JP2005003183A - Hydraulic circuit of construction machinery - Google Patents

Hydraulic circuit of construction machinery Download PDF

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Publication number
JP2005003183A
JP2005003183A JP2003170446A JP2003170446A JP2005003183A JP 2005003183 A JP2005003183 A JP 2005003183A JP 2003170446 A JP2003170446 A JP 2003170446A JP 2003170446 A JP2003170446 A JP 2003170446A JP 2005003183 A JP2005003183 A JP 2005003183A
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Prior art keywords
accumulator
valve
pressure
oil passage
hydraulic
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JP2003170446A
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Japanese (ja)
Inventor
Hajime Ishikawa
一 石川
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Sumitomo SHI Construction Machinery Co Ltd
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Sumitomo SHI Construction Machinery Co Ltd
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Priority to JP2003170446A priority Critical patent/JP2005003183A/en
Publication of JP2005003183A publication Critical patent/JP2005003183A/en
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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2217—Hydraulic or pneumatic drives with energy recovery arrangements, e.g. using accumulators, flywheels
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/08—Superstructures; Supports for superstructures
    • E02F9/10—Supports for movable superstructures mounted on travelling or walking gears or on other superstructures
    • E02F9/12—Slewing or traversing gears
    • E02F9/121—Turntables, i.e. structure rotatable about 360°
    • E02F9/128—Braking systems
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/226—Safety arrangements, e.g. hydraulic driven fans, preventing cavitation, leakage, overheating

Abstract

<P>PROBLEM TO BE SOLVED: To reduce load on a hydraulic pump in the hydraulic circuit of construction machinery. <P>SOLUTION: This hydraulic circuit of the construction machinery is so formed that branch oil passages 41 are formed in main pipelines 12 and 13 connected to a hydraulic motor 14 and a directional control valve 11 and sequence valves 42 are installed in the branch oil passages 41 to