EP0327666A1 - Hydraulic drive - Google Patents

Hydraulic drive Download PDF

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Publication number
EP0327666A1
EP0327666A1 EP88112361A EP88112361A EP0327666A1 EP 0327666 A1 EP0327666 A1 EP 0327666A1 EP 88112361 A EP88112361 A EP 88112361A EP 88112361 A EP88112361 A EP 88112361A EP 0327666 A1 EP0327666 A1 EP 0327666A1
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EP
European Patent Office
Prior art keywords
stroke
hydraulic drive
pressure
piston
working
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.)
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Application number
EP88112361A
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German (de)
French (fr)
Inventor
Josef Nusser
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Individual
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Individual
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Publication date
Priority claimed from DE3803009A external-priority patent/DE3803009C2/en
Application filed by Individual filed Critical Individual
Publication of EP0327666A1 publication Critical patent/EP0327666A1/en
Withdrawn legal-status Critical Current

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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
    • F15B11/028—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force
    • F15B11/036—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force by means of servomotors having a plurality of working chambers
    • 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
    • F15B2211/30—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
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
    • 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
    • F15B2211/505—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
    • F15B2211/50536—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using unloading valves controlling the supply pressure by diverting fluid to the 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
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5151—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a directional control valve
    • 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
    • F15B2211/5153—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve
    • F15B2211/5154—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve being connected to multiple ports of an 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
    • F15B2211/50—Pressure control
    • F15B2211/52—Pressure control characterised by the type of actuation
    • F15B2211/528—Pressure control characterised by the type of actuation actuated by fluid 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
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/625—Accumulators
    • 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
    • F15B2211/7055—Linear output members having more than two chambers
    • 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
    • F15B2211/775—Combined control, e.g. control of speed and force for providing a high speed approach stroke with low force followed by a low speed working stroke with high force, e.g. for a hydraulic press

Definitions

  • the invention relates to a hydraulic drive for linear movement with a hydraulically driven, stroke-movable, piston-cylinder assignment.
  • Such drives have the purpose of performing lifting movements to overcome a working resistance.
  • hydraulic cylinders which are fed with a flow of flow when the work surface is unchangeable and can only be acted upon at the same time.
  • the volume flow rate is analogous to the stroke, but also the working pressure to the lifting force.
  • the flow rate is subject to very strong pressure fluctuations when the lifting force is applied differently, which have a negative effect on the pump and the drive upstream of the pump.
  • the pump must be designed in such a way that it is able to generate a high pressure and to provide a large volume flow rate for the smooth-running range of the stroke movement to ensure a sufficient stroke speed.
  • This configuration requires in particular because of the high pressure required for the power stroke and the pressure reduction that is essential for the easy-running area, poor efficiency. Attempts have been made to eliminate these disadvantages by means of different flow rates which are generated by several independent pumps. Reversible variable pumps are also used. As a result, the flow volume could be approximated to the demand.
  • the stroke movement in the low-speed range is to be carried out as a rapid stroke with a low flow rate requirement, in order to then be continued in the power stroke in the case of greater working resistance by means of lifting force amplification.
  • Several hydraulic drives should be powered by just one pump and load peaks on the drive side should be avoided.
  • the multi-stage piston-cylinder design forms separate pressure spaces with the resulting partial work surfaces of different sizes and the work surface can be partially or completely acted upon by the working pressure of the flow and at the start of the preliminary stroke
  • the pressure chamber with the smallest assigned work surface is initially fed with flow and during the work stroke to overcome a greater working resistance, in addition until the intended stroke length is reached, the pressure chamber with the next larger work surface can be fed with flow in succession.
  • a multiple piston consists of the inner piston with a circular cross section and one or more annular pistons concentrically surrounding the inner piston with an annular working surface and is displaceable relative to the multiple cylinder adapted to it, thereby forming separate pressure chambers and separately pressurizable working surfaces the working pressure of the flow rate can be partially or completely applied to this working area and, at the beginning of the preliminary stroke, the pressure space with the smallest assigned working area is initially fed with flow rate and during the working stroke to overcome a greater working resistance, additionally until the intended stroke length is reached , the pressure chamber with the next larger work surface is fed with flow in succession.
  • the delivery flow can be switched into the pressure chambers as a function of force and / or path.
  • the rapid, error-free supply of the pressure chambers is ensured by the fact that the delivery flow is automatically switched into the pressure rooms to be supplied with delivery flow one after the other, and a counterpressure level in an already supplied pressure room is effective as a signal for the connection of the pressure room to be subsequently fed with delivery flow, whereby short switching distances and a direct switching process are given, in that the signal pressure acts as switching force for the switching process.
  • the pressure chambers are constantly filled with fluid and can be fed from the storage container or emptied into the same, depending on the direction of movement of the piston, until a pressure chamber concerned is supplied with flow and the flow between this pressure chamber and the reservoir is interrupted.
  • the smoothness of the return stroke of the piston is given by unlocking the check valves swipe the pressure chambers and the reservoir, so that the fluid can escape from the pressure chambers in the reservoir.
  • the return stroke is very safe and precise because the piston is double-acting.
  • a very reliable and compact design is achieved in that the signal and / or control elements are fully or partially integrated in the cylinder. Exact positioning of the end position is often necessary, largely without the need for end position damping.A low piston speed should be achieved shortly before the end of the stroke, in that one or more pressure chambers with a larger work surface are fed with flow, regardless of the required lifting force.
  • the stepped piston is double-acting and formed by the piston rod 1 and the piston steps 6, 7, 8 and arranged in the adapted double-acting stepped cylinder 2 in a stroke-movable manner.
  • a plurality of separate pressure spaces 3, 4, 5 and work surfaces 22 of different sizes and for the return stroke of the pressure space 9 are formed.
  • the delivery flow generated by the pump 10 is fed into the pressure chamber 3 via the 4/2 way valve 11 through a corresponding switching position via the feed line 12.
  • By closing the check valve 13 a pressure is created in the pressure chamber 3 which, because of the comparatively small working surface 22 and a low flow volume, moves the stepped piston to the front at high speed.
  • the filling flow flows through the check valves 18, 20 into the increasing pressure Rooms 4, 5 and the contents of the pressure chamber 9 can be emptied into the pressure accumulator 14 or the tank 15 via the valve 11.
  • the connecting valve 16 opens and the delivery flow can feed the pressure chamber 4 via the line 17.
  • the pressure in the pressure chamber 4 increases, so that the check valve 18 closes and the lifting force increases.
  • the connecting valve 19 opens and the flow can also feed the pressure chamber 5 and the check valve 20 closes. In this switch position, the stepped piston can deliver its greatest lifting force.
  • the flow into the pressure chambers 3, 4, 5 is interrupted and can be conducted into the pressure chamber 9.
  • the check valves 13, 18, 20 are relaxed.
  • the stepped piston travels back stroke and the pressure chambers 3, 4, 5 are emptied via the lines 23 into the tank 21 or to maintain a low preload pressure in the pressure accumulator 24 and, if the preload pressure is exceeded, only partially into the tank 21 via the pressure relief valve 25
  • the pressure of the filling stream held by the pressure accumulator 24 ensures that the pressure spaces 3, 4, 5 are always filled with the filling stream without bubbles, even during the filling process.
  • the cylinder cover 26 can be attached so that the pressure chamber 27 is formed and connected to the line 23 via the line 28 and the check valve 29.
  • the contents of the pressure chamber 27 can escape into the line 23 until, at the desired stopping point, the flow supply to the pressure chambers 3, 4, 5 is interrupted and the check valve 29 is closed.
  • the double piston 29 shown in FIG. 3 consists of the inner piston 30 with a circular cross section and the ring piston 31 surrounding the inner piston 30 and the adapted cylinder 32.
  • the inner piston 30 and the outer ring piston 31 have different working surfaces 22 and form with them the assigned pressure chambers 3, 4.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Actuator (AREA)

