WO2022195832A1 - 作業機械 - Google Patents
作業機械 Download PDFInfo
- Publication number
- WO2022195832A1 WO2022195832A1 PCT/JP2021/011261 JP2021011261W WO2022195832A1 WO 2022195832 A1 WO2022195832 A1 WO 2022195832A1 JP 2021011261 W JP2021011261 W JP 2021011261W WO 2022195832 A1 WO2022195832 A1 WO 2022195832A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- spool
- valve
- pressure
- pilot
- opening area
- Prior art date
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Images
Classifications
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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
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
- F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
- F15B13/042—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated by fluid pressure
- F15B13/043—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated by fluid pressure with electrically-controlled pilot valves
- F15B13/0433—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated by fluid pressure with electrically-controlled pilot valves the pilot valves being pressure control 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
- 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
- F15B11/042—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the feed line, i.e. "meter in"
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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
- F15B20/00—Safety arrangements for fluid actuator systems; Applications of safety devices in fluid actuator systems; Emergency measures for fluid actuator systems
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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
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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
- F15B2211/20507—Type of prime mover
- F15B2211/20523—Internal combustion engine
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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
- F15B2211/2053—Type of pump
- F15B2211/20546—Type of pump variable capacity
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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
- F15B2211/3105—Neutral or centre positions
- F15B2211/3111—Neutral or centre positions the pump port being closed in the centre position, e.g. so-called closed centre
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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
- F15B2211/327—Directional control characterised by the type of actuation electrically or electronically
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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
- F15B2211/355—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
- F15B2211/40—Flow control
- F15B2211/405—Flow control characterised by the type of flow control means or valve
- F15B2211/40507—Flow control characterised by the type of flow control means or valve with constant throttles or orifices
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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
- F15B2211/40—Flow control
- F15B2211/405—Flow control characterised by the type of flow control means or valve
- F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
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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
- F15B2211/40—Flow control
- F15B2211/415—Flow control characterised by the connections of the flow control means in the circuit
- F15B2211/41563—Flow control characterised by the connections of the flow control means in the circuit being connected to a pressure source and a return line
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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
- F15B2211/40—Flow control
- F15B2211/42—Flow control characterised by the type of actuation
- F15B2211/426—Flow control characterised by the type of actuation electrically or electronically
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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
- F15B2211/40—Flow control
- F15B2211/42—Flow control characterised by the type of actuation
- F15B2211/428—Flow control characterised by the type of actuation actuated by fluid pressure
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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
- F15B2211/40—Flow control
- F15B2211/45—Control of bleed-off flow, e.g. control of bypass flow to the return line
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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
- F15B2211/50—Pressure control
- F15B2211/505—Pressure control characterised by the type of pressure control means
- F15B2211/50554—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure downstream of the pressure control means, e.g. pressure reducing 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
- F15B2211/60—Circuit components or control therefor
- F15B2211/625—Accumulators
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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
- F15B2211/6309—Electronic controllers using input signals representing a pressure the pressure being a pressure source supply 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
- F15B2211/633—Electronic controllers using input signals representing a state of the prime mover, e.g. torque or rotational speed
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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
- F15B2211/6651—Control of the prime mover, e.g. control of the output torque or rotational speed
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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
- F15B2211/6652—Control of the pressure source, e.g. control of the swash plate angle
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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
- F15B2211/67—Methods for controlling pilot pressure
Definitions
- the present invention relates to working machines.
- a main fluid pressure circuit that controls the working fluid discharged from the main pump by a pilot operated control valve and supplies it to the fluid actuator, and the pressure oil discharged from the pilot pump whose pressure is set by the pilot relief valve is sent to the electromagnetic proportional pressure reducing valve.
- a working machine includes a pilot system fluid pressure circuit that supplies a pilot primary pressure and guides a secondary pressure controlled by an electromagnetic proportional pressure reducing valve to a pilot-operated control valve (Fig. 6). In such a work machine, even if there is no manual operation by the operator, the constant flow of hydraulic oil discharged from the pilot pump is relieved to the tank by the pilot relief valve, so the energy consumption efficiency is poor. was there.
- Patent Document 1 in order to improve the deterioration of energy consumption efficiency due to the provision of a pilot relief valve, a main fluid pressure circuit in which a working fluid discharged from a pump is controlled by a pilot operated control valve and supplied to a fluid pressure actuator. and a pilot system fluid pressure circuit for supplying a portion of the working fluid discharged from the pump of the main fluid pressure circuit to the pilot acting portion of the pilot operated control valve.
- a bypass sequence valve is provided in a bypass passage that connects the pump and the tank.
- the bypass sequence valve is controlled to a no-load communication state, and when there is a manual operation signal, the pressure at the inlet of the bypass sequence valve is controlled to be equal to or higher than the primary pressure of the pilot. .
- a bleed-off valve (e.g., equivalent to the bypass sequence valve described in Patent Document 1) that discharges part of the working fluid discharged from the pump to a tank, when the flow rate and pressure of the working fluid passing through the bleed-off valve increase, , the thrust required to drive the valve body increases.
- a pilot-driven bleed-off valve is employed.
- the present invention provides a work machine having a pilot circuit that guides a portion of a working fluid discharged from a pump to a main circuit to a control valve.
- An object of the present invention is to provide a working machine equipped with a pilot-driven bleed-off valve that can stably secure the pressure of a main circuit.
- a working machine includes a main circuit that supplies a working fluid discharged from a pump to an actuator, and a control circuit that is provided in the main circuit and controls the flow of the working fluid that is supplied from the pump to the actuator.
- a bleed-off passage connecting the pump and the tank; a pilot-driven bleed-off valve provided in the bleed-off passage; a third pressure reducing valve that generates a pilot secondary pressure that acts on a pilot pressure receiving portion of an off-valve; an operation device that operates the actuator; and a control of the third pressure reducing valve based on operation by the operation device and a controller.
- the bleed-off valve has a spool that moves in the axial direction, a valve body that slidably accommodates the spool, and a working fluid that passes through the bleed-off valve by a secondary pilot pressure generated by the third pressure reducing valve. and an aperture.
- the movement area of the spool in the axial direction has a first movement area in which the opening area of the diaphragm changes stepwise and a second movement area in which the opening area of the diaphragm changes continuously.
- the control device controls the third pressure reducing valve to position the spool in the first movement region when the actuator is not operated by the operating device.
- the controller controls the third pressure reducing valve so as to position the spool in the second movement region when the actuator is operated by the operation device with an operation amount larger than a predetermined value. to control.
- the throttle has a throttle hole that provides resistance to working fluid passing therethrough when the spool is positioned in the first movement region.
- FIG. 1 is a side view of a hydraulic excavator according to an embodiment of the present invention
- the cross-sectional schematic diagram of the bleed-off valve which concerns on this embodiment. It is a cross-sectional schematic diagram which expands and shows a part of 1st land part, and shows a 1st entrance hole, a 2nd entrance hole, and a 3rd entrance hole. It is a cross-sectional schematic diagram showing an enlarged part of a spool and a valve body, showing an outlet hole, a fluid chamber and a notch. The figure explaining the flow of the hydraulic oil in each position of a spool.
- FIG. 5 is a diagram showing the aperture area A10 of the first aperture, the aperture area A20 of the second aperture, and the synthetic aperture area A0 of the aperture at each position of the spool; Functional block diagram of the main controller.
- FIG. 5 is a diagram showing details of arithmetic processing performed by a control valve command generation unit;
- the target opening area At of the bleed-off valve set according to the operation of the gate lock lever device and the operation lever of the actuator, the pump discharge flow rate (pump target flow rate Qt) and pressure set according to the operation of the actuator operation lever 4 is a time chart showing changes in discharge pressure P detected by a sensor;
- FIG. 8 is a schematic cross-sectional view of a bleed-off valve according to Modification 2;
- FIG. 11 is a cross-sectional schematic diagram showing an enlarged part of a first land portion in a bleed-off valve according to Modification 5, showing a first inlet hole, a second inlet hole, and a third inlet hole.
- FIG. 1 is a side view of a hydraulic excavator 1 according to an embodiment of the present invention.
- the longitudinal direction and the vertical direction of the hydraulic excavator 1 are defined as shown in FIG. That is, in the present embodiment, the front of the driver's seat (to the left in the figure) is the front of the hydraulic excavator 1 unless otherwise specified.
- the hydraulic excavator 1 includes a body (body) 20 and a working device 10 attached to the body 20 .
- the machine body 20 includes a running body 2 and a revolving body 3 mounted on the running body 2 so as to be able to turn.
- the traveling body 2 has a pair of left and right crawlers and a traveling hydraulic motor 2a that is an actuator.
- the traveling body 2 travels by driving the crawler with a traveling hydraulic motor 2a.
- the revolving body 3 has a revolving hydraulic motor 3a as an actuator.
- the revolving body 3 is rotated with respect to the traveling body 2 by a revolving hydraulic motor 3a.
- the revolving body 3 includes a revolving frame 30, an operator's cab 31 provided on the front left side of the revolving frame 30, a counterweight 32 provided at the rear of the revolving frame 30, and a rear side of the operator's cab 31 in the revolving frame 30. and an engine compartment 33 .
- the engine room 33 accommodates an engine as a power source and hydraulic equipment such as a hydraulic pump, valves, and an accumulator.
- the work device 10 is rotatably connected to the center of the front portion of the revolving frame 30 .
- the work device 10 is a multi-joint type work device having a plurality of rotatably connected driven members and a plurality of hydraulic cylinders for driving the driven members.
- a boom 11, an arm 12 and a bucket 13 as three driven members are connected in series.
- the boom 11 is rotatably connected at its base end to the front portion of the revolving frame 30 .
- the base end of the arm 12 is rotatably connected to the tip of the boom 11 .
- Bucket 13 is rotatably connected to the tip of arm 12 .
- the boom 11 is driven by a hydraulic cylinder (hereinafter also referred to as a boom cylinder 11a), which is an actuator, and rotates with respect to the revolving frame 30.
- the arm 12 is driven by a hydraulic cylinder (hereinafter also referred to as an arm cylinder 12 a ), which is an actuator, and rotates with respect to the boom 11 .
- the bucket 13 is driven by a hydraulic cylinder (hereinafter also referred to as a bucket cylinder 13 a ), which is an actuator, and rotates with respect to the arm 12 .
- FIG. 2 is a diagram showing a hydraulic system 90 mounted on the hydraulic excavator 1.
- the hydraulic system 90 is provided with hydraulic equipment for driving a plurality of hydraulic actuators (2a, 3a, 11a, 12a, 13a). Hydraulic equipment for driving the other hydraulic actuators (2a, 3a, 13a) is omitted from illustration.
- FIG. 2 also shows a main controller 100, which is a control device for controlling the hydraulic system 90, and devices (21, 22, 23, 24, 25) that output signals to the main controller 100.
- the hydraulic excavator 1 includes an engine control dial 21 for setting a target rotational speed of the engine 80, and an operating device (also referred to as a boom operating device) for operating the boom cylinder 11a (boom 11). 23 , an operation device (also referred to as an arm operation device) 24 for operating the arm cylinder 12 a (arm 12 ), and a gate lock lever device 22 .
- These devices ( 21 to 24 ) are provided in the operator's cab 31 .
