EP1004542B1 - Hydraulic system especially for an industrial truck - Google Patents

Hydraulic system especially for an industrial truck Download PDF

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Publication number
EP1004542B1
EP1004542B1 EP99123341A EP99123341A EP1004542B1 EP 1004542 B1 EP1004542 B1 EP 1004542B1 EP 99123341 A EP99123341 A EP 99123341A EP 99123341 A EP99123341 A EP 99123341A EP 1004542 B1 EP1004542 B1 EP 1004542B1
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EP
European Patent Office
Prior art keywords
tank
hydraulic
working machine
machine according
valve
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Expired - Lifetime
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EP99123341A
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German (de)
French (fr)
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EP1004542A1 (en
Inventor
Rainer Dr.-Ing. Bavendiek
Claus-Peter Dipl.-Ing. Jahns
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STILL GmbH
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STILL GmbH
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F9/00—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
    • B66F9/06—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
    • B66F9/075—Constructional features or details
    • B66F9/20—Means for actuating or controlling masts, platforms, or forks
    • B66F9/22—Hydraulic devices or systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B17/00—Pumps characterised by combination with, or adaptation to, specific driving engines or motors
    • F04B17/03—Pumps characterised by combination with, or adaptation to, specific driving engines or motors driven by electric motors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B23/00—Pumping installations or systems
    • F04B23/02—Pumping installations or systems having reservoirs
    • F04B23/021—Pumping installations or systems having reservoirs the pump being immersed in the reservoir
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B23/00—Pumping installations or systems
    • F04B23/02—Pumping installations or systems having reservoirs
    • F04B23/021—Pumping installations or systems having reservoirs the pump being immersed in the reservoir
    • F04B23/023—Pumping installations or systems having reservoirs the pump being immersed in the reservoir only the pump-part being immersed, the driving-part being outside the reservoir
    • 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
    • F15B1/00—Installations or systems with accumulators; Supply reservoir or sump assemblies
    • F15B1/26—Supply reservoir or sump assemblies

