EP1092095B1 - Hydraulic circuit - Google Patents

Hydraulic circuit Download PDF

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Publication number
EP1092095B1
EP1092095B1 EP99936360A EP99936360A EP1092095B1 EP 1092095 B1 EP1092095 B1 EP 1092095B1 EP 99936360 A EP99936360 A EP 99936360A EP 99936360 A EP99936360 A EP 99936360A EP 1092095 B1 EP1092095 B1 EP 1092095B1
Authority
EP
European Patent Office
Prior art keywords
pressure
consumer
bypass channel
valve
load
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
EP99936360A
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German (de)
French (fr)
Other versions
EP1092095A1 (en
EP1092095B2 (en
Inventor
Thomas Weickert
Erich Adlon
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Bosch Rexroth AG
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Bosch Rexroth AG
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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
    • F15B11/003—Systems with load-holding 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
    • 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
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20546—Type of pump variable capacity
    • F15B2211/20553—Type of pump variable capacity with pilot circuit, e.g. for controlling a swash plate
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/25—Pressure control functions
    • F15B2211/253—Pressure margin control, e.g. pump pressure in relation to load pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—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
    • F15B2211/3054—In combination with a pressure compensating valve the pressure compensating valve is arranged between directional control valve and output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3144—Directional control characterised by the positions of the valve element the positions being continuously variable, e.g. as realised by proportional valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/329—Directional control characterised by the type of actuation actuated by fluid pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50545—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using braking valves to maintain a back pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/605—Load sensing circuits
    • F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
    • F15B2211/6054—Load sensing circuits having valve means between output member and the load sensing circuit using shuttle valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/78—Control of multiple output members
    • 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
    • F15B2211/80—Other types of control related to particular problems or conditions
    • F15B2211/88—Control measures for saving energy

Definitions

  • the invention relates to a hydraulic circuit to control at least one lower and one load higher consumer according to the preamble of the claim 1.
  • Such circuits also load-sensing circuits are called) among other things for the control of mobile Working machines, for example used by excavators. Hydraulically operated are operated via the central circuit Aggregates of the working machine, for example a slewing gear, the traction drive, a spoon, a stick or an am Excavator boom mounted clamping device controlled.
  • Such a load-sensing circuit is, for example known from EP 0 566 449 AS.
  • This circuit has a variable displacement pump that can be controlled that it produces a pressure at its outlet which is around one certain difference above the highest load pressure the hydraulic consumer lies.
  • a load-sensing controller is provided, which depends on the pump pressure in the direction of reducing the stroke volume and the highest pressure on consumers and one Compression spring in the direction of increasing the stroke volume is acted upon. The one that comes with the variable pump Difference between the pump pressure and the highest load pressure corresponds to the force of the aforementioned Spring.
  • Each of the consumers has an adjustable orifice plate assigned with a downstream pressure compensator, via which kept the pressure drop at the orifice constant is, so that the amount of hydraulic fluid flowing to the respective consumer from the opening cross section of the orifice plate and not the load pressure of the consumer or the pump pressure depends.
  • the variable pump with maximum volume and the hydraulic fluid flow still not enough to meet the given Maintain pressure drop across the orifice plates the pressure balances of all actuated hydraulic consumers adjusted in the closing direction so that all hydraulic fluid flows to the individual. Consumers around the same proportion can be reduced. That is, with a downstream Pressure compensators are related to the volume flows Consumers always in the ratio of the opening cross-sections the orifice plates. Because of this load-independent flow distribution (LUDV) move all controlled Consumers with a percentage around the same value reduced speed.
  • LUDV load-independent flow distribution
  • variable displacement pump mentioned at the beginning is common with a pressure control and with a power control equipped with the maximum possible pump pressure or the maximum power output by the variable pump (Excavator output) are adjustable. This printing and Power regulations are superimposed on the load-sensing regulation.
  • the WO95 / 32364 of the applicant discloses a control arrangement, about only when a limit load pressure is exceeded the load pressure of the lower hydraulic load to the load sensing controller of the variable pump is reported.
  • This limit load pressure is chosen so that ensures the supply of the other hydraulic consumer is.
  • This is the subject of WO95 / 32364 achieved by the spring chamber of the pressure compensator of the lower load Consumer via a pressure relief valve arrangement is connectable to the tank. If exceeded a limit load pressure opens the pressure relief valve the connection to the tank so that the spring chamber of the Pressure balance of the lower load consumer relieved and the control piston is brought into its open position, in which the load pressure of this consumer in the load pressure reporting line is reported.
  • the invention is based on the object to create a control arrangement by which at minimal device-related effort a sufficient Supply of all consumers is guaranteed.
  • the measure of providing a bypass channel bypassing the pressure compensator downstream of the orifice plate is, it is not necessary to limit the System pressure to regulate the pressure compensator or hydraulic fluid to drain into the tank.
  • the resulting system pressure can be by appropriate choice of the bypass cross section be predetermined. Because of the reduced System pressure can be the lower load with a larger amount of hydraulic fluid are supplied for example in a speed increase Cantilever or similar can be implemented.
  • a particularly simple circuit receives one, if the orifice upstream of the pressure compensator is formed by a proportional directional control valve, wherein the bypass channel depending on the valve spool position of the proportional directional control valve is controllable.
  • the individual pressure compensator acts on the bypass channel only in the fine control area in which comparatively low hydraulic fluid volume flows Flow through the pressure compensator.
  • the structure can be further simplified if the Bypass channel in the valve spool of the proportional directional control valve is formed and by a control edge of the valve slide bore on is controllable.
  • two working connections one via the proportional valve Controlled consumer.
  • the bypass channel is only one of the working connections is assigned so that, for example, in the bypass flows through the lifting function.
  • both work connections Assign bypass channels it is also possible to have both work connections Assign bypass channels.
  • bypass channel only after a certain stroke of the proportional valve is turned on, so that at the beginning no bypass flow occurs in the control.
  • the valve spool of the proportional directional control valve is preferably with a central speed section and two outer directional parts, each are assigned to a connection of the consumer.
  • the bypass channel extends within the valve spool from the speed part to the direction part, so that the pressure compensator is bypassed.
  • the pressure loss in the bypass channel can be minimized, if this has oblique and radial holes in the outer circumference of the valve slide opens.
  • Fig. 1 is part of a circuit diagram for a hydraulic circuit for controlling a mobile working device, shown for example an excavator.
  • This excavator has several consumers, such as a boom, a spoon, a stick, a chassis drive and a slewing gear driven by a Variable pump 2 can be supplied with hydraulic fluid.
  • a Variable pump 2 can be supplied with hydraulic fluid.
  • a setting of the stroke volume of the variable pump takes place via a load-sensing controller 8, which is dependent from the pump pressure on the one hand and from the highest load pressure to consumers 4, 6 and the force of a compression spring 10 on the other hand, the stroke volume of the variable displacement pump regulates.
  • the hydraulic fluid delivered by the variable displacement pump is via a pump line 12 with branch lines 12a, 12b to the two consumers 4 and 6, respectively.
  • each branch of the pump line 12 (12a, 12b) is an adjustable measuring aperture 14a, 14b is formed. like in The metering orifices are explained in more detail below 14a, 14b as speed parts of a proportional valve executed.
  • each orifice plate 14a, 14b Downstream of each orifice plate 14a, 14b, respectively a pressure compensator 16a, 16b switched.
  • the control piston of this 2-way pressure compensator is in the opening direction over a Control line 18 with the pressure downstream of the orifice 14a, 14b and in the closing direction via a load control line 20 applied with the highest load pressure that of a load pressure reporting line 22 is tapped. about this is the highest load pressure also for the load sensing controller 8 led.
  • the control of the adjustable measuring orifices 14a, 14b takes place via manually operable control devices 30a, 30b, which is in operative connection with the measuring orifices 14a and 14b stand.
  • the bypass channel 32 branches downstream the orifice 14a and ends in the working line 24a to the consumer 6.
  • the bypass channel 32 is one Suitable control device 34 is provided, the bypass channel 32 blocked in the basic position and dependent controls from the opening cross section of the orifice 14a.
  • the number 34 provided switching device can be any Be a device that is suitable for the bypass channel 32nd shut off and depending on the control of the Open orifice 14a.
  • FIG. 2 is the circuit diagram of a valve disk 35 a valve block for realizing that shown in FIG. 1 Circuit shown.
  • the valve disc 35 contains the pressure compensator 16a, a proportional valve 36 the speed part of which the measuring aperture 14a is formed is and the bypass channel 32, as well as the others, in the following connecting lines of the hydraulic elements described in more detail.
  • the proportional valve 36 next to the Orifice plate 14a also a directional part for control the consumer A, B, and the control of the bypass channel 32 integrated.
  • the proportional valve 36 has a pump connection P, two working ports A, B, with the cylinder chambers a differential cylinder b or with a hydraulic motor are connected. Furthermore, there is an output port P1 to the pressure compensator 16a, a bypass connection U, two input connections R, S of the directional part and a tank connection T formed on the proportional valve 36.
  • the two end faces of the valve spool 38 of the Proportional valve 36 are formed by two compression springs 41a, 41b biased into its basic position. In this basic position ports P, A, B, U and S are closed, while ports P1 and R are connected to the tank are.
  • valve spool 38 The end faces of the valve spool 38 are acted upon by control pressures P ST , so that it can be moved out of its spring-loaded basic position.
  • the output port P1 is through the pump line 12a connected to the input port Q of the pressure compensator 16a.
  • branches of the Pump line 12a from the control line 18 via which the Pressure downstream of the orifice 14a (proportional valve 36) to the left end face of the pressure compensator 16a in FIG. 2 is reported.
  • the load pressure of the consumer 6 is over the load signal line 20 with the load pressure signal line 22 connected and led to the spring side of the pressure compensator 16a.
  • the output connection C of the pressure compensator 16a is via lines 40, 42 with the input connections R and S of the Directionally connected. Located in lines 40, 42 there are two check valves 56a, 56b that provide a backflow of the hydraulic fluid from the directional part to the pressure compensator 16a prevent.
  • the tank connection T is connected via a tank line 44 connected to the tank.
  • the pressure compensator 16a when activated of the proportional valve 36 the pressure drop across measuring orifice 14a kept constant regardless of load pressure, so that the volume flow to the consumer 6 proportional to the opening cross section of the orifice 14a.
  • FIG. 3 shows a section through a directional valve segment, through which the circuit shown in Fig. 2 is realized is.
  • the directional valve segment has a valve plate 52, in the mounting holes for the valve slide 38, the pressure compensator 16a, two pressure relief valves 54a, 54b and the two check or load holding valves 56a, 56b are trained.
  • the valve plate 52 In the valve plate 52 are further the two working connections A, B, two control connections 58a, 58b for controlling the proportional valve 36, a pump connection P, at least one connection for the Load pressure reporting line 22 and a tank connection are provided.
  • the valve spool 38 has in its central area a control collar 60, which in cooperation with a web 62 of the valve bore forms the orifice 14a.
  • a control collar 60 which in cooperation with a web 62 of the valve bore forms the orifice 14a.
  • the valve spool 38 by the two compression springs 41a, 41b in its basic position biased in which no flow through the orifice 14a takes place.
  • the proportional valve 36 is activated by applying a control pressure to the two control connections 58a and 58b, which are connected to the Spring chamber 64a or 64b of the proportional valve 36 connected are.
  • a control pressure to the two control connections 58a and 58b, which are connected to the Spring chamber 64a or 64b of the proportional valve 36 connected are.
  • the control line between the control connections 58a, 58b and the spring chambers 64a and 64b formed a nozzle with a check valve, by damping the valve spool movement is possible.
  • the control collar 60 is in the area of its end faces provided with a plurality of control notches 64 and 66, via the pressure medium from a with the pump connection P connected annulus 68 led to the input port Q. can be, so that the lower end face in Fig. 3 of Control piston 72 of the pressure compensator 16a with the pressure downstream the measuring orifice can be acted upon.
  • the input port Q of the pressure compensator 16a is as Axial connection designed so that the fluid pressure also on the lower end face 70 of the control piston 72 acts.
  • the Output connection C is designed as a radial connection and opens into lines 40 and 42. In these lines 40, 42, the load holding valves 56a, 56b are arranged which a backflow from the valve spool 38 to the pressure compensator Prevent 16a and a flow in reverse Enable direction.
  • each working connection A, B is a directional part assigned, through which a work port A or B with a Line 40, 42 or can be connected to the tank T.
  • the directional part formed on the right in FIG port B has three axially spaced Tax groups 74, 76 and 78.
  • the tax groups 76 and 78 are each provided with control notches 80 and 82, which are to radially arranged between these control collars 76, 78 open the recessed section.
  • Fig. 4 shows a detailed representation of the valve spool 38 in the central region of this axial bore 92.
  • a check valve is in the axial bore 92 provided, the valve body 96 via a compression spring 97 is biased against a valve seat 98.
  • a radial bore star opens downstream of the valve body 96 100 and a helical bore star 102.
  • the Radial bore star 100 is through a web 104 of the receiving bore 103 of the valve spool 38 blocked.
  • the Oblique bore star 102 opens into the radially recessed one Section between tax bands 84 and 86.
  • the valve body 96 biased against the valve seat 98 prevents hydraulic fluid from port A into the Axial bore 92 can flow. A flow in The opposite direction is practically not prevented since the Compression spring 97 is weak.
  • the geometry of the radial bore star 100 and Inclined bore star 102 is chosen such that at one Displacement of the valve slide 38 to the left these stars 100, 102 the connection from the work connection A can be opened to the tank connection T.
  • valve spool 38 is shown 3 moved to the right so that the control notches 64 in cooperation with the web 62 the connection from the pump connection P to the input connection Q Control the pressure compensator.
  • the end face 105 of the control piston lying at the top in FIG. 3 72 is of the force of a control spring 106 and acted upon by the load pressure, which via a control edge and an angular bore 108 in the control piston 72 from a circumferential groove 110 is tapped.
  • the control piston 72 is deflected upwards and the output connection C opened up until there is a balance of forces above the control piston 72.
  • the load holding valve 56a is opened and the hydraulic fluid via the Line 40 and the control collar 86 with the control notches 88 led to work port A.
  • the tax union 76 assigned to the working connection B and the Control notches 82 the connection between the work connection B and the tank port T turned open, so that Flow hydraulic fluid back into the tank from the consumer can.
  • the inclined bores are in this fine control range 90 of the bypass channel 32 not yet through the control edge 107 opened.
  • valve spool If the valve spool is moved further 38, the control edge 107 opens the bypass channel 82, see above that the hydraulic fluid or at least a partial volume flow is led to work port A. The system pressure decreases, so that the load-lower consumer 6 with higher Speed can be operated.
  • bypass channel is 32 only assigned to work port A, which is required for the lifting function of the consumer is.
  • other connection can also work B another bypass channel can be assigned to the then an identical structure to the work connection described above would have.
  • FIG. 5 shows the pressure and volume flow ratios of the above-described processes as a function of time. It is assumed that a higher load consumer, for example a spoon, is first moved to a stop. The corresponding pressure curve is shown in Fig. 5 with solid lines. Accordingly, the load pressure at this consumer rises very quickly and reaches a maximum at time t1, which is predetermined by the pump power p sys .
  • a lower load consumer for example a boom
  • the bypass channel 32 is opened in the manner described above, so that the hydraulic fluid flow Q increases to the load-lower consumer (dashed line). Due to this increase in the hydraulic fluid volume flow to the load-lower consumer, the pressure drops from the system pressure p SYS to a lower level p *.
  • the pressure level p * can be set by a suitable choice of the bypass channel diameter, so that the pressure drops, for example, from a pressure of 240 bar to a pressure p * of 200 bar.
  • bypass channel 32 into the proportional valve 36 is integrated.
  • bypass channel via external Circuits is realized.
  • At least a LUDV circuit for control is disclosed a lower and a higher consumer, with each consumer an orifice and downstream pressure compensator to keep the Pressure drop across the orifice are assigned.
  • the Pressure balance of the lower load is a controllable Bypass channel assigned via which the pressure compensator this consumer is bypassable.

