JP2004278746A

JP2004278746A - Hydraulic operating device of construction machinery

Info

Publication number: JP2004278746A
Application number: JP2003073896A
Authority: JP
Inventors: Kazuaki Inoue; 和明井上
Original assignee: Hitachi Sumitomo Heavy Industries Construction Crane Co Ltd
Current assignee: Sumitomo Heavy Industries Construction Crane Co Ltd
Priority date: 2003-03-18
Filing date: 2003-03-18
Publication date: 2004-10-07

Abstract

<P>PROBLEM TO BE SOLVED: To prevent operation amount of an operation lever and movement of a machine from being affected by the rotation speed of an engine. <P>SOLUTION: In this hydraulic operating device of construction machinery, secondary pressure is generated in a proportional pressure reducing valve 5 by operation of the operation lever 4, a flow rate control valve 3 is controlled by this secondary pressure to supply delivery oil of a hydraulic pump 2 to an actuator. Solenoid proportional pressure reducing valves 11 and 21 are disposed in parallel with the proportional pressure reducing valve 5, the flow rate control valve 3 is controlled by high-pressure selecting the secondary pressure of the valve 5 and the secondary pressure of the valves 11 and 21, the secondary pressure of the valve 5 is detected by pressure sensors 10 and 20, and the rotation speed of the engine 1 is detected by a rotation sensor 30. When primary flow rate of the control valve 3 is maximum, based on the detection signals, a controller 40 controls the valves 11 and 21 so that the secondary pressure of the valve 5 is substantially equal to the secondary pressure of the valves 11 and 21. When primary flow rate of the control valve 3 is minimum, the controller 40 controls them so that the valves 11 and 21 generate the secondary pressure according to a predetermined function using the secondary pressure of the valve 5 as a parameter. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は建設機械の油圧操作装置に関するものであり、特に、操作レバーの操作量と機械の動きとの関係がエンジン回転数の影響を受けることを防止できるように構成した建設機械の油圧操作装置に関するものである。
【０００２】
【従来の技術及び発明が解決しようとする課題】
この種の建設機械の油圧操作装置として、特許文献１のようなものがある。
【０００３】
【特許文献１】特開平８−２８２９７８号公報
【０００４】
