性がよく、油圧モータの発進時のタイムラグがなく、スムーズな発進が可能となった。
【図面の簡単な説明】
【図１】本発明の実施の形態の２速油圧モータの自動変速切換弁が低速側位置にあるときの概略断面図を含む油圧回路図を示す。
【図２】同切換弁が高速側位置にあるときの概略断面図を含む油圧回路図。
【符号の説明】
１・・２速油圧モータ ２・・コントロールピストン ３・・シャトル弁
４・・ハウジング ７・・自動変切換弁 ８・・スプリング
１０・・２速スプール １５・・大径スプール穴 １６・・第１の小径スプール穴
１７・・第２の小径スプール穴 １９・・２速スプールの中空穴肩部
２０・・２速スプールの中空穴 ２１・・パイロット圧力室
Ｂ・・第２小径スプール Ｃ・・第１小径スプール
Ｄ２・・第２小径スプールＢの径 Ｄ３・・第１小径スプールＣの径[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-speed hydraulic motor for driving a crawler for a construction machine. The two-speed hydraulic motor automatically switches between a low speed and a high speed according to the magnitude of a load acting on the motor. [0002] Automatic shift switching valve
2. Description of the Related Art A conventional automatic transmission switching valve for a two-speed hydraulic motor is disclosed in, for example, FIGS. This switching valve that switches between the low speed state and the high speed state of the two-speed motor is in a state of being switched to the high speed side position in response to an external pilot pressure. When the load acting on the hydraulic motor increases, the pressure of the high pressure port of the hydraulic motor enters the switching valve through the shuttle valve. When this pressure is opposed to the pilot pressure from the outside and becomes larger than a predetermined pressure, the switching valve is switched to the low speed side position. Further, when the load of the hydraulic motor becomes small and the pressure entering the switching valve through the shuttle valve becomes a predetermined pressure or less, the switching valve is switched to the high speed position. If the two switching setting pressures of this switching valve are P Hi → LO (high speed → low speed) and P LO → Hi (low speed → high speed), the switching pressure setting of P Hi → LO and P LO → Hi is set to spool (main In the present invention, it is adjusted by two round bar members (pressure-receiving area adjusting member-shown as a small-diameter spool in the present invention) accommodated in two small-diameter holes of a spool closed by an inner partition wall. Hysteresis is provided. This prevents hunting due to pressure fluctuations in automatic shifting of the hydraulic motor. In this prior art, there is hysteresis in the low-speed / high-speed setting switching pressure.
[0003]
[Patent Document 1] Japanese Patent Laid-Open No. 2003-28102 FIGS. 3 and 4
[0004]
However, in the prior art of Patent Document 1, there is a large hysteresis between the two switching set pressures P Hi → LO (high speed → low speed) and P LO → Hi (low speed → high speed) of the switching valve. Yes, the set pressure of P LO → Hi is set low. When the hydraulic motor is suddenly driven with the switching valve at the high speed side position, the pressure of the hydraulic motor suddenly rises, so it switches to the single low speed side position, and then the load pressure of the hydraulic motor decreases and returns to the high speed side position. However, since the switching setting pressure of P LO → Hi is low, the responsiveness is poor, the time lag until the switching valve returns from the low speed side to the high speed side is large, and a smooth start is not possible. Thus, switch setting pressure P Hi → LO is intact, it is necessary to increase only the switch setting pressure P LO → Hi. In that case, it is necessary to increase the outer diameter of the spool or to decrease the outer diameter of the spring-side round bar member. If increasing the outer diameter D 1 of the spool valve body increases. When reducing the outer diameter D 2 of the spring-side of the rod member, processing becomes difficult. Also, reducing the outer diameter D 2 of the spring-side of the round bar member, switch setting pressure P LO → Hi increases therewith switch setting pressure P Hi → LO is increased at the same time. Therefore, when P LO → Hi is increased to reduce hysteresis without changing P Hi → LO , the outer diameter D 3 of the round rod member on the external pilot side must also be reduced, and the processing is reduced. It becomes difficult. When the spool diameter is increased, the valve body is increased, and when each round bar member is decreased, there is a problem that processing becomes difficult.
[0005]
The object of the present invention is to solve the problems of the prior art, and in setting the two switching pressures (high speed → low speed, low speed → high speed) of the hydraulic motor, the hysteresis can be reduced and the diameter of the spool (second speed spool) can be increased. It is another object of the present invention to provide an automatic transmission switching valve for a two-speed hydraulic motor with reduced hysteresis without reducing the diameter of each round bar member (each small diameter spool).
