EP2256082B1 - Hydrostatic drive system for a mobile work machine - Google Patents

Hydrostatic drive system for a mobile work machine Download PDF

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Publication number
EP2256082B1
EP2256082B1 EP10004441.1A EP10004441A EP2256082B1 EP 2256082 B1 EP2256082 B1 EP 2256082B1 EP 10004441 A EP10004441 A EP 10004441A EP 2256082 B1 EP2256082 B1 EP 2256082B1
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EP
European Patent Office
Prior art keywords
pressure
valve
line
pump
brake
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.)
Not-in-force
Application number
EP10004441.1A
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German (de)
French (fr)
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EP2256082B9 (en
EP2256082A2 (en
EP2256082A3 (en
Inventor
Markus Schwab
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STILL GmbH
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STILL GmbH
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Publication date
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Publication of EP2256082A2 publication Critical patent/EP2256082A2/en
Publication of EP2256082A3 publication Critical patent/EP2256082A3/en
Application granted granted Critical
Publication of EP2256082B1 publication Critical patent/EP2256082B1/en
Publication of EP2256082B9 publication Critical patent/EP2256082B9/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
    • F15B7/00—Systems in which the movement produced is definitely related to the output of a volumetric pump; Telemotors
    • F15B7/003—Systems in which the movement produced is definitely related to the output of a volumetric pump; Telemotors with multiple outputs

Definitions

  • the invention relates to a hydrostatic drive system of a mobile work machine, in particular a truck, with a pump which is provided to supply at least one consumer of a working hydraulics and a hydraulic steering, as well as with a hydraulic means of a brake pressure controllable braking device, which is designed as a spring brake and means the brake pressure is applied in a release position, wherein in a delivery line of the pump, a priority valve for the preferred supply of the steering is arranged and wherein for generating the brake pressure with the delivery line of the pump upstream of the priority valve of the steering in communication associated control pressure line is provided.
  • a biasing valve is arranged in a guided from the working hydraulic conveyor line container circulation line whose spring preload corresponds to the required brake pressure, so that by throttling over the biasing valve for Container outflowing pressure medium of the brake pressure is generated.
  • a drive system result in high energy losses, since the spring bias of the priority valve and the bias of the biasing valve are received as losses in the generation of the brake pressure.
  • the DE 20 2004 010 530 U1 discloses a hydrostatic drive system of a vehicle in which a hydraulic steering is associated with an additional priority valve with a pressure reducing function with which the pressure level of the hydraulic steering can be limited to reduce the construction cost of the steering.
  • a drive system of a truck is known in which the brake release line of the spring brake is connected upstream of a priority valve to the delivery line of the pump.
  • the pressure generated in the delivery line of the pump from the bias of the spring on the priority valve and the spring on a circulation pressure compensator is insufficient to actuate the spring brake in the release position.
  • the circulation pressure compensator is to be operated in the blocking position to achieve a corresponding pressure build-up upstream of the priority valve.
  • an additional shut-off valve is arranged in a consumer line of a consumer, for example the tilt drive, so that a load pressure is generated by actuating the directional control valve against the shut-off consumer line.
  • the present invention has for its object to provide a generic drive system available, in which the brake pressure for applying the hydraulic braking device can be generated with low construction costs and low energy losses.
  • This object is achieved according to the invention in that, when the load of the braking device is not actuated, the braking force for actuating the braking device is provided in the release position at each operating point without additional energy losses from the system pressure generated by the pump in the delivery line upstream of the priority valve.
  • the idea according to the invention thus consists of tapping the brake pressure upstream of the priority valve of the steering directly from the delivery line of the pump and thus producing the system pressure of the pump upstream of the priority valve so that the bias of the priority valve and the pressure drop occurring at the priority valve for Generation of the brake pressure can be exploited.
  • a generation of the brake pressure without additional energy losses with only one pump can be achieved, whereby the drive system according to the invention further has a low construction cost.
  • the braking device is designed as Federspeichürbremse, which can be acted upon by the brake pressure in a release position.
  • a corresponding brake valve such as a controllable pressure reducing valve, in this case the brake pressure can be reduced controlled, so that the spring brake is used as a service brake.
  • the priority valve is expediently acted upon by means of a spring in the direction of a conveying line connecting the pump to the steering position.
  • the upstream of the priority valve system pressure is determined by the spring bias of the spring of the priority valve, which can be made available from the system pressure in a simple way, the required brake pressure for safe operation of the braking device.
  • control pressure line is guided to a brake valve of the braking device, wherein in the control pressure line, a pressure reducing valve is arranged.
  • a pressure reducing valve in the control pressure line, a constant brake pressure level at the brake valve can be achieved in a simple manner with changing delivery pressure of the pump and thus with changing system pressure upstream of the priority valve.
  • the drive system according to the invention can be designed as a so-called open-center system in which the pump is designed as a constant pump and a control valve device for controlling the working hydraulics has a circulation pressure compensator, the highest load pressure of the load of the working hydraulics and a spring in the direction of a blocking position and the delivery pressure of the pump is applied in the direction of a flow position.
  • the system pressure upstream of the priority valve at non-actuated consumers is also determined by the spring bias of the spring of the rotary pressure balance, which with the connected to the delivery line of the pump upstream of the priority valve control pressure line and disposed in this pressure reducing valve in a simple manner, the required brake pressure Braking device can be generated without additional energy losses from the system pressure upstream of the priority valve.
  • the spring bias of the priority valve of the steering and / or spring preload the circulation pressure compensator adjusted such that a minimum brake pressure in the control pressure line can be generated at each operating point.
  • the drive system according to the invention can also be designed as a so-called closed-center system, in which the pump is controlled as load-sensing Variable displacement pump is formed, which is controlled by the highest load pressure of the working hydraulics and / or the steering.
  • a variable delivers when not driven consumers of the working hydraulics and / or non-actuated steering a standby pressure as a controlled variable of the variable, which is present as system pressure in the delivery line upstream of the priority valve of the steering and from the means of the delivery line to the pump upstream of the priority valve connected control pressure line in a simple manner, the minimum required brake pressure for safe operation of the braking device can be generated without additional energy losses.
  • the load pressure signaling line routed to a delivery volume adjusting device of the pump can be in communication with the control pressure line.
  • the variable displacement pump is thus also controlled by the pending in the control pressure line brake pressure, so that is achieved in a simple manner that in all operating conditions, the minimum brake pressure from the system pressure supplied by the variable system pressure upstream of the priority valve of the steering can be generated.
  • the system pressure of the pump drops below the minimum brake pressure in certain operating points, for example a lifting of a lifting drive without load.
  • the standby pressure and thus the controlled variable of the pump and / or the Spring bias of the priority valve are set such that at each operating point a minimum required brake pressure in the control pressure line can be generated, the required minimum brake pressure for safe operation of the braking device in a simple manner in all operating conditions from the system pressure generated by the pump upstream of the priority valve can be generated.
  • the pump can be driven by an internal combustion engine drive machine, such as an internal combustion engine, in which the pump is constantly in operation and provides a flow for generating the brake pressure.
  • the pump may be driven by an electric drive motor, the pump being actuated only when steering and / or working hydraulics are needed to provide a volumetric flow.
  • the control pressure line is associated with a pressure fluid reservoir.
  • a check valve opening in the direction of the pressure reducing valve is expediently arranged in the control pressure line upstream of the storage device and upstream of the pressure reducing valve.
  • a drive system for controlling the load of the working hydraulics in each case an electro-hydraulically actuated control valve, in particular a directional control valve, wherein a control pressure supply line of the control valve is in communication with the control pressure line.
  • electro-hydraulically actuated and pilot operated control valves to achieve high actuation forces for the control valve, a control pressure supply with a constant control pressure level is required, from which by means of appropriate pilot valves, a control pressure is generated for actuating the control valves.
  • control pressure level for the pilot control the control valves of the working hydraulics is usually at the level of the brake pressure of the brake device can be achieved by connecting the control pressure supply line for the pilot valves of the control valves to the brake pressure leading control pressure line in a simple way a control pressure supply for the pilot-operated control valves of the working hydraulics without additional construction costs ,
  • the control pressure supply line is expediently in communication with the control pressure line downstream of the pressure reducing valve.
  • the pending in the control pressure line between the pressure reducing valve and the brake valve brake pressure at a constant level can thereby be used in a simple manner as a control pressure supply with a constant level for the pilot-operated control valves of the working hydraulics.
  • FIG. 1 is an inventive, designed as an open-center system drive system of a designed example, designed as a truck work machine in a schematic circuit diagram.
  • the drive system comprises a fixed-displacement pump 1, which is operated in the open circuit and is provided to supply a working hydraulics 2 and a hydraulic steering 3.
  • the pump 1 sucks from a container and promotes in a delivery line 4, in the preferred supply of the steering 3, a priority valve 5 is arranged.
  • a delivery branch line 6 leads to the steering 3 and a delivery branch line 7 to a control valve 8 formed as a control valve block of the working hydraulics. 2
  • the priority valve 5 is by means of a spring 9 and the load in a load pressure branch line 10 of the steering 3 load pressure of the steering. 3 in the direction of the delivery line 4 with the delivery branch line 6 for the preferred supply of the steering 3 connecting position 5a acted upon.
  • the priority valve 5 can be acted upon in the direction of a position 5b, in which the delivery line 4 is connected to both delivery branch lines 6 and 7 for the simultaneous supply of the steering 3 and the working hydraulics 2.
  • the control valve device 8 of the working hydraulics 2 comprises a control valve 11 designed as a directional control valve for controlling each consumer of the working hydraulics 2
  • FIG. 1 are schematically illustrated control valves 11 for actuating a lifting drive 12, a tilt drive, not shown, and possibly an auxiliary drive, not shown, for example, a side slide, the working hydraulics 2 are provided.
  • a circulation pressure compensator 15 is arranged, which is arranged in a guided from the delivery branch line 7 to the container branch line.
  • the circulation pressure compensator 15 is acted upon by the highest load pressure of the consumers of the working hydraulics 2 and of a spring 17 in the direction of a blocking position and of the delivery pressure present in the delivery branch line 7 in the direction of a flow-through position in a load pressure signaling branch line 16.
  • the drive system according to the invention further comprises a hydraulically actuated braking device 20, for example a spring brake device, which is controllable by means of a brake valve 21, for example, an electrically controllable proportional pressure reducing valve.
  • a hydraulically actuated braking device 20 for example a spring brake device, which is controllable by means of a brake valve 21, for example, an electrically controllable proportional pressure reducing valve.
  • the brake valve 21 is the input side with a constant brake pressure leading control pressure line 25 in connection, which is according to the invention connected to the delivery line 4 of the pump 1 upstream of the priority valve 5 of the steering 3.
  • a pressure reducing valve 26 is arranged to keep the constant at the brake valve 21 pending brake pressure.
  • the control valves 11 for controlling the load of the working hydraulics 2 are each electro-hydraulically actuated.
  • electrically controlled pilot valves for example by means of a proportional solenoid operated pressure reducing valves, provided by means of which the control valves 11 actuated control pressures can be generated.
  • the pilot valves are to generate a corresponding control valve 11 actuated control pressure on the input side with a control pressure supply line 27 in connection with the control pressure line 25 between the pressure reducing valve 26 and the brake valve 21 is connected.
  • the pump 1 can be driven in an internal combustion engine powered truck by a designed as an internal combustion engine drive machine 28 and operated continuously during operation of the truck.
  • the drive machine 28 of the pump 1 is formed by an electric motor. Since the pump 1 of such a truck is driven by an electric drive system only upon actuation of the steering 3 and / or the working hydraulics 2, the control pressure line 25 upstream of the pressure reducing valve 26 is associated with a hydraulic accumulator 29.
  • a check valve 30 is arranged, for example, a check valve which opens in the direction of the pressure reducing valve 26.
  • FIG. 2 is an inventive, designed as a closed-center system drive system of an example designed as a truck work machine shown in a schematic circuit diagram.
  • the same components are provided here with the same reference numerals.
  • the pump 1 provided for supplying the working hydraulics 2 and the further load formed by the hydraulic steering 3 is designed as a load-sensing-controlled variable displacement pump.
  • a demand volume control device 40 designed as a demand flow control device is provided, which is controlled by the highest load pressure of the consumers of the drive system.
  • One of the highest load pressure of the consumer leading load pressure signaling line 41 is guided here to the Fordervolumenstell issued 40 of the pump 1.
  • the control valves 11 for controlling the load of the working hydraulics 2 according to the FIG. 2 are each electro-hydraulically actuated.
  • the non-illustrated electrically controlled pilot valves for example by means of a proportional solenoid operated pressure reducing valves, by means of which the control valves 11 actuated control pressures can be generated on the input side to the control pressure supply line 27 in connection, which branches off from the control pressure line 25 between the pressure reducing valve 26 and the brake valve 21.
  • the pump 1 the FIG. 2 can be provided in addition to the supply of the steering 3 and the working hydraulics 2 continue to operate a further consumer, such as a fan drive 45, wherein a fan motor 46 is connected via a control valve 47 with the working hydraulics 2 guided delivery line 7 in combination.
  • a fan drive 45 wherein a fan motor 46 is connected via a control valve 47 with the working hydraulics 2 guided delivery line 7 in combination.
  • a load pressure detection chain 50 for detecting the highest load pressure of the load of the drive system and forwarding the highest load pressure to the Fordervolumenstell adopted 40 of the pump 1, is based on the brake pressure leading control pressure line 25 from.
  • the branch line 53 is connected to the output of another selection valve 54 designed as a shuttle valve, which is connected on the input side to the load pressure signaling branch line 10 of the steering system 3 and a branch line 55.
  • the branch line 55 communicates with the output of another selector valve 56 designed as a shuttle valve, which is connected on the input side to the load pressure signaling branch line 16 of the working hydraulics 2 and to a load pressure signaling line 57 of the fan drive 45, which leads to the highest load pressure of the consumers of the working hydraulics 2.
  • another selector valve 56 designed as a shuttle valve, which is connected on the input side to the load pressure signaling branch line 16 of the working hydraulics 2 and to a load pressure signaling line 57 of the fan drive 45, which leads to the highest load pressure of the consumers of the working hydraulics 2.
  • FIG. 2 is also according to the invention guided to the brake valve 21 control pressure line 25 connected to the delivery line 4 of the pump 1 upstream of the priority valve 5 of the steering 3, wherein in the control pressure line 25 to generate a constant control pressure levels designed as a pressure reducing valve 26, hydraulically controlled pressure reducing valve is arranged Setting the constant brake pressure level defined at the input of the brake valve 21.
  • the pressure reducing valve 26 is in accordance with FIGS. 1 . 2 provided with a spring.
  • the control pressure supply line 27 to the control pressure supply of the electro-hydraulically actuated control valves 11 of the working hydraulics 12 is analogous to the FIG. 1 connected to the control pressure line 25 between the pressure reducing valve 26 and the brake valve 21.
  • the pump 1 In a drive system according to the FIG. 1 or the FIG. 2 the pump 1, the flow for supplying the load of the working hydraulics 2 and the steering 3 and the optional fan drive 45 available.
  • the priority valve 5 prioritizes the steering 3 when actuated before the working hydraulics 2 and the optional fan drive 45 with simultaneous actuation of the steering 3 and the working hydraulics 2 and the fan drive 45.
  • the spring bias of the spring 9 of the priority valve 5 changes the performance of the priority valve 5 and determines the flow resistance and thus the pressure drop across the priority valve 5 of the steering 3.
  • the priority valve 5 When uncontrolled steering 3, the priority valve 5 is acted upon in the position 5b, in which the volume flow of the pump 1 completely flows to the control valve device 8 and thus the control valves 11 of the working hydraulics 2. At the priority valve 5 the Steering 3 occurs in this case a pressure difference, which is in direct dependence on the spring bias of the spring 9.
  • the circulation pressure compensator 15 In non-actuated control valves 11 of the working hydraulics 2, the circulation pressure compensator 15 according to the FIG. 1 acted upon in the flow position, provided that in the delivery branch line 7 pending system pressure exceeds the spring preload of the spring 17 of the rotary pressure compensator 15. As a result, flows in unconfirmed consumers of the working hydraulics 2 and uncontrolled steering 3, the full flow of the pump 1 via the priority valve 5 and the circulation pressure compensator 15 to the container.
  • the pressure difference at the circulation pressure compensator 15 is here in direct dependence on the spring preload of the spring 17.
  • the minimum required brake pressure in the control pressure line 25 is defined, which is required for safe operation of the braking device 20.
  • the spring bias of the spring 9 of the priority valve 5 and the spring bias of the spring 17 of the rotary pressure compensator 15 are in the drive system according to the invention according to the FIG. 1 tuned so that when un-actuated consumers, the sum of the pressure difference at the priority valve 5 and the pressure difference at the circulation pressure compensator 15 plus the line resistance and flow resistance of other components at least the minimum brake pressure, which is defined by the spring of the pressure reducing valve 26, whereby the brake pressure to Operation of the braking device 20 from the system pressure generated by the pump 1 in the delivery line 4 upstream of the priority valve 5 in all operating conditions without additional energy losses from the already occurring and existing pressure losses on the priority valve 5 and the rotary pressure compensator 15 can be provided.
  • an internal combustion engine-powered truck in which the pump 1 is driven by a trained as an internal combustion engine work machine 28 during operation of the truck, can by this design of the springs of the circulation pressure compensator 15 and the priority valve 5 of the steering 3 in all operating conditions of the minimum required Brake pressure in the control pressure line 25 from the system pressure of the pump 1 upstream of the priority valve 5 are generated.
  • an electrically operated industrial truck in which the pump 1 is driven by a drive machine designed as an electric motor 28, the pump 1 is operated only upon request of the steering 3 and / or the working hydraulics 3.
  • the check valve 30 in conjunction with the pressure accumulator 29, the brake pressure can be maintained when the pump 1 is switched off. If the brake pressure degrades through leaks, the accumulator 29 can be charged by a brief operation of the pump 1 to maintain the brake pressure again.
  • a drive system according to the invention according to the FIG. 2 is set in non-actuated consumers of the working hydraulics 2, non-actuated fan drive 45 and non-actuated steering system pressure 3 in the delivery line 4 from the sum of, for example, by a spring on the Fordervolumenstell issued 40 formed by a demand control valve standby pressure of the pump 1 and the Pressure difference at the priority valve 5 and plus the line resistance and flow resistance of other components together.
  • a constant brake pressure of the braking device 20 in an open-center system according to the FIG. 1 or as a closed-center system according to the FIG. 2 trained hydrostatic drive system from the system pressure generated by the pump 1 upstream of the priority valve 5 of the steering 3 can be achieved.
  • the invention can in this case be used in internal combustion engine operated machines in which the pump 1 is driven by an internal combustion engine, or electrically, in particular battery-electric, powered machines in which the pump 1 is driven by an electric motor, are used.
  • the brake pressure in the control pressure line 25 can be maintained in a simple manner with the pressure accumulator 29 in conjunction with the check valve 30 with the pump 1 switched off.

