EP1954949B1 - Hydraulic control device - Google Patents

Hydraulic control device Download PDF

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Publication number
EP1954949B1
EP1954949B1 EP06818465A EP06818465A EP1954949B1 EP 1954949 B1 EP1954949 B1 EP 1954949B1 EP 06818465 A EP06818465 A EP 06818465A EP 06818465 A EP06818465 A EP 06818465A EP 1954949 B1 EP1954949 B1 EP 1954949B1
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EP
European Patent Office
Prior art keywords
pressure
load
valve
consumer
hydraulic
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 - Fee Related
Application number
EP06818465A
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German (de)
French (fr)
Other versions
EP1954949A1 (en
Inventor
Wolfgang Kauss
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Bosch Rexroth AG
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Bosch Rexroth AG
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Publication of EP1954949A1 publication Critical patent/EP1954949A1/en
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Expired - Fee Related legal-status Critical Current
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/05Systems 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
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/028Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/161Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
    • F15B11/165Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for adjusting the pump output or bypass in response to demand
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/161Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
    • F15B11/168Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load with an isolator valve (duplicating valve), i.e. at least one load sense [LS] pressure is derived from a work port load sense pressure but is not a work port pressure itself
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/20Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205Systems with pumps
    • F15B2211/2053Type of pump
    • F15B2211/20546Type of pump variable capacity
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/20Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/25Pressure control functions
    • F15B2211/253Pressure margin control, e.g. pump pressure in relation to load pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/305Directional control characterised by the type of valves
    • F15B2211/30525Directional control valves, e.g. 4/3-directional control valve
    • F15B2211/3053In combination with a pressure compensating valve
    • F15B2211/30535In combination with a pressure compensating valve the pressure compensating valve is arranged between pressure source and directional control valve
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/32Directional control characterised by the type of actuation
    • F15B2211/329Directional control characterised by the type of actuation actuated by fluid pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/50Pressure control
    • F15B2211/55Pressure control for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief valve
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/60Circuit components or control therefor
    • F15B2211/605Load sensing circuits
    • F15B2211/6051Load sensing circuits having valve means between output member and the load sensing circuit
    • F15B2211/6054Load sensing circuits having valve means between output member and the load sensing circuit using shuttle valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/60Circuit components or control therefor
    • F15B2211/65Methods of control of the load sensing pressure
    • F15B2211/651Methods of control of the load sensing pressure characterised by the way the load pressure is communicated to the load sensing circuit
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/60Circuit components or control therefor
    • F15B2211/65Methods of control of the load sensing pressure
    • F15B2211/654Methods of control of the load sensing pressure the load sensing pressure being lower than the load pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/70Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051Linear output members
    • F15B2211/7052Single-acting output members
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/70Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051Linear output members
    • F15B2211/7053Double-acting output members
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/70Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F15B2211/7135Combinations of output members of different types, e.g. single-acting cylinders with rotary motors
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/70Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/76Control of force or torque of the output member

