EP1211359B1 - Boom cylinder control circuit of working machine - Google Patents
Boom cylinder control circuit of working machine Download PDFInfo
- Publication number
- EP1211359B1 EP1211359B1 EP00956920A EP00956920A EP1211359B1 EP 1211359 B1 EP1211359 B1 EP 1211359B1 EP 00956920 A EP00956920 A EP 00956920A EP 00956920 A EP00956920 A EP 00956920A EP 1211359 B1 EP1211359 B1 EP 1211359B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- lowering
- oil
- boom
- boom cylinder
- rising
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2221—Control of flow rate; Load sensing arrangements
- E02F9/2225—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
- E02F3/00—Dredgers; Soil-shifting machines
- E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
- E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
- E02F3/36—Component parts
- E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
- E02F3/43—Control of dipper or bucket position; Control of sequence of drive operations
- E02F3/435—Control of dipper or bucket position; Control of sequence of drive operations for dipper-arms, backhoes or the like
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- 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
- E02F9/2203—Arrangements for controlling the attitude of actuators, e.g. speed, floating function
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2221—Control of flow rate; Load sensing arrangements
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2278—Hydraulic circuits
- E02F9/2285—Pilot-operated systems
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- 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
- F15B11/003—Systems with load-holding valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
- F15B11/024—Systems essentially incorporating special features for controlling the speed or actuating force of an output member by means of differential connection of the servomotor lines, e.g. regenerative circuits
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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
- F15B11/044—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the return line, i.e. "meter out"
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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
- F15B2211/30505—Non-return valves, i.e. check valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/305—Directional control characterised by the type of valves
- F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/31—Directional control characterised by the positions of the valve element
- F15B2211/3105—Neutral or centre positions
- F15B2211/3111—Neutral or centre positions the pump port being closed in the centre position, e.g. so-called closed centre
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/31—Directional control characterised by the positions of the valve element
- F15B2211/3144—Directional control characterised by the positions of the valve element the positions being continuously variable, e.g. as realised by proportional valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
- F15B2211/3157—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line
- F15B2211/31588—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line having a single pressure source and multiple output members
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/32—Directional control characterised by the type of actuation
- F15B2211/329—Directional control characterised by the type of actuation actuated by fluid pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/40—Flow control
- F15B2211/405—Flow control characterised by the type of flow control means or valve
- F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/40—Flow control
- F15B2211/405—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
- F15B2211/40—Flow control
- F15B2211/41—Flow control characterised by the positions of the valve element
- F15B2211/413—Flow 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
- F15B2211/40—Flow control
- F15B2211/415—Flow control characterised by the connections of the flow control means in the circuit
- F15B2211/41581—Flow control characterised by the connections of the flow control means in the circuit being connected to an output member and a return line
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/40—Flow control
- F15B2211/42—Flow control characterised by the type of actuation
- F15B2211/428—Flow control characterised by the type of actuation actuated by fluid pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/40—Flow control
- F15B2211/46—Control of flow in the return line, i.e. meter-out control
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/63—Electronic controllers
- F15B2211/6303—Electronic controllers using input signals
- F15B2211/6306—Electronic controllers using input signals representing a pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/63—Electronic controllers
- F15B2211/6303—Electronic controllers using input signals
- F15B2211/6346—Electronic controllers using input signals representing a state of input means, e.g. joystick position
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/635—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements
- F15B2211/6355—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements having valve means
Definitions
- the present invention belongs to the technical field of a boom cylinder control circuit of an operation machine such as a hydraulic shovel.
- a stick is supported so as to be swingable back and forth on the front end portion of a boom whose base end portion is supported so as to be swingable up and down on the machine main body and a tool such as a bucket, a breaker, a clamshell or the like is attached on the front end portion of the said stick.
- a working machine for example as shown in Fig. 5 , when removing operations of rocks lying on flat ground are performed by moving a bucket 7 back and forth along the ground, in addition to manipulations of the stick 6, manipulations of a boom 5 are performed simultaneously in order to move the boom up and down. Also, as shown in Fig.
- JP-09 132927A discloses a boom cylinder control circuit in which a control valve is used to control fluid pressure to the boom cylinder in accordance with manipulations of an operating member and instructions from a control unit.
- a lowering side oil discharge passage, the opening and closing of wich is controlled by a lowering side control means, can allow fluid to flow to a reservoir.
- Other prior art arrangements are described in DE 19932948A and FR-A-2537184 .
- a boom cylinder control circuit of a working machine having a boom cylinder for moving a boom up and down
- said control circuit of the boom cylinder comprising; a control valve which performs pressure oil supplying and discharging control with respect to the boom cylinder based on manipulations of an operating member and instructions from a control unit; a lowering side oil discharging passage which allows oil of a boom cylinder head side oil chamber to flow toward the oil reservoir side without passing through the control valve; and a lowering side control means which performs opening and closing control of the lowering side oil discharging passage based on the instructions from the control unit, characterized in that a mode selector switch is connected to the control unit permitting selection of a normal mode and a lowering hold releasing mode, wherein when the normal mode is selected by the mode selector switch the lowering side control means is controlled so as to close the lowering side oil discharging passage based on the instructions from the control unit and the control valve is controlled so as to supply the pressure oil to the boom cylinder in accordance
- the control circuit according to claim 2 includes a rising side oil discharge passage which allows oil of a boom cylinder rod side oil chamber to flow toward the oil reservoir side without passing through the control valve and a rising side control means which performs opening and closing control of the rising side oil discharging passage, the mode selector switch permitting the selection of a lowering and rising hold releasing mode, wherein when the lowering and rising hold releasing mode is selected by the mode selector switch and the operating member is operated toward the boom rising side, the lowering side control means is controlled so as to close the lowering side oil discharging passage and the rising side control means is controlled so as to open the rising side oil discharging passage, based on the instructions from the control unit and the control valve is controlled so as to supply the pressure oil to the rising side of the boom cylinder in accordance with the manipulations of the operating member, and wherein when the lowering and rising hold releasing mode is selected by the mode selector switch and the operating member is operated toward the boom lowering side, the lowering side control means and the rising side control means open their discharging passage
- the lowering side oil discharging passage is controlled so as to be opened based on a manipulation of the operating member toward the boom lowering side and on the other hand, when the said lowering side oil discharging passage is open, the lowering side oil discharging passage is controlled so that, even by operating the operating member toward the boom lowering side, the pressure oil is not supplied from the control valve to the boom cylinder, whereby it is avoidable that the boom unexpectedly moves down due to the empty weight without an operator's intentions.
- the control means which performs opening and closing control of the lowering side oil discharging passage and the rising side oil discharging passage can comprise solenoid valves which can be switched between the opening position to open the oil discharging passage and closing position to close the oil discharging passage.
- the control circuit may include valves for preventing empty weight-lowering which, when the operating member is not manipulated toward the boom lowering side, prevent oil from being discharged from the boom cylinder head side oil chamber, but, based on a manipulation toward the boom lowering side, allow oil to be discharged from the head side oil chamber.
- the said hydraulic shovel 1 denotes a hydraulic shovel and the basic construction is the same as that of the prior art such that the said hydraulic shovel 1 comprises various portions such as a crawler-type lower structure 2, an upper structure 3 which is rotatably supported on the said lower structure 2, a front attachment 4 mounted on the said upper structure 3 and the like, and furthermore, the said front attachment 4 comprises various members such as a boom 5 which is supported so as to be swingable up and down on the upper structure 3, a stick 6 which is supported so as to be swingable back and forth on the front end portion of the boom 5, a bucket 7 which is attached so as to be swingable back and forth on the front end portion of the stick 6 and the like.