Abstract

The invention relates to a hydraulic drive for linear movement, with the possibility of a rapid stroke and a power stroke, by a hydraulically driven piston (28, 30, 31)/cylinder (2, 32) association which can perform a stroke movement and has a working area (22) which is split up into sectional working areas (22) as a function of the stroke power required and to which delivery flow can be partly or fully admitted. <IMAGE>

Description

Die Erfindung betrifft einem hydraulischen Antrieb für Linearbewegung mit einer hydraulisch angetrie­benen, hubbeweglichen, Kolben-Zylinder Zuordnung.The invention relates to a hydraulic drive for linear movement with a hydraulically driven, stroke-movable, piston-cylinder assignment.

Derartige Antriebe haben den Zweck, Hubbewegungen zur Überwindung eines Arbeitswiderstandes auszu­führen.Such drives have the purpose of performing lifting movements to overcome a working resistance.

Zur Erfüllung dieser Erfordernisse sind Hydraulik­zylinder bekannt, die bei unveränderlicher nur gleich­zeitig beaufschlagbarer Arbeitsfläche mit Förderstrom gespeist werden. Dabei verhält sich das Förderstrom­volumen analog zum Hubweg, gleichwohl wie der Arbeits­druck zur Hubkraft.To meet these requirements, hydraulic cylinders are known which are fed with a flow of flow when the work surface is unchangeable and can only be acted upon at the same time. The volume flow rate is analogous to the stroke, but also the working pressure to the lifting force.

