EP0499694B1 - Hydraulic control device - Google Patents

Hydraulic control device Download PDF

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Publication number
EP0499694B1
EP0499694B1 EP91119267A EP91119267A EP0499694B1 EP 0499694 B1 EP0499694 B1 EP 0499694B1 EP 91119267 A EP91119267 A EP 91119267A EP 91119267 A EP91119267 A EP 91119267A EP 0499694 B1 EP0499694 B1 EP 0499694B1
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EP
European Patent Office
Prior art keywords
valve
control
pressure
load
line
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
EP91119267A
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German (de)
French (fr)
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EP0499694A2 (en
EP0499694A3 (en
Inventor
Rudolf Brunner
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Heilmeier and Weinlein Fabrik fuer Oel Hydraulik GmbH and Co KG
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Heilmeier and Weinlein Fabrik fuer Oel Hydraulik GmbH and Co KG
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Publication date
Priority to DE19914105459 priority Critical patent/DE4105459C2/de
Priority to DE4105459 priority
Application filed by Heilmeier and Weinlein Fabrik fuer Oel Hydraulik GmbH and Co KG filed Critical Heilmeier and Weinlein Fabrik fuer Oel Hydraulik GmbH and Co KG
Priority claimed from JP4033286A external-priority patent/JPH086723B2/en
Publication of EP0499694A2 publication Critical patent/EP0499694A2/en
Publication of EP0499694A3 publication Critical patent/EP0499694A3/en
Publication of EP0499694B1 publication Critical patent/EP0499694B1/en
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/003Systems with load-holding valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B21/00Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
    • F15B21/04Special measures taken in connection with the properties of the fluid
    • F15B21/045Compensating for variations in viscosity or temperature
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/305Directional control characterised by the type of valves
    • F15B2211/30505Non-return valves, i.e. check valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/305Directional control characterised by the type of valves
    • F15B2211/30505Non-return valves, i.e. check valves
    • F15B2211/3051Cross-check valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/305Directional control characterised by the type of valves
    • F15B2211/30505Non-return valves, i.e. check valves
    • F15B2211/30515Load holding valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/305Directional control characterised by the type of valves
    • F15B2211/30525Directional control valves, e.g. 4/3-directional control valve
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/31Directional control characterised by the positions of the valve element
    • F15B2211/3105Neutral or centre positions
    • F15B2211/3111Neutral or centre positions the pump port being closed in the centre position, e.g. so-called closed centre
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/31Directional control characterised by the positions of the valve element
    • F15B2211/3122Special positions other than the pump port being connected to working ports or the working ports being connected to the return line
    • F15B2211/3127Floating position connecting the working ports and the return line
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/31Directional control characterised by the positions of the valve element
    • F15B2211/3144Directional control characterised by the positions of the valve element the positions being continuously variable, e.g. as realised by proportional valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/40Flow control
    • F15B2211/405Flow control characterised by the type of flow control means or valve
    • F15B2211/40515Flow control characterised by the type of flow control means or valve with variable throttles or orifices
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/40Flow control
    • F15B2211/405Flow control characterised by the type of flow control means or valve
    • F15B2211/40576Assemblies of multiple valves
    • F15B2211/40584Assemblies of multiple valves the flow control means arranged in parallel with a check valve
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/40Flow control
    • F15B2211/41Flow control characterised by the positions of the valve element
    • F15B2211/413Flow control characterised by the positions of the valve element the positions being continuously variable, e.g. as realised by proportional valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/40Flow control
    • F15B2211/415Flow control characterised by the connections of the flow control means in the circuit
    • F15B2211/41581Flow control characterised by the connections of the flow control means in the circuit being connected to an output member and a return line
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/40Flow control
    • F15B2211/42Flow control characterised by the type of actuation
    • F15B2211/428Flow control characterised by the type of actuation actuated by fluid pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/40Flow control
    • F15B2211/45Control of bleed-off flow, e.g. control of bypass flow to the return line
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/40Flow control
    • F15B2211/46Control of flow in the return line, i.e. meter-out control
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/60Circuit components or control therefor
    • F15B2211/625Accumulators
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/80Other types of control related to particular problems or conditions
    • F15B2211/86Control during or prevention of abnormal conditions
    • F15B2211/8613Control during or prevention of abnormal conditions the abnormal condition being oscillations
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/80Other types of control related to particular problems or conditions
    • F15B2211/86Control during or prevention of abnormal conditions
    • F15B2211/8616Control during or prevention of abnormal conditions the abnormal condition being noise or vibration

Description

  • The invention relates to a hydraulic control device of the type specified in the preamble of claim 1.
  • Such a hydraulic cutter device is known from the publication 7100, June 1986, pp. 1 and 2, from Heilmeier & Weinlein, 8000 Munich 80.
