JPH05272505A - Hydraulic circuit having pressure-compensation valve - Google Patents
Hydraulic circuit having pressure-compensation valveInfo
- Publication number
- JPH05272505A JPH05272505A JP4102548A JP10254892A JPH05272505A JP H05272505 A JPH05272505 A JP H05272505A JP 4102548 A JP4102548 A JP 4102548A JP 10254892 A JP10254892 A JP 10254892A JP H05272505 A JPH05272505 A JP H05272505A
- Authority
- JP
- Japan
- Prior art keywords
- pressure
- valve
- relief valve
- load
- pump
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Fluid-Pressure Circuits (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、複数のポンプの吐出圧
油を複数の操作弁によって複数のアクチュエータに供給
する圧力補償弁を有する油圧回路に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit having a pressure compensating valve for supplying pressure oil discharged from a plurality of pumps to a plurality of actuators by a plurality of operating valves.
【０００２】[0002]
【従来の技術】圧力補償弁を有する油圧回路としては例
えば特開昭６２−８８８０３号公報に示すものが知られ
ている。すなわち、ポンプの吐出路に複数のクローズド
センタ型式の操作弁を配設し、その操作弁とアクチュエ
ータの接続回路に圧力補償弁を設け、各アクチュエータ
の負荷圧における最高圧をチェック弁で検出し、その負
荷圧を各圧力補償弁のバネ室に供給して、その負荷圧に
対応するセット圧とする油圧回路が知られている。2. Description of the Related Art As a hydraulic circuit having a pressure compensating valve, for example, one disclosed in Japanese Patent Application Laid-Open No. 62-88803 is known. That is, a plurality of closed center type operation valves are arranged in the discharge path of the pump, a pressure compensation valve is provided in the connection circuit between the operation valve and the actuator, and the maximum pressure of the load pressure of each actuator is detected by a check valve, A hydraulic circuit is known in which the load pressure is supplied to the spring chamber of each pressure compensation valve to make a set pressure corresponding to the load pressure.
【０００３】かかる油圧回路であれば、複数の操作弁を
同時操作した時に複数のアクチュエータの負荷圧におけ
る最高圧によって圧力補償弁がセットされ、複数のアク
チェータの負荷圧が異なっても操作弁の開口面積比によ
って複数のアクチュエータに流量分配できる。With such a hydraulic circuit, when a plurality of operating valves are simultaneously operated, the pressure compensating valve is set by the maximum pressure among the load pressures of a plurality of actuators, and the opening of the operating valve is achieved even if the load pressures of a plurality of actuators differ. The flow rate can be distributed to a plurality of actuators by the area ratio.
【０００４】[0004]
【発明が解決しようとする課題】かかる油圧回路油圧回
路においては、油圧ポンプのポンプ吐出圧と負荷圧の差
圧によって油圧ポンプの斜板を傾転制御するＬＳ弁を備
え、ポンプ吐出圧が負荷圧よりも前述の差圧だけ高くな
るようにしている。他方、アクチュエータがストローク
エンドとなったり、アクチュエータに著しく大きく負荷
が作用して負荷圧が非常に高くなるとポンプ吐出圧も非
常に高くなって油圧機器の寿命に影響を及ぼすので、ポ
ンプ吐出圧をタンクに流出、つまりリリーフしてポンプ
吐出圧を制限している。このリリーフ時にはポンプ吐出
圧と負荷圧の差圧が前述のＬＳ弁により設定した差圧よ
りも大になろうとするため油圧ポンプの斜板が自動的に
最小斜板角、つまりカットオフ状態となって油圧ポンプ
の吐出量が最少となりリリーフ流量が減少するのでリリ
ーフロスを低減できる。しかしながら、前述の負荷圧が
非常に高い状態からその負荷圧が小さくなってリリーフ
しなくなった時に最小斜板角の斜板が必要な斜板角とな
るまでに通常０．２〜０．４秒の時間遅れがあり、この
間油圧ポンプの吐出量が不足してしまう。例えば、パワ
ーショベルなどの掘削機の油圧回路とした場合に、バケ
ットによる掘削中に岩石を掘りおこす時にはバケットシ
リンダの負荷が著しく大となって前述のリリーフ作動し
て油圧ポンプが最小斜板角となり、掘りおこした岩石を
バケットで掬い込む時にはバケットシリンダの負荷が小
となって前述のリリーフ作動が中止するが、最小斜板角
の斜板が必要な斜板角になるまでに時間遅れがあり、こ
の間バケットの力が不足してオペレータは掘削力の小さ
な掘削機であると感覚してしまう。In such a hydraulic circuit hydraulic circuit, an LS valve for tilt-controlling the swash plate of the hydraulic pump by the differential pressure between the pump discharge pressure of the hydraulic pump and the load pressure is provided, and the pump discharge pressure is the load. It is designed to be higher than the pressure by the above-mentioned differential pressure. On the other hand, if the actuator reaches the stroke end, or if the load pressure becomes extremely high due to a significantly large load acting on the actuator, the pump discharge pressure will also become very high and affect the life of hydraulic equipment. It flows out, that is, reliefs to limit the pump discharge pressure. At the time of this relief, the differential pressure between the pump discharge pressure and the load pressure tends to become larger than the differential pressure set by the LS valve described above, so the swash plate of the hydraulic pump automatically becomes the minimum swash plate angle, that is, the cut-off state. As a result, the discharge amount of the hydraulic pump is minimized and the relief flow rate is reduced, so relief loss can be reduced. However, it usually takes 0.2 to 0.4 seconds until the swash plate with the minimum swash plate angle reaches the required swash plate angle when the above-mentioned load pressure becomes too high and the relief pressure is reduced. However, the discharge amount of the hydraulic pump becomes insufficient during this period. For example, in the case of a hydraulic circuit of an excavator such as a power shovel, when rock is excavated during excavation by a bucket, the load on the bucket cylinder is significantly increased and the relief operation described above causes the hydraulic pump to reach the minimum swash plate angle. , When scooping rocks dug up with a bucket, the load on the bucket cylinder becomes small and the above-mentioned relief operation is stopped, but there is a time delay until the swash plate with the minimum swash plate angle becomes the required swash plate angle, During this time, the power of the bucket is insufficient, and the operator feels that the excavator has a small excavation force.
