EP0628731B1 - Pilot-actuated servovalve - Google Patents

Pilot-actuated servovalve Download PDF

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Publication number
EP0628731B1
EP0628731B1 EP94107440A EP94107440A EP0628731B1 EP 0628731 B1 EP0628731 B1 EP 0628731B1 EP 94107440 A EP94107440 A EP 94107440A EP 94107440 A EP94107440 A EP 94107440A EP 0628731 B1 EP0628731 B1 EP 0628731B1
Authority
EP
European Patent Office
Prior art keywords
pilot
main control
piston
control piston
valve
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
EP94107440A
Other languages
German (de)
French (fr)
Other versions
EP0628731A1 (en
Inventor
Arsène Bourkel
Bernd Lanfermann
Karl Tratberger
Karl-Heinz Post
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hydrolux SARL
Original Assignee
Hydrolux SARL
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Filing date
Publication date
Application filed by Hydrolux SARL filed Critical Hydrolux SARL
Publication of EP0628731A1 publication Critical patent/EP0628731A1/en
Application granted granted Critical
Publication of EP0628731B1 publication Critical patent/EP0628731B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • 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
    • F15B13/0435—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 the pilot valves being sliding 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
    • 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
    • F15B13/0401—Valve members; Fluid interconnections therefor
    • F15B13/0402—Valve members; Fluid interconnections therefor for linearly sliding valves, e.g. spool 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
    • 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
    • F15B13/0433—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 the pilot valves being pressure control 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
    • F15B20/002—Electrical failure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H01F7/16—Rectilinearly-movable armatures
    • H01F2007/1684—Armature position measurement using coils
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/86493—Multi-way valve unit
    • Y10T137/86574—Supply and exhaust
    • Y10T137/86582—Pilot-actuated
    • Y10T137/86606—Common to plural valve motor chambers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/86493—Multi-way valve unit
    • Y10T137/86574—Supply and exhaust
    • Y10T137/86582—Pilot-actuated
    • Y10T137/86614—Electric
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/86493—Multi-way valve unit
    • Y10T137/86574—Supply and exhaust
    • Y10T137/8667—Reciprocating valve
    • Y10T137/86694—Piston valve
    • Y10T137/86702—With internal flow passage

Definitions

  • the invention relates to a pilot operated servo valve with at least three main power connections.
  • Pilot operated electrohydraulic servo valves in two and multi-stage version with more than two Main power connections e.g. as 4-way valves, for Control of position, speed, power at Cylinders for linear movements or position, Speed and torque for hydraulic motors for Rotational movements, each of two displacement chambers have used.
  • These 4-way servo valves are conventional Design as a panel valve.
  • a The main spool of the main stage is directly in a valve housing or in one used in the housing Control sleeve fitted.
  • the confluence of the Main power connections are symmetrical with respect to the also formed symmetrical main control piston.
  • the hydraulic actuation of the main control piston takes place doing so by pressurizing its two end faces in Control chambers, which are on both sides of the valve housing flanged end caps are arranged.
  • This Control chambers are with control bores with a Pilot servo valve connected. Return springs are for Centering of the main spool provided.
  • Valves for block installation are available in various designs known. There are also servo valves with large ones Flow for block installation, however, these have only 2 Main power connections and are designed as seat valves. Screw-in block built-in valves are included in the mobile area 4 main power connections known, but as switching Directional valves are designed with direct solenoid actuation.
  • Valves of this type are, for example, in the book "The Hydraulic Trainer / Volume 2: Proportional and Servo valve technology ", publisher Mannesmann Rexroth GmbH (Germany), ISBN 3-8023-0266-4. At these valves is the valve body as a valve block for Build on a flat pad Hydraulic blocks trained. They all have one symmetrical main spool on its two End faces are arranged in control chambers. Return springs cause centering of the Main control piston.
  • the invention is based on the object pilot operated servo valve of the type described above create which saves space in a control block can be integrated and a clearly defined Has security position without losing out on a good one dynamic behavior of the servo valve to do without have to.
  • the pilot operated servo valve according to the invention is with its control sleeve directly into a stepped bore Control blocks used.
  • This control block then points side block holes for the second, third and everyone another main power connection.
  • This block hole for the first main power connection can, for example, directly in axial extension of the stepped bore for the control sleeve be carried out what with conventional piloted Servo valves with more than two main connections so far not possible. Bridge formation in the control block between individual junctions in the control sleeve are also no longer required.
  • inventive Servo valve is thus a much more compact design Control blocks achieved than with conventional ones Servo valves is the case.
  • Even in more complex ones Hydraulic controls can do the inventive Servo valve together with various additional valves, for example 2-way cartridge valves in a control block can be integrated to save space.
  • a direct installation in the The cylinder cover of larger cylinders is also possible.
  • the asymmetrical hydrostatic load on the main control piston appropriate dimensioning of the pressure compensation area of the Main control piston compensated.
  • hydrostatic Compensation will be the required actuation forces for the main spool, reducing the Operating areas in the control chambers are designed to be smaller can be. This results in smaller ones Tax oil volumes, that is, with the same size Pilot valve shorter positioning times can be achieved.
  • the second End of the main control piston axially sealed in the Pressure equalization chamber introduced to the Pressure compensation area as the second piston face to train.
  • This embodiment allows a more compact one Design of the valve than this with an annular Pressure equalization area is possible. The latter embodiment is not excluded, however.
  • a hydrostatic overcompensation of the servo valve is achieved when the axially effective area of the Pressure compensation area larger than the axially effective area the first piston face.
  • the pump connection (P) be axially inserted into the control sleeve; of the Tank connection (T) is between the first and second working connection.
  • Other assignments of the Main power connections are also possible without to the most important advantages of the invention To waive the servo valve.
  • the four control edges of the main spool point preferably a zero coverage.
  • the working connection (A) is therefore in the first End position of the main spool with the Tank connection (T) connected during the Working connection (B) via the pressure chamber with the Pump connection (P) is connected.
  • the second working connection (B) to the pump connection (P) blocked.
  • the Main control piston on a first auxiliary control edge which is assigned to the third and fourth control edge in such a way that in the first axial end position of the Main control piston the fourth axial hydraulic Axially closes the connection.
  • the third and fourth Control edges are then, for example, arranged in such a way that at the first axial end position of the main control piston the third axial hydraulic connection between Tank connection (T) and second working connection (B) is released.
  • the Servo valves become the first working port (A) and the second working connection (B) in the first end position of the Main control piston for pump connection (P) and Tank connection (T) blocked.
  • the main spool has first and second Auxiliary control edge on.
  • the first auxiliary control edge is the assigned third and fourth control edge such that they in the first axial end position of the main control piston fourth axial hydraulic connection closes.
  • the second auxiliary control edge is the first and second Control edge assigned such that it is axial at first End position of the main spool is the second axial hydraulic connection closes.
  • the first and second Control edges are arranged such that the first axial end position of the main spool, the first axial hydraulic connection between pump connection (P) and the first working connection (A) is closed.
  • the the third and fourth control edges are such arranged that in the first axial end position of the Main control piston the third axial hydraulic Connection between tank connection (T) and second Work port (B) is closed.
  • Unlock valve enables when it is relieved in a spring-centered basic position, for example with one Emergency stop or error signal that the main spool by the return spring, respectively by additional hydraulic pressure forces in its first axial end position is operated.
  • a hydraulic cylinder through Blocking of the work connections stopped, or by Connect the work connections to the tank without pressure be switched. This can lead to uncontrolled driving in an end position of the cylinder when errors are detected in the control electronics, machine control or even in Pilot valve itself can be avoided.
  • Valve versions also with a 3-way pilot valve enable the second control chamber with which in Direction of the first end position acting second Actuating area, with an always depressurized Tank line (Y) directly hydraulically connected.
  • the first control chamber with the opposite direction the first actuating surface acting the first end position, on the other hand with the working connection of the 3-way pilot valve hydraulically connected.
  • the main spool position sensor is in a first embodiment as a distance measuring system electrical output executed and in a closed Control loop integrated with the pilot valve.
  • the servo valve can also be used with mechanical Return.
  • a 3-way pilot spool valve in axial Extension of the second end of the main spool arranged which has a pilot pressure connection (P '), a pilot tank connection (T '), a pilot work connection (A ') and has a piston valve.
  • a measuring spring connects the pilot spool valve axially with the main spool, and one proportional to one electrical signal acting, control magnet is mechanical connected to the pilot spool.
  • the main spool is thus positioned in a closed position control loop up to Balance of forces between magnetic and measuring spring force is reached.
  • the pilot pressure connection (P ') is via the isolation valve with the pilot tank connection (T ') directly hydraulically connected, and the pilot valve is designed so that the Pilot work connection (A '), depending on the position of the Pilot spool, either with the pilot tank connection (T ') or the pilot pump connection (P') is directly connected hydraulically.
  • the main control piston drives the release valve as described in its first axial end position.
  • Figure 1 shows a longitudinal section through a first Version of the servo valve 3.
  • a control sleeve 5 is in a stepped bore 2 of a control block 1 is used.
  • a main control piston 6 axially slidably fitted.
  • the one shown in the figures Servo valve 3 is a 4-way servo valve and has one Pump connection (P), a tank connection (T), and one first working connection (A) and a second Working connection (B).
  • the pump connection (P) is hydraulic Connection to a pressure line (not shown). Of the Tank connection (T) is in hydraulic connection with a unpressurized line (not shown).
  • the Work ports (A) and (B) are hydraulic Connection with a first or second Displacement chamber of a hydraulic linear or Rotary drive (not shown).
  • a first control block bore 50 for the Pump connection (P) ends in a coaxial extension of the Stepped bore 2 in the control sleeve 5.
  • Three Block bores 51, 52, 53 for the tank connection (T) 51, first working port (A) 52 and the second Working connection (B) 53 are across the stepped bore 2 arranged and open laterally in the control sleeve 5. You form axially spaced annular openings 51 ', 52', 53 ', with corresponding Cross bores in the control sleeve 5.
  • control sleeve 5 connects a first axial hydraulic connection 28 the mouth 50 'for the Pump connection (P) with the mouth 52 'for the Working connection (A); a second axial hydraulic Connection 29 the mouth 51 'for the tank connection (T) with the mouth 52 'for the working connection (A); a third axial hydraulic connection 30 the junction 51 ' for the tank connection (T) with the mouth 53 'for the Working connection (B); and a fourth axial hydraulic Connection 31 the junction 53 'for the Working connection (B) with a coaxial inside the Control sleeve 5 arranged auxiliary connection chamber 22.
  • the main control piston 6 has a first coaxial Piston collar 8 on which the working connection (A) is assigned and axially in the first and second axial hydraulic connection 28 and 29 is displaceable, and a second coaxial piston collar 9, which the Working connection (B) is assigned and axially in the third and fourth axial hydraulic link 30 and 31 is slidable.
  • the first piston collar 8 forms one assigned to the first hydraulic connection 28 first control edge 28 'and one, the second hydraulic connection 29 assigned second Control edge 29 '. Both control edges 28 ', 29' point a zero coverage.
  • the second piston collar 9 forms one assigned to the third hydraulic connection 30 third control edge 30 'and one, the fourth hydraulic connection 31 assigned fourth Control edge 31 '. Both control edges 30 ', 31' point also a zero coverage.
  • auxiliary connection chamber 22 Via an axial piston bore 18 and a Piston transverse bore 19 is through the auxiliary connection chamber 22 the main control piston 6 with the pump connection (P) connected.
  • the main control piston therefore connects with its coaxial piston collar 8 the first Working connection (A) and with its coaxial piston collar 9 the second working connection (B) alternately with the Pump connection (P) or the tank connection (T), the respective flow of hydraulic fluid over the four Control edges 28 ', 29', 30 ', 31' is regulated.
  • the main control piston 6 is hydrostatically asymmetrical charged.
  • a hydrostatic pressure equalization of the Main control piston is carried out by continuing the coaxial piston bore 18 to the second end of the Main control piston 6, where it has a piston cross bore 20 opens into a pressure compensation chamber 25 which in one Valve cover 40 is arranged.
  • the second end of the Main spool is axially sealed by a Sealing insert 7, in this pressure compensation chamber 25 introduced and forms a pressure equalization approach 21.
  • This has one of the pressure equalization chamber 25 first piston face 12 hydrostatically counteracting Pressure equalization surface 13.
  • a complete one hydrostatic pressure equalization results when the Pressure compensation surface 13 is equal to the piston end surface 12 is chosen.
  • a hydrostatic overcompensation will occur reached when the pressure equalization surface 13 is larger than that Piston face 12 is selected.
  • the main control piston 6 is actuated via a machined coaxial actuating piston collar 11 by pressurizing its annular first or second actuating surface 14, 15.
  • the latter are in a first and second control chamber 26 and 27 arranged in the valve cover 40, where they over Pilot connections 56, 57 with the working connections (A ') and (B ') a flanged 4-way pilot servo valve 60 are connected.
  • Pilot connections 56, 57 with the working connections (A ') and (B ') a flanged 4-way pilot servo valve 60 are connected.
  • the actuating ring surfaces 14, 15 are just as large designed that when the control edges 28 ', 30 ', or 29', 31 'generated flow forces safely be overcome. This allows very short Positioning times for positioning the main control piston 6 at reach the specified pilot control valve 60.
  • the pressure equalization approach 21 enlarged in diameter so that the Pressure compensation area 13 larger than that Piston end face 12, this causes one Overcompensation with an additional hydrostatic Force to reset the main spool 6 in the first end position.
  • release valve 62 is in its spring-centered basic position (i.e. not actuated magnet), the control chamber (A ') 26 with the Operating area (A ') 14 relieved to the tank.
  • the 4-way pilot control valve Main control piston 6 in the first end position. Only at; only when Actuation of the release valve 62 becomes the 4-way pilot servo valve 60 for positioning the Main control piston 6 effective.
  • the positioning of the Main spool 6 also with a simplified 3-way pilot valve 61 can be performed (see Figure 5). It has a pilot pump connection (P '), one Pilot tank connection (T ') and a control connection (A') on.
  • the pilot pump connection (P ') is via the Control pressure line (X) pressurized.
  • the pre-tax tank connection (T ') is with an unpressurized Control line (Y) connected.
  • the control connection (A ') is via a release valve 62 with the first control chamber 26 connected.
  • the control chamber 27 with the actuating surface 15 which, by the above-described enlargement of the Pressure compensation area 13, smaller than that Actuating surface 14 of the control chamber 26 is permanent Relieved to the tank via the unpressurized control line (Y) 54.
  • the uncontrolled 3-way pilot valve 61 the Main control piston 6 in the rest position while at electrical control by pressurizing the larger actuation area 14 compared to the tank-relieved actuating surface 15 a hydraulic Control force arises, the main control piston 6, in the already described type, in electro-hydraulic Position control loop positioned. To do this, however Unlock valve 62 may be actuated. With discharge of the Isolation valve 62 in its basic position, e.g. as a result of an error that has occurred, the control chamber 26 relieved to the tank again, so that independent of the 3-way pilot valve 61, through the hydrostatic Overcompensation and by the return spring 24, the Main control piston 6 moves to the first end position.
  • Unlocking valve 62 does not require, this can also omitted, in which case the control chamber 26 directly with the Control port (A ') of 3-way pilot valve 61 connected is.
  • a Piston spool valve 67 in 3-way version is axial Extension of the main control piston 6 arranged. It points a pilot pump port (P ') 58, a pilot tank port (T ') 59, a control connection (A') 56 and a piston slide 68. The latter supports itself one end on a spring plate 69 in the Pressure compensation chamber 25 and is at its second end connected to a proportional magnet 66.
  • a Measuring spring 65 is in the pressure compensation chamber 25 between Spring plate 69 and main control piston 6 arranged.
  • Piston spool 68 is for the purpose of hydrostatic Pressure equalization, axially pierced. Independent of The position of the spool 68 is the control connection always with the pilot pump connection (P ') or the Pilot tank connection (T ') connected. Of the main control piston 6 is designed as in FIGS. 4 and 5 and thus has identical properties.
  • pilot pump connection (P ') 58' is additional a release valve 62 is arranged in the pilot pump connection (P ') 58'. With its electrical The pilot pump connection is relieved to the basic position (P ') 58 connected to the tank. Independently from the position of the pilot valve 67 is the Actuating surface (A ') 14 is therefore always depressurized to the tank relieved, whereby the main control piston 6 again by the hydrostatic overcompensation and the return spring 24 is operated in the first end position.

