EP0798260B1 - Anordnung an Gabelhubwagen - Google Patents

Anordnung an Gabelhubwagen Download PDF

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Publication number
EP0798260B1
EP0798260B1 EP19970850047 EP97850047A EP0798260B1 EP 0798260 B1 EP0798260 B1 EP 0798260B1 EP 19970850047 EP19970850047 EP 19970850047 EP 97850047 A EP97850047 A EP 97850047A EP 0798260 B1 EP0798260 B1 EP 0798260B1
Authority
EP
European Patent Office
Prior art keywords
movement
hydraulic
motor
end positions
current
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
EP19970850047
Other languages
English (en)
French (fr)
Other versions
EP0798260A2 (de
EP0798260A3 (de
Inventor
Kurt-Ove Stenberg
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.)
BT Industries AB
Original Assignee
BT Industries 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 BT Industries AB filed Critical BT Industries AB
Publication of EP0798260A2 publication Critical patent/EP0798260A2/de
Publication of EP0798260A3 publication Critical patent/EP0798260A3/de
Application granted granted Critical
Publication of EP0798260B1 publication Critical patent/EP0798260B1/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
    • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F9/00—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
    • B66F9/06—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
    • B66F9/075—Constructional features or details
    • B66F9/20—Means for actuating or controlling masts, platforms, or forks
    • B66F9/22—Hydraulic devices or systems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F9/00—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
    • B66F9/06—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
    • B66F9/075—Constructional features or details
    • B66F9/12—Platforms; Forks; Other load supporting or gripping members
    • B66F9/122—Platforms; Forks; Other load supporting or gripping members longitudinally movable
    • 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
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/20—Other details, e.g. assembly with regulating devices
    • F15B15/28—Means for indicating the position, e.g. end of stroke
    • F15B15/2815—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT
    • F15B15/2838—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT with out using position sensors, e.g. by volume flow measurement or pump speed

