JP3652510B2

JP3652510B2 - Hydraulic control device for machine having upper swing body

Info

Publication number: JP3652510B2
Application number: JP16755398A
Authority: JP
Inventors: 哲松本
Original assignee: Toshiba Machine Co Ltd
Current assignee: Shibaura Machine Co Ltd
Priority date: 1998-06-15
Filing date: 1998-06-15
Publication date: 2005-05-25
Anticipated expiration: 2018-06-15
Also published as: JP2000002203A

Description

【０００１】
【発明の属する技術分野】
本発明は、建設機械等における上部旋回体を有する機械の油圧制御装置に係り、特に複数のアクチュエータを同時操作する場合の複合操作性を向上させた油圧制御装置に関するものである。
【０００２】
【従来の技術】
従来、油圧ショベルの複数のアクチュエータに対して油圧ポンプの吐出圧油を供給する圧油供給装置として、例えば油圧ポンプの吐出路に、複数の方向制御弁をパラレルに設けて、複数のアクチュエータに圧油を供給し、各方向制御弁を中立時にポンプポートを遮断するクローズドセンタ形とし、各方向制御弁の入口側に圧力補償弁を設け、各アクチュエータの負荷圧における最も高い負荷圧を圧力補償弁に作用させると共に、その最も高い負荷圧とポンプ圧との差圧が設定値となるように油圧ポンプの容量を制御して、複数のアクチュエータに負荷の大小によらず同時に油圧ポンプの吐出圧油を方向制御弁の開口面積に応じた流量配分で供給するようにしたクローズドセンタ形ロードセンシングシステムとしての圧油供給装置が知られている。
【０００３】
しかしながら、前記構成からなる圧油供給装置は、旋回用油圧モータにより上部車体を旋回する動作とブーム用シリンダ、バケット用シリンダにより、作業機を作動する動作を同時に行うと次のような問題がある。
【０００４】
すなわち、旋回用油圧モータに圧油を供給して、上部車体を定常旋回動作中に例えばブーム用シリンダに圧油を供給して作業機を作動すると、油圧ポンプの容量はそのブーム用シリンダの流量に見合うように瞬時に増大する。一方、旋回用の方向制御弁に設けた圧力補償弁は、ブーム用シリンダの負荷圧が旋回用油圧モータの負荷圧よりも高いので、ブーム用シリンダの負荷圧によって開口面積の小さい方向に作動して被補償位置となり、油圧ポンプの容量が増大しても旋回用油圧モータに供給される流量を一定にしようとするが、その圧力補償弁が前述した被補償位置となるまでに若干の時間遅れがあり、その間に旋回用油圧モータに流量が余分に流れ、旋回速度が一瞬増速する。このため、上部車体を円滑に旋回させることができず、オペレータの乗り心地を悪化させる難点がある。
【０００５】
このような難点を解消するため、旋回用油圧モータに圧油を供給する油圧ポンプを別に設けて、旋回用回路と作業用回路とを独立させた圧油供給装置が提案されている。しかし、この場合、旋回起動時には旋回用油圧モータの負荷トルクが大きく、旋回用油圧ポンプのポンプ吐出圧はリリーフ弁のセット圧まで上昇し、その吐出流量の殆どがリリーフ弁からタンクに流出してしまうので、無駄となる。
【０００６】
そこで、前述した難点を解決する手段として、例えば図５に示す構成からなる圧油供給装置が提案されている（特開平１０−３７９０７号公報）。
【０００７】
すなわち、前記提案に係る圧油供給装置は、図５において、可変容量形の第１油圧ポンプ１と、複数のクローズトセンタ形式の方向制御弁３（ 3-1〜3-5 ）と、複数の圧力補償弁２１を備え、前記第１油圧ポンプ１の容量を最も高い負荷圧に見合う値に制御すると共に、各圧力補償弁２１に最も高い負荷圧を作用させて、第１油圧ポンプ１の吐出圧油を複数のアクチュエータに方向制御弁３の開口面積に応じた流量配分で供給する第１の油圧回路と、第２油圧ポンプ３０の吐出圧油をオープンセンタ形式の特定（旋回用）の方向制御弁３３で特定のアクチュエータ（旋回用油圧モータ４０）に供給する第２の油圧回路と、前記第２油圧ポンプ３０の吐出路３２を第１油圧ポンプ１の吐出路２に接続する連通路４１と、前記連通路４１に設けたチェック弁４２と切換弁４３とを備え、前記チェック弁４２を第１油圧ポンプ１の吐出路２から第２油圧ポンプ３０の吐出路３２に圧油が流れないものとし、前記切換弁４３を遮断位置と連通位置に切換え可能に構成したものである。なお、参照符号３１はパイロット用油圧ポンプを示すものである。
【０００８】
従って、このように構成される圧油供給装置によれば、第１油圧ポンプ１の吐出圧油を、複数のアクチュエータ（左走行油圧モータ４、バケットシリンダ５、右走行油圧モータ６、ブームシリンダ７、アームシリンダ８）に対し方向制御弁３（ 3-1〜3-5 ）の開口面積に応じた流量配分で供給することができるので、１つの油圧ポンプで複数のアクチュエータを同時に作動させることができる。そして、第１油圧ポンプ１を備えた第１の油圧回路と第２油圧ポンプ３０を備えた第２の油圧回路が独立しているから、方向制御弁３と特定の方向制御弁３３を同時操作して前記アクチュエータと特定のアクチュエータ（旋回用油圧モータ４０）を同時に作動させる時に、特定のアクチュエータが増速することはない等の利点が得られる。
【０００９】
【発明が解決しようとする課題】
しかしながら、前記提案に係る従来の圧油供給装置においては、改善されるべき種々の問題が残されている。
【００１０】
すなわち、前記従来技術においては、適用例を油圧ショベルとし、第１油圧ポンプ１としての可変容量ポンプには旋回を除くアクチュエータを操作するための方向制御弁３（ 3-1〜3-5 ）をパラレルに接続し、旋回用方向制御弁３３へは第２油圧ポンプ３０からの圧油を単独で供給すると共に、ブームおよび旋回を同時操作した場合には、第２油圧ポンプ３０の圧油供給ライン３２を逆止弁４２および切換弁４３を介して第１油圧ポンプ１の圧油供給ライン２に接続している。従って、このような構成によれば、前記同時操作の場合には、旋回用油圧モータ４０の駆動圧力は、ブーム駆動圧までしか上がらず、しかも旋回の余剰油はブームシリンダ７へ供給されるので、ブームシリンダ７が増速される。
【００１１】
しかし、前記従来技術においては、旋回単独または旋回とブームとが同時操作された場合のみ第２油圧ポンプ３０は活用されており、例えばアームシリンダ８、バケットシリンダ５等が操作された場合には、前記第２油圧ポンプ３０の吐出油は何等有効に活用されておらず、単にタンクラインへ排出されているに過ぎない。従って、省エネルギー上の問題がある。
【００１２】
また、旋回とアーム等を同時操作する場合を考慮すると、２個のポンプを駆動する原動機においては、当然ながら２個のポンプの和のエネルギーが必要となり、しかも旋回速度を従来のシステムと同等のレベルを維持する場合には、第２油圧ポンプの容量を小さくすることはできない。従って、第１油圧ポンプからのみ圧油の供給を受けるアーム単独操作の場合には、必要十分なアーム速度を得ることができない難点がある。
【００１３】
そこで、本発明者は、鋭意研究ならび検討を重ねた結果、少なくとも旋回モータとブームシリンダとを含む複数のアクチュエータで駆動する上部旋回体を有する機械からなり、前記各アクチュエータに対し第１の可変容量ポンプと第２の可変容量ポンプからの圧油を各アクチュエータが接続された各切換弁を介して供給し、各アクチュエータからの戻り油を前記切換弁を介してタンクラインに排出するよう構成し、これら複数の切換弁を、第１の可変容量ポンプからの圧油の供給を受けるＡ群の切換弁と、第２の可変容量ポンプからの圧油の供給を受けるＢ群の切換弁とに分け、各アクチュエータに対して前記第１および第２の可変容量ポンプのいずれか一方または両方から圧油を供給するよう構成した上部旋回体を有する機械の油圧制御装置において、第１の可変容量ポンプの供給ラインにＡ群の切換弁をパラレルに接続すると共に、第２の可変容量ポンプの供給ラインにＢ群の切換弁をパラレルに接続する構成とし、また各切換弁は、前記各可変容量ポンプの圧油供給通路からの圧油をアクチュエータへ供給するに際して、前記圧油供給通路から、切換スプールの移動により開度の調整される開口部、中間室を経て、シリンダポートへ供給するよう構成すると共に、前記中間室とシリンダポートとの間の油路上またはシリンダポートとタンクラインとの間の油路上に、この油路の開度を調整する流量調整手段を設けて、その開度を前記各切換弁の中間室の圧力により前記油路を開方向に調整するように構成し、また各切換弁には、中間室の圧力を検出する検出手段を設け、Ａ群の切換弁およびＢ群の切換弁においてそれぞれ検出された圧力の中の最高圧力ＰA およびＰB を選択し、Ａ群およびＢ群の切換弁内の各流量調整手段に対してその開度を閉方向に調整するよう作用させると共に、前記圧力ＰA およびＰB の各通路を圧力ＰA からＰB へ圧油が流れるのを阻止する向きに逆止弁を設けて連通接続し、さらに第１の可変容量ポンプの圧力供給通路から２つの分岐ラインＬA1およびＬA2を分岐し、一方の分岐ラインＬA1は、一方の流量調整手段ＦA1を介してタンクラインに接続して、前記流量調整手段ＦA1の開度を前記圧力ＰA とばね力とにより閉方向に調整すると共に第１の可変容量ポンプの吐出圧力により開方向に調整し、他方の分岐ラインＬA2は、他の流量調整手段ＦANと逆止弁とを介して前記第２の可変容量ポンプの圧力供給通路に接続した構成とし、また第２の可変容量ポンプの圧油供給通路から分岐ラインＬB1を分岐し、この分岐ラインＬB1は、流量調整手段ＦB1を介してタンクラインに接続して、前記流量調整手段ＦB1の開度を前記第２の可変容量ポンプの吐出圧力により開方向に調整すると共に前記圧力ＰB とばね力とにより閉方向に調整するように構成することにより、複数のアクチュエータを同時操作する場合に、各アクチュエータの負荷圧が大きく異なっていても、第１および第２の可変容量ポンプの吐出油をきわめて有効に活用し、各アクチュエータの速度維持、各可変容量ポンプの吐出流量の有効活用を図ることができることを突き止めた。
【００１４】
従って、本発明の目的は、２基の可変容量ポンプを使用して建設機械等を駆動するに際し、旋回と他のアクチュエータとを同時操作した場合の複合操作性を向上させると共に、２基の可変容量ポンプの吐出油を有効に活用することができる上部旋回体を有する機械の油圧制御装置を提供することにある。
【００１５】
【課題を解決するための手段】
前記目的を達成するため、本発明に係る上部旋回体を有する機械の油圧制御装置は、少なくとも旋回モータとブームシリンダとを含む複数のアクチュエータで駆動する上部旋回体を有する機械からなり、前記各アクチュエータに対し第１の可変容量ポンプと第２の可変容量ポンプからの圧油を各アクチュエータが接続された各切換弁を介して供給し、各アクチュエータからの戻り油を前記切換弁を介してタンクラインに排出するよう構成し、これら複数の切換弁を、第１の可変容量ポンプからの圧油の供給を受けるＡ群の切換弁と、第２の可変容量ポンプからの圧油の供給を受けるＢ群の切換弁とに分け、各アクチュエータに対して前記第１および第２の可変容量ポンプのいずれか一方または両方から圧油を供給するよう構成した上部旋回体を有する機械の油圧制御装置において、
第１の可変容量ポンプの供給ラインにＡ群の切換弁をパラレルに接続すると共に、第２の可変容量ポンプの供給ラインにＢ群の切換弁をパラレルに接続し、
各切換弁は、前記各可変容量ポンプの圧油供給通路からの圧油をアクチュエータへ供給するに際し、前記圧油供給通路から、切換スプールの移動により開度の調整される開口部、中間室を経て、シリンダポートへ供給するよう構成すると共に、前記中間室とシリンダポートとの間の油路上またはシリンダポートとタンクラインとの間の油路上に、この油路の開度を調整する流量調整手段を設けて、その開度を前記各切換弁の中間室の圧力により前記油路を開方向に調整し、
各切換弁には、中間室の圧力を検出する検出手段を設け、Ａ群の切換弁およびＢ群の切換弁においてそれぞれ検出された圧力の中の最高圧力ＰA およびＰB を選択し、Ａ群およびＢ群の切換弁内の各流量調整手段に対してその開度を閉方向に調整するよう作用させると共に、前記圧力ＰA およびＰB の各通路を圧力ＰAからＰB へ圧油が流れるのを阻止する向きに逆止弁を設けて連通接続し、
第１の可変容量ポンプの圧力供給通路から２つの分岐ラインＬA1およびＬA2を分岐し、一方の分岐ラインＬA1は、一方の流量調整手段ＦA1を介してタンクラインに接続して、前記流量調整手段ＦA1の開度を前記圧力ＰA とばね力とにより閉方向に調整すると共に第１の可変容量ポンプの吐出圧力により開方向に調整し、他方の分岐ラインＬA2は、他の流量調整手段ＦANと逆止弁とを介して前記第２の可変容量ポンプの圧力供給通路に接続し、
第２の可変容量ポンプの圧油供給通路から分岐ラインＬB1を分岐し、この分岐ラインＬB1は、流量調整手段ＦB1を介してタンクラインに接続して、前記流量調整手段ＦB1の開度を前記第２の可変容量ポンプの吐出圧力により開方向に調整すると共に前記圧力ＰB とばね力とにより閉方向に調整するように構成することを特徴とする。
【００１６】
この場合、前記分岐ラインＬA2上の他の流量調整手段ＦANは、外部信号によって開度を調整し得る開閉弁として構成することができる。
【００１７】
また、前記分岐ラインＬA2上の他の流量調整手段ＦANは、外部信号によって開度を調整し得る開閉弁と流量調整手段ＦA2とから構成し、前記流量調整手段ＦA2の開度はこの流量調整手段ＦA2と前記開閉弁との間の油路の圧力により開方向に調整すると共に、Ａ群の切換弁にのみ含まれる切換弁の中間室の選択された最高圧力により閉方向に調整するように構成することができる。
【００１８】
さらに、Ａ群の切換弁には少なくとも旋回用切換弁を備えると共に、Ｂ群の切換弁には少なくともブーム用切換弁を備えた構成とすることができる。
【００１９】
一方、前記上部旋回体を有する機械は２個の走行モータにより走行駆動される機械からなり、Ａ群の切換弁には旋回用切換弁を備えると共に、Ｂ群の切換弁には少なくともブーム用切換弁と前記２個の走行駆動用切換弁を備えた構成とすることができる。
【００２０】
また、前記上部旋回体を有する機械は１個の走行モータにより走行駆動される機械からなり、Ａ群の切換弁には旋回用切換弁と走行駆動用切換弁とを備えると共に、Ｂ群の切換弁には少なくともブーム用切換弁を備えた構成とすることができる。
【００２２】
そして、前記上部旋回体を有する機械は、少なくとも旋回モータと、１個の走行モータと、ブームシリンダと、アームシリンダと、バケットシリンダとから駆動される機械からなり、Ａ群の切換弁には少なくとも旋回用切換弁と走行駆動用切換弁とを備えると共に、Ｂ群の切換弁には少なくともブームシリンダ、アームシリンダおよびバケットシリンダ用の切換弁を備えた構成とすることができる。
【００２３】
本発明において、前記分岐ラインＬA2上に設けた開閉弁は、中立位置では開放位置に維持され、Ａ群の切換弁に含まれる切換弁の操作信号により閉方向に開度を調整するように構成することができる。
【００２４】
この場合、前記分岐ラインＬA2上の開閉弁を操作する信号は旋回用切換弁の操作信号とすることができる。
【００２５】
また、前記分岐ラインＬA2上に設けた開閉弁は、中立位置では開放位置に維持され、旋回用切換弁の操作信号により閉方向に開度を調整すると共に、ブーム用切換弁のブーム上げ操作信号により開方向に開度を調整するように構成することができる。
【００２６】
さらに、前記各切換弁をクローズドセンタ形切換弁とし、流量調整手段ＦA1、ＦB1の下流側に圧力発生手段ＦTA、ＦTBを設け、これら圧力発生手段の上流側圧力に応じて第１の可変容量ポンプおよび第２の可変容量ポンプの吐出流量をそれぞれ調整するように構成することができる。
【００２７】
これに対し、前記各切換弁をオープンセンタ形切換弁とし、流量調整手段ＦA1、ＦB1の下流側に圧力発生手段ＦTA、ＦTBを設け、Ａ群の切換弁およびＢ群の切換弁を通してセンタバイパス通路を設け、このセンタバイパス通路の出口を前記圧力発生手段ＦTA、ＦTBの上流側に逆止弁を介してそれぞれ接続し、前記圧力発生手段ＦTA、ＦTBの上流側圧力に応じて第１の可変容量ポンプおよび第２の可変容量ポンプの吐出流量をそれぞれ調整するように構成することができる。
【００２８】
代案として、前記切換弁をオープンセンタ形切換弁とし、流量調整手段ＦA1、ＦB1の下流側に圧力発生手段ＦTA、ＦTBを設け、Ａ群の切換弁およびＢ群の切換弁を通してセンタバイパス通路を設け、このセンタバイパス通路の出口を前記圧力発生手段ＦTAの上流側に接続し、前記圧力発生手段ＦTA、ＦTBの上流側圧力に応じて第１の可変容量ポンプおよび第２の可変容量ポンプの吐出流量をそれぞれ調整するように構成することもできる。
【００２９】
前記油圧制御装置の構成において、前記Ｂ群の切換弁を構成する切換弁の最端面に圧油供給通路、センタバイパス通路、タンクライン、圧力ＰB の通路を開口させ、前記切換弁の端面をカバー部材で閉塞し、前記カバー部材にはポンプ供給ラインとセンタバイパス通路とを接続する通路を設けた構成とすることができる。
【００３０】
そして、前記Ｂ群の切換弁を構成する切換弁の最端面とカバー部材との間に追加切換弁を設け、この追加切換弁にはＢ群の切換弁と共通した圧油供給通路と、センタバイパス通路と、タンクラインと、圧力ＰB の通路に連通した信号ラインとをそれぞれ備えた構成とすることができる。
【００３１】
【発明の実施の形態】
次に、本発明に係る上部旋回体を有する機械の油圧制御装置の実施例につき、添付図面を参照しながら以下詳細に説明する。
【００３２】
図１は、本発明に係る油圧制御装置の一実施例を示す油圧回路図である。すなわち、図１（ａ）、（ｂ）、（ｃ）において、参照符号Ｐ1は第１の可変容量ポンプを示すと共に、Ｐ2は第２の可変容量ポンプをそれぞれ示す。これら第１の可変容量ポンプＰ1および第２の可変容量ポンプＰ2の吐出油は、それぞれ圧油供給通路１０１および２０１を介してＡ群の切換弁（旋回用切換弁ＳＷ）およびＢ群の切換弁（左走行用切換弁ＴＬ、右走行用切換弁ＴＲ、バケット用切換弁ＢＫＴ、ブーム用切換弁ＢＭ、アーム用切換弁ＡＲＭ）へそれぞれ供給されるように構成されている。
【００３３】
前記Ａ群の切換弁としての旋回用切換弁ＳＷに関連して、流量調整手段１０４が設けられており、この流量調整手段１０４は、中間室１１２とシリンダポート１１５、１１６との間に設けられ、前記流量調整手段１０４の開度は、前記中間室１１２の圧力とばね１１３のばね力とにより開方向に調整され、通路１１７の圧力ＰA により閉方向に調整されている。
【００３４】
また、第１の可変容量ポンプＰ1 の圧油供給通路１０１からは、分岐ラインＬA1、ＬA2が分岐しており、一方の分岐ラインＬA1上には流量調整手段ＦA1と圧力発生手段ＦTAが設けられ、前記Ｂ群の切換弁およびＡ群の切換弁を通過して流出するセンタバイパス通路２０３の出口通路２０４を経て流出した油の一部を分岐するよう構成し、さらに前記出口通路２０４は逆止弁１０３を介して分岐ラインＬA1上の前記流量調整手段ＦA1の下流側であって、前記圧力発生手段ＦTAの上流側に連通接続されている。また、前記出口通路２０４が連通接続される位置と同じ位置から、信号ライン１０６が導出され、第１の可変容量ポンプＰ1 の吐出流量調整機構１０７に伝達されるように構成されている。
【００３５】
なお、図１における実施例においては、第１の可変容量ポンプＰ1 および第２の可変容量ポンプＰ2 の吐出流量制御方式は、共にネガティブ流量制御方式の場合を示している。
【００３６】
また、他方の分岐ラインＬA2には、開閉弁１０２と流量調整手段ＦA2とによって構成される他の流量調整手段ＦANを設け、逆止弁１０８を介して第２の可変容量ポンプＰ2 の圧油供給ライン２０２が接続されている。前記開閉弁１０２の開度は、本実施例においては、旋回用切換弁ＳＷの操作信号により閉方向に調整し、前記Ｂ群の切換弁に含まれるブーム用切換弁ＢＭのブーム上げ操作信号により、開方向に調整ないし維持するように構成されている。なお、この開閉弁１０２は、フルストロークの位置においても所定の開度を維持するように構成されている。一方、前記流量調整手段ＦA2の開度は、旋回用切換弁ＳＷの中間室１１２の圧力により閉方向に調整され、この流量調整手段ＦA2の上流側圧力によって開方向に調整するように構成されている。
【００３７】
さらに、前記Ｂ群の切換弁において、各切換弁は第２の可変容量ポンプＰ2 の圧油供給ライン２０２にパラレルに接続配置されており、各切換弁はタンクライン２１８との間の油路中に流量調整手段（例えば左走行用切換弁ＴＬにおいては流量調整手段２１４）が、それぞれの切換弁に対応して設けられている。また、各切換弁の中間室の圧力（例えば左走行用切換弁ＴＬにおいては中間室２１２の圧力）が、それぞれ検出され、通路２１７にそれぞれ導かれている。
【００３８】
なお、図１における実施例においては、各中間室（２１２）の圧力は、各流量調整手段（２１４）に設けた逆止弁（２１３）により高圧選択され、この結果Ｂ群の切換弁に含まれる切換弁の中間室の圧力のうち最高圧力ＰB が通路２１７において検出される。
【００３９】
また、第２の可変容量ポンプＰ2 の圧油供給通路２０１からは、分岐ラインＬB1が分岐され、分岐ラインＬB1上には流量調整手段ＦB1と圧力発生手段ＦTBが設けられ、その下流側がタンクＴに連通するタンクライン１１８に接続されている。そして、前記分岐ラインＬB1上において、流量調整手段ＦB1と圧力発生手段ＦTBとの間には、逆止弁２０５を介してセンタバイパス通路２０３の出口通路２０４が分岐されて連通接続されている。さらに、前記出口通路２０４が連通接続される位置と同じ位置から、信号ライン２０７が導出され、第２の可変容量ポンプＰ2 の吐出流量調整機構２０８に伝達されるように構成されている。
【００４０】
なお、代案として、図１に示す実施例においては、センタバイパス通路２０３の出口通路２０４を、それぞれ圧力発生手段ＦTA、ＦTBの上流側に逆止弁１０３、２０５を介して接続しているが、図４に示すように、センタバイパス通路２０３の出口通路２０４を、一方の圧力発生手段ＦTAの上流側のみに接続して、前記逆止弁１０３、２０５を省略した構成とすることもできる。
【００４１】
図１に示す実施例においては、Ａ群の切換弁およびＢ群の切換弁にそれぞれ含まれる各切換弁の中間室の圧力のうち、最高圧力が通路１１７、２１７で検出されているが、これらの通路は通路２１７から通路１１７への流れのみを許容する向きに設けた逆止弁２１１を介して接続されている。そして、各通路１１７、２１７は、各切換弁が中立位置にある場合に確実に低圧となるようにするため、絞り１１０、２１０を介してドレンラインＤr に連通接続するよう構成されている。
【００４２】
切換弁の構造（その１）
