WO2017145658A1 - Work machine hydraulic circuit - Google Patents

Work machine hydraulic circuit Download PDF

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Publication number
WO2017145658A1
WO2017145658A1 PCT/JP2017/003245 JP2017003245W WO2017145658A1 WO 2017145658 A1 WO2017145658 A1 WO 2017145658A1 JP 2017003245 W JP2017003245 W JP 2017003245W WO 2017145658 A1 WO2017145658 A1 WO 2017145658A1
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WO
WIPO (PCT)
Prior art keywords
pressure
flow rate
control valve
hydraulic pump
rotation speed
Prior art date
Application number
PCT/JP2017/003245
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French (fr)
Japanese (ja)
Inventor
大木　孝利
格 宮崎
Original Assignee
日立建機株式会社
日立住友重機械建機クレーン株式会社
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Application filed by 日立建機株式会社, 日立住友重機械建機クレーン株式会社 filed Critical 日立建機株式会社
Publication of WO2017145658A1 publication Critical patent/WO2017145658A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C13/00—Other constructional features or details
    • B66C13/18—Control systems or devices
    • B66C13/20—Control systems or devices for non-electric drives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C23/00—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes
    • B66C23/62—Constructional features or details
    • B66C23/84—Slewing gear
    • B66C23/86—Slewing gear hydraulically actuated
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/05—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed specially adapted to maintain constant speed, e.g. pressure-compensated, load-responsive