Abstract

The invention relates to a load-independent flow regulation circuit for controlling at least one low load consumer (6) and one high load consumer (4), wherein each consumer (4, 6) is allocated a metering orifice (14a, 14b) and a downstream pressure regulator (16a, 16b) to constantly maintain pressure drop above the metering orifice (16a). A controllable bypass duct (32) is allocated to the pressure regulator of the low load consumer through which the pressure regulator of said consumer may be circumvented.

Description

Die Erfindung betrifft eine hydraulische Schaltung zur Ansteuerung zumindest eines lastniedrigeren und eines lasthöheren Verbrauchers gemäß dem Oberbegriff des Patentanspruchs 1.The invention relates to a hydraulic circuit to control at least one lower and one load higher consumer according to the preamble of the claim 1.

Derartige Schaltungen (auch Load-Sensing-Schaltungen genannt) werden unter anderem zur Ansteuerung von mobilen Arbeitsmaschinen, beispielsweise von Baggern eingesetzt. Über die zentrale Schaltung werden hydraulisch betätigte Aggregate der Arbeitsmaschine, beispielsweise ein Drehwerk, der Fahrantrieb, ein Löffel, ein Stiel oder eine am Baggerausleger montierte Klemmeinrichtung angesteuert.Such circuits (also load-sensing circuits are called) among other things for the control of mobile Working machines, for example used by excavators. Hydraulically operated are operated via the central circuit Aggregates of the working machine, for example a slewing gear, the traction drive, a spoon, a stick or an am Excavator boom mounted clamping device controlled.

