EP0603722B1 - Hydraulic control system - Google Patents

Hydraulic control system Download PDF

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Publication number
EP0603722B1
EP0603722B1 EP93120202A EP93120202A EP0603722B1 EP 0603722 B1 EP0603722 B1 EP 0603722B1 EP 93120202 A EP93120202 A EP 93120202A EP 93120202 A EP93120202 A EP 93120202A EP 0603722 B1 EP0603722 B1 EP 0603722B1
Authority
EP
European Patent Office
Prior art keywords
control
valve
line
hydraulic
pressure
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
EP93120202A
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German (de)
French (fr)
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EP0603722A1 (en
Inventor
Rudolf Brunner Obering
Martin Dipl.-Ing. Heusser
Harald Dipl.-Ing. Klemens
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Heilmeier and Weinlein Fabrik fuer Oel Hydraulik GmbH and Co KG
Original Assignee
Heilmeier and Weinlein Fabrik fuer Oel Hydraulik GmbH and Co KG
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Publication of EP0603722A1 publication Critical patent/EP0603722A1/en
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Publication of EP0603722B1 publication Critical patent/EP0603722B1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/003—Systems with load-holding valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
    • F15B11/162—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for giving priority to particular servomotors or users
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50545—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using braking valves to maintain a back pressure

Definitions

  • the invention relates to a hydraulic control device of the type specified in the preamble of claim 1.
  • the inflow regulating pressure compensator regulates the amount allocated to the proportional directional control slide valve to such an extent that the hydraulic consumer stops when a load limit is reached. This is brought about by the response of a pressure limiting valve connecting the control line to the return line to the load pressure prevailing in the control line. Until this load limit is reached, the hydraulic consumer can be moved independently of the load at the speed selected by the setting of the slide piston, ie, if necessary at the maximum speed. Because of the maximum speed of the hydraulic consumer or the respective load that is possible until the load limit is reached, a relatively high safety factor must be taken into account for a mobile crane equipped with this control device, which greatly limits the permissible load and / or the range.
  • a relatively large safety factor must be taken into account for safety reasons, which limits the load capacity and / or the range.
  • the safety factor depends on the speed of movement.
  • the amount of hydraulic medium flowing to the hydraulic consumer and thus the speed of movement of the hydraulic motor are reduced in a hydraulic control device according to EP-B-0 340 235 depending on the load.
  • the safety factor to be taken into account when calculating the hoist is then lower as soon as the critical load condition is reached due to the reduced speed.
  • a throttle travel control slide is used, in which a load-independent speed control is not possible.
  • the quantity reduction device is built into the spool of the throttle travel control spool and uses the load pressure of the hydraulic motor to reduce the inflow quantity via a bypass control for the return. Since the load pressure controls the reduction in quantity, no load holding valve can be used to hold the load. The full pump pressure is applied to the throttle valve on the respective pressure side. Since hydraulic medium is drained to the tank via the bypass control means this results in a high mechanical load on the hydraulic medium and an undesirable development of heat. Furthermore, the bypass control is unsuitable if a plurality of directional control slides arranged in parallel control hydraulic motors which can be loaded at different levels simultaneously. A particularly serious disadvantage results from the scanning of the load pressure to reduce the feed quantity if the load pressure does not represent a meaningful reference value in special operating conditions.
  • the invention has for its object to provide a hydraulic control device of the type mentioned, which is structurally simple, enables load-independent speed control of the hydraulic consumer, and in which the quantity reduction can be controlled very reliably.
  • the proportional directional spool valve with the inlet control pressure compensator always ensures load-independent speed control of the hydraulic motor. Since the quantity-reducing device is arranged separately from the slide piston, it can advantageously be operated with a hydraulic or electrical or Control mechanical signal that meaningfully represents a critical load condition of the hoist. This increases the reliability of the quantity reducing device, because it does not have to respond to the load pressure tapped off on the spool if this is not meaningful enough.
  • the hydraulic control device is structurally simple because it works with proven proportional directional spool valves and inlet regulating pressure compensators, which only require simple and inexpensive modifications, which can be retrofitted if necessary, for the quantity reduction function.
  • the use of load holding valves which is advantageous for safety reasons, is possible without restriction.
  • the gripping range and / or the load capacity of the hoist can be increased because the speed of movement can be freely reduced in the critical loading state of the hoist. If the quantity-reducing device intervenes between the inlet control pressure compensator and the proportional travel spool, then the quantity of hydraulic medium flowing in upstream of the spool is reduced, without any bypass control for the return, which is disadvantageous for other parallel consumers. If the quantity reduction device attacks the inlet control pressure compensator, then the quantity supplied to the proportional directional control slide is correspondingly withdrawn in the inlet control pressure compensator.
  • the slide piston is either reset to a lower speed setting or prevented from reaching a setting for an impermissibly high speed.
  • a meaningful signal can be used to control the pressure reducing device, so that the quantity reducing device is at a critical level Load condition intervenes reliably even if there is no critical load condition on the hydraulic motor itself.
  • the control device is particularly useful for mobile cranes, but can also be used for other lifting equipment such as forklifts or lift trucks, tail lifts, concrete pumping devices or even rail-bound and stationary cranes. In principle, modified accordingly, it can also be used to reduce the speed of hoists with load hooks and / or trolleys, even when moving with an electric motor.
  • the hydraulic consumers can be moved at the maximum speed as long as there is no critical load in the hoist. The speed is only reduced when the critical load condition is reached. Then a large load can be moved up to the long range with a lower movement speed. This leads to an increased gripping range and a higher permissible load of the hoist, with the load being moved at a reduced speed at high load in the gripping range gained.
  • the orifice when the orifice is switched on, the pressure difference across the slide piston and thus the amount flowing to the hydraulic consumer are reduced.
  • the aperture can be switched on in at least one step or continuously.
  • the load pressure in the control line or the signal from another signal transmitter that represents a critical load state of the lifting device can serve as a signal for switching on the diaphragm.
  • a 2/2-way switching or control valve is inexpensive and reliable and can also be retrofitted.
  • the prestressing of the control spring of the inlet control pressure compensator is withdrawn to reduce the supply quantity.
  • the inlet control pressure compensator reduces the amount of hydraulic medium flowing into the spool. You can work with a pressure signal in the control line or with an external signal to operate the servo actuator.
  • the secondary pressure relief valve responds as soon as the control pressure in the control line generates a pressure signal that represents the critical load condition.
  • the secondary pressure relief valve allows hydraulic pressure medium to flow off to the return, whereby the amount of hydraulic medium allocated by the inlet control pressure compensator for the proportional directional control slide is correspondingly reduced.
  • the orifice and / or the characteristic curve of the pressure relief valve which is set even steeper by the orifice as desired, ensures that the supply control pressure compensator increases the quantity reduction as the quantity increases.
  • the quantity reduction is controlled only in one direction of movement of the hydraulic consumer.
  • pressure-independent leakage via the two-way controller is used in a particularly advantageous manner to reduce the amount.
  • the quantity reduction can be controlled in only one direction of movement or in both directions of movement of the hydraulic consumer.
  • This embodiment can also be implemented retrospectively in the case of conventional proportional directional control slide valve concepts.
  • the pressure-independent quantity reduction can be modulated with a control valve.
  • the embodiment according to claim 8 is advantageous.
  • the increased switching hysteresis or the hydraulic self-holding compensates for brief interferences. It is possible to use a time relay so that, for example, the quantity can only be reduced after e.g. 0.2 seconds, but the quantity reduction is only canceled when the signal is longer than e.g. 0.7 seconds no longer occurs.
  • the embodiment according to claim 9 is advantageous because usually several hydraulic consumers that can be operated simultaneously and simultaneously can be controlled in one hoist.
  • the speed reduction is only controlled if necessary with the proportional directional control valve, which is responsible for reaching the critical load condition or for which the greatest leakage occurs via the Two-way controller occurs.
  • the hydraulic self-retention of the switching valve or the adjustable switching hysteresis of the switching valve prevent the quantity reduction from swinging in and out.
  • the slide piston is reset by the return servo drive from a setting position for a higher speed to a setting position for a reduced speed when a critical load condition occurs.
  • the reset device either resets the spool from a setting position for a higher speed to a setting position for a low speed or limits the spool stroke.
  • the signal for controlling the quantity reduction is derived hydraulically or electrically from the lifting or articulating cylinder or from a working line of the lifting or articulating cylinder, at a point at which a signal that is meaningful under all operating conditions can be tapped, the represents a critical load condition in the hoist.
  • the signal transmitter can be arranged at any point within the structure of the hoist at which a signal that is meaningful under all circumstances can be determined.
  • the signal transmission to the quantity reduction device is particularly simple in terms of construction.
  • a swivel boom 2 is arranged on a mast 1 in a joint 14, from which a pivotable telescopic boom 3 extends with an extension part 3a, on which a gripper 4 (or a Load harness, a lifting fork, or the like.
  • the swing arm 2 can be pivoted by means of a lifting cylinder 5.
  • An articulated cylinder 6 is inserted between the telescopic boom 3 and the swivel boom 2.
  • the extension part 3a can be extended and retracted with an extension cylinder 7.
  • the cylinders 5, 6, 7 and the gripper 4 are driven by a hydraulic control device (not shown in FIG. 1).
  • the signal generator 8 senses the pressure in the push-out space of the lifting cylinder 5.
  • the signal generator 9 senses the pressure in the push-out space of the articulated cylinder 6.
  • the signal generator 10 is a shuttle valve which transmits the higher pressure in the lifting cylinder 5 or in the articulated cylinder 6 as signal Y.