turn on and off the accumulation of pressure in an accumulator 43. Also, the accumulator 43 is connected to the port of the directional control valve 11 on the hydraulic pump 10 side through a filling oil passage 46, and a load holding mechanism 50 is installed in the middle of filling oil passage 46 so that pressure oil accumulated in the accumulator 43 can be discharged into the main pipelines 12 and 13. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は建設機械の油圧回路に関するものであり、特に、油圧アクチュエータに圧油を供給する油圧ポンプの負荷軽減による省エネ化に関するものである。
【０００２】
【従来の技術】
従来の此種建設機械の油圧回路を図３に示す。同図は上部旋回体を旋回させるための油圧モータの油圧回路であり、油圧ポンプ１０から吐出された圧油は方向制御弁１１を介して一方の主管路１２または１３に導出され、油圧モータ１４を回転駆動させて他方の主管路１３または１２から方向制御弁１１を介してタンク１５に戻される。
【０００３】
前記主管路１２，１３からリリーフ弁１６，１７を有するリリーフ油路１８，１９を分岐し、該リリーフ油路１８，１９の接合点が油路２０を介してタンク１５に連通している。また、前記主管路１２，１３からチェック弁２１，２２を有する油路２３，２４が分岐し、該油路２３，２４の接合点が前記油路２０を介してタンク１５に連通している。
【０００４】
前記油圧モータ１４の出力軸２５にはブレーキ装置２６が装着されており、該ブレーキ装置２６には旋回ロック弁２８を介してパイロットポンプ２９の圧油が常時導入される。従って、操作レバー２７が中立位置にあるときでも、ブレーキ装置２６は開放状態に保持され、オペレータの意志によりスイッチ（図示せず）を操作して前記旋回ロック弁２８を切り換えることにより、前記ブレーキ装置２６の制動を可能としている。そして、操作レバー２７を操作位置に操作したときは、リモコン弁３０からパイロット圧が作用して前記方向制御弁１１が切り換わり、油圧ポンプ１０の圧油が主管路１２または１３に供給され、油圧モータ１４が正転または逆転駆動される。
【０００５】
一方、操作レバー２７を操作位置から中立位置に戻したときは、前記方向制御弁１１が中立位置に復帰して主管路１２，１３が遮断される。このとき、上部旋回体の慣性力により油圧モータ１４が回転を継続しようとするため、戻り側の主管路（例えば１３）の油圧が上昇し、油圧が所定圧以上になるとリリーフ弁（例えば１７）が開き、供給側のチェック弁（例えば２１）を経て供給側の主管路（例えば１２）に連通し、圧油が循環することによって上部旋回体の慣性力を低下させる。圧油の一部は油路２０を経てタンク１５に捨てられる。
【０００６】
また、これと同様の油圧回路を備えた慣性体の揺れ戻り防止装置も知られている（例えば、特許文献１参照）。
【０００７】
【特許文献１】
特開平６−３１３４０２号公報（第１〜３頁、図１）。
【０００８】
【発明が解決しようとする課題】
上記従来の此種建設機械の油圧回路は、操作レバーを操作位置から中立位置に戻したときに、戻り側の主管路の油圧がリリーフ弁の設定圧以上に上昇した場合は、圧油の一部がタンクに捨てられるのでエネルギーの損失が大きい。また、旋回起動時に操作レバーをフル操作した場合は、油圧ポンプの負荷が大きくなってエンジンの燃料消費量が大となる。
【０００９】
そこで、建設機械の油圧回路に於いて、油圧ポンプの負荷を軽減するために解決すべき技術的課題が生じてくるのであり、本発明はこの課題を解決することを目的とする。
【００１０】
【課題を解決するための手段】
本発明は上記目的を達成するために提案されたものであり、請求項１記載の発明は、油圧ポンプからの圧油を方向制御弁を介して油圧アクチュエータに供給する建設機械の油圧回路に於いて、前記油圧アクチュエータと方向制御弁とを接続する主管路に分岐油路を設けてアキュムレータを接続するとともに、該分岐油路の途中にアキュムレータへの蓄圧を入り切りするシーケンス弁を介装し、更に、前記アキュムレータと方向制御弁の油圧ポンプ側のポートとを注入油路にて接続し、該注入油路の途中に前記アキュムレータに蓄圧された圧油を主管路へ放出するための負荷保持機構を設けた建設機械の油圧回路を提供する。
【００１１】
従って、前記シーケンス弁が入りとなれば、主管路の圧油が分岐油路を経てアキュムレータに蓄圧される。一方、負荷保持機構が開放された場合は、アキュムレータに蓄圧されている圧油を方向制御弁を経て主管路に放出することにより、油圧ポンプの負荷を軽減する。
【００１２】
