EP0376023B1 - Electrohydraulic proportional valve - Google Patents

Electrohydraulic proportional valve Download PDF

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Publication number
EP0376023B1
EP0376023B1 EP89122724A EP89122724A EP0376023B1 EP 0376023 B1 EP0376023 B1 EP 0376023B1 EP 89122724 A EP89122724 A EP 89122724A EP 89122724 A EP89122724 A EP 89122724A EP 0376023 B1 EP0376023 B1 EP 0376023B1
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EP
European Patent Office
Prior art keywords
control
valve
proportional directional
auxiliary
connection
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
EP89122724A
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German (de)
French (fr)
Other versions
EP0376023A2 (en
EP0376023A3 (en
Inventor
Eckard Schuttenberg
Berthold Dipl.-Ing. Pfuhl (Fh)
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication date
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Publication of EP0376023A3 publication Critical patent/EP0376023A3/en
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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
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
    • F15B13/042—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated by fluid pressure
    • F15B13/043—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated by fluid pressure with electrically-controlled pilot 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
    • F15B20/00—Safety arrangements for fluid actuator systems; Applications of safety devices in fluid actuator systems; Emergency measures for fluid actuator systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/355—Pilot pressure 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
    • F15B2211/60—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
    • 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
    • F15B2211/67—Methods for controlling pilot pressure

Definitions

  • the invention is based on an electrohydraulic proportional directional valve according to the preamble of the main claim.
  • this proportional valve In addition to the four main connections A, B, P, T, this proportional valve also has control connections X and Y for external control oil supply and discharge in the main valve. There are also auxiliary connections C1 and C2 in the main valve, but these are used for the function of the load tap for the pressure compensator.
  • This proportional valve can therefore not meet any further safety requirements such as those required by professional associations or accident prevention regulations for hydraulic machines and systems in the safety area. Also, in special applications, this proportional valve can be too slow in the event of an emergency stop because the main spool is reset by the springs in the main valve, which can only exert a restoring force corresponding to a few bar pressure and the pressure medium must flow through the small cross-sections of the pilot valve .
  • the electrohydraulic proportional directional control valve according to the invention with the characterizing features of the main claim has the advantage that it can meet diverse security requirements with relatively little effort.
  • the dynamic behavior can also be considerably improved if the resetting of the main control spool is supported hydraulically by the spring forces by an intermediate pressure in the pilot control circuit.
  • the measures listed in the subclaims enable advantageous developments and improvements of the proportional directional control valve specified in the main claim.
  • Particularly advantageous embodiments result in a design according to claims 2 to 4, whereby a particularly simple and inexpensive solution can be achieved.
  • the standard version can be used as the housing for the main control valve, in which the auxiliary connections are available per se, but have previously been used for another function.
  • a relatively small valve can be used as the switching valve, which only has to have the same nominal size as the regulating pilot valve, ie the switching valve must meet the flow of the pilot valve without increasing the pressure difference. Large-volume safety valves in the work lines can therefore be avoided.
  • electrical position indicators can be arranged on the main control valve as well as on the pilot valve in the case of very high safety requirements.
  • the main control spool can still be equipped with a leakage oil drain if the connected working cylinder is to be prevented from drifting. It is also advantageous if the tapping of the reliefs is incorporated directly in the main control slide, that is to say in an actuator which determines the flow.
  • a design according to claim 12 is also particularly expedient, as a result of which pressure build-up in a control chamber can be prevented particularly effectively. Tapping the relief directly in the control oil supply allows a particularly compact solution. This self-monitoring of the valve also guarantees a high level of safety. Further particularly advantageous configurations result from the remaining claims, the description and the drawing.
  • FIG. 1 shows a first electrohydraulic proportional directional control valve in a simplified representation and partly in longitudinal section
  • FIG. 1a shows the switching symbol of the pilot stage in FIG. 1
  • FIGS. 2 to 6 different switching valves for use with the first proportional directional control valve according to FIG. 1 to implement different safety requirements
  • FIG. 7 shows a longitudinal section by a part of a second proportional directional control valve with a change in the tapping of the relief in the control circuit compared to FIG. 1
  • FIG. 8 a partial section through a third exemplary embodiment.
  • FIG. 1 shows a simplified representation of an electrohydraulic proportional directional valve 10, which is used to control a double-acting working cylinder 11.
  • the proportional directional control valve 10 essentially consists of a hydraulically controlled main control valve 12, an electrically controlled pilot control valve 13 and a switching valve 14 connected to the main control valve 12.
  • Main control valve 12 and attached pilot valve 13 are known per se with regard to their basic structure from the literature reference mentioned at the beginning, to which reference is expressly made.
  • the proportional main control valve 12 is designed as a 4/3-way valve with four controlled main connections A, B, P and T and a main control spool 17 which can be moved continuously in three switching positions.
  • the main control slide 17 is in the housing 15 in one Slider bore 18 guided tight and sliding.
  • the slide bore 18 penetrates a centrally located inlet chamber 19, which is connected to the main connection P, two adjacent motor chambers 21, 22, which are connected to the main connections A and B, and two return chambers 23 and 24, which are connected to the main connection T. .
  • the main port P is supplied in a manner not shown by a pump with pressure medium, while the main port T is relieved to the tank.
  • the two sides of the double-acting working cylinder 11 are connected to the main connections A and B.
  • the main control slide 17 projects with its front ends 25, 26 into a control chamber 27, 28, which each receive a spring 29, 31 to form a double-acting resetting device 32 for the main control slide 17.
  • a control chamber 27, 28 By pressurizing a control chamber 27, 28 while simultaneously relieving pressure on the other control chamber 28, 27, the main control slide 17 can be deflected in both directions from its drawn central position against the force of the resetting device 32.
  • the pilot valve 13 is designed as a 4/4-way valve, the control functions of which can be found in the associated, simplified illustration according to FIG. 1a.
  • the pilot valve 13 has four controlled connections A, B, P, T and a pilot spool 33, which can be controlled by the single proportional magnet 16 against the force of a spring 34 in four switching positions 35, 36, 37 and 38.
  • the switch position 37 is designed as a neutral control position in which all four connections A, B, P, T of the pilot valve 13 are closed. From this neutral control position, the pilot spool 33 can be transferred into the two working positions 38 and 36, respectively, by correspondingly controlling the proportional magnet 16, in which one of the connections A, B is alternately connected to the connection P, while the other connection B, A to Tank connection T is relieved.
  • the proportional magnet 16 is de-energized, the spring 34 presses the pilot spool 33 into its safety position 35, in which the two connections A, B are connected to one another and to the tank connection T and the P connection is shut off.
  • the pilot valve 13 is mounted on the main control valve 12 in such a way that its connection P is connected to a control connection X of the main control valve 12 via a supply channel 39 in the housing 15. Furthermore, from the port T of the pilot valve 13, a relief channel 41 in the housing 15 leads to a control port Y of the main control valve 12. These two control ports X, Y are used for external control oil supply and drainage and thus form parts of a control circuit together with the channels 39, 41 42. The supply channel 39 and the relief channel 41 cannot be influenced hydraulically by the main control slide 17 itself.
  • the connection B of the pilot valve 13 is connected via a first control channel 43 to the A-side control chamber 27 in the main control valve 12, while in a corresponding manner the connection A has a connection to the B-side control chamber 28 via a second control channel 44.
  • the slide bore 18 receiving the main control slide 17 is expanded in the area between the first return chamber 23 and the associated control chamber 27 to form a first annular chamber 45 which is connected to an auxiliary connection C1 arranged in the housing 15.
  • the main control slide 17 has in the area of this first annular chamber 45 a first annular groove 46 which, on the one hand, always has a connection with the first annular chamber 45 in the central position of the main control slide 17 and, on the other hand, is constantly connected to the A- via a longitudinal groove 47 on the outside of the slide end 25. side control room 27 is connected.
  • the slide bore 18 penetrates on the opposite valve side a second annular chamber 48, which has a connection to an auxiliary connection C2 and which has a corresponding second annular groove 49 in the main control slide 17 and an associated second longitudinal groove 51 with the B-side Control room 28 has connection. Furthermore, the main control slide 17 has a leak oil drain 52, which is not of interest in the present context, in order to prevent undesired drifting of the working cylinder 11.
  • the two auxiliary connections C1, C2 are each connected via a line 53, 54 to the connections A, B of the switching valve 14, which is designed as a simple, spring-centered, electromagnetically actuated 4/3-way valve.
  • the switching valve 14 has a central, spring-centered zero position 55, in which it relieves both auxiliary connections C1, C2 to the tank connection T, while the connection P is hydraulically blocked.
  • a left switch position 56 all connections A, B, P, T are blocked, while in a right switch position 57, connection B to the tank is relieved and connections A and P are blocked.
  • the mode of operation of the electrohydraulic proportional directional valve 10 to meet special safety requirements is described as follows, the basic function of the two-stage proportional valve being assumed to be known, according to which the control oil supplied at the control connection X from the pilot valve 13, depending on the control position of the pilot valve 33, builds up pressure in the control spaces 27, 28 causes, while at the same time the other control chamber 28, 27 is relieved in order to deflect the main control slide 17 proportionally to the two sides from the center position shown.
  • One of these requirements can e.g. be that, when the protective grille is open, the working cylinder 11 must be prevented from making an unauthorized closing movement, i.e. the main control slide 17 must not reach its flow direction P-A.
  • This requirement is met with the aid of the zero position 55 of the switching valve 14, since in this spring-centered neutral position both auxiliary connections C1, C2 to the tank are relieved and thus a deflection of the main control slide 17 is not possible even with a regulating pilot valve 13.
  • This can already be achieved with a relatively small switching valve 14, which only has to have the same nominal flow rate as the pilot valve 13, so that the pressure medium possibly controlled by the pilot valve 13 into a control chamber can also be safely discharged to the tank, so that no disturbing pressure build-up takes place.
  • the switching valve 14 is brought into its left switching position 56, in which it shuts off both auxiliary connections C1, C2.
  • FIGS. 2 to 6 show different switching valves which can be used instead of the switching valve 14 in the proportional directional control valve 10 according to FIG. 1. These switching valves differ as follows, the spring-centered zero position 55 and the left (56) and right switching position 57 always being identified by the same reference numerals as in the switching valve 14.
  • FIG. 2 shows a switching valve 61, in which the spring-centered zero position 55 is designed so that normal control can be controlled with the proportional directional control valve 10. While in the right switch position 57 the auxiliary connection C2 is relieved, in the left switch position 56 the auxiliary connection C1 to the tank is relieved, so that in these switch positions 56, 57 the main control slide 17 can only be deflected in one direction and thus depending on the pin assignment the connections PA or PB are monitored.
  • FIG. 3 shows a third switching valve 62, which differs from the first switching valve 14 only in that, in the zero position 55, the two auxiliary connections C1 and C2 are connected to one another, while the tank connection T is blocked. This promotes rapid pressure equalization, especially if the switching valve has larger cross sections than the pilot valve 13.
  • FIG. 4 shows a fourth switching valve 63, which differs from the first switching valve 14 only in that, in the right switching position 57, the auxiliary connection C1 associated with the A side to the tank is relieved.
  • FIG. 5 shows a fifth switching valve 64, which is designed as a 4/2 solenoid valve and only has the positions 55, 57, in which it alternately relieves one of the connections A, B to the tank T.
  • the fifth switching valve 64 it is achieved that the main control slide 17 can only ever be deflected in one direction. If the switching valve 64 sticks, a change in direction cannot be carried out. This ensures self-monitoring of the valve.
  • FIG. 6 shows a sixth switching valve 65, which is designed as a spring-loaded 2/2 solenoid valve and which only controls an auxiliary connection C2, which can also be assigned C1 if required.
  • FIG. 7 shows a longitudinal section through part of a second proportional directional control valve 70 which works with other control means to avoid pressure build-up in a control room.
  • the second proportional directional control valve 70 differs from the first proportional directional control valve 10 as follows, the same reference numerals being used for the same components.
  • the supply channel 39 starting from the control connection X is guided to the pilot control valve 13 in a manner which can be influenced by the main control slide 17.
  • the supply channel 39 runs through an annular chamber 71 which is formed in the housing 15 between the first annular chamber 45 and the left return chamber 23.
  • the main control slide 17 has in the area of this annular chamber 71 an annular groove 72 which forms an auxiliary control edge 73.
  • This auxiliary control edge 73 has a positive overlap 74 with respect to the first annular chamber 45, which is smaller than the positive overlap with which the main control slide 17 is equipped between the main connections P and A.
  • a hydraulic cross-connection as in FIG. 1 is omitted between the left control chamber 27 and the first annular chamber 45.
  • the mode of operation of the second proportional directional control valve 70 with regard to its safety function is explained as follows: It is assumed that in the event of an unwanted deflection of the main control spool 17 from its spring-centered center position to the left into a working position, the switching valve 65 connected to line 53 assumes its zero position, whereby it relieves the auxiliary connection C1 to the tank.
  • the main control slide 17 begins to move to the left, its auxiliary control edge 73 opens a connection from the control connection X to the auxiliary connection C1, so that control oil supplied in the control connection X is no longer guided from the regulating pilot valve 13 into the control chamber 28, but rather via the annular groove 72 to the auxiliary connection C1 and further to the tank.
  • the main control slide 17 thus relieves itself, as a result of which no pressure can be built up in the pilot valve 13. An unwanted deflection of the main control slide 17 to the left is therefore not possible.
  • the positive overlaps 74 on the main control slide 17 are matched to one another in such a way that the connection from the main connection P to A is not opened.
  • FIG. 8 shows a longitudinal section through part of a third proportional directional control valve 80, which differs from the second proportional directional control valve 70 as follows, the same reference numerals being used for the same components.
  • a second auxiliary control edge 82 is formed via an additional, second annular groove 81, which has a positive overlap 83 with respect to the first annular chamber 45.
  • the two annular grooves 72, 81 are connected to one another via transverse bores 84 in the main control slide 17.
  • pilot valve with a single proportional solenoid
  • a pilot control stage can also be used that works with two proportional solenoids.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Servomotors (AREA)
  • Multiple-Way Valves (AREA)