Definitions

  • the invention relates to a hydraulic control device in load-sensing embodiment according to the preamble of patent claim 1.
  • a so-called load-compensated or load-sensing control device for controlling a plurality of hydraulic consumers is for example from DE 197 15 020 A1 and from the DE 102 45 836 A1 known.
  • the load pressure of the individual consumers is detected.
  • the highest detected load pressure is fed via a load pressure signaling line to a control element of the pressure medium source.
  • the pressure provided by the pressure medium source is thereby adjusted by a certain control pressure difference ⁇ p above the highest load pressure.
  • the speed of the individual consumers is controlled by adjustable metering orifices.
  • Individual pressure balances regulate the pressure difference across the metering orifices in each case to a constant value, so that the speed of the individual consumers can be controlled independently of their load pressure.
  • Such pressure compensators are also called LS pressure compensators.
  • the consumers controlled in this way are called LS consumers.
  • the respective individual pressure compensator is usually acted upon in the opening direction by the load pressure of the consumer, ie by the pressure downstream of the metering orifice, as well as by a control spring and in the closing direction by the pressure upstream of the metering orifice. If the consumer associated branch of the load pressure signaling line is provided with a pressure relief valve, the pressure of the pressure medium supplied to the consumer can be limited individually for each LS consumer. The individual pressure compensator then provides at its output at most a pressure that the opening pressure of the pressure relief valve plus the pressure equivalent of their control spring corresponds.
  • a priority valve usually takes the place of the individual pressure compensator which, in addition to the quantity of pressure medium supplied to the prioritized consumer, controls the quantity of pressure medium supplied to the subordinate consumers. Also via such a priority valve can be done in the manner described a pressure limit.
  • the hydraulic control device is designed in load-sensing technology and serves to control a first hydraulic consumer and a second hydraulic consumer.
  • the first consumer may be an LS consumer with upstream or downstream Individual pressure balance act. Be but it is also the case that it is a so-called LUDV consumer is (l ast u ntouche D urch Weg v grant), as further elaborated in the following description includes.
  • a first control valve for controlling the first hydraulic consumer and a second control valve for controlling the second hydraulic consumer are present.
  • a first load signal is detectable based on a load pressure applied to the first hydraulic load
  • a second load signal is detectable based on a load pressure applied to the second hydraulic load.
  • the first control valve and the second control valve pressure medium from a pressure medium source can be fed in parallel.
  • a load reporting path can be acted on to control an actuator assigned to the pressure medium source with a highest currently detected load signal.
  • a limiting device allows the limitation of the second load signal to a predetermined signal limit value.
  • a switching means is provided which can be controlled by the second load signal such that, at the latest when the second load signal reaches the signal limit value, the signal carried on the load signaling path is limited by the limiting device.
  • the first consumer pressure medium under a higher pressure than a maximum allowable limit load pressure of the second consumer is supplied. Only when the load pressure of the second consumer reaches a predetermined pressure limit, the load signal is limited to the load signaling path. In this case, the supply pressure provided by the pressure medium source is reliably lowered in accordance with the pressure limit value and the control pressure difference ⁇ p of the pressure medium source.
  • This overload protection according to the invention can be implemented both in purely hydraulic and in electrohydraulic load-sensing controllers.
  • a switching valve which fluidly connects a load pressure signaling line to a pressure limiting valve in an actuated switching position.
  • the switching pressure of the second load consumer is supplied as control pressure.
  • the pressure limitation is effected by influencing the control mechanism of the pressure medium source and not, as in the conventional case, by a arranged in the consumer supply valve.
  • the valves used according to the invention for pressure limiting, the switching valve and the pressure relief valve are invariably connected to control lines of small cross-section and can therefore be carried out inexpensively in a smaller nominal size.
  • the pressure limiting valve is arranged on a supply line from a load pressure signaling connection of the second control valve to the load pressure signaling line.
  • a pressure limiting valve is already provided in many hydraulic control blocks and allows a simple modification of existing series.
  • a preferred embodiment of the present invention is that the switching valve is designed as a seat valve, and that it has the function of a check valve opening to the load pressure signaling line in an unactuated shift position. In this way, the switching valve ensures that the load pressure of the second consumer is only reported to the load pressure signaling line, if this is the load pressurehighest consumer.
  • the switching valve thus replaces that in conventional constructions for this purpose used check valve and allows a compact and efficient design of the control device.
  • a required for actuation of the switching valve switching pressure corresponds at most to the opening pressure of the pressure relief valve.
  • the switching pressure of the switching valve is about 5 to 10 bar below the opening pressure of the pressure relief valve, one achieves a particularly reliable insertion of the pressure relief.
  • the first control valve comprises a load-holding valve. This ensures that, regardless of a pressure limit in the load-sensing line and a subsequently reduced supply pressure, no sagging of the first load is to be feared.
  • a hydraulic control device 1 is used to control at least two hydraulic consumers 15 and 30.
  • a pressure medium supply line 13 is supplied by a hydraulic pump 10 from a storage tank 12 with pressure medium.
  • the hydraulic pump 10 is an adjustable pump, the delivery rate of which is controlled by a pump regulator 11.
  • the pump regulator 11 is controlled by the pressure signal applied in a load pressure detection line 24. It ensures that at the output of the pump 10, a pressure is established, which is at a certain control pressure .DELTA.p above the load pressure signal.
  • the adjustable metering orifice 18 and the directional control valve 20 are both formed on the valve piston of a control valve.
  • the pressure compensator 16 is acted upon in the opening direction with the pressure downstream of the adjustable metering orifice 18 and with the force of a control spring. In the closing direction is at the control member of the pressure compensator 16, the pressure upstream of the metering orifice 18.
  • the pressure detected downstream of the metering orifice 18 corresponds to the load pressure of the consumer 15. This load pressure is supplied as a pressure signal via a shuttle valve 26 to the load pressure signaling line 24.
  • the shuttle valve 26 also allows load pressure signals of other consumers to lead to the load pressure signaling line 24. In this case, the load pressure signaling line 24 is acted upon by the highest of the detected load pressure signals.
  • the control line 24 is relieved via a flow control valve 25 to the storage tank 12 out.
  • the hydraulic consumer 30 is driven essentially via an adjustable metering orifice 32. This can be carried out together with a directional control valve on the valve piston of another control valve. At one Load pressure signaling connection 33, a load pressure signal of the consumer 30 can be detected. Usually, the load pressure signaling connection 33 is located on the control valve, which also forms the adjustable metering orifice 32. The load pressure signaling connection 33 is connected to a control line 34. The pressure on the control line 34 is limited by a pressure limiting valve 35. The control line 34 leads to a switching valve 36. A control member of the switching valve 36 is acted upon in the direction of an unactuated valve position by a spring 38.
  • the switching valve 36 In the direction of an actuated valve position, the switching valve 36 is acted upon by the load pressure signal of the load 30, which is brought by the control line 34 via a further control line 37 to it.
  • the switching valve 36 controls a connection between the control line 34 and the load pressure signaling line 24.
  • the switching valve 36 In the unactuated switching position, the switching valve 36 has the function of a load pressure signaling line 24 to open the check valve.
  • the switching valve 36 releases a fluidic connection between the control line 34 and the load pressure signaling line 24.
  • the control of the hydraulic consumer 15 corresponds to the conventional control of a consumer in a load-sensing system and is therefore not specifically explained. In the following, in particular, the mechanism of limiting the load 30 acting on the load will be discussed.
  • the opening pressure of the pressure limiting valve 35 corresponds to a pressure which is around the control pressure difference ⁇ p of the pump regulator 11 below the maximum permissible load pressure of the consumer 30.
  • the spring 38 of the switching valve 36 is dimensioned such that it corresponds to a switching pressure which is about 5 to 10 bar below the opening pressure of the pressure limiting valve 35.
  • the switching valve 36 is closed. In this state, either the load pressure of the consumer 15 or the check valve function of the switching valve 36, the load pressure of the consumer 30 is reported in the load pressure signaling line 24, depending on which load pressure is the higher. This can be in the load pressure signaling line 24 by the consumer 15th or by further consumers reported load pressure signal are well above the maximum allowable load pressure of the consumer 30. Accordingly, the supply pressure provided by the hydraulic pump 10 may also exceed the maximum allowable load pressure of the consumer 30. As long as the load 30 is subjected to a load resulting in a load pressure below its maximum allowable load pressure, the load 30 will not be overloaded.
  • the switching valve 36 releases a connection between the load pressure signaling line 24 and the control line 34 and in particular the pressure limiting valve 35.
  • the load pressure signal present in the load pressure signaling line 24 is limited to the opening pressure of the pressure limiting valve 35. Since the switching pressure of the switching valve 36 is about 5 to 10 bar below the opening pressure of the pressure relief valve 35, and the opening pressure in turn by about the control pressure difference Ap of the pump controller 11 is below the maximum allowable load pressure of the consumer 30, in this way an overload of the consumer 30th effectively prevented.
  • the load pressure signal is limited to the central load pressure signaling line 24 and thus the supply pressure available to all consumers. However, this occurs only when an overload of the consumer 30 threatens. In normal operation, the consumer 15 or further consumers can be operated at a pressure which is above the load pressure limit of the consumer 30.
  • the FIG. 2 shows a circuit diagram of a hydraulic control device 2.
  • the hydraulic control device 2 is a modification of the hydraulic control device 1, which differs from this only in the arrangement of the switching valve and the pressure relief valve and in the type of the switching valve. Components of the hydraulic control device 2, which correspond to those of the hydraulic control device 1, are provided with the same reference numerals and will not be described specifically.
  • the switching valve 44 in the case of the hydraulic control device 2, is fluidically connected to the load pressure signaling line 24 via a separate connecting line 45.
  • the switching valve 44, the pressure relief valve 48 is arranged downstream.
  • a control line 40 leads to the load pressure signaling line 24 via a check valve 42 opening toward the load pressure signaling line 24.
  • the load pressure signal of the consumer 30 is supplied via the control line 47 to an actuator of the switching valve 44 and acts on it in the opening direction. In the closing direction, the actuator of the switching valve 44 is acted upon by the spring 46.
  • an actuated switching position of the switching valve 44 there is a fluid connection between the load pressure signaling line 24 and the pressure limiting valve 48.
  • an unactuated switching position of the switching valve 44 the fluidic connection between the load pressure signaling line 24 and the pressure relief valve 48 is interrupted.
  • the opening pressure of the pressure relief valve 48 is set in accordance with the maximum allowable load pressure of the load 30.
  • the determined by the spring 46 switching pressure of the switching valve 44 is about 5 to 10 bar less than the opening pressure of the pressure relief valve 48th
  • the load pressure detected at the load pressure signaling connection 33 is reported to the load pressure signaling line 24 via the check valve 42 if no higher load pressure exists on the part of the further load.
  • the load pressure detected at the terminal 33 is applied to the switching valve 44 via the control line 47.
  • this load pressure signal reaches the opening pressure of the switching valve 44, the switching valve 44 releases the connection between the load pressure signaling line 24 and the pressure limiting valve 48.
  • the load pressure signal guided on the load pressure signaling line 24 is limited to the opening pressure of the pressure limiting valve 48.
  • the function of the hydraulic control device 2 thus corresponds to the function of the hydraulic control device 1 with regard to the overload protection for the load 30.
  • the connection of the switching valve 44 to the load pressure signaling line 24 via a separate control line 45 allows a greater flexibility in the arrangement of the switching valve 44 and the pressure relief valve 48. In addition, a simply constructed switching valve can be used.
  • FIG. 3 is with the hydraulic control device 3, a further modification of in FIG. 1 shown hydraulic control device 1 shown. Again, the same components are provided with the same reference numerals and are not specifically explained.
  • the speed of the consumer 15 is controlled via a metering orifice 52. Downstream of the metering orifice 52, a pressure compensator 54 is arranged. In the fluid path from the pump 10 to the consumer 15 are further a load-holding valve 64 and the directional control valve 20.
  • the pressure compensator 54 has a control piston 57. By the control piston 57 performs a control line 58 into a back space 55 of the pressure compensator 54. In the control line 58 is a check valve 59 opening towards the rear space 55 is arranged.
  • the rear space 55 is in fluid communication with a load pressure signaling line 50.
  • a spring 56 is arranged in the rear space 55, which acts on the control piston 57.
  • Further consumers are supplied via similarly constructed pressure compensators 62 with pressure medium.
  • a steering unit 70 is supplied via the supply line 13.
  • the steering unit 70 controls via terminals 78 and 79 to / the steering cylinder of a vehicle.
  • the main component of the steering unit 70 is a rotor set 72, via which the terminals 78 and 79 supplied amount of pressure medium is controlled.
  • a load pressure signal is passed to the outside. This load pressure signal is limited within the steering unit 70 by a pressure relief valve 74.
  • the load pressure signal present at the load pressure signaling connection 76 is conducted via the control line 77 to the switching valve 36. Via the control line 37, an actuator of the switching valve 36 is acted upon by this load pressure signal.
  • the pressure compensator 54 regulates the pressure downstream of the metering orifice 52 to a value which is about the pressure equivalent of the force of the spring 56 above the load pressure signal, which is present in its rear space 55.
  • Spring 56 designed quite weak, so that the pressure between the metering orifice 52 and the pressure compensator 54 is only slightly above the pending in the pressure chamber 55 load pressure signal.
  • This load pressure signal corresponds to the highest load pressure of the connected consumers.
  • the back rooms of further pressure compensators 62, etc., as well as the pressure chamber 55 are acted upon by the load pressure signal carried in the load pressure signaling line 50.
  • the pressure upstream of the metering orifice 52 corresponds to the supply pressure provided by the hydraulic pump 10.
  • the steering unit 70 is supplied via the supply line 13 from the pump 10.
  • the present at the output 76 of the steering unit 70 load pressure signal is supplied via the switching valve 36, which has the function of a check valve in the unactuated position, the load pressure signaling line 50.
  • the load-holding valve 64 is arranged in the supply line of the consumer 15.
  • the overload protection mechanisms described with reference to the hydraulic control devices 1, 2 and 3 can also be implemented in the electronic control unit of an electro-hydraulic control device.
  • the load-signaling path in the sense of claim 1 is implemented as a load-pressure-signaling line, the limiting device as a pressure-limiting valve, and the switching means as a switching valve.

Description

Die Erfindung betrifft eine hydraulische Steuervorrichtung in load-sensing Ausführung gemäß dem Oberbegriff des Patentanspruchs 1.The invention relates to a hydraulic control device in load-sensing embodiment according to the preamble of patent claim 1.