  • the signal Y can be a hydraulic pressure signal or be an electrical signal that is generated, for example via a pressure switch.
  • the signal generator 11 is arranged at the pivot pin 13 of the lifting cylinder 5 on the mast 1 and is designed as a strain gauge or pressure sensor or similar electronically scannable element.
  • the signal generator 12 is arranged at the joint 14 between the mast 1 and the swivel arm 2 and electronically scanned as a strain gauge or the like.
  • One or more signal generators are used to operate in the hydraulic control device V, e.g. 3 to control a quantity reduction device M.
  • V hydraulic control device
  • FIG. 3 different embodiments of quantity-reducing devices are shown in six units separated by dash-dotted lines. 4 and 5 illustrate further possible variations for quantity reducing devices M.
  • a proportional travel control slide valve S1 to S6 with an associated inlet control pressure compensator Z for load-independent speed control.
  • the hydraulic consumer controlled by the proportional travel control spool S1 to S6 e.g. cylinders 5, 6, 7 in Fig. 1 moves independently of the load at a speed which is based solely on the adjustment of the proportional travel control spool. This is achieved in that the inlet control pressure compensator Z keeps the pressure drop set on the proportional travel control valve constant regardless of the load.
  • Each proportional travel control valve S1 to S6 is connected via a branch pressure line 15a to a common pressure line 15, in which the inlet control pressure compensator Z is arranged.
  • a common return line 16 is connected via branch return lines 16a to all proportional directional control spools S1 to S6.
  • Two working lines 17, 18 each lead from the proportional travel control spools S1 to S6 to the hydraulic motor. In the case of a hydraulic motor which can only be acted upon in one direction and adjustable in the opposite direction under load, only one working line 17 or 18 would be provided.
  • the proportional travel control slides S1 to S6 shown in FIG. 3 have manual adjustment devices 19, with which a slide piston 21 can be adjusted from a zero position against a return spring device 20 into two control positions a and b.
  • a control line 22 carrying the respective load pressure is connected to the control side of the inlet control pressure compensator Z.
  • the control line 22 is connected via an orifice 23 to bleed lines 24a, 24b which can be connected to the working lines 17, 18 via the slide piston 21.
  • a control line 25 connects the bleed lines 24a, 24b via a shuttle valve 26 to a common main control line 27, which leads to a control device of a constant pump or a control pump (not shown) for adjusting the pressure in the pressure line 15.
  • a common return control line 28 is connected to a tank.
  • a further control line 29 is subjected to a constant control pressure during operation of the control device, for example 25 bar.
  • a regulating member 30 is continuously adjustable between a through position and a shut-off position.
  • the control element 30 In the direction of the through position, the control element 30 is acted upon by the pressure in the control line 22 and by a control spring 31.
  • the control element 30 In the opposite direction, the control element 30 via an auxiliary control line 32 with an orifice from the pressure in the pressure line 15a downstream of the inlet control pressure compensator Z.
  • the quantity reducing device M has for the proportional directional control valve S1, e.g. of the lifting cylinder 5 of FIG. 1, a control or switching valve 33 with a fixed or variable orifice 34, which can be activated when the signal Y occurs in the pressure line 15a.
  • the control or switching valve 33 can be actuated by a magnet 35, to which the signal Y is supplied in electrical form.
  • the aperture 34 is not effective during normal operation.
  • the speed is determined by the setting position of the slide piston 21.
  • the pressure difference across the spool 21 is kept constant by the inlet control pressure compensator.
  • signal Y occurs, the aperture 34 is switched on. This means a reduction in volume and thus a reduction in speed for the hydraulic consumer.
  • the curve of FIG. 2 shows how (solid curve) the quantity Q increases over the stroke of the slide piston 21 without the orifice plate 34 being switched on.
  • the dashed curve 20% means that only 20% of the original amount will flow in each point of the stroke of the slide piston 21 after the orifice 34 has been switched on. If, as indicated in FIG.
  • a control valve or a variable orifice 34 is used, then the orifice 34 can be switched on continuously and one for each Set the quantity curve adapted to the requirements, for example as indicated by the dot-dash line in FIG. 2 at "var".
  • the quantity reduction device M has a servo actuator 36 for the control spring 31 of the inlet control pressure compensator Z in order to reduce the preload of the control spring in order to reduce the quantity.
  • a spring-loaded piston displaceable against a return spring is controlled with a switching valve 37 which is connected to the control line 28 via an auxiliary control line 38 and to the pressure line 15a via a further auxiliary control line 39. If the switching valve has a magnet 35, this is excited via the signal Y in order to remove the bias of the control spring 31. This can also be done continuously in one step. By reducing the spring preload, the control pressure difference becomes smaller and the quantity reduction in both working lines 17, 18 is the same in percentage terms.
  • Another auxiliary control line 40 connects the pressure side of the spring-loaded piston to the outlet of the switching valve 37.
  • the quantity reducing device M is equipped with a secondary pressure limiting valve 43, which is arranged in an auxiliary control line 42 connected to the control line 22 to the return line 16a and is set to a pressure value in the control line 22 which represents a critical load state, for example in the hydraulic consumer .
  • An orifice 44 is provided upstream of the secondary pressure relief valve 43.
  • the secondary pressure relief valve 43 has - with or without an orifice 44 - a pressure characteristic curve that increases with an increasing flow rate, and thus from response with increasing load pressure an increasing amount flows through the valve 43.
  • the quantity reducing device M acts in both directions of movement of the hydraulic consumer.
  • the quantity reduction device M is designed analogously to that of the third proportional travel control spool S3 and is equipped with a secondary pressure valve 43 and an upstream orifice 44 in the auxiliary control line 42 '.
  • This quantity reduction device M is only effective in one direction of movement of the hydraulic motor, namely in the control position a of the proportional travel control spool S4.
  • the auxiliary control line 42 ' is guided through a passage 45 in the slide piston 21, which is only open in the control position a. This passage is blocked in the neutral position and in the control position b.
  • the quantity reduction device M works with pressure-independent leakage and only in one direction of movement.
  • the auxiliary control line 42 which is led through the passage 45 in the spool 21 to a tank T, contains a two-way controller 46 to which a switching or control valve 47 is assigned, e.g. downstream, is.
  • a switching or control valve 47 is assigned, e.g. downstream, is.
  • the slide piston 21, which is manually adjustable by means of the adjusting device 19 is a reset servo drive 48 is provided which engages via a valve 49 controllable with the signal Y.
  • the valve 49 is connected to a tank control line 51 and, via a line 50, the control line 29 (which carries a constant pressure).
  • the reset servo drive is activated and the spool 21 is either pushed back from the previously selected setting or is prevented from any further adjustment at all. If the quantity reduction device is to work in both directions of movement, then two counter-acting return servo drives 48 are required.
  • the spool 21 - as is often the case - is hydraulically or electro-hydraulically piloted (indicated at 61), e.g. Via an electromagnetic (magnet 54a) adjustable pressure reducing valve 54 in a control line 52, a further pressure reducing valve 56 can then be inserted into the control line 52, which is activated by the signal Y and reduces the pressure for adjusting the slide piston 21.
  • the further pressure reducing valve 55 can be controlled either hydraulically or electromagnetically. In both variants it is ensured that the speed of the hydraulic motor is reduced from the occurrence of a signal Y or that the low speed is not exceeded.
  • the fourth proportional directional control spool S5 corresponds to the proportional travel control spool S5 of FIG. 3, with the difference that an electro-hydraulic pilot control 61 is also provided, which is connected to the control line 29 and the control line 28 (to the tank).
  • Any quantity reduction device M has in the auxiliary control line 42 to a common collective control line 57 a two-way controller 46 with a check valve 58, which is expediently spring-loaded and opens in the flow direction to the collective control line 57.
  • the quantity is reduced in both directions of movement when the quantity reduction device responds.
  • the switching valve 59 is a 2/2-way switching valve or a magnetically lockable check valve 62.
  • the switching valve 59 is put into the open position. In the open position, a pressure-independent leak occurs via the two-way controller 46 of the proportional travel control spool S5, S7 or S8, which contributes to the critical load state, which leads to a reduction in the quantity because the respective inlet control pressure compensator Z now only allocates a reduced quantity.
  • the switching valve 59 is designed with an increased switching hysteresis so that pressure or load fluctuations occurring during the speed reduction or an unwanted change in the signal Y lead to the switching valve 59 being reset immediately.
  • a time relay can be used which holds the signal for a pre-settable time period and does not cancel the quantity reduction until the signal change remains beyond the set time period.
  • auxiliary control line 42 leads to the control line 57.
  • a two-way controller 46 with an associated check valve 58 is provided in each auxiliary control line 42.
  • the two-way controller 46 enables pressure-independent leakage as soon as the switching valve 59 switches to passage when a signal Y occurs in the control line 64.
  • the switching valve 59 can be a so-called snap holder or a valve 63 with hydraulic self-holding, which, for example, holds its respective position, for example when the pressure signal Y disappears, for a predetermined period of time.
  • the check valves 58 prevent the pressure prevailing in the collective control line 57 from acting back into a control line 22 with a lower control pressure.
  • control pressure in the control line 64 switches the switching valve 59 into the through position, then only the reduced amount is fed to the lifting cylinder 5, so that it moves at a reduced speed.
  • the proportional directional control spool becomes S7 adjusted to move the articulated cylinder 6, then the amount fed to the articulated cylinder 6 is reduced due to the pressure-independent leakage via the two-way controller 46. If both proportional travel control spools S5, S7 are actuated, then only a slight reduced movement speed is permitted for both cylinders 5, 6 or only for that of the two cylinders which is responsible for the critical load condition.
  • the signal Y controlling the respective quantity reducing device M in the control devices V according to FIGS. 4 and 5 can also come from any of the signal transmitters indicated in FIG. 1 or also from another external signal transmitter not shown but meaningfully representing a critical load condition .
  • the components of the quantity reducing devices M used in each case can either be integrated in the proportional directional control slide valve or can be provided on its housing or in the connection block which is usually provided.
  • the proportional directional control spool can therefore also be retrofitted with regard to the speed reduction function. Basic modifications of the proportional directional spool are not necessary for this.