図２は、前述した油圧制御装置に適用し得る各切換弁の一実施例としての構造を示すものである。すなわち、図２において参照符号１３０はバルブボディを示し、このバルブボディ１３０は、可変容量ポンプＰからの圧油の供給を受ける共通の圧油供給通路１３２と、切換スプール１３４と、この切換スプール１３４の移動により圧油供給通路１３２からの圧油の供給を受ける中間室１３６と、シリンダポート１３８ａ、１３８ｂへの通路１４０、１４０と、逆止弁１４２と、前記切換スプール１３４の移動によりシリンダポート１３８ａまたは１３８ｂの圧油をタンクＴへ排出する補助ポート１４４、１４４およびタンクライン１４７をそれぞれ内蔵した構成からなる。
【００４３】
なお、前記切換スプール１３４には、この切換スプール１３４の移動に伴い圧油供給通路１３２を中間室１３６と接続するための切欠部１３３が設けられている。また、前記切換スプール１３４には、この切換スプール１３４の移動に伴いシリンダポート１３８ａまたは１３８ｂを通路１４０または補助ポート１４４に連通接続するための切欠部１４５、１４５′および１４６、１４６′が設けられている。
【００４４】
前記補助ポート１４４、１４４は、シリンダポート１３８ａ、１３８ｂとタンクライン１４７との間に設けられ、また補助ポート１４４、１４４とタンクライン１４７との間には、シリンダポート１３８ａ、１３８ｂからタンクライン１４７への通路の開度Ａを調整するための流量調整手段１４８が設けられている。
【００４５】
しかるに、前記流量調整手段１４８は、スプール１５０とばね１５２とを備え、前記スプール１５０は、バルブボディ１３０に形成されたスプール穴１５３、１５４、１５５にそれぞれ摺動自在かつ液密的に保持すると共に、その一端をカバー１５６により囲繞保持する。そして、スプール１５０に設けた内部通路１５８の一端は逆止弁１６０および通路１６１を介して前記カバー１５６内に形成した背室１６２に連通接続すると共に、その他端は前室１６４に開口する。この場合、前記逆止弁１６０は、背室１６２から前室１６４への圧油の流れを阻止するように組み込まれている。
【００４６】
一方、前記前室１６４は、前記中間室１３６と通路１６５を介して連通接続され、前記前室１６４内に前記ばね１５２を収納配置して、前記スプール１５０の他端を弾力的に保持している。
【００４７】
このようにして、前記流量調整手段１４８は、前記スプール１５０がばね１５１の弾力に抗して下方へ移動するに従い、スプール１５０の肩部１５０ａがスプール穴１５４に係合しつつ、その開度Ａは切欠部１５０ｂによって規制されて次第に小さくなるように構成される。
【００４８】
なお、本実施例の図２に示す構成図においては、切換スプールに対しセンタバイパス通路１６６を設けて、オープンセンタ型の油圧制御装置として構成したものであるが、クローズドセンタ型の油圧制御装置として構成することもできることは勿論である。
【００４９】
また、本実施例においては、図２に示す構成からなる切換弁を複数含むものであって、図２に示す切換弁の背室１６２は、図示していない他の切換弁の流量調整手段における各背室（例えば１６２ａ、１６２ｂ、１６２ｃ）と連通路１６８を介して接続し、この連通路１６８を適宜絞り１７０を介してタンクＴへ連通接続する。
【００５０】
切換弁の構造（その２）
図３は、前述した油圧制御装置に適用し得る各切換弁の別の実施例としての構造を示すものである。すなわち、図３において参照符号２３０はバルブボディを示し、このバルブボディ２３０は、可変容量ポンプＰからの圧油の供給を受ける共通の圧油供給通路２３２と、切換スプール２３４と、この切換スプール２３４の移動により圧油供給通路２３２からの圧油の供給を受ける油室２３６と、シリンダポート２３８ａ、２３８ｂと、前記油室２３６からシリンダポート２３８ａまたは２３８ｂへの通路２４０、２４０の途中に設けられた流量調整手段２４２と、逆止弁２４４、２４４と、前記切換スプール２３４の移動によりシリンダポート２３８ａ、２３８ｂの圧油をタンクＴへ排出するタンクポート２４６とをそれぞれ内蔵した構成からなる。なお、本実施例の切換弁の構造においては、切換スプール２３４の一部に、可変容量ポンプＰからの圧油の供給を受ける圧油供給通路２３２に対して分岐される圧油を供給する、センタバイパス通路２８０が設けられている。
【００５１】
しかるに、前記流量調整手段２４２は、スプール２４８とばね２４９とを備え、その中立位置において、ばね２４９はスプール２４８に対して油室２３６からシリンダポート２３８ａ、２３８ｂへ連通する通路２３９を開放する側にこれを保持している。このスプール２４８は、カバー２５０により囲繞すると共に、その一端を前記カバー２５０に当接させて、スプール２４８をバルブボディ２３０に設けたスプール穴２５２内に摺動自在かつ液密的に保持する。
【００５２】
一方、バルブボディ２３０には、前記通路２３９に連通する通路２４０、２４０が設けられると共に、これら通路２４０、２４０の途中には逆止弁２４４、２４４が設けられ、そして前記通路２３９の油室２３６側には前室２５４が形成されている。また、前記スプール２４８の一端を保持するカバー２５０内には、背室２５６が形成され、この背室２５６に前記ばね２４９が収納配置されている。
【００５３】
さらに、前記通路２４０と背室２５６との間のスプール穴２５２の中間部には、中間室２５８が設けられ、この中間室２５８に対しては、スプール２４８が中立位置にある時、前記スプール２４８に設けられた通路２６０、２６１が開口するように構成配置されている。しかるに、前記スプール２４８は、前記通路２６０がスプール内通路２６２を介して背室２５６と連通接続されている。なお、前記通路２６１は、比較的小径とし、絞り効果を持たせてある。
【００５４】
そして、前記中間室２５８は、本実施例の図３に示す構成と同一の他の切換スプールの各中間室（例えば２５９ａ、２５９ｂ、２５９ｃ）と連通路２６４を介して接続し、この連通路２６４を適宜絞り２６６を介してタンクＴへ連通接続する。
【００５５】
次に、前述した実施例における上部旋回体を有する機械の油圧制御装置の動作につき説明する。
【００５６】
（１）各切換弁が中立位置にある場合
図１に示す実施例において、全ての切換弁が中立位置にある場合は、各切換弁の中間室２１２は圧油供給通路２０２から遮断されており、従って通路１１７、２１７は共に低圧に維持されている。そして、第１の可変容量ポンプＰ1の吐出油は、分岐ラインＬA1上の流量調整手段ＦA1を（ばね力と低圧ＰAに対抗して）開口させ、通路１０５へ流出する。前記吐出油は、分岐ラインＬA2を経て第２の可変容量ポンプＰ2の圧油供給ライン２０２へ導出され、さらにセンタバイパス通路２０３および出口通路２０４を経て、逆止弁１０３、２０５を介し通路１０５、２０６へ流出する。
【００５７】
また、第２の可変容量ポンプＰ2 においても、同様にして、その吐出油は、圧油供給通路２０１、分岐ラインＬB1を流過し、流量調整手段ＦB1、圧力発生手段ＦTBを経て、タンクライン１１８に至ると共に、圧油供給ライン２０２、センタバイパス通路２０３および出口通路２０４を経て、逆止弁１０３、２０５を介し通路１０５、２０６へ流出する。
【００５８】
従って、図１に示す実施例においては、第１の可変容量ポンプＰ1 および第２の可変容量ポンプＰ2 は、ネガティブ流量制御方式であるため、この制御方式の特性上、前記第１の可変容量ポンプＰ1 および第２の可変容量ポンプＰ2 の吐出流量は、最小値に維持されている。
【００５９】
（２）Ａ群の切換弁を操作した場合
図１に示す実施例においては、Ａ群の切換弁として旋回用切換弁ＳＷを示しているが、この切換弁を図示において上方に操作すると、センタバイパス通路２０３の出口通路２０４への排出油量は、切換弁の操作量に応じて減少し、そしてフルストローク位置ではセンタバイパス通路２０３が閉じられる。これと同時に、この切換弁の中間室１１２の圧力は、逆止弁１１１を介して通路１１７により検出され、これが流量調整手段ＦA1の閉方向にばね力と共に作用するので、前記切換弁ＳＷの絞り１２９における圧力降下を、ばね力による圧力より若干小さく設定することにより、流量調整手段ＦA1は閉じられ、従って通路１０５へ排出される油は無くなることによって、第１の可変容量ポンプＰ1 の吐出油は最大となり、この全量が図示していない旋回モータへ供給される。
【００６０】
この状態では、通路１１７の圧油は、逆止弁２１１によりＢ群の切換弁への流れを阻止されているので、通路２１７は低圧に維持されており、しかも圧油供給ライン２０２の圧力は、逆止弁２１５により第２の可変容量ポンプＰ2 には作用しないので、この第２の可変容量ポンプＰ2 の吐出油は、流量調整手段ＦB1から低圧で通路２０６へ排出され、この排出油が圧力発生手段ＦTBに作用して通路２０６に所定の圧力が発生し、第２の可変容量ポンプＰ2 の吐出油を最少に維持している。
【００６１】
従って、Ａ群に含まれる旋回用切換弁ＳＷを操作した場合には、第１の可変容量ポンプＰ1のみが作動状態となり、第２の可変容量ポンプＰ2は低圧で最少の吐出状態を維持しているので、エネルギー損失を最少とすることができる。
【００６２】
（３）Ｂ群の切換弁を操作した場合
Ｂ群の切換弁を操作した場合は、操作した切換弁の中間室の圧力が、通路２１７で検出される。この検出された圧力は、信号ライン２１６を経て流量調整手段ＦB1に至ると同時に、逆止弁２１１を介して通路１１７へ導出され、さらに信号ライン１１９を経て流量調整手段ＦA1に至り、前記操作した切換弁における圧力降下による力がそれぞれ流量調整手段ＦA1、ＦB1の閉方向に作用するばね力と平衡するように、前記流量調整手段ＦA1、ＦB1の開度を調整する。
【００６３】
従って、切換弁をフル操作した場合には、センタバイパス通路は閉鎖されるので、各切換弁においては、それぞれ予め設定された開度に応じて、必要流量が第１の可変容量ポンプＰ1 および第２の可変容量ポンプＰ2 から平衡して供給される。
【００６４】
この結果、例えばブーム用切換弁ＢＭおよびアーム用切換弁ＡＲＭにおいては、フルストロークにおける開度を大きく設定しておけば、第１の可変容量ポンプＰ1 および第２の可変容量ポンプＰ2 の最大流量を全量活用することができるので、各アクチュエータとしてのシリンダの速度を速めることができる。一方、走行用切換弁ＴＬ、ＴＲにおいては、フルストローク状態での開度を、例えば第１の可変容量ポンプＰ1 および第２の可変容量ポンプＰ2 の最大流量の１／２ずつを利用するように設定すれば、走行用切換弁ＴＬまたはＴＲにおいては、共に可変容量ポンプ１個分相当の油量を各走行モータへ供給することができる。
【００６５】
また、Ｂ群の切換弁に含まれる複数のいずれかの切換弁を同時操作した場合でも、各切換弁に設けた流量調整手段の作用により、各切換弁に接続されたアクチュエータへは、第１の可変容量ポンプＰ1 および第２の可変容量ポンプＰ2 からの圧油を確実に流量配分して供給することができる。
【００６６】
（４）Ａ群およびＢ群の切換弁を同時操作した場合
図１に示す実施例において、Ａ群の切換弁としての旋回用切換弁ＳＷと、Ｂ群の切換弁としてのブーム用切換弁ＢＭとを、同時操作した場合（ブーム上げ操作）を仮定すると、旋回の起動時においては、旋回の慣性が大きいために、第１の可変容量ポンプＰ1 の圧油供給通路１０１の圧力は上昇するが、殆ど旋回モータへは圧油が流れない。しかし、ブームの圧力は、旋回に比較すれば低いので、ブーム用切換弁ＢＭの操作に対応して、ブームは素早く動く。
【００６７】
しかるに、本実施例においては、分岐ラインＬA2を経て開閉弁１０２、流量調整手段ＦA2および逆止弁１０８を介して、第２の可変容量ポンプＰ2 の圧油供給通路２０１に接続されているので、前記開閉弁１０２を旋回用切換弁の操作信号により操作するように構成した場合、前記開閉弁１０２は所定量に絞られているので、圧油が圧油供給通路１０１から分岐ラインＬA2を流過して、圧油供給ライン２０２ヘ流入するに際し、開閉弁１０２で圧力降下が発生して、この下流側の通路２１９の圧力が低下する。
【００６８】
一方、前記流量調整手段ＦA2の閉方向には、旋回用切換弁ＳＷの中間室１１２の圧力が検出されて作用しているが、この中間室の圧力は、旋回起動時には高圧となっているので、流量調整手段ＦANの開度は絞られ、通路２１９と旋回用切換弁ＳＷの中間室１１２の圧力とが、ほぼ等しくなるように調整される。この結果、旋回駆動するのに必要な圧力を、第１の可変容量ポンプＰ1 で維持すると共に、一部の余剰油を第２の可変容量ポンプＰ2 の圧油供給ライン２０２に供給し、ブーム用切換弁ＢＭに補給してアクチュエータとしてのブームシリンダを高速に動作させることができる。
【００６９】
さらに、開閉弁１０２の最終開度を調整することにより、前記ブームシリンダへの供給油量を調整することができるので、本発明を適用し得る機械の操作条件に応じて、旋回とブームとの圧油の流量配分率を調整することができ、機械の作業性ないし生産性を向上させることができる。
【００７０】
なお、前述した実施例の油圧制御装置において、Ｂ群の切換弁がブーム用切換弁ＢＭ以外の場合であっても、Ａ群の切換弁の圧力が高い場合には、前述した実施例と同じ効果を得ることができる。また、この場合、Ｂ群の切換弁のうち複数の切換弁が同時に操作されても、Ｂ群の切換弁に含まれる切換弁の間で、各切換弁に設けられた流量調整手段の作用により、第２の可変容量ポンプの吐出流量と第１の可変容量ポンプからの余剰油が、Ｂ群の切換弁内の各切換弁の操作量に応じて各アクチュエータへ配分される。
【００７１】
また、前記（３）項の場合において、第１の可変容量ポンプおよび第２の可変容量ポンプに対する吐出流量調整方法は、前記（２）項および（１）項の場合と同様である。
【００７２】
さらに、Ａ群の切換弁に接続されたアクチュエータの負荷圧が、Ｂ群の切換弁に接続されたアクチュエータの負荷圧より低い場合には、通路２１７の圧力は、逆止弁２１１を経てＡ群の切換弁の流量調整手段にも作用するので、Ａ群およびＢ群の切換弁を通して各切換弁間の流量配分が確実に行われる。
【００７３】
特に、本発明に係る上部旋回体を有する機械の油圧制御装置においては、追加切換弁が必要な場合には、センタバイパスを有する切換弁であるにも拘らず、きわめて容易に切換弁を追加することができ、多用途に対応することができる。しかも、本発明の油圧制御装置に適用する切換弁の構造として、図２および図３に示す構成とすることにより、圧油の最大流量を容易に調整することができ、機械にアクチュエータが追加された場合でも、各アクチュエータに応じた最適な速度並びに既設のアクチュエータとの間でも、確実な流量配分を行うことができる。
【００７４】
以上、本発明の好適な実施例について説明したが、本発明は前記実施例に限定されることなく、本発明の精神を逸脱しない範囲内において多くの設計変更が可能である。
【００７５】
【発明の効果】
前述したように、本発明に係る上部旋回体を有する機械の油圧制御装置は、第１の可変容量ポンプの供給ラインにＡ群の切換弁をパラレルに接続すると共に、第２の可変容量ポンプの供給ラインにＢ群の切換弁をパラレルに接続し、各切換弁は、前記可変容量ポンプの圧油供給通路からの圧油をアクチュエータへ供給するに際し、前記圧油供給通路から、切換スプールの移動により開度の調整される開口部、中間室を経て、シリンダポートへ供給するよう構成すると共に、前記中間室とシリンダポートとの間の油路上またはシリンダポートとタンクラインとの間の油路上に、この油路の開度を調整する流量調整手段を設けて、その開度を前記各切換弁の中間室の圧力により前記油路を開方向に調整し、各切換弁には、中間室の圧力を検出する検出手段を設け、Ａ群の切換弁およびＢ群の切換弁においてそれぞれ検出された圧力の中の最高圧力ＰA およびＰB を選択し、Ａ群およびＢ群の切換弁内の各流量調整手段に対してその開度を閉方向に調整するよう作用させると共に、前記圧力ＰA およびＰB の各通路を圧力ＰA からＰB へ圧油が流れるのを阻止する向きに逆止弁を設けて連通接続し、第１の可変容量ポンプの圧油供給通路から２つの分岐ラインＬA1およびＬA2を分岐し、一方の分岐ラインＬA1は、一方の流量調整手段ＦA1を介してタンクラインに接続して、前記流量調整手段ＦA1の開度を前記圧力ＰA とばね力とにより閉方向に調整すると共に第１の可変容量ポンプの吐出圧力により開方向に調整し、他方の分岐ラインＬA2は、他の流量調整手段ＦANと逆止弁とを介して前記第２の可変容量ポンプの圧力供給通路に接続し、第２の可変容量ポンプの圧油供給通路から分岐ラインＬB1を分岐し、この分岐ラインＬB1は、流量調整手段ＦB1を介してタンクラインに接続して、前記流量調整手段ＦB1の開度を前記第２の可変容量ポンプの吐出圧力により開方向に調整すると共に前記圧力ＰB とばね力とにより閉方向に調整する構成としたことにより、複数のアクチュエータを同時操作する場合において、各アクチュエータの負荷圧が大きく異なっていても、第１および第２の可変容量ポンプの吐出油をきわめて有効に活用し、各アクチュエータの速度維持、各可変容量ポンプの吐出流量の有効活用を図ることができる。
【００７６】
特に、本発明の油圧制御装置によれば、圧油の最大流量を容易に調整することができると共に、アクチュエータが追加された場合においても、各アクチュエータに応じた最適な速度並びに既設のアクチュエータとの間においても、確実な圧油の流量配分を達成することができる。
【図面の簡単な説明】
【図１】本発明に係る上部旋回体を有する機械の油圧制御装置の一実施例を示す油圧制御回路図であって、（ａ）は前記油圧制御回路全体を示し、（ｂ）は（ａ）のＡ群を拡大して示し、（ｃ）は（ａ）のＢ群中の１つ例えば、ＴＬの部分を拡大して示す。
【図２】図１に示す油圧制御装置に適用する切換弁の構造の一実施例を示す要部断面概略構成図である。
【図３】図１に示す油圧制御装置に適用する切換弁の構造の別の実施例を示す要部断面概略構成図である。
【図４】図１に示す油圧制御装置の変形例を示す油圧制御回路の要部回路図である。
【図５】従来の油圧制御装置の油圧制御回路図である。
【符号の説明】
１０１、２０１圧油供給通路
１０２開閉弁
１０３、１０８、１１１、逆止弁
１０４、２１４流量調整手段
１０６、１１９、２０７信号ライン
１０７、２０８吐出流量調整機構
１１０、２１０絞り
１１２、２１２中間室
１１３ばね
１１５、１１６シリンダポート
１０５、１１７、２０６通路
１１８、２１８タンクライン
１２９絞り
２０５、２１１、２１３、２１５逆止弁
２０２圧油供給ライン
２０３センタバイパス通路
２０４出口通路
２１６、２１７、２１９通路
Ｐ1 第１の可変容量ポンプ
Ｐ2 第２の可変容量ポンプ
ＦA1、ＦB1 流量調整手段
ＬA1、ＬA2 分岐ライン
ＬB1 分岐ライン
ＦTA、ＦTB 圧力発生手段
ＦAN、ＦA2 流量調整手段
ＰA 、ＰB 圧油の最高圧力
１３０バルブボディ
１３２圧油供給通路
１３３切欠部
１３４切換スプール
１３６中間室
１３８ａ、３８ｂシリンダポート
１４０通路
１４２逆止弁
１４４補助ポート
１４５、１４６、１４５′、１４６′ 切欠部
１４７タンクライン
１４８流量調整手段
１５０スプール
１５０ａ肩部
１５０ｂ切欠部
１５１凹部
１５２ばね
１５３、１５４、１５５スプール穴
１５４ａ環状通路
１５６カバー部
１５８内部通路
１６０逆止弁
１６１通路
１６２背室
１６２ａ、１６２ｂ、１６２ｃ他の背室
１６４前室
１６５通路
１６６センタバイパス通路
１６８連通路
１７０絞り
２３０バルブボディ
２３２圧油供給通路
２３４切換スプール
２３４ａ、２３４ｂ切欠部
２３６油室
２３８ａ、２３８ｂシリンダポート
２３９通路
２４０通路
２４２流量調整手段
２４４逆止弁
２４５油室
２４６タンクポート
２４８スプール
２４９ばね
２５０カバー
２５２スプール穴
２５４前室
２５６背室
２５８中間室
２５９ａ、２５９ｂ、２５９ｃ他の中間室
２６０、２６１通路
２６２、２６３スプール内通路
２６４連通路
２６５通路
２６６絞り
２８０センタバイパス通路
Ｐ可変容量ポンプ
Ｔタンク[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic control device for a machine having an upper turning body in a construction machine or the like, and more particularly to a hydraulic control device that improves combined operability when a plurality of actuators are operated simultaneously.
[0002]
[Prior art]
Conventionally, as a pressure oil supply device that supplies hydraulic pump discharge pressure oil to a plurality of actuators of a hydraulic excavator, for example, a plurality of directional control valves are provided in parallel in a discharge path of the hydraulic pump, and pressure is applied to the plurality of actuators. It is a closed center type that supplies oil and shuts off the pump port when neutral, and a pressure compensation valve is provided on the inlet side of each directional control valve to provide the highest load pressure of each actuator. The hydraulic pump capacity is controlled so that the differential pressure between the highest load pressure and the pump pressure becomes the set value, and the discharge pressure oil of the hydraulic pump can be simultaneously applied to multiple actuators regardless of the size of the load. Is known as a closed center type load sensing system that supplies oil with a flow distribution according to the opening area of the directional control valve. .
[0003]
