EP3533752B1 - Industrial truck with at least one hydraulic mast lifting cylinder - Google Patents

Industrial truck with at least one hydraulic mast lifting cylinder Download PDF

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Publication number
EP3533752B1
EP3533752B1 EP19158782.3A EP19158782A EP3533752B1 EP 3533752 B1 EP3533752 B1 EP 3533752B1 EP 19158782 A EP19158782 A EP 19158782A EP 3533752 B1 EP3533752 B1 EP 3533752B1
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EP
European Patent Office
Prior art keywords
lowering
industrial truck
load
path
valve
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EP19158782.3A
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German (de)
French (fr)
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EP3533752A1 (en
Inventor
Kai Fischer
Johannes Michael Frey
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Jungheinrich AG
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Jungheinrich AG
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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
    • B66F9/08—Masts; Guides; Chains
    • 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 present invention relates to an industrial truck with at least one hydraulic mast lifting cylinder.
  • the mast lift cylinder is connected to a hydraulic block via a hydraulic assembly.
  • the hydraulic arrangement limits a lowering speed of the mast lifting cylinder.
  • Masts on an industrial truck usually have at least one mast lift cylinder and one free lift cylinder. Via the mast lifting cylinder, mast sections are telescopically displaced in relation to one another in the mast.
  • the free lift cylinder moves a load bearing means relative to an inner mast section.
  • the maximum lowering speed of a mast is limited. The limitation is achieved via the hydraulic system using a corresponding throttle. For example, a lowering speed of 0.6 m/s is planned for a loading condition close to the rated load.
  • a vehicle operator specifies a desired lowering speed, for example, via an operating lever, which is checked for its admissibility.
  • the hydraulic arrangement is also equipped with a line breakage protection.
  • the line break protection fulfills the task of preventing the load from falling if a line breaks.
  • the object of the invention is to provide an industrial truck that can be used efficiently even with large lifting heights.
  • the industrial truck according to the invention has at least one hydraulic mast lifting cylinder which is connected to a hydraulic block via a hydraulic arrangement.
  • the hydraulic arrangement limits the lowering speed of the mast lifting cylinder.
  • the hydraulic system is designed to limit the lowering speed to at least two maximum values depending on the load, of which there is a first maximum value for the lowering speed at a predetermined load value, in particular at nominal load, and a second maximum value for the lowering speed at a second load that is smaller than the first load.
  • the first maximum value is preferably smaller than the second maximum value.
  • the mast lifting cylinder is lowered at a lower lowering speed in the event of a greater load.
  • the mast lift cylinder can be lowered at a greater speed. Due to the configuration of the hydraulic arrangement according to the invention, the lifting mast can be lowered again at great speed after the load has been lowered at a height. In the case of long-term use of an industrial truck, particularly at high lifting heights, this results in rapid empty lowering and significantly improved operational behavior of the industrial truck.
  • the hydraulic system is equipped with at least two separate lowering paths.
  • Each of the lowering paths has a load break safety device.
  • Two lowering paths it is possible to switch between two lowering speeds.
  • the usage of Two lowering paths does not necessarily mean that it is only possible to switch between two lowering speeds in discrete form. It is also entirely conceivable to provide a continuous transition between the two lowering paths that are separate from one another.
  • Each of the lowering paths is equipped with a load breaking device to ensure that a load breaking device is provided for each of the lowering speeds.
  • Each of the two lowering paths preferably defines a maximum volume flow for the lowering movement.
  • the volume flow essentially determines the lowering speed of the mast lifting cylinder.
  • a pressure balance is used to switch between the first and the second maximum value.
  • a pressure from the mast lifting cylinder is applied to the pressure compensator as control pressure. This applied pressure can certainly also be reduced or increased so that the pressure compensator responds.
  • the pressure compensator actuates a check valve, with which one of the lowering paths (Q1) is blocked or switched on to the other lowering path (Q2), so that when the lowering path is blocked, the first maximum value and when the lowering path is switched on, the second maximum value is available as the lowering speed for the mast lifting cylinder .
  • a second lowering path is either blocked or connected in parallel to the first lowering path. With the parallel connection, the volume flow of the two lowering paths is added, so that the volume flow is added and the lowering speed increases.
  • the check valve has a in a valve block with a biased against a spring force valve spool, which responds to a pressure in the first lowering path against a spring bias in a den second lowering path closing position is advanced. Because of the spring force, the valve spool is prestressed into a position in which both lowering paths are connected in parallel. If the valve spool is in its spring-loaded position, both lowering paths are connected. If the pressure in the first lowering path increases, this is taken as an indication of a large load and the valve spool is advanced into its blocking position.
  • a changeover valve is provided, which is used to switch between the first lowering path and the second lowering path in such a way that either the first maximum value occurs in the first lowering path or the second maximum value occurs in the second lowering path.
  • the switching valve also works with a pressure compensator.
  • the switchover valve has a valve slide that is preloaded against a spring force and, depending on its position, selectively blocks one of the lowering paths.
  • the valve slide is constructed in such a way that the two lowering paths can only be blocked alternatively to one another.