Abstract

A pilot-actuated servovalve with at least three main flow connections (50, 51, 52, 53) for space-saving installation in a control block is presented. The discharge into the control sleeve (5) for the first main flow connection (50) is formed opposite a piston end face (12) of the main control piston (6). In a pressure-compensation chamber (25), the main control piston (6) forms a pressure-compensation area (13). The pressure-compensation chamber (25) is hydraulically connected to the first main flow connection (50) by a pressure-relief passage (18, 20) in the main control piston (6). A return spring (24) exerts a spring force on the main control piston (6) in the direction of a first axial end stop and thus clearly secures a safety end position. The valve is distinguished by good dynamic behaviour. <IMAGE>

Description

Die Erfindung betrifft ein vorgesteuertes Servoventil mit mindestens drei Hauptstromanschlüssen.The invention relates to a pilot operated servo valve with at least three main power connections.

Vorgesteuerte elektrohydraulische Servoventile in zwei- und mehrstufiger Ausführung mit mehr als zwei Hauptstromanschlüssen werden, z.B. als 4-Wege-Ventile, zur Steuerung von Position, Geschwindigkeit, Kraft bei Zylindern für Linearbewegungen, respektiv Position, Drehzahl und Drehmoment bei Hydromotoren für Drehbewegungen, die jeweils zwei Verdrängerkammern aufweisen, eingesetzt.Pilot operated electrohydraulic servo valves in two and multi-stage version with more than two Main power connections, e.g. as 4-way valves, for Control of position, speed, power at Cylinders for linear movements or position, Speed and torque for hydraulic motors for Rotational movements, each of two displacement chambers have used.

Diese 4-Wege-Servoventile sind in der herkömmlichen Bauform als Plattenaufbauventile ausgeführt. Ein Hauptsteuerschieber der Hauptstufe ist dabei direkt in einem Ventilgehäuse oder in einer im Gehäuse eingesetzten Steuerhülse eingepasst. Die Einmündungen der Hauptstromanschlüsse sind symmetrisch in Bezug auf den ebenfalls symmetrischen Hauptsteuerkolben ausgebildet. Die hydraulische Betätigung des Hauptsteuerkolbens erfolgt dabei durch Druckbeaufschlagung seiner beiden Endflächen in Steuerkammern, welche in beidseitig am Ventilgehäuse angeflanschten Endkappen angeordnet sind. Diese Steuerkammern sind über Steuerbohrungen mit einem Vorsteuer-Servoventil verbunden. Rückstellfedern sind zur Mittenzentrierung des Hauptsteuerkolbens vorgesehen .These 4-way servo valves are conventional Design as a panel valve. A The main spool of the main stage is directly in a valve housing or in one used in the housing Control sleeve fitted. The confluence of the Main power connections are symmetrical with respect to the also formed symmetrical main control piston. The hydraulic actuation of the main control piston takes place doing so by pressurizing its two end faces in Control chambers, which are on both sides of the valve housing flanged end caps are arranged. This Control chambers are with control bores with a Pilot servo valve connected. Return springs are for Centering of the main spool provided.

Ventile für Blockeinbau sind in diversen Ausführungen bekannt. So gibt es auch Servoventile mit grossen Durchflüssen für Blockeinbau, jedoch haben diese nur 2 Hauptstromanschlüsse und sind als Sitzventile ausgeführt. Aus dem Mobilbereich sind Einschraub-Blockeinbauventile mit 4 Hauptstromanschlüssen bekannt, die jedoch als schaltende Wegeventile mit direkter Magnetbetätigung ausgeführt sind.Valves for block installation are available in various designs known. There are also servo valves with large ones Flow for block installation, however, these have only 2 Main power connections and are designed as seat valves. Screw-in block built-in valves are included in the mobile area 4 main power connections known, but as switching Directional valves are designed with direct solenoid actuation.

Von besonderer Bedeutung beim praktischen Einsatz von Servoventilen ist der Sicherheitsaspekt bei Ausfall oder Fehler in der elektrischen Ansteuerung oder im Vorsteuer-Servoventil. Ein solcher Ausfall darf nicht zu einer undefinierten Lage des Hauptsteuerkolbens und damit zu unkontrollierbaren Bewegungen des angeschlossenen Zylinders, z.B. Schliessbewegungen bei Pressen, führen.Of particular importance in the practical use of Servo valves are the safety aspect in the event of failure or Fault in the electrical control or in the pilot servo valve. Such a failure must not result in one undefined position of the main control piston and thus too uncontrollable movements of the connected Cylinders, e.g. Closing movements in presses.

Bekannte Lösungen bei mehrstufigen Servoventilen in Plattenaufbau-Ausführung sind so aufgebaut, dass ein zusätzliches elektrisch betätigtes Wegeventil zwischen dem Vorsteuer-Servoventil und den hydraulischen Steuerkammern des Hauptsteuerkolbens angeordnet ist. Bei Fehler schaltet dieses Wegeventil in seine federzentrierte Grundstellung zurück, unterbricht die Verbindung zum Vorsteuer-Servoventil und verbindet die Steuerkammern des Hauptsteuerkolbens so, dass letzterer durch zwei Druckfedern zwischen zwei Federtellern in Gehäuseanschlag mittenzentriert wird. Zum eindeutig definierten Verhalten der Zylinderbewegung bei Mittenzentrierung des Hauptsteuerkolbens, muss das Ventil jedoch eine positive Überdeckung der Steuerkanten mindestens zur Druckquelle aufweisen. Diese positive Überdeckung der Steuerkanten hat gegenüber der Nullüberdeckung der vier Steuerkanten zwischen Druckquelle, Arbeitsanschlüssen und Tankrücklauf, gravierende Nachteile bezüglich der erzielbaren Positioniergenauigkeit der Zylinderbewegung im Lageregelkreis und bei Einsatz des Ventils zu Druckregelung.Known solutions for multi-stage servo valves in Panel mounting designs are constructed so that a additional electrically operated directional valve between the pilot servo valve and the hydraulic Control chambers of the main control piston is arranged. At This directional valve switches into its fault spring-centered home position interrupts the Connection to the pilot control valve and connects the Control chambers of the main spool so that the latter by two compression springs between two spring plates in Housing stop is centered. To be clear defined behavior of the cylinder movement Centering the main spool, the valve must however a positive overlap of the control edges have at least to the pressure source. This positive Overlap of the control edges compared to the Zero coverage of the four control edges between Pressure source, work connections and tank return, serious disadvantages with regard to the achievable Positioning accuracy of the cylinder movement in the Position control loop and when using the valve too Pressure control.