- the said front attachment 4 comprises various members such as a boom 5 which is supported so as to be swingable up and down on the upper structure 3, a stick 6 which is supported so as to be swingable back and forth on the front end portion of the boom 5, a bucket 7 which is attached so as to be swingable back and forth on the front end portion of the stick 6
- a variety of tools such as a breaker 8, a clamshell (not illustrated) and the like can be attached on the front end portion of the stick 6 depending on the operations performed by the hydraulic shovel 1.
- Fig. 2 a pressure oil charging and discharging circuit of the said boom cylinder 10 is shown in Fig. 2 .
- 11 denotes a hydraulic pump
- 12 denotes an oil reservoir
- 13 is a control valve for the boom
- the control valve 13 comprises a 3-position selector valve provided with a first port 13a to be connected to the hydraulic pump 11, a second port 13b to be connected to the oil reservoir 12, a third port 13c to be connected to an oil chamber 10a on the rod side (cylinder contracting side) of the boom cylinder 10, a fourth port 13d to be connected to an oil chamber 10b on the head side (cylinder expanding side) of the boom cylinder 10 via a logic valve 14 (which will be described later), and pilot ports 13e and 13f on the expanding side and contracting side.
- 11 denotes a hydraulic pump
- 12 denotes an oil reservoir
- 13 is a control valve for the boom
- the control valve 13 comprises a 3-position selector valve provided with a first port 13a to be connected to the hydraulic pump
- the control valve 13 is located at a neutral position N where the first through fourth ports 13a through 13d are closed, however, when a pilot pressure is supplied to the expanding side pilot port 13e, the control valve 13 is switched to an expanding side position X where the valve passage from the first port 13a to the fourth port 13d and the valve passage from the third port 13c to the second port 13b are opened and pressure oil from the hydraulic pump 11 is supplied to the head side oil chamber 10b of the boom cylinder 10 via the logic valve 14, while oil discharged from the rod side oil chamber 10a is flowed toward the oil reservoir 12.
- the control valve 13 is switched to a contracting side position Y where the valve passage from the first port 13a to the third port 13c and the valve passage from the fourth port 13d to the second port 13b are opened and pressure oil from the hydraulic pump 11 is supplied to the rod side oil chamber 10a of the boom cylinder 10, while oil discharged from the head side oil chamber 10b is flowed toward the oil reservoir 12 via the logic valve 14.
- 15A and 15B denote pilot valves on the expanding side and contracting side, and by manipulating a boom operating lever 16 toward the boom rising side (cylinder expanding side) or the boom lowering side (cylinder contracting side), a pilot pressure is output from the pilot valve 15A or 15B on the side thus operated.
- the pilot pressure output from the expanding side pilot valve 15A is supplied to the expanding side pilot port 13e of the control valve 13.
- the pilot pressure output from the contracting side pilot valve 15B is supplied to the contracting side pilot port 13f of the control valve 13 via a first solenoid valve 17 (which will be described later) and also supplied to a pilot port 18a of a control valve 18 (which will be described later).
- the pilot pressure is outputted from the contracting side pilot valve 15B, the said pressure is detected by a pressure sensor 19.
- the first solenoid valve 17 is a 2-position selector valve and this is, in a condition where a solenoid 17a is not excited, located at the first position X where the pilot pressure output from the contracting side pilot valve 15B is supplied to the control valve contracting side pilot port 13f, however, when the solenoid 17a is excited based on a command from a control portion 20 (which will be described later), the first solenoid valve 17 is switched to the second position Y where the pilot pressure is not supplied to the control valve contracting side pilot port 13f.
- the control valve 18 is a 2-position selector valve provided with the pilot port 18a and the first through third ports 18b through 18d.
- the pilot port 18a is connected to the contracting side pilot valve 15B
- the first port 18b is connected to a first pilot port 14e of the logic valve 14 (which will be described later)
- the second port 18c is connected to a second pilot port 14h of the logic valve 14
- the third port 18d is connected to the oil reservoir 12.
- control valve 18 is located at a first position X where the valve passage which communicates the first port 18b to the second port 18c is opened and the third port 18d is closed when a pilot pressure is not supplied to the pilot port 18a, however, when a pilot pressure is supplied to the pilot port 18a, the control valve 18 is switched to a second position Y where the first port 18b is closed and the valve passage from the second port 18c to the third port 18d is opened.
- the logic valve 14 is constructed using a poppet 14a and provided with a first oil chamber 14c where a first port 14b is formed, a second oil chamber 14f where a second port 14d and the first pilot port 14e are formed, and a spring storage chamber 14i where a spring 14g is stored and the second pilot port 14h is formed.
- the first port 14b of the logic valve 14 is connected to the fourth port 13d of the control valve 13, the second port 14d is connected to the head side oil chamber 10b of the boom cylinder 10, the first pilot port 14e is, as mentioned before, connected to the first port 18b of the control valve 18, and the second pilot port 14h is connected to the second port 18c of the control valve 18. Also, the spring 14g is set so as to press the poppet 14a toward the closing position side (which will be described later).
- the logic valve 14 is structured so that, in a condition where the control valve 18 is located at the first position X, the pressure of the head side oil chamber 10b of the boom cylinder 10 is introduced in the spring storage chamber 14i via the second port 14d, the second oil chamber 14f, the first pilot port 14e, the control valve 18 at the first position X, and the second pilot port 14h, and the pressure introduced in the said spring storage chamber 14i acts as a force to press the poppet 14a toward the closing position side.
- the poppet 14a is structured so as to be movable to the closing position (the position of the poppet 14a of Fig. 2 ) where the valve passage 14k which communicates the first oil chamber 14c to the second oil chamber 14f is closed to prevent oil from entering or exiting from the boom cylinder head side oil chamber 10b and the opening position (the position of the poppet 14a of Figs. 3 and 4 .) where the valve passage 14k is opened and allows oil to enter or exit from the boom cylinder head side oil chamber 10b.
- the pressure introduced in the spring storage chamber 14i and a pressing force of the spring 14g are set so as to act as a force to press the poppet 14a toward the closing position side and the pressure inputted in the first oil chamber 14c and the second oil chamber 14f is set so as to act as a force to press the poppet 14a toward the opening position side.
- the poppet 14a is pressed by the total pressure (A + B) of the pressure A introduced in the spring storage chamber 14i and the pressing force B of the spring 14g toward the closing position side.
- the above-described total pressure (A + B) is set so as to be greater than the pressure C which is inputted from the boom cylinder head side oil chamber 10b into the second oil chamber 14f and presses the poppet 14a toward the opening position side (A + B > C) but smaller than the total pressure (C + D) of the said pressure C and the pressure D which is inputted from the hydraulic pump 11 via the control valve 13 at the expanding side position X into the first oil chamber 14c and presses the poppet 14a toward the opening position side (A + B ⁇ C + D).
- the poppet 14a is held at the closing position and prevents oil from being discharged from the boom cylinder head side oil chamber 10b as long as the pressure oil from the hydraulic pump 11 is not inputted into the first oil chamber 14c.
- the poppet 14a is located at the opening position.
- the poppet 14a is pressed toward the closing position side only by the pressing force B of the spring 14g, while the said pressing force B of the spring 14g is set so as to be smaller than the pressure C which is inputted from the boom cylinder head side oil chamber 10b into the second oil chamber 14f and presses the poppet 14a toward the opening position side (B ⁇ C).
- the poppet 14a is located at the opening position by the pressure of the boom cylinder head side oil chamber 10b.
- the logic valve 14 when the boom operating lever 16 is manipulated toward the lowering side or the rising side, the logic valve 14 is located at the opening side and allows oil to enter and exit from the boom cylinder head side oil chamber 10b, whereas when the boom operating lever 16 is not manipulated toward either the lowering side or the rising side, the logic valve 14 is held at the closing side and prevents oil from being discharged from the boom cylinder head side oil chamber 10b.
- the logic valve 14 and the control valve 18 are directly mounted on the boom cylinder 10 as one valve unit for preventing empty weight-lowering.