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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)
  • Valve Device For Special Equipments (AREA)
  • Jib Cranes (AREA)

Abstract

In a hydraulic control system (V) for at least one hydraulic consumer (5, 6) of a mobile crane (K), which control system (V) has a directional control spool, connected on the one side to a pressure line (15) and a return line (16) and on the other side to two working lines (17, 18) to the hydraulic motor and having an adjustable spool piston (21), as well as a volume-reducing device (M) which can be brought into engagement as a function of a critical loading state and with which at least the volume of the hydraulic medium flowing to the hydraulic motor can be reduced, the directional control spool is designed as a proportional directional control spool (S1 to S8) with a feed-control pressure balance (Z) connected upstream in the pressure line (15a), and the volume-reducing device (M) is arranged constructionally separate from the spool piston (21) so that it engages between the feed-control pressure balance (Z) and the proportional directional control spool (S1 to S8) or on the feed-control pressure balance (Z) or on the spool piston (21). <IMAGE>

Description

Die Erfindung betrifft eine hydraulische Steuervorrichtung der im Oberbegriff des Patentanspruchs 1 angegebenen Art.The invention relates to a hydraulic control device of the type specified in the preamble of claim 1.

Bei einer aus DE-A-37 10 699 bekannten Steuervorrichtung für Mobilkräne regelt bei Erreichen einer Lastgrenze die Zulaufregel-Druckwaage die dem Proportional-Wegesteuerschieber zugeteilte Menge so weit ab, daß der Hydroverbraucher anhält. Dies wird bewirkt durch Ansprechen eines die Steuerleitung mit dem Rücklauf verbindenden Druck-Begrenzungsventils auf den in der Steuerleitung herrschenden Lastdruck. Bis zum Erreichen dieser Lastgrenze läßt sich der Hydroverbraucher lastunabhängig mit der Geschwindigkeit bewegen, die durch die Einstellung des Schieberkolbens gewählt ist, d.h., gegebenenfalls mit der maximalen Geschwindigkeit. Wegen der bis zum Erreichen der Lastgrenze möglichen maximalen Geschwindigkeit des Hydroverbrauchers bzw. der jeweiligen Last ist für einen mit dieser Steuervorrichtung ausgestatteten Mobilkran ein relativ hoher Sicherheitsfaktor zu berücksichtigen, der die zulässige Last und/oder die Reichweite stark beschränkt.In a control device for mobile cranes known from DE-A-37 10 699, the inflow regulating pressure compensator regulates the amount allocated to the proportional directional control slide valve to such an extent that the hydraulic consumer stops when a load limit is reached. This is brought about by the response of a pressure limiting valve connecting the control line to the return line to the load pressure prevailing in the control line. Until this load limit is reached, the hydraulic consumer can be moved independently of the load at the speed selected by the setting of the slide piston, ie, if necessary at the maximum speed. Because of the maximum speed of the hydraulic consumer or the respective load that is possible until the load limit is reached, a relatively high safety factor must be taken into account for a mobile crane equipped with this control device, which greatly limits the permissible load and / or the range.

Bei der Berechnung eines Mobilkrans ist wegen der Lastbewegung oder der Bewegung von Komponenten des Hebezeugs aus Sicherheitsgründen ein relativ großer Sicherheitsfaktor zu berücksichtigen, der die Tragfähigkeit und/oder die Reichweite beschränkt. Der Sicherheitsfaktor hängt von der Bewegungsgeschwindigkeit ab. Um bei einem Mobilkran trotzdem eine höhere Tragfähigkeit und/oder eine größere Reichweite zu erreichen, wird bei einer hydraulischen Steuervorrichtung gemäß EP-B-0 340 235 in Abhängigkeit von der Last die zum Hydroverbraucher strömende Menge des Hydraulikmediums und damit die Bewegungsgeschwindigkeit des Hydromotors verringert. Der bei der Berechnung des Hebezeugs zu berücksichtigende Sicherheitsfaktor ist dann ab Erreichen des kritischen Belastungszustands wegen der verringerten Geschwindigkeit niedriger. In der bekannten Steuervorrichtung wird ein Drosselwegesteuerschieber verwendet, bei dem eine lastunabhängige Geschwindigkeitssteuerung nicht möglich ist. Die Mengenreduzier-Vorrichtung ist in den Schieberkolben des Drosselwegesteuerschiebers eingebaut und benutzt den Lastdruck des Hydromotors, um die Zulaufmenge über eine Bypaßregelung zum Rücklauf zu verringern. Da der Lastdruck die Verringerung der Menge steuert, läßt sich kein Lasthalteventil zum Halten der Last benutzen. An der jeweiligen Druckseite steht am Drosselwegesteuerschieber der volle Pumpendruck an. Da Hydraulikmedium über die Bypaßregelung zum Tank abgelassen wird, bedeutet dies eine hohe mechanische Belastung des Hydraulikmediums und eine unerwünschte Wärmeentwicklung. Ferner ist die Bypaßregelung unzweckmäßig, wenn mehrere parallel angeordnete Wegesteuerschieber unterschiedlich hoch belastbare Hydromotoren gleichzeitig steuern. Ein besonders schwerwiegender Nachteil resultiert aus der Abtastung des Lastdrucks zur Verminderung der Zulaufmenge, wenn der Lastdruck bei besonderen Betriebszuständen keinen aussagefähigen Referenzwert darstellt. Beispielsweise kann bei einem nach unten geneigten Knickzylinder der Lastdruck bei ziehender Last zu gering sein, um trotz eines kritischen Betriebszustandes im Hebezeug die Zulaufmenge zu reduzieren. Schließlich ist der Drosselwegesteuerschieber außerordentlich kompliziert, und teuer und störungsanfällig.When calculating a mobile crane, due to the load movement or the movement of components of the hoist, a relatively large safety factor must be taken into account for safety reasons, which limits the load capacity and / or the range. The safety factor depends on the speed of movement. In order to achieve a higher load capacity and / or a longer reach in a mobile crane, the amount of hydraulic medium flowing to the hydraulic consumer and thus the speed of movement of the hydraulic motor are reduced in a hydraulic control device according to EP-B-0 340 235 depending on the load. The safety factor to be taken into account when calculating the hoist is then lower as soon as the critical load condition is reached due to the reduced speed. In the known control device, a throttle travel control slide is used, in which a load-independent speed control is not possible. The quantity reduction device is built into the spool of the throttle travel control spool and uses the load pressure of the hydraulic motor to reduce the inflow quantity via a bypass control for the return. Since the load pressure controls the reduction in quantity, no load holding valve can be used to hold the load. The full pump pressure is applied to the throttle valve on the respective pressure side. Since hydraulic medium is drained to the tank via the bypass control means this results in a high mechanical load on the hydraulic medium and an undesirable development of heat. Furthermore, the bypass control is unsuitable if a plurality of directional control slides arranged in parallel control hydraulic motors which can be loaded at different levels simultaneously. A particularly serious disadvantage results from the scanning of the load pressure to reduce the feed quantity if the load pressure does not represent a meaningful reference value in special operating conditions. For example, in the case of an articulated cylinder that is inclined downward, the load pressure when the load is being pulled may be too low to reduce the supply quantity in spite of a critical operating state in the hoist. Finally, the throttle travel control spool is extremely complicated, and expensive and prone to failure.

Der Erfindung liegt die Aufgabe zugrunde, eine hydraulische Steuervorrichtung der eingangs genannten Art zu schaffen, die baulich einfach ist, eine lastunabhängige Geschwindigkeitssteuerung des Hydroverbrauchers ermöglicht, und bei der die Mengenreduzierung sehr zuverlässig steuerbar ist.The invention has for its object to provide a hydraulic control device of the type mentioned, which is structurally simple, enables load-independent speed control of the hydraulic consumer, and in which the quantity reduction can be controlled very reliably.

Die gestellte Aufgabe wird erfindungsgemäß mit den im Patentanspruch 1 angegebenen Merkmalen gelöst.The object is achieved according to the invention with the features specified in claim 1.

Bei dieser Ausbildung gewährleistet der Proportional-wegesteuerschieber mit der Zulaufregel-Druckwaage stets eine lastunabhängige Geschwindigkeitssteuerung des Hydromotors. Da die Mengen-Reduziervorrichtung vom Schieberkolben getrennt angeordnet ist, läßt sie sich vorteilhaft mit einem hydraulischen oder elektrischen oder mechanischen Signal steuern, das einen kritischen Belastungszustand des Hebezeugs aussagefähig repräsentiert. Dies steigert die Zuverlässigkeit der Mengenreduzier-vorrichtung, weil diese nicht auf den am Schieberkolben abgegriffenen Lastdruck anzusprechen braucht, wenn dieser nicht aussagefähig genug ist. Die hydraulische Steuervorrichtung ist baulich einfach, da mit bewährten Proportionalwegesteuerschiebern und Zulaufregel-Druckwaagen gearbeitet wird, die für die Mengenreduzierfunktion nur einfache und kostengünstige, ggfs. nachrüstbare Modifikationen benötigen. Die aus sicherheitstechnischen Gründen vorteilhafte Verwendung von Lasthalteventilen ist ohne Einschränkung möglich. Der Greifbereich und/oder die Tragfähigkeit des Hebezeugs kann bzw. können vergrößert werden, weil die Bewegungsgeschwindigkeit im kritischen Belastungszustand des Hebezeugs frei wählbar reduziert wird. Greift die Mengenreduzier-Vorrichtung zwischen der Zulaufregel-Druckwaage und dem Proportionalwegesteuerschieber ein, dann wird die dem Schieberkolben zulaufende Menge des Hydraulikmediums stromauf des Schieberkolbens reduziert, und zwar ohne für weitere parallele Verbraucher nachteilige Bypaßregelung zum Rücklauf. Greift die Mengenreduzier-Vorrichtung an der Zulaufregel-Druckwaage an, dann wird die dem Proportionalwegesteuerschieber zugeführte Menge bereits in der Zulaufregel-Druckwaage entsprechend zurückgenommen. Greift die Mengenreduzier-Vorrichtung schließlich direkt am Schieberkolben ein, dann wird der Schieberkolben entweder auf eine niedrigere Geschwindigkeitseinstellung zurückgestellt oder daran gehindert, eine Einstellung für eine unzulässig hohe Geschwindigkeit zu erreichen. In jedem Fall läßt sich ein aussagefähiges Signal zum Steuern der Druckreduzier-Vorrichtung benutzen, so daß die Mengenreduzier-Vorrichtung bei einem kritischen Belastungszustand auch dann zuverlässig eingreift, wenn am Hydromotor selbst kein kritischer Belastungszustand vorliegt. Die Steuervorrichtung ist für Mobilkräne besonders zweckmäßig, aber auch für anderes Hebezeug wie Gabel- oder Hubstapler, Ladebordwände, Betonpump-Einrichtungen oder sogar schienengebundene und stationäre Kräne brauchbar. Prinzipiell ist sie - entsprechend modifiziert - auch zur Geschwindigkeitsverringerung bei Hebezeugen mit Lasthaken und/oder Laufkatzen brauchbar, auch bei elektromotorisch bewegten.With this design, the proportional directional spool valve with the inlet control pressure compensator always ensures load-independent speed control of the hydraulic motor. Since the quantity-reducing device is arranged separately from the slide piston, it can advantageously be operated with a hydraulic or electrical or Control mechanical signal that meaningfully represents a critical load condition of the hoist. This increases the reliability of the quantity reducing device, because it does not have to respond to the load pressure tapped off on the spool if this is not meaningful enough. The hydraulic control device is structurally simple because it works with proven proportional directional spool valves and inlet regulating pressure compensators, which only require simple and inexpensive modifications, which can be retrofitted if necessary, for the quantity reduction function. The use of load holding valves, which is advantageous for safety reasons, is possible without restriction. The gripping range and / or the load capacity of the hoist can be increased because the speed of movement can be freely reduced in the critical loading state of the hoist. If the quantity-reducing device intervenes between the inlet control pressure compensator and the proportional travel spool, then the quantity of hydraulic medium flowing in upstream of the spool is reduced, without any bypass control for the return, which is disadvantageous for other parallel consumers. If the quantity reduction device attacks the inlet control pressure compensator, then the quantity supplied to the proportional directional control slide is correspondingly withdrawn in the inlet control pressure compensator. If the quantity reduction device finally engages directly on the slide piston, the slide piston is either reset to a lower speed setting or prevented from reaching a setting for an impermissibly high speed. In any case, a meaningful signal can be used to control the pressure reducing device, so that the quantity reducing device is at a critical level Load condition intervenes reliably even if there is no critical load condition on the hydraulic motor itself. The control device is particularly useful for mobile cranes, but can also be used for other lifting equipment such as forklifts or lift trucks, tail lifts, concrete pumping devices or even rail-bound and stationary cranes. In principle, modified accordingly, it can also be used to reduce the speed of hoists with load hooks and / or trolleys, even when moving with an electric motor.

