EP4717927A1 - Hydraulic drive device - Google Patents

Hydraulic drive device

Info

Publication number
EP4717927A1
EP4717927A1 EP24868198.3A EP24868198A EP4717927A1 EP 4717927 A1 EP4717927 A1 EP 4717927A1 EP 24868198 A EP24868198 A EP 24868198A EP 4717927 A1 EP4717927 A1 EP 4717927A1
Authority
EP
European Patent Office
Prior art keywords
hydraulic pump
control valve
hydraulic
flow control
actuator
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP24868198.3A
Other languages
German (de)
French (fr)
Inventor
Seiji Hijikata
Tsuyoshi Yamada
Sho FURUKAWA
Ryo YAGISAWA
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Construction Machinery Co Ltd
Original Assignee
Hitachi Construction Machinery Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Construction Machinery Co Ltd filed Critical Hitachi Construction Machinery Co Ltd
Publication of EP4717927A1 publication Critical patent/EP4717927A1/en
Pending legal-status Critical Current

Links

Classifications

    • 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
    • F15B11/028—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force
    • 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
    • E02F3/00—Dredgers; Soil-shifting machines
    • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
    • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
    • E02F3/30—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets with a dipper-arm pivoted on a cantilever beam, i.e. boom
    • 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
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • 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
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • E02F9/2225—Control of flow rate; Load sensing arrangements using pressure-compensating valves
    • E02F9/2228—Control of flow rate; Load sensing arrangements using pressure-compensating valves including an electronic controller
    • 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
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • E02F9/2232—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps
    • E02F9/2235—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps including an electronic controller
    • 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
    • F15B1/00—Installations or systems with accumulators; Supply reservoir or sump assemblies
    • F15B1/02—Installations or systems with accumulators
    • F15B1/027—Installations or systems with accumulators having accumulator charging devices
    • F15B1/033—Installations or systems with accumulators having accumulator charging devices with electrical control means
    • 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
    • F15B1/00—Installations or systems with accumulators; Supply reservoir or sump assemblies
    • F15B1/02—Installations or systems with accumulators
    • F15B1/04—Accumulators
    • 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
    • F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
    • F15B21/08—Servomotor systems incorporating electrically operated control means
    • F15B21/087—Control strategy, e.g. with block diagram
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/20507—Type of prime mover
    • F15B2211/20523—Internal combustion engine
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20546—Type of pump variable capacity
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/21—Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge
    • F15B2211/212—Systems with pressure sources other than pumps, e.g. with a pyrotechnical charge the pressure sources being accumulators
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/3056—Assemblies of multiple valves
    • F15B2211/30565—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3105—Neutral or centre positions
    • F15B2211/3116—Neutral or centre positions the pump port being open in the centre position, e.g. so-called open centre
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
    • F15B2211/31523—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source and an output member
    • F15B2211/31535—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source and an output member having multiple pressure sources and a single output member
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
    • F15B2211/3157—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line
    • F15B2211/31582—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line having multiple pressure sources and a single output member
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/327—Directional control characterised by the type of actuation electrically or electronically
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/415—Flow control characterised by the connections of the flow control means in the circuit
    • F15B2211/41554—Flow control characterised by the connections of the flow control means in the circuit being connected to a return line and a directional control valve
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/42—Flow control characterised by the type of actuation
    • F15B2211/426—Flow control characterised by the type of actuation electrically or electronically
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/45—Control of bleed-off flow, e.g. control of bypass flow to the return line
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6306—Electronic controllers using input signals representing a pressure
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6306—Electronic controllers using input signals representing a pressure
    • F15B2211/6309—Electronic controllers using input signals representing a pressure the pressure being a pressure source supply pressure
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6306—Electronic controllers using input signals representing a pressure
    • F15B2211/6313—Electronic controllers using input signals representing a pressure the pressure being a load pressure
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6346—Electronic controllers using input signals representing a state of input means, e.g. joystick position
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/665—Methods of control using electronic components
    • F15B2211/6651—Control of the prime mover, e.g. control of the output torque or rotational speed
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/665—Methods of control using electronic components
    • F15B2211/6652—Control of the pressure source, e.g. control of the swash plate angle
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/80—Other types of control related to particular problems or conditions
    • F15B2211/86—Control during or prevention of abnormal conditions
    • F15B2211/8606—Control during or prevention of abnormal conditions the abnormal condition being a shock

