DK2594523T3 - Lifting platform with a hydraulic system - Google Patents

Lifting platform with a hydraulic system Download PDF

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Publication number
DK2594523T3
DK2594523T3 DK11189373T DK11189373T DK2594523T3 DK 2594523 T3 DK2594523 T3 DK 2594523T3 DK 11189373 T DK11189373 T DK 11189373T DK 11189373 T DK11189373 T DK 11189373T DK 2594523 T3 DK2594523 T3 DK 2594523T3
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DK
Denmark
Prior art keywords
volume flow
pressure
flow regulating
regulating valve
valve
Prior art date
Application number
DK11189373T
Other languages
Danish (da)
Inventor
Verkoyen Torsten Dr-Ing
Original Assignee
Palfinger Platforms GmbH
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 Palfinger Platforms GmbH filed Critical Palfinger Platforms GmbH
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Publication of DK2594523T3 publication Critical patent/DK2594523T3/en

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Classifications

    • 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
    • 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
    • B66F1/00—Devices, e.g. jacks, for lifting loads in predetermined steps
    • 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
    • B66F7/00—Lifting frames, e.g. for lifting vehicles; Platform lifts
    • B66F7/02—Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms suspended from ropes, cables, or chains or screws and movable along pillars
    • B66F7/04—Lifting frames, e.g. for lifting vehicles; Platform lifts with platforms suspended from ropes, cables, or chains or screws and movable along pillars hydraulically or pneumatically operated

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  • Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Mechanical Engineering (AREA)
  • Transportation (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Civil Engineering (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Forklifts And Lifting Vehicles (AREA)

