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EP0759109B1 - Hydraulic system for a mobile machine such as a wheel loader - Google Patents

Hydraulic system for a mobile machine such as a wheel loader Download PDF

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Publication number
EP0759109B1
EP0759109B1 EP95917954A EP95917954A EP0759109B1 EP 0759109 B1 EP0759109 B1 EP 0759109B1 EP 95917954 A EP95917954 A EP 95917954A EP 95917954 A EP95917954 A EP 95917954A EP 0759109 B1 EP0759109 B1 EP 0759109B1
Authority
EP
European Patent Office
Prior art keywords
valve
directional control
hydraulic
control valve
channel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP95917954A
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German (de)
French (fr)
Other versions
EP0759109A1 (en
Inventor
Edwin Harnischfeger
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bosch Rexroth AG
Original Assignee
Mannesmann Rexroth AG
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Publication date
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Publication of EP0759109A1 publication Critical patent/EP0759109A1/en
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Expired - Lifetime legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2264—Arrangements or adaptations of elements for hydraulic drives
    • E02F9/2267—Valves or distributors
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2203—Arrangements for controlling the attitude of actuators, e.g. speed, floating function
    • E02F9/2207—Arrangements for controlling the attitude of actuators, e.g. speed, floating function for reducing or compensating oscillations
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2217—Hydraulic or pneumatic drives with energy recovery arrangements, e.g. using accumulators, flywheels
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2264—Arrangements or adaptations of elements for hydraulic drives
    • E02F9/2271—Actuators and supports therefor and protection therefor

