WO2013190726A1 - 作業機 - Google Patents
作業機 Download PDFInfo
- Publication number
- WO2013190726A1 WO2013190726A1 PCT/JP2012/081994 JP2012081994W WO2013190726A1 WO 2013190726 A1 WO2013190726 A1 WO 2013190726A1 JP 2012081994 W JP2012081994 W JP 2012081994W WO 2013190726 A1 WO2013190726 A1 WO 2013190726A1
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- WO
- WIPO (PCT)
- Prior art keywords
- pressure
- load pressure
- flow passage
- load
- hydraulic
- Prior art date
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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
- F15B13/026—Pressure compensating valves
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F3/00—Dredgers; Soil-shifting machines
- E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
- E02F3/96—Dredgers; Soil-shifting machines mechanically-driven with arrangements for alternate or simultaneous use of different digging elements
- E02F3/963—Arrangements on backhoes for alternate use of different tools
- E02F3/964—Arrangements on backhoes for alternate use of different tools of several tools mounted on one machine
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2221—Control of flow rate; Load sensing arrangements
- E02F9/2225—Control of flow rate; Load sensing arrangements using pressure-compensating valves
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2221—Control of flow rate; Load sensing arrangements
- E02F9/2239—Control of flow rate; Load sensing arrangements using two or more pumps with cross-assistance
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2278—Hydraulic circuits
- E02F9/2282—Systems using center bypass type changeover valves
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2278—Hydraulic circuits
- E02F9/2285—Pilot-operated systems
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2278—Hydraulic circuits
- E02F9/2292—Systems with two or more pumps
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2278—Hydraulic circuits
- E02F9/2296—Systems with a variable displacement pump
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
- F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
- F15B11/163—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for sharing the pump output equally amongst users or groups of users, e.g. using anti-saturation, pressure compensation
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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
- F15B7/00—Systems in which the movement produced is definitely related to the output of a volumetric pump; Telemotors
- F15B7/003—Systems in which the movement produced is definitely related to the output of a volumetric pump; Telemotors with multiple outputs
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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
- F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
- F15B2211/25—Pressure control functions
- F15B2211/253—Pressure margin control, e.g. pump pressure in relation to load pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/305—Directional control characterised by the type of valves
- F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
- F15B2211/3053—In combination with a pressure compensating valve
- F15B2211/30555—Inlet and outlet of the pressure compensating valve being connected to the directional control valve
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/605—Load sensing circuits
- F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
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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
- F15B2211/65—Methods of control of the load sensing pressure
- F15B2211/651—Methods of control of the load sensing pressure characterised by the way the load pressure is communicated to the load sensing circuit
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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
- F15B2211/65—Methods of control of the load sensing pressure
- F15B2211/652—Methods of control of the load sensing pressure the load sensing pressure being different from the load pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
- F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
- F15B2211/7135—Combinations of output members of different types, e.g. single-acting cylinders with rotary motors
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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
- F15B2211/80—Other types of control related to particular problems or conditions
- F15B2211/86—Control during or prevention of abnormal conditions
- F15B2211/8613—Control during or prevention of abnormal conditions the abnormal condition being oscillations
Definitions
- the present invention relates to a work machine such as a backhoe equipped with a load sensing system.
- the load sensing system includes a flow control unit for controlling the main pump in addition to the variable capacity main pump, the direction switching valve, and the pressure compensation valve, and controls the flow rate using the discharge pressure of the main pump as the PPS signal pressure. And a PPS transmission line that transmits the highest load pressure of the load pressures of the hydraulic actuator as a PLS signal pressure to the flow rate control unit.
- the flow rate controller controls the discharge pressure of the main pump so that the differential pressure obtained by subtracting the PLS signal pressure from the PPS signal pressure is maintained at a constant pressure.
- the load sensing system is configured such that when a plurality of hydraulic actuators are operated, an amount corresponding to an operation amount is applied to each operated hydraulic cylinder regardless of a difference in load acting on the operated hydraulic actuator.
- the discharge flow rate of the main pump is divided so that only the pressure oil is supplied.
- the pressure compensation valve is provided with a load pressure flow passage for introducing the load pressure of the hydraulic actuator corresponding to the pressure compensation valve and outputting it to the PLS transmission line.
- the present invention provides a work machine that exhibits quick response when a hydraulic actuator is started, and that can improve machine stability during operation after the hydraulic actuator is started. This is the issue.
- the technical means taken by the present invention to solve the technical problems are characterized by the following points.
- the invention according to claim 1 includes a plurality of hydraulic actuators and a variable displacement hydraulic pump that supplies pressure oil to these hydraulic actuators, and subtracts the highest load pressure of the hydraulic actuator from the discharge pressure of the hydraulic pump.
- a first load pressure flow path that introduces a load pressure of the hydraulic actuator and outputs it to a PLS transmission line that transmits the highest load pressure of the hydraulic actuator when the hydraulic actuator is activated;
- a reduced second load pressure flow passage is provided.
- the direction switching valve which controls the supply direction of the pressure oil discharged from the said hydraulic pump and supplies it to the said hydraulic actuator is provided corresponding to each hydraulic actuator, Pressure compensation valves that function to keep the pressure constant are provided for each direction switching valve, The pressure compensation valve is provided with the first load pressure flow passage and the second load pressure flow passage, and the first load pressure flow passage functions from the stroke start end to the middle of the stroke of the pressure compensation valve.
- the second load pressure flow passage functions during a full stroke.
- the first load pressure flow passage is not provided with a throttle
- the second load pressure flow passage is provided with a throttle so that the flow amount of the pressure oil in the second load pressure flow passage is reduced to the first. It is characterized by being reduced more than the load pressure flow passage.
- a throttle is provided in both of the first load pressure flow passage and the second load pressure flow passage, and the second load pressure flow with respect to the flow path opening area of the throttle of the first load pressure flow passage. The flow amount of the pressure oil in the second load pressure flow passage is made smaller than that in the first load pressure flow passage by reducing the flow path opening area of the passage restriction.
- the pressure compensation valve includes a load pressure introduction port for introducing the load pressure of the hydraulic actuator, and a load for outputting the load pressure of the hydraulic actuator introduced from the load pressure introduction port to the PLS transmission line.
- the load pressure inlet port and the load pressure outlet port communicate with each other through the first load pressure flow passage from the stroke start end of the pressure compensation valve to the middle of the stroke, and switch from the middle of the stroke to communicate with each other through the second load pressure flow passage. It is characterized by.
- the present invention has the following effects. According to the first aspect of the present invention, when the hydraulic actuator is started, the load pressure of the hydraulic actuator passes through the first load pressure flow passage having a larger amount of pressure oil flow than the second load pressure flow passage. Therefore, the control response of the hydraulic pump is high, the control pressure follows instantaneously, and the quick response is demonstrated.
- the load pressure of the hydraulic actuator is transmitted to the PLS transmission line via the second load pressure flow passage whose flow rate is limited rather than the first load pressure flow passage. Therefore, the transmission response of the PLS signal pressure is slowed by the second load pressure flow passage, and the body stability of the work implement can be improved by suppressing the followability of the control pressure to the hydraulic pump.
- the structure can be simplified by incorporating the first load pressure flow passage and the second load pressure flow passage into the pressure compensation valve.
- the load pressure of the hydraulic actuator is transmitted through the flow path without the throttle, and during the operation after the start of the hydraulic actuator, the load of the hydraulic actuator is transmitted through the flow path with the throttle.
- the load pressure of the hydraulic actuator is transmitted through the flow path having a large throttle, and during the operation after the hydraulic actuator is started, the load of the hydraulic actuator is transmitted by the small flow path.
- a quick response is exhibited at the time of starting the hydraulic actuator, and a work machine that can increase the stability of the machine body is easily implemented during the operation after starting the hydraulic actuator. be able to.
- the pressure compensation valve is provided with the load pressure introduction port and the load pressure outlet port, and these ports communicate with each other through the first load pressure flow passage from the stroke start end of the pressure compensation valve to the middle of the stroke.
- the middle of the stroke and communicating with the second load pressure flow passage, it provides quick response when the hydraulic actuator is activated, and is stable during operation after the hydraulic actuator is activated. It is possible to easily realize a working machine that can improve the performance.