Description

Lifting work platform with a hydraulic system
Description [0001] The invention relates to a lifting work platform with a hydraulic system, which has at least one engine, designed in particular as a pump, and at least one working machine, in particular a working machine designed as a hydraulic cylinder, wherein each working machine is connected by means of two connections serving as an inflow or a return depending on the operating state of the working machine, and with at least one valve, arranged in the pressure lines, for setting the respective operating state of at least one, in particular of each, working machine.
[0002] Lifting working platforms comprise a plurality of hydraulic cylinders formed as working machines. For example, two hydraulic cylinders are assigned to a support. The one hydraulic cylinder causes a horizontal extension of the support, and the other hydraulic cylinder causes a vertical extension. Further hydraulic cylinders are provided in order to extend the lifting arm or the basket arm.
[0003] In order to change the operating state, a four-three-way proportional valve is provided for each hydraulic cylinder, to which two proportional coils are assigned, in order to move the four-three-way proportional valve out of its middle position into the two other switching states. DE 10053485 A1 discloses a hydraulic system of this kind, with a pump and a hydraulic cylinder.
[0004] Proportional valves allow for a proportionally controlled form of movement. Depending on the setting of the actuation lever actuated by a user, the proportional valve is moved in the same amount into the open or closed state. This proves to be a disadvantage, in particular with substantial distances between the four-three-way proportional valve and the corresponding working machine, since the pressure line must first be filled with hydraulic fluid until the load pressure is reached. Only when the load pressure is exceeded will the desired movement of the hydraulic cylinder be implemented.
[0005] The object of the invention is to avoid the aforementioned disadvantages and to provide a lifting work platform which allows for a faster setting of a desired operating state even with working machines which are connected to the corresponding valve via a long pressure line.
[0006] This object is solved in that, for an initially pressure-regulated, and later at least also, in particular exclusively, volume-flow regulated operating mode of at least one working machine, the valve is formed as a hydraulic switching valve with at least two, and preferably three, switching states, and arranged in the pressure line between the working machine and the switching valve is a volume flow regulating valve with two switching states, which branches on the one hand into a loading line between the engine and the measuring diaphragm, and, on the other, branches into a further loading line between the measuring diaphragm and the volume flow regulating valve, wherein, in order to change the switching state of the volume flow regulating valve, the one loading line is connected by means of a corresponding connection to the one side of the volume flow regulating valve, and the other loading line is connected by a corresponding connection to the other side of the volume flow regulating valve, and wherein, for the actuation of the volume flow regulating valve, on the one hand a measuring diaphragm is provided in the pressure line between the engine and the volume flow regulating valve, which can be changed in its position by means of an actuation element, in particular by means of an electric coil, and, on the other hand, a pressure sensor is provided, which, in proportion to the measured hydraulic pressure, issues a signal to the measuring diaphragm.
[0007] The volume flow regulating valve can be a 2-way volume flow regulating valve. The volume flow regulating valve is usually held in a first switching state by a spring force. If, for example, this is a pressure spring, then the volume flow regulating valve will be moved out of this first position into its second position when pressure is imposed onto the end of the volume flow regulating valve opposite the spring, provided that the pressure loading force is greater than the spring force.
[0008] The embodiment according to the invention allows in a first step for a purely pressure-regulated form of movement. As a result of this, the pressure line is filled with hydraulic fluid in a very short period of time, and, by the hydraulic fluid, a pressure is produced which is, for example, 98% of the desired load pressure. If the pressure sensor detects that the target value of 98% of the load pressure has been reached, it sends a signal to the actuation element of the measuring diaphragm, proportional to the measured pressure. The measuring diaphragm is closed by the actuation element, and the infeed of hydraulic fluid is thereby interrupted.
[0009] In a second step, the volume flow regulated operation then takes place in a second step, in which the measuring diaphragm allows for a defined volume flow to pass, which corresponds to the setting of the actuation lever, independently of the prevailing pressure. Thanks to the volume flow regulating valve, a volume flow which has been set will remain unchanged, even if there is a change in the pressure gradient present at the switching valve.
[0010] By means of the embodiment according to the invention, the desired operating state can be reached faster and more precisely in comparison with conventional lifting work platforms. The pressure is regulated behind the measuring diaphragm by the pressure sensor. As an alternative, the volume flow can be proportional to the pressure drop at the measuring diaphragm.
[0011] By contrast with conventional lifting work platforms, in the first step there is accordingly no quantity requirement, but a purely pressure requirement, such that, as a result, the pressure line is filled directly and rapidly. In the second step, a quantity-regulated form of movement then follows, which allows for a fine adjustment.
[0012] As well as a more precise form of movement of lifting work platforms, the number of proportional coils can also be reduced. While with conventional lifting work platforms two proportional coils were required for each proportional valve, only one proportional coil is assigned to each measuring diaphragm.
[0013] The pressure of the hydraulic fluid can be measured in the part region of the pressure line located between the measuring diaphragm and the volume flow regulating valve.
[0014] In this situation, it is advantageous if the pressure is measured in the loading line which branches between the measuring diaphragm and the volume flow regulating valve.
