EP0464481B1 - Control device for a hydraulic motor - Google Patents

Control device for a hydraulic motor Download PDF

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Publication number
EP0464481B1
EP0464481B1 EP91110125A EP91110125A EP0464481B1 EP 0464481 B1 EP0464481 B1 EP 0464481B1 EP 91110125 A EP91110125 A EP 91110125A EP 91110125 A EP91110125 A EP 91110125A EP 0464481 B1 EP0464481 B1 EP 0464481B1
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EP
European Patent Office
Prior art keywords
valve
line
cylinder
cylinder space
pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP91110125A
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German (de)
French (fr)
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EP0464481A1 (en
Inventor
Egon Dipl.-Ing. Tittmann
Heinz Ing. Walter (Grad.)
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Robert Bosch GmbH
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Robert Bosch GmbH
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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
    • F15B11/08—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor
    • 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
    • F15B2211/3056—Assemblies of multiple valves
    • F15B2211/30565—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve
    • F15B2211/3057—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve having two valves, one for each port of a double-acting output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/3056—Assemblies of multiple valves
    • F15B2211/30565—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve
    • F15B2211/3058—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve having additional valves for interconnecting the fluid chambers of a double-acting actuator, e.g. for regeneration mode or for floating mode
    • 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
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3144—Directional control characterised by the positions of the valve element the positions being continuously variable, e.g. as realised by proportional 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
    • F15B2211/35—Directional control combined with flow control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40507—Flow control characterised by the type of flow control means or valve with constant throttles or orifices
    • 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
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40576—Assemblies of multiple 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
    • F15B2211/40—Flow control
    • F15B2211/415—Flow control characterised by the connections of the flow control means in the circuit
    • F15B2211/41554—Flow control characterised by the connections of the flow control means in the circuit being connected to a return line 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
    • F15B2211/40—Flow control
    • F15B2211/415—Flow control characterised by the connections of the flow control means in the circuit
    • F15B2211/41581—Flow control characterised by the connections of the flow control means in the circuit being connected to an output member and a return line
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/42—Flow control characterised by the type of actuation
    • F15B2211/428—Flow 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
    • F15B2211/635—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements
    • F15B2211/6355—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements having valve means

