WO1999024720A1 - Circuit hydraulique - Google Patents

Circuit hydraulique Download PDF

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Publication number
WO1999024720A1
WO1999024720A1 PCT/DE1998/003050 DE9803050W WO9924720A1 WO 1999024720 A1 WO1999024720 A1 WO 1999024720A1 DE 9803050 W DE9803050 W DE 9803050W WO 9924720 A1 WO9924720 A1 WO 9924720A1
Authority
WO
WIPO (PCT)
Prior art keywords
valve
pressure
control
load pressure
proportional valve
Prior art date
Application number
PCT/DE1998/003050
Other languages
German (de)
English (en)
Inventor
Winfried RÜB
Original Assignee
Mannesmann Rexroth Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mannesmann Rexroth Ag filed Critical Mannesmann Rexroth Ag
Publication of WO1999024720A1 publication Critical patent/WO1999024720A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/05—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed specially adapted to maintain constant speed, e.g. pressure-compensated, load-responsive
    • 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
    • F15B13/044—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated by electrically-controlled means, e.g. solenoids, torque-motors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30525—Directional control valves, e.g. 4/3-directional control valve
    • F15B2211/3053—In combination with a pressure compensating valve
    • F15B2211/30535—In combination with a pressure compensating valve the pressure compensating valve is arranged between pressure source and directional control valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/355—Pilot pressure control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/365—Directional control combined with flow control and pressure control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/55—Pressure control for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/635—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements
    • F15B2211/6355—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements having valve means

