WO2024071261A1 - 作業機械 - Google Patents

作業機械 Download PDF

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Publication number
WO2024071261A1
WO2024071261A1 PCT/JP2023/035296 JP2023035296W WO2024071261A1 WO 2024071261 A1 WO2024071261 A1 WO 2024071261A1 JP 2023035296 W JP2023035296 W JP 2023035296W WO 2024071261 A1 WO2024071261 A1 WO 2024071261A1
Authority
WO
WIPO (PCT)
Prior art keywords
pressure
valve
opening area
pilot
hydraulic
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.)
Ceased
Application number
PCT/JP2023/035296
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
征勲 茅根
充彦 金濱
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
Priority to JP2024550427A priority Critical patent/JP7788568B2/ja
Priority to KR1020257003733A priority patent/KR20250047736A/ko
Priority to CN202380058168.5A priority patent/CN119654494B/zh
Priority to EP23872483.5A priority patent/EP4549747A1/en
Publication of WO2024071261A1 publication Critical patent/WO2024071261A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • 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
    • F15B11/08—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2217—Hydraulic or pneumatic drives with energy recovery arrangements, e.g. using accumulators, flywheels
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • 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
    • E02F9/2278—Hydraulic circuits
    • E02F9/2282—Systems using center bypass type changeover valves
    • 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
    • E02F9/2278—Hydraulic circuits
    • E02F9/2296—Systems with a variable displacement pump
    • 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
    • F15B11/044—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the return line, i.e. "meter out"
    • 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
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • 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
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/20—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors controlling several interacting or sequentially-operating members
    • 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
    • E02F3/36—Component parts
    • E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
    • E02F3/43—Control of dipper or bucket position; Control of sequence of drive operations
    • E02F3/435—Control of dipper or bucket position; Control of sequence of drive operations for dipper-arms, backhoes or the like
    • 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
    • F15B2211/30505—Non-return valves, i.e. check valves
    • 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
    • F15B2211/30525—Directional control valves, e.g. 4/3-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
    • F15B2211/30—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
    • F15B2211/3058—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 having additional valves for interconnecting the fluid chambers of a double-acting actuator, e.g. for regeneration mode or for floating mode
    • 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
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3144—Directional control characterised by the positions of the valve element the positions being continuously variable, e.g. as realised by proportional valves
    • 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
    • F15B2211/329—Directional control characterised by the type of actuation actuated by fluid 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
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
    • 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
    • F15B2211/41—Flow control characterised by the positions of the valve element
    • F15B2211/413—Flow control characterised by the positions of the valve element the positions being continuously variable, e.g. as realised by proportional valves
    • 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
    • F15B2211/428—Flow control characterised by the type of actuation actuated by fluid 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
    • F15B2211/40—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
    • F15B2211/40—Flow control
    • F15B2211/46—Control of flow in the return line, i.e. meter-out control
    • 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
    • F15B2211/625—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
    • F15B2211/60—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
    • F15B2211/635—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements
    • F15B2211/6355—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements having valve 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders

Definitions

  • the present invention relates to a work machine.
  • a work machine includes a main circuit that controls hydraulic oil discharged from a hydraulic pump by a cylinder control valve and supplies it to a hydraulic cylinder, and a pilot circuit that reduces the pressure of a portion of the hydraulic oil discharged from the hydraulic pump by a pilot pressure reducing valve and supplies it to an electromagnetic proportional pressure reducing valve as pilot primary pressure, and directs secondary pressure generated by the electromagnetic proportional pressure reducing valve to the cylinder control valve (see Patent Document 1).
  • the work machine described in Patent Document 1 is provided with a bypass sequence valve in a bypass passage that connects the hydraulic pump and the tank.
  • the bypass sequence valve is controlled to a connected state when there is no manual operation signal from the operating device, and is controlled so that the pressure at the inlet of the bypass sequence valve (i.e., the discharge pressure of the hydraulic pump) is equal to or higher than the pilot primary pressure when there is a manual operation signal from the operating device.
  • the discharge pressure of the hydraulic pump drops.
  • the bypass sequence valve is controlled so that the discharge pressure of the hydraulic pump is equal to or higher than the pilot primary pressure.
  • the present invention aims to provide a work machine that can ensure stable pilot primary pressure when an operation is performed to operate a work device in the direction of gravity.
  • a working machine includes a working device having a plurality of hydraulic cylinders and a plurality of driven members driven by the plurality of hydraulic cylinders, an operating device for operating the hydraulic cylinders, a main circuit for supplying hydraulic oil discharged from a hydraulic pump to the hydraulic cylinders, a cylinder control valve provided in the main circuit for controlling the flow of hydraulic oil supplied from the hydraulic pump to the hydraulic cylinders, a pilot circuit for directing a portion of the hydraulic oil discharged from the hydraulic pump to a pilot pressure receiving portion of the cylinder control valve, a first pressure reducing valve provided in the pilot circuit for reducing the pressure of the hydraulic oil discharged from the hydraulic pump to generate a pilot primary pressure, a second pressure reducing valve provided in the pilot circuit for reducing the pilot primary pressure to generate a pilot secondary pressure acting on the pilot pressure receiving portion of the cylinder control valve, and a hydraulic pump connected to a tank, and the hydraulic cylinder pressure reducing device includes a center bypass passage in which a cylinder control valve is provided,
  • the control device controls the third pressure reducing valve based on the pressure detected by the pressure sensor, and when the pressure detected by the pressure sensor becomes low, the control device controls the third pressure reducing valve so that the opening area of the bypass cut valve becomes smaller, and the opening area of the meter-out throttle is reduced as the amount of operation of the operation device to operate the working device in the gravity direction becomes larger.
  • FIG. 1 is a side view of a hydraulic excavator according to a first embodiment of the present invention.
  • FIG. 2 is a diagram showing a hydraulic system mounted on the hydraulic excavator according to the first embodiment of the present invention.
  • FIG. 3 is a flowchart showing an example of a flow of valve control processing executed by the main controller according to the first embodiment of the present invention.
  • FIG. 4 is a diagram showing time series changes in the operating position of the gate lock lever device, the boom lowering operation amount of the boom operating device, the discharge pressure of the hydraulic pump, the discharge capacity of the hydraulic pump, the opening area of the bypass cut valve, and the opening area of the meter-out throttle of the CT opening control valve.
  • FIG. 5 is a functional block diagram of a main controller according to a second embodiment of the present invention, showing functions related to control of the bypass cut valve.
  • FIG. 6 is a diagram showing a hydraulic system according to a modified embodiment of the present invention.
  • a work machine according to an embodiment of the present invention will be described with reference to the drawings.
  • the work machine is a crawler-type hydraulic excavator.
  • First Embodiment Fig. 1 is a side view of a hydraulic excavator 1 according to a first embodiment of the present invention.
  • the front-rear and up-down directions of the hydraulic excavator 1 are defined as shown in Fig. 1.
  • the front of the driver's seat (the left direction in the figure) is the front of the hydraulic excavator 1.
  • the hydraulic excavator 1 comprises a machine body (vehicle body) 20 and a work device 10 attached to the machine body 20.
  • the machine body 20 comprises a running body 2 and a rotating body 3 mounted on the running body 2 so as to be capable of rotating.
  • the running body 2 has a pair of left and right crawlers and a traveling hydraulic motor 2a which is an actuator.