Die vorliegende Erfindung betrifft ein vorgesteuertes Servoventil welches folgende technische Merkmale umfasst:

  • einen Hauptsteuerkolben mit einem ersten Ende und einem zweiten Ende,
  • einen Ventilkörper in welchem der Hauptsteuerkolben axial verschiebbar angeordnet ist,
  • in axialem Abstand zu einander angeordnete Einmündungen in den Ventilkörper für mindestens drei Hauptstromanschlüsse,
  • eine erste axiale hydraulische Verbindung innerhalb des Ventilkörpers zwischen der Einmündung für den ersten Hauptstromanschluss und der Einmündung für den zweiten Hauptstromanschluss,
  • eine zweite axiale hydraulische Verbindung innerhalb des Ventilkörpers zwischen der Einmündung für den zweiten Hauptstromanschluss und der Einmündung für den dritten Hauptstromanschluss,
  • eine, der ersten axialen hydraulischen Verbindung zum Regeln des Durchflusses zugeordnete, erste Steuerkante des Hauptsteuerkolbens,
  • eine, der zweiten axialen hydraulischen Verbindung zum Regeln des Durchflusses zugeordnete, zweite Steuerkante des Hauptsteuerkolbens ,
  • eine erste Steuerkammer, in welcher der Hauptsteuerkolben eine erste Betätigungsfläche ausbildet,
  • eine zweite Steuerkammer, in welcher der Hauptsteuerkolben eine, der ersten Betätigungsfläche axial entgegenwirkende, zweite Betätigungsfläche ausbildet,
  • ein Vorsteuerventil hydraulisch verbunden mit mindestens einer der beiden Steuerkammern, und
  • eine Rückführung zwischen Hauptsteuerkolben und Vorsteuerventil, in welche ein Positionsaufnehmer des Hauptsteuerkolbens eingebunden ist.
    • The present invention relates to a pilot operated servo valve which comprises the following technical features:
  • a main spool with a first end and a second end,
  • a valve body in which the main control piston is arranged to be axially displaceable,
  • openings at an axial distance from one another in the valve body for at least three main flow connections,
  • a first axial hydraulic connection within the valve body between the mouth for the first main flow connection and the mouth for the second main flow connection,
  • a second axial hydraulic connection within the valve body between the mouth for the second main flow connection and the mouth for the third main flow connection,
  • a first control edge of the main control piston assigned to the first axial hydraulic connection for regulating the flow,
  • a second control edge of the main control piston assigned to the second axial hydraulic connection for regulating the flow,
  • a first control chamber in which the main control piston forms a first actuating surface,
  • a second control chamber in which the main control piston forms a second actuating surface which axially counteracts the first actuating surface,
  • a pilot valve hydraulically connected to at least one of the two control chambers, and
  • a return between the main control piston and pilot valve, in which a position sensor of the main control piston is integrated.

    • Ventile dieser Bauart sind zum Beispiel in dem Buch "Der Hydraulik Trainer / Band 2 : Proportional- und Servoventil-Technik", Herausgeber Mannesmann Rexroth GmbH (Deutschland), ISBN 3-8023-0266-4, beschrieben. Bei diesen Ventilen ist Ventilkörper als Ventilblock zum Aufbau auf eine flache Anschlußfläche eines Hydraulikblocks ausgebildet. Sie weisen alle einen symmetrischen Haupsteuerkolben auf, dessen beiden Stirnseiten in Steuerkammern angeordnet sind. Rückstellfedern bewirken eine Mittenzentrierung des Haupsteuerkolbens.Valves of this type are, for example, in the book "The Hydraulic Trainer / Volume 2: Proportional and Servo valve technology ", publisher Mannesmann Rexroth GmbH (Germany), ISBN 3-8023-0266-4. At these valves is the valve body as a valve block for Build on a flat pad Hydraulic blocks trained. They all have one symmetrical main spool on its two End faces are arranged in control chambers. Return springs cause centering of the Main control piston.

    Der Erfindung liegt die Aufgabe zugrunde, ein vorgesteuertes Servoventil der vorbeschriebenen Art zu schaffen welches raumsparend in einen Steuerblock integriert werden kann und eine eindeutig festgelegte Sicherheitsstellung aufweist, ohne dabei auf ein gutes dynamisches Verhalten des Servoventils verzichten zu müssen.The invention is based on the object pilot operated servo valve of the type described above create which saves space in a control block can be integrated and a clearly defined Has security position without losing out on a good one dynamic behavior of the servo valve to do without have to.

    Diese Aufgabe wird erfindungsgemäss dadurch gelöst:

  • dass der Ventilkörper durch eine Steuerhülse ausgebildet wird in welcher die Einmündung für den ersten Hauptstromanschluss gegenüber einer ersten Kolbenstirnfläche am ersten Ende des Hauptsteuerkolbens ausgebildet ist, die Einmündungen für den zweiten, dritten und jeden weiteren Hauptstromanschluss seitlich zum Hauptsteuerkolben angeordnet sind,
  • dass der Hauptsteuerkolben in einer Druckausgleichskammer eine, der ersten Kolbenstirnfläche hydrostatisch entgegenwirkende, Kolbendruckausgleichfläche ausbildet, wobei die Druckausgleichskammer durch einen Druckentlastungskanal im Hauptsteuerkolben mit dem ersten Hauptstromanschluss hydraulisch verbunden ist, und
  • dass der Hauptsteuerkolben eine Anschlagfläche ausbildet, welche durch Zusammenwirken mit einer entsprechenden Gegenanschlagfläche eine erste axiale Endstellung des Hauptsteuerkolbens mechanisch festlegt, wobei eine Rückstellfeder dem Hauptsteuerkolben derart zugeordnet ist, dass sie auf letzteren eine Federkraft in Richtung seiner ersten axialen Endstellung ausübt.
    • According to the invention, this object is achieved by:
  • that the valve body is formed by a control sleeve in which the opening for the first main flow connection is formed opposite a first piston end face at the first end of the main control piston, the openings for the second, third and each further main flow connection are arranged laterally to the main control piston,
  • that the main control piston forms a piston pressure compensation surface in a pressure compensation chamber that hydrostatically counteracts the first piston end face, the pressure compensation chamber being hydraulically connected to the first main flow connection by a pressure relief channel in the main control piston, and
  • that the main control piston forms a stop surface, which mechanically defines a first axial end position of the main control piston by cooperation with a corresponding counter stop surface, a return spring being assigned to the main control piston in such a way that it exerts a spring force on the latter in the direction of its first axial end position.

    • Das erfindungsgemässe vorgesteuerte Servoventil wird mit seiner Steuerhülse direkt in eine Stufenbohrung eines Steuerblocks eingesetzt. Dieser Steuerblock weist dann seitliche Blockbohrungen für den zweiten, dritten und jeden weiteren Hauptstromanschluss auf. Betreffend die Anordnung der Blockbohrung für den ersten Hauptstromanschluss besteht jedoch grösstmögliche Freiheit. Diese Blockbohrung für den ersten Hauptstromanschluss kann zum Beispiel unmittelbar in axialer Verlängerung der Stufenbohrung für die Steuerhülse ausgeführt sein, was bei herkömmlichen vorgesteuerten Servoventilen mit mehr als zwei Hauptanschlüssen bis jetzt nicht möglich ist. Brückenbildungen im Steuerblock zwischen einzelnen Einmündungen in die Steuerhülse sind ebenfalls nicht mehr erfordert. Mit dem erfindungsgemässen Servoventil wird somit eine weitaus kompaktere Bauweise der Steuerblöcke erreicht, als dies bei herkömmlichen Servoventilen der Fall ist. Auch in komplexeren hydraulischen Steuerungen kann das erfindungsgemässe Servoventil zusammen mit diversen zusätzlichen Ventilen, zum Beispiel 2-Wege-Einbauventile, in einen Steuerblock raumsparend integriert werden. Ein direkter Einbau in den Zylinderdeckel von grösseren Zylindern ist ebenfalls möglich.The pilot operated servo valve according to the invention is with its control sleeve directly into a stepped bore Control blocks used. This control block then points side block holes for the second, third and everyone another main power connection. Regarding the arrangement there is a block hole for the first main power connection however the greatest possible freedom. This block hole for the first main power connector can, for example, directly in axial extension of the stepped bore for the control sleeve be carried out what with conventional piloted Servo valves with more than two main connections so far not possible. Bridge formation in the control block between individual junctions in the control sleeve are also no longer required. With the inventive Servo valve is thus a much more compact design Control blocks achieved than with conventional ones Servo valves is the case. Even in more complex ones Hydraulic controls can do the inventive Servo valve together with various additional valves, for example 2-way cartridge valves in a control block can be integrated to save space. A direct installation in the The cylinder cover of larger cylinders is also possible.

    Beim erfindungsgemässen Ventil wird die unsymmetrische hydrostatische Belastung des Hauptsteuerkolben durch entsprechende Dimensionierung der Druckausgleichsfläche des Hauptsteuerkolbens kompensiert. Durch diese hydrostatische Kompensation werden die erforderlichen Betätigungskräfte für den Hauptsteuerkolben verringert, wodurch die Betätigungsflächen in den Steuerkammern kleiner ausgelegt werden können. Es ergeben sich somit kleinere Steuerölvolumina, das heisst, dass bei gleich grossem Vorsteuerventil kürzere Stellzeiten erzielt werden.In the valve according to the invention, the asymmetrical hydrostatic load on the main control piston appropriate dimensioning of the pressure compensation area of the Main control piston compensated. Through this hydrostatic Compensation will be the required actuation forces for the main spool, reducing the Operating areas in the control chambers are designed to be smaller can be. This results in smaller ones Tax oil volumes, that is, with the same size Pilot valve shorter positioning times can be achieved.

    Durch die, durch unmittelbaren Gehäuseanschlag des Hauptsteuerkolbens, mechanisch definierte erste axiale Endstellung des Hauptsteuerkolbens, sowie durch die unmittelbar auf den Hauptsteuerkolben wirkende Rückstellfeder wird eine Sicherheitsstellung des Servoventils eindeutig festgelegt. Selbst bei Nullüberdeckung der Steuerkanten ist das Verhalten des erfindungsgemässen Ventils bei erster Endstellung des Hauptsteuerkolbens eindeutig festgelegt, was bei herkömmlichen, mittenzentrierten Servoventilen nicht möglich ist.By, by the immediate housing stop of the Main control piston, mechanically defined first axial End position of the main spool, as well as by the acting directly on the main spool Return spring is a safety position of the Servo valve clearly defined. Even at Zero overlap of the control edges is the behavior of the Valve according to the invention in the first end position of the Main control piston clearly defines what at conventional, center-centered servo valves are not is possible.