[0015] The loading line which branches between the measuring diaphragm and the volume flow regulating valve can comprise a bypass opening into a tank and provided with a diaphragm. In the event that, in the first step, with the pressure-regulated form of movement, too high a pressure has been set, this pressure can be reduced by way of the bypass. The hydraulic fluid emerging from the hydraulic system in this situation is collected in the tank. It is advantageous if the diaphragm is formed as fixed and not adjustable.
[0016] At least one switching valve can be formed as a four-three-way valve. At the two opposing ends of the switching element, seen in the direction of the switching path, a switching magnet or solenoid can be provided in each case. A switching magnet only allows for movement into the one or other position. Intermediate positions are not possible.
[0017] With the preferred embodiment of the invention, it is advantageous if a plurality of working machines of the hydraulic system are combined into at least one group I, II ...., in particular into a plurality of groups I, II .., wherein each working machine is assigned to only a single group I, II .., with the respective working machines being assigned in each case a hydraulic switching element with at least two switching states, wherein, at the change of the switching state of the switching element, the operating state of at least one working machine of the corresponding group changes.
[0018] An embodiment of the invention represented in the single drawing is explained hereinafter. This represents a highly simplified hydraulic system of a lifting work platform. For the sake of better overview, only one working machine 1 is represented, formed as a hydraulic cylinder.
[0019] As can be seen from the figure, the hydraulic system comprises a pump as the engine 2, which is connected to a tank 3. By means of two connections, serving, depending on the operating state of the engine 2, as inflow or return, each working machine 1 is connected by means of corresponding pressure lines 4, 5 to the engine 2.
[0020] As the valve, a hydraulic switching valve 6 is provided, which exhibits two switching states. The switching valve 6 can be displaced in the direction of the arrow 7. In the middle position represented, the working machine 1 is not switched on. The hydraulic oil can flow out of the hydraulic cylinder into a tank 8. Two springs 9, which engage at the two ends of the switching valve 6, hold the switching valve 6 in its middle position. In addition, at each end of the switching valve 6 an electric coil 10 is provided, which causes a displacement in the direction of the arrow 7.
[0021] In addition, a volume flow regulating valve 11 with two switching states is arranged in the pressure line 4 between the working machine 1 and the switching valve 6. In the position shown, the volume flow regulating valve 11 is held by a pressure spring 12, which in the embodiment represented takes effect on the right-hand end of the volume flow regulating valve 11. The volume flow regulating valve 11 can be displaced in the direction of the arrow 13.
[0022] In addition, arranged in the pressure line 4 between the volume flow regulating valve 11 and the engine 2 is a measuring diaphragm 14. In order to adjust the measuring diaphragm 14, an actuation element 15, such as an electrically-operating proportional coil, is assigned to it.
[0023] Additionally, both a loading line 16 branches between the engine 2 and the measuring diaphragm 14 from the pressure line 4, as well as a further loading line 17 between the measuring diaphragm 14 and the volume flow regulating valve 11. In order to change the switching state of the volume flow regulating valve 11, the one loading line 16 is connected to a corresponding connection of the one side of the volume flow regulating valve 11, and the other loading line 17 to a corresponding connection on the other side of the volume flow regulating valve 11.
[0024] The actuation of the volume flow regulating valve 11 is effected on the one hand by the measuring diaphragm 4 and, on the other, by a pressure sensor 18, which, proportionately to the measured hydraulic pressure, issues a signal to the actuation element 15 of the measuring diaphragm 14. The pressure is measured in this situation in the loading line 17, which branches between the measuring diaphragm 14 and the volume flow regulating valve 11.
[0025] Additionally, the loading line 17, which branches between the measuring diaphragm 14 and the volume flow regulating valve 11, comprises a bypass 20, opening into a tank 19, with a diaphragm 21.
[0026] As can be seen from the figure, a load retention valve 22 is also provided in each pressure line 4, 5. In addition to this, an overpressure valve 23 and a further tank 24 are also provided, in order to prevent too high a pressure build-up. In the event of too high a pressure build-up, the overpressure valve 23 opens and the hydraulic oil can flow into the further tank 24.
[0027] In the embodiment represented, the hydraulic system comprises in total four tanks, which serve to supply the hydraulic fluid. It is of course also possible for only one common tank to be provided.
[0028] The hydraulic system represented allows, in a first step, for an initially pressure-regulated form of operation, and in a subsequent second step for at least one volume flow-regulated form of operation, in particular exclusively volume flow-regulated.
[0029] If, for example, an operator of the lifting working platform actuates the actuation lever which is assigned to the main cylinder of the basket arm, the switching valve 6 is displaced to the right, such that the left-hand switching state is reached. The measuring diaphragm 14 and the volume flow regulating valve 11 are fully opened, as is represented in the figure, such that the pressure line 4 concerned is thereby immediately filled by the inflowing hydraulic fluid.
[0030] If the pressure sensor 18 now measures a preset value, which amounts, for example, to 98% of the load pressure which is to be attained, then the pressure sensor 18 issues a signal to the actuation element 15, and the measuring diaphragm 14 is closed by the actuation element 15.
[0031] In the second step, a volume flow-controlled form of movement now follows. In this situation the measuring diaphragm 14 only allows through the volume flow quantity which corresponds to the setting of the actuation lever. Once the desired operating state of the working machine 1 has been reached, the measuring diaphragm 14 is closed again by the actuation element 15.

