JPH0386684A - Hydraulic system for industrial vehicle - Google Patents
Hydraulic system for industrial vehicleInfo
- Publication number
- JPH0386684A JPH0386684A JP1224985A JP22498589A JPH0386684A JP H0386684 A JPH0386684 A JP H0386684A JP 1224985 A JP1224985 A JP 1224985A JP 22498589 A JP22498589 A JP 22498589A JP H0386684 A JPH0386684 A JP H0386684A
- Authority
- JP
- Japan
- Prior art keywords
- pressure
- flow rate
- valve
- cargo handling
- control valve
- 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
- 230000007246 mechanism Effects 0.000 claims abstract description 9
- 238000006073 displacement reaction Methods 0.000 claims description 16
- 230000007423 decrease Effects 0.000 abstract description 5
- 230000008859 change Effects 0.000 abstract description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000001174 ascending effect Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
Landscapes
- Power Steering Mechanism (AREA)
- Forklifts And Lifting Vehicles (AREA)
- Fluid-Pressure Circuits (AREA)
Abstract
Description
【発明の詳細な説明】
[産業上の利用分野]
本発明は、フォークリフト等産業車両の油圧装置に係り
、詳しくは荷役及びパワーステアリング用油圧ポンプの
容量制御を行うようにした油圧装置に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic system for an industrial vehicle such as a forklift, and more particularly to a hydraulic system that controls the capacity of a hydraulic pump for cargo handling and power steering.
[従来の技術]
フォークリフトに装備されている一般的な油圧装置は、
第3図に例示するように、エンジン1によって駆動され
る定容量形油圧ポンプ2の吐出管路3に分流弁4が設け
られ、圧力油は該分流弁4によってパワーステアリング
回路5の所要流量と残余の荷役回路用流量とに分流され
るとともに、荷役回路6に送給された圧力油は、荷役制
御弁7の操作を介して必要の都度リフトシリンダ8又は
ティルトシリンダ9に供給される。[Conventional technology] A typical hydraulic system equipped on a forklift truck is
As illustrated in FIG. 3, a flow divider valve 4 is provided in the discharge pipe line 3 of the constant displacement hydraulic pump 2 driven by the engine 1, and the pressure oil is adjusted to the required flow rate of the power steering circuit 5 through the flow divider valve 4. The pressure oil that is divided into the remaining flow rate for the cargo handling circuit and supplied to the cargo handling circuit 6 is supplied to the lift cylinder 8 or the tilt cylinder 9 through the operation of the cargo handling control valve 7 as needed.
[発明が解決しようとする課題]
上述したように従来の油圧装置は、定容量油圧ポンプ2
から吐出された圧力油のうち、パワーステアリング回路
5用として確保される所要流量以外はすべて荷役回路6
へ送給されるため、実際に荷役操作が行なわれていない
状態では、かかる圧力油は単に荷役制御弁7を経由する
余剰油として油槽に還流されてしまう。しかも油圧ポン
プ2の吐出油量はエンジン回転数の上昇につれて比例的
に増大し、無用な余剰油の循環は一層助長される結果と
なる。したがって、このような圧力油の無駄な循環の繰
返しは動力損失に加えて油温の上昇を招き、シール部材
などの早期劣化を誘発して油圧装置に重大な欠陥を生じ
させる素因となる。[Problems to be Solved by the Invention] As described above, the conventional hydraulic system has a fixed displacement hydraulic pump 2.
Of the pressure oil discharged from the cargo handling circuit 6, all of the pressure oil discharged from the cargo handling circuit 6 except for the required flow rate secured for the power steering circuit 5.
Therefore, when no cargo handling operation is actually performed, this pressure oil simply flows back to the oil tank as surplus oil via the cargo handling control valve 7. Moreover, the amount of oil discharged from the hydraulic pump 2 increases proportionally as the engine speed increases, and the circulation of unnecessary surplus oil is further promoted. Therefore, such repeated wasteful circulation of pressure oil causes a rise in oil temperature in addition to power loss, leading to early deterioration of sealing members and the like, and causing serious defects in the hydraulic system.