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Operation Control Of Excavators (AREA)

Abstract

The present invention aims to provide a hydraulic drive system capable of improving the operability of a hydraulic actuator by suppressing shock when switching from the state where the hydraulic pump accumulates in the accumulator to the state where the hydraulic pump drives the hydraulic actuator. Therefore, when the detection value of the first pressure sensor falls below a predetermined first threshold without an operation signal being input, the controller communicates the hydraulic pump to the accumulator while interrupting the hydraulic pump and hydraulic actuator and interrupting the hydraulic pump and tank. When an operation signal is input while pressure oil is being supplied from the hydraulic pump to the accumulator, the controller reduces the opening of the accumulator flow control valve and communicates the hydraulic pump to the tank while interrupting the hydraulic pump and the hydraulic actuator. Then, after a predetermined time has elapsed or after the pressure of the hydraulic pump has decreased, the controller communicates the hydraulic pump and the hydraulic actuator.

Description

    Technical Field
  • The present invention relates to a hydraulic drive system mounted on construction machinery such as hydraulic excavators.
    • Background Art
  • As prior art documents disclosing hydraulic drive systems mounted on construction machinery such as hydraulic excavators, there is, for example, patent document 1. The hydraulic drive system of patent document 1 includes a first hydraulic pump, a first hydraulic actuator driven by receiving pressure oil from the first hydraulic pump, a first pipe supplying pressure oil from the first hydraulic pump to the first hydraulic actuator, a first pump flow rate adjustment device installed in the first pipe to adjust the flow of pressure oil from the first hydraulic pump to the first hydraulic actuator, a first ion, and a first accumulator flow rate adjustment device to adjust the flow of pressure oil from the first hydraulic pump to the first accumulator. Furthermore, the hydraulic drive system includes a first accumulator flow rate supply device that supplies pressure oil stored in the first accumulator to the first hydraulic actuator via a second pipe separate from the first pipe. In this hydraulic drive system, the hydraulic actuator can be driven by the hydraulic pump or the accumulator, and the accumulator with reduced pressure can be charged (accumulated) by the hydraulic pump.
    • Prior Art Documents Patent Documents
  • [Patent document 1]
    WO 2018/061165
    • Summary of the Invention Problems to be Solved by the Invention
  • However, in the hydraulic drive system described in patent document 1, when switching from a state where the accumulator is accumulated by the hydraulic pump to a state where the hydraulic actuator is driven by the hydraulic pump, a large shock occurs due to the pressure difference between the hydraulic pump and the hydraulic actuator. Therefore, there is a concern that good operability desired by the operator cannot be ensured.
  • The present invention has been made in view of the above problems, and its purpose is to provide a hydraulic drive system capable of improving the operability of the hydraulic actuator by suppressing the shock when switching from a state where the accumulator is accumulated by the hydraulic pump to a state where the hydraulic actuator is driven by the hydraulic pump.
    • Means for Solving the Problems
  • To achieve the above purpose, the hydraulic drive system of the present invention includes a tank for storing hydraulic fluid, a hydraulic pump for sucking in and discharging hydraulic fluid from the tank, a hydraulic actuator, an actuator flow control valve for controlling a flow rate of pressure oil supplied from the hydraulic pump to the hydraulic actuator, a tank flow control valve for controlling a flow rate of pressure oil discharged from the hydraulic pump to the tank, an accumulator for accumulating pressure oil discharged from the hydraulic pump, an accumulator flow control valve for controlling a flow rate of pressure oil supplied from the hydraulic pump to the accumulator, a first pressure sensor for detecting a pressure of the accumulator, an operation device for operating the hydraulic actuator, and a controller that receives operation signals from the operation device and detection values from the first pressure sensor, and outputs control signals to the actuator flow control valve, the tank flow