JPH0988901A - Pump inclination angle control device - Google Patents
Pump inclination angle control deviceInfo
- Publication number
- JPH0988901A JPH0988901A JP7244596A JP24459695A JPH0988901A JP H0988901 A JPH0988901 A JP H0988901A JP 7244596 A JP7244596 A JP 7244596A JP 24459695 A JP24459695 A JP 24459695A JP H0988901 A JPH0988901 A JP H0988901A
- Authority
- JP
- Japan
- Prior art keywords
- pressure
- valve
- reducing valve
- pump
- load sensing
- 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.)
- Granted
Links
Landscapes
- Control Of Positive-Displacement Pumps (AREA)
- Operation Control Of Excavators (AREA)
- Fluid-Pressure Circuits (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】この発明は、油圧シャベルな
ど建設機械への使用に適するロードセンシングシステム
のポンプ傾転角制御装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump tilt angle control device for a load sensing system suitable for use in a construction machine such as a hydraulic shovel.
【０００２】[0002]
【従来の技術】油圧シャベルなどのアクチュエータに可
変ポンプを配管接続し、その途中に可変絞りを備える駆
動回路において、ポンプの動力損失を小さく抑えるた
め、可変ポンプの傾転角を作動圧に応じて調整するレギ
ュレータピストンと、可変絞りの上流側と下流側の差圧
に応じてこれを設定差圧に保つようにレギュレータピス
トンの作動圧を制御するロードセンシングバルブを設
け、アクチュエータへの必要量に応じて可変ポンプの吐
出量を調整するようにしたものが知られてる。2. Description of the Related Art In a drive circuit in which a variable pump is connected to an actuator such as a hydraulic shovel by piping, and a variable throttle is provided in the middle of the actuator, the tilt angle of the variable pump is adjusted according to the operating pressure in order to suppress power loss of the pump. A regulator piston to be adjusted and a load sensing valve to control the working pressure of the regulator piston to keep it at a set differential pressure according to the differential pressure between the upstream side and the downstream side of the variable throttle are provided. It is known to adjust the discharge rate of a variable pump.
【０００３】このようなロードセンシングシステムにお
いて、アクチュエータの微量操作性（いわゆる、インチ
ング性能）を高めるため、ロードセンシングバルブの差
圧設定に可変ポンプの傾転角をフィードバックするよう
にしたものや、ロードセンシングバルブの設定差圧を外
部信号に応じて電気的または油圧的に変化させるように
したものがある（特開昭５８ー１４３１８７号公報，特
開平３ー７４６０５号公報）。In such a load sensing system, in order to enhance the operability of the actuator in a small amount (so-called inching performance), the tilt angle of the variable pump is fed back to the differential pressure setting of the load sensing valve, and the load sensing system. There is one in which the set differential pressure of the sensing valve is changed electrically or hydraulically according to an external signal (Japanese Patent Laid-Open No. 58-143187 and Japanese Patent Laid-Open No. 3-74605).
【０００４】[0004]
【発明が解決しようとする課題】しかしながら、前者で
はポンプ傾転角が変位すると、ロードセンシングバルブ
の設定差圧が必ず変化するため、オペレータのレバー操
作量（可変絞りの開度）とポンプ吐出量の間に１次的な
比例関係が成り立たず、通常モード時においてはオペレ
ータに違和感を与えるという問題点があった。また、ロ
ードセンシングバルブの設定差圧にメカニカルな連動機
構を介してポンプ傾転角をフィードバックするため、そ
の連動機構の各部品の寸法公差やガタおよび使用中の摩
耗などの影響を受けやすく、その調整も難しいという不
具合があった。However, in the former case, when the pump tilt angle changes, the set differential pressure of the load sensing valve always changes, so the operator's lever operation amount (variable throttle opening) and pump discharge amount are changed. However, there is a problem that the operator does not feel a sense of discomfort in the normal mode because a linear proportional relationship cannot be established between the two. In addition, since the pump tilt angle is fed back to the set differential pressure of the load sensing valve via a mechanical interlocking mechanism, it is susceptible to dimensional tolerance of each part of the interlocking mechanism, backlash, and wear during use. There was a problem that adjustment was difficult.
【０００５】後者では外部信号でロードセンシングバル
ブの設定スプリングに対抗して差圧を変えることによ
り、可変絞りの開度に比例するアクチュエータへの流量
特性がインチングモードと通常モードとに切り替わるよ
うになっているが、インチングモード時に何らかのトラ
ブルで外部信号が途絶えると、ロードセンシングバルブ
の制御特性が差圧の大きい通常モードに戻るため、アク
チュエータの動作速度が急に増加するという問題点があ
った。In the latter case, the flow rate characteristic to the actuator proportional to the opening of the variable throttle is switched between the inching mode and the normal mode by changing the differential pressure against the set spring of the load sensing valve by an external signal. However, if the external signal is interrupted due to some trouble in the inching mode, the control characteristic of the load sensing valve returns to the normal mode in which the differential pressure is large, so that the operating speed of the actuator suddenly increases.
