EP3597588A1 - Chariot de manutention doté d'un système hydraulique ainsi que procédé de fonctionnement d'un système hydraulique - Google Patents

Chariot de manutention doté d'un système hydraulique ainsi que procédé de fonctionnement d'un système hydraulique Download PDF

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Publication number
EP3597588A1
EP3597588A1 EP19185823.2A EP19185823A EP3597588A1 EP 3597588 A1 EP3597588 A1 EP 3597588A1 EP 19185823 A EP19185823 A EP 19185823A EP 3597588 A1 EP3597588 A1 EP 3597588A1
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EP
European Patent Office
Prior art keywords
mast
lowering
lifting
free
valve
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.)
Granted
Application number
EP19185823.2A
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German (de)
English (en)
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EP3597588B1 (fr
Inventor
Jens Glaeske
Thomas Stolten
Hans-Peter ARP
Nis-Georg Nissen
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.)
Jungheinrich AG
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Jungheinrich AG
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Publication date
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Publication of EP3597588A1 publication Critical patent/EP3597588A1/fr
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F9/00—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
    • B66F9/06—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
    • B66F9/075—Constructional features or details
    • B66F9/20—Means for actuating or controlling masts, platforms, or forks
    • B66F9/22—Hydraulic devices or systems

Definitions

  • the invention relates to an industrial truck with a lifting mast with at least one mast lifting stage driven by at least one mast lifting cylinder and with a free lifting stage driven by at least one free lifting cylinder, with which a load suspension device can be moved along the lifting mast, comprising a hydraulic system for supplying the at least one mast lifting cylinder and the at least one a free lift cylinder with a hydraulic fluid. Furthermore, the invention relates to a method for operating a hydraulic system of an industrial truck with a lifting mast with at least one mast lifting stage and with a free lifting stage with which a load suspension device can be moved along the lifting mast, the hydraulic system comprising at least one mast lifting cylinder for driving the at least one mast lifting stage and at least comprises a free lift cylinder for driving the free lift stage.
  • Industrial trucks such as forklifts, have many via a lifting mast with one or more mast lifting stages that are hydraulically operated by one or more mast lifting cylinders.
  • the lifting mast comprises a standing mast permanently connected to the vehicle and usually two mast lifting stages, a central mast and an inner mast, which are extended by a mast lifting cylinder.
  • a free lift cylinder moves a free lift stage with which a load suspension device, for example a lifting fork or the like, can be moved along the inner mast of the lifting mast.
  • the free lift stage moves the barrel lifting device along this mast step and allows the operator of the industrial truck to move the load lifting device in height without the lifting mast being extended and thus changing the overall height of the industrial truck.
  • an industrial truck with a lifting mast which comprises a hydraulic system for supplying at least one mast lifting cylinder and at least one free lifting cylinder, which is set up in such a way that the at least one mast lifting cylinder and the at least one free lifting cylinder in load lifting operation and / or can be operated simultaneously in load lowering mode. It is thus possible for the mast lift stages and the free lift stage to be retracted and / or extended at the same time.
  • the lifting and lowering times of the load handler can be significantly reduced by the synchronous actuation of the mast lifting stages and the free lifting stage.
  • an industrial truck with a lifting mast with at least one mast lifting stage driven by at least one mast lifting cylinder and with a free lifting stage driven by at least one free lifting cylinder, with which a load suspension device can be moved along the lifting mast, comprising a hydraulic system for supplying the at least one mast lifting cylinder and of the at least one free lift cylinder with a hydraulic fluid, this industrial truck being further developed in that the hydraulic system is set up to at least temporarily actuate the at least one mast lift cylinder and the at least one free lift cylinder in the load lifting mode and / or in the load lowering mode, the hydraulic system for relieving the load comprises at least one mast lift cylinder and the at least one free lift cylinder in the load lowering mode a first hydraulic return line and a second hydraulic return line and the first and the second hydraulis che return line are fluidly coupled to one another via a third connecting line, in which a third lowering valve is integrated.
  • the known problem that the mast lift stage (s) is / are still extended after the lowering process is advantageously eliminated while the load suspension device is already in the area of the free lift.