Definitions

  • the invention is based on a hydraulic system for a mobile tool, especially used for a wheel loader is and the features from the preamble of the claim 1 has.
  • DE 39 09 205 C1 shows several directional control valves, one of which is used to move to the Lifting and lowering the loading shovel using hydraulic fluid to supply.
  • this directional valve has also a switch position in which the two pressure chambers each lift cylinder are connected to the tank.
  • this Switch position of the directional valve lies with the loading shovel Weight on the ground and can be leveled over this be pulled or pushed. It floats on the as it were Bottom, which is why the switch position of the directional valve in question is also referred to as the switch position "swimming".
  • the "swimming" function can be found in DE 41 29 509 A1 can also be realized with an additional directional valve, the two pressure chambers each in a switch position Lift cylinder connects with each other and with the tank.
  • the invention has for its object a hydraulic Control arrangement with the features from the preamble of the claim 1 evolve so that a compact and space-saving Construction is possible that the piping effort is reduced and that the production can be inexpensive.
  • a hydraulic system solved the features from the preamble of the claim 1 and in which according to the characterizing part of this claim the shut-off valve in the directional control valve via which the two pressure chambers of the hydraulic cylinder can be pressurized separately and / or can be connected together with the tank, is integrated that the hydraulic accumulator and the first pressure chamber of the hydraulic cylinder with each other via the control spool of the directional valve are connectable.
  • the system is not also one additional shut-off valve available. Rather, one of the Directional control valves also function the shut-off valve. With that the Piping costs less, the design is compact and saves space, and costs are reduced.
  • a first directional valve via the the two pressure chambers of the hydraulic cylinder alternately with one Hydraulic pump and can be connected to the tank, and a second directional valve available, through which the two pressure rooms together with are connectable to the tank, so by the function "Swimming" is feasible.
  • the shut-off valve is now advantageous integrated in the second directional valve, because then none fourth switching position for the first directional valve is necessary.
  • the directional valve 10 serves in addition to two lift cylinders connected in parallel to each other press and lift the loading shovel of a wheel loader and lower.
  • Each lift cylinder 13 contains in a cylinder housing 14 a piston 15 having a piston rod 16, which the inside of the housing 14 in a piston rod side, annular pressure chamber 17 and in a piston rod-side Divides pressure chamber 18.
  • the pressure chambers 17 on the piston rod side the lift cylinders 13 are connected to a consumer line 19 first port 20 of the directional valve 10 connected.
  • the Pressure chambers 18 are connected via a line 21 to a connection 21 of the directional valve 10 connected.
  • This directional valve 10 has a valve housing 25 through which in Direction of alignment with the directional control valve 11 a pressure channel 26, which is connected to the pressure connection of a hydraulic pump 27 and pass through a tank channel 28 into a tank 29 opens.
  • the opening cross sections of these two channels are by the position of the control slide 30 of the directional valve 10 unaffected.
  • Another through the valve housing 25 Channel 31 is called the circulation channel, which in a middle position of the control slide 30 is open and at a shift of the spool 30 from the spring-centered Center position in one or the other direction until it is completely closed off.
  • the circulation channel 31 also leads through the others on the directional valve section 11 remote side of section 10 arranged
  • Directional valve sections of the valve block 12 is through the Control spool of the other directional valve sections as well can be influenced by the control slide 30 and ultimately with connected to the pressure channel 26.
  • the spool is moved 30 from the middle position become the connection 21 with the pressure channel 26 and the connection 20 with the tank channel 28 connected.
  • the pressure spaces 18 are pressurized and relieves the pressure chambers 17 to the tank.
  • the piston rods 16 extend, the loading shovel of the wheel loader is raised.
  • the pressure spaces 17 are pressurized and relieves the pressure chambers 18 to the tank.
  • the loading shovel Lowers itself.
  • the housing 35 of the directional control valve 11 is largely the same as the housing 25 of the directional valve 10. It has a channel 36 in extension of the pressure channel 26 of the valve 10, a tank channel 38 in the extension of the tank channel 28 and a continuous circulation channel 41, which continues the circulation channel 31 of the directional valve 10.
  • the circulation channel 41 is, as can be seen from the circuit symbol, in each position of the control spool 40 of the directional valve 11 connected to the tank channel 38, so that it is also possible a permanent connection between the circulation channel 31 and the To produce tank channel 28 in the housing 25 of the directional control valve 10 and to dispense with a circulation channel in the housing 35 of the directional control valve 11.
  • the tank channels 28 and 38 are namely open to one another.
  • the channel 36 of the valve housing 35 to the pressure channel 26 the valve housing 25 shut off.
  • This barrier can already be provided in the mold for the valve housing 35, however, only be carried out afterwards.
  • the channel 36 is open. It is connected to a hydraulic accumulator 42.
  • the directional control valve 11 also has two consumer connections 20 and 21, with the consumer connection 20th as the corresponding connection of the directional valve 10 with the pressure chambers 17 and the consumer connection 21 as the corresponding Connection of the directional valve 10 with the pressure chambers 18 of the lift cylinders 13 is connected.
  • the control spool 40 In the spring-centered position of the control spool 40 are the two consumer connections 20 and 21 and channels 36 and 38 against each other cordoned off.
  • the consumer connections are in one side position 20 and 21 with the channel 38 and thus with the tank 29 connected while the channel 36 is blocked. Consequently the lift cylinder 13 prevails in both pressure chambers 17 and 18 Tank pressure.
  • the loading shovel of a wheel loader can be used for leveling of the soil can be pulled over it.
  • the control spool 40 is shifted into this position arbitrarily by the driver or automatically when the wheel loader has reached a certain driving speed. It then becomes an electromagnetically operable pilot valve 50 actuated and a control pressure chamber 51 of the directional valve 11, which in the rest position of the valve 50 is relieved to the tank with a Line 52 connected by the maximum control pressure that for the actuation of the directional control valves of block 12 are available stands, is acted upon.
  • the memory 42 is up to one via a filling valve arrangement 60 adjustable maximum pressure can be charged via the filling valve arrangement 60 with the pressure chambers 18 of the lift cylinders 13 connected.
  • a filling valve arrangement 60 adjustable maximum pressure can be charged via the filling valve arrangement 60 with the pressure chambers 18 of the lift cylinders 13 connected.
  • the connection could also be outside of the valve housing 35 or within the housing 25.
  • the valve assembly 60 includes a pressure reducing valve 61 and a connected between the pressure reducing valve and the hydraulic accumulator 42, check valve 62 opening towards the hydraulic accumulator.
  • the pressure spaces 18 the lift cylinder 13 are pressurized, so the Hydraulic accumulator 42 via the valves 61 and 62 up to that in the Pressure spaces 18 prevailing pressure, provided this pressure does not exceed a value set on the pressure reducing valve.
  • the pressure in the pressure chambers 18 usually remains below of the set value, so that in the hydraulic accumulator 42 occurred maximum pressure, which is due to the check valve 62 is held in the hydraulic accumulator.

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  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Operation Control Of Excavators (AREA)

Description

Die Erfindung geht aus von einer hydraulischen Anlage, die für ein mobiles Arbeitsgerät, insbesondere für einen Radlader verwendet wird und die die Merkmale aus dem Oberbegriff des Anspruchs 1 aufweist.The invention is based on a hydraulic system for a mobile tool, especially used for a wheel loader is and the features from the preamble of the claim 1 has.