- the boom operation device 23 detects an operation lever 23a that can be tilted from a neutral position to the boom up side and the boom down side, and the operation direction and the operation amount of the operation lever 23a, and determines the operation direction and the operation amount of the operation lever 23a. and an operation sensor for outputting an operation signal representing to the main controller 100 .
- the arm operation device 24 detects an operation lever 24a that can be tilted from a neutral position to the arm cloud side and the arm dump side, and the operation direction and operation amount of the operation lever 24a, and determines the operation direction and operation amount of the operation lever 24a. and an operation sensor for outputting an operation signal representing to the main controller 100 .
- the operation amount (operation angle) of the operation levers 23a and 24a detected by the operation sensors of the operation devices 23 and 24 is 0[%] (0°) at the neutral position, and the absolute value increases as the tilt from the neutral position increases. value increases.
- the gate lock lever device 22 has a lock position (up position) that permits entry into and exits from the driver's cab 31 and prohibits the operation of the actuators (11a, 12a, 13a), 12a, 13a) and a lever 22a selectively operated to the unlocked position (lowered position).
- the gate lock lever device 22 also has an operation position sensor that detects the operation position of the lever 22a and outputs a gate lock lever signal indicating the operation position of the lever 22a to the main controller 100.
- the engine control dial 21 is an operation device for setting the target rotational speed of the engine 80 and outputs an operation signal to the main controller 100 .
- the main controller 100 determines a target rotation speed based on an operation signal from the engine control dial 21 and outputs a signal of the determined target rotation speed to the engine controller 105 .
- the engine 80 is provided with an engine rotation speed sensor 80a that detects the actual rotation speed of the engine 80 and a fuel injection device 80b that adjusts the amount of fuel injected into the cylinders of the engine 80 .
- the engine controller 105 controls the fuel injection device 80b so that the actual rotation speed of the engine 80 detected by the engine rotation speed sensor 80a becomes the target rotation speed output from the main controller 100.
- the hydraulic system 90 includes a pump 81, a main circuit HC1 that supplies hydraulic oil as a working fluid discharged from the pump 81 to the boom cylinder 11a and the arm cylinder 12a, a pilot circuit HC2 connected to the main circuit HC1, and the pump. 81 and a bleed-off passage Lb connecting the tank 19 in which hydraulic oil is stored.
- the pilot circuit HC2 distributes a portion of the hydraulic fluid discharged from the pump 81 to pilot pressure receiving portions 45a, 45b, 46a, 46b of the control valves 45 and 46, which will be described later, and a pilot pressure receiving portion 149 of the bleed-off valve 140, which will be described later. It is a circuit that leads to
- the pump 81 is connected to the engine 80 and driven by the engine 80 to suck hydraulic oil from the tank 19 and discharge it.
- the pump 81 is a variable displacement piston type hydraulic pump, and its discharge capacity (displacement capacity) changes as the inclination of the swash plate is changed by the regulator 81a.
- the engine 80 is a power source of the hydraulic excavator 1, and is configured by an internal combustion engine such as a diesel engine, for example.
- the main circuit HC1 includes a control valve (hereinafter also referred to as a boom control valve) 45 for controlling the flow of hydraulic fluid supplied from the pump 81 to the boom cylinder 11a, and a control valve for controlling hydraulic fluid supplied from the pump 81 to the arm cylinder 12a.
- a control valve (hereinafter also referred to as an arm control valve) 46 for controlling the flow is provided.
- the main circuit HC1 has a pump discharge passage Ld connected to the discharge port of the pump 81, a parallel passage Lp connected to the pump discharge passage Ld, and a tank passage Lt connected to the tank 19.
- the parallel passage Lp is a passage that guides hydraulic oil from the pump discharge passage Ld to the pump ports of the boom control valve 45 and the arm control valve 46.
- a parallel passage Lp connected to the pump port of the boom control valve 45 is provided with a check valve 41 for holding the load pressure of the boom cylinder 11a. The check valve 41 is fully closed when the pump discharge pressure falls below the cylinder pressure.
- a parallel passage Lp connected to the pump port of the arm control valve 46 is provided with a check valve 42 for holding the load pressure of the arm cylinder 12a. The check valve 42 is fully closed when the pump discharge pressure falls below the cylinder pressure.
- the bleed-off passage Lb is connected to the parallel passage Lp.
- a pilot-driven bleed-off valve 140 is provided in the bleed-off passage Lb.
- the bleed-off valve 140 has a throttle (variable throttle) 150 that imparts resistance to the flow of hydraulic oil passing therethrough, and the hydraulic oil discharged from the pump 81 is discharged to the tank 19 through this throttle 150 .
- the bleed-off valve 140 can adjust the pump discharge pressure by changing the opening area (opening degree) of the throttle 150 .
- the pilot circuit HC2 includes a pilot pressure reducing valve (first pressure reducing valve) 71 that reduces the pressure of hydraulic fluid discharged from the pump 81 (that is, the pump discharge pressure) to generate a pilot primary pressure, and a pilot primary pressure.
- Electromagnetic valves (second pressure reducing valves) 51 and 61 that generate the secondary pressure, and electromagnetic valves that reduce the primary pilot pressure and generate secondary pilot pressure that acts on the pilot pressure receiving portions 46a and 46b of the arm control valve 46.
- second pressure reducing valves 52, 62 an electromagnetic valve (third pressure reducing valve) 63 that reduces the primary pilot pressure to generate the secondary pilot pressure that acts on the pilot pressure receiving portion 149 of the bleed-off valve 140;
- a lock valve 74 capable of shutting off the pilot primary pressure is provided.
- the solenoid valves 51, 52, 61, 62, 63 are proportional solenoid valves driven by solenoid thrust generated in response to control currents supplied to the solenoids.
- the solenoid valves 51 and 61 generate pilot secondary pressure to be output to the pilot pressure receiving portions 45 a and 45 b of the boom control valve 45 using the pilot primary pressure generated by the pilot pressure reducing valve 71 as source pressure.
- the solenoid valves 51 and 61 are controlled based on signals (control currents) output from the main controller 100 .
- the main controller 100 controls the solenoid valves 51 and 61 based on operation signals output from the boom operating device 23 .
- the boom control valve 45 When the pilot secondary pressure generated by the solenoid valve 51 acts on the pilot pressure receiving portion 45a of the boom control valve 45, the boom control valve 45 is switched to the extended position. As a result, the hydraulic fluid discharged from the pump 81 is guided to the bottom chamber of the boom cylinder 11a, and the hydraulic fluid is discharged from the rod chamber to the tank 19, thereby extending the boom cylinder 11a. As a result, the boom 11 rotates upward (that is, the boom 11 stands up).
- the boom control valve 45 When the pilot secondary pressure generated by the solenoid valve 61 acts on the pilot pressure receiving portion 45b of the boom control valve 45, the boom control valve 45 is switched to the retracted position. As a result, the hydraulic fluid discharged from the pump 81 is guided to the rod chamber of the boom cylinder 11a, and the hydraulic fluid is discharged from the bottom chamber to the tank 19, causing the boom cylinder 11a to contract. As a result, the boom 11 rotates downward (that is, the boom 11 falls down).
- the solenoid valves 52 and 62 generate pilot secondary pressure to be output to the pilot pressure receiving portions 46 a and 46 b of the arm control valve 46 using the pilot primary pressure generated by the pilot pressure reducing valve 71 as source pressure.
- the solenoid valves 52 and 62 are controlled based on signals (control current) output from the main controller 100 .
- the main controller 100 controls the solenoid valves 52, 62 based on the operation signal output from the arm operation device 24.
- the arm control valve 46 When the pilot secondary pressure generated by the solenoid valve 52 acts on the pilot pressure receiving portion 46a of the arm control valve 46, the arm control valve 46 is switched to the extended position. As a result, the hydraulic fluid discharged from the pump 81 is guided to the bottom chamber of the arm cylinder 12a, and the hydraulic fluid is discharged from the rod chamber to the tank 19, thereby extending the arm cylinder 12a. As a result, the arm 12 rotates downward (that is, the arm 12 performs a crowding motion).
- the arm control valve 46 When the pilot secondary pressure generated by the solenoid valve 62 acts on the pilot pressure receiving portion 46b of the arm control valve 46, the arm control valve 46 is switched to the retracted position. As a result, the hydraulic fluid discharged from the pump 81 is guided to the rod chamber of the arm cylinder 12a, and the hydraulic fluid is discharged from the bottom chamber to the tank 19, causing the arm cylinder 12a to contract. As a result, the arm 12 rotates upward (that is, the arm 12 performs a dump operation).
- the solenoid valve 63 uses the pilot primary pressure generated by the pilot pressure reducing valve 71 as source pressure to generate the pilot secondary pressure to be output to the pilot pressure receiving portion 149 of the bleed-off valve 140 .
- the solenoid valve 63 is controlled based on a signal (control current) output from the main controller 100 .
- the main controller 100 controls the electromagnetic valve 63 based on the gate lock lever signal output from the gate lock lever device 22 and the operation signals output from the operation devices 23 and 24 .
- the bleed-off valve 140 controls the position of the spool 141 (see FIG. 3) according to the pilot secondary pressure acting on the pilot pressure receiving portion 149 .
- the pilot secondary pressure is equivalent to the tank pressure
- the spring force of the return spring 163 holds the spool 141 at the neutral position.
- the aperture area of the diaphragm 150 becomes the maximum aperture area Amax.
- the spool 141 moves against the spring force of the return spring 163, and the opening area of the throttle 150 becomes smaller.
- the bleed-off valve 140 shuts off the communication between the pump 81 and the tank 19 .
- the aperture area of the diaphragm 150 becomes the minimum aperture area Amin (for example, 0). The details of the structure and control of the bleed-off valve 140 will be described later.
- a lock valve 74 is provided between the pilot pressure reducing valve 71 and the solenoid valves 51 , 52 , 61 , 62 , 63 .
- the lock valve 74 is an electromagnetic switching valve that is switched between a blocking position and a communicating position by a control signal output from the main controller 100 according to the operating position of the gate lock lever device 22 .
- the lock valve 74 When the gate lock lever device 22 is operated to the lock position, the lock valve 74 is switched to the blocking position. As a result, the pilot primary pressure to the solenoid valves 51, 52, 61, 62 is cut off, and the operation of the operating levers 23a, 24a is disabled. Moreover, since the pilot primary pressure to the solenoid valve 63 is cut off, the bleed-off valve 140 is held at the neutral position regardless of the operation by the operating devices 23 and 24 .
- the lock valve 74 is switched to the communicating position. Therefore, when the gate lock lever device 22 is operated to the unlocked position, the pilot secondary pressure is generated by the solenoid valves 51, 52, 61, 62 according to the operating direction and operating amount of the operating levers 23a, 24a.
- the actuators (11a, 12a) corresponding to the operated operating levers 23a, 24a are operated.
- pilot circuit HC2 is provided with the check valve 72 and the accumulator 73 as described above, even if the discharge pressure of the pump 81 temporarily becomes lower than the set pressure of the pilot pressure reducing valve 71, the pilot It is possible to maintain the primary pressure.
- the main controller 100 includes a CPU (Central Processing Unit) 101 as an operation circuit, a ROM (Read Only Memory) 102 as a storage device, a RAM (Random Access Memory) 103 as a storage device, an input/output interface 104, and other It consists of a microcomputer with peripheral circuits.