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  • Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Mechanical Engineering (AREA)
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  • General Engineering & Computer Science (AREA)
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  • Valves And Accessory Devices For Braking Systems (AREA)
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Description

Die Erfindung betrifft ein hydrostatisches Antriebssystem einer mobilen Arbeitsmaschine, insbesondere eines Flurförderzeugs, mit einer Pumpe, die zur Versorgung mindestens eines Verbrauchers einer Arbeitshydraulik und einer hydraulischen Lenkung vorgesehen ist, sowie mit einer hydraulischen mittels eines Bremsdruckes steuerbaren Bremseinrichtung, die als Federspeicherbremse ausgebildet ist und mittels des Bremsdruckes in eine Lösestellung beaufschlagt ist, wobei in einer Förderleitung der Pumpe ein Prioritätsventil zur bevorzugten Versorgung der Lenkung angeordnet ist und wobei zur Erzeugung des Bremsdruckes eine mit der Förderleitung der Pumpe stromauf des Prioritätsventils der Lenkung in Verbindung stehende Steuerdruckleitung vorgesehen ist.The invention relates to a hydrostatic drive system of a mobile work machine, in particular a truck, with a pump which is provided to supply at least one consumer of a working hydraulics and a hydraulic steering, as well as with a hydraulic means of a brake pressure controllable braking device, which is designed as a spring brake and means the brake pressure is applied in a release position, wherein in a delivery line of the pump, a priority valve for the preferred supply of the steering is arranged and wherein for generating the brake pressure with the delivery line of the pump upstream of the priority valve of the steering in communication associated control pressure line is provided.

Bei mobilen Arbeitsmaschinen, beispielsweise Flurförderzeugen, ist sicherzustellen, dass zu jedem Zeitpunkt während des Betriebs der Arbeitsmaschine ein minimaler Bremsdruck aufrechterhalten wird, um die Funktionsfähigkeit der Bremseinrichtung während des Betriebs der Arbeitsmaschine sicherzustellen.In mobile work machines, such as industrial trucks, it must be ensured that a minimum brake pressure is maintained at all times during operation of the work machine in order to ensure the functioning of the braking device during operation of the work machine.