Description

Stand der TechnikState of the art

Die Erfindung geht aus von einem elektrohydraulischen Proportionalwegeventil nach der Gattung des Hauptanspruchs.The invention is based on an electrohydraulic proportional directional valve according to the preamble of the main claim.

Es ist schon ein solches Proportionalwegeventil aus der Literaturstelle "Bosch Hydraulik, Proportionalventile, Hydraulik in Theorie und Praxis, 1983, Robert Bosch GmbH, Geschäftsbereich K6 Hydraulik", insbesondere Seite 302 bekannt, mit dem bestimmte Sicherheitsforderungen erfüllbar sind. Der von einem einzigen Proportionalmagneten gegen Federkraft betätigbare Vorsteuerschieber wird dort bei Stromausfall in eine federzentrierte, vierte Schaltstellung gefahren, in der zwischen den beiden stirnseitig gelegenen Steuerkammern am Hauptsteuerschieber zumindest ein Druckausgleich hergestellt wird. Der federzentrierte Hauptsteuerschieber nimmt daraufhin seine Mittelstellung ein und verhindert eine Fehlfunktion eines am Proportionalventil angeschlossenen, hydraulischen Motors. Dieses Proportionalventil weist im Hauptventil neben den vier Hauptanschlüssen A, B, P, T noch zusätzlich die Steueranschlüsse X und Y zur externen Steuerölzu- bzw. -abführung auf. Ferner sind im Hauptventil Hilfsanschlüsse C1 und C2 vorhanden, die jedoch für die Funktion des Lastabgriffs für die Druckwaage benutzt werden. Dieses Proportionalventil kann daher nicht weitergehende Sicherheitsanforderungen erfüllen, wie sie von Berufsgenossenschaften bzw. von UnfallverhütungsVorschriften für hydraulische Maschinen und Anlagen im Sicherheitsbereich gefordert werden. Auch kann bei speziellen Anwendungsfällen dieses Proportionalventil bei Not-Aus-Schaltung zu langsam sein, weil das Zurückstellen des Hauptsteuerschiebers durch die Federn im Hauptventil geschieht, die lediglich eine Rückstellkraft entsprechend wenigen bar Druck ausüben können und das Druckmittel über die kleinen Querschnitte des Vorsteuerventils fließen muß.Such a proportional directional control valve is already known from the literature reference "Bosch hydraulics, proportional valves, hydraulics in theory and practice, 1983, Robert Bosch GmbH, division K6 hydraulics", in particular page 302, with which certain safety requirements can be met. The pilot spool, which can be actuated against spring force by a single proportional magnet, is moved there in the event of a power failure to a spring-centered, fourth switching position, in which at least pressure compensation is established between the two control chambers on the main control spool located at the end. The spring-centered main spool then takes up its central position and prevents malfunction of a hydraulic motor connected to the proportional valve. In addition to the four main connections A, B, P, T, this proportional valve also has control connections X and Y for external control oil supply and discharge in the main valve. There are also auxiliary connections C1 and C2 in the main valve, but these are used for the function of the load tap for the pressure compensator. This proportional valve can therefore not meet any further safety requirements such as those required by professional associations or accident prevention regulations for hydraulic machines and systems in the safety area. Also, in special applications, this proportional valve can be too slow in the event of an emergency stop because the main spool is reset by the springs in the main valve, which can only exert a restoring force corresponding to a few bar pressure and the pressure medium must flow through the small cross-sections of the pilot valve .