請求項２記載の発明は、上記シーケンス弁は、ノーマル位置にアキュムレータ方向への流れを許容するチェック弁を有し、操作レバーが操作されたときに閉止位置に切り換わるように形成された建設機械の油圧回路を提供する。
【００１３】
従って、主管路からの圧油をアキュムレータに受け入れるが、アキュムレータに蓄圧された圧油が主管路へ不慮流出することを阻止する。
【００１４】
請求項３記載の発明は、上記負荷保持機構は、注入油路を遮断するチェック弁と、該チェック弁を開閉するための切換弁とを有し、操作レバーがフル操作されたときに該チェック弁を開放して、アキュムレータから方向制御弁方向への流れを許容するように形成された建設機械の油圧回路を提供する。
【００１５】
従って、操作レバーがフル操作されたときは負荷保持機構が開放され、アキュムレータに蓄圧した圧油を前記方向制御弁を経て主管路に放出する。
【００１６】
請求項４記載の発明は、操作レバーがフル操作されたときに、上記負荷保持機構のチェック弁を開放するための減圧弁を設けた建設機械の油圧回路を提供する。
【００１７】
従って、操作レバーがフル操作されたときのみ負荷保持機構を開放して、アキュムレータに蓄圧した圧油を放出できる。
【００１８】
【発明の実施の形態】
以下、本発明の一実施の形態を図面に従って詳述する。図１は建設機械の一例として油圧ショベル３１を示し、下部走行体３２の上に旋回機構３３を介して上部旋回体３４が旋回自在に載置されている。上部旋回体３４にはその前方一側部にキャブ３５が設けられ、且つ、前方中央部にブーム３６が俯仰可能に取り付けられている。更に、ブーム３６の先端にアーム３７が上下回動自在に取り付けられ、該アーム３７の先端にバケット３８が取り付けられている。
【００１９】
図２は本発明の油圧回路を示したものであり、説明の都合上、従来と同一構成部分には同一符号を付してその説明を省略するものとする。油圧モータ１４と方向制御弁１１とを接続する油路１２，１３の途中にシャトル弁４０を介して分岐油路４１を設け、該分岐油路４１の途中にシーケンス弁４２を介装してアキュムレータ４３を接続する。
【００２０】
このシーケンス弁４２はアキュムレータ４３への蓄圧を入り切りするものであり、ノーマル位置にアキュムレータ４３方向への流れを許容するチェック弁４２ａを有し、後述するように、操作レバー２７が操作されてリモコン弁３０からパイロット油路４４または４５に所定圧以上のパイロット圧が発生したときに、閉止位置４２ｂに切り換わるように形成されている。即ち、アキュムレータ４３に蓄圧された圧油は、シーケンス弁４２がノーマル位置または閉止位置のどちらに切り換わっても、主管路１２，１３側への流入が阻止される。
【００２１】
更に、前記アキュムレータ４３と方向制御弁１１の油圧ポンプ１０側のポートとを注入油路４６にて接続し、該注入油路４６の途中に負荷保持機構５０を設ける。この負荷保持機構５０はアキュムレータ４３に蓄圧された圧油を主管路１２，１３へ放出するためのものであり、前記注入油路４６を遮断するチェック弁５１と、該チェック弁５１を開閉するための切換弁５２とを有し、操作レバー２７がフル操作されたときに該チェック弁５１を開放して、前記アキュムレータ４３から方向制御弁１１方向への流れを許容するように形成されている。尚、前記注入油路４６には方向制御弁１１から負荷保持機構５０方向への流れを遮断するチェック弁５３が介装されている。
【００２２】
前記負荷保持機構５０について更に説明すれば、前記チェック弁５１は、注入油路４６を閉止または連通させるポペット５１ａと、該ポペット５１ａを閉止側に押圧するバネ室５１ｂとを有している。また、前記切換弁５２は、ノーマル位置にタンク１５方向への流れを遮断するチェック弁５２ａと、アキュムレータ４３に蓄圧された圧油を前記チェック弁５１のバネ室５１ｂへ連通させるバイパス５２ｂとを備え、オフセット位置に切り換わると前記バイパス５２ｂを遮断し、且つ、前記チェック弁５１のバネ室５１ｂ内の圧油をタンク１５へ連通させるように形成してある。
【００２３】
更に、前記パイロット油路４４，４５間にシャトル弁５４を介装し、該シャトル弁５４の出口にパイロット油路５５を接続するとともに、このパイロット油路５５の途中に減圧弁５６を介装して前記切換弁５２のパイロットポート５２ｃに接続する。操作レバー２７がフル操作されたときにシャトル弁５４にて高圧選択されたパイロット圧が減圧弁５６へ導出され、前記切換弁５２のパイロットポート５２ｃにパイロット圧が作用して切換弁５２がノーマル位置からオフセット位置へ切り換わるように構成されている。
【００２４】
而して、操作レバー２７を中立位置から左右何れかへ緩慢操作した場合は、リモコン弁３０からパイロット油路４４または４５へパイロット圧が導出され、前記方向制御弁１１が切り換わって、油圧ポンプ１０の圧油が主管路１２または１３に供給され、油圧モータ１４が正転または逆転駆動される。
【００２５】
このとき、操作レバー２７をフル操作しなければ、パイロット油路５５のパイロット圧も所定圧に達しないので前記減圧弁５６が閉止し、前記負荷保持機構５０の切換弁５２がノーマル位置にあって、前記チェック弁５１は閉止状態を保持する。従って、アキュムレータ４３に蓄圧された圧油はアキュムレータ４３内に保持される。
【００２６】