【０００５】そこで、本発明は前述の課題を解決できる
ようにした圧力補償弁を有する油圧回路を提供すること
を目的とする。Therefore, an object of the present invention is to provide a hydraulic circuit having a pressure compensating valve capable of solving the above-mentioned problems.
【０００６】[0006]
【課題を解決するための手段】複数の油圧ポンプ１と、
圧力補償弁５を有する複数の操作弁２と、複数の操作弁
２の負荷圧を検出して圧力補償弁５にフィードバックす
る複数の負荷圧導入路６を有する圧力補償弁を有する油
圧回路において、前記油圧ポンプ１の斜板７を傾転制御
するＬＳ弁１０と、前記負荷圧導入路６に設けたセット
圧可変のリリーフ弁３８と、前記油圧ポンプ１の吐出路
１ａに設けられ前記リリーフ弁３８の低圧セット圧より
高圧セット圧である主リリーフ弁２６と、前記リリーフ
弁３８のセット圧を可変とする手段を設けて成る圧力補
償弁を有する油圧回路。A plurality of hydraulic pumps 1, and
In a hydraulic circuit having a plurality of operating valves 2 having pressure compensating valves 5 and a pressure compensating valve having a plurality of load pressure introducing passages 6 for detecting load pressures of the plurality of operating valves 2 and feeding back to the pressure compensating valves 5, An LS valve 10 for tilting and controlling the swash plate 7 of the hydraulic pump 1, a relief valve 38 having a variable set pressure provided in the load pressure introducing passage 6, and a relief valve provided in the discharge passage 1a of the hydraulic pump 1. A hydraulic circuit having a main relief valve 26 having a higher set pressure than the low pressure set pressure of 38, and a pressure compensating valve provided with means for varying the set pressure of the relief valve 38.
【０００７】[0007]
【作 用】リリーフ弁３８のセット圧を低圧とすれば
負荷圧が高い時に油圧ポンプ１の斜板７を最小斜板角と
してリリーフロスを低減できるし、リリーフ弁３８のセ
ット圧を高圧とすれば負荷圧が高い時に主リリーフ弁２
６がリリーフ作動してその負荷圧低下時に必要流量を時
間遅れなくアクチュエータに供給できる。[Operation] If the set pressure of the relief valve 38 is set to a low pressure, the swash plate 7 of the hydraulic pump 1 can be set to a minimum swash plate angle to reduce relief loss when the load pressure is high, and the set pressure of the relief valve 38 can be set to a high pressure. For example, when the load pressure is high, the main relief valve 2
The relief operation of 6 can supply the required flow rate to the actuator without a time delay when the load pressure decreases.
