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EP3680493B1 - Switching assembly - Google Patents

Switching assembly Download PDF

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Publication number
EP3680493B1
EP3680493B1 EP19218530.4A EP19218530A EP3680493B1 EP 3680493 B1 EP3680493 B1 EP 3680493B1 EP 19218530 A EP19218530 A EP 19218530A EP 3680493 B1 EP3680493 B1 EP 3680493B1
Authority
EP
European Patent Office
Prior art keywords
working device
pressure
valve
circuit arrangement
lowering
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.)
Active
Application number
EP19218530.4A
Other languages
German (de)
French (fr)
Other versions
EP3680493A1 (en
Inventor
Peter Bruck
Markus Veit
Patrick Hans
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hydac Fluidtechnik GmbH
Original Assignee
Hydac Fluidtechnik GmbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Hydac Fluidtechnik GmbH filed Critical Hydac Fluidtechnik GmbH
Publication of EP3680493A1 publication Critical patent/EP3680493A1/en
Application granted granted Critical
Publication of EP3680493B1 publication Critical patent/EP3680493B1/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/044—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the return line, i.e. "meter out"
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/27—Directional control by means of the pressure source
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30505—Non-return valves, i.e. check valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
    • F15B2211/31552—Directional control characterised by the connections of the valve or valves in the circuit being connected to an output member and a return line
    • F15B2211/31558—Directional control characterised by the connections of the valve or valves in the circuit being connected to an output member and a return line having a single output member
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/327—Directional control characterised by the type of actuation electrically or electronically
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/35—Directional control combined with flow control
    • F15B2211/353—Flow control by regulating means in return line, i.e. meter-out control
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5157—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a return line
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/52—Pressure control characterised by the type of actuation
    • F15B2211/526—Pressure control characterised by the type of actuation electrically or electronically
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6336—Electronic controllers using input signals representing a state of the output member, e.g. position, speed or acceleration
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7052—Single-acting output members
    • 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
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/76—Control of force or torque of the output member
    • F15B2211/761—Control of a negative load, i.e. of a load generating hydraulic energy

