EP0564939B1 - Hydraulic control system for several motors - Google Patents

Hydraulic control system for several motors Download PDF

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Publication number
EP0564939B1
EP0564939B1 EP93105124A EP93105124A EP0564939B1 EP 0564939 B1 EP0564939 B1 EP 0564939B1 EP 93105124 A EP93105124 A EP 93105124A EP 93105124 A EP93105124 A EP 93105124A EP 0564939 B1 EP0564939 B1 EP 0564939B1
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EP
European Patent Office
Prior art keywords
control
pressure
control device
pump
valves
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP93105124A
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German (de)
French (fr)
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EP0564939A1 (en
Inventor
Dieter Roth
Mikko Erkkilä
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Bosch Rexroth AG
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Mannesmann Rexroth AG
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Priority claimed from DE4308004A external-priority patent/DE4308004C2/en
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Publication of EP0564939A1 publication Critical patent/EP0564939A1/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
    • F15B11/16—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
    • F15B11/165—Servomotor 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20546—Type of pump variable capacity
    • F15B2211/20553—Type of pump variable capacity with pilot circuit, e.g. for controlling a swash plate
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/20576—Systems with pumps with multiple pumps
    • F15B2211/20584—Combinations of pumps with high and low capacity
    • 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
    • F15B2211/30525—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
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3105—Neutral or centre positions
    • F15B2211/3116—Neutral or centre positions the pump port being open in the centre position, e.g. so-called open centre
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3144—Directional control characterised by the positions of the valve element the positions being continuously variable, e.g. as realised by proportional valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/329—Directional control characterised by the type of actuation actuated by fluid pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—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
    • F15B2211/415—Flow control characterised by the connections of the flow control means in the circuit
    • F15B2211/41554—Flow control characterised by the connections of the flow control means in the circuit being connected to a return line 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
    • F15B2211/40—Flow control
    • F15B2211/42—Flow control characterised by the type of actuation
    • F15B2211/428—Flow control characterised by the type of actuation actuated by fluid pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/47—Flow control in one direction only
    • F15B2211/473—Flow control in one direction only without restriction in the reverse direction
    • 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
    • F15B2211/50518—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
    • F15B2211/50527—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 using cross-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
    • F15B2211/51—Pressure control characterised by the positions of the valve element
    • F15B2211/511—Pressure control characterised by the positions of the valve element the positions being discrete
    • 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
    • F15B2211/5158—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and an output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/555—Pressure control for assuring a minimum pressure, e.g. by using a back pressure valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/635—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements
    • F15B2211/6355—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements having valve means
    • 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
    • F15B2211/67—Methods for controlling pilot pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—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
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F15B2211/7114—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators

Definitions

  • the invention relates to a hydraulic control device according to the preamble of claim 1.
  • the pressure regulator of the pump is set to a value which corresponds to the maximum permissible consumer pressure. If, for example, the consumer, such as the tilt cylinder or lift cylinder of a loader, is driven to the stop and held in this position, the pump swivels back so far and thus reduces its delivery rate to such an extent that the maximum value of the pressure set on the pressure regulator is maintained. Regardless of whether such a high pressure is required for the consumer or not in this operating state.
  • the invention is therefore based on the object of developing the known hydraulic control device according to the preamble of claim 1 in such a way that only the pump pressure occurs during operation of the hydraulic device, which is required for the function of the consumers at the time of their operation.
  • This is achieved with the characterizing features of claim 1.
  • Characterized in that the pressure setting of the pressure regulator for the pump from the control position of the control valve for the consumer with the greatest load is carried out with the actuation of the control valves at the same time a corresponding setting of the pressure regulator, which is required to actuate the consumer.
  • the control valve for the greatest load must therefore be moved in the opening direction until the pressure control device ensures a pressure build-up corresponding to the load by the pump.
  • the speed of this consumer is therefore not determined by the released opening cross section of the assigned control valve, but by the setting of the pressure control device for the variable displacement pump, which is dependent on the setting of the opening cross section of the assigned control valve. If the control pistons are in their starting position, the pressure control device is also provided no control signal is supplied to the pump. In this operating state, the pressure regulator is only acted upon by the low force of the largely relaxed control spring. The pump thus operates at the minimum delivery rate that arises against the pressure specified by the low preload of the control spring. This ensures particularly economical operation of the hydraulic system.
  • a pump is equipped with a pressure regulator, with which the pump pressure is limited to a maximum value, and with a flow regulator, which increases the flow rate by means of a control spring and the highest load pressure and can be acted upon by the pump pressure in the sense of a reduction in the delivery rate.
  • the delivery rate is adjusted so that there is a pressure difference determined by the control spring between the pump pressure and the highest load pressure.
  • the flow rate controller can be acted upon by a pilot valve of a control valve instead of the highest load pressure by means of a shuttle valve, provided the pilot pressure is higher than the highest load pressure.
  • the pilot control device can therefore only set a maximum of a value of the pump pressure which is higher than the maximum pilot pressure by the pressure difference determined by the control spring.
  • the pump pressure is therefore set either from the highest load pressure or from the pilot pressure if the highest load pressure is lower than the maximum pilot pressure, or only from the highest load pressure if this is higher than the maximum pilot pressure.
  • Figure 1 which shows a circuit diagram of a hydraulic control device for a loader, denotes 1 an adjustable pump with actuating cylinder 2.
  • 4 denotes the pressure regulator and 3 the delivery flow regulator.
  • the pressure line 5 of the pump leads to the inlet 6 of a control block 7 with three control pistons 8, 9, and 10, which, with corresponding recesses in the control block, serve directional valves for actuating the working cylinders 11, 12 for the shovel or boom, not shown.
  • the control pistons 8, 9 and 10 are connected to the connections 1 to 5 of a pilot control block 18 via control lines 13, 14, 15, 16 and 17.
  • the pilot control block has four manually operated pressure control valves 20, 21, 22 and 23.
  • a switching valve 24 which directs the control pressure set on the pressure control valve 20 up to a certain size via the control line 16 to the one control surface of the control piston 9.
  • the switching valve 24 shifts in the direction of its switching position a and interrupts the connection of the pressure control valve 20 to the control piston 9 via the control line 16. This is connected to the tank in this switching position of the switching valve 24.
  • the control line 17, which is connected to the one control side of the control piston 10, is used to shift the control pressure from the closed position shown into the floating position, in which the the work lines 30, 31 carrying the lift cylinders 12 are connected to one another and the lift cylinders can thus move freely.
  • a control line section 16a leads to a switching valve 35 which, in the switching position a, ie when pressure is applied via the pressure control valve 20 and thus also when the control piston 9 is pressurized in the “lowering” direction, the pressure line 37 of the control oil pump 38 with the control chamber 39 of a preload valve 40, which is located in the tank line 41, is subjected to control pressure.
  • control lines 13, 14, 15, 16 are operatively coupled to one another via shuttle valves 45, 46 and 47, such that the control pressure acting in the output control line 48 of the shuttle valve 47 is the highest control pressure at the pressure control valves 20, 21, 22 and 23 is set, is effective.
  • This control pressure acts on the biasing piston 50 for the control spring 51 of the pressure regulator 4 via the control line 48 and preloads the control spring 51 accordingly.
  • the highest control pressure in each case for actuating the control pistons 8, 9 is thus a measure of the pressure setting of the pressure regulator 4. If one or the other of the working cylinders 11 or 12 or both are to assume a certain working position, the pressure control valves in question will become so high Control pressure specified that such a pressure can build up in the pump line 5, which brings about a corresponding working movement of the working cylinders, the control pistons simultaneously Move 8 and / or 9 to corresponding tax positions.
  • the control piston 10 does not take part in the pressure regulation of the pump, since this is only intended to bring about a floating position.
  • the control surface of the biasing piston 50 acted upon by the control pressure is larger than the opposite control surface formed by the control piston 4a of the pressure regulator 4 and acted upon by the pump pressure. Since the forces acting on the control piston 4a result from the product of the effective pressurized area and the respective control pressure, a relatively high pump pressure can be regulated via the biasing piston with a large pressure-effective area.
  • the ratio of the control surface of the control piston of the pressure regulator acted upon by the pump pressure relates to the effective control surface of the biasing piston 50, for example, in the order of magnitude of 1 to 8 to 20. 30 bar a pressure setting of the pump in the order of magnitude up to max. Achieve 300 bar. Depending on the application, a different area ratio may also be appropriate. If high pressure is selected for control, the area ratio can also be 1: 1.
  • the exemplary embodiment according to Figure 2 differs from the exemplary embodiment according to Figure 1 only in that the highest control pressure prevailing in the control line 48 is not the pressure regulator 4 but a pressure limiting valve 60 for its respective pressure setting for the pressure regulator via the throttle 61 and the control line 62 4 acting control liquid branched from the pressure line 5 of the pump is supplied. With this arrangement, the standard pressure regulator of the pump can be retained. It is only necessary that the pressure relief valve be equipped with an appropriate pressure ratio.
  • the exemplary embodiment according to FIG. 3 corresponds to the exemplary embodiment according to FIG. 2, wherein instead of hydraulic control means, electrical control means 70, 71 in the form of control signals 70 generating electrical signals and electrical actuating magnets for the control valves 8, 9 and the pressure limiting valve 60 are provided. So this is an electrical solution.
  • control pressure for the pressure regulator is formed as throttles that can be changed with the control piston stroke in the flow cross-section by forming the interacting control edges 8, 9, 10, which control the conveying liquid circulation, to form a control block SB.
  • the greater the stroke the greater the throttling effect of the interacting control edges of the control valves and, accordingly, the pressure - seen in the direction of flow - in front of the throttles increases, the highest pressure also being determined by the control piston with the largest stroke.
  • the control liquid is withdrawn from the pressure line 5 of the pump via a throttle 61 and returned to the tank via the circulation channel 66.
  • the throttle 61 in the initial position of the directional control valves limits the maximum delivery rate to be returned from the pump to the tank via the circulation channel 66 in the control block.
  • the highest control pressure also determines the most deflected control piston.