  • the running body 2 runs by driving the crawlers with the traveling hydraulic motor 2a.
  • the rotating body 3 has a rotating frame 30, a rotating hydraulic motor 3a which is an actuator, and a speed reduction mechanism which reduces the rotation of the rotating hydraulic motor 3a and transmits it to the rotating frame 30.
  • the rotating body 3 rotates relative to the running body 2 by the rotating hydraulic motor 3a.
  • the rotating body 3 has a cab 31 provided on the front left side of the rotating frame 30, a counterweight 32 provided at the rear of the rotating frame 30, and an engine room 33 provided on the rotating frame 30 behind the cab 31.
  • the engine room 33 houses an engine, which is the prime mover, and hydraulic equipment such as a hydraulic pump, valves, and accumulators.
  • the work device 10 is rotatably connected to the center of the front of the rotating frame 30.
  • the working device 10 is a multi-joint working device having a number of driven members that are rotatably connected and a number of hydraulic cylinders that drive the driven members.
  • the three driven members, a boom 11, an arm 12, and a bucket 13, are connected in series.
  • the base end of the boom 11 is rotatably connected to the front of the rotating frame 30.
  • the base end of the arm 12 is rotatably connected to the tip of the boom 11.
  • the bucket 13 is rotatably connected to the tip of the arm 12.
  • the boom 11 is driven by a hydraulic cylinder (hereinafter also referred to as boom cylinder 11a) which is an actuator, and rotates relative to the revolving frame 30.
  • the arm 12 is driven by a hydraulic cylinder (hereinafter also referred to as arm cylinder 12a) which is an actuator, and rotates relative to the boom 11.
  • the bucket 13 is driven by a hydraulic cylinder (hereinafter also referred to as bucket cylinder 13a) which is an actuator, and rotates relative to the arm 12.
  • FIG. 2 is a diagram showing a hydraulic system 90 mounted on the hydraulic excavator 1.
  • the hydraulic system 90 is provided with hydraulic equipment for driving multiple hydraulic actuators (2a, 3a, 11a, 12a, 13a).
  • FIG. 2 only shows the hydraulic equipment for driving the boom cylinder 11a and arm cylinder 12a, and does not show the hydraulic equipment for driving the other hydraulic actuators (2a, 3a, 13a).
  • multiple hydraulic pumps 81 are often used to drive the actuators, but the following explanation will be given taking as an example a case where only one hydraulic pump 81 is used to drive the actuators.
  • FIG. 2 also illustrates a main controller 100, which is a control device that controls the hydraulic system 90, and a device that outputs signals to the main controller 100.
  • the hydraulic excavator 1 is equipped with an engine control dial 21 for setting a target rotation speed of the engine 80, an operating device (also written as a boom operating device) 23 for operating the boom cylinder 11a (boom 11), an operating device (also written as an arm operating device) 24 for operating the arm cylinder 12a (arm 12), and a gate lock lever device 22.
  • These devices (21 to 24) are provided inside the operator's cab 31.
  • the boom operation device 23 has an operation lever 23a that can be tilted from a neutral position to the boom-raising side and the boom-lowering side, and an operation sensor that detects the operation direction and amount of operation of the operation lever 23a and outputs an operation signal indicating the operation direction and amount of operation of the operation lever 23a to the main controller 100.
  • the arm operation device 24 has an operation lever 24a that can be tilted from a neutral position to the arm crowding side and the arm dumping side, and an operation sensor that detects the operation direction and amount of operation of the operation lever 24a and outputs an operation signal indicating the operation direction and amount of operation of the operation lever 24a to the main controller 100.
  • the operation amount (operation angle) of the operation levers 23a, 24a detected by the operation sensor of the operation devices 23, 24 is 0% (0°) when in the neutral position, and the absolute value increases the more it is tilted from the neutral position.
  • the gate lock lever device 22 has a lever 22a that is selectively operated to a locked position (upper position) that permits entry and exit of the cab 31 and prohibits the operation of the actuators (11a, 12a, 13a), and an unlocked position (lower position) that prohibits entry and exit of the cab 31 and permits the operation of the actuators (11a, 12a, 13a).
  • the gate lock lever device 22 also has an operation position sensor that detects the operation position of the lever 22a and outputs a gate lock lever signal indicative of the operation position of the lever 22a to the main controller 100.
  • the engine control dial 21 is an operating device for setting the target rotation speed of the engine 80, and outputs an operating signal to the main controller 100.
  • the main controller 100 determines the target rotation speed based on the operating signal from the engine control dial 21, and outputs a signal of the determined target rotation speed to the engine controller 105.
  • the engine 80 is provided with a rotation speed sensor 80a that detects the actual rotation speed of the engine 80, and a fuel injection device 80b that adjusts the amount of fuel injected into the cylinder of the engine 80.
  • the engine controller 105 controls the fuel injection device 80b so that the actual rotation speed of the engine 80 detected by the rotation speed sensor 80a becomes the target rotation speed output from the main controller 100.
  • the hydraulic system 90 includes a hydraulic pump 81, a main circuit HC1 that supplies hydraulic oil as a working fluid discharged from the hydraulic pump 81 to the boom cylinder 11a and the arm cylinder 12a, a pilot circuit HC2 that is connected to the main circuit HC1, and a center bypass passage Lb that connects the hydraulic pump 81 to a tank 19 in which the hydraulic oil is stored.
  • the pilot circuit HC2 is a circuit that guides a portion of the hydraulic oil discharged from the hydraulic pump 81 to pilot pressure receiving portions 45a, 45b, 46a, 46b of cylinder control valves 45, 46 described later, pilot pressure receiving portion 17a of bypass cut valve 17 described later, and pilot pressure receiving portions of CT opening control valves 26A, 26B described later.
  • the hydraulic pump 81 is connected to the engine 80 and driven by the engine 80 to suck in and discharge hydraulic oil from the tank 19.
  • the hydraulic pump 81 is a variable displacement piston-type hydraulic pump, and its discharge capacity (displacement volume) changes when the tilt angle of the swash plate is changed by the regulator 81a.
  • the regulator 81a has a tilt actuator that controls the tilt angle of the swash plate of the hydraulic pump 81, and an electromagnetic proportional valve that generates a control pressure for the tilt actuator using the discharge pressure of the hydraulic pump 81 as the base pressure.
  • the engine 80 is the power source of the hydraulic excavator 1, and is composed of an internal combustion engine such as a diesel engine, for example.
  • the main circuit HC1 is provided with a cylinder control valve (hereinafter also referred to as the boom control valve) 45 that controls the flow (flow rate and direction) of hydraulic oil supplied from the hydraulic pump 81 to the boom cylinder 11a, and a cylinder control valve (hereinafter also referred to as the arm control valve) 46 that controls the flow (flow rate and direction) of hydraulic oil supplied from the hydraulic pump 81 to the arm cylinder 12a.
  • a cylinder control valve hereinafter also referred to as the boom control valve
  • the arm control valve cylinder control valve
  • the main circuit HC1 is provided with a relief valve 47 that determines the maximum pressure of the hydraulic pump 81 discharge pressure by discharging the hydraulic oil discharged from the hydraulic pump 81 into the tank 19 when the discharge pressure (circuit pressure) of the hydraulic pump 81 exceeds a preset pressure.