【０００６】この発明はこのような問題点を解決するこ
とを目的とする。The present invention aims to solve such problems.
【０００７】[0007]
【課題を解決するための手段】この発明では、アクチュ
エータと可変ポンプを接続するメイン回路に可変絞りを
介装し、可変ポンプの傾転角を作動圧に応じて調整する
レギュレータピストンと、可変絞りの上流側と下流側の
差圧に応じてこれを設定差圧に保つようにレギュレータ
ピストンの作動圧を制御するロードセンシングバルブを
備えるポンプ傾転角制御装置において、ロードセンシン
グバルブに差圧設定用の受圧部を設け、ポンプ傾転角の
フィードバックを受けて圧縮されるスプリングのバネ力
に応じた２次圧を出力する減圧弁と、外部信号に応じた
２次圧を出力する電磁減圧弁と、これら減圧弁の１次圧
を供給する制御用ポンプと、減圧弁と電磁減圧弁との２
次圧の高い方を選択してロードセンシングバルブの差圧
設定用の受圧部に導くシャトル弁を設ける。According to the present invention, a variable throttle is provided in a main circuit connecting an actuator and a variable pump, and a regulator piston for adjusting a tilt angle of the variable pump according to an operating pressure and a variable throttle. In the pump tilt angle control device equipped with a load sensing valve that controls the working pressure of the regulator piston so as to keep it at the set differential pressure according to the differential pressure between the upstream side and the downstream side, A pressure reducing valve that outputs a secondary pressure corresponding to the spring force of a spring that is compressed by receiving feedback of the pump tilt angle, and an electromagnetic pressure reducing valve that outputs a secondary pressure according to an external signal. , A control pump that supplies the primary pressure of these pressure reducing valves, and a pressure reducing valve and an electromagnetic pressure reducing valve.
A shuttle valve that selects the higher secondary pressure and guides it to the pressure receiving part for setting the differential pressure of the load sensing valve is provided.
【０００８】[0008]
【作用】可変ポンプの吐出油は、可変絞りを通して流
れ、その流量に応じた速度でアクチュエータを動作させ
る。このとき、可変絞りの上流側と下流側に差圧が発生
し、ロードセンシングバルブに作用する。ロードセンシ
ングバルブはレギュレータピストンの作動圧を制御し、
可変絞りの前後差圧を設定差圧に保つようにポンプ傾転
角を調整する。The discharge oil of the variable pump flows through the variable throttle, and the actuator is operated at a speed according to the flow rate. At this time, a differential pressure is generated between the upstream side and the downstream side of the variable throttle and acts on the load sensing valve. The load sensing valve controls the working pressure of the regulator piston,
Adjust the pump tilt angle to keep the differential pressure across the variable throttle at the set differential pressure.
【０００９】制御用ポンプの吐出油は、電磁減圧弁と減
圧弁の１次圧として供給される。電磁減圧弁は外部信号
に応じた２次圧を出力し、減圧弁はポンプ傾転角のフィ
ードバックを受けて圧縮されるスプリングのバネ力に応
じた２次圧を出力する。そして、これら２次圧の高い方
がシャトル弁を介してロードセンシングバルブの差圧設
定用の受圧部に作用する。The discharge oil of the control pump is supplied as the primary pressure of the electromagnetic pressure reducing valve and the pressure reducing valve. The electromagnetic pressure reducing valve outputs a secondary pressure according to an external signal, and the pressure reducing valve outputs a secondary pressure according to the spring force of a spring compressed by receiving feedback of the pump tilt angle. The higher secondary pressure acts on the pressure receiving portion for setting the differential pressure of the load sensing valve via the shuttle valve.
【００１０】減圧弁のスプリングをインチングモードに
適合するバネ定数に設定し、電磁減圧弁の外部信号を通
常モードに適合する電流値に設定すると、通常モード時
は電磁減圧弁を作動させるとその２次圧が選択され、ロ
ードセンシングバルブの設定差圧を大きくする。そのた
め、可変絞りの流量が増加するので、アクチュエータは
それだけ速く動作する。また、外部信号により電磁減圧
弁の２次圧を一定に制御すると、可変絞りの開度に比例
するアクチュエータへの流量特性が得られるので、オペ
レータは何ら違和感なく、絞り開度の操作を行えること
になる。When the spring of the pressure reducing valve is set to a spring constant suitable for the inching mode and the external signal of the electromagnetic pressure reducing valve is set to a current value suitable for the normal mode, the electromagnetic pressure reducing valve is operated in the normal mode. The secondary pressure is selected and the set differential pressure of the load sensing valve is increased. Therefore, the flow rate of the variable throttle increases, so that the actuator operates faster. Further, if the secondary pressure of the electromagnetic pressure reducing valve is controlled to be constant by an external signal, the flow rate characteristic to the actuator proportional to the opening of the variable throttle can be obtained, so that the operator can operate the throttle opening without any discomfort. become.