- the main controller 100 may be composed of one microcomputer or may be composed of a plurality of microcomputers.
- the engine controller 105 also has the same configuration as the main controller 100, is connected to the main controller 100, and exchanges information (data) with each other.
- the ROM 102 is a non-volatile memory such as an EEPROM, and stores programs capable of executing various calculations. That is, the ROM 102 is a storage medium capable of reading a program that implements the functions of this embodiment.
- a RAM 103 is a volatile memory and a work memory for directly inputting/outputting data to/from the CPU 101 . The RAM 103 temporarily stores necessary data while the CPU 101 is executing the program.
- the main controller 100 may further include a storage device such as a flash memory or hard disk drive.
- the CPU 101 is a processing device that develops a program stored in the ROM 102 into the RAM 103 and executes arithmetic operations, and performs predetermined arithmetic processing on signals received from the input/output interface 104, the ROM 102, and the RAM 103 according to the program.
- Input/output interface 104 receives signals from engine control dial 21, gate lock lever device 22, operating devices 23 and 24, pressure sensor 25, engine controller 105, and the like.
- the input unit of the input/output interface 104 converts the input signal so that the CPU 101 can perform calculations.
- the output section of the input/output interface 104 generates a signal for output according to the calculation result of the CPU 101, and sends the signal to the lock valve 74, the electromagnetic valves 51, 52, 61, 62, 63, the regulator 81a, and the like. Output.
- the pressure sensor 25 detects the pump discharge pressure (circuit pressure of the main circuit HC1) and outputs a signal representing the detection result (pump discharge pressure) to the main controller 100.
- the main controller 100 controls the displacement of the pump 81 by means of the regulator 81a based on the pump discharge pressure and the actual engine rotation speed detected by the sensors 25 and 80a and the operation signals from the operation devices 23 and 24.
- a hydraulic system 90 includes a control valve block 4 having a boom control valve 45, an arm control valve 46, a bleed-off valve 140, check valves 41 and 42, and a relief valve 47, and a second control valve having solenoid valves 51 and 52.
- a control valve block 4 having a boom control valve 45, an arm control valve 46, a bleed-off valve 140, check valves 41 and 42, and a relief valve 47, and a second control valve having solenoid valves 51 and 52.
- 1 solenoid valve block 5 a second solenoid valve block 6 having solenoid valves 61 , 62 and 63 , and a pilot primary pressure generating block 7 having a pilot pressure reducing valve 71 , a check valve 72 and a lock valve 74 .
- FIG. 3 is a schematic cross-sectional view of the bleed-off valve 140 mounted on the control valve block 4.
- the bleed-off valve 140 has a valve body 161 forming part of the valve housing of the control valve block 4, and a spool 141 that is a cylindrical valve body.
- the bleed-off valve 140 is not limited to being arranged in the illustrated orientation, and can be arranged in various orientations.
- the valve body 161 includes a slide hole 170 that slidably accommodates the spool 141, and a supply passage (corresponding to the bleed-off passage Lb) that communicates with the slide hole 170 and is supplied with hydraulic oil discharged from the pump 81. 171, a discharge passage (corresponding to the tank passage Lt) 172 communicating between the slide hole 170 and the tank 19, and between the supply passage 171 and the discharge passage 172 so as to be adjacent to the supply passage 171 and the discharge passage 172, respectively. It has a fluid chamber 197 provided in the slide hole 170 and a pilot passage 174 through which the pilot secondary pressure generated by the solenoid valve 63 is guided.
- a pilot pressure receiving portion (pressure receiving chamber) 149 is formed by the lower end portion of the slide hole 170 and the lower end portion of the spool 141 .
- the supply passage 171 and the discharge passage 172 are each connected to an annular recess formed so as to be recessed radially outward from the sliding surface of the spool 141 in the sliding hole 170 .
- the sliding hole 170 is formed so as to open to the end face (upper end face in the drawing) of the valve body 161, and the valve cap 162 is attached to the valve body 161 so as to cover this opening.
- a spring chamber 175 is formed on the illustrated upper end side of the spool 141 .
- a drain passage (not shown) connecting the spring chamber 175 and the tank 19 is formed in the valve cap 162 . Therefore, the spring chamber 175 is kept at a pressure corresponding to the tank pressure.
- the spring chamber 175 accommodates a return spring 163 as a biasing member that applies spring force to the spool 141 .
- the return spring 163 is a compression coil spring that biases the spool 141 in a direction (downward in the drawing) in which the opening area of the throttle 150 of the bleed-off valve 140 increases.
- the pilot passage 174 guides the pilot secondary pressure generated by the solenoid valve 63 to the pilot pressure receiving portion 149 . Hydraulic oil guided to pilot pressure receiving portion 149 biases spool 141 in a direction in which the opening area of throttle 150 of bleed-off valve 140 decreases (that is, in a direction opposite to the biasing direction of return spring 163).
- the spool 141 stops at a position where the thrust due to the pilot secondary pressure and the spring force of the return spring 163 are balanced. In this manner, the spool 141 is axially moved by the pilot secondary pressure generated by the solenoid valve 63, thereby changing the opening area (opening degree) of the throttle 150.
- the spool 141 has an axially extending internal passageway 146 of circular cross-section.
- the internal passage 146 is a hole that penetrates the spool 141 in the axial direction.
- the opening on the upper end side of the spool 141 is blocked by a rod 142 .
- Rod 142 is coupled to spool 141 and extends upward from the upper end of spool 141 .
- the opening on the lower end side of the spool 141 is closed by a plug.
- the axial direction is the central axis direction of the spool 141 , that is, the moving direction of the spool 141 .
- the outer diameter of the pilot passage 174 is smaller than the outer diameter of the slide hole 170. Therefore, a step surface 179 is formed between the slide hole 170 and the pilot passage 174 .
- the spool 141 is in a neutral position (stroke end on one end side) where downward movement is restricted by contact with the stepped surface 179, and upward movement by the rod 142 contacting the valve cap 162. is regulated (stroke end on the other end side) in the axial direction.
- the spool 141 has a plurality of land portions that slide along the inner peripheral surface of the slide hole 170, including a first land portion 181 provided on the lower end side (one end side in the axial direction) and a first land portion 181 provided on the upper end side (the other end side in the axial direction). ), and a second land portion 182 provided on the .
- the first land portion 181 and the second land portion 182 are provided axially apart from each other. Therefore, between the first land portion 181 and the second land portion 182 on the outer periphery of the spool 141, an annular groove 183 is formed which is recessed radially inward from the first land portion 181 and the second land portion 182.
- the fluid chamber 197 is formed by an annular recess 173 that is recessed radially outward from the sliding surface of the spool 141 in the sliding hole 170 .
- the outer peripheral portion of the first land portion 181 blocks communication between the supply passage 171 and the fluid chamber 197 on the outer peripheral side of the spool 141 .
- the supply passage 171 and the fluid chamber 197 communicate with each other through the internal passage 146 of the spool 141, as will be described later. Also, the first land portion 181 communicates or blocks the communication between the fluid chamber 197 and the discharge passage 172 .
- a first inlet hole 191 , a second inlet hole 192 , a third inlet hole 193 , and an outlet hole 196 are formed in the first land portion 181 as a plurality of through holes penetrating in the radial direction of the spool 141 . .
- These through holes (191, 192, 193, 196) are formed to have circular cross sections.
- One first inlet hole 191, one second inlet hole 192 and one third inlet hole 193 are provided.
- a plurality of outlet holes 196 are provided and are spaced apart in the circumferential direction.
- the radial direction (radial direction) of the spool 141 is orthogonal to the axial direction of the spool 141 .
- the lower end of the second inlet hole 192 is formed at a position separated from the upper end of the third inlet hole 193 by a predetermined distance.
- the first inlet hole 191 is formed at a position where its lower end is separated from the upper end of the second inlet hole 192 by a predetermined distance.
- the outlet hole 196 is formed at a position where its lower end is separated from the upper end of the second inlet hole 192 by a predetermined distance upward in the drawing.
- the first inlet hole 191, the second inlet hole 192, and the third inlet hole 193 constitute a first throttle 151 that functions as a throttle 150 that applies resistance to the hydraulic oil passing through.
- the outlet hole 196 is a communication hole that always communicates the internal passage 146 and the fluid chamber 197 regardless of the position of the spool 141 .
- the first inlet hole 191 and the second inlet hole 192 which are throttle holes, are closed to the supply passage 171 when the spool 141 is positioned at the neutral position on the one end side of the slide hole 170 (see FIG. 6A).
- the spool 141 communicates with the internal passage 146 and is positioned at a predetermined distance away from the neutral position on the other end side of the slide hole 170 (see FIGS. 6(c) to 6(e)). blocks communication between the supply passage 171 and the internal passage 146 .
- the opening area of the throttle 150 of the bleed-off valve 140 is smaller than when the first inlet hole 191 is in the open state.
- the opening area of the throttle 150 of the bleed-off valve 140 is smaller than when the second inlet hole 192 is in the open state. That is, the first inlet hole 191 and the second inlet hole 192 are adjustment holes for adjusting the opening area of the throttle 150 of the bleed-off valve 140 by communicating or blocking the supply passage 171 and the internal passage 146. function as
- FIG. 4 is a schematic cross-sectional view showing an enlarged part of the first land portion 181, showing the first inlet hole 191, the second inlet hole 192 and the third inlet hole 193.
- the total value (total opening area) of the opening areas of the first inlet hole 191, the second inlet hole 192, and the third inlet hole 193 is the total value (total opening area) of the opening areas of the plurality of outlet holes 196 (see FIG. 3).
- the plurality of outlet holes 196 have a plurality of total opening areas so that the passing pressure loss at the outlet holes 196 is negligibly small compared to the passing pressure loss at the inlet holes (191, 192, 193). is sufficiently large compared to the total opening area of the inlet holes (throttle holes).
- the opening area of the first inlet hole 191 is A11
- the opening area of the second inlet hole 192 is A12
- the opening area of the third inlet hole 193 is A13.
- the opening area A13 of the third inlet hole 193 is larger than the opening area A12 of the second inlet hole 192
- the opening area A13 of the third inlet hole 193 is larger than the opening area A11 of the first inlet hole 191 .
- the opening area A11 of the first inlet hole 191 may be larger than, smaller than, or the same as the opening area A12 of the second inlet hole 192 .
- a plurality of (for example, four) notch portions 144 are formed at the upper end portion (axial end portion) of the first land portion 181 .
- the plurality of cutouts 144 are spaced apart in the circumferential direction of the first land portion 181 .
- the notch portion 144 is formed in the shape of a groove that is recessed radially inward from the outer peripheral surface of the first land portion 181 .
- the notch portion 144 can also be said to be a concave portion that opens to the upper end surface and the outer peripheral surface of the first land portion 181 .
- the notch portion 144 extends from the upper end surface of the first land portion 181 in the axial direction of the spool 141 with a predetermined length L1 (see FIG. 5A).
- the bottom of the groove-shaped notch 144 is inclined so that the radial distance from the sliding surface of the spool 141 in the sliding hole 170 gradually decreases from the upper end surface of the first land portion 181 toward the lower end side. is doing.
