JP2004316815A

JP2004316815A - Method and apparatus for controlling hydraulic circuit

Info

Publication number: JP2004316815A
Application number: JP2003113170A
Authority: JP
Inventors: Atsushi Masuzawa; 淳増沢
Original assignee: Caterpillar Mitsubishi Ltd; Shin Caterpillar Mitsubishi Ltd
Current assignee: Caterpillar Japan Ltd; Caterpillar Mitsubishi Ltd
Priority date: 2003-04-17
Filing date: 2003-04-17
Publication date: 2004-11-11

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controlling method for a hydraulic circuit capable of controlling hydraulic horsepower of the hydraulic circuit actuated by fluid after directly computing dynamic viscosity of the fluid flowing into a conduit. <P>SOLUTION: In a controller, a pump discharge flow amount Q, a conduit mean cross-section area between a first measuring point and a second measuring point A, differential pressure (P1-P2), and a proportional constant k are assigned in Q = k×μ×A×√(P1-P2) to compute an actual dynamic viscosity μ of the fluid. The dynamic viscosity in the appropriate range of the fluid is obtained based on temperature/dynamic viscosity characteristics data which shows a relation between temperature and the dynamic viscosity of the fluid to judge whether the actual dynamic viscosity μ of the fluid is included in the appropriate range of the dynamic viscosity. When the actual dynamic viscosity μ is not included in the appropriate range of the dynamic viscosity, a cooling ability of a cooling means is variably controlled so that the actual dynamic viscosity μ may be included in the appropriate range. When the actual dynamic viscosity μ can not be controlled in the appropriate range within a certain time, it is controlled so that the hydraulic horsepower in the hydraulic circuit may be lowered. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、動粘度を演算された液体により作動される液圧回路の液圧馬力を制御する液圧回路制御方法および液圧回路制御装置に関する。
【０００２】
【従来の技術】
油圧回路において、例えば、作動油の粘度が高い場合は、油圧ポンプにおける吸入抵抗の増加、吐出流量の減少によるキャビテーションの発生、油圧馬力の低下を生じさせ、制御弁における応答性能を悪化させるなどの問題が発生するので、正確な粘度を把握することは重要である。
【０００３】
一般的に、作動油の温度（以下、「油温」という）を計測して、油温−粘度特性データから粘度を求めるようにしているが、油温を介して間接的に作動油の粘度を類推する方法では、作動油の劣化などにより、油温−粘度特性が変化した場合は、正確な粘度を把握することができない。
【０００４】
一方、ポンプとアクチュエータとを備えた油圧回路にあって、作動油の粘度の変化を検出するための回転式粘度センサと、作動油の汚染度を検出するための光学センサとを備えるとともに、作動油中の含有異物量が設定値よりも大きくなったことを第１の判定手段により判定するとともに、作動油の粘度が設定範囲を外れたかどうかを第２の判定手段により判定するようにした作動油の劣化度検出手段がある（例えば、特許文献１参照）。
【０００５】
【特許文献１】
特開平６−１１７９８７号公報（第１頁、図１）
【０００６】
【発明が解決しようとする課題】
このように、従来は、作動油の劣化度を判断する際に、作動油の粘度が設定範囲を外れたかどうかを判定し、粘度が適正範囲内にない場合は、作動油交換の条件としているが、作動油の粘度を適正に制御しながら液圧回路を制御しようとするものではない。
【０００７】
本発明は、このような点に鑑みなされたもので、液体の動粘度との関係で液圧回路を適切に制御できる液圧回路制御方法および液圧回路制御装置を提供することを目的とするものである。
【０００８】
【課題を解決するための手段】
請求項１に記載された発明は、液体の温度および実際の動粘度を計測し、液体の温度と動粘度との関係を表わす温度・動粘度特性データから、計測した温度における液体の適正範囲の動粘度を求め、液体の実際の動粘度が適正範囲の動粘度に含まれるか否かを判断し、実際の動粘度が適正範囲の動粘度に含まれない場合は、液体を冷却する冷却手段の冷却能力を可変制御することによって実際の動粘度を適正範囲に含ませるように制御し、一定時間内に実際の動粘度が適正範囲内に制御された場合は動粘度を演算された液体により作動される液圧回路の運転を継続し、一定時間内に実際の動粘度が適正範囲内に制御されない場合は液圧回路の液圧馬力を低下させるように制御する液圧回路制御方法であり、そして、計測した液体の実際の動粘度が、液体の温度と動粘度との関係を表わす温度・動粘度特性データから求めた液体の適正範囲の動粘度に含まれない場合は、冷却手段の冷却能力を可変制御することによって実際の動粘度を適正範囲に含ませるように制御し、一定時間内に実際の動粘度を適正範囲内に制御できないときは、液圧回路の液圧馬力を低下させるように制御することで、無理な運転継続を防止でき、液体の動粘度との関係で液圧回路を適切に制御できる液圧回路制御方法を提供できる。
【０００９】
請求項２に記載された発明は、請求項１記載の液圧回路制御方法において、実際の動粘度を計測するときは、ポンプから管路に液体を吐出する際のポンプ吐出流量Ｑを把握し、管路内の第１計測箇所の圧力Ｐ１とこの第１計測箇所より下流側に位置する第２計測箇所の圧力Ｐ２との間の差圧（Ｐ１−Ｐ２）を計測し、ポンプ吐出流量Ｑ、第１計測箇所・第２計測箇所間の管路平均断面積Ａ、差圧（Ｐ１−Ｐ２）、比例定数ｋを、Ｑ＝ｋ・μ・Ａ・√（Ｐ１−Ｐ２）に代入して、液体の実際の動粘度μを演算する液圧回路制御方法であり、そして、把握した管路へのポンプ吐出流量と、既知の管路平均断面積と、計測した管路内の差圧と、比例定数とによって、管路内で流れる液体の実際の動粘度を直接演算した上で、この実際の動粘度が、液体の温度と動粘度との関係を表わす温度・動粘度特性データから求めた適正範囲の動粘度に含まれない場合は、冷却手段の冷却能力を可変制御することによって実際の動粘度を適正範囲に含ませるように制御し、一定時間内に実際の動粘度を適正範囲内に制御できないときは液圧回路の液圧馬力を低下させるように制御することで、無理な運転継続を防止でき、液体の動粘度との関係で液圧回路を適切に制御できる。
【００１０】
請求項３に記載された発明は、液体の温度を計測する温度計測手段と、液体の実際の動粘度を計測する動粘度計測手段と、液体を冷却する冷却能力を制御可能な冷却手段と、温度および動粘度を計測された液体により作動される液圧回路と、液体の温度と動粘度との関係を表わす温度・動粘度特性データから、計測した温度における液体の適正範囲の動粘度を求め、液体の実際の動粘度が適正範囲の動粘度に含まれるか否かを判断し、実際の動粘度が適正範囲の動粘度に含まれない場合は、冷却手段の冷却能力を可変制御することによって実際の動粘度を適正範囲に含ませるように制御し、一定時間内に実際の動粘度が適正範囲内に制御された場合は動粘度を計測された液体により作動される液圧回路の運転を継続し、一定時間内に実際の動粘度が適正範囲内に制御されない場合は液圧回路の液圧馬力を低下させるように制御するコントローラとを具備した液圧回路制御装置であり、そして、温度計測手段により液体の温度を計測するとともに、動粘度計測手段により液体の実際の動粘度を計測し、この実際の動粘度が、液体の温度と動粘度との関係を表わす温度・動粘度特性データから求めた適正範囲の動粘度に含まれないと判断したコントローラは、冷却手段の冷却能力を可変制御することによって実際の動粘度を適正範囲内に含ませるように制御し、一定時間内に実際の動粘度を適正範囲内に制御できないときは液圧回路の液圧馬力を低下させるように制御することで、無理な運転継続を防止でき、液体の動粘度との関係で液圧回路を適切に制御できる液圧回路制御装置を提供できる。
【００１１】
請求項４に記載された発明は、請求項３記載の液圧回路制御装置における動粘度計測手段が、ポンプから管路に液体を吐出する際のポンプ吐出流量Ｑを把握するポンプ吐出流量把握手段と、管路内の第１計測箇所の圧力Ｐ１とこの第１計測箇所より下流側に位置する第２計測箇所の圧力Ｐ２との間の差圧（Ｐ１−Ｐ２）を計測する差圧計測手段とを具備し、コントローラは、ポンプ吐出流量Ｑ、第１計測箇所・第２計測箇所間の管路平均断面積Ａ、差圧（Ｐ１−Ｐ２）、比例定数ｋを、Ｑ＝ｋ・μ・Ａ・√（Ｐ１−Ｐ２）に代入して、液体の実際の動粘度μを演算する液圧回路制御装置であり、そして、ポンプ吐出流量把握手段により把握された管路へのポンプ吐出流量と、既知の管路平均断面積と、差圧計測手段により計測された管路内の差圧と、比例定数とから、コントローラは、管路内で流れる液体の実際の動粘度を演算した上で、この実際の動粘度が、温度計測手段により計測された液体の温度と動粘度との関係を表わす温度・動粘度特性データから求めた適正範囲の動粘度に含まれないと判断した場合は、冷却手段の冷却能力を可変制御することによって実際の動粘度を適正範囲に含ませるように制御し、一定時間内に実際の動粘度を適正範囲内に制御できないときは液圧回路の液圧馬力を低下させるように制御することで、無理な運転継続を防止でき、液体の動粘度との関係で液圧回路を適切に制御できる。
【００１２】
