WO2023033080A1 - 建設機械 - Google Patents
建設機械 Download PDFInfo
- Publication number
- WO2023033080A1 WO2023033080A1 PCT/JP2022/032866 JP2022032866W WO2023033080A1 WO 2023033080 A1 WO2023033080 A1 WO 2023033080A1 JP 2022032866 W JP2022032866 W JP 2022032866W WO 2023033080 A1 WO2023033080 A1 WO 2023033080A1
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- WIPO (PCT)
- Prior art keywords
- boom
- pressure
- command value
- control valve
- valve
- Prior art date
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- 238000010276 construction Methods 0.000 title claims abstract description 24
- 230000007423 decrease Effects 0.000 claims abstract description 25
- 238000004891 communication Methods 0.000 claims abstract description 18
- 238000007599 discharging Methods 0.000 claims 1
- 239000003921 oil Substances 0.000 description 71
- 238000000034 method Methods 0.000 description 15
- 239000010720 hydraulic oil Substances 0.000 description 13
- 230000007935 neutral effect Effects 0.000 description 8
- 230000008569 process Effects 0.000 description 7
- 230000003247 decreasing effect Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 230000006870 function Effects 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 230000004044 response Effects 0.000 description 3
- 230000000903 blocking effect Effects 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000009412 basement excavation Methods 0.000 description 1
- 238000010009 beating Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
Images
Classifications
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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
- E02F9/2221—Control of flow rate; Load sensing arrangements
- E02F9/2239—Control of flow rate; Load sensing arrangements using two or more pumps with cross-assistance
- E02F9/2242—Control of flow rate; Load sensing arrangements using two or more pumps with cross-assistance including an electronic controller
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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
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F3/00—Dredgers; Soil-shifting machines
- E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
- E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
- E02F3/30—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets with a dipper-arm pivoted on a cantilever beam, i.e. boom
- E02F3/32—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets with a dipper-arm pivoted on a cantilever beam, i.e. boom working downwardly and towards the machine, e.g. with backhoes
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- 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
- E02F3/425—Drive systems for dipper-arms, backhoes or the like
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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
- E02F9/2221—Control of flow rate; Load sensing arrangements
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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
- E02F9/2278—Hydraulic circuits
- E02F9/2285—Pilot-operated systems
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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
- E02F9/2278—Hydraulic circuits
- E02F9/2292—Systems with two or more pumps
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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
- E02F9/2278—Hydraulic circuits
- E02F9/2296—Systems with a variable displacement pump
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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
- F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
- F15B11/028—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60Y—INDEXING SCHEME RELATING TO ASPECTS CROSS-CUTTING VEHICLE TECHNOLOGY
- B60Y2200/00—Type of vehicle
- B60Y2200/40—Special vehicles
- B60Y2200/41—Construction vehicles, e.g. graders, excavators
- B60Y2200/412—Excavators
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- 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
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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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
- F15B2211/205—Systems with pumps
- F15B2211/20576—Systems with pumps with multiple pumps
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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
- 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
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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
- 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
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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
- 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
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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
- 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
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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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/35—Directional control combined with flow control
- F15B2211/351—Flow control by regulating means in feed line, i.e. meter-in control
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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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/355—Pilot pressure control
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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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/63—Electronic controllers
- F15B2211/6303—Electronic controllers using input signals
- F15B2211/6306—Electronic controllers using input signals representing a pressure
- F15B2211/6313—Electronic controllers using input signals representing a pressure the pressure being a load pressure
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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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/63—Electronic controllers
- F15B2211/6303—Electronic controllers using input signals
- F15B2211/6346—Electronic controllers using input signals representing a state of input means, e.g. joystick position
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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
- 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
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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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/665—Methods of control using electronic components
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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
- F15B2211/00—Circuits for servomotor systems
- F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
- F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
- F15B2211/7051—Linear output members
- F15B2211/7053—Double-acting output members
Definitions
- the present invention relates to construction machinery such as hydraulic excavators.
- Construction machines such as hydraulic excavators perform a variety of work, such as soil plowing and leveling, in addition to excavation work.
- the flow rate and pressure of pressurized oil required to drive the boom cylinder vary depending on the work.
- the meter-in flow rate to the boom cylinder is increased by, for example, merging the discharge oil of a plurality of hydraulic pumps.
- the boom lowering operation is performed with the bucket floating in the air, the energy loss is suppressed by limiting the meter-in flow rate to the boom cylinder.
- the meter-in flow rate to the boom cylinder is increased to enable the jack-up operation.
- Such control of the meter-in flow rate to the boom cylinder is performed, for example, by controlling the flow rate of pressurized oil supplied to the boom cylinder with an electromagnetic valve according to the bottom pressure of the boom cylinder (Patent Document 1).
- the meter-in flow rate corresponding to the jack-up operation is selected even after switching from the boom raising operation to the boom lowering operation. and high meter-in flow may continue. As a result, maneuverability can be affected by inconsistent conditions with required boom operating speeds.
- An object of the present invention is to provide a construction machine capable of matching the operating speed of the boom to the required speed and improving operability.
- the present invention provides a vehicle body, a front working machine connected to the vehicle body, a boom cylinder for vertically driving the front working machine, a prime mover, and a first hydraulic system driven by the prime mover.
- a second hydraulic pump driven by the prime mover; a first directional control valve for controlling pressure oil flowing from the first hydraulic pump to the boom cylinder; and pressure flowing from the second hydraulic pump to the boom cylinder.
- a second directional control valve that controls oil; a pilot pump that discharges pilot oil that drives the first directional control valve and the second directional control valve; and the first directional control valve using the pilot oil as a source pressure and a boom lowering pressure reducing valve that outputs a boom lowering pilot pressure that drives the second directional control valve in the boom lowering direction, and a boom lowering pressure reducing valve that uses the pilot oil as a source pressure to operate the first directional control valve and the second directional control valve as a boom
- a construction machine comprising a boom raising pressure reducing valve for outputting a boom raising pilot pressure for driving in a raising direction, and a boom operating lever for operating the boom lowering pressure reducing valve and the boom raising pressure reducing valve, wherein the bottom pressure of the boom cylinder is reduced.