control valve, and the accumulator flow control valve. The controller is configured to, when a detection value of the first pressure sensor falls below a predetermined first threshold while no operation signal is input from the operation device, supply pressure oil from the hydraulic pump to the accumulator by communicating the hydraulic pump and the accumulator through the accumulator flow control valve while interrupting the hydraulic pump and the hydraulic actuator through the actuator flow control valve, and interrupting the hydraulic pump and the tank with the tank flow control valve. The controller is configured to, when an operation signal is input from the operation device while pressure oil is being supplied from the hydraulic pump to the accumulator, reduce the opening of the accumulator flow control valve while interrupting the hydraulic pump and the hydraulic actuator through the actuator flow control valve, and communicate the hydraulic pump and the tank through the tank flow control valve, and then, after a predetermined time has elapsed or after the pressure of the hydraulic pump has decreased, communicate the hydraulic pump and the hydraulic actuator through the actuator flow control valve.
    • Advantages of the Invention
  • According to the present invention, when an operation signal is input from the operation device while the accumulator is accumulated by the hydraulic pump, after a predetermined time has elapsed or after the pressure of the hydraulic pump has decreased, the hydraulic pump and the hydraulic actuator are communicated via the actuator flow control valve. Therefore, it is possible to prevent the hydraulic pump and the hydraulic actuator from being communicated via the actuator flow control valve when the pressure of the hydraulic pump greatly exceeds the pressure of the hydraulic actuator. As a result, the shock when switching from a state where the accumulator is accumulated by the hydraulic pump to a state where the hydraulic actuator is driven by the hydraulic pump is suppressed, making it possible to improve the operability of the hydraulic actuator.
    • Brief Description of the Drawings
    • [Fig. 1]
      FIG. 1 is a perspective view of a hydraulic excavator equipped with a hydraulic drive system according to the first embodiment of the present invention.
    • [Fig. 2]
      FIG. 2 is a hydraulic circuit diagram of the hydraulic drive system according to the first embodiment of the present invention.
    • [Fig. 3]
      FIG. 3 is a flowchart showing the processing of the controller related to the operation of each control valve in the first embodiment of the present invention.
    • [Fig. 4]
      FIG. 4 is a time chart comparing the operation of each control valve in the first embodiment of the present invention with the case where the control of this embodiment is not applied (prior art).
    • [Fig. 5]
      FIG. 5 is a modification example of the hydraulic circuit diagram of the hydraulic drive system in the first embodiment of the present invention.
    • [Fig. 6]
      FIG. 6 is a hydraulic circuit diagram of the hydraulic drive system according to the second embodiment of the present invention.
    • [Fig. 7]
      FIG. 7 is a flowchart showing the processing of the controller related to the operation of each control valve in the second embodiment of the present invention.
    Modes for Carrying Out the Invention
  • The embodiments of the present invention will be described below with reference to the drawings. In each figure, equivalent members are given the same reference numerals, and duplicate descriptions are omitted as appropriate.
    • [Embodiment 1]
  • Fig. 1 is a perspective view of a hydraulic excavator equipped with a hydraulic drive system according to the first embodiment of the present invention. The application of the hydraulic drive system according to the present invention is not limited to hydraulic excavators; it can also be applied to other construction machinery such as crawlers and wheel loaders.
  • In Fig. 1, the hydraulic excavator 100 includes a lower travel body 101, an upper swing body 102, and a working device 103. The upper swing body 102 is driven by a travel motor 104 (hydraulic actuator). The upper swing body 102 is rotatably installed on the lower travel body 101 and is driven by a swing motor (hydraulic actuator) not shown.
  • The working device 103 includes a boom 105, an arm 106, and a bucket 107. The boom 105 is rotatably supported by the upper swing body 102 and is driven by a boom cylinder 108 (hydraulic actuator). The arm 106 is rotatably supported by the boom 105 and is driven by an arm cylinder 109 (hydraulic actuator). The bucket 107 is rotatably supported by the arm 106 and is driven by a bucket cylinder 110 (hydraulic actuator).