請求項５に記載された発明は、請求項３または４記載の液圧回路制御装置において、実際の動粘度が適正範囲の動粘度に含まれない異常状態が一定時間継続したと判断したコントローラから出力された信号により異常状態を表示するモニタを具備した液圧回路制御装置であり、そして、コントローラが、液体の実際の動粘度を適正範囲内に制御できない異常状態であると判断したときは、その異常状態をモニタに表示して、作業者に注意を喚起できる。
【００１３】
請求項６に記載された発明は、請求項３乃至５のいずれか記載の液圧回路制御装置におけるコントローラが、一定時間内に実際の動粘度が適正範囲内に制御されない場合は、液圧回路のポンプ駆動用エンジンの回転速度を減速させるように制御する液圧回路制御装置であり、そして、液体の実際の動粘度を適正範囲に制御できないと判断したコントローラは、液圧回路のポンプ駆動用エンジンの回転速度を減速させることで、液圧回路の液圧馬力を低下させるので、液圧回路の無理な運転継続を防止できる。
【００１４】
請求項７に記載された発明は、請求項３乃至６のいずれか記載の液圧回路制御装置におけるコントローラが、一定時間内に実際の動粘度が適正範囲内に制御されない場合は、液圧回路のポンプ吐出流量を減少させるように制御する液圧回路制御装置であり、そして、液体の実際の動粘度を適正範囲に制御できないと判断したコントローラは、液圧回路のポンプ吐出流量を減少させることで、液圧回路の液圧馬力を低下させるので、液圧回路の無理な運転継続を防止できる。
【００１５】
請求項８に記載された発明は、請求項３乃至７のいずれか記載の液圧回路制御装置におけるコントローラが、一定時間内に実際の動粘度が適正範囲内に制御されない場合は、液圧回路のポンプ吐出圧力を低下させるように制御する液圧回路制御装置であり、そして、液体の実際の動粘度を適正範囲に制御できないと判断したコントローラは、液圧回路のポンプ吐出圧力を低下させることで、液圧回路の液圧馬力を低下させるので、液圧回路の無理な運転継続を防止できる。
【００１６】
【発明の実施の形態】
以下、本発明を図１乃至図５に示された実施の形態を参照しながら詳細に説明する。
【００１７】
図２は、液体粘度計測装置を示し、図３は、この液体粘度計測装置が組込まれた液体粘度制御装置および液圧回路制御装置を示し、これらの装置は、油圧ショベルなどの建設機械に搭載されている。なお、本発明で取扱われる液体は、液圧回路としての油圧回路における動力伝達媒体である作動油の場合を例示するが、これに限られるものではなく、例えばエンジンなどに用いられる潤滑油などにも適用できる。
【００１８】
図３に示されるように、液圧回路としての油圧回路１０において、ポンプ駆動用エンジン１１により駆動されるメインポンプ１２の吐出ライン１３は、油圧ショベルなどの作業機械を作動する油圧モータまたは油圧シリンダなどを制御する負荷回路１４に接続されている。
【００１９】
この負荷回路１４で仕事をした液体としての作動油（以下、この作動油を単に「油」という）は温度上昇するので、その油を油タンク１５に戻す前に冷却するためのオイルクーラ１６が設置されている。
【００２０】
このオイルクーラ１６は、ポンプ駆動用エンジン冷却用のラジエータ１７およびターボチャージャ吸気冷却用のインテークエアクーラ１８と共用または別個の冷却ファン１９を備え、この冷却ファン１９の外気吸引作用により外部から冷風の供給を受ける。
【００２１】
オイルクーラ１６、ラジエータ１７、インテークエアクーラ１８および冷却ファン１９は、油を冷却する冷却能力を制御可能な冷却手段２０を構成している。
【００２２】
この冷却ファン１９は、ポンプ駆動用エンジン１１により駆動されるポンプとしてのパイロットポンプ２１から供給された油により回転される油圧モータ２２によって駆動される。
【００２３】
パイロットポンプ２１は、演算手段としてのコントローラ２３からの制御信号に応じて動作する電磁アクチュエータ２４により制御される容量可変手段２５を備えた可変容量型ポンプであり、容量可変手段２５により可変制御されたポンプ容量ｑに応じてポンプ吐出流量Ｑが変化するので、このポンプ吐出流量Ｑに応じて油圧モータ２２の回転速度を可変制御でき、この油圧モータ２２により駆動される冷却ファン１９の回転速度も可変制御できる。
【００２４】
コントローラ２３には、ポンプ駆動用エンジン１１のエンジン回転速度Ｎを自動制御する制御装置が内蔵されている。例えば、負荷回路１４のコントロール弁をパイロット操作する手動パイロット弁（リモコン弁）のレバー操作がなされない状態が一定時間経過すると、ポンプ駆動用エンジン１１のアクセル位置を自動的にアイドリング状態まで低下させ、レバー操作がなされると同時に、エンジン回転速度Ｎをアクセルダイヤルによる設定位置に回復させる機能などが内蔵されている。
【００２５】
また、このコントローラ２３は、計測した実際の動粘度μが適正範囲の動粘度に含まれない異常状態が一定時間継続したと判断した場合は、その異常状態に係る信号を出力する。
【００２６】
さらに、このコントローラ２３には、入力装置としても機能する表示装置としてのモニタ２７が接続されている。
【００２７】
このモニタ２７は、建設機械の、燃料残量、冷却水温、油温などに関する各種情報を表示するとともに、油の実際の動粘度μが適正範囲の動粘度に含まれない異常状態が一定時間継続したと判断したコントローラ２３から出力された信号により異常状態を表示する機能も有する。
【００２８】
さらに、このコントローラ２３には、オイルクーラ１６の上流側に設けられた電磁比例弁（分流弁）２８と、油タンク１５内の油の温度を計測する温度計測手段としての油温センサ２９とが、それぞれ接続されている。
【００２９】
電磁比例弁２８は、負荷回路１４からオイルクーラ１６を経て油タンク１５に戻される油と、負荷回路１４からオイルクーラ１６を経ないで油タンク１５に戻される油との比率をコントローラ２３からの信号に応じて変化させる分流弁である。
【００３０】
この電磁比例弁２８も、冷却手段２０の冷却能力を制御可能とする手段であり、負荷回路１４からオイルクーラ１６を経て油タンク１５に戻される油の比率を上げることで、冷却能力を上げ、また、負荷回路１４からオイルクーラ１６を経ないで油タンク１５にバイパスされる油の比率を上げることで、冷却能力を下げる。
【００３１】
メインポンプ１２は、コントローラ２３からの制御信号に応じて動作する電磁アクチュエータ３１により制御される容量可変手段３２を備えた可変容量型ポンプであり、このメインポンプ１２の吐出ライン１３と油タンク１５との間には、設定圧可変式のリリーフバルブ３３が設けられている。このリリーフバルブ３３のスプリングプリセット荷重すなわち設定圧は、コントローラ２３からの信号により作動する電磁アクチュエータにより可変制御できる。
【００３２】
コントローラ２３には、ポンプ駆動用エンジン１１のエンジン回転速度Ｎを制御するアクセルアクチュエータ３４と、エンジン回転速度Ｎを計測するための回転速度センサ３５が接続されている。
【００３３】
パイロットポンプ２１の吐出側の管路３６には、差圧計測手段としての、圧力センサ３７と、この圧力センサ３７より下流側に位置する圧力センサ３８とが設けられている。
【００３４】
この図３に示された回路において、４１は、パイロットポンプ２１から管路３６に油を吐出する際のポンプ吐出流量Ｑを把握するポンプ吐出流量把握手段であり、このポンプ吐出流量把握手段４１は、ポンプ駆動用エンジン１１のエンジン回転速度Ｎを計測する回転速度センサ３５を備え、この回転速度センサ３５で計測したパイロットポンプ２１の回転速度と、パイロットポンプ２１の容量可変手段２５を作動する電磁アクチュエータ２４に対するコントローラ２３の指令値より容易に把握可能なパイロットポンプ２１のポンプ容量ｑとによって、パイロットポンプ２１から管路３６に油を吐出する際のポンプ吐出流量Ｑを把握する。
【００３５】
ここで、ポンプ駆動用エンジン１１のエンジン回転速度Ｎを計測する回転速度センサ３５は、エンジン回転速度Ｎを制御するために一般的に用いられている既設センサであり、パイロットポンプ２１のポンプ容量ｑも上記のように既知であるので、このポンプ吐出流量把握手段４１は、特別なセンサを新設することなくパイロットポンプ２１のポンプ吐出流量Ｑ（＝Ｎ・ｑ）を把握できる。
【００３６】
また、差圧計測手段としての圧力センサ３７，３８が、管路３６内の第１計測箇所の圧力Ｐ１と、この第１計測箇所より下流側に位置する第２計測箇所の圧力Ｐ２との間の差圧（Ｐ１−Ｐ２）を計測する。
【００３７】
これらの、パイロットポンプ２１から管路３６に油を吐出する際のポンプ吐出流量Ｑを把握するための回転速度センサ３５などのポンプ吐出流量把握手段４１と、管路３６内の第１計測箇所の圧力Ｐ１とこの第１計測箇所より下流側に位置する第２計測箇所の圧力Ｐ２との間の差圧（Ｐ１−Ｐ２）を計測する圧力センサ３７，３８とによって、動粘度計測手段４２を形成する。
【００３８】
そして、演算手段としてのコントローラ２３は、図２に示されるようにポンプ吐出流量Ｑ、第１計測箇所・第２計測箇所間の管路平均断面積Ａ、差圧（Ｐ１−Ｐ２）、比例定数ｋを、
Ｑ＝Ｃ・Ａ・√（Ｐ１−Ｐ２）＝ｋ・μ・Ａ・√（Ｐ１−Ｐ２）
に代入して、油の実際の動粘度μを演算する。なお、Ｃ（＝ｋ・μ）は流量係数であり、また、比例定数ｋは、予め求めておく。
【００３９】
このように、ポンプ吐出流量把握手段４１により把握された管路３６へのポンプ吐出流量Ｑと、既知の管路平均断面積Ａと、圧力センサ３７，３８により計測された管路３６内の差圧とから、コントローラ２３が油の実際の動粘度μを演算するので、既存の回路を流用して、２箇所の圧力Ｐｌ、Ｐ２を計測すれば動粘度μを算出でき、管路３６内で流れる油の動粘度を直接演算できる安価な液体粘度計測方法および液体粘度計測装置を提供できる。
【００４０】
次に、図４は、各種油の温度と動粘度との関係を示す温度・動粘度特性データであり、このデータは、コントローラ２３に内蔵または付設された記憶装置（メモリ）にマッピングされ、油温センサ２９で計測した温度における油の適正範囲の動粘度が随時読出可能となっている。
【００４１】
例えば、Ｎｏ．３２は、寒冷地（北海道のみ）に適する油の特性を示し、Ｎｏ．４６は、北海道を除く国内全域に適する油の特性を示すものである。
【００４２】
次に、図５は、得られた動粘度が不適合の場合に、冷却手段２０の運転条件を変更して油圧回路１０を継続運転する油粘度制御システムのフローチャートを示す。
【００４３】
この図５に示された油粘度制御システムは、ポンプ吐出流量把握手段４１の回転速度センサ３５により計測されたエンジン回転速度Ｎと、電磁アクチュエータ２４への指令値によりコントローラ２３内で把握されているパイロットポンプ２１のポンプ容量ｑとによって、パイロットポンプ２１から管路３６に油を吐出する際のポンプ吐出流量Ｑ（＝Ｎ・ｑ）を把握し、圧力センサ３７，３８により、管路３６内の第１計測箇所の圧力Ｐ１とこの第１計測箇所より下流側に位置する第２計測箇所の圧力Ｐ２との間の差圧（Ｐ１−Ｐ２）を計測し、油温センサ２９により、油の温度ｔを計測し（ステップ１）、コントローラ２３により、ポンプ吐出流量Ｑ、第１計測箇所・第２計測箇所間の管路平均断面積Ａ、差圧（Ｐ１−Ｐ２）、比例定数ｋを、Ｑ＝ｋ・μ・Ａ・√（Ｐ１−Ｐ２）に代入して、油の実際の動粘度μを演算し（ステップ２）、図４に示された油の温度と動粘度との関係を表わす温度・動粘度特性データから、計測した温度ｔにおける油の適正範囲の動粘度を求め、油の実際の動粘度μが適正範囲の動粘度に含まれるか否かを判断し（ステップ３）、実際の動粘度μが適正範囲の動粘度に含まれない場合は、油を冷却する冷却手段２０の冷却能力を可変制御することによって実際の動粘度μを適正範囲に含ませるように制御する。
【００４４】