However, the pressure oil supply apparatus configured as described above has the following problems when the operation of turning the upper vehicle body by the turning hydraulic motor and the operation of operating the work machine by the boom cylinder and the bucket cylinder are performed simultaneously. .
[0004]
That is, when hydraulic oil is supplied to a turning hydraulic motor and the working machine is operated by supplying pressure oil to, for example, a boom cylinder during a steady turning operation of the upper vehicle body, the capacity of the hydraulic pump is equal to the flow rate of the boom cylinder. Instantaneous increase to meet On the other hand, since the load pressure of the boom cylinder is higher than the load pressure of the swing hydraulic motor, the pressure compensation valve provided on the direction control valve for swing operates in a direction with a smaller opening area due to the load pressure of the boom cylinder. Even if the hydraulic pump capacity is increased, the flow rate supplied to the swing hydraulic motor is kept constant, but there is a slight delay before the pressure compensation valve reaches the compensated position. In the meantime, an excessive flow rate flows to the turning hydraulic motor, and the turning speed increases momentarily. For this reason, the upper vehicle body cannot be turned smoothly, and there is a problem that the ride comfort of the operator is deteriorated.
[0005]
In order to solve such a difficulty, a hydraulic oil supply device has been proposed in which a hydraulic pump that supplies pressure oil to the turning hydraulic motor is provided separately, and the turning circuit and the working circuit are made independent. However, in this case, when turning is started, the load torque of the turning hydraulic motor is large, the pump discharge pressure of the turning hydraulic pump rises to the set pressure of the relief valve, and most of the discharge flow rate flows out of the relief valve to the tank. It will be useless.
[0006]
Thus, as means for solving the above-mentioned difficulties, for example, a pressure oil supply device having a configuration shown in FIG. 5 has been proposed (Japanese Patent Laid-Open No. 10-37907).
[0007]
In other words, the pressure oil supply device according to the proposal in FIG. 5 includes a variable displacement type first hydraulic pump 1, a plurality of closed center type directional control valves 3 (3-1 to 3-5), a plurality of A pressure compensation valve 21 is provided, and the capacity of the first hydraulic pump 1 is controlled to a value corresponding to the highest load pressure, and the highest load pressure is applied to each pressure compensation valve 21 to discharge the first hydraulic pump 1. A first hydraulic circuit that supplies pressure oil to a plurality of actuators at a flow rate distribution corresponding to the opening area of the direction control valve 3, and a discharge hydraulic oil discharged from the second hydraulic pump 30 in an open center type (for turning) direction A second hydraulic circuit that is supplied to a specific actuator (rotation hydraulic motor 40) by a control valve 33, and a communication path 41 that connects the discharge path 32 of the second hydraulic pump 30 to the discharge path 2 of the first hydraulic pump 1. And a channel provided in the communication passage 41. A check valve 42 and a switching valve 43. The check valve 42 is configured such that pressure oil does not flow from the discharge path 2 of the first hydraulic pump 1 to the discharge path 32 of the second hydraulic pump 30, and the switching valve 43 is It is configured to be switchable between a blocking position and a communication position. Reference numeral 31 denotes a pilot hydraulic pump.
[0008]
Therefore, according to the pressure oil supply apparatus configured as described above, the discharge hydraulic oil from the first hydraulic pump 1 is supplied to a plurality of actuators (left traveling hydraulic motor 4, bucket cylinder 5, right traveling hydraulic motor 6, boom cylinder 7). The arm cylinder 8) can be supplied with a flow rate distribution according to the opening area of the direction control valve 3 (3-1 to 3-5), so that a plurality of actuators can be operated simultaneously by one hydraulic pump. it can. Since the first hydraulic circuit including the first hydraulic pump 1 and the second hydraulic circuit including the second hydraulic pump 30 are independent, the directional control valve 3 and the specific directional control valve 33 are simultaneously operated. Thus, when the actuator and the specific actuator (turning hydraulic motor 40) are operated simultaneously, there is an advantage that the specific actuator is not accelerated.
[0009]
[Problems to be solved by the invention]
However, in the conventional pressure oil supply apparatus according to the above proposal, various problems to be improved remain.
[0010]
That is, in the prior art, the application example is a hydraulic excavator, and the variable displacement pump as the first hydraulic pump 1 is provided with a directional control valve 3 (3-1 to 3-5) for operating an actuator excluding turning. The pressure oil from the second hydraulic pump 30 is independently supplied to the turning direction control valve 33 connected in parallel, and when the boom and the turn are operated simultaneously, the pressure oil supply line of the second hydraulic pump 30 32 is connected to the pressure oil supply line 2 of the first hydraulic pump 1 through a check valve 42 and a switching valve 43. Therefore, according to such a configuration, in the case of the simultaneous operation, the driving pressure of the turning hydraulic motor 40 only rises to the boom driving pressure, and surplus oil for turning is supplied to the boom cylinder 7. The speed of the boom cylinder 7 is increased.
[0011]
However, in the prior art, the second hydraulic pump 30 is utilized only when turning alone or turning and boom are operated simultaneously. For example, when the arm cylinder 8, the bucket cylinder 5 or the like is operated, The oil discharged from the second hydraulic pump 30 is not effectively used at all, and is merely discharged to the tank line. Therefore, there is an energy saving problem.
[0012]
In consideration of the case where the swing and the arm are operated simultaneously, the prime mover that drives the two pumps naturally requires the sum of the energy of the two pumps, and the turning speed is equivalent to that of the conventional system. When the level is maintained, the capacity of the second hydraulic pump cannot be reduced. Therefore, in the case of an arm single operation in which the pressure oil is supplied only from the first hydraulic pump, there is a difficulty that a necessary and sufficient arm speed cannot be obtained.
[0013]
Therefore, as a result of earnest research and examination, the present inventor is composed of a machine having an upper swing body that is driven by a plurality of actuators including at least a swing motor and a boom cylinder, and each actuator has a first variable capacity. The pressure oil from the pump and the second variable displacement pump is supplied through each switching valve to which each actuator is connected, and the return oil from each actuator is discharged to the tank line through the switching valve, The plurality of switching valves are divided into a group A switching valve that receives the pressure oil supplied from the first variable displacement pump and a group B switching valve that receives the pressure oil supplied from the second variable displacement pump. And a hydraulic control device for a machine having an upper rotating body configured to supply pressure oil from one or both of the first and second variable displacement pumps to each actuator. The group A switching valve is connected in parallel to the first variable displacement pump supply line, and the group B switching valve is connected in parallel to the second variable displacement pump supply line. When supplying the pressure oil from the pressure oil supply passage of each variable displacement pump to the actuator, the valve passes from the pressure oil supply passage through an opening, an intermediate chamber whose opening is adjusted by the movement of the switching spool, A flow rate adjusting means for adjusting the opening of the oil passage is provided on the oil passage between the intermediate chamber and the cylinder port or on the oil passage between the cylinder port and the tank line. The opening is configured to adjust the oil passage in the opening direction by the pressure of the intermediate chamber of each switching valve, and each switching valve is provided with detecting means for detecting the pressure of the intermediate chamber, group The highest pressures PA and PB are selected from the pressures detected in the switching valve and the switching valve of the B group, respectively, and the opening degree is set in the closing direction with respect to each flow rate adjusting means in the switching valve of the A group and the B group. A check valve is provided in communication with each of the passages of the pressures PA and PB so as to prevent pressure oil from flowing from the pressures PA to PB, and further connected to the pressure of the first variable displacement pump. Two branch lines LA1 and LA2 are branched from the supply passage, and one branch line LA1 is connected to the tank line via one flow rate adjusting means FA1, and the opening degree of the flow rate adjusting means FA1 is set to the pressure PA and The adjustment is made in the closing direction by the spring force and in the opening direction by the discharge pressure of the first variable displacement pump, and the other branch line LA2 is connected to the second through the other flow rate adjusting means FAN and the check valve. Of variable displacement pump The branch line LB1 is branched from the pressure oil supply path of the second variable displacement pump, and this branch line LB1 is connected to the tank line via the flow rate adjusting means FB1. By adjusting the opening degree of the flow rate adjusting means FB1 in the opening direction by the discharge pressure of the second variable displacement pump and adjusting in the closing direction by the pressure PB and the spring force, a plurality of actuators can be used simultaneously. When operating, even if the load pressure of each actuator is greatly different, the discharge oil of the first and second variable displacement pumps is utilized very effectively, the speed of each actuator is maintained, and the discharge flow rate of each variable displacement pump is adjusted. I found out that it could be used effectively.
