JPWO2004076334A1 - Hydraulic control device for hydraulic working machine - Google Patents

Hydraulic control device for hydraulic working machine Download PDF

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JPWO2004076334A1
JPWO2004076334A1 JP2005502952A JP2005502952A JPWO2004076334A1 JP WO2004076334 A1 JPWO2004076334 A1 JP WO2004076334A1 JP 2005502952 A JP2005502952 A JP 2005502952A JP 2005502952 A JP2005502952 A JP 2005502952A JP WO2004076334 A1 JPWO2004076334 A1 JP WO2004076334A1
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hydraulic
cylinder
boom
working machine
control device
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謙輔 佐藤
謙輔 佐藤
豊岡　司
司 豊岡
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Hitachi Construction Machinery Co Ltd
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Hitachi Construction Machinery Co Ltd
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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
    • E02F3/36—Component parts
    • E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
    • E02F3/43—Control of dipper or bucket position; Control of sequence of drive operations
    • E02F3/431—Control of dipper or bucket position; Control of sequence of drive operations for bucket-arms, front-end loaders, dumpers or the like
    • E02F3/432—Control of dipper or bucket position; Control of sequence of drive operations for bucket-arms, front-end loaders, dumpers or the like for keeping the bucket in a predetermined position or attitude
    • E02F3/433—Control of dipper or bucket position; Control of sequence of drive operations for bucket-arms, front-end loaders, dumpers or the like for keeping the bucket in a predetermined position or attitude horizontal, e.g. self-levelling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F9/00—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
    • B66F9/06—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
    • B66F9/065—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks non-masted
    • B66F9/0655—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks non-masted with a telescopic boom
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F9/00—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
    • B66F9/06—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
    • B66F9/075—Constructional features or details
    • B66F9/20—Means for actuating or controlling masts, platforms, or forks
    • B66F9/22—Hydraulic devices or systems

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  • Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Civil Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mining & Mineral Resources (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Operation Control Of Excavators (AREA)
  • Jib Cranes (AREA)
  • Forklifts And Lifting Vehicles (AREA)

Abstract

ブームの自由端を起伏方向に回動させる起伏シリンダ７と、ブームの先端部に回動可能に取り付けられたアタッチメントと、ブームに対してアタッチメントを上下方向に回動させるチルトシリンダ８と、前記ブームの起伏動作に連動して伸縮し、前記ブームの起伏角度の変化に応じて前記アタッチメントの上下方向の角度を予め設定した角度に保持するレベリングシリンダ９とを備え、ブーム上げ操作時における起伏シリンダ７の作動圧が予め設定した圧力よりも高くなったときに、起伏シリンダ７の伸び動作を行わせる側の管路３５とレベリングシリンダ９の伸び動作を行わせる側の管路３３とを連通させる。この連通は、前記管路３５，３３間に設けられた管路３７と、この管路３７の回路を切り換える第１及び第２切換弁２１，２０によって行われる。A hoisting cylinder 7 that rotates the free end of the boom in the hoisting direction, an attachment that is rotatably attached to the tip of the boom, a tilt cylinder 8 that rotates the attachment in the vertical direction with respect to the boom, and the boom A leveling cylinder 9 that expands and contracts in conjunction with the hoisting movement of the boom and holds the vertical angle of the attachment at a preset angle according to a change in the hoisting angle of the boom. When the operating pressure becomes higher than a preset pressure, the conduit 35 on the side where the undulating cylinder 7 is extended and the conduit 33 on the side where the leveling cylinder 9 is extended are communicated. This communication is performed by the pipe 37 provided between the pipes 35 and 33 and the first and second switching valves 21 and 20 for switching the circuit of the pipe 37.

Description

本発明は、ブームと、当該ブームの起伏角度の如何に関わりなく車体に対する上下方向の角度を予め設定した角度に維持可能なアタッチメントとを備えたリフトトラックなどの油圧作業機の油圧制御装置に関する。  The present invention relates to a hydraulic control device for a hydraulic working machine such as a lift truck that includes a boom and an attachment that can maintain a vertical angle with respect to a vehicle body at a preset angle regardless of the undulation angle of the boom.

従来より、油圧作業機として、リフトトラックと呼ばれる荷役作業用の車両や高所作業車が知られている。高所作業車としては、例えば登録実用新案第２５６６６３１号公報特許文献１に開示されているような装置が公知である。
この種の高所作業車やリフトトラックなどの油圧作業機においては、リフト能力、即ち、どれだけの重量物を持ち上げられるかの性能が重視される。油圧作業機のリフト能力を高めるためには、一般に、起伏シリンダとして受圧面積がより大きな油圧シリンダを用いるという手段がとられる。
しかしながら、油圧シリンダが出せる力は受圧面積×圧力で表されるので、受圧面積が大きな油圧シリンダを用いれば油圧作業機のリフト能力を向上させることができるが、油圧シリンダの伸びスピードは、圧油の流入流量／受圧面積で表されるので、受圧面積が大きな油圧シリンダを用いると、ブーム上げのスピードが遅くなるという不都合が生じる。また、油圧シリンダは、受圧面積が大きくなるほど高価になるので、受圧面積が大きな油圧シリンダを用いると、油圧作業機がコスト高になる不都合も生じる。
また、前記従来技術では、レベリング修正動作を選択スイッチで選択するようにし、レベリング修正を別途行うようにしているが、ブーム上げの動作時の速度やリフト能力については特に考慮されていない。
本発明は、このような従来技術の実情に鑑みてなされたもので、その目的は、ブーム上げの動作速度を従来より遅くすることなく、リフト能力の高い油圧作業機の油圧制御装置を提供することにある。Conventionally, as a hydraulic working machine, a vehicle for cargo handling work or an aerial work vehicle called a lift truck is known. As an aerial work vehicle, for example, an apparatus as disclosed in Patent Document 1 of Registered Utility Model No. 2566631 is known.