- a solenoid valve for reducing boom lowering pilot pressure for a directional control valve for a directional control valve; and a controller for controlling the solenoid valve based on the bottom pressure measured by the bottom pressure sensor and the manipulated variable measured by the manipulated variable sensor. , based on the bottom pressure measured by the bottom pressure sensor, the controller controls the communication area between the boom lowering pressure reducing valve and the pressure receiving chamber of the second directional control valve to decrease as the bottom pressure increases.
- a first opening command value is calculated, and a second opening command value is calculated based on the boom lowering operation amount measured by the operation amount sensor so that the communication area increases as the boom lowering operation amount increases.
- the minimum opening command value that minimizes the communication area is calculated, and if the elapsed time is the set time or more, A minimum selected value of the first opening command value and the second opening command value is determined as the opening command value of the electromagnetic valve, and a command signal corresponding to the determined opening command value is output to the electromagnetic valve.
- the operating speed of the boom can be made to match the required speed, and operability can be improved.
- FIG. 1 is a side view showing a construction machine according to one embodiment of the present invention
- FIG. 1 is a circuit diagram showing a main part of a hydraulic system mounted on a construction machine according to one embodiment of the present invention
- FIG. 1 is a flow chart showing a control procedure of a solenoid valve by a controller mounted on a construction machine according to one embodiment of the present invention
- 4 is a diagram showing an example of functional blocks of a controller for executing the flow of FIG. 3;
- FIG. 1 is a side view showing a construction machine according to one embodiment of the invention.
- a hydraulic excavator 1 is exemplified as a construction machine, but the present invention can be applied to other types of construction machines such as wheel loaders, cranes, and the like, which are used for various works such as civil engineering work, construction work, demolition work, and the like. be.
- the hydraulic excavator 1 is of a crawler type, the present invention can also be applied to wheel-type construction machines.
- the hydraulic excavator 1 includes a vehicle body 4 and a front working machine 10 attached to the vehicle body 4 .
- the vehicle body 4 includes a running body 2 and a revolving body 3 provided on the running body 2 so as to be able to turn.
- the traveling body 2 travels by driving the left and right crawlers with a traveling hydraulic motor.
- the revolving body 3 has a cab 7 in which an operator rides, and is driven to revolve with respect to the traveling body 2 by a revolving hydraulic motor provided in the vehicle body 4 .
- the front working machine 10 is a working machine having a multi-joint working arm 11 and a bucket 14 as an attachment corresponding to the work, and is connected to the revolving body 3 .
- the working arm 11 includes a boom 12 connected to the front portion of the revolving body 3 so as to be able to rotate vertically, and an arm 13 connected to the tip of the boom 12 so as to be able to rotate forward and backward.
- the boom 12 is driven by a boom cylinder 15, the arm 13 by an arm cylinder 16, and the bucket 14 by a bucket cylinder 17, respectively.
- FIG. 1 illustrates a configuration in which the bucket 14 is attached to the working arm 11 as an attachment, the bucket 14 can be replaced with other attachments such as a grapple.
- FIG. 2 is a circuit diagram showing the essential parts of the hydraulic system mounted on the construction machine shown in FIG. In FIG. 2, the drive circuit of the boom cylinder 15 is extracted and shown.
- the hydraulic system shown in FIG. a controller 60 .
- the first hydraulic pump 52 and the second hydraulic pump 53 are variable displacement pumps that discharge working oil for driving hydraulic actuators mounted on the hydraulic excavator 1 , and are driven by the prime mover 51 .
- the prime mover 51 in the present embodiment is an engine such as an internal combustion engine that converts combustion energy into power, but an electric motor may be used as the prime mover 51 in some cases.
- only one each of the first hydraulic pump 52 and the second hydraulic pump 53 is shown in FIG. 2, at least one of the first hydraulic pump 52 and the second hydraulic pump 53 may be plural. Pressure oil sucked from the hydraulic oil tank 59 and discharged from the first hydraulic pump 52 is supplied to the boom cylinder 15 via the first direction control valve 54 .
- Pressure oil sucked from the hydraulic oil tank 59 and discharged from the second hydraulic pump 53 is supplied to the boom cylinder 15 via the second direction control valve 55 .
- Return oil from the boom cylinder 15 returns to the hydraulic oil tank 59 via the first direction control valve 54 and the second direction control valve 55 .
- the pilot pump 56 is a fixed displacement pump that discharges pilot oil for driving hydraulically driven control valves such as the first direction control valve 54 and the second direction control valve 55 . Like the first hydraulic pump 52 and the second hydraulic pump 53 , the pilot pump 56 is driven by the prime mover 51 . A configuration in which the pilot pump 56 is driven by a power source other than the prime mover 51 is also possible. A discharge oil passage 56m of the pilot pump 56 is branched and connected to the boom lowering pressure reducing valve 57d and the boom raising pressure reducing valve 57u of the operation lever device 57, and the like. The discharge pressure of the pilot pump 56 is input to the boom lowering pressure reducing valve 57d, the boom raising pressure reducing valve 57u and the like via the discharge pipe line 57a as the source pressure of the pilot pressure.
- the first direction control valve 54 is a hydraulically driven direction switching valve that controls the flow (direction and flow rate) of pressure oil supplied from the first hydraulic pump 52 to the boom cylinder 15, and receives pressure. It is driven by pilot pressure input to the chamber.
- the first directional control valve 54 is a proportional three-position switching valve having a boom down position 54d, a boom up position 54u, and a neutral position 54n. When the pilot pressure is not acting, the spool of the first directional control valve 54 is positioned at the neutral position 54n by spring force.
- the first hydraulic pump 52 bypasses the boom cylinder 15 and connects to the hydraulic oil tank 59, and the rod side oil chamber and the bottom side oil chamber of the boom cylinder 15 are closed. be done. As a result, the boom cylinder 15 is held without extending or contracting.