一方、操作レバー２７を操作位置から中立位置に戻した場合は、前記方向制御弁１１が中立位置に復帰して主管路１２，１３が遮断される。このとき、上部旋回体の慣性力により油圧モータ１４が回転を継続しようとするが、従来型と同様に、戻り側の主管路（例えば１３）の油圧が上昇して所定圧以上になるとリリーフ弁（例えば１７）が開き、供給側のチェック弁（例えば２１）を経て供給側の主管路（例えば１２）に連通し、圧油が循環することによって上部旋回体の慣性力を低下させる。本発明の油圧回路では、これと同時に、戻り側の高圧油がシャトル弁４０及びシーケンス弁４２のチェック弁４２ａを通過してアキュムレータ４３に蓄圧される。即ち、従来タンク１５に捨てられていた圧油がアキュムレータ４３に蓄圧される。
【００２７】
ここで、操作レバー２７をフル操作した場合は、前述の緩慢操作と同様に、前記方向制御弁１１が切り換わって、油圧ポンプ１０の圧油が主管路１２または１３に供給され、油圧モータ１４が正転または逆転駆動される。更に、リモコン弁３０からパイロット油路４４または４５へ導出されるパイロット圧により、前記シーケンス弁４２が閉止位置４２ｂに切り換わって分岐油路４１を遮断する。
【００２８】
また、シャトル弁５４にて高圧選択されたパイロット油路５５のパイロット圧が所定圧に達して前記減圧弁５６が開放され、前記切換弁５２のパイロットポート５２ｃにパイロット圧が作用して切換弁５２がノーマル位置からオフセット位置へ切り換わる。従って、前記チェック弁５１のバネ室５１ｂ内の圧油がタンク１５へ連通し、ポペット５１ａがバネ室５１ｂ側へ押されてチェック弁５１が開放する。
【００２９】
従って、前記アキュムレータ４３に蓄圧された圧油が、前記負荷保持機構５０のチェック弁５１を通過して注入油路４６から方向制御弁１１の油圧ポンプ１０側のポートに放出され、油圧ポンプ１０から吐出された圧油と合流して、主管路１２または１３へ大量の圧油が供給される。
【００３０】
斯くして、例えば旋回起動時等で、操作レバー２７をフル操作した場合であっても、油圧ポンプ１０から吐出した圧油のほかに、アキュムレータ４３に蓄圧された圧油を放出するので、油圧ポンプ１０の負荷を軽減してエンジンの燃料消費量を小にすることができる。
【００３１】
尚、本発明は、本発明の精神を逸脱しない限り種々の改変を為すことができ、そして、本発明が該改変されたものに及ぶことは当然である。
【００３２】
【発明の効果】
本発明は上記一実施の形態に詳述したように、請求項１記載の発明は、油圧アクチュエータと方向制御弁とを接続する主管路に分岐油路を設け、シーケンス弁を介してアキュムレータを接続し、該アキュムレータと方向制御弁の油圧ポンプ側のポートとを注入油路にて接続し、負荷保持機構を介して前記アキュムレータに蓄圧された圧油を主管路へ放出するように構成したので、従来タンクに捨てられていた圧油をアキュムレータに蓄圧し、旋回起動時等のようにエンジン負荷の大きくなるときに、アキュムレータに蓄圧した圧油を放出して油圧アクチュエータの動作を補助することにより、油圧ポンプの負荷を軽減してエンジンの燃料消費量を抑止することができる。
【００３３】
請求項２記載の発明は、上記シーケンス弁はチェック弁を有するノーマル位置と、操作レバーが操作されたときに切り換わる閉止位置とを有するので、請求項１記載の発明の効果に加えて、主管路からの圧油をアキュムレータに受け入れるが、アキュムレータに蓄圧された圧油が主管路へ不慮流出することを阻止できる。
【００３４】
請求項３記載の発明は、上記負荷保持機構は操作レバーがフル操作されたときにチェック弁を開放して、アキュムレータから方向制御弁方向への流れを許容するように形成されているので、請求項１記載の発明の効果に加えて、操作レバーがフル操作されたときに負荷保持機構が開放されて、アキュムレータに蓄圧した圧油を前記方向制御弁を経て主管路に放出することができる。
【００３５】
請求項４記載の発明は、操作レバーがフル操作されたときに負荷保持機構のチェック弁を開放するための減圧弁を設けたので、請求項１または３記載の発明の効果に加えて、操作レバーがフル操作されたときのみ負荷保持機構を開放して、アキュムレータに蓄圧した圧油を放出できる。
【図面の簡単な説明】
【図１】本発明の一実施の形態を示し、油圧ショベルの側面図。
【図２】本発明の一実施の形態を示す油圧回路図。
【図３】従来技術を示す油圧回路図。
【符号の説明】
１０ 油圧ポンプ
１１ 方向制御弁
１２，１３ 主管路
１４ 油圧モータ（油圧アクチュエータ）
２７ 操作レバー
３０ リモコン弁
４１ 分岐油路
４２ シーケンス弁
４３ アキュムレータ
４６ 注入油路
５０ 負荷保持機構
５１ チェック弁
５２ 切換弁
５６ 減圧弁[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic circuit of a construction machine, and more particularly to energy saving by reducing a load of a hydraulic pump that supplies pressure oil to a hydraulic actuator.