  • In this device, the damping throttle has the task of damping either the control movements or the control movements of the load holding valve in order to dampen pressure fluctuations in the system and thus vibrations of the load. The task of the load holding valve is to prevent the undesired or impermissible wake movement under the load after the hydraulic consumer has stopped. Such control devices equipped with a damping throttle are preferably used when oscillating movements of the hydraulic consumer are to be expected, for example with lifting and extending cylinders of cranes, in particular mobile cranes, with rotary pistons and toothed rack / pinion swivel cylinders, with lifting and swiveling devices of all kinds with a change of sign the direction of load, in winch and slewing gear drives and the like.
  • For hydraulic consumers with a low tendency to vibrate, a bypass check valve is provided in parallel to the damping throttle in order to enable the load holding valve to be opened quickly bypassing the damping throttle.
  • The damping throttle is set so that it produces an optimal damping of pressure fluctuations when the pressurized medium is warm when the hydraulic consumer is moved under load with the load holding valve open. A work cycle movement occurs in the load holding valve, with the movements of relatively small pressure medium volumes in the Control pressure line are connected, which pass through the damping throttle and cause the damping effect in the system. Due to a possibly tight setting of the damping throttle for optimal damping and / or when the pressure medium is cold, the damping throttle can delay a desired rapid control movement of the load holding valve for stopping or positioning a load, so that the hydraulic consumer executes a harmful or dangerous follow-up movement after stopping under the load .
  • In a control device of this type known from DE 37 33 740 A1, a load-lowering valve is actuated with laminar flow via two throttle gaps arranged in parallel in the control pressure line of the load-lowering valve. The two throttle gaps are matched to each other with regard to their straight characteristic curves so that their summary characteristic curve largely follows a desired characteristic curve in the working area. The two throttle gaps change their gap heights with the temperature. In this way, vibration damping that is independent of the temperature of the pressure medium is sought. This principle is also suitable for load holding valves. The gap heights of the two throttle gaps, which are designed for optimal damping even with cold pressure medium, cannot rule out a wake of the hydraulic consumer in a load holding valve.
  • Hydraulic control devices such as those described above are often integrated into hydraulic systems that have a safety shutdown function. This means that the hydraulic consumer or the components it moves are monitored for a load, a load torque or a movement limit that is not may be exceeded. A limit pressure or limit position sensor generates an electrical signal that opens a solenoid valve in the control circuit, which reduces a pilot pressure for a control device of the control valve of the consumer or for a main control device of the hydraulic system. Moving the hydraulic consumer beyond this critical limit should then be prevented by no longer being able to control the working pressure in this direction of movement or by limiting the amount of working pressure medium. However, the sensor often only responds exactly to this safety limit or at most in a relatively narrow, predetermined tolerance range. If, despite the sensor responding, the consumer exceeds the tolerance range, for example due to a trailing movement of the hydraulic consumer under load, the sensor no longer responds and the consumer can continue to be controlled without restriction even in the critical area. This is particularly dangerous for a crane, for example, for the articulated cylinder or the horizontal swivel cylinder and - as established in practice - can occur due to a usually provided damping device, especially when the pressure medium is cold or when the damping is strong.
  • The invention has for its object to provide a hydraulic control device of the type mentioned, in which, despite damping for normal operation, an unwanted wake movement of the hydraulic consumer is excluded under, or a hydraulic control device with a safety shutdown with regard to the reliability of the safety function also under to improve unfavorable conditions.
  • The object is achieved according to the invention with the features specified in the characterizing part of patent claim 1.
  • If the hydraulic consumer is to be reduced by releasing pressure medium from the work line having the load holding valve and thus the load, control pressure is fed into the control pressure line and the load holding valve is activated. The valve arranged in the line loop holds its blocking position; the pressure medium passes the damping throttle; it is steamed. If the hydraulic consumer has to be stopped, the control pressure line is relieved until the load holding valve closes and the load holds. The valve then responds to the pressure difference that arises and assumes its open position so that the load holding valve controls the load pressure valve quickly enough even with cold and therefore viscous pressure medium. The pressure medium bypasses the damping throttle. In the same way, if the damping throttle is set strictly because of the desired damping and the pressurized medium is warm, the valve responds when the hydraulic consumer has to be stopped and the load has to be held and the damping throttle would prevent this. The response sensitivity of the valve is set so that the hydraulic consumer does not run on under unfavorable operating conditions, and still dampens the damping throttle whenever damping is needed, for example while lowering the load. With the valve, the control device is automatically able to override the damping throttle in each case when an operating state that is critical with regard to after-running of the hydraulic consumer occurs. This leads to the advantage of a damping throttle which is optimally adjustable for the damping and of the rapid Response and load holding of the load holding valve in operating states in which the damping throttle would interfere with the activation of the load holding valve. If a safety shutdown is provided in the hydraulic system containing the hydraulic control device, the hydraulic consumer cannot cross the safety limit or pass through a safety tolerance range even under unfavorable conditions.
