WO2021059571A1 - Machine de travail - Google Patents

Machine de travail Download PDF

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Publication number
WO2021059571A1
WO2021059571A1 PCT/JP2020/017249 JP2020017249W WO2021059571A1 WO 2021059571 A1 WO2021059571 A1 WO 2021059571A1 JP 2020017249 W JP2020017249 W JP 2020017249W WO 2021059571 A1 WO2021059571 A1 WO 2021059571A1
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WO
WIPO (PCT)
Prior art keywords
bleed
valve
pressure
operation amount
work machine
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Application number
PCT/JP2020/017249
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English (en)
Japanese (ja)
Inventor
鈴木　大輔
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日立建機株式会社
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Publication of WO2021059571A1 publication Critical patent/WO2021059571A1/fr

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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • 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
    • 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"

Definitions

  • the present invention relates to a work machine such as a hydraulic excavator.
  • a work machine such as a hydraulic excavator includes a hydraulic actuator, a hydraulic pump driven by a prime mover, a control valve that controls the flow of pressure oil from the hydraulic pump to the hydraulic actuator, and an operating device that operates the control valve.
  • the operating device has, for example, an operating lever that can be operated by the operator and a pilot valve that generates a pilot pressure according to the amount of operation from the neutral position of the operating lever, and controls the pilot pressure generated by the pilot valve. Output to the pressure receiving part of.
  • the control valve is switched from the neutral position to the switching position.
  • the hydraulic actuator is driven by supplying and discharging pressure oil through the control valve.
  • the open center type control valve has a meter-in opening for supplying the pressure oil from the hydraulic pump to the hydraulic actuator, a meter-out opening for discharging the pressure oil from the hydraulic actuator to the tank, and pressure oil from the hydraulic pump. Has a bleed-off opening for returning the tank.
  • the meter-in opening and the meter-out opening are closed and the bleed-off opening is opened to return the pressure oil from the hydraulic pump to the tank.
  • the pilot pressure that is, the operating amount of the operating lever
  • the area of the meter-in opening and the meter-out opening increases, and the area of the bleed-off opening decreases.
  • pressure oil is supplied to and discharged from the hydraulic actuator, and the flow rate thereof is controlled.
  • the working machine described in Patent Document 1 includes a bleed-off valve arranged in a bleed-off pipeline for returning pressure oil to a tank from a bleed-off opening of a control valve, a regulator for variably controlling the capacity of a hydraulic pump, and a pilot pressure ( That is, it includes a pressure sensor that detects the operation amount of the operating device) and a controller that controls the bleed-off valve and the regulator according to the pilot pressure detected by the pressure sensor.
  • the controller controls the bleed-off valve so that the opening (opening area) of the bleed-off valve decreases as the pilot pressure increases.
  • the controller calculates the reference pump flow rate based on the pilot pressure, corrects the reference pump flow rate based on the opening degree of the bleed-off valve, and makes the capacity of the hydraulic pump corresponding to the corrected reference pump flow rate. Control the regulator. As a result, the pump flow rate is reduced as compared with the case where the reference pump flow rate is not corrected, and energy can be saved.
  • the present invention has been made in view of the above matters, and an object of the present invention is to provide a working machine capable of preventing pump pressure from being bound.
  • the present invention presents a hydraulic actuator, a variable displacement hydraulic pump driven by a prime mover, and an open center type control for controlling the flow of pressure oil from the hydraulic pump to the hydraulic actuator.
  • a valve an operating device that operates the control valve, an operating amount detector that detects the operating amount of the operating device, a regulator that variably controls the capacity of the hydraulic pump, and a hydraulic pump that supplies the control valve to the control valve.
  • the controller In a work machine provided with a controller that outputs one command current and outputs a second command current for controlling the opening degree of the bleed-off valve, the controller is the said controller detected by the operation amount detector.
  • the reduction speed of the operation amount is calculated using the operation amount of the operating device, and when the reduction speed of the operation amount is larger than a preset predetermined value, the reduction speed of the operation amount is equal to or less than the predetermined value.
