EP0908413A2 - Lift truck with a load grasping device and method for descending the load grasping device - Google Patents

Lift truck with a load grasping device and method for descending the load grasping device Download PDF

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Publication number
EP0908413A2
EP0908413A2 EP98118873A EP98118873A EP0908413A2 EP 0908413 A2 EP0908413 A2 EP 0908413A2 EP 98118873 A EP98118873 A EP 98118873A EP 98118873 A EP98118873 A EP 98118873A EP 0908413 A2 EP0908413 A2 EP 0908413A2
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EP
European Patent Office
Prior art keywords
hydraulic pump
suspension device
load
industrial truck
electric motor
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Granted
Application number
EP98118873A
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German (de)
French (fr)
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EP0908413B1 (en
EP0908413A3 (en
Inventor
Hartmut Nedele
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Still Wagner GmbH and Co KG
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Still Wagner GmbH and Co KG
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Publication of EP0908413A3 publication Critical patent/EP0908413A3/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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/003—Systems with load-holding valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
    • F15B21/14—Energy-recuperation means

Definitions

  • the invention relates to an industrial truck with a vertically movable Load suspension device, wherein a device for moving the vertical Load suspension device at least one hydraulic cylinder and at least one has a hydraulic pump which can be driven by an electric motor and which driven hydraulic pump has a pressure side and a suction side.
  • the invention also relates to a method for lowering a vertically movable Load suspension device on an industrial truck, the industrial truck a Device for vertically moving the load suspension device at least one Hydraulic cylinder and at least one driven by an electric motor Has hydraulic pump.
  • DC shunt motors are used with industrial trucks, especially with Drawbar-guided industrial trucks such as Pallet truck or pallet truck for Drive of the lifting device or for the travel drive is generally known.
  • the present invention has for its object a truck and a Method for lowering the load suspension device on the industrial truck To provide a quick lowering of the load suspension device without Allow load.
  • the suction side the driven hydraulic pump can be connected to the hydraulic cylinder. If the suction side of the hydraulic pump is connected to the hydraulic cylinder and the Hydraulic pump driven by the electric motor sucks the Hydraulic pump hydraulic oil from the hydraulic cylinder on. Lowering the This accelerates the load suspension device. Such an acceleration The lowering is particularly useful when on the load suspension device there is no load, since this means uncomfortable waiting times for the operator of the Industrial truck can be prevented. If on the Load suspension device, however, is a larger load that a lowering with sufficient speed, driving the hydraulic pump is not required. It is possible, for example, the non-electrically driven one Let the hydraulic pump run without power, or use it for energy recovery to take advantage of.
  • the hydraulic pump has a lifting mechanism the load suspension device has a predetermined main conveying direction, and has the hydraulic pump one during the lowering of the load suspension device Main conveying direction opposite conveying direction.
  • the direction of rotation of the Electric motor and thus the hydraulic pump is thus used to lower the Reverse load handler.
  • the hydraulic pump a predetermined main conveying direction for lifting the load suspension device on, and has the hydraulic pump during the lowering of the Load suspension device rectified to the main conveying direction Direction of conveyance.
  • the hydraulic cylinder with the suction side of the Hydraulic pump can be connected by means of a bypass line.
  • the bypass line is closable by means of a check valve which is used to lower the Load suspension device is opened.
  • the hydraulic pump with the hydraulic cylinder is expediently connecting line connectable to a tank by means of a drain line.
  • a part of the hydraulic oil flowing through the pump and / or part of that Hydraulic cylinder flowing oil flow can through the drain line into the tank flow out.
  • the lowering speed and the lifting speed of the Load suspension device can depend on the switching position of the drain valve can be adjusted continuously.
  • the drain valve is designed as a seat valve is.
  • Seat valves are simple and inexpensive to manufacture, on the one hand, and are due to their design, they are absolutely tight in the closed position, making them unintentional Lowering the load suspension device is safely avoided.
  • the drain valve and / or the electric motor are by means of an electric Pulse control unit controllable.
  • the electric motor is externally excited DC shunt motor is executed.
  • separately excited DC shunt motors can control the torque and speed independently can be adjusted from each other, whereby the use of the electric motor for Accelerating the lowering of the load suspension device is made possible.
  • the industrial truck as a pallet truck is preferably designed as a pedestrian-controlled high-lift truck.
  • a Drawbar pallet stacker it is necessary to move the Control the load handler with an electrical switch, because larger Switching elements cannot be arranged on the drawbar.
  • the lifting device of this type of truck usually has a relative light weight, so that the acceleration of the lowering movement is a special is of great importance.
  • the invention now enables fast Control the lowering of the load suspension device from the drawbar.
  • the object is achieved in that certain Control signals and / or operating parameters during the lowering of the Load suspension device using the hydraulic pump hydraulic oil from the Hydraulic cylinder is sucked.
  • Speed setpoints for lowering the load suspension device can be specified are, the electric motor at a low speed setpoint Hydraulic pump does not drive and at a high speed setpoint the Electric motor drives the hydraulic pump.
  • Figure 1 shows a hydraulic circuit for a lifting device industrial truck according to the invention.
  • a drivable by an electric motor 1 Hydraulic pump 2 is connected to a pressureless tank 4 via a line 3.
  • a hydraulic cylinder 5 For lifting the load suspension device by means of a hydraulic cylinder 5 drives the electric motor 1 turns on the hydraulic pump 2 in a direction in which the Pressure side of the hydraulic pump 2 is located in the drawing above.
  • the Hydraulic pump 2 thus pumps hydraulic oil from the tank 4 through the Check valve 7, which is in the position shown here, in the Line 6.
  • a continuously adjustable, designed as a seat valve Drain valve 8 can be a part of the hydraulic oil delivered with the hydraulic pump 2 in the depressurized tank 4 are drained. The rest of the pump 2 Hydraulic oil is supplied to the hydraulic cylinder 5. With the drain valve 8 can thus the lifting speed of the load suspension device can be set.
  • Hydraulic oil from the Hydraulic cylinder 5 drained. To do this, first use a switching magnet the check valve 7 opened. Hydraulic oil can then be pumped through the hydraulic pump 2 drain off, this oil flow the hydraulic pump 2 and thus the electric motor 1st drives. The electric motor 1 is operated as a generator, which for Energy recovery can be exploited. To lower the To accelerate the load suspension device, the drain valve 8 be opened, the speed of the lowering movement over the Opening width of the drain valve 8 can be adjusted. To a maximum To achieve lowering speed of the load suspension device According to the invention, the hydraulic pump 2 by the electric motor 1 in the direction driven, in which the suction side of the hydraulic pump 2 in the drawing above located. Hydraulic oil from hydraulic cylinder 5 is thus pumped 2 sucked in.
  • Electric motor 1 designed as a pulse-controlled direct current shunt motor become. It is also possible to use the electric motor as a three-phase asynchronous motor to execute.
  • FIG. 2 shows a further embodiment for the lifting device industrial truck according to the invention.
  • To raise the load handler is pump 2 a hydraulic oil from the tank 4 through two check valves 10, 11 pumped into the hydraulic cylinder 5.
  • One arranged in a bypass line 12 switchable check valve 13 is located in the shut-off Position.
  • the check valve 13 is opened.
  • the Hydraulic oil flowing out of the hydraulic cylinder 5 can then via the Bypass line through hydraulic pump 2a and drain valve 8 into tank 5 flow away.
  • the drain valve 8 With the drain valve 8, the lowering speed of Load suspension device set. This can, especially if the Load handling device is a large load, with the hydraulic pump 2a and the electric motor 1a energy can be recovered.
  • the lowering movement can be carried out by the hydraulic pump 2a Electric motor 1a are driven, which in this embodiment Suction side of the hydraulic pump 2a is located in the drawing below.
  • This one too Embodiment is an embodiment of the electric motor 1a as a DC shunt motor or useful as a three-phase asynchronous motor.
  • Figure 3a shows the sizes of the control signal 17 for the check valve 7 or Check valve 13, the control signal 18 for the drain valve 8 and the control signal 19th for the electric motor 1 or 1a above that specified by the operator Setpoint 20 for the lowering speed.
  • This diagram shows that the check valve 7 and the check valve 13 when the Load suspension device are always open.
  • the drain valve 8 will rise of the setpoint 20 for the lowering speed opened continuously. If the Setpoint for the lowering speed has almost reached its maximum value, is with the control signal 19, the electric motor 1 or 1a with the corresponding direction of rotation switched on to the lowering movement of the Support load suspension device.
  • Figure 3b shows the corresponding quantities of the control signal 17a for the Check valve 7 or the check valve 13, the control signal 18a for the drain valve 8 and the control signal 19a for the electric motor 1 or 1a above that by the Operator specified target value 20a for the lifting speed.
  • the Check valve 7 and the check valve 13 are always in during lifting the positions shown in Figures 1 and 2.
  • the electric motor 1 or 1a Always operate with the appropriate direction of rotation during lifting. With The drain valve 8 becomes the setpoint 20a for the lifting speed continuously closed further, reducing the actual lifting speed is increased.
  • All control signals according to Fig. 3a and 3b are preferably with or generated several pulse control units and are thus of pulse-shaped Voltages shown.