[0002]
[Prior art]
A hydraulic circuit of a conventional construction machine of this type is shown in FIG. The figure shows a hydraulic circuit of a hydraulic motor for turning the upper swing body. Pressure oil discharged from the hydraulic pump 10 is led to one main pipe 12 or 13 via the direction control valve 11, and the hydraulic motor 14. Is rotated and returned to the tank 15 from the other main pipe line 13 or 12 via the direction control valve 11.
[0003]
Relief oil passages 18, 19 having relief valves 16, 17 are branched from the main pipelines 12, 13, and a junction point of the relief oil passages 18, 19 communicates with the tank 15 through an oil passage 20. Further, oil passages 23 and 24 having check valves 21 and 22 branch from the main pipelines 12 and 13, and a junction point of the oil passages 23 and 24 communicates with the tank 15 through the oil passage 20.
[0004]
A brake device 26 is mounted on the output shaft 25 of the hydraulic motor 14, and pressure oil from a pilot pump 29 is always introduced into the brake device 26 via a turning lock valve 28. Therefore, even when the operation lever 27 is in the neutral position, the brake device 26 is kept open, and the switch device (not shown) is operated to switch the turning lock valve 28 by the operator's will, whereby the brake device 26 is operated. 26 braking is possible. When the operation lever 27 is operated to the operation position, pilot pressure is applied from the remote control valve 30 to switch the direction control valve 11, and the hydraulic oil of the hydraulic pump 10 is supplied to the main pipeline 12 or 13, The motor 14 is driven forward or reverse.
[0005]
On the other hand, when the operation lever 27 is returned from the operation position to the neutral position, the directional control valve 11 returns to the neutral position and the main pipelines 12 and 13 are blocked. At this time, since the hydraulic motor 14 tries to continue to rotate due to the inertial force of the upper swing body, the hydraulic pressure of the return side main pipe (for example, 13) rises, and when the hydraulic pressure exceeds a predetermined pressure, the relief valve (for example, 17) Opens, communicates with the supply side main pipe (for example, 12) via the supply side check valve (for example, 21), and the pressure oil circulates to reduce the inertial force of the upper swing body. Part of the pressure oil is discarded into the tank 15 via the oil passage 20.
[0006]
In addition, an inertial body swing back prevention device having a hydraulic circuit similar to this is also known (see, for example, Patent Document 1).
[0007]
[Patent Document 1]
JP-A-6-313402 (pages 1 to 3, FIG. 1).
[0008]
[Problems to be solved by the invention]
In the conventional hydraulic circuit of this type of construction machine, when the operating lever is returned from the operating position to the neutral position, if the hydraulic pressure of the return main line rises above the set pressure of the relief valve, The energy is lost because the part is thrown away into the tank. Further, when the operation lever is fully operated at the start of turning, the load on the hydraulic pump increases and the fuel consumption of the engine increases.
[0009]
Thus, a technical problem to be solved in order to reduce the load on the hydraulic pump occurs in the hydraulic circuit of the construction machine, and the present invention aims to solve this problem.
[0010]
[Means for Solving the Problems]
The present invention has been proposed in order to achieve the above object, and the invention according to claim 1 is a hydraulic circuit of a construction machine for supplying pressure oil from a hydraulic pump to a hydraulic actuator through a directional control valve. A branch oil passage is provided in a main pipeline connecting the hydraulic actuator and the direction control valve to connect an accumulator, and a sequence valve is provided in the middle of the branch oil passage to turn accumulator on and off. A load holding mechanism for connecting the accumulator and a port on the hydraulic pump side of the directional control valve by an injection oil passage, and discharging the pressure oil accumulated in the accumulator to the main pipeline in the middle of the injection oil passage. The hydraulic circuit of the construction machine provided is provided.
[0011]
Therefore, when the sequence valve is turned on, the pressure oil in the main pipeline is accumulated in the accumulator through the branch oil passage. On the other hand, when the load holding mechanism is released, the pressure oil accumulated in the accumulator is discharged to the main line through the direction control valve, thereby reducing the load on the hydraulic pump.
[0012]
According to a second aspect of the present invention, the sequence valve has a check valve that allows a flow in the direction of the accumulator at a normal position, and is configured to be switched to a closed position when the operation lever is operated. Providing a hydraulic circuit.