  • In the embodiment according to claim 2, the second pressure difference on the valve is set so that this allows the damping throttle to come to full effect again when the load holding valve has almost reached the load holding position and only a small amount of working pressure medium passes the load holding valve. The residual closing stroke of the load holding valve is then again monitored by the damping throttle, which is able to dampen unaffected if pressure fluctuations should occur.
  • In the embodiment according to claim 3, when the load holding valve is opened, the pressure in the control pressure line initially holds the valve in the shut-off position because it overcomes the permanently acting force on the valve. Even with moderate pressure fluctuations, the valve element remains in the shut-off position, so that the damping throttle dampens play movements of the load holding valve and pressure fluctuations in the system. If, due to the damping throttle, the pressure in the control pressure line drops to such an extent that the permanently acting force controls the valve into the open position, a pressure reduction which enables the correct control movement of the load holding valve is ensured by pressure medium flowing out via the valve. In normal operation, because of the air flowing out through the damping throttle Pressurize the valve - if at all - into the open position only if there is a risk of the hydraulic consumer running on. In the case of excessive pressure fluctuations, on the other hand, the valve can also be briefly steered into the open position, whereby it supports the damping effect of the damping throttle by reducing pressure peaks. However, it is immediately steered back into the shut-off position by the permanent force.
  • The embodiment according to claim 4 is structurally simple. The pressure difference between the opening pressure and the spring force on the valve element is in any case guided via the damping throttle. By selecting this pressure difference, the sensitivity of the response of the valve is set, in order to let the damping throttle mainly work in the event of moderate pressure fluctuations in the system, but if the hydraulic consumer needs to be reliably stopped, even under load and with cold pressure medium, the damping throttle automatically and as far as necessary to ignore.
  • The feature of claim 5 is also important because a slide valve works leak-tight and with little structural effort and is relatively independent of temperature.
  • In the embodiment according to claim 6, the prestressed control check valve operates when the hydraulic consumer is moving, even under load, with a raised pressure window, ie as soon as the pressure difference across the damping throttle becomes greater than the permanent force at the check element, pressure medium flows past the damping throttle and until the pressure difference has dropped so far that the permanent Force closes the pilot check valve again and the remaining pressure medium must flow from the control side of the load holding valve via the damping throttle. It results in a desirable effect that the load holding valve quickly moves in a vigorous movement and largely stops the hydraulic consumer before the load holding valve moves into its end position in a subsequent and damped residual stroke movement with the passage in the working line already largely throttled. This not only suppresses or dampens pressure fluctuations, it also controls the load-holding valve so reliably and quickly, regardless of the operating conditions (even with cold pressure medium), especially in the event of a safety shutdown, that there is no overrun of the hydraulic consumer that crosses a safety limit or a safety tolerance range.
  • In practice, the embodiment according to claim 7 has proven itself. With this setting, the hydraulic consumer does not run on under load even when the pressure medium is cold and / or the damping throttle is tightly adjusted.
  • In the embodiment according to claim 8, the relatively vigorously biased control check valve allows the damping throttle to operate largely undisturbed, since it is only effective when there is a risk of unauthorized overrun of the hydraulic consumer, and also shuts off again if this danger occurs after a vigorous control movement of the Load holding valve is eliminated.
  • Another advantageous embodiment is based Claim 9 out. Particularly in the case of mobile cranes, heavy load vibrations occur in practice, which can lead to long-lasting pressure fluctuations in the system and make working with the crane more difficult. The damping effect of the motion damping throttle is then no longer satisfactory. Through the bypass duct with the interference throttle passage arranged therein and the cooperating throttle passage in the control pressure line, an additional hydraulic damping device is integrated into the control circuit of the load holding valve, with which pressure fluctuations can be damped very effectively and quickly, because the pressure medium quantity flowing out via the bypass line means the amplitudes of the pressure fluctuations disturbed that the pressure fluctuations subsided quickly. The inclusion of the different pressures then prevailing in the control circuit of the load holding valve in the pilot control of the valve loaded by the permanent force leads to the advantage of a load holding valve which is immediately activated even under critical operating conditions (cold pressure medium and / or tightly adjusted damping damper).
  • The permanently effective force can be relatively small in the embodiment according to claim 10, since it is supported by the pressure in the bypass line. This improves the response behavior of the valve. Since the valve participates in the damping of the pressure fluctuations, there is also the advantage that the size difference between the throttle passage and the interference throttle passage can be chosen to be very small, and thus the amount of pressure medium flowing out via the bypass line remains desirably small.