Eine derartige Load-Sensing-Schaltung ist beispielsweise aus der EP 0 566 449 AS bekannt. Diese Schaltung hat eine Verstellpumpe, die derart geregelt werden kann, daß sie an ihrem Ausgang einen Druck erzeugt, der um einen bestimmten Differenzbetrag über dem höchsten Lastdruck der hydraulischen Verbraucher liegt. Zur Regelung ist ein Load-Sensing-Regler vorgesehen, der vom Pumpendruck in Richtung der Verringerung des Hubvolumens und vom höchsten Druck an den Verbrauchern sowie von einer Druckfeder in Richtung der Vergrößerung des Hubvolumens beaufschlagbar ist. Die sich bei der Verstellpumpe einstellende Differenz zwischen dem Pumpendruck und dem höchsten Lastruck entspricht der Kraft der vorgenannten Druckfeder.Such a load-sensing circuit is, for example known from EP 0 566 449 AS. This circuit has a variable displacement pump that can be controlled that it produces a pressure at its outlet which is around one certain difference above the highest load pressure the hydraulic consumer lies. For regulation a load-sensing controller is provided, which depends on the pump pressure in the direction of reducing the stroke volume and the highest pressure on consumers and one Compression spring in the direction of increasing the stroke volume is acted upon. The one that comes with the variable pump Difference between the pump pressure and the highest load pressure corresponds to the force of the aforementioned Spring.

Jedem der Verbraucher ist eine verstellbare Meßblende mit einer nachgeschalteten Druckwaage zugeordnet, über die der Druckabfall an der Meßblende konstant gehalten wird, so daß die zum jeweiligen Verbraucher fließende Hydraulikfluidmenge vom Öffnungsquerschnitt der Meßblende und nicht vom Lastdruck des Verbrauchers oder vom Pumpendruck abhängt. In demjenigen Fall, in dem die Verstellpumpe mit maximalem Volumen fördert und der Hydraulikfluidstrom trotzdem nicht ausreicht, um den vorgegebenen Druckabfall über den Meßblenden aufrechtzuerhalten, werden die Druckwaagen aller betätigten hydraulischen Verbraucher in Schließrichtung verstellt, so daß alle Hydraulikfluidströme zu den einzelnen. Verbrauchern um den gleichen Anteil verringert werden. Das heißt, bei nachgeschalteter Druckwaage stehen die Volumenströme zu den Verbrauchern immer im Verhältnis der Öffnungsquerschnitte der Meßblenden. Aufgrund dieser lastunabhängigen Durchflußverteilung (LUDV) bewegen sich alle angesteuerten Verbraucher mit einer prozentual um den gleichen wert verringerten Geschwindigkeit.Each of the consumers has an adjustable orifice plate assigned with a downstream pressure compensator, via which kept the pressure drop at the orifice constant is, so that the amount of hydraulic fluid flowing to the respective consumer from the opening cross section of the orifice plate and not the load pressure of the consumer or the pump pressure depends. In the case where the variable pump with maximum volume and the hydraulic fluid flow still not enough to meet the given Maintain pressure drop across the orifice plates the pressure balances of all actuated hydraulic consumers adjusted in the closing direction so that all hydraulic fluid flows to the individual. Consumers around the same proportion can be reduced. That is, with a downstream Pressure compensators are related to the volume flows Consumers always in the ratio of the opening cross-sections the orifice plates. Because of this load-independent flow distribution (LUDV) move all controlled Consumers with a percentage around the same value reduced speed.

Die eingangs genannte Verstellpumpe ist üblicherweise mit einer Druckregelung und mit einer Leistungsregelung ausgestattet, über die der maximal mögliche Pumpendruck bzw. die maximale von der Verstellpumpe abgebbare Leistung (Baggerleistung) einstellbar sind. Diese Druck- und Leistungsregelungen sind der Load-Sensing-Regelung überlagert.The variable displacement pump mentioned at the beginning is common with a pressure control and with a power control equipped with the maximum possible pump pressure or the maximum power output by the variable pump (Excavator output) are adjustable. This printing and Power regulations are superimposed on the load-sensing regulation.

Mit einer Steueranordnung der vorstehend geschilderten Art kann es dann zu Problemen kommen, wenn ein hydraulischer Verbraucher gegen einen praktisch unendlichen Widerstand arbeitet. Dies kann beispielsweise dann der Fall sein, wenn der hydraulische Verbraucher ein Löffel ist, der auf Anschlag gefahren wird. Bei einem Fahren auf Anschlag baut sich an dem entsprechenden hydraulischen Verbraucher ein Druck auf, der etwa dem durch die Druckregelung vorgegebenen Maximaldruck (Baggerleistung) entspricht. Wird nun ein weiterer hydraulischer Verbraucher, beispielsweise ein Fahrantrieb oder ein Ausleger angesteuert, kann dieser nur mit einer geringeren Geschwindigkeit bewegt werden, da aufgrund des hohen Druckes am erstgenannten Verbraucher (Löffel) bereits bei geringen Hydraulikfluidströmen zum anderen hydraulischen Verbraucher (Fahrantrieb) die Leistungsregelung der Verstelipumpe anspricht.With a control arrangement of the above Kind of problems can arise if a hydraulic Consumers against a virtually infinite Resistance works. This can be the case, for example Case if the hydraulic consumer is a spoon is driven to the stop. When driving on Stop builds on the corresponding hydraulic Consumers put pressure on that through pressure control corresponds to the specified maximum pressure (excavator output). Now becomes another hydraulic consumer, for example a drive or a boom controlled, can only do this at a lower speed be moved because of the high pressure on first-mentioned consumer (spoon) already at low Hydraulic fluid flows to the other hydraulic consumer (Traction drive) the output control of the adjustment pump responds.

Um diesen Nachteil auszuräumen, wird in der WO95/32364 der Anmelderin eine Steueranordnung offenbart, über die bei Überschreiten eines Grenzlastdruckes lediglich der Lastdruck des lastniedrigeren hydraulischen Verbrauchers an den Load-Sensing-Regler der Verstellpumpe gemeldet wird. Dieser Grenzlastdruck ist so gewählt, daß die Versorgung des anderen hydraulischen Verbrauchers gewährleistet ist. Beim Gegenstand der WO95/32364 wird dies erreicht, indem der Federraum der Druckwaage des lastniedrigeren Verbrauchers über eine Druckbegrenzungsventilanordnung mit dem Tank verbindbar ist. Bei Überschreiten eines Grenzlastdruckes öffnet das Druckbegrenzungsventil die Verbindung zum Tank, so daß der Federraum der Druckwaage des lastniedrigeren Verbrauchers entlastet und der Regelkolben in seine Öffnungsstellung gebracht wird, in der der Lastdruck dieses Verbrauchers in die Lastdruckmeldeleitung gemeldet wird.To overcome this disadvantage, the WO95 / 32364 of the applicant discloses a control arrangement, about only when a limit load pressure is exceeded the load pressure of the lower hydraulic load to the load sensing controller of the variable pump is reported. This limit load pressure is chosen so that ensures the supply of the other hydraulic consumer is. This is the subject of WO95 / 32364 achieved by the spring chamber of the pressure compensator of the lower load Consumer via a pressure relief valve arrangement is connectable to the tank. If exceeded a limit load pressure opens the pressure relief valve the connection to the tank so that the spring chamber of the Pressure balance of the lower load consumer relieved and the control piston is brought into its open position, in which the load pressure of this consumer in the load pressure reporting line is reported.

Nachteilig bei dieser Steueranordnung ist, daß ein Teilvolumenstrom zum Tank hin abgeführt wird und somit nicht für die Verbraucheransteuerung verwendet werden kann. Der Wirkungsgrad dieser Steuerung ist daher vergleichsweise gering. Ein weiterer Nachteil besteht darin, daß durch die Rückführung des Hydraulikfluids hin zum Tank Wärme im System erzeugt und somit Pumpenleistung vernichtet wird. The disadvantage of this control arrangement is that a Partial flow is discharged to the tank and thus not be used for consumer control can. The efficiency of this control is therefore comparative low. Another disadvantage is that by returning the hydraulic fluid to Tank generates heat in the system and thus pump performance is destroyed.

Demgegenüber liegt der Erfindung die Aufgabe zugrunde, eine Steueranordnung zu schaffen, durch die bei minimalem vorrichtungstechnischen Aufwand eine hinreichende Versorgung sämtlicher Verbraucher gewährleistet ist.In contrast, the invention is based on the object to create a control arrangement by which at minimal device-related effort a sufficient Supply of all consumers is guaranteed.

Diese Aufgabe wird durch eine hydraulische Schaltung mit den Merkmalen des Patentanspruchs 1 gelöst.This task is accomplished through a hydraulic circuit solved with the features of claim 1.

Durch die Maßnahme, einen Bypasskanal vorzusehen, über den die der Meßblende nachgeschaltete Druckwaage umgehbar ist, ist es nicht erforderlich, zur Begrenzung des Systemdruckes die Druckwaage abzuregeln oder Hydraulikfluid in den Tank abzuführen. Der sich einstellende Systemdruck kann durch entsprechende Wahl des Bypassquerschnittes vorbestimmt werden. Aufgrund des reduzierten Systemdruckes kann der lastniedrigere Verbraucher mit einer größeren Hydraulikfluidmenge versorgt werden, die beispielsweise in eine Geschwindigkeitserhöhung eines Auslegers oder ähnliches umgesetzt werden kann.The measure of providing a bypass channel bypassing the pressure compensator downstream of the orifice plate is, it is not necessary to limit the System pressure to regulate the pressure compensator or hydraulic fluid to drain into the tank. The resulting system pressure can be by appropriate choice of the bypass cross section be predetermined. Because of the reduced System pressure can be the lower load with a larger amount of hydraulic fluid are supplied for example in a speed increase Cantilever or similar can be implemented.

