EP2196682A1 - Dispositif hydraulique pour la commande d'un actionneur d'engin de travaux. - Google Patents

Dispositif hydraulique pour la commande d'un actionneur d'engin de travaux. Download PDF

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Publication number
EP2196682A1
EP2196682A1 EP08425791A EP08425791A EP2196682A1 EP 2196682 A1 EP2196682 A1 EP 2196682A1 EP 08425791 A EP08425791 A EP 08425791A EP 08425791 A EP08425791 A EP 08425791A EP 2196682 A1 EP2196682 A1 EP 2196682A1
Authority
EP
European Patent Office
Prior art keywords
conduit
chamber
valve
actuator
operating fluid
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.)
Withdrawn
Application number
EP08425791A
Other languages
German (de)
English (en)
Inventor
Andrea Storci
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bosch Rexroth Oil Control SpA
Original Assignee
Bosch Rexroth Oil Control SpA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Bosch Rexroth Oil Control SpA filed Critical Bosch Rexroth Oil Control SpA
Priority to EP08425791A priority Critical patent/EP2196682A1/fr
Publication of EP2196682A1 publication Critical patent/EP2196682A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • 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
    • 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
    • E02F9/226—Safety arrangements, e.g. hydraulic driven fans, preventing cavitation, leakage, overheating
    • 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
    • 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"
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/3056—Assemblies of multiple valves
    • 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
    • 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
    • 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
    • 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
    • F15B2211/765—Control of position or angle of the output member

Definitions

  • the invention relates to a hydraulic device for controlling an actuator, in particular an actuator which moves an arm of a mobile work vehicle.
  • Work vehicles such as for example excavators or lift trucks, usually comprise one or more arms supporting a work tool, for example a bucket, a fork or the like.
  • Each arm is provided with an actuator cylinder which moves the arm between a raised position and a lowered position.
  • an operating fluid is sent into a first chamber of the actuator cylinder via a first conduit; at the same time a second chamber of the actuator cylinder is connected to a tank via a second conduit such as to discharge the operating fluid initially present in the second chamber.
  • a known solution places a one-way valve along the first conduit, between the first chamber of the actuator cylinder and the tank, which one-way valve comprises an obturator and a spring to keep the obturator in a closed position.
  • the one-way valve opens when the operating fluid that is directed from the actuator cylinder towards the tank exceeds a predetermined pressure level, able to overcome the resistance of the spring acting on the obturator.
  • a connecting conduit connects a point of the first conduit interposed between the actuator cylinder and the one-way valve with the second conduit.
  • the one-way valve arranged along the first conduit opposes the flow of the operating fluid towards the tank.
  • the operating fluid can thus be deviated along the connecting conduit, which has a relatively low hydraulic resistance, and from here it passes into the second chamber, facilitating the filling thereof.
  • Hydraulic devices of the above-described type have the drawback that the operating fluid, in order to be discharged from the first chamber of the actuator cylinder towards the tank, always have to overcome the force of the spring included in the one-way valve arranged along the first conduit, such as to keep the valve open. Consequently, a part of the work done by the operating fluid cannot be exploited in order to move the arm, but is dissipated in order to keep the one-way valve open. This reduces the power that the operating fluid can usefully dispense.
  • An aim of the invention is to improve hydraulic devices for controlling an actuator of a work vehicle, particularly an actuator destined to move an arm.
  • a further aim is to provide a hydraulic device which can be associated to an actuator in a work vehicle, which is able to prevent a chamber of the actuator from emptying when an operating fluid is removed rapidly from a further chamber of the actuator.
  • a further aim is to provide a hydraulic device for controlling an actuator of a work vehicle in which the power of the operating fluid that is dissipated is reduced.
  • a further aim is to provide a hydraulic device for controlling an actuator of a work vehicle, in which the phenomena of overheating of the operating fluid are minimised.
