EP1711714B1 - Circuit arrangement - Google Patents

Circuit arrangement Download PDF

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Publication number
EP1711714B1
EP1711714B1 EP04801211A EP04801211A EP1711714B1 EP 1711714 B1 EP1711714 B1 EP 1711714B1 EP 04801211 A EP04801211 A EP 04801211A EP 04801211 A EP04801211 A EP 04801211A EP 1711714 B1 EP1711714 B1 EP 1711714B1
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EP
European Patent Office
Prior art keywords
pressure
section
valve
parallel
load
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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.)
Not-in-force
Application number
EP04801211A
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German (de)
French (fr)
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EP1711714A1 (en
Inventor
Gerd Anton Thiry
Alois Hoffmann
Harald BÄR
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Hydac Fluidtechnik GmbH
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Hydac Fluidtechnik GmbH
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Publication of EP1711714A1 publication Critical patent/EP1711714A1/en
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    • 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
    • F15B11/044—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the return line, i.e. "meter out"
    • F15B11/0445—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the return line, i.e. "meter out" with counterbalance valves, e.g. to prevent overrunning or for braking
    • 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
    • F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
    • F15B11/162—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for giving priority to particular servomotors or users
    • 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
    • F15B11/20—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors controlling several interacting or sequentially-operating 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
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30505—Non-return valves, i.e. check 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
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30505—Non-return valves, i.e. check valves
    • F15B2211/3051—Cross-check 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
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30525—Directional control valves, e.g. 4/3-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
    • F15B2211/305—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
    • F15B2211/3055—In combination with a pressure compensating valve the pressure compensating valve is arranged between directional control valve and return line
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/327—Directional control characterised by the type of actuation electrically or electronically
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/42—Flow control characterised by the type of actuation
    • F15B2211/426—Flow control characterised by the type of actuation electrically or electronically
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/455—Control of flow in the feed line, i.e. meter-in 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
    • F15B2211/505—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
    • F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief 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
    • F15B2211/50—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
    • F15B2211/50536—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using unloading valves controlling the supply pressure by diverting fluid to the return line
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5151—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a directional control valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—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
    • F15B2211/50—Pressure control
    • F15B2211/575—Pilot pressure control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/605—Load sensing circuits
    • F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
    • F15B2211/6055—Load sensing circuits having valve means between output member and the load sensing circuit using pressure relief 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
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7053—Double-acting 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
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7058—Rotary 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
    • F15B2211/70—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
    • F15B2211/781—Control of multiple output members one or more output members having priority