Eine besonders einfach aufgebaute Schaltung erhält man, wenn die der Druckwaage vorgeschaltet Meßblende durch ein Proportionalwegeventil ausgebildet wird, wobei der Bypasskanal in Abhängigkeit von der Ventilschieberstellung des Proportionalwegeventils aufsteuerbar ist. Durch die von der Ansteuerung des Proportionalventils abhängige Aufsteuerung des Bypasskanals wirkt die Individualdruckwaage lediglich im Feinsteuerbereich, in dem vergleichsweise geringe Hydraulikfluidvolumenströme die Druckwaage durchströmen.A particularly simple circuit receives one, if the orifice upstream of the pressure compensator is formed by a proportional directional control valve, wherein the bypass channel depending on the valve spool position of the proportional directional control valve is controllable. By the dependent on the control of the proportional valve The individual pressure compensator acts on the bypass channel only in the fine control area in which comparatively low hydraulic fluid volume flows Flow through the pressure compensator.

Der Aufbau läßt sich weiter vereinfachen, wenn der Bypasskanal im Ventilschieber des Proportionalwegeventils ausgebildet ist und durch eine Steuerkante der Ventilschieberbohrung auf steuerbar ist. The structure can be further simplified if the Bypass channel in the valve spool of the proportional directional control valve is formed and by a control edge of the valve slide bore on is controllable.

Um die Rückströmung vom Verbraucher durch den Bypasskanal zu verhindern, wird in diesem eine Rückschlagventilanordung vorgesehen.The return flow from the consumer through the bypass channel to prevent this is a check valve arrangement intended.

Bei einer bevorzugten Variante der Erfindung werden über das Proportionalventil zwei Arbeitsanschlüsse eines Verbrauchers angesteuert. In einigen Fällen, beispielsweise bei doppeltwirkenden Hydraulikzylindern, ist es ausreichend, wenn der Bypasskanal lediglich einem der Arbeitsanschlüsse zugeordnet ist, so daß beispielsweise in der Hebenfunktion eine Durchströmung des Bypasses erfolgt. Selbstverständlich ist es auch möglich, beiden Arbeitsanschlüssen Bypasskanäle zuzuordnen.In a preferred variant of the invention two working connections one via the proportional valve Controlled consumer. In some cases, for example with double-acting hydraulic cylinders, it is sufficient if the bypass channel is only one of the working connections is assigned so that, for example, in the bypass flows through the lifting function. Of course it is also possible to have both work connections Assign bypass channels.

Wie vorstehend bereits erwähnt, kann es vorteilhaft sein, wenn der Bypasskanal erst nach einem bestimmten Hub des Proportionalventils aufgesteuert wird, so daß zu Beginn der Regelung keine Bypassströmung entsteht.As mentioned above, it can be beneficial be if the bypass channel only after a certain stroke of the proportional valve is turned on, so that at the beginning no bypass flow occurs in the control.

Der Ventilschieber des Proportionalwegeventils wird vorzugsweise mit einem mittigen Geschwindigkeitsteil und zwei außenliegenden Richtungsteilen ausgebildet, die jeweils einem Anschluß des Verbrauchers zugeordnet sind. Der Bypasskanal erstreckt sich dabei innerhalb des Ventilschiebers vom Geschwindkeitsteil hin zum Richtungsteil, so daß die Druckwaage umgangen wird.The valve spool of the proportional directional control valve is preferably with a central speed section and two outer directional parts, each are assigned to a connection of the consumer. The bypass channel extends within the valve spool from the speed part to the direction part, so that the pressure compensator is bypassed.

Der Druckverlust im Bypasskanal läßt sich minimieren, wenn dieser mit Schräg- und Radialbohrungen im Außenumfang des Ventilschiebers mündet.The pressure loss in the bypass channel can be minimized, if this has oblique and radial holes in the outer circumference of the valve slide opens.

Sonstige vorteilhafte Weiterbildungen der Erfindung sind Gegenstand der weiteren Unteransprüche. Other advantageous developments of the invention are the subject of further subclaims.

Im folgenden werden bevorzugte Ausführungsbeispiele der Erfindung anhand schematischer Zeichnungen näher erläutert. Es zeigen:

  • Fig. 1 ein Schaltschema einer erfindungsgemäßen Schaltung mit Bypasskanal;
  • Fig. 2 eine Ventilscheibe eines Ventilblocks für eine Schaltung gemäß Fig. 1;
  • Fig. 3 einen Schnitt durch ein Ventilsegment für eine Schaltung gemäß Fig. 1;
  • Fig. 4 eine Detaildarstellung des Ventilsegments aus Fig. 3 und
  • Fig. 5 ein Diagramm zur Verdeutlichung des Systemdruckaufbaus bei der Ansteuerung eines lasthöheren und eines lastniedrigeren Verbrauchers.
    • Preferred exemplary embodiments of the invention are explained in more detail below with the aid of schematic drawings. Show it:
  • 1 shows a circuit diagram of a circuit according to the invention with a bypass channel;
  • FIG. 2 shows a valve disk of a valve block for a circuit according to FIG. 1;
  • 3 shows a section through a valve segment for a circuit according to FIG. 1;
  • FIG. 4 shows a detailed illustration of the valve segment from FIGS. 3 and
  • Fig. 5 is a diagram to illustrate the system pressure build-up when driving a load higher and a load lower consumer.

    • In Fig. 1 ist ein Teil eines Schaltschemas für eine hydraulische Schaltung zur Ansteuerung eines mobilen Arbeitsgerätes, beispielsweise eines Baggers dargestellt. Dieser Bagger hat mehrere Verbraucher, wie beispielsweise einen Ausleger, einen Löffel, einen Stiel, einen Fahrwerksantrieb und einen Drehwerksantrieb, die von einer Verstellpumpe 2 mit Hydraulikfluid versorgt werden. Bei dem in Fig. 1 dargestellten Ausführungsbeispiel sind schematisch ein Zylinder 4 zur Betätigung eines Löffels und ein Zylinder 6 zur Betätigung des Baggerauslegers als Verbraucher dargestellt.In Fig. 1 is part of a circuit diagram for a hydraulic circuit for controlling a mobile working device, shown for example an excavator. This excavator has several consumers, such as a boom, a spoon, a stick, a chassis drive and a slewing gear driven by a Variable pump 2 can be supplied with hydraulic fluid. at are the embodiment shown in Fig. 1 schematically a cylinder 4 for actuating a spoon and a cylinder 6 for actuating the excavator boom as Shown to consumers.

    Eine Einstellung des Hubvolumens der Verstellpumpe erfolgt über einen Load-Sensing-Regler 8, der in Abhängigkeit vom Pumpendruck einerseits und vom höchsten Lastdruck an den Verbrauchern 4, 6 und der Kraft einer Druckfeder 10 andererseits das Hubvolumen der Verstellpumpe regelt. Das von der Verstellpumpe geförderte Hydraulikfluid wird über eine Pumpenleitung 12 mit Zweigleitungen 12a, 12b zu den beiden Verbrauchern 4 bzw. 6 geführt.A setting of the stroke volume of the variable pump takes place via a load-sensing controller 8, which is dependent from the pump pressure on the one hand and from the highest load pressure to consumers 4, 6 and the force of a compression spring 10 on the other hand, the stroke volume of the variable displacement pump regulates. The hydraulic fluid delivered by the variable displacement pump is via a pump line 12 with branch lines 12a, 12b to the two consumers 4 and 6, respectively.

    In jedem Zweig der Pumpenleitung 12 (12a, 12b) ist eine einstellbare Meßblende 14a, 14b ausgebildet. wie im folgenden noch näher erklärt wird, sind diese Meßblenden 14a, 14b als Geschwindigkeitsteile eines Proportionalventils ausgeführt.In each branch of the pump line 12 (12a, 12b) is an adjustable measuring aperture 14a, 14b is formed. like in The metering orifices are explained in more detail below 14a, 14b as speed parts of a proportional valve executed.

    Stromabwärts jeder Meßblende 14a, 14b, ist jeweils eine Druckwaage 16a, 16b geschaltet. Der Regelkolben dieser 2-Wege-Druckwaagen ist in Öffnungsrichtung über eine Steuerleitung 18 mit dem Druck stromabwärts der Meßblende 14a, 14b und in Schließrichtung über eine Laststeuerleitung 20 mit dem höchsten Lastdruck beaufschlagt, der von einer Lastdruckmeldeleitung 22 abgegriffen wird. Über diese ist der höchste Lastdruck auch zum Load-Sensing-Regler 8 geführt.Downstream of each orifice plate 14a, 14b, respectively a pressure compensator 16a, 16b switched. The control piston of this 2-way pressure compensator is in the opening direction over a Control line 18 with the pressure downstream of the orifice 14a, 14b and in the closing direction via a load control line 20 applied with the highest load pressure that of a load pressure reporting line 22 is tapped. about this is the highest load pressure also for the load sensing controller 8 led.