この特許文献１中の油圧操作装置に関する部分を概略記載したものを図４に示す。油圧操作装置は、図４に示すように、エンジン１と、エンジン１によって駆動される油圧ポンプ２と、油圧ポンプ２の吐出油を流量制御してアクチュエータへ供給する流量制御弁３と、操作レバー４の操作にて２次圧を発生し、この２次圧にて前記流量制御弁３を制御する比例減圧弁５とから構成されたものが知られている。なお、特許文献１中には記載されていないが、油圧ポンプ２は、通常、回転数を可変できる動力源であるエンジンによって駆動されるので、図４中にはエンジン１を記載している。
【０００５】
前記流量制御弁３のＰポートには、油圧ポンプ２から吐出された圧油が１次流量として供給される。また、比例減圧弁５のＰポートにはパイロット油圧ポンプ１５からの吐出油が供給され、操作レバー４の操作に応じて減圧されたパイロット２次圧がａ２またはｂ２ポートに発生する。例えば、流量制御弁３の油室ａ１に操作圧Ｐｉが入ると、スプールの移動により油圧ポンプ２から供給される圧油が１次流量として流量制御弁３のＡポートとＴポートに分流されてＡポートに２次流量が流れる。図５に模式的に示すように、流量制御弁３の内部にはスプールの移動量により変化する絞り６，７，８が形成されている。（絞り６は、ＰポートからＴポートへの油路に、絞り７は、ＰポートからＡポートへの油路に、絞り８は、ＢポートからＴポートへの油路にそれぞれ形成されている。）
【０００６】
次に、図６及び図７にて流量制御弁３の作動原理について説明する。流量制御弁３は、中立位置ではＰ→Ｔへの油路の絞り６が開放され、Ｐ→Ａ（又はＢ）への油路の絞り７及びＢ（又はＡ）→Ｔへの油路の絞り８は閉止している。流量制御弁３のスプールを移動させていくと、図６▲１▼に示すように、スプールの移動量（増加）に応じてＰ→Ｔへの油路の絞り６開口面積が減少していく。これと同時に、Ｐ→Ａ（又はＢ）への油路の絞り７及びＢ（又はＡ）→Ｔへの油路の絞り８は、同図▲２▼に示すように、開口面積が増加していく。この結果、流量制御弁３のＰポートに流入する１次流量は、中立位置では全量Ｔポートに流れるが、スプールの移動に伴いＰ→Ｔへの油路の絞り６が絞られていき、Ｐポートには絞り量に応じ圧力Ｐｐ（以下、ポンプ吐出圧という）が発生する。このポンプ吐出圧Ｐｐが、Ａ（又はＢ）ポートに接続した負荷が必要とする圧力Ｐａ（以下、負荷圧という）を超えると、ＰポートからＡ（又はＢ）ポートへ油が流れ始め、流量制御弁３に接続される不図示のアクチュエータが動作を開始する。
【０００７】
このＡ（又はＢ）ポートへの圧油の流れ始め（アクチュエータの動き始め）時点（Ａ又はＢポートへの流量は未だ０）のとき、発生する力と流量の関係は、次式のようになる。
Ｑ＝α・Ｆ√（２ｇ・ｐ／γ）
Ｑ；流量、α；流量係数、Ｆ；絞り開口面積、γ；油の比重量、ｇ；重力加速度、ｐ；差圧。
即ち、ポンプ吐出圧Ｐｐは１次流量Ｑｐの二乗に比例することが分かる。従って、１次流量Ｑｐが変化すると、同じスプール位置で発生する圧力Ｐｐが大きく変化することになり、負荷側が要求する圧力Ｐａを圧力Ｐｐが超えるときの絞り６の面積が、１次流量Ｑｐの関数として決まる。即ち、アクチュエータが動き始めるときのスプールの移動量は１次流量Ｑｐの関数として決定されることを意味する。ＰポートからＡポートへ油が流れると、絞り７による圧損が前述した式のように発生するため、Ｐｐ＝Ｐａでは実際には油は流れない。流れる油の量は、前述したように差庄ｐ（Ｐｐ−Ｐａ）と絞り７の面積の関数となるが、Ｐｐが１次流量Ｑｐの影響を強く受けるために、この流量もＱｐの影響を強く受ける。
【０００８】
以上の原理により、流量制御弁３のスプール移動量とアクチュエータの速度の関係を模式的に表すと、図７のようになり、流量制御弁３の１次流量Ｑｐが少ないときの特性は破線、１次流量Ｑｐが多いときの特性は実線で示すように、
（１）アクチュエータが動き出すときのスプール位置が１次流量Ｑｐの変化で大きく変動する。
（２）速度制御に使える範囲が少ない。（破線、実線の状態とも、スプール移動量の半分程度）
といった欠点がある。従って、操作レバー４の操作量と流量制御弁３のスプール移動量が略比例するため、上記の欠点は、
（１）アクチュエータが動き始めるときの操作レバー４の位置が、１次流量の変化で大きく変動する。とりわけ、Ｑｐが小流量の時に操作レバー４を大きく動かさないと動作しないという不具合がある。
（２）速度制御に使える操作レバーの範囲が少ない。
ということになり、操作性が悪かった。
【０００９】
流量制御弁３の１次流量Ｑｐは、油圧ポンプ２の吐出量に依存し、油圧ポンプ２の吐出量は、油圧ポンプ２を駆動するエンジン１の回転数に依存する。
そこで、操作レバー４の操作量とアクチュエータの動きとがエンジン１の回転数の影響を受けないようにするために解決すべき技術的課題が生じてくるのであり、本発明はこの課題を解決することを目的とする。
【００１０】
【課題を解決するための手段】