【０００８】[0008]
【実 施 例】図１に示すように、油圧ポンプ１の吐出
路１ａには操作弁２が設けられ、この操作弁２とアクチ
ュエータ３を接続する回路４に圧力補償弁５が設けてあ
り、そのアクチュエータ３の負荷圧は操作弁２内の絞り
を通して負荷圧導入路６に導入される。前記油圧ポンプ
１の斜板７は小径ピストン８で容量大方向に傾転され、
大径ピストン９で容量小方向に傾転されると共に、その
小径ピストン８の小径受圧室８ａは前記吐出路１ａに接
続してポンプ吐出圧が供給され、前記大径ピストン９の
大径受圧室９ａはＬＳ弁１０で吐出路１ａとタンク１１
に連通制御される。前記ＬＳ弁１０は負荷圧とばね１２
でドレーン位置Ａに押され、ポンプ吐出圧で供給位置Ｂ
に押されるようになって、ポンプ吐出圧を負荷圧よりも
若干高い圧力、例えば２０ｋｇ／ｃｍ2 となるように斜
板７を傾転動作する。前記油圧ポンプ１の吐出路１ａに
はアンロード弁１３が設けられ、このアンロード弁１３
はばねと第１受圧部１４に供給される負荷圧でオンロー
ド位置１３ａに押され、第２受圧部１５に供給されるポ
ンプ吐出圧でアンロード位置１３ｂに押され、ポンプ吐
出圧と負荷圧の差圧が設定圧力、例えば３０ｋｇ／ｃｍ
2 以上となるとアンロード位置１３ｂとなるもので、複
数の油圧ポンプの個別のポンプ吐出圧と負荷圧のみによ
って作動する。パイロット油圧弁１６はレバー１７を操
作することで補助ポンプ１８の吐出圧油を第１・第２パ
イロット管路１９，２０で操作弁２の第１・第２受圧部
２１，２２に供給して操作弁２を中立位置２ａから第１
位置２ｂ、第２位置２ｃに切換えるものであり、この第
１・第２パイロット管路２１，２２には第１・第２圧力
スイッチ２３，２４が設けられて圧力が発生すると電気
信号をコントローラ２５に出力する。前記油圧ポンプ１
の吐出路１ａには主リリーフ弁２６が設けてある。以上
の説明は図１において左側の油圧ポンプ１のみを示し、
右側の油圧ポンプ１も同様であるから符号を同一として
説明を省略する。[Example] As shown in FIG. 1, a discharge valve 1a of a hydraulic pump 1 is provided with an operating valve 2, and a circuit 4 connecting the operating valve 2 and an actuator 3 is provided with a pressure compensating valve 5. The load pressure of the actuator 3 is introduced into the load pressure introducing passage 6 through the throttle in the operation valve 2. The swash plate 7 of the hydraulic pump 1 is tilted in the direction of large capacity by a small diameter piston 8,
The small diameter pressure chamber 8a of the small diameter piston 8 is tilted by the large diameter piston 9 and is connected to the discharge passage 1a to supply pump discharge pressure. 9a is an LS valve 10 which is a discharge passage 1a and a tank 11.
Is controlled to communicate. The LS valve 10 has a load pressure and a spring 12
Is pushed to the drain position A, and the pump discharge pressure is applied to the supply position B.
Then, the swash plate 7 is tilted so that the pump discharge pressure becomes a pressure slightly higher than the load pressure, for example, 20 kg / cm 2 . An unload valve 13 is provided in the discharge passage 1 a of the hydraulic pump 1, and the unload valve 13
Is pushed to the on-load position 13a by the spring and the load pressure supplied to the first pressure receiving portion 14, and is pushed to the unload position 13b by the pump discharge pressure supplied to the second pressure receiving portion 15, so that the pump discharge pressure and the load pressure are Is the set pressure, for example 30kg / cm
When it becomes 2 or more, it becomes the unload position 13b, and it operates only by individual pump discharge pressure and load pressure of a plurality of hydraulic pumps. The pilot hydraulic valve 16 supplies the discharge pressure oil of the auxiliary pump 18 to the first and second pressure receiving portions 21 and 22 of the operation valve 2 through the first and second pilot conduits 19 and 20 by operating the lever 17. Move the operating valve 2 from the neutral position 2a to the first position.
The position 2b and the second position 2c are switched to. The first and second pilot conduits 21 and 22 are provided with first and second pressure switches 23 and 24, and an electric signal is sent to the controller 25 when pressure is generated. Output to. The hydraulic pump 1
A main relief valve 26 is provided in the discharge passage 1a. The above description shows only the hydraulic pump 1 on the left side in FIG.
Since the hydraulic pump 1 on the right side is also the same, the same reference numerals are used and the description thereof is omitted.
【０００９】前記左側の油圧ポンプ１の吐出路１ａと右
側の油圧ポンプ１の吐出路１ａは第１合分流弁３０で合
流・分流可能となり、前記左側の負荷圧導入路６と右側
の負荷圧導入路６は第２合分流弁３１で合流・分流可能
となり、その第１・第２合分流弁３０，３１はばね力で
合流位置３０ａ，３１ａに押され、受圧部３２，３３に
供給されるパイロット圧油で分流位置３０ｂ，３１ｂに
切換える。前記補助ポンプ１８の吐出圧油は電磁弁３４
で受圧部３２，３３に供給制御され、その電磁弁３４は
ばね力でドレーン位置３４ａに保持され、ソレノイド３
５に通電されると供給位置３４ｂに切換わり、そのソレ
ノイド３５には前記コントローラ２５により通電制御さ
れる。The discharge passage 1a of the left hydraulic pump 1 and the discharge passage 1a of the right hydraulic pump 1 can be joined / split by the first merging / dividing valve 30, and the left load pressure introducing passage 6 and the right load pressure The introduction passage 6 can be merged / divided by the second merge / divide valve 31, and the first and second merge / divide valves 30 and 31 are pushed to the merge positions 30a and 31a by the spring force and supplied to the pressure receiving portions 32 and 33. Switch to the diversion positions 30b and 31b with pilot pressure oil. The pressure oil discharged from the auxiliary pump 18 is a solenoid valve 34.