Definitions

  • the invention relates to a working machine, in particular industrial truck, with a hydraulic system which has at least one tank for hydraulic fluid and at least one hydraulic pump, wherein the hydraulic pump is arranged inside the tank.
  • Work machines are often equipped with a hydraulic system, via which, depending on the type of work machine, the drive of various functions of the machine. In the case of industrial trucks, this usually involves lifting and tilting a load, steering the truck and possibly additional functions for handling loads.
  • the hydraulic system usually has a tank from which hydraulic fluid is sucked by means of a pump. Downstream of the pump is a priority valve, which preferably supplies a hydraulic steering device with hydraulic fluid.
  • hydraulic fluid is provided via arbitrarily controllable directional valves further hydraulic consumers available. These are usually hydraulic cylinders that generate the forces needed to lift, tilt or handle a load.
  • the steering device and the other hydraulic consumers are further connected via return lines to the tank, wherein in the return lines optionally a lowering brake for reducing the flow rate of hydraulic fluid, or a biasing valve for maintaining a predetermined pressure level can be arranged in the corresponding return line.
  • the said hydraulic components are usually separated from each other attached to a frame of the working machine and connected to each other by hose or pipe lines in working machines of the prior art. It is also known to combine various hydraulic components into assemblies and to fix them together on the frame of the machine. In any case, have known hydraulic systems However, a number of joints and joints, which are sealed with seals of various types against leakage of hydraulic fluid.
  • the present invention has for its object to provide a generic machine available, in which the risk of leakage of hydraulic fluid is further reduced.
  • At least one directional control valve is disposed within the tank.
  • the supply of hydraulic fluid to various hydraulic consumers is controlled in response to a signal generated by an operator.
  • Leaks of these usually proportionally controllable directional valves, which may also be designed as slide valves are collected by the tank.
  • slide valves can be dispensed with the costly required in devices of the prior art complex tank return of the type of construction incurred leakage oil. It is even possible to dispense with the commonly used seals against contamination of the slide valves, as they are exposed due to the arrangement in the tank no external influences.
  • an electric drive motor of the hydraulic pump is arranged inside the tank. It is thus no mechanical rotary feedthrough through a wall of the tank required.
  • the hydraulic fluid in the tank also serves as a coolant for the electric drive motor.
  • the arrangement of the electric drive motor within the tank is particularly suitable when a maintenance-free three-phase motor is used.
  • a further improvement in the leakage of hydraulic fluid results when a priority valve is located within the tank.
  • the priority valve ensures that a steering device of the working machine is always sufficiently supplied with hydraulic fluid. Leaks in the area of the priority valve, for example at the hydraulic connection points, do not lead to contamination of the environment by hydraulic fluid in this arrangement. Instead, the leaking hydraulic fluid is collected in the tank.
  • priority valve is attached to the hydraulic pump by means of a flange connection, no additional hydraulic lines are required between these components. Hydraulic pump and priority valve can be installed as a pre-assembled unit in the tank.
  • the directional control valve is designed to be electrically controlled.
  • the directional control valves can thus be arranged spatially independently of the respective associated control lever.
  • a plurality of directional valves are provided which form a directional control valve block.
  • the directional control valve block can be installed in the tank pre-assembled.
  • the priority valve is a part of the directional control valve block. There are therefore no hydraulic lines required to connect the priority valve with the directional control valve block.
  • the steering valve can be designed as part of the directional control valve block.
  • bias valves and / or a lowering brake valve are disposed within the tank.
  • the biasing valve and lowering brake valve are arranged in the return lines of hydraulic consumers. These components can also be arranged within the tank according to the invention.
  • the figure shows a tank 1 of a hydraulic system of a working machine.
  • the tank 1 is sealed with a tank cap 2.
  • a number of components of the hydraulic system are arranged according to the invention.
  • An electric drive motor 3 designed as a three-phase motor is located below the filling level line 4 of the tank 1 and is thus cooled by the hydraulic fluid surrounding it. Flanged to the drive motor 3 is a hydraulic pump 5, which is driven by the drive motor 3. The hydraulic pump 5 sucks hydraulic fluid from the tank 1 via an intake filter 6 arranged in a suction pipe 7.
  • a directional valve block 8 is flanged to the hydraulic pump 5, which in this embodiment comprises a priority valve 8a, a steering valve 8b and two-way valves 8c, 8d.
  • a priority valve 8a a priority valve 8a
  • a steering valve 8b a steering valve 8b
  • two-way valves 8c, 8d a directional valve block 8 is flanged to the hydraulic pump 5, which in this embodiment comprises a priority valve 8a, a steering valve 8b and two-way valves 8c, 8d.
  • the steering valve 8b and the directional control valves 8c, 8d lead via a flange plate 10 hydraulic pressure lines 9 to the respective hydraulic consumers.
  • a passage for electrical lines is further arranged.
  • a control and supply line 11 for the electric drive motor 3 and signal lines 12 to the steering valve 8b and the directional valves 8c, 8d are provided.
  • the signal lines are connected to the corresponding control levers or a steering transmitter, with which electrical control signals are generated.
  • return lines 13 through which hydraulic fluid from the various hydraulic consumers flows back into the tank 1.
  • the return lines 13 are guided via a flange plate 14 through the tank cap 2 into the tank 1.
  • return line which is connected to a not shown lifting cylinder of the machine, there is a lowering brake valve 15.
  • the lowering brake valve 15 prevents too rapid outflow of hydraulic oil into the tank 1 and is therefore suitable, for example, the lowering movement of a load receiving device brake.
  • the return line is a bias valve 16, with which a certain predetermined pressure in the return line is maintained.
  • the hydraulic pump 1, the directional control valve block 8, the lowering brake valve 15 and the biasing valve 16 are arranged inside the tank 1. Leaks in these hydraulic components or at their joints therefore do not lead to contamination of the machine and its environment with hydraulic fluid. Instead, the unintentionally leaking hydraulic fluid is collected in the tank.