本発明は、エンジンに従動するポンプの回転変動と荷役
操作の有無及び種別とを感知して、機に応じたポンプの
容量制御を遂行することを解決すべき技術課題とするも
のである。A technical problem to be solved by the present invention is to detect rotational fluctuations of a pump driven by an engine and the presence or absence and type of cargo handling operations to control the pump capacity according to the machine.
[課題を解決するための手段]
本発明は上記課題解決のため、エンジンにより駆動され
る可変容量形油圧ポンプと、該ポンプの吐出管路に設け
られ、圧力油をパワーステアリング回路の所要流量と残
余の荷役回路用流量とに分流する分流弁と、該荷役回路
の圧力油を荷役アクチュエータへ供給するリフト及びテ
ィルトスプールを内装した荷役制御弁と、上記分流弁に
至る吐出管路中に配設され、該各スプールの動作ポジシ
ョンを経由したパイロット圧によって操作される絞り付
き流量切換弁と、吐出圧力に対抗する該流量切換弁の絞
り後の圧力又は上記各スプールの動作ポジションを経由
した吐出圧力若しくは調整圧力との差圧によってパイロ
ット操作され、上記ポンプの容量可変機構を制御する容
量制御弁とからなり、上記流量切換弁による絞り後の流
量を、上記パワーステアリング回路の所要流量をやや上
回る程度に設定した新規な構成を採用している。[Means for Solving the Problems] In order to solve the above problems, the present invention includes a variable displacement hydraulic pump driven by an engine, and a variable displacement hydraulic pump that is installed in the discharge pipe of the pump and supplies pressure oil to the required flow rate of the power steering circuit. A diverter valve that divides the flow into the remaining flow rate for the cargo handling circuit, a cargo handling control valve equipped with a lift and tilt spool that supplies pressure oil from the cargo handling circuit to the cargo handling actuator, and a discharge pipe that leads to the diverter valve. and a flow rate switching valve with a throttle operated by pilot pressure via the operating position of each of the spools, and a pressure after the throttle of the flow rate switching valve that opposes the discharge pressure or a discharge pressure via the operating position of each of the spools. or a capacity control valve that is pilot-operated by the differential pressure with the adjustment pressure and controls the variable capacity mechanism of the pump, and the flow rate after throttling by the flow rate switching valve is slightly higher than the required flow rate of the power steering circuit. A new configuration has been adopted.
[作用コ
本発明装置において、荷役操作が行われていない状態で
は、流量切換弁はパイロット圧が作用しないままに絞り
流路のポジションが保持されている。したがって、この
絞りにより生じた流量切換弁の前後の差圧がパイロット
圧として容量制御弁に対抗する形で負荷され、該対抗圧
力とばね力との均衡によって該容量制御弁のポジション
も保持される。このとき流量切換弁による絞り後の流量
はパワーステアリング回路の所要流量をやや上回る程度
に設定されており、エンジンの回転変動に基づいたポン
プの吐出油量の増減は、上記差圧の変化を伴って直ちに
容量制御弁から可変容量機構へと作用し、ポンプ1回転
当りの吐出油量が自動的に調節されて上記、絞り後の流
量は安定的に維持される。[Operation] In the apparatus of the present invention, when no cargo handling operation is being performed, the flow rate switching valve is maintained at the throttle flow path position without any pilot pressure acting on it. Therefore, the differential pressure across the flow rate switching valve generated by this restriction is applied as pilot pressure to the capacity control valve in opposition to it, and the position of the capacity control valve is also maintained by the balance between the counter pressure and the spring force. . At this time, the flow rate after throttling by the flow rate switching valve is set to a level that slightly exceeds the required flow rate of the power steering circuit, and the increase or decrease in the amount of oil discharged from the pump based on engine rotational fluctuations is accompanied by changes in the differential pressure mentioned above. Immediately, the capacity control valve acts on the variable capacity mechanism, and the amount of oil discharged per revolution of the pump is automatically adjusted to maintain the above-mentioned flow rate after throttling stably.