The solenoid valve 34 is held at the drain position 34a by a spring force, and the solenoid 3 is controlled by the solenoid 3
When the power is supplied to 5, the supply position 34b is switched to, and the solenoid 35 is energized by the controller 25.
【００１０】前記左側の負荷圧導入路６と右側の負荷圧
導入路６は一対のチェック弁３６，３６を有する短絡路
３７で連通し、この短絡路３７に前記主リリーフ弁２６
よりセット圧の低いリリーフ弁３８が設けてあり、前記
左側の油圧ポンプ１の吐出路１ａと右側の油圧ポンプ１
の吐出路１ａは一対のチェック弁３９，３９を有する短
絡路４０で連通し、この短絡路４０にアンロード弁４１
が接続してある。前記リリーフ弁３８にはセット圧可変
シリンダ４２が設けられ、その受圧室４３には電磁弁４
４で補助油圧ポンプ１８の吐出圧油が供給され、その電
磁弁４４はばね力でドレーン位置４４ａに保持され、ソ
レノイド４５に通電されると供給位置４４ｂとなり、そ
のソレノイド４５には切換スイッチ４６でコントローラ
２５に信号を入力した時に通電される。前記アンロード
弁４１はばね力と前記短絡路３７の負荷圧によってオン
ロード位置４１ａに保持され、前記短絡路４０のポンプ
吐出圧でアンロード位置４１ｂとなるもので、このアン
ロード弁４１のセット圧は前記個別のアンロード弁１３
のセット圧よりも低くしてある。つまり、アンロードす
る時のポンプ吐出圧と負荷圧の差圧が低くしてもある。The left-side load pressure introducing passage 6 and the right-side load pressure introducing passage 6 communicate with each other through a short circuit 37 having a pair of check valves 36, 36, and the main relief valve 26 is connected to the short circuit 37.
A relief valve 38 having a lower set pressure is provided, and the discharge passage 1a of the left hydraulic pump 1 and the right hydraulic pump 1 are provided.
The discharge passage 1a of the above is communicated with a short circuit 40 having a pair of check valves 39, 39, and the unload valve 41 is connected to the short circuit 40.
Is connected. The relief valve 38 is provided with a variable set pressure cylinder 42, and the pressure receiving chamber 43 thereof has a solenoid valve 4
4, the pressure oil discharged from the auxiliary hydraulic pump 18 is supplied, the solenoid valve 44 is held at the drain position 44a by the spring force, and when the solenoid 45 is energized, it becomes the supply position 44b, and the solenoid 45 is switched by the changeover switch 46. It is energized when a signal is input to the controller 25. The unload valve 41 is held at the on-load position 41a by the spring force and the load pressure of the short-circuit path 37 and becomes the unload position 41b by the pump discharge pressure of the short-circuit path 40. The pressure is the individual unloading valve 13
It is lower than the set pressure of. That is, the differential pressure between the pump discharge pressure and the load pressure when unloading may be low.
【００１１】次に作動を説明する。 切換スイッチ４６よりコントローラ２５に信号を入力
せずに第１・第２合分流弁３０，３１を分流位置３０
ａ，３１ｂとして左側のアクチュエータ３に圧油を供給
する動作。 左側のレバー１７でパイロット油圧弁１６を操作して第
１パイロット管路１９にパイロット圧油を供給すると操
作弁２の第１受圧部２１にパイロット圧油が供給されて
操作弁２は第１位置２ｂとなり、左側の油圧ポンプ１の
吐出圧油が左側のアクチュエータ３に供給される。この
アクチュエータ３の負荷圧は操作弁２の第１位置２ｂに
設けた絞りを経て負荷圧導入路６に導入される。この負
荷圧導入路６に流入した負荷圧は一方のチェック弁３６
より短絡路３７に流入してリリーフ弁３８の入口側に作
用する。この時、リリーフ弁３８のセット圧可変シリン
ダ４２の受圧室４３に圧油が供給されずセット圧が低く
なっている。これによって、アクチュエータ３の負荷圧
がリリーフ弁３８の低圧セット圧より高くなるとリリー
フ作動して負荷圧が低下し、アンロード弁４１がアンロ
ードしてポンプ吐出圧の一部がタンクに流出してポンプ
吐出圧が制限される。この時のポンプ吐出圧と負荷圧の
差圧はＬＳ弁１０で設定した差圧よりも大きくなる。こ
れと同時にＬＳ弁１０が供給位置Ｂとなって大径受圧室
９ａにポンプ吐出圧が供給されて斜板７は最小斜板位置
となる。Next, the operation will be described. The first and second combined flow dividing valves 30 and 31 are moved to the flow dividing position 30 without inputting a signal from the changeover switch 46 to the controller 25.