Eine so genannte lastkompensierte oder load-sensing Steuervorrichtung zur Ansteuerung mehrerer hydraulischer Verbraucher ist z.B. aus der DE 197 15 020 A1 und aus der DE 102 45 836 A1 bekannt. Bei einer solchen Steuervorrichtung wird der Lastdruck der einzelnen Verbraucher erfasst. Der höchste erfasste Lastdruck wird über eine Lastdruckmeldeleitung einem Regelglied der Druckmittelquelle zugeführt. Der von der Druckmittelquelle bereitgestellte Druck wird dadurch um eine bestimmte Regeldruckdifferenz Δp über dem höchsten Lastdruck eingeregelt. Die Geschwindigkeit der einzelnen Verbraucher wird über verstellbare Zumessblenden gesteuert. Individualdruckwaagen regeln die Druckdifferenz über den Zumessblenden jeweils auf einen konstanten Wert, so dass die Geschwindigkeit der einzelnen Verbraucher unabhängig von ihrem Lastdruck steuerbar ist. Solche Druckwaagen werden auch LS-Druckwaagen genannt. Die auf diese Weise angesteuerten Verbraucher werden als LS-Verbraucher bezeichnet.A so-called load-compensated or load-sensing control device for controlling a plurality of hydraulic consumers is for example from DE 197 15 020 A1 and from the DE 102 45 836 A1 known. In such a control device, the load pressure of the individual consumers is detected. The highest detected load pressure is fed via a load pressure signaling line to a control element of the pressure medium source. The pressure provided by the pressure medium source is thereby adjusted by a certain control pressure difference Δp above the highest load pressure. The speed of the individual consumers is controlled by adjustable metering orifices. Individual pressure balances regulate the pressure difference across the metering orifices in each case to a constant value, so that the speed of the individual consumers can be controlled independently of their load pressure. Such pressure compensators are also called LS pressure compensators. The consumers controlled in this way are called LS consumers.

Eine weitere hydraulische Steuervorrichtung gemäß dem Oberbegriff des Anspruchs 1 ist aus der DE 4417962 A1 bekannt.Another hydraulic control device according to the preamble of claim 1 is known from DE 4417962 A1 known.

Die jeweilige Individualdruckwaage ist üblicherweise in Öffnungsrichtung von dem Lastdruck des Verbrauchers, d.h. von dem Druck stromab der Zumessblende, sowie von einer Regelfeder und in Schließrichtung von dem Druck stromauf der Zumessblende beaufschlagt. Wenn der dem Verbraucher zugeordnete Zweig der Lastdruckmeldeleitung mit einem Druckbegrenzungsventil versehen wird, lässt sich der Druck des dem Verbraucher zugeführten Druckmittels individuell für jeden LS-Verbraucher begrenzen. Die Individualdruckwaage stellt dann an ihrem Ausgang höchstens einen Druck bereit, der dem Öffnungsdruck des Druckbegrenzungsventils zuzüglich dem Druckäquivalent ihrer Regelfeder entspricht. Soll der Verbraucher gegenüber anderen Verbrauchern priorisiert werden, wie z.B. bei einem Lenkaggregat, tritt an die Stelle der Individualdruckwaage üblicherweise ein Prioritätsventil, das zusätzlich zu der dem priorisierten Verbraucher zugeführten Druckmittelmenge die den nachrangigen Verbrauchern zugeführte Druckmittelmenge steuert. Auch über ein solches Prioritätsventil kann in der beschriebenen Weise eine Druckbegrenzung erfolgen.The respective individual pressure compensator is usually acted upon in the opening direction by the load pressure of the consumer, ie by the pressure downstream of the metering orifice, as well as by a control spring and in the closing direction by the pressure upstream of the metering orifice. If the consumer associated branch of the load pressure signaling line is provided with a pressure relief valve, the pressure of the pressure medium supplied to the consumer can be limited individually for each LS consumer. The individual pressure compensator then provides at its output at most a pressure that the opening pressure of the pressure relief valve plus the pressure equivalent of their control spring corresponds. If the consumer is to be prioritized over other consumers, such as in a steering unit, a priority valve usually takes the place of the individual pressure compensator which, in addition to the quantity of pressure medium supplied to the prioritized consumer, controls the quantity of pressure medium supplied to the subordinate consumers. Also via such a priority valve can be done in the manner described a pressure limit.

Will man jedoch einen Hydromotor, für den eine genaue Geschwindigkeitssteuerung nicht erforderlich ist, an eine solche Steuervorrichtung anschließen, ist es aus Kostengründen wünschenswert, auf eine Individualdruckwaage verzichten zu können. Auch bei Verbrauchern, deren Druckmittelmenge nicht über eine Zumessblende gesteuert ist, z.B. bei einem mittels eines Rotorsatzes gesteuerten Lenkaggregat, ist eine Individualdruckwaage bzw. ein Prioritätsventil zumindest zur Mengenregulierung nicht erforderlich. Daher ist es wünschenswert, die Beaufschlagung eines Verbrauches mit Druck auf andere Weise als durch das Zusammenwirken eines Druckbegrenzungsventils und einer Individualdruckwaage begrenzen zu können.However, if you want to connect a hydraulic motor, for which an accurate speed control is not required, to such a control device, it is desirable for cost reasons to be able to do without an individual pressure compensator. Even with consumers whose pressure medium is not controlled via a metering orifice, e.g. in a steering unit controlled by means of a rotor set, an individual pressure balance or a priority valve is not required, at least for volume control. Therefore, it is desirable to be able to limit the application of pressure to other than by the interaction of a pressure relief valve and an individual pressure compensator.

Den Druck in einer Zulaufleitung des Verbrauchers durch ein Druckbegrenzungsventil direkt zu begrenzen ist jedoch aufgrund der dazu benötigten Ventilgröße aufwendig und ineffizient. Außerdem wäre dadurch eine ständige Druckbegrenzung für alle Verbraucher gegeben.However, to limit the pressure in a supply line of the consumer directly by a pressure relief valve is complicated and inefficient due to the required valve size. In addition, this would provide a permanent pressure limit for all consumers.

Es ist die Aufgabe der vorliegenden Erfindung eine verbesserte hydraulische Steuervorrichtung anzugeben, die eine einfache und effiziente Begrenzung der Druckbeaufschlagung eines Verbrauchers erlaubt.It is the object of the present invention to provide an improved hydraulic control device which allows a simple and efficient limitation of the pressurization of a consumer.

Diese Aufgabe wird erfindungsgemäß durch eine hydraulische Steuervorrichtung mit den Merkmalen des Patentanspruchs 1 gelöst.This object is achieved by a hydraulic control device with the features of claim 1.

Die erfindungsgemäße hydraulische Steuervorrichtung ist in load-sensing Technik ausgeführt und dient der Ansteuerung eines ersten hydraulischen Verbrauchers und eines zweiten hydraulischen Verbrauchers. Bei dem ersten Verbraucher kann es sich um einen LS-Verbraucher mit vor- oder nachgeschalteter Individualdruckwaage handeln. Es soll aber auch der Fall, dass es sich um einen so genannten LUDV-Verbraucher (lastunabhängige Durchflussverteilung) handelt, wie in der nachfolgenden Beschreibung näher ausgeführt, umfasst sein. Des Weiteren sind ein erstes Steuerventil zur Ansteuerung des ersten hydraulischen Verbrauchers und ein zweites Steuerventil zur Ansteuerung des zweiten hydraulischen Verbrauchers vorhanden. Ein erstes Lastsignal ist auf der Grundlage eines Lastdrucks, mit dem der erste hydraulische Verbraucher beaufschlagt ist, und ein zweites Lastsignal ist auf der Grundlage eines Lastdrucks, mit dem der zweite hydraulische Verbraucher beaufschlagt ist, erfassbar. Dem ersten Steuerventil und dem zweiten Steuerventil ist Druckmittel von einer Druckmittelquelle parallel zuführbar. Ein Lastmeldepfad ist zur Ansteuerung eines der Druckmittelquelle zugeordneten Stellorgans mit einem höchsten gegenwärtig erfassten Lastsignal beaufschlagbar. Eine Begrenzungsvorrichtung erlaubt die Begrenzung des zweiten Lastsignals auf einen vorgegebenen Signalgrenzwert.The hydraulic control device according to the invention is designed in load-sensing technology and serves to control a first hydraulic consumer and a second hydraulic consumer. The first consumer may be an LS consumer with upstream or downstream Individual pressure balance act. Be but it is also the case that it is a so-called LUDV consumer is (l ast u nabhängige D urchfluss v grant), as further elaborated in the following description includes. Furthermore, a first control valve for controlling the first hydraulic consumer and a second control valve for controlling the second hydraulic consumer are present. A first load signal is detectable based on a load pressure applied to the first hydraulic load, and a second load signal is detectable based on a load pressure applied to the second hydraulic load. The first control valve and the second control valve pressure medium from a pressure medium source can be fed in parallel. A load reporting path can be acted on to control an actuator assigned to the pressure medium source with a highest currently detected load signal. A limiting device allows the limitation of the second load signal to a predetermined signal limit value.

Es ist die Besonderheit der vorliegenden Erfindung, dass ein Schaltmittel vorgesehen ist, welches durch das zweite Lastsignal so ansteuerbar ist, dass, spätestens wenn das zweite Lastsignal den Signalgrenzwert erreicht, das auf dem Lastmeldepfad geführte Signal durch die Begrenzungsvorrichtung begrenzt wird.It is the peculiarity of the present invention that a switching means is provided which can be controlled by the second load signal such that, at the latest when the second load signal reaches the signal limit value, the signal carried on the load signaling path is limited by the limiting device.

