JPH05272504A - Hydraulic circuit - Google Patents
Hydraulic circuitInfo
- Publication number
- JPH05272504A JPH05272504A JP4102547A JP10254792A JPH05272504A JP H05272504 A JPH05272504 A JP H05272504A JP 4102547 A JP4102547 A JP 4102547A JP 10254792 A JP10254792 A JP 10254792A JP H05272504 A JPH05272504 A JP H05272504A
- Authority
- JP
- Japan
- Prior art keywords
- pressure
- valve
- load
- hydraulic
- 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.)
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Landscapes
- Operation Control Of Excavators (AREA)
- 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 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】図１に示すように、第１ポンプ１と第２
ポンプ２の吐出路１ａ，２ａを接続し、その吐出路１
ａ，１ｂに複数のクローズドセンタ型式の操作弁３を配
設し、その操作弁３とアクチュエータの接続回路４に圧
力補償弁５を設け、各アクチュエータの負荷圧における
最高圧をシャトル弁６で検出し、その負荷圧を各圧力補
償弁５のバネ室５ａ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 shown in FIG. 1, a first pump 1 and a second pump 1
The discharge paths 1a and 2a of the pump 2 are connected to each other, and the discharge path 1
A plurality of closed center type operation valves 3 are provided in a and 1b, a pressure compensation valve 5 is provided in a connection circuit 4 between the operation valve 3 and the actuator, and the maximum pressure of the load pressure of each actuator is detected by the shuttle valve 6. However, there is known a hydraulic circuit in which the load pressure is supplied to the spring chamber 5a of each pressure compensating valve 5 to obtain 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３
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５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３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, a plurality of operating valves 3
The pressure compensating valve 5 is set by the maximum pressure among the load pressures of the plurality of actuators when the actuators are simultaneously operated, and even if the load pressures of the plurality of actuators are different, the flow rates can be distributed to the plurality of actuators by the opening area ratio of the operation valve 3.
【０００４】かかる油圧回路であると、複数のアクチュ
エータを同時作動する場合に圧力補償弁は高い方の負荷
圧でセットされポンプ吐出圧力はそのセット圧より若干
高い高圧となるので、アクチュエータの負荷圧の差が大
きい場合には負荷圧の小さいアクチュエータ側の圧力補
償弁における圧力損失が大となり、第１・第２ポンプ
１，２を駆動する原動機の損失馬力が大となると共に、
作動油の温度が高くなって作動油の劣化を早めることに
なる。例えば、パワーショベルのブームシリンダと旋回
モータに圧油を供給してブーム下降、上部車体旋回する
場合に、ブームは自重降下するから負荷圧は低圧である
が、旋回モータは上部車体を起動・加速するため負荷圧
が高圧となり、その時のポンプ吐出圧はセット圧より若
干高い高圧となるので、ブームシリンダ側の圧力補償弁
では高圧−低圧の分が圧力損失となり、前述のように負
荷圧の差が大であるから圧力損失が大となってしまう。
このことは、アームシリンダでアームを上昇させバケッ
トシリンダでバケットをダンプして土砂を排出する場合
に、アームシリンダの負荷圧が高く、バケットシリンダ
の負荷圧が低くなるから同様である。In such a hydraulic circuit, when a plurality of actuators are simultaneously operated, the pressure compensating valve is set at a higher load pressure and the pump discharge pressure becomes a pressure slightly higher than the set pressure. When the difference between the two is large, the pressure loss in the pressure compensating valve on the actuator side where the load pressure is small becomes large, and the loss horsepower of the prime mover driving the first and second pumps 1 and 2 becomes large, and
The temperature of the hydraulic oil rises, which accelerates the deterioration of the hydraulic oil. For example, when supplying pressure oil to the boom cylinder and swing motor of a power shovel to lower the boom and swing the upper body, the load pressure is low because the boom descends by its own weight, but the swing motor starts and accelerates the upper body. Therefore, the load pressure becomes high, and the pump discharge pressure at that time is slightly higher than the set pressure.Therefore, at the boom cylinder side pressure compensating valve, the high pressure-low pressure component causes a pressure loss. Is large, the pressure loss will be large.
This is the same as when the arm cylinder raises the arm and the bucket cylinder dumps the bucket to discharge the earth and sand, the load pressure of the arm cylinder is high and the load pressure of the bucket cylinder is low.