Aus der DE 39 09 205 C1 ist es bekannt, die Nickschwingungen von Radladern, die insbesondere bei gefüllter Ladeschaufel und höherer Fahrgeschwindigkeit auftreten, mit einem Dämpfungssystem zu dämpfen, das Bestandteil der hydraulischen Anlage des Radladers ist. Zur Schwingungsdämpfung sind die im allgemeinen zwei hydraulischen Liftzylinder zum Heben und Senken der Ladeschaufel über ein Absperrventil an einen Hydrospeicher anschließbar, der von einer Hydropumpe über eine Fülleitung aufgeladen werden kann. Das zwischen dem Hydrospeicher und den Liftzylindern angeordnete Absperrventil ist geschlossen, solange mit der Ladeschaufel gearbeitet wird, und kann vom Fahrer oder automatisch geöffnet werden, sobald beim Fahren Nickschwingungen auftreten oder sobald die Fahrgeschwindigkeit über einem bestimmten Wert von z.B. 6 km/h liegt. Zu einer hydraulischen Steueranordnung eines Radladers gehören, wie dies auch die DE 39 09 205 C1 zeigt, mehrere Wegeventile, von denen eines dazu dient, um zum Heben und Senken der Ladeschaufel die Liftzylinder mit Druckmittel zu versorgen. Nach der DE 39 09 205 C1 besitzt dieses Wegeventil auch eine Schaltstellung, in der die beiden Druckräume jedes Liftzylinders mit dem Tank verbunden sind. In dieser Schaltstellung des Wegeventils liegt die Ladeschaufel mit ihrem Gewicht auf dem Boden auf und kann zur Planierung über diesen gezogen oder geschoben werden. Sie schwimmt gleichsam auf dem Boden, weshalb die betreffende Schaltstellung des Wegeventils auch als die Schaltstellung "Schwimmen" bezeichnet wird. Die Funktion "Schwimmen" kann, wie dies der DE 41 29 509 A1 entnehmbar ist, auch durch ein zusätzliches Wegeventil realisiert werden, das in einer Schaltstellung die beiden Druckräume jedes Liftzylinders miteinander und mit Tank verbindet.It is known from DE 39 09 205 C1 to describe the pitching vibrations of Wheel loaders, especially when the bucket is filled and higher Driving speed occur with a damping system too dampen, the component of the hydraulic system of the wheel loader is. There are generally two for vibration damping hydraulic lift cylinder for lifting and lowering the loading shovel Can be connected to a hydraulic accumulator via a shut-off valve can be charged by a hydraulic pump via a filling line can. The one located between the hydraulic accumulator and the lift cylinders Shut-off valve is closed as long as with the loading shovel is worked, and can be done by the driver or automatically be opened as soon as pitching vibrations occur while driving or as soon as the driving speed is above a certain value from e.g. 6 km / h. To a hydraulic control arrangement belong to a wheel loader, as is also the DE 39 09 205 C1 shows several directional control valves, one of which is used to move to the Lifting and lowering the loading shovel using hydraulic fluid to supply. According to DE 39 09 205 C1, this directional valve has also a switch position in which the two pressure chambers each lift cylinder are connected to the tank. In this Switch position of the directional valve lies with the loading shovel Weight on the ground and can be leveled over this be pulled or pushed. It floats on the as it were Bottom, which is why the switch position of the directional valve in question is also referred to as the switch position "swimming". The The "swimming" function can be found in DE 41 29 509 A1 can also be realized with an additional directional valve, the two pressure chambers each in a switch position Lift cylinder connects with each other and with the tank.

Der Erfindung liegt die Aufgabe zugrunde, eine hydraulische Steueranordnung mit den Merkmalen aus dem Oberbegriff des Anspruchs 1 so weiterzuentwickeln, daß eine kompakte und platzsparende Bauweise möglich ist, daß der Verrohrungsaufwand verringert wird und daß die Herstellung kostengünstig sein kann.The invention has for its object a hydraulic Control arrangement with the features from the preamble of the claim 1 evolve so that a compact and space-saving Construction is possible that the piping effort is reduced and that the production can be inexpensive.