Definitions

  • the present invention relates to a hydraulic circuit of a work machine.
  • a working machine As represented by a crane, a revolving body and a traveling body are provided, a working unit is further provided on the revolving body, a work object is held in the working unit, and is transferred in the turning direction.
  • a working machine In particular, in a working machine such as the above-described crane, since the work object is swung in a swingable state, transfer is performed, and thus an extremely delicate turning operation is required from the operator.
  • Patent Document 1 As a prior art for further improving the safety of a hydraulic drive device for driving a work machine, one described in Patent Document 1 can be cited.
  • a bypass line for directly connecting a tank is provided in an oil passage connecting a pump and an open center type directional control valve, and the flow rate through the meter-in throttle of the directional control valve is limited to a predetermined value or less. Because of this port, safe turning is possible according to the load of the suspended load.
  • the value of the engine speed is not reflected in the differential pressure across the meter-in throttle of the directional control valve, and there is room for improvement in operability.
  • the hydraulic circuit of the work machine includes a prime mover whose rotational speed is determined based on an operation command, a variable displacement hydraulic pump driven by the prime mover, and discharge oil from the variable displacement hydraulic pump.
  • a hydraulic circuit for a work machine including a driven swing motor and a control valve for controlling pressure oil supplied from the variable displacement hydraulic pump to the swing motor, and a rotation speed signal representing the rotation speed of the prime mover
  • a flow rate adjustment valve that adjusts the flow rate of pressure oil that is guided from the variable displacement hydraulic pump to the control valve.
  • the flow rate adjustment valve includes the rotation rate signal generation unit. Based on the output rotational speed signal, the differential pressure across the control valve is set to a value corresponding to the rotational speed of the prime mover.
  • the differential pressure before and after the meter-in throttle of the directional control valve reflects the value of the engine speed that changes based on the user's operation
  • a hydraulic circuit for a work machine that provides an uncomfortable operational feeling is provided. can do.
  • FIG. 1 is a schematic view of a crane 1.
  • the crane 1 includes a lower traveling body 10 and an upper swing body 20.
  • the lower traveling body 10 includes a pair of crawlers 11, a pair of crawler frames 12, and a pair of traveling hydraulic motors 13 that independently drive and control the crawlers 11.
  • the upper swing body 20 is driven by the driving force of the swing frame 21, the engine 22 provided on the swing frame 21, the hydraulic pump 23 driven by the engine 22, the swing hydraulic motor 24, and the swing hydraulic motor 24.
  • a drive mechanism 25 that drives the swing body to swing and a control valve unit 26 that controls the direction and flow rate of the pressure oil supplied to the swing hydraulic motor 24 are provided.
  • a boom 31 that can be raised and lowered is installed on the upper swing body 20.
  • a sheave (not shown) is provided at the tip of the boom 31, and a suspended load 33 is suspended from a hook (not shown) provided at the tip of a hoisting rope 32 that is hung around the sheave.
  • the upper swing body 20 is driven by a swing hydraulic motor 24 in a desired direction in the forward and reverse directions.
  • the hoisting rope 34 is connected to a pendant rope (not shown).
  • the boom 31 moves up and down by retracting and lifting the hoisting rope 34 with a hoisting winch (not shown).
  • the suspended load 33 is moved up and down by retracting and unwinding the hoisting rope 32 by a unillustrated hoisting winch.
  • FIG. 2 is a diagram showing the hydraulic circuit 2 of the crane 1.
  • the hydraulic circuit 2 is supplied to a hydraulic pump 23 and a pilot pump 27 that are driven by the engine 22, a turning hydraulic motor 24 that is driven by pressure oil supplied from the hydraulic pump 23, and a turning hydraulic motor 24.
  • a control valve unit 26 that controls the pressure oil, a pilot relief valve 28 that limits the upper limit of the discharge pressure of the pilot pump 27, and a rotation speed detection valve unit 29 that generates a command pressure PGR corresponding to the discharge flow rate of the pilot pump 27.
  • the command pressure PGR is one of the valve switching control pressures when the upper limit rotational speed corresponding to the engine rotational speed of the turning hydraulic motor 24 is limited.
  • the engine 22 drives the hydraulic pump 23 and the pilot pump 27. The number of revolutions of the engine 22 is controlled based on a depression amount of an unillustrated accelerator pedal operated by an operator.
  • the hydraulic pump 23 is a variable displacement hydraulic pump.
  • the discharge capacity of the hydraulic pump 23 is adjusted by a regulator controlled by a controller (not shown).
  • the hydraulic pump 23 is driven by the engine 22 and pumps pressurized oil to the control valve unit 26.
  • the pilot pump 27 is a fixed displacement hydraulic pump.
  • the pilot pump 27 is driven by the engine 22 and pumps pressurized oil to the rotation speed detection valve unit 29.
  • the control valve unit 26 includes a turning control valve (control valve) 41 that controls the flow direction and flow rate of the pressure oil supplied to the turning hydraulic motor 24, and a relief valve 42 that limits the upper limit of the discharge pressure of the hydraulic pump 23. And a flow rate adjusting valve 43 that adjusts the flow rate of the oil introduced into the turning control valve 41.
  • the flow rate adjusting valve 43 is installed on an oil passage that branches off from an oil passage that connects the discharge port of the hydraulic pump 23 and the turning control valve 41 and is connected to the tank.
  • the turning control valve 41 is at an arbitrary position between a neutral position O (initial position) shown in the figure, an A position on the left side in the figure, and a B position on the right side in the figure by a pilot pressure corresponding to the operation of a turning lever (not shown). Is switched to. Pressure oil having a flow rate corresponding to the operation amount of the turning control valve 41 is supplied to the hydraulic motor 24.
  • the turning control valve 41 is an open center type control valve. When the turning control valve 41 is in the neutral position O, the pressure oil discharged from the hydraulic pump 23 passes through a bleed-off throttle (not shown) and is tanked. Return to.
  • the turning control valve 41 moves in the direction of the A position or the B position, the opening area of the bleed-off restrictor is reduced, and the opening area of the meter-in restrictor is increased. To do.
  • the pressure oil discharged from the hydraulic pump 23 is guided to the turning hydraulic motor 24 through the meter-in throttle.
  • the turning control valve 41 is provided with a port for guiding a meter-in throttle downstream pressure, which will be described later, to the flow rate adjusting valve 43.
  • the meter-in throttle downstream pressure is the tank pressure.
  • the meter-in throttle downstream pressure is a pressure at which the discharge pressure of the hydraulic pump 23 is reduced due to the pressure loss of the meter-in throttle.
  • the flow rate adjustment valve 43 changes between the closed position A and the open position B. In the open position B, part of the oil discharged from the hydraulic pump 23 bypasses to the tank. In the closed position A, the entire amount of oil discharged from the hydraulic pump 23 is introduced into the turning control valve 43.
  • the switching position of the flow control valve 43 is controlled according to the following three pressures.
  • the first pressure is the discharge pressure (meter-in throttle upstream pressure) PC1 of the hydraulic pump 23, and is guided to urge the flow rate adjustment valve 43 to the open position B side.
  • the second pressure is the meter-in throttle downstream pressure PC2 of the turning control valve 41, and is guided to urge the flow rate adjustment valve 43 toward the closed position A.
  • the third pressure is a command pressure PGR output from the rotation speed detection valve unit 29, and is guided to urge the flow rate adjustment valve 43 toward the closed position A.
  • the flow rate adjusting valve 43 is opened and closed so that the differential pressure across the meter-in throttle of the turning control valve 41, that is, the difference between the discharge pressure PC1 of the hydraulic pump 23 and the meter-in throttle downstream pressure PC2 becomes a value corresponding to the command pressure PGR. Operates and functions as a pressure compensation valve.
  • the flow rate control valve 43 When the discharge pressure PC1 of the hydraulic pump 23> the meter-in throttle downstream pressure PC2 + the command pressure PGR, the flow rate control valve 43 is switched to the B position, and a part of the discharge flow rate of the hydraulic pump 23 is bypassed from the flow rate control valve 43 to the tank.
  • the upper limit of the turning speed is limited.
  • the flow rate adjusting valve 43 is switched to the A position, and the total amount of the pressure oil discharged from the variable displacement hydraulic pump 23 is supplied to the turning control valve 41. Supplied.
  • the differential pressure before and after the meter-in throttle is controlled to be equal to or less than a value proportional to the command pressure PGR.
  • the command pressure PGR is substantially proportional to the engine speed.
  • the turning load when the turning load is a predetermined value or more, for example, when the turning lever is fully operated, the turning speed does not exceed the upper limit value.
  • this upper limit value does not depend on the engine speed.
  • the upper limit value is changed according to the engine speed. Therefore, for example, when the turning lever is fully operated, the turning speed upper limit value when the engine speed is set in the high speed range, and the turning speed when the engine speed is set in the medium speed range The upper limit is made different.
  • the work machine of the present invention is configured to vary the differential pressure across the direction control valve in accordance with the engine speed.
  • the rotation speed detection valve unit 29 has a variable throttle 44 for generating a differential pressure corresponding to the discharge flow rate of the pilot pump 27 and a discharge pressure of the pilot pump 27 as a primary pressure, and the primary pressure is changed to a differential pressure across the variable throttle 44. And a pressure control valve 45 for generating a command pressure PGR regulated accordingly.
  • the command pressure PGR increases or decreases according to the engine speed, and is used as a switching control pressure for the flow rate adjusting valve 43 as will be described later.
  • the variable throttle 44 is switched between the open position A and the throttle position B based on the discharge pressure of the pilot pump 27 (upstream pressure of the variable throttle 44) and the downstream pressure of the variable throttle 44. Specifically, the discharge pressure of the pilot pump 27 is guided to switch the variable throttle 44 to the open position A side, and the downstream pressure of the variable throttle 44 is guided to switch the variable throttle 44 to the throttle position B side. .
  • the spring 46 biases the variable throttle 44 so as to switch to the throttle position B side.
  • the spring 46 has a spring constant such that the variable throttle 44 is switched to the open position A when pressure oil starts to be discharged from the hydraulic pump 27.
  • the variable throttle 44 generates a differential pressure across the pilot pump 27 according to the discharge flow rate, and the open position A and the throttle position B so that the discharge flow rate of the pilot pump 27 and the differential pressure across the variable throttle 44 are proportional to each other.
  • the opening area at a position between is set.
  • the downstream pressure of the variable throttle 44 is defined by the pilot relief valve 28 so as to be approximately constant.
  • the pressure control valve 45 switches between the position A and the position B based on the upstream pressure and the downstream pressure of the variable throttle 44.
  • the upstream pressure of the variable throttle 44 is larger than the sum of the downstream pressure of the variable throttle 44 and the command pressure PGR, the pressure control valve 45 is switched to the position A side, and the command is obtained by guiding the upstream pressure of the variable throttle 44.
  • Increase pressure PGR is provided by guiding the upstream pressure of the variable throttle 44.
  • the pressure control valve 45 When the upstream pressure of the variable throttle 44 is smaller than the sum of the downstream pressure of the variable throttle 44 and the command pressure PGR, the pressure control valve 45 is switched to the position B side, and the command pressure PGR is reduced by being connected to the tank. Let That is, the command pressure PGR proportional to the differential pressure across the variable throttle 44 is generated using the downstream pressure of the variable throttle 44 as the primary pressure.
  • the opening area A of the variable throttle 44 is set so that the discharge flow rate of the pilot pump 27 and the differential pressure across the variable throttle 44 have a proportional relationship.
  • the relationship of the front-rear differential pressure ⁇ P of the variable throttle 22 is expressed by the following equation (3).
  • A a ⁇ P (3)
  • Expression (3) is substituted into Expression (2)
  • the relationship between the discharge flow rate Qp of the pilot pump 27 and the differential pressure ⁇ P across the variable throttle 22 is expressed by the following Expression (4).
  • the flow control valve 43 controls the opening degree of the flow control valve 43 so that the differential pressure before and after the meter-in throttle is equal to or less than the pressure proportional to the command pressure PGR. Therefore, the upper limit value of the flow rate that passes through the turning control valve 41 is a flow rate proportional to the engine speed due to the action of the flow rate control valve 43.
  • the working machine that is, the hydraulic circuit 2 of the crane 1 includes an engine 22 as a prime mover whose rotation speed is determined based on an operation command, a variable displacement hydraulic pump 23 driven by the engine 22, and a variable displacement hydraulic pump 23.
  • a swing motor 24 driven by the oil discharged from the engine, an open center control valve 41 for controlling the pressure oil supplied from the variable displacement hydraulic pump 23 to the swing motor 24, and a hydraulic pressure representing the rotational speed of the engine 22.
  • a flow rate adjustment pressure that is a rotation speed signal that is, a rotation speed signal generation unit that generates a command pressure PGR, that is, a rotation speed detection valve unit 29, and a flow rate that adjusts the flow rate of pressure oil introduced from the variable displacement hydraulic pump 23 to the control valve 41.
  • a control valve 43 sets the differential pressure across the control valve 41 to a value corresponding to the rotational speed of the engine 22 based on the command pressure PGR output from the rotational speed detection valve unit 29.
  • the flow rate adjusting valve 43 discharges a part of the pressure oil discharged from the variable displacement hydraulic pump 23 to the tank based on the flow rate adjusting pressure output from the rotation speed detection valve unit 29.
  • the flow rate adjustment valve 43 As the command pressure PGR is higher, the flow rate adjustment valve 43 is controlled to the closed side and the amount of oil that escapes to the tank decreases. That is, a part of the pressure oil discharged from the variable displacement hydraulic pump 23 is diverted to an oil passage other than the control valve 41, that is, a tank according to the engine speed. As a result, the flow rate adjustment valve 43 controls the differential pressure across the meter-in throttle so as to be a value proportional to the engine speed.
  • the rotation speed detection valve unit 29 is configured to change the discharge pressure of the fixed displacement hydraulic pump 27 according to the front-rear differential pressure and the variable throttle 44 that generates the front-rear differential pressure by introducing the pressure oil discharged from the fixed displacement hydraulic pump 27.
  • a pressure control valve 45 for converting to the command pressure PGR.
  • the differential pressure across the meter-in throttle of the control valve 41 is set based on the command pressure PGR generated by the pressure control valve 45.
  • the control valve 41 increases as the rotational speed of the engine 22 increases.
  • the differential pressure across the meter-in throttle of the control valve increases, and the differential pressure across the meter-in throttle of the control valve decreases as the rotational speed of the engine 22 decreases. Therefore, the operator can control the torque for driving the turning hydraulic motor 24 by turning the engine control dial to increase or decrease the engine speed, and it is possible to provide a crane with better operability.
  • FIG. 3 is a diagram illustrating a hydraulic circuit 2a according to the second embodiment. Except for the configuration downstream of the pilot pump 27, the second embodiment is the same as the first embodiment.
  • the hydraulic circuit 2a of the second embodiment has a fixed throttle 44a to which the pressure oil discharged from the fixed displacement hydraulic pump 27 is guided.
  • the upstream pressure of the fixed throttle 44a is input to the flow rate adjustment valve 43 via the oil passage 29a as the command pressure PGR.
  • the upstream pressure of the fixed throttle 44a increases or decreases in proportion to the engine speed.
  • the hydraulic circuit of the second embodiment that introduces this upstream pressure as the command pressure PGR into the control port of the flow rate adjustment valve 43 can obtain the same operational effects as those of the first embodiment.
  • the rotation speed detection valve unit 29 since the rotation speed detection valve unit 29 does not exist, the linearity of the PGR with respect to the engine rotation speed is lost as in the first embodiment, but the fixed throttle Therefore, the configuration is simpler than that of the hydraulic circuit of the first embodiment.
  • a rotation detector 50 for detecting the rotation speed of the engine, an electromagnetic valve 52 for generating a command pressure PGR, and an operation command is output to the electromagnetic valve 52 based on the output of the rotation detector 50.
  • the point which is provided with the controller 51 which performs is mainly different from 1st Embodiment.
  • FIG. 4 is a diagram illustrating the connection of the hydraulic circuit 2b and the electrical system in the third embodiment.
  • a relief valve 28 and an electromagnetic valve 52 are connected to the discharge side oil passage of the pilot pump 27.
  • the solenoid valve 52 includes a solenoid that operates based on a command from the controller 51.
  • the solenoid valve 52 generates a command pressure PGR based on a command from the controller 51 using the discharge pressure of the pilot pump 27 as a primary pressure.
  • the rotation detector 50 measures the number of revolutions of the engine 22 and outputs information on the number of revolutions to the controller 51 as an electrical signal.
  • the controller 51 converts the scale of the electrical signal received from the rotation detector 50 and outputs it to the solenoid valve 52. That is, the rotation detector 50, the controller 51, and the electromagnetic valve 52 function as a rotation speed signal generation unit that generates a command pressure PGR that is information related to the rotation speed of the engine 22.
  • the command pressure PGR generated by the electromagnetic valve 52 is generated as a pressure proportional to the engine speed, similarly to the flow rate adjustment pressure output from the pressure control valve 45 of the first embodiment. Therefore, the hydraulic circuit of the third embodiment that introduces the command pressure PGR generated in this way into the control port of the flow rate control valve 43 can obtain the same operational effects as those of the first embodiment. . In the hydraulic circuit of the third embodiment, it is not necessary to provide a throttle in the discharge path of the pilot pump 27, and energy loss of the pressure oil discharged from the pilot pump 27 can be suppressed.
  • the command pressure PGR based on the rotation speed of the engine 22 measured by the rotation detector 50 is generated, and the command pressure PGR is input to the control port of the flow rate adjustment valve 43.
  • the flow control valve 43 may include a solenoid, and the flow control valve 43 may be configured to operate based on an electrical signal output from the controller 51.
  • FIG. 5 is a diagram illustrating a hydraulic circuit 2c and an electric system in a modification of the third embodiment.
  • the solenoid valve 52 is omitted and the flow rate control valve 43 is changed to an electromagnetic flow rate control valve 43a.
  • the discharge pressure (meter-in throttle upstream pressure) and the meter-in throttle downstream pressure of the hydraulic pump 23 are input to the two control ports of the flow control valve 43a.
  • An electric signal proportional to the engine speed output from the controller 51 is applied to the solenoid 43s of the electromagnetic flow control valve 43a, and the solenoid 43s is an electromagnetic switch that switches the flow control valve 43a to the position A side. Give power.
  • the electromagnetic urging force by this electric signal is a signal equivalent to the command pressure PGR. Therefore, the flow rate adjustment valve 43a has an opening degree so that the difference between the discharge pressure (meter-in throttle upstream pressure) of the hydraulic pump 23 and the meter-in throttle downstream pressure is equal to or less than the pressure proportional to the electrical signal output from the controller 51. Be controlled. Therefore, also in the modification of the third embodiment, the same operational effects as those of the first embodiment can be obtained.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Control And Safety Of Cranes (AREA)
  • Jib Cranes (AREA)