    Das erfindungsgemässe Ventil wird vorzugsweise als 4-Wegeventil ausgeführt. Dabei umfasst es zusätzlich:

  • eine zusätzliche seitliche Einmündung in die Steuerhülse für einen vierten Hauptstromanschluss,
  • eine über einen Querbohrung des Hauptsteuerkolbens mit dem Druckausgleichskanal des Hauptsteuerkolbens verbundene Hilfsanschlusskammer,
  • eine dritte axiale hydraulische Verbindung innerhalb der Steuerhülse zwischen der Einmündung für den dritten Hauptstromanschluss und der Einmündung für den vierten Hauptstromanschluss ,
  • eine vierte axiale hydraulische Verbindung innerhalb der Steuerhülse zwischen der Einmündung für den vierten Hauptstromanschluss und der Hilfsanschlusskammer,
  • eine dritte, der dritten axialen hydraulischen Verbindung zugeordnete Steuerkante des Hauptsteuerkolbens , und
  • eine vierte, der vierten axialen hydraulischen Verbindung zugeordnete Steuerkante des Hauptsteuerkolbens.
    • The valve according to the invention is preferably designed as a 4-way valve. It also includes:
  • an additional side opening into the control sleeve for a fourth main power connection,
  • an auxiliary connection chamber connected to the pressure compensation channel of the main control piston via a transverse bore of the main control piston,
  • a third axial hydraulic connection within the control sleeve between the mouth for the third main power connection and the mouth for the fourth main power connection,
  • a fourth axial hydraulic connection within the control sleeve between the opening for the fourth main power connection and the auxiliary connection chamber,
  • a third control edge of the main control piston assigned to the third axial hydraulic connection, and
  • a fourth control edge of the main control piston assigned to the fourth axial hydraulic connection.

    • Auch in dieser 4-Wege-Ausführung sind im Steuerblock keine Brückenbildungen für den Anschluss der Steuerhülse erforderlich.Also in this 4-way version are in the control block no bridging for the connection of the control sleeve required.

    In einer bevorzugten Ausführungsform wird das zweite Ende des Hauptsteuerkolbens axial abgedichtet in die Druckausgleichskammer eingeführt um dort die Druckausgleichsfläche als zweite Kolbenstirnfläche auszubilden. Diese Ausfürungsform erlaubt eine kompaktere Bauform des Ventils, als dies bei einer ringförmigen Druckausgleichsfläche möglich ist. Letztere Ausführungsform wird jedoch nicht ausgeschlossen.In a preferred embodiment, the second End of the main control piston axially sealed in the Pressure equalization chamber introduced to the Pressure compensation area as the second piston face to train. This embodiment allows a more compact one Design of the valve than this with an annular Pressure equalization area is possible. The latter embodiment is not excluded, however.

    Eine hydrostatische Überkompensation des Servoventils wird erreicht, wenn die axial wirksame Fläche der Druckausgleichsfläche grösser als die axial wirksame Fläche der ersten Kolbenstirnseite ist. Bei Druckbeaufschlagung des ersten Hauptstromanschlusses wirkt somit eine Stellkraft in Richtung dieses ersten Hauptstromanschlusses und kann zum Beispiel die Rückstellkraft der Rückstellfeder vorteilhaft ergänzen.A hydrostatic overcompensation of the servo valve is achieved when the axially effective area of the Pressure compensation area larger than the axially effective area the first piston face. When pressurized of the first main power connection thus acts Actuating force in the direction of this first main power connection and can, for example, the restoring force of the return spring advantageously add.

    Die Anschlüsse des Servoventils werden vorzugsweise wie folgt belegt:

  • der erste Hauptstromanschluss wird hydraulisch mit einer Pumpe verbunden und bildet somit einen Pumpenanschluss (P),
  • der zweite Hauptstromanschluss wird hydraulisch mit einer ersten Verdrängerkammer eines Verbrauchers verbunden und bildet somit einen ersten Arbeitsanschluss (A),
  • der dritte Hauptstromanschluss wird hydraulisch mit einem Tank verbunden und bildet somit einen Tankanschluss (T),
  • der vierte Hauptstromanschluss wird, falls vorhanden, hydraulisch mit einer zweiten Verdrängerkammer eines Verbrauchers verbunden und bildet somit einen zweiten Arbeitsanschluss (B).
    • The connections of the servo valve are preferably assigned as follows:
  • the first main power connection is hydraulically connected to a pump and thus forms a pump connection (P),
  • the second main flow connection is hydraulically connected to a first displacement chamber of a consumer and thus forms a first working connection (A),
  • the third main power connection is hydraulically connected to a tank and thus forms a tank connection (T),
  • the fourth main flow connection, if present, is hydraulically connected to a second displacement chamber of a consumer and thus forms a second working connection (B).

    • Bei dieser Ausführung kann der Pumpenanschluss (P) axial in die Steuerhülse eingeführt werden; der Tankanschluss (T) befindet sich zwischen dem ersten und zweiten Arbeitsanschluss. Andere Belegungen der Hauptstromanschlüsse sind jedoch ebenfalls möglich, ohne auf die wesentlichsten Vorteile des erfindungsgemässen Servoventils zu verzichten.With this version, the pump connection (P) be axially inserted into the control sleeve; of the Tank connection (T) is between the first and second working connection. Other assignments of the Main power connections are also possible without to the most important advantages of the invention To waive the servo valve.

    Es bleibt anzumerken, dass allgemein unter Pumpe eine hydraulische Druckquelle, unter Tank ein Gefäss oder eine Leitung ohne wesentlichen Gegendruck und unter Verbraucher ein hydraulischer Rotations- oder Linearantrieb verstanden wird.It should be noted that generally under pump one hydraulic pressure source, a tank or a tank Line without significant back pressure and under consumers understood a hydraulic rotary or linear drive becomes.

    Die vier Steuerkanten des Hauptsteuerkolbens weisen vorzugsweise eine Nullüberdeckung auf. Dadurch werden zum Beispiel eine ausgezeichnete Positioniergenauigkeit, bei Einsatz des Ventils in einem Lageregelkreis eines Hydraulikzylinders, und ein ausgezeichnetes Verhalten, bei Einsatz des Ventils zu Druckregelung, erzielt. Da das Ventil in Sicherheitsstellung nicht mittenzentriert ist, sondern eine axiale Endstellung aufweist, hat die Nullüberdeckung der Steuerkanten keine negative Auswirkung auf das Verhalten des Ventils in seiner Sicherheitsstellung.The four control edges of the main spool point preferably a zero coverage. As a result Example of excellent positioning accuracy, at Use of the valve in a position control loop Hydraulic cylinder, and excellent behavior when Use of the valve for pressure control achieved. Since that The valve is not centered in the safety position, but has an axial end position, has Zero coverage of the control edges has no negative impact on the behavior of the valve in its Security position.

    In einer ersten Ausführungsform des Servoventils nehmen bei erster axialer Endstellung des Hauptsteuerkolbens die Steuerkanten folgende Position ein:

  • die erste axiale hydraulische Verbindung ist durch die erste und/oder zweite Steuerkante verschlossen,
  • die zweite axiale hydraulische Verbindung ist freigegeben,
  • die dritte axiale hydraulische Verbindung ist durch die dritte und/oder vierte Steuerkante verschlossen,
  • die vierte axiale hydraulische Verbindung ist freigegeben.
    • In a first embodiment of the servo valve, the control edges assume the following position in the first axial end position of the main control piston:
  • the first axial hydraulic connection is closed by the first and / or second control edge,
  • the second axial hydraulic connection is released,
  • the third axial hydraulic connection is closed by the third and / or fourth control edge,
  • the fourth axial hydraulic connection is released.

    • Der Arbeitsanschluss (A) ist somit in der ersten Endstellung des Hauptsteuerkolbens mit dem Tankanschluss (T) verbunden, während der Arbeitsanschluss (B) über die Druckkammer mit dem Pumpenanschluss (P) verbunden ist.The working connection (A) is therefore in the first End position of the main spool with the Tank connection (T) connected during the Working connection (B) via the pressure chamber with the Pump connection (P) is connected.

    In einer vorteilhaften Ausgestaltung des Servoventils wird, in der ersten Endstellung des Hauptsteuerkolbens ,der zweite Arbeitsanschluss (B) zum Pumpenanschluss (P) gesperrt. In dieser Ausgestaltung weist der Hauptsteuerkolben eine erste Hilfssteuerkante auf, welche der dritten und vierten Steuerkante derart zugeordnet ist, dass sie bei der ersten axialen Endstellung des Hauptsteuerkolbens die vierte axiale hydraulische Verbindung axial verschliesst. Die dritte und vierte Steuerkanten sind dann, zum Beispiel, derart angeordnet, dass bei erster axialer Endstellung des Hauptsteuerkolbens die dritte axiale hydraulische Verbindung zwischen Tankanschluss (T) und zweitem Arbeitsanschluss (B) freigegeben ist.In an advantageous embodiment of the servo valve in the first end position of the main spool, the second working connection (B) to the pump connection (P) blocked. In this embodiment, the Main control piston on a first auxiliary control edge, which is assigned to the third and fourth control edge in such a way that in the first axial end position of the Main control piston the fourth axial hydraulic Axially closes the connection. The third and fourth Control edges are then, for example, arranged in such a way that at the first axial end position of the main control piston the third axial hydraulic connection between Tank connection (T) and second working connection (B) is released.

    In einer weiteren vorteilhaften Ausgestaltung des Servoventils werden der erste Arbeitsanschluss (A) und der zweite Arbeitsanschluss (B) in der ersten Endstellung des Hauptsteuerkolbens zum Pumpenanschluss (P) und zum Tankanschluss (T) gesperrt. In dieser Ausgestaltung weist der Hauptsteuerkolben eine erste und zweite Hilfssteuerkante auf. Die erste Hilfssteuerkante ist der dritten und vierten Steuerkante derart zugeordnet, dass sie in erster axialer Endstellung des Hauptsteuerkolbens die vierte axiale hydraulische Verbindung verschliesst. Die zweite Hilfssteuerkante ist der ersten und zweiten Steuerkante derart zugeordnet, dass sie bei erster axialer Endstellung des Hauptsteuerkolbens die zweite axiale hydraulische Verbindung verschliesst. Die erste und zweite Steuerkante sind dabei derart angeordnet, dass bei erster axialer Endstellung des Hauptsteuerkolbens, die erste axiale hydraulische Verbindung zwischen Pumpenanschluss (P) und erstem Arbeitsanschluss (A) verschlossen ist. Die dritte und vierte Steuerkante sind dagegen derart angeordnet, dass in erster axialer Endstellung des Hauptsteuerkolbens die dritte axiale hydraulische Verbindung zwischen Tankanschluss (T) und zweitem Arbeitsanschluss (B) verschlossen ist.In a further advantageous embodiment of the Servo valves become the first working port (A) and the second working connection (B) in the first end position of the Main control piston for pump connection (P) and Tank connection (T) blocked. In this embodiment points the main spool has first and second Auxiliary control edge on. The first auxiliary control edge is the assigned third and fourth control edge such that they in the first axial end position of the main control piston fourth axial hydraulic connection closes. The second auxiliary control edge is the first and second Control edge assigned such that it is axial at first End position of the main spool is the second axial hydraulic connection closes. The first and second Control edges are arranged such that the first axial end position of the main spool, the first axial hydraulic connection between pump connection (P) and the first working connection (A) is closed. The the third and fourth control edges, however, are such arranged that in the first axial end position of the Main control piston the third axial hydraulic Connection between tank connection (T) and second Work port (B) is closed.