本発明の建設機械の油圧操作装置は、上記目的を達成するためになされたもので、請求項１に記載の発明は、回転数を可変できる動力源にて駆動される油圧ポンプと、前記油圧ポンプから吐出される圧油を流量制御してアクチュエータへ供給する流量制御弁と、操作レバーの操作にて２次圧を発生し、この２次圧にて前記流量制御弁を制御する比例減圧弁とからなる建設機械の油圧操作装置に適用され、前記比例減圧弁と並列に介装され、制御信号に基づいて所定の２次圧を発生する電磁比例減圧弁と、前記比例減圧弁の２次圧と前記電磁比例減圧弁の２次圧を高圧選択して前記流量制御弁に導く手段と、前記比例減圧弁の２次圧を検出する圧力検出手段と、前記動力源の回転数を検出する回転数検出手段とを設け、前記検出される動力源の回転数と前記比例減圧弁の２次圧とに基づいて、前記電磁比例減圧弁を制御する演算装置を備えたことを特徴とする。
請求項２に記載の発明は、前記流量制御弁の１次流量が最大のときは、前記比例減圧弁の２次圧と電磁比例減圧弁の２次圧とが略等しくなるように制御し、前記流量制御弁の１次流量が最小のときは、前記比例減圧弁の２次圧をパラメータにした所定の関数に従って前記電磁比例減圧弁に２次圧を発生させるように制御する演算装置を備えたことを特徴とする。
【００１１】
【発明の実施の形態】
以下、本発明の一実施の形態を図面に従って詳述する。尚、説明の都合上、従来技術と同一構成部分には同一符号を付してその説明を省略する。図１は建設機械の油圧操作装置を示す。比例減圧弁５のａ２ポートと流量制御弁３の油室ａ１とは管路５０により接続され、管路５０には比例減圧弁５と並列に電磁比例減圧弁１１が管路５１により接続される。この電磁比例減圧弁１１は、油圧源１６から供給される圧油を所定の圧力に減圧し２次圧として流量制御弁３の油室ａ１に出力する。管路５０と管路５１との間には、比例減圧弁５の２次圧と電磁比例減圧弁１１の２次圧とを高圧選択して流量制御弁３の油室ａ１に供給するシャトル弁１２が設けられる。また、管路５０には、比例減圧弁５の２次圧を検出する手段として圧力センサ１０が設けられる。
【００１２】
これと同様に、比例減圧弁５のｂ２ポートと流量制御弁３の油室ｂ１とは管路６０により接続され、管路６０には比例減圧弁５と並列に電磁比例減圧弁２１が管路６１により接続される。この電磁比例減圧弁２１は、油圧源１６から供給される圧油を所定の圧力に減圧し２次圧として流量制御弁３の油室ｂ１に出力する。管路６０と管路６１との間には、比例減圧弁５の２次圧と電磁比例減圧弁２１の２次圧とを高圧選択して流量制御弁３の油室ｂ１に供給するシャトル弁２２が設けられる。また、管路６０には、比例減圧弁５の２次圧を検出する手段として圧力センサ２０が設けられる。
【００１３】
尚、３０は油圧ポンプ２を駆動する動力源であるエンジン１の回転数を検出する手段としての回転センサであり、エンジン１の回転数を検出することにより、このエンジン１によって駆動される油圧ポンプ２の吐出流量（１次流量）を検出できる。そしてこのエンジン回転数に基づいて、１次流量の最大流量、最小流量を予め設定する。
【００１４】
また、圧力センサ１０，２０並びに回転センサ３０の検出信号に基づいて電磁比例減圧弁１１，２１の制御信号を演算する演算装置を備えたコントローラ４０が設けられ、該コントローラ４０は、圧力センサ１０，２０が検出した圧力信号と、回転センサ３０が検出した回転数信号を入力し、後述する制御特性（関数）に基づいて電磁比例減圧弁１１及び２１へ制御信号を出力する。
【００１５】
次に、図２にてコントローラ４０にて演算される電磁比例減圧弁１１，２１の制御信号について説明する。図２は、比例減圧弁５の２次圧と電磁比例減圧弁１１，２１の２次圧との関係を示している。回転センサ３０にてエンジン１の回転数を検出し、その回転数により流量制御弁３の１次流量が最大とされるときには、電磁比例減圧弁１１，２１は、比例減圧弁５の２次圧と略同圧の２次圧を発生するように制御される。即ち、コントローラ４０は、回転センサ３０で検出されたエンジン１の回転数が所定値以上であると油圧ポンプ２による１次流量が最大であることを判断する。そして、圧力センサ１０，２０で検出される比例減圧弁５の２次圧（検出信号）に基づいて、図２の実線で示すように、電磁比例減圧弁１１，２１が比例減圧弁５の２次圧と略同圧の２次圧を出力するように電磁比例減圧弁１１，２１に制御信号を出力する。これにより、流量制御弁３の油室ａ１、ｂ１には、高圧選択弁１２，２２を介して比例減圧弁５の２次圧と略同圧の２次圧が作用し、流量制御弁３は操作レバー４の操作により比例制御弁５が出力する２次圧によって制御される。
【００１６】
なお、上記の場合、流量制御弁３の油室ａ１、ｂ１には比例減圧弁５の２次圧と略同圧が作用することになるため、電磁比例減圧弁１１，２１は、２次圧を出力しないか、もしくは比例減圧弁５の出力する２次圧より小さい２次圧を出力するようにしても高圧選択弁１２，２２により比例減圧弁５の２次圧が選択されて上記と同等の作用を実現できる。
【００１７】