Definitions

  • the invention relates to a device for controlling a hydraulic motor according to the preamble of the main claim.
  • Such a device is already known from DE-A-32 19 730, in which a hydraulic differential cylinder can be controlled via an electrohydraulic control valve, which cooperates with a proportional switching valve which is controlled as a function of the differential pressure and which has a measuring throttle located in a volume flow controlled by the control valve is controllable.
  • a volume flow can be controlled analogously to the hydraulic motor, the size of which considerably exceeds the nominal size of the control valve itself.
  • an overflow circuit is implemented when the piston rod is extended, the volume flow flowing out of the annular space being at least partially returned to the cylinder space.
  • the device according to the invention for controlling a hydraulic motor with the characterizing features of the main claim has the advantage that it can be implemented with relatively little effort and with simple components and thereby enables low-loss operation while maintaining previous advantages.
  • the differential cylinder is operated in an overflow circuit, the losses of a measuring throttle in the volume flow flowing to the engine can be avoided.
  • no volume flow has to flow via the changeover valve which is controlled as a function of the differential pressure.
  • the engine is well clamped hydraulically when the piston rod is extended, since the volume flow flowing out of the annular space is dominated by a single control edge in the control valve and its merging with a pump volume flow only takes place downstream of the control valve.
  • 1 and 2 show a first and a second device for controlling a hydraulic motor, each in a simplified representation.
  • FIG. 1 shows a device 10 for controlling a hydraulic motor, which is designed here as a differential cylinder 11, as is used, for example, as a locking cylinder in a plastic injection molding machine for actuating a mold.
  • the differential cylinder 11 has a cylinder space 12 assigned to its large effective area and an annular space 13 assigned to the smaller effective area, the area ratio of which is 2: 1.
  • the device 10 essentially has, as components, a proportional valve 14 designed as an electrohydraulic control valve, a changeover valve 15 controlled as a function of differential pressure, a pilot-operated check valve 16, and two check valves 17 and 18.
  • the proportional valve 14 which is known per se, has a two-stage design, is switched into a control circuit (not shown in more detail) and, in addition to a spring-centered neutral position 19 with associated zero relief, has a first working position 21 and a second working position 22.
  • An inlet connection 23 designated P is supplied with pressure medium by a pump 24 via an inlet line 25, the first check valve 17 being connected into the inlet line 25.
  • a return connection designated T is connected to a tank 28 via a tank line 27, into which the check valve 16 is connected.
  • a first working line 31 leads from a first motor connection 29, designated A, into the cylinder space 12 of the differential cylinder 11.
  • a second motor connection 32 designated B, is connected to the annular space 13 via a second working line 33.
  • the check valve 16 connected into the tank line 27 consists of a 2/2 cartridge 34, which is hydraulically piloted by a solenoid valve 35.
  • the check valve 16 is designed as a normally open valve.
  • a measuring throttle 36 is connected in the tank line 27 upstream from the shut-off valve 16, which is located in the tank line 27 downstream from a branch point 37.
  • the pressure drop caused by the measuring throttle 36 in the tank line 27 is tapped via two control lines 38, 39 and is used for the differential pressure-dependent control of the changeover valve 15.
  • the switchover valve 15 which is controlled as a function of the differential pressure, is a known throttle valve with double flow for flow force compensation. It has a spring-centered blocking position 41 in which all connections are blocked off and can be deflected into a pressure-dependent working position 42 in which the size of the pressure medium flow flowing through is controlled in proportion to the size of the pressure difference present.
  • the changeover valve 15 is connected in a return line 43, which connects the cylinder space 12 of the differential cylinder 11 directly to the tank 28, this return line 43 for connecting the changeover valve 15 being partially guided in parallel sections.
  • This return line 43 with its section leading to the switching valve 15 port P and the first working line 31 have a common node 44 which is connected via a bypass line 45 to the branch point 37, so that in this way the return port 26 of the proportional valve 14 bypassing Changeover valve 15, check valve 16 and measuring throttle 36 is connected directly to the cylinder chamber 12.
  • this bypass line 45 the second check valve 18 is switched so that it opens towards the cylinder chamber 12.
  • the operation of the device 10 is explained as follows: To close a mold in a plastic injection molding machine, the piston rod of the differential cylinder 11 is extended. For this purpose, the proportional valve 14 is adjusted electrohydraulically from its neutral position 19 into its first working position 21. At the same time, the solenoid valve 35 is excited so that the cartridge 34 blocks the tank line 24. The changeover valve 15 assumes its spring-centered blocking position 41.
  • the volume flow coming from the pump 24 flows into the cylinder space 12 via the control edge PA and the first working line 31.
  • the pressure medium displaced from the annular space 13 flows via the second working line 33, the control edge BT to the branch point 37 and further Via the bypass line 45 with the check valve 18 to the node 44 and further into the cylinder space 12 of the differential cylinder 11.
  • an overflow circuit is realized when the piston rod is extended, the volume flow coming from the pump 24 and the volume flow taken over from the annular space 13 being different unite at node 44 and flow together into cylinder space 12.
  • the piston rod in the differential cylinder 11 is retracted, for which purpose the proportional valve 14 is controlled in its second working position 22.
  • the volume flow coming from the pump 24 flows via the control edge PB into the annular space 13 of the cylinder 11.
  • a volume flow twice as large flows out of the cylinder space 12 through the first working line 31 due to the surface translation in the differential cylinder 11.
  • This volume flow is divided into a partial flow to the switching valve 15 and another partial flow to the proportional valve 14.
  • This partial flow causes a pressure difference at the measuring throttle 36, which acts on the changeover valve 15 via the control lines 38, 39 and adjusts it against spring force from the blocking position 41 into its working position 42.
  • the differential pressure-controlled changeover valve 15 controls a partial flow from the node 44 via the return line 43 directly to the tank 28, the size of this volume flow being proportional to the size of the pressure difference generated by the measuring throttle 36. Due to the double flow through the changeover valve 15, flow forces in the valve are balanced; furthermore, its nominal size can be kept correspondingly small.
  • the device 10 can now be designed so that at a pressure drop of approximately 5 bar at the measuring throttle 36 at maximum opening speed, half the volume flow from the cylinder space 12 in the differential cylinder 11 is controlled via the changeover valve 15 to the tank 28.
  • the functions of accelerating and braking when opening the mold are still guaranteed and are determined by the proportional valve 14 using its ramp technology.
  • the second check valve 18 in the bypass line 45 prevents pressure medium from flowing out of the cylinder space 12 bypassing the proportional valve 14 into the tank line 27.
  • This described division of the returning, double volume flow from the cylinder chamber 12 during the closing process avoids an undesirably strong return throttling at the proportional valve 14.
  • the measuring throttle 36 is arranged in the device 10 in a conduit in which volume flows can only flow back to the tank in one direction.
  • the proportional valve 14 With the device 10, only a simple volume flow is always conducted via the proportional valve 14 both when the piston rod is extended and when it is retracted.
  • the nominal size of this valve can accordingly be chosen to be small, which has a favorable effect, in particular on the costs, particularly in the case of large machines with large volume flows.
  • the check valve 16 only needs to be designed for a simple volume flow; can therefore have a correspondingly small nominal size. It is also advantageous if, in the device 10, the measuring throttle 36 with the cartridge 34 in the check valve 16 are structurally combined in a common housing.
  • the proportional valve 14 is equipped with zero relief in the neutral position 19; this prevents the lock cylinder 11 from drifting, e.g. B. when he occupies a position with an open shape.
  • FIG. 2 shows a second device 50, which differs from the first device 10 as follows, the same reference numerals being used for the same components.
  • the second device 50 uses a double-flow switch valve 51 with a single flow, which is designed here as a cartridge for block installation.
  • the changeover valve 51 works as a proportional throttle valve and, as before, lies in the return line 43 leading to the tank 28.
  • the measuring throttle 36 is connected into the first working line 31 so that it lies between the node 44 and the proportional valve 14 is coming.
  • a parallel branch line 52 is provided in the first working line 31, into which a third check valve 53 opening towards the node 44 is connected. The pressure difference caused by the measuring throttle 36 is passed via the control lines 38 and 39 to the changeover valve 51.
  • control line 39 is controlled by an electromagnetically adjustable pressure control valve 54 which, together with the changeover valve 51 and the throttle 56, enables a pilot-operated proportional pressure valve.
  • the pressure in the annular space 13 is secured by a second pressure valve 55.
  • the mode of operation of the second device 50 largely corresponds to that of the first device 10, reference being made to the following different points:
  • the check valve 53 causes a significantly lower flow resistance than the measuring throttle 36, which generates a pressure drop of about 5 bar at full opening speed of the differential cylinder 11. If this pressure drop is not considered to be a nuisance in some applications, the branch line 52 with check valve 53 can also be completely omitted in the case of a measuring throttle 36 located in the working line 31.
  • the pressure valve 54 is expediently designed as a proportional valve, so that different pressures can be programmed with it. In particular, the mold closing safety pressure and the closing pressure in the differential cylinder 11 and possibly other pressure functions, such as in a pressure cushion, can be regulated. An additional throttle 56 is provided in the control line 39 for these pressure functions.
  • the piston rod on the differential cylinder 11 When a mold is opened, the piston rod on the differential cylinder 11 must be retracted, for which purpose the proportional valve 14 in its second working position 22 guides the volume flow coming from the pump 24 into the annular space 13, the one coming out of the cylinder space 12 flowing volume flow at node 44 is divided again.
  • the measuring throttle 36 is now upstream of the proportional valve 14 in one of the partial flows and generates a pressure difference which actuates the changeover valve 51.
  • the proportional valve 14 is always flowed through only with the simple volume flow, so that no excessive return throttling occurs with a relatively small nominal size.
  • the throttle losses during the overflow circuit when the piston rod is extended are low and at the same time the differential cylinder 11 is well clamped.
  • superimposed pressure functions can be carried out with the changeover valve 51.
  • the check valve 16 is actuated by a solenoid valve 35 with a changed circuit symbol; this circuit symbol enables a better drainage of leak oil compared to FIG. 1.
  • This control of the cartridge 34 used in FIG. 2 can also be used in the first device 10 according to FIG.
  • valve elements can also be installed in the devices for additional functions.
  • a single-stage control valve can also be used.
  • a single-flow valve type can also be used in the device 10.
  • the advantages of the device are also present if a rotary drive is used as the hydraulic motor.
  • the present device is particularly suitable for clamping units of injection and blow molding machines.