  • the second command current is corrected so that the opening degree of the bleed-off valve is larger than that of the bleed-off valve.
  • FIG. 1 is a side view showing the structure of the hydraulic excavator in the present embodiment.
  • the front side left side in FIG. 1
  • the rear side right side in FIG. 1
  • the left side front side with respect to the paper surface in FIG. 1
  • the right side on the paper surface in FIG. 1 of the operator boarding the cab of the hydraulic excavator.
  • the back side is simply referred to as the front side, the rear side, the left side, and the right side.
  • the hydraulic excavator of the present embodiment includes a traveling body 1 that can travel, a rotating body 2 that is provided so as to be able to turn on the upper side of the traveling body 1, and a working device 3 that is connected to the front side of the turning body 2.
  • the traveling body 1 travels by being driven by a traveling motor 4A on the left side and a traveling motor 4B on the right side (see FIG. 2 described later).
  • the swivel body 2 is swiveled by being driven by a swivel motor 5 (see FIG. 2 described later).
  • the work device 3 is rotatable to a boom 6 rotatably connected to the front portion of the swivel body 2, an arm 7 rotatably connected to the tip portion of the boom 6, and a tip portion of the arm 7. It includes a connected bucket 8.
  • the boom 6, arm 7, and bucket 8 are rotated by driving the boom cylinder 9, arm cylinder 10, and bucket cylinder 11, respectively.
  • a cab 12 on which the operator is boarded is provided on the left side of the front portion of the swivel body 2.
  • a plurality of operating devices (details will be described later) operated by the operator are provided in the cab 12.
  • the hydraulic excavator drives a plurality of hydraulic actuators (specifically, the traveling motors 4A and 4B, the swivel motor 5, the boom cylinder 9, the arm cylinder 10, the bucket cylinder 11, and the like described above) in response to the operation of the plurality of operating devices. It is equipped with a hydraulic drive system.
  • the configuration of this hydraulic drive device will be described with reference to FIGS. 2 and 3.
  • FIG. 2 is a diagram showing a hydraulic pump, a hydraulic actuator, a control valve, and the like in the configuration of the hydraulic drive device in the present embodiment.
  • FIG. 3 is a diagram showing an operating device and the like in the configuration of the hydraulic drive device according to the present embodiment.
  • the hydraulic drive device of the present embodiment is driven by a prime mover 13 (specifically, an engine or an electric motor), variable displacement hydraulic pumps 14A and 14B driven by the prime mover 13, and pressure oil from the hydraulic pump 14A. It is driven by the traveling motor 4A and the bucket cylinder 11, the traveling motor 4B driven by the pressure oil from the hydraulic pumps 14B, the swivel motor 5, and the optional hydraulic actuator 15, and the pressure oil from the hydraulic pumps 14A and 14B.
  • a traveling control valve 16A and a bucket control valve 17 that control the flow of pressure oil from the boom cylinder 9 and the arm cylinder 10, the hydraulic pump 14A to the traveling motor 4A, the bucket cylinder 11, the arm cylinder 10, and the boom cylinder 9, respectively.
  • Control valve 18A for arm Control valve 19A for boom, and control of the flow of pressure oil from the hydraulic pump 14B to the swivel motor 5, boom cylinder 9, arm cylinder 10, optional hydraulic actuator 15, and traveling motor 4B, respectively. It includes a turning control valve 20, a boom control valve 19B, an arm control valve 18B, an optional control valve 21, and a traveling control valve 16B.
  • Each control valve is an open center type, and has a meter-in opening for supplying the pressure oil from the hydraulic pump to the hydraulic actuator, a meter-out opening for discharging the pressure oil from the hydraulic actuator to the tank, and a hydraulic pump. It has a bleed-off opening for returning the pressure oil from the tank to the tank.
  • the meter-in opening and the meter-out opening are closed and the bleed-off opening is opened to return the pressure oil from the hydraulic pump to the tank.
  • the switching position of the control valve for example, as the pilot pressure described later increases, the area of the meter-in opening and the meter-out opening increases, and the area of the bleed-off opening decreases. As a result, pressure oil is supplied to and discharged from the hydraulic actuator, and the flow rate thereof is controlled.
  • the hydraulic drive device of the present embodiment includes a traveling operation device 22A for operating the traveling control valve 16A, a traveling operating device 22B for operating the traveling control valve 16B, boom control valves 19A, 19B, and bucket control.
  • the traveling operation device 22A includes an operation lever that can be operated by the operator in the front-rear direction, a first pilot valve that generates a pilot pressure according to the amount of operation on the front side from the neutral position of the operation lever, and an operation lever. It has a second pilot valve that generates pilot pressure according to the amount of operation on the rear side from the neutral position. Then, the pilot pressure generated by the first pilot valve is output to the pressure receiving portion on one side of the traveling control valve 16A, and the traveling control valve 16A is switched from the neutral position to the switching position on one side.