[0014]
Accordingly, an object of the present invention is to improve the combined operability when simultaneously turning and turning other actuators when driving a construction machine or the like using two variable displacement pumps and two variable displacement pumps. It is an object of the present invention to provide a hydraulic control device for a machine having an upper rotating body capable of effectively utilizing oil discharged from a capacity pump.
[0015]
[Means for Solving the Problems]
To achieve the above object, a hydraulic control device for a machine having an upper swing body according to the present invention comprises a machine having an upper swing body driven by a plurality of actuators including at least a swing motor and a boom cylinder, and each of the actuators Pressure oil from the first variable displacement pump and the second variable displacement pump is supplied through each switching valve to which each actuator is connected, and return oil from each actuator is supplied to the tank line through the switching valve. The plurality of switching valves are divided into a group A switching valve that receives supply of pressure oil from the first variable displacement pump, and B that receives supply of pressure oil from the second variable displacement pump. Upper revolving body configured to supply pressure oil from one or both of the first and second variable displacement pumps to each actuator divided into a group of switching valves The hydraulic control device for a machine having,
A group A switching valve is connected in parallel to the supply line of the first variable displacement pump, and a group B switching valve is connected in parallel to the supply line of the second variable displacement pump.
Each switching valve has an opening and an intermediate chamber whose opening degree is adjusted by the movement of the switching spool from the pressure oil supply passage when supplying the pressure oil from the pressure oil supply passage of each variable displacement pump to the actuator. And a flow rate adjusting means for adjusting the opening degree of the oil passage on the oil passage between the intermediate chamber and the cylinder port or on the oil passage between the cylinder port and the tank line. And adjusting the oil passage in the opening direction by the pressure of the intermediate chamber of each switching valve,
Each switching valve is provided with detecting means for detecting the pressure in the intermediate chamber, and selects the highest pressures PA and PB among the pressures detected in the switching valve of the A group and the switching valve of the B group, respectively. The flow rate adjusting means in the switching valve of the group B is operated so as to adjust the opening degree in the closing direction, and the pressure oil is prevented from flowing from the pressure PA to the PB through the passages of the pressures PA and PB. A check valve is installed in the direction and connected in communication.
Two branch lines LA1 and LA2 are branched from the pressure supply passage of the first variable displacement pump, and one branch line LA1 is connected to the tank line via one flow rate adjusting means FA1, and the flow rate adjusting means FA1. Is adjusted in the closing direction by the pressure PA and the spring force, and is adjusted in the opening direction by the discharge pressure of the first variable displacement pump. The other branch line LA2 is non-returned with other flow rate adjusting means FAN. Connected to the pressure supply passage of the second variable displacement pump through a valve,
The branch line LB1 is branched from the pressure oil supply passage of the second variable displacement pump, and this branch line LB1 is connected to the tank line via the flow rate adjusting means FB1, and the opening degree of the flow rate adjusting means FB1 is set to the first level. And adjusting in the opening direction by the discharge pressure of the variable displacement pump 2 and adjusting in the closing direction by the pressure PB and the spring force.
[0016]
In this case, the other flow rate adjusting means FAN on the branch line LA2 can be configured as an on-off valve whose opening degree can be adjusted by an external signal.
[0017]
The other flow rate adjusting means FAN on the branch line LA2 is composed of an on-off valve capable of adjusting the opening degree by an external signal and the flow rate adjusting means FA2, and the opening degree of the flow rate adjusting means FA2 is the flow rate adjusting means. The adjustment is made in the opening direction by the pressure of the oil passage between FA2 and the on-off valve, and the adjustment is made in the closing direction by the selected maximum pressure in the intermediate chamber of the switching valve included only in the switching valve of group A. can do.
[0018]
Further, the group A switching valve may include at least a turning switching valve, and the group B switching valve may include at least a boom switching valve.
[0019]
On the other hand, the machine having the upper swing body is a machine driven by two travel motors, the group A switching valve is provided with a switching valve for turning, and the group B switching valve is at least for boom switching. It can be set as the structure provided with the valve and the said two travel drive switching valves.
[0020]
The machine having the upper swing body is a machine that is driven to travel by one traveling motor. The switching valve for the A group includes a switching valve for rotation and a switching valve for driving driving, and the switching of the B group. The valve can be configured to include at least a boom switching valve.
[0022]
The machine having the upper swing body includes a machine driven by at least a swing motor, one traveling motor, a boom cylinder, an arm cylinder, and a bucket cylinder. A switching valve for turning and a switching valve for driving are provided, and the switching valve for the group B can be provided with switching valves for at least a boom cylinder, an arm cylinder, and a bucket cylinder.
[0023]
In the present invention, the on-off valve provided on the branch line LA2 is maintained in the open position in the neutral position, and the opening degree is adjusted in the closing direction by the operation signal of the switching valve included in the group A switching valve. can do.
[0024]
In this case, the signal for operating the on-off valve on the branch line LA2 can be an operation signal for the turning switching valve.
[0025]
The on-off valve provided on the branch line LA2 is maintained in the open position in the neutral position, and the opening degree is adjusted in the closing direction by the operation signal of the turning switching valve, and the boom raising operation signal of the boom switching valve is adjusted. Thus, the opening degree can be adjusted in the opening direction.
[0026]
Further, each switching valve is a closed center type switching valve, and pressure generating means FTA, FTB are provided downstream of the flow rate adjusting means FA1, FB1, and the first variable displacement pump according to the upstream pressure of these pressure generating means. And the discharge flow rate of the second variable displacement pump can be adjusted respectively.
[0027]
On the other hand, each of the switching valves is an open center type switching valve, pressure generating means FTA, FTB are provided downstream of the flow rate adjusting means FA1, FB1, and a center bypass passage is provided through the group A switching valve and the group B switching valve. And an outlet of the center bypass passage is connected to the upstream side of the pressure generating means FTA and FTB via a check valve, respectively, and a first variable capacity is set according to the upstream pressure of the pressure generating means FTA and FTB. The discharge flow rates of the pump and the second variable displacement pump can be adjusted respectively.
[0028]
As an alternative, the switching valve is an open center type switching valve, pressure generating means FTA and FTB are provided downstream of the flow rate adjusting means FA1 and FB1, and a center bypass passage is provided through the group A switching valve and the group B switching valve. The outlet of the center bypass passage is connected to the upstream side of the pressure generating means FTA, and the discharge flow rates of the first variable capacity pump and the second variable capacity pump according to the upstream pressure of the pressure generating means FTA and FTB. It can also be configured to adjust each of them.
[0029]
In the configuration of the hydraulic control device, a pressure oil supply passage, a center bypass passage, a tank line, and a pressure PB passage are opened at the end face of the switching valve constituting the switching valve of the group B, and the end face of the switching valve is covered. The cover member may be closed, and a passage connecting the pump supply line and the center bypass passage may be provided in the cover member.
[0030]