かかる状態から荷役操作例えばリフト操作が行われると
、吐出管路から荷役制御弁に内装されたリフトスプール
の動作ポジションへと導入された吐出圧力が、それまで
の対抗圧力と代替する形で直接容量制御弁に負荷され、
同時に該吐出圧力は流量切換弁内のパイロットチエツク
弁をも開通させるので、差圧の解消による容量制御弁の
変位を介して可変容量機構は大きく作動し、ポンプ1回
転当りの吐出油量は最大限に増強されるとともに、絞り
による回路抵抗も解消される。When a cargo handling operation, such as a lift operation, is performed in such a state, the discharge pressure introduced from the discharge pipe to the operating position of the lift spool built into the cargo handling control valve directly increases the capacity in place of the previous counterpressure. Loaded on the control valve,
At the same time, the discharge pressure also opens the pilot check valve in the flow rate switching valve, so the variable displacement mechanism operates greatly through the displacement of the displacement control valve due to the elimination of the differential pressure, and the amount of oil discharged per revolution of the pump is maximized. At the same time, the circuit resistance caused by the aperture is also eliminated.
また、荷役操作がティルト操作であった場合には、吐出
管路から同様にティルトスプールの動作ポジションへと
導入された吐出圧力が、該ポジションの絞り流路を介し
て調整圧力に減圧され、上記流量切換弁の絞り後の圧力
よりも高く設定された該調整圧力がそれまでの対抗圧力
に代替する形で上記容量制御弁に負荷される。したがっ
て、容量制御弁をパイロット操作する差圧の減少が該容
量制御弁の変位を通じて可変容量機構へと作用し、ティ
ルト操作に必要な油量を荷役回路へ送給しうる中容量程
度にポンプ1回転当りの吐出油量を増加させる。なお、
この場合も上記調整圧力が流量切換弁内のパイロットチ
エツク弁を開通操作して絞りによる回路抵抗を解消させ
る。In addition, when the cargo handling operation is a tilt operation, the discharge pressure introduced from the discharge pipe to the operating position of the tilt spool is reduced to the adjusted pressure via the throttle channel at that position, and the above-mentioned The adjusted pressure, which is set higher than the throttled pressure of the flow rate switching valve, is applied to the capacity control valve in place of the previous counterpressure. Therefore, the decrease in the differential pressure when pilot operating the capacity control valve acts on the variable capacity mechanism through the displacement of the capacity control valve, and the pump 1 has a medium capacity that can supply the amount of oil necessary for the tilt operation to the cargo handling circuit. Increase the amount of oil discharged per revolution. In addition,
In this case as well, the adjusted pressure opens the pilot check valve in the flow rate switching valve to eliminate the circuit resistance caused by the throttle.
[実施例コ
以下、本発明の実施例を図に基づいて具体的に説明する
。[Embodiments] Hereinafter, embodiments of the present invention will be explained in detail based on the drawings.
第1図及び第2図は本発明をフォークリフトに適用した
油圧装置の要部を示すもので、エンジン10によって駆
動される可変容量形油圧ポンプ11には、周知の斜板式
アキシアルピストンポンプ(以下、単にポンプという〉
が用いられており、該ポンプ11に接続される吐出管路
12には、圧力油をパワーステアリング回路13の所要
流量と残余の荷役回路用流量とに分流する分流弁14が
設けられ、荷役回路15は荷役制御弁16を介してリフ
トシリンダ17、ティルトシリンダ18等の荷役アクチ
ュエータと接続されている。1 and 2 show the main parts of a hydraulic system in which the present invention is applied to a forklift. A variable displacement hydraulic pump 11 driven by an engine 10 includes a well-known swash plate type axial piston pump (hereinafter referred to as Simply called a pump
The discharge pipe 12 connected to the pump 11 is provided with a flow divider valve 14 that divides the pressure oil into the required flow rate of the power steering circuit 13 and the remaining flow rate for the cargo handling circuit. 15 is connected to cargo handling actuators such as a lift cylinder 17 and a tilt cylinder 18 via a cargo handling control valve 16.