Definitions

  • the invention relates to a circuit arrangement with a load-sensing system according to the feature configuration of the preamble of claim 1.
  • load-pressure signaling system is also used as a synonym for load-sensing system, whereby the named system is a hydraulic control system with pressure and volume flow adaptation to the current requirements of one or more consumers.
  • load-sensing systems which are customary on the market, can be realized with both a constant-displacement pump and a variable-displacement pump.
  • the respective consumers can in principle be arranged in series and / or parallel to one another in the supply circuit.
  • the speed of the consumer is preferably controlled by a proportional flow controller, consisting of proportional throttle valve and bypass pressure compensator, independent of the load pressure.
  • a proportional flow controller consisting of proportional throttle valve and bypass pressure compensator, independent of the load pressure.
  • the speeds of both consumers can be set independently, which makes sense for a variety of applications.
  • the highest load pressure is determined and the pump pressure is raised by a certain amount above this load pressure, for example by means of a circulation pressure compensator.
  • a circulation pressure compensator In a system consisting of a combination of parallel and above-described series connection, however, no higher pressure can build up than is required for the series connection section, since there the excess fluid (oil) is led to the tank via the bypass pressure compensators becomes. This is particularly undesirable if higher pressures are needed in the parallel section, for example, the function a work machine and its parts to ensure that.
  • the invention has the object, while maintaining the advantages of the known circuit arrangements with load-sensing system to further improve that in a particularly energy-efficient manner, the circuit arrangement can be actuated.
  • This object is achieved by a circuit arrangement with the features of claim 1 in its entirety.
  • each consumption of the series section is associated with a bypass pressure compensator and that the control inputs of the respective bypass pressure compensator of the series section each associated with the output of the series section Shuttle valve are connected.
  • the respective highest load pressure is forwarded as a control pressure to the valve unit such that, if the load pressure of the parallel section is higher than the load pressure of the series section, the valve unit throttles the return flow for fluid until the pressure of the supply pump on or above the in the parallel section required pressure increases, the consumers of the parallel section are independent of the pressure level of the consumers of the series section operable. In that regard, it is also possible, regardless of the number of consumers in the series section to ensure sufficient fluid pressure for each consumer in the parallel section. For energy-saving operation of said circuit arrangement also contributes to the fact that the pump pressure depending on the load pressure is always raised only as far as necessary.
  • the valve unit is composed of a hydraulically controllable proportional slide valve, preferably a 2-way proportional slide valve educated. Due to the proportional slide valve, it is possible to raise the pump pressure of the supply pump only as much as necessary, which benefits the energy-saving operation of the entire system and thus the circuit arrangement.
  • a circulation pressure compensator is connected in the supply circuit between the supply pump and the return line, to which the highest load pressure is applied in total.
  • circuit arrangement according to the invention is explained in more detail using an exemplary embodiment according to the drawing.
  • the single figure in the form of a circuit diagram shows the essential components of the circuit arrangement according to the invention.
  • the circuit arrangement according to the invention is equipped with a load-sensing system, which is denoted by LS in the circuit diagram.
  • the circuit arrangement is further characterized in that individual consumers 10 are arranged as series consumers of a series section in the fluid flow direction one behind the other.
  • a parallel consumer 14 is connected in the hydraulic supply circuit 12.
  • the series consumers 10 are formed from individual hydraulic motors and the parallel load 14 from a conventional hydraulically operating working cylinder.
  • Said hydraulic supply circuit 12 opens at its free ends in a supply pump P and in a tank T. The connected to the tank T line of the supply circuit 12 forms the so-called. Return 16 of the circuit arrangement.
  • the load-sensing system LS By means of the load-sensing system LS, it is possible to determine the highest load pressure in the series and the parallel section, which is shown in the circuit diagram with LS series and LS-parallel.
  • the respective highest load pressure is forwarded as control pressure to a valve unit 18 for its activation. If, for example, the load pressure of the parallel section with the parallel consumers 14 is higher than the load pressure of the series section with the series consumers 10, the valve unit 18 is throttled so much relative to the return 16 for fluid until the pressure of the supply pump P is on or above that in the parallel section required pressure for this consumer 14 increases.
  • the parallel consumer 14 regardless of the pressure level of the series consumers 10 and to drive in such a way, which was not possible with the previously known circuit arrangements with load-sensing system.
  • the series or parallel section consists of at least one consumer 10,14, wherein preferably two series-connected loads 10 of the series section are arranged in the fluid flow direction before the parallel section with a parallel load 14.
  • the above-mentioned valve unit 18, the control pressures processed by the load-sensing system consists of a hydraulically controllable proportional spool valve, preferably a 2-way proportional spool valve.
  • each consumer 10 of the series section is assigned a bypass pressure compensator 20, 22.
  • the one control pressure line for the valve unit 18 is connected to a shuttle valve 24 of the series section and the other control pressure line to a shuttle valve 26 of the parallel section and to a shuttle valve 28 of the load-sensing system LS. How the connection is made in detail results directly from the circuit arrangement according to the figure. Furthermore, the control inputs of the respective bypass pressure compensators 20,22 of the series section are each connected to the associated output of the changeover valve 24 associated with the series section. As is clear from the circuit diagram, the output of the pressure compensator 20 is fluidly connected to the input of the pressure compensator 22 and the output of the pressure compensator 22 opens into the return line 16, which is connected on the input side to the valve unit 18.
  • a circulation pressure compensator 38 is connected in the supply circuit 12.
  • the control pressures for this circulating pressure compensator 38 are in turn formed on the one hand via the load-sensing system LS and on the other side on the input pressure to the pressure compensator 38 itself.
  • the output of the pressure compensator 38 is fluidly connected to the return line 16 and the input side with the supply pump P.
  • the pending pump supply pressure is also on the line 40 at the entrance of a 4/3-way valve 42 at.
  • the load-sensing system LS is protected by a pressure limiting valve 44 and is connected via a throttle or orifice 46 with the LS - total side of the shuttle valve 28.
  • the output side of the 4/3-way valve 42 opens into two parallel strands in the shuttle valve 26 and in two mutually releasable check valves 48, which in turn are connected on the output side to the piston and rod space of the working cylinder as parallel consumers 14.

Abstract

A circuit arrangement includes a load sensing system (LS) with individual loads ( 10,14 ) arranged in series forming a series section, and in parallel forming a parallel section. A hydraulic supply circuit ( 12 ) includes a supply pump (P) and a runback ( 16 ) for fluid. The load sensing system (LS) determines the highest load pressure in the series section and the parallel section. The loads of the parallel section can be actuated independently from the pressure level of the loads of the series section due to the highest load pressure being transferred as a control pressure to a valve unit ( 18 ) such that, as long as the load pressure of the parallel section is higher than the load pressure of the series section, the valve unit restricts the runback ( 16 ) so that the pressure of the supply pump (P) matches or exceeds the pressure required in the parallel section. Sufficient fluid pressure for the load in the parallel section is ensured independently of the number of loads in the series section.