Description

Die Erfindung betrifft eine Arbeitsmaschine, insbesondere Flurförderzeug, mit einer hydraulischen Anlage, die mindestens einen Tank für Hydraulikfluid und mindestens eine Hydraulikpumpe aufweist, wobei die Hydraulikpumpe innerhalb des Tanks angeordnet ist. Arbeitsmaschinen sind häufig mit einer hydraulischen Anlage ausgerüstet, über welche in Abhängigkeit von der Bauart der Arbeitsmaschine der Antrieb verschiedener Funktionen der Arbeitsmaschine erfolgt. Bei Flurförderzeugen handelt es sich hierbei in der Regel um das Anheben und Neigen einer Last, um das Lenken des Flurförderzeugs sowie gegebenenfalls um Zusatzfunktionen zur Handhabung von Lasten.The invention relates to a working machine, in particular industrial truck, with a hydraulic system which has at least one tank for hydraulic fluid and at least one hydraulic pump, wherein the hydraulic pump is arranged inside the tank. Work machines are often equipped with a hydraulic system, via which, depending on the type of work machine, the drive of various functions of the machine. In the case of industrial trucks, this usually involves lifting and tilting a load, steering the truck and possibly additional functions for handling loads.

Die hydraulische Anlage weist in der Regel einen Tank auf, aus dem mittels einer Pumpe Hydraulikfluid angesaugt wird. Der Pumpe nachgeschaltet ist ein Prioritätsventil, das bevorzugt eine hydraulische Lenkungsvorrichtung mit Hydraulikfluid versorgt. Darüber hinaus wird Hydraulikfluid über willkürlich ansteuerbare Wegeventile weiteren hydraulischen Verbrauchern zur Verfügung gestellt. Hierbei handelt es sich meist um Hydraulikzylinder, mit denen die zum Anheben, Neigen oder Handhaben einer Last erforderlichen Kräfte erzeugt werden. Die Lenkungsvorrichtung und die anderen hydraulischen Verbraucher sind weiterhin über Rücklaufleitungen mit dem Tank verbunden, wobei in den Rücklaufleitungen gegebenenfalls eine Senkbremse zum Reduzieren der Durchflußmenge an Hydraulikfluid, oder ein Vorspannventil zum Aufrechterhalten eines vorgegebenen Druckniveaus in der entsprechenden Rücklaufleitung angeordnet sein kann.The hydraulic system usually has a tank from which hydraulic fluid is sucked by means of a pump. Downstream of the pump is a priority valve, which preferably supplies a hydraulic steering device with hydraulic fluid. In addition, hydraulic fluid is provided via arbitrarily controllable directional valves further hydraulic consumers available. These are usually hydraulic cylinders that generate the forces needed to lift, tilt or handle a load. The steering device and the other hydraulic consumers are further connected via return lines to the tank, wherein in the return lines optionally a lowering brake for reducing the flow rate of hydraulic fluid, or a biasing valve for maintaining a predetermined pressure level can be arranged in the corresponding return line.

Die genannten hydraulischen Bauelemente sind bei Arbeitsmaschinen des Standes der Technik in der Regel voneinander getrennt an einem Rahmen der Arbeitsmaschine befestigt und über Schlauch- oder Rohrleitungen miteinander verbunden. Bekannt ist es ebenfalls, verschiedene hydraulische Bauelemente zu Baugruppen zusammenzufassen und gemeinsam an dem Rahmen der Arbeitsmaschine zu befestigen. In jedem Fall weisen bekannte hydraulische Anlagen jedoch eine Reihe von Trennfugen und Verbindungsstellen auf, die mit Dichtungen verschiedener Art gegen das Austreten von Hydraulikfluid abgedichtet werden.The said hydraulic components are usually separated from each other attached to a frame of the working machine and connected to each other by hose or pipe lines in working machines of the prior art. It is also known to combine various hydraulic components into assemblies and to fix them together on the frame of the machine. In any case, have known hydraulic systems However, a number of joints and joints, which are sealed with seals of various types against leakage of hydraulic fluid.