[0013]
Therefore, the pressure oil from the main pipeline is received by the accumulator, but the pressure oil accumulated in the accumulator is prevented from inadvertently flowing out to the main pipeline.
[0014]
According to a third aspect of the present invention, the load holding mechanism includes a check valve that shuts off the injection oil passage and a switching valve that opens and closes the check valve, and the check mechanism is operated when the operation lever is fully operated. A hydraulic circuit for a construction machine is provided that is configured to open the valve to allow flow from the accumulator in the direction of the directional control valve.
[0015]
Therefore, when the operation lever is fully operated, the load holding mechanism is released, and the pressure oil accumulated in the accumulator is discharged to the main pipeline through the direction control valve.
[0016]
The invention according to claim 4 provides a hydraulic circuit for a construction machine provided with a pressure reducing valve for opening the check valve of the load holding mechanism when the operation lever is fully operated.
[0017]
Therefore, the load holding mechanism can be opened only when the operation lever is fully operated, and the pressure oil accumulated in the accumulator can be released.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a hydraulic excavator 31 as an example of a construction machine, and an upper swing body 34 is mounted on a lower traveling body 32 via a swing mechanism 33 so as to be rotatable. The upper swing body 34 is provided with a cab 35 on one front side thereof, and a boom 36 is attached to the front center portion so as to be able to be raised and lowered. Further, an arm 37 is attached to the tip of the boom 36 so as to be rotatable up and down, and a bucket 38 is attached to the tip of the arm 37.
[0019]
FIG. 2 shows a hydraulic circuit according to the present invention. For convenience of explanation, the same components as those in the prior art are denoted by the same reference numerals and the description thereof is omitted. A branch oil passage 41 is provided in the middle of oil passages 12 and 13 connecting the hydraulic motor 14 and the directional control valve 11 via a shuttle valve 40, and a sequence valve 42 is provided in the middle of the branch oil passage 41 to accumulator. 43 is connected.
[0020]
This sequence valve 42 turns on and off the pressure accumulation in the accumulator 43, and has a check valve 42a that allows the flow in the direction of the accumulator 43 at the normal position. As will be described later, the operation lever 27 is operated to operate the remote control valve. When a pilot pressure equal to or higher than a predetermined pressure is generated from 30 to the pilot oil passage 44 or 45, it is configured to switch to the closing position 42b. That is, the pressure oil accumulated in the accumulator 43 is prevented from flowing into the main pipelines 12 and 13 regardless of whether the sequence valve 42 is switched to the normal position or the closed position.
[0021]
Further, the accumulator 43 and the port on the hydraulic pump 10 side of the direction control valve 11 are connected by an injection oil passage 46, and a load holding mechanism 50 is provided in the middle of the injection oil passage 46. The load holding mechanism 50 is for discharging the pressure oil accumulated in the accumulator 43 to the main pipelines 12 and 13, and for checking and closing the check valve 51 for closing the injection oil passage 46. The check valve 51 is opened when the operation lever 27 is fully operated, and the flow from the accumulator 43 to the direction control valve 11 is allowed. The injection oil passage 46 is provided with a check valve 53 that blocks the flow from the direction control valve 11 toward the load holding mechanism 50.
[0022]
The load holding mechanism 50 will be further described. The check valve 51 includes a poppet 51a for closing or communicating the injection oil passage 46, and a spring chamber 51b for pressing the poppet 51a toward the closing side. Further, the switching valve 52 includes a check valve 52a that blocks the flow in the direction of the tank 15 at a normal position, and a bypass 52b that allows the pressure oil accumulated in the accumulator 43 to communicate with the spring chamber 51b of the check valve 51. When the position is switched to the offset position, the bypass 52b is shut off, and the pressure oil in the spring chamber 51b of the check valve 51 is communicated with the tank 15.
[0023]
Further, a shuttle valve 54 is provided between the pilot oil passages 44 and 45, a pilot oil passage 55 is connected to the outlet of the shuttle valve 54, and a pressure reducing valve 56 is provided in the middle of the pilot oil passage 55. To the pilot port 52c of the switching valve 52. When the operating lever 27 is fully operated, the pilot pressure selected by the shuttle valve 54 is led to the pressure reducing valve 56, and the pilot pressure acts on the pilot port 52c of the switching valve 52 so that the switching valve 52 is in the normal position. To the offset position.