Diese Aufgabe wird erfindungsgemäß durch eine hydraulische Anlage gelöst, die die Merkmale aus dem Oberbegriff des Anspruchs 1 aufweist und bei der gemäß dem kennzeichnenden Teil dieses Anspruchs das Absperrventil derart in das Wegeventil, über das die beiden Druckräume des Hydraulikzylinders getrennt mit Druck beaufschlagbar und/oder gemeinsam mit dem Tank verbindbar sind, integriert ist, daß der Hydrospeicher und der erste Druckraum des Hydrozylinders über den Steuerschieber des Wegeventils miteinander verbindbar sind. Bei einer erfindungsgemäßen hydraulischen Anlage ist also neben den Wegeventilen nicht auch noch ein zusätzliches Absperrventil vorhanden. Vielmehr erfüllt eines der Wegeventile auch die Funktion des Absperrventils. Damit wird der Aufwand für die Verrohrung geringer, die Bauweise ist kompakt und platzsparend, und die Kosten sind reduziert.This object is achieved by a hydraulic system solved the features from the preamble of the claim 1 and in which according to the characterizing part of this claim the shut-off valve in the directional control valve via which the two pressure chambers of the hydraulic cylinder can be pressurized separately and / or can be connected together with the tank, is integrated that the hydraulic accumulator and the first pressure chamber of the hydraulic cylinder with each other via the control spool of the directional valve are connectable. In a hydraulic In addition to the directional control valves, the system is not also one additional shut-off valve available. Rather, one of the Directional control valves also function the shut-off valve. With that the Piping costs less, the design is compact and saves space, and costs are reduced.

Vorteilhafte Ausgestaltungen einer erfindungsgemäßen hydraulischen Anlage kann man den Unteransprüchen entnehmen.Advantageous configurations of a hydraulic system according to the invention Attachment can be found in the subclaims.

So wird gemäß Anspruch 2 während einer Verbindung des ersten Druckraums mit dem Hydrospeicher gleichzeitig der zweite Druckraum mit dem Tank verbunden. Somit kann im zweiten Druckraum kein Unterdruck entstehen und der Kolben des Hydrozylinders kann kavitationsfrei schwingen.So according to claim 2 during a connection of the first Pressure chamber with the hydraulic accumulator at the same time the second pressure chamber connected to the tank. Thus, in the second pressure room No negative pressure is created and the piston of the hydraulic cylinder can swing without cavitation.

Gemäß Anspruch 3 sind in Übereinstimmung mit der hydraulischen Anlage nach der DE 41 29 509 Al ein erstes Wegeventil, über das die beiden Druckräume des Hydrozylinders wechselweise mit einer Hydropumpe und mit dem Tank verbindbar sind, und ein zweites Wegeventil vorhanden, über das die beiden Druckräume gemeinsam mit dem Tank verbindbar sind, durch das also die Funktion "Schwimmen" realisierbar ist. Vorteilhafterweise ist nun das Absperrventil in das zweite Wegeventil integriert, weil dann keine vierte Schaltstellung für das erste Wegeventil notwendig ist.According to claim 3 are in accordance with the hydraulic System according to DE 41 29 509 Al a first directional valve, via the the two pressure chambers of the hydraulic cylinder alternately with one Hydraulic pump and can be connected to the tank, and a second directional valve available, through which the two pressure rooms together with are connectable to the tank, so by the function "Swimming" is feasible. The shut-off valve is now advantageous integrated in the second directional valve, because then none fourth switching position for the first directional valve is necessary.

Gemäß Anspruch 4 kann nicht nur die Verbindung des ersten Druckraums des Hydrozylinders mit dem Hydrospeicher, sondern auch die Verbindung des zweiten Druckraums mit dem Tank durch eine Betätigung des zweiten Wegeventils hergestellt werden. Sieht man einmal von einem eventuellen Vorsteuerventil für das zweite Wegeventil ab, so muß also außer diesem Wegeventil kein weiteres Wegeventil für die Funktion "Dämpfen" der hydraulischen Anlage betätigt werden.According to claim 4, not only the connection of the first pressure chamber of the hydraulic cylinder with the hydraulic accumulator, but also the Connection of the second pressure chamber to the tank by actuation of the second directional valve. One sees once from a possible pilot valve for the second directional valve so there is no need for any other than this directional valve Directional control valve for the "damping" function of the hydraulic system be operated.

Gemäß Anspruch 5 sind für das zweite Wegeventil und ein weiteres Wegeventil, die benachbarte Sektionen eines Ventilblocks bilden, im wesentlichen gleich ausgebildete Ventilgehäuse verwendet.According to claim 5 are for the second directional valve and another Directional control valve, which form adjacent sections of a valve block, used essentially the same valve housing.

Ein Ausführungsbeispiel einer erfindungsgemäßen hydraulischen Anlage ist in der Zeichnung dargestellt. Anhand dieser Zeichnung wird die Erfindung nun näher erläutert.An embodiment of a hydraulic according to the invention The system is shown in the drawing. From this drawing the invention will now be explained in more detail.