Die Hydroverbraucher sind mit der maximalen Geschwindigkeit bewegbar, solange kein kritischer Belastungszustand im Hebezeug orreicht ist. Erst ab Erreichen des kritischen Belastungszustands wird die Geschwindigkeit verringert. Dann ist mit geringerer Bewegungsgeschwindigkeit auch eine große Last bis auf die große Reichweite bewegbar. Dies führt zu einem vergrößerten Greifbereich und einer höheren zulässigen Last des Hebezeugs, wobei mit bei hoher Last in dem hinzugewonnenen Greifbereich mit verringerter Geschwindigkeit gefahren wird.The hydraulic consumers can be moved at the maximum speed as long as there is no critical load in the hoist. The speed is only reduced when the critical load condition is reached. Then a large load can be moved up to the long range with a lower movement speed. This leads to an increased gripping range and a higher permissible load of the hoist, with the load being moved at a reduced speed at high load in the gripping range gained.

Bei der Ausführungsform gemäß Anspruch 2 wird bei Zuschalten der Blende die Druckdifferenz über den Schieberkolben und so die zum Hydroverbraucher strömende Menge verringert. Das Zuschalten der Blende kann in zumindest einer Stufe oder stufenlos erfolgen. Als Signal zum Zuschalten der Blende kann der Lastdruck in der Steuerleitung oder das Signal eines anderen, einen kritischen Lastzustand des Hebezeugs aussagefähig repräsentierenden Signalgebers dienen. Ein 2/2-Wege-Schalt- oder Regelventil ist kostengünstig und zuverlässig und läßt sich auch nachträglich anbringen.In the embodiment according to claim 2, when the orifice is switched on, the pressure difference across the slide piston and thus the amount flowing to the hydraulic consumer are reduced. The aperture can be switched on in at least one step or continuously. The load pressure in the control line or the signal from another signal transmitter that represents a critical load state of the lifting device can serve as a signal for switching on the diaphragm. A 2/2-way switching or control valve is inexpensive and reliable and can also be retrofitted.

Bei der Ausführungsform gemäß Anspruch 3 wird zum Vermindern der Zulaufmenge die Vorspannung der Regelfeder der Zulaufregel-Druckwaage zurückgenommen. Die Zulaufregel-Druckwaage verringert die Menge des dem Schieberkolben zulaufenden Hydraulikmediums. Es kann mit einem Drucksignal in der Steuerleitung oder mit einem externen Signal gearbeitet werden, um den Servostellantrieb zu betätigen.In the embodiment according to claim 3, the prestressing of the control spring of the inlet control pressure compensator is withdrawn to reduce the supply quantity. The inlet control pressure compensator reduces the amount of hydraulic medium flowing into the spool. You can work with a pressure signal in the control line or with an external signal to operate the servo actuator.

Eine baulich einfache Ausführungsform geht aus Anspruch 4 hervor. Unabhängig davon, ob das Signal ein Drucksignal in der Steuerleitung oder ein extern erzeugtes Signal ist, wird der Servostellantrieb aus der Druckleitung gespeist, die stets ausreichenden Druck führt.A structurally simple embodiment is evident from claim 4. Regardless of whether the signal is a pressure signal is in the control line or an externally generated signal, the servo actuator is fed from the pressure line, which always carries sufficient pressure.

Eine baulich einfache Ausführungsform geht aus Anspruch 5 hervor. Das Sekundär-Druckbegrenzungsventil spricht an, sobald der Steuerdruck in der Steuerleitung ein den kritischen Belastungszustand repräsentierendes Drucksignal erzeugt. Das Sekundär-Druckbegrenzungsventil läßt Hydraulikdruckmittel zum Rücklauf abströmen, wodurch sich die Menge des von der Zulaufregel-Druckwaage zugeteilten Hydraulikmediums für den Proportionalwegesteuerschieber entsprechend verringert. Dabei sorgt die Blende und/oder die Kennlinie des Druckbegrenzungsventils, die durch die Blende nach Wunsch noch steiler eingestellt wird, dafür, daß mit steigender Menge die Zulaufregel-Druckwaage die Mengenreduzierung verstärkt.A structurally simple embodiment emerges from claim 5. The secondary pressure relief valve responds as soon as the control pressure in the control line generates a pressure signal that represents the critical load condition. The secondary pressure relief valve allows hydraulic pressure medium to flow off to the return, whereby the amount of hydraulic medium allocated by the inlet control pressure compensator for the proportional directional control slide is correspondingly reduced. The orifice and / or the characteristic curve of the pressure relief valve, which is set even steeper by the orifice as desired, ensures that the supply control pressure compensator increases the quantity reduction as the quantity increases.

Bei der Ausführungsform gemäß Anspruch 6 wird die Mengenreduzierung nur bei einer Bewegungsrichtung des Hydroverbrauchers eingesteuert.In the embodiment according to claim 6, the quantity reduction is controlled only in one direction of movement of the hydraulic consumer.

Bei der Ausführungsform gemäß Anspruch 7 wird in besonders vorteilhafter Weise eine druckunabhängige Leckage über den Zweiwegeregler zum Verringern der Menge benutzt. Die Mengenreduzierung kann in nur einer Bewegungsrichtung oder in beiden Bewegungsrichtungen des Hydroverbrauchers eingesteuert werden. Diese Ausführungsform läßt sich bei üblichen Proportionalwegesteuerschieber-Konzepten auch nachträglich realisieren. Mit einem Regelventil kann die druckunabhängige Mengenreduzierung moduliert werden.In the embodiment according to claim 7, pressure-independent leakage via the two-way controller is used in a particularly advantageous manner to reduce the amount. The quantity reduction can be controlled in only one direction of movement or in both directions of movement of the hydraulic consumer. This embodiment can also be implemented retrospectively in the case of conventional proportional directional control slide valve concepts. The pressure-independent quantity reduction can be modulated with a control valve.

Damit durch eine Lastschwankung oder eine auf andere Weise entstehende Druckwelle die Mengenreduzierung nicht wieder aufgehoben wird, ist die Ausführungsform gemäß Anspruch 8 vorteilhaft. Die verstärkte Schalthysteresis oder die hydraulische Selbsthaltung kompensiert kurzzeitige Störeinwirkungen. Dabei ist es möglich, ein Zeitrelais zu benutzen, so daß beispielsweise die Mengenreduzierung erst nach z.B. 0,2 Sek. eingesteuert wird, das Zurücknehmen der Mengenreduzierung jedoch erst erfolgt, wenn das Signal länger als z.B. 0,7 Sek. nicht mehr auftritt.In order that the quantity reduction is not canceled out again by a load fluctuation or a pressure wave arising in some other way, the embodiment according to claim 8 is advantageous. The increased switching hysteresis or the hydraulic self-holding compensates for brief interferences. It is possible to use a time relay so that, for example, the quantity can only be reduced after e.g. 0.2 seconds, but the quantity reduction is only canceled when the signal is longer than e.g. 0.7 seconds no longer occurs.

Die Ausführungsform gemäß Anspruch 9 ist vorteilhaft, weil in einem Hebezeug üblicherweise mehrere parallel und gleichzeitig betreibbare Hydroverbraucher zu steuern sind. Durch die Verknüpfung der Zweiwegeregler über das Schaltventil und die gemeinsame Rücklaufleitung wird die Geschwindigkeitsreduzierung bei Bedarf nur bei dem Proportionalwegesteuerschieber eingesteuert, der für das Erreichen des kritischen Belastungszustandes verantwortlich ist bzw. bei dem die stärkste Leckage über den Zweiwegeregler auftritt. Die hydraulische Selbsthaltung des Schaltventils oder die einstellbare Schalthysteresis des Schaltventils vermeiden ein pendelndes Ein- und Aussteuern der Mengenreduzierung.The embodiment according to claim 9 is advantageous because usually several hydraulic consumers that can be operated simultaneously and simultaneously can be controlled in one hoist. By linking the two-way controller via the switching valve and the common return line, the speed reduction is only controlled if necessary with the proportional directional control valve, which is responsible for reaching the critical load condition or for which the greatest leakage occurs via the Two-way controller occurs. The hydraulic self-retention of the switching valve or the adjustable switching hysteresis of the switching valve prevent the quantity reduction from swinging in and out.

Bei der baulich besonders einfachen Ausführungsform gemäß Anspruch 10 wird der Schieberkolben durch den Rückstellservoantrieb aus einer Einstellage für eine höhere Geschwindigkeit auf eine Einstellage für eine reduzierte Geschwindigkeit zurückgestellt, wenn ein kritischer Belastungszustand auftritt.In the structurally particularly simple embodiment according to claim 10, the slide piston is reset by the return servo drive from a setting position for a higher speed to a setting position for a reduced speed when a critical load condition occurs.

Bei der Ausführungsform gemäß Anspruch 11 wird durch die Rückstell-Vorrichtung entweder der Schieberkolben aus einer Einstellage für eine höhere Geschwindigkeit zurückgestellt in eine Einstellage für eine niedrige Geschwindigkeit oder wird der Schieberkolbenhub begrenzt.In the embodiment according to claim 11, the reset device either resets the spool from a setting position for a higher speed to a setting position for a low speed or limits the spool stroke.

Bei der Ausführungsform gemäß Anspruch 12 wird das Signal zum Steuern der Mengenreduzierung vom Hebe- oder Knickzylinder oder von einer Arbeitsleitung des Hebe oder Knickzylinders hydraulisch oder elektrisch abgeleitet, und zwar an einer Stelle, an der sich ein unter allen Betriebsbedingungen aussagefähiges Signal abgreifen läßt, das einen kritischen Belastungszustand im Hebezeug repräsentiert.In the embodiment according to claim 12, the signal for controlling the quantity reduction is derived hydraulically or electrically from the lifting or articulating cylinder or from a working line of the lifting or articulating cylinder, at a point at which a signal that is meaningful under all operating conditions can be tapped, the represents a critical load condition in the hoist.