  • the possibility is created to restore the original order of free lift and mast lift, that is, a stroke sequence.
  • the lowering time can be reduced by synchronously lowering the mast lift levels and the free lift level, thus increasing the handling capacity of the industrial truck.
  • the headroom of the industrial truck is not unnecessarily restricted. If, as already mentioned above, the lowering process is not completely finished, ie not down to the lower one End position of the load handler performed because z. B. a load is to be transported, there is the possibility that the mast still protrudes beyond the height of the mast and thus unnecessarily limits the clearance height of the truck. This disadvantage is eliminated by restoring the original stroke sequence.
  • fluidically coupled is understood to mean a hydraulically effective connection between the elements that are fluidically coupled to one another.
  • the third connecting line connects the first and the second hydraulic return line to one another. There is no need for a direct connection. A hydraulically effective connection of these two return lines is sufficient.
  • a hydraulic connecting line via which the first hydraulic return line is fluidly coupled to the third connecting line and the third lowering valve, and a further hydraulic connecting line, via which the second hydraulic return line is fluidly coupled to the third connecting line and the third lowering valve is free of installation.
  • the industrial truck is further developed in that a control is provided which is set up to actuate the third lowering valve, so that when the third lowering valve is open, a stroke sequence between the at least one mast lifting stage driven by the at least one mast lifting cylinder and that of the at least one free lift cylinder driven free lift stage can be restored.
  • the at least one mast lifting cylinder and the at least one free lifting cylinder are actuated simultaneously in the load lowering mode. This makes it possible to retract the mast lift stages and the free lift stage at the same time, which significantly reduces the lowering time of the load handler.
  • the third lowering valve By actuating the third lowering valve, the basically desired stroke sequence can be restored, so that on the one hand a quick lowering process is possible and on the other hand the mast steps do not protrude unnecessarily high above the industrial truck.
  • the at least one mast lifting stage can be retracted and the clearance height of the industrial truck is again the height predetermined by the height of the lifting frame.
  • the headroom of the industrial truck is no longer unnecessarily higher than it is due to the design.
  • actuation of the third lowering valve is understood to mean that it is opened or closed and, if appropriate, the flow rate is also controlled or regulated.
  • the third lowering valve is, for example, an S / W valve, that is to say a binary-acting switching valve which only provides the switching positions open or closed, or alternatively a proportional valve.
  • a first lowering valve is integrated in the first return line and a second lowering valve is integrated in the second return line, wherein the controller is further configured to control the first to third lowering valves in such a way that the first and second lowering valves are kept closed when that third lowering valve is actuated.
  • first hydraulic return line runs between the at least one free lift cylinder and a reservoir for the hydraulic fluid and the second hydraulic return line runs between the at least one mast lift cylinder and this reservoir.
  • the lowering valves are, for example, proportional valves.
  • control is also set up to control the first lowering valve and the second lowering valve during a lowering process of the load suspension device in such a way that the mast lift stage and the free lift stage are retracted simultaneously and the load suspension device is lowered at the end of this lowering process of the load suspension device to close the first and the second lowering valve and then to open the third lowering valve, so that the stroke sequence between the at least one mast lifting stage and the free lifting stage can be restored, in particular the load suspension device being above a lower end position at the end of the lowering process.
  • the free lift cylinder has a first cross section and the mast lift cylinder has a second cross section, the first and the second cross section being selected such that when the third lowering valve is open, the mast lift stage driven by the mast lift cylinder retracts at at least approximately the same speed , with which the free lift stage driven by the at least one free lift cylinder extends so that the load suspension means remains at least approximately at the same level.
  • the mast lift cylinder usually has a higher pressure level than the free lift cylinder. Hydraulic fluid can flow from the mast lift cylinder into the free lift cylinder through the opening of the third lowering valve until the mast lift is completely retracted. If the hydraulically effective cross-sections of the lifting cylinders are selected as indicated, which can be achieved by simple practical tests, the mast lift moves in at the same speed as the free lift extends. These two speeds on the load handler add up to zero, which means that the load handler does not change its height. As a result, the mast lift can be fully retracted while the load handler does not change its height.
