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EP0756574B1 - Vorrichtung zum dämpfen von ungewünschten schwingungen in einem kranelement - Google Patents

Vorrichtung zum dämpfen von ungewünschten schwingungen in einem kranelement Download PDF

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Publication number
EP0756574B1
EP0756574B1 EP95917527A EP95917527A EP0756574B1 EP 0756574 B1 EP0756574 B1 EP 0756574B1 EP 95917527 A EP95917527 A EP 95917527A EP 95917527 A EP95917527 A EP 95917527A EP 0756574 B1 EP0756574 B1 EP 0756574B1
Authority
EP
European Patent Office
Prior art keywords
restriction
hydraulic
circuit
closing device
valve
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
EP95917527A
Other languages
English (en)
French (fr)
Other versions
EP0756574A1 (de
Inventor
Peter ASTRÖM
Gösta SVENSSON
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.)
Hiab AB
Original Assignee
Hiab AB
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Hiab AB filed Critical Hiab AB
Publication of EP0756574A1 publication Critical patent/EP0756574A1/de
Application granted granted Critical
Publication of EP0756574B1 publication Critical patent/EP0756574B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C23/00—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes
    • B66C23/62—Constructional features or details
    • B66C23/84—Slewing gear
    • B66C23/86—Slewing gear hydraulically actuated
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C13/00—Other constructional features or details
    • B66C13/04—Auxiliary devices for controlling movements of suspended loads, or preventing cable slack
    • B66C13/06—Auxiliary devices for controlling movements of suspended loads, or preventing cable slack for minimising or preventing longitudinal or transverse swinging of loads
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C13/00—Other constructional features or details
    • B66C13/04—Auxiliary devices for controlling movements of suspended loads, or preventing cable slack
    • B66C13/06—Auxiliary devices for controlling movements of suspended loads, or preventing cable slack for minimising or preventing longitudinal or transverse swinging of loads
    • B66C13/063—Auxiliary devices for controlling movements of suspended loads, or preventing cable slack for minimising or preventing longitudinal or transverse swinging of loads electrical
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6306—Electronic controllers using input signals representing a pressure
    • F15B2211/6313—Electronic controllers using input signals representing a pressure the pressure being a load pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/80—Other types of control related to particular problems or conditions
    • F15B2211/86—Control during or prevention of abnormal conditions
    • F15B2211/8616—Control during or prevention of abnormal conditions the abnormal condition being noise or vibration