Definitions

  • the invention relates to a circuit arrangement for load-pressure-optimized lowering of loads, having the features in the preamble of claim 1.
  • Circuit arrangements of this type are state of the art and are preferably used in industrial trucks to control working cylinders in the form of lifting cylinders for hoists, such as lifting forks, for lifting loads.
  • the lowering of raised loads caused by gravity takes place via electromagnetically actuatable lowering valves, which are arranged in the fluid return and can be controlled by input commands from an operator.
  • the known circuit arrangements have, in addition to a main lowering valve that blocks or releases the return, a proportional flow control valve as a second lowering valve, via which the operator can set the lowering speed.
  • the known circuit arrangement in the inlet has a non-return valve that prevents lowering via the pump and a pressure-limiting valve that secures the arrangement against impermissible overpressure and prevents loads that are too heavy from being lifted.
  • a non-return valve that prevents lowering via the pump
  • a pressure-limiting valve that secures the arrangement against impermissible overpressure and prevents loads that are too heavy from being lifted.
  • 4,873,817 describes a circuit arrangement with the features in the preamble of claim 1 for load-pressure-optimized lowering of loads by means of a fluidically drivable working device, in particular in the form of at least one hydraulic working cylinder, which can be supplied by a motor-pump unit with a fluid of predeterminable pressure in the inlet for lifting the respective load , and with a return for discharging fluid from the working device when lowering this load, with a proportional pressure relief valve being connected in the return, which performs a dual function in that it acts as a pressure relief valve or as a Proportional valve is used, the return opens with the proportional pressure relief valve in a connection point in the inlet.
  • More circuits go from the DE 10 2007 040 877 A1 , the EP 2 524 585 A2 , the DE 10 2006 205 582 A1 and the DE 10 2012 005 432 A1 out.
  • the object of the invention is to provide a circuit arrangement of the type mentioned at the outset which, while retaining the advantages of the known circuit arrangement, such as redundancy, is characterized by a simpler and more cost-effective design in comparison.
  • this object is achieved by a circuit arrangement which has the features of patent claim 1 in its entirety.
  • a check valve is switched in the form of a 2/2-way check valve. With the shut-off valve forming the main lowering valve and the proportional pressure-limiting valve, the redundant protection of the outflow or the lowering path is formed.
  • a proportional pressure-limiting valve is connected in the return, which performs a dual function in that it serves as a pressure-limiting valve or as a proportional valve when the load is raised and lowered by means of the hydraulic working device.
  • the double function of the proportional pressure relief valve which on the one hand limits the load pressure prevailing in the inlet when the load is lifted to a permissible pressure and on the other hand serves as a proportionally operating lowering valve when the load is lowered, makes it possible to save one valve and a corresponding cost saving in the circuit arrangement according to the invention.
  • the proportional behavior enables sensitive, load-independent lowering.
  • the main lowering valve which is formed by a check valve and is arranged in the return, the redundancy as a safeguard against falling of the load in the event of a failure of one of the valves is retained despite the saving of one valve.
  • the proportional pressure-limiting valve can be actuated electromagnetically and receives its electrical setpoint specification from a controller in which a family of characteristics for this proportional pressure-limiting valve is stored.
  • the arrangement is such that the control for further processing receives sensor data as input variables in the form of the current fluid pressure of the working device depending on its state of motion and in the form of the distance covered depending on the position of the hydraulic working device or in the form of the speed of movement this work facility. let through For loads of different weights to be lifted and the resulting load pressures, the values of the current supply to the proportional pressure relief valve can be determined at which the return volume flow has the desired characteristic curve and thus the desired lowering speed results.
  • the distance or the speed is recorded via a distance or speed measuring system on the hydraulic working device, and the current fluid pressure is recorded by a pressure transducer in the direct inlet of the working device.
  • the controller For the selection of the working speed when operating the respective working device, such as the lifting cylinder, the controller processes control inputs from an operator as a further input variable.
  • a check valve is connected between the connection point and a pressure supply connection for the working device. This arrangement achieves redundancy both in the inflow and in the outflow.
  • a non-return valve is connected between the motor-pump unit and the connection point, which opens in the direction of the working device.
  • the invention also relates to a method for operating the circuit arrangement according to one of patent claims 1 to 7, the method having the features of patent claim 8.
  • the prior art circuit arrangement 2 shown has a pressure supply connection designated P for the connection of a fluidically drivable working device, not shown, such as a lifting cylinder of an industrial truck .
  • the arrangement 2 has a motor-pump unit 4 that can be driven by an electric motor, the suction side of the hydraulic pump 6 of which is connected to a fluid storage tank 10 via a suction filter 8 .
  • the pressure side of the hydraulic pump 6 is connected to the supply port P via an inlet line 12 .
  • a non-return valve 14 is arranged in the feed line 12, which opens in the direction of the pressure supply connection P and prevents, when the motor-pump unit 4 is shut down, a return flow caused by the load pressure at the pressure supply connection P taking place via the pump 6 and thus a lowering of a raised load via the Pump 6 prevented.
  • a return line 18 leading to the tank 10 is connected to a connection point 16 of the inlet line 12 located between the check valve 14 and the pressure supply connection P.
  • a pressure-limiting valve 20 is connected to the supply line 12 between the pump 6 and the non-return valve 14, which secures the supply line 12 to the return line 18 and thus to the tank 10 against impermissible overpressure and thus also forms a safeguard against lifting excessively heavy loads.
  • Two lowering valves are arranged in the return line 18 , which branches off from the supply line 12 at the connection point 16 , for lowering operations of raised loads that take place via the return line 18 .
  • a check valve 22 in the form of an electromagnetically actuated 2/2-way valve which, as the main lowering valve, blocks or opens the return line 18 .
  • a proportional control valve 24 is connected in the return line 18 as the second lowering valve.
  • An electrical control unit provided for activating the electromagnetically actuable proportional control valve 24 in slide or seat design receives a pressure signal from a pressure transducer 26, which corresponds to the load pressure of a respective load, which has been raised by previously switching on the motor-pump unit 4 and is lowered after the pump 6 has stopped shall be.
  • a sensitive control of the lowering speed by controlling the proportional flow control valve 24 is made possible on the basis of the load pressure signal supplied by the pressure transducer 26 and on the basis of command signals which the relevant operator enters to select the lowering speed.
  • the arrangement of two series-connected valves 22 and 24 in the return line 18 provides redundancy which, in the event of a failure of one of the valves 22, 24, prevents the lifted load from falling.
  • FIG. 2 which shows an embodiment of the circuit arrangement according to the invention, are elements that are those of 1 correspond functionally, denoted by the same reference numerals.
  • the pertinent elements are to the solution according to the invention 2 belonging.
  • an inlet line 12 leading to the pressure supply valve P is connected to the pressure side of the hydraulic pump 6 of a motor-pump unit 4, the suction side of which is connected to the fluid storage tank 10 via a suction filter 8.
  • the work facility to be supplied is in 2 a lifting cylinder 28 is shown, whose working chamber 30 on the piston side is connected directly to the pressure supply port P.
  • the 2 also shows the in 1 not shown, designated 32 electrical control unit.
  • As in 1 receives a load pressure signal from the pressure transducer 26 connected to the pressure supply port P.
  • the control unit receives a displacement signal from a displacement measuring system 34 provided on the lifting cylinder 28, which signal represents the piston position of the lifting cylinder 28.
  • the check valve 22 is switched on in the supply line 12 in an area 36 which is located between the connection point 16 at which the return line 18 branches off and the pressure supply port P.
  • the check valve 22 thus forms not only the main lowering valve, but also an element controlling the inflow.
  • line section 36 of supply line 12 which is located between check valve 22 and connection point 16 forms the first part of return 18, the second section of which connects to connection point 16 and leads to tank 10.
  • a proportional pressure-relief valve 38 In the part connected to the connection point 16 there is a proportional pressure-relief valve 38. When the load is lifted, it secures the feed line 12 in the same way as the pressure-relief valve 20 of the known arrangement from FIG 1 against impermissible overpressure.
  • a proportionally acting, electromagnetically actuable valve it simultaneously takes over the control function of the proportional valve 24 of the known arrangement in a dual function.
  • the valve 38 is closed more when the lowering speed is too high and is opened more when the speed is too low.
  • the lowering speed can be sensitively and steplessly regulated based on the speed input by the operator and regardless of the weight of the respective load.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)

Description

Die Erfindung betrifft eine Schaltungsanordnung zum lastdruckoptimierten Absenken von Lasten mit den Merkmalen im Oberbegriff von Anspruch 1.The invention relates to a circuit arrangement for load-pressure-optimized lowering of loads, having the features in the preamble of claim 1.