Bei der Ausführungsform gemäß Anspruch 13 kann der Signalgeber an jeder Stelle innerhalb des Aufbaus des Hebezeugs angeordnet sein, an der ein unter allen Umständen aussagefähiges Signal ermittelbar ist. Bei elektronisch abtastbaren Signalgebern ist die Signalübertragung an die Mengenreduziervorrichtung baulich besonders einfach.In the embodiment according to claim 13, the signal transmitter can be arranged at any point within the structure of the hoist at which a signal that is meaningful under all circumstances can be determined. In the case of electronically scanned signal transmitters, the signal transmission to the quantity reduction device is particularly simple in terms of construction.

Anhand der Zeichnung werden Ausführungsformen des Erfindungsgegenstandes erläutert. Es zeigt:

Fig. 1
ein Schema eines Mobilkrans,
Fig. 2
ein Schaubild,
Fig. 3
ein Blockschaltbild einer hydraulischen Steuervorrichtung mit sechs Alternativen Mengenreduzier-Vorrichtungen,
Fig. 4
ein Blockschaltbild einer hydraulischen Steuervorrichtung mit drei Proportionalwegesteuerschiebern, und
Fig. 5
ein Blockschaltbild einer weiteren Ausführungsform.
Embodiments of the subject matter of the invention are explained with the aid of the drawing. It shows:
Fig. 1
a scheme of a mobile crane,
Fig. 2
a graph,
Fig. 3
a block diagram of a hydraulic control device with six alternatives Quantity reduction devices,
Fig. 4
a block diagram of a hydraulic control device with three proportional directional spool, and
Fig. 5
a block diagram of another embodiment.

Bei einem Hebezeug, z.B. einem Mobilkran K, gemäß Fig. 1, ist an einem Mast 1 in einem Gelenk 14 ein Schwenkausleger 2 angeordnet, von dem sich ein verschwenkbarer Teleskopausleger 3 mit einem Ausschiebeteil 3a wegerstreckt, an dem sich ein Greifer 4 (oder ein Lastgeschirr, eine Hubgabel, oder dgl.) befindet. Der Schwenkausleger 2 ist mittels eines Hebezylinders 5 schwenkbar. Zwischen dem Teleskopausleger 3 und dem Schwenkausleger 2 ist ein Knickzylinder 6 eingesetzt. Der Ausschiebeteil 3a läßt sich mit einem Ausschiebezylinder 7 aus- und einfahren. Die Zylinder 5, 6, 7 und der Greifer 4 werden über eine hydraulische Steuervorrichtung (in Fig. 1 nicht gezeigt) angetrieben. In dem Mobilkran K sind als Beispiele mehrere Signalgeber 8, 9, 10, 11, 12 angedeutet, obwohl in der Regel ein Signalgeber reicht. Der Signalgeber 8 tastet den Druck im Ausschieberaum des Hebezylinders 5 ab. Der Signalgeber 9 tastet den Druck im Ausschieberaum des Knickzylinders 6 ab. Der Signalgeber 10 ist ein Wechselventil, das den jeweils höheren Druck im Hebezylinder 5 oder im Knickzylinder 6 als Signal Y wieterleitet. Das Signal Y kann ein hydraulisches Drucksignal oder ein elektrisches Signal sein, das, z.B. über einen Druckschalter, erzeugt wird. Der Signalgeber 11 ist beim Anlenkzapfen 13 des Hebezylinders 5 am Mast 1 angeordnet und als Dehnungsmeßstreifen oder Druckmeßdose oder ähnliches elektronisch abtastbares Element ausgebildet. Der Signalgeber 12 ist beim Gelenk 14 zwischen dem Mast 1 und dem Schwenkausleger 2 angeordnet und als Dehnungsmeßstreifen oder dgl. elektronisch abtastbar.In the case of a hoist, for example a mobile crane K, according to FIG. 1, a swivel boom 2 is arranged on a mast 1 in a joint 14, from which a pivotable telescopic boom 3 extends with an extension part 3a, on which a gripper 4 (or a Load harness, a lifting fork, or the like. The swing arm 2 can be pivoted by means of a lifting cylinder 5. An articulated cylinder 6 is inserted between the telescopic boom 3 and the swivel boom 2. The extension part 3a can be extended and retracted with an extension cylinder 7. The cylinders 5, 6, 7 and the gripper 4 are driven by a hydraulic control device (not shown in FIG. 1). In the mobile crane K, several signal transmitters 8, 9, 10, 11, 12 are indicated as examples, although one signal transmitter is usually sufficient. The signal generator 8 senses the pressure in the push-out space of the lifting cylinder 5. The signal generator 9 senses the pressure in the push-out space of the articulated cylinder 6. The signal generator 10 is a shuttle valve which transmits the higher pressure in the lifting cylinder 5 or in the articulated cylinder 6 as signal Y. The signal Y can be a hydraulic pressure signal or be an electrical signal that is generated, for example via a pressure switch. The signal generator 11 is arranged at the pivot pin 13 of the lifting cylinder 5 on the mast 1 and is designed as a strain gauge or pressure sensor or similar electronically scannable element. The signal generator 12 is arranged at the joint 14 between the mast 1 and the swivel arm 2 and electronically scanned as a strain gauge or the like.

Ein oder mehrere Signalgeber werden benutzt, um in der hydraulischen Steuervorrichtung V, z.B. gemäß Fig. 3, eine Mengenreduzier-Vorrichtung M zu steuern. In Fig. 3 sind in sechs durch strichpunktierte Linien voneinander getrennten Einheiten unterschiedliche Ausführungsformen von Mengenreduzier-Vorrichtungen gezeigt. Die Fig. 4 und 5 verdeutlichen weitere Variationsmöglichkeiten für Mengenreduzier-Vorrichtungen M.One or more signal generators are used to operate in the hydraulic control device V, e.g. 3 to control a quantity reduction device M. In FIG. 3, different embodiments of quantity-reducing devices are shown in six units separated by dash-dotted lines. 4 and 5 illustrate further possible variations for quantity reducing devices M.

Kern jeder Einheit in Fig. 3 ist ein Proportionalwegesteuerschieber S1 bis S6 mit zugeordneter Zulaufregel-Druckwaage Z für eine lastunabhängige Geschwindigkeitssteuerung. Der jeweils vom Proportionalwegesteuerschieber S1 bis S6 angesteuerte Hydroverbraucher (z.B. die Zylinder 5, 6, 7 in Fig. 1) bewegt sich unabhängig von der Last mit einer Geschwindigkeit, die sich ausschließlich nach der Verstellung des Proportionalwegesteuerschiebers richtet. Erreicht wird dies dadurch, daß die Zulaufregel-Druckwaage Z das am Proportionalwegesteuerschieber eingestellte Druckgefälle unabhängig von der Belastung konstant hält.At the core of each unit in FIG. 3 is a proportional travel control slide valve S1 to S6 with an associated inlet control pressure compensator Z for load-independent speed control. The hydraulic consumer controlled by the proportional travel control spool S1 to S6 (e.g. cylinders 5, 6, 7 in Fig. 1) moves independently of the load at a speed which is based solely on the adjustment of the proportional travel control spool. This is achieved in that the inlet control pressure compensator Z keeps the pressure drop set on the proportional travel control valve constant regardless of the load.

Jeder Proportionalwegesteuerschieber S1 bis S6 ist über eine Abzweig-Druckleitung 15a an eine gemeinsame Druckleitung 15 angeschlossen, in der die Zulaufregel-Druckwaage Z angeordnet ist. Eine gemeinsame Rücklaufleitung 16 ist über Abzweig-Rücklaufleitungen 16a an alle Porportionalwegesteuerschieber S1 bis S6 angeschlossen. Von den Proportionalwegesteuerschiebern S1 bis S6 führen jeweils zwei Arbeitsleitungen 17, 18 zum Hydromotor. Bei einem nur in einer Richtung beaufschlagbaren und in Gegenrichtung unter Last verstellbaren Hydromotor wäre nur eine Arbeitsleitung 17 oder 18 vorgesehen. Die in Fig. 3 gezeigten Proportionalwegesteuerschieber S1 bis S6 weisen manuelle Verstellvorrichtungen 19 auf, mit denen ein Schieberkolben 21 aus einer Nullstellung gegen eine Rückstellfedereinrichtung 20 in zwei Steuerstellungen a und b verstellbar ist. Eine den jeweiligen Lastdruck führende Steuerleitung 22 ist an die Aufsteuerseite der Zulaufregel-Druckwaage Z angeschlossen. Die Steuerleitung 22 ist über eine Blende 23 an über den Schieberkolben 21 an die Arbeitsleitungen 17, 18 anschließbare Abzapfleitungen 24a, 24b angeschlossen. Eine Steuerleitung 25 verbindet die Abzapfleitungen 24a, 24b über ein Wechselventil 26 mit einer gemeinsamen Hauptsteuerleitung 27, die zu einer Regelvorrichtung einer Konstantpumpe oder einer Regelpumpe (nicht gezeigt) zum Einstellen des Drucks in der Druckleitung 15 führt. Eine gemeinsame Rücklaufsteuerleitung 28 ist mit einem Tank verbunden. Eine weitere Steuerleitung 29 ist im Betrieb der Steuervorrichtung mit einem konstanten Steuerdruck beaufschlagt, z.B. mit 25 Bar.Each proportional travel control valve S1 to S6 is connected via a branch pressure line 15a to a common pressure line 15, in which the inlet control pressure compensator Z is arranged. A common return line 16 is connected via branch return lines 16a to all proportional directional control spools S1 to S6. Two working lines 17, 18 each lead from the proportional travel control spools S1 to S6 to the hydraulic motor. In the case of a hydraulic motor which can only be acted upon in one direction and adjustable in the opposite direction under load, only one working line 17 or 18 would be provided. The proportional travel control slides S1 to S6 shown in FIG. 3 have manual adjustment devices 19, with which a slide piston 21 can be adjusted from a zero position against a return spring device 20 into two control positions a and b. A control line 22 carrying the respective load pressure is connected to the control side of the inlet control pressure compensator Z. The control line 22 is connected via an orifice 23 to bleed lines 24a, 24b which can be connected to the working lines 17, 18 via the slide piston 21. A control line 25 connects the bleed lines 24a, 24b via a shuttle valve 26 to a common main control line 27, which leads to a control device of a constant pump or a control pump (not shown) for adjusting the pressure in the pressure line 15. A common return control line 28 is connected to a tank. A further control line 29 is subjected to a constant control pressure during operation of the control device, for example 25 bar.