- FIG. 3 is a hydraulic circuit diagram showing a left half portion of the hydraulic circuit in FIG. 2.
- FIG. 3 is a hydraulic circuit diagram showing a right half portion of the hydraulic circuit of FIG. 2. It is a side view of a backhoe. It is a hydraulic circuit figure concerning other embodiments.
- symbol 1 is the backhoe illustrated as a working machine.
- the backhoe 1 is mainly composed of a lower traveling body 2 and an upper revolving body 3 that is mounted on the traveling body 2 so as to be pivotable around a vertical pivot axis.
- the traveling body 2 includes crawler type traveling devices 6 configured to circulate around the crawler belt 5 in the circumferential direction by traveling motors ML and MR composed of hydraulic motors on both the left and right sides of the track frame 4.
- a dozer device 7 is provided at the front portion of the track frame 4, and the blades of the dozer device 7 can be raised and lowered by expansion and contraction of a dozer cylinder C1 formed of a hydraulic cylinder.
- the swivel body 3 is mounted on the track frame 4 so as to be rotatable about a swivel axis, and constitutes a swivel base 8 and a front working device 9 (excavation) mounted on the front portion of the swivel base 8.
- Working device and a cabin 10 mounted on the swivel base 8.
- the swivel base 8 is provided with an engine E, a radiator, a fuel tank, a hydraulic oil tank, a battery, and the like.
- the swivel base 8 can be swiveled by a swivel motor MT including a hydraulic motor.
- a swing bracket 12 is provided at the front of the swivel base 8 and is supported by a support bracket 11 provided so as to project forward from the swivel base 8 so as to be swingable left and right around an axis in the vertical direction.
- the swing bracket 12 can be swung left and right by expansion and contraction of a swing cylinder C2 formed of a hydraulic cylinder.
- the front work device 9 includes a boom 13 whose base side is pivotally connected to the upper portion of the swing bracket 12 so as to be pivotable about a left and right axis, and is swingable up and down, and a base side of the boom 13 around the left and right axis.
- the arm 14 is pivotally connected to the arm 14 so as to be swingable back and forth
- the bucket 15 is pivotally connected to the front end side of the arm 14 so as to be pivotable around the left and right axes so as to be swingable back and forth. And is composed mainly of.
- the boom 13 is raised by extending a boom cylinder C3 interposed between the boom 13 and the swing bracket 12, and is lowered by contracting the boom cylinder C3.
- the arm 14 swings backward by extending an arm cylinder C4 interposed between the arm 14 and the boom 13 to perform a cloud operation (scratching operation), and contracts the arm cylinder C4. Oscillates forward and dumps.
- the bucket 15 swings backward by extending a bucket cylinder C5 interposed between the bucket 15 and the arm 14 and performs a cloud operation (crawl operation), and contracts the bucket cylinder C5. Dumps by swinging forward.
- the boom cylinder C3, arm cylinder C4, and bucket cylinder C5 are each constituted by a hydraulic cylinder.
- the hydraulic system includes a pressure oil supply unit PSU, a control valve CVU, and a flow rate control unit FCU.
- the pressure oil supply unit PSU outputs first to third pumps P1, P2 and P3 which are hydraulic pumps driven by the engine E, and pressure oil discharged from the first to third pumps P1, P2 and P3.
- First to fourth discharge ports Pa, Pb, Pc, Pd are provided.
- the first pump P1 (main pump) is a swash plate type variable displacement axial pump and is constituted by an equal flow double pump (split flow type hydraulic pump) that can obtain an equal discharge amount from two independent discharge ports. .
- the pressure oil discharged from one discharge port of the first pump P1 is output from the first discharge port Pa, and the pressure oil discharged from the other discharge port of the first pump P1 is output from the second discharge port Pb. Is done.
- the second pump P2 and the third pump P3 are constituted by a constant displacement type gear pump, and the pressure oil discharged from the second pump P2 is output from the third discharge port Pc, and the pressure oil discharged from the third pump P3. Is output from the fourth discharge port Pd.
- the pressure oil discharged from the first pump P1 is used for the travel motors ML, MR, the hydraulic cylinders C3, C4, C5 of the front working device 9, and the swing cylinder C2, and the pressure discharged from the second pump P2.
- the oil is mainly used for the swing motor MT and the dozer cylinder C1 and also used for the boom cylinder C3, the arm cylinder C4, the bucket cylinder C5 and the swing cylinder C2, and the pressure oil discharged from the third pump P3 is used as a pilot. Used for supplying signal pressure such as pressure and detection signal.
- the 1st pump P1 may be comprised from two pumps formed separately.
- the control valve CVU includes control valves V1 to V8 for controlling various hydraulic actuators ML, MR, and MTC1 to C5, first to third intermediate blocks B1 to 3, and first and second end blocks B4 and B5 in one direction. And aggregate.
- V1 is a swing control valve that controls the swing cylinder C2
- V2 is a bucket control valve that controls the bucket cylinder C5
- V3 is an arm control valve that controls the arm cylinder C4
- V4 is a boom control that controls the boom cylinder C3.
- V5 is a right travel control valve that controls the right travel motor MR
- V6 is a left travel control valve that controls the left travel motor ML
- V7 is a dozer control valve that controls the dozer cylinder C1
- V8 is a swing motor MT. It is a turning control valve to control.
- each of the control valves V1 to V8 includes direction switching valves DV1 to DV8 for switching the direction of pressure oil in the valve body VB, and further includes a swing control valve V1, a bucket control valve V2, and an arm control.
- the valve V3 and the boom control valve V4 when a plurality of the boom cylinder C3, the arm cylinder C4, the bucket cylinder C5, and the swing cylinder C2 are used, the valve V3 and the boom control valve V4 function as adjustment of the load between the cylinders C2 to C5.
- Pressure compensation valves (compensator valves) CV1 to CV4 are incorporated in the valve body VB.
- Each of the direction switching valves DV1 to DV8 is composed of a direct acting spool type switching valve and a pilot operation switching valve that is switched by a pilot pressure. Further, the spools of the direction switching valves DV1 to DV8 are moved in proportion to the operation amounts of the operation means for piloting the direction switching valves DV1 to DV8, and the amount of movement of the direction switching valves DV1 to DV8. Is supplied to the hydraulic actuators ML, MR, MT, C1 to 5 to be controlled, and the operation of the operation target (control target) is proportional to the operation amount of each operation means. The speed can be changed.
- the first intermediate block B1 is provided with an unload valve V9 in which the spool is urged in the closing direction by a spring and a main relief valve V10 of the first pump P1
- the second intermediate block B2 is provided with a first flow path switching valve V11 constituted by a direct-acting spool type pilot operation switching valve and relief valves V12, V13 for travel control valves V5, V6.
- the block B3 is provided with a second flow path switching valve V14 constituted by a direct-acting spool type pilot operation switching valve.
- the first intermediate block B1 is interposed between the boom control valve 4 and the second intermediate block B2, and the second intermediate block B2 is interposed between the right travel control valve V5 and the first intermediate block B1,
- the 3 middle block B3 is interposed between the left travel control valve V6 and the dozer control valve V7.
- the first end block B4 is connected to the swing control valve V1
- the second end block B5 is connected to the swing control valve V8.
- a first discharge port Pa is connected to the first flow path switching valve V ⁇ b> 11 via a first discharge path 16, and a second discharge port Pb is connected via a second discharge path 17.
- the first flow path switching valve V11 includes a first discharge path 16 and a second discharge path to the front work system supply line 18 that supplies pressure oil to the boom control valve 4, the arm control valve V3, the bucket control valve V2, and the swing control valve V1.
- a merging position 19 for connecting the road 17 and a traveling left supply path 20 that supplies pressure oil to the left traveling control valve V6 a first discharge path 16 connected to the traveling left supply path 20 and pressure oil that supplies pressure oil to the right traveling control valve V5.
- the supply path 21 can be switched to an independent supply position 22 where the second discharge path 17 is connected, switched to a merging position 19 by a spring, and switched to an independent supply position 22 by a pilot pressure.