Auf diese Weise wird eine einfache und effiziente Begrenzung der Druckbelastung des zweiten Verbrauchers erzielt. So wird es möglich, einen weniger druckfesten Verbraucher zusammen mit höher belastbaren Verbrauchern im gleichen hydraulischen Steuerkreis zu betreiben. Insbesondere kann dem ersten Verbraucher Druckmittel unter einem höherem Druck, als ein maximal zulässiger Grenzlastdruck des zweiten Verbrauchers beträgt, zugeführt werden. Nur wenn der Lastdruck des zweiten Verbrauchers einen vorgegebenen Druckgrenzwert erreicht, wird das Lastsignal auf dem Lastmeldepfad begrenzt. In diesem Fall wird der von der Druckmittelquelle bereitgestellte Versorgungsdruck zuverlässig entsprechend dem Druckgrenzwert und der Regeldruckdifferenz Δp der Druckmittelquelle abgesenkt. Diese nur bedarfsweise aktivierte Begrenzung des Lastsignals auf dem Lastmeldepfad erlaubt also unter normalen Betriebsbedingungen einen uneingeschränkten Betrieb der hydraulischen Verbraucher und sichert im Fall einer drohenden Überlastung eines Verbrauchers diesen zuverlässig ab. Dieser erfindungsgemäße Überlastungsschutz ist sowohl bei rein hydraulischen als auch bei elektrohydraulischen load-sensing Steuerungen implementierbar.In this way, a simple and efficient limitation of the pressure load of the second consumer is achieved. This makes it possible to operate a less pressure-resistant consumer together with higher-load consumers in the same hydraulic control circuit. In particular, the first consumer pressure medium under a higher pressure than a maximum allowable limit load pressure of the second consumer is supplied. Only when the load pressure of the second consumer reaches a predetermined pressure limit, the load signal is limited to the load signaling path. In this case, the supply pressure provided by the pressure medium source is reliably lowered in accordance with the pressure limit value and the control pressure difference Δp of the pressure medium source. This only activated as needed limitation of the load signal on the Lastmeldepfad thus allows Under normal operating conditions unrestricted operation of the hydraulic consumers and secures in the case of imminent overload of a consumer this reliable. This overload protection according to the invention can be implemented both in purely hydraulic and in electrohydraulic load-sensing controllers.

Weitere vorteilhafte Ausgestaltungen sind in den Unteransprüchen angegeben.Further advantageous embodiments are specified in the subclaims.

Gemäß einer besonders bevorzugten Weiterbildung der vorliegenden Erfindung ist ein Schaltventil vorgesehen, das in einer betätigten Schaltstellung eine Lastdruckmeldeleitung mit einem Druckbegrenzungsventil fluidisch verbindet. Dabei ist dem Schaltventil der Lastdruck des zweiten Verbrauchers als Steuerdruck zugeführt. Ein solches Schaltventil lässt sich auf einfache Weise in herkömmliche Konstruktionen von Steueranordnungen integrieren. Zudem erfolgt die Druckbegrenzung durch Beeinflussung des Regelmechanismus der Druckmittelquelle und nicht, wie im herkömmlichen Fall, durch ein in der Verbraucherzuleitung angeordnetes Ventil. Die erfindungsgemäß zur Druckbegrenzung verwendeten Ventile, das Schaltventil und das Druckbegrenzungsventil, sind ausnahmslos an Steuerleitungen kleinen Querschnitts angeschlossen und können daher kostengünstig in kleiner Nenngröße ausgeführt werden.According to a particularly preferred development of the present invention, a switching valve is provided which fluidly connects a load pressure signaling line to a pressure limiting valve in an actuated switching position. In this case, the switching pressure of the second load consumer is supplied as control pressure. Such a switching valve can be easily integrated into conventional constructions of control arrangements. In addition, the pressure limitation is effected by influencing the control mechanism of the pressure medium source and not, as in the conventional case, by a arranged in the consumer supply valve. The valves used according to the invention for pressure limiting, the switching valve and the pressure relief valve are invariably connected to control lines of small cross-section and can therefore be carried out inexpensively in a smaller nominal size.

Vorzugsweise ist das Druckbegrenzungsventil an einer Zuleitung von einem Lastdruckmeldeanschluss des zweiten Steuerventils zur Lastdruckmeldeleitung angeordnet. Eine solche Anordnung eines Druckbegrenzungsventils ist bei vielen Hydrauliksteuerblöcken schon vorgesehen und erlaubt eine einfache Modifikation bestehender Baureihen.Preferably, the pressure limiting valve is arranged on a supply line from a load pressure signaling connection of the second control valve to the load pressure signaling line. Such an arrangement of a pressure limiting valve is already provided in many hydraulic control blocks and allows a simple modification of existing series.

Eine bevorzugte Ausbildung der vorliegenden Erfindung besteht darin, dass das Schaltventil als Sitzventil ausgebildet ist, und dass es in einer unbetätigten Schaltstellung die Funktion eines zur Lastdruckmeldeleitung hin öffnenden Rückschlagventils besitzt. Auf diese Weise sorgt das Schaltventil dafür, dass der Lastdruck des zweiten Verbrauchers nur dann an die Lastdruckmeldeleitung gemeldet wird, wenn dies der lastdruckhöchste Verbraucher ist. Das Schaltventil ersetzt somit das in herkömmlichen Konstruktionen für diesen Zweck verwendete Rückschlagventil und ermöglicht eine kompakte und effiziente Bauweise der Steuervorrichtung.A preferred embodiment of the present invention is that the switching valve is designed as a seat valve, and that it has the function of a check valve opening to the load pressure signaling line in an unactuated shift position. In this way, the switching valve ensures that the load pressure of the second consumer is only reported to the load pressure signaling line, if this is the load pressurehighest consumer. The switching valve thus replaces that in conventional constructions for this purpose used check valve and allows a compact and efficient design of the control device.

Vorzugsweise entspricht ein zur Betätigung des Schaltventils benötigter Schaltdruck höchstens dem Öffnungsdruck des Druckbegrenzungsventils. Dadurch wird bei drohender Überlastung des zweiten Verbrauchers der Druck in der Lastmeldeleitung sicher auf den Öffnungsdruck des Druckbegrenzungsventils begrenzt.Preferably, a required for actuation of the switching valve switching pressure corresponds at most to the opening pressure of the pressure relief valve. As a result, in the event of imminent overloading of the second consumer, the pressure in the load-sensing line is reliably limited to the opening pressure of the pressure-limiting valve.

Wenn der Schaltdruck des Schaltventils um etwa 5 bis 10 bar unter dem Öffnungsdruck des Druckbegrenzungsventils liegt, erzielt man ein besonders zuverlässiges Einsetzen der Druckbegrenzung.If the switching pressure of the switching valve is about 5 to 10 bar below the opening pressure of the pressure relief valve, one achieves a particularly reliable insertion of the pressure relief.

Vorzugsweise umfasst das erste Steuerventil ein Lasthalteventil. Dadurch ist sichergestellt, dass unabhängig von einer Druckbegrenzung in der Lastmeldeleitung und einem daraufhin reduzierten Versorgungsdruck kein Absacken des ersten Verbrauchers zu befürchten ist.Preferably, the first control valve comprises a load-holding valve. This ensures that, regardless of a pressure limit in the load-sensing line and a subsequently reduced supply pressure, no sagging of the first load is to be feared.

Nachfolgend werden die vorliegende Erfindung und deren Vorteile unter Bezugnahme auf die in den Figuren dargestellten Ausführungsbeispiele näher erläutert.Hereinafter, the present invention and its advantages will be explained with reference to the embodiments illustrated in the figures.

Es zeigen:

Fig. 1
ein Schaltbild einer hydraulischen Steueranordnung für einen Verbraucher, in dessen Zuleitung eine Individualdruckwaage ange- ordnet ist, und für einen weiteren Verbraucher, mit dessen Lastdrucksignal ein Schaltventil angesteuert wird, welches eine Ver- bindung zwischen einem den Lastdruck des weiteren Verbrauchers begrenzenden Druckbegrenzungsventil und einer Lastdruckmeldelei- tung steuert,
Fig. 2
eine Abwandlung der in Fig. 1 dargestellten Schaltung mit einer alternativen Anordnung eines Schaltventils und des Druckbegren- zungsventils, bei der das Druckbegrenzungsventil nicht unmittelbar an einen Lastmeldeanschluss des ersten Verbrauchers angeschlossen ist, und
Fig. 3
eine Abwandlung der in Fig. 1 dargestellten Schaltung, nach der mehrere Verbraucher im Sinne einer LUDV-Steuerung ansteuerbar sind und nach der als weiterer Verbraucher ein Lenkaggregat vorge- sehen ist, mit dessen Lastdrucksignal das Schaltventil angesteuert wird.
Show it:
Fig. 1
a circuit diagram of a hydraulic control arrangement for a consumer, in whose supply line an individual pressure compensator is arranged, and for a further consumer, with the load pressure signal, a switching valve is controlled, which is a connection between a the load pressure of the other consumer limiting pressure relief valve and a Lastdruckmeldelei - controls,
Fig. 2
a modification of the in Fig. 1 illustrated circuit with an alternative arrangement of a switching valve and the Druckbegren- tion valve, wherein the pressure relief valve is not directly connected to a load-sensing connection of the first consumer, and
Fig. 3
a modification of the in Fig. 1 shown circuit, according to the several consumers in the sense of a LUDV control can be controlled and according to the further consumer as a steering unit is provided seen, with the load pressure signal, the switching valve is controlled.