- the cutout portion 144 refers to a portion formed by cutting out the axial end portion of the first land portion 181 . That is, the cutout portion 144 may be formed by cutting, or may be formed by a processing method such as forging or casting.
- the cross-sectional shape of the notch portion 144 can be various shapes such as a square shape, a semicircular shape, and a triangular shape.
- tapered cutouts having inclined portions formed over the entire circumference of the axial ends of the first land portions 181 may be provided.
- FIG. 5 is a schematic cross-sectional view showing an enlarged part of the spool 141 and the valve body 161, showing the outlet hole 196, the fluid chamber 197 and the notch 144.
- the valve body 161 is formed with a corner portion (hereinafter referred to as an upper corner portion) E1 at a position where the upper end surface of the annular recess 173 and the sliding surface of the sliding hole 170 intersect.
- a corner portion (hereinafter referred to as a lower corner portion) E2 is formed at a position where the lower end surface of the annular concave portion 173 and the sliding surface of the sliding hole 170 intersect.
- FIG. 5A shows a state in which the upper corner E1 does not face the cutout 144 in the radial direction
- FIG. 5B shows a state in which the upper corner E1 faces the cutout 144 in the radial direction.
- the opening area A20 of the channel cross section 194 formed by the notch 144 and the upper corner E1 is smaller than in the state shown in FIG. 5(a).
- the channel cross section 194 formed by the notch portion 144 and the upper corner portion E1 refers to a channel cross section including a straight line connecting the upper corner portion E1 and the notch portion 144 at the shortest distance. Therefore, in the state shown in FIG. 5(b), hydraulic oil passing through the flow passage cross section 194 formed by the notch 144 and the upper corner E1 has Provides great resistance.
- the second throttle 152 is formed by the gap between the notch portion 144 formed in the first land portion 181 of the spool 141 and the slide hole 170 of the valve body 161 . Therefore, the throttle 150 of the bleed-off valve 140 according to the present embodiment includes a first throttle 151 (see FIG. 4) formed by a plurality of throttle holes (191, 192, 193), a notch 144 and a sliding hole. 170 and a second diaphragm 152 (see FIG. 5(b)) formed by a gap.
- the throttle holes (191, 192, 193) have a radial length L2 that is shorter than the axial length L1 of the notch 144 (see FIG. 5A). formed to be
- the synthetic aperture area (opening degree) of the diaphragm 150 composed of the first diaphragm 151 and the second diaphragm 152 will be described.
- a first inlet hole 191, a second inlet hole 192, and a third inlet hole 193, which constitute the first throttle 151, are provided as parallel openings. Therefore, the opening area A10 of the first throttle 151 corresponds to the total opening area of the inlet holes (191, 192, 193) through which the hydraulic fluid passes.
- the first diaphragm 151 and the second diaphragm 152 are provided as serial apertures. Therefore, the synthetic aperture area (effective area) A0 of the first diaphragm 151 and the second diaphragm 152 is expressed by the following equation (1).
- A10 is the opening area of the first throttle 151
- A20 is the opening area of the second throttle 152 (the opening area of the channel cross section 194)
- the channel cross section 194 is a channel cross section in which the cross-sectional area of the channel formed by the gap between the notch portion 144 and the sliding hole 170 is the smallest.
- FIG. 6 is a diagram for explaining the flow of hydraulic oil at each position of the spool 141.
- FIG. 7 shows the opening area A10 (dashed line) of the first throttle 151 and the opening area
- FIG. 10 is a diagram showing A20 (chain line) and synthetic aperture area A0 (thick solid line) of the diaphragm 150;
- the position Y of the upper corner E1 and the position X of the upper end of the annular recess connected to the supply passage 171 are indicated by two-dot chain lines.
- the horizontal axis represents the position (spool stroke) of the spool 141
- the vertical axis represents the opening area. 7 correspond to the positions of the spool 141 in the states shown in FIGS. 6(a) to 6(e).
- FIG. 6(a) shows a state in which the spool 141 is positioned at the neutral position, which is the stroke end on one end side in the axial direction.
- hydraulic fluid flows from the supply passage 171 of the valve body 161 to the internal passage 146 of the spool 141 through the first inlet hole 191 , the second inlet hole 192 and the third inlet hole 193 of the spool 141 . be guided.
- Hydraulic oil guided to the internal passage 146 is guided to the fluid chamber 197 through the outlet hole 196 of the spool 141, and from the fluid chamber 197 to the discharge passage 172 through the annular flow path between the annular groove 183 and the slide hole 170. be killed.
- the aperture area A20 of the second aperture 152 is sufficiently larger than the aperture area A10 of the first aperture 151 .
- the hole 191 , the second inlet hole 192 and the third inlet hole 193 ) mainly function as the throttle 150 of the bleed-off valve 140 .
- the spool 141 is moved upward in the drawing by a predetermined distance from the state of FIG. It shows a state where In the state shown in FIG. 6( b ), hydraulic fluid is led from the supply passage 171 of the valve body 161 to the internal passage 146 of the spool 141 through the second inlet hole 192 and the third inlet hole 193 of the spool 141 . Hydraulic oil guided to the internal passage 146 is guided to the fluid chamber 197 through the outlet hole 196 of the spool 141, and from the fluid chamber 197 to the discharge passage 172 through the annular flow path between the annular groove 183 and the slide hole 170. be killed.
- the first inlet hole 191 is in a blocked state, and communication between the supply passage 171 and the internal passage 146 through the first inlet hole 191 is blocked.
- the opening area A20 of the second diaphragm 152 is sufficiently larger than the opening area A10 of the first diaphragm 151.
- FIG. therefore, as shown in FIG. 7, in the state of FIG.
- the synthetic aperture area A0 of the diaphragm 150 is substantially the same as the aperture area A10 of the first diaphragm 151, and
- the hole 192 and the third inlet hole 193 ) mainly function as the throttle 150 of the bleed-off valve 140 .
- the spool 141 moves upward in the drawing by a predetermined distance from the state of FIG. The state closed by the peripheral surface is shown.
- hydraulic fluid is led from the supply passage 171 of the valve body 161 to the internal passage 146 of the spool 141 through the third inlet hole 193 of the spool 141 .
- Hydraulic oil guided to the internal passage 146 is guided to the fluid chamber 197 through the outlet hole 196 of the spool 141, and from the fluid chamber 197 to the discharge passage 172 through the annular flow path between the annular groove 183 and the slide hole 170. be killed.
- the first inlet hole 191 and the second inlet hole 192 are closed, and the supply passage 171 and the internal passage 146 communicate with each other through the first inlet hole 191 and the second inlet hole 192. is blocked.
- the aperture area A20 of the second aperture 152 is sufficiently larger than the aperture area A10 of the first aperture 151 . Therefore, as shown in FIG. 7, in the state of FIG.
- the synthetic aperture area A0 of the diaphragm 150 is substantially the same as the aperture area A10 of the first diaphragm 151, and A hole 193 ) mainly functions as a throttle 150 of the bleed-off valve 140 .
- the spool 141 moves upward in the drawing by a predetermined distance from the state of FIG. 6(c), and the upper corner E1 of the valve body 161 and the upper end of the first land 181 are aligned in the radial direction.
- the state in which they face each other that is, the state in which the axial position of the upper end surface of the first land portion 181 coincides with the position Y of the upper corner portion E1 is shown.
- hydraulic fluid is led from the supply passage 171 of the valve body 161 to the internal passage 146 of the spool 141 through the third inlet hole 193 of the spool 141 .
- Hydraulic oil led to the internal passage 146 is led to the fluid chamber 197 through the outlet hole 196 of the spool 141 .
- Hydraulic oil guided to the fluid chamber 197 passes through the second throttle 152 formed by the gap between the notch portion 144 of the first land portion 181 and the slide hole 170, and flows through the annular groove 183 and the slide hole 170. is led to the discharge passage 172 through an annular flow path between .
- the opening area A20 of the second throttle 152 is smaller than that of FIG. 6(c), and the pressure loss caused by the second throttle 152 cannot be ignored. has grown to some extent. For this reason, as shown in FIG. 7, in the state of FIG. Function.
- the second throttle 152 (flow passage cross section 194 ) mainly functions as the throttle 150 of the bleed-off valve 140 .
- FIG. 6(e) shows a state in which the spool 141 has moved upward in the figure by a predetermined distance from the state of FIG. showing.
- communication between the fluid chamber 197 and the discharge passage 172 is blocked by the first land portion 181 .
- the synthetic opening area A0 of the throttle 150 becomes 0 (zero)
- the bleed-off flow rate becomes 0 (zero). That is, the hydraulic oil discharged from the pump 81 is no longer discharged to the tank 19 through the bleed-off valve 140 .
- the first throttle 151 is such that the spool 141 moves from one end side (lower end side in the drawing) of the slide hole 170 toward the other end side (upper end side in the drawing) as shown in FIG. It is formed so that the opening area A10 becomes smaller step by step.
- the second throttle 152 is arranged such that its opening area A20 continuously decreases as the spool 141 moves from one end side (lower end side in the figure) of the slide hole 170 toward the other end side (upper end side in the figure). formed in Therefore, from the neutral position (a) to the predetermined position Z, the synthetic opening area A0 gradually decreases as the spool 141 moves upward. As 141 moves upward, the synthetic aperture area A0 decreases continuously.
- the spool 141 has two moving regions in the axial direction, a first moving region (from the neutral position (a) to a predetermined position Z) in which the synthetic opening area A0 changes stepwise, and a moving region in which the synthetic opening area A0 changes continuously. and a second movement area (from the predetermined position Z to the blocking position (e)).
- first movement region as the spool 141 moves upward from the neutral position in the drawing, the synthetic opening area A0 decreases stepwise from (A11+A12+A13) ⁇ (A12+A13) ⁇ (A13).
- the opening areas A11, A12, and A13 of the first inlet hole 191, the second inlet hole 192, and the third inlet hole 193 are the operating pressure through which the hydraulic oil discharged from the pump 81 passes when the flow rate is the minimum flow rate.
- the oil pressure loss (passage pressure loss) is set to the target value.
- the pump discharge pressure (circuit pressure) P becomes the first target value P1 (eg, 2 MPa) in the state of FIG. 6(a), and the pump discharge pressure (circuit pressure) in the state of FIG. )P becomes the second target value P2 (for example, 3 MPa), and in the state of FIG. Aperture areas A11, A12, and A13 are set so as to occur.
- the first target value P1 of the pump discharge pressure P is set to a value equal to or greater than the minimum pressure (circuit pressure) required to generate the pilot primary pressure capable of moving the spool 141 of the bleed-off valve 140 .
- the first target value P1 a value equal to or higher than the circuit pressure at which the spool 141 of the bleed-off valve 140 can be moved to the state shown in FIG. 6(b) is adopted. Therefore, the first target value P1 can be set to a pressure at which the spools of the control valves 45, 46 cannot move against the centering springs.
- the second target value P2 of the pump discharge pressure P is set to a value greater than the first target value P1.
- a value equal to or higher than the circuit pressure at which the spool 141 of the bleed-off valve 140 can be moved to the state shown in FIG. 6(c) is adopted. Therefore, the second target value P2 can be set to a pressure at which the spools of the control valves 45 and 46 cannot be moved to full stroke against the centering springs.
- the third target value P3 of the pump discharge pressure P is set to a value greater than the second target value P2.