In der Zulaufregel-Druckwaage Z ist ein Regelorgan 30 stufenlos zwischen einer Durchgangsstellung und einer Absperrstellung verstellbar. In Richtung auf die Durchgangsstellung wird das Regelorgan 30 vom Druck in der Steuerleitung 22 und von einer Regelfeder 31 beaufschlagt. In der Gegenrichtung wird das Regelorgan 30 über eine Hilfssteuerleitung 32 mit einer Blende vom Druck in der Druckleitung 15a stromab der Zulaufregel-Druckwaage Z beaufschlagt.In the inlet regulating pressure compensator Z, a regulating member 30 is continuously adjustable between a through position and a shut-off position. In the direction of the through position, the control element 30 is acted upon by the pressure in the control line 22 and by a control spring 31. In the opposite direction, the control element 30 via an auxiliary control line 32 with an orifice from the pressure in the pressure line 15a downstream of the inlet control pressure compensator Z.

Die Mengenreduzier-Vorrichtung M weist für den Porportionalwegesteuerschieber S1, z.B. des Hebezylinders 5 von Fig. 1, ein Regel- oder Schaltventil 33 mit einer fest eingestellten oder variablen Blende 34 auf, die bei Auftreten des Signals Y in die Druckleitung 15a zuschaltbar ist. Das Regel- oder Schaltventil 33 kann durch einen Magneten 35 betätigt werden, dem das Signal Y in elektrischer Form zugeführt wird. Es ist aber auch möglich, das Regel- oder Schaltventil 33 durch ein hydraulisches Drucksignal zu schalten. In der Nullstellung läßt sich die Steuerleitung 22 über eine Hilfsrücklaufleitung 41 zur Rücklaufleitung 16 entlasten.The quantity reducing device M has for the proportional directional control valve S1, e.g. of the lifting cylinder 5 of FIG. 1, a control or switching valve 33 with a fixed or variable orifice 34, which can be activated when the signal Y occurs in the pressure line 15a. The control or switching valve 33 can be actuated by a magnet 35, to which the signal Y is supplied in electrical form. However, it is also possible to switch the control or switching valve 33 by means of a hydraulic pressure signal. In the zero position, the control line 22 can be relieved via an auxiliary return line 41 to the return line 16.

Bei Normalbetrieb ist die Blende 34 nicht wirksam. Die Geschwindigkeit wird durch die Einstellage des Schieberkolbens 21 bestimmt. Die Druckdifferenz über den Schieberkolben 21 wird von der Zulaufregel-Druckwaage konstant gehalten. Bei Auftreten des Signals Y wird die Blende 34 zugeschaltet. Dies bedeutet eine Mengenreduzierung und damit eine Geschwindigkeitsverringerung für den Hydroverbraucher. Anhand der Kurve von Fig. 2 ist zu ersehen, wie (ausgezogene Kurve) die Menge Q über den Hubweg des Schieberkolbens 21 ohne die zugeschaltete Blende 34 zunimmt. Die strichlierte Kurve 20% bedeutet, daß ab Zuschalten der Blende 34 in jedem Punkt des Hubwegs des Schieberkolbens 21 nur mehr 20% der ursprünglichen Menge strömen. Wird, wie in Fig. 3 in der ersten Einheit angedeutet, ein Regelventil oder eine variable Blende 34 verwendet, dann läßt sich die Zuschaltung der Blende 34 stufenlos vornehmen und eine den jeweiligen Anforderungen angepaßte Mengenkurve einstellen, z.B. wie strichpunktiert in Fig. 2 bei "var" angedeutet.The aperture 34 is not effective during normal operation. The speed is determined by the setting position of the slide piston 21. The pressure difference across the spool 21 is kept constant by the inlet control pressure compensator. When signal Y occurs, the aperture 34 is switched on. This means a reduction in volume and thus a reduction in speed for the hydraulic consumer. The curve of FIG. 2 shows how (solid curve) the quantity Q increases over the stroke of the slide piston 21 without the orifice plate 34 being switched on. The dashed curve 20% means that only 20% of the original amount will flow in each point of the stroke of the slide piston 21 after the orifice 34 has been switched on. If, as indicated in FIG. 3 in the first unit, a control valve or a variable orifice 34 is used, then the orifice 34 can be switched on continuously and one for each Set the quantity curve adapted to the requirements, for example as indicated by the dot-dash line in FIG. 2 at "var".

Für den zweiten Proportionalwegesteuerschieber S2 weist die Mengenreduzier-Vorrichtung M einen Servo-Stellantrieb 36 für die Regelfeder 31 der Zulaufrege-Druckwaage Z auf, um die Vorspannung der Regelfeder zur Mengenreduzierung zurückzunehmen. Ein gegen eine Rückstellfeder verschiebbarer Federspannkolben wird mit einem Schaltventil 37 gesteuert, das über eine Hilfssteuerleitung 38 an die Steuerleitung 28 und über eine weitere Hilfssteuerleitung 39 an die Druckleitung 15a angeschlossen ist. Falls das Schaltventil einen Magneten 35 aufweist, wird dieser über das Signal Y erregt, um die Vorspannung der Regelfeder 31 zurückzunehmen. Dies kann in einer Stufe aber auch stufenlos erfolgen. Durch die Zurücknahme der Federvorspannung wird die Regel-Druckdifferenz kleiner und die Mengenreduzierung in beiden Arbeitsleitungen 17, 18 prozentual gleich. Eine weitere Hilfssteuerleitung 40 verbindet die Druckseite des Federspannkolbens mit dem Ausgang des Schaltventils 37.For the second proportional travel control slide S2, the quantity reduction device M has a servo actuator 36 for the control spring 31 of the inlet control pressure compensator Z in order to reduce the preload of the control spring in order to reduce the quantity. A spring-loaded piston displaceable against a return spring is controlled with a switching valve 37 which is connected to the control line 28 via an auxiliary control line 38 and to the pressure line 15a via a further auxiliary control line 39. If the switching valve has a magnet 35, this is excited via the signal Y in order to remove the bias of the control spring 31. This can also be done continuously in one step. By reducing the spring preload, the control pressure difference becomes smaller and the quantity reduction in both working lines 17, 18 is the same in percentage terms. Another auxiliary control line 40 connects the pressure side of the spring-loaded piston to the outlet of the switching valve 37.

Beim dritten Proportionalwegesteuerschieber S3 ist die Mengenreduzier-Vorrichtung M mit einem Sekundär-Druckbegrenzungsventil 43 ausgestattet, das in einer an die Steuerleitung 22 angeschlossenen Hilfssteuerleitung 42 zur Rücklaufleitung 16a angeordnet und auf einen einen kritischen Belastungszustand, z.B. im Hydroverbraucher repräsentierenden Druckwert in der Steuerleitung 22 eingestellt ist. Stromauf des Sekundär-Drucknegrenzungsventils 43 ist eine Blende 44 vorgesehen. Das Sekundär-Druckgegrenzungsventil 43 hat - mit oder ohne Blende 44 - eine mit steigender Durchflußmenge steigende Druckkennlinie, damit ab Ansprechen mit zunehmendem Lastdruck eine zunehmende Menge über das Ventil 43 abfließt. Die Mengenreduzier-Vorrichtung M wirkt in beiden Bewegungsrichtungen des Hydroverbrauchers.In the third proportional travel control slide S3, the quantity reducing device M is equipped with a secondary pressure limiting valve 43, which is arranged in an auxiliary control line 42 connected to the control line 22 to the return line 16a and is set to a pressure value in the control line 22 which represents a critical load state, for example in the hydraulic consumer . An orifice 44 is provided upstream of the secondary pressure relief valve 43. The secondary pressure relief valve 43 has - with or without an orifice 44 - a pressure characteristic curve that increases with an increasing flow rate, and thus from response with increasing load pressure an increasing amount flows through the valve 43. The quantity reducing device M acts in both directions of movement of the hydraulic consumer.

Beim vierten Proportionalwegesteuerschieber S4 ist die Mengenreduzier-Vorrichtung M analog der des dritten Proportionalwegesteuerschiebers S3 ausgebildet und mit einem Sekundärdruckventil 43 und einer vorgeschalteten Blende 44 in der Hilfssteuerleitung 42' ausgestattet. Diese Mengenreduzier-Vorrichtung M ist nur in einer Bewegungsrichtung des Hydromotors wirksam, nämlich in der Steuerstellung a des Proportionalwegesteuerschiebers S4. Die Hilfssteuerleitung 42' ist zu diesem Zweck über einen Durchgang 45 im Schieberkolben 21 geführt, der nur in der Steuerstellung a offen ist. In der Neutralstellung und in der Steuerstellung b ist dieser Durchgang gesperrt.In the fourth proportional travel control spool S4, the quantity reduction device M is designed analogously to that of the third proportional travel control spool S3 and is equipped with a secondary pressure valve 43 and an upstream orifice 44 in the auxiliary control line 42 '. This quantity reduction device M is only effective in one direction of movement of the hydraulic motor, namely in the control position a of the proportional travel control spool S4. For this purpose, the auxiliary control line 42 'is guided through a passage 45 in the slide piston 21, which is only open in the control position a. This passage is blocked in the neutral position and in the control position b.

Beim fünften Proportionalwegesteuerschieber S5 arbeitet die Mengenreduzier-Vorrichtung M mit druckunabhängiger Leckage und nur in einer Bewegungsrichtung. Die Hilfssteuerleitung 42, die über den Durchgang 45 im Schieberkolben 21 zu einem Tank T geführt ist, enthält einen Zweiwegeregler 46, dem ein Schalt- oder Regelventil 47 zugeordnet, z.B. nachgeschaltet, ist. Bei Auftreten des Signals Y wird das Regel- oder Schaltventil 47 verstellt, so daß über den Zweiwegeregler 46 eine druckunabhängige Leckage auftritt, die in der Steuerstellung a des Schieberkolbens 21 zur Mengenreduzierung führt.In the fifth proportional travel control spool S5, the quantity reduction device M works with pressure-independent leakage and only in one direction of movement. The auxiliary control line 42, which is led through the passage 45 in the spool 21 to a tank T, contains a two-way controller 46 to which a switching or control valve 47 is assigned, e.g. downstream, is. When signal Y occurs, the control or switching valve 47 is adjusted so that a pressure-independent leakage occurs via the two-way controller 46, which leads to a reduction in the quantity in the control position a of the spool 21.