Definitions

  • the invention relates to a hydraulic circuit for controlling a consumer according to the preamble of claim 1 and a method for controlling such a circuit.
  • LS system load sensing system
  • two consumers 2, 4 can be supplied with hydraulic fluid by means of a hydraulic pump, which is designed as a constant pump 6 in the exemplary embodiment shown.
  • the latter is assigned an inlet pressure compensator 8, which is acted upon on the one hand by the pressure at the pump outlet (pl) and on the other hand by the highest load pressure of the two consumers 2,4.
  • This highest load pressure is fed to the face of the inlet pressure compensator 8 via a shuttle valve 10.
  • An individual pressure compensator 12 and a proportionally adjustable directional control valve 14 are connected in series in the feed lines to the consumers 2, 4.
  • the individual pressure compensator 12 can be arranged in the direction of pressure build-up in front of the proportional valve 14 (see FIG. 1) or else after the proportional valve 14.
  • the pressure at the input of the proportional valve 14 also acts on one end face of the individual pressure compensator 12.
  • the other end face is acted upon by the load pressure, which is also present on an end face of the inlet pressure compensator 8.
  • the individual pressure compensator and the proportional valve 14 thus form a continuously adjustable flow control valve.
  • the proportional valve has the function of an adjustable measuring orifice on which the pressure drop is kept constant by the individual pressure compensator 12, so that a load pressure independent but adjustable flow volume flow is adjustable.
  • the volume flows to the consumers are always in the ratio of the opening cross-sections of the orifice plates.
  • the most heavily loaded consumer can stop if the sum of the requested volume flows of all consumers is greater than the maximum delivery flow of the pump.
  • a disadvantage of the circuit described above is that the system is essentially influenced by influencing the delivery flow supplied by the pump 6. If one of the consumers 2, 4 is moved back under the influence of external loads, such as in agricultural machinery, forklift trucks, snow plows, mowers etc., the load pressure which increases as a result cannot be limited by influencing the pump 6 but only by additional secondary pressure relief valves.
  • a disadvantage of these systems is that the hydraulic oil volume flow to or from the consumer has to flow through the secondary pressure relief valve, so that corresponding energy losses occur.
  • the invention is based on the object of a hydraulic circuit for controlling a consumer and a method for controlling such a device
  • the measure of applying a control pressure difference to the two end faces of the valve slide by means of which the valve slide is moved into such a control position when a predetermined maximum pressure is reached, since the load pressure is limited to the predetermined value, no additional valves for load pressure Limitation in work lines required.
  • the pressure is thus limited only by adjusting the proportional valve as a function of an applied control pressure, so that no unnecessary energy losses occur when the pressure is limited by a pressure relief valve connected to the supply line or the return line.
  • control lines are routed to the end faces of the valve spool, which are operatively connected to one another via a comparison or pressure valve, which acts on the end faces of the valve spool with the corresponding control pressure difference when the predetermined maximum pressure is reached.
  • both valve faces are subjected to the same pressures.
  • the highest load pressure or any other system pressure can be Slider end faces are guided. The designer thus has more leeway to design the circuit
  • the hydraulic circuit described above and the method for controlling it can also be used if the proportional valve is not assigned an individual pressure compensator. If the system works with an individual pressure compensator, this can be connected upstream or downstream of the proportional valve.
  • a circuit of particularly simple construction is obtained if the two control lines carry the highest load pressure and are connected to one another via a connecting line with throttles, a pressure relief valve being provided in order to connect one of the control lines to a tank when the maximum pressure is reached, so that the Directional valve spool is moved into its control position by the pressure difference.
  • This pressure limiting valve is preferably electrically pilot-operated so that the maximum load pressure setting can be carried out in a particularly simple manner.
  • the comparison valve can be a hydraulically actuated proportional valve, in which one side of the control valve spool is subjected to the load pressure, while the other side of the control valve spool is acted upon by the force of a control spring and the pressure in the return line.
  • the control slide is moved due to the pressure difference applied to its end faces into a deflection position in which an end face of the directional valve spool is acted upon by the pump pressure, so that it is brought into its control position.
  • control spring is preferably subjected to an adjustable preload.
  • the pressure valve is designed as a 2/2-way valve, one end face of which the load pressure can be applied to and that when the maximum load pressure is reached, the 2/2-way valve is moved from its spring-loaded blocking position into a through position in which the proportional valve spool is moved into its control position in order to limit the load pressure to the maximum value.
  • the latter alternative is particularly suitable for movements of pliers or other movements in which an object is held with limited pressure.
  • both the inflow to the consumer and the return flow from the consumer to the tank can be influenced.
  • FIG. 1 shows the structure of a conventional hydraulic circuit for controlling several consumers
  • FIG. 3 shows an exemplary embodiment of the circuit from FIG. 2 with a mechanically controlled proportional directional control valve; 4 shows an exemplary embodiment with an electrically controlled proportional directional control valve;
  • Fig. 5 shows an embodiment in which the comparison valve is designed as a 2/2-way valve
  • Fig. 6 shows another embodiment of a circuit according to the invention, in which the comparison valve is designed as a pressure relief valve
  • Fig. 7 is a plate valve which is constructed after the circuit of FIG. 6.
  • FIG. 2 shows the essential part of the invention of a hydraulic circuit for supplying several consumers, which in principle can be constructed, for example, similar to that as shown in FIG. 1.
  • each consumer 2, 4 is assigned a proportional valve 14 and the highest acting load pressure is fed via a shuttle valve circuit to a constant pump with inlet pressure compensator (6,8 in Fig. 1) or to the pump regulator of a control pump.
  • the proportional valve 14 is generally associated with an individual pressure compensator 12, which can be connected downstream or upstream of the proportional valve 14.
  • this individual pressure compensator 12 can also be dispensed with, so that in the case of such circuits without an individual pressure compensator, the volume flows to those consumers with a lower load pressure are dependent on the pump pressure and on their own load pressure if no other suitable measures are taken.
  • the function essential to the invention is independent of whether individual pressure compensators are provided or not.
  • the proportional valve 14 can be an electrically, hydraulically or mechanically controlled valve and, in the spring-loaded neutral position shown, shuts off two working connections A, B connected to one of the consumers 2 or 4, opposite a pump connection P, and a tank connection T.
  • the connection from the pump connection P to the working connection B is opened, so that the consumer 2 in FIG. 1 is supplied with hydraulic fluid becomes.
  • This consumer can be a hydraulic cylinder, for example, which is then extended.
