WO2015198868A1 - 建設機械の油圧駆動装置 - Google Patents
建設機械の油圧駆動装置 Download PDFInfo
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- WO2015198868A1 WO2015198868A1 PCT/JP2015/066779 JP2015066779W WO2015198868A1 WO 2015198868 A1 WO2015198868 A1 WO 2015198868A1 JP 2015066779 W JP2015066779 W JP 2015066779W WO 2015198868 A1 WO2015198868 A1 WO 2015198868A1
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- pressure
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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
- E02F9/2058—Electric or electro-mechanical or mechanical control devices of vehicle sub-units
- E02F9/2062—Control of propulsion units
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2221—Control of flow rate; Load sensing arrangements
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2221—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
- E02F9/2225—Control of flow rate; Load sensing arrangements using pressure-compensating valves
- E02F9/2228—Control of flow rate; Load sensing arrangements using pressure-compensating valves including an electronic controller
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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
- E02F9/2232—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2221—Control of flow rate; Load sensing arrangements
- E02F9/2232—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps
- E02F9/2235—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps including an electronic controller
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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
- E02F9/2264—Arrangements or adaptations of elements for hydraulic drives
- E02F9/2267—Valves or distributors
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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
- E02F9/2296—Systems with a variable displacement pump
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
- F15B11/028—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force
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- 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
- F15B11/05—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed specially adapted to maintain constant speed, e.g. pressure-compensated, load-responsive
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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
- F15B11/162—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for giving priority to particular servomotors or users
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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
- 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
- F15B11/165—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for adjusting the pump output or bypass in response to demand
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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
- F15B13/024—Pressure relief 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
- 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
- F15B13/06—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with two or more servomotors
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60Y—INDEXING SCHEME RELATING TO ASPECTS CROSS-CUTTING VEHICLE TECHNOLOGY
- B60Y2200/00—Type of vehicle
- B60Y2200/40—Special vehicles
- B60Y2200/41—Construction vehicles, e.g. graders, excavators
- B60Y2200/412—Excavators
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F3/00—Dredgers; Soil-shifting machines
- E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
- E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
- E02F3/30—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets with a dipper-arm pivoted on a cantilever beam, i.e. boom
- E02F3/32—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets with a dipper-arm pivoted on a cantilever beam, i.e. boom working downwardly and towards the machine, e.g. with backhoes
- E02F3/325—Backhoes of the miniature type
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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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- 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
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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
- F15B2211/205—Systems with pumps
- F15B2211/2053—Type of pump
- F15B2211/20546—Type of pump variable capacity
- F15B2211/20553—Type of pump variable capacity with pilot circuit, e.g. for controlling a swash plate
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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
- F15B2211/30535—In combination with a pressure compensating valve the pressure compensating valve is arranged between pressure source and 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
- F15B2211/40—Flow control
- F15B2211/405—Flow control characterised by the type of flow control means or valve
- F15B2211/40576—Assemblies of multiple valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/50—Pressure control
- F15B2211/505—Pressure control characterised by the type of pressure control means
- F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
- F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/50—Pressure control
- F15B2211/51—Pressure control characterised by the positions of the valve element
- F15B2211/513—Pressure control characterised by the positions of the valve element the positions being continuously variable, e.g. as realised by proportional valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/50—Pressure control
- F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
- F15B2211/5151—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a 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
- F15B2211/50—Pressure control
- F15B2211/55—Pressure control for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief 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
- F15B2211/605—Load sensing circuits
- F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
- F15B2211/6055—Load sensing circuits having valve means between output member and the load sensing circuit using pressure relief valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/70—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
Definitions
- the present invention relates to a hydraulic drive device for a construction machine such as a hydraulic excavator equipped with a variable displacement hydraulic pump, and in particular, maintains a differential pressure between a discharge pressure of a hydraulic pump and a maximum load pressure of a plurality of actuators at a target differential pressure.
- the present invention relates to a hydraulic drive device for a construction machine that performs load sensing control for controlling the capacity of a hydraulic pump.
- a hydraulic drive device that performs load sensing control for controlling the capacity of a hydraulic pump so as to maintain the differential pressure between the discharge pressure of the hydraulic pump and the maximum load pressure of a plurality of actuators at a target differential pressure is like a hydraulic excavator.
- load sensing control for controlling the capacity of a hydraulic pump so as to maintain the differential pressure between the discharge pressure of the hydraulic pump and the maximum load pressure of a plurality of actuators at a target differential pressure.
- a differential pressure reducing valve that outputs the differential pressure between the discharge pressure of the hydraulic pump and the maximum load pressure of a plurality of actuators as an absolute pressure is provided, and this absolute pressure is used as a feedback LS differential pressure.
- the absolute pressure which is guided to the LS control valve of the pump regulator and variable depending on the engine speed, is guided to the LS control valve as the target LS differential pressure to perform load sensing control and output from the differential pressure reducing valve.
- the absolute pressure (differential pressure between the discharge pressure of the hydraulic pump and the maximum load pressure) is introduced as a target compensation differential pressure to a plurality of pressure compensation valves to control the differential pressure before and after each flow control valve.
- the differential pressure between the discharge pressure of the hydraulic pump and the maximum load pressure is guided to a plurality of pressure compensation valves as a target compensation differential pressure, and two or more actuators are controlled by controlling the differential pressure before and after each flow control valve.
- the differential pressure between the hydraulic pump discharge pressure and the maximum load pressure depends on the degree of saturation.
- the target compensation differential pressure of the pressure compensation valve also becomes smaller and the differential pressure across the flow control valve becomes smaller. It can be distributed and good composite operability can be secured.
- the target LS is adjusted accordingly. Since the differential pressure is reduced, the flow rate of the pressure oil supplied from the hydraulic pump to the actuator is reduced, and fine operability can be improved.
- Patent Document 1 in order to prevent such an actuator from stopping, a signal pressure variable relief valve whose set pressure is variable according to the target LS differential pressure is arranged in the maximum load pressure line, and a specific actuator is When the stroke end is reached and the discharge pressure of the hydraulic pump rises to the set pressure of the main relief valve, the maximum pressure of the maximum load pressure is limited to a pressure lower than the set pressure of the relief valve by the signal pressure variable relief valve. Yes. As a result, even when a specific actuator reaches the stroke end, the differential pressure between the discharge pressure of the hydraulic pump and the maximum load pressure does not become zero, and the pressure compensation valve does not fully close, so the other actuator does not stop and is good Complex operability is maintained.
- a main relief valve is set only when an operation pilot pressure of a traveling operation device is guided to a main relief valve and an operation lever of the traveling operation device is operated.
- the main relief valve is configured as a variable relief valve so that the pressure increases from the first value to the second value.
- the discharge pressure of the hydraulic pump will rise to the second value of the set pressure of the main relief valve.
- the maximum pressure of the maximum load pressure is limited to a pressure lower than the first value of the set pressure of the main relief valve by the signal pressure variable relief valve, the load sensing is limited. Due to the control function, the discharge pressure of the hydraulic pump is limited by the signal pressure variable relief valve, the pressure obtained by adding the target differential pressure of load sensing control to the maximum load pressure smaller than the first value of the set pressure of the main relief valve Can only rise.
- the load pressure of the travel motor cannot be increased to the second value of the set pressure of the main relief valve, and the effect of securing the output torque of the travel motor due to the increase of the set pressure of the main relief valve cannot be obtained.
- An object of the present invention is to provide a hydraulic drive device for a construction machine that performs load sensing control for controlling the capacity of the hydraulic pump so as to maintain the differential pressure between the discharge pressure of the hydraulic pump and the maximum load pressure of a plurality of actuators at a target differential pressure.
- the other actuator does not stop even if the discharge pressure of the hydraulic pump rises to the set pressure of the main relief valve, such as when one of the actuators reaches the stroke end.
- the set pressure of the main relief valve is made variable and the set pressure of the main relief valve increases when a specific actuator is operated, the load pressure of the specified actuator can be reliably increased to the increased set pressure of the main relief valve. It is an object of the present invention to provide a hydraulic drive device that can be lifted up.