Gemäß Figur 1 dient eine hydraulische Steuervorrichtung 1 der Ansteuerung zumindest zweier hydraulischer Verbraucher 15 und 30. Eine Druckmittelzuleitung 13 wird von einer Hydropumpe 10 aus einem Vorratstank 12 mit Druckmittel versorgt. Bei der Hydropumpe 10 handelt es sich um eine verstellbare Pumpe, deren Fördermenge über einen Pumpenregler 11 gesteuert wird. Der Pumpenregler 11 wird durch das in einer Lastdruckmeldeleitung 24 anstehende Drucksignal gesteuert. Er sorgt dafür, dass sich am Ausgang der Pumpe 10 ein Druck einstellt, der um einen bestimmten Regeldruck Δp über dem Lastdrucksignal liegt.According to FIG. 1 a hydraulic control device 1 is used to control at least two hydraulic consumers 15 and 30. A pressure medium supply line 13 is supplied by a hydraulic pump 10 from a storage tank 12 with pressure medium. The hydraulic pump 10 is an adjustable pump, the delivery rate of which is controlled by a pump regulator 11. The pump regulator 11 is controlled by the pressure signal applied in a load pressure detection line 24. It ensures that at the output of the pump 10, a pressure is established, which is at a certain control pressure .DELTA.p above the load pressure signal.

Die Ansteuerung des hydraulischen Verbrauchers 15 erfolgt über eine Individualdruckwaage 16, eine verstellbare Zumessblende 18 und ein Wegeventil 20. Üblicherweise sind die verstellbare Zumessblende 18 und das Wegeventil 20 beide am Ventilkolben eines Steuerventils gebildet. Die Druckwaage 16 ist in Öffnungsrichtung mit dem Druck stromab der verstellbaren Zumessblende 18 und mit der Kraft einer Regelfeder beaufschlagt. In Schließrichtung steht am Steuerglied der Druckwaage 16 der Druck stromauf der Zumessblende 18 an. Der stromab der Zumessblende 18 erfasste Druck entspricht dem Lastdruck des Verbrauchers 15. Dieser Lastdruck wird als Drucksignal über ein Wechselventil 26 der Lastdruckmeldeleitung 24 zugeführt. Das Wechselventil 26 erlaubt es, auch Lastdrucksignale weiterer Verbraucher auf die Lastdruckmeldeleitung 24 zu führen. Dabei wird die Lastdruckmeldeleitung 24 mit dem höchsten der erfassten Lastdrucksignale beaufschlagt. Die Steuerleitung 24 ist über ein Stromregelventil 25 zum Vorratstank 12 hin entlastbar.The control of the hydraulic load 15 via an individual pressure compensator 16, an adjustable metering orifice 18 and a directional control valve 20. Usually, the adjustable metering orifice 18 and the directional control valve 20 are both formed on the valve piston of a control valve. The pressure compensator 16 is acted upon in the opening direction with the pressure downstream of the adjustable metering orifice 18 and with the force of a control spring. In the closing direction is at the control member of the pressure compensator 16, the pressure upstream of the metering orifice 18. The pressure detected downstream of the metering orifice 18 corresponds to the load pressure of the consumer 15. This load pressure is supplied as a pressure signal via a shuttle valve 26 to the load pressure signaling line 24. The shuttle valve 26 also allows load pressure signals of other consumers to lead to the load pressure signaling line 24. In this case, the load pressure signaling line 24 is acted upon by the highest of the detected load pressure signals. The control line 24 is relieved via a flow control valve 25 to the storage tank 12 out.

Der hydraulische Verbraucher 30 wird im Wesentlichen über eine verstellbare Zumessblende 32 angesteuert. Diese kann zusammen mit einem Wegeventil am Ventilkolben eines weiteren Steuerventils ausgeführt sein. An einem Lastdruckmeldeanschluss 33 ist ein Lastdrucksignal des Verbrauchers 30 erfassbar. Üblicherweise befindet sich der Lastdruckmeldeanschluss 33 an dem Steuerventil, das auch die verstellbare Zumessblende 32 bildet. Der Lastdruckmeldeanschluss 33 ist mit einer Steuerleitung 34 verbunden. Der Druck auf der Steuerleitung 34 ist durch ein Druckbegrenzungsventil 35 begrenzt. Die Steuerleitung 34 führt zu einem Schaltventil 36. Ein Steuerglied des Schaltventils 36 ist in Richtung einer unbetätigten Ventilstellung durch eine Feder 38 beaufschlagt. In Richtung einer betätigten Ventilstellung ist das Schaltventil 36 durch das Lastdrucksignal des Verbrauchers 30 beaufschlagt, das von der Steuerleitung 34 über eine weitere Steuerleitung 37 an es herangeführt wird. Das Schaltventil 36 steuert eine Verbindung zwischen der Steuerleitung 34 und der Lastdruckmeldeleitung 24. In der unbetätigten Schaltstellung besitzt das Schaltventil 36 die Funktion eines zur Lastdruckmeldeleitung 24 hin öffnenden Rückschlagventils. In der betätigten Schaltstellung gibt das Schaltventil 36 eine fluidische Verbindung zwischen der Steuerleitung 34 und der Lastdruckmeldeleitung 24 frei.The hydraulic consumer 30 is driven essentially via an adjustable metering orifice 32. This can be carried out together with a directional control valve on the valve piston of another control valve. At one Load pressure signaling connection 33, a load pressure signal of the consumer 30 can be detected. Usually, the load pressure signaling connection 33 is located on the control valve, which also forms the adjustable metering orifice 32. The load pressure signaling connection 33 is connected to a control line 34. The pressure on the control line 34 is limited by a pressure limiting valve 35. The control line 34 leads to a switching valve 36. A control member of the switching valve 36 is acted upon in the direction of an unactuated valve position by a spring 38. In the direction of an actuated valve position, the switching valve 36 is acted upon by the load pressure signal of the load 30, which is brought by the control line 34 via a further control line 37 to it. The switching valve 36 controls a connection between the control line 34 and the load pressure signaling line 24. In the unactuated switching position, the switching valve 36 has the function of a load pressure signaling line 24 to open the check valve. In the actuated switching position, the switching valve 36 releases a fluidic connection between the control line 34 and the load pressure signaling line 24.

Die Ansteuerung des hydraulischen Verbrauchers 15 entspricht der herkömmlichen Ansteuerung eines Verbrauchers in einem load-sensing System und wird daher nicht eigens erläutert. Im Folgenden wird vor allem auf den Mechanismus der Begrenzung des den Verbraucher 30 beaufschlagenden Lastdrucks eingegangen. Der Öffnungsdruck des Druckbegrenzungsventils 35 entspricht einem Druck, der um die Regeldruckdififerenz Δp des Pumpenreglers 11 unter dem maximal zulässigen Lastdruck des Verbrauchers 30 liegt. Die Feder 38 des Schaltventils 36 ist so bemessen, dass sie einem Schaltdruck entspricht, der um etwa 5 bis 10 bar unter dem Öffnungsdruck des Druckbegrenzungsventils 35 liegt.The control of the hydraulic consumer 15 corresponds to the conventional control of a consumer in a load-sensing system and is therefore not specifically explained. In the following, in particular, the mechanism of limiting the load 30 acting on the load will be discussed. The opening pressure of the pressure limiting valve 35 corresponds to a pressure which is around the control pressure difference Δp of the pump regulator 11 below the maximum permissible load pressure of the consumer 30. The spring 38 of the switching valve 36 is dimensioned such that it corresponds to a switching pressure which is about 5 to 10 bar below the opening pressure of the pressure limiting valve 35.

Solange der Lastdruck des Verbrauchers 30 unter dem Schaltdruck des Schaltventils 36 liegt, ist das Schaltventil 36 geschlossen. In diesem Zustand wird in die Lastdruckmeldeleitung 24 entweder der Lastdruck des Verbrauchers 15 oder über die Rückschlagventilfunktion des Schaltventils 36 der Lastdruck des Verbrauchers 30 gemeldet, je nachdem, welcher Lastdruck der höhere ist. Dabei kann das in die Lastdruckmeldeleitung 24 durch den Verbraucher 15 oder durch weitere Verbraucher gemeldete Lastdrucksignal durchaus über dem maximal zulässigen Lastdruck des Verbrauchers 30 liegen. Dementsprechend übersteigt auch der von der Hydropumpe 10 bereit gestellte Versorgungsdruck möglicherweise den maximal zulässigen Lastdruck des Verbrauchers 30. Solange der Verbraucher 30 mit einer Last beaufschlagt ist, die einen Lastdruck unterhalb seines maximal zulässigen Lastdrucks zur Folge hat, wird der Verbraucher 30 jedoch nicht überlastet.As long as the load pressure of the consumer 30 is below the switching pressure of the switching valve 36, the switching valve 36 is closed. In this state, either the load pressure of the consumer 15 or the check valve function of the switching valve 36, the load pressure of the consumer 30 is reported in the load pressure signaling line 24, depending on which load pressure is the higher. This can be in the load pressure signaling line 24 by the consumer 15th or by further consumers reported load pressure signal are well above the maximum allowable load pressure of the consumer 30. Accordingly, the supply pressure provided by the hydraulic pump 10 may also exceed the maximum allowable load pressure of the consumer 30. As long as the load 30 is subjected to a load resulting in a load pressure below its maximum allowable load pressure, the load 30 will not be overloaded.