  • a hydraulic device for controlling an actuator which comprises a body having a first conduit destined to be connected to a first chamber of the actuator, a second conduit destined to be connected to a second chamber of the actuator, a connecting conduit connecting the first conduit and the second conduit in order to send an operating fluid coming from the first chamber towards the second chamber, a valve having an obturator element for selectively closing the first conduit so that the operating fluid coming from the first chamber flows towards the connecting conduit, characterised in that it comprises control means for displacing the obturator element into an open position when the pressure of the operating fluid in the second chamber exceeds a predetermined level.
  • the hydraulic valve of the invention prevents the second chamber of the actuator from emptying in a case in which the operating fluid exits the first chamber very rapidly. Instead of being discharged, the operating fluid which exits the first chamber can flow directly into the second chamber through the connecting conduit.
  • the control means displace the obturator element into the open position. The operating fluid can thus be discharged through the first conduit.
  • the valve which selectively closes the first conduit is kept open not by the pressure of the operating fluid, as occurred in the known single-operating valves including a spring, but by the control means acting on the obturator element. This enables the control valve to be kept open without removing energy from the operating fluid, such that substantially all the power in the operating fluid can be expended in performing a useful task. Further, undesired overheating of the operating fluid is avoided.
  • Figure 1 illustrates a hydraulic device 1 for controlling an actuator 2, in particular in a mobile work vehicle.
  • the work vehicle can be, for example, a lift truck or an earth moving machine such as a digger.
  • the actuator 2 can be used to move an arm of the work vehicle, for example a telescopic arm in the case of a lift truck or an oscillating arm in the case of an earth moving machine.
  • the arm can be formed by several reciprocally-mobile parts, for example rotatable or slidable to one another, or it can be made of a single structure.
  • the arm moved by the actuator 2 can support a work tool, for example a bucket, a backhoe or a fork.
  • the actuator 2 comprises a first chamber 3 and a second chamber 4, afforded for example internally of a cylinder 5.
  • the first chamber 3 and the second chamber 4 are destined to receive an operating fluid, for example oil.
  • the first chamber 3 and the second chamber 4 are separated by a mobile piston 6, mobile inside the cylinder 5.
  • a stem 7 associated to the arm (not illustrated) of the work vehicle is fixed to the piston 6.
  • the work tool is raised when the operating fluid is sent into the first chamber 3 and discharged from the second chamber 4, such that the stem 7 exits from the cylinder 5. Conversely, the work tool lowers when the operating fluid is sent into the second chamber 4 and discharged from the first chamber 3, such that the stem 7 penetrates internally of the cylinder 5.
  • the hydraulic device 1 comprises a body 8, which internally affords a first conduit 9 and a second conduit 10.
  • the first conduit 9 opens onto the body 8 at a first opening 24 and a second opening 25.
  • the second conduit 10 opens onto the body 8 at a further first opening 26 and a further second opening 27.
  • the first conduit 9 is destined to communicate with the first chamber 3 through the first opening 24, while the second conduit 10 is destined to communicate with the second chamber 4 through the further first opening 26.
  • the first conduit 9 is connectable, through the second opening 25, to a distributor provided with a slide valve 11, shown only schematically in figure 1 .
  • the second conduit 10 is also connectable to the distributor via the further second opening 27.
  • the first conduit 9 and the second conduit 10 can be selectively connected to a main pump, not illustrated, or to a tank 13.
  • the distributor can be a three-way distributor or the slide valve 11 can be mobile among three working positions.
  • the slide valve 11 connects the first conduit 9 to the main pump and the second conduit 10 to the tank 13. In the first position, the tool is thus moved upwards.
  • the first conduit 9 is connected to the tank 13 and the second conduit 10 is connected to the main pump in order to move the tool downwards.
  • a central position interposed between the first position and the second position, both the first conduit 9 and the second conduit 10 are disconnected from the main pump.