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

Description

Die Erfindung betrifft eine hydraulische Steuereinrichtung nach dem Oberbegriff des Anspruches 1. Bei diesen bekannten Steuereinrichtungen wird der Druckregler der Pumpe auf einen Wert eingestellt, der dem maximalen zulässigen Verbraucherdruck entspricht. Wird beispielsweise der Verbraucher wie Tiltzylinder oder Liftzylinder eines Laders bis zum Anschlag gefahren und in dieser Lage gehalten, schwenkt die Pumpe soweit zurück und verringert damit ihre Fördermenge soweit, daß gerade der maximale am Druckregler eingestellte Wert des Druckes aufrechterhalten bleibt. Unabhängig davon, ob in diesem Betriebszustand für den Verbraucher ein so hoher Druck erforderlich ist oder nicht.The invention relates to a hydraulic control device according to the preamble of claim 1. In these known control devices, the pressure regulator of the pump is set to a value which corresponds to the maximum permissible consumer pressure. If, for example, the consumer, such as the tilt cylinder or lift cylinder of a loader, is driven to the stop and held in this position, the pump swivels back so far and thus reduces its delivery rate to such an extent that the maximum value of the pressure set on the pressure regulator is maintained. Regardless of whether such a high pressure is required for the consumer or not in this operating state.

Die Erfindung hat sich deshalb die Aufgabe gestellt, die bekannte hydraulische Steuereinrichtung nach dem Oberbegriff des Anspruches 1 dahingehend weiterzubilden, daß während des Betriebs der Hydraulikeinrichtung jeweils nur der Pumpendruck auftritt, der für die Funktion der Verbraucher zum Zeitpunkt ihres Betriebs erforderlich ist. Dies wird mit den kennzeichnenden Merkmalen des Anspruches 1 erzielt. Dadurch, daß die Druckeinstellung des Druckreglers für die Pumpe von der Steuerlage des Steuerventils für den Verbraucher mit der größten Last erfolgt, wird mit der Betätigung der Steuerventile gleichzeitig eine entsprechende Einstellung des Druckreglers vorgenommen, die zur Betätigung der Verbraucher erforderlich ist. Das Steuerventil für die größte Last muß also soweit in Öffnungsrichtung verschoben werden, bis die Druckregeleinrichtung einen der Last entsprechenden Druckaufbau durch die Pumpe gewährleistet. Die Geschwindigkeit dieses Verbrauchers wird also nicht vom freigegebenen Öffnungsquerschnitt des zugeordneten Steuerventils, sondern durch die Einstellung der von der Einstellung des Öffnungsquerschnitts des zugeordneten Steuerventils abhängigen Druckregeleinrichtung für die Verstellpumpe festgelegt. Befinden sich die Steuerkolben in ihrer Ausgangsstellung erhält auch die Druckregeleinrichtung der Pumpe kein Steuersignal zugeführt. Der Druckregler ist in diesem Betriebszustand nur von der geringen Kraft der weitgehend entspannten Regelfeder beaufschlagt. Die Pumpe arbeitet somit bei der sich hierbei einstellenden minimalen Fördermenge gegen den von der geringen Vorspannung der Regelfeder vorgegebenen Druck. Damit wird ein besonders wirtschaftlicher Betrieb der Hydraulikanlage sichergestellt.The invention is therefore based on the object of developing the known hydraulic control device according to the preamble of claim 1 in such a way that only the pump pressure occurs during operation of the hydraulic device, which is required for the function of the consumers at the time of their operation. This is achieved with the characterizing features of claim 1. Characterized in that the pressure setting of the pressure regulator for the pump from the control position of the control valve for the consumer with the greatest load is carried out with the actuation of the control valves at the same time a corresponding setting of the pressure regulator, which is required to actuate the consumer. The control valve for the greatest load must therefore be moved in the opening direction until the pressure control device ensures a pressure build-up corresponding to the load by the pump. The speed of this consumer is therefore not determined by the released opening cross section of the assigned control valve, but by the setting of the pressure control device for the variable displacement pump, which is dependent on the setting of the opening cross section of the assigned control valve. If the control pistons are in their starting position, the pressure control device is also provided no control signal is supplied to the pump. In this operating state, the pressure regulator is only acted upon by the low force of the largely relaxed control spring. The pump thus operates at the minimum delivery rate that arises against the pressure specified by the low preload of the control spring. This ensures particularly economical operation of the hydraulic system.