  • Fig. 2 is a hydraulic circuit diagram of the hydraulic drive system mounted on the hydraulic excavator 100. In Fig. 2, only the part related to the driving of the boom cylinder 108 is shown, and the parts related to the driving of other actuators are omitted.
  • In Fig. 2, the hydraulic drive system 200 includes an engine 1 as a power source, a hydraulic pump 2 driven by the power of the engine 1, a boom cylinder 108 driven by the pressure oil supplied from the hydraulic pump 2, a center bypass type control valve 3 (actuator flow control valve) that controls the flow rate of pressure oil supplied from the hydraulic pump 2 to the boom cylinder 108 and the flow rate of pressure oil discharged from the boom cylinder 108 to the tank 8, an accumulator 5 that accumulates pressure oil discharged from the hydraulic pump 2, a control valve 6 (accumulator flow control valve) that controls the flow rate of pressure oil supplied from the hydraulic pump 2 to the accumulator 5, a control valve 7 that controls the flow rate of pressure oil supplied from the accumulator 5 to the boom cylinder 108 and the flow rate discharged from the boom cylinder 108 to the tank 8, a control valve 9 (tank flow control valve) that controls the flow rate of pressure oil discharged from the hydraulic pump 2 to the tank 8, a boom control lever 10 (operating device) that instructs the operation of the boom cylinder 108, a pressure sensor 11 (first pressure sensor) that detects the pressure of the accumulator 5, and a controller 12 that adjusts the discharge flow rate of the hydraulic pump 2, the speed of the engine 1, and the flow rate or opening of the control valves 3, 6, 7, 9 according to the operation amount of the boom control lever 10 and the detection value of the pressure sensor 11.
  • The discharge port of the hydraulic pump 2 is connected to the tank 8 via the center bypass passage 13. In the center bypass passage 13, control valves 3 and 9 are arranged in order from the upstream side. Control valve 3 is an open-center type flow control valve, and control valve 9 is a center bypass cut valve. Control valve 3 is connected to the boom cylinder 108 via actuator passages 14 and 15. The meter import of control valve 3 is connected to the center bypass passage 13 via check valve 16. The check valve 16 prevents the backflow of pressure oil from the boom cylinder 108 to the center bypass passage 13.
  • The controller 12 is equipped with a calculation device such as a CPU, storage devices such as ROM and RAM, and an input/output interface for signal input and output with external devices, and realizes the following functions by executing programs stored in ROM, etc. When a control signal is input from the boom control lever 10, the controller 12 increases the discharge flow rate of the hydraulic pump 2 according to the lever control amount and switches at least one of the control valves 3, 7 to a position corresponding to the lever control direction. As a result, pressure oil is supplied from the hydraulic pump 2 or the accumulator 5 to one side (bottom side or rod side) of the boom cylinder 108, while pressure oil is discharged from the other side (rod side or bottom side) of the boom cylinder 108 to the tank 8, causing the boom cylinder 108 to extend or compress. Additionally, when the pressure of the accumulator 5 (the detection value of the pressure sensor 11) decreases, the controller 12 communicates the hydraulic pump 2 and the accumulator 5 through the control valve 6, and accumulates the pressure oil discharged from the hydraulic pump 2 into the accumulator 5.
  • Fig. 3 is a flowchart illustrating the processing of controller 12 related to the operation of control valves 3, 6, and 9. The flow shown in Fig. 3 begins when a key switch, not shown in the diagram, is operated to the ON position. Additionally, the normal position of control valve 3 (the position when no control signal is input) is the neutral position (closed position), the normal position of control valve 6 is the closed position, and the normal position of control valve 9 is the open position.