- the front work system supply line 18 is provided from the first intermediate block B1 to the respective valve bodies VB of the boom control valve 4, the arm control valve V3, the bucket control valve V2, and the swing control valve V1, and one end thereof is a main relief valve. Connected to V10 and the other end is closed. Further, the front work system supply line 18 is connected to the direction switching valves DV1 to DV4 of the swing control valve V1, the bucket control valve V2, the arm control valve V3, and the boom control valve V4 via the hydraulic oil supply path 23, respectively. Yes.
- the control valve CVU is provided with a drain line 24 from the first end block B4 to the turning control valve V8.
- a front work system supply line 18 is connected to the drain line 24 via a connection oil passage 25 and an unload valve V9, and direction control valves DV1 to DV8 of the control valves V1 to V8 are drain oil passages. 26 is connected.
- the second flow path switching valve V14 extends from the third discharge port Pc and passes through the direction switching valve DV8 of the turning control valve V8 and the direction switching valve DV7 of the dozer control valve V7 in sequence.
- the third discharge path 27 is connected to a supply path 28 for supplying pressure oil to the swivel and dozer control valves.
- One end of a connection passage 29 is connected to the upstream side of the second flow path switching valve V14 of the third discharge passage 27 and the downstream side of the dozer control valve V7, and the other end of the connection passage 29 is connected to the front work system. Connected to the supply line 18.
- the connection passage 29 is provided with a check valve V15 for preventing the backflow of pressure oil from the front work system supply line 18 side.
- the second flow path switching valve V14 connects the third discharge path 27 to the drain line 24, thereby not supplying the pressure oil from the second pump P2 to the front work system supply line 18, and a third supply position 30.
- the discharge oil from the second pump P2 can be switched to the supply position 31 for supplying the front working system supply line 18 via the connection passage 29, and the spring Is switched to the non-supplying position 30 and is switched to the supplying position 31 by the pilot pressure.
- the pressure oil output from the fourth discharge port Pd is divided into the valve operation detection line 32, the first pilot pressure supply path 33, and the second pilot pressure supply path 34.
- the valve operation detection line 32 includes a first signal pressure introducing portion 35 provided in the second end block, a direction switching valve DV8 of the swing control valve V8, a direction switching valve DV7 of the dozer control valve V7, and a direction of the left travel control valve V6.
- Switching valve DV6 Direction switching valve DV5 of right-side traveling control valve V5 ⁇ Direction switching valve DV4 of boom control valve V4 ⁇ Direction switching valve DV3 of arm control valve V3 ⁇ Direction switching valve DV2 of bucket control valve V2 ⁇ Swing control valve V1 It is connected to the drain line 24 via the direction switching valve DV1.
- An AI switch 36 comprising a pressure switch is connected between the first signal pressure introducing portion 35 and the turning control valve V8 of the valve operation detection line 32, and any one of the control valves V1 to V8 is operated from a neutral position. As a result, a part of the valve operation detection line 32 is cut off, a pressure is generated in the valve operation detection line 32, and this pressure is detected by the AI switch 36. If the pressure is not detected by the AI switch 36, the rotational speed of the engine E is automatically reduced to idling rotation, and if the pressure is detected by the AI switch 36, the rotational speed of the engine E is automatically increased to a predetermined rotational speed. Thus, the rotational speed of the engine E is automatically controlled.
- the first pilot pressure supply path 33 is introduced from the second signal pressure introduction section 37 to the third intermediate block B3 and connected to the pilot pressure receiving section of the second flow path switching valve V14. Is connected to one end of the first flow path switching oil passage 38, and the other end of the first flow path switching oil passage 38 is connected to the pilot pressure receiving portion of the first flow path switching valve V11. Further, one end side of the travel detection line 39 is connected to the first flow path switching oil passage 38, and the other end side of the travel detection line 39 is the direction switching valve DV6 of the left traveling control valve ⁇ the direction switching valve of the right traveling control valve. It is connected to the drain line 24 through DV5.
- the second pilot pressure supply path 34 is introduced from the third signal pressure introduction unit 40 to the first intermediate block B1, and is downstream of the right travel control valve V5 and upstream of the boom control valve V4 of the valve operation detection line 32. Connected at a connection point 41.
- One end side of the second flow path switching oil passage 42 is connected between the connection point 41 and the third signal pressure introducing portion 40, and the other end side of the second flow path switching oil passage 42 is the second flow path switching valve. It is connected to the pilot pressure receiving part of V14.
- the first flow path switching valve V11 is set to the merge position 19 and the second flow path switching valve V14 is not supplied. 30 and the discharge oil from the first pump P1 is merged so that the pressure oil can be supplied to the direction switching valves DV1 to DV4 of the swing, bucket, arm, and boom control valves V1 to 4, The pressure oil from the two pumps P2 is drained after passing through the swing control valve V8 and the dozer control valve V7.
- this hydraulic system the discharge amount of the hydraulic pump P1 is controlled in accordance with the load pressure of the hydraulic actuators C2 to C5, and the hydraulic power required for the load is discharged from the hydraulic pump P1.
- a load sensing system that can save energy and improve operability is adopted.
- this load sensing system is the first to the load pressure of the boom cylinder C3, the arm cylinder C4, the bucket cylinder C5, and the swing cylinder C2 in a state where the first flow path switching valve V11 is at the merge position 19. It functions to control the discharge pressure (discharge amount) of one pump P1, and compensates pressure after the spools of the directional control valves DV1 to DV4 of the swing control valve V1, bucket control valve V2, arm control valve V3, and boom control valve 4. It is an after-orifice type load sensing system to which valves CV1 to CV4 are respectively connected.
- the load sensing system includes a PPS transmission line 43 that transmits the discharge pressure (PPS signal pressure) of the first pump P1 to the flow rate control unit FCU, a swing cylinder C2, a bucket cylinder C5, and an arm cylinder C4.
- the PLS transmission line 44 transmits the maximum load pressure (PLS signal pressure) of the load pressure of the boom cylinder C3 to the flow control unit FCU.
- the flow rate control unit FCU is configured so that the differential pressure obtained by subtracting the PLS signal pressure from the PPS signal pressure (“PPS signal pressure ⁇ PLS signal pressure”) is maintained at a constant pressure (control differential pressure).
- the swash plate control cylinder 45 that controls the plate is controlled to control the discharge pressure (discharge amount) of the first pump P1.
- the PPS transmission line 43 is connected to the first flow path switching valve V ⁇ b> 11, and the connection oil path 46 is routed in a state where the first flow path switching valve V ⁇ b> 11 is switched to the merge position 19.
- the PPS transmission line 43 communicates with the drain line 24 via the relief oil passage 47, and the PPS signal pressure becomes zero.
- the swash plate angle of the first pump P1 becomes MAX, and the first pump P1 discharges the maximum flow rate.
- the PLS transmission line 44 is connected to a load pressure detection line 48 provided in the control valve CVU.
- the load pressure detection line 48 is provided from the first intermediate block B1 to the valve body VB of the boom control valve 4, the valve body VB of the arm control valve V3, the valve body VB of the bucket control valve V2, and the valve body VB of the swing control valve V1.
- the one end side is connected to a spring-side pilot pressure receiving portion that urges the spool of the unload valve V9 in the closing direction, and the other end side is closed.
- the load pressure detection line 48 is connected to the pressure compensation valves CV1 to CV4 of the swing control valve V1, the bucket control valve V2, the arm control valve V3, and the boom control valve 4, respectively. 49 is connected.
- loads acting on the swing cylinder C2, the boom cylinder C3, the arm cylinder C4, and the bucket cylinder C5 are transmitted to the load pressure detection line 48 through the load pressure transmission oil passages 49, and the swing cylinder C2,
- the maximum load pressure among the loads acting on the boom cylinder C3, the arm cylinder C4, and the bucket cylinder C5 is transmitted as a PLS signal pressure from the load pressure detection line 48 to the flow rate control unit FCU via the PLS transmission line 44.
- the boom control valve V4 will be described in detail with reference to FIG. Since the arm control valve V3, the bucket control valve V2, and the swing control valve V1 are configured in the same manner as the boom control valve 4 except for a part, the arm control valve V3, the bucket control valve V2, and the swing control valve V1. With respect to, the same reference numerals are assigned to the same parts as those of the boom control valve 4 and the description thereof is omitted.