  • The feature of claim 11 is also important because the volume flow necessary for the damping and the pressure pilot control of the valve must actually be able to flow out via the bypass channel in order to contribute to the damping. If a control valve is integrated in the hydraulic control device, which in the zero position establishes a connection between the two working lines or the working line containing the load holding valve to the tank, the bypass line is expediently connected to this line. Alternatively, the bypass line can also be routed directly to the tank. Then a directional control valve with blocked zero position can also be used. Moreover, because of the effective damping, a directional control valve with inlet regulators can be used, which is critical in itself for control devices that are at risk of vibration, because it has a longer settling behavior per se.
  • Furthermore, the embodiment according to claim 12 is expedient because the immediate control check valve enables the load holding valve to be promptly activated in some applications, bypassing the damping throttle. In the event of pressure fluctuations during the movement of the hydraulic consumer, this check valve is in any case kept closed by the pressure in the control pressure line, so that the control pressure medium has to flow via the damping throttle.
  • A structurally simple embodiment emerges from claim 13. The check valve is integrated into the valve and ensures that the load holding valve is opened without delay.
  • The embodiment according to claim 14 is characterized by a particularly effective damping Pressure fluctuations in the system. The operation of the control check valve is influenced favorably by the pressure accumulator.
  • The embodiment according to claim 15 is also expedient. The check valve at this point prevents control pressure medium from flowing out to the other working line, or that pressure fluctuations in the control pressure circuit propagate into the other working line. In addition, the check valve forces the pressure medium, also from the pressure accumulator, to take the outflow path via the bypass channel for the purpose of effective damping.
  • The embodiment according to claim 16 is independent and of particular importance, since the simple safety shutdown device cannot be outwitted even in unfavorable operating conditions, such as cold pressure medium or strong damping with a tight damping throttle, but rather controls the load holding valve as intended without noticeable run-on. At a safety cut-off point, the control check valve is biased less strongly, whereas it can be biased higher at a safety cut-off tolerance range. The reliability of the safety shutdown is also given under conditions which are particularly unfavorable for a safety shutdown, but which are absolutely correct for normal operation.
  • In the embodiment according to claim 17, there is a simple construction of the safety shutdown device. Because like the relief valve, each sensor only needs an electrical supply that can be easily accommodated. The Relief valve is small and can be easily integrated in the directional control valve or in the control device.
  • In all of the above-described embodiments, the valve and the additional components can already be installed in the block of the load holding valve. However, it is also possible, as it were, to place a structural unit as a retrofit unit on the load holding valve or at another point in the control circuit of the load holding valve and to retrofit or retrofit a control device that has already been in operation or has been designed in advance.
  • Embodiments of the subject matter of the invention are explained with the aid of the drawing. It shows:
  • Fig. 1
    1 shows a circuit diagram of a control device, in the load holding position,
    Fig. 2
    a modified embodiment of a control device, in the load holding position,
    Fig. 2a
    2 shows a detailed variant of FIG. 2,
    Fig. 3
    another embodiment of a control device,
    Fig. 3a
    3 shows a detailed variant of FIG. 3,
    Fig. 4
    another embodiment, and
    Fig. 5
    a hydraulic control system with a safety shutdown device.
  • A hydraulic consumer V, for example a double-acting hydraulic cylinder, for moving a load arm carrying a load F, for example as an articulated cylinder of a mobile crane, can be seen in a hydraulic control device S according to FIG. 1. The cylinder with two chambers 2, 3 separated by a piston is supplied with pressure medium from a pressure source P from a tank T. A control valve C is provided to control the hydraulic consumer. In the embodiment shown, it is a 4/3-way control spool with relieved zero position. The chambers 2, 3 of the hydraulic consumer V are connected to the control valve C via working lines 4, 5. When the working line 4 is pressurized, the load F is raised and pressure medium is pushed out through the other working line 5. When the other working line 5 is pressurized, the hydraulic consumer V is moved (lowering) under the load F, pressure medium being pushed out through a working line 4. A load holding valve H is arranged in the one working line 4 and serves to hold the load F, for example in the zero position of the control valve C. The load-holding valve H contains, as usual, a valve 6 that is fluidly adjustable between a passage position to the control valve C and a shut-off position with a valve member 7 that has a control piston (not shown). The valve member 7 is loaded by a spring 7 'in the control direction (as shown). In the control direction, pilot pressure derived via a control line 9 also acts on the side of the control valve C. In contrast, the pilot pressure acts in the opening direction in one of the working line 4 between the valve 6 and the hydraulic consumer V. branching control line 8. Furthermore, a control pressure line 12 is provided, the pressure of which acts on the valve member 7 in the opening direction and which branches off from the working line 5 in the present exemplary embodiment. However, it is also conceivable to feed the pressure in the control pressure line 12 from its own pressure source or pressure control device.