Abstract

Provided is a work machine hydraulic circuit by which good turning operation feel is obtained. This work machine hydraulic circuit is provided with: a prime mover, the rotation speed of which is determined on the basis of an operation instruction; a variable capacity hydraulic pump driven by the prime mover; a turning motor driven by the oil discharged from the variable capacity hydraulic pump; and an open center-type control valve for controlling the pressure oil supplied from the variable capacity hydraulic pump to the turning motor and, in an initial position, for performing control so that the oil discharged from the variable capacity hydraulic pump is returned to a tank. The work machine hydraulic circuit is characterized: in being provided with a rotation speed signal-generating unit for generating a rotation speed signal that represents the rotation speed of the prime mover and a flow rate adjusting valve for adjusting the flow rate of the pressure oil guided from the variable capacity hydraulic pump to the control valve; and in the flow rate adjusting valve making the pressure difference across the control valve to be a value corresponding to the rotation speed of the prime mover on the basis of the rotation speed signal output by the rotation speed signal-generating unit.

Description

作業機械の油圧回路Hydraulic circuit of work machine
　本発明は、作業機械の油圧回路に関する。 The present invention relates to a hydraulic circuit of a work machine.
　作業機械の中には、クレーンに代表されるように、旋回体及び走行体を備え、該旋回体上に更に作業部を備え、作業部にて作業対象物を保持し、旋回方向に移送する作業機が存在する。そして、特に上述したクレーンのような作業機械においては、作業対象物が搖動可能な状態で旋回する事により移送を行う為、非常に繊細な旋回操作をオペレータに要求するものであり、このような作業機械を駆動する為の油圧駆動装置の安全性をより向上する従来技術として、特許文献１に記載されたものが挙げられる。 In the work machine, as represented by a crane, a revolving body and a traveling body are provided, a working unit is further provided on the revolving body, a work object is held in the working unit, and is transferred in the turning direction. There is a working machine. In particular, in a working machine such as the above-described crane, since the work object is swung in a swingable state, transfer is performed, and thus an extremely delicate turning operation is required from the operator. As a prior art for further improving the safety of a hydraulic drive device for driving a work machine, one described in Patent Document 1 can be cited.
特開平７－２５５８９号公報Japanese Patent Laid-Open No. 7-25589
　特許文献１に記載されている発明では、ポンプとオープンセンタ型方向制御弁を結ぶ油路にタンクを直結するバイパスラインを設け、方向制御弁のメータイン絞り通過流量を所定の値以下に制限する為のポートを設けている為、吊り荷の荷重等に応じて安全な旋回を可能としている。しかし、従来技術では、方向制御弁のメータイン絞りの前後差圧にエンジン回転数の値が反映されず、操作性に関して改善の余地があった。 In the invention described in Patent Document 1, a bypass line for directly connecting a tank is provided in an oil passage connecting a pump and an open center type directional control valve, and the flow rate through the meter-in throttle of the directional control valve is limited to a predetermined value or less. Because of this port, safe turning is possible according to the load of the suspended load. However, in the prior art, the value of the engine speed is not reflected in the differential pressure across the meter-in throttle of the directional control valve, and there is room for improvement in operability.
　本発明の第１の態様の作業機械の油圧回路は、操作指令に基づき回転数が決定される原動機と、前記原動機により駆動される可変容量油圧ポンプと、前記可変容量油圧ポンプからの吐出油で駆動される旋回モータと、前記可変容量油圧ポンプから前記旋回モータへ供給される圧油を制御する制御弁とを備えた作業機械の油圧回路であって、前記原動機の回転数を表す回転数信号を生成する回転数信号生成部と、前記可変容量油圧ポンプから前記制御弁に導かれる圧油の流量を調節する流量調節弁と、を備え、前記流量調節弁は、前記回転数信号生成部が出力する前記回転数信号に基づき、前記制御弁の前後差圧を前記原動機の回転数に応じた値とする。 The hydraulic circuit of the work machine according to the first aspect of the present invention includes a prime mover whose rotational speed is determined based on an operation command, a variable displacement hydraulic pump driven by the prime mover, and discharge oil from the variable displacement hydraulic pump. A hydraulic circuit for a work machine including a driven swing motor and a control valve for controlling pressure oil supplied from the variable displacement hydraulic pump to the swing motor, and a rotation speed signal representing the rotation speed of the prime mover And a flow rate adjustment valve that adjusts the flow rate of pressure oil that is guided from the variable displacement hydraulic pump to the control valve. The flow rate adjustment valve includes the rotation rate signal generation unit. Based on the output rotational speed signal, the differential pressure across the control valve is set to a value corresponding to the rotational speed of the prime mover.
　本発明によれば、方向制御弁のメータイン絞りの前後差圧は、ユーザの操作に基づき変化するエンジン回転数の値が反映されるため、違和感のない操作感を得る作業機械の油圧回路を提供することができる。 According to the present invention, since the differential pressure before and after the meter-in throttle of the directional control valve reflects the value of the engine speed that changes based on the user's operation, a hydraulic circuit for a work machine that provides an uncomfortable operational feeling is provided. can do.
クレーンの概略図Schematic of crane 第１の実施の形態における油圧回路を示す図The figure which shows the hydraulic circuit in 1st Embodiment 第２の実施の形態における油圧回路を示す図The figure which shows the hydraulic circuit in 2nd Embodiment 第３の実施の形態における油圧回路、および電気系統の接続を示す図The figure which shows the connection of the hydraulic circuit in 3rd Embodiment, and an electrical system 第３の実施の形態の変形例における油圧回路、および電気系統の接続を示す図The figure which shows the connection of the hydraulic circuit in the modification of 3rd Embodiment, and an electric system
（第１の実施の形態）
　以下、図１～２を参照して、作業機械の油圧回路の第１の実施の形態を説明する。
（構成）
　図１は、クレーン１の概略図である。クレーン１は、下部走行体１０と、上部旋回体２０とを備える。
　下部走行体１０は、一対のクローラ１１、一対のクローラフレーム１２、およびクローラ１１を独立して駆動制御する一対の走行用油圧モータ１３を備える。
　上部旋回体２０は、旋回フレーム２１と、旋回フレーム２１に設けられたエンジン２２と、エンジン２２により駆動される油圧ポンプ２３と、旋回用油圧モータ２４と、旋回用油圧モータ２４の駆動力により上部旋回体を旋回駆動させる駆動機構２５と、旋回用油圧モータ２４へ供給される圧油の方向および流量を制御する制御弁ユニット２６とを備える。 (First embodiment)
Hereinafter, a first embodiment of a hydraulic circuit of a work machine will be described with reference to FIGS.
(Constitution)
FIG. 1 is a schematic view of a crane 1. The crane 1 includes a lower traveling body 10 and an upper swing body 20.
The lower traveling body 10 includes a pair of crawlers 11, a pair of crawler frames 12, and a pair of traveling hydraulic motors 13 that independently drive and control the crawlers 11.
The upper swing body 20 is driven by the driving force of the swing frame 21, the engine 22 provided on the swing frame 21, the hydraulic pump 23 driven by the engine 22, the swing hydraulic motor 24, and the swing hydraulic motor 24. A drive mechanism 25 that drives the swing body to swing and a control valve unit 26 that controls the direction and flow rate of the pressure oil supplied to the swing hydraulic motor 24 are provided.
　上部旋回体２０には、起伏可能なブーム３１が設置される。ブーム３１の先端には不図示のシーブが設けられ、シーブに掛け回された巻き上げロープ３２の先端に設けた不図示のフックに吊り荷３３が吊り下げられる。上部旋回体２０は、旋回用油圧モータ２４により正逆所望の方向に所望の速度で駆動される。起伏ロープ３４は不図示のペンダントロープに接続される。起伏ロープ３４を図示しない起伏ウインチで繰り込み、繰り出すことによりブーム３１が俯仰動する。巻き上げロープ３２を不図示の巻き上げウインチにより繰り込み、繰り出すことにより、吊り荷３３が昇降される。 A boom 31 that can be raised and lowered is installed on the upper swing body 20. A sheave (not shown) is provided at the tip of the boom 31, and a suspended load 33 is suspended from a hook (not shown) provided at the tip of a hoisting rope 32 that is hung around the sheave. The upper swing body 20 is driven by a swing hydraulic motor 24 in a desired direction in the forward and reverse directions. The hoisting rope 34 is connected to a pendant rope (not shown). The boom 31 moves up and down by retracting and lifting the hoisting rope 34 with a hoisting winch (not shown). The suspended load 33 is moved up and down by retracting and unwinding the hoisting rope 32 by a unillustrated hoisting winch.
　図２は、クレーン１の油圧回路２を示す図である。
　油圧回路２は、エンジン２２により駆動される油圧ポンプ２３およびパイロットポンプ２７と、油圧ポンプ２３から圧油の供給を受けて駆動される旋回用油圧モータ２４と、旋回用油圧モータ２４に供給される圧油を制御する制御弁ユニット２６と、パイロットポンプ２７の吐出圧の上限を制限するパイロットリリーフ弁２８と、パイロットポンプ２７の吐出流量に応じた指令圧ＰＧＲを発生させる回転数検出弁ユニット２９とを備える。
　後で詳細に説明するが、指令圧ＰＧＲは旋回用油圧モータ２４のエンジン回転数に応じた上限回転数を制限する際の弁切換制御圧の一つである。
　エンジン２２は、油圧ポンプ２３およびパイロットポンプ２７を駆動する。エンジン２２の回転数は、オペレータにより操作される不図示のアクセルペダルの踏込量に基づき制御される。 FIG. 2 is a diagram showing the hydraulic circuit 2 of the crane 1.
The hydraulic circuit 2 is supplied to a hydraulic pump 23 and a pilot pump 27 that are driven by the engine 22, a turning hydraulic motor 24 that is driven by pressure oil supplied from the hydraulic pump 23, and a turning hydraulic motor 24. A control valve unit 26 that controls the pressure oil, a pilot relief valve 28 that limits the upper limit of the discharge pressure of the pilot pump 27, and a rotation speed detection valve unit 29 that generates a command pressure PGR corresponding to the discharge flow rate of the pilot pump 27. Is provided.
As will be described in detail later, the command pressure PGR is one of the valve switching control pressures when the upper limit rotational speed corresponding to the engine rotational speed of the turning hydraulic motor 24 is limited.
The engine 22 drives the hydraulic pump 23 and the pilot pump 27. The number of revolutions of the engine 22 is controlled based on a depression amount of an unillustrated accelerator pedal operated by an operator.
　油圧ポンプ２３は、可変容量式の油圧ポンプである。油圧ポンプ２３の吐出容量は、不図示のコントローラにより制御されるレギュレータで調整される。油圧ポンプ２３は、エンジン２２により駆動され、制御弁ユニット２６へ圧油を圧送する。
　パイロットポンプ２７は、固定容量式の油圧ポンプである。パイロットポンプ２７は、エンジン２２により駆動され、回転数検出弁ユニット２９へ圧油を圧送する。 The hydraulic pump 23 is a variable displacement hydraulic pump. The discharge capacity of the hydraulic pump 23 is adjusted by a regulator controlled by a controller (not shown). The hydraulic pump 23 is driven by the engine 22 and pumps pressurized oil to the control valve unit 26.
The pilot pump 27 is a fixed displacement hydraulic pump. The pilot pump 27 is driven by the engine 22 and pumps pressurized oil to the rotation speed detection valve unit 29.