Schaltungsanordnungen dieser Art sind Stand der Technik und kommen bevorzugt bei Flurförderzeugen zur Steuerung von Arbeitszylindern in Form von Hubzylindern für Hebezeuge, wie Hubgabeln, zum Heben von Lasten zum Einsatz. Das durch Schwerkraft bewirkte Absenken angehobener Lasten erfolgt über elektromagnetisch betätigbare Senkventile, die im Fluidrücklauf angeordnet und durch Eingabebefehle eines Bedieners ansteuerbar sind. Um eine lastunabhängige Regelung der Senkgeschwindigkeit zu ermöglichen, weisen die bekannten Schaltungsanordnungen neben einem den Rücklauf sperrenden oder freigebenden Hauptsenkventil ein Proportionalstromregelventil als zweites Senkventil auf, über das der Bediener die Senkgeschwindigkeit einstellen kann. Des Weiteren weist die bekannte Schaltungsanordnung im Zulauf ein Absenken über die Pumpe verhinderndes Rückschlagventil sowie ein Druckbegrenzungsventil auf, das die Anordnung gegen unzulässigen Überdruck sichert und das Anheben zu schwerer Lasten verhindert. Zwar stellt die Anordnung zweier Senkventile, dem Hauptsenkventil und dem Proportionalventil, eine Redundanz zur Verfügung, die ein Abstürzen der Last bei Versagen eines der Senkventile verhindert, die bekannte Schaltungsanordnung ist jedoch aufgrund des Vorhandenseins von insgesamt vier Ventilen verhältnismäßig bauaufwendig. Die US 4 873 817 beschreibt eine Schaltungsanordnung mit den Merkmalen im Oberbegriff von Anspruch 1 zum lastdruckoptimierten Absenken von Lasten mittels einer fluidisch antreibbaren Arbeitseinrichtung, insbesondere in Form mindestens eines hydraulischen Arbeitszylinders, die von einer Motor-Pumpeneinheit mit einem Fluid vorgebbaren Drucks im Zulauf zum Heben der jeweiligen Last versorgbar ist, und mit einem Rücklauf zur Abfuhr von Fluid aus der Arbeitseinrichtung beim Senken dieser Last, wobei in den Rücklauf ein Proportional-Druckbegrenzungsventil geschaltet ist, das eine Doppelfunktion wahrnimmt, indem es beim Heben und Senken der Last mittels der hydraulischen Arbeitseinrichtung als Druckbegrenzungsventil bzw. als Proportionalventil dient, wobei der Rücklauf mit dem Proportional-Druckbegrenzungsventil in eine Verbindungsstelle im Zulauf einmündet.Circuit arrangements of this type are state of the art and are preferably used in industrial trucks to control working cylinders in the form of lifting cylinders for hoists, such as lifting forks, for lifting loads. The lowering of raised loads caused by gravity takes place via electromagnetically actuatable lowering valves, which are arranged in the fluid return and can be controlled by input commands from an operator. In order to enable load-independent control of the lowering speed, the known circuit arrangements have, in addition to a main lowering valve that blocks or releases the return, a proportional flow control valve as a second lowering valve, via which the operator can set the lowering speed. Furthermore, the known circuit arrangement in the inlet has a non-return valve that prevents lowering via the pump and a pressure-limiting valve that secures the arrangement against impermissible overpressure and prevents loads that are too heavy from being lifted. Although the arrangement of two lowering valves, the main lowering valve and the proportional valve, provides a redundancy that prevents the load from falling if one of the lowering valves fails, However, the known circuit arrangement is relatively complex due to the presence of a total of four valves. the U.S. 4,873,817 describes a circuit arrangement with the features in the preamble of claim 1 for load-pressure-optimized lowering of loads by means of a fluidically drivable working device, in particular in the form of at least one hydraulic working cylinder, which can be supplied by a motor-pump unit with a fluid of predeterminable pressure in the inlet for lifting the respective load , and with a return for discharging fluid from the working device when lowering this load, with a proportional pressure relief valve being connected in the return, which performs a dual function in that it acts as a pressure relief valve or as a Proportional valve is used, the return opens with the proportional pressure relief valve in a connection point in the inlet.

Weitere Schaltungsanordnungen gehen aus der DE 10 2007 040 877 A1 , der EP 2 524 585 A2 , der DE 10 2006 205 582 A1 und der DE 10 2012 005 432 A1 hervor.More circuits go from the DE 10 2007 040 877 A1 , the EP 2 524 585 A2 , the DE 10 2006 205 582 A1 and the DE 10 2012 005 432 A1 out.