【０００５】このことを解消する油圧回路として特開平
号公報に示すものが知られている。すなわち、図２に
示すように第１ポンプ１の吐出路１ａと第２ポンプ２の
吐出路２ａを合分流弁１６で接続し、第１ポンプ１の吐
出路１ａに接続した操作弁３の圧力補償弁５の負荷圧導
入路１７と第２ポンプ２の吐出路２ａに接続した操作弁
３の圧力補償弁５の負荷圧導入路１８を合分流弁１９で
接続した油圧回路であり、これによって、合分流弁１
６，１９によって各吐出路１ａ，１ｂ及び各負荷圧導入
路１７，１８をそれぞれ独立させ、一方の吐出路１ａに
接続したアクチュエータ１０，１１，１２と他方の吐出
路２ａに接続したアクチュエータ１３，１４，１５を同
時操作した時に、それぞれのアクチュエータの負荷圧で
圧力補償弁をセットして、圧力損失を低減できるように
できる。As a hydraulic circuit for solving this problem, there is known a hydraulic circuit disclosed in Japanese Patent Laid-Open Publication No. That is, as shown in FIG. 2, the discharge passage 1a of the first pump 1 and the discharge passage 2a of the second pump 2 are connected by the merging / dividing valve 16, and the pressure of the operation valve 3 connected to the discharge passage 1a of the first pump 1 is increased. This is a hydraulic circuit in which the load pressure introducing passage 17 of the compensating valve 5 and the load pressure introducing passage 18 of the pressure compensating valve 5 of the operation valve 3 connected to the discharge passage 2a of the second pump 2 are connected by a diverging valve 19. , Junction valve 1
The respective discharge passages 1a, 1b and the respective load pressure introduction passages 17, 18 are made independent by 6, 19 and the actuators 10, 11, 12 connected to one discharge passage 1a and the actuator 13, connected to the other discharge passage 2a, When 14 and 15 are operated at the same time, the pressure compensation valve can be set by the load pressure of each actuator to reduce the pressure loss.
【０００６】[0006]
【発明が解決しようとする課題】かかる油圧回路におい
ては、油圧ポンプ、回路、アクチュエータなどの保護の
ために油圧ポンプの最高ポンプ吐出圧を制限する必要が
ある。しかしながら、かかる油圧回路においてはポンプ
吐出圧Ｐ1 を負荷圧ＰLSに基づいてその負荷圧より若干
高い圧力に制御しているので、ただ単に油圧ポンプの吐
出路にリリーフ弁を設けたのでは前述の油圧回路として
の機能を発揮できないことがある。これを解消するため
に例えば図３に示すように、第１・第２油圧ポンプ１，
２の吐出路１ａ，２ａにアンロード弁２０をそれぞれ設
け、各負荷圧導入路１７，１８にリリーフ弁２１をそれ
ぞれ設け、前記アンロード弁２０を負荷圧ＰLSよりもポ
ンプ吐出圧Ｐ1 が前述の設定圧力以上高くなった時にア
ンロードする構成とする油圧回路が考えられる。In such a hydraulic circuit, it is necessary to limit the maximum pump discharge pressure of the hydraulic pump in order to protect the hydraulic pump, the circuit, the actuator and the like. However, in such a hydraulic circuit, the pump discharge pressure P 1 is controlled to a pressure slightly higher than the load pressure P LS on the basis of the load pressure P LS, and therefore, the relief valve is simply provided in the discharge passage of the hydraulic pump as described above. May not be able to exert its function as a hydraulic circuit. In order to eliminate this, for example, as shown in FIG. 3, the first and second hydraulic pumps 1,
The unloading valve 20 is provided in each of the two discharge passages 1a and 2a, the relief valve 21 is provided in each of the load pressure introducing passages 17 and 18, and the pump discharge pressure P 1 is set to be higher than the load pressure P LS. A hydraulic circuit configured to unload when it becomes higher than the set pressure described above is conceivable.
【０００７】かかる油圧回路であれば、負荷圧導入路１
７，１８の負荷圧ＰLSがリリーフ弁２１の設定圧力以上
となるとリリーフ弁２１がリリーフ作動して負荷圧ＰLS
の一部がタンクに流出し、その負荷圧ＰLSが低下してポ
ンプ吐出圧Ｐ1 との差圧が前記設定圧力以上となるとア
ンロード弁２０がアンロードしてポンプ吐出圧Ｐ1 の一
部がタンクに流出して最高ポンプ吐出圧を制限できる。With such a hydraulic circuit, the load pressure introducing path 1
When the load pressure P LS of Nos. 7 and 18 becomes equal to or higher than the set pressure of the relief valve 21, the relief valve 21 operates to perform the relief pressure P LS.
Part of the pump discharges to the tank, the load pressure P LS decreases, and when the pressure difference from the pump discharge pressure P 1 becomes equal to or higher than the set pressure, the unload valve 20 unloads the pump discharge pressure P 1 The part can flow out to the tank to limit the maximum pump discharge pressure.