Claims (6)

1. Løfteplatform med et hydrauliksystem, som har mindst en drivmaskine (2) udformet især som en pumpe, og mindst en arbejdsmaskine (1), især en arbejdsmaskine (1) udformet som en hydraulikcylinder, hvor hver arbejdsmaskine (1) ved hjælp af respektive trykledninger (4, 5) er tilsluttet en drivmaskine (2) via to forbindelser, der tjener som tilløb eller returløb, afhængig af arbejdsmaskinens (I) driftstilstand, og med mindst en ventil arrangeret i trykledningerne (4, 5) til indstilling af den respektive driftstilstand for mindst en, især hver, arbejdsmaskine (1), kendetegnet ved, at der for en oprindelig trykreguleret og senere i det mindste også, især alene, volumenstrømreguleret driftsmåde af mindst en arbejdsmaskine (1) er ventilen udformet som en hydraulisk omskifterventil (6) med mindst to, fortrinsvis tre, omskifterstilstande, og at en volumenstrømregulerende ventil (11) med to skiftetilstande er arrangeret i trykledningen (4 eller 5) mellem drivmaskinen (2) og omskifterventilen (6), idet en påvirkningsledning (16) på den ene side afgrenes mellem drivmaskinen (2) og måleblænden (14), og at en yderligere påvirkningsledning (17) på den anden side afgrenes mellem måleblænden (14) og den volumenstrømregulerende ventil (11), hvori den ene påvirkningsledning (16) for at ændre den volumenstrømregulerende ventils (16) tilstand er forbundet med en tilsvarende tilslutning på den ene side af den volumenstrømregulerende ventil (11), og den anden påvirkningsledning (17) er forbundet med en tilsvarende tilslutning på den anden side af den volumenstrømregulerende ventil (II) , og hvori der til aktivering af den volumenstrømregulerende ventil (11) på den ene side er tilvejebragt en måleblænde (14) i trykledningen (4 eller 5) mellem drivmaskinen (2) og den volumenstrømregulerende ventil (11), hvilken måleblændes stilling kan ændres ved hjælp et drivelement (15), især ved hjælp af en elektrisk spole, og på den anden side er tilvejebragt en trykføler (18), som sender et signal til drivelementet (15) på måleblænden (14) i forhold til det målte hydrauliske tryk.A lifting platform with a hydraulic system having at least one driving machine (2) designed in particular as a pump, and at least one working machine (1), in particular a working machine (1) designed as a hydraulic cylinder, each working machine (1) using pressure lines (4, 5) are connected to a driving machine (2) via two connections which serve as inlet or return, depending on the operating state of the working machine (I) and with at least one valve arranged in the pressure lines (4, 5) for adjusting the respective operating state of at least one, in particular each, working machine (1), characterized in that for an initially pressure controlled and later at least also, especially only, volume controlled operation of at least one working machine (1), the valve is designed as a hydraulic switch valve (6). ) with at least two, preferably three, switch modes, and that a two-mode volume flow regulating valve (11) is arranged in the pressure line (4 or 5) between the drive (2) and switch the valve (6), branching on one side (16) on the one hand between the driving machine (2) and the measuring aperture (14), and on the other side branching on an additional affect line (17) between the measuring aperture (14) and the volume flow regulating valve ( 11), in which one influx line (16) for changing the state of the volume flow regulating valve (16) is connected to a corresponding connection on one side of the volume flow regulating valve (11) and the other influence line (17) is connected to a corresponding a connection on the other side of the volume flow regulating valve (II) and in which, for activating the volume flow regulating valve (11), on one side, a measuring aperture (14) is provided in the pressure line (4 or 5) between the driving machine (2) and the volume flow regulating valve (11), the position of the measuring apertures can be changed by means of a drive element (15), in particular by means of an electric coil, and on the other hand is provided e. n pressure sensor (18) which sends a signal to the drive element (15) on the measuring aperture (14) relative to the measured hydraulic pressure. 