An additional switching valve is provided between the outermost end face of the switching valve constituting the group B switching valve and the cover member. The additional switching valve has a pressure oil supply passage common to the group B switching valve, a center It is possible to provide a configuration including a bypass passage, a tank line, and a signal line communicating with the passage of pressure PB.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of a hydraulic control device for a machine having an upper rotating body according to the present invention will be described in detail with reference to the accompanying drawings.
[0032]
  FIG. 1 is a hydraulic circuit diagram showing an embodiment of a hydraulic control apparatus according to the present invention. That is, FIG.(A), (b), (c)In the figure, reference numeral P1 denotes a first variable displacement pump, and P2 denotes a second variable displacement pump. The discharge oil of the first variable displacement pump P1 and the second variable displacement pump P2 is supplied from the group A switching valve (swivel switching valve SW) and the group B switching valve via the pressure oil supply passages 101 and 201, respectively. (The left travel switching valve TL, the right travel switching valve TR, the bucket switching valve BKT, the boom switching valve BM, and the arm switching valve ARM).
[0033]
A flow rate adjusting means 104 is provided in association with the turning switching valve SW as the group A switching valve, and this flow rate adjusting means 104 is provided between the intermediate chamber 112 and the cylinder ports 115 and 116. The opening degree of the flow rate adjusting means 104 is adjusted in the opening direction by the pressure of the intermediate chamber 112 and the spring force of the spring 113, and is adjusted in the closing direction by the pressure PA of the passage 117.
[0034]
Further, branch lines LA1 and LA2 branch from the pressure oil supply passage 101 of the first variable displacement pump P1, and a flow rate adjusting means FA1 and a pressure generating means FTA are provided on one branch line LA1. A part of the oil flowing out through the outlet passage 204 of the center bypass passage 203 flowing out through the group B switching valve and the group A switching valve is branched, and the outlet passage 204 further includes a check valve. The communication line 103 is connected to the downstream side of the flow rate adjusting means FA1 on the branch line LA1 and the upstream side of the pressure generating means FTA. Further, the signal line 106 is led out from the same position as the position where the outlet passage 204 is communicated and connected to the discharge flow rate adjusting mechanism 107 of the first variable displacement pump P1.
[0035]
In the embodiment shown in FIG. 1, the discharge flow rate control methods of the first variable displacement pump P1 and the second variable displacement pump P2 are both negative flow rate control methods.
[0036]
The other branch line LA2 is provided with another flow rate adjusting means FAN composed of the on-off valve 102 and the flow rate adjusting means FA2, and the pressure oil supply of the second variable displacement pump P2 is supplied via the check valve 108. Line 202 is connected. In this embodiment, the opening degree of the on-off valve 102 is adjusted in the closing direction by the operation signal of the turning switching valve SW, and the boom raising operation signal of the boom switching valve BM included in the B group switching valve. It is configured to adjust or maintain in the opening direction. The on-off valve 102 is configured to maintain a predetermined opening degree even at a full stroke position. On the other hand, the opening degree of the flow rate adjusting means FA2 is adjusted in the closing direction by the pressure in the intermediate chamber 112 of the turning switching valve SW, and is adjusted in the opening direction by the upstream pressure of the flow rate adjusting means FA2. Yes.
[0037]
Further, in the switching valve of the group B, each switching valve is connected in parallel to the pressure oil supply line 202 of the second variable displacement pump P2, and each switching valve is in the oil passage between the tank line 218 and the switching valve. Further, a flow rate adjusting means (for example, the flow rate adjusting means 214 in the left travel switching valve TL) is provided corresponding to each switching valve. Further, the pressure in the intermediate chamber of each switching valve (for example, the pressure in the intermediate chamber 212 in the left travel switching valve TL) is detected and guided to the passage 217, respectively.
[0038]
In the embodiment shown in FIG. 1, the pressure in each intermediate chamber (212) is selected to be high by a check valve (213) provided in each flow rate adjusting means (214). The highest pressure PB is detected in the passage 217 among the pressures in the intermediate chamber of the switching valve.
[0039]
A branch line LB1 is branched from the pressure oil supply passage 201 of the second variable displacement pump P2, and a flow rate adjusting means FB1 and a pressure generating means FTB are provided on the branch line LB1, and the downstream side thereof is connected to the tank T. It is connected to a tank line 118 that communicates. On the branch line LB1, the outlet passage 204 of the center bypass passage 203 is branched and connected between the flow rate adjusting means FB1 and the pressure generating means FTB via a check valve 205. Further, the signal line 207 is led out from the same position as the position where the outlet passage 204 is connected in communication, and is transmitted to the discharge flow rate adjusting mechanism 208 of the second variable displacement pump P2.
[0040]
As an alternative, in the embodiment shown in FIG. 1, the outlet passage 204 of the center bypass passage 203 is connected to the upstream side of the pressure generating means FTA and FTB via check valves 103 and 205, respectively. As shown in FIG. 4, the outlet passage 204 of the center bypass passage 203 can be connected only to the upstream side of one pressure generating means FTA, and the check valves 103 and 205 can be omitted.
[0041]
In the embodiment shown in FIG. 1, the highest pressure is detected in the passages 117 and 217 among the pressures in the intermediate chambers of the switching valves included in the switching valve of the A group and the switching valve of the B group. These passages are connected via a check valve 211 provided in a direction allowing only the flow from the passage 217 to the passage 117. The passages 117 and 217 are configured to communicate with the drain line Dr via the throttles 110 and 210 in order to ensure low pressure when the switching valves are in the neutral position.
[0042]
Switching valve structure (1)
FIG. 2 shows a structure as an embodiment of each switching valve applicable to the hydraulic control device described above. That is, in FIG. 2, reference numeral 130 indicates a valve body. The valve body 130 includes a common pressure oil supply passage 132 that receives supply of pressure oil from the variable displacement pump P, a switching spool 134, and the switching spool 134. , The intermediate chamber 136 that receives the supply of pressure oil from the pressure oil supply passage 132, the passages 140 and 140 to the cylinder ports 138a and 138b, the check valve 142, and the cylinder spool 138a by the movement of the switching spool 134. Alternatively, the auxiliary ports 144 and 144 for discharging the pressure oil of 138b to the tank T and the tank line 147 are incorporated.
[0043]
The switching spool 134 is provided with a notch 133 for connecting the pressure oil supply passage 132 to the intermediate chamber 136 as the switching spool 134 moves. Further, the switching spool 134 is provided with notches 145, 145 'and 146, 146' for connecting the cylinder port 138a or 138b to the passage 140 or the auxiliary port 144 in accordance with the movement of the switching spool 134. Yes.
[0044]
The auxiliary ports 144 and 144 are provided between the cylinder ports 138a and 138b and the tank line 147, and between the auxiliary ports 144 and 144 and the tank line 147, the cylinder ports 138a and 138b are connected to the tank line 147. A flow rate adjusting means 148 for adjusting the opening degree A of the passage is provided.
[0045]
However, the flow rate adjusting means 148 includes a spool 150 and a spring 152, and the spool 150 is slidably and liquid-tightly held in spool holes 153, 154, and 155 formed in the valve body 130, respectively. One end thereof is surrounded and held by the cover 156. One end of the internal passage 158 provided in the spool 150 is connected to the back chamber 162 formed in the cover 156 via the check valve 160 and the passage 161, and the other end opens to the front chamber 164. In this case, the check valve 160 is incorporated so as to prevent the flow of pressure oil from the back chamber 162 to the front chamber 164.
[0046]
On the other hand, the front chamber 164 is connected to the intermediate chamber 136 through a passage 165, and the spring 152 is housed and disposed in the front chamber 164 to elastically hold the other end of the spool 150. Yes.
[0047]
In this way, the flow rate adjusting means 148 has its opening degree A while the shoulder 150a of the spool 150 is engaged with the spool hole 154 as the spool 150 moves downward against the elasticity of the spring 151. Is configured to be gradually reduced by being restricted by the notch 150b.
[0048]
In the configuration diagram shown in FIG. 2 of the present embodiment, a center bypass passage 166 is provided for the switching spool to configure as an open center type hydraulic control device, but as a closed center type hydraulic control device. Of course, it can also be configured.
[0049]
Further, in this embodiment, a plurality of switching valves having the configuration shown in FIG. 2 are included, and the back chamber 162 of the switching valve shown in FIG. 2 is in the flow rate adjusting means of another switching valve not shown. Each back chamber (for example, 162 a, 162 b, 162 c) is connected via a communication path 168, and this communication path 168 is connected to the tank T through an appropriate throttle 170.
[0050]