  • the hydraulic fluid flowing back from the consumer is led via the connection A to the tank connection T.
  • the cylinder space of the hydraulic cylinder would be supplied with hydraulic fluid, while the annular space would be relieved towards the tank.
  • the working connection B When moving the proportional valve spool in the positions labeled b, the working connection B is connected in the opposite way to the pump connection P and the working connection A to the tank connection T, so that the annular space (FIG. 1) of the consumer 2 is supplied with hydraulic fluid and that Hydraulic fluid located in the cylinder space to the tank T is expanded.
  • the proportional valve is activated on the basis of a certain mechanical, hydraulic or electrical control pulse, so that the proportional valve slide is brought into a position in which the consumer is supplied with the predetermined fluid volume flow.
  • the proportional valve 14 is assigned a comparison valve arrangement 16 which, depending on the load pressure on the consumer, applies a control difference to the end faces of the proportional valve slide, so that when a maximum load pressure is reached it is shifted into a position in which the load pressure on the consumer cannot continue to rise.
  • the reverse flow can also be controlled in the reverse manner.
  • the comparison valve arrangement 16 has the effect that both end faces are acted upon by the same control pressure below the maximum load pressure, while when the limit value is reached a control pressure difference is built up by which the proportional valve spool is displaced such that the inflow of hydraulic fluid to the consumer is throttled and hydraulic fluid flowing back can be drained from the consumer to the tank.
  • the comparison valve arrangement 16 is connected to the working lines connected to the connections A and B via load pressure lines 18, 20.
  • a control pressure difference is applied to the end faces of the proportional valve spool via control connections X, Y, so that it can be moved into the desired position to limit the load pressure at the associated consumer.
  • FIG 3 shows an exemplary embodiment in which the proportional valve 14 is operated by hand in order to supply the consumer with the desired hydraulic volume flow.
  • the comparison valve 16 is designed as a 4-way proportional valve, which in its basic position 0 is the two
  • valve spool When the valve spool is displaced into the positions labeled e, the connection from the pump port P to the control port X and the connection between the control port Y and the tank port T are opened, so that the proportional valve spool is acted upon in the opposite direction with a control pressure.
  • valve spool of the comparison valve 16 is biased into its neutral position 0 by means of compression springs 22, 24, the compression springs 22, 24 acting on the valve spool of the comparison valve 16 with an adjustable preload. This means that the valve slide can only be moved from its neutral position when the spring preload of one of the compression springs 22, 24 is overcome.
  • the load pressure in the working lines is guided via the load pressure lines 18, 20 to the end faces of the valve slide of the comparison valve 16.
  • the spring preload of the two compression springs 22, 24 is set such that the valve slide of the comparison valve 16 is only shifted from its neutral position when the load pressure difference in the load pressure lines 18, 20 exceeds a predetermined maximum value.
  • the proportional valve 14 is actuated, for example, in such a way that the proportional valve slide into the ones marked here with a Positions are brought so that the connection from the pump connection P to the working connection B is opened and the connection from the working connection A to the tank connection T is opened.
  • the consumer is supplied with the predetermined hydraulic fluid volume flow.
  • the comparison valve 16 remains in its neutral position 0, in which both end faces of the proportional valve spool are subjected to the same control pressures. In the present case, these control pressures are equal to the pressure acting on the tank connection T.
  • the load pressure limitation takes place in the reverse manner.
  • the load pressure can be adjusted by changing the preload of the compression springs 22, 24.
  • FIG. 4 shows an embodiment in which the proportional valve 14 is designed as an electrically operated valve.
  • This proportional valve is provided with a further control connection Z, via which the pressure at the pump connection P is guided by means of a control line 28 to a control connection Z 'on the comparison valve 16.
  • This comparison valve 16 has practically the same structure as that in FIG. 3, but the switch positions d and e are interchanged.
  • control connection Z is connected to the tank connection T.
  • the valve spool of the comparison valve 16 is also in its neutral position 0, in which the control connections X, Y are connected to the control connection Z 'and thus via the control line 28 and the control connection Z to the tank connection T. This means that the tank pressure is present on both ends of the proportional valve spool.
  • the working connections A, B and the pump connection P are shut off.
  • the proportional valve slide When energizing the electromagnet arranged on the left in FIG. 4, the proportional valve slide is brought into its positions indicated by a, in which the pump connection P is connected to the working connection A and the working connection B is connected to the tank connection T.
  • the pressure is via the control connection Z. at connection P or at connection A via control line 28 to control connection Z 'and from there via control connections X, Y to the end faces of the proportional valve spool. Since these two pressures are the same, they compensate each other so that the proportional valve spool eventually shifted by the action of the electromagnet.
  • the consumer is now supplied with hydraulic fluid via the working line connected to the working connection A, so that the load pressure in this working line rises and is led via the load pressure line 18 to the left end face of the valve slide of the comparison valve 16 in FIG. 4.
  • the load pressure in the working line connected to the working connection B is led via the load pressure line 20 to the other end face.
  • the valve spool of the comparison valve 16 is brought against the action of the compression spring 22 marked positions in which the control connection Z 'are connected to the control line X and the control line Y to the tank connection T, since at the control connection Z' 4, the right end face of the proportional valve spool in FIG.
  • the load pressure in the other working line can of course be limited in the opposite manner by actuating the proportional valve 14.
  • FIG. 5 shows an exemplary embodiment in which the load pressure only has to be limited in one direction.
  • Such tasks can be found, in particular, in forceps movements and in devices in which holding is carried out with limited pressure.
  • the comparison valve arrangement 16 must therefore only be used in such applications. work on a work line and can therefore be carried out more easily.
  • a pressure limitation is only required in the extension direction of the consumer (hydraulic cylinder) 2, so that only the load pressure in the working line 30 must be limited, which connects the working port A with the cylinder space of the consumer 2.
  • the proportional valve 14 has the same structure as that from FIG. 4, so that a repeated description can be dispensed with.
  • the comparison valve 16 is designed as a 2-way proportional valve, which is biased into its neutral position 0 by an adjustable compression spring 32.
  • the end face of the valve spool of the comparison valve 16 removed from the compression spring 32 is connected to the working line 30 via a load pressure line 34, so that this end face is acted upon by the load pressure.
  • the valve slide of the comparison valve 16 can be brought from its blocking position into the flow positions in which an outflow line 36 is connected to the tank connection T.