Definitions

  • This invention relates to a device for damping undesirable oscillations in an arm or other member of a crane that is pivotally movable by hydraulic means. It is concerned with a system having at least one hydraulic motor in a hydraulic circuit in which there is a restriction. When a circuit-closing device or function is operated to stop the main motion, this restriction converts energy inherent in the system (deformation energy and kinetic energy) to heat in the hydraulic fluid that still flows as a result of oscillation. The heat dissipates that energy to damp or suppress any oscillations of said member.
  • cranes there can be a plurality of movements which are carried out by means of hydraulic motors, usually linearly operating motors in the form of cylinder actuators.
  • One such movement is the horizontal slewing of the crane arm between various azimuth positions.
  • This is often accomplished by means of two integrated hydraulic cylinders, which by way of a common toothed rack actuate a gear wheel coaxially carried by the post supporting the crane arm.
  • Such a crane movement is schematically illustrated in the appended drawing where a crane arm seen from above is designated 1.
  • This crane arm 1 is mounted on a post 2 having a coaxial gear wheel 3, which engages a toothed rack 4 connected at opposite ends to motors in the form of two linear hydraulic actuators.
  • Both the arm and the load it carries are subject to oscillatory or reciprocating motions, and the duration of these may be long. They are caused by the fact that deformation energy is easily absorbed in the crane arm, and potential energy in a freely hanging load, when the crane arm is slewed. Assume that the crane arm 1 at a certain moment during a cycle of oscillation tends to slew anti-clockwise about the centre of the gear wheel 3.
  • the toothed rack 4 is moved to the right in figure 1, the oil pressure in the chamber 7' increasing at the same time as the oil pressure in the chamber 7 decreases.
  • the directional valve 9 is shut off and will not permit flow.
  • the arm 1 will act as a spring at the same time as the free-hanging load acts as a pendulum. That will accelerate in the opposite direction when it reaches the end of its swing and then the arm will be set in motion clockwise.
  • the oil pressure in chamber 7 is thus increased.
  • the crane arm will oscillate.
  • the tip of the crane arm swing or deflect between positions of the order of 2 metres apart and it can be 15 to 20 seconds before the tip and accordingly the load are stopped.
  • Such oscillations are especially troublesome where the load is at the end of a lengthy rope hanging down from the tip of the crane arm.
  • the crane arm tip oscillates to and fro at the same time as the load oscillates relative to the tip through the rope.
  • Such oscillations may also occur during the slewing of the crane arm tip between two desired positions. They may happen, for example, if the hydraulic flows to the respective cylinders 5, 5' are disrupted, as a consequence of sharp lever movements at the directional valve 9 perhaps or as a consequence of the load or the crane arm hitting obstacles.
  • a damping unit which is installed in a branch or intermediate conduit bridging the main conduits between the directional valve and the hydraulic cylinders.
  • the damping unit is in the form of a restriction associated with a co-operating shut-off device.
  • this shut-off device consists of a piston captive in a cylinder and freely movable between opposite end positions, the piston shutting off the oil flow through the restriction when it reaches either end position. When the oil passes the restriction a turbulent flow in the oil is generated which converts the energy inherent in the system to heat.
  • the duration of the oscillations of the crane arm is reduced to a significant extent. Assuming the crane arm is suddenly stopped from the full velocity of slewing, the duration of oscillatory motions (to when the arm is finally still) can be reduced from 15 to 20 seconds to 3 to 5 seconds.
  • the present invention aims to alleviate the problem still left by SE 9101544-6 and provide a damping device which, during the damping operation, promotes regular or even movements of the crane arm and at the same time makes sure that the arm will stop in a reliable manner and in a desired position after slewing.
  • a basic object of the invention is to provide a damping device which is capable of being activated whenever an oscillation tends to occur due to an expected or unexpected external influence on the hydraulic system, such as intentional or unintentional lever movements or collisions against obstacles.
  • Another object is to provide a damping device which, after the arm has stopped moving, will ensure that any flow of hydraulic fluid through the damping restriction will cease and so prevent uncontrolled movements of the crane arm.
  • DE 4 216 241 discloses a further developed embodiment of the damping device according to SE 9101544-6.
  • a circuit-closing device in the form of two shut-off valves is arranged in the intermediate circuit in order to keep the damping unit closed until a predetermined pressure occurs in said circuit.
  • the threshold value of the pressure is, however, given once and for all and cannot be adjusted to varying conditions.
  • FIG 1 is a schematic illustration of a hydraulic system of the type previously mentioned, in which a schematically shown damping device according to the invention is included. More particularly figure 1 shows a first, preferred embodiment having control means including a microcomputer or similar control unit.
  • a restriction symbolically indicated at 13 is arranged in a branch or intermediate conduit 12 between the main conduits 8a, 8b.
  • this restriction may consist of a fixed restriction in the form of an annular insert or shoulder of reduced diameter located in the conduit 12.
  • the conduit may be a tube or a drilled bore in a block.
  • This opening and closing of the valve is controlled by a control unit 15 which in practice advantageously, but not necessarily, may consist of a microcomputer.
  • input data to this control unit are obtained by means of two sensors 16, 16' in the form of pressure or flow sensors. These may be connected as shown to the intermediate conduit 12, or they may be connected to the conduits 8a, 8b, on either side of the restriction 13 and the magnetic valve 14.
  • the purpose of these sensors 16, 16' is to detect significant conditions and/or changes of conditions in the hydraulic oil in the circuit. It is preferred in practice to use sensors which are capable of detecting significant pressures and/or changes of pressure which occur in the two actuators 5, 5' when the crane arm 1 starts to oscillate.
  • control unit 15 When the control unit 15 receives information from the sensors 16, 16' that pressures and/or pressure changes of a certain magnitude have arisen in the system, the unit will provide a signal to the magnetic valve 14 to open, whereby the valve will allow oil to flow through the restriction 13. In other words the restriction is activated, and a turbulent flow is created in the oil passing to and fro through it. The varying deformation energy and the kinetic energy in the system is converted, in a manner known per se, to heat in the oil, and the oscillatory motions of the crane arm are damped.
  • the control unit 15 provides a signal to the magnetic valve 14 to close. Any further flow of oil through the restriction 8 is thus blocked. It should be noted that the directional valve 9 is kept closed all the time during this damping operation. Therefore, when the valve 14 is shut off even a minimum flow of oil between the two cylinders 5, 5' is rendered impossible. This ensures that the crane arm 1 is reliably maintained in its given, desired position.
  • the damping device of figure 1 makes possible a completely, reliably and positively controlled closure of the intermediate conduit 12 when the crane arm is arrested.
  • a basic advantage of the invention is that it provides a reliable and positive adjustment of the crane arm to the desired position while the duration of the resultant oscillations is substantially reduced in comparison with such cranes that lack damping devices.
  • Another advantage in comparison with SE 9101544-6 is that the restriction - and accordingly the damping - can be controlled in a positive and efficacious manner.
  • the control unit 15 when it is a microcomputer, may be programmed in such a manner that the magnetic valve 14, which is normally closed, will be opened not only when the crane arm has finished slewing (when the lever of the directional valve 9 is moved to the neutral position) but also at any moment during slewing.
  • a sequence of oscillations irrespective of whether it occurs after the basic crane arm movement has stopped or during slewing, manifests itself in a harmonic function the condition of which is read by the microcomputer by means of the sensors.
  • the computer On a given condition existing the computer may send a signal to the magnetic valve to either open or close.
  • the freely movable or floating piston in the damping cylinder according to SE 9101544-6 cannot be acted on at all from outside in any controllable manner.
  • the invention is not merely limited to the embodiment disclosed above and in the drawing.
  • the embodiment of figure 1 includes a fixed restriction and a magnetic valve separate from the restriction.
  • a check valve serving both as a variable restriction, and for completely shutting-off the hydraulic conduit.
  • a single fixed restriction in practice in the form of an insert or a shoulder having a small percolation aperture
  • pressure sensors it is also possible to use either flow sensors in the hydraulic circuit or position sensors which instantaneously detect the position of the crane member to be damped.
  • the damping device of the invention may also be used for other members forming parts of a crane, such as the inner boom and the outer boom, in order to damp oscillations in other planes, such as vertical.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Control And Safety Of Cranes (AREA)
  • Vibration Prevention Devices (AREA)