【００１１】電磁減圧弁の作動をオフすると、減圧弁の
２次圧がシャトル弁を介してロードセンシングバルブに
導かれ、その設定差圧を小さくする。そのため、ポンプ
吐出量が減少するため、可変絞りの開度変化に対して、
アクチュエータへの流量変化が少なくなる。しかも、ロ
ードセンシングバルブの設定差圧にポンプ傾転角が減圧
弁の２次圧を介してフィードバックされるため、小流量
時の絞り抵抗に伴う圧力損失を低減しつつ、良好なイン
チング性能を確保できる。When the operation of the electromagnetic pressure reducing valve is turned off, the secondary pressure of the pressure reducing valve is guided to the load sensing valve via the shuttle valve to reduce the set differential pressure thereof. Therefore, since the pump discharge amount decreases,
Flow rate change to the actuator is reduced. Moreover, since the pump tilt angle is fed back to the set pressure difference of the load sensing valve via the secondary pressure of the pressure reducing valve, good inching performance is secured while reducing pressure loss due to throttle resistance at a small flow rate. it can.
【００１２】[0012]
【発明の実施の形態】図１において、３は油圧シャベル
などを駆動するアクチュエータ、１は斜板の傾転角に応
じて吐出量が変化する可変ポンプで、これらは駆動回路
２０を介して接続され、その回路途中にレバー操作可能
な可変絞り２が介装される。ポンプ１の吐出量を制御す
るため、斜板の制御棒１ａに逆向きに作動する第１のレ
ギュレータピストン４ａと第２のレギュレータピストン
４ｂがそれぞれ連結される。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, 3 is an actuator for driving a hydraulic shovel and the like, 1 is a variable pump whose discharge amount changes according to the tilt angle of a swash plate, and these are connected via a drive circuit 20. The lever-operable variable diaphragm 2 is interposed in the middle of the circuit. In order to control the discharge amount of the pump 1, the first regulator piston 4a and the second regulator piston 4b which operate in opposite directions are connected to the control rod 1a of the swash plate, respectively.
【００１３】第１のレギュレータピストン４ａにロード
センシングバルブ５から制御圧が導かれ、第２のレギュ
レータピストン４ｂに駆動回路２０の可変絞り２上流か
らポンプ吐出圧が導かれ、これら駆動力がバランスする
位置に斜板の制御棒１ａを変位させる。なお、第１のレ
ギュレータピストン４ａの受圧面積は、第２のレギュレ
ータピストン４ｂの受圧面積より大きく設定される。A control pressure is introduced from the load sensing valve 5 to the first regulator piston 4a, and a pump discharge pressure is introduced to the second regulator piston 4b from the upstream side of the variable throttle 2 of the drive circuit 20 to balance these driving forces. The control rod 1a of the swash plate is displaced to the position. The pressure receiving area of the first regulator piston 4a is set larger than the pressure receiving area of the second regulator piston 4b.
【００１４】ロードセンシングバルブ５は一端に駆動回
路２０の可変絞り２上流からポンプ吐出圧が導かれ、他
端に同じく可変絞り下流から負荷圧が導かれ、これらの
差圧に対抗するスプリング５ａが備えられる。また、後
述する回路２１を通して信号圧が導かれ、ロードセンシ
ングバルブ５はこれらの圧力およびスプリング５ａのバ
ランスする位置に制御され、その位置に応じてレギュレ
ータピストン４ａの作動圧を調整する。The load sensing valve 5 has one end to which the pump discharge pressure is introduced from the upstream side of the variable throttle 2 of the drive circuit 20, and the other end to which the load pressure is introduced from the downstream side of the variable throttle. Be prepared. Further, a signal pressure is introduced through a circuit 21 described later, the load sensing valve 5 is controlled to a position where these pressures and the spring 5a are balanced, and the working pressure of the regulator piston 4a is adjusted according to the position.
【００１５】信号圧回路２１にはスプリング７ａのバネ
力に応じた２次圧を出力する減圧弁７と、外部信号に応
じた２次圧を出力する電磁減圧弁６が並列に介装され、
これら減圧弁７，６の１次圧として吐出圧を供給する制
御用ポンプ８と、これら２次圧の高い方を選択してロー
ドセンシングバルブ５に導くシャトル弁１０が設けられ
る。In the signal pressure circuit 21, a pressure reducing valve 7 for outputting a secondary pressure corresponding to the spring force of the spring 7a and an electromagnetic pressure reducing valve 6 for outputting a secondary pressure according to an external signal are interposed in parallel.