  • the work vehicle comprises a command organ, for example a lever 12, arranged to move the slide valve 11 between the three above-described work positions.
  • the lever 12 can be positioned in a cabin of the work vehicle such that the operator can reach the lever 12 when she or he is manoeuvring the vehicle.
  • the lever 12 is inserted in a piloting circuit, represented by a broken line in figure 1 , in which the piloting fluid, for example oil, circulates.
  • the piloting fluid can be taken from the tank 13 by means of an auxiliary pump 14. Alternatively, if the auxiliary pump 14 is not present, the piloting fluid can be removed from the line supplied by the main pump.
  • the hydraulic device 1 is mounted in proximity of the actuator 2.
  • the body 8 of the hydraulic device 1 can be connected to the actuator 2 by means of short pipes which join the first conduit 9 to the first chamber 3 and the second conduit 10 to the second chamber 4.
  • the hydraulic device 1 can be directly mounted on the actuator 2, for example by fixing the body 8 to a flange of the actuator 2 by means of threaded connecting elements. In both cases, the hydraulic device 1 is arranged externally of the vehicle cabin.
  • the hydraulic device 1 comprises a control valve 15 arranged along the first conduit 9 for controlling the flow of the operating fluid in the first conduit 9.
  • the control valve 15 is interposed between the first chamber 3 of the actuator 2 and the distributor including the slide valve 11.
  • the control valve 15 comprises an obturator element 16, for example a slide valve.
  • the obturator element 16 is mobile internally of a seating 17, which can be cylindrical, in order to open and close the first conduit 9.
  • a spring 18 contrasts the opening of the obturator element 16.
  • the obturator element 16 is kept closed by the operating fluid pressure in the first conduit 9, even in the absence of forces applied by the spring 18.
  • An activating element 19 for example a piloting piston, acts on the obturator element 16 in the opposite direction to the spring 18.
  • the activating element 19 is moved by the piloting fluid pressure present in a line 21 of the piloting circuit.
  • the body 8 has an inlet 36 though which the piloting fluid can be sent into the line 21 towards the control valve 15 and an outlet 37 through which any excess of piloting fluid is sent to a tank 13.
  • the control valve 15 acts like a block and flow rate control valve in order to block and/or control the flow rate of operating fluid through the first conduit 9.
  • the control valve 15 enables the arm to be kept in a predetermined position, preventing it from moving, for example, in a downwards direction due to leakage through the hydraulic components of the work vehicle.
  • the control valve 15 further prevents the arm from accidentally falling to the ground, for example if a pipe breaks or if a command organ is unintentionally operated.
  • control valve 15 By controlling the operating fluid flow rate flowing through the first conduit 9, the control valve 15 further enables the controlled movement of the work vehicle arm and in particular the controlled descent of the arm towards the ground.
  • a connecting conduit 32 is afforded in the body 8, which connecting conduit 32 connects the first conduit 9 and the second conduit 10.
  • the connecting conduit 32 starts from a point P on the first conduit 9, the point P being interposed between the control valve 15 and the second opening 25.
  • a one-way valve 33 is arranged along the connecting conduit 32, which one-way valve 33 opens at low pressure to enable the operating fluid coming from the first chamber 3 and thus the first conduit 9 to flow towards the second conduit 10.
  • the one-way valve 33 can be uncalibrated, i.e. can be kept closed or open only by the difference between the pressures acting on an obturator organ the valve 33 is provided with.
  • the hydraulic device 1 further comprises a valve, for example a balance valve 34, arranged along the first conduit 9 to selectively open and close the conduit 9.
  • the balance valve 34 is interposed between the point P and the second opening 25.
  • the balance valve 34 comprises an obturator element (not illustrated) which is normally kept closed, such that the operating fluid coming from the first chamber 3 can flow towards the second chamber 4 through the connecting conduit 32, without being discharged through the second opening 25.
  • the hydraulic device 1 comprises control means for displacing the obturator element into an open position when the pressure of the operating fluid in the second chamber 4 exceeds a predetermined level.