  • the main circuit HC1 has a pump discharge passage Ld connected to the discharge port of the hydraulic pump 81, and a parallel passage Lp connected to the pump discharge passage Ld.
  • the parallel passage Lp is a passage that guides hydraulic oil from the pump discharge passage Ld to the pump ports of the boom control valve 45 and the arm control valve 46.
  • the parallel passage Lp constitutes part of a meter-in passage that guides hydraulic oil discharged from the hydraulic pump 81 to the hydraulic cylinder.
  • a check valve 41 is provided in the parallel passage Lp that is connected to the pump port of the boom control valve 45 to maintain the load pressure of the boom cylinder 11a. The check valve 41 is fully closed when the pump discharge pressure falls below the cylinder pressure.
  • a check valve 42 is provided in the parallel passage Lp that is connected to the pump port of the arm control valve 46 to maintain the load pressure of the arm cylinder 12a. The check valve 42 is fully closed when the pump discharge pressure falls below the cylinder pressure.
  • the tank port of the boom control valve 45 is connected to the tank 19 via a return oil passage 45r.
  • the return oil passage 45r constitutes a part of a meter-out passage that guides return oil from the boom cylinder 11a to the tank 19.
  • a CT opening control valve (meter-out control valve) 26A is provided in the return oil passage 45r.
  • the CT opening control valve 26A has a meter-out throttle 28A that imparts resistance to the flow of hydraulic oil passing through it, and discharges the return oil from the boom cylinder 11a to the tank 19 through the meter-out throttle 28A.
  • the CT opening control valve 26A operates according to the pilot secondary pressure output from the solenoid valve 35A described later, and the opening area (opening degree) of the meter-out throttle 28A changes.
  • the return oil passage (meter-out passage) 45r of the boom control valve 45 and the parallel passage (meter-in passage) Lp are connected by a regeneration passage in which a regeneration check valve 27A is provided.
  • the check valve 27A is a check valve that allows hydraulic oil to flow from the return oil passage 45r to the parallel passage Lp and prohibits hydraulic oil from flowing from the parallel passage Lp to the return oil passage 45r.
  • the regeneration check valve 27A opens when the bottom pressure exceeds the rod pressure.
  • a portion of the return oil from the bottom chamber is regenerated and supplied to the rod chamber through the check valve 27A, while the remainder is returned to the tank 19 through the meter-out throttle 28A of the CT opening control valve 26A.
  • a similar regeneration passage is provided in the arm control valve 46.
  • the tank port of the arm control valve 46 is connected to the tank 19 via a return oil passage 46r.
  • the return oil passage 46r constitutes a part of a meter-out passage that guides return oil from the arm cylinder 12a to the tank 19.
  • a CT opening control valve (meter-out control valve) 26B is provided in the return oil passage 46r.
  • the CT opening control valve 26B has a meter-out throttle 28B that imparts resistance to the flow of hydraulic oil passing through it, and discharges return oil from the arm cylinder 12a to the tank 19 through the meter-out throttle 28B.
  • the CT opening control valve 26B operates according to the pilot secondary pressure output from the solenoid valve 35B described later, and the opening area (opening degree) of the meter-out throttle 28B changes.
  • the return oil passage (meter-out passage) 46r and the parallel passage (meter-in passage) Lp of the arm control valve 46 are connected by a regeneration passage provided with a regeneration check valve 27B.
  • the check valve 27B is a check valve that allows hydraulic oil to flow from the return oil passage 46r to the parallel passage Lp and prohibits hydraulic oil from flowing from the parallel passage Lp to the return oil passage 46r.
  • the regeneration check valve 27B opens when the bottom pressure exceeds the rod pressure as the arm cylinder 12a contracts. As a result, a portion of the return oil from the bottom chamber is regenerated and supplied to the rod chamber through the check valve 27B, and the remainder is returned to the tank 19 through the meter-out throttle 28B of the CT opening control valve 26B. When the rod pressure exceeds the bottom pressure, the regeneration check valve 27B is fully closed.
  • the center bypass passage Lb branches off from the pump discharge passage Ld and is connected to the tank 19.
  • a boom control valve 45, an arm control valve 46, and a bypass cut valve 17 are provided in tandem in this order.
  • the bypass cut valve 17 has a throttle that provides resistance to the flow of hydraulic oil passing through it, and the hydraulic oil discharged from the hydraulic pump 81 is discharged through this throttle to the tank 19.
  • the bypass cut valve 17 can adjust the pump discharge pressure by changing the opening area (opening degree) of the throttle.
  • the pilot circuit HC2 is provided with a pilot pressure reducing valve (first pressure reducing valve) 71 that reduces the pressure of the hydraulic oil discharged from the hydraulic pump 81 (i.e., the pump discharge pressure) to generate a pilot primary pressure, a check valve 72 for holding the pilot primary pressure, an accumulator 73 for smoothing the pilot primary pressure, and a lock valve 74 capable of blocking the pilot primary pressure.
  • a pilot pressure reducing valve first pressure reducing valve
  • the pilot circuit HC2 is also provided with solenoid valves (second pressure reducing valves) 61A, 61B that reduce the pilot primary pressure to generate a pilot secondary pressure that acts on the pilot pressure receiving portions 45a, 45b of the boom control valve 45, and solenoid valves (second pressure reducing valves) 62A, 62B that reduce the pilot primary pressure to generate a pilot secondary pressure that acts on the pilot pressure receiving portions 46a, 46b of the arm control valve 46.
  • the pilot circuit HC2 is provided with a solenoid valve (third pressure reducing valve) 63 that reduces the pilot primary pressure to generate a pilot secondary pressure that acts on the pilot pressure receiving portion 17a of the bypass cut valve 17.
  • the pilot circuit HC2 is provided with a solenoid valve (fourth pressure reducing valve) 35A that reduces the pilot primary pressure to generate a pilot secondary pressure that acts on the pilot pressure receiving part of the CT opening control valve 26A, and a solenoid valve (fourth pressure reducing valve) 35B that reduces the pilot primary pressure to generate a pilot secondary pressure that acts on the pilot pressure receiving part of the CT opening control valve 26B.
  • Solenoid valves 35A, 35B, 61A, 61B, 62A, 62B, and 63 are solenoid proportional valves that are driven by solenoid thrust generated in response to the control current supplied to the solenoid.
  • the solenoid valves 61A and 61B generate pilot secondary pressure to be output to the pilot pressure receiving parts 45a and 45b of the boom control valve 45, using the pilot primary pressure generated by the pilot pressure reducing valve 71 as the base pressure.
  • the solenoid valves 61A and 61B are controlled based on a signal (control current) output from the main controller 100.
  • the main controller 100 controls the solenoid valves 61A and 61B based on an operation signal output from the boom operation device 23.
  • the boom control valve 45 When the pilot secondary pressure generated by the solenoid valve 61A acts on the pilot pressure receiving portion 45a of the boom control valve 45, the boom control valve 45 is switched to the extended position. This causes the hydraulic oil discharged from the hydraulic pump 81 to be guided to the bottom chamber of the boom cylinder 11a and the hydraulic oil to be discharged from the rod chamber to the tank 19, causing the boom cylinder 11a to extend. As a result, the boom 11 rotates upward (i.e., the boom 11 stands up).