    Die Kombination mit einem zusätzlich zwischen Vorsteuerventil und Hauptsteuerkolben angeordneten Freischaltventil ermöglicht bei dessen Entlastung in eine federzentrierte Grundstellung, zum Beispiel bei einem Notaus- oder Fehlersignal, dass der Hauptsteuerkolben durch die Rückstellfeder, respektiv durch zusätzliche hydraulische Druckkräfte in seine erste axiale Endstellung betätigt wird. Durch die vorbeschriebenen Ausführungen der Kolbengeometrie kann so z.B. ein Hydraulikzylinder durch Sperren der Arbeitsanschlüsse gestoppt, oder durch Verbinden der Arbeitsanschlüsse zum Tank drucklos geschaltet werden. Dadurch kann das unkontrollierte Fahren in eine Endstellung des Zylinders bei erkannten Fehlern in der Regelelektronik, Maschinensteuerung oder sogar im Vorsteuerventil selbst vermieden werden.The combination with an additional between Pilot valve and main spool arranged Unlock valve enables when it is relieved in a spring-centered basic position, for example with one Emergency stop or error signal that the main spool by the return spring, respectively by additional hydraulic pressure forces in its first axial end position is operated. Through the above-described versions of the Piston geometry can e.g. a hydraulic cylinder through Blocking of the work connections stopped, or by Connect the work connections to the tank without pressure be switched. This can lead to uncontrolled driving in an end position of the cylinder when errors are detected in the control electronics, machine control or even in Pilot valve itself can be avoided.

    Um eine Vorsteuerung der vorbeschriebenen Ventilausführungen auch mit einem 3-Wege-Vorsteuerventil zu ermöglichen, wird die zweite Steuerkammer, mit der in Richtung der ersten Endstellung wirkenden zweiten Betätigungsfläche, mit einer stets drucklosen Tankleitung (Y) unmittelbar hydraulisch verbunden. Die erste Steuerkammer, mit der in entgegengesetzte Richtung der ersten Endstellung wirkenden ersten Betätigungsfläche, wird dagegen mit dem Arbeitsanschluss des 3-Wege-Vorsteuerventil hydraulisch verbunden.To pre-control the above Valve versions also with a 3-way pilot valve enable the second control chamber with which in Direction of the first end position acting second Actuating area, with an always depressurized Tank line (Y) directly hydraulically connected. The first control chamber, with the opposite direction the first actuating surface acting the first end position, on the other hand with the working connection of the 3-way pilot valve hydraulically connected.

    Der Positionsaufnehmer des Hauptsteuerkolbens ist in einer ersten Ausgestaltung als Wegmesssystem mit elektrischem Ausgang ausgeführt und in einen geschlossenen Regelkreis mit dem Vorsteuerventil eingebunden.The main spool position sensor is in a first embodiment as a distance measuring system electrical output executed and in a closed Control loop integrated with the pilot valve.

    Das Servoventil kann jedoch ebenfalls mit mechanischer Rückführung ausgestattet sein. In dieser Ausführung ist dann ein 3-Wege-Vorsteuer-Schieberventil in axialer Verlängerung des zweiten Endes des Hauptsteuerkolbens angeordnet, welches einen Vorsteuer-Druckanschluss (P'), einen Vorsteuer-Tankanschluss (T'), einen Vorsteuer-Arbeitsanschluss (A') und einen Kolbenschieber aufweist. Eine Messfeder verbindet den Vorsteuer-Kolbenschieber axial mit dem Hauptsteuerkolben, und ein proportional zu einem elektrischen Signal wirkender, Stellmagnet ist mechanisch mit dem Vorsteuer-Kolbenschieber verbunden. Die Positionierung des Hauptsteuerkolbens erfolgt somit in einem geschlossenem Positionsregelkreis bis Kräftegleichgewicht zwischen Magnet- und Messfederkraft erreicht ist.The servo valve can also be used with mechanical Return. In this version is then a 3-way pilot spool valve in axial Extension of the second end of the main spool arranged, which has a pilot pressure connection (P '), a pilot tank connection (T '), a pilot work connection (A ') and has a piston valve. A measuring spring connects the pilot spool valve axially with the main spool, and one proportional to one electrical signal acting, control magnet is mechanical connected to the pilot spool. The The main spool is thus positioned in a closed position control loop up to Balance of forces between magnetic and measuring spring force is reached.

    Durch ein entsprechend in der Vorsteuerung angeordnetes Freischaltventil lässt sich auch bei einem 3-Wege-Vorsteuerventil zusätzliche Abschaltsicherheit bei Fehlererkennung erreichen. Der Vorsteuer-Druckanschluss (P') ist dabei über das Freischaltventil mit dem Vorsteuer-Tankanschluss (T') unmittelbar hydraulisch verbunden, und das Vorsteuerventil ist derart gestaltet, dass der Vorsteuer-Arbeitsanschluss (A'), je nach Stellung des Vorsteuer-Kolbenschiebers, entweder mit dem Vorsteuer-Tankanschluss (T') oder dem Vorsteuer-Pumpenanschluss (P') unmittelbar hydraulisch verbunden ist. Bei Entlastung des Freischaltventils fährt der Hauptsteuerkolben, wie vorbeschrieben, in seine erste axiale Endstellung. By a correspondingly in the pilot control arranged release valve can also be used with a 3-way pilot valve additional shutdown security Reach error detection. The pilot pressure connection (P ') is via the isolation valve with the pilot tank connection (T ') directly hydraulically connected, and the pilot valve is designed so that the Pilot work connection (A '), depending on the position of the Pilot spool, either with the pilot tank connection (T ') or the pilot pump connection (P') is directly connected hydraulically. With discharge of the The main control piston drives the release valve as described in its first axial end position.

    Ausführungsbeispiele der Erfindung sind in den beigefügten Zeichnungen dargestellt und werden im folgenden näher beschrieben. Es zeigen:

    • Figur 1 einen Längsschnitt durch eine erste Ausführung des Servoventils, mit 4-Wege-Vorsteuerventil;
    • Figur 2 einen Längsschnitt durch eine zweite Ausführung des Servoventils, mit 4-Wege-Vorsteuerventil;
    • Figur 3 einen Längsschnitt durch eine dritte Ausführung des Servoventils, mit 4-Wege-Vorsteuerventil;
    • Figur 4 einen Längsschnitt durch eine Ausführung des Servoventils wie in Figur 1, jedoch mit 4-Wege-Vorsteuerventil und Freischaltventil;
    • Figur 5 einen Längsschnitt durch eine Ausführung des Servoventils wie in Figur 1, jedoch mit 3-Wege-Vorsteuerventil und Freischaltventil;
    • Figur 6 einen Längsschnitt durch eine weitere Ausführung des Servoventils wie in Figur 1, jedoch mit integriertem 3-Wege-Vorsteuerventil mit mechanischer Rückführung und Freischaltventil.
    Embodiments of the invention are illustrated in the accompanying drawings and are described in more detail below. Show it:
    • Figure 1 shows a longitudinal section through a first embodiment of the servo valve, with 4-way pilot valve;
    • Figure 2 shows a longitudinal section through a second embodiment of the servo valve, with 4-way pilot valve;
    • Figure 3 shows a longitudinal section through a third embodiment of the servo valve, with 4-way pilot valve;
    • FIG. 4 shows a longitudinal section through an embodiment of the servo valve as in FIG. 1, but with a 4-way pilot valve and release valve;
    • 5 shows a longitudinal section through an embodiment of the servo valve as in FIG. 1, but with a 3-way pilot valve and release valve;
    • 6 shows a longitudinal section through a further embodiment of the servo valve as in FIG. 1, but with an integrated 3-way pilot valve with mechanical feedback and release valve.

    Figur 1 zeigt einen Längsschnitt durch eine erste Ausführung des Servoventils 3. Eine Steuerhülse 5 ist in eine Stufenbohrung 2 eines Steuerblockes 1 eingesetzt. In dieser Steuerhülse 5 ist ein Hauptsteuerkolben 6 axial verschiebbar eingepasst. Das in den Figuren gezeigte Servoventil 3 ist ein 4-Wege-Servoventil und weist einen Pumpenanschluss (P), einen Tankanschluss (T), sowie einen ersten Arbeitsanschluss (A) und einen zweiten Arbeitsanschluss (B) auf.Figure 1 shows a longitudinal section through a first Version of the servo valve 3. A control sleeve 5 is in a stepped bore 2 of a control block 1 is used. In this control sleeve 5 is a main control piston 6 axially slidably fitted. The one shown in the figures Servo valve 3 is a 4-way servo valve and has one Pump connection (P), a tank connection (T), and one first working connection (A) and a second Working connection (B).

    Der Pumpenanschluss (P) steht in hydraulischer Verbindung mit einer Druckleitung (nicht gezeigt). Der Tankschluss (T) steht in hydraulischer Verbindung mit einer drucklosen Leitung (nicht gezeigt). Die Arbeitsanschlüsse (A) und (B) stehen in hydraulischer Verbindung mit einer ersten, respektiv zweiten Verdrängerkammer eines hydraulischen Linear- oder Rotationsantrieb (nicht gezeigt). The pump connection (P) is hydraulic Connection to a pressure line (not shown). Of the Tank connection (T) is in hydraulic connection with a unpressurized line (not shown). The Work ports (A) and (B) are hydraulic Connection with a first or second Displacement chamber of a hydraulic linear or Rotary drive (not shown).

    Eine erste Steuerblockbohrung 50 für den Pumpenanschluss (P) mündet in koaxialer Verlängerung der Stufenbohrung 2 in die Steuerhülse 5. Drei Blockbohrungen 51, 52, 53 für den Tankanschluss (T) 51, den ersten Arbeitsanschluss (A) 52 und den zweiten Arbeitsanschluss (B) 53, sind quer zur Stufenbohrung 2 angeordnet und münden seitlich in die Steuerhülse 5. Sie bilden dabei, in axialem Abstand zueinander angeordnete, ringförmige Einmündungen 51', 52', 53', mit entsprechenden Querbohrungen in der Steuerhülse 5 aus.A first control block bore 50 for the Pump connection (P) ends in a coaxial extension of the Stepped bore 2 in the control sleeve 5. Three Block bores 51, 52, 53 for the tank connection (T) 51, first working port (A) 52 and the second Working connection (B) 53 are across the stepped bore 2 arranged and open laterally in the control sleeve 5. You form axially spaced annular openings 51 ', 52', 53 ', with corresponding Cross bores in the control sleeve 5.

    Innerhalb der Steuerhülse 5 verbindet eine erste axiale hydraulische Verbindung 28 die Einmündung 50' für den Pumpenanschluss (P) mit der Einmündung 52' für den Arbeitsanschluss (A); eine zweite axiale hydraulische Verbindung 29 die Einmündung 51' für den Tankanschluss (T) mit der Einmündung 52' für den Arbeitsanschluss (A); eine dritte axiale hydraulische Verbindung 30 die Einmündung 51' für den Tankanschluss (T) mit der Einmündung 53' für den Arbeitsanschluss (B); und eine vierte axiale hydraulische Verbindung 31 die Einmündung 53' für den Arbeitsanschluss (B) mit einer koaxial innerhalb der Steuerhülse 5 angeordneten Hilfsanschlusskammer 22. Bedingt durch die ringförmigen Einmündungen 51', 52', 53' ist der axiale Abstand zwischen der zweiten und dritten (29 und 30) axialen hydraulischen Verbindung weitaus grösser, als der axiale Abstand zwischen der ersten und zweiten (28 und 29), respektiv der dritten und vierten (30 und 31) axialen hydraulischen Verbindung.Within the control sleeve 5 connects a first axial hydraulic connection 28 the mouth 50 'for the Pump connection (P) with the mouth 52 'for the Working connection (A); a second axial hydraulic Connection 29 the mouth 51 'for the tank connection (T) with the mouth 52 'for the working connection (A); a third axial hydraulic connection 30 the junction 51 ' for the tank connection (T) with the mouth 53 'for the Working connection (B); and a fourth axial hydraulic Connection 31 the junction 53 'for the Working connection (B) with a coaxial inside the Control sleeve 5 arranged auxiliary connection chamber 22. Conditionally through the annular openings 51 ', 52', 53 ' axial distance between the second and third (29 and 30) axial hydraulic connection much larger than that axial distance between the first and second (28 and 29), respectively the third and fourth (30 and 31) axial hydraulic connection.