  • an overflow of hydraulic fluid between the mast lift and the free lift ie an actuation of the third lowering valve by the control, is only provided if the load suspension device has not been completely retracted, that is to say is not in its lower end position. Furthermore, a corresponding control is only provided if the mast lift stage (s) is / are not completely retracted.
  • the free lift cylinder has a first cross section and the mast lift cylinder has a second cross section
  • the third lowering valve being a proportional valve and the controller being set up to control a hydraulic pump in dependence on a position of the third lowering valve in such a way that by the additional hydraulic fluid supplied to the hydraulic system of the hydraulic system, which extends the free lift stage driven by the at least one free lift cylinder at at least approximately the same speed as the mast lift stage driven by the at least one mast lift cylinder, so that the load suspension means remains at least approximately at the same level.
  • the hydraulic pump is controlled or regulated depending on the position of the proportional valve.
  • the hydraulic pump delivers the required amount of hydraulic fluid in order to restore the stroke sequence of the mast stages in a controlled manner.
  • the free lift cylinder has a first cross section and the mast lift cylinder has a second cross section
  • the third lowering valve being a proportional valve and the control unit being set up to control, depending on a detected position of the load suspension means, that by the hydraulic pump supplied additional hydraulic fluid which extends the free lift stage driven by the at least one free lift cylinder at at least approximately the same speed at which the mast lift stage driven by the at least one mast lift cylinder moves in, so that the load suspension means remains at least approximately at the same level.
  • the hydraulic pump is controlled or regulated as a function of a position of the load-carrying device that is detected with the aid of a sensor.
  • the first and second cross sections are in particular of different sizes.
  • the industrial truck is further developed in that the hydraulic system is set up in such a way that the third lowering valve acts as a lifting valve in the load lifting mode and as a lowering valve in the load lowering mode.
  • the third lowering valve thus advantageously has a double function.
  • the hydraulic system can be simplified in terms of design, for example a lifting valve can be dispensed with, since the third lowering valve takes over this function in lifting operation.
  • the industrial truck is further developed in that the hydraulic system for supplying the at least one mast lifting cylinder and the at least one free lifting cylinder with hydraulic fluid comprises a hydraulic pump which is set up to operate the free lifting cylinder via a first supply branch and the mast lifting cylinder via a second supply branch to be pressurized with hydraulic fluid under pressure, the third lowering valve being integrated in the first or the second supply branch, and in particular a check valve being present in a connecting line between the hydraulic pump and the third lowering valve.
  • only a check valve is provided on the pressure side of the hydraulic pump.
  • the two supply branches open into a common supply line in which the hydraulic pump is integrated.
  • the check valve is especially in this common supply line.
  • the object is further achieved by a method for operating a hydraulic system of an industrial truck with a lifting mast with at least one mast lifting stage and with a free lifting stage with which a load suspension device can be moved along the lifting mast, the hydraulic system having at least one mast lifting cylinder for driving the at least one mast lifting stage and comprises at least one free lift cylinder for driving the free lift stage, which is further developed in that the hydraulic system actuates the at least one mast lift cylinder and the at least one free lift cylinder at least temporarily at the same time in the load lifting operation and / or in the load lowering operation, the hydraulic system for relieving the at least one mast lifting cylinder and the at least one free stroke cylinder in the load lowering mode comprises a first hydraulic return line and a second hydraulic return line, and wherein the first and the second hydraulic return line are fluidis via a third lowering valve ch are coupled to one another, the hydraulic system comprising a control with which the third lowering valve is operated such that the first and second hydraulic return lines are fluidly coupled to one another via the third lowering valve.
  • the method is developed in particular in that the third lowering valve is opened by a stroke sequence between the mast stroke stage driven by the at least one mast lift cylinder and the free stroke stage driven by the at least one free stroke cylinder restore.
  • a first lowering valve is integrated in the first return line and a second lowering valve is integrated in the second return line, the control unit controlling the first to third lowering valves in such a way that the first and second lowering valves are kept closed when that third lowering valve is actuated.