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

Abstract

The load handling vehicle has at least one hydraulic cylinder (5) and at least one hydraulic pump (2a) driven by an electric motor (1a) for vertical movement of the load lifting device. The suction side of the pump is coupled to the hydraulic cylinder, with control of the lifting and lowering of the load via a continuously adjustable electrical switch element in conjunction with an electrical pulse control stage. Independent claims are also included for a load lifting and lowering method for a load handling vehicle.

Description

Die Erfindung betrifft ein Flurförderzeug mit einer vertikal beweglichen Lastaufnahmevorrichtung, wobei eine Vorrichtung zum vertikalen Bewegen der Lastaufnahmevorrichtung mindestens einen Hydraulikzylinder und mindestens eine mittels eines Elektromotors antreibbare Hydraulikpumpe aufweist und die angetriebene Hydraulikpumpe eine Druckseite und eine Saugseite aufweist. Die Erfindung betrifft ebenfalls ein Verfahren zum Absenken einer vertikal beweglichen Lastaufnahmevorrichtung an einem Flurförderzeug, wobei das Flurförderzeug eine Vorrichtung zum vertikalen Bewegen der Lastaufnahmevorrichtung mindestens einen Hydraulikzylinder und mindestens eine mittels eines Elektromotors antreibbare Hydraulikpumpe aufweist.The invention relates to an industrial truck with a vertically movable Load suspension device, wherein a device for moving the vertical Load suspension device at least one hydraulic cylinder and at least one has a hydraulic pump which can be driven by an electric motor and which driven hydraulic pump has a pressure side and a suction side. The The invention also relates to a method for lowering a vertically movable Load suspension device on an industrial truck, the industrial truck a Device for vertically moving the load suspension device at least one Hydraulic cylinder and at least one driven by an electric motor Has hydraulic pump.