一方、回転センサ３０にてエンジン１の回転数を検出し、その回転数により流量制御弁３の１次流量が最小とされるときには、電磁比例減圧弁１１，２１は、１次流量が最大のときに発生する２次圧よりも大きい２次圧（比例減圧弁５の２次圧より大）を図２の破線で示すような特性で出力するように制御される。即ち、コントローラ４０には、比例減圧弁５の２次圧をパラメータとし、下記条件を満たすように予め設定される特性（関数）により演算される２次圧を出力するように電磁比例減圧弁１１，２１に制御信号を出力する。これにより、流量制御弁３の油室ａ１，ｂ１には、高圧選択弁１２，２２を介して比例減圧弁５の２次圧に応じて上記特性に基づいて電磁比例減圧弁１１，２１が出力する２次圧が作用し、流量制御弁３は、操作レバー４の操作により、その２次圧によって制御される。なお、上記設定される特性は、
（１）アクチュエータの動き出し位置が１次流量の影響を受けずに最大流量時と略同位置となる。
（２）速度制御範囲が１次流量の影響を受けずに最大流量時と略同一となる。
の条件を満たすものであり、予め数種類の１次流量に関して実験を行って上記所定の関数を決定する。また、最小流量と最大流量との間の１次流量については、上記２つの条件を満たすように決定した所定の関数を補完して使用（図２中、「流量をパラメータに可変」として表す部分に対応。）することで、１次流量が最小流量から最大流量までの全流範囲で操作レバーの操作に対して上記条件のようにアクチュエータを駆動することができる。
【００１８】
以上により、図７に示すように従来の油圧操作装置では、流量制御弁３の１次流量が最小のときは、スプール移動量の前半（〜Ｌ０）に不感帯があり、１次流量が最大の時は後半（Ｌ１〜）に不感帯がある。スプール移動量は比例減圧弁の操作角度に略比例するため１次流量が少ない時は操作レバーの操作量が大きくなる欠点があったが、本発明によれば、流量制御弁３の１次流量が最大流量のときよりも少ない場合は、上記特性に基づいて最大流量時よりも大きな２次圧で流量制御弁３を制御することで、操作レバーの同操作位置に対する流量制御弁３のスプールの移動量を最大流量時よりも大きくして、図３に示すように操作レバーの操作によるアクチュエータの動き出し位置を１次流量に関わりなく略同一とすることができ、また、比例減圧弁５の２次圧はスプール移動量Ｌ１相当で良いため、操作レバーの無駄な操作量を無くすことができる。
【００１９】
尚、本発明は、本発明の精神を逸脱しない限り種々の改変を為すことができ、そして、本発明が改変されたものに及ぶことは当然である。
【００２０】
【発明の効果】
本発明の建設機械の油圧操作装置は、操作レバーの操作量と機械の動きとが動力源であるエンジン等の回転数の影響を受けることを防止できるとともに、速度制御に無効な操作レバーの操作範囲を無くすことが可能となり、また、アクチュエータの動き出し位置が１次流量の影響を受けずに略同位置となるとともに、速度制御範囲が１次流量の影響を受けずに略同一となって、操作性を大幅に向上できる。
【図面の簡単な説明】
【図１】本発明の一実施の形態を示し、建設機械の油圧操作装置の回路図。
【図２】本発明の一実施の形態を示し、比例減圧弁の２次圧と電磁比例減圧弁の２次圧指令の関係を示すグラフ。
【図３】本発明の一実施の形態を示し、比例減圧弁の操作角とアクチュエータ速度の変化との関係を示すグラフ。
【図４】従来技術を示し、建設機械の油圧操作装置の回路図。
【図５】従来技術を示し、流量制御弁の内部絞りの説明図。
【図６】従来技術を示し、流量制御弁のスプールの移動量と開口面積の変化との関係を示すグラフ。
【図７】従来技術を示し、流量制御弁のスプールの移動量とアクチュエータ速度の変化との関係を示すグラフ。
【符号の説明】
１；エンジン、２；油圧ポンプ、３；流量制御弁、４；操作レバー、５；比例減圧弁、１０，２０；圧力センサ（２次圧検出手段）、１１，２１；電磁比例減圧弁、１２，２２；シャトル弁、３０；回転センサ、４０；コントローラ（演算装置）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydraulic operating device for a construction machine, and more particularly to a hydraulic operating device for a construction machine configured to prevent a relationship between an operation amount of an operation lever and a movement of the machine from being affected by an engine speed. It is about.
[0002]
Problems to be solved by the prior art and the invention
As a hydraulic operating device for a construction machine of this type, there is one as disclosed in Patent Document 1.