- a value equal to or higher than the circuit pressure that can move the spool 141 of the bleed-off valve 140 to the state shown in FIG. 6(e) is adopted.
- the third target value P3 is set to a pressure that allows the spools of the control valves 45 and 46 to move to full strokes against the centering springs.
- the main controller 100 shown in FIG. 2 controls the solenoid valve 63 to position the spool 141 in the first movement area (see FIG. 7) when the actuators are not operated by the operating devices 23 and 24. , to control the circuit pressure. Further, the main controller 100 positions the spool 141 in the second movement area (see FIG. 7) when the actuator is operated by the operation devices 23 and 24 with an operation amount larger than the predetermined value L0.
- the bleed-off flow rate is controlled by controlling the electromagnetic valve 63 so as to
- the main controller 100 sets the opening area of the diaphragm 150 to the maximum opening area Amax.
- the circuit pressure is controlled to P2 by controlling the position of the spool 141 so that the opening area (A12+A13) is one step smaller than .
- the main controller 100 controls the opening of the aperture.
- the circuit pressure is controlled to P3 or higher.
- FIG. 8 is a functional block diagram of the main controller 100.
- the main controller 100 executes a program stored in the ROM 102 to create an actuator target speed calculator C4, a bleed-off opening calculator C20, a bleed-off valve command generator C10, a control valve command generator C10, and a control valve command generator. It functions as a section C11, an actuator target flow rate calculation section C12, and a pump displacement command generation section C14.
- FIG. 9 is a diagram showing the details of the arithmetic processing performed by the actuator target speed calculator C4.
- the actuator target speed calculator C4 calculates the target speed of the actuator based on the information (operation signal) corresponding to each actuator.
- An example of calculating the target speed of the boom cylinder (actuator) 11a based on the operation signal of the boom cylinder (actuator) 11a will be described below as a representative example.
- the actuator target speed calculator C4 calculates the target speed of the boom cylinder 11a based on the operation signal of the boom cylinder 11a.
- the ROM 102 stores a table T4 in which operation signals and target speeds of the boom cylinder 11a are associated with each other.
- the table T4 shows the characteristic that the target speed increases as the absolute value of the operation amount of the control lever 23a increases.
- the actuator target speed calculation unit C4 refers to the table T4 and calculates the target speed of the boom cylinder 11a based on the operation signal input from the boom operation device 23.
- the target speed indicates the target speed in the extension direction of the boom cylinder 11a when positive, and the target speed in the retraction direction of the boom cylinder 11a when negative.
- the actuator target speed calculator C4 also calculates the target speeds of the arm cylinder 12a, the bucket cylinder 13a, the traveling hydraulic motor 2a, and the turning hydraulic motor 3a.
- FIG. 10 is a diagram showing the details of the arithmetic processing performed by the bleed-off aperture arithmetic unit C20. As shown in FIG. 10, the bleed-off opening calculator C20 calculates the reference opening area of the bleed-off valve 140 based on the gate lock lever signal and the actuator operation signal.
- the bleed-off aperture calculation unit C20 functions as a calculation unit O20a, a maximum value selection unit O20b, determination units O20c and O20e, and selection units O20d and O20f.
- the calculation unit O20a calculates absolute values of actuator operation signals (boom cylinder operation signal, arm cylinder operation signal, etc.).
- the maximum value selection unit O20b selects the largest one of the plurality of absolute values (the absolute value of the boom operation amount, the absolute value of the arm operation amount, etc.) calculated by the calculation unit O20a.
- the determination unit O20c determines whether the maximum value selected by the maximum value selection unit O20b is greater than a predetermined threshold value Th1.
- the threshold value Th1 is predetermined and stored in the ROM 102 to determine whether or not the operating levers (operating levers 23a, 24a, etc.) of the actuator are being operated.
- the threshold Th1 is, for example, a value of about 3% when the maximum operation amount of the control lever is 100%. That is, the maximum value selection unit O20b and the determination unit O20c determine whether at least one of the operation levers (operation levers 23a, 24a, etc.) of the actuator is operated depending on whether the maximum value of the operation signal is greater than the threshold value Th1. It is determined whether there is
- the selection unit O20d determines that the maximum value selected by the maximum value selection unit O20b is greater than the threshold value Th1 and that at least one of the operation levers of the actuator is being operated. Then, the opening area A13 is selected.
- the determination unit O20c makes a negative determination
- the selection unit O20d determines that the maximum value selected by the maximum value selection unit O20b is equal to or smaller than the threshold value Th1, and none of the operation levers of the actuator is being operated. , and the opening area A12+A13 is selected.
- the determination unit O20e determines whether the gate lock lever device 22 is operated to the lock position.
- the selection unit O20f selects the opening area A11+A12+A13 as the reference opening area, and issues a bleed-off valve command. Output to the generation unit C10.
- the determination unit O20e makes a negative determination, that is, when it determines that the gate lock lever device 22 is operated to the unlocked position
- the selection unit O20f selects the opening area (A13 or A12+A13) selected by the selection unit O20d. is selected as the reference opening area, and is output to the bleed-off valve command generator C10.
- FIG. 11 is a diagram showing the details of the arithmetic processing performed by the bleed-off valve command generating section C10.
- the bleed-off valve command generation unit C10 controls the solenoid valve 63 that drives the bleed-off valve 140 based on the operation signal of the actuator and the reference opening area calculated by the bleed-off opening calculation unit C20.
- the bleed-off valve command generation unit C10 functions as a calculation unit O10a, a minimum value selection unit O10b, and a calculation unit O10c.
- the ROM 102 stores tables T10a1 and T10a2 in which actuator operation signals (boom cylinder 11a operation signal, arm cylinder 12a operation signal, etc.) are associated with operation required opening areas of the bleed-off valve 140.
- the computation unit O10a computes the operation required opening area based on the operation signal corresponding to each actuator. An example of calculating the operation required opening area based on the operation signal of the boom cylinder 11a will be described below as a representative example.
- the computation unit O10a computes the operation required opening area of the bleed-off valve 140 based on the operation signal of the boom cylinder 11a.
- the table T10a1 has a characteristic that the required operation opening area decreases as the absolute value of the operation amount of the operation lever 23a increases. In this embodiment, when the operating lever 23a is positioned in the dead zone including the neutral position, the operation required aperture area is set to a value equal to or larger than the maximum aperture area Amax ( ⁇ A11+A12+A13) of the diaphragm 150. Further, the table T10a1 is set so that the required operation opening area corresponds to the opening area A13 of the third inlet hole 193 when the absolute value of the operation amount is a predetermined value L0.
- the computation unit O10a refers to the table T10a1 and computes the required operation opening area based on the operation signal input from the boom operation device 23. Further, the computation unit O10a refers to the table 10a2 and computes the operation required opening area based on the operation signal input from the arm operation device 24. FIG. Furthermore, although not shown, the computing unit 10a computes the operation required opening area based on the operation signal of the bucket cylinder 13a, the operation signal of the traveling hydraulic motor 2a, and the operation signal of the turning hydraulic motor 3a.
- the minimum value selection unit O10b selects the smallest of the plurality of required operation opening areas calculated by the calculation unit 10a and the reference opening area calculated by the bleed-off opening calculation unit C20, and selects the selected one. It is set as the target opening area At of the bleed-off valve 140 .
- the minimum value selection unit O10b outputs the target opening area At of the bleed-off valve 140 to the calculation unit O10c. Note that the minimum value selection unit O10b also outputs the target opening area At of the bleed-off valve 140 to the pump volume command generation unit C14 (see FIG. 8).
- the calculation unit O10c refers to the current conversion table T10c stored in the ROM 102, and calculates the target value of the control current to be supplied to the solenoid valve 63 based on the target opening area At input from the minimum value selection unit O10b. .
- the calculation unit O10c generates a bleed-off valve command for controlling the control current supplied to the solenoid valve 63 to a target value, and outputs the generated bleed-off valve command to a current control unit (not shown). Based on the bleed-off valve command, the current control section controls the control current so that the control current supplied to the solenoid of the solenoid valve 63 becomes a target value.
- FIG. 12 is a diagram showing the details of the arithmetic processing performed by the control valve command generation unit C11.
- the control valve command generator C11 generates control valve commands for controlling the solenoid valves 51, 52, 61, 62 that drive the control valves 45, 46.
- FIG. The control valve command generation unit C11 refers to the table T11a stored in the ROM 102, and based on the operation signal of the actuator (boom cylinder 11a, arm cylinder 12a), the target value of the control current to be supplied to the solenoid valves 51, 52.
- the control valve command generation unit C11 refers to the table T11b stored in the ROM 102, and based on the operation signal of the actuator (boom cylinder 11a, arm cylinder 12a), the target value of the control current to be supplied to the solenoid valves 61, 62. to calculate
- the control valve command generator C11 generates a control valve command for controlling the control current supplied to the solenoid valves 51, 52, 61, 62 to a target value, and sends the generated control valve command to a current controller (not shown). ). Based on the control valve command, the current control unit controls the control current so that the control current supplied to the solenoids of the solenoid valves 51, 52, 61, 62 becomes a target value.
- FIG. 13 is a diagram showing the details of the arithmetic processing performed by the actuator target flow rate calculator C12.
- the actuator target flow rate calculation section C12 calculates the target flow rate of the actuator based on the information (target speed and operation signal) corresponding to each actuator.
- An example of calculating the target flow rate of the boom cylinder 11a based on the target speed and the operation signal of the boom cylinder 11a will be described below as a representative example.
- the actuator target flow rate calculation unit C12 functions as multiplication units O12a and O12b, a determination unit O12c, and a selection unit O12d.
- the multiplication unit O12a multiplies the target speed (positive value) of the boom cylinder 11a calculated by the actuator target speed calculation unit C4 by (Sbot) to calculate the bottom side inflow target flow rate.
- Sbot is the pressure receiving area on the bottom side of the boom cylinder 11a (the pressure receiving area for two cylinders).
- the multiplier O12b multiplies the target speed (negative value) of the boom cylinder 11a calculated by the actuator target speed calculator C4 by (-Srod) to calculate the rod side inflow target flow rate.
- Srod is the pressure receiving area Srod on the rod side of the boom cylinder 11a (pressure receiving area for two cylinders).
- the determination unit O12c determines whether or not the boom operation amount is a positive value based on the operation signal of the boom cylinder 11a. When the determination unit O12c determines that the boom operation amount is a positive value, the selection unit O12d determines the bottom side inflow target flow rate as the target flow rate for the boom cylinder 11a. When the determination unit O12c determines that the boom operation amount is not a positive value, the selection unit O12d determines the rod-side inflow target flow rate as the target flow rate for the boom cylinder 11a.
- the actuator target flow rate calculation unit C12 calculates the operation signal and target speed of the arm cylinder 12a, the operation signal and target speed of the bucket cylinder 13a, the operation signal and target speed of the travel hydraulic motor 2a, and the operation signal and target speed of the turning hydraulic motor 3a. Each target flow rate is calculated based on the operation signal and the target speed.
- FIG. 14 is a diagram showing the details of the arithmetic processing performed by the pump volume command generation unit C14.
- the pump volume command generator C14 generates a pump volume command to be output to the regulator 81a that controls the discharge volume of the pump 81.