  • a switching load value is preferably provided for the industrial truck according to the invention, which is less than or equal to the nominal load, when this is exceeded the lowering speed is switched to the first maximum value.
  • Such behavior conforms to the standard, since it refers to the maximum lowering speed at nominal load.
  • a further hydraulic arrangement is provided for a free lift cylinder of the industrial truck, which can limit the lowering speed to at least two maximum values depending on the load.
  • a lower lowering speed can also be defined for a large load in the free lift cylinder than for a smaller load, which also allows a higher lowering speed in free lift.
  • FIG 1 shows two mast lift cylinders 10 and one free lift cylinder 12 in a schematic view.
  • the distinction between mast lift cylinders and free lift cylinders results from the arrangement and mode of operation of the hydraulic cylinders in a mast.
  • the mast has several telescoping mast sections, the mast sections being moved relative to one another by the mast lifting cylinder.
  • the free lift cylinder lifts the load carrying means relative to the mast section that can be raised the furthest.
  • Mast lifting cylinder 12 and free lifting cylinder 10 are jointly supplied with hydraulic fluid via a hydraulic block (not shown).
  • the cylinders are connected to a hydraulic block whose output line 14 has the input line to the hydraulic assemblies 16 and 18 .
  • the Hydraulic assemblies 16 have two lowering paths 20, 22, while in the illustrated embodiment the free lift cylinder 12 has only a single lowering path 24.
  • Each of the lowering paths 20, 22, 24 has a load breakage safety device (LBS), which ensures slow, controlled lowering even under load in the event of a fault.
  • Load breakage devices LBS are generally known from the prior art.
  • the load break safety device is shown schematically as a valve switched via a pressure compensator.
  • the cylinder-side pressure 26 is compared to a throttled pressure 28 downstream.
  • a check valve 30 is provided for the two mast lifting cylinders 10 .
  • the check valve 30 is biased into the position shown by a spring 32 so that the pressure in the mast lifting cylinder is not too great. In this position, the check valve 30 is open and the mast lifting cylinder 10 is lowered via both lowering paths 36, 38.
  • the lowering paths 36 and 38 are connected in parallel, so that their volume flows add up and the lowering speed is thus increased.
  • the blocking valve 30 is dimensioned such that when the nominal load is approached, it blocks and the load or section of the mast is lowered via the lowering path 38 at the permitted lowering speed.
  • FIG 2 shows an alternative embodiment of the invention in a schematic view.
  • the same components are given the same reference symbols.
  • Two lowering paths 36, 38 are provided for each of the two mast lifting cylinders 10 in this embodiment as well.
  • a changeover valve 40 is provided here, with which it is optionally possible to switch between the lowering path 36 and the lowering path 38 .
  • the lowering process takes place via the lowering path 32.
  • the check valve 40 is in its prestressed position by the spring 42. If the pressure in the mast lifting cylinder 10 increases, the check valve 40 is switched over via the control side 44 and the lowering process takes place exclusively via the lowering path 38.
  • the lowering path 38 is dimensioned in such a way that a maximum permissible lowering speed is not exceeded at nominal load. If, on the other hand, the load is less than the nominal load, a switch is made to the other lowering path 36, which has a significantly larger volume flow, for example, and thus allows a higher lowering speed. Both lowering paths 36 and 38 each have their own appropriately designed load break protection.
  • FIG. 3 shows a schematic view of a hydraulic arrangement according to FIG figure 1 with a practical implementation of the check valve.
  • an interior space 46 of a mast lifting cylinder is shown, which is connected to two lowering paths 48,50.
  • Both lowering paths 48, 50 each have a load break safety device 52, shown schematically.
  • a valve slide 54 is arranged in the lowering channel 48 and is prestressed by a spring 56 into a position releasing the lowering path. If the pressure in the lowering path 48 increases, the valve spool 54 is displaced against the tension of the spring 56 and thus blocks the lowering path 48. In this case, only the lowering path 50 is in operation in order to drain the hydraulic fluid via a connected line 58.
  • the lowering paths 48 and 50 are each closed via screw plugs 60 .
  • FIG. 4 shows a schematic view of a switchover valve in which a valve slide 62 is used to switch between a first path 64 and a second path 66 .
  • Each of the paths 64 and 66 has a load break safety device 68, 70.
  • the valve spool 62 is biased by the spring 72 in a path 66 blocking position. If the pressure in a line 63 increases, the valve slide 62 is pushed against the spring force 72 into its position blocking the path 65 connected to the ambient pressure or from the lowering path, in which position the path 66 is released.
  • the valve slide 62 adjusts depending on the pressure difference between the lowering path and the hydraulic cylinder. A pressure difference necessary for switching is determined by the spring 72 .
  • FIG 5 shows a schematic view of an embodiment of a check valve 74.
  • the check valve 74 has a valve block 76 in which a valve slide 78 is arranged centrally.
  • a line 81 coming from the mast lifting cylinder the hydraulic fluid exits via an outlet channel 80 and a load break safety device 82 via a line 84 to the hydraulic block.
  • a second lowering path 86 is open in the illustrated position of the valve slide 78 so that the hydraulic fluid can escape via the load breakage safety device 88 in this second lowering path.
  • the valve spool 78 is biased by the spring 92 into its lowering path 86 opening position.
  • the pressure from the lowering path 80 is present at the foot of the valve slide 78 via a throttle 90 .
  • valve slide 78 If this pressure exceeds a minimum limit value, the valve slide 78 is pushed against the force of the spring 92 into a position blocking the lowering path 86 .
  • the valve block 76 is closed via screw plugs 94 and 96, with the screw plug 96 having a passage for an extension 98 of a valve slide 78.
  • the position of the valve slide 76 can be checked from the outside via the extension 98 of the valve slide 78 and its intact functioning can thus be checked.