Flurförderzeuge der genannten Art weisen in der Regel ein Hubgerüst auf, an dem die Lastaufnahmevorrichtung auf- und abbewegbar befestigt ist. Das Anheben der Lastaufnahmevorrichtung erfolgt mittels eines Hydraulikzylinders, der mit einer Hydraulikpumpe verbunden ist. Zum Absenken der Lastaufnahmevorrichtung wird bei den Flurförderzeugen des Standes der Technik der Hydraulikzylinder über ein Ventil mit einem Tank verbunden. Das in dem Hydraulikzylinder befindliche Hydrauliköl strömt dann infolge des Gewichts der Lastaufnahmevorrichtung und des Gewichts einer auf der Lastaufnahmevorrichtung möglicherweise befindlichen Last in den Tank ab. Bekannt ist es ebenfalls, das während des Absenkens aus dem Hydraulikzylinder strömende Hydrauliköl durch die Hydraulikpumpe zu leiten, der in dieser Betriebssituation dann als hydraulischer Motors betrieben wird und den Elektromotor, der dann als Generator arbeitet, antreibt. Mit dieser Anordnung kann die während des Absenkens freiwerdende potentielle Energie der Last zurückgewonnen werden. Der elektrische Motor ist hierbei vorzugsweise als fremderregter Gleichstrom-Nebenschlußmotor ausgeführt. Die Verwendung von Gleichstrom-Nebenschlußmotoren ist bei Flurförderzeugen, insbesondere auch bei deichselgeführten Flurförderzeugen wie z.B. Nieder- oder Hochhubwagen, für den Antrieb der Hubvorrichtung oder für den Fahrantrieb allgemein bekannt.Industrial trucks of the type mentioned generally have a mast on which the Load suspension device is attached up and down movable. Raising the Load suspension device is carried out by means of a hydraulic cylinder with a Hydraulic pump is connected. To lower the load suspension device at the industrial trucks of the hydraulic cylinders via a valve connected to a tank. The hydraulic oil in the hydraulic cylinder then flows due to the weight of the load handling device and the weight a possible load on the load suspension device in the tank from. It is also known that during the lowering from the hydraulic cylinder flowing hydraulic oil through the hydraulic pump, which is in this Operating situation is then operated as a hydraulic motor and the electric motor, which then works as a generator. With this arrangement, the during Lowering the potential energy released by the load. Of the electric motor is preferably an externally excited direct current shunt motor executed. The use of DC shunt motors is with industrial trucks, especially with Drawbar-guided industrial trucks such as Pallet truck or pallet truck for Drive of the lifting device or for the travel drive is generally known.

Flurförderzeuge des Standes der Technik weisen, unabhängig von der beschriebenen Möglichkeit der Energierückgewinnung den Nachteil auf, daß ein Absenken der Lastaufnahmevorrichtung ohne Last oftmals relativ langsam erfolgt, da das in dem Hydraulikzylinder befindliche Öl lediglich einen geringen Druck aufweist und aus diesem Grund nur sehr langsam durch das Ventil in den Tank abströmen kann.Industrial trucks of the prior art have, regardless of the described Possibility of energy recovery has the disadvantage that lowering the Load suspension device without load is often relatively slow, because that in the Hydraulic cylinder located oil only has a low pressure and from for this reason can only flow very slowly through the valve into the tank.

Der vorliegenden Erfindung liegt die Aufgabe zugrunde, ein Flurförderzeug und ein Verfahren zum Absenken der Lastaufnahmevorrichtung an dem Flurförderzeug zur Verfügung zu stellen, um ein schnelles Absenken der Lastaufnahmevorrichtung ohne Last zu ermöglichen.The present invention has for its object a truck and a Method for lowering the load suspension device on the industrial truck To provide a quick lowering of the load suspension device without Allow load.

Diese Aufgabe wird bezüglich des Flurförderzeugs dadurch gelöst, daß die Saugseite der angetriebenen Hydraulikpumpe mit dem Hydraulikzylinder verbindbar ist. Wenn die Saugseite der Hydraulikpumpe mit dem Hydraulikzylinder verbunden ist und die Hydraulikpumpe mittels des Elektromotors angetrieben wird, saugt die Hydraulikpumpe Hydrauliköl aus dem Hydraulikzylinder an. Das Absenken der Lastaufnahmevorrichtung wird dadurch beschleunigt. Eine solche Beschleunigung des Absenkens ist insbesondere sinnvoll, wenn sich auf der Lastaufnahmevorrichtung keine Last befindet, da hiermit unangenehme Wartezeiten für die Bedienperson des Flurförderzeugs verhindert werden können. Wenn sich auf der Lastaufnahmevorrichtung jedoch eine größere Last befindet, die ein Absenken mit ausreichender Geschwindigkeit bewirkt, ist ein Antreiben der Hydraulikpumpe nicht erforderlich. Es ist beispielsweise möglich, die nicht elektrisch angetriebene Hydraulikpumpe kraftlos mitlaufen zu lassen, oder sie zur Energierückgewinnung auszunutzen.This object is achieved with regard to the industrial truck in that the suction side the driven hydraulic pump can be connected to the hydraulic cylinder. If the suction side of the hydraulic pump is connected to the hydraulic cylinder and the Hydraulic pump driven by the electric motor sucks the Hydraulic pump hydraulic oil from the hydraulic cylinder on. Lowering the This accelerates the load suspension device. Such an acceleration The lowering is particularly useful when on the load suspension device there is no load, since this means uncomfortable waiting times for the operator of the Industrial truck can be prevented. If on the Load suspension device, however, is a larger load that a lowering with sufficient speed, driving the hydraulic pump is not required. It is possible, for example, the non-electrically driven one Let the hydraulic pump run without power, or use it for energy recovery to take advantage of.

Gemäß einer vorteilhaften Ausführungsform weist die Hydraulikpumpe zum Anheben der Lastaufnahmevorrichtung eine vorgegebene Hauptförderrichtung auf, und weist die Hydraulikpumpe während des Absenkens der Lastaufnahmevorrichtung eine zur Hauptförderrichtung entgegengesetzte Förderrichtung auf. Die Drehrichtung des Elektromotors und damit der Hydraulikpumpe wird somit zum Absenken der Lastaufnahmevorrichtung umgekehrt.According to an advantageous embodiment, the hydraulic pump has a lifting mechanism the load suspension device has a predetermined main conveying direction, and has the hydraulic pump one during the lowering of the load suspension device Main conveying direction opposite conveying direction. The direction of rotation of the Electric motor and thus the hydraulic pump is thus used to lower the Reverse load handler.