Ferner wurde gemäß einem älteren Vorschlag (DE-A-3812116) der Anmelderin bereits vorgeschlagen, zur Erfüllung gestellter Sicherheitsanforderungen bei dem zuvor erwähnten Proportionalventil ein 3/2-Magnetventil zusätzlich in den Steuerkreis zwischen Hauptventil und Vorsteuerventil zu schalten. Damit läßt sich z.B. die häufig vorhandene Forderung an Anlagen und Maschinen mit Schutzeinrichtungen erfüllen, daß beim Öffnen eines Schutzgitters der angeschlossene Arbeitszylinder in nur einer vorgegebenen Richtung betätigt werden darf. So soll z.B. eine Form aufgefahren werden, um defekte Teile entnehmen zu können. Um dies zu erreichen, muß das Proportionalventil so ausgebildet sein, daß sein Hauptschieber nur in eine bestimmte Durchflußrichtung geschaltet werden kann. Von Nachteil bei dieser Lösung ist nun, daß der Aufwand für die Zwischenplattenlösung, in der das 3/2-Magnetventil untergebracht ist, relativ groß ist. Auch die Anpassung an unterschiedliche Sicherheitsanforderungen ist nicht immer leicht durchführbar. So kann durch die schlechte Dynamik in manchen Fällen die Forderung nicht erfüllt werden, daß der Hauptschieber bei Not-Aus bzw. Öffnen eines Schutzgitters schnellstens in seine Ausgangsstellung zurückgestellt werden soll.Furthermore, according to an older proposal (DE-A-3812116), the applicant has already been proposed to additionally connect a 3/2-way solenoid valve in the control circuit between the main valve and the pilot valve in order to meet the safety requirements for the aforementioned proportional valve. This allows e.g. meet the frequently existing requirement for systems and machines with protective devices that the connected working cylinder may only be actuated in one predetermined direction when opening a protective grille. For example, a mold is opened in order to remove defective parts. To achieve this, the proportional valve must be designed so that its main slide can only be switched in a certain flow direction. The disadvantage of this solution is that the effort for the intermediate plate solution, in which the 3/2 solenoid valve is housed, is relatively large. Even adapting to different security requirements is not always easy. In some cases, the poor dynamics mean that the requirement that the main slide should be quickly returned to its starting position in the event of an emergency stop or opening of a protective grille cannot be met.

Vorteile der ErfindungAdvantages of the invention

Das erfindungsgemäße elektrohydraulische Proportionalwegeventil mit den kennzeichnenden Merkmalen des Hauptanspruchs hat demgegenüber den Vorteil, daß es mit relativ geringem Aufwand vielfältige Sicherheitsanforderungen erfüllen kann. Zudem läßt sich auch das dynamische Verhalten dann erheblich verbessern, wenn das Zurückstellen des Hauptsteuerschiebers durch die Federkräfte durch einen Zwischendruck im Vorsteuerkreis hydraulisch unterstützt wird.In contrast, the electrohydraulic proportional directional control valve according to the invention with the characterizing features of the main claim has the advantage that it can meet diverse security requirements with relatively little effort. In addition, the dynamic behavior can also be considerably improved if the resetting of the main control spool is supported hydraulically by the spring forces by an intermediate pressure in the pilot control circuit.

Durch die in den Unteransprüchen aufgeführten Maßnahmen sind vorteilhafte Weiterbildungen und Verbesserungen des im Hauptanspruch angegebenen Proportionalwegeventil möglich. Besonders vorteilhafte Ausführungsformen ergeben sich bei einer Ausbildung nach den Ansprüchen 2 bis 4, wodurch eine besonders einfache und kostengünstige Lösung erzielbar ist. So kann als Gehäuse für das Hauptsteuerventil die Standardausführung benutzt werden, bei der die Hilfsanschlüsse an sich vorhanden sind, jedoch bisher für eine andere Funktion benutzt wurden. Ferner läßt sich als Schaltventil ein relativ klein bauendes Ventil verwenden, das lediglich die gleiche Nenngröße wie das regelnde Vorsteuerventil aufweisen muß, d.h. das Schaltventil muß ohne Erhöhung der Druckdifferenz den Durchfluß des Vorsteuerventils erfüllen. Großvolumige Sicherheitsventile in den Arbeitsleitungen können daher vermieden werden. Ferner lassen sich bei sehr hohen Anforderungen an die Sicherheit am Hauptsteuerventil wie auch am Vorsteuerventil elektrische Stellungsanzeigen anordnen. Der Hauptsteuerschieber ist auch weiterhin mit einer Leckölabführung ausrüstbar, wenn ein Driften des angeschlossenen Arbeitszylinders verhindert werden soll. Vorteilhaft ist es ferner, wenn der Abgriff der Entlastungen direkt im Hauptsteuerschieber eingearbeitet ist, also in einem für den Durchfluß bestimmenden Stellglied. Besonders zweckmäßig ist ferner eine Ausbildung nach Anspruch 12, wodurch ein Druckaufbau in einem Steuerraum besonders wirksam verhindert werden kann. Der Abgriff der Entlastung unmittelbar in der Steuerölzuführung erlaubt eine besonders kompakte Lösung. Zudem garantiert diese Selbstüberwachung des Ventils ein hohes Maß an Sicherheit. Weitere besonders vorteilhafte Ausgestaltungen ergeben sich aus den übrigen Ansprüchen, der Beschreibung sowie der Zeichnung.The measures listed in the subclaims enable advantageous developments and improvements of the proportional directional control valve specified in the main claim. Particularly advantageous embodiments result in a design according to claims 2 to 4, whereby a particularly simple and inexpensive solution can be achieved. For example, the standard version can be used as the housing for the main control valve, in which the auxiliary connections are available per se, but have previously been used for another function. Furthermore, a relatively small valve can be used as the switching valve, which only has to have the same nominal size as the regulating pilot valve, ie the switching valve must meet the flow of the pilot valve without increasing the pressure difference. Large-volume safety valves in the work lines can therefore be avoided. In addition, electrical position indicators can be arranged on the main control valve as well as on the pilot valve in the case of very high safety requirements. The main control spool can still be equipped with a leakage oil drain if the connected working cylinder is to be prevented from drifting. It is also advantageous if the tapping of the reliefs is incorporated directly in the main control slide, that is to say in an actuator which determines the flow. A design according to claim 12 is also particularly expedient, as a result of which pressure build-up in a control chamber can be prevented particularly effectively. Tapping the relief directly in the control oil supply allows a particularly compact solution. This self-monitoring of the valve also guarantees a high level of safety. Further particularly advantageous configurations result from the remaining claims, the description and the drawing.

Zeichnungdrawing

Drei Ausführungsbeispiele der Erfindung sind in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert. Es zeigen Figur 1 ein erstes elektrohydraulisches Proportionalwegeventil in vereinfachter Darstellung und teilweise im Längsschnitt, Figur 1a das Schaltsymbol der Vorsteuerstufe in Figur 1, Figur 2 bis 6 verschiedene Schaltventile zur Verwendung mit dem ersten Proportionalwegeventil nach Figur 1 zur Realisierung unterschiedlicher Sicherheitsanforderungen, Figur 7 einen Längsschnitt durch einen Teil eines zweiten Proportionalwegeventils mit gegenüber der Figur 1 geändertem Abgriff der Entlastung im Steuerkreis und Figur 8 einen Teilschnitt durch ein drittes Ausführungsbeispiel.Three embodiments of the invention are shown in the drawing and explained in more detail in the following description. 1 shows a first electrohydraulic proportional directional control valve in a simplified representation and partly in longitudinal section, FIG. 1a shows the switching symbol of the pilot stage in FIG. 1, FIGS. 2 to 6 different switching valves for use with the first proportional directional control valve according to FIG. 1 to implement different safety requirements, FIG. 7 shows a longitudinal section by a part of a second proportional directional control valve with a change in the tapping of the relief in the control circuit compared to FIG. 1 and FIG. 8 a partial section through a third exemplary embodiment.