[0024]
Thus, when the operation lever 27 is slowly operated from the neutral position to either the left or right, the pilot pressure is derived from the remote control valve 30 to the pilot oil passage 44 or 45, and the direction control valve 11 is switched, so that the hydraulic pump Ten pressure oils are supplied to the main pipeline 12 or 13, and the hydraulic motor 14 is driven forward or backward.
[0025]
At this time, if the operation lever 27 is not fully operated, the pilot pressure in the pilot oil passage 55 does not reach a predetermined pressure, so that the pressure reducing valve 56 is closed and the switching valve 52 of the load holding mechanism 50 is in the normal position. The check valve 51 is kept closed. Accordingly, the pressure oil accumulated in the accumulator 43 is held in the accumulator 43.
[0026]
On the other hand, when the operation lever 27 is returned from the operation position to the neutral position, the direction control valve 11 returns to the neutral position and the main pipelines 12 and 13 are blocked. At this time, the hydraulic motor 14 tries to continue to rotate due to the inertial force of the upper swing body. However, as in the conventional type, when the hydraulic pressure in the return-side main line (for example, 13) rises and exceeds a predetermined pressure, the relief valve (For example, 17) opens, communicates with the supply side main pipe (for example, 12) through the supply side check valve (for example, 21), and the inertial force of the upper swing body is reduced by circulating pressure oil. In the hydraulic circuit of the present invention, at the same time, the high-pressure oil on the return side passes through the check valve 42a of the shuttle valve 40 and the sequence valve 42 and is accumulated in the accumulator 43. That is, the pressure oil that has been discarded in the conventional tank 15 is accumulated in the accumulator 43.
[0027]
Here, when the operation lever 27 is fully operated, the directional control valve 11 is switched and the pressure oil of the hydraulic pump 10 is supplied to the main pipeline 12 or 13 as in the above-described slow operation, and the hydraulic motor 14 Is driven forward or reverse. Further, the sequence valve 42 is switched to the closed position 42b by the pilot pressure led out from the remote control valve 30 to the pilot oil passage 44 or 45, thereby blocking the branch oil passage 41.
[0028]
Further, the pilot pressure in the pilot oil passage 55 selected at the high pressure by the shuttle valve 54 reaches a predetermined pressure, the pressure reducing valve 56 is opened, and the pilot pressure acts on the pilot port 52 c of the switching valve 52, thereby switching the switching valve 52. Switches from the normal position to the offset position. Accordingly, the pressure oil in the spring chamber 51b of the check valve 51 communicates with the tank 15, and the poppet 51a is pushed toward the spring chamber 51b, thereby opening the check valve 51.
[0029]
Accordingly, the pressure oil accumulated in the accumulator 43 passes through the check valve 51 of the load holding mechanism 50 and is discharged from the injection oil passage 46 to the port on the hydraulic pump 10 side of the direction control valve 11, and from the hydraulic pump 10. A large amount of pressurized oil is supplied to the main pipeline 12 or 13 by joining with the discharged pressurized oil.
[0030]
Thus, for example, even when the operation lever 27 is fully operated at the time of turning start or the like, in addition to the pressure oil discharged from the hydraulic pump 10, the pressure oil accumulated in the accumulator 43 is released. The load on the pump 10 can be reduced and the fuel consumption of the engine can be reduced.
[0031]
It should be noted that the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.
[0032]
【The invention's effect】
As described in detail in the above embodiment, the present invention is characterized in that a branch oil passage is provided in a main pipeline connecting a hydraulic actuator and a directional control valve, and an accumulator is connected via a sequence valve. Since the accumulator and the port on the hydraulic pump side of the directional control valve are connected by an injection oil passage, the pressure oil accumulated in the accumulator is discharged to the main pipeline via a load holding mechanism. By accumulating the pressure oil that was previously discarded in the tank in the accumulator, and releasing the pressure oil accumulated in the accumulator when the engine load becomes large, such as when starting turning, by assisting the operation of the hydraulic actuator, The load on the hydraulic pump can be reduced and the fuel consumption of the engine can be suppressed.
[0033]
In the invention according to claim 2, the sequence valve has a normal position having a check valve and a closed position which is switched when the operation lever is operated. Although the pressure oil from the passage is received by the accumulator, the pressure oil accumulated in the accumulator can be prevented from inadvertently flowing out to the main pipeline.