Sobald das Lastdrucksignal des Verbrauchers 30 den Schaltdruck des Schaltventils 36 überschreitet, gibt das Schaltventil 36 eine Verbindung zwischen den Lastdruckmeldeleitung 24 und der Steuerleitung 34 sowie insbesondere dem Druckbegrenzungsventil 35 frei. Dadurch wird das in der Lastdruckmeldeleitung 24 anstehende Lastdrucksignal auf den Öffnungsdruck des Druckbegrenzungsventils 35 begrenzt. Da der Schaltdruck des Schaltventils 36 etwa 5 bis 10 bar unter dem Öffnungsdruck des Druckbegrenzungsventils 35 liegt, und der Öffnungsdruck wiederum um etwa die Regeldruckdifferenz Δp des Pumpenreglers 11 unter dem maximal zulässigen Lastdruck des Verbrauchers 30 liegt, wird auf diese Weise eine Überlastung des Verbrauchers 30 wirkungsvoll verhindert.As soon as the load pressure signal of the consumer 30 exceeds the switching pressure of the switching valve 36, the switching valve 36 releases a connection between the load pressure signaling line 24 and the control line 34 and in particular the pressure limiting valve 35. As a result, the load pressure signal present in the load pressure signaling line 24 is limited to the opening pressure of the pressure limiting valve 35. Since the switching pressure of the switching valve 36 is about 5 to 10 bar below the opening pressure of the pressure relief valve 35, and the opening pressure in turn by about the control pressure difference Ap of the pump controller 11 is below the maximum allowable load pressure of the consumer 30, in this way an overload of the consumer 30th effectively prevented.

Bei Betätigung des Schaltventils 36 wird also das Lastdrucksignal auf der zentralen Lastdruckmeldeleitung 24 und somit der allen Verbrauchern zur Verfügung stehende Versorgungsdruck begrenzt. Dies tritt allerdings nur dann auf, wenn eine Überlastung des Verbrauchers 30 droht. Im Normalbetrieb können der Verbraucher 15 bzw. weitere Verbraucher mit einem Druck betrieben werden, der über der Lastdruckgrenze des Verbrauchers 30 liegt.Upon actuation of the switching valve 36 so the load pressure signal is limited to the central load pressure signaling line 24 and thus the supply pressure available to all consumers. However, this occurs only when an overload of the consumer 30 threatens. In normal operation, the consumer 15 or further consumers can be operated at a pressure which is above the load pressure limit of the consumer 30.

Die Figur 2 zeigt ein Schaltbild einer hydraulischen Steuervorrichtung 2. Die hydraulische Steuervorrichtung 2 ist eine Abwandlung der hydraulischen Steuervorrichtung 1, die sich von dieser lediglich in der Anordnung des Schaltventils und des Druckbegrenzungsventils sowie in der Art des Schaltventils unterscheidet. Bestandteile der hydraulischen Steuervorrichtung 2, die denen der hydraulischen Steuervorrichtung 1 entsprechen, sind mit gleichen Bezugszeichen versehen und werden nicht mehr eigens beschrieben. Im Unterschied zur hydraulischen Steuervorrichtung 1 ist bei der hydraulischen Steuervorrichtung 2 das Schaltventil 44 über eine separate Verbindungsleitung 45 mit der Lastdruckmeldeleitung 24 fluidisch verbunden. Dem Schaltventil 44 ist das Druckbegrenzungsventil 48 nachgeordnet. Vom Lastdruckmeldeanschluss 33 des Verbrauchers 30 oder eines Steuerventils führt eine Steuerleitung 40 über ein zur Lastdruckmeldeleitung 24 hin öffnendes Rückschlagventil 42 zur Lastdruckmeldeleitung 24. Das Lastdrucksignal des Verbrauchers 30 ist über die Steuerleitung 47 einem Stellglied des Schaltventils 44 zugeführt und beaufschlagt dieses in Öffnungsrichtung. In Schließrichtung ist das Stellglied des Schaltventils 44 von der Feder 46 beaufschlagt. In einer betätigten Schaltstellung des Schaltventils 44 besteht eine fluidische Verbindung zwischen der Lastdruckmeldeleitung 24 und dem Druckbegrenzungsventil 48. In einer unbetätigten Schaltstellung des Schaltventils 44 ist die fluidische Verbindung zwischen der Lastdruckmeldeleitung 24 und dem Druckbegrenzungsventil 48 unterbrochen.The FIG. 2 shows a circuit diagram of a hydraulic control device 2. The hydraulic control device 2 is a modification of the hydraulic control device 1, which differs from this only in the arrangement of the switching valve and the pressure relief valve and in the type of the switching valve. Components of the hydraulic control device 2, which correspond to those of the hydraulic control device 1, are provided with the same reference numerals and will not be described specifically. in the In contrast to the hydraulic control device 1, in the case of the hydraulic control device 2, the switching valve 44 is fluidically connected to the load pressure signaling line 24 via a separate connecting line 45. The switching valve 44, the pressure relief valve 48 is arranged downstream. From the load pressure signaling connection 33 of the consumer 30 or a control valve, a control line 40 leads to the load pressure signaling line 24 via a check valve 42 opening toward the load pressure signaling line 24. The load pressure signal of the consumer 30 is supplied via the control line 47 to an actuator of the switching valve 44 and acts on it in the opening direction. In the closing direction, the actuator of the switching valve 44 is acted upon by the spring 46. In an actuated switching position of the switching valve 44, there is a fluid connection between the load pressure signaling line 24 and the pressure limiting valve 48. In an unactuated switching position of the switching valve 44, the fluidic connection between the load pressure signaling line 24 and the pressure relief valve 48 is interrupted.

Wie bei der hydraulischen Steuervorrichtung 1 ist der Öffnungsdruck des Druckbegrenzungsventils 48 nach Maßgabe des maximal zulässigen Lastdrucks des Verbrauchers 30 eingestellt. Der durch die Feder 46 bestimmte Schaltdruck des Schaltventils 44 beträgt etwa 5 bis 10 bar weniger als der Öffnungsdruck des Druckbegrenzungsventils 48.As in the hydraulic control device 1, the opening pressure of the pressure relief valve 48 is set in accordance with the maximum allowable load pressure of the load 30. The determined by the spring 46 switching pressure of the switching valve 44 is about 5 to 10 bar less than the opening pressure of the pressure relief valve 48th

Der am Lastdruckmeldeanschluss 33 erfasste Lastdruck wird - falls seitens der weiteren Verbraucher kein höherer Lastdruck besteht - über das Rückschlagventil 42 in die Lastdruckmeldeleitung 24 gemeldet. Zudem steht der am Anschluss 33 erfasste Lastdruck über die Steuerleitung 47 am Schaltventil 44 an. Erreicht dieses Lastdrucksignal den Öffnungsdruck des Schaltventils 44, so gibt das Schaltventil 44 die Verbindung zwischen der Lastdruckmeldeleitung 24 und dem Druckbegrenzungsventil 48 frei. Daraufhin ist das auf der Lastdruckmeldeleitung 24 geführte Lastdrucksignal auf den Öffnungsdruck des Druckbegrenzungsventils 48 begrenzt. Die Funktion der hydraulischen Steuervorrichtung 2 entspricht also hinsichtlich des Überlastungsschutzes für den Verbraucher 30 der Funktion der hydraulischen Steuervorrichtung 1. Das Anschließen des Schaltventils 44 an die Lastdruckmeldeleitung 24 über eine separate Steuerleitung 45 erlaubt eine höhere Flexibilität bei der Anordnung des Schaltventils 44 und des Druckbegrenzungsventils 48. Zudem kann ein einfach aufgebautes Schaltventil verwendet werden.The load pressure detected at the load pressure signaling connection 33 is reported to the load pressure signaling line 24 via the check valve 42 if no higher load pressure exists on the part of the further load. In addition, the load pressure detected at the terminal 33 is applied to the switching valve 44 via the control line 47. When this load pressure signal reaches the opening pressure of the switching valve 44, the switching valve 44 releases the connection between the load pressure signaling line 24 and the pressure limiting valve 48. Thereupon, the load pressure signal guided on the load pressure signaling line 24 is limited to the opening pressure of the pressure limiting valve 48. The function of the hydraulic control device 2 thus corresponds to the function of the hydraulic control device 1 with regard to the overload protection for the load 30. The connection of the switching valve 44 to the load pressure signaling line 24 via a separate control line 45 allows a greater flexibility in the arrangement of the switching valve 44 and the pressure relief valve 48. In addition, a simply constructed switching valve can be used.