[0006]
Therefore, according to the present invention, in an automatic variable switching valve for switching between a low speed state and a high speed state of a two-speed hydraulic motor, the switching valve is pivoted into a large-diameter spool hole closed at both ends in the housing. A hollow two-speed spool that is movably fitted in a direction, and a first small-diameter spool C that is fitted in first and second small-diameter spool holes provided at both ends of the two-speed spool and is movably fitted in the axial direction; A second small-diameter spool B, and a spring urging in a direction to separate the hollow hole shoulder of the second-speed spool and the second small-diameter spool B, and the first small-diameter spool C and the second-speed spool An external pilot pressure is guided to one outer end of the spool, and the high pressure port pressure of the hydraulic motor that opposes the external pilot pressure is always applied to the first small diameter spool C and the second small diameter spool B in the second speed spool. A central port provided substantially at the center of the switching valve so as to act on the inner surface is guided into a hollow hole from a radial hole located at the center of the second speed spool, and the diameter D2 of the second small diameter spool B is set to the first. The above-described problems of the present invention have been solved by an automatic transmission switching valve for a two-speed hydraulic motor characterized by having a diameter larger than the diameter D3 of the small-diameter spool C.
[0007]
According to the construction of the present invention, the high pressure port pressure of the hydraulic motor that opposes the external pilot pressure is always applied to the inner surfaces of the first small diameter spool C and the second small diameter spool B in the second speed spool. Therefore, the pressure receiving area of the pressure acting on the second speed spool is always the same regardless of the position of the switching valve, and the hysteresis of the switching valve can be reduced. As a result, the hysteresis can be reduced in the setting of the two switching set pressures (high speed → low speed, low speed → high speed), and in particular, the responsiveness until the load force decreases from the low speed side position and returns to the high speed side position is good. There is no time lag when starting, and smooth starting is possible. In addition, the present invention provides an automatic transmission switching valve for a two-speed hydraulic motor with reduced hysteresis without increasing the diameter of the main spool and without reducing the diameter of each small-diameter spool.
[0008]
Preferably, when the high pressure port pressure is higher than the first switching set pressure and the switching valve is in the low speed position, the pressure chamber of the speed switching control piston of the hydraulic motor is communicated with a drain, and the high pressure of the hydraulic motor is increased. When the port pressure is lower than the second switching set pressure and the switching valve is in the high speed position, the pressure chamber of the speed switching control piston of the hydraulic motor communicates with the high pressure port pressure of the hydraulic motor. .
[0009]
1 is a hydraulic circuit diagram including a schematic sectional view of an automatic transmission switching valve of a two-speed hydraulic motor according to an embodiment of the present invention at a low speed side position. FIG. The hydraulic circuit diagram containing a schematic sectional drawing when it exists in a high-speed side position is shown.
As shown in FIG. 1, an automatic variable switching valve 7 for switching between a low speed state and a high speed state of a two-speed hydraulic motor 1 is a large-diameter spool whose ends are closed by plugs 5 and 6 in a housing 4 partially indicated by a dotted line. A hollow two-speed spool 10 fitted in the hole 15 so as to be movable in the axial direction, and first and second small-diameter spool holes 16, 17 provided at both ends of the second speed spool 10 are fitted so as to be movable in the axial direction. The first small-diameter spool C and the second small-diameter spool B that are joined together, and the spring 8 that urges the hollow hole shoulder portion 19 of the second-speed spool 10 and the second small-diameter spool B in the direction of separating. A pilot pressure chamber 21 is formed at one outer end of each of the first small-diameter spool C and the second-speed spool, and the external pilot pressure Pp is guided to the high pressure port pressure Pab of the hydraulic motor 1 that opposes the external pilot pressure Pp. A central port provided substantially at the center of the switching valve 7 so as to always act on the inner surfaces of the first small-diameter spool C and the second small-diameter spool B in the second-speed spool 10. The high pressure port pressure Pab of the hydraulic motor 1 is guided from the radial hole 18 located at the center of the second speed spool 10 to the hollow hole 20 from B, and the diameter D2 of the second small diameter spool B is set to the diameter D3 of the first small diameter spool C. It is a larger one. When the high pressure port pressure Pab is higher than the first switching set pressure P Hi → LO and the switching valve 7 is in the low speed position, the pressurizing chamber of the speed switching control piston 2 of the hydraulic motor 1 is communicated with the drain port DR. pressurizing chamber of speed change control piston 2 of the hydraulic motor 1 communicates with the high pressure port pressure Pab of the hydraulic motor 1 is when the pressure Pab second switch setting pressure P LO → switching valve 7 below Hi is in a high speed state position Has been.