  • First, in step S101, it is determined whether an operation signal has been input from the boom control lever 10. If the determination result of step S101 is Yes, hold control valve 9 in the open position, hold control valve 6 in the closed position, and adjust the opening degree of control valve 3 according to the signal from the boom control lever 10 (step S102). As a result, the pressure oil with a flow rate corresponding to the signal from the boom control lever 10 is supplied from the hydraulic pump 2 to one side (bottom side or rod side) of the boom cylinder 108 via the control valve 3. Then, the pressure oil of the surplus flow discharged from the hydraulic pump 2 is discharged to the tank 8 via the control valves 3, 9, and the pressure oil discharged from the other side (rod side or bottom side) of the boom cylinder 108 is discharged to the tank 8 via the control valve 3. After the completion of Step S102, return to Step S101.
  • If the determination result of step S101 is No, it is determined whether the detection value of pressure sensor 11 (pressure of accumulator 5) is below a predetermined threshold (first threshold) (step S103). If the determination result of step S103 is No, hold control valve 9 in the open position, control valve 6 in the closed position, and control valve 3 in the neutral position (step S104). As a result, when the pressure of the accumulator 5 is high, accumulation in the accumulator 5 is not performed, and the pressure oil discharged from the hydraulic pump 2 is discharged to the tank 8 via the control valves 3, 9, thereby preventing unnecessary pressure increase in the hydraulic pump 2. After the completion of step S104, return to step S101.
  • If the determination result of step S103 is Yes, control valve 3 is held in the neutral position, control valve 9 is switched to the closed position, and control valve 6 is switched to the open position (step S105). As a result, pressure oil discharged from hydraulic pump 2 is accumulated in accumulator 5.
  • Following step S105, it is determined whether an operation signal has been input from the boom control lever 10 (step S106). If the determination result of step S106 is No, return to step S103. As a result, in the state where no operation signal is input from the boom control lever 10, the pressure accumulation in the accumulator 5 continues until the pressure of the accumulator 5 reaches the first threshold.
  • If the determination result of step S106 is Yes, hold the control valve 3 in the neutral position, switch the control valve 6 to the closed position, and switch the control valve 9 to the open position (step S107). As a result, the accumulation to the accumulator 5 is stopped, and the pressure oil discharged from the hydraulic pump 2 is discharged to the tank 8 via the control valves 3 and 9, causing the pressure of the hydraulic pump 2 to decrease. It is not necessarily required to fully close the control valve 6 in step S107; it is sufficient to reduce (decrease) it to an opening that is significantly smaller than the opening of control valve 9.
  • Following step S107, wait for a predetermined time (step S108), and proceed to step S102. As a result, after the pressure of the hydraulic pump 2 decreases, the hydraulic pump 2 and the boom cylinder 108 communicate via the control valve 3, thereby suppressing the shock at the start of driving the boom cylinder 108. The predetermined time referred to here is the time from when the control signal is output to switch the control valve 9 to the open position until the control valve 9 actually switches to the open position. For example, the predetermined time is determined experimentally using an actual machine, and it is considered to be approximately the same as the response time of a typical solenoid valve (around 100 msec).
  • Fig. 4 is a time chart showing the operation of control valves 3, 6, and 9 in this embodiment compared to the case where the control of this embodiment is not applied (prior art). In the prior art, at time t1, the control valve 6 is switched to the open position to accumulate pressure in the accumulator 5. At time t2, an operation signal is input from the boom control lever 10, and immediately thereafter, the control valve 3 is switched to the open position. As a result, the hydraulic pump 2 and the boom cylinder 108 are in communication in a state where the pressure of the hydraulic pump 2 (pump pressure) significantly exceeds the pressure of the boom cylinder 108 (cylinder pressure), causing the cylinder pressure to rise momentarily (between time t2 and time t3), which results in a shock. On the other hand, in this embodiment, control valve 3 is not switched to the open position between time t2 and t3 (the predetermined time of step S108), and it is switched to the open position at time t3 after the pump pressure has decreased, so the cylinder pressure does not rise and no shock occurs.