Es ist schon bekannt, eine Pumpe in Abhängigkeit von einem Vorsteuersignal, mit dem der Steuerschieber eines Steuerventils angesteuert wird, zu verstellen. So wird bei der hydraulischen Steuereinrichtung nach der DE 37 08 492 A1 der Kolben des Verstellzylinders einer Pumpe vom jeweils höchsten Vorsteuerdruck beaufschlagt, der gerade mit Hilfe eines hydraulischen Vorsteuergeräts erzeugt ist. Auf diese Weise wird unmittelbar die Fördermenge der Pumpe vorgegeben. Es handelt sich somit nicht um eine Druckeinstellung, sondern um eine Fördermengeneinstellung.It is already known to adjust a pump as a function of a pilot control signal with which the control slide of a control valve is controlled. In the hydraulic control device according to DE 37 08 492 A1, the piston of the adjusting cylinder of a pump is acted upon by the highest pilot pressure, which is currently being generated with the aid of a hydraulic pilot device. In this way, the delivery rate of the pump is specified directly. It is therefore not a pressure setting, but a delivery rate setting.

Bei einer hydraulischen Steuereinrichtung nach der DE 38 05 287 A1 ist eine Pumpe mit einem Druckregler, mit dem der Pumpendruck auf einen maximalen Wert begrenzt ist, und mit einem Förderstromregler ausgestattet, der im Sinne einer Erhöhung der Fördermenge von einer Regelfeder und vom höchsten Lastdruck und im Sinne einer Verringerung der Fördermenge vom Pumpendruck beaufschlagbar ist. Die Fördermenge wird jeweils so ausgeregelt, daß zwischen Pumpendruck und höchstem Lastdruck die von der Regelfeder bestimmte Druckdifferenz besteht.In a hydraulic control device according to DE 38 05 287 A1, a pump is equipped with a pressure regulator, with which the pump pressure is limited to a maximum value, and with a flow regulator, which increases the flow rate by means of a control spring and the highest load pressure and can be acted upon by the pump pressure in the sense of a reduction in the delivery rate. The delivery rate is adjusted so that there is a pressure difference determined by the control spring between the pump pressure and the highest load pressure.

Über ein Wechselventil ist der Förderstromregler im Sinne einer Erhöhung der Fördermenge anstelle vom höchsten Lastdruck von einem Vorsteuerdruck eines Steuerventils beaufschlagbar, sofern der Vorsteuerdruck höher als der höchste Lastdruck ist. Es ist also mit dem Vorsteuergerät maximal nur ein solcher Wert des Pumpendrucks einstellbar, der um die von der Regelfeder bestimmte Druckdifferenz höher als der maximale Vorsteuerdruck ist. Die Einstellung des Pumpendrucks erfolgt demnach entweder vom höchsten Lastdruck oder vom Vorsteuerdruck, wenn der höchste Lastdruck niedriger als der maximale Vorsteuerdruck ist, oder nur vom höchsten Lastdruck, wenn dieser höher als der maximale Vorsteuerdruck ist.The flow rate controller can be acted upon by a pilot valve of a control valve instead of the highest load pressure by means of a shuttle valve, provided the pilot pressure is higher than the highest load pressure. The pilot control device can therefore only set a maximum of a value of the pump pressure which is higher than the maximum pilot pressure by the pressure difference determined by the control spring. The pump pressure is therefore set either from the highest load pressure or from the pilot pressure if the highest load pressure is lower than the maximum pilot pressure, or only from the highest load pressure if this is higher than the maximum pilot pressure.

Weitere Merkmale der Erfindung ergeben sich aus den Unteransprüchen. Anhand der Zeichnung wird die Erfindung nachfolgend näher beschrieben.Further features of the invention emerge from the subclaims. The invention is described in more detail below with the aid of the drawing.

Die Abbildungen zeigen Ausführungsbeispiele der Erfindung.The figures show exemplary embodiments of the invention.