上記分流弁14に至る吐出管路12中には絞り付き流量
切換弁20が設けられ、該流量切換弁20の詳細な構成
は第2図にもつとも明瞭に示されている。すなわち、弁
主体21には、パイロットチエツク弁22を経由する通
路aと、固定絞り23を経由する通路すとが形成され、
該チエツク弁22はパイロット圧が負荷されない限り閉
止状態を保つので、吐出圧力つまり入口圧力P1と固定
絞り23を介した出口圧力P2との間には差圧を生じ、
該出口圧力P2はパイロット管路26にも導通せられて
いる。A flow rate switching valve 20 with a throttle is provided in the discharge pipe 12 leading to the above-mentioned flow dividing valve 14, and the detailed structure of the flow rate switching valve 20 is clearly shown in FIG. That is, the valve main body 21 is formed with a passage a passing through the pilot check valve 22 and a passage passing through the fixed throttle 23.
Since the check valve 22 remains closed unless pilot pressure is applied, a pressure difference is generated between the discharge pressure, that is, the inlet pressure P1, and the outlet pressure P2 via the fixed throttle 23.
The outlet pressure P2 is also communicated to the pilot line 26.
30は非荷役時にパイロット管路28を介した入口圧力
P1と上記パイロット管路26及びシャトル弁27を介
した出口圧力P2との差圧によって操作される容量制御
弁であって、該容量制御弁30の詳細な構成も同様に第
2図に示されている。Reference numeral 30 denotes a capacity control valve which is operated by the differential pressure between the inlet pressure P1 via the pilot line 28 and the outlet pressure P2 via the pilot line 26 and shuttle valve 27 during non-loading. The detailed configuration of 30 is also shown in FIG.
すなわち、弁主体31にはパイロット管路28.26を
介した差圧とばね32の付勢力との均衡によって制御さ
れるスプール33が内装され、該スプール33にはパイ
ロット管路28を経由した入口圧力P1をボート35を
介して可変容量機構40の制御シリンダ41に導く切欠
34aと、該ボート35をドレンボート36に接続させ
るための切欠34bとが設けられている。そして可変容
量機構40は、上記制御シリンダ41に導入された入口
圧力P1によってピストンロッド42が動作し、復帰ば
ね11aの付勢力と均衡してポンプ11の斜板傾角を変
化させるものである。なお、非荷役時の送給流量を左右
する上記固定絞り23の開度は、絞り前後の差圧(Pl
−P2 >が設定圧に達したとき、容量制御弁3oを
介したポンプ11の容量制御に基づいて得られる絞り後
の流量がパワーステアリング回路13の所要流量をやや
上回る程度に設定されている。That is, the valve body 31 is equipped with a spool 33 that is controlled by the balance between the differential pressure via the pilot line 28 and the biasing force of the spring 32, and the spool 33 has an inlet via the pilot line 28. A notch 34a for guiding the pressure P1 to the control cylinder 41 of the variable displacement mechanism 40 via the boat 35, and a notch 34b for connecting the boat 35 to the drain boat 36 are provided. In the variable displacement mechanism 40, the piston rod 42 is operated by the inlet pressure P1 introduced into the control cylinder 41, and the tilt angle of the swash plate of the pump 11 is changed in balance with the biasing force of the return spring 11a. The opening degree of the fixed throttle 23, which influences the feed flow rate during non-load handling, is determined by the differential pressure (Pl) before and after the throttle.
-P2> reaches the set pressure, the throttled flow rate obtained based on the capacity control of the pump 11 via the capacity control valve 3o is set to be slightly higher than the required flow rate of the power steering circuit 13.
50は吐出管路12の吐出圧力P1を荷役制御弁16を
経由して上記容量制御弁30に作用させるパイロット管
路で、荷役制御弁16に内装されたリフトスプール16
aの動作(上昇)ポジションを経由して上記シャトル弁
27に連通され、該管路50から分岐した管路50aは
同ティルトスプール16bの動作ポジションに設けられ
た絞り流路を経由して同様にシャトル弁27に合流され
ている。なお、上記スプール16a、16bの動作ポジ
ションを経由した吐出圧力P1又は調整圧力P3は、ざ
らに分岐管路50bを経て上記パイロットチエツク弁2
2を開放させるパイロット圧としても作用する。また、
上記絞り流路を経由した調整圧力P3は、後述するティ
ルト操作時の所要流量と適合するよう上記・出口圧力P
2よりも高く設定され士いる。Reference numeral 50 denotes a pilot pipe for applying the discharge pressure P1 of the discharge pipe 12 to the capacity control valve 30 via the cargo handling control valve 16, and a lift spool 16 installed in the cargo handling control valve 16.