Das Verhindern des Austretens von Hydraulikfluid aus der hydraulischen Anlage ist insbesondere aus Gründen des Arbeitsschutzes und Umweltschutzes geboten. Hierfür werden bei der Herstellung der Arbeitsmaschine erhebliche Mittel aufgewendet. Dennoch treten bei Arbeitsmaschinen immer wieder Undichtheiten der hydraulischen Anlage auf, die im Zuge von Reparatur- oder Wartungsarbeiten umgehend behoben werden müssen.The prevention of the escape of hydraulic fluid from the hydraulic system is required in particular for reasons of occupational safety and environmental protection. For this purpose, considerable resources are spent in the production of the work machine. Nevertheless, machine tools frequently leak leaks in the hydraulic system, which must be remedied immediately in the course of repair or maintenance work.

Aus der DE 196 12 582 A1 ist es bekannt, bei einer Arbeitsmaschine die Hydraulikpumpe und einen elektrischen Antriebsmotor für die Hydraulikpumpe innerhalb des Tanks anzuordnen. Aus der Hydraulikpumpe austretendes Lecköl gelangt dadurch direkt in den Hydrauliktank.From DE 196 12 582 A1 it is known to arrange the hydraulic pump and an electric drive motor for the hydraulic pump within the tank in a work machine. Leakage oil escaping from the hydraulic pump thus passes directly into the hydraulic tank.

Der vorliegenden Erfindung liegt die Aufgabe zugrunde, eine gattungsgemäße Arbeitsmaschine zur Verfügung zu stellen, bei der die Gefahr eines Austretens von Hydraulikfluid weiter verringert ist.The present invention has for its object to provide a generic machine available, in which the risk of leakage of hydraulic fluid is further reduced.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß mindestens ein Wegeventil innerhalb des Tanks angeordnet ist. Mittels der Wegeventile wird die Zufuhr von Hydraulikfluid zu verschiedenen hydraulischen Verbrauchern in Abhängigkeit von einem von einer Bedienperson erzeugten Signal gesteuert. Leckagen dieser in der Regel proportional ansteuerbaren Wegeventile, die auch als Schieberventile ausgeführt sein können, werden vom Tank aufgefangen. Bei Schieberventilen kann auf die bei Geräten des Standes der Technik erforderliche aufwendige Tankrückführung des bauartbedingt anfallenden Leckageöls verzichtet werden. Es ist sogar möglich, auf die üblicherweise verwendeten Dichtungen gegen Verschmutzung der Schieberventile zu verzichten, da diese infolge der Anordnung im Tank keinen äußeren Einflüssen ausgesetzt sind. Darüber hinaus ist es möglich, auf eine Abdichtung der einzelnen Schieber der Wegeventile gegen Leckage zu verzichten, wodurch das Wegeventil preiswerter herstellbar ist. Auch bei Undichtheiten eines Gehäuses der Hydraulikpumpe oder ihrer hydraulischen Anschlüsse fließt das austretende Hydrauliköl direkt in den Tank. Hierdurch wird eine Verschmutzung der Arbeitsmaschine und der Umgebung sicher verhindert. Ein Abdichten dieser undichten Stellen ist nur bei groben Beschädigungen der Dichtungselemente erforderlich, wenn das austretende Hydraulikfluid zu einem Leistungsverlust der hydraulischen Anlage führt. Kleinere Undichtheiten können im Zuge von regelmäßig stattfindenden Wartungsarbeiten behoben werden, da sie während des Betriebs der Arbeitsmaschine keine Gefahr für Betriebssicherheit und Umwelt darstellen. Ein weiterer Vorteil der Anordnung der Pumpe im Tank besteht darin, daß bei undichten Stellen in einem Ansaugbereich der Pumpe, beispielsweise an einem Ansaugrohr oder an einem Filter, ein Eintreten von Luft in die Hydraulikpumpe und damit eine Beschädigung infolge Kavitation vermieden wird.This object is achieved in that at least one directional control valve is disposed within the tank. By means of the directional valves, the supply of hydraulic fluid to various hydraulic consumers is controlled in response to a signal generated by an operator. Leaks of these usually proportionally controllable directional valves, which may also be designed as slide valves are collected by the tank. With slide valves can be dispensed with the costly required in devices of the prior art complex tank return of the type of construction incurred leakage oil. It is even possible to dispense with the commonly used seals against contamination of the slide valves, as they are exposed due to the arrangement in the tank no external influences. In addition, it is possible to dispense with a seal of the individual valves of the directional valves against leakage, whereby the directional control valve is cheaper to produce. Even with leaks in a housing of the hydraulic pump or its hydraulic connections, the escaping hydraulic oil flows directly into the tank. As a result, contamination of the working machine and the environment is reliably prevented. A sealing of these leaks Positioning is only required if the sealing elements are severely damaged, if the escaping hydraulic fluid leads to a loss of performance of the hydraulic system. Minor leaks can be remedied as part of regular maintenance because they do not pose a threat to safety and the environment during operation of the work machine. Another advantage of the arrangement of the pump in the tank is that at leaks in a suction region of the pump, for example on an intake pipe or on a filter, an entry of air into the hydraulic pump and thus damage due to cavitation is avoided.