Bei diesen bekannten Ausführungen unterliegt der Förderstrom bei unterschiedlich aufzubringender Hubkraft sehr starken Druckschwankungen, die sich auf die Pumpe und den der Pumpe vorgelagerte Antrieb negativ auswirken. Einerseits muß die Pumpe so aus­gelegt sein, daß sie imstande ist einen hohen Druck zu erzeugen und für den Leichtlaufbereich der Hubbe­wegung zur Gewährleistung einer genügenden Hubge­schwindigkeit ein großes Förderstromvolumen zu er­bringen. Diese Ausgestaltung bedingt insbesondere wegen der erforderlichen hohen Druckvorhaltung für den Krafthub und die für den Leichtlaufbereich un­umgängliche Druckminderung einen schlechten Wirkungs­grad. Es wurde versucht diese Nachteile durch ver­schiedene Förderströme die von mehreren unabhängigen Pumpen erzeugt werden zu beseitigen. Desweitere wer­den reversierbare Verstellpumpen eingesetzt. Dadurch konnte das Förderstromvolumen dem Bedarf angenähert weden. Diese Maßnahmen bedingen einen hohen techni­schen und baulichen Aufwand mit den einhergehenden Verlust- und Verschleißerscheinungen mit starken Belastungsspitzen und dem weiteren Nachteil, daß diese Steuerung wegen der direkten Koppelung von Pumpe und Hydraulikantrieb, auf weitere Steuerkreise nicht erweitert werden kann. Die vorgenannten Ausfüh­rungen haben auch eine Starke Geräuschentwicklung zur Folge.In these known designs, the flow rate is subject to very strong pressure fluctuations when the lifting force is applied differently, which have a negative effect on the pump and the drive upstream of the pump. On the one hand, the pump must be designed in such a way that it is able to generate a high pressure and to provide a large volume flow rate for the smooth-running range of the stroke movement to ensure a sufficient stroke speed. This configuration requires in particular because of the high pressure required for the power stroke and the pressure reduction that is essential for the easy-running area, poor efficiency. Attempts have been made to eliminate these disadvantages by means of different flow rates which are generated by several independent pumps. Reversible variable pumps are also used. As a result, the flow volume could be approximated to the demand. These measures require a high level of technical and structural complexity with the associated loss and wear phenomena with strong load peaks and the further disadvantage that this control cannot be extended to other control circuits because of the direct coupling of the pump and hydraulic drive. The aforementioned designs also result in a strong noise level.

Demgegenüber ist es Aufgabe der Erfindung, mittels geringem baulichen Aufwand und Energieeinsparung sowie Geräuschminderung einen Hydraulikantrieb zu schaffen, bei dem der gewünschte Hubgeschwindigkeits- und Hubkraftverlauf exakt eingehalten werden kann. So soll sofern die Erfordernisse dies nützlich er­scheinen lassen, die Hubbewegung im Leichtlaufbereich als Eilhub bei geringem Förderstrombedarf erfolgen, um dann bei größerem Arbeitswiderstand durch Hubkraft­verstärkung im Krafthub weitergeführt zu werden. Mehrere Hydraulikantriebe sollen von nur einer Pumpe gespeist und antriebsseitige Belastungsspitzen ver­mieden werden können.In contrast, it is an object of the invention to create a hydraulic drive by means of low structural expenditure and energy saving as well as noise reduction, in which the desired stroke speed and stroke force curve can be exactly maintained. Thus, if the requirements make this appear useful, the stroke movement in the low-speed range is to be carried out as a rapid stroke with a low flow rate requirement, in order to then be continued in the power stroke in the case of greater working resistance by means of lifting force amplification. Several hydraulic drives should be powered by just one pump and load peaks on the drive side should be avoided.

Diese Aufgabe wird erfindungsgemäß im Wesentlichen dadurch gelöst, daß durch die mehrstufige Stufen­kolben-Zylinder Ausgestaltung getrennte Durckräume mit den sich daraus ergebenden Teil-Arbeitsflächen verschiedener Größe gebildet werden und die Arbeits­fläche teilweise oder ganz, mit dem Arbeitsdruck des Förderstromes beaufschlagbar ist und bei Beginn des Vorhubes vorteilhaft zunächst der Druckraum mit der kleinsten zugeordneten Arbeitsfläche mit Förderstrom gespeist wird und während des Arbeitshubes zur Über­windung eines größeren Arbeitswiderstandes, zusätz­lich bis zum Erreichen der vorgesehenen Hublänge, nacheinander jeweils der Druckraum mit der nächst größeren Arbeitsfläche mit Förderstrom gespeist werden kann.This object is essentially achieved in that the multi-stage piston-cylinder design forms separate pressure spaces with the resulting partial work surfaces of different sizes and the work surface can be partially or completely acted upon by the working pressure of the flow and at the start of the preliminary stroke Advantageously, the pressure chamber with the smallest assigned work surface is initially fed with flow and during the work stroke to overcome a greater working resistance, in addition until the intended stroke length is reached, the pressure chamber with the next larger work surface can be fed with flow in succession.