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

Description

Die vorliegende Erfindung betrifft ein Flurförderzeug mit mindestens einem hydraulischen Masthubzylinder. Der Masthubzylinder ist mit einem Hydraulikblock über eine Hydraulikanordnung verbunden. Die Hydraulikanordnung begrenzt eine Senkgeschwindigkeit des Masthubzylinders.The present invention relates to an industrial truck with at least one hydraulic mast lifting cylinder. The mast lift cylinder is connected to a hydraulic block via a hydraulic assembly. The hydraulic arrangement limits a lowering speed of the mast lifting cylinder.

Hubgerüste an einem Flurförderzeug besitzen in der Regel mindestens einen Masthubzylinder und einen Freihubzylinder. Über den Masthubzylinder werden in dem Hubgerüst Mastabschnitte teleskopisch gegeneinander verschoben. Der Freihubzylinder bewegt ein Lasttragmittel relativ zu einem inneren Mastabschnitt. Zum Zwecke der Risikominderung und durch Normen vorgegeben, ist die maximale Senkgeschwindigkeit eines Hubgerüstes begrenzt. Die Begrenzung wird über die Hydraulikanordnung durch eine entsprechende Drossel erreicht. Vorgesehen ist beispielsweise eine Senkgeschwindigkeit von 0,6 m/s für einen Beladungszustand nahe der Nennlast. Ein Fahrzeugbediener gibt beispielsweise über einen Bedienhebel eine gewünschte Senkgeschwindigkeit vor, die auf ihre Zulässigkeit überprüft wird. Aus Gründen der Sicherheit ist die Hydraulikanordnung zusätzlich mit einer Leitungsbruchsicherung ausgestattet. Die Leitungsbruchsicherung erfüllt die Aufgabe, bei einer gebrochenen Leitung ein Abstürzen der Last zu verhindern.Masts on an industrial truck usually have at least one mast lift cylinder and one free lift cylinder. Via the mast lifting cylinder, mast sections are telescopically displaced in relation to one another in the mast. The free lift cylinder moves a load bearing means relative to an inner mast section. For the purpose of risk reduction and specified by standards, the maximum lowering speed of a mast is limited. The limitation is achieved via the hydraulic system using a corresponding throttle. For example, a lowering speed of 0.6 m/s is planned for a loading condition close to the rated load. A vehicle operator specifies a desired lowering speed, for example, via an operating lever, which is checked for its admissibility. For safety reasons, the hydraulic arrangement is also equipped with a line breakage protection. The line break protection fulfills the task of preventing the load from falling if a line breaks.

Bei bekannten Flurförderzeugen nimmt das Absenken des Lastteils aus großen Hubhöhen nach einem Absetzen der Last einen großen Zeitanteil in Anspruch. Da das Flurförderzeug erst verfahren werden darf, wenn das Lastteil abgesenkt ist, entsteht eine Wartezeit, die sich bei der Arbeit in großen Hubhöhen aufsummieren kann.In known industrial trucks, lowering the load part from great lifting heights after the load has been set down takes a large proportion of the time. Since the industrial truck can only be moved once the load section has been lowered, there is a waiting time that can add up when working at high lift heights.

Aus der EP 0 592 235 A2 ist ein Flurförderzeug gemäß dem Oberbegriff des Hauptanspruchs bekannt, welches eine Hydraulikanordnung aufweist, die die Senkgeschwindigkeit des Masthubzylinders begrenzt. Neben dem Haupthub- und Senkventil sind zwei weitere Ventile vorgesehen, welche geschlossen werden können um die Senkgeschwindigkeit durch Minderung des Volumenstroms zu begrenzen.From the EP 0 592 235 A2 an industrial truck according to the preamble of the main claim is known, which has a hydraulic arrangement which the Mast lift cylinder lowering speed limited. In addition to the main lifting and lowering valve, two further valves are provided, which can be closed to limit the lowering speed by reducing the volume flow.

Der Erfindung liegt die Aufgabe zugrunde, ein Flurförderzeug bereitzustellen, das effizient auch bei großen Hubhöhen eingesetzt werden kann.The object of the invention is to provide an industrial truck that can be used efficiently even with large lifting heights.

Erfindungsgemäß wird die Aufgabe durch ein Flurförderzeug mit Anspruch 1 gelöst. Vorteilhafte Ausgestaltungen bilden die Gegenstände der Unteransprüche.According to the invention, the object is achieved by an industrial truck with claim 1. Advantageous configurations form the subject matter of the dependent claims.

Das erfindungsgemäße Flurförderzeug besitzt mindestens einen hydraulischen Masthubzylinder, der mit einem Hydraulikblock über eine Hydraulikanordnung verbunden ist. Die Hydraulikanordnung begrenzt hierbei die Senkgeschwindigkeit des Masthubzylinders. Erfindungsgemäß ist die Hydraulikanordnung ausgebildet, die Senkgeschwindigkeit lastabhängig auf mindestens zwei Maximalwerte zu begrenzen, von denen ein erster Maximalwert für die Senkgeschwindigkeit bei einem vorbestimmten Lastwert, insbesondere bei Nennlast und ein zweiter Maximalwert für die Senkgeschwindigkeit bei einer zweiten Last kleiner als der ersten Last vorliegt. Der erste Maximalwert ist dabei bevorzugt kleiner als der zweite Maximalwert. Die erfindungsgemäße Lösung schafft die Möglichkeit, den Masthubzylinder lastabhängig mit mindestens zwei unterschiedlichen Senkgeschwindigkeiten abzusenken. Hierbei ist vorgesehen, dass bei einer größeren Belastung der Masthubzylinder mit einer kleineren Senkgeschwindigkeit abgesenkt wird. Bei einer niedrigeren Last oder rein bei seinem Eigengewicht, kann der Masthubzylinder mit einer größeren Geschwindigkeit abgesenkt werden. Durch die erfindungsgemäße Ausgestaltung der Hydraulikanordnung kann also, nach in der Höhe abgesetzter Last, der Hubmast mit großer Geschwindigkeit wieder abgesenkt werden. Bei einem dauerhaften Einsatz eines Flurförderzeugs insbesondere bei großen Hubhöhen entsteht hier durch ein schnelles Leerabsenken und ein deutlich verbessertes Einsatzverhalten des Flurförderzeugs.The industrial truck according to the invention has at least one hydraulic mast lifting cylinder which is connected to a hydraulic block via a hydraulic arrangement. The hydraulic arrangement limits the lowering speed of the mast lifting cylinder. According to the invention, the hydraulic system is designed to limit the lowering speed to at least two maximum values depending on the load, of which there is a first maximum value for the lowering speed at a predetermined load value, in particular at nominal load, and a second maximum value for the lowering speed at a second load that is smaller than the first load. The first maximum value is preferably smaller than the second maximum value. The solution according to the invention creates the possibility of lowering the mast lifting cylinder, depending on the load, with at least two different lowering speeds. It is provided here that the mast lifting cylinder is lowered at a lower lowering speed in the event of a greater load. With a lower load or purely under its own weight, the mast lift cylinder can be lowered at a greater speed. Due to the configuration of the hydraulic arrangement according to the invention, the lifting mast can be lowered again at great speed after the load has been lowered at a height. In the case of long-term use of an industrial truck, particularly at high lifting heights, this results in rapid empty lowering and significantly improved operational behavior of the industrial truck.