- the present invention provides a variable displacement hydraulic pump driven by a prime mover, a plurality of actuators driven by pressure oil discharged by the hydraulic pump, and a plurality of actuators from the hydraulic pump.
- a plurality of flow control valves for controlling the flow rate of the pressure oil supplied to the actuator, and the front and rear differential pressures of the plurality of flow control valves so that the front and rear differential pressures of the plurality of flow control valves are equal to the target compensation differential pressure, respectively.
- a plurality of pressure compensating valves to be controlled a pump control device that performs load sensing control of a capacity of the hydraulic pump such that a discharge pressure of the hydraulic pump is higher than a maximum load pressure of the plurality of actuators by a target differential pressure; and the hydraulic pressure
- the main relief valve that limits the maximum pump discharge pressure and the maximum load pressure of the actuators are detected, and the detected maximum load pressure is maximized.
- a maximum load pressure detection circuit that outputs to the load pressure line, and a maximum pressure of the maximum load pressure that is connected to the maximum load pressure line via a throttle and is led downstream of the throttle from the set pressure of the main relief valve
- a signal pressure relief valve that restricts the pressure to a lower pressure, and a differential pressure between the discharge pressure of the hydraulic pump and the maximum load pressure downstream of the throttle is led to the pump control device, and the pump control device
- the displacement of the hydraulic pump is controlled so that the differential pressure becomes equal to the target differential pressure of the load sensing control, and the differential pressure between the discharge pressure of the hydraulic pump and the maximum load pressure downstream of the throttle is the target compensation difference.
- the main relief valve is operated by operating a specific actuator among the plurality of actuators.
- the set pressure of the main relief valve is at the first value
- the specific actuator is operated, the set pressure of the main relief valve is from the first value to the first value.
- the signal pressure relief valve is configured such that when the specific actuator is not operated and the set pressure of the main relief valve is at the first value, the signal pressure relief valve is The set pressure of the signal pressure relief valve is at a third value smaller than the first value of the set pressure of the main relief valve, the specific actuator is operated, and the set pressure of the main relief valve is set to the second value.
- the set pressure of the signal pressure relief valve increases from the third value to a fourth value smaller than a second value of the set pressure of the main relief valve, and the main pressure
- the difference between the first value of the set pressure of the relief valve and the third value of the set pressure of the signal pressure relief valve, the second value of the set pressure of the main relief valve, and the set pressure of the signal pressure relief valve It is assumed that the difference from the fourth value is smaller than the target differential pressure of the load sensing control.
- the set pressure of the signal pressure relief valve is smaller than the first value of the set pressure of the main relief valve. Therefore, when the actuator other than the specific actuator reaches the stroke end and the discharge pressure of the hydraulic pump rises to the first value of the set pressure of the main relief valve, the maximum load pressure is the value of the main relief valve.
- the pressure is limited to a pressure smaller than the first value of the set pressure, the differential pressure between the discharge pressure of the hydraulic pump and the maximum load pressure does not become zero, and the pressure compensation valve does not fully close. (The other actuator) does not stop, and good composite operability is maintained.
- the set pressure of the main relief valve increases from the first value to the second value
- the set pressure of the signal pressure relief valve is set from the third value to set the main relief valve.
- the value of the difference between the second value of the set pressure of the main relief valve and the fourth value of the set pressure of the signal pressure relief valve increases to a fourth value that is smaller than the second value of the pressure. Since it is configured to be smaller than the target differential pressure of control, the discharge pressure of the hydraulic pump rises to the second value of the set pressure of the main relief valve by the action of load sensing control, and the load pressure of a specific actuator is reduced to the main relief It is possible to reliably increase the set pressure of the valve to the second value and ensure the necessary driving force.
- the other actuator reaches the stroke end, and the discharge pressure of the hydraulic pump rises to the second value of the set pressure of the main relief valve, the maximum Since the load pressure is limited to a pressure of the fourth value that is smaller than the second value of the set pressure of the main relief valve, the discharge pressure of the hydraulic pump and the maximum load are the same as when an actuator other than a specific actuator is operated. Since the pressure difference does not become zero and the pressure compensation valve does not fully close, the other actuator does not stop in this case as well, and a good combined operability can be obtained.
- the hydraulic drive device for a construction machine that performs load sensing control for controlling the capacity of the hydraulic pump so as to maintain the differential pressure between the discharge pressure of the hydraulic pump and the maximum load pressure of the plurality of actuators at the target differential pressure.
- the other actuator does not stop even if the discharge pressure of the hydraulic pump rises to the set pressure of the main relief valve, such as when one of the actuators reaches the stroke end. Good composite operability can be obtained.
- the load pressure of the specific actuator can be reliably increased to the increased set pressure of the main relief valve. The required driving force can be secured.
- FIG. 5 is a diagram showing the relationship between the discharge pressure when the signal pressure is equal to or higher than the threshold and the discharge pressure of the main pump reaches the set pressure of the main relief valve and the maximum load pressure where the maximum pressure is limited by the signal pressure variable relief valve. is there.
- FIG. 1 is a diagram showing a hydraulic drive device of a hydraulic excavator (construction machine) according to an embodiment of the present invention.
- a hydraulic drive apparatus includes a prime mover (for example, a diesel engine) 1 and a variable displacement main pump 2 (hydraulic pressure) that is driven by the prime mover 1 and discharges pressure oil to a pressure oil supply path 5.
- Pump a fixed displacement pilot pump 30 that is driven by the prime mover 1 and discharges the pressure oil to the pressure oil supply passage 31a, and a plurality of actuators 3a and 3b that are driven by the pressure oil discharged by the main pump 2.
- control valve unit 4 connected to the pressure oil supply passage 5 and controlling the flow of pressure oil supplied from the main pump 2 to the plurality of actuators 3a to 3h, and a load
- a regulator 12 pump control device that controls the discharge flow rate of the main pump 2 by sensing control and torque control is provided.
- the control valve unit 4 is connected to the pressure oil supply passage 5 and controls a plurality of flow rate control valves 6a, 6b, 6c, which control the flow rate and flow direction of the pressure oil supplied from the main pump 2 to the plurality of actuators 3a to 3h.
- 6d, 6e, 6f, 6g, 6h and the plurality of flow control valves 6a to 6h are controlled to control the differential pressure across the plurality of flow control valves 6a to 6h so that the differential pressure across the flow control valves 6a to 6h is equal to the target compensation differential pressure.
- a plurality of pressure compensating valves 7a, 7b, 7c, 7d, 7e which control the flow rate of the pressure oil controlled by the flow rate control valves 6a to 6h in proportion to the meter-in opening areas of the plurality of flow rate control valves 6a to 6j.
- An unload valve 15 that returns the pressure oil in the supply passage 5 to the tank, and shuttle valves 9a, 9b that are connected to the load ports of the flow control valves 6a to 6h in a tournament manner and detect the maximum load pressure Plmax of the actuators 3a to 3h,
- a maximum load pressure detection circuit 9 having 9c, 9d, 9e, 9f, 9g and outputting the maximum load pressure Plmax detected in the maximum load pressure line 35 connected to the output port of the shuttle valve 9g at the final stage;
- the maximum pressure of the maximum load pressure Plmaxa which is connected to the load pressure line 35 via the restrictor (fixed restrictor) 17 and led to the downstream side of the restrictor 17 of the maximum load pressure line 35, is set in the main relief valve 14.
- the differential pressure between the signal pressure relief valve 16 that restricts to a pressure lower than the pressure, the discharge pressure Pp of the main pump 2 and the maximum load pressure Plmaxa on the downstream side of the throttle 17 of the maximum load pressure line 35 is output as an absolute pressure Pls.