Die Lösung der gestellten Aufgabe wird auch erreicht, indem ein Mehrfachkolben aus dem inneren Kolben mit kreisrunden Querschnitt und einen oder mehrere den inneren Kolben konzentrisch umgebenden Ringkolben mit ringförmiger Arbeitsfläche besteht und gegen­über dem ihm angepaßten Mehrfachzylinder verschieb­bar ist und dadurch getrennte Druckräume und getrennt beaufschlagbare Arbeitsflächen gebildet werden und diese Arbeitsfläche teilweise oder ganz, mit dem Arbeitsdruck des Förderstromes beaufschlagbar ist und bei Beginn des Vorhubes vorteilhaft zunächst der Druckraum mit der kleinsten zugeordneten Arbeits­fläche mit Förderstrom gespeist wird und während des Arbeitshubes zur Überwindung eines größeren Arbeits­widerstandes, zusätzlich bis zum Erreichen der vor­gesehenen Hublänge, nacheinander jeweils der Druck­raum mit der nächst größeren Arbeitsfläche mit För­derstrom gespeist wird.The solution to the problem is also achieved in that a multiple piston consists of the inner piston with a circular cross section and one or more annular pistons concentrically surrounding the inner piston with an annular working surface and is displaceable relative to the multiple cylinder adapted to it, thereby forming separate pressure chambers and separately pressurizable working surfaces the working pressure of the flow rate can be partially or completely applied to this working area and, at the beginning of the preliminary stroke, the pressure space with the smallest assigned working area is initially fed with flow rate and during the working stroke to overcome a greater working resistance, additionally until the intended stroke length is reached , the pressure chamber with the next larger work surface is fed with flow in succession.

Um bei jeder Hubstellung die gewünschte Preßkraft und/oder Hubgeschwindigkeit zu erreichen ist vor­gesehen, daß die Förderstromzuschaltung in die Druck­räume kraft- und/oder wegabhängig erfolgen kann. Wo­bei die schnelle, fehlerfreie Versorgung der Druck­räume dadurch gewährleistet ist, daß die Förderstrom­zuschaltung in die nacheinander mit Förderstrom zu versorgenden Druckräume automatisch erfolgt und ein vorgegenes Druckniveau in einem bereits gespeisten Druckraum als Signal für die Zuschaltung des jeweils nachfolgend mit Förderstrom zu speisenden Druckraumes wirksam ist, wobei kurze Schaltwege und ein direkter Schaltvorgang gegeben ist, indem der Signaldruck als Schaltkraft für den Schaltvorgang wirksam ist. Damit die Druckräume immer frei von Luftblasen sind und die einhergehenden Nachteile vermieden werden, sind die Druckräume dauernd mit Fluid gefüllt und können in Abhängigkeit der Bewegungsrichtung des Kolbens aus dem Vorratsbehälter gespeist oder in den­selben entleert werden, bis ein Betreffender Druck­raum mit Förderstrom gespeist und der Druchfluß zwi­schen diesem Druckraum und dem Vorratsbehälter unter­brochen wird. Die Leichtgängigkeit beim Rückhub des Kolbens ist durch Entsperren der Rückschlagventile swischen den Druckräumen und dem Vorratsbehälter ge­geben, sodaß der Fluid aus den Druckräumen in den Vorrats behälter entweichen kann. Sehr sicher und präzise erfolgt der Rückhub, indem der Kolben doppel­wirkend ausgebildet, ist. Eine sehr betriebssichere und kompakte Ausgestaltung wird dadurch erreicht, in­dem die Signal- und/oder Steuerglieder ganz oder teilweise in den Zylinder integriert sind. Oftmals ist eine exakte Positionierung der Endstellung unter weitgehendem Verzicht auf Endlagendämpfung notwendig, dazu soll kurz vor Hubende eine niedere Kolbengesch­windigkeit erreicht werden, indem unabhängig von der erforderlichen Hubkraft zusätzlich ein oder mehrere Druckräume mit größerer Arbeitsfläche mit Förderstrom gespeist werden.In order to achieve the desired pressing force and / or lifting speed at each stroke position, it is provided that the delivery flow can be switched into the pressure chambers as a function of force and / or path. The rapid, error-free supply of the pressure chambers is ensured by the fact that the delivery flow is automatically switched into the pressure rooms to be supplied with delivery flow one after the other, and a counterpressure level in an already supplied pressure room is effective as a signal for the connection of the pressure room to be subsequently fed with delivery flow, whereby short switching distances and a direct switching process are given, in that the signal pressure acts as switching force for the switching process. So that the pressure chambers are always free of air bubbles and the associated disadvantages are avoided, the pressure chambers are constantly filled with fluid and can be fed from the storage container or emptied into the same, depending on the direction of movement of the piston, until a pressure chamber concerned is supplied with flow and the flow between this pressure chamber and the reservoir is interrupted. The smoothness of the return stroke of the piston is given by unlocking the check valves swipe the pressure chambers and the reservoir, so that the fluid can escape from the pressure chambers in the reservoir. The return stroke is very safe and precise because the piston is double-acting. A very reliable and compact design is achieved in that the signal and / or control elements are fully or partially integrated in the cylinder. Exact positioning of the end position is often necessary, largely without the need for end position damping.A low piston speed should be achieved shortly before the end of the stroke, in that one or more pressure chambers with a larger work surface are fed with flow, regardless of the required lifting force.