【０００８】図３に示す油圧回路であると第１・第２油
圧ポンプ１，２の吐出圧油を合流してアクチュエータに
供給する合流時と第１又は第２油圧ポンプ１，２の吐出
圧油を単独にアクチュエータに供給する分流時で油圧ポ
ンプの最高ポンプ吐出圧が異なってしまう。In the hydraulic circuit shown in FIG. 3, when the discharge pressure oil of the first and second hydraulic pumps 1 and 2 merges and is supplied to the actuator, the discharge pressure of the first or second hydraulic pump 1 or 2 The maximum pump discharge pressure of the hydraulic pump will differ when the oil is split into the actuators.
【０００９】すなわち、合流時には第１・第２負荷圧導
入路１７，１８が接続するので、負荷圧ＰLSがリリーフ
弁２１の設定圧力以上となると２つのリリーフ弁２１，
２１から負荷圧の一部がタンクに流出し、分流時には第
１・第２負荷圧導入路１７，１８が分離するので、負荷
圧がリリーフ弁２１の設定圧力以上となると１つのリリ
ーフ弁２１のみから負荷圧の一部がタンクに流出するの
で、その負荷圧に対するリリーフ流量は図４に示すよう
になり、アンロード弁２１がアンロードする差圧（ポン
プ吐出圧−負荷圧）となる際の負荷圧が異なる。例え
ば、合流時には２つのリリーフ弁２１からリリーフする
からリリーフ流量が図４のａに示すように多く低い負荷
圧ＰLS1 で所定のリリーフ流量となるが、分流時にはリ
リーフ流量がそのリリーフ弁２１のオーバライド特性
（図４のｂ）によって決定されるから前述のリリーフ流
量となる時の負荷圧ＰLS2 が高圧となる。That is, since the first and second load pressure introduction passages 17 and 18 are connected at the time of merging, when the load pressure P LS becomes equal to or higher than the set pressure of the relief valve 21, the two relief valves 21 and
A part of the load pressure flows from the tank 21 to the tank, and the first and second load pressure introducing passages 17 and 18 are separated at the time of branching. Therefore, when the load pressure exceeds the set pressure of the relief valve 21, only one relief valve 21 is provided. Since a part of the load pressure flows out of the tank to the tank, the relief flow rate with respect to the load pressure is as shown in FIG. 4, and when the unloading valve 21 has a differential pressure (pump discharge pressure-load pressure). Load pressure is different. For example, since two relief valves 21 are relieved at the time of merging, the relief flow rate becomes large at a low load pressure P LS1 as shown in FIG. Since it is determined by the characteristics (b in FIG. 4), the load pressure P LS2 when the relief flow rate is the above becomes high pressure.
【００１０】これにより、合流時の油圧ポンプの最高ポ
ンプ吐出圧はＰLS1 ＋差圧となり、分流時の油圧ポンプ
の最高ポンプの吐出圧はＰLS2 ＋差圧となってＰLS2 −
ＰLS1 だけ分流時の最高ポンプ吐出圧が高くなる。As a result, the maximum pump discharge pressure of the hydraulic pump at the time of merging becomes P LS1 + differential pressure, and the maximum pump discharge pressure of the hydraulic pump at the time of shunt becomes P LS2 + differential pressure, P LS2 −
The maximum pump discharge pressure when splitting is increased by P LS1 .
【００１１】このために、油圧回路設計時の定格圧力を
合流時の最高ポンプ吐出圧とすると分流時に定格圧力を
こえることになって油圧ポンプ、回路、アクチュエータ
等の油圧機器の寿命に影響を及ぼし、前述の定格圧力を
分流時の最高ポンプ吐出圧とすると合流時に定格圧力に
達しないためアクチュエータの能力が低下する。For this reason, if the rated pressure in the hydraulic circuit design is taken as the maximum pump discharge pressure at the time of merging, the rated pressure will be exceeded during shunting, which will affect the life of hydraulic equipment such as hydraulic pumps, circuits, and actuators. If the rated pressure described above is used as the maximum pump discharge pressure during diverting, the rated pressure will not be reached at the time of merging, and the capacity of the actuator will decrease.
【００１２】そこで、本発明は前述の課題を解決できる
ようにした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 which can solve the above-mentioned problems.