A control pump 8 that supplies the discharge pressure as the primary pressure of the pressure reducing valves 7 and 6 and a shuttle valve 10 that selects the higher secondary pressure and guides it to the load sensing valve 5 are provided.
【００１６】減圧弁７は２次側のパイロット圧に対抗す
るスプリング７ａの設定荷重に応じて開度が制御され、
余剰油をタンク１２へ逃がすもので、スプリング７ａに
レバー１３を介して第１のレギュレータピストン４ａが
連結され、そのピストン変位に応じて支点１３ａを中心
にレバー１３が回動し、スプリング７ａのバネ力を変化
させることにより、ポンプ傾転角が小さいほどスプリン
グ７ａが弱くなり、可変絞り２の差圧が小さくなる。電
磁減圧弁６は信号電流に応じて作動するソレノイド６ａ
を備えるもので、２次側のパイロット圧に対抗するソレ
ノイド６ａの励磁力に応じて開度が制御され、余剰油を
タンク１２へ逃がすようになっている。The opening of the pressure reducing valve 7 is controlled according to the set load of the spring 7a which opposes the pilot pressure on the secondary side,
Excess oil is released to the tank 12, the first regulator piston 4a is connected to the spring 7a via the lever 13, and the lever 13 rotates around the fulcrum 13a according to the displacement of the piston. By changing the force, the spring 7a becomes weaker as the pump tilt angle becomes smaller, and the differential pressure of the variable throttle 2 becomes smaller. The solenoid pressure reducing valve 6 is a solenoid 6a that operates according to a signal current.
The opening degree is controlled according to the exciting force of the solenoid 6a that opposes the pilot pressure on the secondary side, and the surplus oil is allowed to escape to the tank 12.
【００１７】なお、減圧弁７には負荷圧の変動に対する
応答遅れに起因するハンチング現象を抑制するため、２
次側のパイロット圧を絞るオリフィス９が設けられる。
１１は減圧弁７および電磁減圧弁６の１次圧を制限する
リリーフ弁を示す。In order to suppress the hunting phenomenon due to the response delay with respect to the fluctuation of the load pressure, the pressure reducing valve 7 has two
An orifice 9 for reducing the pilot pressure on the next side is provided.
Reference numeral 11 denotes a relief valve that limits the primary pressure of the pressure reducing valve 7 and the electromagnetic pressure reducing valve 6.
【００１８】ロードセンシングバルブ５についてその具
体的な構成を説明すると、図２のようにバルブボデイ３
０にスプール３１とパイロットプランジャ３２を備え
る。スプール３１はスリーブ３３内を摺動自由に挿入さ
れ、ポンプ吐出圧とスプリング５ａおよびパイロットプ
ランジャ３２を介して作用する負荷圧と信号圧とのバラ
ンスする位置に変位し、第１のレギュレータピストン４
ａ側へのポート３４に駆動回路２０の可変絞り２上流側
へのポート３５とタンク１２側へのポート３６を選択的
に接続する。スプール３１の一端側に油室３７が形成さ
れ、駆動回路２０の可変絞り２上流からポンプ吐出圧が
油室３７に導かれる。スプール３１の他端側にバネ室３
８が形成され、スプール３１をポンプ吐出圧に対抗して
付勢するスプリング５ａが収装される。The specific structure of the load sensing valve 5 will be described. As shown in FIG.
A spool 31 and a pilot plunger 32 are provided at the position 0. The spool 31 is slidably inserted in the sleeve 33 and is displaced to a position where the pump discharge pressure and the load pressure and signal pressure acting via the spring 5 a and the pilot plunger 32 are balanced, and the first regulator piston 4
The port 34 to the a side is selectively connected to the port 35 to the upstream side of the variable throttle 2 of the drive circuit 20 and the port 36 to the tank 12 side. An oil chamber 37 is formed on one end side of the spool 31, and pump discharge pressure is introduced into the oil chamber 37 from the upstream side of the variable throttle 2 of the drive circuit 20. The spring chamber 3 is provided at the other end of the spool 31.
8 is formed, and a spring 5a for biasing the spool 31 against the pump discharge pressure is accommodated.
【００１９】パイロットプランジャ３２は大径部３２ａ
と小径部３２ｂとから形成され、バネ室３８の密閉する
プラグ３９に同軸方向へ摺動自由に支持される。プラン
ジャ３２の中間段差面に臨む油室４０と小径部３２ｂ側
の後端面に臨む油室４１が形成され、油室４１に駆動回
路２０の可変絞り２下流の負荷圧が導かれ、油室４０に
シャトル弁１０の選択する信号圧が導かれ、パイロット
プランジャ３２はこれらの圧力を受けてポンプ吐出圧に
対抗する押圧力をスプール３１に及ぼす。４２はスプー
ル３１側の油室３７を密閉するプラグ、４４はポート３
５からポンプ吐出圧を油室３７に導く通路、４３はバネ
室３８の油をタンク１２に戻すドレンを示す。The pilot plunger 32 has a large diameter portion 32a.