Ausgehend von diesem Stand der Technik stellt sich die Erfindung die Aufgabe, eine Schaltungsanordnung der eingangs genannten Gattung zur Verfügung zu stellen, die sich, bei Beibehalten der Vorteile, wie der Redundanz, der bekannten Schaltungsanordnung durch eine demgegenüber einfachere und kostengünstigere Bauweise auszeichnet.Proceeding from this prior art, the object of the invention is to provide a circuit arrangement of the type mentioned at the outset which, while retaining the advantages of the known circuit arrangement, such as redundancy, is characterized by a simpler and more cost-effective design in comparison.

Erfindungsgemäß ist diese Aufgabe durch eine Schaltungsanordnung gelöst, die die Merkmale des Patentanspruchs 1 in seiner Gesamtheit aufweist. Gemäß dem kennzeichnenden Teil des Anspruchs 1 ist vorgesehen, dass zwischen der Verbindungsstelle und der Arbeitseinrichtung ein Sperrventil in Form eines 2/2-Wege-Sperrventils geschaltet ist. Mit dem das Haupt-Senkventil bildenden Sperrventil und dem Proportional-Druckbegrenzungsventil ist so die redundante Absicherung des Ablaufs respektive des Senkpfades gebildet.According to the invention, this object is achieved by a circuit arrangement which has the features of patent claim 1 in its entirety. According to the characterizing part of claim 1 it is provided that between the connection point and the working device a check valve is switched in the form of a 2/2-way check valve. With the shut-off valve forming the main lowering valve and the proportional pressure-limiting valve, the redundant protection of the outflow or the lowering path is formed.

Bei der erfindungsgemäßen Schaltungsanordnung ist in den Rücklauf ein Proportional-Druckbegrenzungsventil geschaltet, das eine Doppelfunktion wahrnimmt, indem es beim Heben und Senken der Last mittels der hydraulischen Arbeitseinrichtung als Druckbegrenzungsventil bzw. als Proportionalventil dient. Die Doppelfunktion des Proportional-Druckbegrenzungsventils, das einerseits den beim Heben der Last den im Zulauf herrschenden Lastdruck auf einen zulässigen Druck begrenzt und andererseits beim Senken der Last als proportional arbeitendes Senkventil dient, ermöglicht die Einsparung eines Ventils und eine entsprechende Kosteneinsparung bei der erfindungsgemäßen Schaltungsanordnung. Gleichzeitig ermöglicht das proportionale Verhalten ein feinfühliges, lastunabhängiges Absenken. In Verbindung mit dem durch ein Sperrventil gebildeten, im Rücklauf angeordneten Haupt-Senkventil bleibt trotz der Einsparung eines Ventils die Redundanz als Sicherung gegen Abstürzen der Last bei Versagen eines der Ventile erhalten.In the circuit arrangement according to the invention, a proportional pressure-limiting valve is connected in the return, which performs a dual function in that it serves as a pressure-limiting valve or as a proportional valve when the load is raised and lowered by means of the hydraulic working device. The double function of the proportional pressure relief valve, which on the one hand limits the load pressure prevailing in the inlet when the load is lifted to a permissible pressure and on the other hand serves as a proportionally operating lowering valve when the load is lowered, makes it possible to save one valve and a corresponding cost saving in the circuit arrangement according to the invention. At the same time, the proportional behavior enables sensitive, load-independent lowering. In connection with the main lowering valve, which is formed by a check valve and is arranged in the return, the redundancy as a safeguard against falling of the load in the event of a failure of one of the valves is retained despite the saving of one valve.

Bei vorteilhaften Ausführungsbeispielen ist das Proportional-Druckbegrenzungsventil elektromagnetisch ansteuerbar und erhält seine elektrische Sollwertvorgabe von einer Steuerung, in der ein Kennlinienfeld für dieses Proportional-Druckbegrenzungsventil hinterlegt ist.In advantageous exemplary embodiments, the proportional pressure-limiting valve can be actuated electromagnetically and receives its electrical setpoint specification from a controller in which a family of characteristics for this proportional pressure-limiting valve is stored.

Mit Vorteil ist hierbei die Anordnung so getroffen, dass die Steuerung zur weiteren Verarbeitung als Eingangsgrößen Sensordaten erhält in Form des aktuellen Fluiddrucks der Arbeitseinrichtung in Abhängigkeit von deren Bewegungszustand und in Form der zurückgelegten Wegstrecke in Abhängigkeit von der Position der hydraulischen Arbeitseinrichtung oder in Form der Bewegungsgeschwindigkeit dieser Arbeitseinrichtung. Dadurch lassen sich für zu hebende Lasten unterschiedlichen Gewichts und sich dadurch ergebenden Lastdrücken die Werte der Bestromung des Proportional-Druckbegrenzungsventils ermitteln, bei denen der Rücklauf-Volumenstrom den gewünschten Kennlinienverlauf besitzt und damit die gewünschte Senkgeschwindigkeit resultiert.Advantageously, the arrangement is such that the control for further processing receives sensor data as input variables in the form of the current fluid pressure of the working device depending on its state of motion and in the form of the distance covered depending on the position of the hydraulic working device or in the form of the speed of movement this work facility. let through For loads of different weights to be lifted and the resulting load pressures, the values of the current supply to the proportional pressure relief valve can be determined at which the return volume flow has the desired characteristic curve and thus the desired lowering speed results.