In der Zeichnung erkennt man ein erstes Wegeventil 10 und ein zweites Wegeventil 11, die unmittelbar benachbarte Sektionen eines Ventilblocks 12 bilden, zu dem noch weitere nicht näher dargestellte Wegeventilsektionen gehören. Das Wegeventil 10 dient dazu, um zwei parallel zueinander geschaltete Liftzylinder zu betätigen und über diese die Ladeschaufel eines Radladers zu heben und zu senken. Jeder Liftzylinder 13 enthält in einem Zylindergehäuse 14 einen eine Kolbenstange 16 aufweisenden Kolben 15, der das Innere des Gehäuses 14 in einen kolbenstangenseitigen, ringförmigen Druckraum 17 und in einen kolbenstangenabseitigen Druckraum 18 aufteilt. Die kolbenstangenseitigen Druckräume 17 der Liftzylinder 13 sind über eine Verbraucherleitung 19 mit einem ersten Anschluß 20 des Wegeventils 10 verbunden. Die Druckräume 18 sind über eine Leitung 21 mit einem Anschluß 21 des Wegeventils 10 verbunden. In the drawing, a first directional valve 10 and one can be seen second directional valve 11, the immediately adjacent sections of a Form valve block 12, to the still further not shown Directional valve sections belong. The directional valve 10 serves in addition to two lift cylinders connected in parallel to each other press and lift the loading shovel of a wheel loader and lower. Each lift cylinder 13 contains in a cylinder housing 14 a piston 15 having a piston rod 16, which the inside of the housing 14 in a piston rod side, annular pressure chamber 17 and in a piston rod-side Divides pressure chamber 18. The pressure chambers 17 on the piston rod side the lift cylinders 13 are connected to a consumer line 19 first port 20 of the directional valve 10 connected. The Pressure chambers 18 are connected via a line 21 to a connection 21 of the directional valve 10 connected.

Dieses Wegeventil 10 besitzt ein Ventilgehäuse 25, durch das in Richtung der Aneinanderreihung mit dem Wegeventil 11 ein Druckkanal 26, der mit dem Druckanschluß einer Hydropumpe 27 verbunden ist, und ein Tankkanal 28 hindurchgehen, der in einen Tank 29 mündet. Die Öffnungsquerschnitte dieser beiden Kanäle werden durch die Position des Steuerschiebers 30 des Wegeventils 10 nicht beeinflußt. Ein weiterer durch das Ventilgehäuse 25 hindurchgehender Kanal 31 wird als Umlaufkanal bezeichnet, der in einer Mittelstellung des Steuerschiebers 30 offen ist und bei einer Verlagerung des Steuerschiebers 30 aus der federzentrierten Mittelstellung heraus in die eine oder in die andere Richtung bis zur völligen Absperrung immer mehr verschlossen wird. Der Umlaufkanal 31 führt auch durch die weiteren auf der der Wegeventilsektion 11 abgelegenen Seite der Sektion 10 angeordneten Wegeventilsektionen des Ventilblocks 12 hindurch, ist durch die Steuerschieber der weiteren Wegeventilsektionen genauso wie durch den Steuerschieber 30 beeinflußbar und letztendlich mit dem Druckkanal 26 verbunden. Bei einer Verlagerung des Steuerschiebers 30 aus der Mittelstellung heraus werden der Anschluß 21 mit dem Druckkanal 26 und der Anschluß 20 mit dem Tankkanal 28 verbunden. Dadurch werden die Druckräume 18 mit Druck beaufschlagt und die Druckräume 17 zum Tank entlastet. Die Kolbenstangen 16 fahren aus, die Ladeschaufel des Radladers wird gehoben. Bei einer Verlagerung des Steuerschiebers 30 in die entgegengesetzte Richtung werden die Druckräume 17 mit Druck beaufschlagt und die Druckräume 18 zum Tank entlastet. Die Ladeschaufel senkt sich.This directional valve 10 has a valve housing 25 through which in Direction of alignment with the directional control valve 11 a pressure channel 26, which is connected to the pressure connection of a hydraulic pump 27 and pass through a tank channel 28 into a tank 29 opens. The opening cross sections of these two channels are by the position of the control slide 30 of the directional valve 10 unaffected. Another through the valve housing 25 Channel 31 is called the circulation channel, which in a middle position of the control slide 30 is open and at a shift of the spool 30 from the spring-centered Center position in one or the other direction until it is completely closed off. The circulation channel 31 also leads through the others on the directional valve section 11 remote side of section 10 arranged Directional valve sections of the valve block 12 is through the Control spool of the other directional valve sections as well can be influenced by the control slide 30 and ultimately with connected to the pressure channel 26. When the spool is moved 30 from the middle position become the connection 21 with the pressure channel 26 and the connection 20 with the tank channel 28 connected. As a result, the pressure spaces 18 are pressurized and relieves the pressure chambers 17 to the tank. The piston rods 16 extend, the loading shovel of the wheel loader is raised. When the spool 30 is shifted to the opposite one Direction, the pressure spaces 17 are pressurized and relieves the pressure chambers 18 to the tank. The loading shovel Lowers itself.