  • the control means can comprise a piloting conduit 50 into which a piloting fluid flows to pilot the obturator element of the balance valve 34.
  • the piloting conduit 50 connects the balance valve 34 at a point of the connecting conduit 32 which is interposed between the one-way valve 33 and the second conduit 10. In other words, the piloting conduit 50 communicates with the second conduit 10 through the connecting conduit 32.
  • the piloting fluid which pilots the balance valve 34 is therefore the operating fluid circulating in the second conduit 10 which, during use, is connected to the second chamber 4. In this way, a piloting pressure acts on the obturator element of the balance valve 34 which piloting pressure is correlated to the operating fluid pressure in the second chamber 4.
  • the control means controlling the opening of the balance valve 34 are designed such as to displace the obturator element into the open position as soon as the operating fluid present in the second chamber 4 is pressurised, which occurs when it is attempted to send operating fluid into the second chamber 4 which is already completely full. In an opposite case, i.e. if the second chamber 4 is not completely full of operating fluid, the balance valve 34 is maintained in a closed position.
  • the one-way valve 33 and the component 34 act as an anti-cavitation device preventing the second chamber 4 from emptying when the operating fluid is made to flow rapidly out of the first chamber 3. This can happen when the arm of the work machine is moved downwards, exploiting the force of gravity due to the weight of the arm, the tool and any load supported by the tool. In this case, the stem 7 penetrates internally of the cylinder 5 and the operating fluid exits very rapidly from the first chamber 3, which reduces in volume.
  • the main pump sends the operating fluid towards the second chamber 4 of the actuator 2, the volume of which increases. If however the operating fluid flow rate sent by the main pump towards the second chamber 4 is lower than the rate required in order to guarantee the filling of the second chamber 4, a lower pressure is present in the second chamber than the predetermined pressure at which the balance valve 34 opens.
  • the balance valve 34 thus remains in the closed position and prevents the operating fluid coming from the first chamber 3 from being discharged through the second opening 25. Consequently, the operating fluid coming from the first chamber 3 passes through the control valve 15, which is completely open, and thus flows into the connecting conduit 32, opening the one-way valve 33. The operating fluid passes from the connecting conduit 32 into the second conduit 10 and reaches the second chamber 4 of the actuator 2.
  • the present in the second chamber 4 increases and exceeds the predetermined level at which the balance valve 34 is calibrated.
  • the fluid in the piloting conduit 50 thus moves the obturator element of the balance valve 34 into the open position. This enables the operating fluid coming from the first chamber 3 to be discharged into the tank through the second opening 25 and the distributor.
  • the control means can enable regulation of the position of the obturator element of the balance valve 34, such that the valve defines a variable-size passage hole for the operating fluid.
  • the passage hole can grow in size together with the pressure of the operating fluid present in the first chamber 3, such as to rapidly discharge the operating fluid in order to enable the arm to be moved quickly.
  • the balance valve 34 is kept open when so required by the pressure of the piloting fluid. Consequently, the operating fluid coming from the first chamber 3 does not have to expend energy to keep the valve open. All the energy associated to the operating fluid can thus be used to move the arm of the work vehicle, which enables maximisation of the power that the work vehicle can supply. Further, the operating fluid overheating phenomenon is now limited.
  • pilot valve 34 instead of the balance valve 34 a pilot valve of a different type can be used, for example a slide valve which is piloted into the open position by the piloting fluid circulating in the piloting conduit 50.
  • a delivery conduit 22 is afforded internally of the body 8, which delivery conduit 22 starts from a first portion of the first conduit 9 and connects up to a second portion of the first conduit 9, such as to bypass the control valve 15.
  • the delivery conduit 22 has thus a first end and a second end, both connected to the first conduit 9.