Description

Die Erfindung betrifft eine Schaltungsanordnung mit einem Load-Sensing-System gemäß der Merkmalsausgestaltung des Oberbegriffes des Patentanspruches 1.The invention relates to a circuit arrangement with a load-sensing system according to the feature configuration of the preamble of claim 1.

Als Synonym für Load-Sensing-System findet auch der Begriff Lastdruck - Meldesystem Anwendung, wobei es sich bei dem genannten System um ein hydraulisches Steuerungssystem mit Druck- und Volumenstromanpassung handelt, und zwar an die momentanen Anforderungen eines oder mehrerer Verbraucher. Dahingehende Load-Sensing-Systeme, die marktüblich sind, lassen sich sowohl mit einer Konstantpumpe als auch mit einer Verstellpumpe realisieren.The term load-pressure signaling system is also used as a synonym for load-sensing system, whereby the named system is a hydraulic control system with pressure and volume flow adaptation to the current requirements of one or more consumers. These load-sensing systems, which are customary on the market, can be realized with both a constant-displacement pump and a variable-displacement pump.

Ferner können in hydraulischen Systemen und Steuerungen die jeweiligen Verbraucher prinzipiell in Reihe und/oder parallel zueinander im Versorgungskreis angeordnet sein.Furthermore, in hydraulic systems and controls, the respective consumers can in principle be arranged in series and / or parallel to one another in the supply circuit.

Bei der üblichen Reihenschaltung werden die Verbraucher vom gleichen Flüssigkeitsstrom durchflossen und die Drücke addieren sich. Der Rücklauf des einen Verbrauchers bildet den Zulauf des nächsten Verbrauchers, so dass jedem Verbraucher der gesamte Volumenstrom in Hintereinanderabfolge zur Verfügung steht. Die Reihenschaltung kommt insbesondere dort zur Anwendung, wo Verbraucher mit geringen Lastdrücken vorhanden sind.In the usual series connection, the consumers are traversed by the same liquid flow and the pressures add up. The return of one consumer forms the inlet of the next consumer, so that each consumer the entire volume flow is available in a sequential order. The series connection is used in particular where consumers are present with low load pressures.

Die Geschwindigkeit der Verbraucher wird vorzugsweise über Proportionalstromregler, bestehend aus Proportional-Drosselventil und Bypass-Druckwaage, lastdruckunabhängig geregelt. Bei dieser Anordnung können die Geschwindigkeiten beider Verbraucher unabhängig voneinander eingestellt werden, was für eine Vielzahl von Anwendungsfällen sinnvoll ist.The speed of the consumer is preferably controlled by a proportional flow controller, consisting of proportional throttle valve and bypass pressure compensator, independent of the load pressure. In this arrangement, the speeds of both consumers can be set independently, which makes sense for a variety of applications.

Parallel geschaltete Verbraucher unterliegen hingegen alle dem gleichen Eingangsdruck und die Volumenströme addieren sich. Um alle Verbraucher gleichzeitig mit maximaler Geschwindigkeit zu betreiben, muß die Versorgungspumpe dann entsprechend groß dimensioniert sein, was bei der Reihenschaltung, wie dargelegt, nicht notwendig ist.In contrast, consumers connected in parallel are all subject to the same inlet pressure and the volume flows add up. In order to operate all consumers at the same time at maximum speed, the supply pump must then be dimensioned correspondingly large, which is not necessary in the series connection, as set forth.

In einem Load-Sensing-System der genannten Art wird der höchste Lastdruck ermittelt und der Pumpendruck um einen bestimmten Betrag über diesen Lastdruck angehoben, beispielsweise mittels einer Umlauf Druckwaage. In einem System, das aus einer Kombination aus Parallel- und oben beschriebener Reihenschaltung besteht, kann sich jedoch kein höherer Druck aufbauen, als für die Reihenschaltungs-Sektion erforderlich ist, da dort das überschüssige Fluid (Öl) über die Bypass-Druckwaagen zum Tank geführt wird. Dies ist insbesondere dann unerwünscht, wenn in der Parallelsektion höhere Drücke benötigt werden, beispielsweise um die Funktion einer Arbeitsmaschine und deren Teile dahingehend sicherstellen zu können.In a load-sensing system of the type mentioned, the highest load pressure is determined and the pump pressure is raised by a certain amount above this load pressure, for example by means of a circulation pressure compensator. In a system consisting of a combination of parallel and above-described series connection, however, no higher pressure can build up than is required for the series connection section, since there the excess fluid (oil) is led to the tank via the bypass pressure compensators becomes. This is particularly undesirable if higher pressures are needed in the parallel section, for example, the function a work machine and its parts to ensure that.