In a hydraulic working machine such as an aerial work vehicle or a lift truck of this type, importance is attached to the lift capacity, that is, the performance of how many heavy objects can be lifted. In order to increase the lift capacity of the hydraulic working machine, generally, a means is adopted in which a hydraulic cylinder having a larger pressure receiving area is used as the undulating cylinder.
However, since the force that can be generated by the hydraulic cylinder is expressed as pressure receiving area x pressure, if a hydraulic cylinder with a large pressure receiving area is used, the lift capacity of the hydraulic working machine can be improved. Therefore, when a hydraulic cylinder having a large pressure receiving area is used, the boom raising speed is reduced. In addition, since the hydraulic cylinder becomes more expensive as the pressure receiving area becomes larger, the use of a hydraulic cylinder having a larger pressure receiving area causes a disadvantage that the cost of the hydraulic working machine increases.
In the prior art, the leveling correction operation is selected by the selection switch, and the leveling correction is separately performed. However, the speed and the lift capability during the boom raising operation are not particularly taken into consideration.
The present invention has been made in view of the actual situation of the prior art as described above, and an object thereof is to provide a hydraulic control device for a hydraulic working machine having a high lift capacity without slowing down the boom raising operation speed. There is.

前記目的を達成するため、第１の手段は、一端が回動端として固定側に回動可能に取り付けられたブームと、前記ブームの他端側を自由端として起伏方向に回動させる第１のシリンダと、前記ブームの自由端側の先端部に回動可能に取り付けられたアタッチメントと、前記ブームに対して前記アタッチメントを上下方向に回動させる第２のシリンダと、前記ブームの起伏動作に連動して伸縮し、前記ブームの起伏角度の変化に応じて前記アタッチメントの上下方向の角度を予め設定した角度に保持する第３のシリンダと、前記第１及び第２のシリンダにそれぞれ圧油を供給する油圧ポンプと、当該油圧ポンプから前記第１及び第２のシリンダにそれぞれ供給される圧油の流れを制御する方向制御弁と、当該方向制御弁を切換操作する操作装置とを備えた油圧作業機の油圧制御装置において、ブーム上げ操作時における前記第１のシリンダの作動圧が予め設定した圧力よりも高くなったときに、前記第１のシリンダの伸び動作を行わせる側と前記第３のシリンダの伸び動作を行わせる側とを連通させる手段を備えていることを特徴とする。
第２の手段は、第１の手段において、前記連通させる手段が、前記第１のシリンダの伸び動作を行わせる側に接続された第１の管路および前記第３のシリンダの伸び動作を行わせる側に接続された第２の管路を接続する第３の管路に設けられていることを特徴とする。
第３の手段は、第２の手段において、前記連通させる手段が、前記第３の管路に設けられた第１の切換弁と、ブーム上げ操作を行う前記操作装置の操作に応じて切り換えられ、前記第１の管路の圧力を前記第１の切換弁のパイロットポートに導く第２の切換弁とからなることを特徴とする。
第４の手段は、第３の手段において、前記操作装置が油圧パイロット式の操作装置であり、前記第２の切換弁は前記パイロットポートに前記油圧パイロット圧を導き、前記第１の切換弁の切換を行うことを特徴とする。
第５の手段は、第１の手段において、前記ブームが２段以上の伸縮機構を備えていることを特徴とする。
第６の手段は、第１の手段において、前記アタッチメントが、ホーク、バスケットおよびバケットの１つを含むことを特徴とする。
第７の手段は、第１の手段において、前記固定側が前記油圧作業機の本体部であることを特徴とする。
第８の手段は、第１ないし第７のいずれかの手段において、前記油圧作業機がリフトトラックおよび高所作業車のいずれかを含むことを特徴とする。
なお、以下の実施形態において、第１のシリンダは起伏シリンダ７に、第２のシリンダはチルトシリンダ８に、第３のシリンダはレベリングシリンダ９に、連通する手段は第１及び第２切換弁２１，２０に、油圧ポンプは符号１０に、方向制御弁は符号１１に、操作装置は符号１３に、第１の切換弁は第１切換弁２１に、第２の切換弁は第２切換弁２０に、第１の管路は管路３５に、第２の管路は管路３３に、第３の管路は管路３７に、第１の切換弁のパイロットポートは符号２１ｄにそれぞれ対応する。
本発明によれば、ブーム上げ操作時において第１のシリンダの作動圧が予め設定した圧力よりも高くなったときに油圧ポンプから吐出された圧油が第１のシリンダの伸び動作側及び第３のシリンダの伸び動作側の双方に供給されるので、第３のシリンダの伸張力もブームを回動させる駆動力として利用でき、油圧作業機のリフト能力を高めることができる。In order to achieve the above object, the first means includes a boom having one end pivotably attached to the fixed side and a first end that pivots in the undulation direction with the other end of the boom as a free end. A second cylinder for rotating the attachment in the vertical direction with respect to the boom, and a boom raising and lowering operation. A third cylinder that expands and contracts in conjunction with each other and holds the vertical angle of the attachment at a preset angle in accordance with a change in the boom undulation angle, and pressure oil is respectively applied to the first and second cylinders. Hydraulic pump to be supplied, directional control valve for controlling the flow of pressure oil respectively supplied from the hydraulic pump to the first and second cylinders, and an operating device for switching the directional control valve In the hydraulic control device for a hydraulic working machine having the above-described configuration, when the operating pressure of the first cylinder at the time of boom raising operation becomes higher than a preset pressure, the first cylinder is extended. And means for communicating with the side of the third cylinder on which the extension operation is performed.
In the second means, in the first means, the means for communicating performs the extension operation of the first pipe line and the third cylinder connected to the side on which the extension operation of the first cylinder is performed. It is provided in the 3rd pipe line which connects the 2nd pipe line connected to the side to make.