  • The load holding valve H is bypassed (for lifting) by a bypass channel 10 with a check valve 11 opening in the direction of the hydraulic consumer V.
  • An adjustable damping throttle 13 is contained in the control pressure line 12, which dampens pressure fluctuations during the lowering movement of the load F and, in this embodiment, the opening and closing movements of the valve 6. In the control pressure line 12, a line loop 14 bypasses the damping throttle 13. In the line loop 14, a valve 15 with a valve element 16 is arranged, in FIGS. 1-3 a a 2/2-way slide valve, which is between a through position a and a shut-off position b is reversible. In the direction of the through position a, the valve element 16 is acted upon by a permanent force f of a suitably adjustable spring 18. In the direction of its shut-off position b, however, the valve element 16 is acted upon by the pressure in a pilot line 17 which branches off from the line loop 14 between the valve 15 and the other working line 5.
  • The force f is somewhat less than the force acting on the valve element 16 as a result of the (pilot) pressure in the pilot line 17.
  • To lower the load F, the working line 5 is pressurized by means of the control valve C. Since the check valve 11 blocks, the valve 6 must be opened, which is done via the control pressure line 12 and the damping throttle 13. The pressure in the control pressure line 12 holds the valve 15 in the shut-off position b via the pilot line 17, so that the pressure medium for opening is via the damping throttle 13. If pressure fluctuations occur later in the system during the lowering movement, then the valve 15 remains in its shut-off position, at least in the case of moderate pressure fluctuations; in the area of the working cycle of the valve 6 (e.g. a few 1/10 mm) the pressure medium is damped by the damping throttle 13.
  • If the load F is to be stopped, the pressure in the other working line 5 and thus in the control pressure line 12 is reduced. If the pressure at the valve member 7 cannot decrease quickly enough to control it via the damping throttle 13, then the spring 18 pushes the valve element 16 into the through position b, in which the damping throttle 13 is bypassed via the line loop 14 and the valve 6 is rapidly actuated. The hydraulic consumer V does not overrun. The valve 15 comes into effect in the manner described above if the damping throttle 13 would delay the control movement due to the viscosity with cold pressure medium or if the damping throttle 13 is set very tightly for reasons of sufficient damping. Furthermore, the valve 15 can briefly switch to passage in the event of excessive pressure fluctuations in the pressure control line 12 in order to participate in the damping and to allow pressure peaks to pass. Even before the pressure in the control pressure line 12 is completely reduced, the spring 18 brings the valve 15 into the Shut-off position. The residual pressure is reduced via the damping throttle 13. The valve 15 fulfills this auxiliary control function as with an increased pressure window.
  • The control device S according to FIG. 2 differs from the embodiment according to FIG. 1 by a further line loop 19 of the control pressure line 12, in which a control check valve 20 opening in the direction of the valve 6 is arranged in order to delay the opening of the valve 6 avoid. In the event of pressure fluctuations during the lowering movement, the check valve 20 is held in the blocking position, so that moving control pressure medium quantities pass through the damping throttle 13. The further function of the control device S according to FIG. 2 corresponds to that of FIG. 1.
  • In the embodiment according to FIG. 2a, the check valve 20 is structurally integrated in the valve 15 'or in its valve element 16'. The function is the same as in the embodiment according to FIG. 2.
  • The control device S according to FIG. 3 differs from the embodiment according to FIG. 2 by an additional damping device X for pressure fluctuations in the system. The damping device X is formed from a throttle passage D1 in the control pressure line 12 and a bypass line 22 branching off from the control pressure line 12 at 21 and containing an interference throttle passage D2. The interference throttle passage D2 is larger than the throttle passage D1. The bypass line 22 is either connected to the working line 4 (at 23), or — as indicated by the broken line at 24 — directly to the tank T connected so that when the working line 5 and thus also the control pressure line 12 are pressurized, pressure medium continuously flows out via the bypass line 22. The series-connected passages D1 and D2 effect an additional effective damping of pressure fluctuations when control pressure medium flows out.
  • In the opening direction, the damping throttle 13 is bypassed by the check valve 20. In the line loop 14, the valve 15˝ with its valve element 16˝ is arranged, which ensures the rapid actuation of the valve 6 even under difficult operating conditions (cold pressure medium and / or tight setting of the damping throttle 13). The valve element 16 is loaded by the spring 18 with the permanent force and the pressure in a pilot control line 26 in the direction of the through position a. The pilot line 26 branches off from the bypass line 22 downstream of the interference throttle passage D2. In the direction of the blocking position b, the valve element 16˝ is loaded via the pilot line 17 from the control pressure line 12, specifically with the pressure prevailing between the branch 21 of the bypass line 22 and the damping throttle 13. The force f set with the spring 18 can be relatively low in this embodiment because the spring 18 is supported by the pressure in the pilot line 26. At a pilot pressure of 20 bar required on the valve 6, an adjustment of the spring 18 to a pressure value of 15 bar is sufficient to ensure the rapid actuation of the valve 6 without after-running in the case of cold pressure medium and / or too tightly adjusted damping throttle 13. Since the valve 15˝ supports the damping of pressure fluctuations, the throttle passage D2 only needs to be slightly larger than that To be throttle passage D1, which desirably keeps the amount of pressure medium flowing through the bypass line 22 low.