Die ein Schaltschema einer hydraulischen Steuereinrichtung für einen Lader zeigende Abbildung 1 bezeichnet mit 1 eine verstellbare Pumpe mit Stellzylinder 2. 4 bezeichnet den Druckregler und 3 den Förderstromregler. Die Druckleitung 5 der Pumpe führt zum Einlaß 6 eines Steuerblocks 7 mit drei Steuerkolben 8, 9, und 10, die mit entsprechenden Ausnehmungen im Steuerblock Wegeventile zum Ansteuern der Arbeitszylinder 11, 12 für die nicht dargestellte Schaufel bzw. Ausleger dienen. Die Steuerkolben 8, 9, und 10 stehen über Steuerleitungen 13, 14, 15, 16 und 17 mit den Anschlüssen 1 bis 5 eines Vorsteuerblocks 18 in Verbindung. Der Vorsteuerblock weist vier von Hand zu betätigende Druckregelventile 20, 21, 22 und 23 auf. Ferner ein Schaltventil 24, das den am Druckregelventil 20 eingestellten Steuerdruck bis zu einer bestimmten Größe über die Steuerleitung 16 an die eine Steuerfläche des Steuerkolbens 9 leitet. Bei Überschreiten des an der Feder einzustellenden Schaltdrucks verschiebt sich das Schaltventil 24 in Richtung seiner Schaltstellung a und unterbricht die Verbindung des Druckregelventils 20 zum Steuerkolben 9 über die Steuerleitung 16. Diese wird in dieser Schaltstellung des Schaltventils 24 mit dem Tank verbunden. Bei weiterem Anstieg des am Druckregelventil 20 einzustellenden Steuerdrucks wird über die Steuerleitung 17, die mit der einen Steuerseite des Steuerkolbens 10 in Verbindung steht, diese aus der gezeigten Schließstellung in die Schwimmstellung verschoben, in der die zu den Liftzylindern 12 führenden Arbeitsleitungen 30, 31 miteinander verbunden sind und sich damit die Liftzylinder frei bewegen können. Die Arbeitsbewegungen der Liftzylinder werden mit Hilfe des Steuerkolbens 9 gesteuert, der über die Arbeisleitungen 32, 33 mit den Arbeitsleitungen 30, 31 verbunden ist und damit zu den betreffenden Zylinderräumen 34, 35 der Liftzylinder Direktverbindung aufweist. Von der Steuerleitung 16 führt ein Steuerleitungsabschnitt 16a zu einem Schaltventil 35, das in der Schaltstellung a also bei Druckbeaufschlagung über das Druckregelventil 20 und damit auch bei Druckbeaufschlagung des Steuerkolbens 9 in Richtung "Senken" die Druckleitung 37 der Steuerölpumpe 38 mit dem Steuerraum 39 eines Vorspannventils 40, das sich in der Tankleitung 41 befindet, mit Steuerdruck beaufschlagt. Damit wird sichergestellt, daß beim Senken der Liftzylinder die aus den Zylinderräumen 34 austretende Arbeitsflüssigkeit unter einem entsprechend hohen Druck gehalten wird, der bei in den kolbenstangenseitigen Zylinderräumen 35 sich einstellenden Unterdruck ein Nachströmen von Arbeitsflüssigkeit über das Rückschlagventil 43 von der Tankleitung 41 in den mit der Arbeitsleitung 32 verbundenen Leitungsabschnitt 32a und von dort zu den kolbenstangenseitigen Zylinderräumen 35 gewährleistet. Die Steuerleitungen 13, 14, 15, 16 sind untereinander über Wechselventile 45, 46 und 47 wirkungsmäßig miteinander gekoppelt, derart, daß der in der Ausgangssteuerleitung 48 des Wechselventils 47 wirkende Steuerdruck dem jeweils höchsten Steuerdruck, der an den Druckregelventilen 20, 21, 22 und 23 eingestellt ist, wirksam ist. Dieser Steuerdruck beaufschlagt über die Steuerleitung 48 den Vorspannkolben 50 für die Regelfeder 51 des Druckreglers 4 und spannt die Regelfeder 51 entsprechend vor. Der jeweils höchste Steuerdruck zur Betätigung der Steuerkolben 8, 9 ist somit ein Maß für die Druckeinstellung des Druckreglers 4. Soll also der eine oder andere Arbeitszylinder 11 bzw. 12 bzw. beide gemeinsam eine bestimmte Arbeitsstellung einnehmen, wird an den betreffenden Druckregelventilen ein so hoher Steuerdruck vorgegeben, daß sich in der Pumpenleitung 5 ein solcher Druck aufbauen kann, der eine entsprechende Arbeitsbewegung der Arbeitszylinder herbeiführt, wobei sich gleichzeitig die Steuerkolben 8 und/oder 9 in entsprechende Steuerlagen verschieben. Der Steuerkolben 10 nimmt an der Druckregelung der Pumpe nicht teil, da dieser lediglich eine Schwimmstellung herbeiführen soll. Diese ersetzt letztlich eine vierte Schaltstellung des Steuerventils 9 für die Liftzylinder 12. Die vom Steuerdruck beaufschlagte Steuerfläche des Vorspannkolbens 50 ist größer als die gegenüberliegende vom Regelkolben 4a des Druckreglers 4 gebildete vom Pumpendruck beaufschlagte Steuerfläche. Da die am Regelkolben 4a angreifenden Kräfte sich aus dem Produkt aus wirksamer druckbeaufschlagter Fläche und dem jeweiligen Steuerdruck ergeben, kann über den Vorspannkolben mit großer druckwirksamer Fläche ein verhältnismäßig großer Pumpendruck geregelt werden. Das Verhältnis der vom Pumpendruck beaufschlagten Steuerfläche des Regelkolbens des Druckreglers verhält sich zur wirksamen Steuerfläche des Vorspannkolbens 50 beispielsweise in der Größenordnung von 1 zu 8 bis 20. Durch dieses Flächenverhältnis läßt sich mit Hilfe des von den Druckregelventilen einzustellenden Steuerdrucks von beispielsweise max. 30 bar eine Druckeinstellung der Pumpe in der Größenordnung bis max. 300 bar erzielen. Je nach Anwendungsfall kann auch ein anderes Flächenverhältnis zweckmäßig sein. Falls Hochdruck zur Ansteuerung gewählt wird, kann das Flächenverhältnis auch bei 1:1 liegen.Figure 1, which shows a circuit diagram of a hydraulic control device for a loader, denotes 1 an adjustable pump with actuating cylinder 2. 4 denotes the pressure regulator and 3 the delivery flow regulator. The pressure line 5 of the pump leads to the inlet 6 of a control block 7 with three control pistons 8, 9, and 10, which, with corresponding recesses in the control block, serve directional valves for actuating the working cylinders 11, 12 for the shovel or boom, not shown. The control pistons 8, 9 and 10 are connected to the connections 1 to 5 of a pilot control block 18 via control lines 13, 14, 15, 16 and 17. The pilot control block has four manually operated pressure control valves 20, 21, 22 and 23. Furthermore, a switching valve 24, which directs the control pressure set on the pressure control valve 20 up to a certain size via the control line 16 to the one control surface of the control piston 9. When the switching pressure to be set on the spring is exceeded, the switching valve 24 shifts in the direction of its switching position a and interrupts the connection of the pressure control valve 20 to the control piston 9 via the control line 16. This is connected to the tank in this switching position of the switching valve 24. If the control pressure to be set on the pressure control valve 20 increases further, the control line 17, which is connected to the one control side of the control piston 10, is used to shift the control pressure from the closed position shown into the floating position, in which the the work lines 30, 31 carrying the lift cylinders 12 are connected to one another and the lift cylinders can thus move freely. The working movements of the lift cylinders are controlled with the aid of the control piston 9, which is connected to the work lines 30, 31 via the working lines 32, 33 and thus has a direct connection to the relevant cylinder spaces 34, 35. From the control line 16, a control line section 16a leads to a switching valve 35 which, in the switching position a, ie when pressure is applied via the pressure control valve 20 and thus also when the control piston 9 is pressurized in the “lowering” direction, the pressure line 37 of the control oil pump 38 with the control chamber 39 of a preload valve 40, which is located in the tank line 41, is subjected to control pressure. This ensures that when the lift cylinder is lowered, the working fluid emerging from the cylinder spaces 34 is kept at a correspondingly high pressure, which, when the vacuum in the piston rod-side cylinder spaces 35 is created, causes the working fluid to flow in via the check valve 43 from the tank line 41 into the one with the Working line 32 connected line section 32a and from there to the piston rod-side cylinder spaces 35 guaranteed. The control lines 13, 14, 15, 16 are operatively coupled to one another via shuttle valves 45, 46 and 47, such that the control pressure acting in the output control line 48 of the shuttle valve 47 is the highest control pressure at the pressure control valves 20, 21, 22 and 23 is set, is effective. This control pressure acts on the biasing piston 50 for the control spring 51 of the pressure regulator 4 via the control line 48 and preloads the control spring 51 accordingly. The highest control pressure in each case for actuating the control pistons 8, 9 is thus a measure of the pressure setting of the pressure regulator 4. If one or the other of the working cylinders 11 or 12 or both are to assume a certain working position, the pressure control valves in question will become so high Control pressure specified that such a pressure can build up in the pump line 5, which brings about a corresponding working movement of the working cylinders, the control pistons simultaneously Move 8 and / or 9 to corresponding tax positions. The control piston 10 does not take part in the pressure regulation of the pump, since this is only intended to bring about a floating position. This ultimately replaces a fourth switching position of the control valve 9 for the lift cylinders 12. The control surface of the biasing piston 50 acted upon by the control pressure is larger than the opposite control surface formed by the control piston 4a of the pressure regulator 4 and acted upon by the pump pressure. Since the forces acting on the control piston 4a result from the product of the effective pressurized area and the respective control pressure, a relatively high pump pressure can be regulated via the biasing piston with a large pressure-effective area. The ratio of the control surface of the control piston of the pressure regulator acted upon by the pump pressure relates to the effective control surface of the biasing piston 50, for example, in the order of magnitude of 1 to 8 to 20. 30 bar a pressure setting of the pump in the order of magnitude up to max. Achieve 300 bar. Depending on the application, a different area ratio may also be appropriate. If high pressure is selected for control, the area ratio can also be 1: 1.