  • the method is further developed, in particular, in that the controller controls the first lowering valve and the second lowering valve during a lowering process of the load suspension device in such a way that the mast lift stage and the free lift stage are retracted simultaneously and the load suspension device is lowered, at the end of this lowering process of the load suspension device the first and the second lowering valve are closed and then the third lowering valve is opened so that the stroke sequence between the at least one mast lifting stage and the free lifting stage is restored, in particular the load suspension device being at the end of the lowering process above a lower end position.
  • the method is advantageously further developed in that, when the third lowering valve is open, the mast lift stage driven by the mast lift cylinder retracts at least approximately the same speed as the free lift stage driven by the at least one free lift cylinder, so that the load suspension means remains at least approximately at the same height.
  • the free lift cylinder has a first cross section and the mast lift cylinder has a second cross section
  • the third lowering valve a proportional valve and the control unit controls a hydraulic pump in such a manner as a function of a position of the third lowering valve and / or as a function of a detected position of the load-carrying means that additional hydraulic fluid supplied to the hydraulic system by the hydraulic pump controls the free stroke level driven by the at least one free stroke cylinder with at least approximately the same speed extends with which the mast lift stage driven by the at least one mast lift cylinder retracts, so that the load suspension means remains at least approximately at the same height.
  • the method is further developed in that the third lowering valve acts as a lifting valve in load lifting operation and as a lowering valve in load lowering operation.
  • the third lowering valve thus advantageously fulfills a double function.
  • Embodiments according to the invention can fulfill individual features or a combination of several features.
  • Fig. 1 shows an industrial truck 2, for example a forklift, with a lifting mast 4, comprising, for example, a first mast lifting stage 41, the inner mast, and a second mast lifting stage 42, the middle mast.
  • the mast 4 is one in Fig. 1 Mast lift cylinder, not shown (several mast lift cylinders can also be provided).
  • the lifting mast 4 comprises a standing mast 54 which is firmly connected to the vehicle frame of the industrial truck 2 (cf. also FIG. 4 ).
  • the maximum height of the mast 54 limits the design-related headroom of the industrial truck 2.
  • the middle mast that is to say the second mast lifting stage 42, is driven, for example, by the mast lifting cylinder.
  • the inner mast that is to say the first mast lifting stage 41, is also coupled, for example, to the central mast via a chain, so that these two extending masts extend simultaneously.
  • the industrial truck 2 further comprises a free lift stage with which a load suspension device 6, for example a load suspension fork, can be moved along the inner mast, that is to say along the first mast lift stage 41.
  • the free lift stage comprises a free lift cylinder 8.
  • Fig. 2 shows a schematic circuit diagram of a hydraulic system 10 as it is integrated in the industrial truck 2 according to one embodiment.
  • the hydraulic system 10 serves to supply a mast lifting cylinder 12 and the free lifting cylinder 8 with which the load suspension device 6 is moved with a hydraulic fluid 14.
  • the hydraulic fluid 14 is removed from a storage container 16 and also supplied to it again.
  • the hydraulic system 10 is set up to at least temporarily operate the mast lifting cylinder 12 and the free lifting cylinder 8 simultaneously in the load lifting mode and / or in the load lowering mode.
  • the hydraulic system 10 comprises separate hydraulic return lines, namely a first hydraulic return line 181 and a second hydraulic return line 182.
  • the first hydraulic return line 181 runs between the free lift cylinder 8 and the storage container 16.
  • the second hydraulic return line 182 runs between the mast lifting cylinder 12 and the storage container 16.
  • the first and the second hydraulic return line 181, 182 are brought together on the pressure side of a common hydraulic return line 44.
  • a common lowering valve 46 is integrated in the common hydraulic return line 44.
  • a first lowering valve 21 is integrated in the first hydraulic return line 181 and a second lowering valve 22 is integrated in the second hydraulic return line 182.
  • the lowering valves 21, 22, like the common lowering valve 46, are, for example, proportional valves.