- a lowering side oil discharging passage E leading to the oil reservoir 12 is formed by branching off from the oil passage which couples the control valve fourth port 13d with the logic valve first port 14b.
- a second solenoid valve 21 (which will be described later) is disposed on the said lowering side oil passage E.
- a rising side oil discharging passage F leading to the oil reservoir 12 is formed by branching off from the oil passage which couples the control valve third port 13c with the boom cylinder rod side oil chamber 10a.
- a third solenoid valve 22 (which will be described later) is disposed on the said rising side discharging oil passage F.
- the second solenoid valve 21 and the third solenoid valve 22 are 2-position selector valves and these are, in a condition where solenoids 21 a and 22a are not excited, located at the closing position X where the lowering side discharging oil passage E and the rising side discharging oil passage F are respectively closed, however, when the solenoids 21a and 22a are excited based on commands from a control unit 20, the second solenoid valve 21 and the third solenoid valve 22 are switched to the opening position Y where the lowering side discharging oil passage E and the rising side discharging oil passage F are respectively opened.
- the oil discharged from the boom cylinder head side oil chamber 10b via the logic valve 14 at the opening side can be flowed to the oil reservoir 12 via the lowering side oil discharging passage E
- the oil discharged from the boom cylinder rod side oil chamber 10a can be flowed to the oil reservoir 12 via the rising side oil discharging passage F.
- control unit 20 is constructed using a microcomputer and the like, wherein signals from the pressure sensor 19 and a mode selector switch 23 (which will be described later) are inputted and based on the said input signal, solenoid exciting control signals are outputted to the first through third solenoid valves 17, 21, and 22.
- the mode selector switch 23 is provided on the operator's seat portion of the hydraulic shovel 1 and can select and set from three modes of "normal mode” for performing normal operations such as excavation and loading and the like, "lowering hold releasing mode” for performing operations to crush stones and the like by means of the breaker 8, and "lowering and rising hold releasing mode” for performing operations to move the bucket 7 back and forth along the ground and the like.
- the control unit 20 When the mode selector switch 23 is set to the "normal mode", the control unit 20 does not output the solenoid exiting signals to the first, second, and third solenoid valves 17, 21, and 22. Accordingly, the first solenoid valve 17 is located at the first position X where the pilot pressure output from the contracting side pilot port 15B is supplied to the control valve contracting side pilot port 13f. Also, the second solenoid valve 21 and the third solenoid valve 22 are located at the closing position X where the lowering side oil discharging passage E and the rising side oil discharging passage F are respectively closed.
- a pilot pressure is output from the contracting side pilot valve 15B.
- the said pilot pressure is supplied via the first solenoid valve 17 at the first position X to the control valve contracting side pilot port 13f and switches the control valve 13 to the contracting side position Y, while the said pilot pressure is supplied to the pilot port 18a of the control valve 18 and switches the control valve 18 to the second position Y.
- the pressure oil output from the hydraulic pump 11 is supplied via the control valve 13 at the contracting side position Y to the boom cylinder rod side oil chamber 10a.
- the oil of the boom cylinder head side oil chamber 10b is discharged via the logic valve 14 at the opening position and the control valve 13 at the contracting side position Y to the oil reservoir 12, thus the boom cylinder 10 contracts and the boom 5 moves down.
- the control unit 20 outputs the solenoid exciting signal to the first solenoid valve 17. Accordingly, the first solenoid valve 17 is switched to the second position Y where the pilot pressure output from the contracting side pilot valve 15B is not supplied to the control valve contracting side pilot port 13f.
- the control unit 20 further outputs a solenoid exciting signal to the second solenoid valve 21, whereby the second solenoid valve 21 is switched to the opening side Y where the lowering side oil discharging passage E is opened.
- a solenoid exciting signal is not outputted to the third solenoid valve 22, the said third solenoid valve 22 is held at the closing position X where the rising side oil discharging passage F is closed.
- a pilot pressure output from the contracting side pilot valve 15B is supplied to the pilot port 18a of the control valve 18 and switches the control valve 18 to the second position Y, and based on the detection of the output of the said pilot pressure by the pressure sensor 19, a solenoid exciting signal is output to the second solenoid valve 21 from the control portion 20, whereby the second solenoid valve 21 is switched to the opening position Y where the lowering side oil discharging passage E is opened.
- the control unit 20 outputs the solenoid exciting signals to the first solenoid valve 17 and the third solenoid valve 22. Accordingly, the first solenoid valve 17 is switched to the second position Y where the pilot pressure output from the contracting side pilot valve 15B is not supplied to the control valve contracting side pilot port 13f.
- the third solenoid valve 22 is switched to the opening position Y where the rising side oil discharging passage F is opened.
- control unit 20 When the output of the pilot pressure from the contracting side pilot valve 15B is detected by the pressure sensor 19, the control unit 20 further outputs the solenoid exciting signal to the second solenoid valve 21, whereby the second solenoid valve 21 is switched to the opening position Y where the lowering side oil discharging passage E is opened.
- the oil of the boom cylinder rod side oil chamber 10a is discharged to the oil reservoir 12 via the control valve 13 at the expanding side position X or the third solenoid valve 22 at the opening position Y, thus the boom cylinder 10 expands and the boom 5 moves up.
- the mode selector switch 23 when normal operations such as excavation and loading and the like are performed, the mode selector switch 23 is set to the "normal mode". Accordingly, as mentioned before, a pressure oil is supplied to the boom cylinder 10 based on manipulations of the boom operating lever 16. On the other hand, since both rising side oil discharging passage E and lowering side oil discharge passage F are closed, the boom 5 does not move up and down due to the external force, thus normal up and down movements of the boom 5 can be performed based on the manipulations of the boom operation lever 16.
- the mode selector switch 23 When operations to crush stones and the like are performed by means of the breaker 8, the mode selector switch 23 is set to the "lowering hold releasing mode". In this condition, when the boom operating lever 16 is manipulated toward the lowering side, the control valve 13 is held at the neutral position N, while the lowering side oil discharging passage F is opened. The boom 5 moves down due to the empty weight of the front attachment 4. Thus, the breaker 8 is pressed downward by the empty weight of the front attachment 4 and can obtain a thrust that is required in the stone crushing operations. Moreover, at this time, the rising side oil discharging passage E is closed and upward movement is restricted, the reaction force is not lost and effective breaker operations can be performed.
- the mode selector switch 23 is set to the "lowering and rising hold releasing mode".
- the control valve 13 is held at the neutral position N, while the rising side oil discharging passage E and the lowering side oil discharging passage F are opened.
- the boom 5 moves up due to the external force and moves down due to the empty weight of the front attachment 4.
- the boom 5 automatically moves up due to the reaction force that the bucket 7 receives from the ground and also automatically moves down due to the empty weight of the front attachment 4.
- the bucket 7 can be moved in the back and forth direction along the ground without performing operations to move the boom 5 up and down.
- the boom operating lever 16 is manipulated toward the lowering side.
- the boom 5 moves down until the front end portion of the clamshell is brought into contact with the objects due to the empty weight of the front attachment 4 and when the front end portion of the clamshell is brought into contact with the objects, the boom 5 automatically stops moving down.
- the boom 5 can be easily operated and operability is improved.
- a pressure oil is not supplied from the hydraulic pump 11 to the boom cylinder 10, thus contributing to a reduction in fuel consumption.
- the downward movement due to the empty weight of the boom 5 is allowed only when the mode selector switch 23 is set to the "lowering hold releasing mode” or “lowering and rising hold releasing mode” and the boom operating lever 16 is manipulated toward the lowering side, therefore there is an advantage in that an inconvenience such that the boom 5 unexpectedly moves down due to the empty weight against the operator's intentions is avoidable.
- the present invention by constructing as such, when the lower side oil discharging passage of a working machine such as a hydraulic shovel is opened, an oil discharge from the head side oil chamber of the boom cylinder is allowed and the boom moves down due to the empty weight.
