FLUID PRESSURE CIRCUIT AND WORK MACHINE

• Main Authors: KANENAWA HIRONARI, IMOTO SHUHEI, HATA YOSHIHIKO, KISHIDA KOJI, TOYODA MITSUHIRO, MATOBA NOBUAKI
• Format: Patent
• Language: English; Japanese
• Published: 08.12.2016
• Subjects: BLASTING; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR; DREDGING; FIXED CONSTRUCTIONS; FLUID-PRESSURE ACTUATORS; FLUID-PRESSURE ACTUATORS, e.g. SERVO-MOTORS; FOUNDATIONS; HEATING; HYDRAULIC ENGINEERING; HYDRAULICS OR PNEUMATICS IN GENERAL; LIGHTING; MECHANICAL ENGINEERING; SOIL SHIFTING; SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; WEAPONS

PROBLEM TO BE SOLVED: To provide a fluid pressure circuit and a work machine in which an energy loss and a pressure loss during excavation idling operation can be reduced.SOLUTION: There is provided a vehicle-mounted controller operated in such a way that an operation of each of electromagnetic proportional control valves 26 and 28 and a breed-off valve 66 is controlled according to the amount of operation of a lever for operating at least the work device upwardly when the operating state of a work device is detected and it is detected that the work device is kept at an excavation state, so that a hydraulic oil supplied from pumps 12 and 13 to boom cylinders 7c1 and 7c2 is reduced, a return oil from the rod side of the boom cylinders 7c1 and 7c2 is bypassed to a tank 21, and at the same time a pump flow rate discharged from the pumps 12 and 13 is reduced. There is provided a make-up circuit M for bypassing the return oil from the rod side to the pumps 12 and 13 to a tank 21 by the breed-off valve 66 and supplementing the hydraulic oil from the tank 21 to the head sides of the boom cylinders 7c1 and 7c2.SELECTED DRAWING: Figure 1 【課題】掘削の透かし動作時のエネルギ損失および圧力損失を低減できる流体圧回路および作業機械を提供する。【解決手段】作業装置の動作状態を検出するとともに、作業装置が掘削状態であることを検出したときに、少なくとも作業装置を上方に動作させるレバーの操作量に応じて電磁比例式のブーム用制御弁26，28およびブリードオフ弁66のそれぞれの動作を制御することで、ブームシリンダ7c1，7c2にポンプ12，13から供給する作動油を低減させ、ブームシリンダ7c1，7c2のロッド側からの戻り油をタンク21にバイパスさせるとともに、ポンプ12，13から吐出するポンプ流量を低減させる車載コントローラを備える。ブリードオフ弁66によりロッド側からポンプ12，13への戻り油をタンク21にバイパスし、ブームシリンダ7c1，7c2のヘッド側にタンク21から作動油を補充するメイクアップ回路Ｍを備える。【選択図】図１