Das Ausführungsbeispiel nach Abbildung 2 unterscheidet sich gegenüber dem Ausführungsbeispiel nach Abbildung 1 lediglich dadurch, daß der in der Steuerleitung 48 herrschende höchste Steuerdruck nicht dem Druckregler 4, sondern einem Druckbegrenzungsventil 60 zu dessen jeweiliger Druckeinstellung für die über die Drossel 61 und die Steuerleitung 62 den Druckregler 4 beaufschlagende von der Druckleitung 5 der Pumpe abgezweigte Steuerflüssigkeit zugeführt wird. Bei dieser Anordnung kann der serienmäßig verwendete Druckregler der Pumpe beibehalten werden. Es ist lediglich erforderlich, daß das Druckbegrenzungsventil mit einer entsprechenden Druckübersetzung ausgestattet werden.The exemplary embodiment according to Figure 2 differs from the exemplary embodiment according to Figure 1 only in that the highest control pressure prevailing in the control line 48 is not the pressure regulator 4 but a pressure limiting valve 60 for its respective pressure setting for the pressure regulator via the throttle 61 and the control line 62 4 acting control liquid branched from the pressure line 5 of the pump is supplied. With this arrangement, the standard pressure regulator of the pump can be retained. It is only necessary that the pressure relief valve be equipped with an appropriate pressure ratio.