Operation of supplying pressure oil to the left actuator 3 as a and 31b. When the pilot hydraulic valve 16 is operated by the lever 17 on the left side to supply the pilot pressure oil to the first pilot conduit 19, the pilot pressure oil is supplied to the first pressure receiving portion 21 of the operation valve 2 and the operation valve 2 is at the first position. 2b, the pressure oil discharged from the left hydraulic pump 1 is supplied to the left actuator 3. The load pressure of the actuator 3 is introduced into the load pressure introducing passage 6 through the throttle provided in the first position 2b of the operation valve 2. The load pressure flowing into the load pressure introducing passage 6 is determined by the check valve 36 on one side.
Further, it flows into the short circuit path 37 and acts on the inlet side of the relief valve 38. At this time, pressure oil is not supplied to the pressure receiving chamber 43 of the set pressure variable cylinder 42 of the relief valve 38, and the set pressure is low. As a result, when the load pressure of the actuator 3 becomes higher than the low pressure set pressure of the relief valve 38, the relief operation is performed to reduce the load pressure, the unload valve 41 is unloaded, and a part of the pump discharge pressure flows out to the tank. Pump discharge pressure is limited. At this time, the differential pressure between the pump discharge pressure and the load pressure becomes larger than the differential pressure set by the LS valve 10. At the same time, the LS valve 10 becomes the supply position B, the pump discharge pressure is supplied to the large diameter pressure receiving chamber 9a, and the swash plate 7 becomes the minimum swash plate position.
【００１２】切換スイッチ４６よりコントローラ２５
に信号を入力して第１・第２合分流弁３０，３１を分流
位置３０ｂ，３１ｂとして左側のアクチュエータ３１に
圧油を供給する動作。 前述のと同一の動作となるが、コントローラ２５より
電磁弁４４のソレノイド４５に通電されて電磁弁４４が
供給位置４４ｂとなり、補助油圧ポンプ１８の吐出圧油
がリリーフ弁３８のセット圧可変シリンダ４２の受圧室
４３に供給され、そのリリーフ弁３８のセット圧が非常
に高圧となる。このために、前述のと同様に負荷圧が
高くなってもリリーフ弁３８はリリーフ作動せず、負荷
圧の上昇につれてポンプ吐出圧も上昇する。ポンプ吐出
圧が主リリーフ弁２６のセット圧以上となると主リリー
フ弁２６がリリーフ作動してポンプ吐出圧が制限され
る。この時のポンプ吐出圧と負荷圧の差圧はＬＳ弁１０
により設定した差圧となり、斜板７は最小斜板角になら
ない。この状態でアクチュエータ３の負荷が減少して負
荷圧が低下するとポンプ吐出圧も低下して主リリーフ弁
２６は閉じるが、この主リリーフ弁２６の応答は斜板７
の応答に比べて非常に速いので、前述のリーフ状態から
少し負荷圧が低くなるとリリーフしていた油が即全量ア
クュエータ３に流れるので、時間遅れがなく掘削力が小
さいという異和感をオペレータに与えることがない。From the changeover switch 46 to the controller 25
Signal is input to the first and second combined flow dividing valves 30 and 31 as the flow dividing positions 30b and 31b to supply pressure oil to the left actuator 31. Although the operation is the same as that described above, the solenoid 45 of the solenoid valve 44 is energized by the controller 25 to move the solenoid valve 44 to the supply position 44b, and the discharge pressure oil of the auxiliary hydraulic pump 18 is set by the set pressure variable cylinder 42 of the relief valve 38. Is supplied to the pressure receiving chamber 43, and the set pressure of the relief valve 38 becomes extremely high. Therefore, similarly to the above, the relief valve 38 does not perform the relief operation even when the load pressure becomes high, and the pump discharge pressure also increases as the load pressure increases. When the pump discharge pressure becomes equal to or higher than the set pressure of the main relief valve 26, the main relief valve 26 is relief operated and the pump discharge pressure is limited. At this time, the differential pressure between the pump discharge pressure and the load pressure is the LS valve 10.
The swash plate 7 does not have the minimum swash plate angle. In this state, when the load on the actuator 3 decreases and the load pressure decreases, the pump discharge pressure also decreases and the main relief valve 26 closes, but the response of the main relief valve 26 is the swash plate 7.
It is very fast compared to the response of the above, so when the load pressure becomes a little lower from the above-mentioned leaf state, the relief oil immediately flows to the actuator 3, so that there is no time delay and the excavation force is small. Never give.