  • the boom control valve 45 When the pilot secondary pressure generated by the solenoid valve 61B acts on the pilot pressure receiving portion 45b of the boom control valve 45, the boom control valve 45 is switched to the contracted position. This causes the hydraulic oil discharged from the hydraulic pump 81 to be guided to the rod chamber of the boom cylinder 11a and the hydraulic oil to be discharged from the bottom chamber to the tank 19, causing the boom cylinder 11a to contract. As a result, the boom 11 rotates downward (i.e., the boom 11 is lowered).
  • the solenoid valves 62A, 62B generate pilot secondary pressure to be output to the pilot pressure receiving parts 46a, 46b of the arm control valve 46, using the pilot primary pressure generated by the pilot pressure reducing valve 71 as the base pressure.
  • the solenoid valves 62A, 62B are controlled based on a signal (control current) output from the main controller 100.
  • the main controller 100 controls the solenoid valves 62A, 62B based on an operation signal output from the arm operation device 24.
  • the arm control valve 46 When the pilot secondary pressure generated by the solenoid valve 62A acts on the pilot pressure receiving portion 46a of the arm control valve 46, the arm control valve 46 is switched to the extended position. This causes the hydraulic oil discharged from the hydraulic pump 81 to be guided to the bottom chamber of the arm cylinder 12a and the hydraulic oil to be discharged from the rod chamber to the tank 19, causing the arm cylinder 12a to extend. As a result, the arm 12 rotates downward (i.e., the arm 12 performs a crowding operation).
  • the arm control valve 46 When the pilot secondary pressure generated by the solenoid valve 62B acts on the pilot pressure receiving portion 46b of the arm control valve 46, the arm control valve 46 is switched to the contracted position. This causes the hydraulic oil discharged from the hydraulic pump 81 to be guided to the rod chamber of the arm cylinder 12a and the hydraulic oil to be discharged from the bottom chamber to the tank 19, causing the arm cylinder 12a to contract. As a result, the arm 12 rotates upward (i.e., the arm 12 performs a dumping operation).
  • the solenoid valve 63 uses the pilot primary pressure generated by the pilot pressure reducing valve 71 as the base pressure and generates a pilot secondary pressure to be output to the pilot pressure receiving portion 17a of the bypass cut valve 17.
  • the solenoid valve 63 is controlled based on a signal (control current) output from the main controller 100.
  • the main controller 100 controls the solenoid valve 63 based on a gate lock lever signal output from the gate lock lever device 22, an operation signal output from the operation devices 23, 24, and a pressure detected by a pressure sensor 25 described later.
  • the bypass cut valve 17 has a spool position controlled according to the pilot secondary pressure acting on the pilot pressure receiving portion 17a.
  • the pilot secondary pressure is equivalent to the tank pressure
  • the spring force of the return spring holds the spool in the neutral position.
  • the aperture opening area is the maximum opening area Abmax.
  • the spool moves against the spring force of the return spring, and the opening area of the throttle becomes smaller.
  • the bypass cut valve 17 cuts off communication between the hydraulic pump 81 and the tank 19. At this time, the opening area of the throttle becomes the minimum opening area Abmin (e.g., 0).
  • a lock valve 74 is provided between the pilot pressure reducing valve 71 and the solenoid valves 35A, 35B, 61A, 61B, 62A, 62B, and 63.
  • the lock valve 74 is an electromagnetic switching valve that is switched to either a blocking position or a communication position by a control signal output from the main controller 100 according to the operating position of the gate lock lever device 22.
  • the lock valve 74 When the gate lock lever device 22 is operated to the lock position, the lock valve 74 is switched to the cut-off position. This cuts off the pilot primary pressure to the solenoid valves 61A, 61B, 62A, and 62B, and disables operation by the operating levers 23a and 24a. In addition, because the pilot primary pressure to the solenoid valve 63 is also cut off, the bypass cut valve 17 is held in the neutral position regardless of operation by the operating devices 23 and 24.
  • the lock valve 74 is switched to the communication position. Therefore, when the gate lock lever device 22 is operated to the unlocked position, pilot secondary pressure according to the operation direction and operation amount of the operating levers 23a, 24a is generated by the solenoid valves 61A, 61B, 62A, 62B, and the actuators (11a, 12a) corresponding to the operated operating levers 23a, 24a are activated.
  • the pilot circuit HC2 is provided with a check valve 72 and an accumulator 73, so that the pilot primary pressure can be maintained even if the discharge pressure of the hydraulic pump 81 temporarily becomes lower than the set pressure of the pilot pressure reducing valve 71.
  • the main controller 100 is composed of a microcomputer equipped with a CPU (Central Processing Unit) 101 as an operating circuit, a ROM (Read Only Memory) 102 as a storage device, a RAM (Random Access Memory) 103 as a storage device, an input/output interface 104, and other peripheral circuits.
  • the main controller 100 may be composed of one microcomputer or multiple microcomputers.
  • the engine controller 105 has a similar configuration to the main controller 100, is connected to the main controller 100, and exchanges information (data) with the main controller 100.
  • ROM 102 is a non-volatile memory such as an EEPROM, and stores programs capable of executing various calculations.
  • ROM 102 is a storage medium capable of reading programs that realize the functions of this embodiment.
  • RAM 103 is a volatile memory, and is a work memory that directly inputs and outputs data to and from CPU 101. RAM 103 temporarily stores necessary data while CPU 101 is executing a program.
  • main controller 100 may further include a storage device such as a flash memory, a hard disk drive, etc.
  • the CPU 101 is a processing device that loads a program stored in the ROM 102 into the RAM 103 and executes the program, and performs predetermined calculations on signals received from the input/output interface 104, ROM 102, and RAM 103 in accordance with the program. Signals from the engine control dial 21, gate lock lever device 22, operating devices 23 and 24, pressure sensor 25, engine controller 105, etc. are input to the input/output interface 104. The input section of the input/output interface 104 converts the input signals so that they can be calculated by the CPU 101.
  • the output section of the input/output interface 104 generates an output signal according to the result of the calculation by the CPU 101, and outputs the signal to the lock valve 74, solenoid valves 35A, 35B, 61A, 61B, 62A, 62B, and 63, regulator 81a, etc.
  • the pressure sensor 25 detects the pressure of the hydraulic oil on the discharge side of the hydraulic pump 81.
  • the pressure sensor 25 detects the discharge pressure of the hydraulic pump 81 (circuit pressure of the main circuit HC1) and outputs a signal representing the detection result (pump discharge pressure) to the main controller 100.
  • the main controller 100 controls the discharge capacity of the hydraulic pump 81 using the regulator 81a based on the pump discharge pressure and actual engine rotation speed detected by the sensors 25, 80a, and the operation signals from the operation devices 23, 24.
  • the hydraulic system 90 includes a control valve block 4 having a boom control valve 45, an arm control valve 46, a bypass cut valve 17, CT opening control valves 26A, 26B, check valves 27A, 27B, 41, 42, and a relief valve 47, a first solenoid valve block 5 having solenoid valves 61A, 62A, a second solenoid valve block 6 having solenoid valves 61B, 62B, 63, a third solenoid valve block 8 having solenoid valves 35A, 35B, and a pilot primary pressure generating block 7 having a pilot pressure reducing valve 71, a check valve 72, and a lock valve 74.