- the actuator 3a is, for example, a boom cylinder that drives a boom 104a (FIG. 3) of a hydraulic excavator
- the actuator 3b is, for example, an arm cylinder that drives an arm 104b (FIG. 3) of the hydraulic excavator
- the actuator 3c is, for example, hydraulic A swing motor that drives the upper swing body 109 (FIG. 3) of the excavator
- the actuator 3d drives, for example, a bucket cylinder that drives the bucket 104c (FIG. 3)
- the actuator 3e drives, for example, the swing post 103 (FIG. 3).
- the actuator 3f is, for example, a left traveling motor that drives the left crawler belt 101a (FIG.
- a right-hand drive motor that drives Eta 3h is, for example, a blade cylinder for driving the blade 106 (FIG. 3).
- the hydraulic drive device is connected to the pressure oil supply passage 31a of the pilot pump 30 and detects the discharge flow rate of the pilot pump 30 as an absolute pressure PGR.
- a pilot relief valve 32 that is connected to a pilot pressure oil supply passage 31 b on the downstream side of the prime mover rotation speed detection valve 13 and generates a constant pilot pressure Ppi in the pilot pressure oil supply passage 31 b, and a pilot pressure oil supply passage 31 b
- a gate lock valve 100 that switches between connecting the pressure oil supply passage 31c on the downstream side to the pressure oil supply passage 31b or the tank by the gate lock lever 24, and a pilot pressure on the downstream side of the gate lock valve 100.
- a travel operation detection circuit (specific actuator operation detection circuit) 70 including
- the prime mover rotational speed detection valve 13 includes a flow rate detection valve 50 connected between the pressure oil supply passage 31a and the pilot pressure oil supply passage 31b of the pilot pump 30, and the differential pressure across the flow rate detection valve 50 as an absolute pressure PGR. And a differential pressure reducing valve 51 that outputs as follows.
- the flow rate detection valve 50 has a variable restrictor 50a that increases the opening area as the passing flow rate (discharge flow rate of the pilot pump 30) increases.
- the oil discharged from the pilot pump 30 passes through the variable throttle 50a of the flow rate detection valve 50 and flows toward the pilot oil passage 31b.
- a differential pressure that increases as the passing flow rate increases in the variable throttle portion 50a of the flow rate detection valve 50, and the differential pressure reducing valve 51 uses the differential pressure in the front and rear as an absolute pressure PGR in the signal pressure line 52.
- Output Since the discharge flow rate of the pilot pump 30 changes depending on the rotation speed of the prime mover 1, the discharge flow rate of the pilot pump 30 can be detected by detecting the differential pressure across the variable throttle 50a. Can be detected.
- the pilot valve units 60a, 60b, 60c, 60d, 60e, 60f, 60g, and 60h include a boom operation device 123a, an arm operation device 122a, a turning operation device 122b, and a bucket operation device 123b, respectively.
- the swing operation device 125, the left travel operation device 124a, the right travel operation device 124b, and the blade operation device 126 are provided and operated when the operator operates the operation lever. a1, a2; b1, b2; c1, c2; d1, d2; e1, e2; f1, f2; g1, g2; h1, h2.
- the pilot valve units 60f, 60g to which the shuttle valves 70a, 70b, 70c are connected are for traveling, and the corresponding operating pilot pressures (operating pilot pressures f1, f2; when the operating devices 124a, 124b are operated).
- the highest pressure of g1 and g2) is detected by the shuttle valves 70a, 70b, 70c as the travel operation signal pressure Ptpi, and is applied to the signal pressure lines 36, 36a, 36b connected to the output port of the final stage shuttle valve 70c.
- the detected traveling operation signal pressure Ptpi is output.
- the absolute pressure PGR output from the differential pressure reducing valve 51 of the prime mover rotation speed detection valve 13 is guided to the regulator 12 as a target LS differential pressure, and is also introduced as a part of the set pressure Pun0 to the closing direction operation side of the unload valve 15. It is burned.
- the absolute pressure Pls output from the differential pressure reducing valve 11 is guided as a feedback LS differential pressure to the regulator 12 of the main pump 2, and is also guided as a target compensated differential pressure to the opening direction operation side of the pressure compensating valves 7a to 7h. Further, the absolute pressure PGR output from the differential pressure reducing valve 51 of the prime mover rotation speed detection valve 13 is guided to the signal pressure relief valve 16 as a part of a set pressure PA (described later).
- the travel operation signal pressure Ptpi detected by the travel operation detection circuit 70 is guided to the main relief valve 14 through the signal pressure line 36a as a part of the set pressure PS (described later) and through the signal pressure line 36b.
- the signal pressure relief valve 16 is also guided as part of the set pressure PA (described later).
- the regulator 12 includes an LS control valve 12b, an LS control piston (capacity control actuator) 12c, a torque control (horsepower control) piston (capacity control actuator) 12d, and a spring 12e.
- the LS control valve 12b has a pressure receiving portion 12b1 at an end portion that operates in a direction in which a constant pilot pressure Ppi is guided to the LS control piston 12c, and operates in a direction in which the pressure oil of the LS control piston 12c is discharged to the tank.
- a pressure receiving portion 12b2 is provided at the end on the side.
- the absolute pressure Pls (feedback LS differential pressure) output from the differential pressure reducing valve 11 to the pressure receiving portion 12b1 and passed through the switching valve 80 is guided, and the absolute pressure PGR (target) output from the prime mover rotational speed detection valve 13 to the pressure receiving portion 12b2.
- the LS control valve 12b guides a constant pilot pressure Ppi to the LS control piston 12c, and when Pls ⁇ PGR, the LS control valve 12b tanks the pressure oil of the LS control piston 12c. Operate to release.
- the LS control piston 12c is guided with a constant pilot pressure Ppi.
- the absolute pressure Pls output from the differential pressure reducing valve 11 (the differential pressure (feedback LS differential pressure) between the discharge pressure Pp of the main pump 2 and the maximum load pressure Plmaxa on the downstream side of the throttle 17 of the maximum load pressure line 35). It is controlled to be equal to the absolute pressure PGR (target LS differential pressure) output from the prime mover rotational speed detection valve 13, and as a result, the discharge pressure of the main pump 2 is the target differential pressure PGR from the maximum load pressure Plmaxa of the actuators 3a to 3h.
- the LS control valve 12b and the LS control piston 12c are configured so that the discharge pressure of the main pump 2 is higher by the target differential pressure PGR than the maximum load pressure Plmaxa of the actuators 3a to 3h.
- capacitance of 2 is comprised.
- the torque control piston 12d is guided by the discharge pressure of the main pump 2, and reduces the tilt (capacity) of the main pump 2 by increasing the discharge pressure so that the absorption torque of the main pump 2 does not exceed a predetermined torque. Torque control is performed.
- the spring 12e sets the torque control limit torque.
- the torque control piston 12d and the spring 12e provide a torque control unit that controls the capacity of the main pump 2 so that the absorption torque of the main pump 2 does not exceed a predetermined limit torque when the discharge pressure of the main pump 2 increases. It is composed.
- the pressure compensation valves 7a to 7h have pressure receiving portions 7a1, 7b1, 7c1, 7d1, 7e1, 7f1, 7g1, 7h1 to which the absolute pressure Pls output from the differential pressure reducing valve 11 is guided on the opening direction operation side.
- the pressure Pls is set as the target compensation differential pressure.
- the pressure compensation valves 7a to 7h are controlled so that the differential pressure across the flow control valves 6a to 6h is equal to the target compensation differential pressure.
- the absolute pressure Pls output from the differential pressure reducing valve 11 decreases according to the degree of supply shortage, and the target of the pressure compensation valve Since the compensated differential pressure is reduced, the main pump 2 discharge flow rate can be distributed according to the ratio of the opening area of the flow control valve in this case as well, and good composite operability can be ensured.
- the unload valve 15 has a pressure receiving portion 15a to which the absolute pressure PGR (target LS differential pressure) output from the prime mover rotational speed detection valve 13 is guided on the closing direction operation side, and a spring 15b is provided on the same closing direction operation side. Has been placed.
- the unload valve 15 is applied with the pressure of the pressure oil supply passage 5 (discharge pressure of the main pump 2) Pp on the open direction operation side, and the maximum load detected by the maximum load pressure detection circuit 9 on the close direction operation side.