Zur Beseitigung dieser Nachteile wurde demgemäß in der US-A-4 756 298 und der FR-A-2 754 571 bereits eine gattungsgemäße Schaltungsanordnung vorgeschlagen mit einem Load-Sensing-System, bei der einzelne Verbraucher sowohl in Reihe unter Bildung einer Reihensektion als auch parallel unter Bildung einer Parallelsektion zueinander angeordnet in einen hydraulischen Versorgungskreis mit mindestens einer Versorgungspumpe und einem Rücklauf für Fluid geschaltet sind, wobei das Load-Sensing-System den jeweils höchsten Lastdruck bei der Reihen- und Parallelsektion ermittelt und wobei der jeweils höchste Lastdruck als Steuerdruck an eine Ventileinheit derart weitergeleitet ist, dass, sofern der Lastdruck der Parallelsektion höher liegt als der Lastdruck der Reihensektion, die Ventileinheit den Rücklauf für Fluid so stark androsselt, bis der Druck der Versorgungspumpe auf oder über den in der Parallelsektion benötigten Druck ansteigt.To eliminate these disadvantages has been accordingly in the US-A-4,756,298 and the FR-A-2 754 571 already proposed a generic circuit arrangement with a load-sensing system in which individual consumers are connected both in series to form a series section and parallel to form a parallel section arranged in a hydraulic supply circuit with at least one supply pump and a return for fluid, wherein the load sensing system determines the respective highest load pressure in the series and parallel section and wherein the respective highest load pressure as control pressure to a valve unit is forwarded such that, if the load pressure of the parallel section is higher than the load pressure of the series section, the valve unit Throttle return fluid until the pressure of the supply pump rises to or above the pressure required in the parallel section.

Ausgehend von diesem Stand der Technik liegt der Erfindung die Aufgabe zugrunde, unter Beibehalten der Vorteile die bekannten Schaltungsanordnungen mit Load-Sensing-System dahingehend weiter zu verbessern, dass in besonders energiesparender Weise die Schaltungsanordnung betätigbar ist. Eine dahingehende Aufgabe löst eine Schaltungsanordnung mit den Merkmalen des Patentanspruches 1 in seiner Gesamtheit.Based on this prior art, the invention has the object, while maintaining the advantages of the known circuit arrangements with load-sensing system to further improve that in a particularly energy-efficient manner, the circuit arrangement can be actuated. This object is achieved by a circuit arrangement with the features of claim 1 in its entirety.

Gemäß dem kennzeichnenden Teil des Patentanspruches 1 ist vorgesehen, dass jedem Verbrauchen der Reihensektion eine Bypass-Druckwaage zugeordnet ist und dass die Steuereingänge der jeweiligen Bypass-Druckwaage der Reihensektion jeweils an den Ausgang des der Reihensektion zugeordneten Wechselventils angeschlossen sind. Dies leistet einen Beitrag dazu, dass die Schaltungsanordnung besonders energiesparend arbeiten kann.According to the characterizing part of claim 1, it is provided that each consumption of the series section is associated with a bypass pressure compensator and that the control inputs of the respective bypass pressure compensator of the series section each associated with the output of the series section Shuttle valve are connected. This makes a contribution to the fact that the circuit arrangement can work particularly energy-saving.

Der jeweils höchste Lastdruck ist als Steuerdruck an die Ventileinheit derart weitergeleitet, dass, sofern der Lastdruck der Parallelsektion höher liegt als der Lastdruck der Reihensektion, die Ventileinheit den Rücklauf für Fluid so stark androsselt, bis der Druck der Versorgungspumpe auf oder über den in der Parallelsektion benötigten Druck ansteigt, wobei die Verbraucher der Parallelsektion unabhängig vom Druckniveau der Verbraucher der Reihensektion betätigbar sind. Insoweit ist es auch möglich, unabhängig von der Anzahl der Verbraucher in der Reihensektion genügend Fluiddruck für den jeweiligen Verbraucher in der Parallelsektion sicherzustellen. Zum energiesparenden Betrieb der genannten Schaltungsanordnung trägt auch mit bei, dass der Pumpendruck lastdruckabhängig immer nur insoweit angehoben wird, wie erforderlich.The respective highest load pressure is forwarded as a control pressure to the valve unit such that, if the load pressure of the parallel section is higher than the load pressure of the series section, the valve unit throttles the return flow for fluid until the pressure of the supply pump on or above the in the parallel section required pressure increases, the consumers of the parallel section are independent of the pressure level of the consumers of the series section operable. In that regard, it is also possible, regardless of the number of consumers in the series section to ensure sufficient fluid pressure for each consumer in the parallel section. For energy-saving operation of said circuit arrangement also contributes to the fact that the pump pressure depending on the load pressure is always raised only as far as necessary.