【００１３】[0013]
【課題を解決するための手段】複数の油圧ポンプ３０
と、圧力補償弁３４を有する複数の操作弁３１と、複数
の操作弁３１の負荷圧を検出して圧力補償弁３４にフィ
ードバックする複数の負荷圧導入路３５と、複数の油圧
ポンプ３０の吐出路３０ａを合流、分離させる第１合分
流弁５５と、複数の負荷圧導入路３５を合流、分離させ
る第２合分流弁５６を有する油圧回路において、前記複
数の油圧ポンプ３０ａ吐出路３０ａをチェック弁６４を
介して連通する第１の短絡路６５と、前記複数の負荷圧
導入路３５をチェック弁６１を介して連通する第２の短
絡路６２と、この第２の短絡路６２に設けたリリーフ弁
６３と、前記第１の短絡路６５に設けられてそのポンプ
吐出圧と前記第２の短絡路６２の負荷圧の差圧でアンロ
ードするアンロード弁６６を設けて成る油圧回路。Means for Solving the Problems A plurality of hydraulic pumps 30
A plurality of operating valves 31 having pressure compensating valves 34, a plurality of load pressure introducing passages 35 for detecting load pressures of the plurality of operating valves 31 and feeding back to the pressure compensating valves 34, and discharges of a plurality of hydraulic pumps 30. In a hydraulic circuit having a first merging / branching valve 55 for merging and separating the passage 30a and a second merging / branching valve 56 for merging and separating the plurality of load pressure introduction passages 35, the plurality of hydraulic pumps 30a discharge passages 30a are checked. The first short circuit path 65 communicating with the valve 64, the second short circuit path 62 communicating the plurality of load pressure introducing paths 35 with the check valve 61, and the second short circuit path 62 are provided. A hydraulic circuit comprising a relief valve 63 and an unload valve 66 provided in the first short circuit 65 for unloading by a differential pressure between the pump discharge pressure and the load pressure of the second short circuit 62.
【００１４】[0014]
【作 用】合流時でも分流時でも１つのリリーフ弁６
３がリリーフし、それによって１つのアンロード弁６６
がアンロードして最高ポンプ吐出圧を制限しているか
ら、最高ポンプ吐出圧を合流時と分流時で同一にでき
る。[Operation] One relief valve 6 for both merging and branching
3 is relieved, which results in one unloading valve 66
Limits the maximum pump discharge pressure by unloading, so that the maximum pump discharge pressure can be made the same when merging and branching.
【００１５】[0015]
【実 施 例】図５に示すように、油圧ポンプ３０の吐
出路３０ａには操作弁３１が設けられ、この操作弁３１
とアクチュエータ３２を接続する回路３３に圧力補償弁
３４が設けてあり、そのアクチュエータ３２の負荷圧は
操作弁３０内の絞りを通して負荷圧導入路３５に導入さ
れる。前記油圧ポンプ３０の斜板３６は小径ピストン３
７で容量大方向に傾転され、大径ピストン３８で容量小
方向に傾転されると共に、その小径ピストン３７の小径
受圧室３７ａは前記吐出路３０ａに接続してポンプ吐出
圧が供給され、前記大径ピストン３８の大径受圧室３８
ａはＬＳ弁３９で吐出路３０ａとタンク４０に連通制御
される。前記ＬＳ弁３９は負荷圧とばね４１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３６を傾
転動作する。前記油圧ポンプ３０の吐出路３０ａにはア
ンロード弁４２が設けられ、このアンロード弁４２はば
ねと第１受圧部４３に供給される負荷圧でオンロード位
置４２ａに押され、第２受圧部４４に供給されるポンプ
吐出圧でアンロード位置４２ｂ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／ｃｍ2以
上となるとアンロード位置４２ｂ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４５はレバー４６を操作す
ることで補助ポンプ４７の吐出圧油を第１・第２パイロ
ット管路４８，４９で操作弁３１の第１・第２受圧部５
０，５１に供給して操作弁３１を中立位置３１ａから第
１位置３１ｂ、第２位置３１ｃに切換えるものであり、
この第１・第２パイロット管路４８，４９には第１・第
２圧力スイッチ５２，５３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５４に出力する。以上の説明
は図５において左側の油圧ポンプ３０のみを示し、右側
の油圧ポンプ３０も同様であるから符号を同一として説
明を省略する。[Examples] As shown in FIG. 5, an operating valve 31 is provided in the discharge passage 30a of the hydraulic pump 30.
A pressure compensating valve 34 is provided in a circuit 33 connecting the actuator 32 and the actuator 32, and the load pressure of the actuator 32 is introduced into the load pressure introducing passage 35 through the throttle in the operation valve 30. The swash plate 36 of the hydraulic pump 30 is a small-diameter piston 3
7, the large-diameter piston 38 tilts in the large-capacity direction, and the large-diameter piston 38 tilts in the small-capacity direction. The small-diameter pressure receiving chamber 37a of the small-diameter piston 37 is connected to the discharge passage 30a to supply pump discharge pressure. Large-diameter pressure receiving chamber 38 of the large-diameter piston 38
The a is controlled by the LS valve 39 so as to communicate with the discharge passage 30a and the tank 40. The LS valve 39 is pushed to the drain position A by the load pressure and the spring 41, and is pushed to the supply position B by the pump discharge pressure, so that the pump discharge pressure is slightly higher than the load pressure, for example, 20 kg / cm 2. The swash plate 36 is tilted so that An unloading valve 42 is provided in the discharge passage 30a of the hydraulic pump 30, and the unloading valve 42 is pushed to the on-load position 42a by the load pressure supplied to the spring and the first pressure receiving portion 43, and the second pressure receiving portion 42a. It is pushed to the unload position 42b by the pump discharge pressure supplied to the pump 44, and becomes the unload position 42b when the pressure difference between the pump discharge pressure and the load pressure reaches a set pressure, for example, 30 kg / cm 2 or more. Operates only on the individual pump discharge and load pressures of the pump. The pilot hydraulic valve 45 operates the lever 46 so that the pressure oil discharged from the auxiliary pump 47 is transferred to the first and second pressure receiving portions 5 of the operation valve 31 through the first and second pilot conduits 48 and 49.
