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EP2330304B1 - Hydraulic assembly - Google Patents

Hydraulic assembly Download PDF

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Publication number
EP2330304B1
EP2330304B1 EP09014848A EP09014848A EP2330304B1 EP 2330304 B1 EP2330304 B1 EP 2330304B1 EP 09014848 A EP09014848 A EP 09014848A EP 09014848 A EP09014848 A EP 09014848A EP 2330304 B1 EP2330304 B1 EP 2330304B1
Authority
EP
European Patent Office
Prior art keywords
pressure
pump stage
pressure pump
reservoir
line
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
EP09014848A
Other languages
German (de)
French (fr)
Other versions
EP2330304A1 (en
Inventor
Johann König
Bernd Grabow
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.)
Hawe Hydraulik SE
Original Assignee
Hawe Hydraulik SE
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 Hawe Hydraulik SE filed Critical Hawe Hydraulik SE
Priority to EP09014848A priority Critical patent/EP2330304B1/en
Publication of EP2330304A1 publication Critical patent/EP2330304A1/en
Application granted granted Critical
Publication of EP2330304B1 publication Critical patent/EP2330304B1/en
Not-in-force 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
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/17—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors using two or more pumps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/16—Control arrangements for fluid-driven presses
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B23/00—Pumping installations or systems
    • F04B23/04—Combinations of two or more pumps
    • F04B23/08—Combinations of two or more pumps the pumps being of different types
    • F04B23/10—Combinations of two or more pumps the pumps being of different types at least one pump being of the reciprocating positive-displacement type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B23/00—Pumping installations or systems
    • F04B23/04—Combinations of two or more pumps
    • F04B23/08—Combinations of two or more pumps the pumps being of different types
    • F04B23/12—Combinations of two or more pumps the pumps being of different types at least one pump being of the rotary-piston positive-displacement type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/002—Hydraulic systems to change the pump delivery
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/007—Installations or systems with two or more pumps or pump cylinders, wherein the flow-path through the stages can be changed, e.g. from series to parallel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/08—Regulating by delivery pressure
    • 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
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20538—Type of pump constant capacity
    • 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
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20561—Type of pump reversible
    • 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
    • F15B2211/205—Systems with pumps
    • F15B2211/20576—Systems with pumps with multiple pumps
    • F15B2211/20592—Combinations of pumps for supplying high and low pressure
    • 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
    • F15B2211/265—Control of multiple pressure sources
    • F15B2211/2658—Control of multiple pressure sources by control of the prime movers