    Vom Ausgangsanschluß der Druckwaage 16a, 16b führt eine Arbeitsleitung 24a, 24b zu den jeweiligen Verbrauchern 4 bzw. 6. Der Lastdruck der Verbraucher 4, 6 wird über Zweigleitungen 26a, 26b abgegriffen und zu einem Wechselventil 28 geführt, an dessen Ausgang die Lastdruckmeldeleitung 22 angeschlossen ist.From the output connection of the pressure compensator 16a, 16b leads a working line 24a, 24b to the respective consumers 4 or 6. The load pressure of consumers 4, 6 will tapped via branch lines 26a, 26b and to one Shuttle valve 28 out, at the output of the load pressure reporting line 22 is connected.

    Die Ansteuerung der einstellbaren Meßblenden 14a, 14b erfolgt über manuell betätigbare Steuereinrichtungen 30a, 30b, die mit den Meßblenden 14a bzw. 14b in Wirkverbindung stehen.The control of the adjustable measuring orifices 14a, 14b takes place via manually operable control devices 30a, 30b, which is in operative connection with the measuring orifices 14a and 14b stand.

    Durch eine Schaltung der vorbeschriebenen Art ist eine klassische "LUDV"-Schaltung realisiert, bei der über die Druckwaagen 16a, 16b der Druckabfall über den Meßblenden 14a, 14b lastdruckunabhängig konstant gehalten wird. Beim Ausschöpfen der vollen Pumpenleistung werden üblicherweise beide Druckwaagen 16a, 16b zurückgeregelt, so daß der Hydraulikfluidvolumenstrom zu den beiden Verbrauchern 4, 6 um den gleichen Prozentanteil reduziert wird. Wie eingangs bereits beschrieben wurde, kann bei diesen Schaltungen dann ein Problem auftreten, wenn der lasthöhere Verbraucher (Löffel 4) auf Anschlag gefahren wird, so daß der Lastdruck dieses Verbrauchers im Bereich des Pumpenmaximaldruckes angesiedelt ist. Schaltet man nun zusätzlich einen lastniedrigeren Verbraucher hinzu, so geht der Volumenstrom des lastniedrigeren Verbrauchers auf einen Wert zurück, der durch die maximale Pumpenleistung vorgegeben ist. Ein großer Teil der Leistung wird in der abregelnden Druckwaage dieses Verbrauchers vernichtet.By a circuit of the type described is one Classic "LUDV" circuit implemented, in which over the pressure compensators 16a, 16b the pressure drop across the orifice plates 14a, 14b kept constant regardless of load pressure becomes. When exhausting the full pump capacity usually both pressure compensators 16a, 16b are reduced, so that the hydraulic fluid volume flow to the two consumers 4, 6 reduced by the same percentage becomes. As already described at the beginning, at a problem with these circuits if the higher loads (bucket 4) moved to the stop is so that the load pressure of this consumer in the area of the maximum pump pressure. One switches now add an additional load-lower consumer, this is how the volume flow of the lower load consumer goes to a value determined by the maximum pump output is specified. Much of the performance will destroyed in the regulating pressure compensator of this consumer.

    Um dies zu verhindern, wird bei der in Fig. 1 dargestellten Regelung dem lastniedrigeren Verbraucher b ein Bypasskanal 32 zugeordnet, der eine Umgehung der Druckwaage 16a ermöglicht. Der Bypasskanal 32 zweigt stromabwärts der Meßblende 14a ab und mündet in der Arbeitsleitung 24a zum Verbraucher 6. Im Bypasskanal 32 ist eine geeignete Steuereinrichtung 34 vorgesehen, die den Bypasskanal 32 in der Grundstellung absperrt und in Abhängigkeit vom Öffnungquerschnitt der Meßblende 14a aufsteuert. Durch diese Schaltung wird der Hydraulikfluidvolumenstrom zum Verbraucher 6 hin nicht durch die Druckwaage 16a abgeregelt, so daß sich ein niedrigerer Systemdruck als bei einem System ohne Bypasskanal 32 einstellt. Dies ermöglicht es, den Ausleger 6 mit einer größeren Geschwindigkeit auszufahren. Die mit dem Bezugszeichen 34 versehene Schalteinrichtung kann dabei eine beliebige Einrichtung sein, die geeignet ist, um den Bypasskanal 32 abzusperren und in Abhängigkeit von der Ansteuerung der Meßblende 14a aufzusteuern. To prevent this, the one shown in Fig. 1 Regulation the lower load consumer b Bypass channel 32 assigned to bypassing the pressure compensator 16a enables. The bypass channel 32 branches downstream the orifice 14a and ends in the working line 24a to the consumer 6. In the bypass channel 32 is one Suitable control device 34 is provided, the bypass channel 32 blocked in the basic position and dependent controls from the opening cross section of the orifice 14a. Through this circuit, the hydraulic fluid volume flow to the consumer 6 not through the pressure compensator 16a regulated so that there is a lower system pressure than in a system without a bypass channel 32. This allows the boom 6 at a higher speed extend. The number 34 provided switching device can be any Be a device that is suitable for the bypass channel 32nd shut off and depending on the control of the Open orifice 14a.

    In Fig. 2 ist das Schaltschema einer Ventilscheibe 35 eines Ventilblockes zur Realisierung der in Fig. 1 abgebildeten Schaltung dargestellt. Die Ventilscheibe 35 enthält die Druckwaage 16a, ein Proportionalventil 36, durch dessen Geschwindigkeitsteil die Meßblende 14a ausgebildet ist und den Bypasskanal 32, sowie die sonstigen, im folgenden näher beschriebenen Verbindungsleitungen der Hydraulikelemente. Bei dem in Fig. 2 dargestellten Ausführungsbeispiel sind im Proportionalventil 36 neben der Meßblende 14a auch noch ein Richtungsteil zur Ansteuerung der Verbraucher A, B, sowie die Ansteuerung des Bypasskanals 32 integriert.2 is the circuit diagram of a valve disk 35 a valve block for realizing that shown in FIG. 1 Circuit shown. The valve disc 35 contains the pressure compensator 16a, a proportional valve 36 the speed part of which the measuring aperture 14a is formed is and the bypass channel 32, as well as the others, in the following connecting lines of the hydraulic elements described in more detail. In the embodiment shown in Fig. 2 are in the proportional valve 36 next to the Orifice plate 14a also a directional part for control the consumer A, B, and the control of the bypass channel 32 integrated.

    Das Proportionalventil 36 hat einen Pumpenanschluß P, zwei Arbeitsanschlüsse A, B, die mit den Zylinderräumen eines Differentialzylinders b oder mit einem Hydromotor verbunden sind. Des weiteren sind ein Ausgangsanschluß P1 zur Druckwaage 16a, ein Bypass-Anschluß U, zwei Eingangsanschlüsse R, S des Richtungsteils und ein Tankanschluß T am Proportionalventil 36 ausgebildet.The proportional valve 36 has a pump connection P, two working ports A, B, with the cylinder chambers a differential cylinder b or with a hydraulic motor are connected. Furthermore, there is an output port P1 to the pressure compensator 16a, a bypass connection U, two input connections R, S of the directional part and a tank connection T formed on the proportional valve 36.

    Die beiden Stirnseiten des Ventilschiebers 38 des Proportionalventils 36 sind durch zwei Druckfedern 41a, 41b in ihre Grundposition vorgespannt. In dieser Grundposition sind die Anschlüsse P, A, B, U und S abgesperrt, während die Anschlüsse P1 und R mit dem Tank verbunden sind.The two end faces of the valve spool 38 of the Proportional valve 36 are formed by two compression springs 41a, 41b biased into its basic position. In this basic position ports P, A, B, U and S are closed, while ports P1 and R are connected to the tank are.

    Die Stirnflächen des Ventilschiebers 38 sind mit Steuerdrücken PST beaufschlagt, so daß dieser aus seiner federvorgespannten Grundposition herausbewegbar ist.The end faces of the valve spool 38 are acted upon by control pressures P ST , so that it can be moved out of its spring-loaded basic position.

    Der Ausgangsanschluß P1 ist über die Pumpenleitung 12a mit dem Eingangsanschluß Q der Druckwaage 16a verbunden. Wie bereits vorstehend erläutert, zweigt von der Pumpenleitung 12a die Steuerleitung 18 ab, über die der Druck stromabwärts der Meßblende 14a (Proportionalventil 36) an die in Fig. 2 linke Stirnseite der Druckwaage 16a gemeldet ist. Der Lastdruck des Verbrauchers 6 ist über die Lastmeldeleitung 20 mit der Lastdruckmeldeleitung 22 verbunden und zur Federseite der Druckwaage 16a geführt. Der Ausgangsanschluß C der Druckwaage 16a ist über Leitungen 40, 42 mit den Eingangsanschlüssen R bzw. S des Richtungsteils verbunden. In den Leitungen 40, 42 befinden sich zwei Rückschlagventile 56a, 56b, die eine Rückströmung des Hydraulikfluids vom Richtungsteil zur Druckwaage 16a verhindern.The output port P1 is through the pump line 12a connected to the input port Q of the pressure compensator 16a. As already explained above, branches of the Pump line 12a from the control line 18 via which the Pressure downstream of the orifice 14a (proportional valve 36) to the left end face of the pressure compensator 16a in FIG. 2 is reported. The load pressure of the consumer 6 is over the load signal line 20 with the load pressure signal line 22 connected and led to the spring side of the pressure compensator 16a. The output connection C of the pressure compensator 16a is via lines 40, 42 with the input connections R and S of the Directionally connected. Located in lines 40, 42 there are two check valves 56a, 56b that provide a backflow of the hydraulic fluid from the directional part to the pressure compensator 16a prevent.