According to a third means, in the second means, the means for communicating is switched according to an operation of the first switching valve provided in the third pipe line and the operation device for performing a boom raising operation. And a second switching valve for guiding the pressure of the first pipe line to the pilot port of the first switching valve.
According to a fourth means, in the third means, the operating device is a hydraulic pilot type operating device, the second switching valve guides the hydraulic pilot pressure to the pilot port, and the first switching valve Switching is performed.
The fifth means is characterized in that, in the first means, the boom is provided with a telescopic mechanism having two or more stages.
A sixth means is characterized in that, in the first means, the attachment includes one of a hawk, a basket and a bucket.
The seventh means is characterized in that, in the first means, the fixed side is a main body of the hydraulic working machine.
The eighth means is characterized in that, in any one of the first to seventh means, the hydraulic working machine includes either a lift truck or an aerial work vehicle.
In the following embodiments, the first cylinder is the undulating cylinder 7, the second cylinder is the tilt cylinder 8, the third cylinder is the leveling cylinder 9, and the means for communication is the first and second switching valves 21. , 20, the hydraulic pump is indicated by reference numeral 10, the directional control valve is indicated by reference numeral 11, the operating device is indicated by reference numeral 13, the first switching valve is indicated by reference numeral 21, and the second switching valve is indicated by reference numeral 20. The first pipe corresponds to the pipe 35, the second pipe corresponds to the pipe 33, the third pipe corresponds to the pipe 37, and the pilot port of the first switching valve corresponds to the reference numeral 21d. .
According to the present invention, when the operating pressure of the first cylinder becomes higher than a preset pressure during the boom raising operation, the pressure oil discharged from the hydraulic pump is increased by the first cylinder extending operation side and the third cylinder. Therefore, the extension force of the third cylinder can also be used as a driving force for rotating the boom, and the lift capability of the hydraulic working machine can be enhanced.

図１は本発明の実施形態に係る油圧作業機に備えられる油圧回路の回路図である。
図２は本発明の実施形態に係る油圧作業機の一例を示す側面図である。FIG. 1 is a circuit diagram of a hydraulic circuit provided in a hydraulic working machine according to an embodiment of the present invention.
FIG. 2 is a side view showing an example of the hydraulic working machine according to the embodiment of the present invention.

以下、本発明を実施するための最良の形態について、図面を参照して説明する。
図２は本発明の実施形態に係る油圧作業機としてのリフトトラックの一例を示す図である。この図より明らかなように、本実施形態に係るリフトトラックは、前輪２、後輪３及び運転席４を有する車体１と、車体１に一端が回動可能に取り付けられた伸縮可能なブーム５と、ブーム５の先端部に回動可能に取り付けられたフォークなどのアタッチメント６と、車体１とブーム５との間に設置され、車体１に対してブーム５を起伏方向（Ａ−Ｂ方向）に回動させる起伏シリンダ７と、ブーム５とアタッチメント６との間に設置され、ブーム５に対してアタッチメント６をチルト方向（Ｃ−Ｄ方向）に回動させるチルトシリンダ８と、車体１とブーム５との間に設置され、ブーム５の起伏動作に連動して伸縮されるレベリングシリンダ９とを備えている。
レベリングシリンダ９は、車体１に対するブーム５の起伏角度が変更された場合にも、車体１に対するアタッチメント６の上下方向の相対的な角度（チルト角度）を予め設定した角度に保つためのものであって、チルトシリンダ８と図示しない管路を介して接続されており、ブーム５が起伏操作されたとき、レベリングシリンダ９から押し出された圧油をチルトシリンダ８に供給して、ブーム５に対するアタッチメント６のチルト角度を変更するようになっている。なお、この実施形態では、アタッチメント６として荷を運ぶフォークを例示しているが、その他に、土砂の掘削や整地を行うバケット、あるいは荷や人を上方に運ぶバスケットなどが使用される。