Weitere Vorteile ergeben sich, wenn ein elektrischer Antriebsmotor der Hydraulikpumpe innerhalb des Tanks angeordnet ist. Es ist damit keine mechanische Drehdurchführung durch eine Wand des Tanks erforderlich. Das in dem Tank befindliche Hydraulikfluid dient darüber hinaus als Kühlmittel für den elektrischen Antriebsmotor. Die Anordnung des elektrischen Antriebsmotors innerhalb des Tanks bietet sich insbesondere an, wenn ein wartungsfreier Drehstrommotor eingesetzt wird.Further advantages result when an electric drive motor of the hydraulic pump is arranged inside the tank. It is thus no mechanical rotary feedthrough through a wall of the tank required. The hydraulic fluid in the tank also serves as a coolant for the electric drive motor. The arrangement of the electric drive motor within the tank is particularly suitable when a maintenance-free three-phase motor is used.

Wenn ein elektrischer Antriebsmotor der Hydraulikpumpe außerhalb des Tanks angeordnet ist, wird eine sichere Abdichtung erzielt, wenn eine den elektrischen Antriebsmotor mit der Hydraulikpumpe verbindende Welle gegenüber dem Tank mit einem Wellendichtring abgedichtet ist. Diese Anordnung bietet sich insbesondere bei der Verwendung eines Gleichstrommotors an, der für regelmäßig durchzuführende Wartungsarbeiten zugänglich sein muß.When an electric drive motor of the hydraulic pump is disposed outside the tank, a secure seal is achieved when a shaft connecting the electric drive motor to the hydraulic pump is sealed to the tank with a shaft seal. This arrangement is particularly useful when using a DC motor, which must be accessible for regular maintenance.