- the first hydraulic pump 52 bypasses the boom cylinder 15 and connects to the hydraulic oil tank 59, and the bottom side oil chamber of the boom cylinder 15 is connected to the rod side oil chamber and the rod side oil chamber. It is connected to the hydraulic oil tank 59 .
- part of the pressurized oil pushed away from the bottom-side oil chamber by the weight of the front work implement 10 is supplied to the rod-side oil chamber, and the boom cylinder 15 contracts.
- the first hydraulic pump 52 When the first directional control valve 54 is at the boom raising position 54 u, the first hydraulic pump 52 connects to the bottom side oil chamber of the boom cylinder 15 and the rod side oil chamber of the boom cylinder 15 connects to the hydraulic oil tank 59 . As a result, the boom cylinder 15 is extended by the pressurized oil discharged from the first hydraulic pump 52 .
- the second direction control valve 55 is a hydraulically driven directional switching valve that controls the flow (direction and flow rate) of pressure oil supplied from the second hydraulic pump 53 to the boom cylinder 15, and receives pressure. It is driven by pilot pressure input to the chamber.
- the second directional control valve 55 is a proportional three-position switching valve having a boom down position 55d, a boom up position 55u, and a neutral position 55n. When the pilot pressure is not acting, the spool of the second directional control valve 55 is positioned at the neutral position 55n by spring force.
- the second hydraulic pump 53 bypasses the boom cylinder 15 and connects to the hydraulic oil tank 59, and the rod side oil chamber and the bottom side oil chamber of the boom cylinder 15 are closed. be done. As a result, the boom cylinder 15 is held without extending or contracting.
- the second hydraulic pump 53 When the second directional control valve 55 is at the boom lowering position 55d, the second hydraulic pump 53 is connected to the rod side oil chamber of the boom cylinder 15, and the bottom side oil chamber of the boom cylinder 15 is connected to the hydraulic oil tank 59. As a result, the boom cylinder 15 is contracted by the pressurized oil discharged from the second hydraulic pump 53 .
- the second hydraulic pump 53 When the second directional control valve 55 is at the boom raising position 55u, the second hydraulic pump 53 is connected to the bottom side oil chamber of the boom cylinder 15, and the rod side oil chamber of the boom cylinder 15 is connected to the hydraulic oil tank 59. As a result, the boom cylinder 15 is extended by the pressurized oil discharged from the second hydraulic pump 53 .
- the pressure receiving chambers on the boom lowering side of the first directional control valve 54 and the second directional control valve 55 are connected to the boom lowering pressure reducing valve 57d via pilot oil passages 56a and 56b, respectively, and the boom lowering pressure reducing valve It is connected to the pilot pump 56 via the valve 57d.
- the boom lowering pressure reducing valve 57d is operated by the boom operating lever 57l. When the boom operating lever 57l is operated in the boom lowering direction (to the left in FIG. 2), the boom lowering pressure reducing valve 57d operates according to the amount of operation of the boom operating lever 57l.
- the discharge oil passage 56m of the pilot pump 56 and the pilot oil passages 56a, 56b are connected, and the pressure of the pilot oil from the pilot pump 56 is used as the source pressure, and the boom lowering operation amount of the boom control lever 57l is controlled.
- Boom down pilot pressure is output.
- this pilot pressure acts on the pressure receiving chambers of the first directional control valve 54 and the second directional control valve 55 on the boom lowering side, the first directional control valve 54 and the second directional control valve 55 move from the neutral positions 54n and 55n to the boom lowering position. direction to switch to boom down positions 54d and 55d.
- Boom raising pressure reducing valve The pressure receiving chambers on the boom raising side of the first directional control valve 54 and the second directional control valve 55 are connected to the boom raising pressure reducing valve 57u via pilot oil passages 56c and 56d, respectively, and the boom raising pressure reducing valve It is connected to the pilot pump 56 via the valve 57u. Like the boom lowering pressure reducing valve 57d, the boom raising pressure reducing valve 57u is also operated by the boom operating lever 57l. When the boom operating lever 57l is operated in the boom raising direction (to the right in FIG. 2), the boom raising pressure reducing valve 57u operates according to the amount of operation of the boom operating lever 57l.
- pilot pressure is output.
- this pilot pressure acts on the pressure receiving chambers of the first directional control valve 54 and the second directional control valve 55 on the boom raising side, the first directional control valve 54 and the second directional control valve 55 move from the neutral positions 54n and 55n to the boom raising position. direction to switch to boom raised positions 54u and 55u.
- the electromagnetic valve 58 reduces the boom lowering pilot pressure output by the boom lowering pressure reducing valve 57d, and the corrected boom lowering pilot pressure (corrected boom lowering) to the pressure receiving chamber on the boom lowering side of the second directional control valve 55 It is a proportional electromagnetic pressure reducing valve that outputs pilot pressure).
- the solenoid valve 58 is provided in a pilot oil passage 56b that connects the boom lowering pressure reducing valve 57d and the pressure receiving chamber of the second directional control valve 55 on the boom lowering side.
- the solenoid valve 58 has an open position 58a and a closed position 58b.
- the spool of the solenoid valve 58 is pushed toward the shutoff position 58b by spring force when the solenoid is deenergized, and moves toward the open position 58a against the spring force when the solenoid is energized.
- the configuration may be such that the spool is pressed against the open position 58a in the demagnetized state, and the spool moves toward the cutoff position 58b when excited.
- the solenoid valve 58 is a two-position valve that is switchable between an open position 58a and a cutoff position 58b.
- the solenoid valve 58 is switched to the open position 58a, the pressure receiving chamber on the boom lowering side of the second direction control valve 55 is connected to the boom lowering pressure reducing valve 57d.
- the solenoid valve 58 is switched to the blocking position 58b, the pressure receiving chamber of the second directional control valve 55 on the boom lowering side is connected to the hydraulic oil tank 59. As shown in FIG.