すなわち、油の実際の動粘度μが適正範囲の動粘度より低い場合（オーバーヒート状態）は、油を冷却する冷却手段２０の冷却能力を増加させ（ステップ４）、実際の動粘度μが適正範囲の動粘度より高い場合（オーバークール状態）は、油を冷却する冷却手段２０の冷却能力を減少させる（ステップ５）。
【００４５】
例えば、オーバーヒートにより油の実際の動粘度μが適正範囲の動粘度より低い場合は、コントローラ２３により電磁比例弁（分流弁）２８を制御して、冷却手段２０のオイルクーラ１６に供給される油の流量を増加させるように制御することで、あるいは、コントローラ２３によりパイロットポンプ２１の容量可変手段２５を制御して、冷却手段２０が備えた冷却ファン１９の回転速度を増速させるように制御することで、冷却能力を増加させて、油温を強制的に下げ、油の動粘度を適正範囲内に制御する（ステップ４）。
【００４６】
一方、オーバークールにより油の実際の動粘度μが適正範囲の動粘度より高い場合は、コントローラ２３により電磁比例弁（分流弁）２８を制御して、冷却手段２０のオイルクーラ１６に供給される油の流量を減少させるように制御することで、あるいは、コントローラ２３によりパイロットポンプ２１の容量可変手段２５を制御して、冷却ファン１９の回転速度を減速させるように制御することで、冷却能力を減少させて、油温の上昇を図り、油の動粘度を適正範囲内に制御する（ステップ５）。
【００４７】
このような冷却能力の増減制御は、実際の動粘度μが適正範囲内に入るまで継続し、数分毎に、ステップ１の計測を再度行い、再計測で得られた実際の動粘度μが適正範囲内に制御されたか否かを再判定し（ステップ２、３）、実際の動粘度μが適正範囲内に制御された場合は、その動粘度μの油により作動される油圧回路１０の運転を継続する。
【００４８】
一定時間を過ぎても、油の実際の動粘度μが適正範囲内に制御されない粘度不適合が継続した場合、コントローラ２３は、その状態を異常として認知する（ステップ６）。
【００４９】
そして、コントローラ２３は、運転を継続しつつ、モニタ２７上に運転条件を表示する（ステップ７）。
【００５０】
例えば、一定時間経過しても動粘度が高め、または低めで一定の場合は、油粘度不適当として、油タンク１５に充填されている油の推定動粘度を表示し、また、一定時間経過しても、動粘度の変更が起こらない場合は、冷却手段２０に異常が発生しているなどの不具合継続状態での運転を記録する。
【００５１】
この図５に示された油粘度制御システムによれば、把握した管路３６へのポンプ吐出流量Ｑと、既知の管路平均断面積Ａと、計測した管路３６内の差圧とによって、管路３６内で流れる油の実際の動粘度μを直接演算した上で、この実際の動粘度μが、図４に示された油の温度と動粘度との関係を表わす温度・動粘度特性データから求めた適正範囲の動粘度に含まれない場合は、冷却手段２０の冷却能力を可変制御することによって実際の動粘度μを適正範囲内に制御できるので、例えば油の粘度が高い場合に発生する、メインポンプ１２におけるポンプ吸入抵抗の増加、ポンプ吐出流量の減少によるキャビテーションの発生、油圧回路１０が有する液圧有効馬力としての油圧有効馬力の低下、負荷回路１４内のコントロール弁における応答性能の悪化などの問題点を解消できる。
【００５２】
すなわち、オーバーヒート状態などにより油の実際の動粘度μが適正範囲より低い場合は、冷却能力を増加させ、また、オーバークール状態などにより油の実際の動粘度μが適正範囲より高い場合は、冷却能力を減少させることで、油の粘度を適正範囲内に制御できる。
【００５３】
また、ポンプ吐出流量把握手段４１により把握された管路３６へのポンプ吐出流量Ｑと、既知の管路平均断面積Ａと、圧力センサ３７，３８により計測された管路３６内の差圧（Ｐ１−Ｐ２）とから、コントローラ２３が管路３６内で流れる油の実際の動粘度μを直接演算した上で、この実際の動粘度μが、油温センサ２９により計測された油の温度と動粘度との関係を表わす温度・動粘度特性データから求めた適正範囲の動粘度に含まれるか否かを判断し、含まれない場合は、冷却手段２０の冷却能力を可変制御することによって実際の動粘度μを適正範囲内に制御できるので、例えば油の粘度が高い場合に発生する、メインポンプ１２におけるポンプ吸入抵抗の増加、ポンプ吐出流量の減少によるキャビテーションの発生、油圧回路１０の油圧有効馬力の低下、制御弁における応答性能の悪化などの問題点を解消できる。
【００５４】
コントローラ２３が、油の実際の動粘度μを適正範囲内に制御できない異常状態であると判断したときは、その異常状態をモニタ２７に表示して、作業者に注意を喚起できる。
【００５５】
オーバーヒート状態などにより油の実際の動粘度μが適正範囲より低い場合は、コントローラ２３により電磁比例弁（分流弁）２８を制御することにより、冷却手段２０に供給される油の流量を増加させるように制御することで、あるいは、コントローラ２３によりパイロットポンプ２１の容量可変手段２５を制御することにより、冷却ファン１９の回転速度を増加させるように制御することで、冷却能力を増加させて、油の動粘度を適正範囲内に制御できる。
【００５６】
次に、図１は、得られた動粘度が不適合の場合に、油圧回路の運転条件を制御する油圧回路制御システムのフローチャートを示す。
【００５７】
この図１に示された油圧回路制御システムは、ポンプ吐出流量把握手段４１の回転速度センサ３５により計測されたエンジン回転速度Ｎと、電磁アクチュエータ２４への指令値によりコントローラ２３内で把握されているパイロットポンプ２１のポンプ容量ｑとによって、パイロットポンプ２１から管路３６に油を吐出する際のポンプ吐出流量Ｑ（＝Ｎ・ｑ）を把握し、圧力センサ３７，３８により、管路３６内の第１計測箇所の圧力Ｐ１とこの第１計測箇所より下流側に位置する第２計測箇所の圧力Ｐ２との間の差圧（Ｐ１−Ｐ２）を計測し、油温センサ２９により、油の温度ｔを計測し（ステップ１１）、コントローラ２３により、ポンプ吐出流量Ｑ、第１計測箇所・第２計測箇所間の管路３６の管路平均断面積Ａ、差圧（Ｐ１−Ｐ２）、比例定数ｋを、Ｑ＝ｋ・μ・Ａ・√（Ｐ１−Ｐ２）に代入して、油の実際の動粘度μを演算し（ステップ１２）、図４に示される油の温度と動粘度との関係を表わす温度・動粘度特性データから、計測した温度ｔにおける油の適正範囲の動粘度を求め、油の実際の動粘度μが適正範囲の動粘度に含まれるか否かを判断し（ステップ１３）、実際の動粘度μが適正範囲の動粘度に含まれない場合は、油を冷却する冷却手段２０の冷却能力を可変制御することによって実際の動粘度μを適正範囲に含ませるように制御する。
【００５８】
すなわち、オーバークール状態で油の実際の動粘度μが適正範囲の動粘度より高い場合は、コントローラ２３により電磁比例弁（分流弁）２８を制御することにより、一定時間（数分）の間、冷却手段２０のオイルクーラ１６に供給される油の流量を減少させるように制御することで、冷却手段２０の冷却能力を減少させて、油温の上昇を図り、油の動粘度を適正範囲内に制御する（ステップ１４）。
【００５９】
このような冷却能力の制御を一定時間（数分）継続し、一定時間の経過後に、ステップ１１の計測を再度行い、再計測で得られた実際の動粘度μが適正範囲内に制御されたか否かを再判定し（ステップ１２、１３）、実際の動粘度μが適正範囲内に制御された場合は、その動粘度μの油により作動される油圧回路１０の運転を継続する。
【００６０】
一方、一定時間（数分）の経過後も実際の動粘度μが適正範囲内に制御されない場合は、あるいは、オーバーヒート状態となって油の実際の動粘度μが適正範囲の動粘度より低くなった場合、コントローラ２３は、その状態を異常として認知する（ステップ１５）。
【００６１】
そして、このコントローラ２３からモニタ２７上に異常表示、または警報を出力するとともに、油圧回路１０の油圧馬力を低下させるように制御する（ステップ１６）。
【００６２】
例えば、一定時間内に実際の動粘度μが適正範囲内に制御されない異常を認知したコントローラ２３は、アクセルアクチュエータ３４を制御して、ポンプ駆動用エンジン１１のエンジン回転速度Ｎを減速させるように制御したり、電磁アクチュエータ３１により容量可変手段３２を制御して、メインポンプ１２のポンプ吐出流量を減少させるように制御し、これらによりメインポンプ１２のポンプ吸収馬力を低下させ、また、リリーフバルブ３３の設定圧を電磁アクチュエータにより下げて、メインポンプ１２のポンプ吐出圧力を低下させるように制御し、また、場合によってはポンプ駆動用エンジン１１を停止させる。
【００６３】
この図１に示された油圧回路制御システムによれば、把握した管路３６へのポンプ吐出流量Ｑと、既知の管路平均断面積Ａと、計測した管路３６内の差圧とによって、油の実際の動粘度μを演算し、この実際の動粘度μが、図４に示される油の温度と動粘度との関係を表わす温度・動粘度特性データから求めた油の適正範囲の動粘度に含まれない場合は、冷却手段２０の冷却能力を可変制御することによって実際の動粘度μを適正範囲に含ませるように制御し、実際の動粘度μを適正範囲内に制御できるときは油圧回路１０の運転をそのまま継続するとともに、実際の動粘度μを適正範囲内に制御できないときは、油圧回路１０の油圧馬力を低下させるように制御することで、無理な運転継続を防止でき、油の動粘度との関係で油圧回路１０を適切に制御できる。
【００６４】
すなわち、ポンプ吐出流量把握手段４１により把握された管路３６へのポンプ吐出流量Ｑと、既知の管路平均断面積Ａと、圧力センサ３７，３８により計測された管路３６内の差圧とから、コントローラ２３が、油の実際の動粘度μを演算し、この実際の動粘度μが、温度計測手段により計測された油の温度と動粘度との関係を表わす温度・動粘度特性データから求めた油の適正範囲の動粘度に含まれるか否かを判断し、含まれない場合は、冷却手段２０の冷却能力を可変制御することによって実際の動粘度μを適正範囲に含ませるように制御し、実際の動粘度μを適正範囲内に制御できるときは油圧回路１０の運転を継続するとともに、実際の動粘度μを適正範囲内に制御できないときは、油圧回路１０の油圧馬力を低下させるように制御することで、無理な運転継続を防止でき、油の動粘度との関係で油圧回路１０を適切に制御できる。
【００６５】
例えば、油の実際の動粘度μを適正範囲内に制御できないと判断したコントローラ２３は、油圧回路１０のポンプ駆動用エンジン１１のエンジン回転速度Ｎを減速させて、メインポンプ１２の吐出流量を減少させることで、油圧回路１０の油圧馬力を低下させるので、油圧回路１０の無理な運転継続を防止でき、油の動粘度との関係で油圧回路１０を適切に制御できる。
【００６６】
または、油の実際の動粘度μを適正範囲内に制御できないと判断したコントローラ２３は、メインポンプ１２の電磁アクチュエータ３１を制御して、油圧回路１０のポンプ吐出流量を減少させることで、油圧回路１０の油圧馬力を低下させるので、油圧回路１０の無理な運転継続を防止でき、油の動粘度との関係で油圧回路１０を適切に制御できる。
【００６７】
あるいは、油の実際の動粘度μを適正範囲内に制御できないと判断したコントローラ２３は、リリーフバルブ３３の設定圧を可変制御して、油圧回路１０のポンプ吐出圧力を低下させることで、油圧回路１０の油圧馬力を低下させるので、油圧回路１０の無理な運転継続を防止でき、油の動粘度との関係で油圧回路１０を適切に制御できる。
【００６８】
また、コントローラ２３が、油の実際の動粘度μを適正範囲内に制御できない異常状態であると判断したときは、その異常状態をモニタ２７に表示して、作業者に注意を喚起できる。
【００６９】