  • the pilot pressure generated by the second pilot valve is output to the pressure receiving portion on the other side of the traveling control valve 16A to switch the traveling control valve 16A from the neutral position to the switching position on the other side.
  • the traveling motor 4A is driven by supplying and discharging pressure oil.
  • the pressure sensors 25A and 25B detect the pilot pressures of the first pilot valve and the second pilot valve corresponding to the operation amounts on the front side and the rear side of the traveling operation device 22A, respectively.
  • the traveling operation device 22B includes an operation lever that can be operated by the operator in the front-rear direction, a third pilot valve that generates a pilot pressure according to the amount of operation on the front side from the neutral position of the operation lever, and an operation lever. It has a fourth pilot valve that generates pilot pressure according to the amount of operation on the rear side from the neutral position. Then, the pilot pressure generated by the third pilot valve is output to the pressure receiving portion on one side of the traveling control valve 16B, and the traveling control valve 16B is switched from the neutral position to the switching position on one side.
  • the pilot pressure generated by the fourth pilot valve is output to the pressure receiving portion on the other side of the traveling control valve 16B to switch the traveling control valve 16B from the neutral position to the switching position on the other side.
  • the traveling motor 4B is driven by supplying and discharging pressure oil.
  • the pressure sensors 25C and 25D detect the pilot pressures of the third pilot valve and the fourth pilot valve corresponding to the operation amounts on the front side and the rear side of the traveling operation device 22B, respectively.
  • the work operation device 23A includes an operation lever that can be operated by the operator in the front-rear direction and the left-right direction, and a fifth pilot valve that generates a pilot pressure according to the operation amount on the front side from the neutral position of the operation lever.
  • the sixth pilot valve that generates pilot pressure according to the amount of operation on the rear side from the neutral position of the operating lever, and the seventh pilot valve that generates pilot pressure according to the amount of operation on the left side from the neutral position of the operating lever. It has an eighth pilot valve that generates pilot pressure according to the amount of operation on the right side from the neutral position of the lever.
  • the pilot pressure generated by the fifth pilot valve is output to the pressure receiving portion on one side of the arm control valves 18A and 18B, and the arm control valves 18A and 18B are switched from the neutral position to the switching position on one side.
  • the pilot pressure generated by the sixth pilot valve is output to the pressure receiving portion on the other side of the arm control valves 18A and 18B, and the arm control valves 18A and 18B are switched from the neutral position to the switching position on the other side.
  • the arm cylinder 10 is driven by supplying and discharging pressure oil.
  • the pressure sensors 25E and 25F (operation amount detectors) detect the pilot pressures of the fifth pilot valve and the sixth pilot valve corresponding to the operation amounts on the front side and the rear side of the working operation device 23A, respectively.
  • the working operation device 23A outputs the pilot pressure generated by the seventh pilot valve to the pressure receiving portion on one side of the swivel control valve 20 to switch the swivel control valve 20 from the neutral position to the switching position on one side. ..
  • the pilot pressure generated by the eighth pilot valve is output to the pressure receiving portion on the other side of the swivel control valve 20 to switch the swivel control valve 20 from the neutral position to the switching position on the other side.
  • the swivel motor 5 is driven by supplying and discharging pressure oil.
  • the pressure sensors 25G and 25H (operation amount detectors) detect the pilot pressures of the 11th pilot valve and the 12th pilot valve corresponding to the operation amounts on the left side and the right side of the working operation device 23A, respectively.
  • the work operation device 23B includes an operation lever that can be operated by the operator in the front-rear direction and the left-right direction, and a ninth pilot valve that generates a pilot pressure according to the operation amount on the front side from the neutral position of the operation lever.