Aus der DE 103 15 494 A1 ist ein hydrostatisches Antriebssystem für ein batterie-elektrisch betriebenes Flurförderzeug bekannt, bei dem eine erste Pumpe zur Versorgung der Arbeitshydraulik vorgesehen ist und eine zweite Pumpe zur Versorgung einer hydraulischen Lenkung und zur Erzeugung eines Bremsdruckes einer hydraulischen Bremseinrichtung dient. Ein den Bremsdruck erzeugendes Bremsventil ist hierbei an die Förderleitung der Pumpe stromab eines Prioritätsventils für die Lenkung angeschlossen. Ein derartiges Antriebssystem mit zwei hydraulischen Pumpen führt jedoch zu einem hohen Bauaufwand und einem hohen Herstellungsaufwand.From the DE 103 15 494 A1 is a hydrostatic drive system for a battery-electrically powered truck, in which a first pump for supplying the working hydraulics is provided and a second pump for supplying a hydraulic steering and for generating a brake pressure of a hydraulic braking device is used. A brake pressure generating brake valve is in this case connected to the delivery line of the pump downstream of a priority valve for the steering. However, such a drive system with two hydraulic pumps leads to a high construction cost and a high production cost.

Aus der DE 103 15 496 A1 ist bekannt, eine Pumpe eines hydrostatischen Antriebssystems eines batterie-elektrisch betriebenen Flurförderzeugs zur Versorgung einer Arbeitshydraulik, einer hydraulischen Lenkung sowie zur Ansteuerung einer hydraulischen Bremseinrichtung zu verwenden. Stromab eines Prioritätsventils für die Lenkung ist eine zu der Bremseinrichtung geführte Bremsleitung an die zur der Arbeitshydraulik geführte Förderleitung der Pumpe angeschlossen, in der ein Bremsventil zur Erzeugung eines Bremsdruckes angeordnet ist. Um bei nicht betätigter Lenkung und nicht angesteuerter Arbeitshydraulik einen Bremsdruck zur Beaufschlagung der Bremseinrichtung zu erzeugen, ist in einer von der zur Arbeitshydraulik geführten Förderleitung abzweigenden Behälterumlaufleitung ein Vorspannventil angeordnet, dessen Federvorspannung dem erforderlichen Bremsdruck entspricht, so dass durch ein Androsseln des über das Vorspannventil zum Behälter abströmenden Druckmittels der Bremsdruck erzeugt wird. Bei einem derartigen Antriebssystem ergeben sich jedoch hohe Energieverluste, da die Federvorspannung des Prioritätsventils und die Vorspannung des Vorspannventils als Verluste bei der Erzeugung des Bremsdruckes eingehen.From the DE 103 15 496 A1 It is known to use a pump of a hydrostatic drive system of a battery-electrically operated truck to supply a working hydraulics, a hydraulic steering and to control a hydraulic braking device. Downstream of a priority valve for the Steering is a guided to the brake device brake line connected to the guided to the working hydraulics delivery line of the pump, in which a brake valve is arranged to generate a brake pressure. In order to produce a brake pressure for acting on the braking device with non-actuated steering and non-actuated working hydraulics, a biasing valve is arranged in a guided from the working hydraulic conveyor line container circulation line whose spring preload corresponds to the required brake pressure, so that by throttling over the biasing valve for Container outflowing pressure medium of the brake pressure is generated. In such a drive system, however, result in high energy losses, since the spring bias of the priority valve and the bias of the biasing valve are received as losses in the generation of the brake pressure.

Die DE 20 2004 010 530 U1 offenbart ein hydrostatisches Antriebssystem eines Fahrzeugs, bei dem einer hydraulischen Lenkung ein zusätzliches Prioritätsventil mit einer Druckminderfunktion zugeordnet ist, mit dem das Druckniveau der hydraulischen Lenkung begrenzt werden kann, um den Bauaufwand für die Lenkung zu verringern.The DE 20 2004 010 530 U1 discloses a hydrostatic drive system of a vehicle in which a hydraulic steering is associated with an additional priority valve with a pressure reducing function with which the pressure level of the hydraulic steering can be limited to reduce the construction cost of the steering.

Aus der gattungsgemäßen DE 101 51 831 A1 ist ein Antriebssystem eines Flurförderzeugs bekannt, bei der die Bremslöseleitung der Federspeicherbremse stromauf eines Prioritätsventils an die Förderleitung der Pumpe angeschlossen ist. Bei nicht betätigten Verbrauchern ist der aus der Vorspannung der Feder am Prioritätsventil und der Feder an einer Umlaufdruckwaage erzeugte Druck in der Förderleitung der Pumpe nicht ausreichend, um die Federspeicherbremse in die Lösestellung zu betätigen. Um die Federspeicherbremse in die Lösestellung zu beaufschlagen, ist die Umlaufdruckwaage in die Sperrstellung zu betätigen, um einen entsprechenden Druckaufbau stromauf des Prioritätsventils zu erzielen. Gemäß der Figur 2 wird zum Lösen der Federspeicherbremse mit einem zusätzlich erforderlichen Zusatzventil an beiden Seiten der Umlaufdruckwaage der Förderdruck angelegt, so dass die Umlaufdruckwaage durch die Feder schließt und ein Druckaufbau in der Förderleitung erfolgt, um den erforderlichen Bremslösedruck zu erzeugen. Gemäß der Figur 3 wird in einer Verbraucherleitung eines Verbrauchers beispielsweise des Neigeantriebs, ein zusätzliches Sperrventil angeordnet, so dass durch eine Betätigung des Wegeventils gegen die abgesperrte Verbraucherleitung ein Lastdruck erzeugt wird,From the generic DE 101 51 831 A1 a drive system of a truck is known in which the brake release line of the spring brake is connected upstream of a priority valve to the delivery line of the pump. For non-actuated consumers, the pressure generated in the delivery line of the pump from the bias of the spring on the priority valve and the spring on a circulation pressure compensator is insufficient to actuate the spring brake in the release position. To apply the spring brake in the release position, the circulation pressure compensator is to be operated in the blocking position to achieve a corresponding pressure build-up upstream of the priority valve. According to the FIG. 2 is applied to release the spring brake with an additional additional valve required on both sides of the circulation pressure of the delivery pressure, so that the circulation pressure compensator closes by the spring and a pressure build-up in the delivery line to produce the required brake release pressure. According to FIG. 3, an additional shut-off valve is arranged in a consumer line of a consumer, for example the tilt drive, so that a load pressure is generated by actuating the directional control valve against the shut-off consumer line.

der die Umlaufdruckwaage in die Sperrstellung beaufschlagt, um den erforderlichen Förderdruck und somit der erforderliche Bremslösedruck erzeugen zu können.of the circulation pressure compensator biased in the blocking position to produce the required delivery pressure and thus the required brake release pressure can.

Der vorliegenden Erfindung liegt die Aufgabe zugrunde, ein gattungsgemäße Antriebssystem zur Verfügung zu stellen, bei dem mit geringem Bauaufwand und geringen Energieverlusten der Bremsdruck zur Beaufschlagung der hydraulischen Bremseinrichtung erzeugbar ist.The present invention has for its object to provide a generic drive system available, in which the brake pressure for applying the hydraulic braking device can be generated with low construction costs and low energy losses.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, dass bei unbetätigtem Verbraucher der Arbeltshydraullk und unbetätigter Lenkung der Bremsdruck zur Betätigung der Bremseinrichtung in die Lösestellung in jedem Betriebspunkt ohne zusätzliche Energieverluste aus dem von der Pumpe in der Förderleitung stromauf des Prioritätsventils erzeugten Systemdruck bereitgestellt wird. Der erfindungsgemäße Gedanke besteht somit darin, den Bremsdruck stromauf des Prioritätsventils der Lenkung direkt aus der Förderleitung der Pumpe abzugreifen und somit aus dem stromauf des Prioritätsventils anstehenden Systemdruck der Pumpe zu erzeugen, so dass die Vorspannung des Priortätsventils und der ohnehin auftretende Druckabfall an dem Prioritätsventil zur Erzeugung des Bremsdruckes ausgenutzt werden kann. Hierdurch ist eine Erzeugung des Bremsdruckes ohne zusätzliche Energieverluste mit lediglich einer Pumpe erzielbar, wodurch das erfindungsgemäße Antriebssystem weiterhin einen geringen Bauaufwand aufweiset.This object is achieved according to the invention in that, when the load of the braking device is not actuated, the braking force for actuating the braking device is provided in the release position at each operating point without additional energy losses from the system pressure generated by the pump in the delivery line upstream of the priority valve. The idea according to the invention thus consists of tapping the brake pressure upstream of the priority valve of the steering directly from the delivery line of the pump and thus producing the system pressure of the pump upstream of the priority valve so that the bias of the priority valve and the pressure drop occurring at the priority valve for Generation of the brake pressure can be exploited. As a result, a generation of the brake pressure without additional energy losses with only one pump can be achieved, whereby the drive system according to the invention further has a low construction cost.

Die Bremseinrichtung ist als Federspeichürbremse ausgebildet, die mittels des Bremsdruckes in eine Lösestellung beaufschlagbar ist. Mit einem entsprechenden Bremsventil, beispielsweise einem steuerbaren Druckminderventil, kann hierbei der Bremsdruck gesteuert reduziert werden, so dass die Federspeicherbremse als Betriebsbremse verwendbar ist.The braking device is designed as Federspeichürbremse, which can be acted upon by the brake pressure in a release position. With a corresponding brake valve, such as a controllable pressure reducing valve, in this case the brake pressure can be reduced controlled, so that the spring brake is used as a service brake.

Das Prioritätsventil ist zweckmäßigerweise mittels einer Feder in Richtung einer die Förderleitung der Pumpe mit der Lenkung verbindenden Stellung beaufschlagt. Der stromauf des Prioritätsventils anstehende Systemdruck wird von der Federvorspannung der Feder des Prioritätsventils mitbestimmt, wodurch aus dem Systemdruck auf einfache Weise der erforderliche Bremsdruck zur sicheren Betätigung der Bremseinrichtung bereit gestellt werden kann.The priority valve is expediently acted upon by means of a spring in the direction of a conveying line connecting the pump to the steering position. The upstream of the priority valve system pressure is determined by the spring bias of the spring of the priority valve, which can be made available from the system pressure in a simple way, the required brake pressure for safe operation of the braking device.