以上のような液体粘度計測装置は、油圧ショベルなどの建設機械に搭載し、油の動粘度を直接計測するので、測定精度が高く、また、この液体粘度計測装置からの出力信号により、上述のようにポンプ駆動用エンジン１１、メインポンプ１２などの運転条件を自動制御でき、油圧回路１０の油圧馬力を落としたり、冷却手段２０の冷却能力を制御することができるが、さらに、以下のような機能を付加することもできる。
【００７０】
（１）異常なコンタミネーション（ごみ）が混入した場合、差圧（Ｐ１−Ｐ２）が大きくなることで、見かけ上の粘度が上がるため、コンタミネーション混入異常を検知することが可能である。
【００７１】
異常なコンタミネーションがなくても、油の劣化に伴ない発生する不純物などにより油の粘度が高くなった場合も、タイムリーに油の交換時期をオペレータに知らせることが可能となる。通常は、５０００時間程度を目安に交換している。
【００７２】
（２）油タンク１５などに実際に充填されている油の粘度グレードを、モニタ２７に表示できるので、この表示を確認することで、交換時に油の粘度グレードを間違えることがない。
【００７３】
（３）計測された差圧（Ｐ１−Ｐ２）より換算した油の動粘度から、間違った油が充填されている場合などの、油自体が適正でない場合も、その油の交換をモニタ２７などにて勧告することが可能である。例えば、建設機械を温暖な地域から寒冷地に運搬した場合の、油の不適正を機械側から指摘することができる。
【００７４】
（４）本発明は、油圧回路１０の作動油だけでなく、全く同じ考え方をポンプ駆動用エンジン１１の潤滑油にも適用できる。
【００７５】
【発明の効果】
請求項１記載の発明によれば、計測した液体の実際の動粘度が、液体の温度と動粘度との関係を表わす温度・動粘度特性データから求めた液体の適正範囲の動粘度に含まれない場合は、冷却手段の冷却能力を可変制御することによって実際の動粘度を適正範囲に含ませるように制御し、一定時間内に実際の動粘度を適正範囲内に制御できないときは、液圧回路の液圧馬力を低下させるように制御することで、無理な運転継続を防止でき、液体の動粘度との関係で液圧回路を適切に制御できる液圧回路制御方法を提供できる。
【００７６】
請求項２記載の発明によれば、把握した管路へのポンプ吐出流量と、既知の管路平均断面積と、計測した管路内の差圧と、比例定数とによって、管路内で流れる液体の実際の動粘度を直接演算した上で、この実際の動粘度が、液体の温度と動粘度との関係を表わす温度・動粘度特性データから求めた適正範囲の動粘度に含まれない場合は、冷却手段の冷却能力を可変制御することによって実際の動粘度を適正範囲に含ませるように制御し、一定時間内に実際の動粘度を適正範囲内に制御できないときは液圧回路の液圧馬力を低下させるように制御することで、無理な運転継続を防止でき、液体の動粘度との関係で液圧回路を適切に制御できる。
【００７７】
請求項３記載の発明によれば、温度計測手段により液体の温度を計測するとともに、動粘度計測手段により液体の実際の動粘度を計測し、この実際の動粘度が、液体の温度と動粘度との関係を表わす温度・動粘度特性データから求めた適正範囲の動粘度に含まれないと判断したコントローラは、冷却手段の冷却能力を可変制御することによって実際の動粘度を適正範囲内に含ませるように制御し、一定時間内に実際の動粘度を適正範囲内に制御できないときは液圧回路の液圧馬力を低下させるように制御することで、無理な運転継続を防止でき、液体の動粘度との関係で液圧回路を適切に制御できる液圧回路制御装置を提供できる。
【００７８】
請求項４記載の発明によれば、ポンプ吐出流量把握手段により把握された管路へのポンプ吐出流量と、既知の管路平均断面積と、差圧計測手段により計測された管路内の差圧と、比例定数とから、コントローラは、管路内で流れる液体の実際の動粘度を演算した上で、この実際の動粘度が、温度計測手段により計測された液体の温度と動粘度との関係を表わす温度・動粘度特性データから求めた適正範囲の動粘度に含まれないと判断した場合は、冷却手段の冷却能力を可変制御することによって実際の動粘度を適正範囲に含ませるように制御し、一定時間内に実際の動粘度を適正範囲内に制御できないときは液圧回路の液圧馬力を低下させるように制御することで、無理な運転継続を防止でき、液体の動粘度との関係で液圧回路を適切に制御できる。
【００７９】
請求項５記載の発明によれば、コントローラが、液体の実際の動粘度を適正範囲内に制御できない異常状態であると判断したときは、その異常状態をモニタに表示して、作業者に注意を喚起できる。
【００８０】
請求項６記載の発明によれば、液体の実際の動粘度を適正範囲に制御できないと判断したコントローラは、液圧回路のポンプ駆動用エンジンの回転速度を減速させることで、液圧馬力を低下させるので、液圧回路の無理な運転継続を防止できる。
【００８１】
請求項７記載の発明によれば、液体の実際の動粘度を適正範囲に制御できないと判断したコントローラは、液圧回路のポンプ吐出流量を減少させることで、液圧回路の液圧馬力を低下させるので、液圧回路の無理な運転継続を防止できる。
【００８２】
請求項８記載の発明によれば、液体の実際の動粘度を適正範囲に制御できないと判断したコントローラは、液圧回路のポンプ吐出圧力を低下させることで、液圧回路の液圧馬力を低下させるので、液圧回路の無理な運転継続を防止できる。
【図面の簡単な説明】
【図１】本発明に係る液体回路制御方法の一実施の形態を示すフローチャートである。
【図２】同上液体回路制御方法を実施するための液体粘度計測装置の原理を示す説明図である。
【図３】同上液体粘度計測装置が組込まれた液圧回路の一実施の形態を示す回路図である。
【図４】同上液体粘度計測装置が比較対象とする各種油の温度と動粘度との関係を示す温度・動粘度特性図である。
【図５】同上液体粘度計測装置を用いた液体粘度制御方法の一実施の形態を示すフローチャートである。
【符号の説明】
１０液圧回路としての油圧回路
１１ポンプ駆動用エンジン
２０冷却手段
２１ポンプとしてのパイロットポンプ
２３コントローラ
２７モニタ
２９温度計測手段としての油温センサ
３６管路
３７，３８差圧計測手段としての圧力センサ
４１ポンプ吐出流量把握手段
４２動粘度計測手段[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydraulic circuit control method and a hydraulic circuit control device for controlling hydraulic horsepower of a hydraulic circuit operated by a liquid whose kinematic viscosity has been calculated.
[0002]
[Prior art]
In the hydraulic circuit, for example, when the viscosity of the hydraulic oil is high, the suction resistance of the hydraulic pump increases, cavitation occurs due to a decrease in the discharge flow rate, the hydraulic horsepower decreases, and the response performance of the control valve deteriorates. It is important to know the exact viscosity because problems arise.
[0003]
Generally, the temperature of the hydraulic oil (hereinafter referred to as “oil temperature”) is measured and the viscosity is obtained from the oil temperature-viscosity characteristic data. However, the viscosity of the hydraulic oil is indirectly determined via the oil temperature. When the oil temperature-viscosity characteristic changes due to the deterioration of the hydraulic oil or the like, it is not possible to accurately determine the viscosity.
[0004]
On the other hand, in a hydraulic circuit including a pump and an actuator, the hydraulic circuit includes a rotary viscosity sensor for detecting a change in viscosity of hydraulic oil, and an optical sensor for detecting a degree of contamination of hydraulic oil. The first determining means determines that the amount of foreign matter contained in the oil has become larger than the set value, and the second determining means determines whether the viscosity of the hydraulic oil is out of the set range. There is oil deterioration degree detection means (for example, see Patent Document 1).
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. H6-117987 (page 1, FIG. 1)
[0006]
[Problems to be solved by the invention]
As described above, conventionally, when determining the degree of deterioration of the hydraulic oil, it is determined whether or not the viscosity of the hydraulic oil is out of a set range. However, it is not intended to control the hydraulic circuit while appropriately controlling the viscosity of the hydraulic oil.
[0007]
The present invention has been made in view of such a point, and an object of the present invention is to provide a hydraulic circuit control method and a hydraulic circuit control device that can appropriately control a hydraulic circuit in relation to the kinematic viscosity of a liquid. Things.