Switching valve structure (2)
FIG. 3 shows the structure of another embodiment of each switching valve that can be applied to the hydraulic control device described above. That is, in FIG. 3, reference numeral 230 indicates a valve body. The valve body 230 has a common pressure oil supply passage 232 that receives supply of pressure oil from the variable displacement pump P, a switching spool 234, and the switching spool 234. Are provided in the middle of an oil chamber 236 that receives supply of pressure oil from the pressure oil supply passage 232, cylinder ports 238a and 238b, and passages 240 and 240 from the oil chamber 236 to the cylinder port 238a or 238b. The flow rate adjusting means 242, check valves 244 and 244, and a tank port 246 that discharges the pressure oil in the cylinder ports 238 a and 238 b to the tank T by the movement of the switching spool 234 are built-in. In the structure of the switching valve of the present embodiment, a part of the switching spool 234 is supplied with the pressure oil branched to the pressure oil supply passage 232 that receives the supply of the pressure oil from the variable displacement pump P. A center bypass passage 280 is provided.
[0051]
However, the flow rate adjusting means 242 includes a spool 248 and a spring 249. In the neutral position, the spring 249 opens the passage 239 communicating with the spool 248 from the oil chamber 236 to the cylinder ports 238a and 238b. Hold this. The spool 248 is surrounded by the cover 250 and one end of the spool 248 is brought into contact with the cover 250 so that the spool 248 is slidably and liquid-tightly held in a spool hole 252 provided in the valve body 230.
[0052]
On the other hand, the valve body 230 is provided with passages 240 and 240 communicating with the passage 239, check valves 244 and 244 are provided in the middle of the passages 240 and 240, and the oil chamber 236 of the passage 239. A front chamber 254 is formed on the side. A back chamber 256 is formed in the cover 250 that holds one end of the spool 248, and the spring 249 is accommodated in the back chamber 256.
[0053]
Further, an intermediate chamber 258 is provided at an intermediate portion of the spool hole 252 between the passage 240 and the back chamber 256. When the spool 248 is in the neutral position, the spool 248 is disposed in the intermediate chamber 258. Are arranged so that the passages 260 and 261 provided in the opening are opened. However, in the spool 248, the passage 260 is connected to the back chamber 256 through the spool internal passage 262. The passage 261 has a relatively small diameter and has a throttling effect.
[0054]
The intermediate chamber 258 is connected to each intermediate chamber (for example, 259a, 259b, 259c) of another switching spool having the same configuration as that shown in FIG. 3 of the present embodiment via a communication path 264, and this communication path 264 Is connected to the tank T through an aperture 266 as appropriate.
[0055]
Next, the operation of the hydraulic control device for the machine having the upper swing body in the above-described embodiment will be described.
[0056]
  (1)When each switching valve is in the neutral position
  In the embodiment shown in FIG. 1, when all the switching valves are in the neutral position, the intermediate chamber of each switching valve212Is the pressure oil supply passage202Therefore, the passages 117 and 217 are both maintained at a low pressure. Then, the discharge oil of the first variable displacement pump P1 opens the flow rate adjusting means FA1 on the branch line LA1 (against the spring force and the low pressure PA) and flows out to the passage 105. The discharged oil is led to the pressure oil supply line 202 of the second variable displacement pump P2 via the branch line LA2, and further to the passage 105, via the check valve 103, 205, via the center bypass passage 203 and the outlet passage 204. It flows out to 206.
[0057]
Similarly, in the second variable displacement pump P2, the discharged oil flows through the pressure oil supply passage 201 and the branch line LB1, passes through the flow rate adjusting means FB1 and the pressure generating means FTB, and then reaches the tank line 118. And then flows out to the passages 105 and 206 through the check valves 103 and 205 through the pressure oil supply line 202, the center bypass passage 203 and the outlet passage 204.
[0058]
Therefore, in the embodiment shown in FIG. 1, since the first variable displacement pump P1 and the second variable displacement pump P2 are of the negative flow rate control method, the first variable displacement pump is characterized by the characteristics of this control method. The discharge flow rates of P1 and the second variable displacement pump P2 are maintained at the minimum values.
[0059]
(2)When the switching valve of group A is operated
In the embodiment shown in FIG. 1, the turning switching valve SW is shown as the switching valve of the A group. However, when this switching valve is operated upward in the drawing, the amount of oil discharged to the outlet passage 204 of the center bypass passage 203 Decreases in accordance with the operation amount of the switching valve, and the center bypass passage 203 is closed at the full stroke position. At the same time, the pressure in the intermediate chamber 112 of this switching valve is detected by the passage 117 via the check valve 111, and this acts together with the spring force in the closing direction of the flow rate adjusting means FA1, so that the switching valve SW is throttled. By setting the pressure drop at 129 to be slightly smaller than the pressure due to the spring force, the flow rate adjusting means FA1 is closed, so that no oil is discharged into the passage 105, so that the discharge oil of the first variable displacement pump P1 is The maximum amount is supplied to a swing motor (not shown).
[0060]
In this state, the pressure oil in the passage 117 is prevented from flowing to the switching valve of the group B by the check valve 211, so the passage 217 is maintained at a low pressure, and the pressure in the pressure oil supply line 202 is Since the check valve 215 does not act on the second variable displacement pump P2, the oil discharged from the second variable displacement pump P2 is discharged from the flow rate adjusting means FB1 to the passage 206 at a low pressure. A predetermined pressure is generated in the passage 206 by acting on the generating means FTB, and the discharge oil of the second variable displacement pump P2 is kept to a minimum.
[0061]
  Therefore, group AFor turning included inSwitching valveSWIs operated, only the first variable displacement pump P1 is in an operating state, and the second variable displacement pump P2 maintains a minimum discharge state at a low pressure, so that energy loss can be minimized. .
[0062]
(3)When the switching valve of group B is operated
When the switching valve of the group B is operated, the pressure in the intermediate chamber of the operated switching valve is detected by the passage 217. The detected pressure reaches the flow rate adjusting means FB1 through the signal line 216, and is led out to the passage 117 through the check valve 211, and further reaches the flow rate adjusting means FA1 through the signal line 119. The opening degree of the flow rate adjusting means FA1, FB1 is adjusted so that the force due to the pressure drop in the switching valve is balanced with the spring force acting in the closing direction of the flow rate adjusting means FA1, FB1.
[0063]
Accordingly, when the switching valve is fully operated, the center bypass passage is closed, so that each switching valve has a required flow rate corresponding to the first variable displacement pump P1 and the first variable pump according to the preset opening degree. The two variable displacement pumps P2 are supplied in equilibrium.
[0064]
As a result, for example, in the boom switching valve BM and the arm switching valve ARM, the maximum flow rates of the first variable displacement pump P1 and the second variable displacement pump P2 can be increased if the opening in the full stroke is set large. Since the entire amount can be utilized, the speed of the cylinder as each actuator can be increased. On the other hand, in the travel switching valves TL and TR, the opening in the full stroke state is used, for example, by half each of the maximum flow rates of the first variable displacement pump P1 and the second variable displacement pump P2. If set, in the travel switching valve TL or TR, the amount of oil corresponding to one variable displacement pump can be supplied to each travel motor.
[0065]
In addition, even when any one of the plurality of switching valves included in the switching valve of the group B is operated simultaneously, the actuator connected to each switching valve is connected to the first by the action of the flow rate adjusting means provided in each switching valve. The pressure oil from the variable displacement pump P1 and the second variable displacement pump P2 can be reliably distributed and supplied.
[0066]
(4)When the switching valves of group A and group B are operated simultaneously
In the embodiment shown in FIG. 1, it is assumed that the turning switching valve SW as the switching valve for the A group and the boom switching valve BM as the switching valve for the B group are operated simultaneously (boom raising operation). At the start of turning, since the turning inertia is large, the pressure in the pressure oil supply passage 101 of the first variable displacement pump P1 rises, but almost no pressure oil flows to the turning motor. However, since the pressure of the boom is lower than that of turning, the boom moves quickly in response to the operation of the boom switching valve BM.
[0067]