[0003]
[Patent Document 1] Japanese Patent Application Laid-Open No. 8-2829778
FIG. 4 schematically shows a portion related to a hydraulic operating device in Patent Document 1. As shown in FIG. 4, the hydraulic operating device includes an engine 1, a hydraulic pump 2 driven by the engine 1, a flow control valve 3 for controlling the flow rate of oil discharged from the hydraulic pump 2 and supplying the oil to an actuator, and an operating lever. A secondary pressure is generated by the operation of Step 4, and a proportional pressure reducing valve 5 that controls the flow rate control valve 3 with the secondary pressure is known. Although not described in Patent Document 1, the hydraulic pump 2 is usually driven by an engine which is a power source whose rotation speed can be varied. Therefore, the engine 1 is illustrated in FIG.
[0005]
The pressure oil discharged from the hydraulic pump 2 is supplied to the P port of the flow control valve 3 as a primary flow rate. Further, the discharge oil from the pilot hydraulic pump 15 is supplied to the P port of the proportional pressure reducing valve 5, and a reduced pilot secondary pressure is generated at the port a 2 or b 2 according to the operation of the operation lever 4. For example, when the operating pressure Pi enters the oil chamber a1 of the flow control valve 3, the pressure oil supplied from the hydraulic pump 2 by the movement of the spool is divided as a primary flow into the A port and the T port of the flow control valve 3. The secondary flow rate flows through the A port. As shown schematically in FIG. 5, inside the flow control valve 3, there are formed throttles 6, 7, 8 which change depending on the amount of movement of the spool. (The throttle 6 is formed in the oil passage from the P port to the T port, the throttle 7 is formed in the oil passage from the P port to the A port, and the throttle 8 is formed in the oil passage from the B port to the T port. .)
[0006]
Next, the operating principle of the flow control valve 3 will be described with reference to FIGS. In the neutral position, the flow control valve 3 opens the throttle 6 of the oil passage from P to T, and restricts the throttle 7 of the oil passage to P → A (or B) and the oil passage to B (or A) → T. The aperture 8 is closed. As the spool of the flow control valve 3 is moved, as shown in FIG. 6 (1), the opening area of the throttle 6 of the oil passage from P to T decreases in accordance with the amount of movement (increase) of the spool. . At the same time, the opening area of the throttle 7 of the oil passage from P to A (or B) and the throttle 8 of the oil passage from B (or A) to T increase as shown in FIG. To go. As a result, the entire primary flow rate flowing into the P port of the flow control valve 3 flows through the T port at the neutral position, but the throttle 6 of the oil passage from P to T is narrowed down with the movement of the spool. A pressure Pp (hereinafter, referred to as a pump discharge pressure) is generated at the port in accordance with the throttle amount. When the pump discharge pressure Pp exceeds a pressure Pa (hereinafter, referred to as a load pressure) required by a load connected to the A (or B) port, oil starts flowing from the P port to the A (or B) port, and the flow rate is increased. An actuator (not shown) connected to the control valve 3 starts operating.
[0007]
At the time when the flow of the pressure oil to the A (or B) port starts (the movement of the actuator starts) (the flow rate to the A or B port is still 0), the relation between the generated force and the flow rate is as follows: Become.
Q = α · F√ (2g · p / γ)
Q: flow rate, α: flow coefficient, F: throttle opening area, γ: specific weight of oil, g: gravitational acceleration, p: differential pressure.
That is, it is understood that the pump discharge pressure Pp is proportional to the square of the primary flow rate Qp. Therefore, when the primary flow rate Qp changes, the pressure Pp generated at the same spool position greatly changes, and the area of the throttle 6 when the pressure Pp exceeds the pressure Pa required by the load side becomes equal to the primary flow rate Qp. Determined as a function. That is, the amount of movement of the spool when the actuator starts to move is determined as a function of the primary flow rate Qp. When oil flows from the P port to the A port, pressure loss due to the throttle 7 occurs as in the above-described equation, and therefore, when Pp = Pa, the oil does not actually flow. As described above, the amount of flowing oil is a function of the difference p (Pp−Pa) and the area of the throttle 7, but since Pp is strongly affected by the primary flow rate Qp, this flow rate is also affected by Qp. Receive strongly.
[0008]
FIG. 7 schematically shows the relationship between the amount of movement of the spool of the flow control valve 3 and the speed of the actuator according to the above principle. The characteristic when the primary flow Qp of the flow control valve 3 is small is indicated by a broken line. As shown by the solid line, the characteristic when the primary flow rate Qp is large is as follows.
(1) The spool position when the actuator starts to move greatly fluctuates due to a change in the primary flow rate Qp.