    Der Haupttsteuerkolben 6 weist einen ersten koaxialen Kolbenbund 8 auf, welcher dem Arbeitsanschluss (A) zugeordnet ist und axial in der ersten und zweiten axialen hydraulischen Verbindung 28 und 29 verschiebbar ist, sowie einen zweiten koaxialen Kolbenbund 9 auf, welcher dem Arbeitsanschluss (B) zugeordnet ist und axial in der dritten und vierten axialen hydraulischen Verbindung 30 und 31 verschiebbar ist. Der erste Kolbenbund 8 bildet eine, der ersten hydraulischen Verbindung 28 zugeordnete, erste Steuerkante 28' aus, sowie eine, der zweiten hydraulischen Verbindung 29 zugeordnete, zweite Steuerkante 29' aus. Beide Steuerkanten 28', 29' weisen eine Nullüberdeckung auf. Der zweite Kolbenbund 9 bildet eine, der dritten hydraulischen Verbindung 30 zugeordnete, dritte Steuerkante 30' aus, sowie eine, der vierten hydraulischen Verbindung 31 zugeordnete, vierte Steuerkante 31' aus. Beide Steuerkanten 30', 31' weisen ebenfalls eine Nullüberdeckung auf.The main control piston 6 has a first coaxial Piston collar 8 on which the working connection (A) is assigned and axially in the first and second axial hydraulic connection 28 and 29 is displaceable, and a second coaxial piston collar 9, which the Working connection (B) is assigned and axially in the third and fourth axial hydraulic link 30 and 31 is slidable. The first piston collar 8 forms one assigned to the first hydraulic connection 28 first control edge 28 'and one, the second hydraulic connection 29 assigned second Control edge 29 '. Both control edges 28 ', 29' point a zero coverage. The second piston collar 9 forms one assigned to the third hydraulic connection 30 third control edge 30 'and one, the fourth hydraulic connection 31 assigned fourth Control edge 31 '. Both control edges 30 ', 31' point also a zero coverage.

    Über eine axiale Kolbenbohrung 18 und eine Kolbenquerbohrung 19 ist die Hilfsanschlusskammer 22 durch den Hauptsteuerkolben 6 mit dem Pumpenanschluss (P) verbunden. Der Hauptsteuerkolben verbindet demnach mit seinem koaxialen Kolbenbund 8 den ersten Arbeitsanschluss (A) und mit seinem koaxialen Kolbenbund 9 den zweiten Arbeitsanschluss (B) wechselseitig mit dem Pumpenanschluss (P) oder dem Tankanschluss (T), wobei der jeweilige Durchfluss der Hydraulikflüssigkeit über die vier Steuerkanten 28', 29', 30', 31' geregelt wird.Via an axial piston bore 18 and a Piston transverse bore 19 is through the auxiliary connection chamber 22 the main control piston 6 with the pump connection (P) connected. The main control piston therefore connects with its coaxial piston collar 8 the first Working connection (A) and with its coaxial piston collar 9 the second working connection (B) alternately with the Pump connection (P) or the tank connection (T), the respective flow of hydraulic fluid over the four Control edges 28 ', 29', 30 ', 31' is regulated.

    Über seine druckbeaufschlagte Kolbenstirnfläche 12, ist der Hauptsteuerkolben 6 hydrostatisch unsymmetrisch belastet. Ein hydrostatischer Druckausgleich des Hauptsteuerkolbens erfolgt durch Weiterführung der koaxialen Kolbenbohrung 18 zum zweiten Ende des Hauptsteuerkolbens 6, wo sie über eine Kolbenquerbohrung 20 in eine Druckausgleichskammer 25 einmündet, welche in einem Ventildeckel 40 angeordnet ist. Das zweite Ende des Hauptsteuerkolbens ist, axial abgedichtet durch einen Dichteinsatz 7, in diese Druckausgleichskammer 25 eingeführt und bildet einen Druckausgleichsansatz 21 aus. Dieser weist in der Druckausgleichskammer 25 eine der ersten Kolbenstirnfläche 12 hydrostatisch entgegenwirkende Druckausgleichsfläche 13 auf. Ein vollständiger hydrostatischer Druckausgleich ergibt sich wenn die Druckausgleichsfläche 13 gleich der Kolbenstirnfläche 12 gewählt wird. Eine hydrostatische Überkompensation wird erreicht wenn die Druckausgleichsfläche 13 grösser als die Kolbenstirnfläche 12 gewählt wird.About its pressurized piston face 12, is the main control piston 6 is hydrostatically asymmetrical charged. A hydrostatic pressure equalization of the Main control piston is carried out by continuing the coaxial piston bore 18 to the second end of the Main control piston 6, where it has a piston cross bore 20 opens into a pressure compensation chamber 25 which in one Valve cover 40 is arranged. The second end of the Main spool is axially sealed by a Sealing insert 7, in this pressure compensation chamber 25 introduced and forms a pressure equalization approach 21. This has one of the pressure equalization chamber 25 first piston face 12 hydrostatically counteracting Pressure equalization surface 13. A complete one hydrostatic pressure equalization results when the Pressure compensation surface 13 is equal to the piston end surface 12 is chosen. A hydrostatic overcompensation will occur reached when the pressure equalization surface 13 is larger than that Piston face 12 is selected.

    Die Betätigung des Hauptsteuerkolbens 6 erfolgt über einen angearbeiteten koaxialen Betätigungskolbenbund 11 durch entsprechende Druckbeaufschlagung seiner ringförmigen ersten, respektiv zweiten Betätigungsfläche 14, 15 . Letztere sind in einer ersten und zweiten Steuerkammer 26 und 27 im Ventildeckel 40 angeordnet, wo sie über Vorsteuer-Anschlüsse 56, 57 mit den Arbeitsanschlüssen (A') und (B') eines angeflanschten 4-Wege-Vorsteuer-Servoventils 60 verbunden sind. Durch Rückführung der, mit einer elektrischen Wegmesvorrichtung 63, gemessenen Position des Hauptsteuerkolbens 6, und Soll-Istwert-Vergleich, in einem elektronischen Regelverstärker 64, ergibt sich demnach ein elektro-hydraulischer geschlossener Regelkreis.The main control piston 6 is actuated via a machined coaxial actuating piston collar 11 by pressurizing its annular first or second actuating surface 14, 15. The latter are in a first and second control chamber 26 and 27 arranged in the valve cover 40, where they over Pilot connections 56, 57 with the working connections (A ') and (B ') a flanged 4-way pilot servo valve 60 are connected. By returning the, with an electrical displacement measuring device 63 Position of the main control piston 6 and setpoint / actual value comparison, in an electronic control amplifier 64, this results in an electro-hydraulic closed Control loop.

    Die Betätigungsringflächen 14, 15 sind gerade so gross ausgelegt, dass die beim Überströmen der Steuerkanten 28', 30', bzw. 29', 31' entstehenden Strömungskräfte sicher überwunden werden. Dadurch lassen sich sehr kurze Stellzeiten zum Positionieren des Hauptsteuerkolbens 6 bei vorgegebenem Vorsteuerservoventil 60 erreichen.The actuating ring surfaces 14, 15 are just as large designed that when the control edges 28 ', 30 ', or 29', 31 'generated flow forces safely be overcome. This allows very short Positioning times for positioning the main control piston 6 at reach the specified pilot control valve 60.

    Zwei axial entgegengesetzte Endstellungen des Hauptsteuerkolbens 6 werden mechanisch durch eine Anschlagringfläche 16 des Hauptsteuerkolbens in der Steuerkammer 26, respektiv eine Anschlagendfläche 17 am zweiten Ende des Hauptsteuerkolbens festgelegt. Bei druckloser erster Steuerkammer 26 wird der Hauptsteuerkolben 6 durch eine Rückstellfeder 24, welche zum Beispiel in der Druckausgleichskammer 25 angeordnet ist, in die erste Endstellung gedrückt. In dieser ersten Endstellung liegt die Anschlagringfläche 16 an einer Gegenfläche 16' der Steuerhülse 5 an, wobei in Figur 1:

    • die erste Steuerkante 28' die erste hydraulische Verbindung 28 zwischen Pumpenanschluss (P) und Arbeitsanschluss (A) verschliesst;
    • die zweite Steuerkante 29' die zweite hydraulische Verbindung 29 zwischen Tankanschluss (T) und Arbeitsanschluss (A) freigibt;
    • die vierte Steuerkante 31' die vierte hydraulische Verbindung zwischen Pumpenanschluss (P) und Arbeitsanschluss (B) freigibt und die dritte hydraulische Verbindung 30 zwischen Tankanschluss (T) und Arbeitsanschluss (B) verschliesst.
    Two axially opposite end positions of the main control piston 6 are mechanically defined by a stop ring surface 16 of the main control piston in the control chamber 26, or respectively a stop end surface 17 at the second end of the main control piston. When the first control chamber 26 is depressurized, the main control piston 6 is pressed into the first end position by a return spring 24, which is arranged, for example, in the pressure compensation chamber 25. In this first end position, the stop ring surface 16 bears on a counter surface 16 'of the control sleeve 5, with in FIG. 1:
    • the first control edge 28 'closes the first hydraulic connection 28 between the pump connection (P) and the working connection (A);
    • the second control edge 29 'enables the second hydraulic connection 29 between the tank connection (T) and the working connection (A);
    • the fourth control edge 31 'releases the fourth hydraulic connection between the pump connection (P) and the working connection (B) and closes the third hydraulic connection 30 between the tank connection (T) and the working connection (B).

    In dieser Stellung ist somit der Arbeitsanschluss (A) drucklos zum Tank entlastet, der Arbeitsanschluss (B) jedoch über die Hilfsanschlusskammer 22 mit dem Pumpenanschluss (P) verbunden.In this position, the working connection (A) is depressurized to the tank, the working connection (B) however via the auxiliary connection chamber 22 with the Pump connection (P) connected.

    Bei vielen technischen Anwendungen z.B. in Pressen und Kunststoffspritzgiessmaschinen darf der vom Servoventil gesteuerte Zylinder jedoch keine Bewegung mehr ausführen, wenn eine Sicherheitsabschaltung erfolgt, oder die Ansteuerelektronik ausfällt bzw. dort ein Fehler auftritt. Beide Arbeitsanschlüsse (A) und (B) müssen dazu entweder drucklos zum Tank entlastet oder gesperrt werden, was bei Servoventilen mit Nullüberdeckung bis jetzt nicht möglich war.In many technical applications e.g. in presses and Plastic injection molding machines are allowed from the servo valve controlled cylinders stop moving, if there is a safety shutdown, or the Control electronics fail or an error occurs there. Both working connections (A) and (B) must either unpressurized to the tank or locked, which at Servo valves with zero overlap not yet possible was.