  • The function of the control device S according to FIG. 3 essentially corresponds to that of FIG. 2.
  • In the embodiment variant according to FIG. 3a, the check valve 20 shown in FIG. 3 is structurally integrated into the valve element 16 ‴ of the valve 15 ‴. The pressure pilot control of the valve 15 ‴ takes place in the same way as in FIG. 3.
  • The valve 15, 15 ', 15˝, 15 ‴ need not necessarily be a Schieherventil, although this has the advantage of working practically leak-free. The desired function can also be achieved with a seat valve or a controllable check valve with pre-tension.
  • Furthermore, it is conceivable to design the valve 15, 15 ', 15˝, 15 ‴ magnetically actuated and remotely controlled via a thermostat or a pressure switch and then to actuate it when, for example, the pressure medium is cold or the pressure prevailing on the control side of the valve 6 because of delayed degradation increases too high or is not degraded quickly enough.
  • In the embodiment of FIG. 4, the hydraulic control device, as the valve 15 IV which bypasses the damping throttle 13 in the outflow direction from the valve 6, has a control check valve, the check element 16 IV of which is preloaded on a seat 28 by the spring 18, which can be preloaded. The control check valve opens against the Permanent force f of the spring 18 in the outflow direction from the valve 6. The spring 18 is set to a preload value which is slightly less than the value of the force acting on the check element 16 IV due to the opening pressure. At an opening pressure of approx. 40 bar, the force of the spring 18 corresponds to at least 15 bar, expediently it is approx. 25 bar. The function of the control device S is the same as the function of the embodiment in FIG. 3. However, it is also possible to omit the check valve 20 in the second line loop 19. Then the function of the control device S according to FIG. 4 would correspond to the function of the embodiment of FIG. 1, apart from the damping device X additionally provided in FIG. 4.
  • In contrast to the embodiment according to FIG. 3, the bypass duct 22 of the damping device X is connected to a return line 24 leading directly to the tank T, the one working line 4 also being connected to this return line 24 via a pressure relief valve 27. A filter 29 is also arranged in the control pressure line 12. On the side of the control pressure line 12 facing the other working line 5, which is not shown, a check valve 32 blocking the other working line 5 is also arranged. In addition, a pressure accumulator 31 is also connected to the connection point 21 via a line 30. The damping device X, including the pressure accumulator 31, could also be omitted. Furthermore, it is conceivable to provide the damping device X without a pressure accumulator 31.
  • If the control pressure line 12 is not pressurized to actuate the load holding valve H, then blocks the check valve 32; the pressure in the control pressure line 12 decreases via the bypass line 22 into the return line 24. If the pressure difference across the damping throttle 13, for example due to cold pressure medium or because of a tight setting of the damping throttle 13, increases to such an extent that the control movement of the valve 6 would be delayed, then the force f of the spring 18 is overcome and the control check valve is opened. The valve element 7 of the valve 6 of the load holding valve H performs a powerful stroke in the control direction until the valve element 7 is almost in the controlled end position. The load and the hydraulic consumer come to a halt. Through valve 6 - if at all - only a negligible amount of working pressure medium flows. The spring 18 brings the check element 16 IV back into contact with the seat 28 when the pressure difference across the damping throttle 13 has decreased accordingly. The control pressure medium is forced via the damping throttle 13 via the remaining stroke of the valve element 7. The control movement of the valve 6 takes place in two mutually harmonious phases, the first, longer phase being effected by the control check valve and the second, shorter phase by the damping throttle 13. There is no noticeable wake of the hydro consumer. By means of the control check valve, the response behavior of the load holding valve during control can be adjusted so that the damping throttle required for damping and also adjusted with regard to optimal damping is overridden under unfavorable operating conditions which may lead to a lag. This is particularly advantageous if, for example, the hydraulic consumer runs on in a safety circuit or the components actuated by this should be prevented or only tolerated to a precisely measurable extent.
  • Fig. 5 illustrates the integration of the hydraulic control device S into a hydraulic system K, e.g. of a crane which has a safety shutdown device A. The safety shutdown device A prevents the hydraulic consumer V from being moved further at a load, load torque or a movement limit in the direction in which it has reached this limit. The hydraulic consumer V in FIG. 5 is, for example, the articulated cylinder of a crane. A reference point 33, which is indicated at the consumer V, must not cross a boundary indicated by a hatched area 34. Instead of the movement limit, a pressure limit or a torque limit could also be monitored. A sensor 43 scans the reference point 33 and generates a signal as soon as the point 33 reaches the area 34. The signal would no longer be emitted if the point 33 left the area 34 in one direction or the other.