- a working machine such as a hydraulic shovel
- an oil discharge from the head side oil chamber of the boom cylinder is allowed and the boom moves down due to the empty weight.
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Description
- The present invention belongs to the technical field of a boom cylinder control circuit of an operation machine such as a hydraulic shovel.
- In general, as operation machines such as hydraulic shovels and the like, there is one wherein a stick is supported so as to be swingable back and forth on the front end portion of a boom whose base end portion is supported so as to be swingable up and down on the machine main body and a tool such as a bucket, a breaker, a clamshell or the like is attached on the front end portion of the said stick. In such a working machine, for example as shown in
Fig. 5 , when removing operations of rocks lying on flat ground are performed by moving abucket 7 back and forth along the ground, in addition to manipulations of thestick 6, manipulations of aboom 5 are performed simultaneously in order to move the boom up and down. Also, as shown inFig. 6 , when rock crushing operations are performed by means of abreaker 8, it is necessary to manipulate theboom 5 toward the lowering side and press thebreaker 8 against rocks, and perform the operations so as to always apply an appropriate thrust to thebreaker 8. In addition, when operations to scoop up objects are operated by means of a clamshell, the boom is lowered until the clamshell makes contact with the objects. - However, in the aforementioned operations to move the bucket in the back and forth direction along the ground, if the stick operations and the boom operations are not performed simultaneously and appropriately, the bucket front end bites into the ground or lifts off the ground and work efficiency lowers. Also, in the breaker operations, if a force to press the boom downward is too great, the machine body is lifted and operations cannot be easily performed, and if a force to press the boom downward is too small, a necessary thrust cannot be obtained, therefore finding the proper balance thereof is difficult. Furthermore, in the operations using the clamshell, it is necessary to stop the boom lowering operation upon recognition that the clamshell makes contact with the object to be scooped up. Therefore, during these operations, close attention must be paid to boom manipulations at all times, manipulations are complicated and an operator's fatigue increases. In addition, with the boom operations, pressure oil is supplied to the boom cylinder, therefore fuel consumption increases and fuel efficiency is poor. Herein there are problems to be solved by the present invention.
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JP-09 132927A DE 19932948A andFR-A-2537184 - According to
claim 1 there is provided a boom cylinder control circuit of a working machine having a boom cylinder for moving a boom up and down, said control circuit of the boom cylinder comprising; a control valve which performs pressure oil supplying and discharging control with respect to the boom cylinder based on manipulations of an operating member and instructions from a control unit; a lowering side oil discharging passage which allows oil of a boom cylinder head side oil chamber to flow toward the oil reservoir side without passing through the control valve; and a lowering side control means which performs opening and closing control of the lowering side oil discharging passage based on the instructions from the control unit, characterized in that a mode selector switch is connected to the control unit permitting selection of a normal mode and a lowering hold releasing mode, wherein when the normal mode is selected by the mode selector switch the lowering side control means is controlled so as to close the lowering side oil discharging passage based on the instructions from the control unit and the control valve is controlled so as to supply the pressure oil to the boom cylinder in accordance with the manipulations of the operating member and when the lowering hold releasing mode is selected and the operating member is operated toward the boom lowering side the lowering side control means is controlled so as to open the lowering side oil discharging passage and the control valve is controlled so as not to supply the pressure oil to the boom cylinder, based on the instructions from the control unit. - When the lower side oil discharging passage is opened, discharge oil from the head side oil chamber of the boom cylinder is allowed and the boom moves down due tot the empty weight. For example, when stone crushing operations are performed by means of the breaker, boom operations become easy and fuel consumption can be reduced.
- The control circuit according to
claim 2 includes a rising side oil discharge passage which allows oil of a boom cylinder rod side oil chamber to flow toward the oil reservoir side without passing through the control valve and a rising side control means which performs opening and closing control of the rising side oil discharging passage, the mode selector switch permitting the selection of a lowering and rising hold releasing mode, wherein when the lowering and rising hold releasing mode is selected by the mode selector switch and the operating member is operated toward the boom rising side, the lowering side control means is controlled so as to close the lowering side oil discharging passage and the rising side control means is controlled so as to open the rising side oil discharging passage, based on the instructions from the control unit and the control valve is controlled so as to supply the pressure oil to the rising side of the boom cylinder in accordance with the manipulations of the operating member, and wherein when the lowering and rising hold releasing mode is selected by the mode selector switch and the operating member is operated toward the boom lowering side, the lowering side control means and the rising side control means open their discharging passages and the control valve is controlled so as not to supply the pressure oil to the boom cylinder, based on the instructions of the control unit. For example, operations to move the bucket in the back and forth direction along the ground are performed, boom operations become easy and fuel consumption can be reduced. - In embodiments in accordance with the invention the lowering side oil discharging passage is controlled so as to be opened based on a manipulation of the operating member toward the boom lowering side and on the other hand, when the said lowering side oil discharging passage is open, the lowering side oil discharging passage is controlled so that, even by operating the operating member toward the boom lowering side, the pressure oil is not supplied from the control valve to the boom cylinder, whereby it is avoidable that the boom unexpectedly moves down due to the empty weight without an operator's intentions.
- The control means which performs opening and closing control of the lowering side oil discharging passage and the rising side oil discharging passage can comprise solenoid valves which can be switched between the opening position to open the oil discharging passage and closing position to close the oil discharging passage.
- The control circuit may include valves for preventing empty weight-lowering which, when the operating member is not manipulated toward the boom lowering side, prevent oil from being discharged from the boom cylinder head side oil chamber, but, based on a manipulation toward the boom lowering side, allow oil to be discharged from the head side oil chamber.