- the opening area connecting the pressure receiving chamber of the second direction control valve 55 to the boom lowering pressure reducing valve 57d and the opening area connecting the pressure receiving chamber to the hydraulic oil tank 59 are determined.
- the ratio to the area changes.
- the reduction amount of the boom lowering pilot pressure can be adjusted by the ratio of the opening area, and the corrected boom lowering pilot pressure for the second directional control valve 55 can be controlled.
- the larger the amount of pressure reduction by the solenoid valve 58 of the boom lowering pilot pressure for the second directional control valve 55 (the smaller the corrected boom lowering pilot pressure), the more the second directional control valve 55 moves in the boom lowering direction even with the same boom lowering operation amount.
- the boom lowering pilot pressure does not act on the second direction control valve 55, and even if the boom lowering operation is performed, the second hydraulic pump 53 , pressure oil is no longer supplied to the rod-side oil chamber of the boom cylinder 15 .
- the solenoid valve 58 is completely switched to the open position 58a, the reduction amount of the boom lowering pilot pressure is minimized.
- the second direction control valve 55 operates in response to the boom lowering operation amount to the same extent as the first direction control valve 54 , and pressurized oil is supplied from the second hydraulic pump 53 to the rod-side oil chamber of the boom cylinder 15 . be.
- the operation amount of the boom control lever 57l is measured by operation amount sensors S3 and S4.
- the operation amount sensor S3 measures the boom lowering operation amount Ad
- the operation amount sensor S3 measures the boom raising operation amount Au.
- Both of the operation amount sensors S3 and S4 are pressure sensors.
- the manipulated variable sensor S3 connects the boom lowering pressure reducing valve 57d to the pressure receiving chamber on the boom lowering side of the first directional control valve 54 and the solenoid valve 58 (for example, the output port of the boom lowering pressure reducing valve 57d or the immediately downstream).
- the boom lowering operation amount Ad is measured by measuring the boom lowering pilot pressure with the operation amount sensor S3.
- the operation amount sensor S4 is controlled by a pilot oil passage 56c or 56d (for example, the output of the boom raising pressure reducing valve 57u) connecting the boom raising pressure reducing valve 57u to the pressure receiving chambers of the first direction control valve 54 and the second direction control valve 55 on the boom raising side. port or immediately downstream thereof).
- the boom raising operation amount Au is measured by measuring the boom raising pilot pressure with the operation amount sensor S4. Potentiometers or the like may be used as the operation amount sensors S3 and S4 in place of the pressure sensors, and the angle of the boom operation lever 57l may be measured to measure the boom lowering operation amount Ad and the boom raising operation amount Au.
- the bottom pressure Pb of the boom cylinder 15 (the pressure of the bottom side oil chamber) is measured by the bottom pressure sensor S1.
- the bottom pressure sensor S1 is provided in an oil passage connecting the bottom side oil chamber of the boom cylinder 15 to the first direction control valve 54 and the second direction control valve 55 (for example, the input/output port of the bottom side oil chamber or its vicinity). A pressure sensor.
- the rod pressure Pr of the boom cylinder 15 (the pressure of the rod-side oil chamber) is measured by the rod pressure sensor S2.
- the rod pressure sensor S2 is provided in an oil passage connecting the rod-side oil chamber of the boom cylinder 15 to the first direction control valve 54 and the second direction control valve 55 (for example, the input/output port of the rod-side oil chamber or its vicinity). A pressure sensor.
- the measured values of the bottom pressure sensor S1, the rod pressure sensor S2, and the operation amount sensors S3 and S4 are input to the controller 60.
- the operation of the electromagnetic valve 58 is controlled by the controller 60 based on the bottom pressure Pb of the boom cylinder 15 and the amount of operation of the boom operating lever 57l.
- the controller 60 is an in-vehicle computer including a CPU, a memory, a timer, etc.
- the CPU executes a program pre-stored in the memory to perform various processes.
- the controller 60 includes an electromagnetic sensor based on the bottom pressure measured by the bottom pressure sensor S1, the boom lowering operation amount measured by the operation amount sensor S3, and the elapsed time after the boom raising operation when the boom is lowered.
- a characteristic function is provided to control the valve 58 . This function is described below.
- FIG. 3 is a flow chart showing the control procedure of the solenoid valve 58 by the controller 60.
- the controller 60 repeatedly executes the flow of FIG. 3 in a short cycle time (eg, 0.1 s) when power is supplied (eg, when the key switch is turned on).
- a short cycle time eg, 0.1 s
- the controller 60 first inputs the measured values (output signals) of the bottom pressure sensor S1 and the manipulated variable sensors S3 and S4 (step S01).
- the controller 60 determines whether a boom lowering operation is being performed (whether the boom lowering operation amount Ad>0) based on the measurement value of the operation amount sensor S3 (step S02).
- the controller 60 shifts the procedure from step S02 to step S03. If the boom lowering operation has not been performed, the controller 60 moves the procedure from step S02 to step S07.
- the controller 60 calculates the first opening degree command value V1 for the solenoid valve 58 based on the bottom pressure Pb of the boom cylinder 15 measured by the bottom pressure sensor S1 (step S03).
- the first opening degree command value V1 decreases as the bottom pressure Pb increases as the communication area between the boom lowering pressure reducing valve 57d and the pressure receiving chamber of the second directional control valve 55 (opening area of the oil passage at the open position 58a). It is calculated based on the control table set as follows.
- the controller 60 calculates a second opening degree command value V2 for the electromagnetic valve 58 based on the boom lowering operation amount Ad measured by the operation amount sensor S3 (step S04).
- the order of steps S03 and S04 may be reversed or may be performed simultaneously.
- the second opening command value V2 changes as the boom lowering operation amount Ad increases as the communication area between the boom lowering pressure reducing valve 57d and the pressure receiving chamber of the second directional control valve 55 (opening area of the oil passage at the open position 58a) increases. Calculated based on a control table set to increase.
- the controller 60 calculates the elapsed time T after the most recent boom-up operation based on the measured value of the operation amount sensor S4, and determines whether the elapsed time T is equal to or longer than the preset set time Ts (step S05).