Beschreibung der AusführungsbeispieleDescription of the embodiments

Die Figur 1 zeigt in vereinfachter Darstellung ein elektrohydraulisches Proportionalwegeventil 10, das zur Steuerung eines doppeltwirkenden Arbeitszylinders 11 dient. Das Proportionalwegeventil 10 besteht im wesentlichen aus einem hydraulisch gesteuerten Hauptsteuerventil 12, einem elektrisch gesteuerten Vorsteuerventil 13 und einem an das Hauptsteuerventil 12 angeschlossenen Schaltventil 14. Das Vorsteuersteuerventil 13, das auf ein Gehäuse 15 des Hauptsteuerventils 12 geflanscht ist, wird von einem Proportionalmagneten 16 betätigt, in dem zusätzlich ein Wegaufnehmer integriert ist. Hauptsteuerventil 12 und angebautes Vorsteuerventil 13 sind hinsichtlich ihres prinzipiellen Aufbaus aus der eingangs genannten Literaturstelle an sich bekannt, auf die ausdrücklich Bezug genommen wird.FIG. 1 shows a simplified representation of an electrohydraulic proportional directional valve 10, which is used to control a double-acting working cylinder 11. The proportional directional control valve 10 essentially consists of a hydraulically controlled main control valve 12, an electrically controlled pilot control valve 13 and a switching valve 14 connected to the main control valve 12. The pilot control valve 13, which is flanged onto a housing 15 of the main control valve 12, is actuated by a proportional magnet 16. in which an additional displacement sensor is integrated. Main control valve 12 and attached pilot valve 13 are known per se with regard to their basic structure from the literature reference mentioned at the beginning, to which reference is expressly made.

Das proportional arbeitende Hauptsteuerventil 12 ist als 4/3-Wegeventil mit vier gesteuerten Hauptanschlüssen A, B, P und T und einem in drei Schaltstellungen stetig verschiebbaren Hauptsteuerschieber 17 ausgebildet. Der Hauptsteuerschieber 17 ist im Gehäuse 15 in einer Schieberbohrung 18 dicht und gleitend geführt. Die Schieberbohrung 18 durchdringt eine mittig liegende Zulaufkammer 19, die mit dem Hauptanschluß P in Verbindung steht, zwei danebenliegende Motorkammern 21, 22, welche mit den Hauptanschlüssen A und B in Verbindung stehen sowie zwei Rücklaufkammern 23 und 24, welche mit dem Hauptanschluß T Verbindung haben. Der Hauptanschluß P wird in nicht näher gezeichneter Weise von einer Pumpe mit Druckmittel versorgt, während der Hauptanschluß T zum Tank entlastet ist. An die Hauptanschlüsse A und B sind die beiden Seiten des doppeltwirkenden Arbeitszylinders 11 angeschlossen.The proportional main control valve 12 is designed as a 4/3-way valve with four controlled main connections A, B, P and T and a main control spool 17 which can be moved continuously in three switching positions. The main control slide 17 is in the housing 15 in one Slider bore 18 guided tight and sliding. The slide bore 18 penetrates a centrally located inlet chamber 19, which is connected to the main connection P, two adjacent motor chambers 21, 22, which are connected to the main connections A and B, and two return chambers 23 and 24, which are connected to the main connection T. . The main port P is supplied in a manner not shown by a pump with pressure medium, while the main port T is relieved to the tank. The two sides of the double-acting working cylinder 11 are connected to the main connections A and B.

Der Hauptsteuerschieber 17 ragt mit seinen stirnseitigen Enden 25, 26 jeweils in einen Steuerraum 27, 28, die jeweils eine Feder 29, 31 zur Bildung einer doppeltwirkenden Rückstelleinrichtung 32 für den Hauptsteuerschieber 17 aufnehmen. Durch Druckbeaufschlagung eines Steuerraums 27, 28 bei gleichzeitiger Druckentlastung des anderen Steuerraumes 28, 27 läßt sich der Hauptsteuerschieber 17 aus seiner gezeichneten Mittelstellung gegen die Kraft der Rückstelleinrichtung 32 nach beiden Richtungen hin auslenken.The main control slide 17 projects with its front ends 25, 26 into a control chamber 27, 28, which each receive a spring 29, 31 to form a double-acting resetting device 32 for the main control slide 17. By pressurizing a control chamber 27, 28 while simultaneously relieving pressure on the other control chamber 28, 27, the main control slide 17 can be deflected in both directions from its drawn central position against the force of the resetting device 32.

Das Vorsteuerventil 13 ist als 4/4-Wegeventil ausgebildet, dessen Steuerfunktionen aus der zugehörigen, vereinfachten Darstellung nach Figur 1a entnehmbar sind. Das Vorsteuerventil 13 weist vier gesteuerte Anschlüsse A, B, P, T und einen Vorsteuerschieber 33 auf, der von dem einzigen Proportionalmagneten 16 gegen die Kraft einer Feder 34 in vier Schaltstellungen 35, 36, 37 und 38 steuerbar ist. Die Schaltstellung 37 ist dabei als neutrale Regelstellung ausgebildet, in welcher alle vier Anschlüsse A, B, P, T des Vorsteuerventils 13 abgeschlossen sind. Aus dieser neutralen Regelstellung kann der Vorsteuerschieber 33 durch entsprechende Ansteuerung des Proportionalmagneten 16 in die beiden Arbeitsstellungen 38 bzw. 36 überführt werden, in denen abwechselnd einer der Anschlüsse A, B mit dem Anschluß P verbunden wird, während der andere Anschluß B, A zum Tankanschluß T entlastet wird. Bei stromlosem Proportionalmagnet 16 drückt die Feder 34 den Vorsteuerschieber 33 in seine Sicherheitsstellung 35, in der beide Anschlüsse A, B miteinander und mit dem Tankanschluß T verbunden sind und der P-Anschluß abgesperrt ist.The pilot valve 13 is designed as a 4/4-way valve, the control functions of which can be found in the associated, simplified illustration according to FIG. 1a. The pilot valve 13 has four controlled connections A, B, P, T and a pilot spool 33, which can be controlled by the single proportional magnet 16 against the force of a spring 34 in four switching positions 35, 36, 37 and 38. The switch position 37 is designed as a neutral control position in which all four connections A, B, P, T of the pilot valve 13 are closed. From this neutral control position, the pilot spool 33 can be transferred into the two working positions 38 and 36, respectively, by correspondingly controlling the proportional magnet 16, in which one of the connections A, B is alternately connected to the connection P, while the other connection B, A to Tank connection T is relieved. When the proportional magnet 16 is de-energized, the spring 34 presses the pilot spool 33 into its safety position 35, in which the two connections A, B are connected to one another and to the tank connection T and the P connection is shut off.

Das Vorsteuerventil 13 ist an dem Hauptsteuerventil 12 so angebaut, daß sein Anschluß P über einen Versorgungskanal 39 im Gehäuse 15 mit einem Steueranschluß X des Hauptsteuerventils 12 verbunden ist. Ferner führt vom Anschluß T des Vorsteuerventils 13 ein Entlastungskanal 41 im Gehäuse 15 zu einem Steueranschluß Y des Hauptsteuerventils 12. Diese beiden Steueranschlüsse X, Y dienen zur externen Steuerölzu- bzw. -Abführung und bilden somit zusammen mit den Kanälen 39, 41 Teile eines Steuerkreises 42. Der Versorgungskanal 39 und der Entlastungskanal 41 sind vom Hauptsteuerschieber 17 selbst nicht hydraulisch beeinflußbar. Der Anschluß B des Vorsteuerventils 13 ist über einen ersten Steuerkanal 43 mit dem A-seitigen Steuerraum 27 im Hauptsteuerventil 12 verbunden, während in entsprechender Weise der Anschluß A über einen zweiten Steuerkanal 44 mit dem B-seitigen Steuerraum 28 Verbindung hat.The pilot valve 13 is mounted on the main control valve 12 in such a way that its connection P is connected to a control connection X of the main control valve 12 via a supply channel 39 in the housing 15. Furthermore, from the port T of the pilot valve 13, a relief channel 41 in the housing 15 leads to a control port Y of the main control valve 12. These two control ports X, Y are used for external control oil supply and drainage and thus form parts of a control circuit together with the channels 39, 41 42. The supply channel 39 and the relief channel 41 cannot be influenced hydraulically by the main control slide 17 itself. The connection B of the pilot valve 13 is connected via a first control channel 43 to the A-side control chamber 27 in the main control valve 12, while in a corresponding manner the connection A has a connection to the B-side control chamber 28 via a second control channel 44.