  • the tenth pilot valve that generates pilot pressure according to the amount of operation on the rear side from the neutral position of the operating lever, and the eleventh pilot valve that generates pilot pressure according to the amount of operation on the left side from the neutral position of the operating lever. It has a twelfth pilot valve that generates pilot pressure according to the amount of operation on the right side from the neutral position of the lever.
  • the pilot pressure generated by the ninth pilot valve is output to the pressure receiving portion on one side of the boom control valves 19A and 19B, and the boom control valves 19A and 19B are switched from the neutral position to the switching position on one side.
  • the pilot pressure generated by the tenth pilot valve is output to the pressure receiving portion on the other side of the boom control valves 19A and 19B, and the boom control valves 19A and 19B are switched from the neutral position to the switching position on the other side.
  • the boom cylinder 9 is driven by supplying and discharging pressure oil.
  • the pressure sensors 25I and 25J (operation amount detector) detect the pilot pressures of the 9th pilot valve and the 10th pilot valve corresponding to the operation amount on the front side and the rear side of the working operation device 23B, respectively.
  • the working operation device 23B outputs the pilot pressure generated by the 11th pilot valve to the pressure receiving portion on one side of the bucket control valve 17 to switch the bucket control valve 17 from the neutral position to the switching position on one side. ..
  • the pilot pressure generated by the 12th pilot valve is output to the pressure receiving portion on the other side of the bucket control valve 17, and the bucket control valve 17 is switched from the neutral position to the switching position on the other side.
  • the bucket cylinder 11 is driven by supplying and discharging pressure oil.
  • the pressure sensors 25K and 25L (operation amount detector) detect the pilot pressures of the 11th pilot valve and the 12th pilot valve corresponding to the operation amount on the left side and the right side of the working operation device 23B, respectively.
  • the optional operation device 24 includes an operation lever that can be operated by the operator, a thirteenth pilot valve that generates a pilot pressure according to the amount of operation on one side from the neutral position of the operation lever, and a neutral position of the operation lever. It has a 14th pilot valve that generates a pilot pressure according to the amount of operation on the other side. Then, the pilot pressure generated by the 13th pilot valve is output to the pressure receiving portion on one side of the option control valve 21, and the option control valve 21 is switched from the neutral position to the switching position on one side. Alternatively, the pilot pressure generated by the 14th pilot valve is output to the pressure receiving portion on the other side of the option control valve 21, and the option control valve 21 is switched from the neutral position to the switching position on the other side.
  • the optional hydraulic actuator is driven by supplying and discharging pressure oil.
  • the pressure sensors 25M and 25N (operation amount detector) detect the pilot pressures of the 13th pilot valve and the 14th pilot valve corresponding to the operation amount on one side and the other side of the optional operation device 24, respectively.
  • the hydraulic drive system of the present embodiment includes regulators 26A and 26B that variably control the capacities of the hydraulic pumps 14A and 14B, and a bleed that returns the pressure oil supplied from the hydraulic pumps 14A to the control valves 16A, 17, 18A and 19A to the tank.
  • the bleed-off valve 28A arranged in the off-line 27A and the bleed-off placed in the bleed-off line 27B that returns the pressure oil supplied from the hydraulic pump 14B to the control valves 20, 19B, 18B, 21, 16B to the tank. It includes a valve 28B and a controller 30 that controls the regulators 26A and 26B and also controls the bleed-off valves 28A and 28B via the electromagnetic proportional valves 29A and 29B.
  • the regulator 26A has a tilting cylinder that changes the tilting angle of the swash plate of the hydraulic pump 14A, and a solenoid valve.
  • This solenoid valve is operated by a pump command current (first command current) from the controller 30 to control the operating pressure of the tilting cylinder.
  • first command current first command current
  • the regulator 26B has a tilting cylinder that changes the tilting angle of the swash plate of the hydraulic pump 14B, and a solenoid valve.
  • This solenoid valve is operated by a pump command current (first command current) from the controller 30 to control the operating pressure of the tilting cylinder.
  • first command current first command current
  • the electromagnetic proportional valve 29A operates by the bleed-off command current (second command current) from the controller 30, generates a bleed-off control pressure, and outputs the bleed-off control pressure.
  • the bleed-off valve 28A is operated by the bleed-off control pressure from the electromagnetic proportional valve 29A, and the opening degree (opening area) is variable.