Gemäß einer vorteilhaften Ausgestaltungsform der Erfindung ist die Steuerdruckleitung zu einem Bremsventil der Bremseinrichtung geführt, wobei in der Steuerdruckleitung ein Druckminderventil angeordnet ist. Mit einem derartigen Druckminderventil in der Steuerdruckleitung kann bei sich veränderndem Förderdruck der Pumpe und somit bei sich veränderndem Systemdruck stromauf des Prioritätsventils auf einfache Weise ein konstantes Bremsdruckniveau an dem Bremsventil erzielt werden.According to an advantageous embodiment of the invention, the control pressure line is guided to a brake valve of the braking device, wherein in the control pressure line, a pressure reducing valve is arranged. With such a pressure reducing valve in the control pressure line, a constant brake pressure level at the brake valve can be achieved in a simple manner with changing delivery pressure of the pump and thus with changing system pressure upstream of the priority valve.

Das erfindungsgemäße Antriebssystem kann als sogenanntes Open-Center-System ausgebildet sein, bei dem die Pumpe als Konstantpumpe ausgebildet ist und eine Steuerventileinrichtung zur Steuerung der Arbeitshydraulik eine Umlaufdruckwaage aufweist, die von dem höchsten Lastdruck der Verbraucher der Arbeitshydraulik und einer Feder in Richtung einer Sperrstellung und dem Förderdruck der Pumpe in Richtung einer Durchflussstellung beaufschlagt ist. Bei einem derartigen Antriebssystem wird der Systemdruck stromauf des Prioritätsventils bei nicht betätigten Verbrauchern ebenfalls von der Federvorspannung der Feder der Umlaufdruckwaage bestimmt, wodurch mit der an die Förderleitung der Pumpe stromauf des Prioritätsventils angeschlossenen Steuerdruckleitung und dem in dieser angeordneten Druckminderventil auf einfache Weise der erforderliche Bremsdruck der Bremseinrichtung ohne zusätzliche Energieverluste aus dem Systemdruck stromauf des Prioritätsventils erzeugt werden kann.The drive system according to the invention can be designed as a so-called open-center system in which the pump is designed as a constant pump and a control valve device for controlling the working hydraulics has a circulation pressure compensator, the highest load pressure of the load of the working hydraulics and a spring in the direction of a blocking position and the delivery pressure of the pump is applied in the direction of a flow position. In such a drive system, the system pressure upstream of the priority valve at non-actuated consumers is also determined by the spring bias of the spring of the rotary pressure balance, which with the connected to the delivery line of the pump upstream of the priority valve control pressure line and disposed in this pressure reducing valve in a simple manner, the required brake pressure Braking device can be generated without additional energy losses from the system pressure upstream of the priority valve.

Um den zur sicheren Betätigung der Bremseinrichtung erforderlichen minimalen Bremsdruck in allen Betriebszuständen aus dem von der Pumpe gelieferten Systemdruck stromauf des Prioritätsventils der Lenkung zu erzeugen und angreifen zu können, sind gemäß einer vorteilhaften Weiterbildung der Erfindung die Federvorspannung des Prioritätsventils der Lenkung und/oder die Federvorspannung der Umlaufdruckwaage derart eingestellt, dass in jedem Betriebspunkt ein minimaler Bremsdruck in der Steuerdruckleitung erzeugbar ist. Hierdurch wird auf einfache Weise erzielt und sichergestellt, dass sich in jedem Betriebspunkt aus dem Systemdruck stromauf des Prioritätsventils der minimal erforderliche Bremsdruck für die sichere Betätigung der Bremseinrichtung zwischen der Pumpe und dem Prioritätsventil der Lenkung einstellt.In order to generate and attack the required for safe operation of the braking device minimum brake pressure in all operating conditions from the system pressure supplied by the pump upstream of the priority valve of the steering, according to an advantageous embodiment of the invention, the spring bias of the priority valve of the steering and / or spring preload the circulation pressure compensator adjusted such that a minimum brake pressure in the control pressure line can be generated at each operating point. This achieves and ensures in a simple manner that adjusts the minimum required brake pressure for the safe operation of the braking device between the pump and the priority valve of the steering at each operating point from the system pressure upstream of the priority valve.

Das erfindungsgemäße Antriebssystem kann ebenfalls als sogenanntes Closed-Center-System ausgebildet sein, bei dem die Pumpe als Load-Sensing-geregelte Verstellpumpe ausgebildet ist, die von dem höchsten Lastdruck der Arbeitshydraulik und/oder der Lenkung gesteuert ist. Eine derartige Verstellpumpe liefert bei nicht angesteuerten Verbrauchern der Arbeitshydraulik und/oder nicht betätigter Lenkung einen Standby-Druck als Regelgröße der Verstellpumpe, der als Systemdruck in der Förderleitung stromauf des Prioritätsventils der Lenkung ansteht und aus dem mittels der an die Förderleitung der Pumpe stromauf des Prioritätsventils angeschlossenen Steuerdruckleitung auf einfache Weise der minimal erforderliche Bremsdruck zur sicheren Betätigung der Bremseinrichtung ohne zusätzliche Energieverluste erzeugt werden kann.The drive system according to the invention can also be designed as a so-called closed-center system, in which the pump is controlled as load-sensing Variable displacement pump is formed, which is controlled by the highest load pressure of the working hydraulics and / or the steering. Such a variable delivers when not driven consumers of the working hydraulics and / or non-actuated steering a standby pressure as a controlled variable of the variable, which is present as system pressure in the delivery line upstream of the priority valve of the steering and from the means of the delivery line to the pump upstream of the priority valve connected control pressure line in a simple manner, the minimum required brake pressure for safe operation of the braking device can be generated without additional energy losses.

Gemäß einer zweckmäßigen Weiterbildung der Erfindung kann die an eine Fördervolumenstelleinrichtung der Pumpe geführte Lastdruckmeldeleitung mit der Steuerdruckleitung in Verbindung stehen. Die Verstellpumpe ist somit ebenfalls von dem in der Steuerdruckleitung anstehenden Bremsdruck gesteuert, so dass auf einfache Weise erzielt wird, dass in allen Betriebszuständen der minimale Bremsdruck aus dem von der Verstellpumpe gelieferten Systemdruck stromauf des Prioritätsventils der Lenkung erzeugt werden kann. Bei einem Flurförderzeug kann somit auf einfache Weise vermieden werden, dass in bestimmten Betriebspunkten, beispielsweise einem Anheben eines Hubantriebs ohne Last der Systemdruck der Pumpe unter den minimalen Bremsdruck einbricht.According to an expedient development of the invention, the load pressure signaling line routed to a delivery volume adjusting device of the pump can be in communication with the control pressure line. The variable displacement pump is thus also controlled by the pending in the control pressure line brake pressure, so that is achieved in a simple manner that in all operating conditions, the minimum brake pressure from the system pressure supplied by the variable system pressure upstream of the priority valve of the steering can be generated. In the case of an industrial truck, it can thus be easily avoided that the system pressure of the pump drops below the minimum brake pressure in certain operating points, for example a lifting of a lifting drive without load.

Zweckmäßigerweise geht hierzu eine zu einer Fördervolumenstelleinrichtung der Pumpe führenden Lastdruckmeldekette von der den Bremsdruck führenden Steuerdruckleitung aus, wobei von der Steuerdruckleitung stromab des Druckminderventils eine Zweigleitung zu einem Eingang eines Auswahlventils geführt ist, an dessen weiteren Eingang eine den höchsten Lastdruck der Arbeitshydraulik und/oder der Lenkungseinrichtung führende Zweigleitung angeschlossen ist, wobei das Auswahlventil ausgangsseitig mit der zu der Fördervolumenstelleinrichtung der Pumpe geführten Lastdruckmeldeleitung in Verbindung steht. Somit wird erzielt, dass auch der Bremsdruck in der Lastdruckmeldeleitung ansteht, um in allen Betriebszuständen eine sichere Erzeugung des minimal erforderlichen Bremsdruckes aus dem Systemdruck der Pumpe sicherzustellen.Appropriately, this goes to a leading to a delivery volume adjustment of the pump load pressure signaling chain from the brake pressure leading control pressure line, which is guided by the control pressure line downstream of the pressure reducing valve, a branch line to an input of a selector valve, at the other input one of the highest load pressure of the working hydraulics and / or Steering device leading branch line is connected, the selector valve on the output side is connected to the guided to the delivery volume control device of the pump load pressure signaling line. Thus, it is achieved that the brake pressure in the load pressure signaling line is present in order to ensure a safe generation of the minimum required brake pressure from the system pressure of the pump in all operating conditions.

Sofern gemäß einer vorteilhaften Ausführungsform der Erfindung bei einem derartigen Antriebssystem der Standby-Druck und somit die Regelgröße der Pumpe und/oder die Federvorspannung des Prioritätsventils derart eingestellt sind, dass in jedem Betriebspunkt ein minimal erforderlicher Bremsdruck in der Steuerdruckleitung erzeugbar ist, kann der erforderliche minimale Bremsdruck zur sicheren Betätigung der Bremseinrichtung auf einfache Weise in allen Betriebszuständen aus dem von der Pumpe erzeugten Systemdruck stromauf des Prioritätsventils erzeugt werden.If according to an advantageous embodiment of the invention in such a drive system, the standby pressure and thus the controlled variable of the pump and / or the Spring bias of the priority valve are set such that at each operating point a minimum required brake pressure in the control pressure line can be generated, the required minimum brake pressure for safe operation of the braking device in a simple manner in all operating conditions from the system pressure generated by the pump upstream of the priority valve can be generated.

Die Pumpe kann von einer verbrennungsmotorischen Antriebsmaschine, beispielsweise einem Verbrennungsmotor, angetrieben werden, bei der die Pumpe ständig in Betrieb ist und einen Förderstrom zur Erzeugung des Bremsdruckes liefert. Alternativ kann die Pumpe von einem elektrischen Antriebsmotor angetrieben werden, wobei die Pumpe lediglich bei einem Bedarf der Lenkung und/oder der Arbeitshydraulik betätigt wird und einen Volumenstrom liefert. Um bei einem derartigen Antriebssystem mit einer von einem Elektromotor angetriebene Pumpe auch bei nicht betätigter Pumpe den erforderlichen Bremsdruck zu erzeugen und aufrechtzuerhalten, ist gemäß einer bevorzugten Weiterbildung der Erfindung vorgesehen, dass der Steuerdruckleitung ein Druckmittelspeicher zugeordnet ist. Über den Druckmittelspeicher kann somit bei abgeschalteter Pumpe der Bremsdruck in der Steuerdruckleitung auf einfache Weise aufrechterhalten werden.The pump can be driven by an internal combustion engine drive machine, such as an internal combustion engine, in which the pump is constantly in operation and provides a flow for generating the brake pressure. Alternatively, the pump may be driven by an electric drive motor, the pump being actuated only when steering and / or working hydraulics are needed to provide a volumetric flow. In order to produce and maintain the required brake pressure in such a drive system with a pump driven by an electric motor even when the pump is not actuated, it is provided according to a preferred embodiment of the invention that the control pressure line is associated with a pressure fluid reservoir. Thus, when the pump is switched off, the brake pressure in the control pressure line can be maintained in a simple manner via the accumulator.