図１に前記構成のリフトトラックに備えられる油圧回路の回路図を示す。なお、図１の回路図においては、本発明の説明に直接関係がないため、ブーム５を伸縮させるための油圧回路が省略されているが、ブーム５は複数段、例えば５段で伸縮可能となっている。
図１より明らかなように、本実施形態に係る油圧回路は、油圧源である油圧ポンプ１０と、油圧ポンプ１０より起伏シリンダ７に供給される圧油の流れを制御する方向制御弁１１と、油圧ポンプ１０よりチルトシリンダ８に供給される圧油の流れを制御する方向制御弁１２と、方向制御弁１１の操作装置１３と、方向制御弁１２の操作装置１４と、方向制御弁１１と起伏シリンダ７とを接続する管路３５，３６と、管路３５（起伏シリンダ７の伸び動作側管路）に設けられたカウンターバランス弁１５と、方向制御弁１２とチルトシリンダ８とを接続する管路３１，３２と、管路３１（チルトシリンダ８の伸び動作側管路）に設けられたカウンターバランス弁１６と、管路３１とレベリングシリンダ９のボトム室９ａとを接続する管路（レベリングシリンダ９の伸び動作側管路）３３と、管路３２とレベリングシリンダ９のロッド室９ｂとを接続する管路３４と、油圧ポンプ１０の出口管路３０とタンク１８とを接続する管路に設けられたリリーフ弁１７とから構成されており、操作装置１３，１４は、それぞれ操作レバー１３ａ、１４ａと、減圧弁１３ｂ，１４ｂと、パイロット圧を供給するパイロットポンプ４０とから構成されている。
本実施形態では、起伏シリンダ７の伸び動作側管路３５とレベリングシリンダ９の伸び動作側管路３３とを接続する管路３７が設けられ、この管路３７には、第１切換弁２１と、操作装置１３のブーム上げ操作によって切り換えられ、第１切換弁２１のパイロットポート２１ｄに起伏シリンダ７の伸び動作側管路３５の圧力を供給する第２切換弁２０とが設けられている。なお、第１切換弁２１に備えられた戻しばね２１ｃによって設定される第１切換弁２１の設定圧、もしくは切換設定圧は、リリーフ弁１７の設定圧よりもやや低い値に設定される。なお、特許請求の範囲にいう連通する手段は、前記第１切換弁２１と前記第２切換弁２０との組合せから構成されている。
オペレータが操作レバー１４ａを操作し、パイロットポート１２ｄにパイロット圧を供給して方向切換弁１２を中立位置１２ｂから位置１２ａに切り換えると、油圧ポンプ１０から吐出された圧油が管路３０、方向切換弁１２及び管路３２を通ってチルトシリンダ８のロッド室８ｂに供給されるので、チルトシリンダ８が縮み方向に動作し、アタッチメント６が下げ方向（Ｄ方向）に回動する。チルトシリンダ８の縮み動作に伴ってチルトシリンダ８のボトム室８ａから押し出された作動油は、カウンターバランス弁１６、管路３１及び方向切換弁１２を通ってタンク１８に戻される。
これに対して、オペレータが操作レバー１４ａを操作し、パイロットポート１２ｅにパイロット圧を供給して方向切換弁１２を位置１２ｃに切り換えた場合には、油圧ポンプ１０から吐出された圧油が管路３０、方向切換弁１２、管路３１及びカウンターバランス弁１６に設けられた逆止弁１６ａを通ってチルトシリンダ８のボトム室８ａに供給されるので、チルトシリンダ８が伸び方向に動作し、アタッチメント６が上げ方向（Ｃ方向）に回動する。チルトシリンダ８の伸び動作に伴ってチルトシリンダ８のロッド室８ｂから押し出された作動油は、管路３２及び方向切換弁１２を通ってタンク１８に戻される。
また、オペレータが操作レバー１３ａを操作し、パイロットポート１１ｄにパイロット圧を供給し、方向切換弁１１を中立位置１１ｂから位置１１ａに切り換えると、油圧ポンプ１０から吐出された圧油が管路３０、方向切換弁１１、管路３５、カウンターバランス弁１５に設けられた逆止弁１５ａを通って起伏シリンダ７のボトム室７ａに供給されるので、起伏シリンダ７が伸び方向に動作し、ブーム５が上げ方向（Ａ方向）に回動する。起伏シリンダ７の伸び動作に伴って起伏シリンダ７のロッド室７ｂから押し出された作動油は、管路３６、方向切換弁１１を通ってタンク１８に戻される。ブーム５が上げ方向に回動されると、レベリングシリンダ９が強制的に伸ばされ、レベリングシリンダ９のロッド室９ｂから作動油が押し出されるので、その作動油が管路３４及び管路３２を通ってチルトシリンダ８のロッド室８ｂに流入し、チルトシリンダ８が縮み方向に動作して、アタッチメント６が下げ方向（Ｄ方向）に回動する。チルトシリンダ８の縮み動作に伴ってチルトシリンダ８のボトム室８ａから押し出された作動油は、カウンターバランス弁１６、管路３１及び管路３３を介してレベリングシリンダ９のボトム室９ａに導かれる。その結果、ブーム５の上げ操作に応じて、車体１に対するアタッチメント６の上下方向の相対的な角度が変更され、自動的にブーム上げ操作前の状態に保持される。
ブーム上げ用のパイロット圧が第２切換弁２０のパイロットポート２０ｄに作用していない場合、第２切換弁２０は位置２０ａに保持される。このとき、第１切換弁２１のパイロットポート２１ｄにはタンク圧しか作用しないので、第１切換弁２１は位置２１ａに保持され、管路３１と管路３７とが遮断されると共に管路３１と管路３３とが第１切換弁２１を介して連通される。
これに対して、オペレータが操作レバー１３ａを操作し、パイロットポート１１ｅにパイロット圧を供給し、方向切換弁１１を室１１ｃに切り換えた場合には、油圧ポンプ１０から吐出された圧油が管路３０、方向切換弁１１及び管路３６を通って起伏シリンダ７のロッド室７ｂに供給されるので、起伏シリンダ７が縮み方向に動作し、ブーム５が下げ方向（Ｂ方向）に回動する。起伏シリンダ７の縮み動作に伴って起伏シリンダ７のボトム室７ａから押し出された作動油は、カウンターバランス弁１５、管路３５及び方向切換弁１１を通ってタンク１８に戻される。ブーム５が下げ方向に回動されると、レベリングシリンダ９が強制的に縮められ、レベリングシリンダ９のボトム室９ａから作動油が押し出されるので、その作動油が管路３３、管路３１及びカウンターバランス弁１６の逆止弁１６ａを通ってチルトシリンダ８のボトム室８ａに流入し、チルトシリンダ８が伸び方向に動作して、アタッチメント６が上げ方向（Ｃ方向）に回動する。チルトシリンダ８の伸び動作に伴ってチルトシリンダ８のロッド室８ｂから押し出された作動油は、管路３２及び管路３４を介してレベリングシリンダ９のロッド室９ｂに導かれる。その結果、ブーム５の下げ操作に関わりなく、車体１に対するアタッチメント６のチルト角度が自動的にブーム上げ操作前の状態に保たれる。
オペレータによりブーム上げ操作が行われると、操作装置１３からのパイロット圧により方向切換弁１１が位置１１ａに切り換えられると共に第２切換弁２０が位置２０ｂに切り換えられる。これにより、油圧ポンプ１０から吐出された圧油が管路３０、方向切換弁１１、管路３５、カウンターバランス弁１５の逆止弁１５ａを通って起伏シリンダ７のボトム室７ａに供給されると共に、第２切換弁２０が位置２０ｂに切り換えられていることから、管路３５の圧力（起伏シリンダ７の作動圧）が管路３７を介して第１切換弁２１のパイロットポート２１ｄにも作用する。起伏シリンダ７の作動圧は、アタッチメント６によって持ち上げようとする荷物の重量が大きいほど大きくなる。
起伏シリンダ７の作動圧が第１切換弁２１の設定圧よりも低い場合には、第１切換弁２１が位置２１ａに保持されるので、管路３１と管路３７との遮断状態及び管路３１と管路３３との連通状態が維持される。したがって、この場合にも、前記の手順でブーム５の上げ操作及びブーム５の上げ操作に伴うアタッチメント６のチルト角度の調整操作が行われる。