  • the outflow line 36 branches off to the proportional valve 14 into two control lines 38, 40, which are each guided to an end face of the proportional valve spool.
  • a throttle 42 is arranged in the right control line 40 in FIG. 5.
  • a connecting line 44 leads to the control connection Z of the proportional valve 14. That is, in the neutral position N of the proportional valve 14 shown in FIG. 5, the two end faces of the proportional valve spool are above the control eranschluß Z, the connecting line 44 and the two control lines 38, 40 connected to the tank port T.
  • the left-hand electromagnet of the proportional valve 14 is energized in FIG. 5, so that the proportional valve spool is moved to the positions marked with a, in which the connection from the pump connection P to the work connection A and the connection from the work connection B to the tank connection T can be controlled.
  • the hydraulic cylinder 2 is extended and, for example, a forceps gripping movement is carried out.
  • the pressure at the pump connection P is routed via the control connection Z and the control lines 44, 40 and 38 to the two end faces of the proportional valve spool, so that the control pressure is the same on both sides.
  • the 2-way proportional valve (comparison valve) 16 When the maximum load pressure that can be set by the compression spring 32 is reached, the 2-way proportional valve (comparison valve) 16 is brought into its flow position, so that the outflow line 36 and the control line 38 are connected to the tank connection T. As a result, the left end face of the proportional valve spool in FIG. 5 is relieved towards the tank T, while due to the throttle 42 on the right end face a control pressure corresponding to the pressure at the working port A is still present. As a result, the proportional valve slide is brought into a position in which the hydraulic fluid flow to the consumer 2 is throttled or interrupted, so that the load pressure in the working line 30 drops again below the predetermined maximum value.
  • the comparison valve 16 is not in operative connection with the other working line 46, which is connected to the working connection B, since when the hydraulic cylinder 2 is loosened, that is to say when the hydraulic cylinder 2 is moved back, no increase in load pressure can take place.
  • the comparison valve 16 is designed as an electrically actuated pressure relief valve.
  • the proportional valve 14 is designed as a 3-way proportional valve and is used in a circuit for controlling a double-acting hydraulic cylinder with inlet throttling.
  • the proportional valve 14 is followed by a switching valve via which the cylinder space or the annular space of the hydraulic cylinder can optionally be supplied with hydraulic fluid. This means that switching from, for example, lifting to lowering is carried out by actuating the switching valve, while the proportional valve can remain in its working position.
  • the electromagnet on the right in FIG. 6 is energized, so that the proportional valve slide is brought into the working positions marked with a.
  • the pump connection P is connected to the work connection A and the tank connection T is shut off.
  • the return of the hydraulic fluid from the hydraulic cylinder takes place through its own tank line without return flow restriction, which is not shown in FIG. 6.
  • the two control connections Xi and X2 are also connected to each other in the working positions.
  • Proportional valve 14 is brought into a floating position S, in which the pump connection P is shut off and the working connection A and the control connection X2 are connected to the tank connection.
  • the load pressure of the consumer or another suitable system pressure is tapped via a load pressure line 46 and led to the end faces of the proportional valve spool via two control lines 48, 50.
  • the two control connections X ] _, X2 are also connected to the control line 50.
  • a throttle 52 is also connected in this.
  • a load pressure line 54 branches off from the control line 50 and is led to the inlet connection D of the pressure relief valve.
  • An output port E of the pressure relief valve is connected to the tank T.
  • the end face of the pressure valve valve slide which is remote from the electromagnet, is likewise acted upon by the control pressure prevailing in the load pressure line 54 via a branch line 56.
  • the proportional valve When the consumer is actuated, the proportional valve is brought into the positions marked with a and the switching valve (not shown) is actuated in such a way that the consumer is raised or lowered. As long as the load pressure at the consumer is below the desired maximum value, the same control pressure is present on both ends of the proportional valve spool, so that it remains in its position specified by the force of the electromagnet.
  • the pressure relief valve which is normally in a closed position, is opened by the control pressure acting via the control line 56, so that the pressure in the load pressure line 54 and thus also in the region between the throttle 52 and the right end face of the proportional valve spool is reduced towards the tank T, while the pressure on the left-hand end of FIG.
  • valve housing 2 in which the valve arrangement described above for controlling a hydraulic cylinder with inlet throttling is accommodated.
  • the valve housing 2 is of disk or plate construction, so that several valve disks of this type can be joined together to form a control block.
  • the hydraulic cylinder is connected to two working ports A and B; Furthermore, the valve housing has a tank connection T, a pump connection P and a control connection X.
  • the proportionally adjustable directional control valve 14 from FIG. 6, a switching valve 60 and a check valve 62 are also accommodated in the valve housing 2, the axes of which are parallel to one another in the plate are arranged. In the illustrated embodiment, the proportional valve 14, the switching valve 60 and the check valve 62 are actuated by electromagnets.
  • the proportional valve 14 has a proportional valve slide 64, the two end faces of which are acted upon by a load pressure LS via the control lines or control channels 48 or 50.
  • the control channel 50 is provided with a nozzle bore which forms the throttle 52 in FIG. 6.
  • the electrically operable pressure relief valve 16 is screwed into a connection bore of the valve housing 2, which is arranged at the bottom right in FIG. 7 and via which, when a maximum load pressure in the area between the nozzle bore (throttle 52) and the one in FIG. A connection to a tank line 55 is opened on the end face of the proportional valve spool 64, so that the right end face of the proportional valve spool 64 is relieved and the volume flow can be throttled.
  • the invention thus makes it possible in a simple manner to limit the maximum load pressure individually for each consumer and to connect the individual proportional valves in an LS or a LUDV system.
  • the valve arrangements according to the invention can also be used in mixed systems with load signaling valves and non-load-adapted valves, so that an inexpensive assembly of the valve assemblies in the modular system is made possible.
  • the circuit according to the invention does not result in unnecessary energy losses in the pressure limitation, since hydraulic fluid not conveyed unnecessarily by the pump must be drained from the refueling via a secondary valve.
  • the tank pressure is usually applied to the end faces of the proportional valve spool.
  • the constructive freedom is increased, especially when designing series and modular systems.
  • a hydraulic circuit for controlling a consumer and a method for controlling such a circuit, in which a valve slide of a load-adjusted proportional valve is assigned a comparison valve, via which a pressure difference can be applied to the valve slide of the proportional valve when a predetermined maximum load pressure is reached, so that this is moved to a position in which the load pressure is limited to the predetermined maximum value.