- the elapsed time T is, for example, the time from when the most recently input boom raising operation amount Au (>0) becomes 0 to the current time.
- the starting time of the elapsed time T may be the time when the boom raising operation amount reaches a predetermined pilot pressure.
- the controller 60 shifts the procedure from step S05 to step S06. If the elapsed time T is less than the set time Ts, the controller 60 moves the procedure from step S05 to step S07.
- the controller 60 sets the minimum selected value (smaller value) of the first opening command value V1 and the second opening command value V2 to the final value. It is determined as the opening command value V (step S06).
- the controller 60 determines the minimum opening command value Vmin as the final opening command value V (step S07). The same applies when it is determined in step S02 that the boom lowering operation has not been performed.
- the minimum opening command value Vmin is a value that minimizes the area of communication between the boom lowering pressure reducing valve 57d and the pressure receiving chamber of the second directional control valve 55 (opening area of the oil passage at the open position 58a).
- the minimum value of the communication area (opening area of the oil passage at the open position 58a) is 0, for example.
- the pressure receiving chamber is connected only to the hydraulic oil tank 59 .
- the controller 60 After determining the opening command value V in step S06 or S07, the controller 60 generates a command signal (current or voltage) corresponding to the determined opening command value V, and outputs the generated command signal to the solenoid valve 58 ( solenoid) and return the procedure to step S01 (step S08).
- the operation of the second directional control valve 55 during the boom lowering operation is restricted depending on the conditions.
- the meter-in flow rate from the second hydraulic pump 53 to the bottom side oil chamber of the boom cylinder 15 decreases even with the same boom lowering operation amount Ad.
- FIG. 4 is a diagram showing an example of functional blocks of the controller 60 for executing the flow of FIG.
- the controller 60 includes a first opening command value calculation 61, a second opening command value calculation 62, an elapsed time calculation 63 after the boom raising operation, a third opening command value calculation 64, an opening It has a function to execute the process of command value determination 65 .
- the first opening command value calculation 61 is a process of calculating the first opening command value V1 based on the bottom pressure Pb measured by the bottom pressure sensor S1 according to the control line (control table) stored in the memory. .
- the control line is defined so that V1 decreases as Pb increases in the Pb-V1 coordinate system, in which the horizontal axis is Pb and the vertical axis is V1.
- the first opening degree command value V1 corresponds to a value for commanding a communication area between the boom lowering pressure reducing valve 57d and the pressure receiving chamber of the second directional control valve 55 on the boom lowering side, and the communication area increases as V1 increases.
- V1 calculated under the control line displayed in the first opening degree command value calculation block 61 decreases as the bottom pressure Pb increases.
- the control lines referred to in the first opening degree command value calculation 61 include the first control line L1 and the second control line L2.
- the first control line L1 is a control line that is referenced when the bottom pressure Pb increases
- the second control line L2 is a control line that is referenced when the bottom pressure Pb decreases.
- P1-P4 shown in the block of the first opening command value calculation 61 are set values for Pb (P1 ⁇ P2 ⁇ P3 ⁇ P4).
- V1 Vmax (maximum opening command value) in the region of Pb ⁇ P2
- V1 monotonously decreases from Vmax to Vmin in the region of P2 ⁇ Pb ⁇ P4 as Pb increases
- V1 Vmin (minimum opening command value) in the region of Pb>P4
- V1 Vmin in the region of Pb>P3
- V1 Vmin in the region of Pb>P3
- V1 calculated by the controller 60 as Pb increases or decreases under the control line will be described in detail. If Pb rises from a value less than or equal to P2 (i.e., the value at which V1 takes Vmax), controller 60 decreases V1 along first control line L1 (V1 corresponding to Pb on first control line L1 becomes calculation). Conversely, if Pb falls from a value greater than or equal to P3 (ie, the value at which V1 takes Vmin), controller 60 increases V1 along second control line L2 (corresponding to Pb on second control line L2). V1).
- P2 i.e., the value at which V1 takes Vmax
- P3 i.e., the value at which V1 takes Vmin
- V1 simply decreases from Vmax to Vmin along the first control line L1 as Pb increases, and then decreases as Pb decreases.
- V1 increases from Vmin to Vmax along the second control line L2.
- V1 maintains the value on the second control line L2 to the value on the first control line L1, and then decreases as Pb rises along the first control line L1.
- the second opening command value calculation 62 is a process of calculating the second opening command value V2 based on the boom lowering operation amount Ad measured by the operation amount sensor S3 according to the control line (control table) stored in the memory. is.
- the control line is defined so that V2 increases as Ad increases in the Ad-V2 coordinate system in which the horizontal axis is Ad and the vertical axis is V2.
- the second opening degree command value V2 also corresponds to a value for commanding the communication area between the boom lowering pressure reducing valve 57d and the pressure receiving chamber of the second directional control valve 55 on the boom lowering side, and the communication area increases as V2 increases.
- V2 calculated under the control line displayed in the second opening command value calculation block 62 increases as Ad increases.
- A1 and A2 shown in the second opening command value calculation block 62 are set values for Ad (0 ⁇ A1 ⁇ A2).
- the value on the control line is always calculated as V2 for Ad. .
- the post-boom raising operation elapsed time calculation 63 is processing for calculating the elapsed time T from the stop of the most recent boom raising operation to the present based on the boom raising operation amount Au measured by the operation amount sensor S4 and the measurement time of the timer. be.
- the beginning of the elapsed time T is the time when the most recent boom raising operation amount Au (>0) becomes zero.
- the time when the boom raising operation amount Au becomes 0 can be identified from, for example, the log data of the boom raising operation amount Au stored in the memory. Elapsed time T is calculated.
- the third opening command value calculation 64 is a process of calculating the third opening command value for the electromagnetic valve 58 based on the elapsed time T after the boom raising operation. In the processing of the third opening command value calculation 64, when the elapsed time T is less than the set time Ts, the communication area between the boom lowering pressure reducing valve 57d and the pressure receiving chamber on the boom lowering side of the second directional control valve 55 is the minimum value.