[0008]
[Means for Solving the Problems]
The invention described in claim 1 measures the temperature and the actual kinematic viscosity of the liquid, and determines the proper range of the liquid at the measured temperature from the temperature / kinematic viscosity characteristic data representing the relationship between the temperature and the kinematic viscosity of the liquid. Determine the kinematic viscosity, determine whether the actual kinematic viscosity of the liquid is included in the appropriate range of kinematic viscosity, if the actual kinematic viscosity is not included in the appropriate range of kinematic viscosity, cooling means to cool the liquid The kinematic viscosity is controlled by the calculated liquid if the actual kinematic viscosity is controlled within the appropriate range within a certain time by variably controlling the cooling capacity of the kinematic viscosity. This is a hydraulic circuit control method that continues to operate the hydraulic circuit to be operated, and if the actual kinematic viscosity is not controlled within an appropriate range within a certain period of time, reduces the hydraulic horsepower of the hydraulic circuit. And the actual kinematic viscosity of the measured liquid Is not included in the kinematic viscosity in the appropriate range of the liquid obtained from the temperature / kinematic viscosity characteristic data representing the relationship between the temperature and the kinematic viscosity of the liquid, the actual dynamic dynamic range is controlled by variably controlling the cooling capacity of the cooling means. If the viscosity is controlled to be within the appropriate range, and if the actual kinematic viscosity cannot be controlled within the appropriate range within a certain period of time, the hydraulic circuit of the hydraulic circuit will be controlled to reduce the hydraulic horsepower, which will result in improper operation. It is possible to provide a hydraulic circuit control method capable of preventing continuation and appropriately controlling the hydraulic circuit in relation to the kinematic viscosity of the liquid.
[0009]
According to a second aspect of the present invention, in the hydraulic circuit control method according to the first aspect, when the actual kinematic viscosity is measured, the pump discharge flow rate Q at the time of discharging the liquid from the pump to the pipeline is grasped. , The pressure difference (P1−P2) between the pressure P1 at the first measurement point in the pipeline and the pressure P2 at the second measurement point located downstream from the first measurement point is measured, and the pump discharge flow rate Q , The average pipe cross-sectional area A between the first measurement point and the second measurement point, the differential pressure (P1−P2), and the proportionality constant k are substituted into Q = k · μ · A · √ (P1−P2). Is a hydraulic circuit control method that calculates the actual kinematic viscosity μ of the liquid, and the pump discharge flow rate to the grasped pipeline, the known pipeline average cross-sectional area, and the measured differential pressure in the pipeline. Calculates the actual kinematic viscosity of the liquid flowing in the pipeline directly by using the proportional constant and the actual kinematic viscosity. If the kinematic viscosity is not included in the appropriate range obtained from the temperature / kinematic viscosity characteristic data representing the relationship between the temperature and the kinematic viscosity, the actual kinematic viscosity is adjusted to the appropriate range by variably controlling the cooling capacity of the cooling means. If the actual kinematic viscosity cannot be controlled within an appropriate range within a certain period of time, control is performed so as to reduce the hydraulic horsepower of the hydraulic circuit, thereby preventing excessive continuation of operation. The hydraulic circuit can be appropriately controlled in relation to the kinematic viscosity of the hydraulic circuit.
[0010]
The invention described in claim 3 is a temperature measuring means for measuring the temperature of the liquid, a kinematic viscosity measuring means for measuring the actual kinematic viscosity of the liquid, a cooling means capable of controlling a cooling capacity for cooling the liquid, From the hydraulic circuit operated by the liquid whose temperature and kinematic viscosity has been measured, and the temperature / kinematic viscosity characteristic data indicating the relationship between the temperature and the kinematic viscosity of the liquid, determine the kinematic viscosity of the liquid within the appropriate range at the measured temperature. , Determine whether the actual kinematic viscosity of the liquid is included in the appropriate range of kinematic viscosity, and if the actual kinematic viscosity is not included in the appropriate range of kinematic viscosity, variably control the cooling capacity of the cooling means. The operation of the hydraulic circuit that is controlled by the liquid whose kinematic viscosity is measured when the actual kinematic viscosity is controlled within the appropriate range within a certain period of time The actual movement within a certain period of time. And a controller for controlling the hydraulic horsepower of the hydraulic circuit to reduce the hydraulic horsepower when the degree is not controlled within the appropriate range, and the temperature of the liquid is measured by temperature measuring means. The actual kinematic viscosity of the liquid is measured by the kinematic viscosity measuring means, and the actual kinematic viscosity is included in the appropriate range of kinematic viscosity obtained from the temperature / kinematic viscosity characteristic data representing the relationship between the liquid temperature and the kinematic viscosity. The controller that determines that the actual kinematic viscosity is not within the appropriate range by controlling the cooling capacity of the cooling means to be within the appropriate range by variably controlling the cooling capacity of the cooling means cannot be controlled within the predetermined time. In such a case, by controlling the hydraulic power of the hydraulic circuit to decrease, it is possible to prevent unreasonable continuation of operation and to provide a hydraulic circuit control device that can appropriately control the hydraulic circuit in relation to the kinematic viscosity of the liquid. It can be.
[0011]
According to a fourth aspect of the present invention, there is provided a hydraulic circuit control device according to the third aspect, wherein the kinematic viscosity measuring means grasps a pump discharge flow rate Q when the liquid is discharged from the pump to the pipeline. Pressure measuring means for measuring a pressure difference (P1-P2) between a pressure P1 at a first measurement point in a pipeline and a pressure P2 at a second measurement point located downstream of the first measurement point. The controller calculates the pump discharge flow rate Q, the average pipe cross-sectional area A between the first measurement point and the second measurement point, the differential pressure (P1−P2), and the proportionality constant k as follows: Q = k · μ · A · √ (P1−P2) is a hydraulic circuit control device that calculates the actual kinematic viscosity μ of the liquid, and calculates the pump discharge flow rate to the pipeline grasped by the pump discharge flow rate grasping means. , The known mean cross-sectional area of the pipe and the difference in the pipe measured by the differential pressure measuring means From the pressure and the proportionality constant, the controller calculates the actual kinematic viscosity of the liquid flowing in the pipeline, and then calculates the actual kinematic viscosity between the temperature and the kinematic viscosity of the liquid measured by the temperature measuring means. If it is determined that the kinematic viscosity is not included in the appropriate range obtained from the temperature / kinematic viscosity characteristic data representing the relationship, the actual kinematic viscosity is included in the appropriate range by variably controlling the cooling capacity of the cooling means. If the actual kinematic viscosity cannot be controlled within an appropriate range within a certain period of time, by controlling the hydraulic horsepower of the hydraulic circuit to decrease, it is possible to prevent unreasonable continuation of operation and improve the kinematic viscosity of the liquid. Therefore, the hydraulic circuit can be appropriately controlled.
[0012]
According to a fifth aspect of the present invention, in the hydraulic circuit control device according to the third or fourth aspect, the controller determines that the abnormal state in which the actual kinematic viscosity is not included in the appropriate range of the kinetic viscosity has continued for a certain period of time. A hydraulic circuit control device including a monitor that displays an abnormal state by the output signal, and when the controller determines that the actual kinematic viscosity of the liquid is in an abnormal state that cannot be controlled within an appropriate range, The abnormal state can be displayed on a monitor to alert the operator.
[0013]
According to a sixth aspect of the present invention, the controller in the hydraulic circuit controller according to any one of the third to fifth aspects is configured such that, when the actual kinematic viscosity is not controlled within an appropriate range within a predetermined time, the hydraulic circuit is controlled. Is a hydraulic circuit control device that controls the rotation speed of the pump drive engine to be reduced, and the controller that determines that the actual kinematic viscosity of the liquid cannot be controlled to an appropriate range is a hydraulic circuit control device. Since the hydraulic horsepower of the hydraulic circuit is reduced by reducing the rotation speed of the engine, it is possible to prevent the hydraulic circuit from being forcedly operated.
[0014]
According to a seventh aspect of the present invention, the controller in the hydraulic circuit controller according to any one of the third to sixth aspects is configured such that, if the actual kinematic viscosity is not controlled within an appropriate range within a predetermined time, the hydraulic circuit is controlled. A hydraulic circuit control device that controls to reduce the pump discharge flow rate of the hydraulic circuit, and the controller that determines that the actual kinematic viscosity of the liquid cannot be controlled to an appropriate range may reduce the pump discharge flow rate of the hydraulic circuit. Thus, the hydraulic horsepower of the hydraulic circuit is reduced, so that the hydraulic circuit can be prevented from being forcedly operated.
[0015]
According to an eighth aspect of the present invention, the controller in the hydraulic circuit controller according to any one of the third to seventh aspects is configured such that, if the actual kinematic viscosity is not controlled within an appropriate range within a predetermined time, the hydraulic circuit is controlled. A hydraulic circuit control device that controls to reduce the pump discharge pressure of the hydraulic circuit, and the controller that determines that the actual kinematic viscosity of the liquid cannot be controlled within an appropriate range can reduce the pump discharge pressure of the hydraulic circuit. Thus, the hydraulic horsepower of the hydraulic circuit is reduced, so that the hydraulic circuit can be prevented from being forcedly operated.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the embodiments shown in FIGS.
[0017]
FIG. 2 shows a liquid viscosity measurement device, and FIG. 3 shows a liquid viscosity control device and a hydraulic circuit control device in which the liquid viscosity measurement device is incorporated. These devices are mounted on construction machines such as hydraulic excavators. Have been. The liquid handled in the present invention is exemplified by the case of hydraulic oil, which is a power transmission medium in a hydraulic circuit as a hydraulic circuit, but is not limited thereto, and may be, for example, lubricating oil used in an engine or the like. Is also applicable.
[0018]
As shown in FIG. 3, in a hydraulic circuit 10 as a hydraulic circuit, a discharge line 13 of a main pump 12 driven by a pump driving engine 11 is provided with a hydraulic motor or a hydraulic cylinder for operating a work machine such as a hydraulic shovel. Connected to a load circuit 14 for controlling the operation.
[0019]
Since the temperature of the hydraulic oil (hereinafter, simply referred to as “oil”) as a liquid that has worked in the load circuit 14 rises, an oil cooler 16 for cooling the oil before returning the oil to the oil tank 15 is provided. is set up.
[0020]
The oil cooler 16 includes a radiator 17 for cooling the engine for driving the pump and an intake air cooler 18 for cooling the intake air of the turbocharger, or a cooling fan 19 which is shared or separate from the outside. Receive supply.
[0021]
The oil cooler 16, the radiator 17, the intake air cooler 18, and the cooling fan 19 constitute a cooling means 20 capable of controlling a cooling capacity for cooling oil.
[0022]
The cooling fan 19 is driven by a hydraulic motor 22 rotated by oil supplied from a pilot pump 21 as a pump driven by the pump driving engine 11.
[0023]
The pilot pump 21 is a variable displacement pump provided with a displacement variable device 25 controlled by an electromagnetic actuator 24 that operates in response to a control signal from a controller 23 as a calculation device, and is variably controlled by the displacement variable device 25. Since the pump discharge flow rate Q changes in accordance with the pump displacement q, the rotation speed of the hydraulic motor 22 can be variably controlled in accordance with the pump discharge flow rate Q, and the rotation speed of the cooling fan 19 driven by the hydraulic motor 22 also changes. Can control.
[0024]
The controller 23 has a built-in control device for automatically controlling the engine rotation speed N of the pump driving engine 11. For example, when the lever operation of the manual pilot valve (remote control valve) for pilot-operating the control valve of the load circuit 14 has not been performed for a certain period of time, the accelerator position of the pump driving engine 11 is automatically lowered to the idling state, A function for restoring the engine rotation speed N to the position set by the accelerator dial at the same time as the lever operation is provided is built in.