  • the electromagnetic proportional valve 29B operates by the bleed-off command current (second command current) from the controller 30 to generate and output the bleed-off control pressure.
  • the bleed-off valve 28B is operated by the bleed-off control pressure from the electromagnetic proportional valve 29B, and the opening degree (opening area) is variable.
  • FIG. 4 is a block diagram showing a functional configuration of the controller according to the present embodiment.
  • the controller 30 has a control unit (for example, a CPU) that executes arithmetic processing and control processing based on a program, and a storage unit (for example, ROM, RAM) that stores the program and the processing result.
  • the controller 30 includes a pump control unit 31A, a bleed-off control unit 32A, a decoefficient calculation unit 33A, and an output unit 34A related to the hydraulic pump 14A, and a pump control unit 31B and a bleed-off control related to the hydraulic pump 14B. It has a unit 32B, a decoefficient calculation unit 33B, and an output unit 34B.
  • the pump control unit 31A considers the target flow rate of the pump (however, the opening degree of the bleed-off valve 28A) based on the pilot pressure detected by the pressure sensors 25A, 25B, 25K, 25L and the pressure sensors 25E, 25F, 25I, 25J. Calculates the corrected target flow rate of the pump), selects the maximum of the calculated target flow rates, generates a pump command current corresponding to this pump target flow rate, and outputs it to the electromagnetic valve of the regulator 26A. ..
  • the bleed-off control unit 32A is based on the pilot pressure detected by the pressure sensors 25A, 25B, 25K, 25L and the pressure sensors 25E, 25F, 25I, 25J, for example, from the pilot pressure using the calculation table shown in FIG. Calculate the bleed-off control pressure. Then, the maximum bleed-off control pressure calculated is selected, and the bleed-off command current corresponding to this bleed-off control pressure is calculated.
  • the decoefficient calculation unit 33A selects the maximum of the pilot pressures detected by the pressure sensors 25A, 25B, 25K, 25L and the pressure sensors 25E, 25F, 25I, 25J, and reduces the pilot pressure (that is, the reduction rate). Calculate the rate of decrease in the amount of operation of the operating device).
  • the pilot pressure Pa is selected at the previous time ta and the pilot pressure Pb (however, Pb ⁇ Pa) is selected at the current time tb
  • the reduction rate of the pilot pressure is (Pa-Pb) / (tb-).
  • the bleed-off command current output from the output unit 34A to the electromagnetic proportional valve 29A is reduced, and the bleed-off control pressure generated by the electromagnetic proportional valve 29A is reduced.
  • the opening degree of the bleed-off valve 28A can be increased so as to compensate for the response delay of the bleed-off valve 28A.
  • the subtraction factor calculation unit 33A further limits the speed at which the reduction factor C rises. Specifically, a low-pass filter is used when the reduction coefficient C rises, and the reduction coefficient C is limited so that the rate of increase of the reduction coefficient C is equal to or less than a predetermined value. Thereby, the opening degree control of the bleed-off valve 28A can be stabilized.
  • the pump control unit 31B sets the target flow rate of the pump (however, the bleed-off valve 28A) based on the pilot pressure detected by the pressure sensors 25C, 25D, 25G, 25H, 25M, 25N and the pressure sensors 25E, 25F, 25I, 25J.
  • the target flow rate of the pump corrected in consideration of the opening degree) is calculated, the maximum of the calculated target flow rates is selected, the pump command current corresponding to this pump target flow rate is generated, and the electromagnetic wave of the regulator 26B Output to the valve.
  • the bleed-off control unit 32B uses, for example, the calculation table shown in FIG. 5 based on the pilot pressure detected by the pressure sensors 25C, 25D, 25G, 25H, 25M, 25N and the pressure sensors 25E, 25F, 25I, 25J. , Calculate the bleed-off control pressure from the pilot pressure. Then, the maximum bleed-off control pressure calculated is selected, and the bleed-off command current corresponding to this bleed-off control pressure is calculated.
  • the reduction coefficient C is lowered as the difference between the reduction rate of the pilot pressure and the predetermined value D becomes larger.
  • the bleed-off command current output from the output unit 34B to the electromagnetic proportional valve 29B is reduced, and the bleed-off control pressure generated by the electromagnetic proportional valve 29B is reduced.
  • the opening degree of the bleed-off valve 28B can be increased so as to compensate for the response delay of the bleed-off valve 28B.
  • the subtraction factor calculation unit 33B further limits the speed at which the reduction factor C rises. Specifically, a low-pass filter is used when the reduction coefficient C rises, and the reduction coefficient C is limited so that the rate of increase of the reduction coefficient C is equal to or less than a predetermined value. Thereby, the opening degree control of the bleed-off valve 28B can be stabilized.