Die den Hauptsteuerschieber 17 aufnehmende Schieberbohrung 18 ist im Bereich zwischen der ersten Rücklaufkammer 23 und dem zugeordneten Steuerraum 27 zu einer ersten Ringkammer 45 erweitert, die mit einem im Gehäuse 15 angeordneten Hilfsanschluß C1 in Verbindung steht. Der Hauptsteuerschieber 17 weist im Bereich dieser ersten Ringkammer 45 eine erste Ringnut 46 auf, die einerseits in der gezeichneten Mittelstellung des Hauptsteuerschiebers 17 stets mit der ersten Ringkammer 45 Verbindung hat und die andererseits über eine am Schieberende 25 außen ausgebildete Längsnut 47 ständig mit dem A-seitigen Steuerraum 27 verbunden ist. In entsprechender Weise durchdringt die Schieberbohrung 18 auf der gegenüberliegenden Ventilseite eine zweite Ringkammer 48, die Verbindung zu einem Hilfsanschluß C2 hat und die über eine entsprechende zweite Ringnut 49 im Hauptsteuerschieber 17 und eine zugeordnete zweite Längsnut 51 mit dem B-seitigen Steuerraum 28 Verbindung hat. Ferner weist der Hauptsteuerschieber 17 eine im vorliegenden Zusammenhang nicht näher interessierende Leckölabführung 52 auf, um ein ungewolltes Driften des Arbeitszylinders 11 zu verhindern.The slide bore 18 receiving the main control slide 17 is expanded in the area between the first return chamber 23 and the associated control chamber 27 to form a first annular chamber 45 which is connected to an auxiliary connection C1 arranged in the housing 15. The main control slide 17 has in the area of this first annular chamber 45 a first annular groove 46 which, on the one hand, always has a connection with the first annular chamber 45 in the central position of the main control slide 17 and, on the other hand, is constantly connected to the A- via a longitudinal groove 47 on the outside of the slide end 25. side control room 27 is connected. In a corresponding manner, the slide bore 18 penetrates on the opposite valve side a second annular chamber 48, which has a connection to an auxiliary connection C2 and which has a corresponding second annular groove 49 in the main control slide 17 and an associated second longitudinal groove 51 with the B-side Control room 28 has connection. Furthermore, the main control slide 17 has a leak oil drain 52, which is not of interest in the present context, in order to prevent undesired drifting of the working cylinder 11.

Wie Figur 1 ferner zeigt, sind die beiden Hilfsanschlüsse C1, C2 jeweils über eine Leitung 53, 54 mit den Anschlüssen A, B des Schaltventils 14 verbunden, das als einfaches, federzentriertes, elektromagnetisch betätigtes 4/3-Wegeventil ausgebildet ist. Das Schaltventil 14 hat eine mittlere, federzentrierte Nullstellung 55, in der es beide Hilfsanschlüsse C1, C2 zum Tankanschluß T entlastet, während der Anschluß P hydraulisch blockiert ist. In einer linken Schaltstellung 56 sind alle Anschlüsse A, B, P, T abgesperrt, während in einer rechten Schaltstellung 57 der Anschluß B zum Tank entlastet ist und die Anschlüsse A und P gesperrt sind.As FIG. 1 also shows, the two auxiliary connections C1, C2 are each connected via a line 53, 54 to the connections A, B of the switching valve 14, which is designed as a simple, spring-centered, electromagnetically actuated 4/3-way valve. The switching valve 14 has a central, spring-centered zero position 55, in which it relieves both auxiliary connections C1, C2 to the tank connection T, while the connection P is hydraulically blocked. In a left switch position 56, all connections A, B, P, T are blocked, while in a right switch position 57, connection B to the tank is relieved and connections A and P are blocked.

Die Wirkungsweise des elektrohydraulischen Proportionalwegeventils 10 zur Erfüllung besonderer Sicherheitsanforderungen wird wie folgt beschrieben, wobei die grundsätzliche Funktion des zweistufigen Proportionalventils als bekannt vorausgesetzt wird, wonach das am Steueranschluß X zugeführte Steueröl vom Vorsteuerventil 13 je nach Regelstellung des Vorsteuerschiebers 33 einen Druckaufbau in den Steuerraumen 27, 28 bewirkt, während gleichzeitig der andere Steuerraum 28, 27 entlastet wird,um den Hauptsteuerschieber 17 aus der gezeichneten Mittelstellung proportional nach beiden Seiten hin auszulenken.The mode of operation of the electrohydraulic proportional directional valve 10 to meet special safety requirements is described as follows, the basic function of the two-stage proportional valve being assumed to be known, according to which the control oil supplied at the control connection X from the pilot valve 13, depending on the control position of the pilot valve 33, builds up pressure in the control spaces 27, 28 causes, while at the same time the other control chamber 28, 27 is relieved in order to deflect the main control slide 17 proportionally to the two sides from the center position shown.

Bei vorliegendem Proportionalwegeventil 10 sind nun zumindest in der Mittelstellung des Hauptsteuerschiebers 17 dessen Steuerräume 27, 28 jeweils über die Längsnuten 47, 51, die Ringnuten 46, 49 und die Ringkammern 45, 48 jeweils mit den Hilfsanschlüssen C1 bzw. C2 verbunden, die ihrerseits an das Schaltventil 14 angeschlossen sind. Je nach gerade wirksamen Schaltsymbol am Schaltventil 14 können nun unterschiedliche Sicherheitsansforderungen am Hauptsteuerventil 12 realisiert werden, wie dies bei Anlagen und Maschinen mit Schutzeinrichtungen häufig gefordert wird.In the present proportional directional control valve 10, at least in the central position of the main control slide 17, its control spaces 27, 28 are each connected via the longitudinal grooves 47, 51, the annular grooves 46, 49 and the annular chambers 45, 48 to the auxiliary connections C1 and C2, which in turn are connected the switching valve 14 are connected. Depending on the currently active switching symbol on the switching valve 14, different ones can now be used Safety requirements are realized on the main control valve 12, as is often required in systems and machines with protective devices.

Eine dieser Forderungen kann z.B. sein, daß bei einem geöffneten Schutzgitter verhindert werden muß, daß der Arbeitszylinder 11 eine unerlaubte schließende Bewegung macht, d.h. der Hauptsteuerschieber 17 darf seine Durchflußrichtung P-A nicht erreichen. Diese Forderung wird mit Hilfe der Nullstellung 55 des Schaltventils 14 erfüllt, da in dieser federzentrierten Neutralstellung beide Hilfsanschlüsse C1, C2 zum Tank entlastet sind und somit eine Auslenkung des Hauptsteuerschiebers 17 auch bei einem regelnden Vorsteuerventil 13 nicht möglich ist. Dies läßt sich bereits mit einem relativ klein bauenden Schaltventil 14 erreichen, das lediglich den gleichen Nenndurchfluß wie das Vorsteuerventil 13 aufweisen muß, so daß das vom Vorsteuerventil 13 eventuell in einen Steuerraum gesteuerte Druckmittel auch sicher zum Tank abgeführt werden kann, so daß kein störender Druckaufbau stattfindet.One of these requirements can e.g. be that, when the protective grille is open, the working cylinder 11 must be prevented from making an unauthorized closing movement, i.e. the main control slide 17 must not reach its flow direction P-A. This requirement is met with the aid of the zero position 55 of the switching valve 14, since in this spring-centered neutral position both auxiliary connections C1, C2 to the tank are relieved and thus a deflection of the main control slide 17 is not possible even with a regulating pilot valve 13. This can already be achieved with a relatively small switching valve 14, which only has to have the same nominal flow rate as the pilot valve 13, so that the pressure medium possibly controlled by the pilot valve 13 into a control chamber can also be safely discharged to the tank, so that no disturbing pressure build-up takes place.

Eine zusätzliche Forderung bei Unfall-Verhütungsvorschriften verlangt, daß bei einem geöffneten Schutzgitter die Möglichkeit bestehen soll, daß die Form nur auffahrbar ist, um beispielsweise defekte Teile zu entnehmen, d.h. der Hauptsteuerschieber 17 darf nur in die Durchflußrichtung P-B geschaltet werden. Diese Forderung läßt sich mit Hilfe der rechten Schaltstellung 57 des Schaltventils 14 erreichen, wobei der Hilfsanschluß C2 zum Tank entlastet wird, während der andere Hilfsanschluß C1 blockiert ist. Damit kann bei regelndem Vorsteuerventil 13 ein Druckaufbau lediglich in dem linken Steuerraum 27 stattfinden, so daß eine Auslenkung des Hauptsteuerschiebers 17 nach rechts zum Aufsteuern eines Durchflußes von P nach B möglich ist, nicht aber eine Durchflußsteuerung von P nach A.An additional requirement for accident prevention regulations requires that, with an open protective grille, there should be the possibility that the mold can only be opened, for example to remove defective parts, ie the main control slide 17 may only be switched in the flow direction PB. This requirement can be achieved with the help of the right switching position 57 of the switching valve 14, the auxiliary connection C2 being relieved of pressure to the tank, while the other auxiliary connection C1 is blocked. With a regulating pilot valve 13, a pressure build-up can only take place in the left control chamber 27, so that a deflection of the main control slide 17 to the right is possible for controlling a flow from P to B, but not a flow control from P to A.