In einer anderen, ebenso vorteilhaften Ausführungsform weist die Hydraulikpumpe zum Anheben der Lastaufnahmevorrichtung eine vorgegebene Hauptförderrichtung auf, und weist die Hydraulikpumpe während des Absenkens der Lastaufnahmeeinrichtung eine zur Hauptförderrichtung gleichgerichtete Förderrichtung auf. Es ergibt sich hieraus der Vorteil, daß eine handelsübliche Hydraulikpumpe verwendet werden kann, die für nur eine Drehrichtung ausgelegt ist. In another, equally advantageous embodiment, the hydraulic pump a predetermined main conveying direction for lifting the load suspension device on, and has the hydraulic pump during the lowering of the Load suspension device rectified to the main conveying direction Direction of conveyance. This has the advantage that a commercially available Hydraulic pump can be used, which is designed for only one direction of rotation.

Es ist hierbei erforderlich, daß der Hydraulikzylinder mit der Saugseite der Hydraulikpumpe mittels einer Bypassleitung verbindbar ist. Die Bypassleitung ist mittels eines Sperrventils verschließbar, das zum Absenken der Lastaufnahmevorrichtung geöffnet wird.It is necessary that the hydraulic cylinder with the suction side of the Hydraulic pump can be connected by means of a bypass line. The bypass line is closable by means of a check valve which is used to lower the Load suspension device is opened.

Zweckmäßigerweise ist eine die Hydraulikpumpe mit dem Hydraulikzylinder verbindende Leitung mittels einer Ablaßleitung mit einem Tank verbindbar. Ein Teil des die Pumpe durchströmenden Hydrauliköls und/oder ein Teil des von dem Hydraulikzylinder abfließende Ölstroms kann durch die Ablaßleitung in den Tank abströmen.The hydraulic pump with the hydraulic cylinder is expediently connecting line connectable to a tank by means of a drain line. A part of the hydraulic oil flowing through the pump and / or part of that Hydraulic cylinder flowing oil flow can through the drain line into the tank flow out.

Mit besonderem Vorteil ist hierbei in der Ablaßleitung ein stufenlos einstellbares Ablaßventil angeordnet. Die Senkgeschwindigkeit und die Anhebegeschwindigkeit der Lastaufnahmevorrichtung können abhängig von der Schaltstellung des Ablaßventils stufenlos eingestellt werden.It is particularly advantageous to have an infinitely adjustable one in the drain line Drain valve arranged. The lowering speed and the lifting speed of the Load suspension device can depend on the switching position of the drain valve can be adjusted continuously.

Hierbei ist es besonders zweckmäßig, wenn das Ablaßventil als Sitzventil ausgebildet ist. Sitzventile sind einerseits einfach und preisgünstig herstellbar, andererseits sind sie bauartbedingt in geschlossener Stellung absolut dicht, womit ein unbeabsichtigtes Absenken der Lastaufnahmevorrichtung sicher vermieden wird.It is particularly expedient here if the drain valve is designed as a seat valve is. Seat valves are simple and inexpensive to manufacture, on the one hand, and are due to their design, they are absolutely tight in the closed position, making them unintentional Lowering the load suspension device is safely avoided.

Das Ablaßventil und/oder der Elektromotor sind mittels einer elektrischen Impulssteuereinheit steuerbar.The drain valve and / or the electric motor are by means of an electric Pulse control unit controllable.

Es ergeben sich dabei besondere Vorteile, wenn der Elektromotor als fremderregter Gleichstrom-Nebenschlußmotor ausgeführt ist. Bei fremderregten Gleichstrom-Nebenschlußmotoren können das Drehmoment und die Drehzahl unabhängig voneinander eingestellt werden, wodurch die Verwendung des Elektromotors zum Beschleunigen des Absenkens der Lastaufnahmevorrichtung ermöglicht wird.There are special advantages if the electric motor is externally excited DC shunt motor is executed. For separately excited DC shunt motors can control the torque and speed independently can be adjusted from each other, whereby the use of the electric motor for Accelerating the lowering of the load suspension device is made possible.

Zweckmäßigerweise ist zur Steuerung des Anhebens und/oder des Absenkens der Lastaufnahmevorrichtung mindestens ein stufenlos betätigbares elektrisches Schaltelement vorgesehen, das mit der elektrischen Impulssteuereinheit in Wirkverbindung steht.It is expedient to control the raising and / or lowering of the Load suspension device at least one continuously actuable electrical Switching element provided that with the electrical pulse control unit in Active connection is established.

Besondere Vorteile ergeben sich, wenn das Flurförderzeug als Hochhubwagen, vorzugsweise als deichselgeführter Hochhubwagen ausgeführt ist. Bei einem deichselgeführten Hochhubwagen ist es erforderlich, die Bewegung des Lastaufnahmemittels mit einem elektrischen Schalter zu steuern, da größere Schaltelemente nicht an der Deichsel angeordnet werden können. Darüber hinaus besitzt die Lastaufnahmevorrichtung von Hubwagen dieser Art in der Regel ein relativ geringes Gewicht, so daß der Beschleunigung der Absenkbewegung eine besonders große Bedeutung zukommt. Durch die Erfindung wird es nun ermöglicht, ein schnelles Absenken der Lastaufnahmevorrichtung von der Deichsel aus zu steuern.There are special advantages if the industrial truck as a pallet truck, is preferably designed as a pedestrian-controlled high-lift truck. At a Drawbar pallet stacker it is necessary to move the Control the load handler with an electrical switch, because larger Switching elements cannot be arranged on the drawbar. Furthermore the lifting device of this type of truck usually has a relative light weight, so that the acceleration of the lowering movement is a special is of great importance. The invention now enables fast Control the lowering of the load suspension device from the drawbar.