- the pressure Plmax is applied.
- the set pressure of the unload valve 15 is defined by the absolute pressure PGR (target LS differential pressure), the urging force of the spring 15b, and the maximum load pressure Plmax.
- the set pressure of the unload valve 15 is given as a pressure obtained by adding the absolute pressure PGR (target LS differential pressure), the pressure conversion value of the urging force of the spring 15b, and the maximum load pressure Plmax.
- PGR target LS differential pressure
- the unload valve 15 is opened and operates to return the pressure oil in the pressure oil supply passage 5 to the tank, whereby the discharge pressure Pp of the main pump 2 is set as the target.
- the pressure is controlled so as not to become higher than the pressure obtained by adding the pressure conversion value of the urging force of the spring 15a to the LS differential pressure PGR.
- the pressure conversion value of the urging force of the spring 15a is usually a value smaller than the target LS differential pressure PGR.
- the main relief valve 14 has a spring 14a and a pressure receiving portion 14b (first pressure receiving portion) on the closing direction operation side.
- the pressure receiving portion 14b is connected to the signal pressure line 36a and is detected by the traveling operation detection circuit 70.
- a signal pressure Ptpi is applied.
- the set pressure PS of the main relief valve 14 is the first value PS1 set by the spring 14a.
- the set pressure PS of the main relief valve 14 is applied to the spring 14a and the pressure receiving portion 14b.
- the signal pressure Ptpi increases the first value PS1 to a second value PS2 that is larger than the first value PS1.
- the main relief valve 14 is configured as a variable relief valve in which the main relief valve 14 changes to binary values PS1 and PS2 according to the travel operation signal pressure Ptpi to which the set pressure PS is applied to the pressure receiving portion 14b.
- the signal pressure relief valve 16 has a spring 16a on the closing direction operation side and a first pressure receiving portion 16b on the opening direction operation side.
- the pressure receiving portion 16b is connected to the signal pressure line 52, and the signal pressure relief valve 16 is
- the variable pressure relief valve is configured to change depending on the output pressure (absolute pressure) PGR of the prime mover rotational speed detection valve 13 to which the set pressure PA is applied to the pressure receiving portion 14b.
- the signal pressure relief valve 16 has a second pressure receiving portion 16c (second pressure receiving portion) on the closing direction operation side, and the pressure receiving portion 16c is connected to the signal pressure line 36b and detected by the traveling operation detection circuit 70.
- the traveling operation signal pressure Ptpi is applied to the pressure receiving portion 16c.
- the set pressure PA of the signal pressure relief valve 16 is applied to the urging force of the spring 16a and the pressure receiving portion 16b.
- the third value PA1 based on the absolute pressure PGR to be performed.
- the set pressure PA of the signal pressure relief valve 16 is from the third value PA1 to the third value PA1. Increases to a large fourth value PA2.
- the signal pressure relief valve 16 is also configured as a variable relief valve in which the set pressure PA changes to binary PA1 and PA2 depending on the pressure applied to the pressure receiving portion 16c.
- the signal pressure relief valve 16 is referred to as a signal pressure variable relief valve.
- FIG. 2 is a graph showing changes in the set pressure with respect to the travel operation signal pressure Ptpi of the main relief valve 14 and the signal pressure variable relief valve 16.
- the horizontal axis represents the traveling operation signal pressure Ptpi detected by the traveling operation detection circuit 70
- the vertical axis represents the set pressures PS and PA of the main relief valve 14 and the signal pressure variable relief valve 16.
- the set pressure PS of the main relief valve 14 is the first due to the biasing force of the spring 14a.
- the set pressure PS of the main relief valve 14 is applied to the pressure receiving portion 14b.
- the travel operation signal pressure Ptpi is increased from the first value PS1 to the second value PS2 larger than the first value PS1 by ⁇ Pt1.
- ⁇ Pt1 is a pressure value set by applying the traveling operation signal pressure Ptpi to the pressure receiving portion 14b of the main relief valve 14.
- the set pressure PA of the signal pressure variable relief valve 16 is applied to the urging force of the spring 16a and the pressure receiving portion 16b.
- the absolute value PGR applied is at the third value PA1
- the signal pressure variable relief valve The set pressure PA of 16 is increased by ⁇ Pt2 from the third value PA1 to the fourth value PA2 larger than the third value PA1 by the traveling operation signal pressure Ptpi applied to the pressure receiving portion 16c.
- the spring 16a is configured to have a spring constant corresponding to the pressure value PS1 + ⁇
- the set pressure PA of the variable signal pressure relief valve 16 is the spring 16a, the absolute pressure PGR applied to the pressure receiving portion 16b, and the pressure receiving pressure.
- the traveling operation signal pressure Ptpi applied to the part 16c is controlled so as to be in the following formula.
- PA1 PS1 + ⁇ -PGR ⁇ When traveling operation signal pressure Ptpi applied to pressure receiving portion 16c is equal to or higher than threshold value Ptr>
- the signal pressure variable relief valve 16 is set both when the travel operation devices 124a and 124b are not operated and when at least one of the travel operation devices 124a and 124b is operated.
- the pressures PA1 and PA2 are controlled so as to be lower than the set pressures PS1 and PS2 of the main relief valve 14 by PGR- ⁇ .
- PGR- ⁇ is smaller than the target LS differential pressure (target differential pressure in load sensing control) PGR.
- the set pressure PA1 of the signal pressure variable relief valve 16 is the main pressure.
- the third value PA1 is lower than the first value PS1 of the set pressure of the relief valve 14, and at least one of the travel operation devices 124a, 124b is operated, and the set pressure of the main relief valve 14 is the second value.
- the set pressure of the signal pressure variable relief valve 16 increases from the third value PA1 to a fourth value PA4 which is smaller than the second value PS2 of the set pressure of the main relief valve 14, and
- the difference ⁇ Pt1 between the first value PS1 of the set pressure of the main relief valve 14 and the third value PA1 of the set pressure of the signal pressure variable relief valve, the second value PS2 of the set pressure of the main relief valve 14 and the signal pressure Variable relief valve 16 The difference between the fourth value PA2 bets pressure are both to be smaller than the target differential pressure PGR of the load sensing control, signal pressure variable relief valve 16 is configured.
- the set pressure is increased as the target LS differential pressure (target differential pressure in load sensing control) PGR decreases.
- the third value PA1 and the fourth value PA2 increase, and the differential pressure between the discharge pressure of the main pump 2 and the maximum load pressure Plmaxa downstream of the throttle 17 (the absolute pressure Pls output from the differential pressure reducing valve 11) decreases.
- the variable signal pressure relief valve 16 is configured.
- FIG. 3 is a diagram showing the external appearance of a hydraulic excavator in which the above-described hydraulic drive device is mounted.
- a hydraulic excavator well known as a work machine includes a lower traveling body 101, an upper swing body 109, and a swing-type front work machine 104.
- the front work machine 104 includes a boom 104a, an arm 104b, The bucket 104c is configured.
- the upper turning body 109 can turn with respect to the lower traveling body 101 by a turning motor 3c.
- a swing post 103 is attached to a front portion of the upper swing body 109, and a front work machine 104 is attached to the swing post 103 so as to be movable up and down.
- the swing post 103 can be rotated in the horizontal direction with respect to the upper swing body 109 by expansion and contraction of the swing cylinder 3e.
- the boom 104a, the arm 104b, and the bucket 104c of the front work machine 104 are the boom cylinder 3a, the arm cylinder 3b, and the bucket cylinder. It can be turned up and down by 3d expansion and contraction.
- a blade 106 that moves up and down by expansion and contraction of the blade cylinder 3h is attached to the central frame of the lower traveling body 102.
- the lower traveling body 101 travels by driving the left and right crawler belts 101a and 101b by the rotation of the traveling motors 3f and 3g.
- the upper swing body 109 is provided with a canopy type driver's cab 108.
- a driver's seat 121 In the driver's cab 108, there is a driver's seat 121, left / right operation devices 122 and 123 for front / turn (only the left side is shown in FIG. 3), and for driving.