- the solenoid valve 58 is adjusted so that the communication area between the boom lowering pressure reducing valve 57d and the pressure receiving chamber of the second directional control valve 55 on the boom lowering side becomes the maximum value.
- the restriction amount of the meter-in flow rate to the bottom side oil chamber of the boom cylinder 15 during the boom lowering operation is preferably controlled as described above with reference to FIG. .
- the operation of the second direction control valve 55 is prohibited (operation limit is maximized) until the elapsed time T after the most recent boom raising operation reaches the set time Ts, and the boom lowering operation is performed.
- the meter-in flow rate to the rod-side oil chamber of the boom cylinder 15 does not immediately increase. For example, when the boom raising operation and the boom lowering operation are alternately repeated in a short period, such as in pounding work, when the bottom pressure Pb of the boom cylinder 15 fluctuates greatly when the operation is switched from boom raising to boom lowering.
- the first control line L1 and the second control line L2 are prepared, and the first opening command value V1 is calculated under the first control line L1 when Pb rises, and when Pb falls A first opening degree command value V1 is calculated under the second control line L2. Since the first control line L1 and the second control line L2 are offset by ⁇ Pb in the Pb-axis direction in the Pb-V1 coordinate system, when the value of Pb changes from increasing to decreasing (or from decreasing to increasing), The first opening degree command value V1 does not change until the change exceeds a certain amount ( ⁇ Pb). Therefore, it is possible to prevent the solenoid valve 58 from operating too sensitively when the bottom pressure Pb fluctuates as described above.
- the controller 60 may be configured to calculate the difference between the rod pressure Pr measured by the rod pressure sensor S2 and the bottom pressure Pb, and to calculate the first opening degree command value V1 based on this difference. .
- the operating lever device 57 including the boom operating lever 57l that mechanically interlocks with the boom lowering pressure reducing valve 57d and the boom raising pressure reducing valve 57u
- the operating lever device 57 can also adopt an electric lever device.
- the boom lowering pressure reducing valve 57d and the boom raising pressure reducing valve 57u are electromagnetically driven, and the boom lowering pressure reducing valve 57d and the boom raising pressure reducing valve 57u are controlled by a command signal output from the controller 60 in response to the operation signal of the electric lever device. is configured to operate.
- the operation amount of the boom operating lever 57l can be detected by a potentiometer or the like, and the present invention can be applied.
- first hydraulic pump 52 and the second hydraulic pump 53 are respectively one
- SYMBOLS 1 Hydraulic excavator (construction machine), 4... Vehicle body, 10... Front working machine, 15... Boom cylinder, 51... Prime mover, 52... First hydraulic pump, 53... Second hydraulic pump, 54... First directional control valve, 55 Second direction control valve 56 Pilot pump 56b Pilot oil passage 57d Boom lowering pressure reducing valve 57l Boom control lever 57u Boom raising pressure reducing valve 58 Solenoid valve 60 Controller Ad Boom lowering operation amount (operation amount), Au... Boom raising operation amount (operation amount), L1... First control line, L2... Second control line, Pb... Bottom pressure, Pr... Rod pressure, S1... Bottom pressure sensor, S2... Rod pressure sensor, S3, S4... Operation amount sensor, T... Elapsed time, Ts... Set time, V... Opening command value, V1... First opening command value, V2... Second opening command value, V3 ... Third opening command value, Vmax ... Maximum opening command value, Vmin ... Minimum opening command value