- the direction switching valve DV4 of the boom control valve V4 moves the spool from the neutral position 50, the first switching position 51 that is switched by moving the spool from the neutral position 50 in one direction, and the spool from the neutral position 50 in the other direction.
- the second switching position 52 can be switched.
- the first switching position 51 of the direction switching valve DV4 is a boom raising position for extending the boom cylinder C3 to raise the boom 13
- the second switching position 52 is for reducing the boom cylinder C3.
- the boom is lowered to lower the boom 13.
- the direction switching valve DV4 of the boom control valve V4 includes a pump port 53 to which the hydraulic oil supply path 23 is connected, and a hydraulic oil feed passage 54 for flowing hydraulic oil from the first pump P1 to the pressure compensation valve CV4.
- a hydraulic oil feed passage 54 for flowing hydraulic oil from the first pump P1 to the pressure compensation valve CV4.
- the first actuator port 60 connected to the bottom side oil chamber of the boom cylinder C3 via the first actuator oil passage 59, and connected to the head side oil chamber of the boom cylinder C3 via the second actuator oil passage 61.
- a second actuator port 62 is provided to the bottom side oil chamber of the boom cylinder C3 via the first actuator oil passage 59, and connected to the head side oil chamber of the boom cylinder C3 via the second actuator oil passage 61.
- the pressure compensation valve CV4 is composed of a direct acting spool type switching valve, and is slidable from the stroke start end position 63 (neutral position) to the full stroke position 64 by moving the spool in one direction.
- the spring 65 is urged in a direction to be switched to the stroke start end position 63.
- the pressure compensation valve CV4 includes a hydraulic oil inlet port 66 that is connected to the hydraulic oil feed passage 54 and communicates with the output port 55 of the direction switching valve DV4, and a hydraulic oil outlet port that communicates with the hydraulic oil inlet port 66. 67, a load pressure introduction port 68 for introducing the load of the boom cylinder C3, and a load pressure outlet port 69 communicating with the load pressure introduction port 68.
- a hydraulic oil flow passage 70 formed in the spool of the pressure compensation valve CV4 and communicating the hydraulic oil inlet port 66 and the hydraulic oil outlet port 67 is throttled at the stroke start end position 63, and from the stroke start end position 63. As the spool moves to the full stroke position 64, the flow path opening area is increased.
- the hydraulic oil outlet port 67 communicates with the first input port 56 and the second input port 57 of the direction switching valve DV4 via the communication passage 71.
- the communication path 71 has a first flow path 71a having one end connected to the hydraulic oil outlet port 67, and a second flow path 71b and a third flow path 71c having one end connected to the other end of the first flow path 71a. It consists of and.
- the other end side of the second flow path 71 b is connected to the first input port 56, and the other end side of the third flow path 71 c is connected to the second input port 57.
- a check valve V16 that prevents backflow of pressure oil from the first and second input ports 56 and 57 to the hydraulic oil outlet port 67 is interposed in each of the first flow path 71a and the second flow path 71b.
- One end side of the first spool hydraulic oil passage 72 is connected to the hydraulic oil feed oil passage 54 (hydraulic oil inlet port 66), and the other end side of the first spool hydraulic oil passage 72 is the return of the spool of the pressure compensation valve CV4. It is connected to the pressure receiving part 73 on the side opposite to the side where the spring 65 is provided.
- a load pressure introduction path 74 is connected to the load pressure introduction port 68, and the other end side of the load pressure introduction path 74 is connected to the first flow path 71 a of the communication path 71.
- the load pressure transmission port 49 is connected to the load pressure outlet port 69 to transmit the load pressure of the boom cylinder C3 to the load pressure detection line 48 (the load pressure of the boom cylinder C3 is output to the PLS transmission line 44). ).
- one end side of the second spool operating oil passage 75 is connected to the load pressure transmission oil passage 49, and a return spring 65 of the spool of the pressure compensation valve CV4 is provided on the other end side of the second spool operating oil passage 75. It is connected to the pressure receiving part 76 on the same side as the other side.
- the pressure oil flow path formed in the spool of the pressure compensation valve CV4 and connecting the load pressure introduction port 68 and the load pressure outlet port 69 is connected to the load pressure introduction port 68 and the load pressure outlet port 69 at the stroke start end position 63.
- a second load pressure flow passage 78 that communicates the load pressure introduction port 68 and the load pressure outlet port 69 at the full stroke position 64.
- a check valve V17 for preventing the backflow of pressure oil from the load pressure outlet port 69 to the load pressure introduction port 68 is interposed, and the check valve V17 of the second load pressure flow passage 78 is interposed.
- a throttle 79 is interposed upstream of the first load pressure flow passage 77, and no throttle is provided. Further, the spool of the pressure compensation valve CV4 is switched from the first load pressure flow passage 77 to the second load pressure flow passage 78 in the middle of moving from the stroke start end position 63 to the full stroke position 64.
- the load pressure introduction port 68 and the load pressure outlet port 69 are communicated with each other via the first load pressure flow passage 77.
- the load pressure introduction port 68 and the load pressure outlet port 69 are communicated with each other through the second load pressure flow passage 78.
- the pressure compensation valve CV4 is provided with a second load pressure flow passage 78 in which a throttle is interposed, and the first load pressure flow passage 77 is moved while the spool of the pressure compensation valve CV4 moves from the stroke start position 63 to the full stroke position 64.
- the second load pressure flow passage 78 is switched to “the second load pressure flow passage 78” is the difference in configuration between the boom control valve V4, the swing control valve V1, the bucket control valve V2, and the arm control valve V3. That is, only the first load pressure flow passage 77 is provided in the pressure compensation valves CV1 to CV3 of the swing control valve V1, the bucket control valve V2 and the arm control valve V3, and the first load pressure is extended from the stroke start end to the full stroke.
- a flow passage 77 communicates the load pressure introduction port 68 and the load pressure outlet port 69.
- the boom control valve V4, the swing control valve V1, the bucket control valve V2, and the arm control valve V3 have the same configuration.
- the pump port 53 and the output port 55 are connected to each other through the first connection oil passage 81 in which the throttle 80 is interposed.
- the first input port 56 is connected to the first actuator port 60 and the second actuator port 62 is connected to the drain port 58.
- the pressure oil from the first pump P1 is supplied from the hydraulic oil feed oil passage 54 ⁇ the hydraulic oil flow passage 70 ⁇ the first flow passage 71a of the communication passage 71 ⁇ the second flow passage 71b of the communication passage 71 ⁇ the first actuator oil passage.
- the oil is supplied to the bottom side oil chambers of the cylinders C2 to C5, and the oil in the head side oil chambers of the cylinders C2 to C5 is discharged and flows to the drain line 24.
- a scraping operation is performed, in the case of the bucket 15, a scooping operation is performed, and in the case of the swing bracket 12, the swinging operation is performed in one side.
- the oil is supplied to the head side oil chambers of the cylinders C2 to C5, and the oil in the bottom side oil chambers of the cylinders C2 to C5 is discharged and flows to the drain line 24.
- Arm dump operation, bucket 15 performs bucket dump operation, and swing bracket 12 swings left and right.
- the first flow path switching valve V11 When the first flow path switching valve V11 is at the merging position 19, the direction control valves DV1 to DV4 of the swing control valve V1, the bucket control valve V2, the arm control valve V3, and the boom control valve V4 are at the neutral position 50.
- the discharge pressure of the first pump P1 increases and the difference between the PPS signal pressure and the PLS signal pressure (which is zero at this time) becomes greater than the control differential pressure, the first pump P1 decreases the discharge amount.
- the unload valve V9 While the flow rate is controlled, the unload valve V9 is opened, and the discharge oil from the first pump P1 (hydraulic oil in the front work system supply line 18) is dropped into the tank T. Therefore, in this state, the discharge pressure of the first pump P1 becomes a pressure set by the unload valve V9, and the discharge flow rate of the first pump P1 becomes the minimum discharge amount.