A pipe line 50a, which is connected to the shuttle valve 27 via the operating (ascending) position of the tilt spool 16b and branched from the pipe line 50, similarly communicates with the shuttle valve 27 via a throttle passage provided at the operating position of the tilt spool 16b. It is merged into the shuttle valve 27. Note that the discharge pressure P1 or the adjusted pressure P3 that has passed through the operating positions of the spools 16a and 16b is roughly transmitted to the pilot check valve 2 through a branch pipe 50b.
It also acts as a pilot pressure to open 2. Also,
The adjusted pressure P3 via the throttle flow path is adjusted to match the flow rate required during tilt operation, which will be described later.
It may be set higher than 2.
上述の構成において、荷IQ操作が行われていない状態
では、パイロットチエツク弁22は閉止状態にあり、圧
力油は吐出管路12から固定絞り23を経て通路すへと
流れ、この絞り作用によって該流量切換弁20の出口側
流量が規制され、同時に入口圧力P1と出口圧力P2と
の間には差圧が生じる。また、このときの出口側流量は
分流弁14によって確保されるパワーステアリング回路
13の所要流量をやや上回る程度に設定されており、荷
役回路15に対する余剰圧力油の送給はごく僅少に!1
1限されている。In the above configuration, when the load IQ operation is not performed, the pilot check valve 22 is in a closed state, and the pressure oil flows from the discharge pipe 12 to the passage via the fixed throttle 23, and the throttle action causes the pressure oil to flow into the passage. The flow rate on the outlet side of the flow rate switching valve 20 is regulated, and at the same time, a pressure difference is generated between the inlet pressure P1 and the outlet pressure P2. In addition, the flow rate on the outlet side at this time is set to be slightly higher than the required flow rate of the power steering circuit 13 secured by the flow dividing valve 14, so that the amount of excess pressure oil supplied to the cargo handling circuit 15 is extremely small! 1
Limited to 1.
ところがポンプ11の回転はエンジン10に支配されて
随時変動するため、例えばエンジン10の回転が上昇す
ると吐出管路12の流量が増加し、同時に入口圧力P1
、出口圧力P2及び出口側流量は共に増大することにな
る。しかし入口圧力P1の上昇は、パイロット管路28
から上記した差圧によって均衡状態を保持している容量
制御弁30のボート35を経由して直ちにflilJ御
シリンダシリンダ41内に反映されるので、ピストンロ
ッド42は復帰ばね11aの付勢力に抗して斜板傾角を
縮小側へ変化させる。勿論、エンジン10の回転が低下
した場合には、上記説明とは全く逆作用的な動作を辿っ
てポンプ11の1回転当りの吐出油量が調節されるので
、流量制御弁20の出口側流量はほぼ一定に保たれる。However, the rotation of the pump 11 is controlled by the engine 10 and varies from time to time. For example, when the rotation of the engine 10 increases, the flow rate of the discharge pipe 12 increases, and at the same time, the inlet pressure P1 increases.
, the outlet pressure P2 and the outlet flow rate both increase. However, the increase in inlet pressure P1
Since the pressure is immediately reflected in the flilJ control cylinder 41 via the boat 35 of the capacity control valve 30, which is maintained in an equilibrium state by the above-mentioned differential pressure, the piston rod 42 resists the biasing force of the return spring 11a. to change the swash plate inclination to the reduction side. Of course, when the rotation of the engine 10 decreases, the amount of oil discharged per revolution of the pump 11 is adjusted through an operation that is completely opposite to the above explanation, so that the flow rate on the outlet side of the flow rate control valve 20 is adjusted. remains almost constant.