Definitions

  • the invention relates to a hydraulic unit according to the preamble of patent claim 1.
  • a hydraulic unit for example, according to EP 1 731 762 A in Kikuiger execution or according to the EP application with the application number EP 09 005 384 ).
  • the flow rates of all pump stages are summarily used, the low-pressure pumping stage of a common electric rotary engine driven pump stages delivers a much higher flow rate than the high-pressure pump stage to quickly perform the rapid traverse can until the predetermined pressure level reached in the pressure line is.
  • the at least one low-pressure pump stage is separated in a pressure-dependent manner from the pressure line and the pressure is built up by the high-pressure pump stage. Since then the low-pressure pump stage continues to work, their flow must be dissipated loss as possible in the reservoir.
  • a circulation valve which conducts the delivery flow as low as possible into the reservoir.
  • the usually provided pressure relief valve which secures the low-pressure pump stage, is unsuitable for the derivation of the flow, because then the low-pressure pump stage would have to constantly promote against the set pressure of the pressure relief valve.
  • Recirculating valves are expensive and require considerable installation space and a special interconnection, since they may only switch to run when the predetermined pressure level is reached.
  • the invention has for its object to provide a hydraulic unit of the type mentioned, in which the task, the flow of at least one low-pressure pump stage to dissipate loss to the reservoir, is solved in a structurally simpler and more cost-effective manner.
  • the structurally simple and inexpensive realizable trick to derive the flow of at least one low-pressure pump stage by a reversal of direction to the reservoir saves the installation and interconnection of a circulation valve for the low-pressure pump stage.
  • the low-pressure pump stage is designed so that it reverses the direction of rotation, the flow with minimal internal losses to the reservoir, ie, with lower flow losses or throttling losses as an optionally provided pressure relief valve for the low-pressure pump stage to an undesirably high mechanical load of the pressure medium or To avoid its inappropriate heating.
  • the high-pressure pump stage is at least one radial or axial piston pump with direction of rotation independent conveying direction
  • the low-pressure pump stage is a reversible gear pump.
  • a reversible gear pump is characterized in that it has opposite directions of rotation, depending on the direction of rotation, wherein it is, suitably connected, such that a conveying direction corresponds to the conveying direction of the high-pressure pump stage to the pressure line, whereas the other conveying direction points to the reservoir.
  • the delivery side and the suction side are reversed, and this effect is used to divert the flow without further aids in the reservoir.
  • a first, in the flow direction to the low-pressure pump stage blocking Provided check valve locks as soon as the predetermined pressure level is reached.
  • a suction line to the reservoir is provided, in which a second, in the flow direction to the reservoir blocking check valve is arranged.
  • the second check valve locks in a rotational direction and with the one conveying direction from the suction line, so that the low-pressure pump stage promotes into the pressure line until the first check valve shuts off. Then or shortly before, the direction of rotation reverses. After that, the low-pressure pump stage sucks in its other conveying direction via the suction line and then opened second check valve from the reservoir and their flow is pumped back into the reservoir.
  • the opening pressure of the second check valve, the flow resistance in the suction line and the promotion in the other direction of the low pressure pump stage are chosen so that the flow is dissipated loss.
  • the low-pressure pump stage is secured in a conveying direction to the pressure line by a first pressure relief valve.
  • this pressure relief valve is associated with the low pressure pump stage as an option to prevent damage to the low pressure pump stage due to a surge, e.g. in a collision, counteract.
  • all pump stages are driven simultaneously by a common reversible electric motor.
  • the electric motor is controlled in one direction of rotation until the predetermined pressure level in the pressure line is reached or a device operated by the hydraulic unit has carried out a rapid stroke with low pressure. Then, the direction of rotation of the electric motor and thus the pump stages is reversed, whereupon only promotes the high-pressure pump stage in the pressure line, whereas the low-pressure pump stage directs their flow into the reservoir.
  • a separate electric motor is provided for at least one pump stage, preferably the high-pressure pump stage.
  • the low-pressure pump stage or multiple low-pressure pump stages may be driven by one or more electric motors, with all electric motors running permanently, and only the one or more electric motors of the low-pressure pump stage (s) being reversed in the direction of rotation.
  • the electric motor and the pump stages are arranged in a housing forming the reservoir, preferably including the suction line with the second check valve and the pressure line led to an outside of the housing.
  • a valve device may be mounted, which includes at least the first check valve and the first pressure relief valve.
  • the valve device has a connection block with pressure and reservoir connections (for connecting a consumer) and a second pressure-limiting valve monitoring the high-pressure pump stage.
  • This terminal block can be mounted on the outside of the housing via an intermediate plate. The intermediate plate may then have the first check valve and the first pressure relief valve.
  • a reversible electric motor having a rated power of about 0.5 kW to 1.0 kW is used, and the pump stages are designed so that the specific delivery flows of the high pressure and low pressure pump stages in a ratio of about 1: 5 until 1: 10 stand.
  • an electric motor control for the electric motor which is connected for correct reversal of direction with a signal generator, which supplies the signal for reversing the direction of rotation.
  • a signal generator which supplies the signal for reversing the direction of rotation.
  • This may, preferably, be an Eilhub position sensor of a hydraulic power operated by the hydraulic unit, such as a press, and / or a pressure sensor responsive to the pressure conditions, for example in the pressure line, and / or a response sensor of the first pressure relief valve or the first check valve ,
  • Fig. 1 illustrates an embodiment of a hydraulic unit A based on a block diagram, wherein the embodiment of the hydraulic unit A two pump stages 4, 5 and a common, both pump stages 4, 5 driving electric motor 6 contains.
  • the pump stages are a high-pressure pump stage 4 and a low-pressure pump stage 5, wherein the high-pressure pump stage 4 can be formed by at least one radial piston or axial piston pump, which supplies a flow independently of the direction of rotation in a single conveying direction.
  • the low-pressure pump stage 5 may be at least one reversible gear pump, which operates in a direction-dependent manner with opposite conveying directions.
  • more than two pump stages could be provided and could have at least one pump stage own electric motor as a drive source, which is operated simultaneously with at least one further electric motor for driving the other pump stage or pump stages.
  • the hydraulic unit A points in Fig. 1 three sections 1, 2, 3, wherein the section 1 may for example be a terminal block, the section 2, for example, an intermediate plate, and the section 3 a in Fig. 1 not shown housing (housing 26 in Fig. 2 ) with components housed in this housing.
  • the hydraulic unit A is a so-called motor pump unit, in which the electric motor and the pump stages in a reservoir-forming housing 26 (FIG. Fig. 2 ) are housed while the sections 1, 2 are mounted on the outside of the housing 26.
  • the electric motor and the pump stages could be arranged in other containers or independently outside of a container.
  • the electric motor 6 is, for example, a three-phase motor operated with alternating current with a rated power of between about 0.5 kW and 1.0 kW, suitably a so-called sub-oil engine, which can run in open form in the container 26 in the pressure medium and cooled by this becomes.
  • the high-pressure pump stage 4 can be designed so that it can build up a maximum pressure of up to 580 bar, for example, while delivering a specific flow rate of about 1 cm 3 per revolution.
  • the low-pressure stage for example, generates a specific flow rate of about 8 cm 3 per revolution, wherein the electric motor 6 is running at a speed of between about 1360 and 1650 revolutions per minute, depending on the voltage and the frequency of the alternating current.
  • these are only non-limiting examples of the design of the hydraulic unit.
  • Fig. 1 is the high-pressure and low-pressure pump stages 4, 5 associated with a common reservoir R.
  • a, preferably electronic or computerized, engine control 7 is provided, which receives a signal i to reverse the direction of rotation of a signal generator 8, which is representative, for example, that a certain pressure level has been reached or a powered consumer has performed a particular stroke.
  • the high-pressure pump stage 4 is connected on the delivery side to a pressure line 9, which leads to a pressure line connection 24 of the section 1.
  • a line branches off to a connection 11 of the section 2 (optional), at which the pressure in the pressure line 9 can be measured (pressure gauge).
  • a line 12 is connected, from which leads at a node 13, a connecting line 14 to the node 10 in the pressure line 9.
  • a first check valve 15 is included, which blocks in the flow direction to the low-pressure pump stage.
  • From the node 13 also branches off a line to a port 16 of the section 2 from (optional), at which the pressure in the line 12 is verifiable or measurable (manometer).
  • a pressure switch for example, the signal i delivers.
  • a first pressure relief valve 17 is included, the response pressure, preferably, is adjustable, and which secures the low-pressure pump stage 5.
  • the reservoir line 23 branches off from the pressure line 9 and contains a second pressure relief valve 18, whose response pressure, preferably adjustable, and which secures the high-pressure pump stage 4.
  • the reservoir line 23 is further connected to the reservoir port 25 in the section 1.
  • a suction line 19 is installed, in which a second check valve 21 is included, which blocks in the flow direction to the reservoir.
  • a leakage line 22 lead into the reservoir R.
  • the sections 1, 2, ie the terminal block as section 1 and an intermediate plate as the section 2, are mounted on the outside of the housing 26, more precisely on a terminal base 27 of the housing 26 containing the pressure means.
  • the terminal block 1 for example, the terminals 24, 25 (in Fig. 2 not highlighted).
  • settings 28, 29, for example, for the response pressure of the first and second pressure relief valves 17, 18 can be seen.
  • the electric motor 6 is driven in a first direction of rotation, in which the conveying direction of the low-pressure pump stage 5 to the pressure line 9 points.
  • the high-pressure pump stage 4 and the low-pressure pump stage 5 jointly promote in the pressure line 9, wherein the first check valve 15 is open and the first and second pressure relief valves 17, 18 and the second check valve 21 shut off.
  • Both pump stages 4, 5 suck from the reservoir R, wherein the flow the low-pressure pump stage 5 holds the second check valve 21 in the blocking position.
  • the electric motor 6 is reversed in its direction of rotation.
  • the first check valve 15 goes into the blocking position and separates the low-pressure pump stage 5 from the pressure line 9.
  • the high-pressure pump stage 4 further promotes in the same direction in the pressure line 9 to build there even higher pressure, while the low-pressure pump stage 5 now sucked in reverse flow direction via the suction line 19 and the opened second check valve 21 and directly into the reservoir R promotes.
  • the first pressure relief valve 17 may for example be set to a response pressure of 50 bar, the second pressure relief valve 18, however, to a response pressure of 410 bar.
  • the electric motor 6 can be turned off.
  • the motor controller 7 drives the electric motor 6 again in the first direction of rotation, with which both pump stages 4, 5 jointly convey into the pressure line 9.