  • a control valve block 4 having a boom control valve 45, an arm control valve 46, a bypass cut valve 17, CT opening control valves 26A, 26B, check valves 27A, 27B, 41, 42, and a relief valve 47
  • a first solenoid valve block 5 having solenoid valves 61A, 62A
  • the control valve block 4 distributes the hydraulic oil discharged from the hydraulic pump 81 to hydraulic cylinders such as the boom cylinder 11a and the arm cylinder 12a.
  • the pilot primary pressure generation block 7 reduces the pressure of the hydraulic oil discharged from the hydraulic pump 81 to an appropriate set pressure (e.g., 4 MPa) using the pilot pressure reducing valve 71.
  • an appropriate set pressure e.g. 4 MPa
  • the pilot primary pressure generated by the pilot pressure reducing valve 71 is directed to the first to third solenoid valve blocks 5, 6, and 8.
  • the pilot primary pressure circuits of the first to third solenoid valve blocks 5, 6, and 8 are connected to the tank 19.
  • the primary pressures of the solenoid valves 35A, 35B, 61A, 61B, 62A, 62B, and 63 are opened to near 0 (zero), so that the valves 17, 26A, 26B, 45, and 46 are held in the neutral position.
  • the pilot 1 pressure generating block 7 is equipped with a check valve 72 and an accumulator 73, so even if the pump discharge pressure falls below the set pressure of the pilot pressure reducing valve 71, the pilot 1 pressure is temporarily maintained.
  • the pump discharge pressure drops.
  • the main controller 100 increases the pump discharge pressure and ensures pilot primary pressure by reducing the opening area of the throttle of the bypass cut valve 17.
  • the weight of the working device 10 may increase or the center of gravity of the working device 10 may become farther from the center of rotation. In this case, the moment of inertia of the working device 10 increases.
  • FIG. 3 An example of the flow of valve control processing executed by the main controller 100 will be described with reference to FIG. 3.
  • the processing shown in the flowchart of FIG. 3 is started when an ignition switch (not shown) is turned on, and is repeatedly executed at a predetermined control period.
  • step S100 the main controller 100 acquires a gate lock lever signal from the gate lock lever device 22, an operation signal from the operation devices 23 and 24, and a pressure signal from the pressure sensor 25, and proceeds to step S105.
  • step S105 the main controller 100 determines whether the gate lock lever device 22 has been operated to the unlocked position (lowered position) based on the gate lock lever signal acquired in step S100. If it is determined in step S105 that the gate lock lever device 22 has been operated to the unlocked position (i.e., a state in which the actuator can be moved), the process proceeds to step S110. If it is determined in step S105 that the gate lock lever device 22 has been operated to the locked position (uppered position) (i.e., a state in which the actuator cannot be moved), the process proceeds to step S115.
  • step S115 the main controller 100 sets the target opening area Abt of the bypass cut valve 17 to the maximum opening area Abmax, sets the target opening area Act of the CT opening control valves 26A, 26B to the maximum opening area Acmax, and proceeds to step S180.
  • step S110 the main controller 100 determines whether or not at least one of the operating devices 23, 24 is being operated based on the operation signal acquired in step S100.
  • the main controller 100 determines that the operating devices 23, 24 are being operated if the amount of operation of the operating devices 23, 24 is equal to or greater than a predetermined value.
  • the main controller 100 determines that the operating devices 23, 24 are not being operated if the amount of operation of the operating devices 23, 24 is less than the predetermined value. If it is determined in step S110 that at least one of the operating devices 23, 24 is being operated, the process proceeds to step S120. If it is determined in step S110 that neither of the operating devices 23, 24 is being operated, the process proceeds to step S125.
  • step S125 the main controller 100 sets the target opening area Abt of the bypass cut valve 17 to the opening area Abn for non-operation, and sets the target opening area Act of the CT opening control valves 26A, 26B to the maximum opening area Acmax.
  • the opening area Abn for non-operation is a value that is greater than the minimum opening area Abmin and smaller than the maximum opening area Abmax (Abmin ⁇ Abn ⁇ Abmax).
  • the opening area Abn for non-operation is set so that a pilot primary pressure that can displace the spools of the control valves 45, 46 to the maximum stroke can be generated even if a slight pressure drop occurs.
  • the opening area Abn for non-operation is set to an opening area that can generate a pilot primary pressure of 3.3 [MPa] as the lower limit pressure Pimin of the pilot primary pressure.
  • the opening area Abn for non-operation may be any opening area that can generate a pilot primary pressure within a certain range (above the lower limit pressure Pimin and below the upper limit pressure Pimax) that can displace the spool to the maximum stroke.
  • the opening area Abn for non-operation is set so that when the gate lock lever device 22 is operated to the unlocked position and the operating devices 23, 24 are not operated (standby state), the pump discharge pressure Pp becomes the upper limit pressure Pimax of the pilot primary pressure (for example, about 4 MPa).
  • the main controller 100 may detect the pump discharge flow rate, which varies depending on the temperature of the hydraulic oil and the engine speed, and calculate the opening area Abn for when the hydraulic pump 81 is not in operation so that the discharge pressure of the hydraulic pump 81 detected by the pressure sensor 25 falls within a certain range (above the lower limit pressure Pimin and below the upper limit pressure Pimax).
  • step S120 the main controller 100 determines whether the pump discharge pressure Pp is within a certain range (above the lower limit pressure Pimin and below the upper limit pressure Pimax) based on the pressure signal acquired in step S100. If it is determined in step S120 that the pump discharge pressure Pp is within the certain range, the process proceeds to step S130. If it is determined in step S120 that the pump discharge pressure Pp is not within the certain range, the process proceeds to step S135.
  • step S130 the main controller 100 sets the target opening area Abt of the bypass cut valve 17 to the target opening area Abt (previous value) set one control cycle ago, and sets the target opening area Act of the CT opening control valves 26A, 26B to the target opening area Act (previous value) set one control cycle ago, and proceeds to step S180.
  • step S135 the main controller 100 determines whether the pump discharge pressure Pp is higher than the upper limit pressure Pimax based on the pressure signal acquired in step S100. If it is determined in step S135 that the pump discharge pressure Pp is higher than the upper limit pressure Pimax, the process proceeds to step S140. If it is determined in step S135 that the pump discharge pressure Pp is equal to or lower than the upper limit pressure Pimax, the process proceeds to step S150.
  • step S140 the main controller 100 determines whether the target opening area Abt of the bypass cut valve 17 is equal to or greater than the maximum opening area Abmax. If it is determined in step S140 that the target opening area Abt of the bypass cut valve 17 is equal to or greater than the maximum opening area Abmax, the process proceeds to step S130. If it is determined in step S140 that the target opening area Abt of the bypass cut valve 17 is less than the maximum opening area Abmax, the process proceeds to step S145.
  • step S145 the main controller 100 adds a predetermined value ⁇ Ab to the target opening area Abt (previous value) of the bypass cut valve 17 and sets the result as a new target opening area Abt (present value).
  • the main controller 100 also sets the target opening area Act of the CT opening control valves 26A, 26B to the target opening area Act (previous value) set one control cycle ago, and proceeds to step S180.
  • step S150 the main controller 100 determines whether the pump discharge pressure Pp is lower than the lower limit pressure Pimin based on the pressure signal acquired in step S100. If it is determined in step S150 that the pump discharge pressure Pp is lower than the lower limit pressure Pimin, the process proceeds to step S160. If it is determined in step S150 that the pump discharge pressure Pp is equal to or higher than the lower limit pressure Pimin, the process returns to step S120.