In einer bevorzugten Ausgestaltung ist die Hydraulikanordnung mit mindestens zwei voneinander getrennten Senkpfaden ausgestattet. Jeder der Senkpfade besitzt jeweils eine Lastbruchsicherung. Durch die Verwendung von zwei Senkpfaden kann zwischen zwei Senkgeschwindigkeiten umgeschaltet werden. Die Verwendung von zwei Senkpfaden schließt noch nicht zwingend ein, dass nur zwischen zwei Senkgeschwindigkeiten in diskreter Form umgeschaltet werden kann. Es ist durchaus auch denkbar, einen kontinuierlichen Übergang zwischen den beiden voneinander getrennten Senkpfaden vorzusehen. Jeder der Senkpfade ist mit einer Lastbruchsicherung ausgestattet sodass sichergestellt ist, dass für jede der Senkgeschwindigkeiten eine Lastbruchsicherung vorgesehen ist.In a preferred embodiment, the hydraulic system is equipped with at least two separate lowering paths. Each of the lowering paths has a load break safety device. By using two lowering paths, it is possible to switch between two lowering speeds. The usage of Two lowering paths does not necessarily mean that it is only possible to switch between two lowering speeds in discrete form. It is also entirely conceivable to provide a continuous transition between the two lowering paths that are separate from one another. Each of the lowering paths is equipped with a load breaking device to ensure that a load breaking device is provided for each of the lowering speeds.

Bevorzugt definiert jeder der beiden Senkpfade einen maximalen Volumenstrom für die Senkbewegung. Der Volumenstrom bestimmt hierbei im Wesentlichen die Senkgeschwindigkeit des Masthubzylinders.Each of the two lowering paths preferably defines a maximum volume flow for the lowering movement. The volume flow essentially determines the lowering speed of the mast lifting cylinder.

Bei dem erfindungsgemäßen Flurförderzeug wird zwischen dem ersten und dem zweiten Maximalwert mit Hilfe einer Druckwaage umgeschaltet. An der Druckwaage liegt ein Druck aus dem Masthubzylinder als Steuerdruck an. Dieser anliegende Druck kann durchaus auch reduziert oder erhöht sein, damit die Druckwaage anspricht.In the industrial truck according to the invention, a pressure balance is used to switch between the first and the second maximum value. A pressure from the mast lifting cylinder is applied to the pressure compensator as control pressure. This applied pressure can certainly also be reduced or increased so that the pressure compensator responds.

Für das Umschalten zwischen den beiden Maximalwerten für die Senkgeschwindigkeiten ist vorgesehen, entweder ein Sperrventil oder ein Umschaltventil vorzusehen. Im ersteren Fall betätigt die Druckwaage ein Sperrventil, mit dem einer der Senkpfade (Q1) gesperrt, oder zu dem anderen Senkpfad (Q2) zugeschaltet wird, sodass bei gesperrtem Senkpfad der erste Maximalwert und bei zugeschaltetem Senkpfad der zweite Maximalwert als Senkgeschwindigkeit für den Masthubzylinder vorliegt. Mit dem Sperrventil wird ein zweiter Senkpfad wahlweise gesperrt oder parallel zum ersten Senkpfad geschaltet. Mit der Parallelschaltung addiert sich der Volumenstrom der beiden Senkpfade, sodass sich der Volumenstrom addiert und die Senkgeschwindigkeit vergrößert.Provision is made for switching between the two maximum values for the lowering speeds to provide either a check valve or a switching valve. In the first case, the pressure compensator actuates a check valve, with which one of the lowering paths (Q1) is blocked or switched on to the other lowering path (Q2), so that when the lowering path is blocked, the first maximum value and when the lowering path is switched on, the second maximum value is available as the lowering speed for the mast lifting cylinder . With the blocking valve, a second lowering path is either blocked or connected in parallel to the first lowering path. With the parallel connection, the volume flow of the two lowering paths is added, so that the volume flow is added and the lowering speed increases.

In einer bevorzugten Ausgestaltung weist das Sperrventil einen in einem Ventilblock mit einem gegen eine Federkraft vorgespannten Ventilschieber auf, der ansprechend auf einen Druck in dem ersten Senkpfad gegen eine Federvorspannung in eine den zweiten Senkpfad schließende Position vorgeschoben wird. Aufgrund der Federkraft ist der Ventilschieber also in eine Stellung vorgespannt, in der beide Senkpfade parallel geschaltet sind. Ist der Ventilschieber in seiner federvorgespannten Stellung, so sind beide Senkpfade angeschlossen. Steigt der Druck in dem ersten Senkpfad an, so wird dies als Anzeichen für eine große Last genommen und der Ventilschieber in seine Sperrposition vorgeschoben.In a preferred embodiment, the check valve has a in a valve block with a biased against a spring force valve spool, which responds to a pressure in the first lowering path against a spring bias in a den second lowering path closing position is advanced. Because of the spring force, the valve spool is prestressed into a position in which both lowering paths are connected in parallel. If the valve spool is in its spring-loaded position, both lowering paths are connected. If the pressure in the first lowering path increases, this is taken as an indication of a large load and the valve spool is advanced into its blocking position.