    • [Summary]
  • The hydraulic drive system 200 of the first embodiment includes a tank 8 for storing hydraulic fluid, a hydraulic pump 2 for sucking in and discharging hydraulic fluid from the tank 8, a hydraulic actuator 108, an actuator flow control valve 3 for controlling the flow rate of pressure oil supplied from the hydraulic pump 2 to the hydraulic actuator 108, a tank flow control valve 9 for controlling the flow rate of pressure oil discharged from the hydraulic pump 2 to the tank 8, an accumulator 5 for accumulating pressure oil discharged from the hydraulic pump 2, an accumulator flow control valve 6 for controlling the flow rate of pressure oil supplied from the hydraulic pump 2 to the accumulator 5, a first pressure sensor 11 for detecting the pressure of the accumulator 5, an operation device 10 for operating the hydraulic actuator 108, and a controller 12 that receives operation signals from the operation device 10 and detection values from the first pressure sensor 11, and outputs control signals to the actuator flow control valve 3, the tank flow control valve 9, and the accumulator flow control valve 6. The controller 12, when the detection value of the first pressure sensor 11 falls below a predetermined first threshold without an operation signal being input from the operation device 10, communicates the hydraulic pump 2 to the accumulator 5 through the accumulator flow control valve 6, while interrupting the hydraulic pump 2 from the hydraulic actuator 108 through the actuator flow control valve 3, and interrupting the hydraulic pump 2 from the tank 8 through the tank flow control valve 9. Thus, when an operation signal is input from the operation device 10 while pressure oil is being supplied from the hydraulic pump 2 to the accumulator 5, the opening of the accumulator flow control valve 6 is reduced while interrupting the hydraulic pump 2 and the hydraulic actuator 108 with the actuator flow control valve 3, and the hydraulic pump 2 and the tank 8 communicate with the tank flow control valve 9. Then, after a predetermined time has elapsed or after the pressure of the hydraulic pump 2 has decreased, the hydraulic pump 2 and the hydraulic actuator 108 communicate with the actuator flow control valve 3.
  • According to the first embodiment configured as described above, when an operation signal is input from the operation device 10 while being accumulated in the accumulator 5 by the hydraulic pump 2, the hydraulic pump 2 and the hydraulic actuator 108 communicate via the actuator flow control valve 3 after a predetermined time has elapsed or after the pressure of the hydraulic pump 2 has decreased. Therefore, it is possible to prevent the hydraulic pump and the hydraulic actuator 108 from communicating via the actuator flow control valve 3 when the pressure of the hydraulic pump 2 greatly exceeds the pressure of the hydraulic actuator 108. As a result, the shock that occurs when switching from the state where the accumulator 5 is accumulated by the hydraulic pump 2 to the state where the hydraulic actuator 108 is driven by the hydraulic pump 2 is suppressed, thereby improving the operability of the hydraulic actuator 108.
  • In the first embodiment, the actuator flow control valve 3 is an open-center type flow control valve installed in the center bypass passage 13, and the tank flow control valve 9 is a center bypass cut valve installed in the center bypass passage 13. Thus, in the hydraulic drive system 200 with an open-center type hydraulic circuit configuration, the shock that occurs when switching from the state where the accumulator 5 is accumulated by the hydraulic pump 2 to the state where the hydraulic actuator 108 is driven by the hydraulic pump 2 is suppressed, thereby improving the operability of the hydraulic actuator 108. It should be noted that the actuator flow control valve is not limited to the open-center type flow control valve 3, and may be a closed-center type flow control valve 3A as shown in the modification example of Fig. 5. In that case, the bleed-off valve 9A, which discharges the excess flow of the hydraulic pump 2 to the tank 8, corresponds to the tank flow control valve.
    • [Embodiment 2]
  • The second embodiment of the present invention will be described focusing on the differences from the first embodiment.