0, 51 to switch the operating valve 31 from the neutral position 31a to the first position 31b and the second position 31c.
First and second pressure switches 52 and 53 are provided in the first and second pilot lines 48 and 49, and when pressure is generated, an electric signal is output to the controller 54. In the above description, only the hydraulic pump 30 on the left side in FIG. 5 is shown, and the hydraulic pump 30 on the right side is the same, so the same reference numerals are used and the description thereof is omitted.
【００１６】前記左側の油圧ポンプ３０の吐出路３０ａ
と右側の油圧ポンプ３０の吐出路３０ａは第１合分流弁
５５で合流・分流可能となり、前記左側の負荷圧導入路
３５と右側の負荷圧導入路３５は第２合分流弁５６で合
流・分流可能となり、その第１・第２合分流弁５５，５
６はばね力で合流位置５５ａ，５６ａに押され、受圧部
５７，５８に供給されるパイロット圧油で分流位置５５
ｂ，５６ｂに切換える。前記補助ポンプ４７の吐出圧油
は電磁弁５９で受圧部５７，５８に供給制御され、その
電磁弁５９はばね力でドレーン位置５９ａに保持され、
ソレノイド６０に通電されると供給位置５９ｂに切換わ
り、そのソレノイド６０には前記コントローラ５４によ
り通電制御される。Discharge passage 30a of the left hydraulic pump 30
And the discharge passage 30a of the hydraulic pump 30 on the right side can be joined / split by the first joining / dividing valve 55, and the load pressure introducing passage 35 on the left side and the load pressure introducing passage 35 on the right side are joined by the second joining / dividing valve 56. Flow splitting becomes possible, and the first and second combined split valves 55, 5
6 is pushed by the spring force to the merging positions 55a and 56a, and the pilot pressure oil supplied to the pressure receiving portions 57 and 58 is used to divide the diverging position 55.
Switch to b, 56b. The pressure oil discharged from the auxiliary pump 47 is controlled to be supplied to the pressure receiving portions 57 and 58 by an electromagnetic valve 59, and the electromagnetic valve 59 is held at the drain position 59a by a spring force.
When the solenoid 60 is energized, it is switched to the supply position 59b, and the solenoid 60 is energized by the controller 54.
【００１７】前記左側の負荷圧導入路３５と右側の負荷
圧導入路３５は一対のチェック弁６１，６１を有する短
絡路６２で連通し、この短絡路６２にリリーフ弁６３が
設けてあり、前記左側の油圧ポンプ３０の吐出路３０ａ
と右側の油圧ポンプ３０の吐出路３０ａは一対のチェッ
ク弁６４，６４を有する短絡路６５で連通し、この短絡
路６５にアンロード弁６６が接続してある。このアンロ
ード弁６６はばね力と前記短絡路６２の負荷圧によって
オンロード位置６６ａに保持され、前記短絡路６５のポ
ンプ吐出圧でアンロード位置６６ｂとなるもので、この
アンロード弁６６のセット圧は前記個別のアンロード弁
４２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 35 and the right-side load pressure introducing passage 35 communicate with each other through a short circuit 62 having a pair of check valves 61, 61, and a relief valve 63 is provided in the short circuit 62. Discharge passage 30a of the left hydraulic pump 30
And the discharge passage 30a of the hydraulic pump 30 on the right side are communicated with each other by a short circuit 65 having a pair of check valves 64, 64, and an unload valve 66 is connected to the short circuit 65. The unload valve 66 is held at the on-load position 66a by the spring force and the load pressure of the short-circuit path 62 and becomes the unload position 66b by the pump discharge pressure of the short-circuit path 65. The pressure is lower than the set pressure of the individual unload valves 42. That is, the differential pressure between the pump discharge pressure and the load pressure when unloading may be low.