Bei einer bevorzugten Ausführungsform der erfindungsgemäßen Schaltungsanordnung ist die Ventileinheit aus einem hydraulisch steuerbaren Proportionalschieberventil, vorzugsweise einem 2-Wege-Proportionalschieberventil gebildet. Aufgrund des Proportionalschieberventils ist es möglich, den Pumpendruck der Versorgungspumpe nur so weit anzuheben, wie erforderlich, was dem energiesparenden Betrieb des Gesamtsystems und somit der Schaltungsanordnung zugute kommt.In a preferred embodiment of the circuit arrangement according to the invention, the valve unit is composed of a hydraulically controllable proportional slide valve, preferably a 2-way proportional slide valve educated. Due to the proportional slide valve, it is possible to raise the pump pressure of the supply pump only as much as necessary, which benefits the energy-saving operation of the entire system and thus the circuit arrangement.

Bei einer weiteren bevorzugten Ausführungsform der erfindungsgemäßen Schaltungsanordnung ist zwischen der Versorgungspumpe und dem Rücklauf eine Umlauf-Druckwaage in den Versorgungskreislauf geschaltet, an der insgesamt der höchste Lastdruck anliegt. Wenn somit kein Verbraucher aktiv ist oder benötigt wird, kann das Fluid (Öl) mit geringem Druckverlust über die Umlauf-Druckwaage zum Tank rückgeführt werden, was wiederum einem energiesparenden Betrieb zugute kommt.In a further preferred embodiment of the circuit arrangement according to the invention, a circulation pressure compensator is connected in the supply circuit between the supply pump and the return line, to which the highest load pressure is applied in total. Thus, when no consumer is active or needed, the fluid (oil) can be returned to the tank with low pressure loss via the recirculating pressure compensator, which in turn benefits an energy saving operation.

Weitere vorteilhafte Ausführungsformen sind Gegenstand der sonstigen Unteransprüche.Further advantageous embodiments are the subject of the other dependent claims.

Im folgenden wird die erfindungsgemäße Schaltungsanordnung anhand eines Ausführungsbeispiels nach der Zeichnung näher erläutert. Dabei zeigt die einzige Figur in der Art einer Schaltplandarstellung die wesentlichen Komponenten der erfindungsgemäßen Schaltungsanordnung.In the following the circuit arrangement according to the invention is explained in more detail using an exemplary embodiment according to the drawing. The single figure in the form of a circuit diagram shows the essential components of the circuit arrangement according to the invention.

Die erfindungsgemäße Schaltungsanordnung ist mit einem Load-Sensing-System ausgestattet, das in dem Schaltplan mit LS bezeichnet ist. Die Schaltungsanordnung ist des weiteren dadurch charakterisiert, dass einzelne Verbraucher 10 als Reihenverbraucher einer Reihensektion in Fluidströmungsrichtung hintereinander angeordnet sind. Neben den Reihenverbrauchern 10 und parallel zu diesen sowie unter Bildung einer Parallelsektion ist in den hydraulischen Versorgungskreis 12 ein Parallelverbraucher 14 geschaltet. Die Reihenverbraucher 10 sind aus einzelnen hydraulischen Motoren gebildet und der Parallelverbraucher 14 aus einem üblichen hydraulisch arbeitenden Arbeitszylinder. Der genannte hydraulische Versorgungskreis 12 mündet an seinen freien Enden in eine Versorgungspumpe P sowie in einen Tank T. Die an den Tank T angeschlossene Leitung des Versorgungskreises 12 bildet den sog. Rücklauf 16 der Schaltungsanordnung.The circuit arrangement according to the invention is equipped with a load-sensing system, which is denoted by LS in the circuit diagram. The circuit arrangement is further characterized in that individual consumers 10 are arranged as series consumers of a series section in the fluid flow direction one behind the other. In addition to the series consumers 10 and parallel to these and forming a parallel section, a parallel consumer 14 is connected in the hydraulic supply circuit 12. The series consumers 10 are formed from individual hydraulic motors and the parallel load 14 from a conventional hydraulically operating working cylinder. Said hydraulic supply circuit 12 opens at its free ends in a supply pump P and in a tank T. The connected to the tank T line of the supply circuit 12 forms the so-called. Return 16 of the circuit arrangement.