Um hierbei einen Abbau des in der Steuerdruckleitung anstehenden Druckes bei abgeschalteter Pumpe zu vermeiden, ist zweckmäßigerweise in der Steuerdruckleitung stromauf der Speichereinrichtung und stromauf des Druckminderventils ein in Richtung zu dem Druckminderventil öffnendes Sperrventil, insbesondere Rückschlagventil, angeordnet.In order to avoid a reduction in the pressure present in the control pressure line when the pump is switched off, a check valve opening in the direction of the pressure reducing valve, in particular a non-return valve, is expediently arranged in the control pressure line upstream of the storage device and upstream of the pressure reducing valve.

Bei einem erfindungsgemäßen Antriebssystem kann zur Steuerung der Verbraucher der Arbeitshydraulik jeweils ein elektro-hydraulisch betätigbares Steuerventil, insbesondere ein Wegeventil, vorgesehen sein, wobei eine Steuerdruckversorgungsleitung des Steuerventils mit der Steuerdruckleitung in Verbindung steht. Bei elektro-hydraulisch betätigten und vorgesteuerten Steuerventilen ist zur Erzielung hoher Betätigungskräfte für das Steuerventil eine Steuerdruckversorgung mit einem konstanten Steuerdruckniveau erforderlich, aus dem mittels entsprechender Vorsteuerventile ein Steuerdruck zur Betätigung der Steuerventile erzeugt wird. Da ein derartiges Steuerdruckniveau für die Vorsteuerung der Steuerventile der Arbeitshydraulik in der Regel auf dem Niveau des Bremsdruckes der Bremseinrichtung liegt, kann durch einen Anschluss der Steuerdruckversorgungsleitung für die Vorsteuerventile der Steuerventile an die den Bremsdruck führende Steuerdruckleitung weiterhin auf einfache Weise eine Steuerdruckversorgung für die vorgesteuerten Steuerventile der Arbeitshydraulik ohne zusätzlichen Bauaufwand erzielt werden.In a drive system according to the invention may be provided for controlling the load of the working hydraulics in each case an electro-hydraulically actuated control valve, in particular a directional control valve, wherein a control pressure supply line of the control valve is in communication with the control pressure line. In electro-hydraulically actuated and pilot operated control valves to achieve high actuation forces for the control valve, a control pressure supply with a constant control pressure level is required, from which by means of appropriate pilot valves, a control pressure is generated for actuating the control valves. Because such a control pressure level for the pilot control the control valves of the working hydraulics is usually at the level of the brake pressure of the brake device can be achieved by connecting the control pressure supply line for the pilot valves of the control valves to the brake pressure leading control pressure line in a simple way a control pressure supply for the pilot-operated control valves of the working hydraulics without additional construction costs ,

Die Steuerdruckversorgungsleitung steht hierbei zweckmäßigerweise mit der Steuerdruckleitung stromab des Druckminderventils in Verbindung. Der in der Steuerdruckleitung zwischen dem Druckminderventil und dem Bremsventil anstehende Bremsdruck mit einem konstanten Niveau kann hierdurch auf einfache Weise als Steuerdruckversorgung mit einem konstanten Niveau für die vorgesteuerten Steuerventile der Arbeitshydraulik verwendet werden.The control pressure supply line is expediently in communication with the control pressure line downstream of the pressure reducing valve. The pending in the control pressure line between the pressure reducing valve and the brake valve brake pressure at a constant level can thereby be used in a simple manner as a control pressure supply with a constant level for the pilot-operated control valves of the working hydraulics.

Weitere Vorteile und Einzelheiten der Erfindung werden anhand der in den schematischen Figuren dargestellten Ausführungsbeispiele näher erläutert. Hierbei zeigen

Figur 1
eine erste Ausführungsform eines erfindungsgemäßen Antriebssystems und
Figur 2
eine zweite Ausführungsform eines erfindungsgemäßen Antriebssystems.
Further advantages and details of the invention will be explained in more detail with reference to the embodiments illustrated in the schematic figures. Show here
FIG. 1
a first embodiment of a drive system according to the invention and
FIG. 2
A second embodiment of a drive system according to the invention.

In der Figur 1 ist ein erfindungsgemäßes, als Open-Center-System ausgebildetes Antriebssystem einer beispielsweise als Flurförderzeug ausgebildeten Arbeitsmaschine in einem schematischen Schaltplan dargestellt.In the FIG. 1 is an inventive, designed as an open-center system drive system of a designed example, designed as a truck work machine in a schematic circuit diagram.

Das Antriebssystem umfasst eine als Konstantpumpe ausgebildete Pumpe 1, die im offenen Kreislauf betrieben ist und zur Versorgung einer Arbeitshydraulik 2 und einer hydraulischen Lenkung 3 vorgesehen ist. Die Pumpe 1 saugt aus einem Behälter und fördert in eine Förderleitung 4, in der zur bevorzugten Versorgung der Lenkung 3 ein Prioritätsventil 5 angeordnet ist. Von dem Prioritätsventil 5 führt eine Förderzweigleitung 6 zu der Lenkung 3 und eine Förderzweigleitung 7 zu einer als Steuerventilblock ausgebildeten Steuerventileinrichtung 8 der Arbeitshydraulik 2.The drive system comprises a fixed-displacement pump 1, which is operated in the open circuit and is provided to supply a working hydraulics 2 and a hydraulic steering 3. The pump 1 sucks from a container and promotes in a delivery line 4, in the preferred supply of the steering 3, a priority valve 5 is arranged. From the priority valve 5, a delivery branch line 6 leads to the steering 3 and a delivery branch line 7 to a control valve 8 formed as a control valve block of the working hydraulics. 2

Das Prioritätsventil 5 ist mittels einer Feder 9 und dem in einer Lastdruckmeldezweigleitung 10 der Lenkung 3 anstehenden Lastdruck der Lenkung. 3 in Richtung einer die Förderleitung 4 mit der Förderzweigleitung 6 zur bevorzugten Versorgung der Lenkung 3 verbindenden Stellung 5a beaufschlagbar. Mittels des in der Förderzweigleitung 6 anstehenden Förderdruckes ist das Prioritätsventil 5 in Richtung einer Stellung 5b beaufschlagbar, in der die Förderleitung 4 mit beiden Förderzweigleitungen 6 und 7 zur gleichzeitigen Versorgung der Lenkung 3 und der Arbeitshydraulik 2 verbunden ist.The priority valve 5 is by means of a spring 9 and the load in a load pressure branch line 10 of the steering 3 load pressure of the steering. 3 in the direction of the delivery line 4 with the delivery branch line 6 for the preferred supply of the steering 3 connecting position 5a acted upon. By means of the pending delivery pressure in the delivery branch line 6, the priority valve 5 can be acted upon in the direction of a position 5b, in which the delivery line 4 is connected to both delivery branch lines 6 and 7 for the simultaneous supply of the steering 3 and the working hydraulics 2.

Die Steuerventileinrichtung 8 der Arbeitshydraulik 2 umfasst zur Steuerung jedes Verbrauchers der Arbeitshydraulik 2 ein als Wegeventil ausgebildetes Steuerventil 11. In der Figur 1 sind schematisch dargestellte Steuerventile 11 zur Betätigung eines Hubantriebs 12, eines nicht mehr dargestellten Neigeantriebs und gegebenenfalls eines nicht mehr dargestellten Zusatzantriebs, beispielsweise eines Seitenschiebers, der Arbeitshydraulik 2 vorgesehen.The control valve device 8 of the working hydraulics 2 comprises a control valve 11 designed as a directional control valve for controlling each consumer of the working hydraulics 2 FIG. 1 are schematically illustrated control valves 11 for actuating a lifting drive 12, a tilt drive, not shown, and possibly an auxiliary drive, not shown, for example, a side slide, the working hydraulics 2 are provided.

In der Steuerventileinrichtung 8 der Arbeitshydraulik 2 ist gemäß der Figur 1 eine Umlaufdruckwaage 15 angeordnet, die in einer von der Förderzweigleitung 7 zum Behälter geführten Zweigleitung angeordnet ist. Die Umlaufdruckwaage 15 ist von dem in einer Lastdruckmeldezweigleitung 16 anstehenden, höchsten Lastdruck der Verbraucher der Arbeitshydraulik 2 und einer Feder 17 in Richtung einer Sperrstellung und von dem in der Förderzweigleitung 7 anstehenden Förderdruck in Richtung einer Durchflussstellung beaufschlagt.In the control valve device 8 of the working hydraulics 2 is in accordance with the FIG. 1 a circulation pressure compensator 15 is arranged, which is arranged in a guided from the delivery branch line 7 to the container branch line. The circulation pressure compensator 15 is acted upon by the highest load pressure of the consumers of the working hydraulics 2 and of a spring 17 in the direction of a blocking position and of the delivery pressure present in the delivery branch line 7 in the direction of a flow-through position in a load pressure signaling branch line 16.

Das erfindungsgemäße Antriebssystem umfasst weiterhin eine hydraulisch betätigbare Bremseinrichtung 20, beispielsweise eine Federspeicherbremseinrichtung, die mittels eines Bremsventils 21, beispielsweise eines elektrisch ansteuerbaren Proportional-Druckminderventils, steuerbar ist.The drive system according to the invention further comprises a hydraulically actuated braking device 20, for example a spring brake device, which is controllable by means of a brake valve 21, for example, an electrically controllable proportional pressure reducing valve.

Das Bremsventil 21 steht eingansseitig mit einer einen konstanten Bremsdruck führenden Steuerdruckleitung 25 in Verbindung, die erfindungsgemäß an die Förderleitung 4 der Pumpe 1 stromauf des Prioritätsventils 5 der Lenkung 3 angeschlossen ist. In der Steuerdruckleitung 25 ist hierbei zur Konstanthaltung des an dem Bremsventil 21 anstehenden Bremsdruckes ein Druckminderventil 26 angeordnet.The brake valve 21 is the input side with a constant brake pressure leading control pressure line 25 in connection, which is according to the invention connected to the delivery line 4 of the pump 1 upstream of the priority valve 5 of the steering 3. In the control pressure line 25 in this case a pressure reducing valve 26 is arranged to keep the constant at the brake valve 21 pending brake pressure.