起伏シリンダ７の作動圧が第１切換弁２１の設定圧よりも高い場合には、第１切換弁２１が位置２１ｂに切り換えられるので、管路３３と管路３５とが管路３７を介して接続されると共に、管路３１とタンク１８とが接続される。このため、油圧ポンプ１０から吐出された圧油が管路３０、方向切換弁１１、管路３５を通って起伏シリンダ７のボトム室７ａに供給されると共に、管路３５中の圧油の一部が管路３７、切換弁２１、管路３３を通ってレベリングシリンダ９のボトム室９ａに供給される。これにより、起伏シリンダ７とレベリングシリンダ９の双方に伸び方向の力が生じ、これらがブーム５を上げ方向に回動させる力として作用するので、起伏シリンダ単独でブーム５を上げ方向に回動させる場合に比べて、油圧作業機のリフト能力が高められる。
なお、本実施形態では操作装置１３，１４は油圧パイロット方式のものを例示しているが、電気操作式のものを使用することもできる。この場合には、操作レバー１３ａの操作により電気信号が出力され、操作レバー１３ａの操作によって出力された電気信号によって第２切換弁２０を切り換えるように構成する。
また、図１の構成において、方向制御弁１１のブーム上げ側へ切り換える側のパイロットポート１１ｄに接続されたパイロット回路に圧力検出器を設け、この圧力検出器により圧力変換を検出し、その検出信号（電気信号）を例えば電気油圧変換弁により圧力に変換して第２切換弁２０のパイロットポート２０ｄに導いて第２切換弁２０を切り換えるように構成することもできる。
さらに、本実施形態では、第１及び第２切換弁２１，２０によって管路３７を連通させる切換手段を構成しているが、管路３７と、方向制御弁１１をブーム上げ側へ切り換える側のパイロットポート１１ｄに接続されたパイロット回路とにそれぞれ圧力検出器を配置し、管路３７の圧力が予め設定した圧力より大きく、かつ、方向制御弁１１がブーム上げ側に切り換わったことをそれぞれの圧力検出器からの信号によって制御装置が検出したときに、当該制御装置からの制御信号によって第１切換弁２１を切り換えるように構成することもできる。なお、この切り換えは、前記制御装置からの制御信号を例えば電気油圧変換弁により圧力に変換し、第１切換弁２１のパイロットポート２１ｄに圧力を印加することにより行われる。
このように、本実施形態に係る油圧作業機は、起伏シリンダ７の伸び動作側管路３５とレベリングシリンダ９の伸び動作側管路３３とを接続する管路３７に予め設定された圧力値で管路３５，３３との連通状態を変更する手段（切換弁２０，２１）を備え、ブーム上げ操作時における起伏シリンダ７の作動圧が回路切換手段の設定圧よりも高くなったときに各伸び動作側管路３３，３５が連通されて、油圧ポンプ１０から吐出された圧油が起伏シリンダ７の伸び動作側及びレベリングシリンダ９の伸び動作側の双方に供給されるようにしたので、レベリングシリンダ９の伸張力もブームを回動させる駆動力として利用することが可能となり、これにより油圧作業機のリフト能力を高めることができる。
また、油圧作業機のリフト能力を犠牲にすることなく起伏シリンダ７の受圧面積の小型化を図ることが可能となり、これにより油圧作業機の低コスト化を図ることができる。
さらに、本例の油圧作業機は、油圧ポンプ１０から吐出された圧油をレベリングシリンダ９に供給するための手段を２つの切換弁２０，２１によって構成したので、汎用品の組合せで構成することが可能となる。
なお、前記連通させる手段は、本実施形態では第１切換弁２１および第２切換弁２０によって構成されているが、ブーム上げ操作時における第１のシリンダの作動圧が予め設定した圧力よりも高くなったときに、第１のシリンダの伸び動作を行わせる側と第３のシリンダの伸び動作を行わせる側とを連通させる機能を備えていれば前記切換弁２１，２０の組み合わせに限定されるものではなく、必要に応じて適宜設計することができる。The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 2 is a view showing an example of a lift truck as a hydraulic working machine according to the embodiment of the present invention. As is apparent from this figure, the lift truck according to the present embodiment includes a vehicle body 1 having front wheels 2, a rear wheel 3, and a driver's seat 4, and an extendable boom 5 having one end rotatably attached to the vehicle body 1. And an attachment 6 such as a fork that is rotatably attached to the tip of the boom 5, and the vehicle body 1 and the boom 5. The boom 5 is raised and lowered with respect to the vehicle body 1 (AB direction). A tilt cylinder 8 that is rotated between the boom 5 and the attachment 6, and a tilt cylinder 8 that rotates the attachment 6 in the tilt direction (CD direction) relative to the boom 5, the vehicle body 1 and the boom. 5 and a leveling cylinder 9 that is expanded and contracted in conjunction with the hoisting operation of the boom 5.
The leveling cylinder 9 is used to keep the relative angle (tilt angle) in the vertical direction of the attachment 6 with respect to the vehicle body 1 at a preset angle even when the hoisting angle of the boom 5 with respect to the vehicle body 1 is changed. Thus, when the boom 5 is raised and lowered, the pressure oil pushed out from the leveling cylinder 9 is supplied to the tilt cylinder 8 and the attachment 6 to the boom 5 is connected. The tilt angle is changed. In this embodiment, a fork for carrying a load is illustrated as the attachment 6, but a bucket for excavating or leveling soil or a basket for carrying a load or a person upward is also used.