【００１８】次に作動を説明する。左側の操作レバー４
６でパイロット油圧弁４５を操作して第１パイロット管
路４８にパイロット圧油を供給すると操作弁３１の第１
受圧部５０にパイロット圧油が供給されて操作弁３１は
第１位置３１ｂとなり、左側の油圧ポンプ３０の吐出圧
油が左側のアクチュエータ３２に供給される。このアク
チュエータ３２の負荷圧は操作弁３１の第１位置３１ｂ
に設けた絞りを経て負荷圧導入路３５に導入される。こ
れにより、第１圧力スイッチ５２が電気信号をコントロ
ーラ５４に入力してコントローラ５４は左側の操作弁３
１が第１位置３１ｂとなったと判断し、それによって合
流するかしないかを予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５９のソレノイド６０に
操作せずにドレーン位置５９ａとし、第１・第２合分流
弁５５，５６を合流位置５５ａ，５６ａとして左側と右
側の油圧ポンプ３０の吐出圧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５９の
ソレノイド６０に通電して供給位置５９ｂとし、補助油
圧ポンプ４７の吐出圧油を第１・第２合分流弁５５，５
６の受圧部５７，５８に供給して分流位置５５ｂ，５６
ｂとし、左側の油圧ポンプ３０の吐出圧油のみを左側の
アクチュエータ３２に供給する。他方、負荷圧導入路３
５の負荷圧はＬＳ弁３９に作用して油圧ポンプ３０の斜
板３６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３４に作用して
圧力補償する。左側の操作レバー４６を前述と反対に操
作して第２パイロット管路４９にパイロット圧油を供給
した場合及び、右側の操作レバー４６を操作した場合も
前述と同様になる。Next, the operation will be described. Left operating lever 4
6 operates the pilot hydraulic valve 45 to supply pilot pressure oil to the first pilot line 48, and the first operation of the operation valve 31
The pilot pressure oil is supplied to the pressure receiving portion 50, the operation valve 31 is in the first position 31b, and the discharge pressure oil of the left hydraulic pump 30 is supplied to the left actuator 32. The load pressure of the actuator 32 is the first position 31b of the operation valve 31.
It is introduced into the load pressure introducing passage 35 through the throttle provided in the. As a result, the first pressure switch 52 inputs an electric signal to the controller 54, and the controller 54 causes the left operation valve 3 to operate.
1 is determined to be the first position 31b, and whether or not to join the first position 31b is calculated based on a preset pattern. , The first and second merging / dividing valves 55 and 56 are set as merging positions 55a and 56a, and the discharge pressures of the left and right hydraulic pumps 30 are merged and supplied to the left actuator 32. When the flow is divided, the solenoid 60 of the solenoid valve 59 is energized to the supply position 59b, and the pressure oil discharged from the auxiliary hydraulic pump 47 is divided into the first and second combined flow dividing valves 55 and 5.
6 to supply pressure to the pressure receiving portions 57 and 58, and the flow dividing positions 55b and 56
b, only the pressure oil discharged from the left hydraulic pump 30 is supplied to the left actuator 32. On the other hand, load pressure introduction path 3
The load pressure of 5 acts on the LS valve 39 to tilt the swash plate 36 of the hydraulic pump 30 to set the differential pressure between the pump discharge pressure and the load pressure as the set pressure, and the load pressure acts on the pressure compensating valve 34. To compensate the pressure. The same applies to the case where the left operation lever 46 is operated in the opposite manner to supply pilot pressure oil to the second pilot conduit 49 and the case where the right operation lever 46 is operated.
【００１９】次に合流時のアンロード弁４２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３２がス
トロークエンドとなった時、又はアクチュエータ３２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６１より短絡路６２に流入してリリ
ーフ弁６３よりリリーフする。左右側の油圧ポンプ３
０，３０のポンプ吐出圧油はチェック弁６４より短絡路
６５に流入してアンロード弁６６の入口側に流入すると
同時にアンロード弁６６に作用する。これにより、アン
ロード弁６６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６６がアンロード位置６６ｂとなっ
て左右側の油圧ポンプ３０の吐出圧の一部がアンロード
する。Next, the unloading operation of the unloading valve 42 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 32 reaches the stroke end in the above-mentioned state, or when the load of the actuator 32 is very large and the load pressure is very high, the load pressure flows from the check valve 61 into the short circuit path 62 and the relief is performed. Relief from valve 63. Hydraulic pump 3 on the left and right
The pump discharge pressure oils of 0 and 30 flow from the check valve 64 into the short-circuit path 65, flow into the inlet side of the unload valve 66, and simultaneously act on the unload valve 66. As a result, the load pressure acting on the unload valve 66 becomes lower than the pump discharge pressure, and the unload valve 66 becomes the unload position 66b, so that part of the discharge pressure of the left and right hydraulic pumps 30 is unloaded.