  • step S160 the main controller 100 determines whether the target opening area Abt of the bypass cut valve 17 is equal to or smaller than the minimum opening area Abmin. If it is determined in step S160 that the target opening area Abt of the bypass cut valve 17 is equal to or smaller than the minimum opening area Abmin, the process proceeds to step S170. If it is determined in step S160 that the target opening area Abt of the bypass cut valve 17 is larger than the minimum opening area Abmin, the process proceeds to step S175.
  • the main controller 100 sets the target opening area Act of the CT opening control valves 26A, 26B to the minimum opening area Acmin (e.g., 0).
  • the main controller 100 also sets the target opening area Abt of the bypass cut valve 17 to the target opening area Abt (previous value) set one control cycle ago, and proceeds to step S180.
  • step S175 the main controller 100 subtracts a predetermined value ⁇ Ab from the target opening area Abt (previous value) of the bypass cut valve 17, and sets the result as a new target opening area Abt (present value).
  • the main controller 100 also sets the target opening area Act of the CT opening control valves 26A, 26B to the target opening area Act (previous value) set one control cycle ago, and proceeds to step S180.
  • step S180 the main controller 100 outputs a control current corresponding to the target opening area Abt of the bypass cut valve 17 to the solenoid valve 63, and the process proceeds to step S190.
  • step S190 the main controller 100 outputs a control current corresponding to the target opening area Act of the CT opening control valves 26A, 26B to the solenoid valves 61A, 61B, and ends the process shown in the flowchart of FIG. 3.
  • FIG. 4 is a diagram showing the time series changes in the operation position Pg of the gate lock lever device 22, the boom lowering operation amount L of the boom operation device 23, the discharge pressure Pp of the hydraulic pump 81, the discharge capacity (tilt angle of the swash plate) q of the hydraulic pump 81, the opening area Ab of the bypass cut valve 17, and the opening area Ac of the meter-out throttle 28A of the CT opening control valve 26A.
  • the horizontal axis indicates time (elapsed time). At time t0, the gate lock lever device 22 is in the lock position, and the bucket 13 is sufficiently separated from the ground.
  • the operator operates the gate lock lever device 22 to the unlock position. This makes it possible to operate the work device 10 by the operation devices 23 and 24 (standby state).
  • the opening area of the bypass cut valve 17 decreases from the maximum opening area Abmax to the opening area Abn for non-operation (see step S125 in FIG. 3).
  • the discharge pressure Pp of the hydraulic pump 81 increases to the upper limit pressure Pimax. This ensures the necessary pilot primary pressure, and when the operating devices 23 and 24 are operated, the solenoid valves 61A, 61B, 62A, and 62B are able to appropriately generate pilot secondary pressure according to the amount of operation.
  • the operator uses the boom operation device 23 to perform the boom lowering operation. From time t2 to time t3, the operation amount L of the boom operation device 23 gradually increases. From time t3 to time t4, the operation amount L is maintained at the operation amount L1 for fine operation. As the operation amount L increases from time t2, the discharge capacity q of the hydraulic pump 81 increases. The spool of the boom control valve 45 is displaced to a position according to the operation amount L, and the boom 11 is lowered. As the operation amount L of the boom lowering operation increases, the discharge pressure Pp of the hydraulic pump 81 decreases.
  • the operation amount L of the boom operation device 23 gradually increases. From time t5 to time t6, the operation amount L is maintained at the operation amount L2 for half operation. As the operation amount L increases from time t4, the discharge capacity q of the hydraulic pump 81 increases. The spool of the boom control valve 45 is displaced to a position according to the operation amount L, and the lowering speed of the boom 11 increases. As the operation amount L of the boom lowering operation increases, the discharge pressure Pp of the hydraulic pump 81 decreases.
  • the operation amount L of the boom operation device 23 gradually increases. From time t7 to time t8, the operation amount L is maintained at an operation amount L3 between half operation and full operation. As the operation amount L increases from time t6, the discharge capacity q of the hydraulic pump 81 increases. The spool of the boom control valve 45 is displaced to a position according to the operation amount L, and the lowering speed of the boom 11 increases. As the operation amount L of the boom lowering operation increases, the discharge pressure Pp of the hydraulic pump 81 decreases.
  • the operation amount L of the boom operation device 23 gradually increases. From time t9 to time t10, the operation amount L is maintained at the maximum operation amount Lmax for full operation. As the operation amount L increases from time t8 to the maximum operation amount Lmax, the discharge capacity q of the hydraulic pump 81 increases to the maximum discharge capacity (maximum tilt angle) qmax. The spool of the boom control valve 45 is displaced to the maximum stroke position, and the lowering speed of the boom 11 increases. As the operation amount L of the boom lowering operation increases, the discharge pressure Pp of the hydraulic pump 81 decreases.
  • the opening area Ac of the CT opening control valve 26A decreases from the maximum opening area Acmax to the minimum opening area Acmin (e.g., 0) (see step S170 in FIG. 3). As a result, the discharge pressure Pp of the hydraulic pump 81 rises to the upper limit pressure Pimax.
  • the opening area of the bypass cut valve 17 is reduced, thereby increasing the discharge pressure Pp of the hydraulic pump 81 and preventing the discharge pressure Pp from becoming lower than the lower limit pressure Pimin of the set pressure of the pilot pressure reducing valve 71. Furthermore, when the boom lowering operation is performed, for example, when the operation amount L is the maximum operation amount Lmax, not only the bypass cut valve 17 but also the opening area of the meter-out throttle 28A of the CT opening control valve 26A is reduced.
  • the main controller (control device) 100 controls the solenoid valve (third pressure reducing valve) 63 to reduce the opening area Ab of the bypass cut valve 17 (see steps S150, S160, S175, and S180 in FIG. 3).
  • the solenoid valve (third pressure reducing valve) 63 controls the solenoid valve (third pressure reducing valve) 63 to reduce the opening area Ab of the bypass cut valve 17.
  • the bypass cut valve 17 is controlled to the closing side and the discharge pressure of the hydraulic pump 81 increases.
  • the pressure Pp detected by the pressure sensor 25 is higher than the upper limit pressure (second pressure) Pimax that is higher than the lower limit pressure Pimin, and the opening area Ab of the bypass cut valve 17 is smaller than the maximum opening area (second area) Abmax that is larger than the minimum opening area Abmin
  • the main controller 100 controls the solenoid valve 63 so that the opening area Ab of the bypass cut valve 17 is increased (see steps S135, S140, S145, and S180 in FIG. 3).
  • the main controller 100 controls the solenoid valves (fourth pressure reducing valves) 35A, 35B to reduce the opening area of the meter-out throttles 28A, 28B when the pressure Pp detected by the pressure sensor 25 is lower than the lower limit pressure Pimin and the opening area Ab of the bypass cut valve 17 is equal to or smaller than the minimum opening area (see steps S150, S160, S170, S190 in FIG. 3).
  • the hydraulic system 90 according to this embodiment is configured to reduce the opening area of the meter-out throttles 28A, 28B as the amount of operation (boom lowering operation, arm crowding operation) by the operating devices 23, 24 to operate the work device 10 in the direction of gravity increases.
  • the main controller 100 controls the solenoid valve 63 so that the opening area Ab of the bypass cut valve 17 becomes an opening area smaller by a predetermined value ⁇ Ab (see steps S175 and S180 in FIG. 3).