Mit Vorteil ist hierbei die Wegstrecke oder die Geschwindigkeit über ein Weg- bzw. Geschwindigkeits-Messsystem an der hydraulischen Arbeitseinrichtung erfasst, und der aktuelle Fluiddruck ist durch einen Druckwertaufnehmer im unmittelbaren Zulauf der Arbeitseinrichtung erfasst.Advantageously, the distance or the speed is recorded via a distance or speed measuring system on the hydraulic working device, and the current fluid pressure is recorded by a pressure transducer in the direct inlet of the working device.

Für die Wahl der Arbeitsgeschwindigkeit beim Betrieb der jeweiligen Arbeitseinrichtung, wie dem Hubzylinder, verarbeitet die Steuerung als weitere Eingangsgröße Steuereingaben einer Bedienperson.For the selection of the working speed when operating the respective working device, such as the lifting cylinder, the controller processes control inputs from an operator as a further input variable.

Bei einer bevorzugten Ausführungsform der Erfindung ist vorgesehen, dass ein Sperrventil zwischen der Verbindungsstelle und einem Druckversorgungsanschluss für die Arbeitseinrichtung geschaltet ist. Durch diese Anordnung ist eine Redundanz sowohl im Zulauf als auch im Ablauf erreicht.In a preferred embodiment of the invention, it is provided that a check valve is connected between the connection point and a pressure supply connection for the working device. This arrangement achieves redundancy both in the inflow and in the outflow.

Als Sicherung gegen ein Absenken durch Rückstrom im Zulauf ist zwischen der Motor-Pumpeneinheit und der Verbindungsstelle ein Rückschlagventil geschaltet, das in Richtung der Arbeitseinrichtung öffnet.To protect against lowering due to backflow in the inlet, a non-return valve is connected between the motor-pump unit and the connection point, which opens in the direction of the working device.

Gegenstand der Erfindung ist auch ein Verfahren zum Betrieb der Schaltungsanordnung nach einem der Patentansprüche 1 bis 7, wobei das Verfahren die Merkmale des Patentanspruchs 8 aufweist.The invention also relates to a method for operating the circuit arrangement according to one of patent claims 1 to 7, the method having the features of patent claim 8.

Nachstehend ist die Erfindung anhand der beigefügten Zeichnung im Einzelnen erläutert. Es zeigen:

Fig. 1
in Symboldarstellung eine Schaltungsanordnung für die Versorgung einer fluidisch antreibbaren Arbeitseinrichtung gemäß dem Stand der Technik; und
Fig. 2
in Symboldarstellung eine entsprechende Darstellung gemäß einem Ausführungsbeispiel der vorliegenden Erfindung.
The invention is explained in detail below with reference to the attached drawing. Show it:
1
a symbolic representation of a circuit arrangement for the supply of a fluidically drivable working device according to the prior art; and
2
in symbolic representation a corresponding representation according to an embodiment of the present invention.

Die in Fig. 1 gezeigte Schaltungsanordnung 2 des Standes der Technik weist für den Anschluss einer nicht dargestellten fluidisch antreibbaren Arbeitseinrichtung, wie einem Hubzylinder eines Flurförderzeuges, einen mit P bezeichneten Druckversorgungsanschluss auf, der beim Einsatz der Schaltungsanordnung beispielsweise mit dem kolbenseitigen Arbeitsraum des betreffenden, nicht gezeigten Hubzylinders unmittelbar verbunden ist. Für die Druckversorgung weist die Anordnung 2 eine elektromotorisch antreibbare Motor-Pumpeneinheit 4 auf, deren Hydropumpe 6 mit ihrer Saugseite über ein Saugfilter 8 mit einem Fluid-Vorratstank 10 in Verbindung ist. Die Druckseite der Hydropumpe 6 ist über eine Zulaufleitung 12 mit dem Versorgungsanschluss P in Verbindung. In der Zulaufleitung 12 ist ein Rückschlagventil 14 angeordnet, das in Richtung zum Druckversorgungsanschluss P öffnet und verhindert, dass bei stillgesetzter Motor-Pumpeneinheit 4 ein durch den Lastdruck am Druckversorgungsanschluss P bewirkter Rückstrom über die Pumpe 6 erfolgt und damit ein Absenken einer angehobenen Last über die Pumpe 6 verhindert. An einer zwischen Rückschlagventil 14 und Druckversorgungsanschluss P gelegenen Verbindungsstelle 16 der Zulaufleitung 12 ist eine Rücklaufleitung 18 angeschlossen, die zum Tank 10 führt. Zwischen der Pumpe 6 und dem Rückschlagventil 14 ist des Weiteren an der Zulaufleitung 12 ein Druckbegrenzungsventil 20 angeschlossen, das die Zulaufleitung 12 zur Rücklaufleitung 18 und damit zum Tank 10 hin gegen unzulässigen Überdruck sichert und dadurch auch eine Sicherung gegen das Anheben zu schwerer Lasten bildet.In the 1 The prior art circuit arrangement 2 shown has a pressure supply connection designated P for the connection of a fluidically drivable working device, not shown, such as a lifting cylinder of an industrial truck . For the pressure supply, the arrangement 2 has a motor-pump unit 4 that can be driven by an electric motor, the suction side of the hydraulic pump 6 of which is connected to a fluid storage tank 10 via a suction filter 8 . The pressure side of the hydraulic pump 6 is connected to the supply port P via an inlet line 12 . A non-return valve 14 is arranged in the feed line 12, which opens in the direction of the pressure supply connection P and prevents, when the motor-pump unit 4 is shut down, a return flow caused by the load pressure at the pressure supply connection P taking place via the pump 6 and thus a lowering of a raised load via the Pump 6 prevented. A return line 18 leading to the tank 10 is connected to a connection point 16 of the inlet line 12 located between the check valve 14 and the pressure supply connection P. Furthermore, a pressure-limiting valve 20 is connected to the supply line 12 between the pump 6 and the non-return valve 14, which secures the supply line 12 to the return line 18 and thus to the tank 10 against impermissible overpressure and thus also forms a safeguard against lifting excessively heavy loads.