【００２０】次に分流時のアンロード弁４２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３０の吐出路３０ａと右側
の油圧ポンプ３０の吐出路３０ａとが分離すると同時に
左側の負荷圧導入路３５と右側の負荷圧導入路３５が分
離するので、前述の左側のアクチュエータ３２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６
１より短絡路６２に流入し右側のチェック弁６１で右側
の負荷圧導入路３５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６３よりリリーフする。左
側の油圧ポンプ３０の吐出圧は左側のチェック弁６４よ
り短絡路６５に流入して右側のチェック弁６４で右側の
油圧ポンプ３０の吐出路３０ａ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６６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６６
がアンロード位置６６ｂ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３
１が中立位置３１ａであると右側の負荷圧導入路３５は
操作弁３１の中立位置３１ａを経てタンクに接続される
から、その負荷圧はほぼ０ｋｇ／ｃｍ2 であり、右側の
アンロード弁４２の第１受圧部４３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４２は第
２受圧部４４に作用する低圧のポンプ吐出圧でアンロー
ド位置４２ｂとなり、右側の油圧ポンプ３０のポンプ吐
出圧はごく低圧となる。Next, the unloading operation of the unloading valve 42 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 30a of the left hydraulic pump 30 and the discharge passage 30a of the right hydraulic pump 30 are separated, the load pressure introduction passage 35 on the left side and the load pressure introduction passage 35 on the right side are separated from each other. When the load pressure on the check valve 6 becomes too high,
From 1 to the short-circuit path 62, the check valve 61 on the right side is blocked from flowing to the load pressure introducing path 35 on the right side, and the load pressure is relieved from the relief valve 63 as described above. The discharge pressure of the left hydraulic pump 30 flows into the short circuit path 65 from the left check valve 64 and is prevented from flowing to the discharge path 30a of the right hydraulic pump 30 by the right check valve 64. It acts on the inlet side of the load 66. As a result, the unloading valve 66 can be operated in the same manner as when merging
Becomes the unloading position 66b to unload a part of the pump discharge pressure. In the above operation, the operation valve 3 on the right side
When 1 is the neutral position 31a, the load pressure introducing passage 35 on the right side is connected to the tank via the neutral position 31a of the operation valve 31, so the load pressure is about 0 kg / cm 2 , and the unload valve 42 on the right side The load pressure acting on the first pressure receiving portion 43 becomes almost 0 kg / cm 2, and the unload valve 42 is at the unload position 42b due to the low-pressure pump discharge pressure acting on the second pressure receiving portion 44, and the right hydraulic pump The pump discharge pressure of 30 is very low.
【００２１】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６３よりリリーフするから、アンロ
ード弁６６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６３のオーバライド特性により決定され、そ
の際の負荷圧が図６に示すように同一となり、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５
においてリリーフ弁６３の流入側とタンクを小径のオリ
フィス６７で連通してあるが、これは操作弁３１を中立
位置３１ａとした時に一対のチェック弁６１，６１で遮
断されている短絡路６２の負荷圧をすみやかにタンクに
流出するためである。As described above, since the load pressure is relieved from one relief valve 63 during the merging or the diversion, the relief flow rate which is the differential pressure for unloading the unload valve 66 is determined by the override characteristic of the relief valve 63. At that time, the load pressure becomes the same as shown in FIG. 6, and the maximum pump discharge pressure can be made the same at the time of merging and the time of diverting. Also, FIG.
In the above, the inflow side of the relief valve 63 and the tank are communicated with each other by the small diameter orifice 67. This is because the load of the short circuit path 62 which is blocked by the pair of check valves 61, 61 when the operation valve 31 is set to the neutral position 31a. This is because the pressure quickly flows into the tank.
【００２２】[0022]
【発明の効果】合流時でも分流時でも１つのリリーフ弁
６３がリリーフし、それによって１つのアンロード弁６
６がアンロードして最高ポンプ吐出圧を制限しているか
ら、最高ポンプ吐出圧を合流時と分流時で同一にでき
る。操作弁３１を中立位置とした時に第２の短絡路６２
内の負荷圧をすみやかにタンクに流出して応答性を向上
できる。[Effect of the Invention] One relief valve 63 is relieved at the time of merging and at the time of diverting, whereby one unload valve 6 is released.
Since 6 unloads and limits the maximum pump discharge pressure, the maximum pump discharge pressure can be made the same at the time of merging and at the time of branching. When the operation valve 31 is in the neutral position, the second short circuit 62
The load pressure inside can be quickly discharged to the tank to improve responsiveness.
【図１】従来の油圧回路図である。FIG. 1 is a conventional hydraulic circuit diagram.
【図２】改良した従来の油圧回路図である。FIG. 2 is an improved conventional hydraulic circuit diagram.
【図３】最高ポンプ吐出圧を制限する回路図である。FIG. 3 is a circuit diagram for limiting the maximum pump discharge pressure.
【図４】リリーフ流量と負荷圧の関係を示す図表であ
る。FIG. 4 is a chart showing the relationship between relief flow rate and load pressure.
【図５】本発明の実施例を示す油圧回路図である。FIG. 5 is a hydraulic circuit diagram showing an embodiment of the present invention.