- the pump volume command generation unit C14 functions as an integration unit O14a, a calculation unit O14b, multiplication units O14c and O14d, an addition unit O14e, a maximum value selection unit O14f, a division unit O14g, a minimum value selection unit O14h, and a division unit O14i.
- the integration unit O14a integrates the target flow rates of each actuator (boom cylinder 11a, arm cylinder 12a, etc.) calculated by the actuator target flow rate calculation unit C12, and calculates the target flow rate total value.
- the calculation unit O14b takes the square root of the pump discharge pressure P detected by the pressure sensor 25.
- the multiplication unit O14c multiplies the calculation result (square root of the pump discharge pressure P) of the calculation unit O14b by the target opening area At of the bleed-off valve 140 calculated by the bleed-off valve command generation unit C10.
- Multiplication unit O14d multiplies the calculation result of multiplication unit O14c by the flow coefficient c stored in ROM 102 to calculate the bleed-off flow rate (flow rate of hydraulic oil passing through bleed-off valve 140).
- the addition unit O14e adds the bleed-off flow rate, which is the calculation result of the multiplication unit O14d, to the target flow rate total value, which is the calculation result of the integration unit O14a, to calculate the
- the maximum value selection unit O14f compares the required pump flow rate Qr, which is the calculation result of the addition unit O14e, and the minimum flow rate Qmin, and selects the larger one.
- the minimum flow rate Qmin is a flow rate (equipment protection set value) set to prevent damage to the pump 81 and is stored in the ROM 102 in advance.
- the division unit O14g divides the maximum horsepower set value by the pump discharge pressure P to calculate the pump flow rate limit value Ql based on the horsepower limit.
- the minimum value selection unit O14h compares the flow rate (Qr or Qmin) selected by the maximum value selection unit O14f and the pump flow rate limit value Ql, which is the calculation result of the division unit O14g, and selects the smaller one. The resulting flow rate is determined as the pump target flow rate Qt.
- the division unit O14i divides the pump target flow rate Qt, which is the result of calculation by the minimum value selection unit O14h, by the actual engine rotation speed detected by the engine rotation speed sensor 80a to calculate the target value of the discharge capacity (displacement volume). .
- Division unit O14i generates a pump volume command for controlling the discharge volume of pump 81 to a target value, and outputs the generated pump volume command to regulator 81a.
- FIG. 15 shows the gate lock lever device 22 and the target opening area At of the bleed-off valve 140, which is set according to the operation of the operating lever of the actuator, and the discharge flow rate of the pump 81, which is set according to the operation of the operating lever of the actuator ( 4 is a time chart showing changes in a pump target flow rate (Qt) and a discharge pressure P detected by a pressure sensor 25;
- the horizontal axis of FIG. 15 indicates time (time).
- the vertical axis of FIG. 15(a) indicates the operating position of the gate lock lever device 22
- the vertical axis of FIG. 15(b) indicates the operating signal of the actuator (operating amount of the operating lever)
- the vertical axis of FIG. 15(c). indicates the target opening area At of the bleed-off valve 140 set by the main controller 100, and the vertical axis of FIG. Qt)
- FIG. 15( e ) shows the pump discharge pressure P detected by the pressure sensor 25 .
- the throttle holes (191, 192, 193) of the first throttle 151 apply resistance to the hydraulic oil passing through, and the pump discharge pressure P (circuit pressure of the main circuit HC1) is reduced to the first target value P1 (for example, 2 MPa). Since the control lever of the actuator is not operated, the pump discharge flow rate is the minimum flow rate Qmin.
- the main controller 100 increases the control current supplied to the solenoid of the electromagnetic valve 63 to increase the pilot secondary pressure acting on the pilot pressure receiving portion 149 of the bleed-off valve 140, thereby causing the spool 141 to move to the position shown in FIG. It is moved to the position shown in (b).
- the throttle holes (192, 193) of the first throttle 151 apply resistance to the hydraulic oil passing through, and the pump discharge pressure P rises by one step to reach the second target value P2 (eg, 3 MPa).
- the spool 141 By raising the pump discharge pressure P up to the second target value P2, the spool 141 is quickly driven in the direction of decreasing the opening area of the throttle 150 of the bleed-off valve 140 when the operation of the operating lever is started. It will be in a state where it can be done.
- the operation lever 23a of the boom operation device 23 is operated from the neutral position.
- the main controller 100 increases the pilot secondary pressure acting on the pilot pressure receiving portion 149 of the bleed-off valve 140 by increasing the control current value supplied to the solenoid of the solenoid valve 63, thereby causing the spool 141 to move. It is moved to the position shown in 6(c).
- the throttle hole (193) of the first throttle 151 applies resistance to the hydraulic oil passing through, and the pump discharge pressure P further increases by one step to reach the third target value P3 (eg, 4 MPa).
- the responsiveness of the spool 141 of the bleed-off valve 140 to the operation of the control lever can be further enhanced.
- the circuit pressure is such that the spools of the control valves 45 and 46 can be moved to full stroke by operating the operating levers 23a and 24a.
- the main controller 100 converts the operation required opening area (opening area less than A13) calculated based on the operation signal to the target opening area of the bleed-off valve 140. Set as At. Therefore, after time t4, the target opening area At of the bleed-off valve 140 decreases as the amount of operation of the control lever 23a increases.
- the target opening area At of the bleed-off valve 140 is set to A13 immediately after the check valve 41 opens, part of the hydraulic oil discharged from the pump 81 can escape to the tank 19 through the bleed-off valve 140. can.
- the target opening area At of the bleed-off valve 140 continuously decreases, the flow rate of hydraulic oil supplied to the boom cylinder 11a continuously increases. As a result, it is possible to prevent a shock from occurring due to a sudden increase in the flow rate of the hydraulic oil supplied to the boom cylinder 11a, and it is possible to smoothly operate the boom cylinder 11a.
- the plurality of apertures (191, 192, 193) constitute the first aperture 151
- the notch 144 constitutes the second aperture 152
- the first aperture is The pressure loss generated at 151 is used to keep the circuit pressure at a predetermined pressure.
- a plurality of throttle holes (191, 192, 193) are spaced apart in the axial direction. Therefore, as shown in FIG. 7, movement areas Ac1, Ac2, and Ac3 capable of keeping the synthetic opening area A0 constant can be secured as movement areas of the spool 141 in the axial direction.
- the circuit pressure when the circuit pressure is maintained at the predetermined pressures P1, P2 and P3, by positioning the spool 141 within the moving regions Ac1, Ac2 and Ac3, disturbance such as vibration and changes in hydraulic oil temperature can be prevented. It is possible to prevent the synthetic opening area A0 from changing when the position of the spool 141 is displaced in the axial direction. That is, according to the present embodiment, the circuit pressure can be adjusted with higher accuracy than in the comparative example, so that the circuit pressure necessary for generating the pilot primary pressure can be stably ensured.
- the hydraulic excavator (work machine) 1 includes a main circuit HC1 that supplies the working fluid discharged from the pump 81 to the actuators, and a main circuit HC1 provided in the main circuit HC1 that controls the flow of the working fluid supplied from the pump 81 to the actuators.
- Electromagnetic valves (second pressure reducing valves) 51, 61, 52, 62 for generating pilot secondary pressure acting on pilot pressure receiving portions 45a, 45b, 46a, 46b of 45, 46, pump 81 and tank 19 are connected.
- the bleed-off valve 140 passes through a spool 141 that moves in the axial direction and a valve body 161 that slidably accommodates the spool 141 by a pilot secondary pressure generated by an electromagnetic valve (third pressure reducing valve) 63. and a restriction 150 that provides resistance to the working fluid.
- the movement area of the spool 141 in the axial direction includes a first movement area in which the opening area (opening degree) of the diaphragm 150 changes stepwise, and a second movement area in which the opening area (opening degree) of the diaphragm 150 changes continuously.
- the main controller 100 controls the electromagnetic valve (third pressure reducing valve) 63 so as to position the spool 141 in the first movement area when the actuators are not operated by the operating devices 23 and 24 .
- the main controller 100 controls the electromagnetic valve (second 3 pressure reducing valve) 63 is controlled.
- the throttle 150 has throttle holes (first inlet hole 191, second inlet hole 192, and third inlet hole 193) that provide resistance to the working fluid passing through it when the spool 141 is positioned in the first movement area. have.
- the actuator when the actuator is not operated, the working fluid passes through the throttle holes (the first inlet hole 191, the second inlet hole 192, and the third inlet hole 193), thereby generating pressure loss. Therefore, the circuit pressure necessary for generating the pilot primary pressure can be stably secured.
- the valve body 161 slides between a slide hole 170 that slidably accommodates the spool 141 and a supply passage 171 that communicates with the slide hole 170 and is supplied with the working fluid discharged from the pump 81 . It has a discharge passage 172 communicating the hole 170 and the tank 19 , and a fluid chamber 197 provided in the slide hole 170 so as to be adjacent to the discharge passage 172 .
- the spool 141 includes a first land portion (land portion) 181 that communicates or blocks the discharge passage 172 and the fluid chamber 197, an internal passage 146, and a plurality of throttle holes (second land portions) that communicate the supply passage 171 and the internal passage 146.
- the throttle 150 of the bleed-off valve 140 is formed by a first throttle 151 composed of a plurality of throttle holes (first inlet hole 191, second inlet hole 192, and third inlet hole 193) and a first land portion 181. and a second throttle 152 formed by a gap between the notch 144 and the slide hole 170 .
- the first throttle 151 is formed such that its opening area gradually decreases as the spool 141 moves from one end side of the sliding hole 170 toward the other end side.
- the second throttle 152 is formed such that its opening area continuously decreases as the spool 141 moves from one end side of the sliding hole 170 toward the other end side.
- the circuit pressure can be changed stepwise by stepwise changing the opening area of the first diaphragm 151 .
- the bleed-off flow rate can be continuously changed, so that the actuator can be operated smoothly.
- the first throttle 151 communicates the supply passage 171 and the internal passage 146 when the spool 141 is positioned at one end of the slide hole 170, and the spool 141 is positioned at the other end of the slide hole 170.
- the throttle holes (the first inlet hole 191 and the second inlet hole 192) that block the communication between the supply passage 171 and the internal passage 146 when the supply passage 171 and the internal passage 146 are closed, and the supply passage 171 and the internal passage 146 regardless of the position of the spool 141. and a throttle hole (third inlet hole 193) that communicates with the
- the first inlet hole 191 and the second inlet hole 192 that transition from the communicating state to the blocking state are provided. Therefore, by closing only the first inlet hole 191 when the pump discharge flow rate is at a predetermined value (for example, minimum flow rate), the pump discharge pressure P is changed from the first target value P1 to the second target value P2. By increasing by one step and closing both the first inlet hole 191 and the second inlet hole 192, the pump discharge pressure P can be further increased by one step from the second target value P2 to the third target value P3. can. With this configuration, the circuit pressure can be changed stepwise to three pressure states.
- the efficiency of energy consumption can be improved, and the operation of the spool 141 of the bleed-off valve 140 and the spools of the control valves 45 and 46 can be improved. responsiveness and movable range can be adjusted.
- the hydraulic excavator 1 selectively operates a gate lock lever device (locked position) between a lock position that prohibits the operation of the actuators (11a, 12a) and an unlocked position that permits the operation of the actuators (11a, 12a).
- the main controller 100 controls the opening area of the diaphragm 150.