    Der Tankanschluß T ist über eine Tankleitung 44 mit dem Tank verbunden. Durch die Druckwaage 16a wird bei Ansteuerung des Proportionalventils 36 der Druckabfall über der Meßblende 14a lastdruckunabhängig konstant gehalten, so daß der Volumenstrom zum Verbraucher 6 proportional zum Öffnungsquerschnitt der Meßblende 14a ist.The tank connection T is connected via a tank line 44 connected to the tank. Through the pressure compensator 16a, when activated of the proportional valve 36 the pressure drop across measuring orifice 14a kept constant regardless of load pressure, so that the volume flow to the consumer 6 proportional to the opening cross section of the orifice 14a.

    Bei Anlegen eines Steuerdruckes PST beispielsweise an die linke Stirnfläche des Proportionalventils 36 wird der Ventilschieber 38 nach rechts verschoben, so daß die Meßblende 14a zur Verbindung der Anschlüsse P, P1 aufgesteuert wird. Im Feinsteuerbereich, das heißt im ersten Teil des Ventilschieberhubes ist die Verbindung zum Bypasskanalanschluß U noch versperrt. Das Hydraulikfluid wird über die Arbeitsleitung 12a zum Eingangsanschluß Q und über die Steuerleitung 18 zur linken Stirnseite des Regelkolbens der Druckwaage 16a geführt, so daß diese in ihre Regelposition zum Konstanthalten des Druckabfalls über der Meßblende 14a verschoben wird.When a control pressure P ST is applied, for example, to the left end face of the proportional valve 36, the valve slide 38 is shifted to the right, so that the orifice 14a for opening the connections P, P1 is opened. In the fine control range, that is, in the first part of the valve spool stroke, the connection to the bypass duct connection U is still blocked. The hydraulic fluid is fed via the working line 12a to the input connection Q and via the control line 18 to the left end of the regulating piston of the pressure compensator 16a, so that it is shifted into its regulating position in order to keep the pressure drop across the measuring orifice 14a constant.

    Der derart eingestellte Hydraulikfluidstrom wird dann über die Leitung 40, die Anschlüsse R, A zum Arbeitsanschluß des Verbrauchers 6 geführt, während über den Arbeitsanschluß B und die Tankleitung 44 das Hydraulikfluid vom Verbraucher 6 zurück zum Tank geführt wird. Der Anschluß S ist verschlossen.The hydraulic fluid flow set in this way is then via line 40, the connections R, A to the working connection of the consumer 6 performed while on the work connection B and the tank line 44 the hydraulic fluid is led back to the tank by the consumer 6. The connection S is closed.

    Beim weiteren Auf steuern der Meßblende 14a, wird der Bypasskanal 32 durch den Ventilschieber 38 aufgesteuert, so daß das Hydraulikfluid direkt in die Leitung 40 einströmt. Der Volumenstrom zur Druckwaage 16a wird verringert oder gar ganz abgesperrt, so daß ein größerer Volumenstrom zum Verbraucher 6 geführt wird. Diese Vergrößerung des Volumenstroms führt auch dann zu einem Absinken des Systemdrucks, wenn der lasthöhere Verbraucher 4 auf Anschlag gefahren ist.On further control of the orifice 14a, the Bypass channel 32 controlled by valve slide 38, so that the hydraulic fluid flows directly into line 40. The volume flow to the pressure compensator 16a is reduced or shut off completely, so that a larger volume flow is led to the consumer 6. This enlargement of the volume flow also leads to a decrease of the system pressure when the higher load 4 on Stop has reached.

    Fig. 3 zeigt einen Schnitt durch ein Wegeventilsegment, durch das die in Fig. 2 dargestellte Schaltung realisiert ist. Das Wegeventilsegment hat eine Ventilplatte 52, in der Aufnahmebohrungen für den Ventilschieber 38, die Druckwaage 16a, zwei Druckbegrenzungsventile 54a, 54b und die beiden Rückschlag- oder Lasthalteventile 56a, 56b ausgebildet sind. In der Ventilplatte 52 sind des weiteren die beiden Arbeitsanschlüsse A, B, zwei Steueranschlüsse 58a, 58b zur Ansteuerung des Proportionalventils 36, ein Pumpenanschluß P, zumindest ein Anschluß für die Lastdruckmeldeleitung 22 und ein Tankanschluß vorgesehen.3 shows a section through a directional valve segment, through which the circuit shown in Fig. 2 is realized is. The directional valve segment has a valve plate 52, in the mounting holes for the valve slide 38, the pressure compensator 16a, two pressure relief valves 54a, 54b and the two check or load holding valves 56a, 56b are trained. In the valve plate 52 are further the two working connections A, B, two control connections 58a, 58b for controlling the proportional valve 36, a pump connection P, at least one connection for the Load pressure reporting line 22 and a tank connection are provided.

    Der prinzipielle Grundaufbau dieses Wegeventilsegmentes ist bereits aus dem Stand der Technik bekannt und beispielsweise in der eingangs genannten WO95/32364 beschrieben.The basic structure of this directional valve segment is already known from the prior art and described for example in the above-mentioned WO95 / 32364.

    Der Ventilschieber 38 hat in seinem mittleren Bereich einen Steuerbund 60, der im Zusammenwirken mit einem Steg 62 der Ventilbohrung die Meßblende 14a ausbildet. In der Darstellung gemäß Fig. 3 ist der Ventilschieber 38 durch die beiden Druckfedern 41a, 41b in seine Grundposition vorgespannt, in der keine Durchströmung der Meßblende 14a stattfindet.The valve spool 38 has in its central area a control collar 60, which in cooperation with a web 62 of the valve bore forms the orifice 14a. In the 3 is the valve spool 38 by the two compression springs 41a, 41b in its basic position biased in which no flow through the orifice 14a takes place.

    Die Ansteuerung des Proportionalventils 36 erfolgt durch Anlegen eines Steuerdruckes an die beiden Steueranschlüsse 58a bzw. 58b, die über Steuerleitungen mit dem Federraum 64a bzw. 64b des Proportionalventils 36 verbunden sind. In der Steuerleitung zwischen den Steueranschlüssen 58a, 58b und den Federräumen 64a bzw. 64b ist eine Düse mit einem Rückschlagventil ausgebildet, durch die eine Dämpfung der Ventilschieberbewegung möglich ist.The proportional valve 36 is activated by applying a control pressure to the two control connections 58a and 58b, which are connected to the Spring chamber 64a or 64b of the proportional valve 36 connected are. In the control line between the control connections 58a, 58b and the spring chambers 64a and 64b formed a nozzle with a check valve, by damping the valve spool movement is possible.

    Der Steuerbund 60 ist im Bereich seiner Stirnflächen mit einer Vielzahl von Steuerkerben 64 bzw. 66 versehen, über die Druckmittel aus einem mit dem Pumpenanschluß P verbundenen Ringraum 68 zum Eingangsanschluß Q geführt werden kann, so daß die in Fig. 3 untere Stirnfläche des Regelkolbens 72 der Druckwaage 16a mit dem Druck stromabwärts der Meßblende beaufschlagbar ist.The control collar 60 is in the area of its end faces provided with a plurality of control notches 64 and 66, via the pressure medium from a with the pump connection P connected annulus 68 led to the input port Q. can be, so that the lower end face in Fig. 3 of Control piston 72 of the pressure compensator 16a with the pressure downstream the measuring orifice can be acted upon.

    Bei einer Verschiebung des Wegeventilschiebers 38 nach rechts (Fig. 3) wird die Meßblende 14a durch Zusammenwirken der Steuerkerben 64 mit der einen Steuerkante des Steges 62 gebildet, während bei einer Verschiebung nach links die Steuerkerben 66 die Verbindung vom Ringraum 68 zur Druckwaage 16a hin aufsteuern.When the directional valve spool 38 is displaced to the right (Fig. 3), the orifice 14a by cooperation the control notches 64 with the one control edge of the web 62 formed during a shift to the left the control notches 66 the connection from the annulus 68 head towards the pressure compensator 16a.

    Der Eingangsanschluß Q der Druckwaage 16a ist als Axialanschluß ausgebildet, so daß der Fluiddruck auch auf die untere Stirnfläche 70 des Regelkolbens 72 wirkt. Der Ausgangsanschluß C ist als Radialanschluß ausgebildet und mündet in den Leitungen 40 bzw. 42. In diesen Leitungen 40, 42 sind die Lasthalteventile 56a, 56b angeordnet, die eine Rückströmung vom Ventilschieber 38 zur Druckwaage 16a hin verhindern und eine Durchströmung in umgekehrter Richtung ermöglichen. The input port Q of the pressure compensator 16a is as Axial connection designed so that the fluid pressure also on the lower end face 70 of the control piston 72 acts. The Output connection C is designed as a radial connection and opens into lines 40 and 42. In these lines 40, 42, the load holding valves 56a, 56b are arranged which a backflow from the valve spool 38 to the pressure compensator Prevent 16a and a flow in reverse Enable direction.