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

Description

Die Erfindung betrifft ein Hydraulikaggregat gemäß dem Oberbegriff des Patentanspruchs 1.The invention relates to a hydraulic unit according to the preamble of patent claim 1.

Beispielsweise zur Pressensteuerung kann es erforderlich sein, eine Pressplatte im Eilgang mit moderatem Druck und großer Fördermenge zu verstellen, und anschließend einen Presstakt mit wesentlich höherem Pressdruck auszuführen. Unter anderem für solche Anforderungen ist es bekannt, ein Hydraulikaggregat (beispielsweise gemäß EP 1 731 762 A in mehrkreisiger Ausführung oder gemäß der EP-Anmeldung mit der Anmeldungsnummer EP 09 005 384 ) einzusetzen. Für den Eilgang werden die Förderströme aller Pumpenstufen summarisch eingesetzt, wobei die Niederdruck-Pumpenstufe der von einem gemeinsamen Elektromotor drehangetriebenen Pumpenstufen einen wesentlich höheren Förderstrom liefert als die Hochdruck-Pumpenstufe, um den Eilgang zügig durchführen zu können, bis das vorbestimmte Druckniveau in der Druckleitung erreicht ist. Dann wird die zumindest eine Niederdruck-Pumpenstufe druckabhängig von der Druckleitung separiert und wird der Pressdruck von der Hochdruck-Pumpenstufe aufgebaut. Da dann die Niederdruck-Pumpenstufe weiterhin arbeitet, muss ihr Förderstrom möglichst verlustarm in das Reservoir abgeleitet werden. Hierzu ist es bekannt, der Niederdruck-Pumpenstufe ein Umlaufventil zuzuordnen, das den Förderstrom möglichst verlustarm in das Reservoir leitet. Das üblicherweise vorgesehene Druckbegrenzungsventil, das die Niederdruck-Pumpenstufe absichert, ist für das Ableiten des Förderstromes ungeeignet, weil dann die Niederdruck-Pumpenstufe ständig gegen den Ansprechdruck des Druckbegrenzungsventils fördern müsste. Umlaufventile sind jedoch teuer und benötigen nennenswerten Einbauraum und eine spezielle Verschaltung, da sie erst auf Durchlauf schalten dürfen, wenn das vorbestimmte Druckniveau erreicht ist.For example, for press control, it may be necessary to adjust a press plate at rapid speed with moderate pressure and high flow rate, and then perform a press cycle with much higher pressure. Among other things, for such requirements, it is known, a hydraulic unit (for example, according to EP 1 731 762 A in mehrkreisiger execution or according to the EP application with the application number EP 09 005 384 ). For rapid traverse, the flow rates of all pump stages are summarily used, the low-pressure pumping stage of a common electric rotary engine driven pump stages delivers a much higher flow rate than the high-pressure pump stage to quickly perform the rapid traverse can until the predetermined pressure level reached in the pressure line is. Then, the at least one low-pressure pump stage is separated in a pressure-dependent manner from the pressure line and the pressure is built up by the high-pressure pump stage. Since then the low-pressure pump stage continues to work, their flow must be dissipated loss as possible in the reservoir. For this purpose, it is known to associate the low-pressure pump stage with a circulation valve, which conducts the delivery flow as low as possible into the reservoir. The usually provided pressure relief valve, which secures the low-pressure pump stage, is unsuitable for the derivation of the flow, because then the low-pressure pump stage would have to constantly promote against the set pressure of the pressure relief valve. Recirculating valves are expensive and require considerable installation space and a special interconnection, since they may only switch to run when the predetermined pressure level is reached.

Weiterer Stand der Technik ist enthalten in GB 2 070 693 A , JP 01 087884 A , US 4 008 571 A und JP 2005 090351 A .Further prior art is contained in GB 2 070 693 A . JP 01 087884 A . US 4,008,571 A and JP 2005 090351 A ,

Der Erfindung liegt die Aufgabe zugrunde, ein Hydraulikaggregat der eingangs genannten Art anzugeben, bei dem die Aufgabe, den Förderstrom zumindest einer Niederdruck-Pumpenstufe zum Reservoir verlustarm abzuleiten, auf baulich einfachere und kostengünstigere Weise gelöst ist.The invention has for its object to provide a hydraulic unit of the type mentioned, in which the task, the flow of at least one low-pressure pump stage to dissipate loss to the reservoir, is solved in a structurally simpler and more cost-effective manner.

Die gestellte Aufgabe wird mit den Merkmalen des Patentanspruchs 1 gelöst.The stated object is achieved with the features of claim 1.

Der baulich einfache und kostengünstig realisierbare Kunstgriff, den Förderstrom der zumindest einen Niederdruck-Pumpenstufe durch eine Drehrichtungsumkehr zum Reservoir abzuleiten, erspart den Einbau und die Verschaltung eines Umlaufventils für die Niederdruck-Pumpenstufe. Dabei ist die Niederdruck-Pumpenstufe so ausgebildet, dass sie bei Drehrichtungsumkehr den Förderstrom mit minimalen inneren Verlusten zum Reservoir leitet, d.h., mit geringeren Strömungsverlusten oder Drosselungsverlusten als ein gegebenenfalls vorgesehenes Druckbegrenzungsventil für die Niederdruck-Pumpenstufe, um eine unerwünscht hohe mechanische Belastung des Druckmittels bzw. dessen unzweckmäßige Erwärmung zu vermeiden.The structurally simple and inexpensive realizable trick to derive the flow of at least one low-pressure pump stage by a reversal of direction to the reservoir, saves the installation and interconnection of a circulation valve for the low-pressure pump stage. In this case, the low-pressure pump stage is designed so that it reverses the direction of rotation, the flow with minimal internal losses to the reservoir, ie, with lower flow losses or throttling losses as an optionally provided pressure relief valve for the low-pressure pump stage to an undesirably high mechanical load of the pressure medium or To avoid its inappropriate heating.