- the first flow path switching valve V11 When the first flow path switching valve V11 is at the merging position 19, when the boom control valve V4 is operated alone, the following functions.
- the spool of the direction switching valve DV4 of the boom control valve V4 When the spool of the direction switching valve DV4 of the boom control valve V4 is moved in the direction of switching from the neutral position 50 to the first switching position 51 or the second switching position 52, the pressure oil from the first pump P1 flows into the boom cylinder C3.
- the load pressure acting on the boom cylinder C3 is transmitted to the load pressure detection line 48 via the load pressure introduction passage 74 ⁇ the first load pressure flow passage 77 ⁇ the load pressure transmission oil passage 49, and the load pressure acting on the boom cylinder C3 is transmitted.
- a PLS signal pressure is generated, and the PLS signal pressure is transmitted to the flow rate control unit FCU via the PLS transmission line 44.
- the PLS signal pressure (load pressure acting on the boom cylinder C3) is applied to the pressure receiving portion 76 on the same side as the side where the spool return spring 65 of the pressure compensation valve CV4 is provided via the second spool hydraulic oil passage 75.
- the discharge pressure of the first pump P1 is automatically controlled so that the “PPS signal pressure ⁇ PLS signal pressure” becomes the control differential pressure, and the unload flow rate through the unload valve V9 becomes zero.
- the discharge flow rate of one pump P1 begins to increase, and the entire amount of discharge oil from the first pump P1 flows to the boom cylinder C3 in accordance with the operation amount of the boom control valve V4.
- the boom control valve V4 is activated, the load pressure introduction port 68 and the load pressure outlet port 69 of the pressure compensation valve CV4 are communicated with each other by the first load pressure flow passage 77 without restriction, and the discharge pressure of the first pump P1 is increased.
- the spool In the process of increasing the pressure, the spool is moved in the direction of switching to the full stroke position 64 by the pressure standing in the first spool operating oil passage 72.
- the first load pressure flow passage 77 is switched to the second load pressure flow passage 78, and the load pressure introduction port is provided by the second load pressure flow passage 78 having the throttle 79.
- 68 communicates with the load pressure outlet port 69.
- the pressure in the first spool hydraulic oil passage 72 is larger than the sum of the PLS signal pressure and the return spring 65, and the spool of the pressure compensation valve CV4 is full stroke.
- the pressure compensation valve CV4 is maintained at the full stroke position 64 during the operation of the boom control valve V4.
- the load pressure of the boom cylinder C3 is transmitted to the PLS transmission line 44, so that the transmission response of the PLS signal pressure is slowed by the throttle 79 of the second load pressure flow passage 78 (the transmission response of the PLS signal pressure). Therefore, the stability of the body of the backhoe 1 (work machine) can be improved by suppressing the followability of the control pressure to the first pump P1.
- the boom 13 (boom control valve V4) is activated, the load pressure of the boom cylinder C3 is transmitted to the PLS transmission line 44 via the first load pressure flow passage 77 without a throttle (the throttle effect described above is achieved). Therefore, the control response of the first pump P1 is high, the control pressure follows instantaneously, and the quick response is exhibited.
- the responsiveness at the time of starting the boom control valve V4 is improved and the response at the time of starting the boom 13 is improved while sufficiently ensuring the body stability during the operation of the boom control valve V4 after starting. It is possible to satisfy both of ensuring safety and ensuring the stability of the airframe during operation of the boom 13 after startup.
- the boom control valve V4 and one or more of the swing control valve V1, the bucket control valve V2, and the arm control valve V3 are operated in combination. Will function as follows.
- the highest load pressure among the load pressures acting on the hydraulic cylinders C2 to C5 controlled by the operated control valves V1 to V4 becomes the PLS signal pressure
- the PLS signal pressure becomes the second spool hydraulic fluid passage 75.
- the pressure compensation valves CV1 to CV4 act on the pressure receiving portion 76 on the same side as the side where the return spring 65 of the spool is provided, so that “PPS signal pressure ⁇ PLS signal pressure” becomes the control differential pressure.
- the discharge pressure of the first pump P1 is automatically controlled, and the total amount of discharge oil of the first pump P1 flows to the operated hydraulic cylinders C2 to C5 according to the operated amount of the operated control valves V1 to V4.
- the pressure compensation valves CV1 to CV4 make the differential pressure across the spools of the directional control valves DV1 to DV4 of the operated control valves V1 to 4 (differential pressure between the upstream pressure and the downstream pressure of the spool) constant. Regardless of the magnitude of the load acting on the operated hydraulic cylinders C2 to 5, the discharge flow rate of the first pump P1 is an amount corresponding to the operation amount for each of the operated hydraulic cylinders C2 to C5. Divided.
- the maximum discharge amount of the first pump P1 is proportionally distributed to the operated hydraulic cylinders C2 to C5. Is done.
- the load on the boom cylinder C3 is the largest, the load pressure acting on the boom cylinder C3 becomes the PLS signal pressure, and the discharge pressure of the first pump P1 is controlled. The effect of.
- the boom 13 and the arm 14 are operated and the load of the boom cylinder C3 is larger than that of the arm cylinder C4, the following effects are obtained.
- the boom 13 and the arm 14 are driven to perform horizontal pulling (operation for pulling the arm 14 until the arm 14 becomes vertical while raising the boom 13 so that the tip of the bucket 15 moves along the ground) 13 and the arm 14 are likely to fall by their own weight when the arm 13 and the arm 14 are activated, but the boom control valve V4 has good responsiveness at the time of activation, so that the boom 13 can be caused to rise due to the fall of the arm 14 due to its own weight.
- the controllability of the 15 toes is good (the arm 14 can be prevented from dropping due to its own weight and the control of the toes of the bucket 15 being unstable).
- the airframe is stable, so that it is difficult for undulation of the ground due to the bucket 15 toe to move up and down.
- FIG. 6 shows another embodiment.
- the first load pressure flow passage 77 is also provided with a throttle, and the throttle opening of the throttle of the first load pressure flow passage 77 is set to the throttle of the second load pressure flow passage 78. It is larger than the channel opening area.
- the throttle opening of the throttle of the first load pressure flow passage 77 is set to the throttle of the second load pressure flow passage 78. It is larger than the channel opening area.
- it is comprised similarly to the said embodiment.
- the pressure compensation valve CV4 of the boom control valve V4 is provided with the first load pressure flow passage 77 and the second load pressure flow passage 78, and the load pressure introduction port 68 and the load are loaded when the boom control valve V4 is activated.
- the pressure outlet port 69 is communicated with the first load pressure flow passage 77, and the load pressure introduction port 68 and the load pressure outlet port 69 are connected with the second load pressure flow passage 78 during the operation after the boom control valve V4 is activated.
- this may be adopted for other control valves (for example, arm control valve V3).
- the present invention is applied to a pressure compensation valve for a control valve that controls a hydraulic cylinder.
- the present invention is applied to a pressure compensation valve for a control valve that controls another hydraulic actuator (hydraulic drive type actuator). Also good.