かかる状態から例えばリフト操作(リフトスプール16
aの変位〉が行われると、吐出管路12からパイロット
管路50を経てリフトスプール16aの上昇ポジション
へと導入された吐出圧力P1がそのままシャトル弁27
に導かれる。該吐出圧力P1はそれまでシャトル弁27
を経由していた上記出口圧力P2よりも高いため、該シ
ャトル弁27を優先的に通過して容量制御弁30に代替
圧力として負荷される。したがって、スプール33には
相反する方向に同圧の吐出圧力(入口圧力〉Plが作用
することとなり、スプール33はばね32の付勢力によ
り図示右方へ大きく移動する。From this state, for example, lift operation (lift spool 16
When displacement a> is performed, the discharge pressure P1 introduced from the discharge pipe 12 to the raised position of the lift spool 16a via the pilot pipe 50 is directly applied to the shuttle valve 27.
guided by. Until then, the discharge pressure P1 is
Since the pressure is higher than the outlet pressure P2 that has passed through the shuttle valve 27, the pressure passes through the shuttle valve 27 preferentially and is applied to the capacity control valve 30 as an alternative pressure. Therefore, the same discharge pressure (inlet pressure>Pl) acts on the spool 33 in opposite directions, and the spool 33 moves significantly to the right in the drawing due to the biasing force of the spring 32.
このため制御シリンダ41はポート35及び切欠34a
を介してドレンポート36と全面的に連通し、油圧力の
支援を失ったピストンロッド42は復帰ばね11aの付
勢力に屈して速やかに退勤するので、斜板傾角の拡大側
への変化によりポンプ11の1回転当りの吐出油量は最
大限に増強される。そしてパイロット管路50を経由し
た吐出圧力P1が、同時に管路50bを介してパイロタ
1〜チエツク弁22を開き通路aを開通させるので、ポ
ンプ11のフル稼動と固定絞り23を経由する回路抵抗
の解消にさらにエンジン10の回転上昇操作が加わって
、リフト操作を行うに十分な量の圧力油が荷役回路15
へ速やかに送給される。Therefore, the control cylinder 41 has the port 35 and the notch 34a.
The piston rod 42, which is in full communication with the drain port 36 through the piston rod and loses the support of hydraulic pressure, succumbs to the biasing force of the return spring 11a and quickly withdraws, so that the pump 11, the amount of oil discharged per revolution is maximized. Then, the discharge pressure P1 via the pilot pipe 50 simultaneously opens the pilot 1 to the check valve 22 via the pipe 50b and opens the passage a, so that the pump 11 is fully operated and the circuit resistance via the fixed throttle 23 is reduced. When the engine 10 is operated to increase the rotation of the engine 10, a sufficient amount of pressure oil is supplied to the cargo handling circuit 15 to carry out the lift operation.
will be promptly sent to.
また、荷役操作がリフト操作の半量程度の油量で足りる
ティルト操作であった場合には、吐出管路12からパイ
ロット管路50及び分岐管路50aを経てティルトスプ
ール16bの動作ポジションへと導入された吐出圧力P
1が、該ポジションの絞り流路により調整圧力P3に減
圧されて同様にシャトル弁27に導かれる。このとき該
調整圧力P3もそれまでシャトル弁27を経由していた
上記出口圧力P2より高く設定されているため、出口圧
力P2に優先しこれに代替する形で容量制御弁30に負
荷される。したがって、スプール33は差圧の減少によ
って図示右方へ移動し、制御シリンダ41と連通するポ
ート35を切欠34bを介して一時的にドレンポート3
6に連通させる。In addition, when the cargo handling operation is a tilt operation that requires about half the amount of oil as in a lift operation, the oil is introduced from the discharge pipe 12 through the pilot pipe 50 and the branch pipe 50a to the operating position of the tilt spool 16b. discharge pressure P
1 is reduced in pressure to the adjusted pressure P3 by the throttle flow path at the position, and is similarly guided to the shuttle valve 27. At this time, the adjusted pressure P3 is also set higher than the outlet pressure P2 which has passed through the shuttle valve 27 up to that point, so it is loaded on the capacity control valve 30 in a manner that takes priority over and replaces the outlet pressure P2. Therefore, the spool 33 moves to the right in the figure due to the decrease in differential pressure, and temporarily connects the port 35 communicating with the control cylinder 41 to the drain port 3 through the notch 34b.
Connect to 6.