In Figur 3 ist mit der hydraulischen Steuervorrichtung 3 eine weitere Abwandlung der in Figur 1 dargestellten hydraulischen Steuervorrichtung 1 gezeigt. Wiederum sind gleiche Bestandteile mit gleichen Bezugszeichen versehen und werden nicht eigens erläutert. Die Geschwindigkeit des Verbrauchers 15 wird über eine Zumessblende 52 gesteuert. Stromab der Zumessblende 52 ist eine Druckwaage 54 angeordnet. Im Fluidweg von der Pumpe 10 zum Verbraucher 15 befinden sich des Weiteren ein Lasthalteventil 64 und das Wegeventil 20. Die Druckwaage 54 besitzt einen Regelkolben 57. Durch den Regelkolben 57 führt eine Steuerleitung 58 in einen Rückraum 55 der Druckwaage 54. In der Steuerleitung 58 ist ein zum Rückraum 55 hin öffnendes Rückschlagventil 59 angeordnet. Der Rückraum 55 steht mit einer Lastdruckmeldeleitung 50 in fluidischer Verbindung. Zudem ist im Rückraum 55 eine Feder 56 angeordnet, die auf den Regelkolben 57 wirkt. Weitere Verbraucher (nicht gezeigt) werden über gleichartig aufgebaute Druckwaagen 62 mit Druckmittel versorgt.In FIG. 3 is with the hydraulic control device 3, a further modification of in FIG. 1 shown hydraulic control device 1 shown. Again, the same components are provided with the same reference numerals and are not specifically explained. The speed of the consumer 15 is controlled via a metering orifice 52. Downstream of the metering orifice 52, a pressure compensator 54 is arranged. In the fluid path from the pump 10 to the consumer 15 are further a load-holding valve 64 and the directional control valve 20. The pressure compensator 54 has a control piston 57. By the control piston 57 performs a control line 58 into a back space 55 of the pressure compensator 54. In the control line 58 is a check valve 59 opening towards the rear space 55 is arranged. The rear space 55 is in fluid communication with a load pressure signaling line 50. In addition, a spring 56 is arranged in the rear space 55, which acts on the control piston 57. Further consumers (not shown) are supplied via similarly constructed pressure compensators 62 with pressure medium.

Über die Zuleitung 13 wird zudem ein Lenkaggregat 70 versorgt. Das Lenkaggregat 70 steuert über Anschlüsse 78 und 79 den/die Lenkzylinder eines Fahrzeuges an. Hauptbestandteil des Lenkaggregates 70 ist ein Rotorsatz 72, über den die den Anschlüssen 78 und 79 zugeführte Druckmittelmenge gesteuert wird. An einem Lastdruckmeldeanschluss 76 des Lenkaggregates 70 ist ein Lastdrucksignal nach außen geführt. Dieses Lastdrucksignal wird innerhalb des Lenkaggregates 70 durch ein Druckbegrenzungsventils 74 begrenzt. Das am Lastdruckmeldeanschluss 76 anstehende Lastdrucksignal wird über die Steuerleitung 77 an das Schaltventil 36 geführt. Über die Steuerleitung 37 ist ein Stellglied des Schaltventils 36 mit diesem Lastdrucksignal beaufschlagt.In addition, a steering unit 70 is supplied via the supply line 13. The steering unit 70 controls via terminals 78 and 79 to / the steering cylinder of a vehicle. The main component of the steering unit 70 is a rotor set 72, via which the terminals 78 and 79 supplied amount of pressure medium is controlled. At a load pressure signaling port 76 of the steering unit 70, a load pressure signal is passed to the outside. This load pressure signal is limited within the steering unit 70 by a pressure relief valve 74. The load pressure signal present at the load pressure signaling connection 76 is conducted via the control line 77 to the switching valve 36. Via the control line 37, an actuator of the switching valve 36 is acted upon by this load pressure signal.

Die Druckwaage 54 regelt den Druck stromab der Zumessblende 52 auf einen Wert ein, der um das Druckäquvivalent der Kraft der Feder 56 über dem Lastdrucksignal liegt, das in ihrem Rückraum 55 ansteht. Üblicherweise ist die Feder 56 recht schwach ausgelegt, so dass der Druck zwischen der Zumessblende 52 und der Druckwaage 54 nur geringfügig über dem in dem Druckraum 55 anstehenden Lastdrucksignal liegt. Dieses Lastdrucksignal entspricht dem höchsten Lastdruck der angeschlossenen Verbraucher. Die Rückräume weiterer Druckwaagen 62, etc. sind ebenso wie der Druckraum 55 mit dem in der Lastdruckmeldeleitung 50 geführten Lastdrucksignal beaufschlagt. Der Druck stromauf der Zumessblende 52 entspricht dem von der Hydropumpe 10 bereitgestellten Versorgungsdruck. Daher steht über der Zumessblende 52 eine Druckdifferenz an, die im Wesentlichen der Regeldruckdifferenz Δp des Pumpenreglers 11 entspricht. Diese Art der load-sensing Steuerung ist unter der Bezeichnung lastunabhängige Durchflussverteilung (LUDV) bekannt. Sollte der von der Pumpe geförderte Volumenstrom nicht zur Deckung des Bedarfs der Verbraucher ausreichen, so verteilt sich der zur Verfügung stehende Strom gleichmäßig unter den auf diese Weise angesteuerten Verbrauchern.The pressure compensator 54 regulates the pressure downstream of the metering orifice 52 to a value which is about the pressure equivalent of the force of the spring 56 above the load pressure signal, which is present in its rear space 55. Usually that is Spring 56 designed quite weak, so that the pressure between the metering orifice 52 and the pressure compensator 54 is only slightly above the pending in the pressure chamber 55 load pressure signal. This load pressure signal corresponds to the highest load pressure of the connected consumers. The back rooms of further pressure compensators 62, etc., as well as the pressure chamber 55 are acted upon by the load pressure signal carried in the load pressure signaling line 50. The pressure upstream of the metering orifice 52 corresponds to the supply pressure provided by the hydraulic pump 10. Therefore, there is a pressure difference across the metering orifice 52, which essentially corresponds to the control pressure difference Δp of the pump regulator 11. This type of load-sensing control is known as load independent flow distribution (LUDV). If the volume flow delivered by the pump is not sufficient to meet the needs of the consumers, the available power is evenly distributed among the consumers controlled in this way.

Als weiterer Verbraucher wird das Lenkaggregat 70 über die Zuleitung 13 von der Pumpe 10 versorgt. Durch die Dimensionierung der Pumpe 10, durch eine genaue Berechnung des Bedarfs der anderen Verbrauchern 15, etc., und/oder durch eine geeignete Steuerung der im Betrieb auftretenden Lastdruckverhältnisse an den Verbrauchern sei sichergestellt, dass keine Untersättigung auftritt bzw. dass das Lenkaggregat 70 stets mit ausreichend Druckmittel versorgt ist. Das am Ausgang 76 des Lenkaggregates 70 anstehende Lastdrucksignal ist über das Schaltventil 36, welches in unbetätigter Stellung die Funktion eines Rückschlagventils hat, der Lastdruckmeldeleitung 50 zugeführt. Sobald sich der Lastdruck des Lenkaggregates 70 einem maximal zulässigen Lastdruck nähert, also Überlastung des Lenkaggregates 70 droht; schaltet das Schaltventil 36 durch den vom Lenkaggregat 70 gemeldeten Lastdruck in eine betätigte Stellung, in der es die Lastdruckmeldeleitung 50 und den Lastdruckmeldeanschluss 76 fluidisch verbindet. Daraufhin ist der in der Lastdruckmeldleitung 50 herrschende Druck durch das interne Druckbegrenzungsventil 74 des Lenkaggregates 70 begrenzt. Eine Überlastung des Lenkaggregates 70 wird somit zuverlässig verhindert. Solange das Schaltventil 36 nicht betätigt ist, kann das in der Lastdruckmeldeleitung 50 anstehende Lastdrucksignal durchaus über dem maximal zufälligen Lastdruck des Lenkaggregates 70 liegen. Erst bei drohender Überlastung des Lenkaggregates 70, genauer gesagt, wenn dessen Lastdruck den Schaltdruck des Schaltventils 36 erreicht, tritt eine Begrenzung des Lastdrucksignals auf der zentralen Lastdruckmeldeleitung 50 in Kraft. Um ein eventuelles Absacken des Verbrauchers 15 in Folge der Lastdruckbegrenzung und der daraus resultierenden Versorgungsdruckbegrenzung zu verhindern, ist in der Versorgungsleitung des Verbrauchers 15 das Lasthalteventil 64 angeordnet.As a further consumer, the steering unit 70 is supplied via the supply line 13 from the pump 10. By dimensioning the pump 10, by an accurate calculation of the needs of other consumers 15, etc., and / or by a suitable control of the load pressure conditions occurring in the operation of the consumers to ensure that no undersaturation occurs or that the steering unit 70 always is supplied with sufficient pressure medium. The present at the output 76 of the steering unit 70 load pressure signal is supplied via the switching valve 36, which has the function of a check valve in the unactuated position, the load pressure signaling line 50. As soon as the load pressure of the steering unit 70 approaches a maximum allowable load pressure, so overloading of the steering unit 70 threatens; Switching the switching valve 36 by the load indicated by the steering unit 70 load in an actuated position in which it connects the load pressure signaling line 50 and the load pressure signaling port 76 fluidly. Thereupon, the pressure prevailing in the load pressure detection line 50 is limited by the internal pressure limiting valve 74 of the steering unit 70. An overload of the steering unit 70 is thus reliably prevented. As long as the switching valve 36 is not actuated, the pending in the load pressure signaling line 50 load pressure signal over the maximum random load pressure of the steering unit 70 are. Only when imminent overloading of the steering unit 70, more specifically, when the load pressure reaches the switching pressure of the switching valve 36, occurs a limitation of the load pressure signal on the central load pressure signaling line 50 in force. In order to prevent a possible sagging of the load 15 as a result of the load pressure limiting and the resulting supply pressure limitation, the load-holding valve 64 is arranged in the supply line of the consumer 15.