Eine weitere Verbesserung hinsichtlich des Austretens von Hydraulikfluid ergibt sich, wenn ein Prioritätsventil innerhalb des Tanks angeordnet ist. Das Prioritätsventil stellt sicher, daß eine Lenkungsvorrichtung der Arbeitsmaschine jederzeit ausreichend mit Hydraulikfluid versorgt wird. Undichte Stellen im Bereich des Prioritätsventils, beispielsweise an den hydraulischen Anschlußstellen, führen bei dieser Anordnung nicht zu einer Verschmutzung der Umgebung durch Hydraulikfluid. Stattdessen wird das auslaufende Hydraulikfluid im Tank aufgefangen.A further improvement in the leakage of hydraulic fluid results when a priority valve is located within the tank. The priority valve ensures that a steering device of the working machine is always sufficiently supplied with hydraulic fluid. Leaks in the area of the priority valve, for example at the hydraulic connection points, do not lead to contamination of the environment by hydraulic fluid in this arrangement. Instead, the leaking hydraulic fluid is collected in the tank.

Wenn das Prioritätsventil mittels einer Flanschverbindung an der Hydraulikpumpe befestigt ist, sind zwischen diesen Bauteilen keine zusätzlichen hydraulischen Leitungen erforderlich. Hydraulikpumpe und Prioritätsventil können als vormontierte Baueinheit in den Tank eingebaut werden.If the priority valve is attached to the hydraulic pump by means of a flange connection, no additional hydraulic lines are required between these components. Hydraulic pump and priority valve can be installed as a pre-assembled unit in the tank.

Bei der Anordnung des Wegeventils im Tank ist es von Vorteil, wenn das Wegeventil elektrisch ansteuerbar ausgeführt ist. Die Wegeventile können damit räumlich unabhängig von dem jeweils zugeordneten Bedienhebel angeordnet werden.In the arrangement of the directional valve in the tank, it is advantageous if the directional control valve is designed to be electrically controlled. The directional control valves can thus be arranged spatially independently of the respective associated control lever.

Zweckmäßigerweise sind mehrere Wegeventile vorgesehen, die einen Wegeventilblock bilden. Der Wegeventilblock kann vormontiert in den Tank eingebaut werden.Conveniently, a plurality of directional valves are provided which form a directional control valve block. The directional control valve block can be installed in the tank pre-assembled.

Mit besonderem Vorteil ist das Prioritätsventil ein Bestandteil des Wegeventilblocks. Es sind somit auch keine hydraulischen Leitungen erforderlich, die das Prioritätsventil mit dem Wegeventilblock verbinden.With particular advantage, the priority valve is a part of the directional control valve block. There are therefore no hydraulic lines required to connect the priority valve with the directional control valve block.

Zu dem oben Erläuterten analoge Vorteile ergeben sich, wenn ein Lenkventil innerhalb des Tanks angeordnet ist.Analogous advantages to those discussed above arise when a steering valve is located within the tank.

Zusätzlich kann auch das Lenkventil als Bestandteil des Wegeventilblocks ausgeführt sein.In addition, the steering valve can be designed as part of the directional control valve block.

Zusätzliche Vorteile ergeben sich, wenn ein oder mehrere Vorspannventile und/oder ein Senkbremsventil innerhalb des Tanks angeordnet sind. Vorspannventil und Senkbremsventil sind in den Rücklaufleitungen von hydraulischen Verbrauchern angeordnet. Auch diese Bauelemente können erfindungsgemäß innerhalb des Tanks angeordnet werden.Additional advantages arise when one or more bias valves and / or a lowering brake valve are disposed within the tank. The biasing valve and lowering brake valve are arranged in the return lines of hydraulic consumers. These components can also be arranged within the tank according to the invention.

Weitere Vorteile und Einzelheiten der Erfindung werden anhand des in der schematischen Figur dargestellten Ausführungsbeispiels näher erläutert.Further advantages and details of the invention will be explained in more detail with reference to the embodiment shown in the schematic figure.

Die Figur zeigt einen Tank 1 einer hydraulischen Anlage einer Arbeitsmaschine. Der Tank 1 ist mit einer Tankhaube 2 dicht verschlossen. Innerhalb des Tanks 1 sind erfindungsgemäß eine Reihe von Bauteilen der hydraulischen Anlage angeordnet.The figure shows a tank 1 of a hydraulic system of a working machine. The tank 1 is sealed with a tank cap 2. Within the tank 1, a number of components of the hydraulic system are arranged according to the invention.