Mittels des Load-Sensing-Systems LS ist es möglich, den jeweils höchsten Lastdruck bei der Reihen- und der Parallelsektion zu ermitteln, was in dem Schaltplan mit LS-Reihe und LS-Parallel wiedergegeben ist. Der jeweils höchste Lastdruck, sei es von der Reihen- oder der Parallelsektion, wird als Steuerdruck an eine Ventileinheit 18 zu deren Ansteuerung weitergeleitet. Liegt dann beispielsweise der Lastdruck der Parallelsektion mit den Parallelverbrauchern 14 höher als der Lastdruck der Reihensektion mit den Reihenverbrauchern 10, wird die Ventileinheit 18 bezogen auf den Rücklauf 16 für Fluid so stark angedrosselt, bis der Druck der Versorgungspumpe P auf oder über den in der Parallelsektion benötigten Druck für diesen Verbraucher 14 ansteigt. Somit ist es möglich, den Parallelverbraucher 14 unabhängig vom Druckniveau der Reihenverbraucher 10 zu betätigen und dergestalt anzusteuern, was mit den bisher bekannten Schaltungsanordnungen mit Load-Sensing-System nicht möglich war.By means of the load-sensing system LS, it is possible to determine the highest load pressure in the series and the parallel section, which is shown in the circuit diagram with LS series and LS-parallel. The respective highest load pressure, be it from the series or the parallel section, is forwarded as control pressure to a valve unit 18 for its activation. If, for example, the load pressure of the parallel section with the parallel consumers 14 is higher than the load pressure of the series section with the series consumers 10, the valve unit 18 is throttled so much relative to the return 16 for fluid until the pressure of the supply pump P is on or above that in the parallel section required pressure for this consumer 14 increases. Thus, it is possible to operate the parallel consumer 14 regardless of the pressure level of the series consumers 10 and to drive in such a way, which was not possible with the previously known circuit arrangements with load-sensing system.

Die Reihen- oder Parallelsektion besteht mindestens aus einem Verbraucher 10,14, wobei vorzugsweise zwei in Reihe geschaltete Verbraucher 10 der Reihensektion in Fluidströmungsrichtung vor der Parallelsektion mit einem Parallelverbraucher 14 angeordnet sind. Es sind hier aber auch andere Verbrauchergestaltungen denkbar, beispielsweise nur ein Verbraucher 10 für die Reihensektion und zwei oder mehr Verbraucher für die Parallelsektion (nicht dargestellt). Die vorstehend erwähnte Ventileinheit 18, die die Steuerdrücke des Load-Sensing-Systems verarbeitet, besteht aus einem hydraulisch steuerbaren Proportionalschieberventil, vorzugsweise aus einem 2-Wege-Proportionalschieberventil. Des weiteren ist jedem Verbraucher 10 der Reihensektion eine Bypass-Druckwaage 20,22 zugeordnet.The series or parallel section consists of at least one consumer 10,14, wherein preferably two series-connected loads 10 of the series section are arranged in the fluid flow direction before the parallel section with a parallel load 14. However, other consumer designs are also conceivable here, for example only one consumer 10 for the series section and two or more consumers for the parallel section (not shown). The above-mentioned valve unit 18, the control pressures processed by the load-sensing system, consists of a hydraulically controllable proportional spool valve, preferably a 2-way proportional spool valve. Furthermore, each consumer 10 of the series section is assigned a bypass pressure compensator 20, 22.

Die eine Steuerdruckleitung für die Ventileinheit 18 ist an ein Wechselventil 24 der Reihensektion angeschlossen und die andere Steuerdruckleitung an ein Wechselventil 26 der Parallelsektion sowie an ein Wechselventil 28 des Load-Sensing-Systems LS. Wie die Verschaltung im einzelnen vorgenommen ist, ergibt sich unmittelbar aus der Schaltungsanordnung nach der Figur. Ferner sind die Steuereingänge der jeweiligen Bypass-Druckwaagen 20,22 der Reihensektion jeweils an den zugeordneten Ausgang des der Reihensektion zugeordneten Wechselventils 24 angeschlossen. Wie sich des weiteren aus der Schaltplandarstellung ergibt, ist der Ausgang der Druckwaage 20 fluidführend mit dem Eingang der Druckwaage 22 verbunden und der Ausgang der Druckwaage 22 mündet in die Rücklaufleitung 16, die eingangsseitig an die Ventileinheit 18 angeschlossen ist.The one control pressure line for the valve unit 18 is connected to a shuttle valve 24 of the series section and the other control pressure line to a shuttle valve 26 of the parallel section and to a shuttle valve 28 of the load-sensing system LS. How the connection is made in detail results directly from the circuit arrangement according to the figure. Furthermore, the control inputs of the respective bypass pressure compensators 20,22 of the series section are each connected to the associated output of the changeover valve 24 associated with the series section. As is clear from the circuit diagram, the output of the pressure compensator 20 is fluidly connected to the input of the pressure compensator 22 and the output of the pressure compensator 22 opens into the return line 16, which is connected on the input side to the valve unit 18.