Schließlich sei darauf hingewiesen, dass die die anhand der hydraulischen Steuervorrichtungen 1, 2 und 3 beschriebenen Überlastschutzmechanismen ebenso in der elektronischen Steuereinheit einer elektrohydraulischen Steuervorrichtung implementiert werden können. In Bezug auf eine hydraulische Steuervorrichtung ist der Lastmeldepfad im Sinne des Anspruchs 1 als Lastdruckmeldeleitung, die Begrenzungsvorrichtung als Druckbegrenzungsventil und das Schaltmittel als Schaltventil implementiert.Finally, it should be noted that the overload protection mechanisms described with reference to the hydraulic control devices 1, 2 and 3 can also be implemented in the electronic control unit of an electro-hydraulic control device. With regard to a hydraulic control device, the load-signaling path in the sense of claim 1 is implemented as a load-pressure-signaling line, the limiting device as a pressure-limiting valve, and the switching means as a switching valve.

BezugszeichenlisteLIST OF REFERENCE NUMBERS

11
Hydraulische SteuervorrichtungHydraulic control device
22
Hydraulische SteuervorrichtungHydraulic control device
33
Hydraulische SteuervorrichtungHydraulic control device
1010
Pumpepump
1111
Pumpenreglerpump regulator
1212
Tanktank
1313
Zuleitungsupply
1515
Hydraulischer VerbraucherHydraulic consumer
1616
Druckwaagepressure compensator
1818
Verstellbare ZumessblendeAdjustable metering orifice
2020
Wegeventilway valve
2424
LastdruckmeldeleitungLoad pressure signaling line
2525
StromregelventilFlow control valve
2626
Wechselventilshuttle valve
3030
Hydraulischer VerbraucherHydraulic consumer
3232
Verstellbare ZumessblendeAdjustable metering orifice
3333
LastdruckmeldeanschlussLoad pressure signaling connection
3434
Steuerleitungcontrol line
3535
DruckbegrenzungsventilPressure relief valve
3636
Schaltventilswitching valve
3737
Steuerleitungcontrol line
3838
Federfeather
4040
Steuerleitungcontrol line
4242
Rückschlagventilcheck valve
4444
Schaltventilswitching valve
4545
Verbindungsleitungconnecting line
4646
Federfeather
4848
DruckbegrenzungsventilPressure relief valve
5050
LastdruckmeldeleitungLoad pressure signaling line
5252
Zumessblendemetering orifice
5454
Druckwaagepressure compensator
5555
Rückwärtiger DruckraumBackward pressure chamber
5656
Regelfedercontrol spring
5757
Regelkolbencontrol piston
5858
Steuerleitungcontrol line
5959
Rückschlagventilcheck valve
6262
Druckwaagepressure compensator
6464
LasthalteventilLoad-holding valve
7070
Lenkaggregatsteering unit
7272
Rotorsatzrotor set
7474
DruckbegrenzungsventilPressure relief valve
7676
LastdruckmeldeanschlussLoad pressure signaling connection
7777
Steuerleitungcontrol line
7878
Anschlussconnection
7979
Anschlussconnection

Claims (7)

  1. Hydraulic control device of the load-sensing type for activating a first hydraulic consumer (15) and a second hydraulic consumer (30), in which hydraulic control device a first control valve (18, 20) for activating the first hydraulic consumer (15) and a second control valve (32) for activating the second hydraulic consumer (30) are present,
    a first load signal can be detected on the basis of a load pressure which acts upon the first hydraulic consumer (15) and a second load signal can be detected on the basis of a load pressure which acts upon the second hydraulic consumer (30), pressure medium can be supplied from a pressure-medium source (10) in parallel to the first control valve (18, 20) and to the second control valve (32),
    a load communication path (24) is present, which, to activate an actuating member (11) assigned to the pressure-medium source (10), can be acted upon with a highest currently detected load signal, and
    in which a limiting device (35; 48) is present, by means of which the second load signal can be limited to a predetermined signal limit value,
    characterized in that
    a switching means (36; 44) is provided, which can be activated by the second load signal such that, at the latest when the second load signal reaches the signal limit value, the signal carried on the load communication path (24) is limited by the limiting device (35; 48).
  2. Hydraulic control device according to Claim 1, characterized in that a switching valve (36; 44) is provided, which, in an actuated switching position, fluidically connects a load-pressure communication line (24) to a pressure-limiting valve (35; 48), and in that the load pressure of the second consumer (30) is supplied as control pressure to the switching valve (36; 44).
  3. Hydraulic control device according to Claim 2, characterized in that the pressure-limiting valve (35; 74) is arranged on a supply line from a load-pressure communication connection of the second control valve (32; 72) to the load-pressure communication line (24; 50).
  4. Hydraulic control device according to Claim 3, characterized in that the switching valve (36) is designed as a seat valve, and in that, in a non-actuated switching position, it has the function of a non-return valve opening towards the load-pressure communication line (24; 50).
  5. Hydraulic control device according to one of Claims 2 to 4, characterized in that a switching pressure required for actuating the switching valve (36, 44) corresponds at most to the opening pressure of the pressure-limiting valve (35; 48; 74).
  6. Hydraulic control device according to Claim 5, characterized in that the switching pressure of the switching valve (36; 44) is about 5 to 10 bar below the opening pressure of the pressure-limiting valve (35; 48; 74).
  7. Hydraulic control device according to one of Claims 1 to 6, characterized in that the first control valve (52, 20, 64) comprises a load-holding valve (64).
EP06818465A 2005-11-21 2006-11-10 Hydraulic control device Expired - Fee Related EP1954949B1 (en)

Applications Claiming Priority (2)

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DE102005055309A DE102005055309A1 (en) 2005-11-21 2005-11-21 Hydraulic control device
PCT/EP2006/010793 WO2007057126A1 (en) 2005-11-21 2006-11-10 Hydraulic control device

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EP1954949B1 true EP1954949B1 (en) 2010-02-10

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EP (1) EP1954949B1 (en)
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WO (1) WO2007057126A1 (en)

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DE102011118255A1 (en) * 2011-11-11 2013-05-16 Robert Bosch Gmbh Hydrostatic drive and vehicle with such a drive
JP5948260B2 (en) * 2013-01-24 2016-07-06 Kyb株式会社 Fluid pressure control device
US11143211B1 (en) * 2021-01-29 2021-10-12 Cnh Industrial America Llc System and method for controlling hydraulic fluid flow within a work vehicle

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DE4417962A1 (en) 1994-05-21 1995-11-23 Rexroth Mannesmann Gmbh Control arrangement for at least two hydraulic consumers
DE19703997A1 (en) * 1997-02-04 1998-08-06 Mannesmann Rexroth Ag Hydraulic control circuit for a priority and for a subordinate hydraulic consumer
DE19715020A1 (en) 1997-04-11 1998-10-15 Rexroth Mannesmann Gmbh Hydraulic control system for transporting vehicle, especially sedimentation vessels
DE19930618A1 (en) * 1999-07-02 2001-01-04 Mannesmann Rexroth Ag Hydraulic control arrangement for supplying pressure medium to preferably several hydraulic consumers
DE10058032A1 (en) 2000-11-23 2002-05-29 Mannesmann Rexroth Ag Hydraulic control arrangement
DE10149791B4 (en) 2001-10-09 2012-03-29 Linde Material Handling Gmbh Control valve means
DE10245836B4 (en) 2002-04-26 2013-03-14 Bosch Rexroth Aktiengesellschaft LS-way valve assembly

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US8006490B2 (en) 2011-08-30
DE102005055309A1 (en) 2007-05-24
WO2007057126A1 (en) 2007-05-24
DE502006006129D1 (en) 2010-03-25
EP1954949A1 (en) 2008-08-13
US20090064673A1 (en) 2009-03-12

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