【００１３】合流・分流の動作。 前述のの動作により、第１圧力スイッチ２３が電気信
号をコントローラ２５に入力してコントローラ２５は左
側の操作弁２が第１位置２ｂとなったと判断し、それに
よって合流するかしなかいを予じめ設定したパターンに
基づいて演算し、合流する場合には電磁弁３４のソレノ
イド３５に通電せずにドレーン位置３４ａとし、第１・
第２合分流弁３０，３１を合流位置３０ａ，３１ａとし
て左側と右側の油圧ポンプ１の吐出圧油を合流して左側
のアクチュエータ３２に供給する。分流する場合には電
磁弁３４のソレノイド３５に通電して供給位置３４ｂと
し、補助油圧ポンプ１８の吐出圧油を第１・第２合分流
弁３０，３１の受圧部３２，３３に供給して分流位置３
０ｂ，３１ｂとし、左側の油圧ポンプ１の吐出圧油のみ
を左側のアクチュエータ３に供給する。他方、負荷圧導
入路６の負荷圧はＬＳ弁１０に作用して油圧ポンプ１の
斜板７を傾転しポンプ吐出圧と負荷圧の差圧を設定圧力
とすると共に、その負荷圧は圧力補償弁５に作用して圧
力補償する。左側のレバー１７を前述と反対に操作して
第２パイロット管路２０にパイロット圧油を供給した場
合及び、右側のレバー１７を操作した場合も前述と同様
になる。Merging / splitting operation. By the above-mentioned operation, the first pressure switch 23 inputs the electric signal to the controller 25, and the controller 25 determines that the left operation valve 2 is in the first position 2b, and thereby predicts whether or not to merge. When the calculation is performed based on the set pattern, the solenoid 35 of the solenoid valve 34 is not energized and the drain position 34a is set to the first position.
The second merging / dividing valves 30 and 31 are used as merging positions 30a and 31a, and the pressure oil discharged from the left and right hydraulic pumps 1 is merged and supplied to the left actuator 32. When diverting, the solenoid 35 of the solenoid valve 34 is energized to the supply position 34b, and the pressure oil discharged from the auxiliary hydraulic pump 18 is supplied to the pressure receiving portions 32 and 33 of the first and second combined flow dividing valves 30 and 31. Dividing position 3
0b and 31b, only the pressure oil discharged from the left hydraulic pump 1 is supplied to the left actuator 3. On the other hand, the load pressure in the load pressure introduction path 6 acts on the LS valve 10 to tilt the swash plate 7 of the hydraulic pump 1 to set the differential pressure between the pump discharge pressure and the load pressure as the set pressure, and the load pressure is the pressure. It acts on the compensating valve 5 to perform pressure compensation. The same applies to the case where the left lever 17 is operated in the opposite direction to supply pilot pressure oil to the second pilot conduit 20, and the case where the right lever 17 is operated.
【００１４】次に合流時のアンロード弁４１のアンロー
ド動作（油圧ホンプの最高ポンプ吐出圧の制限動作）を
説明する。前述の状態で左側のアクチュエータ３がスト
ロークエンドとなった時、又はアクチュエータ３の負荷
が非常に大きく、負荷圧が非常に高い時には、その負荷
圧はチェック弁３６より短絡路３７に流入して低圧セッ
トのリリーフ弁３８よりリリーフする。左右側の油圧ポ
ンプ１，１のポンプ吐出圧油はチェック弁３９より短絡
路４０に流入してアンロード弁４１の入口側に流入する
と同時にアンロード弁４１に作用する。これにより、ア
ンロード弁４１に作用する負荷圧がポンプ吐出圧よりも
低下してアンロード弁４１がアンロード位置４１ｂとな
って左右側の油圧ポンプ１の吐出圧の一部がアンロード
する。Next, the unloading operation of the unloading valve 41 at the time of merging (the operation of limiting the maximum pump discharge pressure of the hydraulic pump) will be described. When the left actuator 3 reaches the stroke end in the above-mentioned state, or when the load on the actuator 3 is very large and the load pressure is very high, the load pressure flows from the check valve 36 into the short-circuit path 37 and is low pressure. Relief from the relief valve 38 of the set. The pump discharge pressure oil of the left and right hydraulic pumps 1, 1 flows into the short-circuit passage 40 from the check valve 39, flows into the inlet side of the unload valve 41, and simultaneously acts on the unload valve 41. As a result, the load pressure acting on the unload valve 41 becomes lower than the pump discharge pressure, and the unload valve 41 becomes the unload position 41b, so that part of the discharge pressure of the left and right hydraulic pumps 1 is unloaded.