Description

Stand der TechnikState of the art

Die Erfindung geht aus von einer Einrichtung zur Steuerung eines hydraulischen Motors nach der Gattung des Hauptanspruchs.The invention relates to a device for controlling a hydraulic motor according to the preamble of the main claim.

Es ist schon eine solche Einrichtung aus der DE-A-32 19 730 bekannt, bei der ein hydraulischer Differentialzylinder über ein elektrohydraulisches Regelventil ansteuerbar ist, das mit einem differenzdruckabhängig gesteuerten, proportional arbeitenden Umschaltventil zusammenarbeitet, welches über eine in vom Regelventil gesteuerten Volumenstrom liegende Meßdrossel ansteuerbar ist. Mit dieser Einrichtung ist zum hydraulischen Motor ein Volumenstrom analog steuerbar, dessen Größe die Nenngröße des Regelventils selbst erheblich übersteigt. Bei dem als Schließzylinder in einer Kunststoff-Spritzgießmaschine verwendeten Differentialzylinder wird beim Ausfahren der Kolbenstange eine Überstömschaltung realisiert, wobei der aus dem Ringraum abfließende Volumenstrom wenigstens teilweise in den Zylinderraum zurückgeführt wird. Andererseits wird beim Einfahren der Kolbenstange der aus dem Zylinderraum abfließende Volumenstrom geteilt, wobei über das Regelventil und das Umschaltventil jeweils nur ein einfacher Volumenstrom abgeführt wird, so daß eine erhöhte Rücklaufdrosselung am Regelventil vermieden wird. Bei dieser Einrichtung müssen somit in beiden Arbeitsrichtungen des Differentialzylinders im Regelventil selbst keine über dessen Nenngröße hinaus gehenden Volumenströme verarbeitet werden. Es kann nun aber in manchen Fällen von Nachteil sein, daß der beim Ausfahren der Kolbenstange aus dem Ringraum abfließende Volumenstrom so geteilt wird, daß der eine Teilstrom über das Regelventil zur Zulaufseite des Umschaltventils fließt, während der andere Teilstrom bereits stromaufwärts vom Regelventil abgezweigt und zum Umschaltventil geführt wird, wo sich beide Teilströme wieder vereinigen können und zur Zylinderseite geführt werden. Dies kann eine aufwendige Bauweise des Umschaltventils verursachen und zum anderen die Energieausnutzung beeinträchtigen. Ferner kann auch die bei der Überströmschaltung im Zulaufstrom liegende Meßdrossel unerwünschte Drosselverluste hervorrufen.Such a device is already known from DE-A-32 19 730, in which a hydraulic differential cylinder can be controlled via an electrohydraulic control valve, which cooperates with a proportional switching valve which is controlled as a function of the differential pressure and which has a measuring throttle located in a volume flow controlled by the control valve is controllable. With this device, a volume flow can be controlled analogously to the hydraulic motor, the size of which considerably exceeds the nominal size of the control valve itself. In the differential cylinder used as the locking cylinder in a plastic injection molding machine, an overflow circuit is implemented when the piston rod is extended, the volume flow flowing out of the annular space being at least partially returned to the cylinder space. On the other hand, when the piston rod is retracted, the volume flow flowing out of the cylinder space is divided, only a simple volume flow being discharged via the control valve and the changeover valve, so that an increased return throttling at the control valve is avoided. With this device, therefore, in both working directions of the differential cylinder in the control valve itself no volume flows beyond its nominal size have to be processed. In some cases, however, it can be disadvantageous that the volume flow flowing out of the annular space when the piston rod is extended is divided so that one partial flow flows via the control valve to the inlet side of the changeover valve, while the other partial flow branches off upstream from the control valve and to Changeover valve is guided, where both partial flows can combine again and are led to the cylinder side. This can cause a complex construction of the changeover valve and, on the other hand, impair the energy utilization. Furthermore, the measuring throttle located in the inflow flow in the overflow circuit can also cause undesirable throttle losses.

Vorteile der ErfindungAdvantages of the invention

Die erfindungsgemäße Einrichtung zur Steuerung eines hydraulischen Motors mit den kennzeichnenden Merkmalen des Hauptanspruchs hat demgegenüber den Vorteil, daß sie mit relativ geringem Aufwand und mit einfachen Bauelementen realisierbar ist und dabei unter Beibehaltung bisheriger Vorteile einen verlustleistungsarmen Betrieb ermöglicht. So lassen sich beim Betrieb des Differentialzylinders in Überströmschaltung die Verluste einer Meßdrossel in dem zum Motor fließenden Volumenstrom vermeiden. Ferner muß beim Betrieb mit Überströmschaltung kein Volumenstrom über das differenzdruckabhängig gesteuerte Umschaltventil strömen. Ferner ist der Motor beim Ausfahren der Kolbenstange hydraulisch gut eingespannt, da der aus dem Ringraum abfließende Volumenstrom von einer einzigen Steuerkante im Regelventil beherrscht wird und erst stromabwärts vom Regelventil dessen Zusammenführung mit einem Pumpen-Volumenstrom stattfindet.The device according to the invention for controlling a hydraulic motor with the characterizing features of the main claim has the advantage that it can be implemented with relatively little effort and with simple components and thereby enables low-loss operation while maintaining previous advantages. Thus, when the differential cylinder is operated in an overflow circuit, the losses of a measuring throttle in the volume flow flowing to the engine can be avoided. Furthermore, when operating with an overflow circuit, no volume flow has to flow via the changeover valve which is controlled as a function of the differential pressure. Furthermore, the engine is well clamped hydraulically when the piston rod is extended, since the volume flow flowing out of the annular space is dominated by a single control edge in the control valve and its merging with a pump volume flow only takes place downstream of the control valve.