  • The working lines 4 and 5 are connected to the control valve C which is designed as a directional control valve and which is supplied with pressure medium by the pump P and at the same time is connected to a tank T. A regulating device, for example in the form of an inlet regulator Z, is arranged on the inlet side of the control valve C and supplies the pressure valve quantity to the control valve C as a function of the load pressure in order to control the consumer V properly. For this purpose, the control device Z is acted upon in the closing direction via a pilot control line 41 with the pressure upstream of the control valve C, in Closing direction, however, via a control line 37 with the load pressure in the working line 5 and a control spring 42. This is the usual pressure compensator principle.
  • Instead of an inlet regulator, the regulating device Z could also be formed by a main regulator, which regulates the inlet pressure or the delivery quantity in a common supply line in the case of several consumers supplied by the same pump P, depending on the greatest need or the priority of a selected consumer.
  • A relief valve 36 is arranged in the control line 37, which is expediently equipped as a solenoid valve with an actuating magnet 38 and a shut-off position spring 39 for a valve element 40. The actuating magnet 38 receives the signal in line 35 from sensor 43 and relieves the control line 37 as soon as point 33 has entered area 34. The control device Z interrupts the further supply to the control valve C. The pressure in the working line 5 is no longer increased. The load holding valve H on the left in FIG. 4 must therefore actuate so quickly when the safety shutdown device A responds that the hydraulic consumer V does not perform a wake at which point 33 extends beyond area 34. The valve 15 IV of the left load holding valve H is adjusted with its spring 18 in such a way that it ensures the rapid actuation of the load holding valve H, which is matched to the region 34.
  • The load holding valve H1 shown on the right in FIG. 5 serves to hold the load in the other direction of movement of the hydraulic consumer V. Although this is not shown in FIG. 5 this direction of movement of the consumer V could also be monitored by a safety shutdown device A. Then the one working line 4 would have to be brought into control pressure connection with the control device Z.

Claims (17)

  1. Hydraulic control device (S), having a dual-acting hydraulic consumer (V) which can be pressurized via two operating lines (4, 5) and is safeguarded in at least one operating direction by a load-holding valve (H, H1) which can be controlled hydraulically to open and close, having a control pressure line (12) which is connected to a control connection of the load-holding valve (H) and can be pressurized selectively, having a damping throttle (13) in the control pressure line (12), and a valve (15, 15′, 15˝, 15‴, 15IV) provided in the control pressure line (12) parallel to the damping throttle (13), characterized in that, when the load-holding valve (H) is controlled to close, at a predetermined first pressure difference at the damping throttle (13) which is due to viscosity and/or adjustment, the valve (15, 15′, 15˝, 15‴, 15IV) can be switched over automatically and pressure-dependently from a shut-off position (b) into a passage position (a).
  2. Hydraulic control device according to Claim 1, characterized in that, at a predetermined second pressure difference which is lower compared to the first pressure difference, the valve (15, 15′, 15˝, 15‴, 15IV) can be switched over automatically and pressure-dependently from the passage position (a) into the shut-off position (b).
  3. Hydraulic control device according to Claims 1 and 2, characterized in that a line loop (14) is provided in the control pressure line (12), which line loop bypasses the damping throttle (13) and in which there is arranged the valve (15, 15′, 15˝, 15‴) having a valve element (16, 16′, 16˝, 16‴) which can be moved between the passage position (a) and the shut-off position (b), and in that the valve element (16, 16′, 16˝, 16‴) is pressurized in the direction towards its shut-off position (b) with the control-open pressure prevailing in the control pressure line (12) on the side of the damping throttle (13) facing away from the load-holding valve (H) and is pressurized in the direction towards its passage position (a) by a permanent force (f) which is adjusted to a value lying below the value of the force of the control-open pressure of the load-holding valve (H) acting on the valve element.
  4. Hydraulic control device according to Claim 3, characterized in that the valve element (16, 16′, 16˝, 16‴) is loaded by a spring (18), and in that the spring (18) is adjusted, at a control-open pressure of, for example, 20 bar, to a force value corresponding to about 15 bar on the valve element.
  5. Hydraulic control device according to Claims 1 to 4, characterized in that the valve (15, 15′, 15˝, 15‴) is a slide valve having a piston slide which forms the valve element (16, 16′, 16˝, 16‴).