- Operating devices 124a and 124b (shown only on the left side in FIG. 4), a swing operating device 125 (see FIG. 1), a blade operating device 126 (see FIG. 1), a gate lock lever 24, and the like.
- the operation levers of the operation devices 122 and 123 can be operated in any direction based on the cross direction from the neutral position.
- the operation device 122 When the left operation lever of the operation device 122 is operated in the front-rear direction, the operation device 122 is used for turning. When functioning as the operating device 122b (FIG. 1) and operating the operating lever of the operating device 122 in the left-right direction, the operating device 122 functions as the arm operating device 122a (FIG. 1). When the operation lever is operated in the front-rear direction, the operation device 123 functions as a boom operation device 123a (FIG. 1). When the operation lever of the operation device 123 is operated in the left-right direction, the operation device 123 is used for the bucket. It functions as the operation device 123b (FIG. 1).
- FIG. 4 is a diagram illustrating a comparative example.
- This comparative example is obtained by replacing the signal pressure variable relief valve 16 with the signal pressure variable relief valve 116 described in Patent Document 1 in the hydraulic drive system of the present embodiment shown in FIG.
- the main driving operation is performed.
- the main relief valve 14 is configured as a variable relief valve so that the set pressure of the relief valve 14 increases from the first value PS1 to the second value PS2.
- the signal pressure variable relief valve 116 does not include the pressure receiving portion 16 c according to the embodiment of the present invention shown in FIG. 1. For this reason, the set pressure PA of the variable signal pressure relief valve 116 is controlled so as to be expressed by the following equation with respect to the output pressure (absolute pressure) PGR of the prime mover rotation speed detection valve 13 applied to the pressure receiving portion 16b.
- PS1 is a set pressure of the main relief valve 14 when neither of the travel operation devices 124a and 124b is operated
- PS1 + ⁇ is a pressure value set by the spring constant of the spring 16a.
- ⁇ is an LS control adjustment value greater than 0 and less than PGR.
- the signal pressure variable relief valve 116 since the signal pressure variable relief valve 116 is provided, when neither the traveling operation devices 124a and 124b are operated and the traveling operation signal pressure Ptpi is the tank pressure, the signal pressure variable relief is provided.
- the maximum load pressure Plmaxa guided to the differential pressure reducing valve 11 by the action of the valve 116 is limited to the set pressure PS1- (PGR- ⁇ ) of the variable signal pressure relief valve 116, so that a cylinder type actuator such as the boom cylinder 3a is used. Even when the stroke end is reached, the absolute pressure Pls output from the differential pressure reducing valve 11 does not become zero. For this reason, when other actuators are combined and operated in this state, the other actuators do not stop operating.
- the comparative example has the following problems.
- the main relief valve 14 increases the set pressure of the main relief valve 14 from PS1 to PS2 only when at least one of the traveling operation devices 124a and 124b is operated and the traveling operation signal pressure Ptpi is equal to or higher than the threshold value Ptr.
- the purpose is to secure the required output torque of the traveling motors 3f and 3g during traveling and to improve traveling performance.
- FIG. 5 The left side (a) of FIG. 5 shows the case where the operating lever of the operating device other than traveling is input and the discharge pressure Pp of the main pump 2 reaches the set pressure PS1 of the main relief valve 14 in the comparative example shown in FIG. It is a figure which shows the relationship between the discharge pressure Pp and the maximum load pressure Plmaxa by which the maximum pressure was restrict
- FIG. 5 shows the relationship between the discharge pressure Pp and the maximum load pressure Plmaxa by which the maximum pressure was restrict
- the target compensation differential pressure (Pp ⁇ Plmaxa) is maintained at a value greater than 0 and less than PGR. Therefore, the pressure compensation valves 7a to 7h are not fully closed, and other actuators are combined to operate in this state. Can do.
- the absolute pressure PGR that is output by the prime mover rotation speed detection valve 13 and becomes the target LS differential pressure is guided to the pressure receiving portion 16b of the signal pressure variable relief valve 116.
- the maximum load pressure Plmaxa is limited to PS1 ⁇ (PGR ⁇ ) by the signal pressure variable relief valve 116 at any prime mover speed, so that excellent composite operability can be achieved regardless of the speed of the prime mover 1. Obtainable.
- the set pressure of the main relief valve 14 is set to the first value PS1 by the travel operation signal pressure Ptpi. Increases from 2 to the second value PS2.
- FIG. 6 is a diagram showing the relationship between the discharge pressure Pp when the pressure reaches the set pressure PS2 of the main relief valve 14 and the maximum load pressure Plmaxa whose maximum pressure is limited by the signal pressure variable relief valve 116.
- the maximum load pressure Plmaxa is limited to PS1- (PGR- ⁇ ) by the signal pressure variable relief valve 116, so that the absolute pressure Pls (Pp ⁇ Plmaxa) is PGR + (PS2-PS1) - ⁇ .
- PS2-PS1 ⁇ Pt1
- ⁇ Pt1 is set to a value larger than the PGR that is the target LS differential pressure. For this reason, the absolute pressure Pls is larger than the target LS differential pressure PGR.
- the load pressure of the travel motors 3f and 3g does not increase to PS2 that is the set pressure of the main relief valve 14 during the travel operation, and the necessary travel is performed even though the main relief valve 14 is variable. There arises a problem that the output torque of the motors 3f and 3g cannot be obtained.
- a prime mover rotational speed detection valve 13 is connected to the pressure oil supply passage 31a.
- the prime mover rotational speed detection valve 13 is configured by a flow rate detection valve 50 and a differential pressure reducing valve 51 according to the discharge flow rate of the pilot pump 30. Is output as absolute pressure PGR (target LS differential pressure).
- a pilot relief valve 32 is connected downstream of the prime mover rotation speed detection valve 13 to generate a constant pressure (pilot primary pressure) Ppi in the pilot pressure oil supply passage 31b.
- the set pressure of the unload valve 15 is the value of the prime motor rotation speed detection valve 13 applied to the pressure receiving portion 15a. This is a value obtained by adding the output pressure PGR (target LS differential pressure) and the pressure converted value of the urging force of the spring 15b.
- the pressure Pp of the pressure oil supply passage 5 is added to the target LS differential pressure PGR by the spring 15b. Is maintained at a pressure obtained by adding the pressure conversion value of the urging force (Pp> PGR).
- the maximum load pressure Plmax is guided to the downstream side of the throttle 17 through the throttle 17, and the maximum load pressure Plmaxa on the downstream side of the throttle 17 is guided to the differential pressure reducing valve 11 and the signal pressure variable relief valve 16.
- the set pressure of the signal pressure variable relief valve 16 at this time is PS1- (PGR- ⁇ ), which is much higher than Plmax maintained at the tank pressure, so Plmax is the signal pressure variable relief valve.
- Plmaxa Plmax.
- Plmaxa Plmax
- Pls Plmax
- the absolute pressure Pls output from the differential pressure reducing valve 11 is guided to the LS control valve 12b of the regulator 12 as a feedback LS differential pressure. Since the LS control valve 12b compares Pls and PGR and Pls> PGR, the LS control valve 12b is pushed leftward in FIG. 1 to switch to the right position, and is generated by the pilot relief valve 32.
- the pilot primary pressure Ppi is guided to the LS control piston 12c. Since a constant pilot primary pressure Ppi is introduced to the LS control piston 12c, the capacity (flow rate) of the main pump 2 is kept to a minimum.
- the pressure receiving portion 14b of the main relief valve 14 and the pressure receiving portion 16c of the signal pressure variable relief valve 16 include As in the case of (a), the tank pressure is guided through the shuttle valves 70a, 70b, 70c and the signal pressure lines 36, 36a, 36b of the traveling operation detection circuit 70. At this time, as shown in FIG. 2, the set pressure of the main relief valve 14 is the first value PS1 set by the spring 14a, and the set pressure of the signal pressure variable relief valve 16 is set by the spring 16a and the pressure receiving portion 16b.