Weitere Enzelheiten, Vorteile und Merkmale der Erfin­dung ergeben sich aus der folgenden Beschriebung. Auf der Zeichnung ist die Erfindung beispielsweise veran­schaulicht. Es zeigen:

  • Fig. 1 Stufenkolben und Stufenzylinder mit Steuerung doppelwirkend,
  • Fig. 2 Stufenkolben und Stufenzylinder,
  • Fig. 3 Mehrfachkolben und Mehrfachzylinder,
  • Fig. 4 eine weitere Ausgestaltung von Mehrfachkolben und Mehrfachzylinder.
Further details, advantages and features of the invention result from the following description. The invention is illustrated for example in the drawing. Show it:
  • 1 step piston and step cylinder with control double-acting,
  • 2 step piston and step cylinder,
  • 3 multiple pistons and multiple cylinders,
  • Fig. 4 shows a further embodiment of multiple pistons and multiple cylinders.

Beim Hydraulikantrieb der Darstellung nach der Fig. 1 ist der Stufenkolben doppelwirkend und durch die Kol­benstange 1 und die Kolbenstufen 6, 7, 8 gebildet und in dem angepaßten doppelwirkenden Stufenzylinder 2 hubbeweglich angeordnet. Dadurch werden mehrere ge­trennte Druckräume 3, 4, 5 und Arbeitsflächen 22 mit unterschiedlicher Größe und für den Rückhub der Druck­raum 9 gebildet. Bei Beginn des Arbeitshubes wird der von der Pumpe 10 erzeugte Förderstrom über das 4/2 Wegeventil 11 durch entsprechende Schaltstellung über die Zuleitung 12 in den Druckraum 3 eingespeist. Durch Schließen des Rückschlagventils 13 entsteht im Druckraum 3 ein Druck, der wegen der vergleichsweise kleinen Arbeistfläche 22 bei geringem Förderstrom­volumen den Stufenkolben im Schnellgang nach vorne bewegt. Gleichzeitig fließt Füllstrom über die Rück­schlagventile 18, 20 in die sich vergrößernden Druck­ räume 4, 5 und der Inhalt des Druckraumes 9 kann sich über das Ventil 11 in den Druckspeicher 14 oder den Tank 15 entleeren. Sobald der Stufenkolben auf einen Widerstand trifft, der den Druck des Förder­stromes über den vorgegebenen Wert ansteigen läßt, öffnet das Zuschaltventil 16 und der Förderstrom kann über die Leitung 17 den Druckraum 4 speisen. Dabei steigt der Druck im Druckraum 4 an, sodaß das Rückschlagventil 18 schließt und die Hubkraft ansteigt. Nachdem der Druckaufbau den vorgegebenen Wert wieder erreicht hat, öffnet das Zuschaltventil 19 und der Förderstrom kann auch den Druckraum 5 speisen und das Rückschlagventil 20 schließt. Bei dieser Schaltstel­lung kann der Stufenkolben seine größte Hubkraft er­bringen.1, the stepped piston is double-acting and formed by the piston rod 1 and the piston steps 6, 7, 8 and arranged in the adapted double-acting stepped cylinder 2 in a stroke-movable manner. As a result, a plurality of separate pressure spaces 3, 4, 5 and work surfaces 22 of different sizes and for the return stroke of the pressure space 9 are formed. At the start of the working stroke, the delivery flow generated by the pump 10 is fed into the pressure chamber 3 via the 4/2 way valve 11 through a corresponding switching position via the feed line 12. By closing the check valve 13, a pressure is created in the pressure chamber 3 which, because of the comparatively small working surface 22 and a low flow volume, moves the stepped piston to the front at high speed. At the same time, the filling flow flows through the check valves 18, 20 into the increasing pressure Rooms 4, 5 and the contents of the pressure chamber 9 can be emptied into the pressure accumulator 14 or the tank 15 via the valve 11. As soon as the stepped piston encounters a resistance that causes the pressure of the delivery flow to rise above the predetermined value, the connecting valve 16 opens and the delivery flow can feed the pressure chamber 4 via the line 17. The pressure in the pressure chamber 4 increases, so that the check valve 18 closes and the lifting force increases. After the pressure build-up has reached the predetermined value again, the connecting valve 19 opens and the flow can also feed the pressure chamber 5 and the check valve 20 closes. In this switch position, the stepped piston can deliver its greatest lifting force.

Zur Beendigung des Arbeitshubes wird der Förderstrom in die Druckräume 3, 4, 5 unterbrochen und kann in den Druckraum 9 geleitet werden. Gleichzeitig werden die Rückschlagventile 13, 18, 20 entspannt. Der Stufen­kolben fährt Rückhub und die Druckräume 3, 4, 5 ent­leeren sich über die Leitungen 23 in den Tank 21 oder zur Aufrechterhaltung eines geringen Vorspanndrucks in den Druckspeicher 24 und bei übersteigen des Vor­spanndrucks über das Druckbegrenzungsventil 25 nur teilweise in den Tank 21. Der geringe vom Druckspei­cher 24 vorgehaltene Druck des Füllstromes gewährleistet, daß die Druckräume 3, 4, 5 auch beim Befüllvorgang immer blasenfrei mit dem Füllstrom gefüllt sind.At the end of the working stroke, the flow into the pressure chambers 3, 4, 5 is interrupted and can be conducted into the pressure chamber 9. At the same time, the check valves 13, 18, 20 are relaxed. The stepped piston travels back stroke and the pressure chambers 3, 4, 5 are emptied via the lines 23 into the tank 21 or to maintain a low preload pressure in the pressure accumulator 24 and, if the preload pressure is exceeded, only partially into the tank 21 via the pressure relief valve 25 The pressure of the filling stream held by the pressure accumulator 24 ensures that the pressure spaces 3, 4, 5 are always filled with the filling stream without bubbles, even during the filling process.