  • a first one-way valve 23 is arranged along the delivery conduit 22, which enables the operating fluid to flow only from the distributor towards the first chamber 3 and prevents the flow of operating fluid in the opposite direction.
  • the hydraulic device 1 further comprises a pressure limiter valve 28, interposed between the delivery conduit 22 and the line 21.
  • a pressure limiter valve 28 When the pressure limiter valve 28 opens, it causes total opening of the obturator element 16 in order to prevent excessive build-up of pressure in the first chamber 3.
  • a choke device 29 is arranged along the line 21, in an interposed position between the pilot valve 20 and the pressure limiter valve 28.
  • a second one-way valve 30 is included along the line 21, mounted in parallel to the choke device 29, which enables a fluid flow only from the inlet 36 towards the control valve 15.
  • a branch 31 connecting the line 21 to the activating element 19 of the control valve 15 runs from a portion of the line 21 interposed between the choke device 29 and the pressure limiter valve 28.
  • the pressure limiter valve 28 is a normally-closed valve that opens when the operating fluid pressure in the first chamber 3 of the actuator 2 exceeds a predetermined limit value. This can happen, for example, because the tool has accidentally impacted against an obstacle such as a rock. If the pressure limiter valve 28 opens, the operating fluid present in the first chamber 3 passes into the line 21.
  • the choke device 29 is of such a size that if the pressure limiter valve 28 opens, in the tract of line 21 interposed between the choke device 29 and the pressure limiter valve 28 a sufficient pressure is created to move the obturator element 16 via the branch 31, the obturator element 16 being brought into a completely open position.
  • the operating fluid present in the first chamber 3 passes through the control valve 15 and exits the hydraulic device 1 through the second opening 25.
  • the fluid is then discharged through the distributor, in proximity of which a further pressure limiter valve is arranged, not illustrated, which in turn opens.
  • a further pressure limiter valve is arranged, not illustrated, which in turn opens.
  • the operator wishing to raise the arm activates the lever 12 such that the slide valve 11 of the distributor is brought into the first position, in which the first conduit 9 is connected to the main pump and the second conduit 10 is connected to the tank 13.
  • the operating fluid enters the body 8 through the second opening 25 and passes through the delivery conduit 22, exits from the first opening 24 and passes into the first chamber 3.
  • the operating fluid in the second chamber 4 is discharged into the tank 13 through the second conduit 10 and the distributor. Consequently, the stem 7 exits the cylinder 5 and the arm is raised.
  • the operator moves the lever 12 to move the slide valve 11 into the second position, in which the first conduit 9 is connected to the tank 13 and the second conduit 10 to the main pump.
  • the operating fluid processed by the main pump enters the body 8 through the further second opening 27 and, after having run through the second conduit 10, enters the second chamber 4 of the actuator 2.
  • the operating fluid is evacuated from the first chamber 3 via the first conduit 9 such that the stem 7 moves towards the inside of the cylinder 5.
  • the operator By acting on the lever 12, the operator can control the position of the obturator member 16 of the control valve 15, such that the control valve 15 allows a certain operating fluid flow to pass. This brings the arm downwards in a controlled way.
  • the pilot valve 20 positions the obturator element 16 in a completely open configuration and the operating fluid is discharged through the control valve 15 at maximum flow.
  • the operating fluid is discharged through the distributor when the secibd cganver 4 is completely full of operating fluid, in which case the balance valve 34 is piloted into the open position and connects the first opening 24 to the second opening 25.
  • the balance valve 34 is closed and the operating fluid coming from the first chamber 3 goines into the connecting conduit 32, opens the one-way valve 33 and fills the second chamber 4. This prevents the second chamber 4 from emptying if the operating fluid exits the first chamber 3 very quickly.
  • the body 8 housing the control valve 15 also houses the pilot valve 20 and the anti-cavitation device. This makes the hydraulic device very compact and enables the hydraulic device 1 to be mounted in proximity of the actuator 2.