Bei einer zweckmäßigen Ausführungsform ist der die Pumpenstufen gemeinsam drehantreibende Elektromotor reversibel, ist die Hochdruck-Pumpenstufe wenigstens eine Radial-oder eine Axialkolbenpumpe mit drehrichtungsunabhängiger Förderrichtung, und ist die Niederdruck-Pumpenstufe eine reversible Zahnradpumpe. Eine reversible Zahnradpumpe zeichnet sich dadurch aus, dass sie drehrichtungsabhängig entgegengesetzte Förderrichtungen hat, wobei sie, zweckmäßig, so verschaltet ist, dass eine Förderrichtung der Förderrichtung der Hochdruck-Pumpenstufe zur Druckleitung entspricht, hingegen die andere Förderrichtung zum Reservoir weist. In anderen Worten, werden bei einer reversiblen Zahnradpumpe bei Drehrichtungsumkehr die Förderseite und die Saugseite vertauscht, und wird dieser Effekt benutzt, um den Förderstrom ohne weitere Hilfsmittel ins Reservoir abzuleiten.In an expedient embodiment of the pump stages together rotatably driving electric motor is reversible, the high-pressure pump stage is at least one radial or axial piston pump with direction of rotation independent conveying direction, and the low-pressure pump stage is a reversible gear pump. A reversible gear pump is characterized in that it has opposite directions of rotation, depending on the direction of rotation, wherein it is, suitably connected, such that a conveying direction corresponds to the conveying direction of the high-pressure pump stage to the pressure line, whereas the other conveying direction points to the reservoir. In other words, in a reversible gear pump in direction of rotation reversal, the delivery side and the suction side are reversed, and this effect is used to divert the flow without further aids in the reservoir.

Bei einer zweckmäßigen Ausführungsform ist zum Separieren der jeweiligen Niederdruck-Pumpenstufe von der Druckleitung, sobald das vorbestimmte Druckniveau in der Druckleitung erreicht ist, zwischen gleichsinnigen Förderseiten der Hochdruck-Pumpenstufe und der zumindest eine Niederdruck-Pumpenstufe ein erstes, in Strömungsrichtung zur Niederdruck-Pumpenstufe sperrendes Rückschlagventil vorgesehen. Das erste Rückschlagventil sperrt, sobald das vorbestimmte Druckniveau erreicht ist. Ferner ist zum Ableiten des Förderstroms der jeweiligen Niederdruck-Pumpenstufe zum Reservoir zwischen dem ersten Rückschlagventil und der Niederdruck-Pumpenstufe eine Saugleitung zum Reservoir vorgesehen, in der ein zweites, in Strömungsrichtung zum Reservoir sperrendes Rückschlagventil angeordnet ist. Bei Verwendung der reversiblen Zahnradpumpe sperrt das zweite Rückschlagventil in einer Drehrichtung und mit der einen Förderrichtung die Saugleitung ab, so dass die Niederdruck-Pumpenstufe in die Druckleitung fördert, bis das erste Rückschlagventil absperrt. Dann oder kurz davor erfolgt die Drehrichtungsumkehr. Danach saugt die Niederdruck-Pumpenstufe in ihrer anderen Förderrichtung über die Saugleitung und das dann geöffnete zweite Rückschlagventil aus dem Reservoir an und wird ihr Förderstrom zurück in das Reservoir gepumpt. Der Öffnungsdruck des zweiten Rückschlagventils, der Strömungswiderstand in der Saugleitung und die Förderung in der anderen Förderrichtung der Niederdruck-Pumpenstufe werden so gewählt, dass der Förderstrom verlustarm abgeleitet wird.In an expedient embodiment, for separating the respective low-pressure pump stage from the pressure line, as soon as the predetermined pressure level in the pressure line is reached, between the same-direction delivery sides of the high-pressure pump stage and the at least one low-pressure pump stage a first, in the flow direction to the low-pressure pump stage blocking Provided check valve. The first check valve locks as soon as the predetermined pressure level is reached. Further, for deriving the flow of the respective low-pressure pump stage to the reservoir between the first check valve and the low-pressure pump stage, a suction line to the reservoir is provided, in which a second, in the flow direction to the reservoir blocking check valve is arranged. When using the reversible gear pump, the second check valve locks in a rotational direction and with the one conveying direction from the suction line, so that the low-pressure pump stage promotes into the pressure line until the first check valve shuts off. Then or shortly before, the direction of rotation reverses. After that, the low-pressure pump stage sucks in its other conveying direction via the suction line and then opened second check valve from the reservoir and their flow is pumped back into the reservoir. The opening pressure of the second check valve, the flow resistance in the suction line and the promotion in the other direction of the low pressure pump stage are chosen so that the flow is dissipated loss.

Bei einer zweckmäßigen Ausführungsform ist die Niederdruck-Pumpenstufe in der einen Förderrichtung zur Druckleitung durch ein erstes Druckbegrenzungsventil abgesichert. Dieses Druckbegrenzungsventil ist als Option sicherheitshalber der Niederdruck-Pumpenstufe zugeordnet, um einer Beschädigung der Niederdruck-Pumpenstufe aufgrund eines Druckstoßes, z.B. bei einer Kollision, entgegenzuwirken.In an advantageous embodiment, the low-pressure pump stage is secured in a conveying direction to the pressure line by a first pressure relief valve. As an option, this pressure relief valve is associated with the low pressure pump stage as an option to prevent damage to the low pressure pump stage due to a surge, e.g. in a collision, counteract.

Bei einer zweckmäßigen Ausführungsform werden alle Pumpenstufen von einem gemeinsamen reversiblen Elektromotor gleichzeitig angetrieben. Der Elektromotor wird in einer Drehrichtung gesteuert, bis das vorbestimmte Druckniveau in der Druckleitung erreicht ist oder eine mit dem Hydraulikaggregat betriebene Einrichtung einen raschen Hub mit geringem Druck ausgeführt hat. Dann wird die Drehrichtung des Elektromotors und damit der Pumpenstufen umgekehrt, worauf nur noch die Hochdruck-Pumpenstufe in die Druckleitung fördert, hingegen die Niederdruck-Pumpenstufe ihren Förderstrom in das Reservoir leitet.In an expedient embodiment, all pump stages are driven simultaneously by a common reversible electric motor. The electric motor is controlled in one direction of rotation until the predetermined pressure level in the pressure line is reached or a device operated by the hydraulic unit has carried out a rapid stroke with low pressure. Then, the direction of rotation of the electric motor and thus the pump stages is reversed, whereupon only promotes the high-pressure pump stage in the pressure line, whereas the low-pressure pump stage directs their flow into the reservoir.