Die Steuerventile 11 zur Steuerung der Verbraucher der Arbeitshydraulik 2 sind jeweils elektro-hydraulisch betätigbar. Hierzu sind nicht näher dargestellte elektrisch angesteuerte Vorsteuerventile, beispielsweise mittels eines Proportionalmagneten betätigte Druckminderventile, vorgesehen, mittels denen die Steuerventile 11 betätigende Steuerdrücke erzeugbar sind. Die Vorsteuerventile stehen zur Erzeugung eines entsprechenden das Steuerventil 11 betätigenden Steuerdrucks eingangsseitig mit einer Steuerdruckversorgungsleitung 27 in Verbindung, die an die Steuerdruckleitung 25 wischen dem Druckminderventil 26 und dem Bremsventil 21 angeschlossen ist.The control valves 11 for controlling the load of the working hydraulics 2 are each electro-hydraulically actuated. For this purpose, not shown in detail electrically controlled pilot valves, for example by means of a proportional solenoid operated pressure reducing valves, provided by means of which the control valves 11 actuated control pressures can be generated. The pilot valves are to generate a corresponding control valve 11 actuated control pressure on the input side with a control pressure supply line 27 in connection with the control pressure line 25 between the pressure reducing valve 26 and the brake valve 21 is connected.

Die Pumpe 1 kann bei einem verbrennungsmotorisch betriebenen Flurförderzeug von einer als Verbrennungsmotor ausgebildeten Antriebsmaschine 28 angetrieben werden und ständig im Betrieb des Flurförderzeugs betrieben werden. Bei einem Flurförderzeug mit einem elektrischen Antriebssystem, beispielsweise einem batterie-elektrisch betriebenen Flurförderzug, ist die Antriebsmaschine 28 der Pumpe 1 von einem Elektromotor gebildet. Da die Pumpe 1 eines derartigen Flurförderzeugs mit einem elektrischen Antriebssystem lediglich bei einer Betätigung der Lenkung 3 und/oder der Arbeitshydraulik 2 angetrieben wird, ist der Steuerdruckleitung 25 stromauf des Druckminderventils 26 ein hydraulischer Druckmittelspeicher 29 zugeordnet. In der Steuerdruckleitung 25 ist hierbei stromauf des Anschlusses des Druckmittelspeichers 29 und stromauf des Druckminderventils 26 ein Sperrventil 30 angeordnet, beispielsweise ein Rückschlagventil, das in Richtung zu dem Druckminderventil 26 öffnet.The pump 1 can be driven in an internal combustion engine powered truck by a designed as an internal combustion engine drive machine 28 and operated continuously during operation of the truck. In an industrial truck with an electric drive system, for example, a battery-powered floor conveyor, the drive machine 28 of the pump 1 is formed by an electric motor. Since the pump 1 of such a truck is driven by an electric drive system only upon actuation of the steering 3 and / or the working hydraulics 2, the control pressure line 25 upstream of the pressure reducing valve 26 is associated with a hydraulic accumulator 29. In the control pressure line 25 in this case upstream of the connection of the accumulator 29 and upstream of the pressure reducing valve 26, a check valve 30 is arranged, for example, a check valve which opens in the direction of the pressure reducing valve 26.

In der Figur 2 ist ein erfindungsgemäßes, als Closed-Center-System ausgebildetes Antriebssystem einer beispielsweise als Flurförderzeug ausgebildeten Arbeitsmaschine in einem schematischen Schaltplan dargestellt. Gleiche Bauteile sind hierbei mit gleichen Bezugsziffern versehen.In the FIG. 2 is an inventive, designed as a closed-center system drive system of an example designed as a truck work machine shown in a schematic circuit diagram. The same components are provided here with the same reference numerals.

Die zur Versorgung der Arbeitshydraulik 2 und des von der hydraulischen Lenkung 3 gebildeten weiteren Verbrauchers vorgesehene Pumpe 1 ist als Load-Sensing-geregelte Verstellpumpe ausgebildet. Zur Regelung der Fördermenge der Pumpe 1 ist eine als Bedarfsstromregeleinrichtung ausgebildete Fordervolumenstelleinrichtung 40 vorgesehen, die von dem höchsten Lastdruck der Verbraucher des Antriebssystems gesteuert ist. Eine den höchsten Lastdruck der Verbraucher führende Lastdruckmeldeleitung 41 ist hierbei an die Fordervolumenstelleinrichtung 40 der Pumpe 1 geführt.The pump 1 provided for supplying the working hydraulics 2 and the further load formed by the hydraulic steering 3 is designed as a load-sensing-controlled variable displacement pump. To regulate the delivery rate of the pump 1, a demand volume control device 40 designed as a demand flow control device is provided, which is controlled by the highest load pressure of the consumers of the drive system. One of the highest load pressure of the consumer leading load pressure signaling line 41 is guided here to the Fordervolumenstelleinrichtung 40 of the pump 1.

Die Steuerventile 11 zur Steuerung der Verbraucher der Arbeitshydraulik 2 gemäß den Figur 2 sind jeweils elektro-hydraulisch betätigbar. Die nicht näher dargestellten elektrisch angesteuerte Vorsteuerventile, beispielsweise mittels eines Proportionalmagneten betätigte Druckminderventile, mittels denen die Steuerventile 11 betätigende Steuerdrücke erzeugbar sind, stehen eingangsseitig mit der Steuerdruckversorgungsleitung 27 in Verbindung, die von der Steuerdruckleitung 25 zwischen dem Druckminderventil 26 und dem Bremsventil 21 abzweigt.The control valves 11 for controlling the load of the working hydraulics 2 according to the FIG. 2 are each electro-hydraulically actuated. The non-illustrated electrically controlled pilot valves, for example by means of a proportional solenoid operated pressure reducing valves, by means of which the control valves 11 actuated control pressures can be generated on the input side to the control pressure supply line 27 in connection, which branches off from the control pressure line 25 between the pressure reducing valve 26 and the brake valve 21.

Die Pumpe 1 der Figur 2 kann neben der Versorgung der Lenkung 3 und der Arbeitshydraulik 2 weiterhin zur Betätigung eines weiteren Verbrauchers vorgesehen werden, beispielsweise eines Lüfterantriebs 45, wobei ein Lüftermotor 46 über ein Steuerventil 47 mit der zur Arbeitshydraulik 2 geführten Förderzeugleitung 7 in Verbindung steht.The pump 1 the FIG. 2 can be provided in addition to the supply of the steering 3 and the working hydraulics 2 continue to operate a further consumer, such as a fan drive 45, wherein a fan motor 46 is connected via a control valve 47 with the working hydraulics 2 guided delivery line 7 in combination.

Eine Lastdruckmeldekette 50 zur Erfassung des höchsten Lastdruckes der Verbraucher des Antriebssystems und Weiterleitung des höchsten Lastdruckes an die Fordervolumenstelleinrichtung 40 der Pumpe 1, geht von der den Bremsdruck führenden Steuerdruckleitung 25 aus.A load pressure detection chain 50 for detecting the highest load pressure of the load of the drive system and forwarding the highest load pressure to the Fordervolumenstelleinrichtung 40 of the pump 1, is based on the brake pressure leading control pressure line 25 from.

Hierzu ist eine von der Steuerdruckleitung 25 stromab des Druckminderventils 26 abzweigende und den Bremsdruck führende Zweigleitung 51 zu einem Eingang eines Auswahlventils 52, beispielsweise eines Wechselventils, geführt, an dessen weiteren Eingang eine den höchsten Lastdruck der Arbeitshydraulik 2 und/oder der Lenkungseinrichtung 3 sowie des Lüfterantriebs 45 führende Zweigleitung 53 angeschlossen ist, wobei das Auswahlventil 52 ausgangsseitig mit der zu der Fordervolumenstelleinrichtung 40 geführten Lastdruckmeldeleitung 41 in Verbindung steht. Die Zweigleitung 53 ist an den Ausgang eines weiteren als Wechselventil ausgebildeten Auswahlventils 54 angeschlossen, das eingangsseitig mit der Lastdruckmeldezweigleitung 10 der Lenkung 3 und einer Zweigleitung 55 in Verbindung steht. Die Zweigleitung 55 steht mit dem Ausgang eines weiteren als Wechselventils ausgebildeten Auswahlventils 56 in Verbindung, das eingangsseitig mit der den höchsten Lastdruck der Verbraucher der Arbeitshydraulik 2 führenden Lastdruckmeldezweigleitung 16 der Arbeitshydraulik 2 und einer Lastdruckmeldeleitung 57 des Lüfterantriebs 45 in Verbindung steht.For this purpose, one of the control pressure line 25 downstream of the pressure reducing valve 26 branching and the brake pressure leading branch line 51 to an input of a selector valve 52, such as a shuttle valve, led, at the other input one of the highest load pressure of the working hydraulics 2 and / or the steering device 3 and the Fan drive 45 leading branch line 53 is connected, wherein the selector valve 52 on the output side with the guided to the Fordervolumenstelleinrichtung 40 load pressure signaling line 41 in combination stands. The branch line 53 is connected to the output of another selection valve 54 designed as a shuttle valve, which is connected on the input side to the load pressure signaling branch line 10 of the steering system 3 and a branch line 55. The branch line 55 communicates with the output of another selector valve 56 designed as a shuttle valve, which is connected on the input side to the load pressure signaling branch line 16 of the working hydraulics 2 and to a load pressure signaling line 57 of the fan drive 45, which leads to the highest load pressure of the consumers of the working hydraulics 2.

Bei der Figur 2 ist ebenfalls erfindungsgemäß die an das Bremsventil 21 geführte Steuerdruckleitung 25 an die Förderleitung 4 der Pumpe 1 stromauf des Prioritätsventils 5 der Lenkung 3 angeschlossen, wobei in der Steuerdruckleitung 25 zur Erzeugung eines konstanten Steuerdruckniveaus das als Druckminderventil 26 ausgebildete, hydraulisch gesteuerte Druckreduzierventil angeordnet ist, dessen Einstellung das konstante Bremsdruckniveau am Eingang des Bremsventils 21 definiert. Zur Einstellung des Bremsdruckdruckniveaus ist das Druckminderventil 26 gemäß den Figuren 1, 2 mit einer Feder versehen. Die Steuerdruckversorgungsleitung 27 zur Steuerdruckversorgung der elektro-hydraulisch betätigbaren Steuerventile 11 der Arbeitshydraulik 12 ist analog zu der Figur 1 an die Steuerdruckleitung 25 zwischen dem Druckminderventil 26 und dem Bremsventil 21 angeschlossen.In the FIG. 2 is also according to the invention guided to the brake valve 21 control pressure line 25 connected to the delivery line 4 of the pump 1 upstream of the priority valve 5 of the steering 3, wherein in the control pressure line 25 to generate a constant control pressure levels designed as a pressure reducing valve 26, hydraulically controlled pressure reducing valve is arranged Setting the constant brake pressure level defined at the input of the brake valve 21. To adjust the brake pressure pressure level, the pressure reducing valve 26 is in accordance with FIGS. 1 . 2 provided with a spring. The control pressure supply line 27 to the control pressure supply of the electro-hydraulically actuated control valves 11 of the working hydraulics 12 is analogous to the FIG. 1 connected to the control pressure line 25 between the pressure reducing valve 26 and the brake valve 21.