In der zweiten bevorzugten Ausgestaltung ist ein Umschaltventil vorgesehen, mit dem zwischen dem ersten Senkpfad und dem zweiten Senkpfad derart umgeschaltet wird, dass entweder der erste Maximalwert bei dem ersten Senkpfad, oder der zweite Maximalwert bei dem zweiten Senkpfad auftritt. Auch das Umschaltventil arbeitet mit einer Druckwaage. Das Umschaltventil weist in einem Ventilblock einen gegen eine Federkraft vorgespannten Ventilschieber auf, der abhängig von seiner Stellung wahlweise einen der Senkpfade sperrt. Hierbei ist der Ventilschieber konstruktiv derart ausgebildet, dass die beiden Senkpfade nur alternativ zueinander gesperrt werden können.In the second preferred embodiment, a changeover valve is provided, which is used to switch between the first lowering path and the second lowering path in such a way that either the first maximum value occurs in the first lowering path or the second maximum value occurs in the second lowering path. The switching valve also works with a pressure compensator. In a valve block, the switchover valve has a valve slide that is preloaded against a spring force and, depending on its position, selectively blocks one of the lowering paths. In this case, the valve slide is constructed in such a way that the two lowering paths can only be blocked alternatively to one another.

Für das erfindungsgemäße Flurförderzeug ist bevorzugt ein Umschaltlastwert vorgesehen, der kleiner oder gleich der Nennlast ist, bei dessen Überschreiten die Senkgeschwindigkeit auf den ersten Maximalwert umgeschaltet wird. Ein solches Verhalten ist Normkonform, da diese sich auf die maximale Senkgeschwindigkeit bei Nennlast bezieht.A switching load value is preferably provided for the industrial truck according to the invention, which is less than or equal to the nominal load, when this is exceeded the lowering speed is switched to the first maximum value. Such behavior conforms to the standard, since it refers to the maximum lowering speed at nominal load.

In einer bevorzugten Weiterbildung ist für einen Freihubzylinder des Flurförderzeugs eine weitere Hydraulikanordnung vorgesehen, die die Senkgeschwindigkeit lastabhängig auf mindestens zwei Maximalwerte begrenzen kann. Wie beim Masthubzylinder kann auch beim Freihubzylinder für eine große Last eine kleinere Senkgeschwindigkeit definiert sein, als für eine kleinere Last, die auch im Freihub eine größere Senkgeschwindigkeit zulässt.In a preferred development, a further hydraulic arrangement is provided for a free lift cylinder of the industrial truck, which can limit the lowering speed to at least two maximum values depending on the load. As with the mast lift cylinder, a lower lowering speed can also be defined for a large load in the free lift cylinder than for a smaller load, which also allows a higher lowering speed in free lift.

Die vorliegende Erfindung wird anhand von zwei Ausführungsbeispielen näher erläutert. Es zeigen:

Fig. 1
einen hydraulischen Schaltplan mit einem Sperrventil zwischen einem ersten und einem zweiten Senkpfad,
Fig. 2
ein zweites Ausführungsbeispiel mit einem Umschaltventil zwischen dem ersten und dem zweiten Senkpfad,
Fig. 3
eine schematische Ansicht einer Hydraulikanordnung mit einem Sperrventil,
Fig.4
eine schematische Ansicht einer Hydraulikanordnung mit einem Umschaltventil und
Fig. 5
eine schematische Ansicht einer Hydraulikanordnung mit einem anderen Sperrventil, das von dem in Fig. 3 verschieden ist.
The present invention is explained in more detail using two exemplary embodiments. Show it:
1
a hydraulic circuit diagram with a check valve between a first and a second lowering path,
2
a second embodiment with a switching valve between the first and the second lowering path,
3
a schematic view of a hydraulic system with a check valve,
Fig.4
a schematic view of a hydraulic system with a switching valve and
figure 5
a schematic view of a hydraulic arrangement with a different blocking valve, which is different from that in 3 is different.

Figur 1 zeigt in einer schematischen Ansicht zwei Masthubzylinder 10 sowie einen Freihubzylinder 12. Die Unterscheidung zwischen Masthubzylinder und Freihubzylinder ergibt sich aus der Anordnung und Wirkungsweise der hydraulischen Zylinder in einem Hubgerüst. Das Hubgerüst besitzt mehrere teleskopierbare Mastabschnitte, wobei die Mastabschnitte relativ zueinander durch die Masthubzylinder verfahren werden. Der Freihubzylinder hebt das Lasttragmittel relativ zu dem am weitesten anhebbaren Mastabschnitt. figure 1 shows two mast lift cylinders 10 and one free lift cylinder 12 in a schematic view. The distinction between mast lift cylinders and free lift cylinders results from the arrangement and mode of operation of the hydraulic cylinders in a mast. The mast has several telescoping mast sections, the mast sections being moved relative to one another by the mast lifting cylinder. The free lift cylinder lifts the load carrying means relative to the mast section that can be raised the furthest.