  • the hydraulic device 1 defines a sort of valve unit which enables the operating fluid flow from and towards the actuator 2 to be regulated.
  • Figure 2 shows a hydraulic device 101 in an alternative version.
  • the components of the hydraulic device 101 common to the hydraulic device 1 of figure 1 are denoted using the same reference numbers as used for figure 1 , and are not further described in detail.
  • a first conduit 109, a second conduit 110 and a delivery conduit 122 are afforded in the body 8 of the hydraulic device 101.
  • the first conduit 109 opens on the body 8 at a first opening 124 and a second opening 125.
  • the first opening 124 is destined to be connected to the first chamber 3 of the actuator 2, while the second opening 125 is to be connected directly to the tank 13, without passing through the distributor.
  • the second conduit 110 opens on the body 8 at a further first opening 126 and a further second opening 127, destined to be connected respectively to the second chamber 4 of the actuator 2 and to the distributor including the slide valve 11.
  • the delivery conduit 122 has an end that opens on the body 8 at an inlet opening 40 destined to be connected to the distributor. A further end of the delivery conduit 122 joins the first conduit 109 at a point of the first conduit 109 that is interposed between the control valve 15 and the first opening 124.
  • the main pump sends the operating fluid into the delivery conduit 122 through the distributor and the inlet opening 40.
  • the operating fluid passes from the delivery conduit 122 and reaches the first chamber 3.
  • the operating fluid in the second chamber 4 is discharged through the second conduit 110.
  • the slide valve 11 is positioned such as to connect the main pump to the second conduit 110. Consequently the operating fluid is sent into the second chamber 4.
  • the control valve 15 is opened by the desired amount to enable the operating fluid to flow from the first chamber 3 towards the tank 113. If necessary, a part of the operating fluid coming from the first chamber can reach the second chamber 4 through the connecting conduit 32. If the second chamber 4 is already full, the balance valve 34 is opened and enables the operating fluid to be discharged into the tank 113.
  • the operating fluid coming from the first chamber 3 is thus discharged into the tank 13 without passing through the distributor.
  • the hydraulic resistance the operating fluid has to overcome in order to be discharged is reduced, as the hydraulic resistance defined by an eventual connecting line connecting the first conduit to the distributor is eliminated. This enables the duration of the work cycle to be reduced and the temperature of the operating fluid to be limited
  • Figure 3 shows a hydraulic device 201 in an alternative version, which differs from the hydraulic device 1 shown in figure 1 because it enables a more precise control to be had over the position of the obturator member 16 of the control valve 15.
  • the hydraulic device comprises a pilot valve 20 for controlledly sending the piloting fluid to the control valve 15, such as to move the obturator element 16.
  • the pilot valve 20 can comprise a proportional valve, in particular a pressure control proportional valve, i.e. a valve which generates in outlet a piloting fluid pressure which is proportional to a command signal in input.
  • the command signal in input can be an electric signal.
  • the pilot valve 20 is interposed between the control valve 15 and a pressurised circuit which sends the pilot valve 20 the piloting fluid at a relatively high pressure.
  • the pressurised circuit can comprise the auxiliary pump 14.
  • the piloting fluid which exits the pilot valve 20 has a variable pressure according to a predetermined law.
  • the piloting fluid pressure in outlet from the pilot valve 20 can be selected by the operator via a selection device, for example a lever.
  • the operator can precisely regulate the piloting fluid pressure in outlet from the pilot valve 20. Consequently, it is possible to regulate the obturator element 16 of the control valve 15 exactly, and therefore the flow rate of the operating fluid passing through the control valve 15. This enables precise control of the movement of the stem 7 and therefore the arm of the work vehicle, when the arm is lowered.
  • the pilot valve 20 and the control valve 15 are both inserted into the body 8 of the hydraulic device 201. Consequently the pilot valve 20 and the control valve 15 are connected to one another by means of a line 221 which is very short. Thanks to its shortness, the line 221 enables the pilot valve 20 to command the control valve 15 with no delay.