【００１５】次に分流時のアンロード弁４１のアンロー
ド動作（油圧ポンプの最高ポンプ吐出圧の制限動作）を
説明する。左側の油圧ポンプ１の吐出路１ａと右側の油
圧ポンプ１の吐出路１ａとが分離すると同時に左側の負
荷圧導入路６と右側の負荷圧導入路６が分離するので、
前述の左側のアクチュエータ３の負荷圧が非常に高くな
ると、その負荷圧は左側のチェック弁３６より短絡路３
７に流入し右側のチェック弁３６で右側の負荷圧導入路
６に流れることを阻止され、その負荷圧は前述と同様に
リリーフ弁３８よりリリーフする。左側の油圧ポンプ１
の吐出圧は左側のチェック弁３９より短絡路４０に流入
して右側のチェック弁３９で右側の油圧ポンプ１の吐出
路１ａに流れることを阻止され、そのポンプ吐出圧はア
ンロード４１の入口側に作用する。これにより合流時と
同様にしてアンロード弁４１がアンロード位置４１ｂと
なってポンプ吐出圧の一部をアンロードする。以上の動
作において、右側の操作弁２が中立位置２ａであると右
側の負荷圧導入路６は操作弁２の中立位置２ａを経てタ
ンクに接続されるから、その負荷圧はほぼ０ｋｇ／ｃｍ
2 であり、右側のアンロード弁１３の第１受圧部１４に
作用する負荷圧がほぼ０ｋｇ／ｃｍ2 となってそのアン
ロード弁１３は第２受圧部１５に作用する低圧のポンプ
吐出圧でアンロード位置１３ｂとなり、右側の油圧ポン
プ１のポンプ吐出圧はごく低圧となる。Next, the unloading operation of the unloading valve 41 at the time of branching (the operation of limiting the maximum pump discharge pressure of the hydraulic pump) will be described. Since the discharge passage 1a of the left hydraulic pump 1 and the discharge passage 1a of the right hydraulic pump 1 are separated at the same time, the left load pressure introducing passage 6 and the right load pressure introducing passage 6 are separated,
When the load pressure of the actuator 3 on the left side becomes extremely high, the load pressure is applied to the short circuit 3 from the check valve 36 on the left side.
7 and the check valve 36 on the right side is prevented from flowing to the load pressure introducing path 6 on the right side, and the load pressure is relieved by the relief valve 38 as described above. Left hydraulic pump 1
Is prevented from flowing into the short-circuit path 40 from the left check valve 39 and flowing to the discharge path 1a of the right hydraulic pump 1 by the right check valve 39, and the pump discharge pressure is the inlet side of the unload 41. Act on. As a result, the unload valve 41 becomes the unload position 41b in the same manner as when merging, and a part of the pump discharge pressure is unloaded. In the above operation, when the right operation valve 2 is in the neutral position 2a, the right load pressure introducing passage 6 is connected to the tank via the neutral position 2a of the operation valve 2, so that the load pressure is almost 0 kg / cm.
2 and the load pressure acting on the first pressure receiving portion 14 of the unload valve 13 on the right side becomes almost 0 kg / cm 2, and the unload valve 13 is a low pump discharge pressure acting on the second pressure receiving portion 15. The unload position 13b is reached, and the pump discharge pressure of the right hydraulic pump 1 becomes extremely low.
【００１６】以上のように合流時でも分流時でも負荷圧
は１つのリリーフ弁３８よりリリーフするから、アンロ
ード弁４１がアンロードする差圧となるリリーフ流量が
リリーフ弁３８のオーバライド特性により決定され、そ
の際の負荷圧が同一となり、最高ポンプ吐出圧を合流時
と分流時で同一にできる。また、図１においてリリーフ
弁３８の流入側とタンクを小径のオリフィス４７で連通
してあるが、これは操作弁２を中立位置２ａとした時に
一対のチェック弁３６，３６で遮断されている短絡路３
７の負荷圧をすみやかにタンクに流出するためである。
なお、以上の実施例は合分流弁を用いたがこれに限るも
のではない。As described above, since the load pressure is relieved from one relief valve 38 at the time of merging or branching, the relief flow rate which becomes the differential pressure for unloading the unload valve 41 is determined by the override characteristic of the relief valve 38. At that time, the load pressure becomes the same, and the maximum pump discharge pressure can be made the same at the time of merging and at the time of diversion. Further, in FIG. 1, the inflow side of the relief valve 38 and the tank are communicated with each other by a small diameter orifice 47. This is a short circuit which is cut off by a pair of check valves 36, 36 when the operation valve 2 is set to the neutral position 2a. Road 3
This is because the load pressure of 7 immediately flows out to the tank.
It should be noted that although the above embodiment uses the merging / branching valve, the invention is not limited to this.
【００１７】[0017]
【発明の効果】リリーフ弁３８のセット圧を低圧とすれ
ば負荷圧が高い時に油圧ポンプ１の斜板７を最小斜板角
としてリーフロスを低減できるし、リリーフ弁３８のセ
ット圧を高圧とすれば負荷圧が高い時に主リリーフ弁２
６がリリーフ作動してその負荷圧低下時に必要流量を時
間遅れなくアクチュエータに供給できる。By reducing the set pressure of the relief valve 38, the swash plate 7 of the hydraulic pump 1 can be set to the minimum swash plate angle to reduce leaf loss when the load pressure is high, and the set pressure of the relief valve 38 can be set to a high pressure. For example, when the load pressure is high, the main relief valve 2
The relief operation of 6 can supply the required flow rate to the actuator without a time delay when the load pressure decreases.