（制御弁ユニット２６の構成）
　制御弁ユニット２６は、旋回用油圧モータ２４に供給される圧油の流れ方向および流量を制御する旋回用制御弁（制御弁）４１と、油圧ポンプ２３の吐出圧の上限を制限するリリーフ弁４２と、旋回用制御弁４１に導入される油の流量を調節する流量調節弁４３とを備える。流量調節弁４３は、油圧ポンプ２３の吐出ポートと旋回用制御弁４１を接続する油路から分岐してタンクへ接続される油路上に設置される。 (Configuration of control valve unit 26)
The control valve unit 26 includes a turning control valve (control valve) 41 that controls the flow direction and flow rate of the pressure oil supplied to the turning hydraulic motor 24, and a relief valve 42 that limits the upper limit of the discharge pressure of the hydraulic pump 23. And a flow rate adjusting valve 43 that adjusts the flow rate of the oil introduced into the turning control valve 41. The flow rate adjusting valve 43 is installed on an oil passage that branches off from an oil passage that connects the discharge port of the hydraulic pump 23 and the turning control valve 41 and is connected to the tank.
　旋回用制御弁４１は、不図示の旋回レバーの操作に応じたパイロット圧により、図示中央の中立位置Ｏ（初期位置）、図示左側のＡ位置、および図示右側のＢ位置の間の任意の位置に切換えられる。旋回用制御弁４１の操作量に応じた流量の圧油が油圧モータ２４に供給される。旋回用制御弁４１はオープンセンタ型の制御弁であって、旋回用制御弁４１が中立位置Ｏにある場合は、油圧ポンプ２３から吐出された圧油は不図示のブリードオフ絞りを通ってタンクへ戻る。旋回用制御弁４１のパイロットポートにパイロット圧が導かれると、旋回用制御弁４１はＡ位置またはＢ位置の方向へ移動し、ブリードオフ絞りの開口面積が減少し、メータイン絞りの開口面積が増加する。油圧ポンプ２３から吐出された圧油は、メータイン絞りを通って旋回用油圧モータ２４に導かれる。 The turning control valve 41 is at an arbitrary position between a neutral position O (initial position) shown in the figure, an A position on the left side in the figure, and a B position on the right side in the figure by a pilot pressure corresponding to the operation of a turning lever (not shown). Is switched to. Pressure oil having a flow rate corresponding to the operation amount of the turning control valve 41 is supplied to the hydraulic motor 24. The turning control valve 41 is an open center type control valve. When the turning control valve 41 is in the neutral position O, the pressure oil discharged from the hydraulic pump 23 passes through a bleed-off throttle (not shown) and is tanked. Return to. When pilot pressure is introduced to the pilot port of the turning control valve 41, the turning control valve 41 moves in the direction of the A position or the B position, the opening area of the bleed-off restrictor is reduced, and the opening area of the meter-in restrictor is increased. To do. The pressure oil discharged from the hydraulic pump 23 is guided to the turning hydraulic motor 24 through the meter-in throttle.
　旋回用制御弁４１には、後述するメータイン絞り下流圧を流量調節弁４３に導くポートが設けられている。旋回用制御弁４１が中立位置Ｏにある場合、メータイン絞り下流圧はタンク圧である。旋回用制御弁４１がＡ位置またはＢ位置にある場合、メータイン絞り下流圧は油圧ポンプ２３の吐出圧がメータイン絞りの圧損で低下した圧力である。
　流量調節弁４３は、閉位置Ａと開位置Ｂとの間で換わる。開位置Ｂでは、油圧ポンプ２３の吐出油の一部がタンクへバイパスする。閉位置Ａでは、油圧ポンプ２３の吐出油は全量が旋回用制御弁４３に導入される。 The turning control valve 41 is provided with a port for guiding a meter-in throttle downstream pressure, which will be described later, to the flow rate adjusting valve 43. When the turning control valve 41 is in the neutral position O, the meter-in throttle downstream pressure is the tank pressure. When the turning control valve 41 is in the A position or the B position, the meter-in throttle downstream pressure is a pressure at which the discharge pressure of the hydraulic pump 23 is reduced due to the pressure loss of the meter-in throttle.
The flow rate adjustment valve 43 changes between the closed position A and the open position B. In the open position B, part of the oil discharged from the hydraulic pump 23 bypasses to the tank. In the closed position A, the entire amount of oil discharged from the hydraulic pump 23 is introduced into the turning control valve 43.
　流量調節弁４３の切換え位置は、以下の３つの圧力に応じて制御される。第１の圧力は油圧ポンプ２３の吐出圧（メータイン絞り上流圧）ＰＣ１であり、流量調節弁４３を開位置Ｂ側に付勢するように導かれる。第２の圧力は旋回用制御弁４１のメータイン絞り下流圧ＰＣ２であり、流量調節弁４３を閉位置Ａ側に付勢するように導かれる。第３の圧力は回転数検出弁ユニット２９から出力される指令圧ＰＧＲであり、流量調節弁４３を閉位置Ａ側に付勢するように導かれる。 The switching position of the flow control valve 43 is controlled according to the following three pressures. The first pressure is the discharge pressure (meter-in throttle upstream pressure) PC1 of the hydraulic pump 23, and is guided to urge the flow rate adjustment valve 43 to the open position B side. The second pressure is the meter-in throttle downstream pressure PC2 of the turning control valve 41, and is guided to urge the flow rate adjustment valve 43 toward the closed position A. The third pressure is a command pressure PGR output from the rotation speed detection valve unit 29, and is guided to urge the flow rate adjustment valve 43 toward the closed position A.
　流量調節弁４３は、旋回用制御弁４１のメータイン絞りの前後差圧、すなわち油圧ポンプ２３の吐出圧ＰＣ１と前述のメータイン絞り下流圧ＰＣ２の差が指令圧ＰＧＲに応じた値となるように開閉動作し、圧力補償弁としての機能を有する。 The flow rate adjusting valve 43 is opened and closed so that the differential pressure across the meter-in throttle of the turning control valve 41, that is, the difference between the discharge pressure PC1 of the hydraulic pump 23 and the meter-in throttle downstream pressure PC2 becomes a value corresponding to the command pressure PGR. Operates and functions as a pressure compensation valve.
　油圧ポンプ２３の吐出圧ＰＣ１＞メータイン絞り下流圧ＰＣ２＋指令圧ＰＧＲのとき、流量調節弁４３はＢ位置に切り換わり、油圧ポンプ２３の吐出流量の一部は流量調節弁４３からタンクへバイパスして旋回速度の上限が制限される。
　油圧ポンプ２３の吐出圧ＰＣ１≦メータイン絞り下流圧ＰＣ２＋指令圧ＰＧＲのとき、流量調節弁４３はＡ位置に切り換わり、可変容量油圧ポンプ２３から吐出される圧油の全量が旋回用制御弁４１に供給される。
　以上の動作を繰り返すことで、メータイン絞り前後差圧が指令圧ＰＧＲに比例した値以下に制御される。後述するように指令圧ＰＧＲはエンジン回転数に略比例する。 When the discharge pressure PC1 of the hydraulic pump 23> the meter-in throttle downstream pressure PC2 + the command pressure PGR, the flow rate control valve 43 is switched to the B position, and a part of the discharge flow rate of the hydraulic pump 23 is bypassed from the flow rate control valve 43 to the tank. The upper limit of the turning speed is limited.
When the discharge pressure PC1 of the hydraulic pump 23 ≦ the meter-in throttle downstream pressure PC2 + the command pressure PGR, the flow rate adjusting valve 43 is switched to the A position, and the total amount of the pressure oil discharged from the variable displacement hydraulic pump 23 is supplied to the turning control valve 41. Supplied.
By repeating the above operation, the differential pressure before and after the meter-in throttle is controlled to be equal to or less than a value proportional to the command pressure PGR. As will be described later, the command pressure PGR is substantially proportional to the engine speed.
　従来技術では、旋回負荷が所定値以上の場合に、たとえば旋回レバーがフル操作された時に旋回速度が上限値を超えないようにしている。しかし、この上限値はエンジン回転数の高低に依存していない。これに対し、本発明は、この上限値をエンジン回転数の高低に応じて変動させる。そのため、たとえば旋回レバーがフル操作された場合、エンジン回転数が高回転数域に設定されている場合の旋回速度上限値と、エンジン回転数が中回転数域に設定されている場合の旋回速度上限値が異なるようにしている。すなわち、本発明の作業機械では、方向制御弁の前後差圧をエンジン回転数に応じて変動させるように構成している。 In the prior art, when the turning load is a predetermined value or more, for example, when the turning lever is fully operated, the turning speed does not exceed the upper limit value. However, this upper limit value does not depend on the engine speed. On the other hand, in the present invention, the upper limit value is changed according to the engine speed. Therefore, for example, when the turning lever is fully operated, the turning speed upper limit value when the engine speed is set in the high speed range, and the turning speed when the engine speed is set in the medium speed range The upper limit is made different. In other words, the work machine of the present invention is configured to vary the differential pressure across the direction control valve in accordance with the engine speed.
（回転数検出弁ユニット２９の構成）
　回転数検出弁ユニット２９は、パイロットポンプ２７の吐出流量に応じた差圧を発生させる可変絞り４４と、パイロットポンプ２７の吐出圧を一次圧として、その一次圧を可変絞り４４の前後差圧に応じて調圧した指令圧ＰＧＲを発生させる圧力制御弁４５とを備える。指令圧ＰＧＲは、エンジン回転数に応じて増減し、後述するように流量調節弁４３の切換え制御圧として利用される。 (Configuration of the rotational speed detection valve unit 29)
The rotation speed detection valve unit 29 has a variable throttle 44 for generating a differential pressure corresponding to the discharge flow rate of the pilot pump 27 and a discharge pressure of the pilot pump 27 as a primary pressure, and the primary pressure is changed to a differential pressure across the variable throttle 44. And a pressure control valve 45 for generating a command pressure PGR regulated accordingly. The command pressure PGR increases or decreases according to the engine speed, and is used as a switching control pressure for the flow rate adjusting valve 43 as will be described later.
　可変絞り４４は、パイロットポンプ２７の吐出圧（可変絞り４４の上流圧）と可変絞り４４の下流圧に基づき、開位置Ａと絞り位置Ｂとの間で切り換わる。具体的には、パイロットポンプ２７の吐出圧は、可変絞り４４を開位置Ａ側に切換えるように導かれ、可変絞り４４の下流圧は、可変絞り４４を絞り位置Ｂ側に切換えるように導かれる。バネ４６は、可変絞り４４を絞り位置Ｂ側に切換えるように付勢する。バネ４６は、油圧ポンプ２７から圧油が吐出され始めると可変絞り４４が開位置Ａに切り換わるようなバネ定数を有する。 The variable throttle 44 is switched between the open position A and the throttle position B based on the discharge pressure of the pilot pump 27 (upstream pressure of the variable throttle 44) and the downstream pressure of the variable throttle 44. Specifically, the discharge pressure of the pilot pump 27 is guided to switch the variable throttle 44 to the open position A side, and the downstream pressure of the variable throttle 44 is guided to switch the variable throttle 44 to the throttle position B side. . The spring 46 biases the variable throttle 44 so as to switch to the throttle position B side. The spring 46 has a spring constant such that the variable throttle 44 is switched to the open position A when pressure oil starts to be discharged from the hydraulic pump 27.
　可変絞り４４は、パイロットポンプ２７の吐出流量に応じた前後差圧を発生させ、パイロットポンプ２７の吐出流量と可変絞り４４の前後差圧が比例関係になるように、開位置Ａと絞り位置Ｂとの間の位置における開口面積が設定される。可変絞り４４の下流圧は、パイロットリリーフ弁２８によりおおよそ一定圧となるように規定される。