In der an der Verbindungsstelle 16 von der Zulaufleitung 12 abzweigenden Rücklaufleitung 18 sind für über die Rücklaufleitung 18 erfolgende Senkvorgänge angehobener Lasten zwei Senkventile angeordnet. Zum einen handelt es sich um ein Sperrventil 22 in Form eines elektromagnetisch betätigbaren 2/2-Wege-Ventils, das als Haupt-Senkventil die Rücklaufleitung 18 sperrt oder freigibt. Um eine Regelung der Senkgeschwindigkeit zu ermöglichen, ist in der Rücklaufleitung 18 als zweites Senkventil ein Proportionalregelventil 24 geschaltet. Eine zur Ansteuerung des elektromagnetisch betätigbaren Proportionalregelventils 24 in Schieber- oder Sitzausführung vorgesehene elektrische Steuereinheit erhält von einem Druckwertgeber 26 ein Drucksignal, das dem Lastdruck einer jeweiligen Last entspricht, die durch vorausgegangenes Einschalten der Motor-Pumpeneinheit 4 angehoben ist und nach Stillsetzen der Pumpe 6 abgesenkt werden soll. Anhand des vom Druckwertgeber 26 gelieferten Lastdrucksignals und aufgrund von Befehlssignalen, die der betreffende Bediener zur Wahl der Senkgeschwindigkeit eingibt, ist eine feinfühlige Regelung der Senkgeschwindigkeit durch Ansteuern des Proportionalstromregelventils 24 ermöglicht. Durch die Anordnung zweier in Reihe geschalteter Ventile 22 und 24 in der Rücklaufleitung 18 steht eine Redundanz zur Verfügung, die im Falle des Versagens eines der Ventile 22, 24 ein Abstürzen der angehobenen Last verhindert.Two lowering valves are arranged in the return line 18 , which branches off from the supply line 12 at the connection point 16 , for lowering operations of raised loads that take place via the return line 18 . On the one hand, there is a check valve 22 in the form of an electromagnetically actuated 2/2-way valve which, as the main lowering valve, blocks or opens the return line 18 . In order to enable the lowering speed to be regulated, a proportional control valve 24 is connected in the return line 18 as the second lowering valve. An electrical control unit provided for activating the electromagnetically actuable proportional control valve 24 in slide or seat design receives a pressure signal from a pressure transducer 26, which corresponds to the load pressure of a respective load, which has been raised by previously switching on the motor-pump unit 4 and is lowered after the pump 6 has stopped shall be. A sensitive control of the lowering speed by controlling the proportional flow control valve 24 is made possible on the basis of the load pressure signal supplied by the pressure transducer 26 and on the basis of command signals which the relevant operator enters to select the lowering speed. The arrangement of two series-connected valves 22 and 24 in the return line 18 provides redundancy which, in the event of a failure of one of the valves 22, 24, prevents the lifted load from falling.

In Fig. 2, die ein Ausführungsbeispiel der erfindungsgemäßen Schaltungsanordnung zeigt, sind Elemente, die solchen von Fig. 1 funktionsmäßig entsprechen, mit gleichen Bezugszeichen bezeichnet. Die dahingehenden Elemente sind zu der erfindungsgemäßen Lösung nach der Fig. 2 zugehörig. Wie bei Fig. 1 ist eine zum Druckversorgungsventil P führende Zulaufleitung 12 mit der Druckseite der Hydropumpe 6 einer Motor-Pumpeneinheit 4 verbunden, deren Saugseite über ein Saugfilter 8 mit dem Fluid-Vorratstank 10 in Verbindung ist. Als zu versorgende Arbeitseinrichtung ist in Fig. 2 ein Hubzylinder 28 dargestellt, dessen kolbenseitiger Arbeitsraum 30 unmittelbar mit dem Druckversorgungsanschluss P verbunden ist. Die Fig. 2 zeigt auch die in Fig. 1 nicht dargestellte, mit 32 bezeichnete elektrische Steuereinheit. Wie bei Fig. 1 erhält diese ein Lastdrucksignal von dem mit dem Druckversorgungsanschluss P verbundenen Druckwertgeber 26. Zusätzlich erhält die Steuereinheit von einem am Hubzylinder 28 vorgesehenen Wegmesssystem 34 ein Wegsignal, das die Kolbenposition des Hubzylinders 28 darstellt.In 2 , which shows an embodiment of the circuit arrangement according to the invention, are elements that are those of 1 correspond functionally, denoted by the same reference numerals. The pertinent elements are to the solution according to the invention 2 belonging. As in 1 an inlet line 12 leading to the pressure supply valve P is connected to the pressure side of the hydraulic pump 6 of a motor-pump unit 4, the suction side of which is connected to the fluid storage tank 10 via a suction filter 8. The work facility to be supplied is in 2 a lifting cylinder 28 is shown, whose working chamber 30 on the piston side is connected directly to the pressure supply port P. the 2 also shows the in 1 not shown, designated 32 electrical control unit. As in 1 This receives a load pressure signal from the pressure transducer 26 connected to the pressure supply port P. In addition, the control unit receives a displacement signal from a displacement measuring system 34 provided on the lifting cylinder 28, which signal represents the piston position of the lifting cylinder 28.