- the set third value PA1, that is, PS1- (PGR- ⁇ ) is obtained.
- the boom pilot valve unit 60a When the boom operation lever is input in the direction in which the boom cylinder 3a extends, that is, in the boom raising direction, the boom pilot valve unit 60a outputs the boom raising operation pilot pressure a1, and the flow control valve 6a moves rightward in FIG. Switch.
- the flow control valve 6a When the flow control valve 6a is switched from the neutral position, pressure oil is supplied to the boom cylinder 3a, and the load pressure of the boom cylinder 3a is supplied to the shuttle valves 9a, 9b, 9c, 9d via the load port of the flow control valve 6a.
- the maximum load pressure Plmax is detected as the maximum load pressure Plmax, and this maximum load pressure Plmax is guided to the unload valve 15 and also to the downstream side of the throttle 17, and the throttle 17
- the maximum load pressure Plmaxa is led to the differential pressure reducing valve 11 and the signal pressure variable relief valve 16 on the downstream side.
- the set pressure of the unload valve 15 is set such that the output pressure PGR (target LS differential pressure) of the prime mover rotation speed detection valve 13 applied to the pressure receiving portion 15a and the spring 15b.
- the pressure conversion value of the urging force and the maximum load pressure Plmax (load pressure on the bottom side of the boom cylinder 3a) are increased to a pressure (PGR + pressure conversion value of the urging force of the spring 15b + Plmax), and the pressure oil supply path 5 Shut off the oil passage that discharges the pressure oil to the tank.
- the set pressure of the signal pressure variable relief valve 16 is PS1- (PGR- ⁇ ) as described above, and the maximum pressure of the maximum load pressure Plmaxa on the downstream side of the throttle 17 is limited to PS1- (PGR- ⁇ ).
- the differential pressure reducing valve 11 outputs the differential pressure (Pp-Plmaxa) between the pressure in the pressure oil supply passage 5 (discharge pressure of the main pump 2) Pp and the maximum load pressure Plmaxa as an absolute pressure Pls.
- the feedback LS differential pressure is guided to the LS control valve 12b of the regulator 12.
- the LS control valve 12b compares Pls and PGR.
- the LS control valve 12b of the regulator 12 is Pls ⁇ PGR
- the pressure oil discharged from the main pump 2 to the pressure oil supply path 5 is supplied to the bottom side of the boom cylinder 3a via the pressure compensation valve 7a and the flow rate control valve 6a, and the boom cylinder 3a is extended.
- the load pressure of the boom cylinder 3a and the pressure of the pressure oil supply passage 5 (discharge pressure of the main pump 2) Pp rise to the set pressure PS1 of the main relief valve 14.
- the left side (a) of FIG. 6 inputs an operation lever of an operating device other than traveling, and the discharge pressure Pp and the signal pressure variable relief when the discharge pressure Pp of the main pump 2 reaches the set pressure PS1 of the main relief valve 14. It is a figure which shows the relationship with the maximum load pressure Plmaxa by which the maximum pressure was restrict
- the maximum load pressure Plmaxa on the downstream side of the throttle 17 is limited to the set pressure PS1- (PGR- ⁇ ) because the set pressure of the signal pressure variable relief valve 16 is PS1- (PGR- ⁇ ).
- ⁇ is a value greater than 0 and less than PGR as described above. 0 ⁇ Pls ⁇ PGR It becomes.
- the absolute pressure PGR output from the prime mover rotation speed detection valve 13 and serving as the target LS differential pressure is guided to the pressure receiving portion 16b of the variable signal pressure relief valve 16, and the variable signal pressure relief as the target LS differential pressure PGR decreases.
- the absolute value Pls (the discharge pressure Pp of the main pump 2 and the maximum load pressure on the downstream side of the throttle 17) output from the differential pressure reducing valve 11 when the third value PA1 and the fourth value PA2 of the set pressure of the valve 16 increase. (Differential pressure with Plmaxa) becomes smaller.
- the maximum pressure of the maximum load pressure Plmaxa is limited to PS1- (PGR- ⁇ ) by the signal pressure variable relief valve 16, and the main pressure Since the differential pressure Pls between the discharge pressure Pp of the pump 2 and the maximum load pressure Plmaxa on the downstream side of the throttle 17 changes according to the target LS differential pressure PGR, good combined operability can be achieved regardless of the rotational speed of the prime mover 1. Obtainable.
- the set pressure increases to PS2 obtained by adding the value ⁇ Pt set by the travel operation signal pressure Ptpi of the pressure receiving portion 14b to the first actuator PS1 set by the spring 14a, and the set pressure of the signal pressure variable relief valve 16 is PA2 obtained by adding the value ⁇ Pt set by the travel operation signal pressure Ptpi of the pressure receiving portion 16c to the third value PA1 set by the spring 16a and the pressure receiving portion 16b, that is, PS2 Increase to + ⁇ -PGR.
- the set pressure of the unload valve 15 is set such that the output pressure PGR (target LS differential pressure) of the prime mover rotation speed detection valve 13 applied to the pressure receiving portion 15a and the spring 15b.
- the pressure rises to the pressure (PGR + pressure conversion value of the urging force of the spring 15b + Plmax) obtained by adding the pressure conversion value of the urging force and the maximum load pressure Plmax (load pressure of the left traveling motor 3f) to the pressure oil supply passage 5 Shut off the oil passage that discharges to the tank.
- the set pressure of the signal pressure variable relief valve 16 is PS2- (PGR- ⁇ ) as described above, and the maximum load pressure on the downstream side of the throttle 17 Plmaxa maximum pressure is limited to PS2- (PGR- ⁇ ).
- the differential pressure reducing valve 11 outputs the differential pressure (Pp ⁇ Plmaxa) between the pressure in the pressure oil supply passage 5 (discharge pressure of the main pump 2) Pp and the maximum load pressure Plmaxa on the downstream side of the throttle 17 as an absolute pressure Pls.
- the absolute pressure Pls is guided to the LS control valve 12b of the regulator 12 as a feedback LS differential pressure.
- the LS control valve 12b compares Pls and PGR as in the case of (b), and controls the tilt of the main pump 2 so that Pls becomes equal to PGR.
- the pressure oil discharged from the main pump 2 to the pressure oil supply path 5 is supplied to the left traveling motor 3f via the pressure compensation valve 7f and the flow rate control valve 6f, and rotates the left traveling motor 3f.
- the right side (b) of FIG. 6 inputs the operating lever of the traveling operation device, the traveling operation signal pressure Ptpi is equal to or higher than the threshold value Ptr, and the discharge pressure Pp of the main pump 2 reaches the set pressure PS2 of the main relief valve 14. It is a figure which shows the relationship between the discharge pressure Pp at that time, and the maximum load pressure Plmaxa by which the maximum pressure was restrict
- the maximum load pressure Plmaxa on the downstream side of the throttle 17 is limited to the set pressure PS2- (PGR- ⁇ ) because the set pressure of the signal pressure variable relief valve 16 is PS2- (PGR- ⁇ ).
- ⁇ is a value greater than 0 and less than PGR as described above. 0 ⁇ Pls ⁇ PGR It becomes.
- the LS control valve 12b of the regulator 12 is Pls ⁇ PGR
- the maximum load pressure Plmaxa is limited to PS2- (PGR- ⁇ ) by the action of the signal pressure variable relief valve 16. Since the feedback LS differential pressure Pls becomes PGR- ⁇ (Pls does not become larger than PGR as in the comparative example shown in FIG. 4), the discharge pressure of the main pump 2 (the load pressure of the left travel motor 3f) is the main The pressure rises to the set pressure PS2 of the relief valve 14, and the load pressure of the left traveling motor 3f does not reach PS2 due to the load sensing control of the main pump 2 as in the comparative example.