  6. Hydraulic control device according to Claims 1 and 2, characterized in that a line loop (14) is provided in the control pressure line (12), which line loop bypasses the damping throttle (13) and in which there is arranged the valve (15IV) which is designed as a control-close non-return valve and has a non-return element (16IV) which can be moved between the passage position with the flow direction away from the load-holding valve (H) and the shut-off position, and in that the non-return element (16IV) is elastically prestressed in the direction towards its shut-off position by a permanent force (f), for example an adjustable spring (18), which is adjusted to a value lying below the value of the force of the control-open pressure of the load-holding valve (H) acting on the non-return element (16IV).
  7. Hydraulic control device according to Claim 3 or 6, characterized in that the force (f) is limited to a value which is between 10% and 50% smaller than the value of the force of the control-open pressure required in the control pressure line (12) between the damping throttle (13) and the load-holding valve (H) to control the load-holding valve to open.
  8. Hydraulic control device according to Claim 6, characterized in that the spring (18) is adjusted, at a control-open pressure of 35 to 40 bar, to a force value corresponding to about 25 bar on the non-return element (16IV).
  9. Hydraulic control device according to Claims 1 to 8, characterized in that a throttle passage (D1) is arranged in the control pressure line (12) on the side of the damping throttle (13) facing away from the load-holding valve (H), and in that a bypass line (22), having a disturbance throttle passage (D2) which is larger compared to the throttle passage (D1), branches off from the control pressure line (12) between the throttle passage (D1) and the damping throttle (13).
  10. Hydraulic control device according to Claims 1 to 5 and 9, characterized in that the valve element (16˝, 16‴) of the valve (15˝, 15‴) is pressurized in the direction towards its shut-off position (b) by the pressure prevailing in the control pressure line (12) between the damping throttle (13) and the throttle passage (D1) and in the direction towards its passage position (a) by the permanent force (f) and by the pressure prevailing in the bypass line (22) downstream of the throttle passage (D2).
  11. Hydraulic control device according to Claim 9, characterized in that the bypass line (22) is connected to the one operating line (4) containing the load-holding valve (H) or directly to the tank (T).
  12. Hydraulic control device according to Claims 1 to 11, characterized in that there is provided a control-open non-return valve (20) which bypasses the damping throttle (13) in the flow direction to the load-holding valve (H).
  13. Hydraulic control device according to Claims 1 to 5 and 12, characterized in that the control-open non-return valve (20) is constructionally incorporated in the valve (15′, 15‴), preferably in its valve element (16′, 16‴).
  14. Hydraulic control device according to Claims 1, 6, 7, 8, 9, 11 and 12, characterized in that a pressure accumulator (31) is connected to the control pressure line (12) between the throttle passage (D1) and the damping throttle (13).
  15. Hydraulic control device according to Claim 14, characterized in that a non-return valve (32) which shuts off in the flow direction to the other operating line (4) is provided in the control-open pressure line (12) between the throttle passage (D1) and the other operating line (4).
  16. Hydraulic control device according to at least one of Claims 1 to 15, characterized in that the operating lines (4, 5) are connected to a control valve (C), preferably a directional control valve, which can be pressurized with operating pressure medium on the inlet side via a control unit (Z), preferably according to requirement, in that a safety cut-off device (A) with at least one lifting, load-moment or load-pressure sensor (43) and at least one pressure relief valve (36) is provided for the control unit (Z), and in that the permanent force (f) on the valve element (16, 16′, 16˝, 16‴) or on the non-return element (16IV) acting on the control-open pressure of the load-holding valve (H), the adjustment of the damping throttle (13) and the response behaviour of the safety cut-off device (A) are matched in such a way that the load-holding valve (H) can be controlled into its load-holding position when the safety cut-off device (A) responds.
  17. Hydraulic control device according to Claim 16, characterized in that the sensor (43) is designed as an electrical or electronic transducer and the pressure relief valve (36) is designed as a solenoid which can be actuated by the sensor (43).
EP91119267A 1991-02-21 1991-11-12 Hydraulic control device Expired - Lifetime EP0499694B1 (en)

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DE19914105459 DE4105459C2 (en) 1991-02-21 1991-02-21
DE4105459 1991-02-21

Applications Claiming Priority (1)

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JP4033286A JPH086723B2 (en) 1991-02-21 1992-02-20 Hydraulic control device

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EP0499694A2 EP0499694A2 (en) 1992-08-26
EP0499694A3 EP0499694A3 (en) 1993-02-03
EP0499694B1 true EP0499694B1 (en) 1995-10-11

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DE (1) DE4105459C2 (en)
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GR3017882T3 (en) 1996-01-31
DE4105459A1 (en) 1992-08-27
AT129049T (en) 1995-10-15
EP0499694A3 (en) 1993-02-03
ES2080221T3 (en) 1996-02-01
DE4105459C2 (en) 1993-03-18
EP0499694A2 (en) 1992-08-26
US5259293A (en) 1993-11-09
DK0499694T3 (en) 1996-01-22

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