[0034]
Since the load holding mechanism is formed so as to allow the flow from the accumulator to the direction control valve when the operation lever is fully operated, the check valve is opened. In addition to the effect of the invention described in Item 1, when the operation lever is fully operated, the load holding mechanism is opened, and the pressure oil accumulated in the accumulator can be discharged to the main line through the direction control valve.
[0035]
Since the pressure reducing valve for opening the check valve of the load holding mechanism when the operation lever is fully operated is provided in the invention according to the fourth aspect, in addition to the effect of the invention according to the first or third aspect, Only when the lever is fully operated, the load holding mechanism can be opened to release the pressure oil accumulated in the accumulator.
[Brief description of the drawings]
FIG. 1 is a side view of a hydraulic excavator according to an embodiment of the present invention.
FIG. 2 is a hydraulic circuit diagram showing an embodiment of the present invention.
FIG. 3 is a hydraulic circuit diagram showing a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Hydraulic pump 11 Directional control valve 12, 13 Main line 14 Hydraulic motor (hydraulic actuator)
27 Control lever 30 Remote control valve 41 Branch oil passage 42 Sequence valve 43 Accumulator 46 Injection oil passage 50 Load holding mechanism 51 Check valve 52 Switching valve 56 Pressure reducing valve

Claims (4)

油圧ポンプからの圧油を方向制御弁を介して油圧アクチュエータに供給する建設機械の油圧回路に於いて、
前記油圧アクチュエータと方向制御弁とを接続する主管路に分岐油路を設けてアキュムレータを接続するとともに、該分岐油路の途中にアキュムレータへの蓄圧を入り切りするシーケンス弁を介装し、更に、前記アキュムレータと方向制御弁の油圧ポンプ側のポートとを注入油路にて接続し、該注入油路の途中に前記アキュムレータに蓄圧された圧油を主管路へ放出するための負荷保持機構を設けたことを特徴とする建設機械の油圧回路。In a hydraulic circuit of a construction machine that supplies pressure oil from a hydraulic pump to a hydraulic actuator via a directional control valve,
A branch oil passage is provided in a main pipeline connecting the hydraulic actuator and the directional control valve to connect an accumulator, and a sequence valve is provided in the middle of the branch oil passage to turn on and off the accumulated pressure in the accumulator. An accumulator and a port on the hydraulic pump side of the directional control valve are connected by an injection oil passage, and a load holding mechanism is provided in the middle of the injection oil passage to discharge the pressure oil accumulated in the accumulator to the main pipeline. A hydraulic circuit of a construction machine characterized by the above. 上記シーケンス弁は、ノーマル位置にアキュムレータ方向への流れを許容するチェック弁を有し、操作レバーが操作されたときに閉止位置に切り換わるように形成された請求項１記載の建設機械の油圧回路。2. The hydraulic circuit for a construction machine according to claim 1, wherein the sequence valve has a check valve that allows a flow in an accumulator direction at a normal position, and is configured to switch to a closed position when an operation lever is operated. . 上記負荷保持機構は、注入油路を遮断するチェック弁と、該チェック弁を開閉するための切換弁とを有し、操作レバーがフル操作されたときに該チェック弁を開放して、アキュムレータから方向制御弁方向への流れを許容するように形成された請求項１記載の建設機械の油圧回路。The load holding mechanism has a check valve that shuts off the injection oil passage and a switching valve that opens and closes the check valve. When the operation lever is fully operated, the check valve is opened and the accumulator is operated. The hydraulic circuit for a construction machine according to claim 1, wherein the hydraulic circuit is configured to allow a flow in a direction of the direction control valve. 操作レバーがフル操作されたときに、上記負荷保持機構のチェック弁を開放するための減圧弁を設けた請求項１または３記載の建設機械の油圧回路。4. The hydraulic circuit for a construction machine according to claim 1, further comprising a pressure reducing valve for opening a check valve of the load holding mechanism when the operation lever is fully operated.
JP2003170446A 2003-06-16 2003-06-16 Hydraulic circuit of construction machinery Pending JP2005003183A (en)

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US11149753B2 (en) 2017-09-11 2021-10-19 Hitachi Construction Machinery Co., Ltd. Hydraulic energy recovery apparatus for working machine
WO2021093301A1 (en) * 2019-11-14 2021-05-20 山河智能装备股份有限公司 Energy recycling device
CN111120424A (en) * 2020-01-15 2020-05-08 天津市中重科技工程有限公司 Hydraulic control system for lifting device of feeding trolley

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