In Fluidströmungsrichtung vor der Druckwaage 20 erfolgt in einem Abzweig zu der Reihensektion der Anschluß des ersten Verbrauchers 10 an den Versorgungskreis 12, wobei die dahingehende Versorgung über ein Proportional-Drosselventil 30 absperrbar ist. Der Ausgang des in Reihe ersten Verbrauchers 10 mündet auf die Eingangsseite eines weiteren Proportional-Drosselventils 32, an den der zweite Verbraucher 10 ausgangsseitig angeschlossen ist. Der jeweilige Ausgang des Verbrauchers 10 ist über ein Rückschlagventil 34 abgesichert. Des weiteren ist der Eingang des Proportional-Drosselventils 32 fluidführend an die Verbindungsleitung 36 zwischen den beiden Druckwaagen 20,22 angeschlossen. Der anstehende Fluiddruck an der Ausgangsseite der beiden Proportional-Drosselventile 30,32 wird als Steuerdruck sowohl auf die jeweils einen Seiten der Druckwaagen 20,22 geführt als auch zum Wechselventil 24. Auf der gegenüberliegenden Seite der Druckwaagen 20,22 liegt als Steuerdruck der eingangsseitige Fluiddruck bei den genannten Druckwaagen 20,22 an.In the fluid flow direction in front of the pressure compensator 20 takes place in a branch to the series section of the terminal of the first load 10 to the supply circuit 12, wherein the pertinent supply via a proportional throttle valve 30 is shut off. The output of the first consumer in series 10 opens on the input side of a further proportional throttle valve 32 to which the second load 10 is connected on the output side. The respective output of the consumer 10 is secured by a check valve 34. Furthermore, the input of the proportional throttle valve 32 is fluidly connected to the connecting line 36 between the two pressure compensators 20,22. The applied fluid pressure on the output side of the two proportional throttle valves On the opposite side of the pressure compensators 20,22 is located as a control pressure of the input side fluid pressure at said pressure compensators 20,22 on.

Zwischen der Versorgungspumpe P und dem Rücklauf 16 ist in den Versorgungskreis 12 eine Umlauf-Druckwaage 38 geschaltet. Die Steuerdrücke für diese Umlauf-Druckwaage 38 sind wiederum auf der einen Seite über das Load-Sensing-System LS gebildet und auf der anderen Seite über den Eingangsdruck an der Druckwaage 38 selbst. Der Ausgang der Druckwaage 38 ist fluidführend mit dem Rücklauf 16 verbunden und die Eingangsseite mit der Versorgungspumpe P. Der dahingehende Pumpenversorgungsdruck steht auch über die Leitung 40 am Eingang eines 4/3-Wege-Ventils 42 an. Das Load-Sensing-System LS ist über ein Druckbegrenzungsventil 44 abgesichert und ist über eine Drossel oder Blende 46 mit der LS - Gesamtseite des Wechselventils 28 verbunden.Between the supply pump P and the return 16, a circulation pressure compensator 38 is connected in the supply circuit 12. The control pressures for this circulating pressure compensator 38 are in turn formed on the one hand via the load-sensing system LS and on the other side on the input pressure to the pressure compensator 38 itself. The output of the pressure compensator 38 is fluidly connected to the return line 16 and the input side with the supply pump P. The pending pump supply pressure is also on the line 40 at the entrance of a 4/3-way valve 42 at. The load-sensing system LS is protected by a pressure limiting valve 44 and is connected via a throttle or orifice 46 with the LS - total side of the shuttle valve 28.

Die Ausgangsseite des 4/3-Wege-Ventils 42 mündet in zwei parallelen Strängen in das Wechselventil 26 ein sowie in zwei gegenseitig entsperrbare Rückschlagventile 48, die ausgangsseitig wiederum an dem Kolben- und Stangenraum des Arbeitszylinders als Parallelverbraucher 14 angeschlossen sind.The output side of the 4/3-way valve 42 opens into two parallel strands in the shuttle valve 26 and in two mutually releasable check valves 48, which in turn are connected on the output side to the piston and rod space of the working cylinder as parallel consumers 14.

Mit der erfindungsgemäßen Ventilanordnung mit einem Load-Sensing-System sind die Verbraucher 10,14 sowohl in Reihe als auch parallel zueinander angeordnet. Alle Reihenverbraucher 10 sind, wie dargelegt, mit einer Bypass-Druckwaage 20,22 ausgestattet. Der jeweils höchste Lastdruck in der Reihensektion und der Parallelsektion werden getrennt voneinander ermittelt und als Steuerdrücke, wie beschrieben, an ein hydraulisch gesteuertes 2-Wege-Proportionalschieberventil 18 gemeldet. Liegt der Druck der Parallelverbraucher 14 über dem der Reihenverbraucher 10, so drosselt dieses Ventil 18 den Rücklauf 16 der Reihensektion so stark an, bis der Pumpendruck der Versorgungspumpe P über den in der Parallelsektion benötigten Druck ansteigt. Der insgesamt höchste Lastdruck liegt dabei immer an der Umlauf-Druckwaage 38 an. Die genannte Schaltungsanordnung arbeitet energiesparend, da der Pumpendruck lastdruckabhängig immer nur so weit angehoben wird, wie erforderlich. Zusammenfassend lassen sich die Vorteile wie folgt beschreiben:

  • Parallelverbraucher 14 können unabhängig vom Druckniveau der Reihenverbraucher 10 betätigt werden,
  • der Pumpendruck der Versorgungspumpe P wird durch das 2-Wege-Proportionalschieberventil 18 nur so weit angehoben wie erforderlich,
  • wenn kein Verbraucher 10,14 aktiv ist, wird das Fluid mit geringem Druckverlust über die Umlauf-Druckwaage 38 zum Tank T geführt.
With the valve arrangement according to the invention with a load-sensing system, the consumers 10, 14 are arranged both in series and parallel to one another. All series consumers 10 are, as stated, equipped with a bypass pressure compensator 20,22. The respective highest load pressure in the series section and the parallel section are determined separately and as control pressures, as described, to a hydraulically controlled 2-way proportional spool valve 18 reported. If the pressure of the parallel consumers 14 is greater than that of the series consumer 10, this valve 18 throttles the return 16 of the series section until the pump pressure of the supply pump P rises above the pressure required in the parallel section. The total highest load pressure is always at the circulation pressure compensator 38. Said circuit arrangement works energy-saving, since the pump pressure depending on the load pressure is always raised only as far as necessary. In summary, the advantages can be described as follows:
  • Parallel consumers 14 can be actuated independently of the pressure level of the series consumers 10,
  • the pump pressure of the supply pump P is raised by the 2-way proportional spool valve 18 only as much as necessary,
  • if no consumer 10,14 is active, the fluid is passed through the circulation pressure compensator 38 to the tank T with low pressure loss.

Claims (7)

  1. Switching arrangement with a load sensing system (LS), where a single consumer (10, 14) is switched in series forming a sequence section as well as forming a parallel section located in relation to each other within a hydraulic supply cycle (12) with at least one supply pump (P) and a return (16) for fluid, whereby the load sensing system (LS) detects the relevant highest load pressure within the serial and parallel sections, and whereby the relevant highest load pressure is transmitted as a control pressure to a valve unit (18) in such a way that the valve unit throttles the return (16) of the fluid until the pressure of the supply pump (P) rises to or above the pressure required within the parallel section as long as the load pressure of the parallel section is higher than the load pressure of the serial section, characterised in that by-pass pressure scales (20, 22) are allocated to each consumer (10) of the serial section, and in that the control inputs of the relevant by-pass pressure scales (20, 22) of the serial section are each connected with the output of one of the alternating valves (24) of the serial section.
  2. Switching arrangement according to Claim 1, characterised in that the valve unit (18) consists of a hydraulically controllable proportional displacement valve, preferably a 2-way proportional displacement valve.
  3. Switching arrangement according to Claim 1 or 2, characterised in that the control pressure line for the valve unit (18) is connected with the alternating valve (24) of the serial section, and in that the other control pressure line is connected with at least one alternating valve (26) of the parallel section and with at least one alternating valve (28) of the load sensing system (LS).
  4. Switching arrangement according to one of the Claims 1 to 3, characterised in that circulation pressure scales (38) are switched in the supply cycle (12) between the supply pump (P) and the return (16) where the overall highest load pressure lies.
  5. Switching arrangement according to one of the Claims 1 to 4, characterised in that a proportional throttle valve (30) is located between the first consumer (10) of the serial section viewed in the fluid flow direction and the supply pump (P) as well as a further proportional throttle valve (32) between the relevant previous and the relevant subsequent consumer (10) of a serial section.
  6. Switching arrangement according to one of the Claims 1 to 5, characterised in that simultaneously de-lockable non-return valves (48) are located between the alternating valve (26) of the parallel section and the associated consumer (14).
  7. Switching arrangement according to one of the Claims 1 to 6, characterised in that the relevant consumer (10) of the serial section is a hydraulic motor, and the consumer (14) of the parallel section a hydraulic working cylinder.
EP04801211A 2004-02-05 2004-12-08 Circuit arrangement Not-in-force EP1711714B1 (en)

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ATE398240T1 (en) 2008-07-15
JP4777910B2 (en) 2011-09-21
JP2007520674A (en) 2007-07-26
US20070137192A1 (en) 2007-06-21
WO2005075833A8 (en) 2005-11-17
DE102004005606B3 (en) 2005-10-06
WO2005075833A1 (en) 2005-08-18
EP1711714A1 (en) 2006-10-18
DE502004007371D1 (en) 2008-07-24
US7426884B2 (en) 2008-09-23

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