  • the hydraulic device 1 thus has shorter response times than in a case in which the position of the obturator member 16 of the control valve 15 is directly regulated by means of the lever 12 present in the work vehicle cabin, as in the version of figure 1 .
  • FIG. 3 shows an auxiliary pump 14 which can be provided for removing the piloting fluid from the tank 13.
  • auxiliary pump 14 which can be provided for removing the piloting fluid from the tank 13.
  • two distinct tanks 13 have been shown, although the work vehicle normally comprises a single tank.
  • Figure 4 shows a hydraulic device 301 in a further alternative version.
  • the hydraulic device 301 like the hydraulic device 201 shown in figure 3 , comprises both the anticavitation circuit including the balance valve 34 and the piloting valve 20.
  • the first conduit 109 similarly to what is shown in figure 2 , the first conduit 109 has a first opening 124 destined to be connected to the first chamber 3 of the actuator 2 and a second opening 125 intended to be directly connected to the tank 113, without passing through the distributor.
  • FIG. 5 shows a hydraulic device 401 in a further alternative version.
  • the hydraulic device differs 401 from the hydraulic device 1 described in reference to figure 1 , because it comprises a further control valve 45 arranged along the second conduit 10.
  • the further control valve 45 is normally closed and is piloted into an open position by the pressure of the operating fluid present in the first conduit 9.
  • a piloting branch 46 interposed between the first conduit 9 and the further control valve 45 is afforded in the body 8 of the hydraulic device 401.
  • a choke element 47 can be included along the piloting branch 46.
  • a one-way valve 48 is arranged in parallel to the further control valve 45 and enables the operating fluid to flow only from the second opening 27 to the further first opening 26, preventing flow in the opposite direction.
  • the connecting conduit 32 connects the point P of the first conduit 9 with a further point Q of the second conduit 10, the further point Q being interposed between the further first opening 26 and the further control valve 45.
  • the operating fluid is sent from the main pump into the second conduit 10 through the distributor.
  • the operating fluid passes through the one-way valve device 48 and reaches the second chamber 4 of the actuator 2, causing the stem 7 to return into the cylinder 5.
  • the main pump sends the operating fluid into the first chamber 3 by means of the first conduit 9 and the delivery conduit 22.
  • the further control valve 45 thus enables the operating fluid to be discharged controlledly from the second chamber 4 towards the tank.
  • the further control valve 45 which controls the discharge of the operating fluid from the second chamber 4, is piloted by the operating fluid pressure present on the opposite side of the actuator 2, i.e. in the first chamber 3.
  • the further control valve 45 thus functions according to a system known as "crossover piloting".
  • the further control valve 45 acts as a block and control valve of the flow, which enables the operating fluid to be discharged controlledly through the second conduit 10. This enables the extending movement of the arm to be precisely controlled.
  • the control valve 15 and the further control valve 45 enable the operating fluid to be controlledly discharged from both sides of the actuator 2, i.e. both from the first chamber 3 and from the second chamber 4. In this way, the arm of the operating machine moves in a controlled way both when it is raised and when it is lowered.
  • Figure 6 illustrates a hydraulic device 501 of a further alternative version. Like the hydraulic device 401 shown in figure 5 , the hydraulic device 501 also comprises the further control valve 45 arranged along the second conduit 110.
  • the hydraulic device 501 of figure 6 differs from the hydraulic device 401 of figure 5 because the body 8 has a first conduit 109 having a terminal portion connected to the first chamber 3 of the actuator 2 and a further terminal portion connected directly to the tank 113, such that the operating fluid can be discharged from the second opening 125 without passing through the distributor. From this point of view, the hydraulic device 501 shown in figure 6 is similar to the hydraulic device 101 shown in figure 2 .
  • FIG 7 illustrates a hydraulic device 601 deriving from the combination of the hydraulic devices shown in figures 3 and 5 .