Das Gehäuse 35 des Wegeventils 11 ist weitgehend gleich dem Gehäuse 25 des Wegeventils 10. Es besitzt einen Kanal 36 in Verlängerung des Druckkanals 26 des Ventils 10, einen Tankkanal 38 in Verlängerung des Tankkanals 28 und einen durchgehenden Umlaufkanal 41, der den Umlaufkanal 31 des Wegeventils 10 fortsetzt. Der Umlaufkanal 41 ist, wie man aus dem Schaltsymbol ersieht, in jeder Position des Steuerschiebers 40 des Wegeventils 11 mit dem Tankkanal 38 verbunden, so daß es auch möglich ist, eine dauernde Verbindung zwischen dem Umlaufkanal 31 und dem Tankkanal 28 im Gehäuse 25 des Wegeventils 10 herzustellen und auf einen Umlaufkanal im Gehäuse 35 des Wegeventils 11 zu verzichten. Die Tankkanäle 28 und 38 sind nämlich zueinander offen. Dagegen ist der Kanal 36 des Ventilgehäuses 35 zum Druckkanal 26 des Ventilgehäuses 25 hin abgesperrt. Diese Absperrung kann schon in der Gußform für das Ventilgehäuse 35 vorgesehen sein, jedoch auch erst nachträglich erfolgen. Zur dem Wegeventil 10 abgewandten Seite des Ventilgehäuses 35 hin ist der Kanal 36 offen. Er ist an einen Hydrospeicher 42 angeschlossen.The housing 35 of the directional control valve 11 is largely the same as the housing 25 of the directional valve 10. It has a channel 36 in extension of the pressure channel 26 of the valve 10, a tank channel 38 in the extension of the tank channel 28 and a continuous circulation channel 41, which continues the circulation channel 31 of the directional valve 10. The circulation channel 41 is, as can be seen from the circuit symbol, in each position of the control spool 40 of the directional valve 11 connected to the tank channel 38, so that it is also possible a permanent connection between the circulation channel 31 and the To produce tank channel 28 in the housing 25 of the directional control valve 10 and to dispense with a circulation channel in the housing 35 of the directional control valve 11. The tank channels 28 and 38 are namely open to one another. In contrast, the channel 36 of the valve housing 35 to the pressure channel 26 the valve housing 25 shut off. This barrier can already be provided in the mold for the valve housing 35, however, only be carried out afterwards. To the directional valve 10 opposite side of the valve housing 35, the channel 36 is open. It is connected to a hydraulic accumulator 42.

Wie das Wegeventil 10 besitzt auch das Wegeventil 11 zwei Verbraucheranschlüsse 20 und 21, wobei der Verbraucheranschluß 20 wie der entsprechende Anschluß des Wegeventils 10 mit den Druckräumen 17 und der Verbraucheranschluß 21 wie der entsprechende Anschluß des Wegeventils 10 mit den Druckräumen 18 der Liftzylinder 13 verbunden ist. In der wiederum federzentrierten Mittelstellung des Steuerschiebers 40 sind die beiden Verbraucheranschlüsse 20 und 21 sowie die Kanäle 36 und 38 gegeneinander abgesperrt. In der einen seitlichen Stellung sind die Verbraucheranschlüsse 20 und 21 mit dem Kanal 38 und somit mit dem Tank 29 verbunden, während der Kanal 36 abgesperrt ist. Somit herrscht in beiden Druckräumen 17 und 18 der Liftzylinder 13 Tankdruck. Die Ladeschaufel eines Radladers kann zum Planieren des Bodens über diesen hinweggezogen werden. Durch die entsprechende Betätigung des Steuerschiebers 40 wird also die Funktion "Schwimmen" realisiert. Bei einer Verlagerung des Steuerschiebers 40 aus der Mittelstellung heraus in die entgegengesetzte Richtung wird der Anschluß 20 des Wegeventils 11 mit dem Kanal 38, also mit dem Tank 29, und der Anschluß 21 mit dem Kanal 36, also mit dem Hydrospeicher 42 verbunden. Die Druckräume 17 der Liftzylinder 13 sind dadurch zum Tank entlastet, während die Druckräume 18 mit dem Hydrospeicher 42 verbunden sind. Es kann also Öl zwischen den Druckräumen 18 und dem Hydrospeicher 42 hin und her geschoben werden, so daß der Ausleger des Radladers mit der Ladeschaufel und der Lader selbst kein starres System mehr bilden und Nickschwingungen gedämpft werden. Like the directional control valve 10, the directional control valve 11 also has two consumer connections 20 and 21, with the consumer connection 20th as the corresponding connection of the directional valve 10 with the pressure chambers 17 and the consumer connection 21 as the corresponding Connection of the directional valve 10 with the pressure chambers 18 of the lift cylinders 13 is connected. In the spring-centered position of the control spool 40 are the two consumer connections 20 and 21 and channels 36 and 38 against each other cordoned off. The consumer connections are in one side position 20 and 21 with the channel 38 and thus with the tank 29 connected while the channel 36 is blocked. Consequently the lift cylinder 13 prevails in both pressure chambers 17 and 18 Tank pressure. The loading shovel of a wheel loader can be used for leveling of the soil can be pulled over it. By the appropriate Actuation of the control slide 40 becomes the function "Swimming" realized. When the spool is moved 40 from the middle position to the opposite Direction becomes the connection 20 of the directional valve 11 with the channel 38, ie with the tank 29, and the connection 21 with the channel 36, thus connected to the hydraulic accumulator 42. The pressure rooms 17 of the Lift cylinders 13 are thereby relieved to the tank, while the Pressure chambers 18 are connected to the hydraulic accumulator 42. It can thus oil between the pressure chambers 18 and the hydraulic accumulator 42 and pushed so that the boom of the wheel loader with the loading shovel and the loader itself are no longer a rigid system form and pitch vibrations are damped.