FIG. 1 is a circuit diagram of a hydraulic circuit provided in the lift truck having the above configuration. In the circuit diagram of FIG. 1, the hydraulic circuit for extending and retracting the boom 5 is omitted because it is not directly related to the description of the present invention. However, the boom 5 can be expanded and contracted in a plurality of stages, for example, 5 stages. It has become.
As is clear from FIG. 1, the hydraulic circuit according to the present embodiment includes a hydraulic pump 10 that is a hydraulic source, a directional control valve 11 that controls the flow of pressure oil supplied from the hydraulic pump 10 to the undulation cylinder 7, Direction control valve 12 for controlling the flow of pressure oil supplied from hydraulic pump 10 to tilt cylinder 8, operation device 13 for direction control valve 11, operation device 14 for direction control valve 12, direction control valve 11 and undulation Pipe lines 35, 36 connecting the cylinder 7, a counter balance valve 15 provided in the pipe line 35 (extraction operation side pipe line of the hoisting cylinder 7), a pipe connecting the direction control valve 12 and the tilt cylinder 8. The pipes 31 and 32, the counterbalance valve 16 provided in the pipe 31 (the extension operation side pipe of the tilt cylinder 8), and the pipe (level) connecting the pipe 31 and the bottom chamber 9a of the leveling cylinder 9 are connected. A pipe 34 connecting the pipe 32 and the rod chamber 9 b of the leveling cylinder 9, a pipe connecting the outlet pipe 30 of the hydraulic pump 10 and the tank 18. The operation devices 13 and 14 are each composed of operation levers 13a and 14a, pressure reducing valves 13b and 14b, and a pilot pump 40 for supplying pilot pressure. .
In the present embodiment, a pipe line 37 is provided for connecting the extension operation side pipe line 35 of the hoisting cylinder 7 and the extension operation side pipe line 33 of the leveling cylinder 9, and the pipe 37 includes the first switching valve 21 and the pipe 37. There is provided a second switching valve 20 that is switched by the boom raising operation of the operating device 13 and supplies the pressure of the expansion operation side pipe line 35 of the hoisting cylinder 7 to the pilot port 21d of the first switching valve 21. Note that the set pressure or the switch set pressure of the first switch valve 21 set by the return spring 21 c provided in the first switch valve 21 is set to a value slightly lower than the set pressure of the relief valve 17. Note that the communicating means in the claims is composed of a combination of the first switching valve 21 and the second switching valve 20.
When the operator operates the operating lever 14a to supply pilot pressure to the pilot port 12d and switch the direction switching valve 12 from the neutral position 12b to the position 12a, the pressure oil discharged from the hydraulic pump 10 is switched to the line 30 and direction. Since it is supplied to the rod chamber 8b of the tilt cylinder 8 through the valve 12 and the pipe line 32, the tilt cylinder 8 operates in the contraction direction, and the attachment 6 rotates in the lowering direction (D direction). The hydraulic oil pushed out from the bottom chamber 8 a of the tilt cylinder 8 in accordance with the contraction operation of the tilt cylinder 8 is returned to the tank 18 through the counter balance valve 16, the pipe line 31 and the direction switching valve 12.
On the other hand, when the operator operates the operation lever 14a to supply pilot pressure to the pilot port 12e and switch the direction switching valve 12 to the position 12c, the pressure oil discharged from the hydraulic pump 10 is connected to the pipeline. 30, the direction switching valve 12, the pipe line 31, and the check valve 16a provided in the counter balance valve 16 are supplied to the bottom chamber 8a of the tilt cylinder 8, so that the tilt cylinder 8 operates in the extending direction and is attached. 6 rotates in the raising direction (C direction). The hydraulic oil pushed out from the rod chamber 8 b of the tilt cylinder 8 along with the extension operation of the tilt cylinder 8 is returned to the tank 18 through the pipe line 32 and the direction switching valve 12.
Further, when the operator operates the operation lever 13a to supply pilot pressure to the pilot port 11d and switch the direction switching valve 11 from the neutral position 11b to the position 11a, the pressure oil discharged from the hydraulic pump 10 is supplied to the pipe line 30; Since the directional switching valve 11, the pipe line 35, and the check valve 15 a provided in the counter balance valve 15 are supplied to the bottom chamber 7 a of the undulating cylinder 7, the undulating cylinder 7 operates in the extending direction, and the boom 5 It rotates in the raising direction (A direction). The hydraulic oil pushed out from the rod chamber 7 b of the hoisting cylinder 7 as the hoisting cylinder 7 extends is returned to the tank 18 through the pipe 36 and the direction switching valve 11. When the boom 5 is rotated in the raising direction, the leveling cylinder 9 is forcibly extended and the hydraulic oil is pushed out from the rod chamber 9b of the leveling cylinder 9, so that the hydraulic oil passes through the pipe line 34 and the pipe line 32. Then, it flows into the rod chamber 8b of the tilt cylinder 8, the tilt cylinder 8 operates in the contracting direction, and the attachment 6 rotates in the lowering direction (D direction). The hydraulic oil pushed out from the bottom chamber 8a of the tilt cylinder 8 with the contraction operation of the tilt cylinder 8 is guided to the bottom chamber 9a of the leveling cylinder 9 through the counter balance valve 16, the pipe line 31 and the pipe line 33. As a result, the relative angle in the vertical direction of the attachment 6 with respect to the vehicle body 1 is changed according to the raising operation of the boom 5 and is automatically held in the state before the boom raising operation.
When the pilot pressure for raising the boom does not act on the pilot port 20d of the second switching valve 20, the second switching valve 20 is held at the position 20a. At this time, since only the tank pressure acts on the pilot port 21d of the first switching valve 21, the first switching valve 21 is held at the position 21a, the line 31 and the line 37 are shut off, and the line 31 and The pipe 33 is communicated with the first switching valve 21.