  • the bleed-off is compared with the case where the reduction speed of the pilot pressure is not more than the predetermined value.
  • the bleed-off command current is corrected so that the valve opening becomes large.
  • the response delay of the bleed-off valve can be improved and the pump pressure can be prevented from being trapped.
  • the durability of hydraulic equipment such as hydraulic pumps can be improved. Further, it is possible to suppress an adverse effect on the deceleration or stop of the hydraulic actuator (particularly, the swivel motor 5).
  • the opening control of the bleed-off valve can be stabilized.
  • FIG. 8 is a diagram showing changes over time in the pilot pressure, the bleed-off control pressure, and the opening degree of the bleed-off valve in the first comparative example (when the bleed-off command current is not corrected).
  • FIG. 9 is a diagram showing changes over time in the pilot pressure, the bleed-off control pressure, and the opening degree of the bleed-off valve in the present embodiment.
  • the pilot pressure decreases.
  • the bleed-off control pressure calculated by the bleed-off control unit of the controller 30 also decreases in proportion to the pilot pressure.
  • the command current corresponding to the bleed-off control pressure is output as it is (in other words, as shown in the figure, the bleed-off control pressure is kept as it is) and output from the controller 30 to the electromagnetic proportional valve, the bleed is generated.
  • the actual opening of the off-valve increases with a considerable delay. Therefore, the opening degree (opening area) of the bleed-off valve is temporarily insufficient, and the pump pressure is bound.
  • the reduction rate of the pilot pressure during the time t1 to t3 is calculated, the reduction coefficient is calculated based on the reduction rate of the pilot pressure, and the bleed-off command current is calculated using this reduction coefficient.
  • the bleed-off control pressure is corrected
  • the command current is output from the controller 30 to the electromagnetic proportional valve, the response delay of the bleed-off valve can be improved. Therefore, it is possible to prevent the pump pressure from being bound.
  • FIG. 10 is a diagram showing changes over time in the pilot pressure, the reduction coefficient, the bleed-off control pressure, and the theoretical opening degree of the bleed-off valve in the second comparative example (when the speed at which the reduction coefficient increases is not limited).
  • FIG. 11 is a diagram showing changes over time in the pilot pressure, the reduction coefficient, the bleed-off control pressure, and the theoretical opening degree of the bleed-off valve in the present embodiment.
  • the reduction factor C1 is calculated based on the rate of decrease in pilot pressure between times t1 and t3, and the reduction factor C2 is calculated based on the rate of decrease in pilot pressure between times t3 and t4.
  • C3 is calculated based on the decrease rate of the pilot pressure
  • C4 is calculated based on the decrease rate of the pilot pressure during the time t5 to t6, and the relationship is C2> C4> C3> C1. Is assumed. In this case, in particular, at time t4, the decompression coefficient C1 is remarkably increased to the decrement coefficient C2. Therefore, as shown in FIG.
  • the opening degree of the bleed-off valve becomes unstable.
  • the opening degree of the bleed-off valve can be stabilized by suppressing the speed at which the reduction coefficient C1 rises to the reduction coefficient C2.
  • the controller 30 multiplies the reduction coefficient C smaller than 1 to give a bleed-off command.
  • the case of correcting the current has been described as an example, but the present invention is not limited to this, and deformation is possible within a range that does not deviate from the gist of the present invention.
  • the controller may correct the bleed-off command current by subtracting a correction amount larger than 0.
  • the correction amount may be increased as the difference between the decrease rate of the pilot pressure and the predetermined value increases. Further, the speed at which the correction amount decreases may be limited.
  • the hydraulic excavator includes electromagnetic proportional valves 29A and 29B that are operated by a bleed-off command current from the controller 30 to generate a bleed-off control pressure, and the bleed-off valves 28A and 28B are electromagnetically proportional.
  • the operation is performed by the bleed-off control pressure from the valves 29A and 29B has been described as an example, but the present invention is not limited to this, and the deformation is possible within a range not deviating from the gist of the present invention.
  • the bleed-off valve may be actuated by a command current from the controller.
  • the hydraulic excavator is provided as an operation amount detector with a pressure sensor for detecting the pilot pressure corresponding to the operation amount of the operation device
  • the hydraulic excavator may include, for example, a displacement sensor that detects the operation amount of the operation lever as the operation amount detector.