However, in the present embodiment, since it is connected to the pressure oil supply passage 201 of the second variable displacement pump P2 via the branch line LA2 via the on-off valve 102, the flow rate adjusting means FA2, and the check valve 108, When the on-off valve 102 is operated by the operation signal of the turning switching valve, the on-off valve 102 is throttled to a predetermined amount, so that the pressure oil flows through the branch line LA2 from the pressure oil supply passage 101. Then, when flowing into the pressure oil supply line 202, a pressure drop occurs in the on-off valve 102, and the pressure in the downstream passage 219 decreases.
[0068]
On the other hand, in the closing direction of the flow rate adjusting means FA2, the pressure in the intermediate chamber 112 of the turning switching valve SW is detected and acted on. However, the pressure in the intermediate chamber is high when the turning is started. The opening degree of the flow rate adjusting means FAN is reduced, and the passage 219 and the pressure in the intermediate chamber 112 of the turning switching valve SW are adjusted so as to be substantially equal. As a result, the pressure required for rotational driving is maintained by the first variable displacement pump P1, and a part of the surplus oil is supplied to the pressure oil supply line 202 of the second variable displacement pump P2, thereby A boom cylinder as an actuator can be operated at high speed by replenishing the switching valve BM.
[0069]
Furthermore, since the amount of oil supplied to the boom cylinder can be adjusted by adjusting the final opening degree of the on-off valve 102, depending on the operating conditions of the machine to which the present invention can be applied, The flow rate distribution ratio of the pressure oil can be adjusted, and the workability or productivity of the machine can be improved.
[0070]
In the hydraulic control apparatus of the above-described embodiment, even when the group B switching valve is other than the boom switching valve BM, when the pressure of the group A switching valve is high, the same as the above-described embodiment. An effect can be obtained. Further, in this case, even if a plurality of switching valves among the switching valves of the group B are operated simultaneously, the flow rate adjusting means provided in each switching valve is operated between the switching valves included in the switching valve of the group B. The discharge flow rate of the second variable displacement pump and the surplus oil from the first variable displacement pump are distributed to each actuator according to the operation amount of each switching valve in the switching valve of the B group.
[0071]
In the case of the item (3), the discharge flow rate adjustment method for the first variable displacement pump and the second variable displacement pump is the same as the case of the items (2) and (1).
[0072]
Further, when the load pressure of the actuator connected to the switching valve of the group A is lower than the load pressure of the actuator connected to the switching valve of the group B, the pressure in the passage 217 is passed through the check valve 211 to the group A. Therefore, the flow rate distribution between the switching valves is reliably performed through the switching valves of the A group and the B group.
[0073]
In particular, in the hydraulic control apparatus for a machine having an upper swing body according to the present invention, when an additional switching valve is required, it is very easy to add the switching valve even though the switching valve has a center bypass. Can be used for various purposes. In addition, by adopting the configuration shown in FIGS. 2 and 3 as the structure of the switching valve applied to the hydraulic control device of the present invention, the maximum flow rate of pressure oil can be easily adjusted, and an actuator is added to the machine. Even in this case, the flow rate can be surely distributed between the optimum speed corresponding to each actuator and the existing actuator.
[0074]
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and many design changes can be made without departing from the spirit of the present invention.
[0075]
【The invention's effect】
As described above, the hydraulic control apparatus for a machine having an upper swing structure according to the present invention connects the group A switching valve in parallel to the supply line of the first variable displacement pump and the second variable displacement pump. A group B switching valve is connected in parallel to the supply line, and each switching valve moves the switching spool from the pressure oil supply passage when supplying pressure oil from the pressure oil supply passage of the variable displacement pump to the actuator. And is configured to be supplied to the cylinder port through an opening whose intermediate opening is adjusted, an intermediate chamber, and an oil path between the intermediate chamber and the cylinder port or an oil path between the cylinder port and the tank line. The flow passage adjusting means for adjusting the opening of the oil passage is provided, and the opening is adjusted in the opening direction by the pressure of the intermediate chamber of each switching valve. Detect pressure And a maximum pressure PA and PB is selected from the pressures detected in the group A switching valve and the group B switching valve, respectively, and the flow rate adjusting means in the group A and group B switching valves is selected. In order to adjust the opening in the closing direction, a check valve is provided in each of the passages of the pressures PA and PB so as to prevent pressure oil from flowing from the pressures PA to PB, and is connected in communication. Two branch lines LA1 and LA2 are branched from the pressure oil supply passage of one variable displacement pump, and one branch line LA1 is connected to a tank line via one flow rate adjusting means FA1, and the flow rate adjusting means FA1. Is adjusted in the closing direction by the pressure PA and the spring force, and is adjusted in the opening direction by the discharge pressure of the first variable displacement pump. The other branch line LA2 is non-returned with other flow rate adjusting means FAN. Said second possible through a valve Connected to the pressure supply passage of the capacity pump and branched from the pressure oil supply passage of the second variable capacity pump, the branch line LB1 is connected to the tank line via the flow rate adjusting means FB1, By adjusting the opening degree of the flow rate adjusting means FB1 in the opening direction by the discharge pressure of the second variable displacement pump and adjusting in the closing direction by the pressure PB and the spring force, a plurality of actuators can be operated simultaneously. In this case, even if the load pressure of each actuator is greatly different, the discharge oil of the first and second variable displacement pumps is utilized very effectively, the speed of each actuator is maintained, and the discharge flow rate of each variable displacement pump is effective. Can be used.
[0076]
  In particular, according to the hydraulic control apparatus of the present invention, the maximum flow rate of pressure oil can be easily adjusted, and even when an actuator is added, the optimum speed corresponding to each actuator and the existing actuator can be adjusted. In betweenSureThe distribution of pressure oil flow can be achieved.
[Brief description of the drawings]
FIG. 1 is a hydraulic control circuit diagram showing an embodiment of a hydraulic control device for a machine having an upper swing body according to the present invention.(A) shows the entire hydraulic control circuit, (b) shows an enlarged view of group A in (a), and (c) shows one of the groups B in (a), for example, a portion of TL Zoom in to show.
FIG. 2 is a schematic cross-sectional view of an essential part showing an embodiment of the structure of a switching valve applied to the hydraulic control device shown in FIG.
FIG. 3 is a schematic cross-sectional view of an essential part showing another embodiment of the structure of the switching valve applied to the hydraulic control device shown in FIG.
FIG. 4 is a main part circuit diagram of a hydraulic control circuit showing a modification of the hydraulic control device shown in FIG. 1;
FIG. 5 is a hydraulic control circuit diagram of a conventional hydraulic control device.
[Explanation of symbols]
101, 201 Pressure oil supply passage
102 On-off valve
103, 108, 111, check valve
104, 214 Flow rate adjusting means
106, 119, 207 Signal line
107, 208 Discharge flow rate adjustment mechanism
110, 210 aperture
112, 212 Intermediate room
113 Spring
115, 116 Cylinder port
105, 117, 206 passage
118, 218 tank lines
129 Aperture
205, 211, 213, 215 Check valve
202 Pressure oil supply line
203 Center bypass passage
204 Exit passage
216, 217, 219 passage
P1 first variable displacement pump
P2 Second variable displacement pump
FA1, FB1 Flow rate adjustment means
LA1, LA2 branch line
LB1 branch line
FTA, FTB Pressure generation means
FAN, FA2 Flow rate adjustment means
Maximum pressure of PA and PB pressure oil
130 Valve body
132 Pressure oil supply passage
133 Notch
134 Change spool
136 Intermediate room
138a, 38b Cylinder port
140 passage
142 Check valve
144 Auxiliary port
145, 146, 145 ', 146' Notch
147 Tank line
148 Flow rate adjusting means
150 spool
150a shoulder
150b Notch
151 recess
152 Spring
153, 154, 155 Spool hole
154a Annular passage
156 Cover part
158 Internal passage
160 Check valve
161 passage
162 Back room
162a, 162b, 162c Other back chambers
164 Front room
165 passage
166 Center bypass passage
168 communication path
170 aperture
230 Valve body
232 Pressure oil supply passage
234 spool selection
234a, 234b Notch
236 Oil chamber
238a, 238b Cylinder port
239 passage
240 passage
242 Flow rate adjusting means
244 Check valve
245 Oil chamber
246 Tank port
248 spool
249 Spring
250 cover
252 Spool hole
254 front room
256 back chamber
258 Intermediate room
259a, 259b, 259c Other intermediate chambers
260, 261 passage
262, 263 Passage in spool
H.264 communication path
265 passage
266 Aperture
280 Center bypass passage
P variable displacement pump
T tank