    Die Verbindung der Leitungen 40, 42 mit den Arbeitsanschlüssen A bzw. B oder dem Tankanschluß T erfolgt jeweils über ein Richtungsteil des Ventiischiebers 38. Das heißt, jedem Arbeitsanschluß A, B ist ein Richtungsteil zugeordnet, über das ein Arbeitsanschluß A bzw. B mit einer Leitung 40, 42 oder mit dem Tank T verbindbar ist.The connection of the lines 40, 42 to the work connections A or B or the tank connection T takes place in each case via a directional part of the valve slide 38. Das means that each working connection A, B is a directional part assigned, through which a work port A or B with a Line 40, 42 or can be connected to the tank T.

    Das in Fig. 3 rechts ausgebildete Richtungsteil für den Anschluß B hat drei im Axialabstand ausgebildete Steuerbünde 74, 76 und 78. Die Steuerbünde 76 und 78 sind jeweils mit Steuerkerben 80 bzw. 82 versehen, die sich zu dem zwischen diesen Steuerbünden 76, 78 angeordneten, radial zurückgesetzten Abschnitt hin öffnen.The directional part formed on the right in FIG port B has three axially spaced Tax groups 74, 76 and 78. The tax groups 76 and 78 are each provided with control notches 80 and 82, which are to radially arranged between these control collars 76, 78 open the recessed section.

    Das dem Arbeitsanschluß A zugeordnete Richtungsteil des Ventilschiebers 38 ist lediglich durch zwei beabstandete Steuerbünde 84, 86 gebildet. Im Steuerbund 86 sind Steuerkerben 88 ausgebildet, die in der Funktion den Steuerkerben 80 des Steuerbundes 78 entsprechen.The direction part assigned to the working connection A. the valve spool 38 is only spaced by two Tax frets 84, 86 formed. In the tax union 86 are Control notches 88 formed in the function of the Tax notches 80 of the tax union 78 correspond.

    Im Axialabstand zu der rechten Stirnfläche des Steuerbundes 86 münden am Außenumfang mehrere, am Umfang verteilte Schrägbohrungen 90, die mit einer gemeinsamen Axialbohrung 92 verbunden sind. Diese durchsetzt den Steuerbund 8 bis zum linken Endabschnitt des Ventilschiebers 38. Bei der dargestellten Variante ist der Endanschlag 94 des Ventilschiebers in die Axialbohrung 92 eingeschraubt, so daß deren linker Endabschnitt verschlossen ist.At an axial distance from the right face of the control collar 86 open on the outer circumference several, distributed around the circumference Oblique bores 90 that share a common Axial bore 92 are connected. This enforces the Control collar 8 to the left end portion of the valve spool 38. In the variant shown is the end stop 94 of the valve slide is screwed into the axial bore 92, so that its left end portion is closed is.

    Fig. 4 zeigt eine Detaildarstellung des Ventilschiebers 38 im Mittelbereich dieser Axialbohrung 92. Fig. 4 shows a detailed representation of the valve spool 38 in the central region of this axial bore 92.

    Demgemäß ist in der Axialbohrung 92 ein Rückhalteventil vorgesehen, dessen Ventilkörper 96 über eine Druckfeder 97 gegen einen Ventilsitz 98 vorgespannt ist.Accordingly, a check valve is in the axial bore 92 provided, the valve body 96 via a compression spring 97 is biased against a valve seat 98.

    Stromabwärts des Ventilkörpers 96 münden ein Radialbohrungsstern 100 und ein Schrägbohrungsstern 102. Der Radialbohrungsstern 100 ist durch einen Steg 104 der Aufnahmebohrung 103 des Ventilschiebers 38 versperrt. Der Schrägbohrungsstern 102 mündet in dem radial zurückgesetzten Abschnitt zwischen den Steuerbünden 84 und 86. Der gegen den Ventilsitz 98 vorgespannte Ventilkörper 96 verhindert, daß Hydraulikfluid vom Anschluß A in die Axialbohrung 92 einströmen kann. Eine Durchströmung in Gegenrichtung wird praktisch nicht verhindert, da die Druckfeder 97 schwach ist.A radial bore star opens downstream of the valve body 96 100 and a helical bore star 102. The Radial bore star 100 is through a web 104 of the receiving bore 103 of the valve spool 38 blocked. The Oblique bore star 102 opens into the radially recessed one Section between tax bands 84 and 86. The valve body 96 biased against the valve seat 98 prevents hydraulic fluid from port A into the Axial bore 92 can flow. A flow in The opposite direction is practically not prevented since the Compression spring 97 is weak.

    Die Geometrie des Radialbohrungssterns 100 und des Schrägbohrungssterns 102 ist derart gewählt, daß bei einer Verschiebung des Ventilschiebers 38 nach links über diese Sterne 100, 102 die Verbindung vom Arbeitsanschluß A zum Tankanschluß T aufsteuerbar ist. Alternativ könnten für die Aufsteuerung selbstverständlich auch Steuerkerben im rechten Stirnflächenbereich des Steuerbundes 84 verwendet werden.The geometry of the radial bore star 100 and Inclined bore star 102 is chosen such that at one Displacement of the valve slide 38 to the left these stars 100, 102 the connection from the work connection A can be opened to the tank connection T. Alternatively, you could of course also control notches for the control used in the right end face area of the control collar 84 become.

    Falls nun an den Steueranschluß 58a ein Steuerdruck angelegt wird, wird der Ventilschieber 38 in der Darstellung nach Fig. 3 nach rechts bewegt, so daß die Steuerkerben 64 im Zusammenwirken mit dem Steg 62 die Verbindung vom Pumpenanschluß P zum Eingangsanschluß Q der Druckwaage auf steuern.If there is now a control pressure at the control connection 58a is applied, the valve spool 38 is shown 3 moved to the right so that the control notches 64 in cooperation with the web 62 the connection from the pump connection P to the input connection Q Control the pressure compensator.

    Die in Fig. 3 oben liegende Stirnfläche 105 des Regelkolbens 72 ist von der Kraft einer Regelfeder 106 und vom Lastdruck beaufschlagt, der über eine Steuerkante und eine Winkelbohrung 108 im Regelkolben 72 von einer Umfangsnut 110 abgegriffen wird. Durch den am Eingangsanschluß Q anliegenden Druck stromabwärts der Meßblende 14a wird der Regelkolben 72 nach oben ausgelenkt und der Ausgangsanschluß C aufgesteuert bis sich ein Kräftegleichgewicht über dem Regelkolben 72 einstellt. Das Lasthalteventil 56a wird geöffnet und das Hydraulikfluid über die Leitung 40 und den Steuerbund 86 mit den Steuerkerben 88 zum Arbeitsanschluß A geführt. Gleichzeitig wird über den dem Arbeitsanschluß B zugeordneten Steuerbund 76 und die Steuerkerben 82 die Verbindung zwischen dem Arbeitsanschluß B und dem Tankanschluß T aufgesteuert, so daß das Hydraulikfluid vom Verbraucher in den Tank zurückströmen kann. In diesem Feinsteuerbereich sind die Schrägbohrungen 90 des Bypasskanals 32 noch nicht durch die Steuerkante 107 aufgesteuert.The end face 105 of the control piston lying at the top in FIG. 3 72 is of the force of a control spring 106 and acted upon by the load pressure, which via a control edge and an angular bore 108 in the control piston 72 from a circumferential groove 110 is tapped. Through the at the input connection Q applied pressure downstream of the orifice 14a the control piston 72 is deflected upwards and the output connection C opened up until there is a balance of forces above the control piston 72. The load holding valve 56a is opened and the hydraulic fluid via the Line 40 and the control collar 86 with the control notches 88 led to work port A. At the same time, the the tax union 76 assigned to the working connection B and the Control notches 82 the connection between the work connection B and the tank port T turned open, so that Flow hydraulic fluid back into the tank from the consumer can. The inclined bores are in this fine control range 90 of the bypass channel 32 not yet through the control edge 107 opened.

    Bei einer weiteren Verschiebung des Ventilschiebers 38 steuert die Steuerkante 107 den Bypasskanal 82 auf, so daß das Hydraulikfluid oder zumindest ein Teilvolumenstrom zum Arbeitsanschluß A geführt wird. Der Systemdruck sinkt ab, so daß der lastniedrigere Verbraucher 6 mit höherer Geschwindigkeit betätigt werden kann.If the valve spool is moved further 38, the control edge 107 opens the bypass channel 82, see above that the hydraulic fluid or at least a partial volume flow is led to work port A. The system pressure decreases, so that the load-lower consumer 6 with higher Speed can be operated.

    Bei einer Ansteuerung des Ventilschiebers 38 in umgekehrter Richtung hat der Bypasskanal keine Wirkung, da die umgekehrte Durchströmung von A zum Eingangsanschluß Q der Druckwaage 16a durch den auf dem Ventilsitz 98 aufliegenden Ventilkörper 96 verhindert wird.When the valve slide 38 is actuated in reverse The bypass channel has no effect since the reverse flow from A to the input port Q the pressure compensator 16a by the one resting on the valve seat 98 Valve body 96 is prevented.