【図１】本発明の実施例を示す油圧回路図である。FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention.
１…油圧ポンプ、１ａ…吐出路、２…操作弁、３…アク
チュエータ、５…圧力補償弁、６…負荷圧導入路、１０
…ＬＳ弁、２５…コントローラ、２６…主リリーフ弁、
３８…リリーフ弁、４２…セット圧可変シリンダ、４３
…受圧室、４４…電磁弁、４５…ソレノイド、４６…切
換スイッチ。DESCRIPTION OF SYMBOLS 1 ... Hydraulic pump, 1a ... Discharge path, 2 ... Operation valve, 3 ... Actuator, 5 ... Pressure compensation valve, 6 ... Load pressure introduction path, 10
... LS valve, 25 ... Controller, 26 ... Main relief valve,
38 ... Relief valve, 42 ... Variable set pressure cylinder, 43
... pressure receiving chamber, 44 ... solenoid valve, 45 ... solenoid, 46 ... changeover switch.
─────────────────────────────────────────────────────
─────────────────────────────────────────────────── ───
【手続補正書】[Procedure amendment]
【提出日】平成５年１月６日[Submission date] January 6, 1993
【手続補正１】[Procedure Amendment 1]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】発明の名称[Name of item to be amended] Title of invention
【補正方法】変更[Correction method] Change
【補正内容】[Correction content]
【発明の名称】 圧力補償弁を有する油圧回路Patent application title: Hydraulic circuit having pressure compensation valve
Claims (2)
有する複数の操作弁２と、複数の操作弁２の負荷圧を検
出して圧力補償弁５にフィードバックする複数の負荷圧
導入路６を有する圧力補償弁を有する油圧回路におい
て、 前記油圧ポンプ１の斜板７を傾転制御するＬＳ弁１０
と、前記負荷圧導入路６に設けたセット圧可変のリリー
フ弁３８と、前記油圧ポンプ１の吐出路１ａに設けられ
前記リリーフ弁３８の低圧セット圧より高圧セット圧で
ある主リリーフ弁２６と、前記リリーフ弁３８のセット
圧を可変とする手段を設けて成る圧力補償弁を有する油
圧回路。1. A plurality of hydraulic pumps 1, a plurality of operating valves 2 having pressure compensating valves 5, and a plurality of load pressure introducing paths for detecting load pressures of the plurality of operating valves 2 and feeding back to the pressure compensating valves 5. In a hydraulic circuit having a pressure compensating valve having 6, an LS valve 10 for tilt-controlling a swash plate 7 of the hydraulic pump 1 is provided.
And a relief valve 38 having a variable set pressure provided in the load pressure introduction passage 6, and a main relief valve 26 provided in the discharge passage 1a of the hydraulic pump 1 and having a higher set pressure than the low set pressure of the relief valve 38. , A hydraulic circuit having a pressure compensating valve provided with means for varying the set pressure of the relief valve 38.
室４３に圧油を供給する電磁弁４４と、この電磁弁４４
のソレノイド４５に通電するコントローラ２５と、その
コントローラ２５に信号を出力する切換スイッチ４６よ
りリリーフ弁３８のセット圧可変手段とした請求項１記
載の圧力補償弁を有する油圧回路。2. A set pressure variable cylinder 42, a solenoid valve 44 for supplying pressure oil to the pressure receiving chamber 43, and this solenoid valve 44.
2. A hydraulic circuit having a pressure compensating valve according to claim 1, wherein the controller 25 energizes the solenoid 45 and the changeover switch 46 for outputting a signal to the controller 25 is used as a set pressure varying means for the relief valve 38.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4102548A JPH05272505A (en) | 1992-03-30 | 1992-03-30 | Hydraulic circuit having pressure-compensation valve |
| US08/244,439 US5481872A (en) | 1991-11-25 | 1992-11-25 | Hydraulic circuit for operating plural actuators and its pressure compensating valve and maximum load pressure detector |
| PCT/JP1992/001540 WO1993011364A1 (en) | 1991-11-25 | 1992-11-25 | Hydraulic circuit for operating plural actuators and its pressure compensating valve and maximum load pressure detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4102548A JPH05272505A (en) | 1992-03-30 | 1992-03-30 | Hydraulic circuit having pressure-compensation valve |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05272505A true JPH05272505A (en) | 1993-10-19 |
Family
ID=14330304
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4102548A Pending JPH05272505A (en) | 1991-11-25 | 1992-03-30 | Hydraulic circuit having pressure-compensation valve |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05272505A (en) |
-
1992
- 1992-03-30 JP JP4102548A patent/JPH05272505A/en active Pending
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