  • FIG. 6 is a hydraulic circuit diagram of the hydraulic drive system 200 in this embodiment. At the upstream end of the center bypass passage 13, a pressure sensor 17 (second pressure sensor) for detecting the pressure of the hydraulic pump 2 is installed. In the actuator passage 14 connecting the control valve 3 and the bottom side of the boom cylinder 108, a pressure sensor 18 (third pressure sensor) for detecting the bottom side pressure of the boom cylinder 108 is installed. The detection values of pressure sensors 17 and 18 are input to the controller 12.
  • FIG. 7 is a flowchart showing the processing of the controller 12 in this embodiment. In FIG. 7, the difference from the first embodiment (shown in FIG. 4) is that step S108A is executed instead of step S108.
  • In step S108A, it is determined whether the value obtained by subtracting the detection value of pressure sensor 18 (bottom side pressure of boom cylinder 108) from the detection value of pressure sensor 17 (pressure of hydraulic pump 2) is less than a predetermined threshold (second threshold). The second threshold is a value indicating the extent to which the pressure of hydraulic pump 2 exceeds the bottom side pressure of boom cylinder 108 without causing shock, and it is determined, for example, through trial and error using an actual machine. If the determination result of step S108A is No, it returns to step S107, and if the determination result of step S108A is Yes, it proceeds to step S102. This allows the hydraulic pump 2 and the boom cylinder 108 to communicate via the control valve 3 when the pressure of the hydraulic pump 2 drops to near the bottom side pressure of the boom cylinder 108, thereby suppressing the response delay of the boom cylinder 108.
    • [Summary]
  • In the second embodiment, the hydraulic drive system 200 includes a second pressure sensor 17 for detecting the pressure of the hydraulic pump 2 and a third pressure sensor 18 for detecting the pressure of the hydraulic actuator 108. The controller 12, when an operation signal is input from the operation device 10 while pressure oil is being supplied from the hydraulic pump 2 to the accumulator 5, reduces the opening of the accumulator flow control valve 6 and communicates the hydraulic pump 2 to the tank through the tank flow control valve 9, while interrupting the hydraulic pump 2 and the hydraulic actuator 108 with the actuator flow control valve 3. Then, after the value obtained by subtracting the detection value of the second pressure sensor 17 from the detection value of the third pressure sensor 18 becomes less than the predetermined second threshold, the actuator flow control valve 3 communicates the hydraulic pump 2 with the hydraulic actuator 108.
  • In the second embodiment configured as described above, as in the first embodiment, the shock when switching from the state where the hydraulic pump 2 accumulates in the accumulator 5 to the state where the hydraulic pump 2 drives the hydraulic actuator 108 is suppressed, thereby improving the operability of the hydraulic actuator 108. Furthermore, since the hydraulic pump 2 and the hydraulic actuator 108 communicate via the actuator flow control valve 3 when the pressure of the hydraulic pump 2 drops to near the pressure of the hydraulic actuator 108, it is possible to suppress the response delay of the hydraulic actuator 108.
  • It should be noted that the present invention is not limited to the embodiments described above and includes various modifications. For example, the embodiments described above are shown to explain the present invention clearly and are not necessarily limited to all the configurations described. Furthermore, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Additionally, it is possible to add, delete, or replace other configurations for some parts of the configuration of each embodiment.
    • Description of Reference Characters
  • 1: Engine, 2: Hydraulic pump, 3: Control valve (flow control valve, actuator flow control valve), 3A: Flow control valve (actuator flow control valve), 5: Accumulator, 6: Control valve (accumulator flow control valve), 7: Control valve, 8: Tank, 9: Control valve (center bypass cut valve, tank flow control valve), 9A: Bleed-off valve (tank flow control valve), 10: Boom control lever (operation device), 11: Pressure sensor (first pressure sensor), 12: Controller, 13: Center bypass flow path, 14, 15: Actuator flow path, 16: Check valve, 17: Pressure sensor (second pressure sensor), 18: Pressure sensor (third pressure sensor), 100: Hydraulic excavator, 101: Lower travel body, 102: Upper swing body, 103: Working device, 104: Travel motor (hydraulic actuator), 105: Boom, 106: Arm, 107: Bucket, 108: Boom cylinder (hydraulic actuator), 109: Arm cylinder (hydraulic actuator), 110: Bucket cylinder (hydraulic actuator), 200: Hydraulic drive system