Bei einer anderen Ausführungsform ist zumindest für eine Pumpenstufe, vorzugsweise die Hochdruck-Pumpenstufe, ein eigener Elektromotor vorgesehen. Die Niederdruck-Pumpenstufe oder mehrere Niederdruck-Pumpenstufen können durch einen oder mehrere Elektromotoren angetrieben werden, wobei alle Elektromotoren permanent laufen, und nur der oder die Elektromotoren der Niederdruck-Pumpenstufe(n) in der Drehrichtung umgesteuert werden.In another embodiment, a separate electric motor is provided for at least one pump stage, preferably the high-pressure pump stage. The low-pressure pump stage or multiple low-pressure pump stages may be driven by one or more electric motors, with all electric motors running permanently, and only the one or more electric motors of the low-pressure pump stage (s) being reversed in the direction of rotation.

Bei einer zweckmäßigen Ausführungsform des Hydraulikaggregats sind der Elektromotor und die Pumpenstufen in einem das Reservoir bildenden Gehäuse angeordnet, vorzugsweise einschließlich der Saugleitung mit dem zweiten Rückschlagventil und der zu einer Außenseite des Gehäuses geführten Druckleitung. An der Außenseite des Gehäuses kann eine Ventileinrichtung montiert sein, die zumindest das erste Rückschlagventil und das erste Druckbegrenzungsventil enthält. Diese gegebenenfalls Wartung, Überprüfung oder Einstellungen erfordernden Komponenten der Ventileinrichtung sind somit von außen gut zugänglich.In an expedient embodiment of the hydraulic unit, the electric motor and the pump stages are arranged in a housing forming the reservoir, preferably including the suction line with the second check valve and the pressure line led to an outside of the housing. On the outside of the housing, a valve device may be mounted, which includes at least the first check valve and the first pressure relief valve. These optionally maintenance, inspection or settings requiring components of the valve device are thus easily accessible from the outside.

Bei einer weiteren, zweckmäßigen Ausführungsform weist die Ventileinrichtung einen Anschlussblock mit Druck- und Reservoiranschlüssen (zum Anschließen eines Verbrauchers) und einem zweiten, die Hochdruck-Pumpenstufe überwachenden Druckbegrenzungsventil auf. Dieser Anschlussblock kann über eine Zwischenplatte an der Außenseite des Gehäuses montiert sein. Die Zwischenplatte kann dann das erste Rückschlagventil und das erste Druckbegrenzungsventil aufweisen.In a further expedient embodiment, the valve device has a connection block with pressure and reservoir connections (for connecting a consumer) and a second pressure-limiting valve monitoring the high-pressure pump stage. This terminal block can be mounted on the outside of the housing via an intermediate plate. The intermediate plate may then have the first check valve and the first pressure relief valve.

Bei einer Ausführungsform wird ein reversibler Elektromotor mit einer Nennleistung von etwa 0,5 kW bis 1,0 kW verwendet, und sind die Pumpenstufen so ausgelegt, dass die spezifischen Förderströme der Hochdruck- und der Niederdruck-Pumpenstufen in einem Verhältnis von etwa 1 : 5 bis 1 : 10 stehen.In one embodiment, a reversible electric motor having a rated power of about 0.5 kW to 1.0 kW is used, and the pump stages are designed so that the specific delivery flows of the high pressure and low pressure pump stages in a ratio of about 1: 5 until 1: 10 stand.

Schließlich ist es zweckmäßig, eine elektrische Motorsteuerung für den Elektromotor vorzusehen, die zur korrekten Drehrichtungsumkehr mit einem Signalgeber verbunden ist, der das Signal zur Drehrichtungsumkehr liefert. Dies kann, vorzugsweise, ein Eilhub-Positionsfühler eines mittels des Hydraulikaggregats betätigten Hydraulikverbrauchers, wie einer Presse, sein, und/oder ein Drucksensor, der auf die Druckverhältnisse beispielsweise in der Druckleitung anspricht, und/oder ein Ansprechsensor des ersten Druckbegrenzungsventils oder des ersten Rückschlagventils.Finally, it is expedient to provide an electric motor control for the electric motor, which is connected for correct reversal of direction with a signal generator, which supplies the signal for reversing the direction of rotation. This may, preferably, be an Eilhub position sensor of a hydraulic power operated by the hydraulic unit, such as a press, and / or a pressure sensor responsive to the pressure conditions, for example in the pressure line, and / or a response sensor of the first pressure relief valve or the first check valve ,

Anhand der Zeichnungen wird eine Ausführungsform des Erfindungsgegenstandes erläutert. Es zeigen:

Fig. 1
ein Blockschaltbild eines Hydraulikaggregats, und
Fig. 2
eine Frontansicht eines konkreten Ausführungsbeispiels eines Hydraulikaggregats in Betriebslage.
With reference to the drawings, an embodiment of the subject invention will be explained. Show it:
Fig. 1
a block diagram of a hydraulic unit, and
Fig. 2
a front view of a concrete embodiment of a hydraulic unit in the operating position.

Fig. 1 verdeutlicht eine Ausführungsform eines Hydraulikaggregats A anhand eines Blockschaltbildes, wobei die Ausführungsform des Hydraulikaggregats A zwei Pumpenstufen 4, 5 und einen gemeinsamen, beide Pumpenstufen 4, 5 antreibenden Elektromotor 6 enthält. Bei den Pumpenstufen handelt es sich um eine Hochdruck-Pumpenstufe 4 und um eine Niederdruck-Pumpenstufe 5, wobei die Hochdruck-Pumpenstufe 4 durch wenigstens eine Radialkolben- oder Axialkolbenpumpe gebildet sein kann, die drehrichtungsunabhängig in einer einzigen Förderrichtung einen Förderstrom liefert. Die Niederdruck-Pumpenstufe 5 kann wenigstens eine reversible Zahnradpumpe sein, die drehrichtungsabhängig mit entgegengesetzten Förderrichtungen arbeitet. Fig. 1 illustrates an embodiment of a hydraulic unit A based on a block diagram, wherein the embodiment of the hydraulic unit A two pump stages 4, 5 and a common, both pump stages 4, 5 driving electric motor 6 contains. The pump stages are a high-pressure pump stage 4 and a low-pressure pump stage 5, wherein the high-pressure pump stage 4 can be formed by at least one radial piston or axial piston pump, which supplies a flow independently of the direction of rotation in a single conveying direction. The low-pressure pump stage 5 may be at least one reversible gear pump, which operates in a direction-dependent manner with opposite conveying directions.