[0025]
When the controller 23 determines that an abnormal state in which the measured actual kinematic viscosity μ is not included in the appropriate range of kinematic viscosity has continued for a certain period of time, the controller 23 outputs a signal relating to the abnormal state.
[0026]
Further, a monitor 27 as a display device that also functions as an input device is connected to the controller 23.
[0027]
The monitor 27 displays various information on the remaining amount of fuel, cooling water temperature, oil temperature, etc. of the construction machine, and an abnormal state in which the actual kinetic viscosity μ of the oil is not included in the appropriate range of kinetic viscosity for a certain period of time. It also has a function of displaying an abnormal state based on a signal output from the controller 23 that has determined that the abnormality has occurred.
[0028]
Further, the controller 23 includes an electromagnetic proportional valve (shunt valve) 28 provided on the upstream side of the oil cooler 16 and an oil temperature sensor 29 as a temperature measuring means for measuring the temperature of the oil in the oil tank 15. , Are connected respectively.
[0029]
The electromagnetic proportional valve 28 determines the ratio between the oil returned from the load circuit 14 to the oil tank 15 via the oil cooler 16 and the oil returned from the load circuit 14 to the oil tank 15 without passing through the oil cooler 16 from the controller 23. This is a shunt valve that changes according to a signal.
[0030]
This electromagnetic proportional valve 28 is also a means capable of controlling the cooling capacity of the cooling means 20, and increases the cooling capacity by increasing the ratio of oil returned from the load circuit 14 to the oil tank 15 via the oil cooler 16, Also, the cooling capacity is reduced by increasing the ratio of the oil bypassed from the load circuit 14 to the oil tank 15 without passing through the oil cooler 16.
[0031]
The main pump 12 is a variable displacement pump provided with a displacement variable means 32 controlled by an electromagnetic actuator 31 that operates in accordance with a control signal from a controller 23. Between them, a relief valve 33 of a variable set pressure type is provided. The spring preset load, that is, the set pressure of the relief valve 33 can be variably controlled by an electromagnetic actuator that operates according to a signal from the controller 23.
[0032]
An accelerator actuator 34 for controlling the engine rotation speed N of the pump driving engine 11 and a rotation speed sensor 35 for measuring the engine rotation speed N are connected to the controller 23.
[0033]
In the pipeline 36 on the discharge side of the pilot pump 21, a pressure sensor 37 as a differential pressure measuring means and a pressure sensor 38 located downstream of the pressure sensor 37 are provided.
[0034]
In the circuit shown in FIG. 3, reference numeral 41 denotes a pump discharge flow rate grasping means for grasping a pump discharge flow rate Q when oil is discharged from the pilot pump 21 to the pipeline 36. A rotation speed sensor 35 for measuring an engine rotation speed N of the pump driving engine 11, and an electromagnetic actuator for operating the rotation speed of the pilot pump 21 measured by the rotation speed sensor 35 and the capacity variable means 25 of the pilot pump 21. The pump discharge flow rate Q when the oil is discharged from the pilot pump 21 to the pipeline 36 is grasped from the pump capacity q of the pilot pump 21 which can be easily grasped from the command value of the controller 23 for the pump 24.
[0035]
Here, the rotation speed sensor 35 that measures the engine rotation speed N of the pump driving engine 11 is an existing sensor generally used to control the engine rotation speed N, and the pump capacity q of the pilot pump 21 is The pump discharge flow rate grasping means 41 can also grasp the pump discharge flow rate Q (= N · q) of the pilot pump 21 without newly providing a special sensor.
[0036]
Further, the pressure sensors 37 and 38 as the differential pressure measuring means are provided between the pressure P1 at the first measurement point in the pipe 36 and the pressure P2 at the second measurement point located downstream of the first measurement point. Is measured (P1-P2).
[0037]
These pump discharge flow rate grasping means 41 such as a rotation speed sensor 35 for grasping a pump discharge flow rate Q when oil is discharged from the pilot pump 21 to the pipe 36, and a first measurement point in the pipe 36. The kinematic viscosity measuring means 42 is formed by the pressure sensors 37 and 38 for measuring the differential pressure (P1-P2) between the pressure P1 and the pressure P2 at the second measuring point located downstream of the first measuring point. I do.
[0038]
Then, as shown in FIG. 2, the controller 23 as a calculating means includes a pump discharge flow rate Q, an average sectional area A of the pipeline between the first measurement point and the second measurement point, a differential pressure (P1−P2), a proportional constant k
Q = C · A · √ (P1−P2) = k · μ · A · √ (P1−P2)
To calculate the actual kinematic viscosity μ of the oil. Note that C (= k · μ) is a flow coefficient, and a proportional constant k is obtained in advance.
[0039]
As described above, the pump discharge flow rate Q to the pipe 36 grasped by the pump discharge flow rate grasping means 41, the known pipe average cross-sectional area A, and the difference in the pipe 36 measured by the pressure sensors 37 and 38. Since the controller 23 calculates the actual kinematic viscosity μ of the oil from the pressure and the existing circuit, the kinematic viscosity μ can be calculated by measuring the pressures Pl and P2 at two locations using the existing circuit. An inexpensive liquid viscosity measurement method and liquid viscosity measurement device capable of directly calculating the kinematic viscosity of flowing oil can be provided.
[0040]
Next, FIG. 4 shows temperature / kinematic viscosity characteristic data indicating the relationship between the temperature and the kinematic viscosity of various types of oil. This data is mapped to a storage device (memory) built in or attached to the controller 23, and The kinematic viscosity of the oil in the appropriate range at the temperature measured by the temperature sensor 29 can be read at any time.
[0041]
For example, no. No. 32 shows oil characteristics suitable for cold regions (Hokkaido only). Reference numeral 46 indicates the characteristics of oil suitable for the whole of Japan except for Hokkaido.
[0042]
Next, FIG. 5 shows a flowchart of an oil viscosity control system that changes the operating condition of the cooling means 20 and continuously operates the hydraulic circuit 10 when the obtained kinematic viscosity is incompatible.
[0043]
The oil viscosity control system shown in FIG. 5 is grasped in the controller 23 by the engine rotation speed N measured by the rotation speed sensor 35 of the pump discharge flow rate grasping means 41 and the command value to the electromagnetic actuator 24. The pump discharge flow rate Q (= N · q) when oil is discharged from the pilot pump 21 to the pipe 36 is grasped from the pump capacity q of the pilot pump 21, and the pressure sensors 37 and 38 are used to detect the pump discharge flow rate Q in the pipe 36. The pressure difference (P1-P2) between the pressure P1 at the first measurement point and the pressure P2 at the second measurement point located downstream of the first measurement point is measured, and the oil temperature sensor 29 measures the oil temperature. t is measured (step 1), and the controller 23 calculates the pump discharge flow rate Q, the average cross-sectional area A of the pipeline between the first measurement point and the second measurement point, the differential pressure (P1-P2), and the proportionality constant k. The actual kinematic viscosity μ of the oil is calculated by substituting Q = k · μ · A · √ (P1−P2) (step 2), and the relationship between the temperature and the kinematic viscosity of the oil shown in FIG. The kinematic viscosity in the appropriate range of the oil at the measured temperature t is determined from the represented temperature / kinematic viscosity characteristic data, and it is determined whether or not the actual kinematic viscosity μ of the oil is included in the kinematic viscosity in the appropriate range (step 3). If the actual kinematic viscosity μ is not included in the appropriate range of kinematic viscosity, the cooling capacity of the cooling means 20 for cooling the oil is controlled to be variable so that the actual kinematic viscosity μ is included in the appropriate range. .
[0044]
That is, when the actual kinematic viscosity μ of the oil is lower than the appropriate range of kinematic viscosity (overheating state), the cooling capacity of the cooling means 20 for cooling the oil is increased (step 4), and the actual kinematic viscosity μ is adjusted to the appropriate range. If the kinetic viscosity is higher than the kinematic viscosity (overcooled state), the cooling capacity of the cooling means 20 for cooling the oil is reduced (step 5).
[0045]
For example, when the actual kinematic viscosity μ of the oil is lower than the appropriate range of kinematic viscosity due to overheating, the controller 23 controls the electromagnetic proportional valve (shunt valve) 28 to supply the oil supplied to the oil cooler 16 of the cooling means 20. Or the controller 23 controls the capacity varying means 25 of the pilot pump 21 to increase the rotation speed of the cooling fan 19 provided in the cooling means 20. As a result, the cooling capacity is increased, the oil temperature is forcibly reduced, and the kinematic viscosity of the oil is controlled within an appropriate range (step 4).
[0046]
On the other hand, if the actual kinematic viscosity μ of the oil is higher than the appropriate range of kinematic viscosity due to overcooling, the controller 23 controls the electromagnetic proportional valve (shunt valve) 28 to supply the oil to the oil cooler 16 of the cooling means 20. The cooling capacity is controlled by controlling the flow rate of the oil to be reduced, or by controlling the variable capacity means 25 of the pilot pump 21 by the controller 23 to reduce the rotation speed of the cooling fan 19. By decreasing the oil temperature, the oil temperature is increased, and the kinematic viscosity of the oil is controlled within an appropriate range (step 5).
[0047]
The control for increasing or decreasing the cooling capacity is continued until the actual kinematic viscosity μ falls within the appropriate range. Every few minutes, the measurement in step 1 is performed again, and the actual kinematic viscosity μ obtained by the re-measurement is obtained. It is again determined whether or not the control has been performed within the appropriate range (steps 2 and 3). If the actual kinematic viscosity μ has been controlled to be within the appropriate range, the hydraulic circuit 10 operated by the oil having the kinematic viscosity μ Continue driving.
[0048]
If the viscosity incompatibility in which the actual kinematic viscosity μ of the oil is not controlled within the appropriate range continues after a certain period of time, the controller 23 recognizes the state as abnormal (step 6).
[0049]
Then, the controller 23 displays the operating conditions on the monitor 27 while continuing the operation (Step 7).
[0050]
For example, if the kinematic viscosity is high or low and constant after a certain period of time, the estimated kinematic viscosity of the oil filled in the oil tank 15 is displayed as inappropriate oil viscosity, and after a certain period of time. Even if the change in the kinematic viscosity does not occur, the operation in a state where the malfunction is continued such as an abnormality in the cooling means 20 is recorded.