Bezüglich des Verfahrens wird die Aufgabe dadurch gelöst, daß bei bestimmten Steuersignalen und/oder Betriebsparametern während des Absenkens der Lastaufnahmevorrichtung mittels der Hydraulikpumpe Hydrauliköl aus dem Hydraulikzylinder gesaugt wird.With regard to the method, the object is achieved in that certain Control signals and / or operating parameters during the lowering of the Load suspension device using the hydraulic pump hydraulic oil from the Hydraulic cylinder is sucked.

Weitere Vorteile ergeben sich, wenn mittels eines Bedienelements verschiedene Geschwindigkeitssollwerte für das Absenken der Lastaufnahmevorrichtung vorgebbar sind, wobei bei einem geringen Geschwindigkeitssollwert der Elektromotor die Hydraulikpumpe nicht antreibt und bei einem hohen Geschwindigkeitssollwert der Elektromotor die Hydraulikpumpe antreibt.Further advantages result when different ones are used by means of an operating element Speed setpoints for lowering the load suspension device can be specified are, the electric motor at a low speed setpoint Hydraulic pump does not drive and at a high speed setpoint the Electric motor drives the hydraulic pump.

Ebenso vorteilhaft ist es, wenn als Betriebsparameter das Gewicht einer auf der Lastaufnahmevorrichtung befindlichen Last verwendet wird, wobei bei einem großen Lastgewicht der Elektromotor die Hydraulikpumpe nicht antreibt und bei einem geringen Lastgewicht der Elektromotor die Hydraulikpumpe antreibt.It is also advantageous if the weight of one on the Load-bearing device located load is used, with a large Load weight of the electric motor does not drive the hydraulic pump and at one low load weight of the electric motor drives the hydraulic pump.

Weitere Vorteile und Einzelheiten der Erfindung werden anhand des in den schematischen Figuren dargestellten Ausführungsbeispiels näher erläutert. Dabei zeigt

Figur 1
eine hydraulische Schaltung für eine Hubvorrichtung,
Figur 2
eine weitere Ausführungsform einer hydraulischen Schaltung,
Figur 3a, b
Diagramme für die Steuersignale der Hydraulikpumpe und verschiedener Ventile.
Further advantages and details of the invention are explained in more detail with reference to the embodiment shown in the schematic figures. It shows
Figure 1
a hydraulic circuit for a lifting device,
Figure 2
another embodiment of a hydraulic circuit,
Figure 3a, b
Diagrams for the control signals of the hydraulic pump and various valves.

Figur 1 zeigt eine hydraulische Schaltung für eine Hubvorrichtung eines erfindungsgemäßen Flurförderzeugs. Eine von einem Elektromotor 1 antreibbare Hydraulikpumpe 2 ist über eine Leitung 3 mit einem drucklosen Tank 4 verbunden.Figure 1 shows a hydraulic circuit for a lifting device industrial truck according to the invention. A drivable by an electric motor 1 Hydraulic pump 2 is connected to a pressureless tank 4 via a line 3.

Zum Anheben der Lastaufnahmevorrichtung mittels eines Hydraulikzylinders 5 treibt der Elektromotor 1 die Hydraulikpumpe 2 in einer Richtung an, bei der sich die Druckseite der Hydraulikpumpe 2 in der Zeichnung oben befindet. Die Hydraulikpumpe 2 fördert somit Hydrauliköl von dem Tank 4 durch das Rückschlagventil 7, das sich hierbei in der dargestellten Stellung befindet, in die Leitung 6. Mittels eines stufenlos einstellbaren, als Sitzventil ausgeführten Ablaßventils 8 kann ein Teil des mit der Hydraulikpumpe 2 geförderten Hydrauliköls in den drucklosen Tank 4 abgelassen werden. Das übrige mit der Pumpe 2 geförderte Hydrauliköl wird dem Hydraulikzylinder 5 zugeführt. Mit dem Ablaßventil 8 kann somit die Hubgeschwindigkeit der Lastaufnahmevorrichtung eingestellt werden.For lifting the load suspension device by means of a hydraulic cylinder 5 drives the electric motor 1 turns on the hydraulic pump 2 in a direction in which the Pressure side of the hydraulic pump 2 is located in the drawing above. The Hydraulic pump 2 thus pumps hydraulic oil from the tank 4 through the Check valve 7, which is in the position shown here, in the Line 6. By means of a continuously adjustable, designed as a seat valve Drain valve 8 can be a part of the hydraulic oil delivered with the hydraulic pump 2 in the depressurized tank 4 are drained. The rest of the pump 2 Hydraulic oil is supplied to the hydraulic cylinder 5. With the drain valve 8 can thus the lifting speed of the load suspension device can be set.