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Abstract
Description
このバックホーにあっては、複数の油圧アクチュエータと、これら油圧アクチュエータに圧油を供給する可変容量型の油圧ポンプからなるメインポンプとが装備されている。
ロードセンシングシステムは、各油圧アクチュエータに対応して設けられていて前記メインポンプから吐出される圧油の供給方向を制御して該油圧アクチュエータに供給する方向切換弁と、各方向切換弁に対応して設けられていて該方向切換弁の前後差圧を一定に保つように機能する圧力補償弁とを備えている。
前記ロードセンシングシステムは、複数の油圧アクチュエータが操作された場合において、操作された油圧アクチュエータに作用する負荷の大きさの違いにかかわらず、操作された各油圧シリンダに対して操作量に応じた量だけ圧油が供給されるようにメインポンプの吐出流量を分流する。
そこで、本発明は、前記問題点に鑑み、油圧アクチュエータの起動時には、すばやい応答性を発揮し、該油圧アクチュエータを起動した後の作動中には機体安定性を高めることのできる作業機を提供することを課題とする。
請求項1に係る発明では、複数の油圧アクチュエータと、これら油圧アクチュエータに圧油を供給する可変容量型の油圧ポンプとを備え、油圧ポンプの吐出圧から油圧アクチュエータのうちの最高負荷圧を引いた差圧を一定圧にするように油圧ポンプの吐出圧を制御するロードセンシングシステムを備えた作業機において、
油圧アクチュエータの起動時に、該油圧アクチュエータの負荷圧を導入して油圧アクチュエータのうちの最高負荷圧を伝達するPLS伝達ラインへと出力する第1負荷圧流通路と、
該油圧アクチュエータの起動後の作動中に、該油圧アクチュエータの負荷圧を導入して前記PLS伝達ラインへと出力する流路であって且つ圧油の流通量を前記第1負荷圧流通路よりも低減させた第2負荷圧流通路とを設けたことを特徴とする。
圧力補償弁に前記第1負荷圧流通路と前記第2負荷圧流通路とを設け、該圧力補償弁のストローク始端からストローク途中までにおいて第1負荷圧流通路が機能し、該圧力補償弁のフルストローク時に第2負荷圧流通路が機能することを特徴とする。
請求項4に係る発明では、前記第1負荷圧流通路及び第2負荷圧流通路の両方に絞りを設け、第1負荷圧流通路の絞りの流路開口面積に対して第2負荷圧流通路の絞りの流路開口面積を小さくすることにより、第2負荷圧流通路の圧油の流通量を第1負荷圧流通路よりも低減させていることを特徴とする。
前記負荷圧入口ポートと負荷圧出口ポートとが、圧力補償弁のストローク始端からストローク途中までにおいて第1負荷圧流通路で連通し、ストローク途中から切り換わって第2負荷圧流通路で連通することを特徴とする。
請求項1に係る発明によれば、油圧アクチュエータの起動時には、該油圧アクチュエータの負荷圧が、第2負荷圧流通路よりも圧油流通量の多い第1負荷圧流通路を介してPLS伝達ラインに伝達されるので、油圧ポンプの制御応答性が高く、瞬時に制御圧が追従し、すばやい応答性を発揮する。
請求項3に係る発明によれば、油圧アクチュエータの起動時は絞りのない流路によって油圧アクチュエータの負荷圧を伝達し、油圧アクチュエータの起動後の作動中は絞りのある流路によって油圧アクチュエータの負荷圧を伝達するようにすることにより、油圧アクチュエータの起動時には、すばやい応答性を発揮し、油圧アクチュエータを起動した後の作動中には、機体安定性を高めることができる作業機を容易に実施することができる。
図5において、符号1は、作業機として例示するバックホーである。
このバックホー1は、下部の走行体2と、この走行体2上に上下方向の旋回軸心回りに旋回自在に搭載された上部の旋回体3とから主構成されている。
走行体2はトラックフレーム4の左右両側に、油圧モータからなる走行モータML,MRによってクローラベルト5を周方向に循環回走するように構成されたクローラ式走行装置6をそれぞれ備えている。
前記旋回体3は、トラックフレーム4上に旋回軸心回りに回動自在に搭載されていて機体を構成する旋回台8と、この旋回台8の前部に装備されたフロント作業装置9(掘削作業装置)と、旋回台8上に搭載されたキャビン10とを備えている。
また、旋回台8の前部には、該旋回台8から前方突出状に設けられた支持ブラケット11に上下方向の軸心回りに左右に揺動自在に支持されたスイングブラケット12が設けられ、このスイングブラケット12は油圧シリンダからなるスイングシリンダC2の伸縮によって左右に揺動操作可能とされている。
アーム14は、該アーム14とブーム13との間に介装されたアームシリンダC4を伸長させることにより後方側に揺動してクラウド動作(掻込動作)し、該アームシリンダC4を収縮させることにより前方側に揺動してダンプ動作する。
前記ブームシリンダC3、アームシリンダC4及びバケットシリンダC5はそれぞれ油圧シリンダによって構成されている。
油圧システムは、図2に示すように、圧油供給ユニットPSUと、コントロールバルブCVUと、流量制御部FCUとを有する。
前記圧油供給ユニットPSUは、エンジンEによって駆動される油圧ポンプからなる第1~3ポンプP1,P2,P3と、該第1~3ポンプP1,P2,P3から吐出された圧油を出力する第1~4吐出ポートPa,Pb,Pc,Pdとを備えている。
第1ポンプP1から吐出された圧油は、走行モータML,MRと、フロント作業装置9の油圧シリンダC3,C4,C5と、スイングシリンダC2とに使用され、第2ポンプP2から吐出された圧油は、主として旋回モータMTとドーザシリンダC1とに使用されると共にブームシリンダC3,アームシリンダC4,バケットシリンダC5及びスイングシリンダC2にも使用され、第3ポンプP3から吐出された圧油は、パイロット圧や検出信号等の信号圧供給用に使用される。
前記コントロールバルブCVUは、各種油圧アクチュエータML,MR,MTC1~C5を制御する制御弁V1~8、第1~3中間ブロックB1~3及び第1,2端部ブロックB4,B5を一方向に配置して集約してなる。
図2において、V1はスイングシリンダC2を制御するスイング制御弁、V2はバケットシリンダC5を制御するバケット制御弁、V3はアームシリンダC4を制御するアーム制御弁、V4はブームシリンダC3を制御するブーム制御弁、V5は右側の走行モータMRを制御する右側走行制御弁、V6は左側の走行モータMLを制御する左側走行制御弁、V7はドーザシリンダC1を制御するドーザ制御弁、V8は旋回モータMTを制御する旋回制御弁である。
図2において、各制御弁V1~8は、バルブボディVB内に、圧油の方向を切り換える方向切換弁DV1~8が組み込まれてなり、さらに、スイング制御弁V1、バケット制御弁V2、アーム制御弁V3及びブーム制御弁V4にあっては、ブームシリンダC3、アームシリンダC4、バケットシリンダC5、スイングシリンダC2のうちの複数を使用したときに、これらシリンダC2~5間の負荷の調整として機能する圧力補償弁(コンペンセータバルブ)CV1~4がバルブボディVB内に組み込まれている。
第1端部ブロックB4はスイング制御弁V1に接続され、第2端部ブロックB5は旋回制御弁V8に接続されている。
第1流路切換弁V11は、ブーム制御弁4,アーム制御弁V3,バケット制御弁V2,スイング制御弁V1に圧油を供給するフロント作業系供給ライン18に第1吐出路16と第2吐出路17とを接続させる合流位置19と、左側走行制御弁V6に圧油を供給する走行左供給路20に第1吐出路16を接続させ且つ右側走行制御弁V5に圧油を供給する走行右供給路21に第2吐出路17を接続させる独立供給位置22とに切換自在とされ、バネによって合流位置19に切り換えられ、パイロット圧によって独立供給位置22に切り換えられる。
また、このフロント作業系供給ライン18はスイング制御弁V1、バケット制御弁V2、アーム制御弁V3、ブーム制御弁V4の各方向切換弁DV1~4にそれぞれ作動油供給路23を介して接続されている。
このドレンライン24には、フロント作業系供給ライン18が、接続油路25及びアンロード弁V9を介して接続されていると共に、各制御弁V1~8の方向切換弁DV1~8がドレン油路26を介して接続されている。