Bei einem Antriebssystem gemäß der Figur 1 bzw. der Figur 2 stellt die Pumpe 1 den Volumenstrom zur Versorgung der Verbraucher der Arbeitshydraulik 2 und der Lenkung 3 sowie des gegebenenfalls vorhandenen Lüfterantriebs 45 zur Verfügung. Das Prioritätsventil 5 priorisiert die Lenkung 3 bei deren Betätigung vor der Arbeitshydraulik 2 und des gegebenenfalls vorhandenen Lüfterantriebs 45 bei gleichzeitiger Betätigung der Lenkung 3 und der Arbeitshydraulik 2 sowie des Lüfterantriebs 45. Die Federvorspannung der Feder 9 des Prioritätsventils 5 verändert die Performance des Prioritätsventils 5 und bestimmt den Durchflusswiderstand und somit den Druckabfall an dem Prioritätsventil 5 der Lenkung 3.In a drive system according to the FIG. 1 or the FIG. 2 the pump 1, the flow for supplying the load of the working hydraulics 2 and the steering 3 and the optional fan drive 45 available. The priority valve 5 prioritizes the steering 3 when actuated before the working hydraulics 2 and the optional fan drive 45 with simultaneous actuation of the steering 3 and the working hydraulics 2 and the fan drive 45. The spring bias of the spring 9 of the priority valve 5 changes the performance of the priority valve 5 and determines the flow resistance and thus the pressure drop across the priority valve 5 of the steering 3.

Bei unbetätigter Lenkung 3 ist das Prioritätsventil 5 in die Stellung 5b beaufschlagt, in der der Volumenstrom der Pumpe 1 vollständig der Steuerventileinrichtung 8 und somit den Steuerventilen 11 der Arbeitshydraulik 2 zuströmt. Am Prioritätsventil 5 der Lenkung 3 tritt hierbei eine Druckdifferenz auf, die in direkter Abhängigkeit zu der Federvorspannung der Feder 9 steht.When uncontrolled steering 3, the priority valve 5 is acted upon in the position 5b, in which the volume flow of the pump 1 completely flows to the control valve device 8 and thus the control valves 11 of the working hydraulics 2. At the priority valve 5 the Steering 3 occurs in this case a pressure difference, which is in direct dependence on the spring bias of the spring 9.

Bei nicht betätigten Steuerventilen 11 der Arbeitshydraulik 2 wird die Umlaufdruckwaage 15 gemäß der Figur 1 in die Durchflussstellung beaufschlagt, sofern der in der Förderzweigleitung 7 anstehende Systemdruck die Federvorspannung der Feder 17 der Umlaufdruckwaage 15 übersteigt. Hierdurch strömt bei unbetätigten Verbrauchern der Arbeitshydraulik 2 und unbetätigter Lenkung 3 der vollständige Volumenstrom der Pumpe 1 über das Prioritätsventil 5 und die Umlaufdruckwaage 15 zum Behälter. Die Druckdifferenz an der Umlaufdruckwaage 15 ist hierbei in direkter Abhängigkeit von der Federvorspannung der Feder 17.In non-actuated control valves 11 of the working hydraulics 2, the circulation pressure compensator 15 according to the FIG. 1 acted upon in the flow position, provided that in the delivery branch line 7 pending system pressure exceeds the spring preload of the spring 17 of the rotary pressure compensator 15. As a result, flows in unconfirmed consumers of the working hydraulics 2 and uncontrolled steering 3, the full flow of the pump 1 via the priority valve 5 and the circulation pressure compensator 15 to the container. The pressure difference at the circulation pressure compensator 15 is here in direct dependence on the spring preload of the spring 17.

Von der Feder des Druckminderventils 26 wird der minimal erforderliche Bremsdruck in der Steuerdruckleitung 25 definiert, der zur sicheren Betätigung der Bremseinrichtung 20 erforderlich ist.From the spring of the pressure reducing valve 26, the minimum required brake pressure in the control pressure line 25 is defined, which is required for safe operation of the braking device 20.

Die Federvorspannung der Feder 9 des Prioritätsventils 5 und die Federvorspannung der Feder 17 der Umlaufdruckwaage 15 sind bei dem erfindungsgemäßen Antriebssystem gemäß der Figur 1 derart abgestimmt, dass bei unbetätigten Verbrauchern die Summe aus der Druckdifferenz an dem Prioritätsventil 5 und der Druckdifferenz an der Umlaufdruckwaage 15 zuzüglich der Leitungswiderstände und Durchflusswiderstände weiterer Komponenten mindestens dem minimalen Bremsdruck entspricht, der von der Feder des Druckminderventils 26 definiert wird, wodurch der Bremsdruck zur Betätigung der Bremseinrichtung 20 aus dem von der Pumpe 1 in der Förderleitung 4 stromauf des Prioritätsventils 5 erzeugten Systemdruck in allen Betriebszuständen ohne zusätzliche Energieverluste aus den ohnehin auftretenden und vorhandenen Druckverlusten über das Prioritätsventils 5 und die Umlaufdruckwaage 15 bereit gestellt werden kann.The spring bias of the spring 9 of the priority valve 5 and the spring bias of the spring 17 of the rotary pressure compensator 15 are in the drive system according to the invention according to the FIG. 1 tuned so that when un-actuated consumers, the sum of the pressure difference at the priority valve 5 and the pressure difference at the circulation pressure compensator 15 plus the line resistance and flow resistance of other components at least the minimum brake pressure, which is defined by the spring of the pressure reducing valve 26, whereby the brake pressure to Operation of the braking device 20 from the system pressure generated by the pump 1 in the delivery line 4 upstream of the priority valve 5 in all operating conditions without additional energy losses from the already occurring and existing pressure losses on the priority valve 5 and the rotary pressure compensator 15 can be provided.

Bei einem verbrennungs-motorisch betriebenen Flurförderzeug, bei dem die Pumpe 1 von einer als Verbrennungsmotor ausgebildeten Arbeitsmaschine 28 im Betrieb des Flurförderzeugs ständig angetrieben ist, kann durch diese Auslegung der Federn der Umlaufdruckwaage 15 und des Prioritätsventils 5 der Lenkung 3 in allen Betriebszuständen der minimal erforderliche Bremsdruck in der Steuerdruckleitung 25 aus dem Systemdruck der Pumpe 1 stromauf des Prioritätsventils 5 erzeugt werden. Bei einem elektrisch betriebenen Flurförderzeug, bei dem die Pumpe 1 von einer als Elektromotor ausgebildeten Antriebsmaschine 28 angetrieben ist, wird die Pumpe 1 lediglich bei einer Anforderung der Lenkung 3 und/oder der Arbeitshydraulik 3 betrieben. Durch das Sperrventil 30 in Verbindung mit dem Druckspeicher 29 kann der Bremsdruck bei abgeschalteter Pumpe 1 aufrechterhalten werden. Sofern sich der Bremsdruck durch Leckagen abbaut, kann durch einen kurzzeitigen Betrieb der Pumpe 1 der Druckmittelspeicher 29 aufgeladen werden, um den Bremsdruck wieder aufrechtzuerhalten.In an internal combustion engine-powered truck, in which the pump 1 is driven by a trained as an internal combustion engine work machine 28 during operation of the truck, can by this design of the springs of the circulation pressure compensator 15 and the priority valve 5 of the steering 3 in all operating conditions of the minimum required Brake pressure in the control pressure line 25 from the system pressure of the pump 1 upstream of the priority valve 5 are generated. In an electrically operated industrial truck, in which the pump 1 is driven by a drive machine designed as an electric motor 28, the pump 1 is operated only upon request of the steering 3 and / or the working hydraulics 3. By the check valve 30 in conjunction with the pressure accumulator 29, the brake pressure can be maintained when the pump 1 is switched off. If the brake pressure degrades through leaks, the accumulator 29 can be charged by a brief operation of the pump 1 to maintain the brake pressure again.

Bei einem erfindungsgemäßen Antriebssystem gemäß der Figur 2 setzt sich bei nicht betätigten Verbrauchern der Arbeitshydraulik 2, nicht betätigtem Lüfterantrieb 45 und nicht betätigter Lenkung 3 der Systemdruck in der Förderleitung 4 aus der Summe des beispielsweise von einer Feder an der von einem Bedarfstromregelventil gebildeten Fordervolumenstelleinrichtung 40 bestimmten Standby-Druckes der Pumpe 1 und der Druckdifferenz an dem Prioritätsventil 5 sowie zuzüglich der Leitungswiderstände und Durchflusswiderstände weiterer Komponenten zusammen. Durch entsprechende Abstimmung des Standby-Druckes der Pumpe 1 und der Federvorspannung der Feder 9 des Prioritätsventils 5 kann hierbei ebenfalls auf einfache Weise erzielt werden, dass aus dem Systemdruck der Pumpe 1 in der Förderleitung 4 stromauf des Prioritätsventils 5 der von der Feder des Druckminderventils 26 bestimmte minimale Bremsdruck zur Betätigung der Bremseinrichtung 20 in allen Betriebszuständen erzeugt und ohne zusätzliche Energieverluste bereit gestellt werden kann.In a drive system according to the invention according to the FIG. 2 is set in non-actuated consumers of the working hydraulics 2, non-actuated fan drive 45 and non-actuated steering system pressure 3 in the delivery line 4 from the sum of, for example, by a spring on the Fordervolumenstelleinrichtung 40 formed by a demand control valve standby pressure of the pump 1 and the Pressure difference at the priority valve 5 and plus the line resistance and flow resistance of other components together. By appropriate adjustment of the standby pressure of the pump 1 and the spring bias of the spring 9 of the priority valve 5 can also be achieved in a simple manner that from the system pressure of the pump 1 in the delivery line 4 upstream of the priority valve 5 of the spring of the pressure reducing valve 26th certain minimum brake pressure to actuate the brake device 20 generated in all operating conditions and can be provided without additional energy losses.