　圧力制御弁４５は、可変絞り４４の上流圧と下流圧に基づき位置Ａと位置Ｂとの間で切り替わる。可変絞り４４の上流圧が可変絞り４４の下流圧と指令圧ＰＧＲとの和よりも大きい場合は、圧力制御弁４５は位置Ａ側に切り替えられ、可変絞り４４の上流圧が導かれることにより指令圧ＰＧＲを増加させる。可変絞り４４の上流圧が可変絞り４４の下流圧と指令圧ＰＧＲとの和よりも小さい場合は、圧力制御弁４５は位置Ｂ側に切り替えられ、タンクと接続されることにより指令圧ＰＧＲを減少させる。すなわち、可変絞り４４の下流圧を一次圧として、可変絞り４４の前後差圧に比例した指令圧ＰＧＲを発生させる。 The variable throttle 44 generates a differential pressure across the pilot pump 27 according to the discharge flow rate, and the open position A and the throttle position B so that the discharge flow rate of the pilot pump 27 and the differential pressure across the variable throttle 44 are proportional to each other. The opening area at a position between is set. The downstream pressure of the variable throttle 44 is defined by the pilot relief valve 28 so as to be approximately constant.
The pressure control valve 45 switches between the position A and the position B based on the upstream pressure and the downstream pressure of the variable throttle 44. When the upstream pressure of the variable throttle 44 is larger than the sum of the downstream pressure of the variable throttle 44 and the command pressure PGR, the pressure control valve 45 is switched to the position A side, and the command is obtained by guiding the upstream pressure of the variable throttle 44. Increase pressure PGR. When the upstream pressure of the variable throttle 44 is smaller than the sum of the downstream pressure of the variable throttle 44 and the command pressure PGR, the pressure control valve 45 is switched to the position B side, and the command pressure PGR is reduced by being connected to the tank. Let That is, the command pressure PGR proportional to the differential pressure across the variable throttle 44 is generated using the downstream pressure of the variable throttle 44 as the primary pressure.
　エンジン２２の回転数と可変絞り４４の前後差圧ΔＰが比例関係にあることを式を用いて詳述する。
　エンジン２２の回転数をＮ，パイロットポンプ２７の押しのけ容積Ｃｍとおくと、パイロットポンプ２７の吐出流量Ｑｐは以下の式（１）により表される。
　Ｑｐ＝ＣｍＮ・・・・・・・・・・・・・・（１）
また、可変絞り４４の開口面積をＡ、作動油の密度をρ、流出係数をｃとすると、パイロットポンプの吐出流量Ｑｐ、エンジン２２の回転数、および可変絞り２２の前後差圧であるΔＰの関係は、以下の式（２）により表される。
　Ｑｐ＝ＣｍＮ＝ｃＡ√（（２／ρ）ΔＰ）・・（２） The fact that the rotational speed of the engine 22 and the front-rear differential pressure ΔP of the variable throttle 44 are in a proportional relationship will be described in detail using equations.
When the rotational speed of the engine 22 is N and the displacement Cm of the pilot pump 27 is set, the discharge flow rate Qp of the pilot pump 27 is expressed by the following equation (1).
Qp = CmN (1)
Further, when the opening area of the variable throttle 44 is A, the hydraulic oil density is ρ, and the outflow coefficient is c, the discharge flow rate Qp of the pilot pump, the rotational speed of the engine 22, and ΔP that is the differential pressure across the variable throttle 22 The relationship is expressed by the following formula (2).
Qp = CmN = cA√ ((2 / ρ) ΔP) (2)
　前述のとおり可変絞り４４の開口面積Ａは、パイロットポンプ２７の吐出流量と可変絞り４４の前後差圧が比例関係になるように設定され、比例係数をａとすると可変絞り４４の開口面積Ａと可変絞り２２の前後差圧ΔＰの関係は、以下の式（３）により表される。
　Ａ＝ａ√ΔＰ・・・・・・・・・・・・・・（３）
　ここで式（２）に式（３）を代入すると、パイロットポンプ２７の吐出流量Ｑｐと可変絞り２２の前後差圧ΔＰの関係は、以下の式（４）により表される。
　ΔＰ＝（１／ｃａ）√（ρ／２）・Ｑｐ
　　　＝（Ｃｍ／ｃａ）√（ρ／２）・Ｎ・・・（４）
　このようにエンジン２２の回転数に比例する可変絞り４４の前後差圧ΔＰが圧力制御弁４５に作用し、前述のとおり圧力制御弁４５が可変絞り４４の前後差圧に比例した指令圧ＰＧＲを発生させる。 As described above, the opening area A of the variable throttle 44 is set so that the discharge flow rate of the pilot pump 27 and the differential pressure across the variable throttle 44 have a proportional relationship. The relationship of the front-rear differential pressure ΔP of the variable throttle 22 is expressed by the following equation (3).
A = a√ΔP (3)
Here, when Expression (3) is substituted into Expression (2), the relationship between the discharge flow rate Qp of the pilot pump 27 and the differential pressure ΔP across the variable throttle 22 is expressed by the following Expression (4).
ΔP = (1 / ca) √ (ρ / 2) · Qp
= (Cm / ca) √ (ρ / 2) · N (4)
Thus, the differential pressure ΔP across the variable throttle 44 proportional to the rotational speed of the engine 22 acts on the pressure control valve 45, and the pressure control valve 45 applies the command pressure PGR proportional to the differential pressure across the variable throttle 44 as described above. generate.
　以下、本発明の作業機械の油圧回路の動作について説明する。
（動作）
　オペレータの操作に基づき、エンジン２２の回転数、および旋回用制御弁４１の切替え位置が制御される。
　パイロットポンプ２７は、エンジン２２の回転数におおよそ比例する流量の圧油を回転数検出弁ユニット２９に圧送する。回転数検出弁ユニット２９は、可変絞り４４を通過する流量に応じた指令圧ＰＧＲを発生させる。 Hereinafter, the operation of the hydraulic circuit of the work machine of the present invention will be described.
(Operation)
Based on the operation of the operator, the rotational speed of the engine 22 and the switching position of the turning control valve 41 are controlled.
The pilot pump 27 pumps pressure oil having a flow rate approximately proportional to the rotational speed of the engine 22 to the rotational speed detection valve unit 29. The rotation speed detection valve unit 29 generates a command pressure PGR corresponding to the flow rate passing through the variable throttle 44.
　流量調節弁４３は、前述のメータイン絞りの前後差圧が、指令圧ＰＧＲに比例した圧力以下となるように、流量調節弁４３の開度を制御する。したがって、流量調節弁４３の働きにより、旋回用制御弁４１を通過する流量の上限値は、エンジン回転数に比例した流量となる。 The flow control valve 43 controls the opening degree of the flow control valve 43 so that the differential pressure before and after the meter-in throttle is equal to or less than the pressure proportional to the command pressure PGR. Therefore, the upper limit value of the flow rate that passes through the turning control valve 41 is a flow rate proportional to the engine speed due to the action of the flow rate control valve 43.
　上述した第１の実施の形態によれば、次の作用効果が得られる。
（１）作業機械、すなわちクレーン１の油圧回路２は、操作指令に基づき回転数が決定される原動機としてのエンジン２２と、エンジン２２により駆動される可変容量油圧ポンプ２３と、可変容量油圧ポンプ２３からの吐出油で駆動される旋回モータ２４と、可変容量油圧ポンプ２３から旋回モータ２４へ供給される圧油を制御するオープンセンタ型の制御弁４１と、エンジン２２の回転数を表す油圧的な回転数信号である流量調節圧、すなわち指令圧ＰＧＲを生成する回転数信号生成部すなわち回転数検出弁ユニット２９と、可変容量油圧ポンプ２３から制御弁４１に導かれる圧油の流量を調節する流量調節弁４３とを備える。流量調節弁４３は、回転数検出弁ユニット２９が出力する指令圧ＰＧＲに基づき、制御弁４１の前後差圧をエンジン２２の回転数に応じた値とする。
　流量調節弁４３は、回転数検出弁ユニット２９が出力する流量調節圧に基づき、可変容量油圧ポンプ２３から吐出される圧油のうち一部をタンクへ排出する。流量調節弁４３は、指令圧ＰＧＲが高いほど閉じ側に制御されてタンクへ逃げる油量が少なくなる。すなわち、エンジン回転数に応じて、可変容量油圧ポンプ２３が吐出する圧油の一部を制御弁４１以外の油路、すなわちタンクに分流する。その結果、流量調節弁４３は、メータイン絞り前後差圧をエンジン回転数に比例した値となるように制御する。換言すると、回転数検出弁ユニット２９は、固定容量油圧ポンプ２７が吐出する圧油が導入されて前後差圧を生成する可変絞り４４と、固定容量油圧ポンプ２７の吐出圧を前後差圧に応じた指令圧ＰＧＲに変換する圧力制御弁４５とを含む。制御弁４１のメータイン絞りの前後差圧は、圧力制御弁４５により発生する指令圧ＰＧＲに基づき設定される。 According to the first embodiment described above, the following operational effects are obtained.
(1) The working machine, that is, the hydraulic circuit 2 of the crane 1 includes an engine 22 as a prime mover whose rotation speed is determined based on an operation command, a variable displacement hydraulic pump 23 driven by the engine 22, and a variable displacement hydraulic pump 23. A swing motor 24 driven by the oil discharged from the engine, an open center control valve 41 for controlling the pressure oil supplied from the variable displacement hydraulic pump 23 to the swing motor 24, and a hydraulic pressure representing the rotational speed of the engine 22. A flow rate adjustment pressure that is a rotation speed signal, that is, a rotation speed signal generation unit that generates a command pressure PGR, that is, a rotation speed detection valve unit 29, and a flow rate that adjusts the flow rate of pressure oil introduced from the variable displacement hydraulic pump 23 to the control valve 41. And a control valve 43. The flow rate adjusting valve 43 sets the differential pressure across the control valve 41 to a value corresponding to the rotational speed of the engine 22 based on the command pressure PGR output from the rotational speed detection valve unit 29.
The flow rate adjusting valve 43 discharges a part of the pressure oil discharged from the variable displacement hydraulic pump 23 to the tank based on the flow rate adjusting pressure output from the rotation speed detection valve unit 29. As the command pressure PGR is higher, the flow rate adjustment valve 43 is controlled to the closed side and the amount of oil that escapes to the tank decreases. That is, a part of the pressure oil discharged from the variable displacement hydraulic pump 23 is diverted to an oil passage other than the control valve 41, that is, a tank according to the engine speed. As a result, the flow rate adjustment valve 43 controls the differential pressure across the meter-in throttle so as to be a value proportional to the engine speed. In other words, the rotation speed detection valve unit 29 is configured to change the discharge pressure of the fixed displacement hydraulic pump 27 according to the front-rear differential pressure and the variable throttle 44 that generates the front-rear differential pressure by introducing the pressure oil discharged from the fixed displacement hydraulic pump 27. And a pressure control valve 45 for converting to the command pressure PGR. The differential pressure across the meter-in throttle of the control valve 41 is set based on the command pressure PGR generated by the pressure control valve 45.
　クレーン１の油圧回路２をこのように構成したので、例えば、レバーをある一定の操作量に固定して、制御弁４１の開口面積を固定したとき、エンジン２２の回転数が高くなるほど制御弁４１のメータイン絞りの前後差圧が上昇し、エンジン２２の回転数が低くなるほど制御弁のメータイン絞りの前後差圧が減少する。そのため、オペレータはエンジンコントロールダイヤルを回し、エンジン回転数を上下させることで旋回用油圧モータ２４を駆動する為のトルクを制御する事が可能となり、より操作性の良いクレーンの提供が可能となる。 Since the hydraulic circuit 2 of the crane 1 is configured in this way, for example, when the lever is fixed at a certain operation amount and the opening area of the control valve 41 is fixed, the control valve 41 increases as the rotational speed of the engine 22 increases. The differential pressure across the meter-in throttle of the control valve increases, and the differential pressure across the meter-in throttle of the control valve decreases as the rotational speed of the engine 22 decreases. Therefore, the operator can control the torque for driving the turning hydraulic motor 24 by turning the engine control dial to increase or decrease the engine speed, and it is possible to provide a crane with better operability.