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Fig. 1 is a side view of the hydraulic shovel. -
Fig. 2 is a hydraulic circuit diagram of the boom cylinder. -
Fig. 3 is a hydraulic circuit diagram of the boom cylinder when a manipulation toward the boom lowering side is performed in a condition where a "lowering hold release mode" is set. -
Fig. 4 is a hydraulic circuit diagram of the boom cylinder when a manipulation toward the boom lowering side is performed in a condition where a "lowering and rising hold releasing mode" is set. -
Fig. 5 is a view showing rock removing operations on flat ground by a bucket. -
Fig. 6 is a view showing stone crushing operations by a breaker. - Now, an embodiment of the invention will be described with reference to the drawings. In the drawings, 1 denotes a hydraulic shovel and the basic construction is the same as that of the prior art such that the said
hydraulic shovel 1 comprises various portions such as a crawler-typelower structure 2, anupper structure 3 which is rotatably supported on the saidlower structure 2, afront attachment 4 mounted on the saidupper structure 3 and the like, and furthermore, the saidfront attachment 4 comprises various members such as aboom 5 which is supported so as to be swingable up and down on theupper structure 3, astick 6 which is supported so as to be swingable back and forth on the front end portion of theboom 5, abucket 7 which is attached so as to be swingable back and forth on the front end portion of thestick 6 and the like. - Instead of the
bucket 7, a variety of tools such as abreaker 8, a clamshell (not illustrated) and the like can be attached on the front end portion of thestick 6 depending on the operations performed by thehydraulic shovel 1. - 10 denotes a boom cylinder to swing the
boom 5 up and down and a pressure oil charging and discharging circuit of the saidboom cylinder 10 is shown inFig. 2 . InFig. 2 , 11 denotes a hydraulic pump, 12 denotes an oil reservoir, 13 is a control valve for the boom, and thecontrol valve 13 comprises a 3-position selector valve provided with afirst port 13a to be connected to thehydraulic pump 11, asecond port 13b to be connected to theoil reservoir 12, athird port 13c to be connected to anoil chamber 10a on the rod side (cylinder contracting side) of theboom cylinder 10, afourth port 13d to be connected to anoil chamber 10b on the head side (cylinder expanding side) of theboom cylinder 10 via a logic valve 14 (which will be described later), andpilot ports - Then, in a condition where a pilot pressure is not supplied to either of the
pilot ports control valve 13 is located at a neutral position N where the first throughfourth ports 13a through 13d are closed, however, when a pilot pressure is supplied to the expandingside pilot port 13e, thecontrol valve 13 is switched to an expanding side position X where the valve passage from thefirst port 13a to thefourth port 13d and the valve passage from thethird port 13c to thesecond port 13b are opened and pressure oil from thehydraulic pump 11 is supplied to the headside oil chamber 10b of theboom cylinder 10 via thelogic valve 14, while oil discharged from the rodside oil chamber 10a is flowed toward theoil reservoir 12. In addition, when a pilot pressure is supplied to the contractingside pilot port 13f, thecontrol valve 13 is switched to a contracting side position Y where the valve passage from thefirst port 13a to thethird port 13c and the valve passage from thefourth port 13d to thesecond port 13b are opened and pressure oil from thehydraulic pump 11 is supplied to the rodside oil chamber 10a of theboom cylinder 10, while oil discharged from the headside oil chamber 10b is flowed toward theoil reservoir 12 via thelogic valve 14. - 15A and 15B denote pilot valves on the expanding side and contracting side, and by manipulating a
boom operating lever 16 toward the boom rising side (cylinder expanding side) or the boom lowering side (cylinder contracting side), a pilot pressure is output from thepilot valve - Then, the pilot pressure output from the expanding
side pilot valve 15A is supplied to the expandingside pilot port 13e of thecontrol valve 13. In addition, the pilot pressure output from the contractingside pilot valve 15B is supplied to the contractingside pilot port 13f of thecontrol valve 13 via a first solenoid valve 17 (which will be described later) and also supplied to apilot port 18a of a control valve 18 (which will be described later). Furthermore, when the pilot pressure is outputted from the contractingside pilot valve 15B, the said pressure is detected by apressure sensor 19. - The
first solenoid valve 17 is a 2-position selector valve and this is, in a condition where asolenoid 17a is not excited, located at the first position X where the pilot pressure output from the contractingside pilot valve 15B is supplied to the control valve contractingside pilot port 13f, however, when thesolenoid 17a is excited based on a command from a control portion 20 (which will be described later), thefirst solenoid valve 17 is switched to the second position Y where the pilot pressure is not supplied to the control valve contractingside pilot port 13f. - The
control valve 18 is a 2-position selector valve provided with thepilot port 18a and the first throughthird ports 18b through 18d. As mentioned before, thepilot port 18a is connected to the contractingside pilot valve 15B, thefirst port 18b is connected to afirst pilot port 14e of the logic valve 14 (which will be described later), thesecond port 18c is connected to asecond pilot port 14h of thelogic valve 14, and thethird port 18d is connected to theoil reservoir 12. - Then, the
control valve 18 is located at a first position X where the valve passage which communicates thefirst port 18b to thesecond port 18c is opened and thethird port 18d is closed when a pilot pressure is not supplied to thepilot port 18a, however, when a pilot pressure is supplied to thepilot port 18a, thecontrol valve 18 is switched to a second position Y where thefirst port 18b is closed and the valve passage from thesecond port 18c to thethird port 18d is opened. - On the other hand, the
logic valve 14 is constructed using apoppet 14a and provided with afirst oil chamber 14c where afirst port 14b is formed, asecond oil chamber 14f where asecond port 14d and thefirst pilot port 14e are formed, and aspring storage chamber 14i where aspring 14g is stored and thesecond pilot port 14h is formed. - The
first port 14b of thelogic valve 14 is connected to thefourth port 13d of thecontrol valve 13, thesecond port 14d is connected to the headside oil chamber 10b of theboom cylinder 10, thefirst pilot port 14e is, as mentioned before, connected to thefirst port 18b of thecontrol valve 18, and thesecond pilot port 14h is connected to thesecond port 18c of thecontrol valve 18. Also, thespring 14g is set so as to press thepoppet 14a toward the closing position side (which will be described later). - The
logic valve 14 is structured so that, in a condition where thecontrol valve 18 is located at the first position X, the pressure of the headside oil chamber 10b of theboom cylinder 10 is introduced in thespring storage chamber 14i via thesecond port 14d, thesecond oil chamber 14f, thefirst pilot port 14e, thecontrol valve 18 at the first position X, and thesecond pilot port 14h, and the pressure introduced in the saidspring storage chamber 14i acts as a force to press thepoppet 14a toward the closing position side. On the other hand, in a condition where thecontrol valve 18 is located at the second position Y, the pressure of the boom cylinderhead oil chamber 10b is not introduced in thespring storage chamber 14i and the oil of thespring storage chamber 14i is flowed toward theoil reservoir 12 via thecontrol valve 18 at the second position Y. - The
poppet 14a is structured so as to be movable to the closing position (the position of thepoppet 14a ofFig. 2 ) where thevalve passage 14k which communicates thefirst oil chamber 14c to thesecond oil chamber 14f is closed to prevent oil from entering or exiting from the boom cylinder headside oil chamber 10b and the opening position (the position of thepoppet 14a ofFigs. 3 and4 .) where thevalve passage 14k is opened and allows oil to enter or exit from the boom cylinder headside oil chamber 10b. Herein, as mentioned before, the pressure introduced in thespring storage chamber 14i and a pressing force of thespring 14g are set so as to act as a force to press thepoppet 14a toward the closing position side and the pressure inputted in thefirst oil chamber 14c and thesecond oil chamber 14f is set so as to act as a force to press thepoppet 14a toward the opening position side. - In the condition where the
control valve 18 is located at the first position X, thepoppet 14a is pressed by the total pressure (A + B) of the pressure A introduced in thespring storage chamber 14i and the pressing force B of thespring 14g toward the closing position side. The above-described total pressure (A + B) is set so as to be greater than the pressure C which is inputted from the boom cylinder headside oil chamber 10b into thesecond oil chamber 14f and presses thepoppet 14a toward the opening position side (A + B > C) but smaller than the total pressure (C + D) of the said pressure C and the pressure D which is inputted from thehydraulic pump 11 via thecontrol valve 13 at the expanding side position X into thefirst oil chamber 14c and presses thepoppet 14a toward the opening position side (A + B < C + D). Thus, in the condition where thecontrol valve 18 is located at the first position X, that is, when theboom operating lever 16 is not manipulated toward the boom lowering side, thepoppet 14a is held at the closing position and prevents oil from being discharged from the boom cylinder headside oil chamber 10b as long as the pressure oil from thehydraulic pump 11 is not inputted into thefirst oil chamber 14c. On the other hand, when theboom operating lever 16 is manipulated toward the boom rising side, the pressure oil from thehydraulic pump 11 is inputted into thefirst oil chamber 14c, and thepoppet 14a is located at the opening position. - In addition, in the condition where the