Für einen normalen Regelbetrieb des Proportionalwegeventils 10 wird das Schaltventil 14 in seine linke Schaltstellung 56 gebracht, in der es beide Hilfsanschlüsse C1, C2 absperrt.For normal control operation of the proportional directional control valve 10, the switching valve 14 is brought into its left switching position 56, in which it shuts off both auxiliary connections C1, C2.

Im normalen Regelbetrieb, also bei bestromten Vorsteuerventil 13, läßt sich ferner ein verbessertes dynamisches Verhalten des Proportionalwegeventils 10 erreichen. Es sei davon ausgegangen, daß in Figur 1 der Hauptsteuerschieber 17 z.B. in Richtung P→A, also nach links, ausgelenkt ist und das Schaltventil 14 seine Stellung 56 einnimmt, wobei nun ein schnelles Zurückstellen in die durch den Sollwert vorgegebene Stellung gewünscht wird. Dazu wird das Schaltventil 14 in seine Stellung 57 geschaltet und zugleich das Vorsteuerventil 13 in der Art bestromt, daß im linken Steuerraum 27 der volle Steuerdruck ansteht. Der rechte Steuerraum 28 wird mit dem Schaltventil 14 entlastet, so daß das Druckmittel aus dem rechten Steuerraum 28 nicht allein über die kleinen Querschnitte des Vorsteuerventils 13 zurückfließen muß. Dadurch werden kürzere Stellzeiten erreicht. Beim Öffnen des Schutzgitters kann dann das Schaltventil 14 in seine Stellung 55 gebracht werden; damit wird jegliches Auslenken des Hauptsteuerschiebers 17 verhindert.In normal control operation, ie when the pilot valve 13 is energized, an improved dynamic behavior of the proportional directional control valve 10 can also be achieved. It is assumed that in Figure 1 the main spool 17 e.g. is deflected in the direction P → A, that is to the left, and the switching valve 14 assumes its position 56, a rapid return to the position predetermined by the desired value now being desired. For this purpose, the switching valve 14 is switched to its position 57 and at the same time the pilot valve 13 is energized in such a way that the full control pressure is present in the left control chamber 27. The right control chamber 28 is relieved with the switching valve 14, so that the pressure medium from the right control chamber 28 does not have to flow back solely through the small cross sections of the pilot valve 13. As a result, shorter positioning times are achieved. When the protective grille is opened, the switching valve 14 can then be brought into its position 55; this prevents any deflection of the main control slide 17.

Darüber hinaus besteht häufig die Forderung, daß bei Not-Aus bzw. beim Öffnen des Schutzgitters der Hauptsteuerschieber 17 schnellstens in seine Mittelstellung zurückgestellt werden soll. Auch diese Forderung ist beim Proportionalwegeventil 10 verbessert, indem beim Zurückstellen des Hauptsteuerschiebers 17 durch die relativ schwachen Kräfte der Federn 29 bzw. 31 das Druckmittel über das Vorsteuerventil 13 und das Schaltventil 14 abströmen kann, so daß ein schnelles Rückstellen erzielbar ist.In addition, there is often the requirement that the main control slide 17 should be quickly returned to its central position in the event of an emergency stop or when the protective grille is opened. This requirement is also improved in the proportional directional control valve 10, in that when the main control spool 17 is reset, the pressure medium can flow out via the pilot control valve 13 and the switching valve 14 due to the relatively weak forces of the springs 29 and 31, so that a quick reset can be achieved.

Mit vorliegendem Proportionalwegeventil 10 lassen sich somit unterschiedlichste Sicherheitsanforderungen erfüllen, wobei als Gehäuse 15 ein kostengünstiges Standardgehäuse verwendbar ist, bei dem bereits ein Steuerkreis 42 mit den Hilfsanschlüssen C1, C2 vorhanden ist.With the present proportional directional control valve 10, a wide variety of safety requirements can thus be met, an inexpensive standard housing, which already can be used as the housing 15 a control circuit 42 is provided with the auxiliary connections C1, C2.

Die Figuren 2 bis 6 zeigen verschiedene Schaltventile, die anstelle des Schaltventils 14 beim Proportionalwegeventil 10 nach Figur 1 verwendbar sind. Diese Schaltventile unterscheiden sich wie folgt, wobei die federzentrierte Nullstellung 55 und die linke (56) bzw. rechte Schaltstellung 57 stets mit gleichen Bezugszeichen wie beim Schaltventil 14 bezeichnet sind.FIGS. 2 to 6 show different switching valves which can be used instead of the switching valve 14 in the proportional directional control valve 10 according to FIG. 1. These switching valves differ as follows, the spring-centered zero position 55 and the left (56) and right switching position 57 always being identified by the same reference numerals as in the switching valve 14.

Die Figur 2 zeigt ein Schaltventil 61, bei dem die federzentrierte Nullstellung 55 so ausgebildet ist, daß mit dem Proportionalwegeventil 10 eine normale Regelung gesteuert werden kann. Während in der rechten Schaltstellung 57 wie bisher der Hilfsanschluß C2 entlastet ist, wird in der linken Schaltstellung 56 der Hilfsanschluß C1 zum Tank entlastet, so daß in diesen Schaltstellungen 56, 57 der Hauptsteuerschieber 17 jeweils nur in einer Richtung auslenkbar ist und somit je nach Anschlußbelegung die Verbindungen PA oder PB überwacht werden.FIG. 2 shows a switching valve 61, in which the spring-centered zero position 55 is designed so that normal control can be controlled with the proportional directional control valve 10. While in the right switch position 57 the auxiliary connection C2 is relieved, in the left switch position 56 the auxiliary connection C1 to the tank is relieved, so that in these switch positions 56, 57 the main control slide 17 can only be deflected in one direction and thus depending on the pin assignment the connections PA or PB are monitored.

Die Figur 3 zeigt ein drittes Schaltventil 62, das sich vom ersten Schaltventil 14 lediglich dadurch unterscheidet, daß bei ihm in der Nullstellung 55 die beiden Hilfsanschlüsse C1 und C2 miteinander verbunden sind, während der Tankanschluß T blockiert ist. Dadurch wird ein schneller Druckausgleich begünstigt, zumal wenn das Schaltventil größere Querschnitte als das Vorsteuerventil 13 aufweist.FIG. 3 shows a third switching valve 62, which differs from the first switching valve 14 only in that, in the zero position 55, the two auxiliary connections C1 and C2 are connected to one another, while the tank connection T is blocked. This promotes rapid pressure equalization, especially if the switching valve has larger cross sections than the pilot valve 13.

Die Figur 4 zeigt ein viertes Schaltventil 63, das sich vom ersten Schaltventil 14 lediglich dadurch unterscheidet, das bei ihm in der rechten Schaltstellung 57 der der A-Seite zugeordnete Hilfsanschluß C1 zum Tank entlastet wird.FIG. 4 shows a fourth switching valve 63, which differs from the first switching valve 14 only in that, in the right switching position 57, the auxiliary connection C1 associated with the A side to the tank is relieved.

Die Figur 5 zeigt ein fünftes Schaltventil 64, das als 4/2-Magnetventil ausgebildet ist und lediglich die Stellungen 55, 57 aufweist, in denen es abwechselnd einen der Anschlüsse A, B zum Tank T entlastet. Mit dem fünften Schaltventil 64 wird erreicht, daß der Hauptsteuerschieber 17 immer nur in einer einzigen Richtung ausgelenkt werden kann. Bleibt das Schaltventil 64 hängen, so läßt sich auch eine Richtungsänderung nicht vornehmen. Somit ist eine Selbstüberwachung des Ventils gegeben.FIG. 5 shows a fifth switching valve 64, which is designed as a 4/2 solenoid valve and only has the positions 55, 57, in which it alternately relieves one of the connections A, B to the tank T. With the fifth switching valve 64 it is achieved that the main control slide 17 can only ever be deflected in one direction. If the switching valve 64 sticks, a change in direction cannot be carried out. This ensures self-monitoring of the valve.

Die Figur 6 zeigt ein sechstes Schaltventil 65, das als federbelastetes 2/2-Magnetventil ausgebildet ist und das lediglich einen Hilfsanschluß C2 steuert, der auch bei Bedarf mit C1 belegt sein kann.FIG. 6 shows a sixth switching valve 65, which is designed as a spring-loaded 2/2 solenoid valve and which only controls an auxiliary connection C2, which can also be assigned C1 if required.