そして制御シリンダ41内の圧力降下と復帰ばね11a
の付勢力とによりピストンロッド42は退勤し、斜板傾
角の拡大側への変化を通じてポンプ11の吐出油量が増
加されると、上記差圧が再度増大に転じてスプール33
は左方へ移動し、ポート35はドレンポート36と絶縁
されると同時に再び入口圧力P1を受入れることとなる
ので、制御シリンダ41内の回復圧力が復帰ばね11a
の付勢力に抗してピストンロッド42を進動させ、斜板
傾角を縮小側へ変化させる。なお、この場合も管路50
bを介した調整圧力P3がパイロットチエツク弁22を
開き通路aを開通させるので、かかる一連の調整動作を
通じて荷役回路15へ送給される油量が、実質的にティ
ルト操作を賄うに足る程度の量となるようポンプ1回転
当りの吐出油量が調節される。and the pressure drop in the control cylinder 41 and the return spring 11a.
The piston rod 42 is retracted due to the biasing force of
moves to the left, and the port 35 is insulated from the drain port 36 and at the same time receives the inlet pressure P1 again, so that the recovery pressure in the control cylinder 41 increases to the return spring 11a.
The piston rod 42 is advanced against the urging force of , and the swash plate inclination angle is changed to the reduction side. In addition, in this case as well, the conduit 50
Since the adjustment pressure P3 via b opens the pilot check valve 22 and opens the passage a, the amount of oil sent to the cargo handling circuit 15 through this series of adjustment operations is sufficient to substantially cover the tilt operation. The amount of oil discharged per revolution of the pump is adjusted so as to achieve the desired amount.
[発明の効果]
以上、詳述したように本発明によれば、吐出管路に設け
た絞り付き流量切換弁によって非荷役時に荷役回路へ送
給される余剰油量を極力制限し、エンジン回転の変動に
対しては容量制御弁との協同により可変容量形油圧ポン
プの吐出油量を調節して回路流量を安定的に保持すると
ともに、一方、荷役時には荷役制御弁に内装されたリフ
トスプール又はティルトスプールの動作ポジションを経
由するパイロット圧によって荷役の種類を判別し、各弁
の変位を通じたポンプ吐出油量の調節と回路抵抗の解消
とにより、それぞれの荷役操作に適応した量の圧力油が
荷役回路へ送給されるので、エンジン回転の変動にも巧
みに対応してすべての事態における余剰油量をきわめて
合理的に削減するのみにとどまらず、油温の上昇がきわ
めて効果的に抑制されるので、各シール部材は熱劣化か
ら解放されて、油圧装置の長期安定化に著しく貢献しう
るちのである。[Effects of the Invention] As described in detail above, according to the present invention, the amount of surplus oil fed to the cargo handling circuit during non-cargo handling is limited as much as possible by the flow rate switching valve with a throttle provided in the discharge pipe, and the engine rotation is In response to fluctuations in the flow rate, the flow rate of the variable displacement hydraulic pump is adjusted in cooperation with the capacity control valve to maintain a stable circuit flow rate. On the other hand, during cargo handling, the lift spool or The type of cargo handling is determined based on the pilot pressure that passes through the operating position of the tilt spool, and by adjusting the amount of pump discharged oil through displacement of each valve and eliminating circuit resistance, the amount of pressure oil suitable for each cargo handling operation is delivered. Since it is sent to the cargo handling circuit, it not only skillfully responds to fluctuations in engine speed and reduces the amount of excess oil in all situations in a very rational manner, but also extremely effectively suppresses increases in oil temperature. As a result, each sealing member is freed from thermal deterioration and significantly contributes to long-term stability of the hydraulic system.
第1図は本発明に係る油圧装置の一実施例を示す油圧回
路図、第2図は同実施例の流量切換弁及び容量制御弁を
示す断面図、第3図は従来の油圧装置を示す油圧回路図
である。
10・・・エンジン 11・・・可変容量形油圧ポンプ
12・・・吐出管路
13・・・パワーステアリング回路
14・・・分流弁 15・・・荷役回路16・・
・荷役制御弁 16a・・・リフトスプール16b・
・・ティルトスプール
20・・・流量切換弁 27・・・シャトル弁30・
・・容量制御弁Fig. 1 is a hydraulic circuit diagram showing an embodiment of a hydraulic system according to the present invention, Fig. 2 is a sectional view showing a flow rate switching valve and a capacity control valve of the same embodiment, and Fig. 3 is a conventional hydraulic system. It is a hydraulic circuit diagram. 10...Engine 11...Variable displacement hydraulic pump 12...Discharge pipe line 13...Power steering circuit 14...Diversion valve 15...Cargo handling circuit 16...