Soll der Stufenkolben am Ende des Arbeitshubes exakt positioniert abgebremst werden, wie es in vielen Arbeitsvorgängen erforderlich ist, kann der Zylinder­verschlußdeckel 26 angebracht werden, so, daß der Druckraum 27 gebildet und über die Leitung 28 und das Rückschlagventil 29 mit der Leitung 23 verbunden ist. Beim Vorhub des Stufenkolbens kann durch Ent­spannen des Rückschlagventils 29 der Inhalt des Druck­raumes 27 in die Leitung 23 entweichen, bis beim ge­wünschten Haltepunkt die Förderstromspeisung der Druckräume 3, 4, 5 unterbrochen und das Rückschlag­ventil 29 geschlossen wird.If the stepped piston is to be braked exactly at the end of the working stroke, as is the case in many Operations are required, the cylinder cover 26 can be attached so that the pressure chamber 27 is formed and connected to the line 23 via the line 28 and the check valve 29. During the forward stroke of the stepped piston, by releasing the check valve 29, the contents of the pressure chamber 27 can escape into the line 23 until, at the desired stopping point, the flow supply to the pressure chambers 3, 4, 5 is interrupted and the check valve 29 is closed.

Die Fig. 2 zeigt den Stufenzylinder 2 mit dem ange­paßten Stufenkolben 28, den Arbeitsflächen 22 und den Druckräumen 3, 4.2 shows the stepped cylinder 2 with the adapted stepped piston 28, the working surfaces 22 and the pressure chambers 3, 4.

Der in der Fig. 3 dargestellte Doppelkolben 29 besteht aus dem inneren Kolben 30 mit kreisrunden Querschnitt und dem den inneren Kolben 30 umgebenden Ringkolben 31 und dem angepaßten Zylinder 32. Der innere Kolben 30 und der äußere Ringkolben 31 weisen unterschiedliche Arbeitsflächen 22 auf und bilden mit dem zugeordneten-­Zylinder 32 die getrennten Druckräume 3, 4.The double piston 29 shown in FIG. 3 consists of the inner piston 30 with a circular cross section and the ring piston 31 surrounding the inner piston 30 and the adapted cylinder 32. The inner piston 30 and the outer ring piston 31 have different working surfaces 22 and form with them the assigned pressure chambers 3, 4.

Claims (13)