Zum Absenken der Lastaufnahmevorrichtung wird Hydrauliköl aus dem Hydraulikzylinder 5 abgelassen. Hierzu wird zunächst mittels eines Schaltmagnets das Rückschlagventil 7 geöffnet. Hydrauliköl kann dann durch die Hydraulikpumpe 2 abfließen, wobei dieser Ölstrom die Hydraulikpumpe 2 und damit den Elektromotor 1 antreibt. Der Elektromotor 1 wird hierbei generatorisch betrieben, was zur Energierückgewinnung ausgenutzt werden kann. Um das Absenken der Lastaufnahmevorrichtung zu beschleunigen, kann zusätzlich das Ablaßventil 8 geöffnet werden, wobei die Geschwindigkeit der Absenkbewegung über die Öffnungsweite des Ablaßventils 8 eingestellt werden kann. Um eine maximale Absenkgeschwindigkeit der Lastaufnahmevorrichtung zu erreichen, wird erfindungsgemäß die Hydraulikpumpe 2 durch den Elektromotor 1 in der Richtung angetrieben, bei der sich die Saugseite der Hydraulikpumpe 2 in der Zeichnung oben befindet. Es wird somit durch die Pumpe 2 Hydrauliköl aus dem Hydraulikzylinder 5 angesaugt.Hydraulic oil from the Hydraulic cylinder 5 drained. To do this, first use a switching magnet the check valve 7 opened. Hydraulic oil can then be pumped through the hydraulic pump 2 drain off, this oil flow the hydraulic pump 2 and thus the electric motor 1st drives. The electric motor 1 is operated as a generator, which for Energy recovery can be exploited. To lower the To accelerate the load suspension device, the drain valve 8 be opened, the speed of the lowering movement over the Opening width of the drain valve 8 can be adjusted. To a maximum To achieve lowering speed of the load suspension device According to the invention, the hydraulic pump 2 by the electric motor 1 in the direction driven, in which the suction side of the hydraulic pump 2 in the drawing above located. Hydraulic oil from hydraulic cylinder 5 is thus pumped 2 sucked in.

Um den Elektromotor 1 mit verschiedenen Drehrichtungen betreiben zu können und gegebenenfalls zur Energierückgewinnung als Generator einzusetzen, kann der Elektromotor 1 als impulsgesteuerter Gleichstrom-Nebenschlußmotor ausgeführt werden. Ebenso ist es möglich, den Elektromotor als Drehstrom-Asynchronmotor auszuführen.In order to operate the electric motor 1 with different directions of rotation and can be used as a generator for energy recovery, if necessary Electric motor 1 designed as a pulse-controlled direct current shunt motor become. It is also possible to use the electric motor as a three-phase asynchronous motor to execute.

Figur 2 zeigt eine weiter Ausführungsform für die Hubvorrichtung eines erfindungsgemäßen Flurförderzeugs. Um die Lastaufnahmevorrichtung anzuheben, wird von der Pumpe 2a Hydrauliköl aus dem Tank 4 durch zwei Rückschlagventile 10, 11 in den Hydraulikzylinder 5 gepumpt. Ein in einer Bypassleitung 12 angeordnetes schaltbares Sperrventil 13 befindet sich dabei in der eingezeichneten absperrenden Stellung. Über das einstellbare Ablaßventil 8 kann analog zur Anordnung gemäß Fig. 1 die Hubgeschwindigkeit eingestellt werden. Figure 2 shows a further embodiment for the lifting device industrial truck according to the invention. To raise the load handler is pump 2 a hydraulic oil from the tank 4 through two check valves 10, 11 pumped into the hydraulic cylinder 5. One arranged in a bypass line 12 switchable check valve 13 is located in the shut-off Position. Via the adjustable drain valve 8, analogous to the arrangement according to FIG. 1 the lifting speed can be set.

Um die Lastaufnahmevorrichtung abzusenken, wird das Sperrventil 13 geöffnet. Das aus dem Hydraulikzylinder 5 abfließende Hydrauliköl kann dann über die Bypassleitung durch die Hydraulikpumpe 2a und das Ablaßventil 8 in den Tank 5 abfließen. Mit dem Ablaßventil 8 wird die Senkgeschwindigkeit der Lastaufnahmevorrichtung eingestellt. Hierbei kann, insbesondere wenn sich auf der Lastaufnahmevorrichtung eine große Last befindet, mit der Hydraulikpumpe 2a und dem Elektromotor 1a Energie zurückgewonnen werden. Zur Beschleunigung der Absenkbewegung kann erfindungsgemäß die Hydraulikpumpe 2a durch den Elektromotor 1a angetrieben werden, wobei sich bei dieser Ausführungsform die Saugseite der Hydraulikpumpe 2a in der Zeichnung unten befindet. Auch bei dieser Ausführungsform ist eine Ausbildung des Elektromotors 1a als Gleichstrom-Nebenschlußmotor oder als Drehstrom-Asynchronmotor zweckmäßig.In order to lower the load suspension device, the check valve 13 is opened. The Hydraulic oil flowing out of the hydraulic cylinder 5 can then via the Bypass line through hydraulic pump 2a and drain valve 8 into tank 5 flow away. With the drain valve 8, the lowering speed of Load suspension device set. This can, especially if the Load handling device is a large load, with the hydraulic pump 2a and the electric motor 1a energy can be recovered. To speed up the According to the invention, the lowering movement can be carried out by the hydraulic pump 2a Electric motor 1a are driven, which in this embodiment Suction side of the hydraulic pump 2a is located in the drawing below. This one too Embodiment is an embodiment of the electric motor 1a as a DC shunt motor or useful as a three-phase asynchronous motor.

Figur 3a zeigt die Größen des Steuersignals 17 für das Rückschlagventil 7 bzw. das Sperrventil 13, des Steuersignals 18 für das Ablaßventil 8 sowie des Steuersignals 19 für den Elektromotor 1 bzw. 1a über dem durch die Bedienperson vorgegebenen Sollwert 20 für die Senkgeschwindigkeit. Aus diesem Diagramm ist zu entnehmen, daß das Rückschlagventil 7 bzw. das Sperrventil 13 bei einem Absenken der Lastaufnahmevorrichtung stets geöffnet sind. Das Ablaßventil 8 wird mit Ansteigen des Sollwerts 20 für die Senkgeschwindigkeit kontinuierlich geöffnet. Wenn der Sollwert für die Senkgeschwindigkeit seinen maximalen Wert annähernd erreicht hat, wird mit dem Steuersignal 19 zusätzlich der Elektromotor 1 bzw. 1a mit der entsprechenden Drehrichtung eingeschaltet, um die Absenkbewegung der Lastaufnahmevorrichtung zu unterstützen.Figure 3a shows the sizes of the control signal 17 for the check valve 7 or Check valve 13, the control signal 18 for the drain valve 8 and the control signal 19th for the electric motor 1 or 1a above that specified by the operator Setpoint 20 for the lowering speed. This diagram shows that the check valve 7 and the check valve 13 when the Load suspension device are always open. The drain valve 8 will rise of the setpoint 20 for the lowering speed opened continuously. If the Setpoint for the lowering speed has almost reached its maximum value, is with the control signal 19, the electric motor 1 or 1a with the corresponding direction of rotation switched on to the lowering movement of the Support load suspension device.