Durch die in den Unteransprüchen aufgeführten Maßnahmen sind vorteilhafte Weiterbildungen und Verbesserungen der im Hauptanspruch angegebenen Einrichtung möglich. Besonders günstig ist es, wenn gemäß Anspruch 3 das Umschaltventil für eine doppelte Durchströmung ausgeführt wird. Damit lassen sich Strömungskräfte ausgleichen; zugleich kann die Nenngröße dieses Umschaltventils klein gehalten werden. Vorteilhaft ist ferner eine Ausbildung nach Anspruch 5, wodurch neben der günstigen Anordnung der Meßdrossel in einer Arbeitsleitung zwischen Regelventil und Differentialzylinder deren Drosselverluste im Überströmbetrieb vermieden werden können. Zweckmäßig ist es ferner, wenn gemäß Anspruch 6 das Umschaltventil für eine vorgesteuerte Druckregelfunktion verwendet wird.Advantageous further developments and improvements of the device specified in the main claim are possible through the measures listed in the subclaims. It when the switching valve is designed for a double flow is particularly favorable. This allows flow forces to be balanced; at the same time, the nominal size of this changeover valve can be kept small. A design according to claim 5 is also advantageous, as a result of which, in addition to the favorable arrangement of the measuring throttle in a working line between control valve and differential cylinder, its throttling losses can be avoided in overflow operation. It is also expedient if, according to claim 6, the changeover valve is used for a pilot-controlled pressure control function.

Zeichnungdrawing

Zwei Ausführungsbeispiele der Erfindung sind in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert. Es zeigen Figur 1 und Figur 2 eine erste bzw. zweite Einrichtung zur Steuerung eines hydraulischen Motors, jeweils in vereinfachter Darstellung.Two embodiments of the invention are shown in the drawing and explained in more detail in the following description. 1 and 2 show a first and a second device for controlling a hydraulic motor, each in a simplified representation.

Beschreibung der AusführungsbeispieleDescription of the embodiments

Die Figur 1 zeigt eine Einrichtung 10 zur Steuerung eines hydraulischen Motors, der hier als Differential-Zylinder 11 ausgebildet ist, wie er zum Beispiel als Schließzylinder in einer Kunststoff-Spritzgießmaschine zum Betätigen einer Form verwendet wird. Der Differentialzylinder 11 hat einen seiner großen wirksamen Fläche zugeordneten Zylinderraum 12 und einen der kleineren wirksamen Fläche zugeordneten Ringraum 13, wobei deren Flächenverhältnis wie 2 : 1 ausgebildet ist.FIG. 1 shows a device 10 for controlling a hydraulic motor, which is designed here as a differential cylinder 11, as is used, for example, as a locking cylinder in a plastic injection molding machine for actuating a mold. The differential cylinder 11 has a cylinder space 12 assigned to its large effective area and an annular space 13 assigned to the smaller effective area, the area ratio of which is 2: 1.

Die Einrichtung 10 weist im wesentlichen als Bauelemente ein als elektrohydraulisches Regelventil ausgebildetes Proportionalventil 14, ein differenzdruckabhängig gesteuertes Umschaltventil 15, ein vorgesteuertes Sperrventil 16, sowie zwei Rückschlagventile 17 und 18 auf.The device 10 essentially has, as components, a proportional valve 14 designed as an electrohydraulic control valve, a changeover valve 15 controlled as a function of differential pressure, a pilot-operated check valve 16, and two check valves 17 and 18.

Das an sich bekannte Proportionalventil 14 ist zweistufig ausgebildet, in einen nicht näher gezeichneten Regelkreis geschaltet und weist neben einer federzentrierten Neutralstellung 19 mit zugehöriger Nullentlastung eine erste Arbeitsstellung 21 sowie eine zweite Arbeitsstellung 22 auf. Ein mit P bezeichneter Zulaufanschluß 23 wird von einer Pumpe 24 über eine Zulaufleitung 25 mit Druckmittel versorgt, wobei in die Zulaufleitung 25 das erste Rückschlagventil 17 geschaltet ist. Ein mit T bezeichneter Rücklaufanschluß 26 steht über eine Tankleitung 27, in die das Sperrventil 16 geschaltet ist, mit einem Tank 28 in Verbindung. Von einem mit A bezeichneten, ersten Motoranschluß 29 führt eine erste Arbeitsleitung 31 in den Zylinderraum 12 des Differentialzylinders 11. In entsprechender Weise ist ein mit B bezeichneter zweiter Motoranschluß 32 über eine zweite Arbeitsleitung 33 mit dem Ringraum 13 verbunden.The proportional valve 14, which is known per se, has a two-stage design, is switched into a control circuit (not shown in more detail) and, in addition to a spring-centered neutral position 19 with associated zero relief, has a first working position 21 and a second working position 22. An inlet connection 23 designated P is supplied with pressure medium by a pump 24 via an inlet line 25, the first check valve 17 being connected into the inlet line 25. A return connection designated T is connected to a tank 28 via a tank line 27, into which the check valve 16 is connected. A first working line 31 leads from a first motor connection 29, designated A, into the cylinder space 12 of the differential cylinder 11. In a corresponding manner, a second motor connection 32, designated B, is connected to the annular space 13 via a second working line 33.

Das in die Tankleitung 27 geschaltete Sperrventil 16 besteht aus einer 2/2-Patrone 34, die hydraulisch von einem Magnetventil 35 vorgesteuert wird. Das Sperrventil 16 ist als normal offenes Ventil ausgebildet. Ferner ist in die Tankleitung 27 stromaufwärts vom Sperrventil 16 eine Meßdrossel 36 geschaltet, welche in der Tankleitung 27 stromabwärts von einem Abzweigpunkt 37 liegt. Das von der Meßdrossel 36 in der Tankleitung 27 verursachte Druckgefälle wird über zwei Steuerleitungen 38, 39 abgegriffen und dient zur differenzdruckabhängigen Steuerung des Umschaltventils 15.The check valve 16 connected into the tank line 27 consists of a 2/2 cartridge 34, which is hydraulically piloted by a solenoid valve 35. The check valve 16 is designed as a normally open valve. Furthermore, a measuring throttle 36 is connected in the tank line 27 upstream from the shut-off valve 16, which is located in the tank line 27 downstream from a branch point 37. The pressure drop caused by the measuring throttle 36 in the tank line 27 is tapped via two control lines 38, 39 and is used for the differential pressure-dependent control of the changeover valve 15.