Durch die weitere seitliche Stelllung des Steuerschiebers 40 ist also die Funktion "Dämpfen" realisiert.Due to the further lateral position of the control slide 40 the "steaming" function is implemented.

Eine Verlagerung des Steuerschiebers 40 in diese Position erfolgt willkürlich vom Fahrzeugführer oder automatisch dann, wenn der Radlader eine bestimmte Fahrgeschwindigkeit erreicht hat. Es wird dann ein elektromagnetisch betätigbares Vorsteuerventil 50 betätigt und ein Steuerdruckraum 51 des Wegeventils 11, der in der Ruhestellung des Ventils 50 zum Tank entlastet ist, mit einer Leitung 52 verbunden, die vom maximalen Steuerdruck, der für die Betätigung der Wegeventile des Blocks 12 zur Verfügung steht, beaufschlagt ist.The control spool 40 is shifted into this position arbitrarily by the driver or automatically when the wheel loader has reached a certain driving speed. It then becomes an electromagnetically operable pilot valve 50 actuated and a control pressure chamber 51 of the directional valve 11, which in the rest position of the valve 50 is relieved to the tank with a Line 52 connected by the maximum control pressure that for the actuation of the directional control valves of block 12 are available stands, is acted upon.

Der Speicher 42 ist über eine Füllventilanordnung 60 bis zu einem einstellbaren Höchstdruck aufladbar und dazu über die Füllventilanordnung 60 mit den Druckräumen 18 der Liftzylinder 13 verbunden. Im vorliegenden Beispiel geschieht dies dadurch, daß die Ventilanordnung 60 innerhalb des Ventilgehäuses 35 des Wegeventils 11 mit einem zum Anschluß 21 dieses Ventils führenden Kanal verbunden ist. Die Anbindung könnte jedoch auch außerhalb des Ventilgehäuses 35 oder innerhalb des Gehäuses 25 erfolgen. Die Ventilanordnung 60 umfaßt ein Druckminderventil 61 und ein zwischen das Druckminderventil und den Hydrospeicher 42 geschaltetes, zum Hydrospeicher hin öffnendes Rückschlagventil 62.The memory 42 is up to one via a filling valve arrangement 60 adjustable maximum pressure can be charged via the filling valve arrangement 60 with the pressure chambers 18 of the lift cylinders 13 connected. In the present example, this happens because the valve assembly 60 within the valve housing 35 of the directional valve 11 with a leading to port 21 of this valve Channel is connected. However, the connection could also be outside of the valve housing 35 or within the housing 25. The valve assembly 60 includes a pressure reducing valve 61 and a connected between the pressure reducing valve and the hydraulic accumulator 42, check valve 62 opening towards the hydraulic accumulator.