（第２の実施の形態）
　図３を参照して、作業機械の油圧回路の第２の実施の形態を説明する。以下の説明では、第１の実施の形態と同じ構成要素には同じ符号を付して相違点を主に説明する。特に説明しない点については、第１の実施の形態と同じである。本実施の形態では、主に、回転数検出弁ユニット２９の代わりに固定絞り４４ａを備える点で、第１の実施の形態と異なる。 (Second Embodiment)
A second embodiment of the hydraulic circuit of the work machine will be described with reference to FIG. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and different points will be mainly described. Points that are not particularly described are the same as those in the first embodiment. This embodiment differs from the first embodiment mainly in that a fixed throttle 44a is provided instead of the rotation speed detection valve unit 29.
（構成）
　クレーン１の構成は、油圧回路２を除いて第１の実施の形態と同様である。図３は、第２の実施の形態における油圧回路２ａを示す図である。パイロットポンプ２７の下流の構成以外は、第１の実施の形態と同様である。
　第２の実施の形態の油圧回路２ａは、固定容量油圧ポンプ２７が吐出する圧油が導かれる固定絞り４４ａを有する。固定絞り４４ａの上流側圧力が指令圧ＰＧＲとして油路２９ａを経由して流量調節弁４３に入力される。
　固定絞り４４ａの上流圧は、概ねエンジン回転数に比例して増減する。したがって、この上流圧を指令圧ＰＧＲとして流量調節弁４３の制御ポートに導入する第２の実施の形態の油圧回路は、第１の実施の形態と同様の作用効果を得ることができる。第２の実施の形態の油圧回路においては、回転数検出弁ユニット２９が存在しない為、第１の実施の形態のように、エンジン回転数に対するＰＧＲの線形性は失われているものの、固定絞りを用いる為、第１の実施の形態の油圧回路に比べて構成が簡易となる。 (Constitution)
The configuration of the crane 1 is the same as that of the first embodiment except for the hydraulic circuit 2. FIG. 3 is a diagram illustrating a hydraulic circuit 2a according to the second embodiment. Except for the configuration downstream of the pilot pump 27, the second embodiment is the same as the first embodiment.
The hydraulic circuit 2a of the second embodiment has a fixed throttle 44a to which the pressure oil discharged from the fixed displacement hydraulic pump 27 is guided. The upstream pressure of the fixed throttle 44a is input to the flow rate adjustment valve 43 via the oil passage 29a as the command pressure PGR.
The upstream pressure of the fixed throttle 44a increases or decreases in proportion to the engine speed. Therefore, the hydraulic circuit of the second embodiment that introduces this upstream pressure as the command pressure PGR into the control port of the flow rate adjustment valve 43 can obtain the same operational effects as those of the first embodiment. In the hydraulic circuit of the second embodiment, since the rotation speed detection valve unit 29 does not exist, the linearity of the PGR with respect to the engine rotation speed is lost as in the first embodiment, but the fixed throttle Therefore, the configuration is simpler than that of the hydraulic circuit of the first embodiment.
（第３の実施の形態）
　図４を参照して、作業機械の油圧回路の第３の実施の形態を説明する。以下の説明では、第１の実施の形態と同じ構成要素には同じ符号を付して相違点を主に説明する。特に説明しない点については、第１の実施の形態と同じである。 (Third embodiment)
With reference to FIG. 4, a third embodiment of the hydraulic circuit of the work machine will be described. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and different points will be mainly described. Points that are not particularly described are the same as those in the first embodiment.
（構成）
　回転数検出弁ユニット２９に代えて、エンジンの回転数を検出する回転検出器５０と、指令圧ＰＧＲを生成する電磁弁５２と、回転検出器５０の出力に基づき電磁弁５２に動作指令を出力するコントローラ５１とを備える点が、主に第１の実施の形態と異なる。 (Constitution)
Instead of the rotation speed detection valve unit 29, a rotation detector 50 for detecting the rotation speed of the engine, an electromagnetic valve 52 for generating a command pressure PGR, and an operation command is output to the electromagnetic valve 52 based on the output of the rotation detector 50. The point which is provided with the controller 51 which performs is mainly different from 1st Embodiment.
　図４は、第３の実施の形態における油圧回路２ｂ、および電気系統の接続を示す図である。パイロットポンプ２７の吐出側油路には、リリーフ弁２８および電磁弁５２が接続される。電磁弁５２は、コントローラ５１の指令に基づき動作するソレノイドを備える。電磁弁５２は、パイロットポンプ２７の吐出圧を１次圧として、コントローラ５１の指令に基づき指令圧ＰＧＲを生成する。
　回転検出器５０は、エンジン２２の回転数を計測し、その回転数の情報を電気信号としてコントローラ５１に出力する。コントローラ５１は、回転検出器５０から受信した電気信号をスケール変換し、電磁弁５２に出力する。すなわち、回転検出器５０、コントローラ５１、および電磁弁５２は、エンジン２２の回転数に関する情報である指令圧ＰＧＲを生成する回転数信号生成部として機能する。 FIG. 4 is a diagram illustrating the connection of the hydraulic circuit 2b and the electrical system in the third embodiment. A relief valve 28 and an electromagnetic valve 52 are connected to the discharge side oil passage of the pilot pump 27. The solenoid valve 52 includes a solenoid that operates based on a command from the controller 51. The solenoid valve 52 generates a command pressure PGR based on a command from the controller 51 using the discharge pressure of the pilot pump 27 as a primary pressure.
The rotation detector 50 measures the number of revolutions of the engine 22 and outputs information on the number of revolutions to the controller 51 as an electrical signal. The controller 51 converts the scale of the electrical signal received from the rotation detector 50 and outputs it to the solenoid valve 52. That is, the rotation detector 50, the controller 51, and the electromagnetic valve 52 function as a rotation speed signal generation unit that generates a command pressure PGR that is information related to the rotation speed of the engine 22.
　電磁弁５２で生成される指令圧ＰＧＲは、第１の実施の形態の圧力制御弁４５から出力される流量調節圧と同様に、エンジン回転数に比例した圧力として生成される。したがって、このようにして生成された指令圧ＰＧＲを流量調節弁４３の制御ポートに導入する第３の実施の形態の油圧回路は、第１の実施の形態と同様の作用効果を得ることができる。また、第３の実施の形態の油圧回路では、パイロットポンプ２７の吐出路に絞りを設ける必要がなく、パイロットポンプ２７から吐出される圧油のエネルギ損失を抑制することができる。 The command pressure PGR generated by the electromagnetic valve 52 is generated as a pressure proportional to the engine speed, similarly to the flow rate adjustment pressure output from the pressure control valve 45 of the first embodiment. Therefore, the hydraulic circuit of the third embodiment that introduces the command pressure PGR generated in this way into the control port of the flow rate control valve 43 can obtain the same operational effects as those of the first embodiment. . In the hydraulic circuit of the third embodiment, it is not necessary to provide a throttle in the discharge path of the pilot pump 27, and energy loss of the pressure oil discharged from the pilot pump 27 can be suppressed.
（第３の実施の形態の変形例）
　第３の実施の形態では、回転検出器５０が計測したエンジン２２の回転数に基づいた指令圧ＰＧＲを生成し、指令圧ＰＧＲを流量調節弁４３の制御ポートに入力した。しかし、流量調節弁４３がソレノイドを備え、コントローラ５１から出力される電気信号に基づき流量調節弁４３が動作するように構成してもよい。 (Modification of the third embodiment)
In the third embodiment, the command pressure PGR based on the rotation speed of the engine 22 measured by the rotation detector 50 is generated, and the command pressure PGR is input to the control port of the flow rate adjustment valve 43. However, the flow control valve 43 may include a solenoid, and the flow control valve 43 may be configured to operate based on an electrical signal output from the controller 51.
　図５は、第３の実施の形態の変形例における油圧回路２ｃ、および電気系統を示す図である。第３の実施の形態における油圧回路２ｂと比較すると、電磁弁５２が省略され、流量調節弁４３が電磁式流量調節弁４３ａに変更されている。
　流量調節弁４３ａの２つの制御ポートには、第１実施の形態と同様に、油圧ポンプ２３の吐出圧（メータイン絞り上流圧）とメータイン絞り下流圧が入力される。また、電磁式流量調節弁４３ａのソレノイド４３ｓには、コントローラ５１から出力されるエンジン回転数に比例する電気信号が印加され、ソレノイド４３ｓは、流量調節弁４３ａを位置Ａ側に切り換える電磁的な付勢力を与える。この電気信号による電磁的な付勢力は上記指令圧ＰＧＲと等価な信号である。したがって、流量調節弁４３ａは、油圧ポンプ２３の吐出圧（メータイン絞り上流圧）とメータイン絞り下流圧の差が、コントローラ５１から出力される電気信号に比例した圧力以下となるように、開度が制御される。よって、第３実施の形態の変形例においても、上記第１実施形態と同様の作用効果を奏することができる。 FIG. 5 is a diagram illustrating a hydraulic circuit 2c and an electric system in a modification of the third embodiment. Compared with the hydraulic circuit 2b in the third embodiment, the solenoid valve 52 is omitted and the flow rate control valve 43 is changed to an electromagnetic flow rate control valve 43a.
Similarly to the first embodiment, the discharge pressure (meter-in throttle upstream pressure) and the meter-in throttle downstream pressure of the hydraulic pump 23 are input to the two control ports of the flow control valve 43a. An electric signal proportional to the engine speed output from the controller 51 is applied to the solenoid 43s of the electromagnetic flow control valve 43a, and the solenoid 43s is an electromagnetic switch that switches the flow control valve 43a to the position A side. Give power. The electromagnetic urging force by this electric signal is a signal equivalent to the command pressure PGR. Therefore, the flow rate adjustment valve 43a has an opening degree so that the difference between the discharge pressure (meter-in throttle upstream pressure) of the hydraulic pump 23 and the meter-in throttle downstream pressure is equal to or less than the pressure proportional to the electrical signal output from the controller 51. Be controlled. Therefore, also in the modification of the third embodiment, the same operational effects as those of the first embodiment can be obtained.
　上述した各実施の形態および変形例は、それぞれ組み合わせてもよい。
　上記では、種々の実施の形態および変形例を説明したが、本発明はこれらの内容に限定されるものではない。本発明の技術的思想の範囲内で考えられるその他の態様も本発明の範囲内に含まれる。 The above-described embodiments and modifications may be combined.
Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other embodiments conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.
　　１　…　クレーン（作業機械）
　　２，２ａ、２ｂ　…　油圧回路
　２２　…　エンジン（原動機）
　２３　…　油圧ポンプ（可変容量油圧ポンプ）
　２４　…　旋回用油圧モータ（旋回モータ）
　２７　…　パイロットポンプ（固定容量油圧ポンプ）
　２９　…　回転数検出弁ユニット（回転数信号生成部）
　４１　…　旋回用制御弁（制御弁）
　４３、４３ａ　…　流量調節弁
　４３ｓ　…　ソレノイド（電磁駆動部）
　４４ａ　…　固定絞り（回転数信号生成部）
　４５　…　圧力制御弁
　５０　…　回転検出器（回転数信号生成部）
　５１　…　コントローラ（回転数信号生成部）
　５２　…　電磁弁（圧力生成部） 1 ... Crane (work machine)
2, 2a, 2b ... Hydraulic circuit 22 ... Engine (prime mover)
23… Hydraulic pump (variable displacement hydraulic pump)
24 ... Hydraulic motor for turning (turning motor)
27… Pilot pump (fixed capacity hydraulic pump)
29 ... Rotation speed detection valve unit (rotation speed signal generator)
41 ... Control valve for turning (control valve)
43, 43a ... Flow control valve 43s ... Solenoid (electromagnetic drive unit)
44a: Fixed aperture (rotation speed signal generator)
45 ... Pressure control valve 50 ... Rotation detector (Rotation speed signal generator)
51 ... Controller (rotation speed signal generator)
52… Solenoid valve (pressure generator)