  • the first and the second lowering valve 21, 22 can be switched between a first switching position 21a, 22a, in which the lowering valves 21, 22 work as check valves, and a second switching position 21b, 22b.
  • the lowering valves 21, 22 are set up to be a first Volume flow or a second volume flow to control or regulate.
  • the first lowering valve 21 controls or regulates a first volume flow through the first hydraulic return line 181
  • the second lowering valve 22 controls or regulates a second volume flow through the second hydraulic return line 182.
  • the first and second lowering valves 21, 22 are each proportional valves.
  • the lowering valves 21, 22 can be controlled separately from one another.
  • a control 24 is included in the hydraulic system 10, which controls the two lowering valves 21, 22 via connecting lines (not shown for reasons of clarity).
  • the common lowering valve 46 also comprises a first switching position 46a, in which it acts as a shut-off valve, and a second switching position 46b, in which the common lowering valve 46 is set up to control or regulate a third volume flow.
  • the controller 24 is set up or provided with software means that the lowering valves 21, 22 open simultaneously in a load-lowering operation, ie when the load-carrying means 6 is lowered.
  • the free lift cylinder 8 of the free lift stage and the mast lift cylinder of the mast lift stages 41, 42 are retracted simultaneously.
  • the load suspension device 6 actuated by the free lift stage drops along the first mast lift stage 41, while the lift mast 4, ie the first and the second mast lift stage 41, 42, retract at the same time. In other words, synchronous retraction takes place of the two mast lifting stages 41, 42 and lowering of the load suspension device 6.
  • the hydraulic system 10 of the industrial truck 2 comprises a hydraulic pump 26. This takes hydraulic fluid 14 from the reservoir 16 via a hydraulic feed line 28.
  • the hydraulic pump 26 is integrated into the hydraulic feed line 28. In the load lifting mode, the hydraulic pump 26 serves to apply hydraulic fluid 14 to the mast lifting cylinder 12 and the free lifting cylinder 8.
  • the hydraulic feed line 28 bifurcates between the hydraulic pump 26, the free lift cylinder 8 and the mast lift cylinder 12 into a first supply branch 31 and into a second supply branch 32.
  • the first supply branch 31 leads to the free lift cylinder 8
  • the second supply branch 32 leads to the mast lift cylinder 12.
  • a lift valve 34 is integrated, which can be designed as a proportional valve.
  • the lift valve 34 like the hydraulic pump 26, can be controlled or regulated via the controller 24.
  • the lifting valve 34 comprises a first switching position 34a, in which the lifting valve 34 acts as a shut-off valve, and a second switching position 34b, in which the lifting valve 34 operates as a proportional valve.
  • the first hydraulic return line 181 and the second hydraulic return line 182 are fluidly coupled to one another via a third connecting line 48, into which a third lowering valve 50 is integrated.
  • the circuit diagram shown shows the third connecting line 48 between the first supply branch 31 and the second supply branch 32 of the supply line 28.
  • the first and the second supply branch 31, 32 are on the first and second nodes 52a, 52b are connected to the first hydraulic return line 181 and the second hydraulic return line 182, respectively.
  • the connection shown is hydraulically equivalent to a direct connection of the first and second hydraulic return lines 181, 182 through the third connection line 48.
  • the controller 24 is set up to actuate the third lowering valve 50 of the hydraulic system 10, ie to open, close it or to control or regulate a flow.
  • the third lowering valve 50 can be, for example, a binary-acting switching valve which only provides the switching positions open or closed, or alternatively a proportional valve. Is only an example in Fig. 2 a proportional valve is shown.
  • a fluidic connection between the mast lifting cylinder 12 and the free lifting cylinder 8 can thus be established.
  • the controller 24 is also configured to keep the first and second lowering valves 21, 22 closed when the third lowering valve 50 is actuated. A backflow of the hydraulic fluid is also prevented by the check valves 36 present in the first and second supply branches 31, 32.
  • the third lowering valve 50 like the lifting valve 34, comprises a first switching position 50a, in which the third lowering valve 50 acts as a shut-off valve, and a second switching position 50b, in which the third lowering valve 50 operates as a proportional valve.