Masthubzylinder 12 und Freihubzylinder 10 werden gemeinsam über einen Hydraulikblock (nicht dargestellt) mit einem Hydraulikfluid versorgt. Hierbei sind die Zylinder an einem Hydraulikblock angeschlossen, dessen Ausgangsleitung 14 die Eingangsleitung zu den Hydraulikanordnungen 16 und 18 besitzt. Die Hydraulikanordnungen 16 besitzen zwei Senkpfade 20, 22, während in dem dargestellten Ausführungsbeispiel der Freihubzylinder 12 nur einen einzigen Senkpfad 24 besitzt. Jeder der Senkpfade 20, 22, 24 besitzt eine Lastbruchsicherung (LBS), die im Falle eines Fehlers ein langsames kontrolliertes Senken selbst bei Last sicherstellt. Lastbruchsicherungen LBS sind allgemein aus dem Stand der Technik bekannt. Schematisch dargestellt ist die Lastbruchsicherung als ein über eine Druckwaage geschaltetes Ventil. Hierbei wird der zylinderseitige Druck 26 mit einem stromabwärts liegenden gedrosselten Druck 28 verglichen. Ist die Druckdifferenz nicht zu groß, so wird ein Senken stromabwärts zugelassen. Ist dagegen aufgrund beispielsweise eines Leitungsbruchs die Druckdifferenz zu groß, so wird eine weitere Drossel 30 eingeschaltet, über die stark gedrosselt der Senkvorgang fortgesetzt wird.Mast lifting cylinder 12 and free lifting cylinder 10 are jointly supplied with hydraulic fluid via a hydraulic block (not shown). Here, the cylinders are connected to a hydraulic block whose output line 14 has the input line to the hydraulic assemblies 16 and 18 . The Hydraulic assemblies 16 have two lowering paths 20, 22, while in the illustrated embodiment the free lift cylinder 12 has only a single lowering path 24. Each of the lowering paths 20, 22, 24 has a load breakage safety device (LBS), which ensures slow, controlled lowering even under load in the event of a fault. Load breakage devices LBS are generally known from the prior art. The load break safety device is shown schematically as a valve switched via a pressure compensator. Here, the cylinder-side pressure 26 is compared to a throttled pressure 28 downstream. If the pressure differential is not too great, then downslope is allowed downstream. If, on the other hand, the pressure difference is too large, for example due to a line break, a further throttle 30 is switched on, via which the lowering process is continued in a heavily throttled manner.

Bei der Ausführung in Figur 1 ist für die beiden Masthubzylinder 10 ein Sperrventil 30 vorgesehen. Das Sperrventil 30 ist für einen nicht zu großen Druck in dem Masthubzylinder in die dargestellte Position über eine Feder 32 vorgespannt. In dieser Position ist das Sperrventil 30 geöffnet und der Masthubzylinder 10 wird über beide Senkpfade 36, 38 abgesenkt. Die Senkpfade 36 und 38 sind parallel geschaltet, sodass sich deren Volumenströme addieren und damit die Senkgeschwindigkeit vergrößert.When running in figure 1 a check valve 30 is provided for the two mast lifting cylinders 10 . The check valve 30 is biased into the position shown by a spring 32 so that the pressure in the mast lifting cylinder is not too great. In this position, the check valve 30 is open and the mast lifting cylinder 10 is lowered via both lowering paths 36, 38. The lowering paths 36 and 38 are connected in parallel, so that their volume flows add up and the lowering speed is thus increased.

Liegt an dem Hydraulikzylinder 10 eine zu große Last an, so steigt der Druck an der Steuerleitung 34 und das Sperrventil 30 schaltet in seine sperrende Position. Hierdurch wird der Senkpfad 36 gesperrt und ein Absenken des Masthubzylinders 10 erfolgt ausschließlich über den Senkpfad 38.If the load on the hydraulic cylinder 10 is too great, the pressure on the control line 34 increases and the check valve 30 switches to its locking position. As a result, the lowering path 36 is blocked and the mast lifting cylinder 10 is lowered exclusively via the lowering path 38.

In der praktischen Umsetzung ist das Sperrventil 30 derart dimensioniert, dass bei annähender Nennlast dieses sperrt und über dem Senkpfad 38 mit der zugelassenen Senkgeschwindigkeit die Last bzw. der Abschnitt des Hubgerüsts gesenkt wird.In practical implementation, the blocking valve 30 is dimensioned such that when the nominal load is approached, it blocks and the load or section of the mast is lowered via the lowering path 38 at the permitted lowering speed.

Figur 2 zeigt in einer schematischen Ansicht eine alternative Ausgestaltung der Erfindung. Hierbei sind gleiche Bauteile mit gleichen Bezugszeichen belegt. Auch in dieser Ausgestaltung sind für die beiden Masthubzylinder 10 jeweils zwei Senkpfade 36, 38 vorgesehen. Anders als im ersten Ausführungsbeispiel ist hier ein Umschaltventil 40 vorgesehen, mit dem wahlweise zwischen dem Senkpfad 36 und dem Senkpfad 38 umgeschaltet wird. In der in Fig. 2 dargestellten Position erfolgt der Senkvorgang über den Senkpfad 32. Das Sperrventil 40 befindet sich in seiner durch die Feder 42 vorgespannten Position. Steigt der Druck in dem Masthubzylinder 10, so wird das Sperrventil 40 über die Steuerseite 44 umgeschaltet und der Senkvorgang erfolgt ausschließlich über den Senkpfad 38. Bei einer erfindungsgemäßen Ausgestaltung ist der Senkpfad 38 derart dimensioniert, dass bei Nennlast eine maximal zulässige Senkgeschwindigkeit nicht überschritten wird. Ist dagegen die Last kleiner als Nennlast, so wird auf den anderen Senkpfad 36 umgeschaltet, der beispielsweise einen deutlich größeren Volumenstrom besitzt und damit eine größere Senkgeschwindigkeit zulässt. Beide Senkpfade 36 und 38 besitzen jeweils ihre eigene entsprechend ausgelegte Lastbruchsicherung. figure 2 shows an alternative embodiment of the invention in a schematic view. In this case, the same components are given the same reference symbols. Two lowering paths 36, 38 are provided for each of the two mast lifting cylinders 10 in this embodiment as well. In contrast to the first exemplary embodiment, a changeover valve 40 is provided here, with which it is optionally possible to switch between the lowering path 36 and the lowering path 38 . in the in 2 the position shown, the lowering process takes place via the lowering path 32. The check valve 40 is in its prestressed position by the spring 42. If the pressure in the mast lifting cylinder 10 increases, the check valve 40 is switched over via the control side 44 and the lowering process takes place exclusively via the lowering path 38. In an embodiment according to the invention, the lowering path 38 is dimensioned in such a way that a maximum permissible lowering speed is not exceeded at nominal load. If, on the other hand, the load is less than the nominal load, a switch is made to the other lowering path 36, which has a significantly larger volume flow, for example, and thus allows a higher lowering speed. Both lowering paths 36 and 38 each have their own appropriately designed load break protection.