On the other hand, when the operator operates the operation lever 13a to supply pilot pressure to the pilot port 11e and switch the direction switching valve 11 to the chamber 11c, the pressure oil discharged from the hydraulic pump 10 is connected to the pipeline. 30, the direction switching valve 11 and the pipe 36 are supplied to the rod chamber 7b of the hoisting cylinder 7, so that the hoisting cylinder 7 operates in the contracting direction and the boom 5 rotates in the lowering direction (B direction). The hydraulic oil pushed out from the bottom chamber 7 a of the hoisting cylinder 7 in accordance with the shrinking operation of the hoisting cylinder 7 is returned to the tank 18 through the counter balance valve 15, the pipe 35 and the direction switching valve 11. When the boom 5 is rotated in the lowering direction, the leveling cylinder 9 is forcibly contracted and the hydraulic oil is pushed out from the bottom chamber 9a of the leveling cylinder 9, so that the hydraulic oil is supplied to the pipe 33, the pipe 31 and the counter. The gas flows into the bottom chamber 8a of the tilt cylinder 8 through the check valve 16a of the balance valve 16, the tilt cylinder 8 operates in the extending direction, and the attachment 6 rotates in the raising direction (C direction). The hydraulic oil pushed out from the rod chamber 8b of the tilt cylinder 8 along with the extending operation of the tilt cylinder 8 is guided to the rod chamber 9b of the leveling cylinder 9 through the pipe line 32 and the pipe line 34. As a result, irrespective of the lowering operation of the boom 5, the tilt angle of the attachment 6 with respect to the vehicle body 1 is automatically maintained in the state before the boom raising operation.
When the boom raising operation is performed by the operator, the direction switching valve 11 is switched to the position 11a and the second switching valve 20 is switched to the position 20b by the pilot pressure from the operating device 13. As a result, the pressure oil discharged from the hydraulic pump 10 is supplied to the bottom chamber 7a of the hoisting cylinder 7 through the conduit 30, the direction switching valve 11, the conduit 35, and the check valve 15a of the counter balance valve 15. Since the second switching valve 20 is switched to the position 20b, the pressure in the pipeline 35 (the operating pressure of the undulating cylinder 7) also acts on the pilot port 21d of the first switching valve 21 via the pipeline 37. . The operating pressure of the hoisting cylinder 7 increases as the weight of the load to be lifted by the attachment 6 increases.
When the operating pressure of the hoisting cylinder 7 is lower than the set pressure of the first switching valve 21, the first switching valve 21 is held at the position 21 a, so that the disconnection state between the pipeline 31 and the pipeline 37 and the pipeline The communication state of 31 and the pipe line 33 is maintained. Therefore, also in this case, the operation for raising the boom 5 and the operation for adjusting the tilt angle of the attachment 6 accompanying the operation for raising the boom 5 are performed according to the above-described procedure.
When the operating pressure of the hoisting cylinder 7 is higher than the set pressure of the first switching valve 21, the first switching valve 21 is switched to the position 21 b, so that the pipe line 33 and the pipe line 35 are connected via the pipe line 37. In addition to being connected, the conduit 31 and the tank 18 are connected. For this reason, the pressure oil discharged from the hydraulic pump 10 is supplied to the bottom chamber 7 a of the hoisting cylinder 7 through the pipe line 30, the direction switching valve 11, and the pipe line 35. The portion is supplied to the bottom chamber 9 a of the leveling cylinder 9 through the pipe 37, the switching valve 21 and the pipe 33. As a result, an extending force is generated in both the hoisting cylinder 7 and the leveling cylinder 9, and these act as a force for rotating the boom 5 in the raising direction. Therefore, the hoisting cylinder alone rotates the boom 5 in the raising direction. Compared to the case, the lifting capacity of the hydraulic working machine is increased.
In the present embodiment, the operation devices 13 and 14 are exemplified by a hydraulic pilot type, but an electric operation type can also be used. In this case, an electric signal is output by operating the operating lever 13a, and the second switching valve 20 is switched by the electric signal output by operating the operating lever 13a.
In the configuration of FIG. 1, a pressure detector is provided in a pilot circuit connected to the pilot port 11d on the side of switching to the boom raising side of the directional control valve 11, pressure conversion is detected by this pressure detector, and the detection signal (Electric signal) may be converted into pressure by, for example, an electrohydraulic conversion valve and guided to the pilot port 20d of the second switching valve 20 to switch the second switching valve 20.
Further, in the present embodiment, the switching means for communicating the pipe line 37 with the first and second switching valves 21 and 20 is configured. On the side where the pipe line 37 and the direction control valve 11 are switched to the boom raising side. A pressure detector is disposed in each of the pilot circuits connected to the pilot port 11d, the pressure in the pipe line 37 is greater than a preset pressure, and the direction control valve 11 is switched to the boom raising side. When the control device detects a signal from the pressure detector, the first switching valve 21 can be switched by the control signal from the control device. This switching is performed by converting a control signal from the control device into a pressure by, for example, an electrohydraulic conversion valve, and applying a pressure to the pilot port 21d of the first switching valve 21.
Thus, the hydraulic working machine according to the present embodiment has a pressure value set in advance in the pipe line 37 that connects the extension operation side pipe line 35 of the hoisting cylinder 7 and the extension operation side pipe line 33 of the leveling cylinder 9. Means (switching valves 20, 21) for changing the state of communication with the pipes 35, 33 are provided, and each expansion is performed when the operating pressure of the hoisting cylinder 7 during the boom raising operation becomes higher than the set pressure of the circuit switching means. Since the operating side conduits 33 and 35 are communicated with each other, the pressure oil discharged from the hydraulic pump 10 is supplied to both the extending operation side of the hoisting cylinder 7 and the extending operation side of the leveling cylinder 9. The extension force of 9 can also be used as a driving force for rotating the boom, whereby the lift capacity of the hydraulic working machine can be increased.