Claims (3)

  1. A hydraulic drive system comprising:
    a tank for storing hydraulic fluid;
    a hydraulic pump for sucking in and discharging hydraulic fluid from the tank;
    a hydraulic actuator;
    an actuator flow control valve for controlling a flow rate of pressure oil supplied from the hydraulic pump to the hydraulic actuator;
    a tank flow control valve for controlling a flow rate of pressure oil discharged from the hydraulic pump to the tank;
    an accumulator for accumulating pressure oil discharged from the hydraulic pump;
    an accumulator flow control valve for controlling a flow rate of pressure oil supplied from the hydraulic pump to the accumulator;
    a first pressure sensor for detecting a pressure of the accumulator;
    an operation device for operating the hydraulic actuator; and
    a controller that receives operation signals from the operation device and detection values from the first pressure sensor, and outputs control signals to the actuator flow control valve, the tank flow control valve, and the accumulator flow control valve, wherein
    the controller is configured to,
    when a detection value of the first pressure sensor falls below a predetermined first threshold in a state where no operation signal is input from the operation device, supply pressure oil from the hydraulic pump to the accumulator by communicating the hydraulic pump and the accumulator through the accumulator flow control valve, while interrupting the hydraulic pump and the hydraulic actuator with the actuator flow control valve, and interrupting the hydraulic pump and the tank with the tank flow control valve;
    when an operation signal is input from the operation device while pressure oil is being supplied from the hydraulic pump to the accumulator, reduce the opening of the accumulator flow control valve while interrupting the hydraulic pump and the hydraulic actuator with the actuator flow control valve, and communicate the hydraulic pump and the tank with the tank flow control valve, and
    then, after a predetermined time has elapsed or after the pressure of the hydraulic pump has decreased, communicate the hydraulic pump and the hydraulic actuator with the actuator flow control valve.
  2. The hydraulic drive system according to claim 1, comprising:
    a second pressure sensor for detecting a pressure of the hydraulic pump; and
    a third pressure sensor for detecting a pressure of the hydraulic actuator,
    wherein the controller is configured to,
    when an operation signal is input from the operation device while pressure oil is being supplied from the hydraulic pump to the accumulator, reduce the opening of the accumulator flow control valve while interrupting the hydraulic pump and the hydraulic actuator with the actuator flow control valve, and communicate the hydraulic pump and the tank with the tank flow control valve, and
    then, after the value obtained by subtracting the detection value of the second pressure sensor from the detection value of the third pressure sensor falls below a predetermined second threshold, communicate the hydraulic pump and the hydraulic actuator with the actuator flow control valve.
  3. The hydraulic drive system according to claim 1, wherein
    the actuator flow control valve is an open-center type flow control valve installed in a center bypass flow path, and
    the tank flow control valve is a center bypass cut valve installed in the center bypass flow path.
EP24868198.3A 2023-09-20 2024-09-12 Hydraulic drive device Pending EP4717927A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2023153920 2023-09-20
PCT/JP2024/032642 WO2025063121A1 (en) 2023-09-20 2024-09-12 Hydraulic drive device

Publications (1)

Publication Number Publication Date
EP4717927A1 true EP4717927A1 (en) 2026-04-01

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ID=95072859

Family Applications (1)

Application Number Title Priority Date Filing Date
EP24868198.3A Pending EP4717927A1 (en) 2023-09-20 2024-09-12 Hydraulic drive device

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Country Link
EP (1) EP4717927A1 (en)
JP (1) JPWO2025063121A1 (en)
KR (1) KR20260013966A (en)
CN (1) CN121399379A (en)
WO (1) WO2025063121A1 (en)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9091039B2 (en) * 2012-03-02 2015-07-28 Deere & Company Ride control system
JP6285787B2 (en) * 2014-04-14 2018-02-28 日立建機株式会社 Hydraulic drive
JP6317656B2 (en) * 2014-10-02 2018-04-25 日立建機株式会社 Hydraulic drive system for work machines
CN108138818B (en) * 2016-09-29 2020-06-23 日立建机株式会社 Hydraulic drive device

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WO2025063121A1 (en) 2025-03-27
CN121399379A (en) 2026-01-23
JPWO2025063121A1 (en) 2025-03-27

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