- the pressure receiving portion 16b of the signal pressure variable relief valve 16 is output by the prime mover rotational speed detection valve 13 and becomes the target LS differential pressure. Since the pressure PGR is introduced, the maximum pressure of the maximum load pressure Plmaxa is changed to the target LS differential pressure PGR by the signal pressure variable relief valve 16 regardless of the value of the target LS differential pressure PGR due to the change in the engine speed. Therefore, it is possible to obtain a good composite operability regardless of the rotational speed of the prime mover 1.
- the set pressure of the signal pressure variable relief valve 16 increases from the third value PA1 to the fourth value PA2
- the set pressure of the main relief valve 14 increases from the first value PS1 to the second value.
- the set pressure increases by the same value ⁇ Pt2 as the value ⁇ Pt1 that increases to the value PS2.
- the variable signal pressure relief valve 16 has the second pressure receiving portion 16c on the closing direction operation side, and the traveling operation signal pressure Ptpi applied to the second pressure receiving portion 16c is equal to or greater than the threshold value Ptr.
- the set pressure of the main relief valve 16 increases from PS1 to PS2
- the relationship of Pls ⁇ PGR is obtained by the action of the signal pressure variable relief valve 16, and therefore, as shown in FIG. 6B.
- the discharge pressure Pp of the main pump 2 can be increased to PS2 by load sensing control, and the required output torque of the traveling motors 3f and 3g can be ensured during traveling to improve traveling performance.
- the absolute pressure Pls output as the target compensation differential pressure from the differential pressure reducing valve 11 becomes zero. Therefore, even when other actuators are combined and operated in that state, the other actuators do not stop operating, and good combined operability is maintained.
- the target LS differential pressure PGR is detected by a change in the prime mover rotational speed. No matter what value the signal pressure variable relief valve 16 limits the maximum pressure of the maximum load pressure Plmaxa to PS1- (PGR- ⁇ ). Sex can be obtained.
- the set pressure of the signal pressure variable relief valve 16 increases from the third value PA1 to the fourth value PA2, the set pressure of the main relief valve 14 increases from the first value PS1 to the second value PS2. Since the set pressure increases by the same value ⁇ Pt2 as the value ⁇ Pt1, the state where the actuators other than the traveling motors 3f and 3g are driven is shifted to the combined operation of simultaneously driving the traveling motors 3f and 3g and the traveling motors 3f and 3g.
- the differential pressure between the discharge pressure Pp of the main pump 2 and the maximum load pressure Plmaxa is the main pressure Before and after the discharge pressure Pp of the pump 2 rises to PS2, it is maintained at the same value.
- the construction machine is a hydraulic excavator
- the specific actuator operated when the set pressure of the main relief valve 14 is increased is the traveling motors 3f and 3g. May be an actuator other than the traveling motor, or may be one actuator or a plurality of actuators.
- the specific actuator may be at least one of the boom cylinder 3a, the arm cylinder 3b, and the bucket cylinder 3d, and by increasing the set pressure of the main relief valve 14 when such an actuator is operated, For example, excavation force and work speed in excavation loading work can be increased, and work efficiency can be improved.
- the present invention is applied to a construction machine other than a hydraulic excavator such as a hydraulic traveling crane. Also good.
- the differential pressure reducing valve 11 that outputs the discharge pressure of the main pump 2 and the maximum load pressure Plmaxa as absolute pressure is provided, and the output pressure Pls is led to the pressure compensating valves 7a to 7h to achieve the target compensation difference.
- the pressure was set and led to the LS control valve 12b as a feedback differential pressure
- the pressure control valves 7a to 7h were provided for the discharge pressure and the maximum load pressure of the main pump 2 in separate oil passages without providing the differential pressure reducing valve 11.
- it may be guided to the LS control valve 12b.
- the target LS differential pressure is set as a value that changes according to the rotational speed of the prime mover 1 by the absolute pressure PGR output from the prime mover rotational speed detection valve 13, but according to the rotational speed of the prime mover. If the target LS differential pressure need not be changed, the target LS differential pressure may be a fixed value.
- the set pressure of the variable signal pressure relief valve 16 increases from the third value PA1 to the fourth value PA2
- the set pressure of the main relief valve 14 increases from the first value PS1 to the second value.
- the set pressure is increased by the same value ⁇ Pt2 as the value ⁇ Pt1 that increases to the value PS2, but the difference between the increased fourth value PA2 and the second value PS2 of the set pressure of the main relief valve 14 is the target LS difference.