Ein als Drehstrommotor ausgeführter elektrischer Antriebsmotor 3 befindet sich unterhalb der Füllstandslinie 4 des Tanks 1 und wird somit von dem ihn umgebenden Hydraulikfluid gekühlt. An den Antriebsmotor 3 angeflanscht ist eine Hydraulikpumpe 5, die von dem Antriebsmotor 3 angetrieben wird. Die Hydraulikpumpe 5 saugt über einen Ansaugfilter 6, der in einem Saugrohr 7 angeordnet ist, Hydraulikfluid aus dem Tank 1 an.An electric drive motor 3 designed as a three-phase motor is located below the filling level line 4 of the tank 1 and is thus cooled by the hydraulic fluid surrounding it. Flanged to the drive motor 3 is a hydraulic pump 5, which is driven by the drive motor 3. The hydraulic pump 5 sucks hydraulic fluid from the tank 1 via an intake filter 6 arranged in a suction pipe 7.

Im Bereich einer Ausgangsöffnung der Hydraulikpumpe 5 ist an die Hydraulikpumpe 5 ein Wegeventilblock 8 angeflanscht, der in diesem Ausführungsbeispiel ein Prioritätsventil 8a, ein Lenkventil 8b sowie zwei Wegeventile 8c, 8d umfaßt. Von dem Lenkventil 8b und den Wegeventilen 8c, 8d führen über eine Flanschplatte 10 hydraulische Druckleitungen 9 zu den jeweiligen hydraulischen Verbrauchern.In the region of an outlet opening of the hydraulic pump 5, a directional valve block 8 is flanged to the hydraulic pump 5, which in this embodiment comprises a priority valve 8a, a steering valve 8b and two-way valves 8c, 8d. Of the steering valve 8b and the directional control valves 8c, 8d lead via a flange plate 10 hydraulic pressure lines 9 to the respective hydraulic consumers.

In der Tankhaube 2 ist weiterhin eine Durchführung für elektrische Leitungen angeordnet. Hierbei sind eine Steuer- und Versorgungsleitung 11 für den elektrischen Antriebsmotor 3, sowie Signalleitungen 12 zu dem Lenkventil 8b und den Wegeventilen 8c, 8d vorgesehen. Die Signalleitungen sind mit den entsprechenden Bedienhebeln bzw. einem Lenkgeber verbunden, mit welchen elektrische Steuersignale erzeugt werden.In the tank cap 2, a passage for electrical lines is further arranged. Here, a control and supply line 11 for the electric drive motor 3, and signal lines 12 to the steering valve 8b and the directional valves 8c, 8d are provided. The signal lines are connected to the corresponding control levers or a steering transmitter, with which electrical control signals are generated.

Dargestellt sind weiterhin zwei Rücklaufleitungen 13, durch welche Hydraulikfluid von den verschiedenen hydraulischen Verbrauchern in den Tank 1 zurückfließt. Die Rücklaufleitungen 13 werden über eine Flanschplatte 14 durch die Tankhaube 2 in den Tank 1 geführt. In der in der Zeichnung rechten Rücklaufleitung, welche mit einem nicht dargestellten Hubzylinder der Arbeitsmaschine verbunden ist, befindet sich ein Senkbremsventil 15. Das Senkbremsventil 15 verhindert ein zu schnelles Abströmen von Hydrauliköl in den Tank 1 und ist daher geeignet, beispielsweise die Absenkbewegung einer Lastaufnahmevorrichtung zu bremsen. In der in der Zeichnung linken Rücklaufleitung befindet sich ein Vorspannventil 16, mit dem ein bestimmter vorgegebener Druck in der Rücklaufleitung aufrechterhalten wird.Also shown are two return lines 13 through which hydraulic fluid from the various hydraulic consumers flows back into the tank 1. The return lines 13 are guided via a flange plate 14 through the tank cap 2 into the tank 1. In the right in the drawing return line, which is connected to a not shown lifting cylinder of the machine, there is a lowering brake valve 15. The lowering brake valve 15 prevents too rapid outflow of hydraulic oil into the tank 1 and is therefore suitable, for example, the lowering movement of a load receiving device brake. In the left in the drawing, the return line is a bias valve 16, with which a certain predetermined pressure in the return line is maintained.