And a small diameter portion 32b, and is supported by the plug 39 that seals the spring chamber 38 so as to be slidable coaxially. An oil chamber 40 facing the intermediate step surface of the plunger 32 and an oil chamber 41 facing the rear end surface of the small diameter portion 32b are formed, and the load pressure downstream of the variable throttle 2 of the drive circuit 20 is guided to the oil chamber 41, so that the oil chamber 40 The signal pressure selected by the shuttle valve 10 is introduced to the pilot plunger 32, and the pilot plunger 32 receives these pressures and exerts a pressing force against the pump discharge pressure on the spool 31. 42 is a plug for sealing the oil chamber 37 on the spool 31 side, and 44 is a port 3
A passage for guiding the pump discharge pressure from 5 to the oil chamber 37 and a drain 43 for returning the oil in the spring chamber 38 to the tank 12.
【００２０】このような構成により、可変ポンプ１の吐
出油が可変絞り２を通してアクチュエータ３へ流れる
と、可変絞り２の上流側と下流側に差圧が発生し、ロー
ドセンシングバルブ５に作用する。ポンプ吐出圧が負荷
圧とスプリング５ａおよび信号圧との総和よりも大きく
なると、ロードセンシングバルブ５はＡポジションに切
り替わり、第１のレギュレータピストン４ａの作動圧を
ポンプ吐出圧まで上昇させる。第２のレギュレータピス
トン４ｂと第１のレギュレータピストン４ａが同圧にな
ると、その受圧面積差に基づく駆動力により、第１のレ
ギュレータピストン４ａが第２のレギュレータピストン
４ｂを押し戻しながら、斜板の制御棒１ａをポンプ吐出
量の減少方向に変位させる。With such a configuration, when the discharge oil of the variable pump 1 flows to the actuator 3 through the variable throttle 2, a differential pressure is generated between the upstream side and the downstream side of the variable throttle 2 and acts on the load sensing valve 5. When the pump discharge pressure becomes larger than the sum of the load pressure and the spring 5a and the signal pressure, the load sensing valve 5 switches to the A position and raises the operating pressure of the first regulator piston 4a to the pump discharge pressure. When the second regulator piston 4b and the first regulator piston 4a have the same pressure, the driving force based on the pressure receiving area difference causes the first regulator piston 4a to push back the second regulator piston 4b and control the swash plate. The rod 1a is displaced in the direction of decreasing the pump discharge amount.
【００２１】可変ポンプ１の吐出量が減少し、ポンプ吐
出圧が負荷圧とスプリング５ａおよび信号圧との総和よ
りも小さくなると、ロードセンシングバルブ５はＢポジ
ションに切り替わり、第１のレギュレータピストン４ａ
の作動圧をタンク１２に開放する。そのため、第２のレ
ギュレータピストン４ｂが第１のレギュレータピストン
４ａを押し戻しながら、斜板の制御棒１ａをポンプ吐出
量の増加方向に変位させる。When the discharge amount of the variable pump 1 decreases and the pump discharge pressure becomes smaller than the sum of the load pressure and the spring 5a and the signal pressure, the load sensing valve 5 switches to the B position and the first regulator piston 4a.
The working pressure of is released to the tank 12. Therefore, while the second regulator piston 4b pushes back the first regulator piston 4a, the swash plate control rod 1a is displaced in the direction of increasing the pump discharge amount.
【００２２】このような制御により、可変絞り２の前後
差圧はロードセンシングバルブ５の設定差圧に調整さ
れ、可変絞り２のレバー操作量に応じてアクチュエータ
３への流量を増減することが可能になる。ロードセンシ
ングバルブ５に作用する差圧の設定はスプリング５ａと
信号圧に依存する。この設定差圧を変更するため、信号
圧回路２１に減圧弁７と電磁減圧弁６が並列に設けら
れ、制御用ポンプ８から減圧弁７および電磁減圧弁６の
１次圧が供給され、これら２次圧の高い方がシャトル弁
１０を介して選択され、信号圧としてロードセンシング
バルブ５に導かれる。By such control, the differential pressure across the variable throttle 2 is adjusted to the set differential pressure of the load sensing valve 5, and the flow rate to the actuator 3 can be increased or decreased according to the lever operation amount of the variable throttle 2. become. The setting of the differential pressure acting on the load sensing valve 5 depends on the spring 5a and the signal pressure. In order to change the set differential pressure, the pressure reducing valve 7 and the electromagnetic pressure reducing valve 6 are provided in parallel in the signal pressure circuit 21, and the primary pressure of the pressure reducing valve 7 and the electromagnetic pressure reducing valve 6 is supplied from the control pump 8 to these. The higher secondary pressure is selected via the shuttle valve 10 and guided to the load sensing valve 5 as a signal pressure.