2. Løfteplatform ifølge det foregående krav, kendetegnet ved, at trykket af det hydrauliske fluid i det delområde af trykledningen (4 eller 5), som er placeret mellem måleblænden (14) og den volumenstrømregulerende ventil (11), måles.Lifting platform according to the preceding claim, characterized in that the pressure of the hydraulic fluid in the part area of the pressure line (4 or 5) located between the measuring diaphragm (14) and the volume flow regulating valve (11) is measured. 3. Løfteplatform ifølge et af de foregående krav, kendetegnet ved, at trykket i påvirkningsledningen (17), som afgrenes mellem måleblænden (14) og den volumenstrømregulerende ventil (11), måles.Lifting platform according to one of the preceding claims, characterized in that the pressure in the actuating line (17), which is branched between the measuring aperture (14) and the volume flow regulating valve (11), is measured. 4. Løfteplatform ifølge et af de foregående krav, kendetegnet ved, at påvirkningsledningen (17), som afgrenes mellem måleblænden (14) og den volumen-strømregulerende ventil (11), har et bypass (20), som udmunder i en tank (19) med en blænde (21).Lifting platform according to one of the preceding claims, characterized in that the actuating line (17) which is branched between the measuring aperture (14) and the volume flow regulating valve (11) has a bypass (20) which opens into a tank (19). ) with an aperture (21). 5. Løfteplatform ifølge et af de foregående krav, kendetegnet ved, at mindst en omskifterventil (6) er udformet som en fire/trevejsventil.Lifting platform according to one of the preceding claims, characterized in that at least one switching valve (6) is designed as a four / three way valve. 6. Løfteplatform ifølge et af de foregående krav, kendetegnet ved, at en flerhed af arbejdsmaskiner (1) i hydrauliksystemet er kombineret til mindst en gruppe I, II, især i en flerhed af grupper I, II, hvor hver arbejdsmaskine (1) er tildelt kun en enkelt gruppe I, II, hvor hver gruppe I, II, ...med respektive arbejdsmaskiner (1) i hvert tilfælde er tildelt et hydraulisk omskifterelement med mindst to skiftestillinger, hvor driftstilstanden af mindst en arbejdsmaskine (1) i den tilsvarende gruppe I, II, ...ændres, når skifteelementets skiftetilstand ændres.Lifting platform according to one of the preceding claims, characterized in that a plurality of working machines (1) in the hydraulic system are combined to at least one group I, II, especially in a plurality of groups I, II, where each working machine (1) is assigned only a single group I, II, where each group I, II, ... with respective working machines (1) is assigned in each case a hydraulic switching element with at least two shift positions, the operating state of at least one working machine (1) in the corresponding groups I, II, ... change when the switching state of the switching element changes.
DK11189373T 2011-11-16 2011-11-16 Lifting platform with a hydraulic system DK2594523T3 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP20110189373 EP2594523B1 (en) 2011-11-16 2011-11-16 Lifting work platform with a hydraulic system

Publications (1)

Publication Number Publication Date
DK2594523T3 true DK2594523T3 (en) 2015-04-13

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DK11189373T DK2594523T3 (en) 2011-11-16 2011-11-16 Lifting platform with a hydraulic system

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DK (1) DK2594523T3 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2829504A1 (en) * 2013-07-23 2015-01-28 Palfinger Platforms GmbH Method for controlling a working machine and hydraulic system for a lifting work platform
CN107165897A (en) * 2017-07-06 2017-09-15 岭南师范学院 A kind of hydraulic control system of agricultural machinery vehicle body elevating mechanism

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10053485B4 (en) * 2000-10-27 2005-12-01 Linde Ag Hydraulic drive device for tilting a load-bearing mast element
US7484814B2 (en) * 2006-03-03 2009-02-03 Husco International, Inc. Hydraulic system with engine anti-stall control
DE102006060351B8 (en) * 2006-12-20 2008-07-24 Sauer-Danfoss Gmbh & Co Ohg Hydraulic circuit with energy recovery

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EP2594523B1 (en) 2015-01-07
EP2594523A1 (en) 2013-05-22

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