Figur 3b zeigt die entsprechenden Größen des Steuersignals 17a für das Rückschlagventil 7 bzw. das Sperrventil 13, des Steuersignals 18a für das Ablaßventil 8 sowie des Steuersignals 19a für den Elektromotor 1 bzw. 1a über dem durch die Bedienperson vorgegebenen Sollwert 20a für die Hubgeschwindigkeit. Das Rückschlagventil 7 bzw. das Sperrventil 13 befinden während des Anhebens stets in den Figuren 1 bzw. 2 dargestellten Stellungen. Ebenso ist der Elektromotor 1 bzw. 1a während des Anhebens stets mit der entsprechenden Drehrichtung in Betrieb. Mit Ansteigen des Sollwerts 20a für die Hubgeschwindigkeit wird das Ablaßventil 8 kontinuierlich weiter geschlossen, wodurch die tatsächliche Hubgeschwindigkeit erhöht wird. Figure 3b shows the corresponding quantities of the control signal 17a for the Check valve 7 or the check valve 13, the control signal 18a for the drain valve 8 and the control signal 19a for the electric motor 1 or 1a above that by the Operator specified target value 20a for the lifting speed. The Check valve 7 and the check valve 13 are always in during lifting the positions shown in Figures 1 and 2. Likewise, the electric motor 1 or 1a Always operate with the appropriate direction of rotation during lifting. With The drain valve 8 becomes the setpoint 20a for the lifting speed continuously closed further, reducing the actual lifting speed is increased.

Sämtliche Steuersignale gemäß Fig. 3a und 3b werden vorzugsweise mit einer oder mehreren Impulssteuereinheiten erzeugt und werden damit von impulsförmigen Spannungen dargestellt.All control signals according to Fig. 3a and 3b are preferably with or generated several pulse control units and are thus of pulse-shaped Voltages shown.

Claims (14)