Die Figur 7 zeigt einen Längsschnitt durch einen Teil eines zweiten Proportionalwegeventils 70, das mit anderen Steuermitteln zum Vermeiden eines Druckaufbaus in einem Steuerraum arbeitet. Das zweite Proportionalwegeventil 70 unterscheidet sich vom ersten Proportionalwegeventil 10 wie folgt, wobei für gleiche Bauelemente gleiche Bezugszeichen verwendet werden.FIG. 7 shows a longitudinal section through part of a second proportional directional control valve 70 which works with other control means to avoid pressure build-up in a control room. The second proportional directional control valve 70 differs from the first proportional directional control valve 10 as follows, the same reference numerals being used for the same components.

Beim zweiten Proportionalwegeventil 70 ist der vom Steueranschluß X ausgehende Versorgungskanal 39 in einer vom Hauptsteuerschieber 17 beeinflußbaren Weise zum Vorsteuerventil 13 geführt. Zu diesem Zweck verläuft der Versorgungskanal 39 über eine Ringkammer 71, die im Gehäuse 15 zwischen der ersten Ringkammer 45 und der linken Rücklaufkammer 23 ausgebildet ist. Der Hauptsteuerschieber 17 weist im Bereich dieser Ringkammer 71 eine Ringnut 72 auf, welche eine Hilfssteuerkante 73 bildet. Diese Hilfssteuerkante 73 weist in bezug auf die erste Ringkammer 45 eine positive Überdeckung 74 auf, die kleiner ist als die positive Überdeckung, mit welcher der Hauptsteuerschieber 17 zwischen den Hauptanschlüssen P und A ausgerüstet ist. Zwischen dem linken Steuerraum 27 und der ersten Ringkammer 45 entfällt eine hydraulische Querverbindung wie nach Figur 1.In the case of the second proportional directional control valve 70, the supply channel 39 starting from the control connection X is guided to the pilot control valve 13 in a manner which can be influenced by the main control slide 17. For this purpose, the supply channel 39 runs through an annular chamber 71 which is formed in the housing 15 between the first annular chamber 45 and the left return chamber 23. The main control slide 17 has in the area of this annular chamber 71 an annular groove 72 which forms an auxiliary control edge 73. This auxiliary control edge 73 has a positive overlap 74 with respect to the first annular chamber 45, which is smaller than the positive overlap with which the main control slide 17 is equipped between the main connections P and A. A hydraulic cross-connection as in FIG. 1 is omitted between the left control chamber 27 and the first annular chamber 45.

Die Wirkungsweise des zweiten Proportionalwegeventils 70 hinsichtlich seiner Sicherheitsfunktion wird wie folgt erläutert: Es wird davon ausgegangen, daß bei einer ungewollten Auslenkung des Hauptsteuerschiebers 17 aus seiner gezeichneten federzentrierten Mittelstellung nach links in eine Arbeitsstellung das an die Leitung 53 angeschlossene Schaltventil 65 seine Nullstellung einnimmt, wobei es den Hilfsanschluß C1 zum Tank entlastet. Bei einer beginnenden Linksbewegung des Hauptsteuerschiebers 17 öffnet seine Hilfssteuerkante 73 eine Verbindung von dem Steueranschluß X zum Hilfsanschluß C1, so daß im Steueranschluß X zugeführtes Steueröl nicht mehr vom regelnden Vorsteuerventil 13 in den Steuerraum 28 geführt wird, sondern bereits über die Ringnut 72 zum Hilfsanschluß C1 und weiter zum Tank abgeleitet wird. Der Hauptsteuerschieber 17 entlastet sich somit selbst, wodurch im Vorsteuerventil 13 kein Druck aufgebaut werden kann. Ein ungewolltes Auslenken des Hauptsteuerschiebers 17 nach links ist daher nicht möglich. Die positiven Überdeckungen 74 am Hauptsteuerschieber 17 sind dabei so aufeinander abgestimmt, daß die Verbindung vom Hauptanschluß P nach A nicht geöffnet wird.The mode of operation of the second proportional directional control valve 70 with regard to its safety function is explained as follows: It is assumed that in the event of an unwanted deflection of the main control spool 17 from its spring-centered center position to the left into a working position, the switching valve 65 connected to line 53 assumes its zero position, whereby it relieves the auxiliary connection C1 to the tank. When the main control slide 17 begins to move to the left, its auxiliary control edge 73 opens a connection from the control connection X to the auxiliary connection C1, so that control oil supplied in the control connection X is no longer guided from the regulating pilot valve 13 into the control chamber 28, but rather via the annular groove 72 to the auxiliary connection C1 and further to the tank. The main control slide 17 thus relieves itself, as a result of which no pressure can be built up in the pilot valve 13. An unwanted deflection of the main control slide 17 to the left is therefore not possible. The positive overlaps 74 on the main control slide 17 are matched to one another in such a way that the connection from the main connection P to A is not opened.

Die Figur 8 zeigt einen Längsschnitt durch einen Teil eines dritten Proportionalwegeventils 80, das sich vom zweiten Proportionalwegeventil 70 wie folgt unterscheidet, wobei für gleiche Bauelemente gleiche Bezugszeichen verwendet werden. Beim dritten Proportionalwegeventil 80 ist über eine zusätzliche, zweite Ringnut 81 eine zweite Hilfsteuerkante 82 ausgebildet, die in bezug auf die erste Ringkammer 45 eine positive Überdeckung 83 aufweist. Die beiden Ringnuten 72, 81 sind über Querbohrungen 84 im Hauptsteuerschieber 17 miteinander verbunden.FIG. 8 shows a longitudinal section through part of a third proportional directional control valve 80, which differs from the second proportional directional control valve 70 as follows, the same reference numerals being used for the same components. In the third proportional directional control valve 80, a second auxiliary control edge 82 is formed via an additional, second annular groove 81, which has a positive overlap 83 with respect to the first annular chamber 45. The two annular grooves 72, 81 are connected to one another via transverse bores 84 in the main control slide 17.

Mit dieser Anordnung wird erreicht, daß beim dritten Proportionalwegeventil 80 eine Selbstentlastung bei Auslenkung des Hauptsteuerschiebers 17 aus seiner Mittelstellung in beiden Richtungen möglich ist.With this arrangement it is achieved that with the third proportional directional control valve 80 a self-relief is possible in both directions when the main control slide 17 is deflected from its central position.

Somit lassen sich bei den Proportionalwegeventilen 70, 80 bei äußerst kompakter Bauform mit relativ geringem Mehraufwand an Standardventilen vielfältige Sicherheitsanforderungen bei Anlagen und Maschinen mit Schutzeinrichtungen erfüllen.This means that the proportional directional control valves 70, 80, with their extremely compact design and relatively little additional effort, can fulfill a wide range of safety requirements for systems and machines with protective devices.

Selbstverständlich sind an den gezeigten Ausführungsformen Änderungen möglich, ohne vom Gedanken der Erfindung abzuweichen. Anstelle des Vorsteuerventils mit einem einzigen Proportionalmagneten kann auch eine Vorsteuerstufe verwendet werden, die mit zwei Proportionalmagneten arbeitet. Ferner ist es auch möglich, bei der Ausführung nach Figur 1 auf die im Steuerschieber 17 eingestochenen Ringnuten 46, 49 ganz zu verzichten und die Querverbindungen allein durch die Längsnuten 47, 51 herzustellen, die dann ausreichend lang ausgebildet werden müssen.Of course, changes are possible to the embodiments shown without departing from the spirit of the invention. Instead of the pilot valve with a single proportional solenoid, a pilot control stage can also be used that works with two proportional solenoids. Furthermore, it is also possible, in the embodiment according to FIG. 1, to dispense entirely with the annular grooves 46, 49 pierced in the control slide 17 and to produce the cross-connections solely through the longitudinal grooves 47, 51, which must then be made sufficiently long.

Anstelle der in Figur 1 dargestellten Bauart, bei der in der gezeichneten Mittelstellung die Steuerräume 27, 28 infolge negativer Überdeckung jeweils ständig mit den Hilfsanschlüssen C1, C2 verbunden sind, kann es auch zweckmäßig sein, diese Querverbindungen mit einer geringen positiven Überdeckung auszurüsten, die jedoch stets kleiner ausgebildet ist als die zugehörige positive Überdeckung des Steuerschiebers zwischen den Hauptanschlüssen. Eine solche Überdekkung hat den Vorteil, daß sie ein schnelleres Zurückstellen des Steuerschiebers erlaubt, da der volle Steuerdruck in der druckbeaufschlagten Steuerkammer beim Zurückstellen länger aufrechterhalten werden kann. Auch ist es bei positiver Überdeckung in der Querverbindung in vorteilhafter Weise möglich, gezielt einen bestimmten Hub am Steuerschieber vorzugeben, nach dessen Durchfahren die Sicherheitsabschaltung wirksam werden soll.Instead of the type of construction shown in FIG. 1, in which the control rooms 27, 28 are permanently connected to the auxiliary connections C1, C2 in the middle position shown as a result of negative coverage, it may also be expedient to equip these cross connections with a low positive coverage, which, however is always made smaller than the associated positive overlap of the control spool between the main connections. Such a covering has the advantage that it allows the control slide to be reset more quickly, since the full control pressure in the pressurized control chamber can be maintained longer when the control is reset. If there is a positive overlap in the cross-connection, it is also possible in an advantageous manner to specifically specify a certain stroke on the control slide, after the passage of which the safety shutdown is to take effect.