[0010]
Next, the operation will be described. FIG. 1 shows a case where the load high pressure port pressure Pab acting on the hydraulic motor 1 is higher than the first switching set pressure P Hi → LO , and the switching valve 7 is in the low speed side position. The pressure oil of the direction switch valve 12 and the pressure Pab of the high pressure port pass through the counter balance valve 11 and the central port A. B flows into the hollow hole 20 from the radial hole 18 of the second-speed spool 10 and presses the spool B in the right direction and the spool C in the left direction as viewed in FIG. As a result, the force acting on the second speed spool 10 is Fab = Pab × π / 4 (D 2 2 −D 3 2 ), and D 2 > D 3 , and therefore the force that pushes the second speed spool 10 leftward. It becomes. On the other hand, the external pilot pressure Pp is led from the left end port Pp of the second speed spool 10 to the pilot pressure chamber 21, and the force acting on the second speed spool 10 is Fp = Pp · π / 4 × (D 1 2 −D 3 2 ), And D 1 > D 3 , so that the second speed spool 10 is pushed to the right. The spring 8 has a force Fsp that pushes the second speed spool 10 leftward. In the case of FIG. 1, the load acting on the hydraulic motor 1 is large (= Pab is large), and the force Fp <Fab + Fsp acting on the second-speed spool 10 is satisfied, and the second-speed spool 10 is pressed leftward. At this time, the pressure chamber pressure Pcp of the control piston 2 of the hydraulic motor 1 is connected to the DR port from the port A ″ or the port B ″ of the switching valve 7 via the shuttle valve 3, and the hydraulic motor 1 is positioned at the low speed side. become.
[0011]
Figure 2 is a high-pressure port pressure Pab acting on the hydraulic motor 1 is shown a case where the second switch set pressure P LO → switching valve 7 below Hi is in a high speed side position, the high pressure port pressure Pab is, through the counterbalance valve 11 Central port A. B flows into the hollow hole 20 from the radial hole 18 of the second speed spool 10. The force Fp = Fab + Fsp acting on the second speed spool 10 at the high speed side position is established, and the second speed spool 10 is pressed to the right. At this time, the pressure Pcp in the control piston 2 is communicated from the port A ″ or the port B ″ of the switching valve 7 to the A ′ port or the port B ′ via the shuttle valve 3. As a result, the load pressure P′a or P′b, which is the pressure Pab of the high-pressure port of the hydraulic motor 1, flows into the control piston 2 through the switching valve 7 and the shuttle valve 3, and as shown by the one-dot chain line, Is the high speed side position. From the above, the balance formula of the force acting on the second speed spool 10 is always expressed by “Fp = Fab + Fsp”, and the hysteresis of the switching valve is provided by the spring constant and the overlap amount (not shown) of the second speed spool 10, Therefore, there is no time lag which is a problem in the prior art, and the hydraulic motor 1 can be started smoothly at the setting of two switching pressures (high speed → low speed, low speed → high speed).
[0012]
[Effect of the Embodiment of the Invention] According to the embodiment of the present invention, the pressure Pab of the high-pressure port is always applied to the inner surfaces of the first small-diameter spool C and the second small-diameter spool B in the second-speed spool. Therefore, the pressure receiving area of the pressure acting on the two-speed spool 10 is always the same regardless of the position of the switching valve, and the two-speed spool 10 is set at two switching setting pressures (high speed → low speed, low speed → high speed). The hysteresis of the switching valve can be reduced without increasing the diameter of the (main spool) and without decreasing the diameter of each small diameter spool (each round bar member). As a result, the responsiveness until the load pressure of the hydraulic motor drops from the low speed side position to the high speed side position is particularly good, and there is no time lag at the start of the hydraulic motor, making it possible to start smoothly.
[Brief description of the drawings]
FIG. 1 is a hydraulic circuit diagram including a schematic cross-sectional view when an automatic shift switching valve of a two-speed hydraulic motor according to an embodiment of the present invention is at a low speed side position.
FIG. 2 is a hydraulic circuit diagram including a schematic cross-sectional view when the switching valve is in a high speed side position.