control valve 18 is located at the second position Y, thepoppet 14a is pressed toward the closing position side only by the pressing force B of thespring 14g, while the said pressing force B of thespring 14g is set so as to be smaller than the pressure C which is inputted from the boom cylinder headside oil chamber 10b into thesecond oil chamber 14f and presses thepoppet 14a toward the opening position side (B < C). Thus, in the condition where thecontrol valve 18 is located at the second position Y, that is, when theboom operating lever 16 is manipulated toward the boom lowering side, thepoppet 14a is located at the opening position by the pressure of the boom cylinder headside oil chamber 10b. - Namely, when the
boom operating lever 16 is manipulated toward the lowering side or the rising side, thelogic valve 14 is located at the opening side and allows oil to enter and exit from the boom cylinder headside oil chamber 10b, whereas when theboom operating lever 16 is not manipulated toward either the lowering side or the rising side, thelogic valve 14 is held at the closing side and prevents oil from being discharged from the boom cylinder headside oil chamber 10b. Thus, for example, even when an incident such as a leakage occurs in a pipe from thecontrol valve 13 to theboom cylinder 10, theboom 5 is prevented from lowering due to the empty weight of thefront attachment 4. Herein, thelogic valve 14 and thecontrol valve 18 are directly mounted on theboom cylinder 10 as one valve unit for preventing empty weight-lowering. - On the other hand, a lowering side oil discharging passage E leading to the
oil reservoir 12 is formed by branching off from the oil passage which couples the control valvefourth port 13d with the logic valvefirst port 14b. A second solenoid valve 21 (which will be described later) is disposed on the said lowering side oil passage E. Also, a rising side oil discharging passage F leading to theoil reservoir 12 is formed by branching off from the oil passage which couples the control valvethird port 13c with the boom cylinder rodside oil chamber 10a. A third solenoid valve 22 (which will be described later) is disposed on the said rising side discharging oil passage F. - The
second solenoid valve 21 and thethird solenoid valve 22 are 2-position selector valves and these are, in a condition wheresolenoids solenoids control unit 20, thesecond solenoid valve 21 and thethird solenoid valve 22 are switched to the opening position Y where the lowering side discharging oil passage E and the rising side discharging oil passage F are respectively opened. Then, in the condition where thesecond solenoid valve 21 is located at the opening position Y, the oil discharged from the boom cylinder headside oil chamber 10b via thelogic valve 14 at the opening side can be flowed to theoil reservoir 12 via the lowering side oil discharging passage E, and in the condition where thethird solenoid valve 22 is located at the opening position Y, the oil discharged from the boom cylinder rodside oil chamber 10a can be flowed to theoil reservoir 12 via the rising side oil discharging passage F. - On the other hand, the
control unit 20 is constructed using a microcomputer and the like, wherein signals from thepressure sensor 19 and a mode selector switch 23 (which will be described later) are inputted and based on the said input signal, solenoid exciting control signals are outputted to the first throughthird solenoid valves - The
mode selector switch 23 is provided on the operator's seat portion of thehydraulic shovel 1 and can select and set from three modes of "normal mode" for performing normal operations such as excavation and loading and the like, "lowering hold releasing mode" for performing operations to crush stones and the like by means of thebreaker 8, and "lowering and rising hold releasing mode" for performing operations to move thebucket 7 back and forth along the ground and the like. - When the
mode selector switch 23 is set to the "normal mode", thecontrol unit 20 does not output the solenoid exiting signals to the first, second, andthird solenoid valves first solenoid valve 17 is located at the first position X where the pilot pressure output from the contractingside pilot port 15B is supplied to the control valve contractingside pilot port 13f. Also, thesecond solenoid valve 21 and thethird solenoid valve 22 are located at the closing position X where the lowering side oil discharging passage E and the rising side oil discharging passage F are respectively closed. - In the "normal mode", when the
boom operating lever 16 is not manipulated toward either rising side or lowering side, a pilot pressure is not output from either of thepilot valves control valve 13 is located at the neutral position N, and thecontrol valve 18 is located at the first position X. In this condition, theboom cylinder 10 is halted, and in addition, since the oil discharging passages from the rodside oil chamber 10a and headside oil chamber 10b of theboom cylinder 10 to theoil reservoir 12 are closed by the third andsecond solenoid valves control valve 13 at the neutral position N, oil is not discharged from either of theoil chambers boom 5, theboom cylinder 10 does not contract. - On the other hand, in the "normal mode", when the
boom operating lever 16 is manipulated toward the rising side, thecontrol valve 13 is switched to the expanding side position X due to the pilot pressure output from the expandingside pilot valve 15A. Accordingly, the pressure oil output from thehydraulic pump 11 is supplied via thelogic valve 14 at the opening position to the boom cylinder headside oil chamber 10b. Also, the oil of the boom cylinder roadside oil chamber 10a is discharged via thecontrol valve 13 at the expanding side position X to theoil reservoir 12, thus theboom cylinder 10 expands and theboom 5 moves up. - In the "normal mode", when the
boom operating lever 16 is manipulated toward the lowering side, a pilot pressure is output from the contractingside pilot valve 15B. The said pilot pressure is supplied via thefirst solenoid valve 17 at the first position X to the control valve contractingside pilot port 13f and switches thecontrol valve 13 to the contracting side position Y, while the said pilot pressure is supplied to thepilot port 18a of thecontrol valve 18 and switches thecontrol valve 18 to the second position Y. Accordingly, the pressure oil output from thehydraulic pump 11 is supplied via thecontrol valve 13 at the contracting side position Y to the boom cylinder rodside oil chamber 10a. Also, the oil of the boom cylinder headside oil chamber 10b is discharged via thelogic valve 14 at the opening position and thecontrol valve 13 at the contracting side position Y to theoil reservoir 12, thus theboom cylinder 10 contracts and theboom 5 moves down. - On the other hand, when the
mode selector switch 23 is set to the "lowering hold releasing mode", thecontrol unit 20 outputs the solenoid exciting signal to thefirst solenoid valve 17. Accordingly, thefirst solenoid valve 17 is switched to the second position Y where the pilot pressure output from the contractingside pilot valve 15B is not supplied to the control valve contractingside pilot port 13f. When the output of the pilot pressure from the contractingside pilot valve 15B is detected by thepressure sensor 19, thecontrol unit 20 further outputs a solenoid exciting signal to thesecond solenoid valve 21, whereby thesecond solenoid valve 21 is switched to the opening side Y where the lowering side oil discharging passage E is opened. On the other hand, when a solenoid exciting signal is not outputted to thethird solenoid valve 22, the saidthird solenoid valve 22 is held at the closing position X where the rising side oil discharging passage F is closed. - In the "lowering hold releasing mode", when the
boom operating lever 16 is not manipulated toward either rising side or lowering side, thecontrol valve 13 is located at the neutral position N, and thecontrol valve 18 is located at the first position X. In this condition, similar to the aforementioned "normal mode", theboom cylinder 10 is halted, and even when an external force toward the lowering side or the rising side is applied to theboom 5, theboom cylinder 10 never contracts. - In addition, in the "lowering hold releasing mode", when the
boom operating lever 16 is manipulated toward the rising side, similar to the aforementioned "normal mode", the pressure oil of thehydraulic pump 11 is supplied via thecontrol valve 13 at the expanding side position X and thelogic valve 14 at the opening position to the boom cylinder headside oil chamber 10b. In this case, since the output of the pilot pressure is not detected by thepressure sensor 19, thesecond solenoid valve 21 is positioned at the opening side X where the lowering side oil discharging passage E is closed, therefore the pressure oil of thehydraulic pump 11 is not discharged to theoil reservoir 12 via the lowering side oil discharging passage E. On the other hand, the oil of the boom cylinder rodside oil chamber 10a is discharged to theoil reservoir 12 via thecontrol valve 13 at the expanding side X, thus theboom cylinder 10 expands and theboom 5 moves up. - Furthermore, in the "lowering hold releasing mode", when the
boom operating lever 16 is manipulated toward the lowering side, a pilot pressure is output from the contractingside pilot valve 15B, however, since thefirst solenoid valve 17 is located at the second position Y, the said pilot pressure is not supplied to the control valve contractingside pilot port 13f and thecontrol valve 13 is held at the neutral position N. On the other hand, a pilot pressure output from the contractingside pilot valve 15B is supplied to thepilot port 18a of thecontrol valve 18 and switches thecontrol valve 18 to the second position Y, and based on the detection of the output of the said pilot pressure by thepressure sensor 19, a solenoid exciting signal is output to thesecond solenoid valve 21 from thecontrol portion 20, whereby thesecond solenoid valve 21 is switched to the opening position Y where the lowering side oil discharging passage E is opened. - Namely, when the