【図６】リリーフ流量と負荷圧の関係を示す図表であ
る。FIG. 6 is a chart showing the relationship between relief flow rate and load pressure.
【符号の説明】 ３０…油圧ポンプ、３０ａ…吐出路、３１…操作弁、３
２…アクチュエータ、３４…圧力補償弁、３５…負荷圧
導入路、４２…アンロード弁、５５…合分流弁、５６…
合分流弁、６１…チェック弁、６２…第１の短絡路、６
３…リリーフ弁、６４…チェック弁、６５…第２の短絡
路、６６…アンロード弁、６７…オリフィス。[Explanation of Codes] 30 ... Hydraulic Pump, 30a ... Discharge Path, 31 ... Operation Valve, 3
2 ... Actuator, 34 ... Pressure compensating valve, 35 ... Load pressure introducing passage, 42 ... Unload valve, 55 ... Combined / diverted valve, 56 ...
Junction flow valve, 61 ... Check valve, 62 ... First short circuit, 6
3 ... Relief valve, 64 ... Check valve, 65 ... Second short circuit, 66 ... Unload valve, 67 ... Orifice.
Claims (2)
４を有する複数の操作弁３１と、複数の操作弁３１の負
荷圧を検出して圧力補償弁３４にフィードバックする複
数の負荷圧導入路３５と、複数の油圧ポンプ３０の吐出
路３０ａを合流、分離させる第１合分流弁５５と、複数
の負荷圧導入路３５を合流、分離させる第２合分流弁５
６を有する油圧回路において、 前記複数の油圧ポンプ３０ａ吐出路３０ａをチェック弁
６４を介して連通する第１の短絡路６５と、前記複数の
負荷圧導入路３５をチェック弁６１を介して連通する第
２の短絡路６２と、この第２の短絡路６２に設けたリリ
ーフ弁６３と、前記第１の短絡路６５に設けられてその
ポンプ吐出圧と前記第２の短絡路６２の負荷圧の差圧で
アンロードするアンロード弁６６を設けて成る油圧回
路。1. A plurality of hydraulic pumps 30 and a pressure compensating valve 3.
4, a plurality of operation valves 31 having a plurality of four, a plurality of load pressure introduction passages 35 for detecting load pressures of the plurality of operation valves 31 and feeding back to the pressure compensation valve 34, and a discharge passage 30a of a plurality of hydraulic pumps 30 are joined, The first merging / dividing valve 55 for separating and the second merging / dividing valve 5 for merging and separating the plurality of load pressure introducing passages 35.
In the hydraulic circuit having 6, a first short circuit path 65 that connects the plurality of hydraulic pumps 30a to the discharge path 30a via a check valve 64 and a plurality of load pressure introduction paths 35 to connect to the plurality of load pressure introduction paths 35 via a check valve 61. The second short-circuit path 62, the relief valve 63 provided in the second short-circuit path 62, the pump discharge pressure provided in the first short-circuit path 65, and the load pressure in the second short-circuit path 62. A hydraulic circuit provided with an unload valve 66 for unloading with a differential pressure.
でタンクに接続した請求項１記載の油圧回路。2. The second short circuit 65 is provided with an orifice 67.
The hydraulic circuit according to claim 1, wherein the hydraulic circuit is connected to the tank by.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4102547A JPH05272504A (en) | 1992-03-30 | 1992-03-30 | Hydraulic circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4102547A JPH05272504A (en) | 1992-03-30 | 1992-03-30 | Hydraulic circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05272504A true JPH05272504A (en) | 1993-10-19 |
Family
ID=14330279
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4102547A Pending JPH05272504A (en) | 1992-03-30 | 1992-03-30 | Hydraulic circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05272504A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1997028318A1 (en) * | 1996-02-01 | 1997-08-07 | Shin Caterpillar Mitsubishi Ltd. | Hydraulic circuit for hydraulic machine |
| JP2013079552A (en) * | 2011-10-05 | 2013-05-02 | Komatsu Ltd | Work vehicle |
| JP2013532260A (en) * | 2010-05-28 | 2013-08-15 | キャタピラー インコーポレイテッド | Hydraulic system that shares instrument flow and steering flow |
-
1992
- 1992-03-30 JP JP4102547A patent/JPH05272504A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1997028318A1 (en) * | 1996-02-01 | 1997-08-07 | Shin Caterpillar Mitsubishi Ltd. | Hydraulic circuit for hydraulic machine |
| JP2013532260A (en) * | 2010-05-28 | 2013-08-15 | キャタピラー インコーポレイテッド | Hydraulic system that shares instrument flow and steering flow |
| JP2013079552A (en) * | 2011-10-05 | 2013-05-02 | Komatsu Ltd | Work vehicle |
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