Bei dem differenzdruckabhängig gesteuerten Umschaltventil 15 handelt es sich um ein an sich bekanntes Drosselventil mit doppelter Durchströmung für Strömungskraftkompensation. Es weist eine federzentrierte Sperrstellung 41 auf, in der alle Anschlüsse abgesperrt sind und ist in eine druckabhängige Arbeitsstellung 42 auslenkbar, in der die Größe des durchfließenden Druckmittelstroms proportional zur Größe der anliegenden Druckdifferenz gesteuert wird. Das Umschaltventil 15 ist in eine Rücklaufleitung 43 geschaltet, welche den Zylinderraum 12 des Differentialzylinders 11 unmittelbar mit dem Tank 28 verbindet, wobei diese Rücklaufleitung 43 zum Anschließen des Umschaltventils 15 teilweise in parallelen Abschnitten geführt ist.The switchover valve 15, which is controlled as a function of the differential pressure, is a known throttle valve with double flow for flow force compensation. It has a spring-centered blocking position 41 in which all connections are blocked off and can be deflected into a pressure-dependent working position 42 in which the size of the pressure medium flow flowing through is controlled in proportion to the size of the pressure difference present. The changeover valve 15 is connected in a return line 43, which connects the cylinder space 12 of the differential cylinder 11 directly to the tank 28, this return line 43 for connecting the changeover valve 15 being partially guided in parallel sections.

Diese Rücklaufleitung 43 mit ihrem zum Schaltventil 15 Anschluß P geführten Abschnitt und die erste Arbeitsleitung 31 haben einen gemeinsamen Knotenpunkt 44, der über eine Bypassleitung 45 mit dem Abzweigpunkt 37 in Verbindung steht, so daß auf diese Weise der Rücklaufanschluß 26 des Proportionalventils 14 unter Umgehung von Umschaltventil 15, Sperrventil 16 und Meßdrossel 36 unmittelbar mit dem Zylinderraum 12 in Verbindung steht. In diese Bypassleitung 45 ist das zweite Rückschlagventil 18 so geschaltet daß es zum Zylinderraum 12 hin öffnet.This return line 43 with its section leading to the switching valve 15 port P and the first working line 31 have a common node 44 which is connected via a bypass line 45 to the branch point 37, so that in this way the return port 26 of the proportional valve 14 bypassing Changeover valve 15, check valve 16 and measuring throttle 36 is connected directly to the cylinder chamber 12. In this bypass line 45, the second check valve 18 is switched so that it opens towards the cylinder chamber 12.

Die Wirkungsweise der Einrichtung 10 wird wie folgt erläutert:
Zum Schließen einer Form in einer Kunststoff-Spritzgießmaschine wird die Kolbenstange des Differentialzylinders 11 ausgefahren. Zu diesem Zweck wird das Proportionalventil 14 aus seiner Neutralstellung 19 elektrohydraulisch in seine erste Arbeitstellung 21 verstellt. Zugleich wird das Magnetventil 35 erregt, so daß die Patrone 34 die Tankleitung 24 blockiert. Das Umschaltventil 15 nimmt seine federzentrierte Sperrstellung 41 ein.The operation of the device 10 is explained as follows:
To close a mold in a plastic injection molding machine, the piston rod of the differential cylinder 11 is extended. For this purpose, the proportional valve 14 is adjusted electrohydraulically from its neutral position 19 into its first working position 21. At the same time, the solenoid valve 35 is excited so that the cartridge 34 blocks the tank line 24. The changeover valve 15 assumes its spring-centered blocking position 41.

In der ersten Arbeitsstellung 21 fließt der von der Pumpe 24 kommende Volumenstrom über die Steuerkante P-A und die erste Arbeitsleitung 31 in den Zylinderraum 12. Gleichzeitig fließt das aus dem Ringraum 13 verdrängte Druckmittel über die zweite Arbeitsleitung 33, die Steuerkante B-T zum Abzweigpunkt 37 und weiter über die Bypassleitung 45 mit dem Rückschlagventil 18 zum Knotenpunkt 44 und weiter in den Zylinderraum 12 des Differentialzylinders 11. Auf diese Weise wird beim Ausfahren der Kolbenstange eine Überströmschaltung realisiert, wobei der von der Pumpe 24 kommende Volumenstrom und der aus dem Ringraum 13 übernommene Volumenstrom sich im Knotenpunkt 44 vereinen und gemeinsam in den Zylinderraum 12 strömen. Durch diese Zusammenführung der beiden Volumenströme am Knotenpunkt 44 wird erreicht, daß bei diesem Schließvorgang mit Hilfe der Steuerkante B-T im Proportionalventil 14 der Differentialzylinder 11 stets gut eingespannt ist. Ferner wird mit dieser Art der Überströmschaltung beim Schließen erreicht, daß das Proportionalventil 14 nur vom einfachen Volumenstrom durchströmt wird, so daß die Nenngröße dieses Ventils entsprechend niedrig gewählt werden kann. Erst wenn die Form durch den Differentialzylinder 11 zugefahren ist, wird die Patrone 34 wieder geöffnet und damit der Ringraum 13 entlastet. Die Funktionen Beschleunigen und Bremsen lassen sich somit beim Schließvorgang mit Hilfe des elektrohydraulisch gesteuerten Proportionalventils 14 in einwandfreier Weise durchführen.In the first working position 21, the volume flow coming from the pump 24 flows into the cylinder space 12 via the control edge PA and the first working line 31. At the same time, the pressure medium displaced from the annular space 13 flows via the second working line 33, the control edge BT to the branch point 37 and further Via the bypass line 45 with the check valve 18 to the node 44 and further into the cylinder space 12 of the differential cylinder 11. In this way, an overflow circuit is realized when the piston rod is extended, the volume flow coming from the pump 24 and the volume flow taken over from the annular space 13 being different unite at node 44 and flow together into cylinder space 12. This combination of the two volume flows at the node 44 ensures that the differential cylinder 11 is always firmly clamped in this closing process with the aid of the control edge B-T in the proportional valve 14. Furthermore, with this type of overflow circuit when closing, the proportional valve 14 is only flowed through by the simple volume flow, so that the nominal size of this valve can be chosen to be correspondingly low. Only when the mold is closed by the differential cylinder 11, the cartridge 34 is opened again and thus the annular space 13 is relieved. The functions of acceleration and braking can thus be carried out in a faultless manner during the closing process with the aid of the electrohydraulically controlled proportional valve 14.