- the gate lock lever device 22 When the gate lock lever device 22 is operated to the unlocked position, the main controller 100 operates the actuators (11a, 12a) by operating devices 23, 24 with an operation amount equal to or less than a predetermined value L0. is being performed, the position of the spool 141 is controlled so that the aperture area of the diaphragm 150 is two steps smaller than the maximum aperture area Amax (A13).
- the opening area of the diaphragm 150 becomes the maximum opening area Amax, so the energy consumption efficiency can be maximized.
- the pump discharge pressure P rises by one step to secure the circuit pressure necessary to generate the pilot pressure necessary to drive the control valves 45 and 46. energy consumption efficiency can be improved to some extent.
- the pump discharge pressure P decreases. Furthermore, since it rises by one step, it becomes possible to operate the control valves 45 and 46 to full stroke according to the operation.
- the throttle holes are through holes that penetrate the spool 141 in the radial direction, and the length L2 in the radial direction is a notch portion. It is formed to be shorter than the axial length L1 of 144 . If the radial length L2 of the throttle hole is too long, the change in pressure loss caused by the temperature change (viscosity change) of the working fluid becomes large. For example, when the temperature of the working fluid is low and the viscosity is high, the pressure loss increases and the circuit pressure may become excessive.
- the radial length L2 of the throttle holes (the first inlet hole 191, the second inlet hole 192, and the third inlet hole 193) is shorter than the axial length L1 of the notch 144. , the influence of temperature change (viscosity change) of the working fluid can be reduced. Therefore, it is possible to prevent the circuit pressure from becoming excessive when the temperature of the working fluid is low, and prevent the circuit pressure from becoming insufficient when the temperature of the working fluid is high.
- the configuration of the bleed-off valve 140 is not limited to the configuration described in the above embodiment.
- two adjustment holes the first inlet hole 191 and the second inlet hole 192 that transition from the communicating state to the blocked state were provided. You may make it provide in a spool.
- one of the two adjustment holes may be omitted.
- the first inlet hole (adjustment hole) 191 may be formed to have an opening area of A11+A12, and the second inlet hole (adjustment hole) 192 may be omitted.
- ⁇ Modification 1-1> A method of setting the target opening area when only one adjustment hole is used for transitioning from the communicating state to the blocking state will be described.
- the main controller 100 according to Modification 1-1 sets the target opening area At of the bleed-off valve 140 to A11+A12+A13 regardless of the operating position of the gate lock lever device 22.
- FIG. Further, the main controller 100 according to Modification 1-1 sets the target opening area At of the bleed-off valve 140 to A13 when the operation amount of the operation lever of the actuator exceeds the threshold value Th1.
- the target opening area At of the bleed-off valve 140 is set to A13. Therefore, the responsiveness of the operation of the spool 141 of the bleed-off valve 140 and the spools of the control valves 45, 46 in response to the operation of the operating devices 23, 24 is higher in the above embodiment than in this modified example.
- ⁇ Modification 1-2> Another method of setting the target opening area when there is only one adjustment hole that transitions from the communicating state to the blocking state will be described.
- the main controller 100 according to Modification 1-2 sets the target opening area At of the bleed-off valve 140 to A11+A12+A13 when the operation position of the gate lock lever device 22 is operated to the lock position. Further, the main controller 100 according to Modification 1-2 sets the target opening area At of the bleed-off valve 140 to A13 when the operation position of the gate lock lever device 22 is operated to the unlock position. .
- the target opening area At of the bleed-off valve 140 is set to A13. Therefore, the energy consumption efficiency of the above embodiment is higher than that of this modified example.
- FIG. 16 is similar to FIG. 3 and is a schematic cross-sectional view of a bleed-off valve 240 according to Modification 2.
- the spool 241 is not formed with the annular groove 183 (see FIG. 3).
- the annular recess 173 is not formed in the slide hole 270 .
- the cutout portion 144 is not formed in the bleed-off valve 240 according to this modification.
- the structure of the bleed-off valve 240 according to this modified example will be mainly described with respect to the differences from the above-described embodiment.
- the valve body 261 includes a slide hole 270 that slidably accommodates the spool 241 , a supply passage 171 that communicates with the slide hole 270 and is supplied with hydraulic oil discharged from the pump 81 , and the slide hole 270 . and a discharge passage 172 communicating with the tank 19 .
- the spool 241 includes an internal passage 146, a plurality of throttle holes (an inlet hole 291, an inlet hole 292, an inlet hole 298, and an inlet hole 299) communicating the supply passage 171 and the internal passage 146, the internal passage 146 and the discharge passage 172. and a plurality of exit holes 296 in communication with.
- the total opening area of the multiple outlet holes 296 is sufficiently larger than the total opening area of the multiple throttle holes (291, 292, 298, 299).
- the throttle 250 of the bleed-off valve 240 is composed of a plurality of throttle holes (291, 292, 298, 299).
- the inlet holes 291 and 292 are throttle holes having a circular cross-section that are spaced apart from each other in the axial direction. It is formed so that the area (opening degree) becomes smaller step by step.
- the opening area of the diaphragm 250 changes from the maximum opening area to the opening area smaller by one step.
- the opening area of the diaphragm 250 changes to an opening area that is one step smaller.
- the inlet holes 298 and 299 are throttle holes formed so that the opening area (opening degree) of the throttle 250 continuously decreases as the spool 241 moves from one end side of the slide hole 270 toward the other end side. is.
- the inlet hole 298 and the inlet hole 299 are spaced apart in the circumferential direction.
- the inlet hole 298 includes an elliptical base hole portion 298b whose major axis is arranged along the axial direction, and an elliptical base hole portion 298b that extends axially from one end (lower end in the drawing) of the base hole 298b toward the lower end of the spool 241. and a cut-out portion 298a formed to be present.
- the cutout portion 298a has a proximal cutout portion 298a1 formed continuously from the base hole portion 298b and a distal cutout portion 298a2 extending downward from the proximal cutout portion 298a1. .
- the width of the distal cutout portion 298a2 is shorter than the width of the proximal cutout portion 298a1.
- the base hole portion 298b and the notch portion 298a penetrate the spool 241 in the radial direction.
- the inlet hole 299 has an elliptical base hole portion 299b whose long axis is arranged along the axial direction, and an axis extending from one end (lower end in the figure) of the base hole 299b toward the lower end of the spool 241. and a cutout portion 299a formed to extend in the direction.
- the notch 299a has a proximal notch 299a1 formed continuously from the base hole 299b and a distal notch 299a2 extending downward from the proximal notch 299a1. .
- the width of the distal cutout portion 299a2 is shorter than the width of the proximal cutout portion 299a1.
- the base hole portion 299b and the notch portion 299a penetrate the spool 241 in the radial direction.
- the main controller 100 positions the spool 241 at a neutral position where all of the plurality of inlet holes (291, 292, 298, 299) are fully open. As a result, the opening area of the diaphragm 250 becomes the maximum opening area Amax, so that the circuit pressure is held at the first target value P1.
- the main controller 100 controls the plurality of entrance holes (291, 292, 298, 299), The spool 241 is positioned so that only the inlet hole 291 is fully closed.
- the opening area of the diaphragm 250 becomes one step smaller than the maximum opening area Amax, and the circuit pressure is maintained at the second target value P2, which is one step higher than the first target value P1.
- the main controller 100 controls the entrance holes 291 and 292. is fully closed and the inlet holes 298 and 299 are fully opened.
- the aperture area of the diaphragm 250 becomes an aperture area that is two steps smaller than the maximum aperture area Amax.
- the opening areas of the inlet holes 291 and 292 become smaller as the amount of operation increases.
- the opening areas of the base holes 298b and 299b which have a larger channel cross-sectional area than the cutouts 298a and 299a, become smaller, and then the opening areas of the cutouts 298a and 299a become smaller. Therefore, the larger the amount of operation of the operating levers 23a and 24a, the smaller the absolute value of the rate of change in the opening area with respect to the amount of operation. Therefore, the actuator can be operated more smoothly than when the rate of change in the opening area with respect to the operation amount is constant.
- the axial length of the spool 241 can be shortened by omitting the fluid chamber 197 . That is, by miniaturizing the control valve block 4, it is possible to reduce the product cost.
- the main controller 100 sets the target aperture area At of the diaphragm 150 to A11+A12. Then, when the gate lock lever device 22 is operated to the lock position from this state, the target opening area At of the diaphragm 150 is set to A11+A12+A13. On the other hand, for example, in a state where the target aperture area At of the diaphragm 150 is set to A11+A12, the main controller 100 sets the target opening area At of the diaphragm 150 to the target area At of the diaphragm 150 when the actuator is not operated for a predetermined time or longer. The opening area At may be set to A11+A12+A13.
- the radial length L2 of the throttle holes (the first inlet hole 191, the second inlet hole 192, and the third inlet hole 193) is set to be shorter than the axial length L1 of the notch 144.
- the invention is not limited to this.
- the radial length L2 of the throttle hole is formed to be equal to or longer than the axial length L1 of the notch 144. good too.
- grooves 390a, 390b and 390c of a predetermined length are formed in the first land portion 181 along the circumferential direction, and the grooves 390a, 390b and 390c are formed at the bottoms of the grooves 390a, 390b and 390c.
- the throttle holes 391, 392, 393 having a diameter smaller than the width in the axial direction may be provided. As a result, the influence of the viscosity of the hydraulic oil can be reduced by shortening the channel length (radial length) of the throttle holes 391, 392, and 393 while improving the strength of the spool 141.
- the aperture holes (the first inlet hole 191, the second inlet hole 192, and the third inlet hole 193) have a circular cross-sectional shape
- the cross-sectional shape of the throttle hole can be various shapes such as an elliptical shape, an elliptical shape, and a polygonal shape.
- Main controller 140 Control Device 140, 240 Bleed-off valve 141, 241 Spool 144 Notch 146 Internal passage 149 Pilot pressure receiving portion 161, 261 Valve body 170, 270 Sliding hole , 171... Supply passage 172... Discharge passage 173... Annular recess 174... Pilot passage 175... Spring chamber 181... First land (land) 191, 391... First inlet hole (throttle hole), 192, 392... Second inlet hole (throttle hole) 193, 393... Third inlet hole (throttle hole) 194... Flow path cross section 196... Outlet hole (communication hole) 197... Fluid chamber 291... Inlet hole (throttle hole), 292... inlet hole (throttle hole), 296... outlet hole, 298, 299...