(2) The range that can be used for speed control is small. (Both the broken line and the solid line indicate about half the amount of spool movement.)
There are drawbacks. Therefore, since the operation amount of the operation lever 4 and the spool movement amount of the flow control valve 3 are substantially proportional, the above-mentioned drawbacks
(1) The position of the operation lever 4 when the actuator starts to move greatly fluctuates due to a change in the primary flow rate. In particular, there is a problem that the operation is not performed unless the operation lever 4 is largely moved when Qp has a small flow rate.
(2) The range of operation levers that can be used for speed control is small.
Therefore, the operability was poor.
[0009]
The primary flow rate Qp of the flow control valve 3 depends on the discharge amount of the hydraulic pump 2, and the discharge amount of the hydraulic pump 2 depends on the rotation speed of the engine 1 that drives the hydraulic pump 2.
Therefore, there arises a technical problem to be solved so that the operation amount of the operation lever 4 and the movement of the actuator are not affected by the rotation speed of the engine 1, and the present invention solves this problem. The purpose is to:
[0010]
[Means for Solving the Problems]
A hydraulic operating device for a construction machine according to the present invention has been made to achieve the above object, and the invention according to claim 1 has a hydraulic pump driven by a power source capable of varying the number of revolutions and the hydraulic pump. A flow control valve for controlling the flow rate of the pressure oil discharged from the pump and supplying it to the actuator; and a proportional pressure reducing valve for generating a secondary pressure by operating an operation lever and controlling the flow control valve with the secondary pressure. An electromagnetic proportional pressure reducing valve that is applied in parallel to the proportional pressure reducing valve and generates a predetermined secondary pressure based on a control signal; Means for selecting a high pressure between the pressure and the secondary pressure of the electromagnetic proportional pressure reducing valve and guiding the selected pressure to the flow control valve; pressure detecting means for detecting the secondary pressure of the proportional pressure reducing valve; and detecting the rotational speed of the power source. Rotation speed detection means, and the detected power source Based on the secondary pressure of the rolling speed and the proportional pressure reducing valve, characterized by comprising an arithmetic unit for controlling the solenoid proportional pressure reducing valves.
The invention according to claim 2 controls the secondary pressure of the proportional pressure reducing valve and the secondary pressure of the electromagnetic proportional pressure reducing valve to be substantially equal when the primary flow rate of the flow rate control valve is maximum, When the primary flow rate of the flow rate control valve is minimum, an arithmetic unit is provided for controlling the electromagnetic proportional pressure reducing valve to generate a secondary pressure according to a predetermined function using the secondary pressure of the proportional pressure reducing valve as a parameter. It is characterized by having.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. For convenience of explanation, the same components as those of the conventional art are denoted by the same reference numerals, and description thereof will be omitted. FIG. 1 shows a hydraulic operating device of a construction machine. The port a2 of the proportional pressure reducing valve 5 and the oil chamber a1 of the flow control valve 3 are connected by a pipe 50, and an electromagnetic proportional pressure reducing valve 11 is connected to the pipe 50 by a pipe 51 in parallel with the proportional pressure reducing valve 5. . The electromagnetic proportional pressure reducing valve 11 reduces the pressure oil supplied from the hydraulic pressure source 16 to a predetermined pressure, and outputs the pressure to the oil chamber a1 of the flow control valve 3 as a secondary pressure. A shuttle valve is provided between the pipe 50 and the pipe 51 for selecting the secondary pressure of the proportional pressure reducing valve 5 and the secondary pressure of the electromagnetic proportional pressure reducing valve 11 to be high and supplying them to the oil chamber a1 of the flow control valve 3. 12 are provided. A pressure sensor 10 is provided in the conduit 50 as a means for detecting the secondary pressure of the proportional pressure reducing valve 5.
[0012]
Similarly, the b2 port of the proportional pressure reducing valve 5 and the oil chamber b1 of the flow control valve 3 are connected by a line 60, and an electromagnetic proportional pressure reducing valve 21 is connected to the line 60 in parallel with the proportional pressure reducing valve 5. 61. The electromagnetic proportional pressure reducing valve 21 reduces the pressure oil supplied from the hydraulic pressure source 16 to a predetermined pressure and outputs the pressure to the oil chamber b1 of the flow control valve 3 as a secondary pressure. Shuttle valve between the pipe 60 and the pipe 61 for selecting the secondary pressure of the proportional pressure reducing valve 5 and the secondary pressure of the electromagnetic proportional pressure reducing valve 21 to be high and supplying them to the oil chamber b1 of the flow control valve 3. 22 are provided. Further, a pressure sensor 20 is provided in the pipeline 60 as means for detecting the secondary pressure of the proportional pressure reducing valve 5.