Anders als bei der bekannten Anordnung von Fig. 1 ist das Sperrventil 22 in die Zulaufleitung 12 in einem Bereich 36 eingeschaltet, der zwischen der Verbindungsstelle 16, an der die Rücklaufleitung 18 abzweigt, und dem Druckversorgungsanschluss P gelegen ist. Das Sperrventil 22 bildet so nicht nur das Haupt-Senkventil, sondern auch ein den Zulauf steuerndes Element. Für den Senkvorgang bildet bei dieser Anordnung der Leitungsabschnitt 36 der Zulaufleitung 12, der zwischen dem Sperrventil 22 und der Verbindungsstelle 16 gelegen ist, den ersten Teil des Rücklaufs 18, dessen zweiter Abschnitt sich an der Verbindungsstelle 16 anschließt und zum Tank 10 führt. In dem an die Verbindungsstelle 16 angeschlossenen Teil befindet sich ein Proportional-Druckbegrenzungsventil 38. Beim Heben der Last sichert es die Zulaufleitung 12 in gleicher Weise wie das Druckbegrenzungsventil 20 der bekannten Anordnung von Fig. 1 gegen unzulässigen Überdruck ab. Als proportional wirkendes, elektromagnetisch betätigbares Ventil übernimmt es in Doppelfunktion gleichzeitig die Regelfunktion des Proportionalventils 24 der bekannten Anordnung.Unlike the known arrangement of 1 the check valve 22 is switched on in the supply line 12 in an area 36 which is located between the connection point 16 at which the return line 18 branches off and the pressure supply port P. The check valve 22 thus forms not only the main lowering valve, but also an element controlling the inflow. In this arrangement, for the lowering process, line section 36 of supply line 12, which is located between check valve 22 and connection point 16, forms the first part of return 18, the second section of which connects to connection point 16 and leads to tank 10. In the part connected to the connection point 16 there is a proportional pressure-relief valve 38. When the load is lifted, it secures the feed line 12 in the same way as the pressure-relief valve 20 of the known arrangement from FIG 1 against impermissible overpressure. As a proportionally acting, electromagnetically actuable valve, it simultaneously takes over the control function of the proportional valve 24 of the known arrangement in a dual function.

Im Betrieb erfolgt das Anheben von Lasten wie beim Stand der Technik durch Betreiben der Hydropumpe 6. Für das Absenken nach Stillsetzen der Pumpe 6 gibt der Bediener die gewünschte Senkgeschwindigkeit über einen Eingabetaster als Sollwertvorgabe in die Steuereinheit 32 ein. Das Sperrventil 22, als Hauptsenkventil, öffnet. Abhängig von der Sollwertvorgabe des Bedieners, dem aus der Last resultierenden, vom Druckwertgeber 26 gemeldeten Druck und der aktuellen, über das Wegmesssystem 34 ermittelten Kolbengeschwindigkeit des Hubzylinders 28, berechnet die Steuereinheit 32 eine Sollwertvorgabe für die Ansteuerung des elektromagnetisch betätigbaren Proportional-Druckbegrenzungsventils 38. Je nach eingesetztem Reglermodul und Parametrierung der Software wird das Proportional-Druckbegrenzungsventil 38 mehr oder weniger geöffnet. Hierfür ist im Regelkreis entsprechend hinterlegt, dass bei zu hoher Senkgeschwindigkeit das Ventil 38 stärker geschlossen und bei zu niedriger Geschwindigkeit mehr geöffnet wird. Bei unterschiedlichen Lasten ist dadurch aufgrund einer Geschwindigkeitseingabe des Bedieners und unabhängig von der Schwere der jeweiligen Last die Senkgeschwindigkeit feinfühlig und stufenlos regelbar. Bei der Anordnung zweier Ventile im Rücklauf, dem Sperrventil 22 und dem Proportional-Druckbegrenzungsventil 38 bleibt die Redundanz im Rücklauf 18 erhalten, so dass auch bei Versagen eines Ventils 22, 38 die Last gegen Abstürzen gesichert ist.During operation, loads are lifted as in the prior art by operating the hydraulic pump 6. For lowering after the pump 6 has stopped, the operator enters the desired lowering speed into the control unit 32 via an input button as a setpoint specification. The check valve 22, as the main lowering valve, opens. The control unit calculates as a function of the operator's setpoint specification, the pressure resulting from the load and reported by the pressure transducer 26 and the current piston speed of the lifting cylinder 28 determined via the position measuring system 34 32 a setpoint specification for the activation of the electromagnetically actuable proportional pressure-limiting valve 38. Depending on the controller module used and the parameterization of the software, the proportional pressure-limiting valve 38 is opened to a greater or lesser extent. For this purpose, it is appropriately stored in the control loop that the valve 38 is closed more when the lowering speed is too high and is opened more when the speed is too low. With different loads, the lowering speed can be sensitively and steplessly regulated based on the speed input by the operator and regardless of the weight of the respective load. With the arrangement of two valves in the return, the check valve 22 and the proportional pressure-limiting valve 38, the redundancy in the return 18 is retained, so that even if one valve 22, 38 fails, the load is secured against falling.