Fig. 3 zeigt eine schematische Ansicht einer Hydraulikanordnung gemäß Figur 1 mit einer praktischen Umsetzung des Sperrventils. In Fig. 3 ist ein Innenraum 46 eines Masthubzylinders gezeigt, der mit zwei Senkpfaden 48, 50 verbunden ist. Beide Senkpfade 48, 50 besitzen jeweils eine schematisch dargestellte Lastbruchsicherung 52. In dem Senkkanal 48 ist ein Ventilschieber 54 angeordnet, der über eine Feder 56 in eine den Senkpfad freigebende Position vorgespannt ist. Steigt der Druck in dem Senkpfad 48, so wird der Ventilschieber 54 gegen die Spannung der Feder 56 verschoben und sperrt somit den Senkpfad 48. In diesem Fall ist nur der Senkpfad 50 in Betrieb, um das Hydraulikfluid über eine angeschlossene Leitung 58 abzuleiten. Die Senkpfade 48 und 50 sind jeweils über Verschlussschrauben 60 verschlossen. 3 shows a schematic view of a hydraulic arrangement according to FIG figure 1 with a practical implementation of the check valve. In 3 an interior space 46 of a mast lifting cylinder is shown, which is connected to two lowering paths 48,50. Both lowering paths 48, 50 each have a load break safety device 52, shown schematically. A valve slide 54 is arranged in the lowering channel 48 and is prestressed by a spring 56 into a position releasing the lowering path. If the pressure in the lowering path 48 increases, the valve spool 54 is displaced against the tension of the spring 56 and thus blocks the lowering path 48. In this case, only the lowering path 50 is in operation in order to drain the hydraulic fluid via a connected line 58. The lowering paths 48 and 50 are each closed via screw plugs 60 .

Fig. 4 zeigt in einer schematischen Ansicht ein Umschaltventil, bei dem über einen Ventilschieber 62 zwischen einem ersten Pfad 64 und einem zweiten Pfad 66 umgeschaltet wird. Jeder der Pfade 64 und 66 besitzt eine Lastbruchsicherung 68, 70. Der Ventilschieber 62 ist durch die Feder 72 in eine den Pfad 66 sperrende Position vorgespannt. Steigt der Druck in einer Leitung 63 an, so wird der Ventilschieber 62 entgegen der Federkraft 72 in seine den mit dem Umgebungsdruck bzw. aus dem Senkpfad verbundenen Pfad 65 sperrende Position geschoben, in der der Pfad 66 freigegeben ist. Der Ventilschieber 62 stellt sich in Abhängigkeit von der Druckdifferenz zwischen Senkpfad und Hydraulikzylinder ein. Eine für das Umschalten notwendige Druckdifferenz wird durch die Feder 72 bestimmt. 4 shows a schematic view of a switchover valve in which a valve slide 62 is used to switch between a first path 64 and a second path 66 . Each of the paths 64 and 66 has a load break safety device 68, 70. The valve spool 62 is biased by the spring 72 in a path 66 blocking position. If the pressure in a line 63 increases, the valve slide 62 is pushed against the spring force 72 into its position blocking the path 65 connected to the ambient pressure or from the lowering path, in which position the path 66 is released. The valve slide 62 adjusts depending on the pressure difference between the lowering path and the hydraulic cylinder. A pressure difference necessary for switching is determined by the spring 72 .

Fig. 5 zeigt in einer schematischen Ansicht eine Ausgestaltung eines Sperrventils 74. Das Sperrventil 74 besitzt einen Ventilblock 76, in dem zentral ein Ventilschieber 78 angeordnet ist. In einer von dem Masthubzylinder kommenden Leitung 81 tritt das Hydraulikfluid über einen Austrittskanal 80 und eine Lastbruchsicherung 82 über eine Leitung 84 zu dem Hydraulikblock aus. Ein zweiter Senkpfad 86 ist in der dargestellten Position des Ventilschiebers 78 geöffnet, sodass das Hydraulikfluid in diesem zweiten Senkpfad über die Lastbruchsicherung 88 austreten kann. Der Ventilschieber 78 ist über die Feder 92 in seine den Senkpfad 86 öffnende Position vorgespannt. Über eine Drossel 90 liegt der Druck aus dem Senkpfad 80 am Fuß des Ventilschiebers 78 an. Übersteigt dieser Druck einen Mindestgrenzwert, so wird der Ventilschieber 78 gegen die Kraft der Feder 92 in eine den Senkpfad 86 versperrende Position geschoben. Der Ventilblock 76 ist über Verschlussschrauben 94 und 96 verschlossen, wobei die Verschlussschraube 96 eine Durchführung für einen Fortsatz 98 eines Ventilschiebers 78 besitzt. Über den Fortsatz 98 des Ventilschiebers 78 kann die Position des Ventilschiebers 76 von außen kontrolliert und damit seine intakte Funktionsweise geprüft werden. figure 5 shows a schematic view of an embodiment of a check valve 74. The check valve 74 has a valve block 76 in which a valve slide 78 is arranged centrally. In a line 81 coming from the mast lifting cylinder, the hydraulic fluid exits via an outlet channel 80 and a load break safety device 82 via a line 84 to the hydraulic block. A second lowering path 86 is open in the illustrated position of the valve slide 78 so that the hydraulic fluid can escape via the load breakage safety device 88 in this second lowering path. The valve spool 78 is biased by the spring 92 into its lowering path 86 opening position. The pressure from the lowering path 80 is present at the foot of the valve slide 78 via a throttle 90 . If this pressure exceeds a minimum limit value, the valve slide 78 is pushed against the force of the spring 92 into a position blocking the lowering path 86 . The valve block 76 is closed via screw plugs 94 and 96, with the screw plug 96 having a passage for an extension 98 of a valve slide 78. The position of the valve slide 76 can be checked from the outside via the extension 98 of the valve slide 78 and its intact functioning can thus be checked.