Bei nicht gezeigten Alternativen des Hydraulikaggregats könnten auch mehr als nur zwei Pumpenstufen vorgesehen sein und könnte zumindest eine Pumpenstufe einen eigenen Elektromotor als Antriebsquelle haben, der gleichzeitig mit zumindest wenigstens einen weiteren Elektromotor zum Antreiben der weiteren Pumpenstufe oder Pumpenstufen betrieben wird.In not shown alternatives of the hydraulic unit also more than two pump stages could be provided and could have at least one pump stage own electric motor as a drive source, which is operated simultaneously with at least one further electric motor for driving the other pump stage or pump stages.

Das Hydraulikaggregat A weist in Fig. 1 drei Sektionen 1, 2, 3 auf, wobei die Sektion 1 beispielsweise ein Anschlussblock sein kann, die Sektion 2 beispielsweise eine Zwischenplatte, und die Sektion 3 ein in Fig. 1 nicht gezeigtes Gehäuse (Gehäuse 26 in Fig. 2) mit in diesem Gehäuse untergebrachten Komponenten repräsentieren kann.The hydraulic unit A points in Fig. 1 three sections 1, 2, 3, wherein the section 1 may for example be a terminal block, the section 2, for example, an intermediate plate, and the section 3 a in Fig. 1 not shown housing (housing 26 in Fig. 2 ) with components housed in this housing.

Konkreter handelt es sich bei dem Hydraulikaggregat A um ein sogenanntes Motorpumpenaggregat, in welchem der Elektromotor und die Pumpenstufen in einem das Reservoir bildenden Gehäuse 26 (Fig. 2) untergebracht sind, während die Sektionen 1, 2 an der Außenseite des Gehäuses 26 montiert sind. Bei nicht gezeigten Alternativen könnten der Elektromotor und die Pumpenstufen in anderen Behältern oder eigenständig außerhalb eines Behälters angeordnet sein.More specifically, the hydraulic unit A is a so-called motor pump unit, in which the electric motor and the pump stages in a reservoir-forming housing 26 (FIG. Fig. 2 ) are housed while the sections 1, 2 are mounted on the outside of the housing 26. In alternatives not shown, the electric motor and the pump stages could be arranged in other containers or independently outside of a container.

Bei einer Ausführungsform ist der Elektromotor 6 z.B. ein mit Wechselstrom betriebener dreiphasiger Motor mit einer Nennleistung zwischen etwa 0,5 kW und 1,0 kW, zweckmäßig ein sogenannter Unterölmotor, der in offener Bauweise in dem Behälter 26 im Druckmittel laufen kann und von diesem gekühlt wird. Die Hochdruck-Pumpenstufe 4 kann so ausgelegt sein, dass sie einen Maximaldruck bis zu 580 bar aufbauen kann, und dabei beispielsweise einen spezifischen Förderstrom von etwa 1 cm3 pro Umdrehung liefert. Die Niederdruckstufe erzeugt beispielsweise einen spezifischen Förderstrom von etwa 8 cm3 pro Umdrehung, wobei der Elektromotor 6 mit einer Drehzahl zwischen etwa 1360 und 1650 Umdrehungen pro Minute läuft, abhängig von der Spannung und der Frequenz des Wechselstroms. Dies sind jedoch nur nicht beschränkende Beispiele zur Auslegung des Hydraulikaggregats.In one embodiment, the electric motor 6 is, for example, a three-phase motor operated with alternating current with a rated power of between about 0.5 kW and 1.0 kW, suitably a so-called sub-oil engine, which can run in open form in the container 26 in the pressure medium and cooled by this becomes. The high-pressure pump stage 4 can be designed so that it can build up a maximum pressure of up to 580 bar, for example, while delivering a specific flow rate of about 1 cm 3 per revolution. The low-pressure stage, for example, generates a specific flow rate of about 8 cm 3 per revolution, wherein the electric motor 6 is running at a speed of between about 1360 and 1650 revolutions per minute, depending on the voltage and the frequency of the alternating current. However, these are only non-limiting examples of the design of the hydraulic unit.

Gemäß Fig. 1 ist den Hochdruck- und Niederdruck-Pumpenstufen 4, 5 ein gemeinsames Reservoir R zugeordnet. Für den Elektromotor 6 ist eine, vorzugsweise elektronische oder computerisierte, Motorsteuerung 7 vorgesehen, die zur Drehrichtungsumkehr von einem Signalgeber 8 ein Signal i erhält, das z.B. repräsentativ dafür ist, dass ein bestimmtes Druckniveau erreicht wurde oder ein betriebener Verbraucher einen bestimmten Hub ausgeführt hat.According to Fig. 1 is the high-pressure and low-pressure pump stages 4, 5 associated with a common reservoir R. For the electric motor 6, a, preferably electronic or computerized, engine control 7 is provided, which receives a signal i to reverse the direction of rotation of a signal generator 8, which is representative, for example, that a certain pressure level has been reached or a powered consumer has performed a particular stroke.

Die Hochdruck-Pumpenstufe 4 ist förderseitig mit einer Druckleitung 9 verbunden, die zu einem Druckleitungsanschluss 24 der Sektion 1 führt. An einem Knoten 10 der Druckleitung 9 zweigt eine Leitung zu einem Anschluss 11 der Sektion 2 ab (optional), an welchem der Druck in der Druckleitung 9 messbar ist (Manometer). An die Niederdruck-Pumpenstufe 5 ist eine Leitung 12 angeschlossen, von der an einem Knoten 13 eine Verbindungsleitung 14 zu dem Knoten 10 in der Druckleitung 9 führt. In der Verbindungsleitung 14 ist ein erstes Rückschlagventil 15 enthalten, das in Strömungsrichtung zur Niederdruck-Pumpenstufe sperrt. Vom Knoten 13 zweigt auch eine Leitung zu einem Anschluss 16 der Sektion 2 ab (optional), an welchem der Druck in der Leitung 12 überprüfbar oder messbar ist (Manometer). Bei einer nicht gezeigten Alternative könnten am Anschluss 11 oder am Anschluss 16 ein Druckschalter angeschlossen sein, der beispielsweise das Signal i liefert.The high-pressure pump stage 4 is connected on the delivery side to a pressure line 9, which leads to a pressure line connection 24 of the section 1. At a node 10 of the pressure line 9, a line branches off to a connection 11 of the section 2 (optional), at which the pressure in the pressure line 9 can be measured (pressure gauge). To the low-pressure pump stage 5, a line 12 is connected, from which leads at a node 13, a connecting line 14 to the node 10 in the pressure line 9. In the connecting line 14, a first check valve 15 is included, which blocks in the flow direction to the low-pressure pump stage. From the node 13 also branches off a line to a port 16 of the section 2 from (optional), at which the pressure in the line 12 is verifiable or measurable (manometer). In an alternative, not shown, could be connected to the terminal 11 or the terminal 16, a pressure switch, for example, the signal i delivers.