Zum Öffnen einer Werkzeugform wird die Kolbenstange im Differentialzylinder 11 eingefahren, wozu das Proportionalventil 14 in seine zweite Arbeitsstellung 22 gesteuert wird. Der von der Pumpe 24 kommende Volumenstrom fließt über die Steuerkante P-B in den Ringraum 13 des Zylinders 11. Gleichzeitig fließt durch die Flächenübersetzung im Differentialzylinder 11 aus dem Zylinderraum 12 ein doppelt so großer Volumenstrom über die erste Arbeitsleitung 31 ab. Am Knotenpunkt 44 wird dieser Volumenstrom geteilt in einen Teilstrom zum Umschaltventil 15 und in einen anderen Teilstrom zum Proportionalventil 14. Der Teilstrom zum Proportionalventil 14 fließt über die Steuerkante A-T in die Tankleitung 27 ab, wobei er die Meßdrossel 36 und das aufgesteuerte Sperrventil 16 durchströmt. Dieser Teilstrom verursacht an der Meßdrossel 36 eine Druckdifferenz, welche über die Steuerleitungen 38, 39 auf das Umschaltventil 15 einwirkt und dieses gegen Federkraft aus der Sperrstellung 41 heraus in seine Arbeitsstellung 42 verstellt. Das differenzdruckgesteuerte Umschaltventil 15 steuert dabei vom Knotenpunkt 44 einen Teilstrom über die Rücklaufleitung 43 unmittelbar zum Tank 28, wobei die Größe dieses Volumenstromes proportional ist zur Größe der von der Meßdrossel 36 erzeugten Druckdifferenz. Durch die doppelte Durchströmung des Umschaltventils 15 werden Strömungskräfte im Ventil ausgeglichen; ferner kann seine Nenngröße entsprechend klein gehalten werden. Die Einrichtung 10 kann nun so ausgelegt werden, daß bei einem Druckgefälle von ungefähr 5 bar an der Meßdrossel 36 bei maximaler Öffnungsgeschwindigkeit der halbe Volumenstrom aus dem Zylinderraum 12 im Differentialzylinder 11 über das Umschaltventil 15 zum Tank 28 gesteuert wird. Die Funktionen Beschleunigen und Bremsen beim Öffnen der Werkzeugform sind weiterhin gewährleistet und werden vom Proportionalventil 14 durch dessen Rampentechnik bestimmt. Das zweite Rückschlagventil 18 in der Bypassleitung 45 verhindert dabei, daß Druckmittel aus dem Zylinderraum 12 unter Umgehung des Proportionalventils 14 in die Tankleitung 27 abströmen kann. Durch diese geschilderte Aufteilung des zurückfließenden, doppelten Volumenstromes aus dem Zylinderraum 12 während des Schließvorganges wird eine unerwünscht starke Rücklaufdrosselung am Proportionalventil 14 vermieden. Die Meßdrossel 36 ist bei der Einrichtung 10 in einem Leitungsstrang angeordnet in dem Volumenströme nur in einer Richtung zum Tank zurückfließen können.To open a mold, the piston rod in the differential cylinder 11 is retracted, for which purpose the proportional valve 14 is controlled in its second working position 22. The volume flow coming from the pump 24 flows via the control edge PB into the annular space 13 of the cylinder 11. At the same time, a volume flow twice as large flows out of the cylinder space 12 through the first working line 31 due to the surface translation in the differential cylinder 11. At the This volume flow is divided into a partial flow to the switching valve 15 and another partial flow to the proportional valve 14. This partial flow causes a pressure difference at the measuring throttle 36, which acts on the changeover valve 15 via the control lines 38, 39 and adjusts it against spring force from the blocking position 41 into its working position 42. The differential pressure-controlled changeover valve 15 controls a partial flow from the node 44 via the return line 43 directly to the tank 28, the size of this volume flow being proportional to the size of the pressure difference generated by the measuring throttle 36. Due to the double flow through the changeover valve 15, flow forces in the valve are balanced; furthermore, its nominal size can be kept correspondingly small. The device 10 can now be designed so that at a pressure drop of approximately 5 bar at the measuring throttle 36 at maximum opening speed, half the volume flow from the cylinder space 12 in the differential cylinder 11 is controlled via the changeover valve 15 to the tank 28. The functions of accelerating and braking when opening the mold are still guaranteed and are determined by the proportional valve 14 using its ramp technology. The second check valve 18 in the bypass line 45 prevents pressure medium from flowing out of the cylinder space 12 bypassing the proportional valve 14 into the tank line 27. This described division of the returning, double volume flow from the cylinder chamber 12 during the closing process avoids an undesirably strong return throttling at the proportional valve 14. The measuring throttle 36 is arranged in the device 10 in a conduit in which volume flows can only flow back to the tank in one direction.

Bei der Einrichtung 10 wird sowohl beim Ausfahren wie auch beim Einfahren der Kolbenstange im Differentialzylinder 11 stets nur ein einfacher Volumenstrom über das Proportionalventil 14 geführt. Die Nenngröße dieses Ventils kann dementsprechend klein gewählt werden, was besonders bei großen Maschinen mit großen Volumenströmen sich günstig, insbesondere auf die Kosten, auswirkt. Ebenso muß das Sperrventil 16 nur auf einen einfachen Volumenstrom ausgelegt werden; kann also eine entsprechend kleine Nenngröße aufweisen. Günstig ist es ferner, wenn bei der Einrichtung 10 die Meßdrossel 36 mit der Patrone 34 im Sperrventil 16 baulich in einem gemeinsamen Gehäuse zusammengefaßt werden. Weiterhin ist es vorteilhaft, daß das Proportionalventil 14 in Neutralstellung 19 mit Nullentlastung ausgerüstet ist; dadurch wird ein Driften des Schließzylinders 11 verhindert, z. B. wenn er eine Stellung mit geöffneter Form einnimmt.With the device 10, only a simple volume flow is always conducted via the proportional valve 14 both when the piston rod is extended and when it is retracted. The nominal size of this valve can accordingly be chosen to be small, which has a favorable effect, in particular on the costs, particularly in the case of large machines with large volume flows. Likewise, the check valve 16 only needs to be designed for a simple volume flow; can therefore have a correspondingly small nominal size. It is also advantageous if, in the device 10, the measuring throttle 36 with the cartridge 34 in the check valve 16 are structurally combined in a common housing. Furthermore, it is advantageous that the proportional valve 14 is equipped with zero relief in the neutral position 19; this prevents the lock cylinder 11 from drifting, e.g. B. when he occupies a position with an open shape.