boom operating lever 16 is manipulated toward the lowering side in the "lowering hold releasing mode", thecontrol valve 13 is located at the neutral position N and the pressure oil from thehydraulic pump 11 is not supplied to theboom cylinder 10, however, the oil of the boom cylinder headside oil chamber 10b is flowed via thelogic valve 14 at the opening position and thesecond solenoid valve 21 at the opening position Y to theoil reservoir 12. In this condition, theboom 5 lowers due to the empty weight of thefront attachment 4 until a tool such as abreaker 8 or the like is brought into contact with an obstruction and the lowering movement is restricted. Also, at this time, even when an external force toward the rising side is applied to theboom 5, the oil discharging passage from the boom cylinder rodside oil chamber 10a to theoil reservoir 12 is closed by thecontrol valve 13 at the neutral position N and thethird solenoid valve 22 at the closing position X, therefore oil is not discharged from the boom cylinder rodside oil chamber 10a, thus theboom 5 never moves up due to the external force. - On the other hand, when the
mode selector switch 23 is set to the "lowering and rising hold releasing mode", thecontrol unit 20 outputs the solenoid exciting signals to thefirst solenoid valve 17 and thethird solenoid valve 22. Accordingly, thefirst solenoid valve 17 is switched to the second position Y where the pilot pressure output from the contractingside pilot valve 15B is not supplied to the control valve contractingside pilot port 13f. Thethird solenoid valve 22 is switched to the opening position Y where the rising side oil discharging passage F is opened. When the output of the pilot pressure from the contractingside pilot valve 15B is detected by thepressure sensor 19, thecontrol unit 20 further outputs the solenoid exciting signal to thesecond solenoid valve 21, whereby thesecond solenoid valve 21 is switched to the opening position Y where the lowering side oil discharging passage E is opened. - In the "lowering and rising hold releasing mode", when the
boom operating lever 16 is not manipulated toward either rising side or lowering side, thecontrol valve 13 is located at the neutral position N, and thecontrol valve 18 is located at the first position X. In this condition, the pressure oil from thehydraulic pump 11 is not supplied to theboom cylinder 10, while the oil from the boom cylinder rodside oil chamber 10a is flowed via thethird solenoid valve 22 at the opening position Y to theoil reservoir 12, and when an external force toward the rising side is applied to theboom 5, theboom 5 moves up. On the other hand, since the oil discharging passage of the oil from the boom cylinder headside oil chamber 10b to theoil reservoir 12 is closed by thesecond solenoid vale 21 at the closing position X and thecontrol valve 13 at the neutral position N, the oil is not discharged from the boom cylinderhead side chamber 10b and theboom 5 never lowers due to the empty weight of thefront attachment 4. - In addition, in the "lowering and rising hold releasing mode", when the
boom operating lever 16 is manipulated toward the rising side, the pressure oil of thehydraulic pump 11 is supplied via thecontrol valve 13 at the expanding side position X and thelogic valve 14 at the opening position to the boom cylinder headside oil chamber 10b. In this case, since the output of the pilot pressure is not detected by thepressure sensor 19, thesecond solenoid valve 21 is positioned at the closing side X where the lowering side oil discharging passage E is closed, therefore the pressure oil of thehydraulic pump 11 is not discharged to theoil reservoir 12 via the lowering side oil discharging passage E. On the other hand, the oil of the boom cylinder rodside oil chamber 10a is discharged to theoil reservoir 12 via thecontrol valve 13 at the expanding side position X or thethird solenoid valve 22 at the opening position Y, thus theboom cylinder 10 expands and theboom 5 moves up. - Furthermore, in the "lowering and rising hold releasing mode", when the
boom operating lever 16 is manipulated toward the lowering side, similar to the aforementioned "lowering hold releasing mode", thecontrol valve 13 is held at the neutral position N, thecontrol valve 18 is switched to the second position Y, and thesecond solenoid valve 21 is switched to the opening position Y where the lowering side oil discharging passage E is opened. - Namely, when the
boom operating lever 16 is manipulated toward the lowering side in the "lowering and rising hold releasing mode", the pressure oil from thehydraulic pump 11 is not supplied to theboom cylinder 10, while the oil of the boom cylinder headside oil chamber 10b is flowed via thelogic valve 14 at the opening position and thesecond solenoid valve 21 at the opening position Y to theoil reservoir 12, thus, theboom 5 lowers due to the empty weight of thefront attachment 4 until a tool such as thebreaker 8 or the like is brought into contact with an obstruction and the lowering movement is restricted. Also, at this time, since the oil of the boom cylinder rodside oil chamber 10a is flowed via thethird solenoid valve 22 at the opening position Y to theoil reservoir 12, when an external force toward the rising side is applied to theboom 5, theboom 5 moves up. - In the aforementioned construction, when normal operations such as excavation and loading and the like are performed, the
mode selector switch 23 is set to the "normal mode". Accordingly, as mentioned before, a pressure oil is supplied to theboom cylinder 10 based on manipulations of theboom operating lever 16. On the other hand, since both rising side oil discharging passage E and lowering side oil discharge passage F are closed, theboom 5 does not move up and down due to the external force, thus normal up and down movements of theboom 5 can be performed based on the manipulations of theboom operation lever 16. - When operations to crush stones and the like are performed by means of the
breaker 8, themode selector switch 23 is set to the "lowering hold releasing mode". In this condition, when theboom operating lever 16 is manipulated toward the lowering side, thecontrol valve 13 is held at the neutral position N, while the lowering side oil discharging passage F is opened. Theboom 5 moves down due to the empty weight of thefront attachment 4. Thus, thebreaker 8 is pressed downward by the empty weight of thefront attachment 4 and can obtain a thrust that is required in the stone crushing operations. Moreover, at this time, the rising side oil discharging passage E is closed and upward movement is restricted, the reaction force is not lost and effective breaker operations can be performed. - Furthermore, when operations to remove rocks lying on flat ground are performed by moving the
bucket 7 back and forth along the ground, themode selector switch 23 is set to the "lowering and rising hold releasing mode". In this condition, when theboom operating lever 16 is manipulated toward the lowering side, thecontrol valve 13 is held at the neutral position N, while the rising side oil discharging passage E and the lowering side oil discharging passage F are opened. Theboom 5 moves up due to the external force and moves down due to the empty weight of thefront attachment 4. Namely, in a condition where thebucket 7 is in contact with the ground, when thestick 6 is moved in the back and forth direction, theboom 5 automatically moves up due to the reaction force that thebucket 7 receives from the ground and also automatically moves down due to the empty weight of thefront attachment 4. Thebucket 7 can be moved in the back and forth direction along the ground without performing operations to move theboom 5 up and down. - Furthermore, when operations to scoop up objects with a clamshell are performed, in a condition where the mode selector switch is set to the "lowering hold releasing mode" or "lowering and rising hold releasing mode", the
boom operating lever 16 is manipulated toward the lowering side. Theboom 5 moves down until the front end portion of the clamshell is brought into contact with the objects due to the empty weight of thefront attachment 4 and when the front end portion of the clamshell is brought into contact with the objects, theboom 5 automatically stops moving down. - According to the embodiment carried out in such a manner, by selecting a mode using the
mode selector switch 23, it becomes possible to move theboom 5 downward with the empty weight or upward with the external force applied to theboom 5. When stones are crushed by thebreaker 8, rocks are removed by thebucket 7 on flat ground, or objects are scooped by the clamshell, theboom 5 can be easily operated and operability is improved. In addition, in this case, a pressure oil is not supplied from thehydraulic pump 11 to theboom cylinder 10, thus contributing to a reduction in fuel consumption. - Further herein, the downward movement due to the empty weight of the
boom 5 is allowed only when themode selector switch 23 is set to the "lowering hold releasing mode" or "lowering and rising hold releasing mode" and theboom operating lever 16 is manipulated toward the lowering side, therefore there is an advantage in that an inconvenience such that theboom 5 unexpectedly moves down due to the empty weight against the operator's intentions is avoidable. - According to the present invention, by constructing as such, when the lower side oil discharging passage of a working machine such as a hydraulic shovel is opened, an oil discharge from the head side oil chamber of the boom cylinder is allowed and the boom moves down due to the empty weight. For example, when stone crushing operations are performed by means of a breaker, there is an industrial applicability in that boom operations become easy and fuel consumption can be reduced.