Claims (6)

  1. 　操作指令に基づき回転数が決定される原動機と、
    　前記原動機により駆動される可変容量油圧ポンプと、
    　前記可変容量油圧ポンプからの吐出油で駆動される旋回モータと、
    　前記可変容量油圧ポンプから前記旋回モータへ供給される圧油を制御すると共に、初期位置において前記可変容量油圧ポンプからの吐出油をタンクに戻すよう制御するオープンセンタ型の制御弁とを備えた作業機械の油圧回路であって、
    　前記原動機の回転数を表す回転数信号を生成する回転数信号生成部と、
    　前記可変容量油圧ポンプから前記制御弁に導かれる圧油の流量を調節する流量調節弁と、を備え、
    　前記流量調節弁は、前記回転数信号生成部が出力する前記回転数信号に基づき、前記制御弁の前後差圧を前記原動機の回転数に応じた値とすることを特徴とする作業機械の油圧回路。     A prime mover whose rotation speed is determined based on an operation command;
    A variable displacement hydraulic pump driven by the prime mover;
    A swing motor driven by oil discharged from the variable displacement hydraulic pump;
    An operation provided with an open center type control valve that controls the pressure oil supplied from the variable displacement hydraulic pump to the swing motor and controls the discharge oil from the variable displacement hydraulic pump to return to the tank at an initial position. A hydraulic circuit of the machine,
    A rotational speed signal generating unit for generating a rotational speed signal representing the rotational speed of the prime mover;
    A flow rate adjusting valve that adjusts the flow rate of pressure oil led from the variable displacement hydraulic pump to the control valve,
    The flow rate adjusting valve sets the differential pressure across the control valve to a value corresponding to the rotational speed of the prime mover based on the rotational speed signal output from the rotational speed signal generation unit. circuit.
  2. 　請求項１に記載の作業機械の油圧回路において、　
    　前記流量調節弁は、油圧的な回転数信号である流量調節圧と、前記制御弁を通過する際のメータイン絞り前後差圧とにより駆動制御され、前記可変容量油圧ポンプが吐出する圧油の一部を前記制御弁以外の油路に分流することで前記メータイン絞り前後差圧を制御し、前記流量の上限値を設定することを特徴とする作業機械の油圧回路。     In the hydraulic circuit of the work machine according to claim 1,
    The flow rate adjusting valve is driven and controlled by a flow rate adjusting pressure that is a hydraulic rotation speed signal and a differential pressure before and after the meter-in throttle when passing through the control valve, and is one of the pressure oils discharged by the variable displacement hydraulic pump. A hydraulic circuit for a working machine, wherein the differential pressure before and after the meter-in throttling is controlled by dividing a part into an oil passage other than the control valve, and an upper limit value of the flow rate is set.
  3. 　請求項２に記載の作業機械の油圧回路において、
    　前記原動機により駆動される固定容量油圧ポンプをさらに備え、
    　前記回転数信号生成部は、前記固定容量油圧ポンプが吐出する圧油が導入されて前後差圧を生成する可変絞りと、前記固定容量油圧ポンプの吐出圧を前記前後差圧に応じた前記流量調節圧に変換する圧力制御弁とを含むことを特徴とする作業機械の油圧回路。     In the hydraulic circuit of the work machine according to claim 2,
    A fixed displacement hydraulic pump driven by the prime mover;
    The rotational speed signal generation unit includes a variable throttle that generates a front-rear differential pressure when pressure oil discharged from the fixed displacement hydraulic pump is introduced, and a discharge flow rate of the fixed displacement hydraulic pump according to the front-rear differential pressure. A hydraulic circuit for a work machine, comprising: a pressure control valve that converts the pressure into a regulated pressure.
  4. 　請求項２に記載の作業機械の油圧回路において、
    　前記原動機により駆動される固定容量油圧ポンプをさらに備え、
    　前記回転数信号生成部は、前記固定容量油圧ポンプが吐出する圧油が導かれる固定絞りを含み、前記固定絞りの上流側圧力を前記流量調節圧として前記流量調節弁に出力することを特徴とする作業機械の油圧回路。     In the hydraulic circuit of the work machine according to claim 2,
    A fixed displacement hydraulic pump driven by the prime mover;
    The rotation speed signal generation unit includes a fixed throttle to which pressure oil discharged from the fixed displacement hydraulic pump is guided, and outputs the upstream pressure of the fixed throttle to the flow rate adjustment valve as the flow rate adjustment pressure. The hydraulic circuit of the working machine that performs.
  5. 　請求項２に記載の作業機械の油圧回路において、
    　前記回転数信号生成部は、前記原動機の回転数を検出する回転数検出器と、前記回転数検出器が出力する前記回転数信号に比例する前記流量調節圧を生成する圧力生成部とを含むことを特徴とする作業機械の油圧回路。     In the hydraulic circuit of the work machine according to claim 2,
    The rotation speed signal generation unit includes a rotation speed detector that detects the rotation speed of the prime mover, and a pressure generation unit that generates the flow rate adjustment pressure proportional to the rotation speed signal output from the rotation speed detector. A hydraulic circuit of a work machine characterized by the above.
  6. 　請求項１に記載の作業機械の油圧回路において、
    　前記回転数信号生成部は、前記原動機の回転数を検出する回転数検出器と、前記流量調節弁に付設された電磁駆動部とを含み、前記電磁駆動部は、前記可変容量油圧ポンプから吐出される圧油が前記制御弁を通過する際のメータイン絞り前後差圧が前記原動機の回転数に応じた値となるように前記流量調節弁を駆動することを特徴とする作業機械の油圧回路。
    　
          In the hydraulic circuit of the work machine according to claim 1,
    The rotational speed signal generation unit includes a rotational speed detector that detects the rotational speed of the prime mover and an electromagnetic drive unit attached to the flow rate control valve, and the electromagnetic drive unit discharges from the variable displacement hydraulic pump. A hydraulic circuit for a working machine, wherein the flow control valve is driven so that a differential pressure before and after meter-in throttling when the pressurized oil passes through the control valve becomes a value corresponding to the rotational speed of the prime mover.