Über die Zweigleitung 51 und die Beaufschlagung der Förderstromregeleinrichtung 40 von dem Bremsdruck in der Steuerdruckleitung 25 kann auf einfache Weise vermieden werden, dass in bestimmten Betriebspunkten, beispielsweise beim Heben eines Hubantriebs ohne Last der Systemdruck unter den Wert des Bremsdruckes einbricht.About the branch line 51 and the loading of the flow control device 40 of the brake pressure in the control pressure line 25 can be easily avoided that breaks down at certain operating points, for example, when lifting a linear actuator with no load, the system pressure below the value of the brake pressure.

Durch lediglich geringfügige Anhebung des Systemdruckes gegenüber Antriebssystemen des Standes der Technik kann bei dem erfindungsgemäßen Antriebsystem durch den Anschluss der Steuerdruckleitung 25 an die Förderleitung 4 stromauf des Prioritätsventils 5 in Verbindung mit dem Druckminderventil 26 ein konstanter Bremsdruck zur sicheren Betätigung der Bremseinrichtung 20 aus dem Systemdruck der Pumpe 1 stromauf des Prioritätsventils 5 ohne zusätzliche Energieverluste erzeugt werden. Zudem kann über die Steuerdruckversorgungsleitung 27, die von der den Bremsdruck führenden Steuerdruckleitung 25 abzweigt, eine externe Steuerdruckversorgung für die elektro-hydraulisch betätigten und vorgesteuerten Steuerventile 11 der Arbeitshydraulik 2 mit konstantem Steuerdruck aus dem von der Pumpe 1 erzeugten Systemdruck auf einfache Weise erzielt werden.By only slightly raising the system pressure compared to drive systems of the prior art can in the drive system according to the invention by connecting the control pressure line 25 to the delivery line 4 upstream of the priority valve 5 in conjunction with the pressure reducing valve 26, a constant brake pressure for safe operation of the braking device 20 from the system pressure Pump 1 upstream of the priority valve 5 are generated without additional energy losses. In addition, via the control pressure supply line 27, which branches from the brake pressure leading the control pressure line 25, an external control pressure supply for the electro-hydraulically operated and pilot operated control valves 11 of the working hydraulics 2 with constant control pressure from the system pressure generated by the pump 1 can be achieved in a simple manner.

Mit dem Druckminderventil 26 kann hierbei bei geringem Bauaufwand und geringem Energieverbrauch ein konstanter Bremsdruck der Bremseinrichtung 20 bei einem als Open-Center-System gemäß der Figur 1 oder einem als Closed-Center-System gemäß der Figur 2 ausgebildeten hydrostatischen Antriebssystem aus dem von der Pumpe 1 erzeugten Systemdruck stromauf des Prioritätsventils 5 der Lenkung 3 erzielt werden.With the pressure reducing valve 26 can here at low construction costs and low energy consumption, a constant brake pressure of the braking device 20 in an open-center system according to the FIG. 1 or as a closed-center system according to the FIG. 2 trained hydrostatic drive system from the system pressure generated by the pump 1 upstream of the priority valve 5 of the steering 3 can be achieved.

Die Erfindung kann hierbei bei verbrennungsmotorisch betriebenen Arbeitsmaschinen, bei denen die Pumpe 1 von einem Verbrennungsmotor angetrieben ist, oder elektrisch, insbesondere batterie-elektrisch, betriebenen Arbeitsmaschinen, bei denen die Pumpe 1 von einem Elektromotor angetrieben ist, eingesetzt werden. Bei einer mittels eines Elektromotors angetriebenen Pumpe 1 kann mit dem Druckspeicher 29 in Verbindung mit dem Sperrventil 30 bei abgeschalteter Pumpe 1 der Bremsdruck in der Steuerdruckleitung 25 auf einfache Weise aufrechterhalten werden.The invention can in this case be used in internal combustion engine operated machines in which the pump 1 is driven by an internal combustion engine, or electrically, in particular battery-electric, powered machines in which the pump 1 is driven by an electric motor, are used. In a driven by an electric motor pump 1, the brake pressure in the control pressure line 25 can be maintained in a simple manner with the pressure accumulator 29 in conjunction with the check valve 30 with the pump 1 switched off.

Claims (13)

  1. Hydrostatic drive system for a mobile work machine, in particular an industrial truck, with a pump (1) which is provided for supplying at least one consumer of working hydraulics (2) and a hydraulic steering system (3), and with a hydraulic brake device (20) which is controllable by means of a brake pressure and is designed as a spring-loaded brake and is loaded into a release position by means of the brake pressure, wherein a priority valve (5) for the preferential supply of the steering system (3) is arranged in a delivery line (4) of the pump (1), and wherein, in order to generate the brake pressure, a control pressure line (25) which is connected to the delivery line (4) of the pump (1) upstream of the priority valve (5) of the steering system (3) is provided, characterized in that, when the consumer of the working hydraulics (2) is not actuated and the steering system (3) is not actuated, the brake pressure for actuating the brake device (20) into the release position is provided at every operating point from the system pressure, which is generated by the pump (1) in the delivery line (4) upstream of the priority valve (5), using the prestress of the priority valve (5).
  2. Hydrostatic drive system according to Claim 1, characterized in that the priority valve (5) is loaded by means of a spring (9) in the direction of a position connecting the delivery line (4) of the pump (1) to the steering system (3).
  3. Hydrostatic drive system according to Claim 1 or 2, characterized in that the control pressure line (25) is guided to a brake valve (21) of the brake device (20), wherein a pressure-reducing valve (26) is arranged in the control pressure line (25).
  4. Hydrostatic drive system according to one of Claims 1 to 3, characterized in that the pump (1) is designed as a fixed displacement pump, and a control valve device (8) for controlling the working hydraulics (2) has a circulation pressure balance (15) which is loaded by the highest load pressure of the consumers of the working hydraulics (2) and by a spring (17) in the direction of a blocking position and by the delivery pressure of the pump (1) in the direction of a through flow position.
  5. Hydrostatic drive system according to Claim 4, characterized in that the spring prestress of the priority valve (5) and the spring prestress of the circulation pressure balance (15) are set in such a manner that a minimum brake pressure can be generated in the control pressure line (25) at a every operating point.
  6. Hydrostatic drive system according to one of Claims 1 to 3, characterized in that the pump (1) is designed as a load-sensing-controlled variable displacement pump which is controlled by the highest load pressure of the working hydraulics (2) and/or the steering system (3).
  7. Hydrostatic drive system according to Claim 6, characterized in that a load pressure signal line (41) which is guided to a volumetric delivery setting device (40) of the pump is connected to the control pressure line (25).
  8. Hydrostatic drive system according to Claim 7, characterized in that a branch line (51) is guided from the control pressure line (25) downstream of the pressure-reducing valve (26) to an input of a selector valve (52), at the further input of which a branch line (53) carrying the highest load pressure of the working hydraulics (2) and/or of the steering device (3) is connected, wherein the selector valve (52) is connected on the output side to the load pressure signal line (41) guided to the volumetric delivery setting device (40) of the pump (1).
  9. Hydrostatic drive system according to one of Claims 6 to 8, characterized in that the standby pressure of the pump (1) and/or the spring prestress of the priority valve (5) are set in such a manner that the minimum brake pressure can be generated in the control pressure line (25) at each operating point.
  10. Hydrostatic drive system according to one of Claims 1 to 9, characterized in that the control pressure line (25) is assigned a pressure medium accumulator (29).
  11. Hydrostatic drive system according to Claim 10, characterized in that a shut-off valve (30) opening in the direction of the pressure-reducing valve (26), in particular a nonreturn valve, is arranged in the control pressure line (25) upstream of the accumulator device (29) and/or upstream of the pressure-reducing valve (26).
  12. Hydrostatic drive system according to one of Claims 1 to 11, characterized in that an electro-hydraulically actuable control valve (11), in particular a directional control valve, is provided for controlling the consumer of the working hydraulics (2), wherein a control pressure supply line (27) of the control valve (11) is connected to the control pressure line (25).
  13. Hydrostatic drive system according to Claim 12, characterized in that the control pressure supply line (27) is connected to the control pressure line (25) downstream of the pressure-reducing valve (26).
EP10004441.1A 2009-05-25 2010-04-27 Hydrostatic drive system for a mobile work machine Not-in-force EP2256082B9 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE200910022468 DE102009022468A1 (en) 2009-05-25 2009-05-25 Hydrostatic drive system of a mobile work machine

Publications (4)

Publication Number Publication Date
EP2256082A2 EP2256082A2 (en) 2010-12-01
EP2256082A3 EP2256082A3 (en) 2011-01-19
EP2256082B1 true EP2256082B1 (en) 2015-07-29
EP2256082B9 EP2256082B9 (en) 2015-10-14

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP10004441.1A Not-in-force EP2256082B9 (en) 2009-05-25 2010-04-27 Hydrostatic drive system for a mobile work machine

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EP (1) EP2256082B9 (en)
DE (1) DE102009022468A1 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107842533B (en) * 2016-09-19 2020-03-31 比亚迪股份有限公司 Priority valve device and vehicle with same
CN107842531B (en) * 2016-09-21 2019-11-22 比亚迪股份有限公司 The hydraulic integrated control system and vehicle of vehicle
CN111765135B (en) * 2020-07-10 2022-05-06 中国铁建重工集团股份有限公司 Hydraulic control system for arch frame operation trolley

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19746090B4 (en) * 1997-09-24 2008-08-28 Linde Material Handling Gmbh Hydrostatic drive system for a vehicle
DE10151831B4 (en) * 2001-10-20 2011-12-22 Still Gmbh Hydraulic system for a truck
DE10315494A1 (en) 2003-04-04 2004-10-21 Linde Ag Hydraulic system for electrically driven floor conveyor, has pump that is driven by electric motor to cool structural component of floor conveyor and actuate hydraulic steering mechanism and drive axle
DE10315496A1 (en) 2003-04-04 2004-10-21 Linde Ag Hydraulic system for a battery-operated industrial truck has two hydraulic pumps, the second pump being used for additional supply to a lifting mechanism
DE202004010530U1 (en) * 2004-07-06 2004-12-09 Deere & Company, Moline Hydraulic circuit with priority valve for vehicle has at least one further priority valve with which priority of only one load is regulated and that also has pressure adaptation function

Also Published As

Publication number Publication date
EP2256082B9 (en) 2015-10-14
EP2256082A2 (en) 2010-12-01
DE102009022468A1 (en) 2010-12-02
EP2256082A3 (en) 2011-01-19

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