Claims (4)

  1. Vorrichtungen zum Dämpfen unerwünschter Schwingungen in einem Teil (1) eines Krans, welches mittels zumindest eines Hydraulikmotors (5, 5') in einer Hydraulikleitung (8) schwenkbeweglich ist, in der eine Schikane (13) vorgesehen ist, die mit einer Kurzschlussvorrichtung (14) zusammenwirkt, wobei die Schikane dazu dient, dem System innewohnende Energie in Wärme in dem Hydraulikmedium umzusetzen, um Schwingungen des durch die Energie erzeugten Elements zu dämpfen oder zu unterdrücken, gekennzeichnet durch Sensormittel (16, 16'), die auf Schwellen in das Teil betreffende Bedingungen auftreten, wenn dieses schwingt, und die dazu ausgelegt sind, die Leitungsverschlussvorrichtung (14) zu schließen, um Strömung durch die Schikane (13) zuzulassen und zu blockieren, wenn die Schwellen überschritten und nicht überschritten werden, und durch Mittel (15) zum elektronischen Verarbeiten von Information von den Sensormitteln (16, 16') in eine Form, die geeignet ist, die Leitungsverschlussvorrichtung (14) zu betätigen.
  2. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, dass die Schaltungsverschlußvorrichtung ein Abschaltventil (14) ist.
  3. Vorrichtung nach Anspruch 2, dadurch gekennzeichnet, dass das Abschaltventil ein Magnetventil vom Ein-/Ausschalt-Typ ist.
  4. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, dass die Schaltungsverschlußvorrichtung ein Ventil ist, das eine vollständige Verschluß- oder eine Zwischenverschlußstellung einnehmen kann, um ein variables Drosseln des Hydraulikmediums zu ermöglichen, welches in der Hydraulikleitung strömt.
EP95917527A 1994-04-22 1995-04-07 Vorrichtung zum dämpfen von ungewünschten schwingungen in einem kranelement Expired - Lifetime EP0756574B1 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE9401369A SE505698C2 (sv) 1994-04-22 1994-04-22 Anordning för dämpning av icke önskvärda oscillationsrörelser i en krandel
SE9401369 1994-04-22
PCT/SE1995/000375 WO1995029118A1 (en) 1994-04-22 1995-04-07 A device for damping undesirable oscillations in a crane member

Publications (2)

Publication Number Publication Date
EP0756574A1 EP0756574A1 (de) 1997-02-05
EP0756574B1 true EP0756574B1 (de) 2001-06-20

Family

ID=20393744

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95917527A Expired - Lifetime EP0756574B1 (de) 1994-04-22 1995-04-07 Vorrichtung zum dämpfen von ungewünschten schwingungen in einem kranelement

Country Status (6)

Country Link
EP (1) EP0756574B1 (de)
AT (1) ATE202324T1 (de)
AU (1) AU2354395A (de)
DE (1) DE69521423T2 (de)
SE (1) SE505698C2 (de)
WO (1) WO1995029118A1 (de)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0985629B1 (de) 1998-09-08 2001-07-25 Palfinger Aktiengesellschaft Kran
DK179730B1 (en) * 2017-10-06 2019-04-26 Hmf Group A/S Damping System, Damping Method and Crane Comprising It

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1284071B (de) * 1966-06-30 1968-11-28 Maschf Augsburg Nuernberg Ag Laufkatze mit Hubfuehrung des Lastaufnahmemittels durch ein Lenkergetriebe, einer Zwanglaufvorrichtung sowie einer den Zwanglauf begrenzt aufhebenden Ausgleichsvorrichtung
US4531647A (en) * 1976-01-14 1985-07-30 Hitachi, Ltd. Device for stopping the swinging movement of a load hung by a crane
JPH0815998B2 (ja) * 1989-10-14 1996-02-21 株式会社神戸製鋼所 ホイール式クレーンの振動抑制装置
SE508992C2 (sv) * 1991-05-22 1998-11-23 Einar Karlsson Anordning för att dämpa svängningar i en hydraulisk lastkran

Also Published As

Publication number Publication date
SE505698C2 (sv) 1997-09-29
AU2354395A (en) 1995-11-16
ATE202324T1 (de) 2001-07-15
EP0756574A1 (de) 1997-02-05
SE9401369L (sv) 1995-10-23
DE69521423T2 (de) 2002-05-02
WO1995029118A1 (en) 1995-11-02
SE9401369D0 (sv) 1994-04-22
DE69521423D1 (de) 2001-07-26

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