[0051]
According to the oil viscosity control system shown in FIG. 5, the pump discharge flow rate Q to the pipe 36 that has been grasped, the known pipe average cross-sectional area A, and the measured differential pressure in the pipe 36 are: After the actual kinematic viscosity μ of the oil flowing in the pipe 36 is directly calculated, the actual kinematic viscosity μ is used as a temperature / kinematic viscosity characteristic representing the relationship between the oil temperature and the kinematic viscosity shown in FIG. If the kinematic viscosity is not included in the appropriate range obtained from the data, the actual kinematic viscosity μ can be controlled within the appropriate range by variably controlling the cooling capacity of the cooling means 20. The generated pump suction resistance in the main pump 12 increases, cavitation occurs due to a decrease in the pump discharge flow rate, the hydraulic effective horsepower decreases as the hydraulic effective horsepower of the hydraulic circuit 10, and the responsiveness of the control valve in the load circuit 14 The problems such as the deterioration can be eliminated.
[0052]
That is, when the actual kinematic viscosity μ of the oil is lower than the appropriate range due to an overheating state or the like, the cooling capacity is increased, and when the actual kinematic viscosity μ of the oil is higher than the appropriate range due to an overcooled state or the like, the cooling capacity is increased. By reducing the capacity, the viscosity of the oil can be controlled within an appropriate range.
[0053]
Further, the pump discharge flow rate Q to the pipe 36 grasped by the pump discharge flow rate grasping means 41, the known pipe average cross-sectional area A, and the differential pressure in the pipe 36 measured by the pressure sensors 37 and 38 ( P1−P2), the controller 23 directly calculates the actual kinematic viscosity μ of the oil flowing in the pipe 36, and the actual kinematic viscosity μ is calculated based on the oil temperature measured by the oil temperature sensor 29 and It is determined whether or not the kinematic viscosity is within the appropriate range obtained from the temperature / kinematic viscosity characteristic data representing the relationship with the kinematic viscosity. If not, the actual cooling performance of the cooling means 20 is controlled by variably controlling the cooling capacity. Can be controlled within an appropriate range, so that, for example, when the viscosity of oil is high, the pump suction resistance in the main pump 12 increases, cavitation occurs due to a decrease in the pump discharge flow rate, and the hydraulic circuit 10 Decrease in pressure effective horsepower, a problem such as deterioration of the response performance in control valve can be eliminated.
[0054]
When the controller 23 determines that the abnormal state cannot control the actual kinematic viscosity μ of the oil within an appropriate range, the abnormal state is displayed on the monitor 27 to alert the operator.
[0055]
When the actual kinematic viscosity μ of the oil is lower than the appropriate range due to an overheating state or the like, the controller 23 controls the solenoid proportional valve (shunt valve) 28 to increase the flow rate of the oil supplied to the cooling means 20. Or the controller 23 controls the variable capacity means 25 of the pilot pump 21 to increase the rotational speed of the cooling fan 19, thereby increasing the cooling capacity and Kinematic viscosity can be controlled within an appropriate range.
[0056]
Next, FIG. 1 shows a flowchart of a hydraulic circuit control system for controlling operating conditions of the hydraulic circuit when the obtained kinematic viscosity is incompatible.
[0057]
The hydraulic circuit control system shown in FIG. 1 is grasped in the controller 23 by the engine speed N measured by the revolution speed sensor 35 of the pump discharge flow rate grasping means 41 and the command value to the electromagnetic actuator 24. The pump discharge flow rate Q (= N · q) when oil is discharged from the pilot pump 21 to the pipe 36 is grasped from the pump capacity q of the pilot pump 21, and the pressure sensors 37 and 38 are used to detect the pump discharge flow rate Q in the pipe 36. The pressure difference (P1-P2) between the pressure P1 at the first measurement point and the pressure P2 at the second measurement point located downstream of the first measurement point is measured, and the oil temperature sensor 29 measures the oil temperature. t is measured (step 11), and the controller 23 controls the pump discharge flow rate Q, the average cross-sectional area A of the pipe 36 between the first measurement point and the second measurement point, and the differential pressure (P1-P2). By substituting the proportionality constant k into Q = k · μ · A · √ (P1−P2), the actual kinematic viscosity μ of the oil is calculated (step 12), and the temperature and the kinematic viscosity of the oil shown in FIG. From the temperature and kinematic viscosity characteristic data representing the relationship, the kinetic viscosity of the oil in the appropriate range at the measured temperature t is determined, and it is determined whether or not the actual kinematic viscosity μ of the oil is included in the kinetic viscosity in the appropriate range. (Step 13) If the actual kinematic viscosity μ is not included in the appropriate range of kinematic viscosity, the actual kinematic viscosity μ is included in the appropriate range by variably controlling the cooling capacity of the cooling means 20 for cooling the oil. Control.
[0058]
That is, when the actual kinematic viscosity μ of the oil is higher than the appropriate range of kinematic viscosity in the overcooled state, the controller 23 controls the electromagnetic proportional valve (shunt valve) 28 for a certain period of time (several minutes). By controlling the flow rate of the oil supplied to the oil cooler 16 of the cooling means 20 to be reduced, the cooling capacity of the cooling means 20 is reduced, the oil temperature is increased, and the kinematic viscosity of the oil is set within an appropriate range. (Step 14).
[0059]
Such control of the cooling capacity is continued for a certain time (several minutes), and after the lapse of the certain time, the measurement in step 11 is performed again, and whether the actual kinematic viscosity μ obtained by the re-measurement has been controlled within an appropriate range. It is determined again whether or not it is (steps 12 and 13). If the actual kinematic viscosity μ is controlled within the appropriate range, the operation of the hydraulic circuit 10 operated by the oil having the kinematic viscosity μ is continued.
[0060]
On the other hand, if the actual kinematic viscosity μ is not controlled within the appropriate range even after the lapse of a certain time (several minutes), or if the actual kinematic viscosity μ of the oil becomes lower than the kinematic viscosity in the appropriate range due to overheating. If so, the controller 23 recognizes the state as abnormal (step 15).
[0061]
Then, the controller 23 outputs an abnormality display or a warning on the monitor 27 and controls the hydraulic horsepower of the hydraulic circuit 10 to decrease (step 16).
[0062]
For example, the controller 23 that has recognized that the actual kinematic viscosity μ is not controlled within the appropriate range within a certain time period controls the accelerator actuator 34 so as to reduce the engine rotation speed N of the pump driving engine 11. Or the electromagnetic actuator 31 controls the capacity variable means 32 to control the pump discharge flow rate of the main pump 12 so as to reduce the pump absorption horsepower of the main pump 12. The set pressure is reduced by an electromagnetic actuator to control the pump discharge pressure of the main pump 12 to decrease, and in some cases, the pump driving engine 11 is stopped.
[0063]
According to the hydraulic circuit control system shown in FIG. 1, the pump discharge flow rate Q to the pipe 36, the known pipe average cross-sectional area A, and the measured differential pressure in the pipe 36 The actual kinematic viscosity μ of the oil is calculated, and the actual kinematic viscosity μ is calculated based on the temperature / kinematic viscosity characteristic data representing the relationship between the oil temperature and the kinematic viscosity shown in FIG. When the kinematic viscosity μ is not included in the viscosity, the actual kinematic viscosity μ is controlled to be within an appropriate range by variably controlling the cooling capacity of the cooling means 20. When the operation of the hydraulic circuit 10 is continued as it is, and when the actual kinematic viscosity μ cannot be controlled within an appropriate range, by controlling the hydraulic horsepower of the hydraulic circuit 10 to be reduced, it is possible to prevent unreasonable operation continuation, Hydraulic circuit 10 is applied in relation to the kinematic viscosity of oil. You can control it.
[0064]
That is, the pump discharge flow rate Q to the pipe 36 grasped by the pump discharge flow rate grasping means 41, the known pipe average cross-sectional area A, and the differential pressure in the pipe 36 measured by the pressure sensors 37 and 38. , The controller 23 calculates the actual kinematic viscosity μ of the oil, and the actual kinematic viscosity μ is calculated from the temperature / kinematic viscosity characteristic data representing the relationship between the oil temperature and the kinematic viscosity measured by the temperature measuring means. It is determined whether or not the obtained oil is included in the appropriate range of kinematic viscosity. If not, the actual kinematic viscosity μ is set to the appropriate range by variably controlling the cooling capacity of the cooling means 20. When the actual dynamic viscosity μ can be controlled within the appropriate range, the operation of the hydraulic circuit 10 is continued. When the actual dynamic viscosity μ cannot be controlled within the appropriate range, the hydraulic horsepower of the hydraulic circuit 10 is reduced. Control Thereby, unreasonable continuation of operation can be prevented and the hydraulic circuit 10 can be appropriately controlled in relation to the kinematic viscosity of oil.
[0065]
For example, the controller 23 that has determined that the actual kinetic viscosity μ of the oil cannot be controlled within an appropriate range, reduces the engine rotation speed N of the pump driving engine 11 of the hydraulic circuit 10 to reduce the discharge flow rate of the main pump 12. By doing so, the hydraulic horsepower of the hydraulic circuit 10 is reduced, so that excessive operation of the hydraulic circuit 10 can be prevented, and the hydraulic circuit 10 can be appropriately controlled in relation to the kinematic viscosity of the oil.
[0066]
Alternatively, the controller 23 that has determined that the actual kinematic viscosity μ of the oil cannot be controlled within an appropriate range, controls the electromagnetic actuator 31 of the main pump 12 to reduce the pump discharge flow rate of the hydraulic circuit 10, thereby reducing the hydraulic circuit Since the hydraulic horsepower of the hydraulic circuit 10 is reduced, the hydraulic circuit 10 can be prevented from being forcedly operated, and the hydraulic circuit 10 can be appropriately controlled in relation to the kinematic viscosity of the oil.
[0067]
Alternatively, the controller 23 that determines that the actual kinematic viscosity μ of the oil cannot be controlled within an appropriate range, variably controls the set pressure of the relief valve 33 and lowers the pump discharge pressure of the hydraulic circuit 10, thereby reducing the hydraulic circuit pressure. Since the hydraulic horsepower of the hydraulic circuit 10 is reduced, the hydraulic circuit 10 can be prevented from being forcedly operated, and the hydraulic circuit 10 can be appropriately controlled in relation to the kinematic viscosity of the oil.
[0068]
In addition, when the controller 23 determines that the abnormal state cannot control the actual kinematic viscosity μ of the oil within an appropriate range, the abnormal state is displayed on the monitor 27 to alert the worker.
[0069]
The liquid viscosity measuring device as described above is mounted on a construction machine such as a hydraulic excavator and directly measures the kinematic viscosity of oil, so that the measurement accuracy is high. As described above, the operating conditions of the pump driving engine 11, the main pump 12, and the like can be automatically controlled, the hydraulic horsepower of the hydraulic circuit 10 can be reduced, and the cooling capacity of the cooling means 20 can be controlled. Functions can also be added.
[0070]
(1) When an abnormal contamination (garbage) is mixed, the apparent pressure is increased by increasing the differential pressure (P1-P2), so that the contamination mixing abnormality can be detected.