Unter Umständen kann es auch zweckmäßig sein, Querverbindungen mit positiver und negativer Überdeckung im Proportionalwegeventil zu kombinieren.Under certain circumstances it can also be useful to combine cross connections with positive and negative overlap in the proportional directional control valve.

Claims (20)

  1. Electrohydraulic proportional directional valve (10, 70, 80) with a hydraulically controlled main control valve (12), the control slide (17) of which is centred in a middle position by spring force and can be deflected towards both sides into working positions via control spaces (27, 28) located on the end faces, in order to control the hydraulic connections between four main connections (A, B, P, T), and with an electromagnetically actuated pilot-control valve (13) which controls the main control valve (12) via a pilot-control circuit (42), for which purpose the two valve connections of the pilot-control valve (13) are connected via control channels (43, 44) to the control spaces (27, 28), in order alternately to load these with control pressure medium or to relieve them, and with at least one auxiliary connection (C1, C2) which is arranged in the main control valve (12) and which, in dependence on the position of the control slide (17), can be connected to another space filled with pressure medium, characterized in that there are arranged on the control slide (17) of the main control valve (12) control means (46, 47, 49, 51; 72, 73; 81, 82), via which a portion (27, 28; 39) of the pilot-control circuit (42), the said portion being loaded with pressure when the pilot-control valve (13) is regulating, is connected to the auxiliary connection (C1, C2), and in that inserted into a line (53, 54) outgoing from the auxiliary connection (C1, C2) is a switching valve (14; 61-65), by means of which the pressure-loaded portion (27, 28, 39) can be relieved.
  2. Proportional directional valve according to Claim 1, characterized in that the pressure-loaded portion of the pilot-control circuit (42) is a control space (27, 28) which is connected to the auxiliary connection (C1, C2) via the cross-connection (47, 46; 51, 49) which can be influenced by the main control slide (17).
  3. Proportional directional valve according to Claim 1 or 2, characterized in that the cross-connection is arranged on the main control slide (17) and, in particular, is designed essentially as a longitudinal groove (47, 51) extending on the outer circumference of the latter.
  4. Proportional directional valve according to Claim 3, characterized in that the longitudinal groove (47, 51) extends between the control space (27, 28) and an annular groove (46, 49) in the control slide (17), which annular groove (46, 49) is located in the region of an annular chamber (45, 48) fixed relative to the housing and connected to the auxiliary connection (C1, C2).
  5. Proportional directional valve according to one or more of Claims 1 to 4, characterized in that the main control valve (12) has a second auxiliary connection (C2) with an associated cross-connection (49, 51) in the other second control space (28), and the line (54) outgoing from the auxiliary connection (C2) leads to a switching valve (14).
  6. Proportional directional valve according to Claim 5, characterized in that the two connections (C1, C2) are connected to a common switching valve (14) via their outgoing lines (53, 54).
  7. Proportional directional valve according to Claim 6, characterized in that the switching valve is designed as a 4-way/3-position valve (14, 61, 62, 63) with a spring-centred neutral position (55).
  8. Proportional directional valve according to Claim 7, characterized in that the switching valve (62), in its spring-centred neutral position (55), connects the two auxiliary connections (C1, C2) to one another.
  9. Proportional directional valve according to Claim 7, characterized in that the switching valve (14; 63), in its spring-centred neutral position (55), relieves the two auxiliary connections (C1, C2) to the tank (T).
  10. Proportional directional valve according to one of Claims 5 to 9, characterized in that the switching valve (14; 61, 62, 63) has at least one switching position, in which the two auxiliary connections (C1, C2) are blocked hydraulically, and has at least one switching position (57), in which one of the auxiliary connections (C2, C1) is relieved and the other (C1, C2) is blocked.
  11. Proportional directional valve according to one of Claims 5 and 6, characterized in that the switching valve is designed as a 2-position valve (64, 65), in particular a spring-centred 3/2 solenoid valve (64), which, in each switching position (55, 57), relieves one of the auxiliary connections (C1, C2) to the tank (T) and shuts off the other auxiliary connection.
  12. Proportional directional valve according to Claim 1, characterized in that the pressure-loaded portion of the pilot-control circuit is a channel (39) which serves upstream of the pilot-control valve (13) to a control connection (X) for the inflow of control pressure medium and which is connected to an annular chamber (71) assigned to the control slide (17), and in that this annular chamber (71) can be connected to the auxiliary connection (C1) via an auxiliary control edge (73) and the control slide (17).
  13. Proportional directional valve according to Claim 12, characterized in that the auxiliary control edge (73) has, in the middle position of the control slide (17), a positive overlap (74) which is smaller than the associated positive overlap of the control slide (17) in relation to a connection between the main connections for the inflow (P) and the motor (A/B).
  14. Proportional directional valve according to Claim 12 or 13, characterized in that a second auxiliary control edge (82) is arranged on the control slide (17), so that in the event of a deflection of the control slide (17) out of its middle position in opposite directions, the inflow (X) of the control pressure medium can be connected to the auxiliary connection (C1).
  15. Proportional directional valve according to one of Claims 12 to 14, characterized in that the auxiliary connection (C1) is connected to the tank (T) via the outgoing line (53), and the switching valve located in this line (53) is designed as a spring-centred magnet-actuated 2/2 valve (65).
  16. Proportional directional valve according to one or more of Claims 1 to 15, characterized in that the control means (47, 46, 49, 51; 72, 73; 81, 82) in the main valve (12) for each auxiliary connection (C1, C2) are arranged respectively essentially between a return-flow chamber (23; 24) and the adjacent control space (27, 28).
  17. Proportional directional valve according to one or more of Claims 1 to 16, characterized in that the pilot-control valve is a 4/4 valve, the pilot-control side of which can be deflected counter to the force of a spring (34) by a single proportional magnet (16).
  18. Proportional directional valve according to one of Claims 1 to 17, characterized in that the load pick-ups for a pressure balance, which are present per se in a housing (15) of the proportional directional valve (10; 70; 80), are used as auxiliary connections (C1, C2).
  19. Proportional directional valve according to one of Claims 1 to 11, characterized in that, in the middle position of the control slide (17), the cross-connection (47, 46, 45, C1) is designed as a negative overlap.
  20. Proportional directional valve according to one of Claims 1 to 11, characterized in that, in the middle position of the control slide, the cross-connection is designed as a positive overlap which is smaller than the associated positive overlap of the control slide in relation to an associated connection between the main connections for the inflow (P) and the motor (A/B).
EP89122724A 1988-12-30 1989-12-09 Electrohydraulic proportional valve Expired - Lifetime EP0376023B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3844336A DE3844336A1 (en) 1988-12-30 1988-12-30 ELECTROHYDRAULIC PORPORTIONAL WAY VALVE
DE3844336 1988-12-30

Publications (3)

Publication Number Publication Date
EP0376023A2 EP0376023A2 (en) 1990-07-04
EP0376023A3 EP0376023A3 (en) 1991-04-17
EP0376023B1 true EP0376023B1 (en) 1994-03-09

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EP89122724A Expired - Lifetime EP0376023B1 (en) 1988-12-30 1989-12-09 Electrohydraulic proportional valve

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EP (1) EP0376023B1 (en)
DE (2) DE3844336A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0471884B1 (en) * 1990-08-24 1996-02-21 MOOG GmbH Electrohydraulic servovalve
DE4446144A1 (en) * 1994-12-23 1996-06-27 Bosch Gmbh Robert Hydraulic control in monoblock design from at least two interlinked electromagnetically actuated proportional directional control valve elements

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2840831C2 (en) * 1978-09-20 1984-06-28 Robert Bosch Gmbh, 7000 Stuttgart Electro-hydraulic directional valve

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Bosch Hydraulik, Proportionalwegeventile, Hydraulik in Theorie un Praxis, 1983, Robert Bosch GmbH, Geschäftsbereich K6, Hydraulik *

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DE58907181D1 (en) 1994-04-14
EP0376023A2 (en) 1990-07-04
EP0376023A3 (en) 1991-04-17
DE3844336A1 (en) 1990-07-05

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