  • Fig. 3 shows a schematic circuit diagram of a hydraulic system 10 as it is integrated into the industrial truck 2 according to a further exemplary embodiment.
  • the hydraulic system 10 is similar to that in FIG Fig. 2 shown hydraulic system 10 built, only the existing design differences are to be explained.
  • the hydraulic system 10 like the system explained above, comprises separate hydraulic return lines, namely a first hydraulic return line 181 and a second hydraulic return line 182.
  • the hydraulic return lines 181, 182 are merged on the pressure side into a common hydraulic return line 44, which leads directly into the Reservoir 16 of hydraulic fluid 14 opens out.
  • a first lowering valve 21 is integrated in the first hydraulic return line 181 and a second lowering valve 22 is integrated in the second hydraulic return line 182. There is a separate control of the first volume flow flowing through the first hydraulic return line 181 and the second volume flow flowing through the second hydraulic return line 182 through the first and second lowering valve 21, 22.
  • a control in which both lowering valves 21, 22 are fully opened and the draining of the hydraulic fluid 14 through a common lowering valve is not provided, as compared to that in FIG Fig. 2 shown embodiment is dispensed with this common lowering valve.
  • the controller 24 is also set up or provided with software means that the lowering valves 21, 22 open simultaneously in a load-lowering operation, ie when the load-carrying means 6 is lowered. So the free lift cylinder 8 of the free lift and the mast lift cylinder of the mast lift stages 41, 42 retracted simultaneously.
  • the hydraulic system 10 includes the hydraulic pump 26. This takes hydraulic fluid 14 from the reservoir 16 via a hydraulic feed line 28.
  • the hydraulic pump 26 is integrated into the hydraulic feed line 28.
  • the hydraulic pump 26 serves to apply hydraulic fluid 14 to the mast lifting cylinder 12 and the free lifting cylinder 8.
  • the hydraulic feed line 28 forks at a third node 52c into a first supply branch 31 and into a second supply branch 32.
  • the first supply branch 31 leads to the free lift cylinder 8
  • the second supply branch 32 leads to the mast lift cylinder 12.
  • a check valve 36 is present at node 52c.
  • the third lowering valve 50 which is integrated, for example, into the first supply branch 31, acts as a lifting valve and its function is the same as that in FIG Fig. 2 shown lift valve 34 comparable.
  • the third lowering valve 50 which acts as a lifting valve, can, like the hydraulic pump 26, be controlled or regulated via the controller 24. It includes a first switch position 50a, in which it acts as a shut-off valve, and a second switch position 50b, in which it works as a proportional valve.
  • the third connecting line 48 is formed by the section of the first supply branch 31 between the first node 52a and the third node 52c and the section of the second supply branch 32 between the third node 52c and the second node 52b.
  • the third lowering valve 50 is integrated into this third connecting line 48.
  • the third connecting line 48 fluidly couples the hydraulic return lines 181, 182 to one another.
  • the controller 24 is set up to actuate the third lowering valve 50 of the hydraulic system 10, that is to say to open, to close it or to control or regulate a flow.
  • the third lowering valve 50 is therefore, for example, a binary-acting switching valve which only provides the switching positions open or closed, or alternatively a proportional valve.
  • a proportional valve is shown by way of example only.
  • the third lowering valve 50 includes, for example, a first switching position 50a, in which it acts as a shut-off valve, and a second switching position 50b, in which it works as a proportional valve.
  • the controller 24 is also configured to keep the first and second lowering valves 21, 22 closed when the third lowering valve 50 is actuated. A backflow of the hydraulic fluid is prevented by the check valve 36.
  • Fig. 4 shows another hydraulic system 10, which differs from that in Fig. 3 hydraulic system 10 shown only differs in that the second switching position 50b of the third lowering valve 50 is designed so that the valve can be flowed through in both directions in this position.
  • Fig. 5 shows an industrial truck 2 after a lowering operation of its load handling device 6, during which the first lowering valve 21 and the second lowering valve 22 were actuated in such a way that the first and second mast lifting stages 41, 42 and the free lifting stage were retracted simultaneously.