    In der Ventilausführung nach Figur 2 verschliesst ein zusätzlich am Hauptsteuerkolben 6 angearbeiteter erster koaxialer Hilfskolbenbund 32 mit seiner ersten Hilfssteuerkante 32' die vierte hydraulische Verbindung 31 von der Hilfsanschlusskammer 22 zum zweiten Arbeitsanschluss (B), während die dritte und vierte Steuerkante 30' und 31' des zweiten koaxialen Kolbenbundes 9 gleichzeitig die dritte hydraulische Verbindung 30 zwischen Tankanschluss (T) und Arbeitsanschluss (B) freigeben. Der erste Arbeitsanschluss (A) ist über die zweite Steuerkante 29' des ersten koaxialen Kolbenbundes 8 ebenfalls zum Tank entlastet, so dass ein angeschlossener Zylinder in beiden Anschlüssen drucklos geschaltet ist.Closes in the valve design according to FIG additionally worked on the main control piston 6 first coaxial auxiliary piston collar 32 with its first Auxiliary control edge 32 ′, the fourth hydraulic connection 31 from the auxiliary connection chamber 22 to the second Work port (B) while the third and fourth Control edge 30 'and 31' of the second coaxial Piston collar 9 simultaneously the third hydraulic Connection 30 between tank connection (T) and Release the working connection (B). The first Working connection (A) is via the second control edge 29 ' of the first coaxial piston collar 8 also to the tank relieved, leaving a connected cylinder in both Connections is depressurized.

    Eine Sicherheitsendstellung mit gesperrten Arbeitsanschlüssen (A) und (B), zur Verriegelung des Zylinders auch bei anstehenden äusseren Belastungen, wird in der Ausführung nach Figur 3 erreicht. Die Steuerkanten respektiv Hilfssteuerkanten 32', 33' sind so angeordnet, dass sie in erster axialer Endstellung des Hauptsteuerkolbens folgende Lage einnehmen:

    • die erste Hilfssteuerkante 32' verschliesst, wie in Figur 2, die vierte Verbindung 31 zwischen der Hilfsanschlusskammer 22 und dem Arbeitsanschluss (B);
    • die vierte Steuerkante 31' verschliesst die dritte hydraulische Verbindung 30 zwischen dem Tankanschluss (T) und dem Arbeitsanschluss (B);
    • die erste Steuerkante 28' verschliesst die erste hydraulische Verbindung 28 zwischen Pumpenanschluss (P) und Arbeitsanschluss (A);und
    • die zweite Hilfssteuerkante 33', an einem zweiten am Hauptsteuerkolben 6 angearbeiteten Hilfskolbenbund 33, verschliesst die zweite hydraulische Verbindung 29 zwischen dem Tankanschluss (T) und dem Arbeitsanschluss (A).
    A safety end position with blocked work connections (A) and (B) for locking the cylinder even when there are external loads is achieved in the embodiment according to FIG. 3. The control edges or auxiliary control edges 32 ', 33' are arranged such that they assume the following position in the first axial end position of the main control piston:
    • the first auxiliary control edge 32 'closes, as in FIG. 2, the fourth connection 31 between the auxiliary connection chamber 22 and the working connection (B);
    • the fourth control edge 31 'closes the third hydraulic connection 30 between the tank connection (T) and the working connection (B);
    • the first control edge 28 'closes the first hydraulic connection 28 between the pump connection (P) and the working connection (A);
    • the second auxiliary control edge 33 ', on a second auxiliary piston collar 33 worked on the main control piston 6, closes the second hydraulic connection 29 between the tank connection (T) and the working connection (A).

    Damit sind beide Arbeitsanschlüsse (A) und (B) sowohl zum Tank als auch druckseitig gesperrt.So both work ports (A) and (B) are both locked to the tank as well as the pressure side.

    Wird entsprechend Figur 4 der Druckausgleichsansatz 21 im Durchmesser so vergrössert, dass die Druckausgleichsfläche 13 grösser als die Kolbenstirnfläche 12 ist, bewirkt dieses eine Überkompensation mit einer zusätzlichen hydrostatischen Kraft zur Rückstellung des Hauptsteuerkolbens 6 in die erste Endstellung.According to FIG. 4, the pressure equalization approach 21 enlarged in diameter so that the Pressure compensation area 13 larger than that Piston end face 12, this causes one Overcompensation with an additional hydrostatic Force to reset the main spool 6 in the first end position.

    Durch ein zusätzlich zwischen dem Steueranschluss (A') 56 des 4-Wege-Vorsteuerservoventils 60 und der Steuerkammer (A') 26 angeordnetes Freischaltventil 62 wird in dessen federzentrierter Grundstellung ( d.h. bei nicht betätigtem Magneten) die Steuerkammer (A') 26 mit der Betätigungsfläche (A') 14 zum Tank entlastet. Unabhängig von der Stellung des 4-Wege-Vorsteuerservoventils fährt der Hauptsteuerkolben 6 in die erste Endstellung. Erst bei Betätigung des Freischaltventils 62 wird das 4-Wege-Vorsteuerservoventil 60 zur Positionierung des Hauptsteuerkolbens 6 wirksam.Through an additional between the control connection (A ') 56 of the 4-way pilot control valve 60 and Control chamber (A ') 26 arranged release valve 62 is in its spring-centered basic position (i.e. not actuated magnet), the control chamber (A ') 26 with the Operating area (A ') 14 relieved to the tank. Independently from the position of the 4-way pilot control valve Main control piston 6 in the first end position. Only at; only when Actuation of the release valve 62 becomes the 4-way pilot servo valve 60 for positioning the Main control piston 6 effective.

    Durch eine veränderte Vorsteuerung kann, zur Kostenreduzierung, die Positionierung des Hauptsteuerkolbens 6 auch mit einem vereinfachten 3-Wege-Vorsteuerventil 61 durchgeführt werden (siehe Figur 5). Es weist einen Vorsteuer-Pumpenanschluss (P'), einen Vorsteuer-Tankanschluss (T') und einen Steueranschluss (A') auf. Der Vorsteuer-Pumpenanschluss (P') ist über die Steuerdruckleitung (X) druckbeaufschlagt. Der Vorsteuer-Tankanschluss (T') ist mit einer drucklosen Steuerleitung (Y) verbunden. Der Steueranschluss (A') ist über ein Freischaltventil 62 mit der ersten Steuerkammer 26 verbunden. Die Steuerkammer 27 mit der Betätigungsfläche 15 die, durch die vorbeschriebene Vergrösserung der Druckausgleichsfläche 13, kleiner als die Betätigungsfläche 14 der Steuerkammer 26 ist, ist ständig über die drucklose Steuerleitung (Y) 54 zum Tank entlastet. Beim nicht angesteuerten 3-Wege-Vorsteuerventil 61 ist der Hauptsteuerkolben 6 in Arbeitsruhestellung, während bei elektrischer Ansteuerung durch Druckbeaufschlagung der grösseren Betätigungsfläche 14 gegenüber der tankentlasteten Betätigungsfläche 15 eine hydraulische Steuerkraft entsteht, die den Hauptsteuerkolben 6, in der bereits beschriebenen Art, im elektro-hydraulischen Positionsregelkreis positioniert. Dazu muss jedoch das Freischaltventil 62 betätigt sein. Bei Entlastung des Freischaltventils 62 in seine Grundstellung, z.B. infolge eines aufgetretenen Fehlers, wird die Steuerkammer 26 wieder zum Tank entlastet, so dass unabhängig vom 3-Wege-Vorsteuerventil 61, durch die hydrostatische Überkompensation und durch die Rückstellfeder 24, der Hauptsteuerkolben 6 in die erste Endstellung fährt.By changing the feedforward control, Cost reduction, the positioning of the Main spool 6 also with a simplified 3-way pilot valve 61 can be performed (see Figure 5). It has a pilot pump connection (P '), one Pilot tank connection (T ') and a control connection (A') on. The pilot pump connection (P ') is via the Control pressure line (X) pressurized. The pre-tax tank connection (T ') is with an unpressurized Control line (Y) connected. The control connection (A ') is via a release valve 62 with the first control chamber 26 connected. The control chamber 27 with the actuating surface 15 which, by the above-described enlargement of the Pressure compensation area 13, smaller than that Actuating surface 14 of the control chamber 26 is permanent Relieved to the tank via the unpressurized control line (Y) 54. In the case of the uncontrolled 3-way pilot valve 61, the Main control piston 6 in the rest position while at electrical control by pressurizing the larger actuation area 14 compared to the tank-relieved actuating surface 15 a hydraulic Control force arises, the main control piston 6, in the already described type, in electro-hydraulic Position control loop positioned. To do this, however Unlock valve 62 may be actuated. With discharge of the Isolation valve 62 in its basic position, e.g. as a result of an error that has occurred, the control chamber 26 relieved to the tank again, so that independent of the 3-way pilot valve 61, through the hydrostatic Overcompensation and by the return spring 24, the Main control piston 6 moves to the first end position.

    Ist die zusätzliche Sicherheit durch das Freischaltventil 62 nicht erfordert, kann dieses auch entfallen, wobei dann die Steuerkammer 26 direkt mit dem Steueranschluss (A') des 3-Wege-Vorsteuerventils 61 verbunden ist.Is the additional security through that Unlocking valve 62 does not require, this can also omitted, in which case the control chamber 26 directly with the Control port (A ') of 3-way pilot valve 61 connected is.

    Anstelle der in den Figuren 1 bis 5 eingesetzten elektrischen Rückführung mit dem elektrischen Wegmessystem 63, wird in der Ausführung nach Figur 6 eine mechanische Rückführung eingesetzt. Ein Kolbenschieberventil 67 in 3-Wege-Ausführung ist in axialer Verlängerung des Hauptsteuerkolbens 6 angeordnet. Es weist einen Vorsteuer-Pumpenanschluss (P') 58, einen Vorsteuer-Tankanschluss (T') 59, einen Steueranschluss (A') 56 und einen Kolbenschieber 68 auf. Letzterer stützt sich mit einem Ende auf einen Federteller 69 in der Druckausgleichskammer 25 und ist mit seinem zweiten Ende mit einem Proportionalmagnet 66 verbunden. Eine Messfeder 65 ist in der Druckausgleichskammer 25 zwischen Federteller 69 und Hauptsteuerkolben 6 angeordnet. Der Kolbenschieber 68 ist, zwecks hydrostatischem Druckausgleich, axial durchbohrt. Unabhängig von der Stellung des Kolbenschiebers 68 ist der Steueranschluss stets mit dem Vorsteuer-Pumpenanschluss (P') oder dem Vorsteuer-Tankanschluss (T') verbunden. Der Hauptsteuerkolben 6 ist wie in Figur 4 und 5 ausgeführt und hat somit identische Eigenschaften.Instead of the one used in Figures 1 to 5 electrical return with the electrical Displacement measuring system 63 becomes a in the embodiment according to FIG mechanical feedback used. A Piston spool valve 67 in 3-way version is axial Extension of the main control piston 6 arranged. It points a pilot pump port (P ') 58, a pilot tank port (T ') 59, a control connection (A') 56 and a piston slide 68. The latter supports itself one end on a spring plate 69 in the Pressure compensation chamber 25 and is at its second end connected to a proportional magnet 66. A Measuring spring 65 is in the pressure compensation chamber 25 between Spring plate 69 and main control piston 6 arranged. Of the Piston spool 68 is for the purpose of hydrostatic Pressure equalization, axially pierced. Independent of The position of the spool 68 is the control connection always with the pilot pump connection (P ') or the Pilot tank connection (T ') connected. Of the The main control piston 6 is designed as in FIGS. 4 and 5 and thus has identical properties.