In addition, it is possible to reduce the pressure receiving area of the hoisting cylinder 7 without sacrificing the lift capacity of the hydraulic working machine, thereby reducing the cost of the hydraulic working machine.
Furthermore, in the hydraulic working machine of this example, the means for supplying the pressure oil discharged from the hydraulic pump 10 to the leveling cylinder 9 is constituted by the two switching valves 20 and 21, so that it is constituted by a combination of general-purpose products. Is possible.
The communicating means is constituted by the first switching valve 21 and the second switching valve 20 in this embodiment, but the operating pressure of the first cylinder during the boom raising operation is higher than a preset pressure. If it has the function which connects the side which performs the extending operation of the 1st cylinder, and the side which performs the extending operation of the 3rd cylinder when it becomes, it is limited to the combination of the said switching valves 21 and 20. It is not a thing and can be designed suitably as needed.

Claims (8)

一端が固定側に回動可能に取り付けられたブームと、
前記ブームの他端側を自由端として起伏方向に回動させる第１のシリンダと、
前記ブームの先端部に回動可能に取り付けられたアタッチメントと、
前記ブームに対して前記アタッチメントを上下方向に回動させる第２のシリンダと、
前記ブームの起伏動作に連動して伸縮し、前記ブームの起伏角度の変化に応じて前記アタッチメントの上下方向の角度を予め設定した角度に保持する第３のシリンダと、
前記第１及び第２のシリンダにそれぞれ圧油を供給する油圧ポンプと、
当該油圧ポンプから前記第１及び第２のシリンダにそれぞれ供給される圧油の流れを制御する方向制御弁と、
当該方向制御弁を切換操作する操作装置と、
を備えた油圧作業機の油圧制御装置において、
ブーム上げ操作時における前記第１のシリンダの作動圧が予め設定した圧力よりも高くなったときに、前記第１のシリンダの伸び動作を行わせる側と前記第３のシリンダの伸び動作を行わせる側とを連通させる手段を備えていることを特徴とする油圧作業機の油圧制御装置。A boom with one end pivotably attached to the fixed side;
A first cylinder that rotates in the undulation direction with the other end of the boom as a free end;
An attachment rotatably attached to the tip of the boom;
A second cylinder for vertically rotating the attachment relative to the boom;
A third cylinder that expands and contracts in conjunction with the boom hoisting operation, and holds the vertical angle of the attachment at a preset angle in accordance with a change in the boom hoisting angle;
A hydraulic pump for supplying pressure oil to each of the first and second cylinders;
A directional control valve for controlling the flow of pressure oil respectively supplied from the hydraulic pump to the first and second cylinders;
An operating device for switching the direction control valve;
In the hydraulic control device of the hydraulic working machine with
When the operating pressure of the first cylinder at the time of boom raising operation becomes higher than a preset pressure, the extension operation of the first cylinder and the extension operation of the third cylinder are performed. A hydraulic control device for a hydraulic working machine, comprising means for communicating with the side. 前記連通させる手段が、
前記第１のシリンダの伸び動作を行わせる側に接続された第１の管路および前記第３のシリンダの伸び動作を行わせる側に接続された第２の管路を接続する第３の管路に設けられていることを特徴とする請求の範囲１記載の油圧作業機の油圧制御装置。The means for communicating is
A third pipe connecting a first pipe connected to the side of the first cylinder that performs the extending operation and a second pipe connected to the side of the third cylinder that performs the extending operation The hydraulic control device for a hydraulic working machine according to claim 1, wherein the hydraulic control device is provided on a road. 前記連通させる手段が、
前記第３の管路に設けられた第１の切換弁と、
ブーム上げ操作を行う前記操作装置の操作に応じて切り換えられ、前記第１の管路の圧力を前記第１の切換弁のパイロットポートに導く第２の切換弁と、
からなることを特徴とする請求の範囲２記載の油圧作業機の油圧制御装置。The means for communicating is
A first switching valve provided in the third pipeline;
A second switching valve that is switched according to an operation of the operating device that performs a boom raising operation, and that guides the pressure of the first pipe line to a pilot port of the first switching valve;
The hydraulic control device for a hydraulic working machine according to claim 2, characterized by comprising: 前記操作装置が油圧パイロット式の操作装置であり、前記第２の切換弁は前記パイロットポートに前記油圧パイロット圧を導き、前記第１の切換弁の切換を行うことを特徴とする請求の範囲３記載の油圧作業機の油圧制御装置。The operating device is a hydraulic pilot type operating device, and the second switching valve guides the hydraulic pilot pressure to the pilot port and switches the first switching valve. The hydraulic control apparatus of the hydraulic working machine as described. 前記ブームが２段以上の伸縮機構を備えていることを特徴とする請求の範囲１記載の油圧作業機の油圧制御装置。The hydraulic control device for a hydraulic working machine according to claim 1, wherein the boom is provided with two or more stages of telescopic mechanisms. 前記アタッチメントが、ホーク、バスケットおよびバケットの１つを含むことを特徴とする請求の範囲１記載の油圧作業機の油圧制御装置。The hydraulic control device for a hydraulic working machine according to claim 1, wherein the attachment includes one of a hawk, a basket, and a bucket. 前記固定側が前記油圧作業機の本体部に設けられていることを特徴とする請求の範囲１記載の油圧作業機の油圧制御装置。The hydraulic control device for a hydraulic working machine according to claim 1, wherein the fixed side is provided in a main body of the hydraulic working machine. 前記油圧作業機がリフトトラックおよび高所作業車のいずれかを含むことを特徴とする請求の範囲１ないし７のいずれか１に記載の油圧作業機の油圧制御装置。The hydraulic control device for a hydraulic working machine according to any one of claims 1 to 7, wherein the hydraulic working machine includes one of a lift truck and an aerial work vehicle.
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