In der Leitung 12, die zu einer Reservoirleitung 23 führt, ist ein erstes Druckbegrenzungsventil 17 enthalten, dessen Ansprechdruck, vorzugsweise, verstellbar ist, und das die Niederdruck-Pumpenstufe 5 absichert. Die Reservoirleitung 23 zweigt von der Druckleitung 9 ab und enthält ein zweites Druckbegrenzungsventil 18, dessen Ansprechdruck, vorzugsweise einstellbar ist, und das die Hochdruck-Pumpenstufe 4 absichert. Die Reservoirleitung 23 ist ferner mit dem Reservoiranschluss 25 in der Sektion 1 verbunden. Zwischen einem Knoten 20 in der Leitung 12 und dem Reservoir R ist eine Saugleitung 19 installiert, in der ein zweites Rückschlagventil 21 enthalten ist, das in Strömungsrichtung zum Reservoir sperrt. Schließlich kann, optional, von der Niederdruck-Pumpenstufe 5 eine Leckageleitung 22 in das Reservoir R führen.In line 12, which leads to a reservoir line 23, a first pressure relief valve 17 is included, the response pressure, preferably, is adjustable, and which secures the low-pressure pump stage 5. The reservoir line 23 branches off from the pressure line 9 and contains a second pressure relief valve 18, whose response pressure, preferably adjustable, and which secures the high-pressure pump stage 4. The reservoir line 23 is further connected to the reservoir port 25 in the section 1. Between a node 20 in the conduit 12 and the reservoir R, a suction line 19 is installed, in which a second check valve 21 is included, which blocks in the flow direction to the reservoir. Finally, optionally, from the low-pressure pump stage 5, a leakage line 22 lead into the reservoir R.

Gemäß Fig. 2 sind die Sektionen 1, 2, d.h. der Anschlussblock als Sektion 1 und eine Zwischenplatte als die Sektion 2, an der Außenseite des Gehäuses 26 montiert, genauer an einem Anschlusssockel 27 des Gehäuses 26, das das Druckmittel enthält. An dem Anschlussblock 1 sind beispielsweise die Anschlüsse 24, 25 (in Fig. 2 nicht näher hervorgehoben) platziert. Ferner sind Einstellmöglichkeiten 28, 29 beispielsweise für den Ansprechdruck der ersten und zweiten Druckbegrenzungsventile 17, 18 erkennbar.According to Fig. 2 For example, the sections 1, 2, ie the terminal block as section 1 and an intermediate plate as the section 2, are mounted on the outside of the housing 26, more precisely on a terminal base 27 of the housing 26 containing the pressure means. At the terminal block 1, for example, the terminals 24, 25 (in Fig. 2 not highlighted). Furthermore, settings 28, 29, for example, for the response pressure of the first and second pressure relief valves 17, 18 can be seen.

Wird das Hydraulikaggregat A in Betrieb genommen, wird der Elektromotor 6 in einer ersten Drehrichtung angetrieben, in der die Förderrichtung der Niederdruck-Pumpenstufe 5 zur Druckleitung 9 weist. Die Hochdruck-Pumpenstufe 4 und die Niederdruck-Pumpenstufe 5 fördern gemeinsam in die Druckleitung 9, wobei das erste Rückschlagventil 15 offen ist und die ersten und zweiten Druckbegrenzungsventile 17, 18 und das zweite Rückschlagventil 21 absperren. Beide Pumpenstufen 4, 5 saugen aus dem Reservoir R an, wobei der Förderstrom der Niederdruck-Pumpenstufe 5 das zweite Rückschlagventil 21 in Sperrstellung hält. Sobald das vorbestimmte Druckniveau in der Druckleitung 9 erreicht ist und/oder das Signal i vom Signalgeber 8 geliefert wird, beispielsweise sobald eine Pressplatte einer Presse den Eilgang bis in eine vorbestimmte Hubstellung ausgeführt hat, wird der Elektromotor 6 in seiner Drehrichtung umgesteuert. Das erste Rückschlagventil 15 geht in die Sperrstellung und separiert die Niederdruck-Pumpenstufe 5 von der Druckleitung 9. Die Hochdruck-Pumpenstufe 4 fördert weiterhin in derselben Förderrichtung in die Druckleitung 9, um dort einen noch höheren Druck aufzubauen, während die Niederdruck-Pumpenstufe 5 jetzt mit umgekehrter Förderrichtung über die Saugleitung 19 und das geöffnete zweite Rückschlagventil 21 ansaugt und direkt in das Reservoir R fördert.If the hydraulic unit A is put into operation, the electric motor 6 is driven in a first direction of rotation, in which the conveying direction of the low-pressure pump stage 5 to the pressure line 9 points. The high-pressure pump stage 4 and the low-pressure pump stage 5 jointly promote in the pressure line 9, wherein the first check valve 15 is open and the first and second pressure relief valves 17, 18 and the second check valve 21 shut off. Both pump stages 4, 5 suck from the reservoir R, wherein the flow the low-pressure pump stage 5 holds the second check valve 21 in the blocking position. Once the predetermined pressure level is reached in the pressure line 9 and / or the signal i is supplied by the signal generator 8, for example, as soon as a press plate of a press has performed the rapid traverse to a predetermined stroke position, the electric motor 6 is reversed in its direction of rotation. The first check valve 15 goes into the blocking position and separates the low-pressure pump stage 5 from the pressure line 9. The high-pressure pump stage 4 further promotes in the same direction in the pressure line 9 to build there even higher pressure, while the low-pressure pump stage 5 now sucked in reverse flow direction via the suction line 19 and the opened second check valve 21 and directly into the reservoir R promotes.