【００２３】減圧弁７のスプリング７ａをインチングモ
ードに適合するバネ定数に設定し、電磁減圧弁６のソレ
ノイド６ａに対する外部信号を通常モードに適合する電
流値に設定すると、電磁減圧弁６の２次圧が減圧弁７の
２次圧よりも高いため、通常モード時は電磁減圧弁６の
２次圧が選択され、ロードセンシングバルブ５の設定差
圧を大きくする。そのため、同一開度に対する可変絞り
２の流量が増加するので、アクチュエータ３はそれだけ
速く動作する。外部信号により電磁減圧弁６の２次圧を
一定の高レベルに制御すると、図３の直線Ａで表すよう
なアクチュエータ３への流量特性が得られるので、レバ
ー操作に連動する絞り開度に１次的に比例した流量とな
り、オペレータは何ら違和感ない操作感が得られる。When the spring 7a of the pressure reducing valve 7 is set to a spring constant suitable for the inching mode and the external signal to the solenoid 6a of the electromagnetic pressure reducing valve 6 is set to a current value suitable for the normal mode, the secondary pressure of the electromagnetic pressure reducing valve 6 is changed. Since the pressure is higher than the secondary pressure of the pressure reducing valve 7, the secondary pressure of the electromagnetic pressure reducing valve 6 is selected in the normal mode to increase the set differential pressure of the load sensing valve 5. Therefore, the flow rate of the variable throttle 2 increases for the same opening, and the actuator 3 operates faster. When the secondary pressure of the electromagnetic pressure reducing valve 6 is controlled to a constant high level by an external signal, the flow rate characteristic to the actuator 3 as shown by the straight line A in FIG. Next, the flow rate becomes proportional, and the operator can obtain a feeling of operation without any discomfort.
【００２４】電磁減圧弁６の作動をオフすると、減圧弁
７の２次圧がシャトル弁１０を介してロードセンシング
バルブ５に導かれ、その設定差圧を小さくする。そのた
め、可変絞り２の流量が減少し、その絞り開度のレバー
操作量に対する流量変化も少なくなる。ロードセンシン
グバルブ５の設定差圧にポンプ傾転角が減圧弁７の２次
圧を介してフィードバックされるため、図３の曲線Ｂで
表すようなアクチュエータ３への流量特性が得られる。
つまり、絞り開度が小さいときは差圧が小さくなるよう
にフィードバックされるので、小流量時の絞り抵抗に伴
う圧力損失を低減しつつ、良好なインチング性能を確保
できる。When the operation of the electromagnetic pressure reducing valve 6 is turned off, the secondary pressure of the pressure reducing valve 7 is guided to the load sensing valve 5 via the shuttle valve 10 to reduce the set differential pressure thereof. Therefore, the flow rate of the variable throttle 2 decreases, and the flow rate change of the throttle opening with respect to the lever operation amount also decreases. Since the pump tilt angle is fed back to the set differential pressure of the load sensing valve 5 via the secondary pressure of the pressure reducing valve 7, the flow rate characteristic to the actuator 3 as shown by the curve B in FIG. 3 is obtained.
That is, when the throttle opening is small, the feedback is performed so that the differential pressure becomes small, so that it is possible to secure good inching performance while reducing the pressure loss due to the throttle resistance when the flow rate is small.
【００２５】この場合、電磁減圧弁６の外部信号をオン
ーオフ的に制御することにより、インチングモードと通
常モードとに選択可能になり、通常モード時の外部信号
が途絶えても、減圧弁７の２次圧でバックアップされる
ため、ロードセンシングバルブ５の設定差圧がゼロに落
ち、アクチュエータ３への流量が急減するようなことは
なく、外部信号に対する良好なフェールセーフ機能を確
保できる。In this case, by controlling the external signal of the electromagnetic pressure reducing valve 6 on / off, it is possible to select between the inching mode and the normal mode. Since it is backed up by the next pressure, the set differential pressure of the load sensing valve 5 does not drop to zero and the flow rate to the actuator 3 does not suddenly decrease, and a good fail-safe function for external signals can be secured.