Durch die Verwendung des serienmäßigen Druckreglers ergibt sich der weitere Vorteil, daß eine druckabhängige Steuerung mit der erfindungsgemäßen Steuerung zusammenarbeiten kann. Das jeweils höchste Signal der beiden Steuerungen wird über ein Wechselventil dem Stromregler zugeführt. In Abbildung 4 ist dies schematisch dargestellt. Die druckabhängige Steuerung ist mit Load-Sensing bezeichnet, der Druckregler der Pumpe 1 mit DFR und das Wechselventil mit 65. Ansonsten entsprechen die Positionszahlen denen der Abbildung 2.The use of the standard pressure regulator results in the further advantage that a pressure-dependent control can work together with the control according to the invention. That in each case The highest signal of the two controls is fed to the current controller via a shuttle valve. This is shown schematically in Figure 4. The pressure-dependent control is called load-sensing, the pressure regulator of pump 1 with DFR and the shuttle valve with 65. Otherwise, the position numbers correspond to those in Figure 2.

Das Ausführungsbeispiel nach Abbildung 3 entspricht dem Ausführungsbeispiel nach Abbildung 2, wobei anstelle hydraulischer Steuermittel elektrische Steuermittel 70, 71 in Form elektrischer Signale erzeugende Steuergeber 70 und elektrische Stellmagnete für die Steuerventile 8, 9 und dem Druckbegrenzungsventil 60 vorgesehen sind. Es handelt sich also hierbei um eine elektrische Lösung.The exemplary embodiment according to FIG. 3 corresponds to the exemplary embodiment according to FIG. 2, wherein instead of hydraulic control means, electrical control means 70, 71 in the form of control signals 70 generating electrical signals and electrical actuating magnets for the control valves 8, 9 and the pressure limiting valve 60 are provided. So this is an electrical solution.

In einem weiteren Ausführungsbeispiel nach Abbildung 5 wird der Steuerdruck für den Druckregler durch Ausbildung der miteinander zusammenwirkenden der den Förderflüssigkeitsumlauf steuernden Steuerkanten der zu einem Steuerblock SB vereinigten Steuerventile 8, 9, 10 als mit dem Steuerkolbenhub im Durchflußquerschnitt veränderbaren Drosseln. Je größer der Hub umso größer wird die Drosselwirkung der miteinander zusammenwirkenden Steuerkanten der Steuerventile und dementsprechend nimmt der Druck - in Durchflußrichtung gesehen - vor den Drosseln zu, wobei der höchste Druck ebenfalls von dem Steuerkolben mit dem größten Hub festgelegt wird. Die Steuerflüssigkeit wird wie bei den Ausführungsbeispielen 2 bis 4 über eine Drossel 61 von der Druckleitung 5 der Pumpe entnommen und über den Umlaufkanal 66 dem Tank zurückgeführt. Bei dieser Art der Steuerdruckerzeugung, die keine zusätzliche Ventileinrichtung zur Erzielung des Steuerdruckes erfordert, begrenzt die Drossel 61 in der Ausgangsstellung der Wegeventile die maximal von der Pumpe zum Tank zurückzuführende Fördermenge über den Umlaufkanal 66 im Steuerblock. Der höchste Steuerdruck bestimmt bei dieser Steuerdruckerzeugung ebenfalls der am meisten ausgelenkte Steuerkolben.In a further exemplary embodiment according to FIG. 5, the control pressure for the pressure regulator is formed as throttles that can be changed with the control piston stroke in the flow cross-section by forming the interacting control edges 8, 9, 10, which control the conveying liquid circulation, to form a control block SB. The greater the stroke, the greater the throttling effect of the interacting control edges of the control valves and, accordingly, the pressure - seen in the direction of flow - in front of the throttles increases, the highest pressure also being determined by the control piston with the largest stroke. As in the exemplary embodiments 2 to 4, the control liquid is withdrawn from the pressure line 5 of the pump via a throttle 61 and returned to the tank via the circulation channel 66. In this type of control pressure generation, which does not require any additional valve device to achieve the control pressure, the throttle 61 in the initial position of the directional control valves limits the maximum delivery rate to be returned from the pump to the tank via the circulation channel 66 in the control block. With this control pressure generation, the highest control pressure also determines the most deflected control piston.