[Explanation of symbols]
1 ・ ・ 2-speed hydraulic motor 2 ・ ・ Control piston 3 ・ ・ Shuttle valve 4 ・ ・ Housing 7 ・ ・ Automatic changeover valve 8 ・ ・ Spring 10 ・ ・ 2 speed spool 15 ・ ・ Large diameter spool hole 16 ・ ・ 1st Small-diameter spool hole 17 ··· Second small-diameter spool hole 19 ·· Hollow hole shoulder portion of second-speed spool · · Hollow hole of second-speed spool 21 · · Pilot pressure chamber B · · Second small-diameter spool C · · · 1 small diameter spool D2 ·· diameter of the second small diameter spool B D3 · · diameter of the first small diameter spool C

Claims (2)

２速油圧モータの低速状態と高速状態を切換える自動変切換弁において、前記切換弁はハウジング内に両端が閉じられた大径スプール穴に軸方向に移動可能に嵌合された中空の２速スプールと、２速スプール両端に設けられた第１及び第２の小径スプール穴に軸方向に移動可能に嵌合された第１小径スプールＣ及び第２小径スプールＢと、前記２速スプールの中空穴肩部と前記第２小径スプールＢとの間を離隔する方向に付勢するスプリングと、を有し、前記第１小径スプールＣ及び２速スプールの一方の外方端部には外部パイロット圧力が導かれ、前記外部パイロット圧力と対抗する油圧モータの高圧ポート圧力を常に前記２速スプール内の第１小径スプールＣ及び第２小径スプールＢの各内側面に作用するように前記切換弁のほぼ中央に設けた中央ポートから２速スプールの中央に位置する半径方向穴より中空穴内に導くようにし、前記第２小径スプールＢの径Ｄ２を第１小径スプールＣの径Ｄ３より大にしたことを特徴とする２速油圧モータの自動変速切換弁。In the automatic variable switching valve that switches between a low speed state and a high speed state of a two-speed hydraulic motor, the switch valve is a hollow two-speed spool that is fitted in a large-diameter spool hole that is closed at both ends in the housing so as to be axially movable. A first small-diameter spool C and a second small-diameter spool B that are fitted in first and second small-diameter spool holes provided at both ends of the second-speed spool so as to be movable in the axial direction, and a hollow hole in the second-speed spool A spring urging in a direction to separate the shoulder and the second small diameter spool B, and external pilot pressure is applied to one outer end of the first small diameter spool C and the second speed spool. The switching valve is substantially centered so that the high pressure port pressure of the hydraulic motor guided and opposed to the external pilot pressure always acts on the inner surfaces of the first small diameter spool C and the second small diameter spool B in the second speed spool. In The second small diameter spool B has a diameter D2 larger than a diameter D3 of the first small diameter spool C so that the radial port located in the center of the second speed spool is guided from the center port to the hollow hole. Automatic speed change valve for 2-speed hydraulic motor. 前記高圧ポート圧力が第１切替設定圧力より高く前記切換弁が低速状態位置にあるときは、前記油圧モータの速度切替コントロールピストンの加圧室はドレンに連通され、前記油圧モータの高圧ポート圧力が第２切替設定圧力より低く前記切換弁が高速状態位置にあるときは、前記油圧モータの速度切替コントロールピストンの加圧室は前記油圧モータの高圧ポート圧力と連通するようにしたことを特徴とする請求項１記載の２速油圧モータの自動変速切換弁。When the high pressure port pressure is higher than the first switching set pressure and the switching valve is in the low speed position, the pressurizing chamber of the speed switching control piston of the hydraulic motor is connected to the drain, and the high pressure port pressure of the hydraulic motor is The pressure chamber of the speed switching control piston of the hydraulic motor communicates with the high pressure port pressure of the hydraulic motor when the switching valve is at a high speed position lower than the second switching set pressure. The automatic transmission switching valve for a two-speed hydraulic motor according to claim 1.
JP2003179967A 2003-06-24 2003-06-24 Automatic transmission switching valve for 2-speed hydraulic motor Expired - Lifetime JP4160862B2 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103591282A (en) * 2013-11-27 2014-02-19 贵州大学 Engineering machinery walking speed controlling and switching valve
CN111852661A (en) * 2020-05-22 2020-10-30 中国航发贵州红林航空动力控制科技有限公司 High-pressure large-flow valve assembly

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015017684A (en) * 2013-07-12 2015-01-29 株式会社不二越 Automatic shift switching valve for two-speed hydraulic motor

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103591282A (en) * 2013-11-27 2014-02-19 贵州大学 Engineering machinery walking speed controlling and switching valve
CN111852661A (en) * 2020-05-22 2020-10-30 中国航发贵州红林航空动力控制科技有限公司 High-pressure large-flow valve assembly
CN111852661B (en) * 2020-05-22 2022-08-05 中国航发贵州红林航空动力控制科技有限公司 High-pressure large-flow valve assembly

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