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  • 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)
  • Operation Control Of Excavators (AREA)
  • Fluid-Pressure Circuits (AREA)

Abstract

L'invention concerne une machine de travail qui est susceptible d'empêcher le piégeage de la pression de la pompe.　Une pelle hydraulique comprend : une soupape de commande qui commande l'écoulement d'huile sous pression, d'une pompe hydraulique à un actionneur hydraulique ; un dispositif d'actionnement pour faire fonctionner la soupape de commande ; un capteur de pression qui détecte une pression pilote qui correspond à une quantité de fonctionnement du dispositif d'actionnement ; un régulateur qui commande de manière variable une capacité de la pompe hydraulique ; une soupape de purge disposée sur une conduite de purge qui renvoie l'huile sous pression fournie à la soupape de commande, de la pompe hydraulique vers un réservoir ; et un dispositif de commande qui délivre en sortie, en fonction de la pression pilote détectée par le capteur de pression, un courant d'instruction pour pompe pour commander la capacité de la pompe hydraulique et un courant d'instruction de purge pour commander un degré d'ouverture de la soupape de purge. Dans un cas où un taux de diminution de la pression pilote est supérieur à une valeur prédéfinie, le dispositif de commande corrige le courant d'instruction de purge, de telle sorte que le degré d'ouverture de la soupape de purge augmente.
PCT/JP2020/017249 2019-09-27 2020-04-21 Machine de travail WO2021059571A1 (fr)

Applications Claiming Priority (2)

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JP2019-177340 2019-09-27
JP2019177340A JP7184725B2 (ja) 2019-09-27 2019-09-27 作業機械

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WO2021059571A1 true WO2021059571A1 (fr) 2021-04-01

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10147959A (ja) * 1996-11-20 1998-06-02 Yutani Heavy Ind Ltd 油圧モータの制御装置
JP5886976B2 (ja) * 2012-10-18 2016-03-16 日立建機株式会社 作業機械
JP2018048503A (ja) * 2016-09-23 2018-03-29 日立建機株式会社 建設機械の制御装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10147959A (ja) * 1996-11-20 1998-06-02 Yutani Heavy Ind Ltd 油圧モータの制御装置
JP5886976B2 (ja) * 2012-10-18 2016-03-16 日立建機株式会社 作業機械
JP2018048503A (ja) * 2016-09-23 2018-03-29 日立建機株式会社 建設機械の制御装置

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