Bezugszeichenlistereference list

1010
Masthubzylindermast lift cylinder
1212
Freihubzylinderfree lift cylinder
1414
Ausgangsleitungoutput line
16, 1816, 18
Hydraulikanordnungenhydraulic arrangements
20, 22, 2420, 22, 24
Senkpfadesink paths
2626
zylinderseitiger Druckcylinder side pressure
2828
gedrosselter Druckthrottled pressure
3030
Sperrventilcheck valve
3232
Feder / Senkpfadspring / sink path
3434
Steuerleitungcontrol line
36,3836.38
Senkpfadesink paths
4040
Umschaltventil/SperrventilReversing valve/blocking valve
4242
FederFeather
4444
Steuerseitecontrol side
4646
Innenrauminner space
48,5048.50
Senkpfadesink paths
5252
Lastbruchsicherungload break protection
5454
Ventilschiebervalve spool
5656
FederFeather
5858
LeitungManagement
6060
Verschlussschraubenscrew plugs
6262
Ventilschiebervalve spool
6464
erster Pfadfirst path
6666
zweiter Pfadsecond path
68, 7068, 70
Lastbruchsperreload breaking lock
7272
FederFeather
7474
Sperrventilcheck valve
7676
Ventilblockvalve block
7878
Ventilschiebervalve spool
8080
Austrittskanalexit channel
8181
LeitungManagement
8282
Lastbruchsicherungload break protection
8484
LeitungManagement
8686
zweiter Senkpfadsecond descent path
8888
Lastbruchsicherungload break protection
9090
Drosselthrottle
9292
FederFeather
94, 9694, 96
VerschlussschraubeScrew
9898
Fortsatzextension

Claims (11)

  1. . An industrial truck with at least one hydraulic mast lifting cylinder (10) that is connected to a hydraulic block via a hydraulic assembly (16, 18) that limits a lowering speed of the mast lifting cylinder (10), wherein the hydraulic assembly (16, 18) is designed to limit the lowering speed to at least two maximum values depending on the load, a first maximum value for the lowering speed being provided at a first predetermined load value and a second maximum value for the lowering speed being provided at a second load value that is less than the first load value, characterized in that switching takes place between the first and second maximum value by means of a pressure balance to which a pressure that depends on the pressure in the mast lifting cylinder (10) is applied.
  2. . The industrial truck according to claim 1, characterized in that the first predetermined load value corresponds to the nominal load.
  3. . The industrial truck according to claim 1 or 2, characterized in that the first maximum value is less than the second maximum value.
  4. . The industrial truck according to any one of claims 1 to 3, characterized in that the hydraulic assembly (16, 18) comprises at least two separate lowering paths (20, 22) with one load break switch (LBS) (52) each.
  5. . The industrial truck according to claim 4, characterized in that each of the lowering paths (20, 22, 24) defines a maximum volumetric flow rate (Q) for a lowering movement of the mast lifting cylinder (10).
  6. . The industrial truck according to any one of claims 1 to 4, characterized in that the pressure balance actuates a shut-off valve (30) by means of which one of the lowering paths (Q1) (20, 22, 24) is blocked or by means of which a switch is made to the other lowering path (Q2) (48), such that the first maximum value is provided in the case of a blocked lowering path and the second maximum value is provided in the case of an activated lowering path as the lowering speed for the mast lifting cylinder (10).
  7. . The industrial truck according to claim 6, characterized in that the shut-off valve (30) comprises a valve block with a valve spool (54) that is preloaded against a spring force (56) and that is shifted against its spring preload into a position blocking the second lowering path (66) in response to a pressure in the first lowering path (64).
  8. . The industrial truck according to any one of claims 1 to 4, characterized in that the pressure balance actuates a switching valve (40) by means of which a switch is made between the first lowering path (64) and the second lowering path (66) in such a way that either the first maximum value occurs for the first lowering path (64) or the second maximum value occurs for the second lowering path (66).
  9. . The industrial truck according to claim 8, characterized in that the switching valve (40) comprises a valve block (76) with a valve spool (54) that is preloaded against a spring force and that selectively blocks one of the lowering paths (64, 66) depending on its position.
  10. . The industrial truck according to any one of claims 1 to 9, characterized in that a switching load value is provided which is less than or equal to the first load value and, when said switching load value is exceeded, the lowering speed is switched to the first maximum value.
  11. . The industrial truck according to any one of claims 1 to 10, characterized in that another hydraulic assembly (18) that limits the lowering speed to at least two maximum values depending on the load is provided for a free lift cylinder (12).
EP19158782.3A 2018-02-28 2019-02-22 Industrial truck with at least one hydraulic mast lifting cylinder Active EP3533752B1 (en)

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DE102018104586.7A DE102018104586A1 (en) 2018-02-28 2018-02-28 Truck with at least one hydraulic mast lifting cylinder

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US20190263648A1 (en) 2019-08-29
EP3533752A1 (en) 2019-09-04
US11377334B2 (en) 2022-07-05

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