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Abstract
Description
図1は本発明の一実施形態に係る建設機械を表す側面図である。同図では、建設機械として油圧ショベル1を例示しているが、ホイールローダ、クレーン等、土木作業、建設作業、解体作業等の各種作業に用いられる他種の建設機械に本発明は適用可能である。油圧ショベル1はクローラ式であるが、ホイール式の建設機械にも本発明は適用可能である。
図2は図1に示した建設機械に搭載された油圧システムの要部を表す回路図である。図2ではブームシリンダ15の駆動回路を抜き出して表している。同図に示した油圧システムは、原動機51、第1油圧ポンプ52、第2油圧ポンプ53、第1方向制御弁54、第2方向制御弁55、パイロットポンプ56、操作レバー装置57、電磁弁58、コントローラ60を備えている。
第1油圧ポンプ52及び第2油圧ポンプ53は、油圧ショベル1に搭載された油圧アクチュエータを駆動する作動油を吐出する可変容量型のポンプであり、原動機51により駆動される。本実施形態における原動機51は内燃機関等の燃焼エネルギーを動力に変換するエンジンであるが、電動機を原動機51に用いる場合もある。図2では第1油圧ポンプ52及び第2油圧ポンプ53を各1個のみ図示しているが、第1油圧ポンプ52及び第2油圧ポンプ53の少なくとも一方を複数にする場合もある。作動油タンク59から吸入されて第1油圧ポンプ52から吐出された圧油は、第1方向制御弁54を経由してブームシリンダ15に供給される。作動油タンク59から吸入されて第2油圧ポンプ53から吐出された圧油は、第2方向制御弁55を経由してブームシリンダ15に供給される。ブームシリンダ15からの戻り油は、第1方向制御弁54及び第2方向制御弁55を介して作動油タンク59に戻る。
パイロットポンプ56は、第1方向制御弁54及び第2方向制御弁55等の油圧駆動式の制御弁を駆動するパイロット油を吐出する固定容量型ポンプである。第1油圧ポンプ52及び第2油圧ポンプ53と同じく、パイロットポンプ56は原動機51により駆動される。原動機51とは別の動力源でパイロットポンプ56を駆動する構成とすることもできる。パイロットポンプ56の吐出油路56mは、分岐して操作レバー装置57のブーム下げ減圧弁57dやブーム上げ減圧弁57u等に接続している。吐出管路57aを介してパイロットポンプ56の吐出圧がブーム下げ減圧弁57dやブーム上げ減圧弁57u等にパイロット圧の元圧として入力される。
第1方向制御弁54は、第1油圧ポンプ52からブームシリンダ15に供給される圧油の流れ(方向及び流量)を制御する油圧駆動式の方向切換弁であり、受圧室に入力されるパイロット圧により駆動される。第1方向制御弁54は、ブーム下げ位置54d、ブーム上げ位置54u、中立位置54nを有する比例式の3位置切換弁である。パイロット圧が作用していない状態では、第1方向制御弁54のスプールは、ばね力により中立位置54nに位置する。
第2方向制御弁55は、第2油圧ポンプ53からブームシリンダ15に供給される圧油の流れ(方向及び流量)を制御する油圧駆動式の方向切換弁であり、受圧室に入力されるパイロット圧により駆動される。第2方向制御弁55は、ブーム下げ位置55d、ブーム上げ位置55u、中立位置55nを有する比例式の3位置切換弁である。パイロット圧が作用していない状態では、第2方向制御弁55のスプールは、ばね力により中立位置55nに位置する。
第1方向制御弁54及び第2方向制御弁55のブーム下げ側の受圧室は、各々パイロット油路56a,56bを介してブーム下げ減圧弁57dに接続し、更にブーム下げ減圧弁57dを介してパイロットポンプ56に接続している。ブーム下げ減圧弁57dは、ブーム操作レバー57lにより操作される。ブーム操作レバー57lがブーム下げ方向(図2では左方向)に操作されると、ブーム操作レバー57lの操作量に応じてブーム下げ減圧弁57dが作動する。これによりパイロットポンプ56の吐出油路56mとパイロット油路56a,56bとが接続されると共に、パイロットポンプ56からのパイロット油の圧力を元圧として、ブーム操作レバー57lのブーム下げ操作量に応じたブーム下げパイロット圧が出力される。このパイロット圧が第1方向制御弁54及び第2方向制御弁55のブーム下げ側の受圧室に作用すると、第1方向制御弁54及び第2方向制御弁55が中立位置54n,55nからブーム下げ方向に駆動され、ブーム下げ位置54d,55dに切り換わる。
第1方向制御弁54及び第2方向制御弁55のブーム上げ側の受圧室は、各々パイロット油路56c,56dを介してブーム上げ減圧弁57uに接続し、更にブーム上げ減圧弁57uを介してパイロットポンプ56に接続している。ブーム上げ減圧弁57uも、ブーム下げ減圧弁57dと同じくブーム操作レバー57lにより操作される。ブーム操作レバー57lがブーム上げ方向(図2では右方向)に操作されると、ブーム操作レバー57lの操作量に応じてブーム上げ減圧弁57uが作動する。これによりパイロットポンプ56の吐出油路56mとパイロット油路56c,56dとが接続され、パイロットポンプ56からのパイロット油の圧力を元圧として、ブーム操作レバー57lのブーム上げ操作量に応じたブーム上げパイロット圧が出力される。このパイロット圧が第1方向制御弁54及び第2方向制御弁55のブーム上げ側の受圧室に作用すると、第1方向制御弁54及び第2方向制御弁55が中立位置54n,55nからブーム上げ方向に駆動され、ブーム上げ位置54u,55uに切り換わる。
上記電磁弁58は、ブーム下げ減圧弁57dが出力するブーム下げパイロット圧を減圧し、第2方向制御弁55のブーム下げ側の受圧室に対する補正ブーム下げパイロット圧(補正されたブーム下げパイロット圧)を出力する比例電磁減圧弁である。この電磁弁58は、ブーム下げ減圧弁57dと第2方向制御弁55のブーム下げ側の受圧室とを繋ぐパイロット油路56bに設けられている。電磁弁58は、開通位置58a及び遮断位置58bを有している。本実施形態において、電磁弁58のスプールは、ソレノイドが消磁された状態でばね力により遮断位置58b側に押し付けられ、ソレノイドが励磁されるとばね力に抗して開通位置58a側に移動する。但し、消磁状態でスプールが開通位置58aに押し付けられ、励磁されると遮断位置58b側にスプールが移動する構成としても良い。
ブーム操作レバー57lの操作量が、操作量センサS3,S4により測定される。操作量センサS3はブーム下げ操作量Adを、操作量センサS3はブーム上げ操作量Auをそれぞれ測定する。操作量センサS3,S4は、いずれも圧力センサである。操作量センサS3は、ブーム下げ減圧弁57dを第1方向制御弁54のブーム下げ側の受圧室及び電磁弁58に接続するパイロット油路56a又は56b(例えばブーム下げ減圧弁57dの出力ポート又はそのすぐ下流)に設けられている。ブーム下げパイロット圧を操作量センサS3で測定することで、ブーム下げ操作量Adが測定される。操作量センサS4は、ブーム上げ減圧弁57uを第1方向制御弁54及び第2方向制御弁55のブーム上げ側の受圧室に接続するパイロット油路56c又は56d(例えばブーム上げ減圧弁57uの出力ポート又はそのすぐ下流)に設けられている。ブーム上げパイロット圧を操作量センサS4で測定することで、ブーム上げ操作量Auが測定される。なお、圧力センサに代えてポテンショメータ等を操作量センサS3,S4に用い、ブーム操作レバー57lの角度を測定してブーム下げ操作量Ad及びブーム上げ操作量Auを測定する構成とすることもできる。