    Durch Kraftvergleich zwischen dem zum elektrischen Steuerstrom proportionalen Kraftaufbau des Proportionalmagneten 66, als Sollwert, und der zur Stellung des Hauptsteuerkolbens 6 proportionale Federkraft der Messfeder 65, als Istwert, wird bei Abweichungen zwischen Soll- und Istwert das Vorsteuerschieberventil 67 mit seinem auf die Betätigungsfläche (A') 14 wirkenden Ausgangssteuerdruck solange ausgeregelt, bis die elektrisch vorgegebene Position im Positionsregelkreis erreicht ist.By comparing the force between the electrical Control current proportional power build-up of the Proportional magnets 66, as the setpoint, and the position of the main control piston 6 proportional spring force Measuring spring 65, as the actual value, is used for deviations between Setpoint and actual value, the pilot valve 67 with its acting on the actuating surface (A ') 14 Output control pressure adjusted until the electrical predetermined position in the position control loop has been reached.

    Im Vorsteuer-Pumpenanschluss (P') 58' ist zusätzlich ein Freischaltventil 62 angeordnet. Bei dessen elektrischer Entlastung in die Grundstellung wird der Vorsteuer-Pumpenanschluss (P') 58 mit dem Tank verbunden. Unabhängig von der Stellung des Vorsteuerschieberventils 67 ist die Betätigungsfläche (A') 14 damit immer drucklos zum Tank entlastet, wodurch der Hauptsteuerkolben 6 wieder durch die hydrostatische Überkompensation und die Rückstellfeder 24 in die erste Endstellung betätigt wird.In the pilot pump connection (P ') 58' is additional a release valve 62 is arranged. With its electrical The pilot pump connection is relieved to the basic position (P ') 58 connected to the tank. Independently from the position of the pilot valve 67 is the Actuating surface (A ') 14 is therefore always depressurized to the tank relieved, whereby the main control piston 6 again by the hydrostatic overcompensation and the return spring 24 is operated in the first end position.

    Auch bei dieser Ausführung kann bei reduzierten Sicherheitsanforderungen das Freischaltventil 62 entfallen, ohne die sichere Grundfunktion zu beeinträchtigen.Even with this version can be reduced Safety requirements for the isolation valve 62 are eliminated, without affecting the safe basic function.

    Claims (14)

    1. Pilot-actuated servovalve, comprising:
      a main control piston (6) with a first end and a second end;
      a valve body (5) in which the main control piston (6) is arranged so as to be capable of axial displacement;
      apertures into the valve body (5) for at least three main flow parts (50, 51, 52, 53) arranged at an axial interval to one another (50', 51', 52', 53');
      a first axial hydraulic connection (28) inside the valve body (5) between the aperture (50') for the first main flow part (50) and the aperture (52') for the second main flow part (52);
      a second axial hydraulic connection (29) inside the valve body (5) between the aperture (52') for the second main flow part (52) and the aperture (51') for the third main flow part (51);
      a first control edge (28') of the main control piston (6) allocated to the first axial hydraulic connection (28);
      a second control edge (29') of the main control piston (6), allocated to the second axial hydraulic connection (29);
      a first control chamber (26) in which the main control piston (6) forms a first actuating surface (14);
      a second control chamber (27) in which the main control piston (6) forms a second actuating surface (15) which takes effect axially against the first actuating surface (14);
      a pilot valve (60, 67), hydraulically connected to at least one of the two control chambers (26, 27); and
      a feedback between the main control piston (6) and the pilot valve (60, 67), into which a position sensor (65, 66) of the main control piston (6) is incorporated;
         characterised in that:
      the valve body is formed by a control sleeve (5), in which the aperture (50') for the first main flow connection (50) is formed opposite a piston front face (12) at the first end of the main control piston (6), and the apertures (51', 52', 53') for the second, third, and each further main flow connection (51, 52, 53) are arranged laterally to the main control piston (6);
      the main control piston forms a piston pressure compensation surface (13) in a pressure compensation chamber (25), which is hydrostatically opposing the piston front face (12), said pressure compensation chamber (25) being hydraulically connected by means of a pressure relief channel (18, 20) in the main control piston (6) to the first main flow connection (50); and
      the main control piston (6) forms a limit stop surface (16), which mechanically delimits by the interaction of a corresponding counter-limit stop surface (16'), a first axial end position of the main control piston (6), a resetting spring (24) being arranged in relation to the main control piston (6) in such a way that it exercises on the latter a spring force in the direction of its first axial end position.
    2. Pilot-actuated servovalve according to Claim 1, characterised by:
      a lateral aperture (53') in the control sleeve (5) for a fourth main flow part (53),
      an ancillary connection chamber (22), connected by means of a transverse bore (19) of the main control piston (6) to the pressure compensation channel (18) of the main control piston (6);
      a third axial hydraulic connection (30) inside the control sleeve (5) between the aperture (51'), for the third main flow part (51) and the aperture (53') for the fourth main flow part (53);
      a fourth axial hydraulic connection (31) inside the control sleeve (5) between the aperture for the fourth main flow part (53) and the ancillary connection chamber (22);
      a third control edge (30') of the main control piston (6) allocated to the third axial hydraulic connection (30); and
      a fourth control edge (31') of the main control piston (6) allocated to the fourth axial hydraulic connection (31).
    3. Pilot-actuated servovalve according to Claim 1 or 2, characterised in that the second end of the main control piston (6) is introduced in an axially sealed manner into the pressure compensation chamber (25), in order to form therein the pressure compensation surface (13) as a second piston front face.
    4. Pilot-actuated servovalve according to one of Claims 1 to 3, characterised in that the axially effective surface of the pressure compensation surface (13) is larger than the axially effective surface of the first piston front face (12).
    5. Pilot-actuated servovalve according to one of Claims 1 to 4, characterised in that:
      the first main flow part (50) is hydraulically connected to a pump, and therefore forms a pump part (P);
      the second main flow part (52) is hydraulically connected to a first displacement chamber of a consuming component, and therefore forms a first working part (A); and
      the third main flow part (51) is hydraulically connected to a pressureless tank, and therefore forms a tank part (T).
    6. Pilot-actuated servovalve according to Claim 2 and Claim 5, characterised in that the fourth main flow part (53) is hydraulically connected to a second displacement chamber of a consuming component, and therefore forms a second working part (B).
    7. Pilot-actuated servovalve according to one of Claims 2, 3, 4 or 6, characterised in that:
      the four control edges of the main control piston (6) feature zero overlap; and
      in the first axial end position of the main control piston,
      the first axial hydraulic connection (28) is closed by the first and/or second control edge(s) (28', 29');
      the second axial hydraulic connection (29) is cleared;
      the third axial hydraulic connection (30) is closed by the third and/or fourth control edge(s) (30', 31');
      the fourth axial hydraulic connection (31) is cleared.
    8. Pilot-actuated servovalve according to one of Claims 2 to 7, characterised in that :
      the first and second control edges (28', 29') are arranged in such a manner that at the first axial end position of the main control piston (6) at least one of the edges closes the first axial hydraulic connection (28);
      the third and fourth control edges (30', 31') are arranged in such a manner that at the first axial end position of the main control piston (6) at least one of the edges closes the third axial hydraulic connection (30);
      a first ancillary control edge (32') is arranged in such a manner that at the first axial end position of the main control piston (6) closes the fourth axial hydraulic connection (31); and
      a second ancillary control edge (33') is arranged in such a manner that at the first axial end position of the main control piston (6) it closes the second axial hydraulic connection (29).
    9. Pilot-actuated servovalve according to one of Claims 2 to 7, characterised in that:
      the first and second control edges (28', 29') are arranged in such a manner that at the first axial end position of the main control piston (6) at least one of these edges closes the first axial hydraulic connection (28);
      the third and fourth control edges (30', 31') are arranged in such a way that at the first axial end position of the main control piston (6) the third axial hydraulic connection (30) is cleared;
      an ancillary control edge (32') is arranged in such a manner that at the first axial end position of the main control piston (6) it closes the fourth axial hydraulic connection (31).
    10. Pilot-actuated servovalve according to one of Claims 6 to 9, characterised in that:
      an isolating valve (62) is connected between the first control chamber (26), with said first actuation surface (14) acting in the opposed direction to the first axial end position, and the pilot valve (60); and
      this isolating valve (62) provides in its basic setting a hydraulic connection between the first control chamber (26) and the pressureless pilot line (Y) (54).
    11. Pilot-actuated servovalve according to one of Claims 6 to 9, characterised in that:
      the second control chamber (27), with said second actuation surface (15), acting in the direction to the first end position, is directly hydraulically connected to a pressureless pilot line (Y) (54); and
      the first control chamber (26), with said first actuation surface (14) acting in the opposed direction to the first end position, is hydraulically connected to a control part (A') of the pilot valve, said pilot valve being a three-way pilot valve (61).
    12. Pilot-actuated servovalve according to Claim 11, characterised in that :
         the position sensor of the main control piston (6) is designed as a path measuring system (63) with an electrical output, and is connected into a closed loop control circuit with the three-way pilot valve (61).
    13. Pilot-actuated servovalve according to Claim 11, characterised in that:
      the pilot valve is a three-way spool-type pilot valve (67) in an axial extension of the second end of the main control piston (6), which has a pilot pressure part (P') (58), a pilot tank part (T) (59), a pilot working part (A') (56), and a spool-type valve piston (68) ;
      a measuring spring (65) connects the spool-type valve piston (68) axially to the main control piston (6); and
      an actuating solenoid (66), which is proportionally responsive to an electrical signal, is connected mechanically to the spool-type valve piston.
    14. Pilot-actuated servovalve according to Claim 13, characterised in that:
      the pilot pressure part (P') (58) is connected by means of an isolating valve (62), in its basic setting, with the pilot tank part (T') (59); and
      the spool-type pilot valve (67) is designed in such a way that the control part (A') (56), depending on the position of the spool-type valve piston (68) is directly connected hydraulically either to the pilot tank part (T) (59) or to the pilot pump part (P') (58).
    EP94107440A 1993-05-27 1994-05-13 Pilot-actuated servovalve Expired - Lifetime EP0628731B1 (en)

    Applications Claiming Priority (2)

    Application Number Priority Date Filing Date Title
    LU88277 1993-05-27
    LU88277A LU88277A1 (en) 1993-05-27 1993-05-27 Pilot operated servo valve

    Publications (2)

    Publication Number Publication Date
    EP0628731A1 EP0628731A1 (en) 1994-12-14
    EP0628731B1 true EP0628731B1 (en) 1998-07-15

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    US (1) US5445188A (en)
    EP (1) EP0628731B1 (en)
    JP (1) JP3519122B2 (en)
    CN (1) CN1041344C (en)
    AT (1) ATE168450T1 (en)
    CA (1) CA2124429C (en)
    DE (1) DE59406438D1 (en)
    LU (1) LU88277A1 (en)
    RU (1) RU2124666C1 (en)

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    Also Published As

    Publication number Publication date
    CA2124429C (en) 2004-01-27
    JPH06341409A (en) 1994-12-13
    CN1098484A (en) 1995-02-08
    JP3519122B2 (en) 2004-04-12
    US5445188A (en) 1995-08-29
    RU2124666C1 (en) 1999-01-10
    ATE168450T1 (en) 1998-08-15
    DE59406438D1 (en) 1998-08-20
    CA2124429A1 (en) 1994-11-28
    CN1041344C (en) 1998-12-23
    LU88277A1 (en) 1994-12-01
    EP0628731A1 (en) 1994-12-14

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