In einer konkreten Ausführungsform kann das erste Druckbegrenzungsventil 17 beispielsweise auf einen Ansprechdruck von 50 bar eingestellt sein, das zweite Druckbegrenzungsventil 18 hingegen auf einen Ansprechdruck von 410 bar.In a specific embodiment, the first pressure relief valve 17 may for example be set to a response pressure of 50 bar, the second pressure relief valve 18, however, to a response pressure of 410 bar.

Ist ein Zyklus ausgeführt, kann der Elektromotor 6 abgestellt werden. Um einen neuen Zyklus auszuführen, treibt die Motorsteuerung 7 den Elektromotor 6 wiederum in der ersten Drehrichtung an, mit welcher beide Pumpenstufen 4, 5 gemeinsam in die Druckleitung 9 fördern.If a cycle is performed, the electric motor 6 can be turned off. In order to carry out a new cycle, the motor controller 7 drives the electric motor 6 again in the first direction of rotation, with which both pump stages 4, 5 jointly convey into the pressure line 9.

Claims (10)

  1. Hydraulic aggregate (A), comprising high pressure and low pressure pump stages (4, 5) rotatably driven by at least one electric motor (6), the pump stages (4, 5) being connected at their discharge sides at least with a common pressure line (9) and at their suction sides to a reservoir (R), the pump stages being hydraulically arranged such that up to a predetermined pressure level in the pressure line (9) the discharge flows of the pump stages (4, 5) are summarised in the pressure line, while with pressures in the pressure line (9) above the predetermined pressure level only the discharge flow of the high pressure pump stage (4) is brought into the pressure line (9) while the discharge flow of each low pressure pump stage (5) which then is separated from the pressure line (9), is directed with minimum losses to the reservoir (R), characterised in that each low pressure pump stage (5) is designed and hydraulically arranged such that the discharge flow of each low pressure pump stage (5) can be directed to the reservoir (R) by a reverse of the sense of rotation of the pump stage (5) as soon as the predetermined pressure level is reached.
  2. Hydraulic aggregate according to claim 1, characterised in that the electric motor (6) is reversible, that the high pressure pump stage (4) comprises at least one radial piston or axial piston pump having a discharge direction which is independent from the sense of rotation, and that the low pressure pump stage (5) is a reversible gear pump operating with respective opposite discharge directions depending on the sense of rotation, such that one discharge direction of the low pressure pump stage (5) which corresponds with the discharge direction of the high pressure pump stage (4) is directed to the pressure line (9), and that the other discharge direction of the low pressure pump stage (5) is directed to the reservoir (R).
  3. Hydraulic aggregate according to at least one of claims 1 and 2, characterised in that between discharge sides of the high pressure pump stage (4) and of the at least one low pressure pump stage (5), which discharge sides have the same sense of discharge direction, a first check valve (15) is provided, which blocks in flow direction towards the low pressure pump stage (5), and that between the first check valve (15) and the low pressure pump stage (5) a suction line (19) extends to the reservoir (R) in which suction line (19) a second check valve (21) is arranged which blocks in flow direction towards the reservoir (R).
  4. Hydraulic aggregate according to claim 2, characterised in that the low pressure pump stage (5) is safeguarded in the one discharge direction towards the pressure line (9) by a first pressure limiting valve (17).
  5. Hydraulic aggregate according to at least one of the preceding claims, characterised in that all pump stages (5, 4) have a permanent drive connection with a common reversible electric motor (6).
  6. Hydraulic aggregate according to at least one of claims 1 to 4, characterised in that an own electric motor (6) is provided for at least one of the pump stages, preferably for the high pressure pump stage (4).
  7. Hydraulic aggregate according to at least one of the preceding claims, characterised in that the electric motor (6) and the pump stages (4, 5) are arranged in a housing (26) defining the reservoir (R), preferably inclusive of the respective suction line (19) containing the second check valve (21) and the pressure line (9) leading to an outer side of the housing (26), and that at the outer side of housing (26) a valve assembly (V) is mounted, which valve assembly (V) contains at least the first check valve (15) and the first pressure limiting valve (17).
  8. Hydraulic aggregate according claim 7, characterised in that the valve assembly (V) comprises a connection block (1) having pressure and reservoir ports (24, 25) and a second connection block containing a second pressure limiting valve (18) for safeguarding the high pressure pump stage (4), which connection block is mounted via an intermediate plate (2) to the outer side of the housing (26) which outer side comprises the first check valve (15) and the first pressure limiting valve (17).
  9. Hydraulic aggregate according to at least one of the preceding claims, characterised in that the reversible electric motor (6) has a nominal power of about 0.5 kW to about 1.0 kW, and that the specific discharge flows of the high pressure and low pressure pump stages (4, 5) are in a ratio of about 1:5 to 1:10.
  10. Hydraulic aggregate according to at least one of the preceding claims, characterised in that an electric motor control (7) is connected with a signal emitter (8) for controlling a reversion of the sense of rotation, preferably with a fast gear-position sensor and/or a pressure sensor and/or a responding sensor of the first pressure limiting valve (17) or of the first check valve (15).
EP09014848A 2009-11-30 2009-11-30 Hydraulic assembly Not-in-force EP2330304B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP09014848A EP2330304B1 (en) 2009-11-30 2009-11-30 Hydraulic assembly

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP09014848A EP2330304B1 (en) 2009-11-30 2009-11-30 Hydraulic assembly

Publications (2)

Publication Number Publication Date
EP2330304A1 EP2330304A1 (en) 2011-06-08
EP2330304B1 true EP2330304B1 (en) 2012-07-18

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ID=42194791

Family Applications (1)

Application Number Title Priority Date Filing Date
EP09014848A Not-in-force EP2330304B1 (en) 2009-11-30 2009-11-30 Hydraulic assembly

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EP (1) EP2330304B1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2642122B1 (en) 2012-03-21 2014-05-21 HAWE Hydraulik SE Pump power unit

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4008571A (en) * 1976-03-31 1977-02-22 Towmotor Corporation Hydraulic system for electric lift trucks
IT1193521B (en) * 1980-03-03 1988-07-08 Same Spa HYDRAULIC CIRCUIT OF A TRACTOR FOR THE CONTROL OF ACTUATORS
JPS6487884A (en) * 1987-09-30 1989-03-31 Matsushita Electric Ind Co Ltd Pump device
JP2005090351A (en) * 2003-09-17 2005-04-07 Toyota Motor Corp Pump device

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EP2330304A1 (en) 2011-06-08

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