Claims

It comprises a machine having an upper swing body driven by a plurality of actuators including at least a swing motor and a boom cylinder, and each actuator supplies pressure oil from the first variable displacement pump and the second variable displacement pump to each actuator. Supplying via each connected switching valve, the return oil from each actuator is discharged to the tank line via the switching valve, and the plurality of switching valves are supplied with pressure from the first variable displacement pump. The first and second variable displacement pumps are divided into a group A switching valve that receives supply of oil and a group B switching valve that receives supply of pressure oil from the second variable displacement pump. In the hydraulic control device for a machine having an upper rotating body configured to supply pressure oil from one or both of the first and second variable displacement pumps, The changeover valve is connected in parallel, and the switching valve of group B is connected in parallel to the supply line of the second variable displacement pump. Each changeover valve applies pressure oil from the pressure oil supply passage of each variable displacement pump to the actuator. When supplying to the cylinder port, the pressure oil supply passage is supplied to the cylinder port through the opening and the intermediate chamber whose opening degree is adjusted by the movement of the switching spool, and between the intermediate chamber and the cylinder port. On the oil passage or on the oil passage between the cylinder port and the tank line, a flow rate adjusting means for adjusting the opening of the oil passage is provided, and the opening is controlled by the pressure in the intermediate chamber of each switching valve. The switching valve is provided with detection means for detecting the pressure in the intermediate chamber, and the highest pressures PA and PB among the pressures detected in the switching valve of the A group and the switching valve of the B group, respectively. choose Then, the flow rate adjusting means in the switching valves of the A group and the B group are operated so as to adjust the opening degree in the closing direction, and the pressure oil passes from the pressure PA to the PB through the passages of the pressures PA and PB. A check valve is provided and connected in a direction to prevent flow, and the two branch lines LA1 and LA2 are branched from the pressure supply passage of the first variable displacement pump. Connected to the tank line through the means FA1, the opening degree of the flow rate adjusting means FA1 is adjusted in the closing direction by the pressure PA and the spring force, and is adjusted in the opening direction by the discharge pressure of the first variable displacement pump. The other branch line LA2 is connected to the pressure supply passage of the second variable displacement pump via another flow rate adjusting means FAN and a check valve, and branches from the pressure oil supply passage of the second variable displacement pump. Branch line LB1 and this branch line B1 is connected to the tank line via the flow rate adjusting means FB1, and adjusts the opening degree of the flow rate adjusting means FB1 in the opening direction by the discharge pressure of the second variable displacement pump, and the pressure PB and the spring force. A hydraulic control device for a machine having an upper swing structure, wherein the hydraulic control device is configured to be adjusted in a closing direction by means of.

2. The hydraulic control device for a machine having an upper swing body according to claim 1, wherein the other flow rate adjusting means FAN on the branch line LA2 is configured as an on-off valve capable of adjusting an opening degree by an external signal.

The other flow rate adjusting means FAN on the branch line LA2 comprises an on-off valve that can adjust the opening degree by an external signal and the flow rate adjusting means FA2, and the opening degree of the flow rate adjusting means FA2 is the same as that of the flow rate adjusting means FA2. Adjusting in the opening direction by the pressure of the oil passage between the on-off valve and adjusting in the closing direction by the selected maximum pressure in the intermediate chamber of the switching valve included only in the switching valve of group A A hydraulic control device for a machine having an upper rotating body according to claim 1.

4. A machine having an upper swing body according to claim 1, wherein the switching valve of the group A includes at least a switching valve for turning, and the switching valve of the group B includes at least a switching valve for a boom. Hydraulic control device.

The machine having the upper swing body is a machine that is driven by two travel motors. The group A switching valve includes a swing switching valve, and the group B switching valve includes at least the boom switching valve and the above-described switching valve. The hydraulic control device for a machine having an upper swing body according to any one of claims 1 to 3, comprising two travel drive switching valves.

The machine having the upper swing body is a machine that is driven to travel by one traveling motor. The switching valve for group A includes a switching valve for rotation and a switching valve for driving driving, and the switching valve for group B includes The hydraulic control device for a machine having an upper swing body according to any one of claims 1 to 3, comprising at least a boom switching valve.

Machine having an upper rotating body, at least the turning motor, and one of the traveling motor, a boom cylinder, an arm cylinder, made from the machine to be driven and a bucket cylinder, a selector valve group A, at least for turning switching together and a valve and the traveling drive switch valve, B group to the switching valve at least the boom cylinder, the upper rotating body according to any one of claims 1 consisting comprises a switching valve for the arm cylinder and bucket cylinder 3 Hydraulic control device of machine having

The on-off valve provided on the branch line LA2 is maintained in the open position in the neutral position, and is configured to adjust the opening degree in the closing direction by an operation signal of the switching valve included in the switching valve of the group A. A hydraulic control device for a machine having the upper swing body according to any one of 2 to 7 .

9. The hydraulic control apparatus for a machine having an upper swing body according to claim 8, wherein the signal for operating the on-off valve on the branch line LA2 comprises an operation signal for a switching valve for swing.

The on-off valve provided on the branch line LA2 is maintained in the open position in the neutral position, and the opening degree is adjusted in the closing direction by the operation signal of the switching valve for turning and the opening direction by the boom raising operation signal of the boom switching valve. 8. A hydraulic control apparatus for a machine having an upper rotating body according to any one of claims 2 to 7 , wherein the opening degree is adjusted to the above.

Each switching valve is a closed center type switching valve, and pressure generating means FTA and FTB are provided on the downstream side of the flow rate adjusting means FA1 and FB1, and the first variable displacement pump and the second variable pump are provided according to the upstream pressure of these pressure generating means. The hydraulic control apparatus for a machine having an upper rotating body according to any one of claims 1 to 10, wherein the discharge flow rate of each of the variable displacement pumps is adjusted.

Each switching valve is an open center type switching valve, and pressure generating means FTA and FTB are provided downstream of the flow rate adjusting means FA1 and FB1, and a center bypass passage is provided through the A group switching valve and the B group switching valve. The outlets of the bypass passages are connected to the upstream sides of the pressure generating means FTA and FTB via check valves, respectively, and the first variable displacement pump and the second variable pump are connected to the upstream side of the pressure generating means FTA and FTB. The hydraulic control device for a machine having an upper swing body according to any one of claims 1 to 10 , wherein the discharge flow rate of the variable displacement pump is adjusted respectively.

Each switching valve is an open center type switching valve, and pressure generating means FTA and FTB are provided downstream of the flow rate adjusting means FA1 and FB1, and a center bypass passage is provided through the A group switching valve and the B group switching valve. The outlet of the bypass passage is connected to the upstream side of the pressure generating means FTA, and the discharge flow rates of the first variable capacity pump and the second variable capacity pump are adjusted according to the upstream pressure of the pressure generating means FTA and FTB, respectively. The hydraulic control device for a machine having an upper swing body according to any one of claims 1 to 10 , which is configured as described above.

A pressure oil supply passage, a center bypass passage, a tank line, and a pressure PB passage are opened at the end face of the switching valve constituting the switching valve of the group B, and the end face of the switching valve is closed with a cover member. 14. The hydraulic control device for a machine having an upper rotating body according to claim 12 or 13, wherein a passage connecting the pressure oil supply passage and the center bypass passage is provided.

An additional switching valve is provided between the end face of the switching valve constituting the group B switching valve and the cover member. The additional switching valve has a pressure oil supply passage common to the group B switching valve, a center bypass passage, 15. The hydraulic control device for a machine having an upper-part turning body according to claim 14 , comprising a tank line and a signal line communicating with the passage of pressure PB.