ブームシリンダ15のボトム圧Pb及びブーム操作レバー57lの操作量に基づき、電磁弁58の動作がコントローラ60により制御される。コントローラ60は、CPUやメモリ、タイマ等を含んで構成された車載コンピュータであり、メモリに予め記憶されたプログラムをCPUにより実行して各種処理を実行する。本実施形態において、コントローラ60には、ブーム下げ操作時に、ボトム圧センサS1で測定されるボトム圧、操作量センサS3で測定されるブーム下げ操作量及びブーム上げ操作後の経過時間に基づいて電磁弁58を制御する特徴的機能が備わっている。この機能について次に説明する。
(1)上記の通り、本実施形態によれば、バケット14が宙に浮いた状態で行われるような低負荷のブーム下げ動作が推定される場面では、ブーム下げ用のメータイン流量を抑えることで、エネルギーロスを抑制することができる。また、ジャッキアップ動作等のようにバケット14を地面に強く押し付ける高負荷のブーム下げ動作が推定される場面では、ブーム下げ用のメータイン流量を増加させて所要の出力を確保することができる。更に、土羽打ち作業等のようにブーム上げ操作とブーム下げ操作が繰り返されるような場合に望まない形で電磁弁58が作動し得る場面では、ブーム上げ操作から設定時間Tsが経過するまで電磁弁58の作動を抑止することで、ブーム下げ時においてメータイン流量が多く発生するのを抑えられ、操作性の悪化を抑制することができる。
以上に本発明の一実施形態を説明したが、本発明の実施形態は以上の形態に限定されず、本発明の趣旨を逸脱しない範囲で様々に変更可能である。以下に幾つか変形例を例示する。
Claims (3)
- 車体と、前記車体に連結したフロント作業機と、前記フロント作業機を上下に駆動するブームシリンダと、原動機と、前記原動機によって駆動される第1油圧ポンプと、前記原動機によって駆動される第2油圧ポンプと、前記第1油圧ポンプから前記ブームシリンダに流れる圧油を制御する第1方向制御弁と、前記第2油圧ポンプから前記ブームシリンダに流れる圧油を制御する第2方向制御弁と、前記第1方向制御弁及び前記第2方向制御弁を駆動するパイロット油を吐出するパイロットポンプと、前記パイロット油を元圧として、前記第1方向制御弁及び前記第2方向制御弁をブーム下げ方向に駆動するブーム下げパイロット圧を出力するブーム下げ減圧弁と、前記パイロット油を元圧として、前記第1方向制御弁及び前記第2方向制御弁をブーム上げ方向に駆動するブーム上げパイロット圧を出力するブーム上げ減圧弁と、前記ブーム下げ減圧弁及び前記ブーム上げ減圧弁を操作するブーム操作レバーとを備えた建設機械において、
前記ブームシリンダのボトム圧を測定するボトム圧センサと、
前記ブーム操作レバーの操作量を測定する操作量センサと、
前記ブーム下げ減圧弁と前記第2方向制御弁の受圧室とを繋ぐパイロット油路に設けられ、前記第2方向制御弁に対するブーム下げパイロット圧を減圧する電磁弁と、
前記ボトム圧センサで測定される前記ボトム圧及び前記操作量センサで測定される前記操作量に基づき前記電磁弁を制御するコントローラとを備え、
前記コントローラは、
前記ボトム圧センサで測定されたボトム圧に基づき、前記ブーム下げ減圧弁と前記第2方向制御弁の受圧室との連通面積が前記ボトム圧の増加に伴って減少するように第1開度指令値を演算し、
前記操作量センサで測定されたブーム下げ操作量に基づき、前記連通面積が前記ブーム下げ操作量の増加に伴って増加するように第2開度指令値を演算し、
ブーム上げ操作後の経過時間に基づき、前記経過時間が設定時間未満である場合は前記連通面積を最小とする最小開度指令値を、前記経過時間が前記設定時間以上である場合は前記第1開度指令値及び前記第2開度指令値の最小選択値を、前記電磁弁の開度指令値に決定し、
決定した開度指令値に応じた指令信号を前記電磁弁に出力する
ことを特徴とする建設機械。 - 請求項1に記載の建設機械おいて、
前記コントローラは、
横軸に前記ボトム圧、縦軸に前記第1開度指令値をとる座標系において、前記ボトム圧の増加に伴って前記第1開度指令値が減少するように規定され、前記横軸の方向にオフセットした第1制御線及び第2制御線を記憶しており、
前記ボトム圧の上昇時には前記第1制御線を参照して前記第1開度指令値を演算し、前記ボトム圧の下降時には前記第2制御線を参照して前記第1開度指令値を演算する
ことを特徴とする建設機械。 - 請求項1に記載の建設機械おいて、
前記ブームシリンダのロッド圧を測定するロッド圧センサと、
前記コントローラは、前記ボトム圧センサで測定されたボトム圧と前記ロッド圧センサで測定されたロッド圧との差分を演算し、前記差分に基づき第1開度指令値を演算することを特徴とする建設機械。
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JP2010275818A (ja) | 2009-05-29 | 2010-12-09 | Hitachi Constr Mach Co Ltd | 建設機械の油圧駆動装置 |
WO2011027791A1 (ja) * | 2009-09-02 | 2011-03-10 | 日立建機株式会社 | 油圧作業機の油圧駆動装置 |
US20160333551A1 (en) * | 2013-06-28 | 2016-11-17 | Volvo Construction Equipment Ab | Hydraulic circuit for construction machinery having floating function and method for controlling floating function |
WO2019065925A1 (ja) * | 2017-09-29 | 2019-04-04 | 日立建機株式会社 | 作業機械 |
WO2020188920A1 (ja) * | 2019-03-20 | 2020-09-24 | 日立建機株式会社 | 油圧ショベル |
JP2021148154A (ja) * | 2020-03-17 | 2021-09-27 | 株式会社小松製作所 | 油圧システム |
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JP2010275818A (ja) | 2009-05-29 | 2010-12-09 | Hitachi Constr Mach Co Ltd | 建設機械の油圧駆動装置 |
WO2011027791A1 (ja) * | 2009-09-02 | 2011-03-10 | 日立建機株式会社 | 油圧作業機の油圧駆動装置 |
US20160333551A1 (en) * | 2013-06-28 | 2016-11-17 | Volvo Construction Equipment Ab | Hydraulic circuit for construction machinery having floating function and method for controlling floating function |
WO2019065925A1 (ja) * | 2017-09-29 | 2019-04-04 | 日立建機株式会社 | 作業機械 |
WO2020188920A1 (ja) * | 2019-03-20 | 2020-09-24 | 日立建機株式会社 | 油圧ショベル |
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