1. Hydraulischer Antrieb für Linearbewegung mit einer hydraulisch angetriebenen, hubbeweglichen Kolben-Zylinderzuordnung, dadurch gekennzeichnet, daß durch die mehrstufige Stufenkolben (28) - Zylinder (2) Ausgestaltung getrennte Druckräume (3, 4, 5) mit den sich daraus ergebenden Teil-Arbeitsflächen (22) verschiedener Größe gebildet werden und die Arbeits­fläche (22) teilweise oder ganz, mit dem Arbeits­druck des Förderstromes beaufschlagbar ist und bei Beginn des Vorhubes vorteilhaft zunächst der Druck­raum (3, 4, 5) mit der kleinsten zugeordneten Arbeits­fläche (22) mit Förderstrom gespeist wird und während des Arbeitshubes zur Überwindung eines größeren Ar­beitswiderstandes, zusätzlich bis zum Erreichen der vorgesehenen Hublänge, nacheinander jeweils der Druck­raum (3, 4, 5) mit der nächst größeren Arbeitsfläche (22) mit Förderstrom gespeist werden kann.1. Hydraulic drive for linear movement with a hydraulically driven, stroke-movable piston-cylinder assignment, characterized in that through the multi-stage piston (28) - cylinder (2) design separate pressure chambers (3, 4, 5) with the resulting partial work surfaces (22) of different sizes are formed and the working surface (22) can be partially or completely acted upon by the working pressure of the delivery flow and, at the beginning of the preliminary stroke, the pressure chamber (3, 4, 5) with the smallest assigned working area (22) with delivery flow is advantageous is fed and during the working stroke to overcome a larger working resistance, in addition until the intended stroke length is reached, the pressure chamber (3, 4, 5) with the next larger working surface (22) can be fed with flow in succession. 2. Hydraulischer Antrieb für Linearbewegung mit einer Hydraulisch angetriebenen, hubbeweglichen Kolben-Zylinderzuordnung, dadurch gekennzeichnet, daß ein Mehrfachkolben (29) aus dem inneren Kolben (30) mit kreisrunden Querschnitt und einen oder mehrere den inneren Kolben (30) konzentrisch umge­benden Ringkolben (31) mit ringförmiger Arbeitsfläche (22) besteht und gegenüber dem ihm angepaßten Mehrfach­zylinder (32) verschiebbar ist und dadurch getrennte Druckräume (3, 4) und getrennt beaufschlagbare Arbeits­flächen (22) gebildet werden und die Arbeitsfläche (22) teilweise oder ganz, mit dem Arbeitsdruck des Förder­stromes beaufschlagbar ist und bei Beginn des Vor­hubes vorteilhaft zunächst der Druckraum (3, 4) mit der kleinsten zugeordneten Arbeitsfläche (22) mit Förderstrom gespeist wird und während des Arbeitshubes zur Überwindung eines größeren Arbeitswiderstandes, zusätzlich bis zum Erreichen der vorgesehenen Hub-­länge, nacheinander jeweils der Druckraum (3, 4) mit der nächst größeren Arbeitsfläche (22) mit Förderstrom gespeist wird.2. Hydraulic drive for linear movement with a hydraulically driven, stroke-movable piston-cylinder association, characterized in that a multiple piston (29) from the inner piston (30) with a circular cross-section and one or more ring pistons (31) concentrically surrounding the inner piston (30) ) with an annular working surface (22) and is displaceable relative to the multiple cylinder (32) adapted to it, thereby forming separate pressure chambers (3, 4) and separately pressurizable working surfaces (22) and the working surface (22) partially or entirely with the working pressure the flow rate can be acted upon and at the beginning of the preliminary stroke the pressure chamber (3, 4) with the smallest assigned working surface (22) is advantageously supplied with flow rate and during the working stroke to overcome a greater working resistance, additionally until the intended stroke length is reached, successively the pressure chamber (3, 4) with the next size Ren work surface (22) is fed with flow. 3. Hydraulischer Antrieb nach Anspruch 1 under 2, da­durch gekennzeichnet, daß die Förderstromzuschaltung in die Druckräume (3, 4, 5) kraft- und/oder wegab­hängig erfolgen kann.3. Hydraulic drive according to claim 1 under 2, characterized in that the delivery flow connection in the pressure chambers (3, 4, 5) can be force and / or path-dependent. 4. Hydraulischer Antrieb nach Anspruch 1 bis 3, da­durch gekennzeichnet, daß die Förderstromzuschaltung in die nacheinander mit Förderstrom zu versorgenden Druckräume (3, 4, 5) automatisch erfolgt und ein vor­gegebenes Druckniveau in einem bereits gespeisten Druckraum (3, 4, 5) als Signal für die Zuschaltung des jeweils nachfolgend mit Förderstrom zu speisenden Druckraumes wirksam ist.4. Hydraulic drive according to claim 1 to 3, characterized in that the delivery flow connection in the successively supplied with delivery flow pressure chambers (3, 4, 5) takes place automatically and a predetermined pressure level in an already supplied pressure chamber (3, 4, 5) as Signal for the connection of the pressure chamber to be fed with the flow rate is effective. 5. Hydraulischer Antrieb nach mindestens einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Signaldruck als Schaltkraft für den Schalt­vorgang wirksam ist.5. Hydraulic drive according to at least one of the preceding claims, characterized in that the signal pressure is effective as a switching force for the switching process. 6. Hydraulischer Antrieb nach mindestens einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Druckräume (3, 4, 5) dauernd mit Fluid ge­füllt sind und in Abhängigkeit der Bewegungsrichtung des Kolbens (28, 29 30, 31) aus dem Vorratsbehälter (24) gespeist oder in denselben entleert werden können.6. Hydraulic drive according to at least one of the preceding claims, characterized in that the pressure spaces (3, 4, 5) are constantly filled with fluid and depending on the direction of movement of the piston (28, 29 30, 31) from the reservoir (24) can be fed or emptied in the same. 7. Hydraulischer Antrieb nach mindestens einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß sobald ein Druckraum (3, 4, 5) mit Förderstrom gespeist wird, der Durchfluß zwischen diesem Druck­raum (3, 4, 5) und dem Vorratsbehälter (24) durch das zugeordnete Rückschlagventil (13, 18, 20) unter­brochen wird.7. Hydraulic drive according to at least one of the preceding claims, characterized in that as soon as a pressure chamber (3, 4, 5) is fed with flow, the flow between this pressure chamber (3, 4, 5) and the reservoir (24) by the assigned check valve (13, 18, 20) is interrupted. 8. Hydraulischer Antrieb nach mindestens einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß beim Rückhub des Kolbens (28, 29, 30, 31) durch Entsperren der Rückschlagventile (13, 18, 20) der Fluid aus den Druckräumen (3, 4, 5) in den Vorratsbehälter (24) entweichen kann.8. Hydraulic drive according to at least one of the preceding claims, characterized in that during the return stroke of the piston (28, 29, 30, 31) by unlocking the check valves (13, 18, 20) the fluid from the pressure chambers (3, 4, 5th ) can escape into the storage container (24). 9. Hydraulischer Antrieb nach mindestens einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Kolben (28, 29, 30, 31) doppelwirkend aus­gebildet sein kann.9. Hydraulic drive according to at least one of the preceding claims, characterized in that the piston (28, 29, 30, 31) can be double-acting. 10. Hydraulischer Antrieb nach mindestens einem der vorgehenden Ansprüche, dadurch gekennzeichnet, daß der Vorhub des Kolbens (28, 29, 30, 31) durch Schließen des Ventils (35) exakt beendet werden kann.10. Hydraulic drive according to at least one of the preceding claims, characterized in that the forward stroke of the piston (28, 29, 30, 31) can be ended exactly by closing the valve (35). 11. Hydraulischer Antrieb nach mindestens einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Signal- und/oder Steuerglieder ganz oder teilweise in den Zylinder (2, 32) integriert sein können.11. Hydraulic drive according to at least one of the preceding claims, characterized in that the signal and / or control elements can be fully or partially integrated in the cylinder (2, 32). 12. Hydraulischer Antrieb nach mindestens einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß kurz vor Hubende eine niedere Kolbengeschwindig­keit erreicht wird, indem unabhängig von der erforder­lichen Hubkraft zusätzlich ein oder mehrere Druckräume ((3, 4, 5) mit größeren Arbeitsfläche ((22) mit Förder­strom gespeist wird.12. Hydraulic drive according to at least one of the preceding claims, characterized in that shortly before the end of the stroke a low piston speed is achieved by additionally one or more pressure chambers ((3, 4, 5) with a larger working surface ((22), regardless of the required lifting force. is fed with flow. 13. Hydraulischer Antrieb nach mindestens einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß Hubstart und Hubende in jeder Hublage erfolgen kann.13. Hydraulic drive according to at least one of the preceding claims, characterized in that the stroke start and stroke end can take place in any stroke position.
EP88112361A 1988-02-02 1988-07-29 Hydraulic drive Withdrawn EP0327666A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE3803009A DE3803009C2 (en) 1987-02-04 1988-02-02 Hydraulic drive