  • the load suspension device 6 is lowered, but is not at its lower end position at the end of the lowering process, but above it.
  • the controller 24 now closes the first and second lowering valves 21, 22 and then opens the third lowering valve 50, so that a fluidic connection is established between the mast lifting cylinder 12 and the free lifting cylinder 8.
  • the hydraulically effective first cross section of the free lift cylinder 8 and the hydraulically active second cross section of the mast lift cylinder 12 are dimensioned such that when the third lowering valve 50 is open, pressure equalization between the mast lift cylinder 12 and the free lift cylinder 8 takes place such that the Retract mast lift cylinders 12 driven mast lift stages 41, 42 at at least approximately the same speed at which the free lift stage driven by the free lift cylinder 8 extends.
  • the load suspension device 6 remains at least approximately at the same level in the entire process.
  • the hydraulic pump 26 is controlled by the controller 24 in such a way that additional hydraulic fluid is supplied from the reservoir 16 to the hydraulic system 10. This is done in such a way that the free lift stage driven by the at least one free lift cylinder 8 is at least approximately the same speed extends with which the mast lift stage 41, 42 driven by the at least one mast lift cylinder 12 retracts. In this way it is achieved that the load suspension device 6 remains at least approximately at the same level.
  • the hydraulic pump 26 is controlled or regulated, for example, as a function of a position of the third lowering valve 50 or also as a function of a detected position of the load suspension device 6.
  • a sensor (not shown) is present, which detects the position of the load suspension device 6 and the recorded measurement value of the controller 24 provides.
  • the hydraulic pump 26 thus delivers the required amount of hydraulic fluid in order to restore the stroke sequence of the mast stages 41, 42 in a controlled manner.
  • FIG. 6 shows the industrial truck 2 at the end of this process between the mast lifting cylinder 12 and the free lifting cylinder 8.
  • the two mast lift stages 41, 42 are retracted, the load suspension device 6 is still at least approximately at the same height.
  • the headroom of the industrial truck 2 is only determined by the height of the mast 54 of the industrial truck 2.

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Structural Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Civil Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
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  • Forklifts And Lifting Vehicles (AREA)
EP19185823.2A 2018-07-18 2019-07-11 Chariot de manutention doté d'un système hydraulique ainsi que procédé de fonctionnement d'un système hydraulique Active EP3597588B1 (fr)

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DE102018117391.1A DE102018117391A1 (de) 2018-07-18 2018-07-18 Flurförderzeug mit einem hydraulischen System sowie Verfahren zum Betreiben eines hydraulischen Systems

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EP3597588A1 true EP3597588A1 (fr) 2020-01-22
EP3597588B1 EP3597588B1 (fr) 2023-08-23

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1593645A2 (fr) * 2004-05-03 2005-11-09 BT Industries Appareil de levage hydraulique pour le mât télescopique d'un chariot élévateur à fourches
EP3336051A1 (fr) * 2016-12-15 2018-06-20 Jungheinrich Aktiengesellschaft Dispositif de levage pour un chariot de manutention ainsi qu'un tel chariot de manutention
DE102017121818A1 (de) 2017-09-20 2019-03-21 Jungheinrich Ag Flurförderzeug, hydraulisches System für ein Flurförderzeug und Verfahren zum Betreiben eines hydraulischen Systems

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102016103256A1 (de) * 2015-12-29 2017-06-29 Still Gmbh Flurförderzeug mit einem Hubgerüst

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1593645A2 (fr) * 2004-05-03 2005-11-09 BT Industries Appareil de levage hydraulique pour le mât télescopique d'un chariot élévateur à fourches
EP3336051A1 (fr) * 2016-12-15 2018-06-20 Jungheinrich Aktiengesellschaft Dispositif de levage pour un chariot de manutention ainsi qu'un tel chariot de manutention
DE102017121818A1 (de) 2017-09-20 2019-03-21 Jungheinrich Ag Flurförderzeug, hydraulisches System für ein Flurförderzeug und Verfahren zum Betreiben eines hydraulischen Systems

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DE102018117391A1 (de) 2020-01-23

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