PCT/JP2017/003245 2016-02-25 2017-01-30 Work machine hydraulic circuit WO2017145658A1 (en)

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CN109292629A (en) * 2018-10-26 2019-02-01 中船华南船舶机械有限公司 A kind of crane Control in Hydraulic Rotation System

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Publication number Priority date Publication date Assignee Title
CN114084802A (en) * 2021-11-19 2022-02-25 徐州建机工程机械有限公司 Double-closed-loop master-slave synchronous control system for multiple mechanisms of tower crane

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JPH11158939A (en) * 1997-11-27 1999-06-15 Hitachi Constr Mach Co Ltd Hydraulic controller
JP2005265016A (en) * 2004-03-17 2005-09-29 Kobelco Contstruction Machinery Ltd Hydraulic control device for working machine

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JPH11158939A (en) * 1997-11-27 1999-06-15 Hitachi Constr Mach Co Ltd Hydraulic controller
JP2005265016A (en) * 2004-03-17 2005-09-29 Kobelco Contstruction Machinery Ltd Hydraulic control device for working machine

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109292629A (en) * 2018-10-26 2019-02-01 中船华南船舶机械有限公司 A kind of crane Control in Hydraulic Rotation System
CN109292629B (en) * 2018-10-26 2020-05-05 中船华南船舶机械有限公司 Hydraulic rotating system of crane

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