Beim sechsten Proportionalwegesteuerschieber S6 sind zwei Varianten Mengenreduzier-Vorrichtung M angedeutet. Bei der einen Variante ist bei dem manuell mittels der Verstelleinrichtung 19 verstellbaren Schieberkolben 21 ein Rückstell-Servoantrieb 48 vorgesehen, der über ein mit dem Signal Y steuerbares Ventil 49 eingreift. Das Ventil 49 ist an eine Tanksteuerleitung 51 und über eine Leitung 50 die Steuerleitung 29 (die einen konstanten Druck führt) angeschlossen. Sobald das Signal Y auftritt, wird der Rückstell-Servoantrieb aktiviert und der Schieberkolben 21 entweder aus der zuvor gewählten Einstellung zurückgeschoben oder überhaupt gegen ein weiteres Verstellen gehindert. Soll die Mengenreduzier-Vorrichtung in beiden Bewegungsrichtungen arbeiten, dann sind zwei entgegengesetzt wirkende Rückstell-Servoantriebe 48 erforderlich.In the sixth proportional directional control valve S6, two variants of the quantity reducing device M are indicated. In one variant, the slide piston 21, which is manually adjustable by means of the adjusting device 19, is a reset servo drive 48 is provided which engages via a valve 49 controllable with the signal Y. The valve 49 is connected to a tank control line 51 and, via a line 50, the control line 29 (which carries a constant pressure). As soon as the signal Y occurs, the reset servo drive is activated and the spool 21 is either pushed back from the previously selected setting or is prevented from any further adjustment at all. If the quantity reduction device is to work in both directions of movement, then two counter-acting return servo drives 48 are required.

Ist der Schieberkolben 21 - wie häufig üblich - hydraulisch oder elektrohydraulisch vorgesteuert (angedeutet bei 61), z.B. über ein elektromagnetisch (Magnet 54a) verstellbares Druckminderventil 54 in einer Steuerleitung 52, dann kann in die Steuerleitung 52 ein weiteres Druckminderventil 56 eingesetzt sein, das mittels des Signals Y aktiviert wird und den Druck zum Verstellen des Schieberkolbens 21 reduziert. Das weitere Druckminderventil 55 kann entweder hydraulisch oder elektromagnetisch angesteuert werden. Bei beiden Varianten ist sichergestellt, daß die Geschwindigkeit des Hydromotors ab Auftreten eines Signals Y verringert wird oder die geringe Geschwindigkeit nicht überschritten wird.If the spool 21 - as is often the case - is hydraulically or electro-hydraulically piloted (indicated at 61), e.g. Via an electromagnetic (magnet 54a) adjustable pressure reducing valve 54 in a control line 52, a further pressure reducing valve 56 can then be inserted into the control line 52, which is activated by the signal Y and reduces the pressure for adjusting the slide piston 21. The further pressure reducing valve 55 can be controlled either hydraulically or electromagnetically. In both variants it is ensured that the speed of the hydraulic motor is reduced from the occurrence of a signal Y or that the low speed is not exceeded.

In Fig. 4 sind drei Proportionalwegesteuerschieber S5, S7 und S8 gezeigt. Der erste Proportionalwegesteuerschieber S5 entspricht dem Proportionalwegesteuerschieber S5 von Fig. 3, mit dem Unterschied, daß auch eine elektrohydraulische Vorsteuerung 61 vorgesehen ist, die an die Steuerleitung 29 und die Steuerleitung 28 (zum Tank) angeschlossen ist. Jede Mengenreduzier-Vorrichtung M weist in der Hilfssteuerleitung 42 zu einer gemeinsamen Sammelsteuerleitung 57 einen Zweiwegeregler 46 mit einem Rückschlagventil 58 auf, das zweckmäßigerweise federbelastet ist und in Strömungsrichtung zur Sammelsteuerleitung 57 öffnet. Bei jedem Proportionalwegesteuerschieber S5, S7, S8 wird die Menge in beiden Bewegungsrichtungen reduziert, wenn die Mengenreduzier-Vorrichtung anspricht. In der Sammelsteuerleitung 57 ist ein Schaltventil 59 mit einem Betätiger 60, z.B. einem Schaltmagneten, vorgesehen, das zwischen einer Durchgangs- und einer Absperrstellung schaltbar ist. In Fig. 4 ist das Schaltventil 59 ein 2/2-Wegeschaltventil oder ein magnetisch sperrbares Rückschlagventil 62. Sobald das Signal Y auftritt, wird das Schaltventil 59 in die Durchgangsstellung gestellt. In der Durchgangsstellung tritt über den Zweiwegeregler 46 des zum kritischen Belastungszustand beitragenden Proportionalwegesteuerschiebers S5, S7 oder S8 eine druckunabhängige Leckage ein, die zum Verringern der Menge führt, weil die jeweilige Zulaufregel-Druckwaage Z nur mehr eine verringerte Menge zuteilt.4 shows three proportional directional control spools S5, S7 and S8. The first proportional travel control spool S5 corresponds to the proportional travel control spool S5 of FIG. 3, with the difference that an electro-hydraulic pilot control 61 is also provided, which is connected to the control line 29 and the control line 28 (to the tank). Any quantity reduction device M has in the auxiliary control line 42 to a common collective control line 57 a two-way controller 46 with a check valve 58, which is expediently spring-loaded and opens in the flow direction to the collective control line 57. With each proportional travel control spool S5, S7, S8, the quantity is reduced in both directions of movement when the quantity reduction device responds. In the collective control line 57 there is a switching valve 59 with an actuator 60, for example a switching magnet, which can be switched between a through position and a shut-off position. 4, the switching valve 59 is a 2/2-way switching valve or a magnetically lockable check valve 62. As soon as the signal Y occurs, the switching valve 59 is put into the open position. In the open position, a pressure-independent leak occurs via the two-way controller 46 of the proportional travel control spool S5, S7 or S8, which contributes to the critical load state, which leads to a reduction in the quantity because the respective inlet control pressure compensator Z now only allocates a reduced quantity.

Damit bei der Geschwindigkeitsverringerung auftretende Druck- oder Lastschwankungen oder eine nicht gewillte Änderung des Signals Y zum sofortigen Zurückstellen des Schaltventils 59 führen, ist das Schaltventil 59 mit einer verstärkten Schalthysteresis ausgelegt. Bei Ansteuerung mittels eines elektrischen Signals Y kann ein Zeitrelais benutzt werden, das das Signal eine voreinstellbare Zeitdauer hält und die Mengenreduzierung erst aufhebt, wenn die Signaländerung über die eingestellte Zeitdauer hinaus bleibt.The switching valve 59 is designed with an increased switching hysteresis so that pressure or load fluctuations occurring during the speed reduction or an unwanted change in the signal Y lead to the switching valve 59 being reset immediately. When actuated by means of an electrical signal Y, a time relay can be used which holds the signal for a pre-settable time period and does not cancel the quantity reduction until the signal change remains beyond the set time period.

Bei der hydraulischen Steuervorrichtung V gemäß Fig. 5 sind zwei Proportionalwegesteuerschieber S5 und S7 für den Hebezylinder 5 und den Knickzylinder 6 eines Mobilkrans an die Druck- und Rücklaufleitung angeschlossen, an die auch weitere, nicht dargestellte Wegesteuerschieber angeschlossen sein können. Für die Senkbewegung des Hebezylinders 5 ist ein Lasthalteventil 65 in der Arbeitsleitung 18 vorgesehen, das aus der Arbeitsleitung 17 aufsteuerbar ist. Beim Knickzylinder 6 sind in beiden Arbeitsleitungen Lasthalteventile enthalten. Als Signalgeber für das Drucksignal Y dient die Arbeitsleitung 18, an die zwischen dem Lasthalteventil 65 und dem Hebezylinder 5 die Steuerleitung 64 angeschlossen ist. Die Mengenreduzier-Vorrichtungen M beider Proportionalwegesteuerschieber S5, S7 sind ähnlich ausgelegt wie in Fig. 4, d.h. die Hilfssteuerleitung 42 führt zur Steuerleitung 57. In jeder Hilfssteuerleitung 42 ist ein Zweiwegeregler 46 mit zugeordnetem Rückschlagventil 58 vorgesehen. Der Zweiwegeregler 46 ermöglicht eine druckunabhängige Leckage, sobald bei Auftreten eines Signals Y in der Steuerleitung 64 das Schaltventil 59 auf Durchgang schaltet. Das Schaltventil 59 kann ein sogenannter Schnapphalter oder ein Ventil 63 mit hydraulischer Selbsthaltung sein, das z.B. seine jeweilige Stellung, z.B. bei Wegfall des Drucksignals Y, noch eine vorbestimmte Zeitdauer hält. Die Rückschlagventile 58 verhindern, daß der in der Sammelsteuerleitung 57 herrschende Druck in eine Steuerleitung 22 mit niedrigerem Steuerdruck zurückwirkt.In the hydraulic control device V according to FIG. 5 two proportional directional control spools S5 and S7 for the lifting cylinder 5 and the articulated cylinder 6 of a mobile crane are connected to the pressure and return line, to which further directional control spools, not shown, can also be connected. For the lowering movement of the lifting cylinder 5, a load holding valve 65 is provided in the working line 18, which can be opened from the working line 17. With the articulated cylinder 6, load holding valves are included in both working lines. The working line 18, to which the control line 64 is connected between the load holding valve 65 and the lifting cylinder 5, serves as the signal generator for the pressure signal Y. The quantity-reducing devices M of both proportional travel control spools S5, S7 are designed similarly to FIG. 4, ie the auxiliary control line 42 leads to the control line 57. In each auxiliary control line 42, a two-way controller 46 with an associated check valve 58 is provided. The two-way controller 46 enables pressure-independent leakage as soon as the switching valve 59 switches to passage when a signal Y occurs in the control line 64. The switching valve 59 can be a so-called snap holder or a valve 63 with hydraulic self-holding, which, for example, holds its respective position, for example when the pressure signal Y disappears, for a predetermined period of time. The check valves 58 prevent the pressure prevailing in the collective control line 57 from acting back into a control line 22 with a lower control pressure.

Schaltet der Steuerdruck in der Steuerleitung 64 (Drucksignal Y) das Schaltventil 59 in die Durchgangsstellung, dann wird dem Hebezylinder 5 nur die reduzierte Menge zugeführt, so daß er sich mit verringerter Geschwindigkeit bewegt. Wird hingegen der Proportionalwegesteuerschieber S7 verstellt, um den Knickzylinder 6 zu bewegen, dann wird wegen der druckunabhängigen Leckage über den Zweiwegeregler 46 die dem Knickzylinder 6 zugeleitete Menge reduziert. Werden beide Proportionalwegesteuerschieber S5, S7 betätigt, dann wird entweder bei beiden Zylindern 5, 6 nur eine geringe verminderte Bewegungsgeschwindigkeit zugelassen oder nur bei demjenigen der beiden Zylinder, der für den kritischen Belastungszustand verantwortlich ist.If the control pressure in the control line 64 (pressure signal Y) switches the switching valve 59 into the through position, then only the reduced amount is fed to the lifting cylinder 5, so that it moves at a reduced speed. However, the proportional directional control spool becomes S7 adjusted to move the articulated cylinder 6, then the amount fed to the articulated cylinder 6 is reduced due to the pressure-independent leakage via the two-way controller 46. If both proportional travel control spools S5, S7 are actuated, then only a slight reduced movement speed is permitted for both cylinders 5, 6 or only for that of the two cylinders which is responsible for the critical load condition.