Flurförderzeug mit einer vertikal beweglichen Lastaufnahmevorrichtung, wobei eine Vorrichtung zum vertikalen Bewegen der Lastaufnahmevorrichtung mindestens einen Hydraulikzylinder (5) und mindestens eine mittels eines Elektromotors (1, 1a) antreibbare Hydraulikpumpe (2, 2a) aufweist und die angetriebene Hydraulikpumpe (2, 2a) eine Druckseite und eine Saugseite aufweist, dadurch gekennzeichnet, daß die Saugseite der angetriebenen Hydraulikpumpe (2, 2a) mit dem Hydraulikzylinder (5) verbindbar ist.Industrial truck with a vertically movable load suspension device, a device for vertically moving the load suspension device having at least one hydraulic cylinder (5) and at least one hydraulic pump (2, 2a) which can be driven by an electric motor (1, 1a) and the driven hydraulic pump (2, 2a) Pressure side and a suction side, characterized in that the suction side of the driven hydraulic pump (2, 2a) can be connected to the hydraulic cylinder (5). Flurförderzeug nach Anspruch 1, dadurch gekennzeichnet, daß die Hydraulikpumpe (2, 2a) zum Anheben der Lastaufnahmevorrichtung eine vorgegebene Hauptförderrichtung aufweist, und daß die Hydraulikpumpe (2, 2a) während des Absenkens der Lastaufnahmevorrichtung eine zur Hauptförderrichtung entgegengesetzte Förderrichtung aufweist.Industrial truck according to claim 1, characterized in that the Hydraulic pump (2, 2a) for lifting the load suspension device has a predetermined main conveying direction, and that the hydraulic pump (2, 2a) during the lowering of the load suspension device Main conveying direction has opposite conveying direction. Flurförderzeug nach Anspruch 1, dadurch gekennzeichnet, daß die Hydraulikpumpe (2, 2a) zum Anheben der Lastaufnahmevorrichtung eine vorgegebene Hauptförderrichtung aufweist, und daß die Hydraulikpumpe (2, 2a) während des Absenkens der Lastaufnahmeeinrichtung eine zur Hauptförderrichtung gleichgerichtete Förderrichtung aufweist.Industrial truck according to claim 1, characterized in that the Hydraulic pump (2, 2a) for lifting the load suspension device has a predetermined main conveying direction, and that the hydraulic pump (2, 2a) during the lowering of the load suspension device Main conveying direction has the same direction of conveyance. Flurförderzeug nach Anspruch 3, dadurch gekennzeichnet, daß der Hydraulikzylinder (5) mit der Saugseite der Hydraulikpumpe (2, 2a) mittels einer Bypassleitung (12) verbindbar ist.Industrial truck according to claim 3, characterized in that the Hydraulic cylinder (5) with the suction side of the hydraulic pump (2, 2a) by means of a Bypass line (12) can be connected. Flurförderzeug nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß eine die Hydraulikpumpe (2, 2a) mit dem Hydraulikzylinder (5) verbindende Leitung (6) mittels einer Ablaßleitung mit einem Tank verbindbar ist.Industrial truck according to one of claims 1 to 4, characterized in that a connecting the hydraulic pump (2, 2a) with the hydraulic cylinder (5) Line (6) can be connected to a tank by means of a drain line. Flurförderzeug nach Anspruch 5, dadurch gekennzeichnet, daß in der Ablaßleitung ein stufenlos einstellbares Ablaßventil (8) angeordnet ist.Industrial truck according to claim 5, characterized in that in the Drain line an infinitely adjustable drain valve (8) is arranged. Flurförderzeug nach Anspruch 6, dadurch gekennzeichnet, daß das Ablaßventil (8) als Sitzventil ausgebildet ist. Industrial truck according to claim 6, characterized in that the drain valve (8) is designed as a seat valve. Flurförderzeug nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, daß das Ablaßventil (8) und/oder der Elektromotor (1, 1a) mittels einer elektrischen Impulssteuereinheit steuerbar sind.Industrial truck according to one of claims 1 to 7, characterized in that the drain valve (8) and / or the electric motor (1, 1a) by means of an electric Pulse control unit are controllable. Flurförderzeug nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, daß der Elektromotor (1, 1a) als fremderregter Gleichstrom-Nebenschlußmotor ausgeführt ist.Industrial truck according to one of claims 1 to 8, characterized in that the electric motor (1, 1a) as a separately excited direct current shunt motor is executed. Flurförderzeug nach Anspruch 8 oder 9, dadurch gekennzeichnet, daß zur Steuerung des Anhebens und/oder des Absenkens der Lastaufnahmevorrichtung mindestens ein stufenlos betätigbares elektrisches Schaltelement vorgesehen ist, das mit der elektrischen Impulssteuereinheit in Wirkverbindung steht.Industrial truck according to claim 8 or 9, characterized in that for Control of the lifting and / or lowering of the load suspension device at least one continuously actuable electrical switching element is provided, which is in operative connection with the electrical pulse control unit. Flurförderzeug nach einem der Ansprüche 1 bis 10, dadurch gekennzeichnet, daß das Flurförderzeug als Hochhubwagen, vorzugsweise als deichselgeführter Hochhubwagen ausgeführt ist.Industrial truck according to one of claims 1 to 10, characterized in that the truck as a pallet truck, preferably as a drawbar Pallet stacker is running. Verfahren zum Absenken einer vertikal beweglichen Lastaufnahmevorrichtung an einem Flurförderzeug, wobei das Flurförderzeug eine Vorrichtung zum vertikalen Bewegen der Lastaufnahmevorrichtung mindestens einen Hydraulikzylinder und mindestens eine mittels eines Elektromotors antreibbare Hydraulikpumpe (2, 2a) aufweist, dadurch gekennzeichnet, daß bei bestimmten Steuersignalen und/oder Betriebsparametern während des Absenkens der Lastaufnahmevorrichtung mittels der Hydraulikpumpe (2, 2a) Hydrauliköl aus dem Hydraulikzylinder (5) gesaugt wird.Method for lowering a vertically movable load suspension device on an industrial truck, the industrial truck having a device for vertically moving the load suspension device at least one hydraulic cylinder and at least one hydraulic pump (2, 2a) which can be driven by an electric motor, characterized in that with certain control signals and / or operating parameters while the load suspension device is being lowered, hydraulic oil is sucked out of the hydraulic cylinder (5) by means of the hydraulic pump (2, 2a). Verfahren nach Anspruch 12, dadurch gekennzeichnet, daß mittels eines Bedienelements verschiedene Geschwindigkeitssollwerte für das Absenken der Lastaufnahmevorrichtung vorgebbar sind, wobei bei einem geringen Geschwindigkeitssollwert der Elektromotor (1, 1a) die Hydraulikpumpe (2, 2a) nicht antreibt und bei einem hohen Geschwindigkeitssollwert der Elektromotor (1, 1a) die Hydraulikpumpe (2, 2a) antreibt. A method according to claim 12, characterized in that by means of a Control elements different speed setpoints for lowering the Load suspension device can be specified, with a low Speed setpoint of the electric motor (1, 1a) the hydraulic pump (2, 2a) does not drive and the electric motor (1, 1a) drives the hydraulic pump (2, 2a). Verfahren nach Anspruch 12 oder 13, dadurch gekennzeichnet, daß als Betriebsparameter das Gewicht einer auf der Lastaufnahmevorrichtung befindlichen Last verwendet wird, wobei bei einem großen Lastgewicht der Elektromotor (1, 1a) die Hydraulikpumpe (2, 2a) nicht antreibt und bei einem geringen Lastgewicht der Elektromotor (1, 1a) die Hydraulikpumpe (2, 2a) antreibt.A method according to claim 12 or 13, characterized in that as Operating parameters the weight of one on the load handling device located load is used, with a large load weight of Electric motor (1, 1a) does not drive the hydraulic pump (2, 2a) and at one low load weight of the electric motor (1, 1a) the hydraulic pump (2, 2a) drives.
EP98118873A 1997-10-08 1998-10-06 Lift truck with a load grasping device Expired - Lifetime EP0908413B1 (en)

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DE19744429A DE19744429A1 (en) 1997-10-08 1997-10-08 Industrial truck with a load suspension device and method for lowering the load suspension device
DE19744429 1997-10-08

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US10844880B2 (en) 2017-01-17 2020-11-24 The Raymond Corporation Variable hydraulic pressure relief systems and methods for a material handling vehicle
US11118607B2 (en) 2017-01-17 2021-09-14 The Raymond Corporation Variable hydraulic pressure relief systems and methods for a material handling vehicle
WO2021004657A1 (en) * 2019-07-08 2021-01-14 Eaton Intelligent Power Limited Hydraulic system architectures and bidirectional proportional valves usable in the system architectures

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EP0908413B1 (en) 2005-12-21
EP0908413A3 (en) 2001-08-08
DE19744429A1 (en) 1999-04-22
DE59813292D1 (en) 2006-01-26

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