【００２６】ポンプ傾転角をロードセンシングバルブ５
の設定差圧にフィードバックするのも減圧弁７の２次圧
に拠るため、メカニカルなフィードバック機構のように
ロードセンシングバルブ５の配置に制約されるというこ
とはなく、レイアウトの自由度が拡大するというメリッ
トが得られる。また、減圧弁７のスプリング７ａのバネ
定数を変えることにより、可変絞り２を交換しなくて
も、その開度特性を変更できるので、実機マッチング調
整も容易に行える。なお、電磁減圧弁６への信号電流値
を任意に選択可能にすると、ロードセンシングバルブ５
の設定差圧の調整範囲をさらに拡大できる。The pump tilt angle is determined by the load sensing valve 5
The secondary pressure of the pressure reducing valve 7 also feeds back to the set differential pressure of 1. Therefore, the layout of the load sensing valve 5 is not limited by the arrangement of the load sensing valve 5 unlike the mechanical feedback mechanism. Benefits are obtained. Further, by changing the spring constant of the spring 7a of the pressure reducing valve 7, the opening characteristic can be changed without replacing the variable throttle 2, so that the actual machine matching adjustment can be easily performed. If the signal current value to the electromagnetic pressure reducing valve 6 can be arbitrarily selected, the load sensing valve 5
The adjustment range of the set differential pressure of can be further expanded.
【００２７】[0027]
【発明の効果】この発明によれば、アクチュエータと可
変ポンプを接続するメイン回路に可変絞りを介装し、可
変ポンプの傾転角を作動圧に応じて調整するレギュレー
タピストンと、可変絞りの上流側と下流側の差圧に応じ
てこれを設定差圧に保つようにレギュレータピストンの
作動圧を制御するロードセンシングバルブを備えるポン
プ傾転角制御装置において、ロードセンシングバルブに
差圧設定用の受圧部を設け、ポンプ傾転角のフィードバ
ックを受けて圧縮されるスプリングのバネ力に応じた２
次圧を出力する減圧弁と、外部信号に応じた２次圧を出
力する電磁減圧弁と、これら減圧弁の１次圧を供給する
制御用ポンプと、減圧弁と電磁減圧弁との２次圧の高い
方を選択してロードセンシングバルブの差圧設定用の受
圧部に導くシャトル弁を設けたので、ポンプ傾転角すな
わち流量に応じて変化する設定差圧に基づく流量特性と
外部信号に応じた一定の設定差圧に基づく流量特性とを
任意に選択できる。According to the present invention, the variable throttle is provided in the main circuit connecting the actuator and the variable pump, and the regulator piston for adjusting the tilt angle of the variable pump according to the working pressure, and the upstream of the variable throttle. In the pump tilt angle control device equipped with a load sensing valve that controls the working pressure of the regulator piston so as to keep it at the set differential pressure according to the differential pressure between the downstream side and the downstream side, the load sensing valve receives the pressure for setting the differential pressure. 2) is provided depending on the spring force of the spring that is compressed by receiving the feedback of the pump tilt angle.
A pressure reducing valve that outputs a secondary pressure, an electromagnetic pressure reducing valve that outputs a secondary pressure according to an external signal, a control pump that supplies the primary pressure of these pressure reducing valves, and a secondary pressure reducing valve and an electromagnetic pressure reducing valve. Since a shuttle valve that selects the higher pressure and guides it to the pressure receiving part for setting the differential pressure of the load sensing valve is provided, the flow rate characteristics based on the set differential pressure that changes according to the pump tilt angle, that is, the flow rate, and the external signal are It is possible to arbitrarily select the flow rate characteristic based on a constant set differential pressure.
【００２８】また、減圧弁の２次圧をインチングモード
に適合する低めの設定にし、電磁減圧弁の２次圧を通常
モードに適合する高めの設定にすると、電磁減圧弁を作
動させることにより、通常モード時に電磁減圧弁の２次
圧が選択され、電磁減圧弁の作動を停止することによ
り、インチングモード時に減圧弁の２次圧が選択される
ようになり、インチング性能の改善と通常操作性の向上
との相反するオペレータ要求を満すことが可能になる。
また、外部信号が何らかのトラブルで途絶えても、減圧
弁の２次圧でロードセンシングバルブの設定差圧がバッ
クアップされるため、外部信号に対するフェールセーフ
機能も確保できる。If the secondary pressure of the pressure reducing valve is set to a lower setting suitable for the inching mode and the secondary pressure of the electromagnetic pressure reducing valve is set to a higher setting suitable for the normal mode, the electromagnetic pressure reducing valve is actuated, The secondary pressure of the electromagnetic pressure reducing valve is selected in the normal mode, and the secondary pressure of the pressure reducing valve is selected in the inching mode by stopping the operation of the electromagnetic pressure reducing valve, improving the inching performance and normal operability. It is possible to satisfy the operator's demands that conflict with the improvement of
Further, even if the external signal is interrupted due to some trouble, the set pressure difference of the load sensing valve is backed up by the secondary pressure of the pressure reducing valve, so that a fail-safe function for the external signal can be secured.
【図１】この発明の実施形態を表す構成図である。FIG. 1 is a configuration diagram illustrating an embodiment of the present invention.