- inlet hole (throttle hole), 298a, 299a... notch, 298b, 299b... base hole, A0... synthetic aperture Area (aperture area of aperture)
- HC1 Main circuit HC2 Pilot circuit L0 Predetermined value Lb Bleed-off passage
- Ld Pump discharge passage Lp Parallel passage
- Lt Tank passage P Pump discharge pressure (Circuit pressure of main circuit), Th1... Threshold
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Fluid-Pressure Circuits (AREA)
Abstract
Description
ブリードオフ弁140の構成は、上記実施形態で説明した構成に限定されない。上記実施形態では、連通状態から遮断状態に遷移する調整孔(第1入口孔191及び第2入口孔192)を2つ設ける例について説明したが、軸方向に離間する3つ以上の調整孔をスプールに設けるようにしてもよい。また、2つの調整孔のうち、1つを省略してもよい。例えば、第1入口孔(調整孔)191は、その開口面積がA11+A12となるように形成し、第2入口孔(調整孔)192は省略してもよい。
連通状態から遮断状態に遷移する調整孔を1つにした場合の目標開口面積の設定方法について説明する。本変形例1-1に係るメインコントローラ100は、ゲートロックレバー装置22の操作位置にかかわらず、ブリードオフ弁140の目標開口面積AtをA11+A12+A13に設定する。また、本変形例1-1に係るメインコントローラ100は、アクチュエータの操作レバーの操作量が閾値Th1を超えると、ブリードオフ弁140の目標開口面積AtをA13に設定する。
連通状態から遮断状態に遷移する調整孔を1つにした場合の目標開口面積の別の設定方法について説明する。本変形例1-2に係るメインコントローラ100は、ゲートロックレバー装置22の操作位置がロック位置に操作されている場合には、ブリードオフ弁140の目標開口面積AtをA11+A12+A13に設定する。また、本変形例1-2に係るメインコントローラ100は、ゲートロックレバー装置22の操作位置がロック解除位置に操作されている場合には、ブリードオフ弁140の目標開口面積AtをA13に設定する。
図16を参照して、上記実施形態の変形例2について説明する。図16は、図3と同様の図であり、変形例2に係るブリードオフ弁240の断面模式図である。以下では、上記実施形態で説明したブリードオフ弁140と異なる点について主に説明する。図16に示すように、本変形例では、スプール241に環状溝183(図3参照)が形成されていない。また、摺動孔270に環状凹部173(図3参照)が形成されていない。さらに、本変形例に係るブリードオフ弁240には、上記実施形態で説明した切り欠き部144(図3参照)も形成されていない。以下、本変形例に係るブリードオフ弁240の構造について、上記実施形態とは異なる点を主に説明する。
上記実施形態では、ゲートロックレバー装置22がロック解除位置に操作されている場合であって、アクチュエータの操作が行われていないときには、メインコントローラ100は、絞り150の目標開口面積AtをA11+A12に設定し、その状態からゲートロックレバー装置22がロック位置に操作されると、絞り150の目標開口面積AtをA11+A12+A13に設定する。これに対して、例えば、メインコントローラ100は、絞り150の目標開口面積AtがA11+A12に設定されている状態において、アクチュエータの操作が予め定めた所定時間以上行われなかった場合に、絞り150の目標開口面積AtをA11+A12+A13に設定してもよい。
上記実施形態では、絞り孔(第1入口孔191、第2入口孔192及び第3入口孔193)の径方向の長さL2が切り欠き部144の軸方向の長さL1よりも短くなるように形成される例について説明したが、本発明はこれに限定されない。例えば、温度変化の少ない作業環境で作業を行う油圧ショベル1においては、絞り孔の径方向の長さL2は、切り欠き部144の軸方向の長さL1と同じか長くなるように形成してもよい。
図17に示すように、第1ランド部181に周方向に沿うように所定長さの溝390a,390b,390cを形成し、この溝390a,390b,390cの底部に溝390a,390b,390cの軸方向の幅よりも径が小さい絞り孔391,392,393を設けるようにしてもよい。これにより、スプール141の強度の向上を図りつつ、絞り孔391,392,393の流路長(径方向長さ)を短くすることにより、作動油の粘性の影響を低減することができる。
上記実施形態では、絞り孔(第1入口孔191、第2入口孔192及び第3入口孔193)の断面形状が円形状である例について説明したが、本発明はこれに限定されない。絞り孔の断面形状は、楕円形状、長円形状、多角形状等、種々の形状とすることができる。
上記実施形態では、作業機械がクローラ式の油圧ショベル1である場合を例に説明したが、本発明はこれに限定されない。ホイール式の油圧ショベル、ホイールローダ、クローラクレーン等、種々の作業機械に本発明を適用することができる。
Claims (6)
- ポンプから吐出される作動流体をアクチュエータに供給するメイン回路と、
前記メイン回路に設けられ、前記ポンプから前記アクチュエータに供給される作動流体の流れを制御する制御弁と、
前記ポンプから吐出される作動流体の一部を前記制御弁のパイロット受圧部に導くパイロット回路と、
前記パイロット回路に設けられ、前記ポンプから吐出される作動流体の圧力を減圧してパイロット1次圧を生成する第1減圧弁と、
前記パイロット回路に設けられ、前記パイロット1次圧を減圧して、前記制御弁のパイロット受圧部に作用するパイロット2次圧を生成する第2減圧弁と、
前記ポンプとタンクとを接続するブリードオフ通路と、
前記ブリードオフ通路に設けられるパイロット駆動式のブリードオフ弁と、
前記パイロット回路に設けられ、前記パイロット1次圧を減圧して、前記ブリードオフ弁のパイロット受圧部に作用するパイロット2次圧を生成する第3減圧弁と、
前記アクチュエータを操作するための操作装置と、
前記操作装置による操作に基づいて、前記第3減圧弁を制御する制御装置と、を備える作業機械において、
前記ブリードオフ弁は、
前記第3減圧弁によって生成されるパイロット2次圧によって、軸方向に移動するスプールと、
前記スプールを摺動自在に収容するバルブボディと、
通過する作動流体に抵抗を付与する絞りと、を有し、
前記スプールの軸方向の移動領域は、前記絞りの開口面積が段階的に変化する第1移動領域と、前記絞りの開口面積が連続的に変化する第2移動領域と、を有し、
前記制御装置は、
前記操作装置による前記アクチュエータの操作が行われていないときには、前記スプールを前記第1移動領域に位置させるように前記第3減圧弁を制御し、
前記操作装置により、予め定めた所定値よりも大きい操作量で前記アクチュエータの操作が行われているときには、前記スプールを前記第2移動領域に位置させるように前記第3減圧弁を制御し、
前記絞りは、前記スプールが前記第1移動領域に位置しているときに、通過する作動流体に抵抗を付与する絞り孔を有する、
ことを特徴とする作業機械。 - 請求項1に記載の作業機械において、
前記バルブボディは、
前記スプールを摺動自在に収容する摺動孔と、
前記摺動孔に連通し、前記ポンプから吐出される作動流体が供給される供給通路と、
前記摺動孔と前記タンクとを連通する排出通路と、
前記排出通路に隣接するように前記摺動孔に設けられる流体室と、を有し、
前記スプールは、
前記排出通路と前記流体室とを連通または遮断するランド部と、
内部通路と、
前記供給通路と前記内部通路とを連通する複数の前記絞り孔と、
前記内部通路と前記流体室とを連通する連通孔と、を有し、
前記ランド部の軸方向端部には、切り欠き部が形成され、
前記絞りは、前記複数の絞り孔によって構成される第1絞りと、前記ランド部に形成された前記切り欠き部と前記摺動孔との隙間によって形成される第2絞りと、によって構成される、
ことを特徴とする作業機械。 - 請求項2に記載の作業機械において、
前記第1絞りは、
前記スプールが前記摺動孔の一端側に位置しているときには前記供給通路と前記内部通路とを連通し、前記スプールが前記摺動孔の他端側に位置しているときには前記供給通路と前記内部通路との連通を遮断する絞り孔と、
前記スプールの位置にかかわらず、前記供給通路と前記内部通路とを連通する絞り孔と、によって構成される、
ことを特徴とする作業機械。 - 請求項2に記載の作業機械において、
前記絞り孔は、前記スプールの径方向に貫通する貫通孔であり、その径方向の長さが前記切り欠き部の軸方向の長さよりも短くなるように形成される、
ことを特徴とする作業機械。 - 請求項1に記載の作業機械において、
前記バルブボディは、
前記スプールを摺動自在に収容する摺動孔と、
前記摺動孔に連通し、前記ポンプから吐出される作動流体が供給される供給通路と、
前記摺動孔と前記タンクとを連通する排出通路と、を有し、
前記スプールは、
内部通路と、
前記供給通路と前記内部通路とを連通する複数の入口孔と、
前記内部通路と前記排出通路とを連通する出口孔と、を有し、
前記絞りは、前記複数の入口孔によって構成され、
前記複数の入口孔には、ベース孔部と、前記ベース孔部の端部から前記スプールの軸方向に延在する切り欠き部が形成された入口孔が含まれる、
ことを特徴とする作業機械。 - 請求項1に記載の作業機械において、
前記アクチュエータの動作を禁止するロック位置と前記アクチュエータの動作を許可するロック解除位置とに選択的に操作されるロックレバー装置、をさらに備え、
前記制御装置は、
前記ロックレバー装置が前記ロック位置に操作されている場合、前記絞りの開口面積が最大開口面積となるように前記スプールの位置を制御し、
前記ロックレバー装置が前記ロック解除位置に操作されている場合であって、前記操作装置による前記アクチュエータの操作が行われていないときには、前記絞りの開口面積が最大開口面積よりも一段階小さい開口面積となるように前記スプールの位置を制御し、
前記ロックレバー装置が前記ロック解除位置に操作されている場合であって、前記操作装置により、前記所定値以下の操作量で前記アクチュエータの操作が行われているときには、前記絞りの開口面積が最大開口面積よりも二段階小さい開口面積となるように前記スプールの位置を制御する、
ことを特徴とする作業機械。
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Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
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JPH0412498U (ja) * | 1990-05-18 | 1992-01-31 | ||
JP2001263304A (ja) | 2000-03-16 | 2001-09-26 | Shin Caterpillar Mitsubishi Ltd | 流体圧回路装置 |
JP2004360898A (ja) * | 2003-05-15 | 2004-12-24 | Kobelco Contstruction Machinery Ltd | 作業機械の油圧制御装置 |
JP2012002289A (ja) * | 2010-06-17 | 2012-01-05 | Hitachi Constr Mach Co Ltd | 油圧駆動装置 |
JP2019094973A (ja) * | 2017-11-22 | 2019-06-20 | キャタピラー エス エー アール エル | 建設機械の油圧制御回路 |
-
2021
- 2021-03-18 CN CN202180095736.XA patent/CN116981851A/zh active Pending
- 2021-03-18 KR KR1020237031109A patent/KR20230142617A/ko unknown
- 2021-03-18 WO PCT/JP2021/011261 patent/WO2022195832A1/ja active Application Filing
- 2021-03-18 JP JP2023506652A patent/JPWO2022195832A1/ja active Pending
- 2021-03-18 EP EP21931579.3A patent/EP4293236A1/en active Pending
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0412498U (ja) * | 1990-05-18 | 1992-01-31 | ||
JP2001263304A (ja) | 2000-03-16 | 2001-09-26 | Shin Caterpillar Mitsubishi Ltd | 流体圧回路装置 |
JP2004360898A (ja) * | 2003-05-15 | 2004-12-24 | Kobelco Contstruction Machinery Ltd | 作業機械の油圧制御装置 |
JP2012002289A (ja) * | 2010-06-17 | 2012-01-05 | Hitachi Constr Mach Co Ltd | 油圧駆動装置 |
JP2019094973A (ja) * | 2017-11-22 | 2019-06-20 | キャタピラー エス エー アール エル | 建設機械の油圧制御回路 |
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WO2024071261A1 (ja) * | 2022-09-29 | 2024-04-04 | 日立建機株式会社 | 作業機械 |
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CN116981851A (zh) | 2023-10-31 |
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