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

Abstract

La présente invention porte sur un circuit hydraulique pour exciter un organe consommateur et sur un procédé d'excitation d'un tel circuit. Une soupape de référence (16) est associée au tiroir d'une soupape à action proportionelle (14) adaptée à la charge. Lorsque la pression sous charge a atteint son maximum prescrit sur le tiroir de la soupape à action proportionnelle, on peut appliquer une pression différentielle à la soupape de référence en poussant cette dernière dans une position où la pression sous charge est limitée à une valeur maximale préétablie.
PCT/DE1998/003050 1997-11-10 1998-10-19 Circuit hydraulique WO1999024720A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE1997149639 DE19749639A1 (de) 1997-11-10 1997-11-10 Hydraulische Schaltung
DE19749639.3 1997-11-10

Publications (1)

Publication Number Publication Date
WO1999024720A1 true WO1999024720A1 (fr) 1999-05-20

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DE10041168A1 (de) * 2000-08-21 2002-03-07 Mannesmann Rexroth Ag Ventileinrichtung
DE10107139B4 (de) * 2001-02-15 2004-09-23 Gebr. Pöttinger GmbH Pflug
DE102006014446A1 (de) 2006-03-29 2007-10-04 Schaeffler Kg Stromregelventil
DE102015203404A1 (de) * 2015-02-26 2016-09-01 Robert Bosch Gmbh Hydraulische Steueranordnung zur Druckmittelversorgung eines hydraulischen Aktuators

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