[0071]
Even if there is no abnormal contamination, even when the viscosity of the oil becomes high due to impurities generated due to the deterioration of the oil, it is possible to inform the operator of the time to change the oil in a timely manner. Normally, the replacement is performed for about 5000 hours.
[0072]
(2) The viscosity grade of the oil actually filled in the oil tank 15 or the like can be displayed on the monitor 27. By checking this display, the viscosity grade of the oil is not mistaken at the time of replacement.
[0073]
(3) From the kinematic viscosity of the oil converted from the measured differential pressure (P1-P2), even when the oil itself is not appropriate, such as when the wrong oil is filled, the replacement of the oil itself is monitored 27 or the like. It is possible to make recommendations. For example, when the construction machine is transported from a warm region to a cold region, it is possible to point out from the machine side that the oil is inappropriate.
[0074]
(4) The present invention is applicable not only to the hydraulic oil of the hydraulic circuit 10 but also to the lubricating oil of the pump driving engine 11.
[0075]
【The invention's effect】
According to the first aspect of the invention, the measured actual kinematic viscosity of the liquid is included in the kinetic viscosity of the liquid in an appropriate range obtained from the temperature / kinematic viscosity characteristic data representing the relationship between the liquid temperature and the kinematic viscosity. Otherwise, the actual kinematic viscosity is controlled to be within the appropriate range by variably controlling the cooling capacity of the cooling means.If the actual kinematic viscosity cannot be controlled within the appropriate range within a certain time, the hydraulic pressure is controlled. By controlling the hydraulic horsepower of the circuit to be reduced, it is possible to provide a hydraulic circuit control method capable of preventing excessive continuation of operation and appropriately controlling the hydraulic circuit in relation to the kinematic viscosity of the liquid.
[0076]
According to the second aspect of the present invention, the flow rate in the pipeline is determined by the pump discharge flow rate to the pipeline, the known average cross-sectional area of the pipeline, the measured differential pressure in the pipeline, and the proportionality constant. When the actual kinematic viscosity of the liquid is directly calculated, and this actual kinematic viscosity is not included in the appropriate range of kinematic viscosity obtained from the temperature / kinematic viscosity characteristic data indicating the relationship between the liquid temperature and the kinematic viscosity. Is controlled so that the actual kinematic viscosity is within an appropriate range by variably controlling the cooling capacity of the cooling means, and if the actual kinematic viscosity cannot be controlled within the appropriate range within a certain time, the hydraulic pressure of the hydraulic circuit is controlled. By controlling the pressure horsepower to be reduced, it is possible to prevent unreasonable continuation of operation, and to appropriately control the hydraulic circuit in relation to the kinematic viscosity of the liquid.
[0077]
According to the third aspect of the present invention, the temperature of the liquid is measured by the temperature measuring means, and the actual kinematic viscosity of the liquid is measured by the kinematic viscosity measuring means. The controller that has determined that the kinematic viscosity is not included in the appropriate range obtained from the temperature / kinematic viscosity characteristic data indicating the relationship with the actual kinematic viscosity is within the appropriate range by variably controlling the cooling capacity of the cooling means. If the actual kinematic viscosity cannot be controlled within an appropriate range within a certain period of time, by controlling the hydraulic power of the hydraulic circuit to decrease, it is possible to prevent unreasonable continuation of operation, A hydraulic circuit control device capable of appropriately controlling a hydraulic circuit in relation to kinematic viscosity can be provided.
[0078]
According to the fourth aspect of the present invention, the pump discharge flow rate to the pipeline grasped by the pump discharge flow rate grasping unit, the known average cross-sectional area of the pipeline, and the difference in the pipeline measured by the differential pressure measuring unit. From the pressure and the proportionality constant, the controller calculates the actual kinematic viscosity of the liquid flowing in the pipeline, and then calculates the actual kinematic viscosity between the temperature and the kinematic viscosity of the liquid measured by the temperature measuring means. If it is determined that the kinematic viscosity is not included in the appropriate range obtained from the temperature / kinematic viscosity characteristic data representing the relationship, the actual kinematic viscosity is included in the appropriate range by variably controlling the cooling capacity of the cooling means. If the actual kinematic viscosity cannot be controlled within an appropriate range within a certain period of time, by controlling the hydraulic horsepower of the hydraulic circuit to decrease, it is possible to prevent unreasonable continuation of operation and improve the kinematic viscosity of the liquid. Control the hydraulic circuit properly Kill.
[0079]
According to the invention, when the controller determines that the liquid is in an abnormal state where the actual kinematic viscosity of the liquid cannot be controlled within an appropriate range, the abnormal state is displayed on a monitor and attention is paid to an operator. Can be evoked.
[0080]
According to the invention described in claim 6, the controller that determines that the actual kinematic viscosity of the liquid cannot be controlled within an appropriate range reduces the hydraulic horsepower by reducing the rotation speed of the pump driving engine of the hydraulic circuit. Therefore, it is possible to prevent the hydraulic circuit from being forcedly operated.
[0081]
According to the invention described in claim 7, the controller that determines that the actual kinematic viscosity of the liquid cannot be controlled within the appropriate range reduces the hydraulic horsepower of the hydraulic circuit by reducing the pump discharge flow rate of the hydraulic circuit. Therefore, it is possible to prevent the hydraulic circuit from being forcedly operated.
[0082]
According to the invention described in claim 8, the controller that determines that the actual kinematic viscosity of the liquid cannot be controlled within an appropriate range reduces the hydraulic horsepower of the hydraulic circuit by reducing the pump discharge pressure of the hydraulic circuit. Therefore, it is possible to prevent the hydraulic circuit from being forcedly operated.
[Brief description of the drawings]
FIG. 1 is a flowchart showing one embodiment of a liquid circuit control method according to the present invention.
FIG. 2 is an explanatory diagram showing the principle of a liquid viscosity measuring device for performing the liquid circuit control method.
FIG. 3 is a circuit diagram showing one embodiment of a hydraulic circuit in which the liquid viscosity measuring device is incorporated.
FIG. 4 is a temperature / kinematic viscosity characteristic diagram showing the relationship between the temperature and the kinematic viscosity of various oils to be compared by the liquid viscosity measuring device.
FIG. 5 is a flowchart showing an embodiment of a liquid viscosity control method using the liquid viscosity measuring device.
[Explanation of symbols]
Reference Signs List 10 Hydraulic circuit as hydraulic circuit 11 Pump driving engine 20 Cooling means 21 Pilot pump 23 as pump Pump 27 Controller 29 Oil temperature sensor 36 as temperature measuring means 36 Pipe lines 37, 38 Pressure sensor 41 as differential pressure measuring means Pump discharge flow rate grasping means 42 Kinematic viscosity measuring means

Claims

Measure the temperature and actual kinematic viscosity of the liquid,
From the temperature / kinematic viscosity characteristic data representing the relationship between the temperature and the kinematic viscosity of the liquid, determine the kinematic viscosity of the liquid at an appropriate range at the measured temperature,
Determine whether the actual kinematic viscosity of the liquid is included in the appropriate range of kinematic viscosity,
If the actual kinematic viscosity is not included in the appropriate range of kinematic viscosity, by controlling the cooling capacity of the cooling means for cooling the liquid to variably control the actual kinematic viscosity to be included in the appropriate range,
If the actual kinematic viscosity is controlled within the appropriate range within a certain time, the operation of the hydraulic circuit operated by the liquid whose kinematic viscosity has been calculated is continued, and the actual kinematic viscosity is within the appropriate range within a certain time. A hydraulic circuit control method characterized by controlling the hydraulic horsepower of the hydraulic circuit to be reduced when the hydraulic circuit is not controlled.

When measuring the actual kinematic viscosity,
Ascertain the pump discharge flow rate Q when discharging liquid from the pump to the pipeline,
Measuring a pressure difference (P1-P2) between a pressure P1 at a first measurement point in the pipeline and a pressure P2 at a second measurement point located downstream of the first measurement point;
The pump discharge flow rate Q, the average cross-sectional area A of the pipeline between the first measurement point and the second measurement point, the differential pressure (P1−P2), and the proportionality constant k are represented by Q = k · μ · A · √ (P1−P2). 2. The hydraulic circuit control method according to claim 1, wherein the actual kinematic viscosity .mu.

Temperature measuring means for measuring the temperature of the liquid,
Kinematic viscosity measuring means for measuring the actual kinematic viscosity of the liquid,
Cooling means capable of controlling the cooling capacity for cooling the liquid,
A hydraulic circuit activated by a liquid whose temperature and kinematic viscosity have been measured,
From the temperature and kinematic viscosity characteristic data representing the relationship between the temperature and the kinematic viscosity of the liquid, determine the kinematic viscosity of the liquid at an appropriate range at the measured temperature. If the actual kinematic viscosity is not included in the appropriate range of kinematic viscosity, control is performed so that the actual kinematic viscosity is included in the appropriate range by variably controlling the cooling capacity of the cooling means, and the control is performed for a certain period of time. If the actual kinematic viscosity is controlled within the appropriate range, the operation of the hydraulic circuit operated by the liquid whose kinematic viscosity is measured is continued, and the actual kinematic viscosity is controlled within the appropriate range within a certain period of time. A controller for controlling the hydraulic horsepower of the hydraulic circuit to decrease the hydraulic horsepower when not performed.

Kinematic viscosity measurement means,
Pump discharge flow rate grasping means for grasping a pump discharge flow rate Q when discharging a liquid from a pump to a pipeline;
A differential pressure measuring means for measuring a differential pressure (P1-P2) between a pressure P1 at a first measurement point in the pipeline and a pressure P2 at a second measurement point located downstream of the first measurement point. Equipped,
The controller calculates the pump discharge flow rate Q, the average pipe cross-sectional area A between the first measurement point and the second measurement point, the differential pressure (P1−P2), and the proportionality constant k as follows: Q = k · μ · A · √ (P1 The hydraulic circuit control device according to claim 3, wherein the actual kinematic viscosity μ of the liquid is calculated by substituting into -P2).

5. A monitor for displaying an abnormal state based on a signal output from a controller that has determined that an abnormal state in which the actual kinematic viscosity is not included in the kinematic viscosity within an appropriate range has continued for a certain period of time. The hydraulic circuit control device as described in the above.

The controller is
6. The method according to claim 3, wherein when the actual kinematic viscosity is not controlled within an appropriate range within a predetermined time, the rotational speed of the pump driving engine of the hydraulic circuit is controlled to be reduced. Hydraulic circuit controller.

The controller is
7. The hydraulic circuit according to claim 3, wherein when the actual kinematic viscosity is not controlled within an appropriate range within a predetermined time, control is performed so as to reduce the pump discharge flow rate of the hydraulic circuit. Control device.

The controller is
The hydraulic circuit according to any one of claims 3 to 7, wherein when the actual kinematic viscosity is not controlled within an appropriate range within a predetermined time, control is performed to reduce the pump discharge pressure of the hydraulic circuit. Control device.