- ⁇ Pt2 may not be the same value as ⁇ Pt1.
- ⁇ Pt2 may be set to be smaller than ⁇ Pt1, and in this case, when shifting to the traveling combined operation, the differential pressure Pls between the discharge pressure Pp of the main pump 2 and the maximum load pressure Plmaxa becomes smaller. The speed is reduced and the safety in the traveling combined operation can be improved.
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Abstract
Description
図1は、本発明の一実施の形態に係わる油圧ショベル(建設機械)の油圧駆動装置を示す図である。
PA1=PS1+α-PGR
<受圧部16cに印加される走行操作信号圧力Ptpiが閾値Ptr以上であるとき>
PA2=PS1+α+ΔPt2-PGR
=PS1+α+ΔPt1-PGR
=PS2+α-PGR
上式を変形すると、
PA1=PS1-(PGR-α)
PA2=PS2-(PGR-α)
なお、αは0より大きくPGR未満のLS制御調整値である(0<α<PGR)。
図4は、比較例を示す図である。この比較例は、図1に示した本実施の形態の油圧駆動装置において、信号圧可変リリーフ弁16を特許文献1記載の信号圧可変リリーフ弁116に置き換えたものである。言い換えれば、特許文献1に記載のように、最高負荷圧ライン35に信号圧可変リリーフ弁116を設けたロードセンシング制御システムの油圧駆動装置において、特許文献2に記載のように、走行操作時にメインリリーフ弁14のセット圧が第1の値PS1から第2の値PS2に増加するようにメインリリーフ弁14を可変リリーフ弁として構成した場合のものである。
上式を変形すると、
PA=PS1-(PGR-α)
前述したように、PS1は走行用の操作装置124a,124bのいずれも操作されていないときのメインリリーフ弁14のセット圧であり、PS1+αはバネ16aのバネ常数によって設定される圧力値である。αは0より大きくPGR未満のLS制御調整値である。
次に、図1に示した本実施の形態の動作を説明する。
全ての操作装置の操作レバーが中立の場合、メインリリーフ弁14の受圧部14b及び信号圧可変リリーフ弁16の受圧部16cには、走行操作検出回路70のシャトル弁70a,70b,70c及び信号圧力ライン36,36a,36bを介してタンク圧が導かれる。このとき、図2に示したように、メインリリーフ弁14のセット圧はバネ14aで設定された第1の値PS1であり、信号圧可変リリーフ弁16のセット圧はバネ16aと受圧部16bにより設定された第3の値PA1、すなわちPS1-(PGR-α)となる。
全ての操作装置の操作レバーが中立の場合には、前述のようにPlmaxa(=Plmax)はタンク圧であるため、タンク圧が0であると仮定すると、Pls=Pp-Plmaxa=Pp>PGRの関係が成り立っている。
走行以外の操作装置の操作レバーを入力した場合、メインリリーフ弁14の受圧部14b及び信号圧可変リリーフ弁16の受圧部16cには、(a)の場合と同様に、走行操作検出回路70のシャトル弁70a,70b,70c及び信号圧力ライン36,36a,36bを介してタンク圧が導かれる。このとき、図2に示したように、メインリリーフ弁14のセット圧はバネ14aで設定された第1の値PS1であり、信号圧可変リリーフ弁16のセット圧はバネ16aと受圧部16bにより設定された第3の値PA1、すなわちPS1-(PGR-α)となる。
Pls=Pp-Plmaxa=PS1-(PS1-(PGR-α))=PGR-α
となる。ここで、αは前述のように0より大きくPGR未満の値であるので、
0<Pls<PGR
となる。
走行用の操作装置124a,124bのいずれか或いは両方の操作レバーを入力した場合、走行操作検出回路70のシャトル弁70a,70b,70cによって高圧選択され、メインリリーフ弁14の受圧部14bと信号圧可変リリーフ弁16の受圧部16cに導かれた走行操作信号圧力Ptpiが閾値Ptr以上になると、図2に示したように、メインリリーフ弁14のセット圧は、バネ14aで設定された第1のアクチュエータPS1に受圧部14bの走行操作信号圧力Ptpiによって設定された値ΔPtを加算したPS2に増加し、信号圧可変リリーフ弁16のセット圧は、バネ16aと受圧部16bとで設定された第3の値PA1に受圧部16cの走行操作信号圧力Ptpiによって設定された値ΔPtを加算したPA2、すなわちPS2+α-PGRに増加する。
Pls=Pp-Plmaxa=PS2-(PS1-(PGR-α))=PGR-α
となる。ここで、αは前述のように0より大きくPGR未満の値であるので、
0<Pls<PGR
となる。
以上のように本実施の形態においては、信号圧可変リリーフ弁16は閉方向作動側に第2受圧部16cを有し、第2受圧部16cに印加される走行操作信号圧力Ptpiが閾値Ptr以上になると、メインリリーフ弁16のセット圧がPS1からPS2に増加するのに合わせて信号圧可変リリーフ弁16のセット圧がPA1からPA2(=PS2-(PGR-α))に増加する。これにより、左走行モータ3fの負荷圧がメインリリーフ弁14のセット圧PS2に達しようとした場合に、信号圧可変リリーフ弁16の働きによってPls<PGRの関係が得られるため、図6Bに示すようにロードセンシング制御でメインポンプ2の吐出圧PpをPS2まで上昇させることができ、走行時に走行モータ3f,3gの必要な出力トルクを確保し、走破性を向上させることができる。
以上の実施の形態では、建設機械が油圧ショベルであり、メインリリーフ弁14のセット圧を増加させる場合に操作される特定のアクチュエータが走行モータ3f,3gである場合について説明したが、特定のアクチュエータは走行モータ以外のアクチュエータであってもよいし、1つのアクチュエータでも複数のアクチュエータであってもよい。例えば、特定のアクチュエータはブームシリンダ3a、アームシリンダ3b、バケットシリンダ3dの少なくとも1つであってもよく、このようなアクチュエータが操作されたときにメインリリーフ弁14のセット圧を増加させることで、例えば掘削積み荷作業における掘削力や作業速度を増大させることができ、作業効率を向上することができる。
2 メインポンプ(油圧ポンプ)
3a~3h アクチュエータ
3f,3g 走行モータ(特定のアクチュエータ)
4 コントロールバルブユニット
6a~6h 流量制御弁
7a~7h 圧力補償弁
9 最高負荷圧検出回路
12 レギュレータ(ポンプ制御装置)
12c LS制御ピストン(容量制御アクチュエータ)
12d トルク制御ピストン(容量制御アクチュエータ)
14 メインリリーフ弁
14b メインリリーフ弁の受圧部(第1受圧部)
15 アンロード弁
16 信号圧可変リリーフ弁(信号圧リリーフ弁)
16c 信号圧可変リリーフ弁の受圧部(第2受圧部)
17 絞り
35 最高負荷圧検出ライン
70 走行操作検出回路
124a,124b 走行用の操作装
Claims (5)
- 原動機により駆動される可変容量型の油圧ポンプと、
この油圧ポンプにより吐出された圧油により駆動される複数のアクチュエータと、
前記油圧ポンプから前記複数のアクチュエータに供給される圧油の流量を制御する複数の流量制御弁と、
前記複数の流量制御弁の前後差圧が目標補償差圧に等しくなるよう前記複数の流量制御弁の前後差圧をそれぞれ制御する複数の圧力補償弁と、
前記油圧ポンプの吐出圧が前記複数のアクチュエータの最高負荷圧より目標差圧だけ高くなるように前記油圧ポンプの容量をロードセンシング制御するポンプ制御装置と、
前記油圧ポンプの吐出圧の最大圧力を制限するメインリリーフ弁と、
前記複数のアクチュエータの最高負荷圧を検出し、検出した最高負荷圧を最高負荷圧ラインに出力する最高負荷圧検出回路と、
前記最高負荷圧ラインに絞りを介して接続され、前記絞りの下流側に導かれた最高負荷圧の最大圧力を前記メインリリーフ弁のセット圧よりも低い圧力に制限する信号圧リリーフ弁とを備え、
前記油圧ポンプの吐出圧と前記絞りの下流側の最高負荷圧との差圧が前記ポンプ制御装置に導かれ、前記ポンプ制御装置は、前記差圧が前記ロードセンシング制御の目標差圧と等しくなるよう前記油圧ポンプの容量を制御するととともに、前記油圧ポンプの吐出圧と前記絞りの下流側の最高負荷圧との差圧が前記目標補償差圧として前記複数の圧力補償弁に導かれる建設機械の油圧駆動装置において、
前記メインリリーフ弁は、前記複数のアクチュエータのうちの特定のアクチュエータが操作されていないときは、前記メインリリーフ弁のセット圧が第1の値にあり、前記特定のアクチュエータが操作されたときは、前記メインリリーフ弁のセット圧が前記第1の値から前記第1の値よりも大きい第2の値に増加するよう構成され、
前記信号圧リリーフ弁は、前記特定のアクチュエータが操作されておらず、前記メインリリーフ弁のセット圧が前記第1の値にあるときは、前記信号圧リリーフ弁のセット圧が前記メインリリーフ弁のセット圧の第1の値よりも小さい第3の値にあり、前記特定のアクチュエータが操作され、前記メインリリーフ弁のセット圧が前記第2の値に増加するときは、前記信号圧リリーフ弁のセット圧が前記第3の値から、前記メインリリーフ弁のセット圧の第2の値よりも小さい第4の値に増加し、かつ前記メインリリーフ弁のセット圧の第1の値と前記信号圧リリーフ弁のセット圧の第3の値との差と、前記メインリリーフ弁のセット圧の第2の値と前記信号圧リリーフ弁のセット圧の第4の値との差が、共に、前記ロードセンシング制御の目標差圧よりも小さくなるように構成されていることを特徴とする建設機械の油圧駆動装置。 - 請求項1に記載の建設機械の油圧駆動装置において、
前記信号圧リリーフ弁は、前記信号圧リリーフ弁のセット圧が第3の値から第4の値に増加するとき、前記メインリリーフ弁のセット圧が第1の値から第2の値に増加する値と同じ値だけセット圧が増加するように構成されていることを特徴とする建設機械の油圧駆動装置。 - 請求項1に記載の建設機械の油圧駆動装置において、
前記信号圧リリーフ弁は、前記ロードセンシング制御の目標差圧が小さくなるにしたがって前記セット圧の第3の値及び第4の値が大きくなり前記油圧ポンプの吐出圧と前記絞りの下流側の最高負荷圧との差圧が小さくなるように構成されていることを特徴とする建設機械の油圧駆動装置。 - 請求項1に記載の建設機械の油圧駆動装置において、
前記複数の流量制御弁を切り換え操作するための操作パイロット圧を生成する操作装置を更に備え、
前記メインリリーフ弁は、前記特定のアクチュエータの操作装置が生成する操作パイロット圧が印加される第1受圧部を有し、前記第1受圧部に印加される操作パイロット圧が閾値より低いときは、前記セット圧は前記第1の値であり、前記操作パイロット圧が前記閾値以上になると、前記セット圧は前記第2の値に増加し、
前記信号圧リリーフ弁は、前記特定のアクチュエータの操作装置が生成する操作パイロット圧が印加される第2受圧部を有し、前記第2受圧部に印加される操作パイロット圧が前記閾値より低いときは、前記セット圧は前記第3の値であり、前記操作パイロット圧が前記閾値以上になると、前記セット圧は前記第4の値に増加することを特徴とする建設機械の油圧駆動装置。 - 請求項1に記載の建設機械の油圧駆動装置において、
前記建設機械は油圧ショベルであり、
前記特定のアクチュエータは、前記油圧ショベルの走行モータであることを特徴とする建設機械の油圧駆動装置。
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