【図２】同じくロードセンシングバルブの要部断面図で
ある。FIG. 2 is a sectional view of the main part of the load sensing valve.
【図３】アクチュエータへの流量特性図である。FIG. 3 is a flow rate characteristic diagram for an actuator.
１ 可変ポンプ ２ 可変絞り ３ アクチュエータ ４ａ 第１のレギュレータピストン ４ｂ 第２のレギュレータピストン ５ ロードセンシングバルブ ５ａ スプリング ６ 電磁減圧弁 ６ａ ソレノイド ７ 減圧弁 ７ａ スプリング ８ 制御用ポンプ ９ オリフィス １０ シャトル弁 １１ リリーフ弁 １２ タンク ３１ スプール ３２ パイロットプランジャ 1 Variable Pump 2 Variable Throttle 3 Actuator 4a First Regulator Piston 4b Second Regulator Piston 5 Load Sensing Valve 5a Spring 6 Electromagnetic Pressure Reducing Valve 6a Solenoid 7 Pressure Reducing Valve 7a Spring 8 Control Pump 9 Orifice 10 Shuttle Valve 11 Relief Valve 12 Tank 31 Spool 32 Pilot Plunger
Claims (1)
動回路に可変絞りを介装し、可変ポンプの傾転角を作動
圧に応じて調整するレギュレータピストンと、可変絞り
の上流側と下流側の差圧に応じてこれを設定差圧に保つ
ようにレギュレータピストンの作動圧を制御するロード
センシングバルブを備えるポンプ傾転角制御装置におい
て、ロードセンシングバルブに差圧設定用の受圧部を設
け、ポンプ傾転角のフィードバックを受けて圧縮される
スプリングのバネ力に応じた２次圧を出力する減圧弁
と、外部信号に応じた２次圧を出力する電磁減圧弁と、
これら減圧弁の１次圧を供給する制御用ポンプと、減圧
弁と電磁減圧弁との２次圧の高い方を選択してロードセ
ンシングバルブの差圧設定用の受圧部に導くシャトル弁
を設けたことを特徴とするポンプ傾転角制御装置。1. A regulator piston for interposing a variable throttle in a drive circuit connecting an actuator and a variable pump, and adjusting a tilt angle of the variable pump according to operating pressure, and a difference between an upstream side and a downstream side of the variable throttle. In a pump tilting angle control device equipped with a load sensing valve that controls the working pressure of a regulator piston so as to maintain it at a set differential pressure according to the pressure, a pressure sensing part for setting the differential pressure is provided on the load sensing valve to A pressure reducing valve that outputs a secondary pressure according to the spring force of a spring that is compressed by receiving feedback of a turning angle, and an electromagnetic pressure reducing valve that outputs a secondary pressure according to an external signal,
A control pump that supplies the primary pressure of these pressure reducing valves, and a shuttle valve that selects the higher secondary pressure of the pressure reducing valve and the electromagnetic pressure reducing valve to the pressure receiving portion for setting the differential pressure of the load sensing valve are provided. A pump tilting angle control device characterized by the above.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24459695A JP3649485B2 (en) | 1995-09-22 | 1995-09-22 | Pump tilt angle control device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24459695A JP3649485B2 (en) | 1995-09-22 | 1995-09-22 | Pump tilt angle control device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0988901A true JPH0988901A (en) | 1997-03-31 |
| JP3649485B2 JP3649485B2 (en) | 2005-05-18 |
Family
ID=17121081
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24459695A Expired - Fee Related JP3649485B2 (en) | 1995-09-22 | 1995-09-22 | Pump tilt angle control device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3649485B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005133537A (en) * | 2003-10-06 | 2005-05-26 | Komatsu Ltd | Hydraulic control device for construction machinery |
| CN102418689A (en) * | 2011-10-31 | 2012-04-18 | 中联重科股份有限公司 | Control system and method of variable pump, hydraulic walking equipment and control method of hydraulic walking equipment |
| CN104179734A (en) * | 2014-08-27 | 2014-12-03 | 浙江德泰机电工程有限公司 | Constant-pressure control device and method for hydraulic pump |
-
1995
- 1995-09-22 JP JP24459695A patent/JP3649485B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005133537A (en) * | 2003-10-06 | 2005-05-26 | Komatsu Ltd | Hydraulic control device for construction machinery |
| CN102418689A (en) * | 2011-10-31 | 2012-04-18 | 中联重科股份有限公司 | Control system and method of variable pump, hydraulic walking equipment and control method of hydraulic walking equipment |
| CN104179734A (en) * | 2014-08-27 | 2014-12-03 | 浙江德泰机电工程有限公司 | Constant-pressure control device and method for hydraulic pump |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3649485B2 (en) | 2005-05-18 |
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