[0013]
Reference numeral 30 denotes a rotation sensor as a means for detecting the rotation speed of the engine 1 which is a power source for driving the hydraulic pump 2, and detects the rotation speed of the engine 1 so that the hydraulic pump driven by the engine 1 2 can detect the discharge flow rate (primary flow rate). Then, based on the engine speed, the maximum flow rate and the minimum flow rate of the primary flow rate are set in advance.
[0014]
Further, a controller 40 including an arithmetic unit for calculating control signals of the electromagnetic proportional pressure reducing valves 11 and 21 based on the detection signals of the pressure sensors 10 and 20 and the rotation sensor 30 is provided. The pressure signal detected by 20 and the rotation speed signal detected by the rotation sensor 30 are input, and control signals are output to the electromagnetic proportional pressure reducing valves 11 and 21 based on control characteristics (functions) described later.
[0015]
Next, control signals for the electromagnetic proportional pressure reducing valves 11 and 21 calculated by the controller 40 will be described with reference to FIG. FIG. 2 shows the relationship between the secondary pressure of the proportional pressure reducing valve 5 and the secondary pressure of the electromagnetic proportional pressure reducing valves 11 and 21. When the rotation speed of the engine 1 is detected by the rotation sensor 30 and the primary flow rate of the flow control valve 3 is maximized based on the rotation speed, the electromagnetic proportional pressure reducing valves 11 and 21 are connected to the secondary pressure of the proportional pressure reducing valve 5. Is controlled to generate a secondary pressure that is substantially the same as That is, the controller 40 determines that the primary flow rate by the hydraulic pump 2 is maximum when the rotation speed of the engine 1 detected by the rotation sensor 30 is equal to or more than a predetermined value. Then, based on the secondary pressure (detection signal) of the proportional pressure reducing valve 5 detected by the pressure sensors 10 and 20, as shown by the solid line in FIG. A control signal is output to the electromagnetic proportional pressure reducing valves 11 and 21 so as to output a secondary pressure substantially equal to the secondary pressure. As a result, a secondary pressure substantially equal to the secondary pressure of the proportional pressure reducing valve 5 acts on the oil chambers a1 and b1 of the flow control valve 3 via the high pressure selection valves 12 and 22. The operation is controlled by the secondary pressure output from the proportional control valve 5 by operating the operation lever 4.
[0016]
In the above case, since the same pressure as the secondary pressure of the proportional pressure reducing valve 5 acts on the oil chambers a1 and b1 of the flow control valve 3, the electromagnetic proportional pressure reducing valves 11 and 21 are controlled by the secondary pressure. Is not output, or the secondary pressure of the proportional pressure reducing valve 5 is selected by the high pressure selection valves 12 and 22 even if a secondary pressure smaller than the secondary pressure output by the proportional pressure reducing valve 5 is selected. Can be realized.
[0017]
On the other hand, when the rotation speed of the engine 1 is detected by the rotation sensor 30 and the primary flow rate of the flow control valve 3 is minimized based on the rotation speed, the electromagnetic proportional pressure-reducing valves 11 and 21 output the maximum primary flow rate. Control is performed so as to output a secondary pressure (greater than the secondary pressure of the proportional pressure-reducing valve 5) larger than the secondary pressure that is sometimes generated, with characteristics as indicated by the broken line in FIG. That is, the controller 40 uses the secondary pressure of the proportional pressure reducing valve 5 as a parameter, and outputs the secondary pressure calculated by a characteristic (function) set in advance so as to satisfy the following conditions. , 21 to output a control signal. Accordingly, the electromagnetic proportional pressure reducing valves 11 and 21 are output to the oil chambers a1 and b1 of the flow rate control valve 3 via the high pressure selecting valves 12 and 22 according to the secondary pressure of the proportional pressure reducing valve 5 based on the above characteristics. The operation of the operation lever 4 controls the flow rate control valve 3 by the secondary pressure. The characteristics set above are:
(1) The movement start position of the actuator is substantially the same as the position at the maximum flow rate without being affected by the primary flow rate.
(2) The speed control range is substantially the same as at the maximum flow rate without being affected by the primary flow rate.
The above condition is satisfied, and the predetermined function is determined by conducting experiments on several types of primary flow rates in advance. For the primary flow rate between the minimum flow rate and the maximum flow rate, a predetermined function determined so as to satisfy the above two conditions is complemented and used (in FIG. 2, a part expressing “flow rate as a parameter”). In this case, the actuator can be driven under the above conditions for the operation of the operation lever in the entire range of the primary flow rate from the minimum flow rate to the maximum flow rate.