Die Figur 2 zeigt eine zweite Einrichtung 50, die sich von der ersten Einrichtung 10 wie folgt unterscheidet, wobei für gleiche Bauelemente gleiche Bezugszeichen verwendet werden.FIG. 2 shows a second device 50, which differs from the first device 10 as follows, the same reference numerals being used for the same components.

Anstelle des doppelt durchströmten Umschaltventils 15 nach Figur 1 verwendet die zweite Einrichtung 50 ein einfach durchströmtes 2-Wege-Umschaltventil 51, das hier als Patrone für Blockeinbau ausgebildet ist. Das Umschaltventil 51 arbeitet als Proportional-Drosselventil und liegt wie bisher in der zum Tank 28 führenden Rücklaufleitung 43. Die Meßdrossel 36 ist bei der zweiten Einrichtung 50 in die erste Arbeitsleitung 31 geschaltet, so daß sie zwischen dem Knotenpunkt 44 und dem Proportionalventil 14 zu liegen kommt. Für eine Umgehung der Meßdrossel 36 ist in der ersten Arbeitsleitung 31 eine parallele Zweigleitung 52 vorgesehen, in die ein zum Knotenpunkt 44 hin öffnendes, drittes Rückschlagventil 53 geschaltet ist. Die von der Meßdrossel 36 verursachte Druckdifferenz wird über die Steuerleitungen 38 bzw. 39 auf das Umschaltventil 51 geleitet. Zudem wird der Druck in der Steuerleitung 39 über ein elektromagnetisch verstellbares Druckregelventil 54 gesteuert das zusammen mit dem Umschaltventil 51 und der Drossel 56 ein vorgesteuertes Proportional-Druckventil ermöglicht. Der Druck im Ringraum 13 ist über ein zweites Druckventil 55 abgesichert.Instead of the double-flow switch valve 15 according to FIG. 1, the second device 50 uses a double-flow switch valve 51 with a single flow, which is designed here as a cartridge for block installation. The changeover valve 51 works as a proportional throttle valve and, as before, lies in the return line 43 leading to the tank 28. In the second device 50, the measuring throttle 36 is connected into the first working line 31 so that it lies between the node 44 and the proportional valve 14 is coming. To bypass the measuring throttle 36, a parallel branch line 52 is provided in the first working line 31, into which a third check valve 53 opening towards the node 44 is connected. The pressure difference caused by the measuring throttle 36 is passed via the control lines 38 and 39 to the changeover valve 51. In addition, the pressure in the control line 39 is controlled by an electromagnetically adjustable pressure control valve 54 which, together with the changeover valve 51 and the throttle 56, enables a pilot-operated proportional pressure valve. The pressure in the annular space 13 is secured by a second pressure valve 55.

Die Wirkungsweise der zweiten Einrichtung 50 entspricht weitgehend derjenigen der ersten Einrichtung 10, wobei auf folgende unterschiedliche Punkte hingewiesen wird:
Zum Schließen einer Form muß die Kolbenstange in der ersten Arbeitsstellung 21 des Proportionalventils 14 ausgefahren werden, wobei der zum Zylinderraum 12 fließende Volumenstrom in der ersten Arbeitsleitung 31 über die Zweitleitung 52 geführt wird. Das Rückschlagventil 53 verursacht dabei einen wesentlich geringeren Durchflußwiderstand als die Meßdrossel 36, die bei voller Öffnungsgeschwindigkeit des Differentialzylinders 11 einen Druckabfall von ca. 5 bar erzeugt. Sofern dieser Druckabfall in manchen Anwendungsfällen nicht als störend angesehen wird, kann auch bei einer in der Arbeitsleitung 31 liegenden Meßdrossel 36 die Zweigleitung 52 mit Rückschlagventil 53 vollständig entfallen. Das Druckventil 54 ist zweckmäßig als Proportionalventil ausgebildet, so daß mit ihm unterschiedliche Drücke programmierbar sind. Insbesondere kann damit der Formschließ-Sicherungsdruck sowie der Schließdruck im Differentialzylinder 11 und gegebenenfalls andere Druckfunktionen, wie zum Beispiel in einem Druckkissen, geregelt werden. Für diese Druckfunktionen ist in der Steuerleitung 39 eine zusätzliche Drossel 56 vorgesehen.The mode of operation of the second device 50 largely corresponds to that of the first device 10, reference being made to the following different points:
To close a mold, the piston rod must be extended in the first working position 21 of the proportional valve 14, the volume flow flowing to the cylinder chamber 12 being conducted in the first working line 31 via the second line 52. The check valve 53 causes a significantly lower flow resistance than the measuring throttle 36, which generates a pressure drop of about 5 bar at full opening speed of the differential cylinder 11. If this pressure drop is not considered to be a nuisance in some applications, the branch line 52 with check valve 53 can also be completely omitted in the case of a measuring throttle 36 located in the working line 31. The pressure valve 54 is expediently designed as a proportional valve, so that different pressures can be programmed with it. In particular, the mold closing safety pressure and the closing pressure in the differential cylinder 11 and possibly other pressure functions, such as in a pressure cushion, can be regulated. An additional throttle 56 is provided in the control line 39 for these pressure functions.

Beim Öffnen einer Form muß die Kolbenstange am Differentialzylinder 11 eingefahren werden, wozu das Proportionalventil 14 in seiner zweiten Arbeitsstellung 22 den von der Pumpe 24 kommenden Volumenstrom in den Ringraum 13 führt, wobei der aus dem Zylinderraum 12 abfließende Volumenstrom am Knotenpunkt 44 wieder geteilt wird. Die Meßdrossel 36 liegt nun stromaufwärts vom Proportionalventil 14 in einem der Teilströme und erzeugt eine Druckdifferenz, welche das Umschaltventil 51 betätigt.When a mold is opened, the piston rod on the differential cylinder 11 must be retracted, for which purpose the proportional valve 14 in its second working position 22 guides the volume flow coming from the pump 24 into the annular space 13, the one coming out of the cylinder space 12 flowing volume flow at node 44 is divided again. The measuring throttle 36 is now upstream of the proportional valve 14 in one of the partial flows and generates a pressure difference which actuates the changeover valve 51.