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EP0327666A1 true EP0327666A1 (en) 1989-08-16

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0499826A1 (en) * 1991-02-16 1992-08-26 Krupp Maschinentechnik Gesellschaft Mit Beschränkter Haftung Actuating arrangement for demolition device
EP0711927A3 (en) * 1994-10-11 1997-03-26 Pneumatic Energy Inc Pneumatic transformer
WO1997020146A1 (en) * 1995-11-24 1997-06-05 Mannesmann Rexroth Gmbh Process and device for driving the hydraulic system of a machine
US5784943A (en) * 1996-03-15 1998-07-28 Tamrock Oy Arrangement in a hydraulic cylinder
AT510542A1 (en) * 2010-10-29 2012-05-15 Metso Paper Inc PRESSURE MEMORY FILLING PROCESS FOR A FLUID SYSTEM
FR3044368A1 (en) * 2015-12-01 2017-06-02 Peugeot Citroen Automobiles Sa DEVICE FOR CONTROLLING AN ORGAN TO BE CHECKED BY TWO CONCENTRIC AND INDEPENDENT CYLINDERS
CN108679008A (en) * 2018-07-19 2018-10-19 江苏师范大学 A kind of continuous output booster and control method of changeable pressure ratio

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB191221945A (en) * 1912-09-26 1913-07-31 George Homeyard Improved Arrangements for Controlling the Pressure Water of Hydraulic Machines.

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB191221945A (en) * 1912-09-26 1913-07-31 George Homeyard Improved Arrangements for Controlling the Pressure Water of Hydraulic Machines.

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0499826A1 (en) * 1991-02-16 1992-08-26 Krupp Maschinentechnik Gesellschaft Mit Beschränkter Haftung Actuating arrangement for demolition device
US5199658A (en) * 1991-02-16 1993-04-06 Krupp Maschinentechnik Gesellschaft Mit Beschrankter Haftung Dual-force hydraulic drive for a demolition tool
EP0711927A3 (en) * 1994-10-11 1997-03-26 Pneumatic Energy Inc Pneumatic transformer
WO1997020146A1 (en) * 1995-11-24 1997-06-05 Mannesmann Rexroth Gmbh Process and device for driving the hydraulic system of a machine
US6145307A (en) * 1995-11-24 2000-11-14 Mannesman Rexoth Ag Method and device for controlling a hydraulic installation of a utility vehicle
US5784943A (en) * 1996-03-15 1998-07-28 Tamrock Oy Arrangement in a hydraulic cylinder
AT510542A1 (en) * 2010-10-29 2012-05-15 Metso Paper Inc PRESSURE MEMORY FILLING PROCESS FOR A FLUID SYSTEM
AT510542B1 (en) * 2010-10-29 2013-04-15 Metso Paper Inc PRESSURE MEMORY FILLING PROCESS FOR A FLUID SYSTEM
FR3044368A1 (en) * 2015-12-01 2017-06-02 Peugeot Citroen Automobiles Sa DEVICE FOR CONTROLLING AN ORGAN TO BE CHECKED BY TWO CONCENTRIC AND INDEPENDENT CYLINDERS
CN108679008A (en) * 2018-07-19 2018-10-19 江苏师范大学 A kind of continuous output booster and control method of changeable pressure ratio
CN108679008B (en) * 2018-07-19 2020-06-16 江苏师范大学 Continuous output supercharger with changeable supercharging ratio and control method

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