Erfindungsgemäß sind die Hydraulikpumpe 1, der Wegeventilblock 8, das Senkbremsventil 15 und das Vorspannventil 16 innerhalb des Tanks 1 angeordnet. Undichtheiten an diesen hydraulischen Bauteilen oder an ihren Verbindungsstellen führen daher nicht zu einer Verschmutzung der Arbeitsmaschine und deren Umgebung mit Hydraulikfluid. Stattdessen wird das ungewollt austretende Hydraulikfluid im Tank aufgefangen.According to the invention, the hydraulic pump 1, the directional control valve block 8, the lowering brake valve 15 and the biasing valve 16 are arranged inside the tank 1. Leaks in these hydraulic components or at their joints therefore do not lead to contamination of the machine and its environment with hydraulic fluid. Instead, the unintentionally leaking hydraulic fluid is collected in the tank.

Claims (11)

  1. Working machine, especially industrial truck, having a hydraulic system, which has at least one tank (1) for hydraulic fluid and at least one hydraulic pump (5), the hydraulic pump (5) being arranged within the tank (1), characterized in that at least one directional control valve (8c, 8d) is arranged within the tank (1).
  2. Working machine according to Claim 1, characterized in that an electrical drive motor (3) of the hydraulic pump (5) is arranged within the tank (1).
  3. Working machine according to Claim 1, characterized in that an electrical drive motor (3) of the hydraulic pump (5) is arranged outside the tank (1), a shaft, which connects the electrical drive motor (3) to the hydraulic pump (5), being sealed with respect to the tank (1) by a shaft sealing ring.
  4. Working machine according to one of Claims 1 to 3, characterized in that a priority valve (8a) is arranged within the tank (1).
  5. Working machine according to Claim 4, characterized in that the priority valve (8a) is fixed to the hydraulic pump (5) by means of a flange connection.
  6. Working machine according to one of Claims 1 to 5, characterized in that the directional control valve (8c, 8d) is designed such that it can be driven electrically.
  7. Working machine according to one of Claims 1 to 6, characterized in that two or more directional control valves (8c, 8d) which form a directional control valve block (8) are provided.
  8. Working machine according to one of Claims 4 to 7, characterized in that the priority valve (8a) is part of the directional control valve block (8).
  9. Working machine according to one of Claims 1 to 8, characterized in that a steering valve (8b) is arranged within the tank (1).
  10. Working machine according to Claim 9, characterized in that the steering valve (8b) is part of the directional control valve block (8).
  11. Working machine according to one of Claims 1 to 10, characterized in that one or more pilot valves (16) and/or a lowering braking valve (15) are arranged within the tank (1).
EP99123341A 1998-11-25 1999-11-23 Hydraulic system especially for an industrial truck Expired - Lifetime EP1004542B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19854417A DE19854417A1 (en) 1998-11-25 1998-11-25 Working machine, in particular industrial truck
DE19854417 1998-11-25

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EP1004542A1 EP1004542A1 (en) 2000-05-31
EP1004542B1 true EP1004542B1 (en) 2006-01-25

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EP (1) EP1004542B1 (en)
DE (2) DE19854417A1 (en)

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DE19854417A1 (en) 2000-05-31
US6290474B1 (en) 2001-09-18
DE59913077D1 (en) 2006-04-13
EP1004542A1 (en) 2000-05-31

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