・Cargo handling control valve 16a...lift spool 16b・
...Tilt spool 20...Flow rate switching valve 27...Shuttle valve 30...
・Capacity control valve
Claims (1)
ポンプの吐出管路に設けられ、圧力油をパワーステアリ
ング回路の所要流量と残余の荷役回路用流量とに分流す
る分流弁と、該荷役回路の圧力油を荷役アクチユエータ
へ供給するリフト及びテイルトスプールを内装した荷役
制御弁と、上記分流弁に至る吐出管路中に配設され、該
各スプールの動作ポジションを経由したパイロット圧に
よつて操作される絞り付き流量切換弁と、吐出圧力に対
抗する該流量切換弁の絞り後の圧力又は上記各スプール
の動作ポジションを経由した吐出圧力若しくは調整圧力
との差圧によつてパイロット操作され、上記ポンプの容
量可変機構を制御する容量制御弁とからなり、上記流量
切換弁による絞り後の流量を、上記パワーステアリング
回路の所要流量をやや上回る程度に設定したことを特徴
とする産業車両の油圧装置。A variable displacement hydraulic pump driven by an engine; a diversion valve installed in the discharge line of the pump to divide pressure oil into the required flow rate for the power steering circuit and the remaining flow rate for the cargo handling circuit; The cargo handling control valve is equipped with a lift and tail spool that supplies pressure oil to the cargo handling actuator, and is installed in the discharge pipe leading to the above-mentioned diverter valve, and is operated by pilot pressure via the operating position of each spool. The flow rate switching valve with a throttle is pilot-operated by the differential pressure between the throttled flow rate switching valve and the throttled pressure of the flow rate switching valve opposing the discharge pressure, or the discharge pressure or adjustment pressure via the operating position of each of the spools. A hydraulic system for an industrial vehicle, comprising a capacity control valve that controls a variable capacity mechanism of a pump, and wherein the flow rate after throttling by the flow rate switching valve is set to a level that slightly exceeds the required flow rate of the power steering circuit. .
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP1224985A JPH0386684A (en) | 1989-08-31 | 1989-08-31 | Hydraulic system for industrial vehicle |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP1224985A JPH0386684A (en) | 1989-08-31 | 1989-08-31 | Hydraulic system for industrial vehicle |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH0386684A true JPH0386684A (en) | 1991-04-11 |
Family
ID=16822291
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP1224985A Pending JPH0386684A (en) | 1989-08-31 | 1989-08-31 | Hydraulic system for industrial vehicle |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH0386684A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006103893A (en) * | 2004-10-06 | 2006-04-20 | Kayaba Ind Co Ltd | Negative control circuit for industrial machine |
JP2006103892A (en) * | 2004-10-06 | 2006-04-20 | Kayaba Ind Co Ltd | Negative control circuit for industrial machine |
JP2007039226A (en) * | 2005-08-05 | 2007-02-15 | Toyota Industries Corp | Hydraulic system of industrial vehicle |
-
1989
- 1989-08-31 JP JP1224985A patent/JPH0386684A/en active Pending
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006103893A (en) * | 2004-10-06 | 2006-04-20 | Kayaba Ind Co Ltd | Negative control circuit for industrial machine |
JP2006103892A (en) * | 2004-10-06 | 2006-04-20 | Kayaba Ind Co Ltd | Negative control circuit for industrial machine |
JP4601377B2 (en) * | 2004-10-06 | 2010-12-22 | カヤバ工業株式会社 | Negative control circuit for industrial machinery |
JP2007039226A (en) * | 2005-08-05 | 2007-02-15 | Toyota Industries Corp | Hydraulic system of industrial vehicle |
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