また、第3吐出路27の第2流路切換弁V14の上流側で且つドーザ制御弁V7の下流側には接続通路29の一端が接続され、この接続通路29の他端は前記フロント作業系供給ライン18に接続されている。また、この接続通路29にはフロント作業系供給ライン18側からの圧油の逆流を阻止するチェック弁V15が介装されている。
弁操作検知ライン32は、第2端部ブロックに設けた第1信号圧導入部35→旋回制御弁V8の方向切換弁DV8→ドーザ制御弁V7の方向切換弁DV7→左側走行制御弁V6の方向切換弁DV6→右側走行制御弁V5の方向切換弁DV5→ブーム制御弁V4の方向切換弁DV4→アーム制御弁V3の方向切換弁DV3→バケット制御弁V2の方向切換弁DV2→スイング制御弁V1の方向切換弁DV1を経てドレンライン24に接続されている。
このAIスイッチ36によって圧が検出されないとエンジンEの回転数がアイドリング回転まで自動的に落とされ、AIスイッチ36によって圧が検出されるとエンジンEの回転数が所定の回転数まで自動的に上がるようにエンジンEの回転数が自動制御される。
また、第1流路切換油路38には走行検出ライン39の一端側が接続され、この走行検出ライン39の他端側は左側走行制御弁の方向切換弁DV6→右側走行制御弁の方向切換弁DV5を経てドレンライン24に接続されている。
この接続点41と第3信号圧導入部40との間に第2流路切換油路42の一端側が接続され、この第2流路切換油路42の他端側は第2流路切換弁V14のパイロット受圧部に接続されている。
これによって、第1吐出ポートPaからの吐出油は左側走行制御弁V6に供給され且つ第2吐出ポートPbからの吐出油は右側走行制御弁V5に供給され、第1、2吐出ポートPa,Pbからの吐出油はスイング用、バケット用、アーム用、ブーム用の制御弁V1~4には供給されない。
本実施形態では、このロードセンシングシステムは、第1流路切換弁V11が合流位置19とされた状態において、ブームシリンダC3、アームシリンダC4、バケットシリンダC5、スイングシリンダC2の負荷圧に対して第1ポンプP1の吐出圧(吐出量)を制御するよう機能し、スイング制御弁V1、バケット制御弁V2、アーム制御弁V3、ブーム制御弁4の各方向切換弁DV1~4のスプールの後に圧力補償弁CV1~4がそれぞれ接続されたアフターオリフィス型のロードセンシングシステムとされている。
図3に示すように、PPS伝達ライン43は、第1流路切換弁V11に接続されていて、第1流路切換弁V11が合流位置19に切り換えられている状態で、接続油路46を介してフロント作業系供給ライン18に接続されて、PPS信号圧を流量制御部FCUに伝達する。
図2に示すように、PLS伝達ライン44は、コントロールバルブCVUに設けられた負荷圧検出ライン48に接続されている。負荷圧検出ライン48は、第1中間ブロックB1からブーム制御弁4のバルブボディVB、アーム制御弁V3のバルブボディVB、バケット制御弁V2のバルブボディVB、スイング制御弁V1のバルブボディVBにわたって設けられていて、一端側がアンロード弁V9のスプールを閉じ方向に付勢するバネ側のパイロット受圧部に接続されると共に他端側が閉塞されている。
このロードセンシングシステムでは、スイングシリンダC2、ブームシリンダC3、アームシリンダC4、バケットシリンダC5に作用する負荷が各負荷圧伝達油路49を介して負荷圧検出ライン48に伝達され、このスイングシリンダC2、ブームシリンダC3、アームシリンダC4、バケットシリンダC5に作用する負荷のうちの最高負荷圧がPLS信号圧として負荷圧検出ライン48からPLS伝達ライン44を介して流量制御部FCUに伝達される。
なお、アーム制御弁V3、バケット制御弁V2、スイング制御弁V1は、一部を除いてブーム制御弁4と同様に構成されているので、アーム制御弁V3、バケット制御弁V2、スイング制御弁V1については、ブーム制御弁4と同様の部分に同様の符号を付して説明を省略する。
ブーム制御弁V4にあっては、方向切換弁DV4の第1切換位置51がブームシリンダC3を伸長させてブーム13を上昇させるブーム上げ位置とされ、第2切換位置52がブームシリンダC3を縮小させてブーム13を下降させるブーム下げ位置とされている。
この圧力補償弁CV4は、前記作動油送り流路54が接続されていて方向切換弁DV4の出力ポート55に連通する作動油入口ポート66と、この作動油入口ポート66に連通する作動油出口ポート67と、ブームシリンダC3の負荷を導入する負荷圧導入ポート68と、この負荷圧導入ポート68に連通する負荷圧出口ポート69とを有する。
前記作動油出口ポート67は、連通路71を介して方向切換弁DV4の第1入力ポート56及び第2入力ポート57に連通している。前記連通路71は、一端側が作動油出口ポート67に接続した第1流路71aと、この第1流路71aの他端側に一端側が接続された第2流路71b及び第3流路71cとから構成されている。第2流路71bの他端側は第1入力ポート56に接続され、第3流路71cの他端側は第2入力ポート57に接続されている。
作動油送り油路54(作動油入口ポート66)には第1スプール作動油路72の一端側が接続され、この第1スプール作動油路72の他端側は、圧力補償弁CV4のスプールの戻しバネ65が設けられた側とは反対側の受圧部73に接続されている。
負荷圧出口ポート69には前記負荷圧伝達油路49が接続されていてブームシリンダC3の負荷圧を負荷圧検出ライン48に伝達する(ブームシリンダC3の負荷圧をPLS伝達ライン44へと出力する)。
圧力補償弁CV4のスプールに形成されていて、負荷圧導入ポート68と負荷圧出口ポート69とを連通させる圧油の流路は、ストローク始端位置63で負荷圧導入ポート68と負荷圧出口ポート69とを連通させる第1負荷圧流通路77と、フルストローク位置64で負荷圧導入ポート68と負荷圧出口ポート69とを連通させる第2負荷圧流通路78とで構成されている。
また、前記第1負荷圧流通路77から第2負荷圧流通路78へは、圧力補償弁CV4のスプールがストローク始端位置63からフルストローク位置64に移動する途中で切り換わる。本実施形態では、例えば、スプールの最大ストロークが8mmとされ、スプールのストロークが0~6mmの時に第1負荷圧流通路77で負荷圧導入ポート68と負荷圧出口ポート69とが連通され、スプールのストロークが6~8mmの時に第2負荷圧流通路78で負荷圧導入ポート68と負荷圧出口ポート69とが連通されるよう構成される。
すると、第1ポンプP1からの圧油は、作動油送り油路54→作動油流通路70→連通路71の第1流路71a→連通路71の第2流路71b→第1アクチュエータ油路59を経てシリンダC2~5のボトム側油室に供給されると共に、シリンダC2~5のヘッド側油室の油が排出されてドレンライン24へと流れ、ブーム13の場合は上げ動作し、アーム14の場合は掻込動作し、バケット15の場合は掬い動作し、スイングブラケット12の場合は左右一方に揺動動作する。
第1ポンプP1からの圧油は、作動油送り油路54→作動油流通路70→連通路71の第1流路71a→連通路71の第3流路71c→第2アクチュエータ油路61を経てシリンダC2~5のヘッド側油室に供給されると共に、シリンダC2~5のボトム側油室の油が排出されてドレンライン24へと流れ、ブーム13の場合は下げ動作し、アーム14の場合はアームダンプ動作し、バケット15の場合はバケットダンプ動作し、スイングブラケット12の場合は左右他方に揺動動作する。
第1流路切換弁V11が合流位置19である場合において、スイング制御弁V1、バケット制御弁V2、アーム制御弁V3及びブーム制御弁V4の方向切換弁DV1~4が中立位置50であると、第1ポンプP1の吐出圧が上昇し、PPS信号圧とPLS信号圧(この時は零である)との差が制御差圧よりも大きくなると、第1ポンプP1が吐出量を減少させる方向に流量制御されると共にアンロード弁V9が開いて第1ポンプP1からの吐出油(フロント作業系供給ライン18の作動油)をタンクTに落とす。したがって、この状態では、第1ポンプP1の吐出圧はアンロード弁V9で設定される圧となり、第1ポンプP1の吐出流量は最小吐出量となる。