[0018]
As described above, in the conventional hydraulic operating device, as shown in FIG. 7, when the primary flow rate of the flow control valve 3 is the minimum, the dead zone exists in the first half (（L0) of the spool movement amount, and the primary flow rate is the maximum. There is a dead zone in the latter half (L1). Since the spool movement amount is substantially proportional to the operation angle of the proportional pressure reducing valve, the operation amount of the operation lever increases when the primary flow rate is small. However, according to the present invention, the primary flow rate of the flow control valve 3 is increased. Is smaller than the maximum flow rate, by controlling the flow control valve 3 with a secondary pressure larger than that at the maximum flow rate based on the above characteristics, the spool of the flow control valve 3 with respect to the same operation position of the operation lever is controlled. By making the moving amount larger than the maximum flow rate, as shown in FIG. 3, the movement start position of the actuator by operating the operation lever can be made substantially the same regardless of the primary flow rate. Since the next pressure may be equivalent to the spool movement amount L1, an unnecessary operation amount of the operation lever can be eliminated.
[0019]
The present invention can be variously modified without departing from the spirit of the present invention, and it goes without saying that the present invention extends to modified ones.
[0020]
【The invention's effect】
The hydraulic operating device for a construction machine according to the present invention can prevent the operation amount of the operating lever and the movement of the machine from being affected by the rotation speed of the engine or the like that is the power source, and operate the operating lever invalid for speed control. It is possible to eliminate the range, and the movement start position of the actuator becomes substantially the same position without being affected by the primary flow rate, and the speed control range becomes substantially the same without being affected by the primary flow rate, Operability can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a hydraulic operating device of a construction machine according to an embodiment of the present invention.
FIG. 2 is a graph showing one embodiment of the present invention and showing a relationship between a secondary pressure of a proportional pressure reducing valve and a secondary pressure command of an electromagnetic proportional pressure reducing valve.
FIG. 3 is a graph showing an embodiment of the present invention and showing a relationship between an operation angle of a proportional pressure reducing valve and a change in actuator speed.
FIG. 4 is a circuit diagram of a hydraulic operating device of a construction machine, showing a conventional technique.
FIG. 5 is a view showing a conventional technique, and is an explanatory view of an internal throttle of a flow control valve.
FIG. 6 is a graph showing the prior art and showing the relationship between the amount of movement of the spool of the flow control valve and the change in the opening area.
FIG. 7 is a graph showing a related art, and showing a relationship between a movement amount of a spool of a flow control valve and a change in an actuator speed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1; Engine 2; Hydraulic pump 3; Flow control valve 4; Operating lever 5; Proportional pressure reducing valve 10, 20; Pressure sensor (secondary pressure detecting means) 11, 21; , 22; shuttle valve, 30; rotation sensor, 40; controller (arithmetic unit)

Claims

A hydraulic pump driven by a power source capable of varying the rotation speed,
A flow rate control valve for controlling the flow rate of the pressure oil discharged from the hydraulic pump and supplying it to the actuator,
A hydraulic pressure control device for a construction machine comprising: a secondary pressure generated by operation of an operation lever; and a proportional pressure reducing valve that controls the flow rate control valve with the secondary pressure.
An electromagnetic proportional pressure reducing valve interposed in parallel with the proportional pressure reducing valve and generating a predetermined secondary pressure based on a control signal;
Means for selecting a high pressure between the secondary pressure of the proportional pressure reducing valve and the secondary pressure of the electromagnetic proportional pressure reducing valve and guiding the selected pressure to the flow control valve;
Pressure detecting means for detecting a secondary pressure of the proportional pressure reducing valve;
A rotation speed detection means for detecting the rotation speed of the power source,
A hydraulic operating device for a construction machine, comprising: a calculating device that controls the electromagnetic proportional pressure reducing valve based on the detected rotation speed of the power source and a secondary pressure of the proportional pressure reducing valve.

When the primary flow rate of the flow control valve is maximum, control is performed so that the secondary pressure of the proportional pressure reducing valve is substantially equal to the secondary pressure of the electromagnetic proportional pressure reducing valve, and the primary flow rate of the flow rate control valve is reduced. 2. An arithmetic unit for controlling the electromagnetic proportional pressure reducing valve to generate a secondary pressure according to a predetermined function using a secondary pressure of the proportional pressure reducing valve as a parameter when the pressure is minimum. A hydraulic operating device for a construction machine according to the above.