  • the main controller 100 controls the solenoid valve 63 each time the above condition is satisfied, thereby gradually reducing the opening area Ab of the bypass cut valve 17 (see FIG. 4). This makes it possible to suppress sudden pressure fluctuations in the main circuit HC1.
  • Fig. 5 is a functional block diagram of the main controller 100 according to the second embodiment of the present invention, and shows functions related to the control of the bypass cut valve 17.
  • the main controller 100 executes feedback control based on the discharge pressure Pp of the hydraulic pump 81.
  • the main controller 100 increases the discharge pressure Pp by reducing the opening area of the bypass cut valve 17 when the discharge pressure Pp becomes lower than the lower limit pressure Pimin, and decreases the discharge pressure Pp by increasing the opening area of the bypass cut valve 17 when the discharge pressure Pp becomes higher than the upper limit pressure Pimax.
  • the main controller 100 has the functions described in the first embodiment, and further has a function of controlling the opening area of the bypass cut valve 17 so that the discharge pressure Pp falls within a certain range (above the lower limit pressure Pimin and below the upper limit pressure Pimax) based on the rotation speed of the hydraulic pump 81 and the temperature of the hydraulic oil.
  • the control method (control mode) of the bypass cut valve 17 described in the first embodiment and the control method (control mode) of the bypass cut valve 17 described in this second embodiment can be switched, for example, by the operator performing a mode switching operation on an input device in the cab 31.
  • the main controller 100 controls the opening area of the bypass cut valve 17, taking into consideration the effect of the flow rate change due to the change in the rotation speed of the hydraulic pump 81 and the effect of the viscosity change due to the change in temperature of the hydraulic oil. For example, when the rotation speed of the hydraulic pump 81 increases while the opening area of the bypass cut valve 17 is held at a predetermined area, the flow rate of the hydraulic oil passing through the bypass cut valve 17 increases, and the discharge pressure of the hydraulic pump 81 increases.
  • the opening area of the bypass cut valve 17 is held at a predetermined area and the rotation speed of the hydraulic pump 81 is at a predetermined speed, if the discharge pressure becomes a target pressure (e.g., 4 MPa), when the rotation speed of the hydraulic pump 81 becomes higher than the predetermined speed, it is necessary to make the opening area of the bypass cut valve 17 larger than the predetermined area.
  • a target pressure e.g. 4 MPa
  • the discharge pressure becomes a target pressure (e.g., 4 MPa)
  • the temperature of the hydraulic oil becomes lower than the predetermined temperature
  • a non-volatile memory in the form of a table or function the characteristics of the opening area of the bypass cut valve 17 relative to the rotation speed of the hydraulic pump 81 such that the discharge pressure becomes the target pressure, and the characteristics of the opening area of the bypass cut valve 17 relative to the temperature of the hydraulic oil, and to use these characteristics to control the opening area of the bypass cut valve 17.
  • the main controller 100 has a first target area setting unit 111, a second target area setting unit 112, a minimum value selection unit 113, a proportional valve pressure setting unit 114, and a control current setting unit 118.
  • the hydraulic pump 81 is mechanically connected to the engine 80. Therefore, the rotation speed sensor 80a functions as a sensor that detects the rotation speed of the hydraulic pump 81. Note that a sensor that detects the rotation speed of the hydraulic pump 81 may be provided separately from the rotation speed sensor 80a of the engine 80.
  • the temperature sensor 19a is provided in the tank 19 or the like (see FIG. 2), detects the temperature of the hydraulic oil, and outputs a signal indicating the detection result to the main controller 100.
  • the first target area setting unit 111 refers to the speed-opening table and sets the first target area Ab1 of the bypass cut valve 17 based on the rotation speed N of the hydraulic pump 81 detected by the rotation speed sensor 80a.
  • the speed-opening table is a data table that specifies the relationship between the rotation speed N of the hydraulic pump 81 and the first target area Ab1, and is stored in a non-volatile memory.
  • the speed-opening table specifies the characteristic that the first target area Ab1 increases from the minimum opening area Abmin to the opening area Abn for non-operation as the rotation speed N of the hydraulic pump 81 increases. Therefore, the first target area setting unit 111 sets the first target area Ab1 of the bypass cut valve 17 to a larger value as the rotation speed N detected by the rotation speed sensor 80a increases.
  • For the rotation speed value of the speed-opening table a rotation speed value that is preset so as to obtain a "pressure that can ensure a stable pilot primary pressure" is used.
  • the second target area setting unit 112 refers to the temperature-opening table and sets the second target area Ab2 of the bypass cut valve 17 based on the hydraulic oil temperature To detected by the temperature sensor 19a.
  • the temperature-opening table is a data table that specifies the relationship between the hydraulic oil temperature To and the second target area Ab2, and is stored in a non-volatile memory.
  • the temperature-opening table specifies the characteristic that the second target area Ab2 decreases from the opening area Abn for non-operation to the minimum opening area Abmin as the hydraulic oil temperature To increases. Therefore, the second target area setting unit 112 sets the second target area Ab2 of the bypass cut valve 17 to a smaller value the higher the temperature To detected by the temperature sensor 19a.
  • the temperature value of the temperature-opening table is a temperature value that is preset so as to obtain a "pressure that can ensure a stable pilot primary pressure.”
  • the minimum value selection unit 113 selects the smaller of the first target area Ab1 set by the first target area setting unit 111 and the second target area Ab2 set by the second target area setting unit 112, and sets it as the target opening area Abt of the bypass cut valve 17.
  • the first target area setting unit 111, the second target area setting unit 112, and the minimum value selection unit 113 function as a target opening area setting unit that sets the target opening area of the bypass cut valve 17.
  • the proportional valve pressure setting unit 114 refers to the opening-proportional valve pressure table and sets the proportional valve pressure po, which is the pilot secondary pressure generated by the solenoid valve 63, based on the target opening area Abt set by the minimum value selection unit 113.
  • the opening-proportional valve pressure table is a data table that specifies the relationship between the target opening area Abt and the proportional valve pressure po, and is stored in non-volatile memory.
  • the opening-proportional valve pressure table specifies the characteristic that the proportional valve pressure po decreases as the target opening area Abt increases. Therefore, the proportional valve pressure setting unit 114 sets the proportional valve pressure po to a smaller value the larger the target opening area Abt is.
  • the control current setting unit 118 sets the control current I to be output to the solenoid valve 63 based on the proportional valve pressure po set by the proportional valve pressure setting unit 114.
  • a data table defining the relationship between these set proportional valve pressures po and the control current I is stored in non-volatile memory as a proportional valve pressure-control current table.
  • the proportional valve pressure-control current table defines the characteristic that the control current I increases as the proportional valve pressure po increases. Therefore, the control current setting unit 118 sets the control current I to a larger value as the proportional valve pressure po increases.
  • the control current setting unit 118 outputs the set control current I to the solenoid valve 63.
  • the main controller 100 sets the first target area Ab1 of the bypass cut valve 17 to a larger value as the rotation speed N of the hydraulic pump 81 detected by the rotation speed sensor 80a increases, and sets the second target area Ab2 of the bypass cut valve 17 to a smaller value as the temperature To of the hydraulic oil detected by the temperature sensor 19a increases.
  • the main controller 100 selects the smaller of the first target area Ab1 and the second target area Ab2 and sets it as the target opening area Abt.