Wenn durch eine Betätigung des Wegeventils 10 die Druckräume 18 der Liftzylinder 13 mit Druck beaufschlagt werden, so wird der Hydrospeicher 42 über die Ventile 61 und 62 bis zu dem in den Druckräumen 18 herrschenden Druck gefüllt, sofern dieser Druck einen am Druckminderventil eingestellten Wert nicht überschreitet. Üblicherweise bleibt der Druck in den Druckräumen 18 unterhalb des eingestellten Wertes, so daß im Hydrospeicher 42 der aufgetretene Höchstdruck herrscht, der durch das Rückschlagventil 62 im Hydrospeicher gehalten wird.If, by actuating the directional control valve 10, the pressure spaces 18 the lift cylinder 13 are pressurized, so the Hydraulic accumulator 42 via the valves 61 and 62 up to that in the Pressure spaces 18 prevailing pressure, provided this pressure does not exceed a value set on the pressure reducing valve. The pressure in the pressure chambers 18 usually remains below of the set value, so that in the hydraulic accumulator 42 occurred maximum pressure, which is due to the check valve 62 is held in the hydraulic accumulator.

Claims (5)

  1. A hydraulic system for a mobile working device, in particular for a wheel loader, having a working tool, in particular a loading shovel, which can be actuated via at least one hydraulic cylinder (13) having a piston (15) which divides the inside of the hydraulic cylinder (13) into two pressure chambers (17, 18), having a shut-off valve via which the first of the two pressure chambers (17, 18) can be connected to a hydraulic accumulator (42) which can be charged via a filling line, and having a directional control valve (11) with a control spool (40) for the separate pressurization and/or for the connecting of the two pressure chambers (17, 18) of the hydraulic cylinder (13) to a tank (29), characterized in that the shut-off valve is so integrated in the directional control valve (11) that the hydraulic accumulator (42) and the first pressure chamber (18) of the hydraulic cylinder (13) can be connected with each other via the control spool (40) of the directional control valve (11).
  2. A hydraulic system according to Claim 1, characterized in that during a connection of the first pressure chamber (18) to the hydraulic accumulator (42) the second pressure chamber (17) is connected to the tank (29).
  3. A hydraulic system according to Claim 1 or 2, characterized in that the two pressure chambers (17, 18) of the hydraulic cylinder (13) can be connected via a first directional control valve (10) alternately to a hydraulic pump (27) and the tank (29), that the two pressure chambers (17, 18) can be connected jointly with the tank via a second directional control valve (11), and that the shut-off valve is integrated in the second directional control valve (11).
  4. A hydraulic system according to Claims 2 and 3, characterized in that both the connection of the first pressure chamber (18) of the hydraulic cylinder (13) to the hydraulic accumulator (42) and the connection of the second pressure chamber (17) to the tank (29) can be produced by an actuation of the second directional control valve (11).
  5. A hydraulic system according to Claim 3 or 4, characterized in that the second directional control valve (11) and a further directional control valve (10) are adjacent sections of a valve block (12), that the second directional control valve (11) and the further directional control valve (10) have valve housings (25, 35) which are substantially of identical design and have a channel (26, 36) extending in the direction of the arrangement one behind the other, aligned with the channel (36, 26) of the other valve housing (35, 32), from which channel (26, 36) a connection exists to the valve bore receiving the corresponding control spool (30, 40), that the two channels (26, 36) are closed off from each other and that the channel (36) of the second directional control valve (11) is connected to the hydraulic accumulator (42) and the channel (26) of the further directional control valve (10 ) is connected to the pressure port of the hydraulic pump (27).
EP95917954A 1994-05-07 1995-04-25 Hydraulic system for a mobile machine such as a wheel loader Expired - Lifetime EP0759109B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE4416228A DE4416228A1 (en) 1994-05-07 1994-05-07 Hydraulic system for a mobile working device, in particular for a wheel loader
DE4416228 1994-05-07
PCT/EP1995/001556 WO1995030800A1 (en) 1994-05-07 1995-04-25 Hydraulic system for a mobile machine such as a wheel loader

Publications (2)

Publication Number Publication Date
EP0759109A1 EP0759109A1 (en) 1997-02-26
EP0759109B1 true EP0759109B1 (en) 1999-01-13

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Application Number Title Priority Date Filing Date
EP95917954A Expired - Lifetime EP0759109B1 (en) 1994-05-07 1995-04-25 Hydraulic system for a mobile machine such as a wheel loader

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US (1) US5802847A (en)
EP (1) EP0759109B1 (en)
JP (1) JPH09512869A (en)
KR (1) KR970702951A (en)
DE (2) DE4416228A1 (en)
WO (1) WO1995030800A1 (en)

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Also Published As

Publication number Publication date
EP0759109A1 (en) 1997-02-26
JPH09512869A (en) 1997-12-22
KR970702951A (en) 1997-06-10
US5802847A (en) 1998-09-08
DE4416228A1 (en) 1995-11-09
WO1995030800A1 (en) 1995-11-16
DE59504825D1 (en) 1999-02-25

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