    Im vorbeschriebenen Ausführungsbeispiel ist der Bypasskanal 32 lediglich dem Arbeitsanschluß A zugeordnet, der für die Hebenfunktion des Verbrauchers erforderlich ist. Selbstverständlich kann auch dem anderen Arbeitsanschluß B ein weiterer Bypasskanal zugeordnet werden, der dann einen identischen Aufbau wie der vorbeschriebene Arbeitsanschluß aufweisen würde. In the exemplary embodiment described above, the bypass channel is 32 only assigned to work port A, which is required for the lifting function of the consumer is. Of course, the other connection can also work B another bypass channel can be assigned to the then an identical structure to the work connection described above would have.

    In dem Diagramm gemäß Fig. 5 sind die Druck- und Volumenstromverhältnisse der vorbeschriebenen Vorgänge in Abhängigkeit von der Zeit dargestellt. Es sei angenommen, daß zunächst ein lasthöherer Verbraucher, beispielsweise ein Löffel auf Anschlag gefahren wird. Der entsprechende Druckverlauf ist in Fig. 5 mit durchgezogenen Linien dargestellt. Demgemäß steigt der Lastdruck an diesem Verbraucher sehr schnell an und erreicht zum Zeitpunkt t1 ein Maximum, das durch die Pumpenleistung psys vorgegeben ist.The diagram according to FIG. 5 shows the pressure and volume flow ratios of the above-described processes as a function of time. It is assumed that a higher load consumer, for example a spoon, is first moved to a stop. The corresponding pressure curve is shown in Fig. 5 with solid lines. Accordingly, the load pressure at this consumer rises very quickly and reaches a maximum at time t1, which is predetermined by the pump power p sys .

    Nach Erreichen dieses Maximaldruckes wird ein lastniedrigerer Verbraucher, beispielsweise ein Ausleger zugesteuert. Bei der Ansteuerung des diesem Verbraucher zugeordneten Proportionalventils 36 wird der Bypasskanal 32 in der vorbeschriebenen Weise aufgesteuert, so daß der Hydraulikfluidstrom Q zum lastniedrigeren Verbraucher ansteigt (gestrichelte Linie). Aufgrund dieses Anstieges des Hydraulikfluidvolumenstroms zum lastniedrigeren Verbraucher sinkt der Druck vom Systemdruck pSYS auf ein niedrigeres Niveau p* ab. Durch geeignete Wahl des Bypasskanaldurchmessers kann das Druckniveau p* eingestellt werden, so daß der Druck beispielsweise von einem Druck von 240 bar auf einen Druck p* von 200 bar absinkt.After reaching this maximum pressure, a lower load consumer, for example a boom, is activated. When the proportional valve 36 assigned to this consumer is activated, the bypass channel 32 is opened in the manner described above, so that the hydraulic fluid flow Q increases to the load-lower consumer (dashed line). Due to this increase in the hydraulic fluid volume flow to the load-lower consumer, the pressure drops from the system pressure p SYS to a lower level p *. The pressure level p * can be set by a suitable choice of the bypass channel diameter, so that the pressure drops, for example, from a pressure of 240 bar to a pressure p * of 200 bar.

    Zu Beginn der Ansteuerung des lastniedrigeren Verbrauchers erfolgt keine Beeinflussung des Druckes p, da der Bypasskanal zu Beginn der Ansteuerung noch nicht aufgesteuert ist.At the beginning of the control of the lower load consumer there is no influence on the pressure p since the bypass channel has not yet been opened at the start of activation is.

    Selbstverständlich ist die Erfindung keinesfalls darauf festgelegt, daß der Bypasskanal 32 in das Proportionalventil 36 integriert ist. Es sind auch andere Lösungen vorstellbar, bei denen der Bypasskanal über externe Schaltungen realisiert ist. Of course, the invention is by no means on it determined that the bypass channel 32 into the proportional valve 36 is integrated. There are other solutions too conceivable in which the bypass channel via external Circuits is realized.

    Offenbart ist ein LUDV-Schaltung zur Ansteuerung zumindest eines lastniedrigeren und eines lasthöheren Verbrauchers, wobei jedem Verbraucher eine Meßblende und eine nachgeschaltete Druckwaage zum Konstanthalten des Druckabfalls über der Meßblende zugeordnet sind. Der Druckwaage des lastniedrigeren Verbrauchers ist ein aufsteuerbarer Bypasskanal zugeordnet, über den die Druckwaage dieses Verbrauchers umgehbar ist.At least a LUDV circuit for control is disclosed a lower and a higher consumer, with each consumer an orifice and downstream pressure compensator to keep the Pressure drop across the orifice are assigned. The Pressure balance of the lower load is a controllable Bypass channel assigned via which the pressure compensator this consumer is bypassable.

    Claims (9)

    1. A hydraulic circuit for controlling at least one of a lower-load consumer and a higher-load consumer (4, 6), including a variable displacement pump (2) the setting of which is variable as a function of the load pressure of the consumers (4, 6), with an adjustable metering orifice (14a, 14b) comprising a downstream pressure compensator (16a, 16b) being provided between said variable displacement pump (2) and each consumer (4, 6), the control piston (72) of which may be acted on in a closing direction by the load pressure of the associated consumer (4, 6) and in an opening direction by the pressure downstream from said metering orifice (14a, 14b), characterized by
         a bypass channel (32) connecting the metering orifice output (P1) with at least one work port (A) for the lower-load consumer (6) while bypassing said associated individual-pressure compensator (16a).
    2. The hydraulic circuit in accordance with claim 1, characterized in that said metering orifice (14a, 14b) is formed by a proportional valve (36) whereby the work port (A, B) may be connected with said pump port (P) or a reservoir (T), and in that said bypass channel (32) may be controlled open in accordance with the valve spool position of said proportional valve (36).
    3. The hydraulic circuit in accordance with claim 2, characterized in that said bypass channel (32) is formed in said valve spool (38) and may be controlled open by a control land of said proportional valve (36).
    4. The hydraulic circuit in accordance with any one of the preceding claims, characterized in that in said bypass channel (32) a check valve (96, 97, 98) is arranged which prevents a hydraulic fluid flow from said consumer (6) to said metering orifice (14a).
    5. The hydraulic circuit in accordance with any one of claims 2 to 4, characterized in that said proportional valve (36) includes two work ports (A, B) for said consumer (6), and in that a bypass channel (32) is associated to each work port (A, B).
    6. The hydraulic circuit in accordance with any one of claims 2 to 5, characterized in that said bypass channel (32) is controlled open only following a predetermined stroke of said valve spool (36).
    7. The hydraulic circuit in accordance with any one of claims 2 to 6, characterized in that said valve spool (38) includes a velocity component having an approximately central arrangement and forming said metering orifice (14a), as well as two directional components through which the hydraulic fluid may be conveyed from said output port (Q) of said pressure compensator (16a) to a work port (A, B) or from said other work port (A, B) to a reservoir port (T), respectively, wherein said bypass channel (32) extends from said velocity component to one of said directional components.
    8. The hydraulic circuit in accordance with any one of claims 4 to 7, characterized in that said bypass channel (32) opens via oblique bores (90) in the range of said velocity component on the one hand, and via a radial bore star (100) and/or an oblique bore star (102) downstream from said check valve (96, 97, 98) in the range of a directional component on the other hand.
    9. The hydraulic circuit in accordance with any one of the preceding claims, characterized in that said variable displacement pump (2) is pressure and power controlled.
    EP99936360A 1998-06-29 1999-05-31 Hydraulic circuit Expired - Lifetime EP1092095B2 (en)

    Applications Claiming Priority (3)

    Application Number Priority Date Filing Date Title
    DE19828963 1998-06-29
    DE19828963A DE19828963A1 (en) 1998-06-29 1998-06-29 Hydraulic switch system for the operation of low- and high-load units
    PCT/DE1999/001591 WO2000000747A1 (en) 1998-06-29 1999-05-31 Hydraulic circuit

    Publications (3)

    Publication Number Publication Date
    EP1092095A1 EP1092095A1 (en) 2001-04-18
    EP1092095B1 true EP1092095B1 (en) 2003-03-26
    EP1092095B2 EP1092095B2 (en) 2007-04-18

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    Family Applications (1)

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    EP99936360A Expired - Lifetime EP1092095B2 (en) 1998-06-29 1999-05-31 Hydraulic circuit

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    US (1) US6367365B1 (en)
    EP (1) EP1092095B2 (en)
    JP (1) JP4520041B2 (en)
    KR (1) KR100636863B1 (en)
    DE (2) DE19828963A1 (en)
    WO (1) WO2000000747A1 (en)

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    KR100636863B1 (en) 2006-10-19
    JP4520041B2 (en) 2010-08-04
    WO2000000747A1 (en) 2000-01-06
    US6367365B1 (en) 2002-04-09
    EP1092095A1 (en) 2001-04-18
    DE19828963A1 (en) 1999-12-30
    KR20010071687A (en) 2001-07-31
    EP1092095B2 (en) 2007-04-18
    DE59904746D1 (en) 2003-04-30
    JP2002519596A (en) 2002-07-02

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