Claims (9)

  1. Circuit arrangement for load-pressure-optimised lowering of loads by means of a fluidically drivable working device (28), in particular in the form of at least one hydraulic working cylinder which can be supplied by a motor-pump unit (4) with a fluid of predefinable pressure in the intake (12) for lifting the respective load, and with a return (18) for discharging fluid from the working device (28) when lowering this load, wherein a proportional pressure-limiting valve (38) is connected in the return (18), said valve performing a dual function in that it serves as a pressure-limiting valve or as a proportional valve during lifting and lowering of the load by means of the hydraulic working device (28), wherein the return (18) with the proportional pressure-limiting valve (38) discharges into a connection point (16) in the intake (12), characterised in that a shut-off valve (22) in the form of a 2/2-way shut-off valve is connected between the connection point (16) and the working device (28).
  2. Circuit arrangement according to claim 1, characterised in that the proportional pressure-limiting valve (38) is electromagnetically controllable and receives its electrical setpoint value from a control system (32) in which a characteristic diagram for this proportional pressure-limiting valve (38) is stored.
  3. Circuit arrangement according to claim 2, characterised in that the control system (32) receives sensor data for further processing as input variables in the form of the current fluid pressure of the working device (28) as a function of its state of movement and in the form of the distance covered as a function of the position of the hydraulic working device (28) or in the form of the speed of movement of this working device (28).
  4. Circuit arrangement according to claim 3, characterised in that the distance or the speed is detected via a displacement (34) or speed measuring system on the hydraulic working device (28) and the current fluid pressure is detected by a pressure value sensor (26) in the direct intake of the working device (28).
  5. Circuit arrangement according to one of claims 2 to 4, characterised in that the control system (32) processes control inputs of an operator as further input variables.
  6. Circuit arrangement according to one of the preceding claims, characterised in that a non-return valve (14), which opens in the direction of the working device (28), is connected between the motor-pump unit (4) and the connection point (16).
  7. Circuit arrangement according to one of the preceding claims, characterised in that the shut-off valve (22) is connected between the connection point (16) and a pressure supply port (P) for the working device (28).
  8. Method for operating a circuit arrangement according to a feature configuration according to one of claims 2 to 5, characterised in that, depending on a setpoint value of the operator, the pressure resulting from the load on the working device (28) and the current speed of the working device (28), the control system (32) calculates a setpoint value for actuating the proportional pressure-limiting valve (38) and in that, depending on the controller module used and parameterisation of the software, the proportional pressure-limiting valve (38) is opened to a greater or lesser extent.
  9. Method according to Claim 8, characterised in that it is stored in the control circuit or the control system (32) respectively that the proportional pressure-limiting valve (38) is closed more when the lowering speed of the working device (28) is too high and is opened more when the speed is too low.
EP19218530.4A 2019-01-12 2019-12-20 Switching assembly Active EP3680493B1 (en)

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DE102020007053A1 (en) 2020-11-19 2022-05-19 Hydac Fluidtechnik Gmbh testing device
DE102021003236A1 (en) 2021-06-23 2022-12-29 Hydac Fluidtechnik Gmbh Method for adapting a control of a proportional valve to its functional operation as part of a fluid system

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US4873817A (en) * 1988-08-01 1989-10-17 United Technologies Automotive, Inc. Electrically controlled pressure relief valve system and method
DE4140409A1 (en) * 1991-12-07 1993-06-09 Robert Bosch Gmbh, 7000 Stuttgart, De ELECTROHYDRAULIC CONTROL DEVICE
DE102007040877A1 (en) * 2007-08-29 2009-03-05 Robert Bosch Gmbh Hoist and method for controlling a hoist
DE102011101553A1 (en) * 2011-05-14 2012-11-15 Robert Bosch Gmbh hoist
DE102012005432A1 (en) * 2012-03-17 2013-09-19 Jungheinrich Aktiengesellschaft Industrial truck for lifting load, has vertical monitoring unit comparing detected pressure values of pressure sensors with each other and generating emergency signal when deviation of pressure values is greater than predetermined value
DE102012011062A1 (en) * 2012-06-04 2013-12-05 Liebherr-France Sas Hydraulic system and pressure relief valve
DE102016205582A1 (en) * 2016-04-05 2017-10-05 Robert Bosch Gmbh Hydraulic drive device with regeneration operation

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