  • the main controller 100 sets the control current I based on the set target opening area Abt, and controls the solenoid valve (third pressure reducing valve) 63 with the set control current I.
  • the second embodiment can avoid the risk of hunting due to feedback control.
  • the bypass cut valve 17 can be appropriately controlled according to the rotation speed N of the hydraulic pump 81 and the temperature To of the hydraulic oil. Therefore, according to the second embodiment, when an operation is performed to operate the working device 10 in the direction of gravity, the pump discharge pressure Pp can be appropriately maintained at the target value Ppt.
  • the opening area of the meter-out throttles 28A, 28B is adjusted in accordance with the displacement of the spools of the cylinder control valves 45, 46, so that the same effect as in the above embodiment can be obtained.
  • the opening area of the meter-out throttles 28A, 28B changes in accordance with the displacement of the spools of the cylinder control valves 45, 46, so that the speed of the hydraulic cylinder during fine operation or half operation is affected.
  • the meter-out throttles 28A, 28B must be determined by the shape of the spool and the hole that accommodates the spool, it is time-consuming to form the cylinder control valves 45, 46. For this reason, it is preferable to provide the CT opening control valves 26A, 26B and the cylinder control valves 45, 46 so that they can be controlled independently, as in the above embodiment.
  • the pressure sensor 25 for detecting the discharge pressure of the hydraulic pump 81 is used as the pressure sensor for detecting the pressure of the hydraulic oil on the discharge side of the hydraulic pump 81, and the main controller 100 controls the solenoid valve 63 based on the detection result of the pressure sensor 25.
  • the main controller 100 may control the solenoid valve 63 based on the detection result of the pressure sensor 75 (see FIG. 2 and FIG. 6) for detecting the pressure of the hydraulic oil on the discharge side of the hydraulic pump 81, instead of the detection result of the pressure sensor 25.
  • the pressure sensor 25 is a pump pressure sensor provided upstream of the pilot pressure reducing valve 71 and detects the discharge pressure of the hydraulic pump 81.
  • the pressure sensor 75 is an accumulator pressure sensor provided downstream of the pilot pressure reducing valve 71 and detects the pressure of the accumulator 73.
  • the solenoid valve 63 is controlled based on the detection result of the pressure sensor 75 for detecting the pressure of the accumulator 73, the frequency of throttling the bypass cut valve 17 can be reduced compared to a configuration in which the solenoid valve 63 is controlled based on the detection result of the pressure sensor 25 for detecting the discharge pressure of the hydraulic pump 81.
  • ⁇ Modification 3> In the first embodiment, an example has been described in which the CT opening control valve 26A is controlled to be fully closed in order to prevent the discharge pressure Pp of the hydraulic pump 81 from decreasing when the boom lowering operation is performed and the bypass cut valve 17 is fully closed, and the CT opening control valve 26B is controlled to prevent the discharge pressure Pp of the hydraulic pump 81 from decreasing when the arm crowding operation is performed and the bypass cut valve 17 is fully closed.
  • the present invention is not limited to this.
  • the control content of the CT opening control valve described in the first embodiment may be applied to only one of the CT opening control valve 26A and the CT opening control valve 26B.
  • the main controller 100 selects the smaller of the first target area Ab1 set based on the rotation speed N of the hydraulic pump 81 and the second target area Ab2 set based on the temperature To of the hydraulic oil, and sets the selected area as the target opening area Abt of the bypass cut valve 17.
  • the main controller 100 according to the second embodiment is configured to set the target opening area Abt by taking into account both the rotation speed N of the hydraulic pump 81 and the temperature To of the hydraulic oil.
  • the method of setting the target opening area Abt is not limited to this method.
  • the main controller 100 may set the target opening area Abt of the bypass cut valve 17 to a larger value as the rotation speed N detected by the rotation speed sensor 80a increases, and control the solenoid valve 63.
  • the bypass cut valve 17 can be appropriately controlled in accordance with the rotation speed N of the hydraulic pump 81.
  • the main controller 100 may set the target opening area Abt of the bypass cut valve 17 to a smaller value as the temperature To detected by the temperature sensor 19a increases, and control the solenoid valve 63.
  • the bypass cut valve 17 can be appropriately controlled in accordance with the temperature To of the hydraulic oil.
  • bypass cut valve 17 is provided in the center bypass passage Lb downstream of the cylinder control valves 45, 46, but the present invention is not limited to this.
  • the bypass cut valve 17 may be provided upstream of the cylinder control valves 45, 46 in the center bypass passage Lb.
  • hydraulic pump 81a... regulator, 90... hydraulic system, 100... main controller (control device), 111... first target area setting section, 112... second target area setting section, 113... minimum value selection section, 114... proportional valve pressure setting section, 118... control current setting section, Ab... bypass cut valve opening area, Ab1... first target area, Ab2... second target area, Abmax... maximum opening area (second area), Abmin... minimum opening area (first area), Abn... opening area for non-operation, Abt... target opening area of bypass cut valve, Ac... opening area of CT opening control valve, Acmax... maximum opening area, Acmin... minimum Aperture area, Act... target aperture area of CT aperture control valve, HC1... main circuit, HC2... pilot circuit, I... control current, L...

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Operation Control Of Excavators (AREA)
PCT/JP2023/035296 2022-09-29 2023-09-27 作業機械 Ceased WO2024071261A1 (ja)

Priority Applications (4)

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JP2024550427A JP7788568B2 (ja) 2022-09-29 2023-09-27 作業機械
KR1020257003733A KR20250047736A (ko) 2022-09-29 2023-09-27 작업 기계
CN202380058168.5A CN119654494B (zh) 2022-09-29 2023-09-27 作业机械
EP23872483.5A EP4549747A1 (en) 2022-09-29 2023-09-27 Work machine

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001263304A (ja) 2000-03-16 2001-09-26 Shin Caterpillar Mitsubishi Ltd 流体圧回路装置
JP2011127727A (ja) * 2009-12-21 2011-06-30 Sumitomo (Shi) Construction Machinery Co Ltd 建設機械の油圧回路
WO2022195832A1 (ja) * 2021-03-18 2022-09-22 日立建機株式会社 作業機械

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5590730A (en) 1994-11-04 1997-01-07 Samsung Heavy Industry Co., Ltd. Straight travelling apparatus for construction vehicles
JP5388787B2 (ja) * 2009-10-15 2014-01-15 日立建機株式会社 作業機械の油圧システム
JP6308859B2 (ja) * 2014-04-28 2018-04-11 日立建機株式会社 油圧駆動装置
JP6842856B2 (ja) 2016-07-26 2021-03-17 川崎重工業株式会社 液圧駆動システム
JP6646007B2 (ja) * 2017-03-31 2020-02-14 日立建機株式会社 建設機械の油圧制御装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001263304A (ja) 2000-03-16 2001-09-26 Shin Caterpillar Mitsubishi Ltd 流体圧回路装置
JP2011127727A (ja) * 2009-12-21 2011-06-30 Sumitomo (Shi) Construction Machinery Co Ltd 建設機械の油圧回路
WO2022195832A1 (ja) * 2021-03-18 2022-09-22 日立建機株式会社 作業機械

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JP7788568B2 (ja) 2025-12-18
CN119654494B (zh) 2025-11-11
KR20250047736A (ko) 2025-04-04

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