Das bei den Steuervorrichtungen V gemäß den Fig. 4 und 5 die jeweilige Mengenreduzier-Vorrichtung M steuernde Signal Y kann auch von jedem der in Fig. 1 angedeuteten Signalgeber oder auch von einem weiteren, nicht gezeigten, aber einen kritischen Belastungszustand aussagefähig repräsentierenden externen Signalgeber stammen. Die Komponenten der jeweils benutzen Mengen-Reduziervorrichtungen M können entweder in den Proportionalwegesteuerschieber integriert oder an dessen Gehäuse oder im üblicherweise vorgesehenen Anschlußblock vorgesehen werden. Die Proportionalwegesteuerschieber können deshalb auch nachträglich im Hinblick auf die Geschwindigkeitsverringerungsfunktion umgerüstet werden. Grundsätzliche Modifkationen der Proportionalwegesteuerschieber sind hierfür nicht erforderlich.The signal Y controlling the respective quantity reducing device M in the control devices V according to FIGS. 4 and 5 can also come from any of the signal transmitters indicated in FIG. 1 or also from another external signal transmitter not shown but meaningfully representing a critical load condition . The components of the quantity reducing devices M used in each case can either be integrated in the proportional directional control slide valve or can be provided on its housing or in the connection block which is usually provided. The proportional directional control spool can therefore also be retrofitted with regard to the speed reduction function. Basic modifications of the proportional directional spool are not necessary for this.

Claims (13)

  1. Hydraulic control device (V) for at least one hydraulic user (5, 6) in a lifting gear (K), in particular in a mobile crane, having a proportional directional control valve (S1 to S8) which, on the one hand, is connected to a pressure line (15, 15a) and to a return line (16, 16a) and, on the other hand, to two working lines (17, 18) to the hydraulic user and has a valve piston (21), which can be adjusted by a manual or a pilot-controlled adjusting device, for speed control up to a predetermined maximum speed and for directional control of the hydraulic user (5, 6), and having a meter-in control compensator (Z) which is connected upstream of the proportional directional control valve (S1 to S8) in the pressure line (15a) and can be acted upon in the opening direction depending on the load pressure from a control line (22) and by a control spring (31) and, in contrast, in the closing direction from the pressure line (15a), it being possible for the speed of movement of the hydraulic user (5, 6) to be preselected independently of the load with the respective setting of the valve piston (21), characterized in that a quantity-reducing device (M) which is separate from the valve piston (21) in terms of construction is provided in the control device (V), in that the quantity-reducing device (M) can be moved, on account of a signal (Y) representing a load state of the lifting gear (A) which is critical owing to the preselected speed, into engagement which limits the quantity of the hydraulic medium flowing to the hydraulic user (5, 6) and thus solely reduces the preselected speed, and in that the quantity-reducing device (M) acts between the meter-in control compensator (Z) and the proportional directional control valve (S1) or on the meter-in control compensator (Z) of the proportional directional control valve (S2, S3, S4, S5, S7, S8) or on the valve piston (21) of the proportional directional control valve (S6) when the signal (Y) occurs.
  2. Hydraulic control device according to Claim 1, characterized in that the quantity-reducing device (M) has an orifice plate (34), which can be connected, in the pressure line (15a) downstream of the meter-in control compensator (Z), preferably in a 2/2 directional switching valve or in a 2/2 directional control valve (33), and in that the connection of the orifice plate can be controlled, preferably in at least one stage or infinitely variably, by means of the signal (Y) of a signal transmitter (8, 9, 10, 11, 12) or in the control line (22).
  3. Hydraulic control device according to Claim 1, characterized in that the quantity-reducing device (M) has a servo-adjusting drive (36) which changes the prestress of the control spring (31) of the meter-in control compensator (Z) and can be actuated by means of the signal (Y), preferably in at least one stage or infinitely variably.
  4. Hydraulic control device according to Claim 3, characterized in that the servo-adjusting drive (36) has a spring-tension piston which can be hydraulically adjusted counter to the force of a restoring spring and whose actuation side can be connected selectively to the pressure line (15a) or the return line (16) via a 3/2 directional switching valve (37), and in that the 3/2 directional switching valve (37) can be controlled electromagnetically or hydraulically.
  5. Hydraulic control device according to Claim 1, characterized in that the quantity-reducing device (M) has a secondary pressure-reducing valve (43) which is connected to the control line (22), is connected to the return line (16), and can be controlled to open by means of the signal (Y) in the control pressure line (22), in that an orifice plate (44) is provided in the control line (22) between the secondary pressure-reducing valve (43) and the meter-in control compensator (Z), and/or in that the secondary pressure-reducing valve (43) has a pressure characteristic which rises with an increasing throughflow quantity.
  6. Hydraulic control device according to Claim 5, characterized in that the secondary pressure-reducing valve (43) is arranged with the orifice plate (44) in at least one auxiliary control line (42, 42') which branches off from the control line (22) of the meter-in control compensator (Z), and in that the auxiliary control line (42') is routed via the proportional directional control valve (S4) and can be switched in the latter only to a control position (a) of the valve piston (21) for passage.
  7. Hydraulic control device according to Claim 1, characterized in that the quantity-reducing device (M) has a two-directional flow controller (46) which leads to the return line (16) and to which the control line (22) can be connected directly via an auxiliary control line (42) or via a passage (45) in the valve piston (21) which is only open in one control position of the proportional directional control valve (S5, S6, S7, S8), and in that, for the two-directional flow controller (46), a switching or control valve (47, 59) is provided, which can be controlled by the signal (Y) of a signal transmitter (64) or in the control line (22).
  8. Hydraulic control device according to Claim 7, characterized in that the switching valve (47, 59, 63) is designed with an increased switching hysteresis or with hydraulic self-holding.
  9. Hydraulic control device according to at least one of Claims 1 to 8, characterized in that a plurality of proportional directional control valves (S6 to S8) which are connected in parallel to the pressure line (15) and to the return line (16) are provided in the control device (V), each having a meter-in control compensator (Z), each having an auxiliary control line (42) which branches off from the control line (22) with a two-directional controller (46) and a nonreturn valve (58) which is arranged upstream or downstream of the latter and opens for return flow (T), in that the two-directional controllers (46) are connected to a common return collector line (57) to a tank (T), in that the return collector line (57) contains, ahead of the tank (T), a 4/2 directional switching valve (63) or a magnetic switching valve (62), and in that the said valve (63 or 62) can be actuated by means of the signal (Y).
  10. Hydraulic control device according to Claim 1, characterized in that the quantity-reducing device (M) has at least one hydraulically or electrically controllable partial restoring servo drive (48) for the valve piston (21) which can be adjusted manually from a zero position counter to the force of a restoring spring.
  11. Hydraulic control device according to Claim 1, characterized in that, for the valve piston (21) which can be adjusted hydraulically or electrohydraulically from a zero position counter to the force of a restoring spring, the quantity-reducing device (M) has at least one electrical or electrohydraulic restoring device (55) which returns the valve piston (21) in the direction of the zero position or reduces the setting pressure for the valve piston (21) when the signal (Y) occurs.
  12. Hydraulic control device according to at least one of Claims 1 to 11, characterized in that the signal (Y) can be generated by means of a signal transmitter (8, 9, 10, 11, 12) which is a hydraulic or electrical pressure sensor in a lifting or pivoting cylinder (5, 6) or in a working line (18) of the lifting cylinder (5) or the pivoting cylinder (6) of the lifting gear designed as a mobile crane (K).
  13. Hydraulic control device according to Claim 12, characterized in that the signal transmitter (11, 12) is an electronically scannable strain gauge or a pressure sensor in a joint (14), which provides significant information regarding a critical load state of the lifting gear or in an attachment point (13) within the lifting gear construction, e.g. in the attachment stalk of the lifting or pivoting cylinder (5, 6).
EP93120202A 1992-12-23 1993-12-15 Hydraulic control system Expired - Lifetime EP0603722B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4243973A DE4243973C1 (en) 1992-12-23 1992-12-23 Hydraulic control device
DE4243973 1992-12-23

Publications (2)

Publication Number Publication Date
EP0603722A1 EP0603722A1 (en) 1994-06-29
EP0603722B1 true EP0603722B1 (en) 1997-04-23

Family

ID=6476465

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93120202A Expired - Lifetime EP0603722B1 (en) 1992-12-23 1993-12-15 Hydraulic control system

Country Status (4)

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EP (1) EP0603722B1 (en)
AT (1) ATE152213T1 (en)
DE (2) DE4243973C1 (en)
DK (1) DK0603722T3 (en)

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DE29515829U1 (en) * 1995-10-05 1995-11-30 Heilmeier & Weinlein Fabrik für Oel-Hydraulik GmbH & Co KG, 81673 München Hydraulic control device and two-way control valve
DE29611525U1 (en) 1996-07-02 1996-09-05 Heilmeier & Weinlein Fabrik für Oel-Hydraulik GmbH & Co KG, 81673 München Hydraulic control device
DE29611526U1 (en) * 1996-07-02 1996-09-05 Heilmeier & Weinlein Fabrik für Oel-Hydraulik GmbH & Co KG, 81673 München Hydraulic control device
KR100527378B1 (en) * 2003-06-25 2005-11-09 볼보 컨스트럭션 이키프먼트 홀딩 스웨덴 에이비 hydraulic circuit of option device of heavy equipment of having spool boom joint
KR100559291B1 (en) * 2003-06-25 2006-03-15 볼보 컨스트럭션 이키프먼트 홀딩 스웨덴 에이비 hydraulic circuit of option device of heavy equipment
DE102006060334B4 (en) * 2006-12-20 2011-08-25 Sauer-Danfoss Aps Hydraulic valve arrangement
EP2157320B1 (en) * 2008-08-20 2010-12-08 HAWE Hydraulik SE Hydraulic device for a hydro motor
CN109306976B (en) * 2018-11-05 2023-05-23 无锡市钻通工程机械有限公司 Load sensitive control system

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Also Published As

Publication number Publication date
DK0603722T3 (en) 1997-09-08
DE4243973C1 (en) 1994-07-07
ATE152213T1 (en) 1997-05-15
EP0603722A1 (en) 1994-06-29
DE59306264D1 (en) 1997-05-28

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