Claims (9)

  1. Hydraulic control device for independent operation of at least two consumers, such as the tilt cylinder and lift cylinder of a loader, whereby the actuation of the consumers is effected by means of control valves comprising control spools with settable control positions, the source of the pressurized medium being in the form of a variable displacement pump with associated pressure control device, whereby the pilot signal for the control valves may simultaneously be fed to the pressure control device, characterized in that the pressure adjustment of the pressure control device (4) is exclusively effected by the pilot signal of the control spool controlling the consumer with the highest load.
  2. Hydraulic control device according to claim 1, characterized in that the actuation of the control spools of the control valves into the respective control position occurs by means of an adjustable control pressure, and that the respective highest control pressure (20, 21, 22) by means of which one of the said control valves (8, 9) is subjected for the purpose of its actuation, is simultaneously a measure for the pressure adjustment of the pressure control device (3) of the variable displacement pump (1).
  3. Hydraulic control device according to claim 1 or 2, characterized in that the pressure control device is formed by a pressure controller (4), said pressure controller being subjected to the pump pressure in the direction towards a smaller flow volume of the pump (1) and in direction of a larger flow volume, to the respective highest control pressure (20 through 23) which is used for actuating the control valves (8, 9).
  4. Hydraulic control device according to claim 3, characterized in that a control spring (51) of the pressure controller (4) is in supporting engagement with a biasing piston (50), said biasing piston being adapted to be subjected to the respective highest control pressure used for actuating said control valves, and that said control spring is further corresponding biased by said biasing piston.
  5. Hydraulic control device according to claim 4, characterized in that the area of the biasing spool subjected to pressure is larger or equal to the area of the control spool (4a) of the pressure controller (4) which is subjected to the pump pressure.
  6. Hydraulic control device according to claim 1 or 2, characterized in that the pressure control device is designed as a pressure controller (4), the pressure adjustment of said pressure controller (4) being carried out by a hydraulic control pressure being of a size or value determined by a pressure valve (60), the adjustment of which depends on the control position of the control spool of the control valve which controls the consumer (11, 12) with the largest load.
  7. Hydraulic control device according to claim 2 or 6, characterized in that the adjustment of the pressure valve (60) is provided by the highest control pressure used for the control of the control valves (8, 9), and that further the control pressure medium is taken from the pressure side (5) of the pump (1) by means of a throttle (61).
  8. Hydraulic control device according to claim 1 and 6, characterized in that the actuation of the control spools is carried out by means of electric control means (70, 71), whereby the highest control current is simultaneously a measure for the pressure valve (60), which is also adjustable by means of electric control means.
  9. Hydraulic control device according to claim 1, characterized in that the control valves are 6-way-valves having a circulating channel, that the pressure control device is designed as a pressure controller (4), the pressure adjustment of which is carried out by pressure of a control pressure medium which is derived from the pump conduit (5) via a throttle (61) and is guided back to the tank via the control valves (8, 9, 10) and the circulating channel (66) which can be throttled by said control valves, and that the size of the pressure is determined by the control valve with the largest movement and thus the smallest throttle cross section for the control pressure medium flowing back to the tank.
EP93105124A 1992-04-04 1993-03-29 Hydraulic control system for several motors Expired - Lifetime EP0564939B1 (en)

Applications Claiming Priority (4)

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DE4211314 1992-04-04
DE4211314 1992-04-04
DE4308004 1993-03-13
DE4308004A DE4308004C2 (en) 1992-04-04 1993-03-13 Hydraulic control device for multiple consumers

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EP0564939B1 true EP0564939B1 (en) 1995-12-13

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US5528911A (en) 1996-06-25
JPH0674204A (en) 1994-03-15
EP0564939A1 (en) 1993-10-13

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