  • the hydraulic device 601 comprises the piloting valve 20 arranged along the line 221 in order to precisely control the position of the obturator member 16 of the control valve 15.
  • the control valve 15 is arranged along the first conduit 9 and acts as a block and control valve of the flow which controls the operating fluid exiting from the first chamber 3 of the actuator 2.
  • the hydraulic device 601 further comprises the further control valve 45 arranged along the second conduit 10 for controlling the operating fluid which is discharged from the second chamber 4.
  • the further control valve 45 is opened by the piloting pressure of the operating fluid present in the first conduit 9.
  • the first conduit 9 has a terminal portion connected to the first chamber 3 and a further terminal portion connected to the distributor including the slide valve 11.
  • the second conduit 10 has a terminal part connected to the second chamber 4 and a further terminal part connected to the distributor.
  • the hydraulic device 601 enables particularly high performance to be obtained.
  • Figure 8 illustrates a hydraulic device 701 which differs from the hydraulic device 601 of figure 7 , because it comprises a body 8 having a first conduit 109 comprising a terminal portion connected to the first chamber 3 and a further portion connected directly to the tank 113.
  • the hydraulic device 701 comprises the further control valve 45, piloted by the fluid contained in the piloting branch 46 which is in communication with the delivery conduit 122.
  • the hydraulic device 701 enables the operating fluid to be sent from the first chamber 3 to the tank very rapidly and without excessive hydraulic resistance, as the operating fluid can be discharged from the first chamber 3 without passing through the distributor.
EP08425791A 2008-12-15 2008-12-15 Dispositif hydraulique pour la commande d'un actionneur d'engin de travaux. Withdrawn EP2196682A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP08425791A EP2196682A1 (fr) 2008-12-15 2008-12-15 Dispositif hydraulique pour la commande d'un actionneur d'engin de travaux.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP08425791A EP2196682A1 (fr) 2008-12-15 2008-12-15 Dispositif hydraulique pour la commande d'un actionneur d'engin de travaux.

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EP2196682A1 true EP2196682A1 (fr) 2010-06-16

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2786959A1 (fr) * 2013-04-05 2014-10-08 Bosch Rexroth Oil Control S.p.A. Dispositif d'anti-cavitation pour vérin hydraulique
US11225981B2 (en) 2017-05-03 2022-01-18 Cnh Industrial America Llc Vehicle with a boom comprising a hydraulic control circuit with a load control valve

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5415076A (en) * 1994-04-18 1995-05-16 Caterpillar Inc. Hydraulic system having a combined meter-out and regeneration valve assembly
EP0867567A2 (fr) * 1997-03-24 1998-09-30 Oyodo Komatsu Co., Ltd. Règleur de pression d'huile
EP1574474A2 (fr) * 2004-03-13 2005-09-14 Deere & Company Agencement hydraulique
JP2006292091A (ja) * 2005-04-12 2006-10-26 Shin Caterpillar Mitsubishi Ltd 流体圧回路

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5415076A (en) * 1994-04-18 1995-05-16 Caterpillar Inc. Hydraulic system having a combined meter-out and regeneration valve assembly
EP0867567A2 (fr) * 1997-03-24 1998-09-30 Oyodo Komatsu Co., Ltd. Règleur de pression d'huile
EP1574474A2 (fr) * 2004-03-13 2005-09-14 Deere & Company Agencement hydraulique
JP2006292091A (ja) * 2005-04-12 2006-10-26 Shin Caterpillar Mitsubishi Ltd 流体圧回路

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2786959A1 (fr) * 2013-04-05 2014-10-08 Bosch Rexroth Oil Control S.p.A. Dispositif d'anti-cavitation pour vérin hydraulique
US11225981B2 (en) 2017-05-03 2022-01-18 Cnh Industrial America Llc Vehicle with a boom comprising a hydraulic control circuit with a load control valve

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