Somit wird auch bei der zweiten Einrichtung 50 in beiden Bewegungsrichtungen des Differentialzylinders 11 das Proportionalventil 14 stets nur mit dem einfachen Volumenstrom durchströmt, so daß keine überhöhte Rücklaufdrosselung bei relativ kleiner Nenngröße auftritt. Zudem sind die Drosselverluste während der Überstömschaltung beim Ausfahren der Kolbenstange gering und zugleich der Differentialzylinder 11 gut eingespannt. Fernerhin lassen sich mit dem Umschaltventil 51 überlagerte Druckfunktionen durchführen.Thus, in the second device 50 in both directions of movement of the differential cylinder 11, the proportional valve 14 is always flowed through only with the simple volume flow, so that no excessive return throttling occurs with a relatively small nominal size. In addition, the throttle losses during the overflow circuit when the piston rod is extended are low and at the same time the differential cylinder 11 is well clamped. Furthermore, superimposed pressure functions can be carried out with the changeover valve 51.

Bei der zweiten Einrichtung 50 wird die Ansteuerung des Sperrventils 16 durch ein Magnetventil 35 mit geändertem Schaltsymbol vorgenommen; dieses Schaltsymbol ermöglicht ein besseres Abfließen von Lecköl im Vergleich zu Figur 1. Diese in Figur 2 verwendete Ansteuerung der Patrone 34 ist auch bei der ersten Einrichtung 10 nach Figur 1 anwendbar.In the second device 50, the check valve 16 is actuated by a solenoid valve 35 with a changed circuit symbol; this circuit symbol enables a better drainage of leak oil compared to FIG. 1. This control of the cartridge 34 used in FIG. 2 can also be used in the first device 10 according to FIG.

Selbstverständlich sind an den gezeigten Ausführungsformen Änderungen möglich, ohne vom Gedanken der Erfindung abzuweichen. So können in die Einrichtungen für zusätzliche Funktionen auch zusätzliche Ventilelemente eingebaut werden. Anstelle des zweistufigen Proportionalventils kann auch ein einstufiges Regelventil verwendet werden. Anstelle des doppelt durchströmten Umschaltventils 15 ist in der Einrichtung 10 auch eine einfach durchströmte Ventilbauart verwendbar. Die Vorteile der Einrichtung sind auch dann gegeben, wenn als hydraulischer Motor ein Drehantrieb verwendet wird. Vorliegende Einrichtung eignet sich besonders für Schließeinheiten von Spritz- und Blasmaschinen.Of course, changes are possible to the embodiments shown without departing from the spirit of the invention. In this way, additional valve elements can also be installed in the devices for additional functions. Instead of the two-stage proportional valve, a single-stage control valve can also be used. Instead of the double-flow switch valve 15, a single-flow valve type can also be used in the device 10. The advantages of the device are also present if a rotary drive is used as the hydraulic motor. The present device is particularly suitable for clamping units of injection and blow molding machines.

Claims (9)

  1. Device (10; 50) for controlling a hydraulic motor (11), in particular a closing cylinder of a plastic injection moulding machine, in which device the motor is constructed as a differential cylinder with annular space (13) and cylinder space (12) and can be actuated via an electrohydraulic control valve (14), and with a metering orifice (36) which, at least during the emptying of the cylinder space (12), is connected into a first volume stream fed via the control valve (14) and, at the same time, produces a pressure difference with which a change-over valve (15; 51) which is controlled as a function of differential pressure, operates proportionally and, during the emptying of the cylinder space (12), directs to the tank (28) a second volume stream which is fed in parallel to the first volume stream, and with means for an overflow circuit for feeding back a volume stream which is flowing off out of the annular space (13) into the cylinder space (12) which is pressurized during this process, characterized in that a shut-off valve (16) is connected into a tank line (27) which is led from the return connection (26) of the control valve (14) to the tank (28), and in that a bypass line (45) which bypasses the metering orifice (36) and the change-over valve (15; 51) is led to the cylinder space (12) from the return connection (26), a non-return valve (18) which shuts off with respect to the return connection (26) being arranged in the said bypass line (45).
  2. Device according to Claim 1, characterized in that the metering orifice (36) is connected into the tank line (27) between control valve (14) and shut-off valve (16).
  3. Device according to Claim 1 or 2, characterized in that the change-over valve is formed as a throttle valve (15) with a double through-flow.
  4. Device according to Claim 1, characterized in that the metering orifice (36) is connected into a working line (31) which leads from the control valve (14) to the cylinder space (12) of the differential cylinder (11).
  5. Device according to Claim 4, characterized in that the working line (31) has a branch line (52) which runs parallel to the metering orifice (36) and into which a non-return valve (53) which opens with respect to the cylinder space (12) is connected.
  6. Device according to one of Claims 4 and 5, characterized in that a pressure valve (54) is provided, which controls the pressure in the working line (31) leading to the cylinder space (12), is in particular adjustable and interacts with the change-over valve (51) for a superimposed, pilot controlled pressure function.
  7. Device according to one of Claims 4 to 6, characterized in that the change-over valve (51) is realized as a two-way cartridge with a single through-flow.
  8. Device according to one or more of Claims 1 to 7, characterized in that the first working line (31), the bypass line (45) and the return line (43) form a node (44) in the region between change-over valve (15) and cylinder space (12).
  9. Device according to one of Claims 1 to 8, characterized in that the control valve (14) has a zero pressure balance in its neutral position (19).
EP91110125A 1990-06-27 1991-06-20 Control device for a hydraulic motor Expired - Lifetime EP0464481B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4020451A DE4020451A1 (en) 1990-06-27 1990-06-27 DEVICE FOR CONTROLLING A HYDRAULIC ENGINE
DE4020451 1990-06-27

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EP0464481A1 EP0464481A1 (en) 1992-01-08
EP0464481B1 true EP0464481B1 (en) 1995-02-01

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EP91110125A Expired - Lifetime EP0464481B1 (en) 1990-06-27 1991-06-20 Control device for a hydraulic motor

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DE (2) DE4020451A1 (en)
ES (1) ES2068435T3 (en)

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DE102021120713A1 (en) 2020-08-19 2022-03-10 Engel Austria Gmbh Hydraulic drive device for a shaping machine

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DE102021120713A1 (en) 2020-08-19 2022-03-10 Engel Austria Gmbh Hydraulic drive device for a shaping machine

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EP0464481A1 (en) 1992-01-08
DE4020451A1 (en) 1992-01-02
ES2068435T3 (en) 1995-04-16
DE59104462D1 (en) 1995-03-16

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