ブーム制御弁V4の方向切換弁DV4のスプールを中立位置50から第1切換位置51又は第2切換位置52に切り換える方向に移動すると、ブームシリンダC3に第1ポンプP1からの圧油が流れ、該ブームシリンダC3に作用する負荷圧が、負荷圧導入路74→第1負荷圧流通路77→負荷圧伝達油路49を経て負荷圧検出ライン48に伝達され、ブームシリンダC3に作用する負荷圧がPLS信号圧となり、該PLS信号圧がPLS伝達ライン44を介して流量制御部FCUに伝達される。また、PLS信号圧(ブームシリンダC3に作用する負荷圧)が第2スプール作動油路75を介して、圧力補償弁CV4のスプールの戻しバネ65が設けられた側と同じ側の受圧部76に作用する。
ブーム制御弁V4の起動時は、圧力補償弁CV4の負荷圧導入ポート68と負荷圧出口ポート69とは、絞りのない第1負荷圧流通路77によって連通され、第1ポンプP1の吐出圧が昇圧される過程において第1スプール作動油路72に立つ圧によってスプールがフルストローク位置64に切り換わる方向に動かされる。そして、ブーム制御弁V4を起動した後の作動時は、第1負荷圧流通路77から第2負荷圧流通路78に切り換わり、絞り79の有る第2負荷圧流通路78によって負荷圧導入ポート68と負荷圧出口ポート69とが連通される。
このブーム制御弁V4の単独操作時にあっては、ブーム13(ブーム制御弁V4)を起動した後のブーム13(ブーム制御弁V4)の作動中には、絞り79のある第2負荷圧流通路78を介してブームシリンダC3の負荷圧がPLS伝達ライン44に伝達されるので、この第2負荷圧流通路78の絞り79によってPLS信号圧の伝達応答性が緩慢となり(PLS信号圧の伝達応答性が必要以上に敏感になるのが抑えられ)、第1ポンプP1に対する制御圧の追従性を抑えることによりバックホー1(作業機)の機体安定性を高めることができる。
すなわち、本願発明にあっては、起動後のブーム制御弁V4の作動中の機体安定性を十分に確保しつつ、ブーム制御弁V4の起動時の応答性が向上し、ブーム13起動時の応答性確保と、起動後のブーム13作動中の機体安定性確保とを両立することができる。
この場合、操作された制御弁V1~4で制御される油圧シリンダC2~5に作用する負荷圧のうちの最高負荷圧がPLS信号圧となると共に該PLS信号圧が第2スプール作動油路75を介して、圧力補償弁CV1~4のスプールの戻しバネ65が設けられた側と同じ側の受け圧部76に作用し、「PPS信号圧-PLS信号圧」が制御差圧となるように第1ポンプP1の吐出圧が自動制御され、操作された制御弁V1~4の操作量に応じて第1ポンプP1の吐出油の全量が操作された油圧シリンダC2~5に流れる。
この場合において、ブームシリンダC3の負荷が一番大きい場合は、ブームシリンダC3に作用する負荷圧がPLS信号圧となり、第1ポンプP1吐出圧が制御され、前述したブーム13単独操作の場合と同様の効果を奏する。
ブーム13とアーム14とを駆動して水平引き(バケット15の爪先が地面に沿って移動するようにブーム13を上げながらアーム14が垂直になるまで該アーム14を引く作業)を行う場合、ブーム13及びアーム14の起動時には、アーム14が自重で落ちやすいが、該起動時にはブーム制御弁V4の応答性がよいので、アーム14の自重による落ち込みにブーム13の上昇を対応させることができ、バケット15爪先の制御性がよい(アーム14が自重で落ち込んでバケット15の爪先の制御が安定しないということを防止することができる)。また、起動後の水平引き作動中は、機体が安定するので、バケット15爪先が上下することによる地面の波打ちなどが発生しにくい。
この実施形態にあっては、第1負荷圧流通路77にも絞りが設けられていると共に、この第1負荷圧流通路77の絞りの流路開口面積を第2負荷圧流通路78の絞りの流路開口面積よりも大きくしている。その他の構成については、前記実施形態と同様に構成される。
本実施形態では、ブーム制御弁V4の圧力補償弁CV4に、第1負荷圧流通路77と、第2負荷圧流通路78とを設け、ブーム制御弁V4の起動時に負荷圧導入ポート68と負荷圧出口ポート69とを第1負荷圧流通路77で連通し、ブーム制御弁V4を起動した後の作動中に負荷圧導入ポート68と負荷圧出口ポート69とを第2負荷圧流通路78で連通するようにしたが、これを他の制御弁(例えば、アーム制御弁V3)にも採用してもよい。
68 負荷圧導入ポート
69 負荷圧出口ポート
77 第1負荷圧流通路
78 第2負荷圧流通路
79 絞り
84 絞り
85 絞り
C2 油圧アクチュエータ(スイングシリンダ)
C3 油圧アクチュエータ(ブームシリンダ)
C4 油圧アクチュエータ(アームシリンダ)
C5 油圧アクチュエータ(バケットシリンダ)
DV1 方向切換弁
DV2 方向切換弁
DV3 方向切換弁
DV4 方向切換弁
CV1 圧力補償弁
CV2 圧力補償弁
CV3 圧力補償弁
CV4 圧力補償弁
P1 油圧ポンプ(第1ポンプ)
Claims (5)
- 複数の油圧アクチュエータ(C2~C5)と、これら油圧アクチュエータ(C2~C5)に圧油を供給する可変容量型の油圧ポンプ(P1)とを備え、油圧ポンプ(P1)の吐出圧から油圧アクチュエータ(C2~C5)のうちの最高負荷圧を引いた差圧を一定圧にするように油圧ポンプ(P1)の吐出圧を制御するロードセンシングシステムを備えた作業機において、
油圧アクチュエータ(C2~C5)の起動時に、該油圧アクチュエータ(C2~C5)の負荷圧を導入して油圧アクチュエータ(C2~C5)のうちの最高負荷圧を伝達するPLS伝達ライン(44)へと出力する第1負荷圧流通路(77)と、
該油圧アクチュエータ(C2~C5)の起動後の作動中に、該油圧アクチュエータ(C2~C5)の負荷圧を導入して前記PLS伝達ライン(44)へと出力する流路であって且つ圧油の流通量を前記第1負荷圧流通路(77)よりも低減させた第2負荷圧流通路(78)とを設けたことを特徴とする作業機。 - 前記油圧ポンプ(P1)から吐出される圧油の供給方向を制御して前記油圧アクチュエータ(C2~C5)に供給する方向切換弁(DV1~4)を各油圧アクチュエータ(C2~C5)に対応して設け、この方向切換弁(DV1~4)の前後差圧を一定に保つように機能する圧力補償弁(CV1~4)を各方向切換弁(DV1~4)に対応して設け、
圧力補償弁(CV4)に前記第1負荷圧流通路(77)と前記第2負荷圧流通路(78)とを設け、該圧力補償弁(CV4)のストローク始端からストローク途中までにおいて第1負荷圧流通路(77)が機能し、該圧力補償弁(CV4)のフルストローク時に第2負荷圧流通路(78)が機能することを特徴とする請求項1に記載の作業機。 - 前記第1負荷圧流通路(77)には絞りを設けないと共に第2負荷圧流通路(78)に絞り(79)を設けることにより、第2負荷圧流通路(78)の圧油の流通量を第1負荷圧流通路(77)よりも低減させていることを特徴とする請求項1又は2に記載の作業機。
- 前記第1負荷圧流通路(77)及び第2負荷圧流通路(78)の両方に絞り(84,85)を設け、第1負荷圧流通路(77)の絞り(84)の流路開口面積に対して第2負荷圧流通路(78)の絞り(85)の流路開口面積を小さくすることにより、第2負荷圧流通路(78)の圧油の流通量を第1負荷圧流通路(77)よりも低減させていることを特徴とする請求項1又は2に記載の作業機。
- 圧力補償弁(CV4)は、油圧アクチュエータ(C2~C5)の負荷圧を導入する負荷圧導入ポート(68)と、この負荷圧導入ポート(68)から導入された油圧アクチュエータ(C2~C5)の負荷圧をPLS伝達ライン(44)へと出力する負荷圧出口ポート(69)とを備え、
前記負荷圧導入ポート(68)と負荷圧出口ポート(69)とが、圧力補償弁(CV4)のストローク始端からストローク途中までにおいて第1負荷圧流通路(77)で連通し、且つストローク途中から切り換わって第2負荷圧流通路(78)で連通することを特徴とする請求項1~4のいずれか1項に記載の作業機。
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JP6656913B2 (ja) * | 2015-12-24 | 2020-03-04 | 株式会社クボタ | 作業機の油圧システム |
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JP7187399B2 (ja) * | 2019-07-26 | 2022-12-12 | 株式会社クボタ | 作業機の油圧システム及び作業機の油圧システムの制御方法 |
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