Claims (3)
- A boom cylinder control circuit of a working machine having a boom cylinder (10) for moving a boom (5) up and down, said control circuit of the boom cylinder (10) comprising;
a control valve(13) which performs pressure oil supplying and discharging control with respect to the boom cylinder (10) based on manipulations of an operating member (16) and instructions from a control unit (20);
a lowering side oil discharging passage (E) which allows oil of a boom cylinder head side oil chamber (10b) flow toward the oil reservoir (12) side without passing through the control valve(13); and
a lowering side control means 21 which performs opening and closing control of the lowering side oil discharging passage (E) based on the instructions from the control unit (20), characterized in that
a mode selector switch (23) is connected to the control unit (20) permitting selection of a normal mode and a lowering hold releasing mode, wherein
when the normal mode is selected by the mode selector switch (23) the lowering side control means is controlled so as to close the lowering side oil discharging passage (E) based on the instructions from the control unit (20) and the control valve (13) is controlled so as to supply the pressure oil to the boom cylinder in accordance with the manipulations of the operating member and
when the lowering hold releasing mode is selected and the operating member is operated toward the boom lowering side the lowering side control means is controlled so as to open the lowering side oil discharging passage (E) and the control valve is controlled so as not to supply the pressure oil to the boom cylinder, based on the instructions from the control unit (20). - A boom cylinder control circuit of a working machine according to Claim 1, including a rising side oil discharging passage (F) which allows oil of a boom cylinder rod side oil chamber 10a to flow toward the oil reservoir side without passing through the control valve(13) and a rising side control means 22 which performs opening and closing control of the rising side oil discharging passage (F), the mode selector switch (23) permitting the selection of a lowering and rising hold releasing mode, wherein
when the lowering and rising hold releasing mode is selected by the mode selector switch and the operating member is operated toward the boom rising side, the lowering side control means 21 is controlled so as to close the lowering side oil discharging passage (E) and the rising side control means 22 is controlled so as to open the rising side oil discharging passage (F), based on the instructions from the control unit (20) and the control valve is controlled so as to supply the pressure oil to the rising side of the boom cylinder in accordance with the manipulations of the operating member, and wherein
when the lowering and rising hold releasing mode is selected by the mode selector switch and the operating member is operated toward the boom lowering side, the lowering side control means and the rising side control means open their discharging passages and the control valve is controlled so as not to supply the pressure oil to the boom cylinder, based on the instructions of the control unit. - A boom cylinder control circuit of a working machine according to Claim 1 or Claim 2, wherein
the control circuit of the boom cylinder is provided with:valves for preventing empty weight-lowering which, when the operating member is not manipulated toward the boom lowering side, prevent oil from being discharged from the boom cylinder head side oil chamber, but, based on a manipulation toward the boom lowering side, allow oil to be discharged from the head side oil chamber.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2000076002A JP3627972B2 (en) | 2000-03-17 | 2000-03-17 | Boom cylinder control circuit for work machines |
JP2000076002 | 2000-03-17 | ||
PCT/JP2000/006005 WO2001071110A1 (en) | 2000-03-17 | 2000-09-04 | Boom cylinder control circuit of working machine |
Publications (3)
Publication Number | Publication Date |
---|---|
EP1211359A1 EP1211359A1 (en) | 2002-06-05 |
EP1211359A4 EP1211359A4 (en) | 2006-12-13 |
EP1211359B1 true EP1211359B1 (en) | 2008-11-05 |
Family
ID=18593808
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP00956920A Expired - Lifetime EP1211359B1 (en) | 2000-03-17 | 2000-09-04 | Boom cylinder control circuit of working machine |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1211359B1 (en) |
JP (1) | JP3627972B2 (en) |
DE (1) | DE60040746D1 (en) |
WO (1) | WO2001071110A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN108005139A (en) * | 2016-10-28 | 2018-05-08 | 住友建机株式会社 | Excavator |
EP4379218A1 (en) * | 2022-12-01 | 2024-06-05 | Zöller-Kipper GmbH | Hydraulic system |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100518768B1 (en) | 2003-05-28 | 2005-10-06 | 볼보 컨스트럭션 이키프먼트 홀딩 스웨덴 에이비 | control device of hydraulic valve for load holding |
KR100631072B1 (en) * | 2005-06-27 | 2006-10-02 | 볼보 컨스트럭션 이키프먼트 홀딩 스웨덴 에이비 | Hydraulic circuit for heavy equipment option device |
JP5975073B2 (en) * | 2014-07-30 | 2016-08-23 | コベルコ建機株式会社 | Construction machinery |
US10407876B2 (en) | 2015-06-02 | 2019-09-10 | Doosan Infracore Co., Ltd. | Hydraulic system of construction machinery |
JP6580618B2 (en) * | 2017-03-21 | 2019-09-25 | 日立建機株式会社 | Construction machinery |
CN111868338B (en) * | 2018-03-22 | 2022-07-26 | 住友重机械工业株式会社 | Excavator |
CN114174594B (en) * | 2019-07-17 | 2023-11-21 | 现代斗山英维高株式会社 | Engineering machine and control method thereof |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3245288A1 (en) * | 1982-12-03 | 1984-06-14 | O & K Orenstein & Koppel Ag, 1000 Berlin | METHOD FOR SAVING ENERGY WHEN SETTING AN EQUIPMENT CYLINDER ON A HYDRAULIC EXCAVATOR BY A HYDRAULIC CIRCUIT |
JPH0794737B2 (en) * | 1989-08-02 | 1995-10-11 | 株式会社小松製作所 | Linear excavation control device in hydraulic excavator |
JPH09132927A (en) * | 1995-11-08 | 1997-05-20 | Komatsu Ltd | Hydraulic circuit of hydraulic shovel |
JP3182081B2 (en) * | 1996-07-01 | 2001-07-03 | 新キャタピラー三菱株式会社 | Hydraulic circuit of hydraulic cylinder in work machine |
JPH11158859A (en) * | 1997-11-27 | 1999-06-15 | Kobelco Constr Mach Eng Co Ltd | Control circuit for working machinery |
US6092454A (en) * | 1998-07-23 | 2000-07-25 | Caterpillar Inc. | Controlled float circuit for an actuator |
-
2000
- 2000-03-17 JP JP2000076002A patent/JP3627972B2/en not_active Expired - Fee Related
- 2000-09-04 DE DE60040746T patent/DE60040746D1/en not_active Expired - Lifetime
- 2000-09-04 EP EP00956920A patent/EP1211359B1/en not_active Expired - Lifetime
- 2000-09-04 WO PCT/JP2000/006005 patent/WO2001071110A1/en active Application Filing
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN108005139A (en) * | 2016-10-28 | 2018-05-08 | 住友建机株式会社 | Excavator |
CN108005139B (en) * | 2016-10-28 | 2022-01-04 | 住友建机株式会社 | Excavator |
EP4379218A1 (en) * | 2022-12-01 | 2024-06-05 | Zöller-Kipper GmbH | Hydraulic system |
Also Published As
Publication number | Publication date |
---|---|
DE60040746D1 (en) | 2008-12-18 |
JP2001262629A (en) | 2001-09-26 |
WO2001071110A1 (en) | 2001-09-27 |
EP1211359A1 (en) | 2002-06-05 |
JP3627972B2 (en) | 2005-03-09 |
EP1211359A4 (en) | 2006-12-13 |
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