Definitions

  • the invention has as its object to provide a method and a device for the control of hydraulically propelled movements, in particular the extending forward of the forks at reach trucks enabling this movement to be slowed down close to the end positions of the movement in order to prevent shocks.
  • this object is solved by measuring or calculating the flow of hydraulic oil to the hydraulic means, for instance a piston, executing the movement and using the flow as a measure of the movement. Since the cross section of the hydraulic cylinder is constant the length of the stroke is proportional to the volume of hydraulic oil fed to the cylinder and a sufficiently exact indication of the position can be obtained in this simple manner. Even if a nonlinear transmission used, as for instance a pantograph mechanism, a distinct movement or stroke will be repeatable, each position corresponding to a precise volume of oil having been fed to the cylinder.
  • the volume of the hydraulic oil that has been fed to the cylinder can for instance be measured with a sensor that registers the number of revolutions that the driving pump execute.
  • This solution also requires the use of a sensor, but this can be placed in shielded places with a reduced risk for damages and drive disturbances.
  • the voltage of the electric motor driving the hydraulic pump can be used as a parameter for the calculation, this in particular for DC-motors.
  • the voltage (at the poles of the engine) essentially corresponds to the RPM of the motor.
  • a measure is obtained corresponding to the oil volume delivered to/or removed from the cylinder, which in turn corresponds to the position of the piston. Oil temperature and the size of the load may influence the measured results, but by using the amperometric value of the current to the motor as additional measuring or control parameter the precision can be improved further when establishing (calculating) the position of the hydraulic piston.
  • the position measuring can then be used for instance for speed reduction (ramping) at the ends of the working stroke of the piston in its respective directions.
  • the invention does not only provide the possibility of slowing down and stopping a piston at suitable end positions with a constant speed between these, but it is also possible with a more or less harmonic movement with a fast intermediate movement zone and a successively reduced speed towards the end positions. In this way no shocks are obtained in the end positions and furthermore the fork movement can be executed faster and with a reduced risk of tilting or instability.
  • control device of the movement may also include a selflearning function. This may for instance be done in such a way that when the truck is started the piston movement is executed a first time with a very early cautious ramping stored in a memory. The control device then registers the mechanically fixed end positions for instance by monitoring the current to the hydraulic pump motor. As the piston reaches its respective end positions the amperometric value of the current will rise immediately and much. Also this indication can be obtained without special and cost demanding parts. In the control device, that may for instance include a small computer this notes in a suitable memory the oil volumes corresponding to the end positions of the movement back and forth. At repeated use the movement speed is reduced shortly before the reaching of these mechanical end positions.
  • a harmonic movement speed profile is adapted to the intended end positions that are located slightly within the mechanical end positions.
  • an accumulated memory is arranged for the movements, that is the number of engine revolutions or the integral of the voltage so that the position will always be registered even if the movements are interrupted and resumed many times or even executed in alternating directions without reaching the ultimate end positions.
  • control device is configured for continuous monitoring so that if, for instance due to changing drive conditions (for instance between hot or cold hydraulic oil) the pistons strikes an end position with too high speed the computer enters a corresponding correction of the control parameter for the next movement.
  • This strike or contact will however normally take place with a reduced speed since the movement in the proximity of the end positions is slowing down and the preprogrammed ramp distance is large.
  • the invention also improves the possible time of use between recharging.
  • the invention is in particular intended for the horizontal fork extending movement of a reach truck, but within the inventive thought even other pistons or even hydraulic motors may be controlled in this way to execute or simplify the execution of a particular movement in one or the other direction before a retarding or stopping is initiated by a control device and one can also consider monitoring the positions of several hydraulic means in the same machine and the controlling of their movements in this way and with common electronic devices based on a common oil pump that is driven by an electric motor.
  • stepped or divided hydraulic cylinders may be controlled, by monitoring the current and the voltage values of the motor that drives the hydraulic devices so that the computer via the amperometric value of the current can keep track of the actual piston area that at each specific movement takes part in the movement.
  • the electronic control of the piston movement may either take place by influencing the driving of the electric motor and/or by controlling electrically controlled valves.
  • electrical valves By the use of the electrical valves it is possible to register where to the oil is delivered without additional sensors, and a computer can keep track of the piston position for one or several hydraulic cylinders even if the piston movements only are partial.
  • the fork extension or reach may be supervised and controlled but also lifting, side-shift, mast tilting and even the driving of the truck may be controlled.
  • the obtained position information may then not only be used for speed ramping for different movements but also for position control, and a reduction of permitted driving speed when the forks are high up and the truck therefore is less stable.
  • the principal configuration of a piston control shown in the drawing includes a hydraulic pump 1 connected to a hydraulic cylinder 2 via a valve 3a in an electric valve unit 3 which is controlled by a computer 4 and a reservoir 11.
  • the hydraulic pump 1 is driven by an integrated electrical DC-motor that in turn via electronically controlled speed regulation 5 is connected to a battery 6 and the computer 4.
  • the drive voltage is monitored via a connection 7 and via a connection 8 also a an amperometric drive current sensor 9 is connected to the computer.
  • the computer registers this, starts the motor and opens the valve 3a.
  • the motor is preferably started successively and increasingly independently of how the driver has influenced the actuator 10, alternatively one can consider that the deflection of the actuator 10 controls how fast the total movement is to be executed and thereby in the initial part of the movement how steep the end position ramp should be.
  • the computer starts integrating the engine voltage over the time in order to monitor the position of the piston in accordance with the preceding description of the invention.
  • the computer controls the motor during a speed reduction ramping so that it runs slower and slower to the stop of the piston and a closing of the valve 3a.
  • This end position does not have to be the mechanical end position of the piston as such.
  • the computer may also note possible obstructions by the corresponding increase of the current for instance if the load when placed on a shelf is hindered by another load and the computer may be programmed to interrupt the movement in such a case.
  • the computer may even by monitoring the amperometric value of the current register if the fork is unloaded and thus can be moved faster.
  • control When using a synchronously or non-synchronously working AC-motors the control may be executed in analogy with the above example, but with the difference that the controlling electronics for the motor delivers the information regarding the rotation of the motor directly since the information for the rotation of the field in the motor is directly accessible in the control electronic of the motor.
  • the invention can also be used for the fork lifting, this in particular when using AC-motors or a separate tachometer or angle sensor for the oil pump.
  • the oil pump with its motor may at such a return flow be driven as a motor in order to increase the speed in the movement or as a generator driven by the oil flow from the lifting cylinders in order to deliver a charging current to the batteries of the truck.
  • This return oil may simultaneously be delivered to some other user, making it possible simultaneously to keep track of two movements, for instance a lowering of the forks and the retraction of the forks.
  • the driving speed may be restricted until the forks and the load have been lowered to a lower level with an increased total stability.
  • the invention gives a simple and practical way to monitor and control all the movements of the truck including steering movements so that a smooth, harmonic, fast and easily controlled manner of working with increased security can be obtained.
  • the computer may at intervals run a reset program, with extended travel until contact is registered, to secure that movement does not stop too far away from the end position.
  • the driver may have the possibility to overrule or initiate a resetting of the monitoring and control system.
  • the method in accordance with the invention is initially intended for the reach movement which is repeated essentially in its entire length most of the time, however the obtained data may also, for instance for the lift movement be used to control the reaching of intermediate positions as for instance different storage levels.

Landscapes

  • Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Civil Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Forklifts And Lifting Vehicles (AREA)
  • Fluid-Pressure Circuits (AREA)

Claims (7)

  1. Verfahren zur Positionsüberwachung und -steuerung von hydraulischen Einrichtungen, insbesondere eines Hydraulikzylinders (2) für eine Reichweitenbewegung von Gabeln eines Gabelstaplers, dadurch gekennzeichnet, daß die Position oder der Weg einer Bewegung dadurch ermittelt wird, daß die Menge des Hydrauliköls gemessen wird, die der betreffenden Hydraulikeinrichtung (2) zugeleitet oder von dieser abgeleitet wird, und daß die Positlonsmessung zu Reduzierung der Bewegungsgeschwindigkeit, einer stufenlosen Geschwindigkeitsveränderung, in der Nähe der Endpositionen der Bewegung genutzt wird.
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Drehzahl der Pumpe (1) als eine Funktion der Versorgungsspannung eines elektrischen Reihenschlußmotors ermittelt wird, welcher die Hydraulikpumpe (1) antreibt.
  3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Zuleitung der Pumpe (1) aus dem Drehwinkel des Felds eines Synchronmotors ermittelt wird.
  4. Verfahren nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, daß der mechanische Anschlag oder die Endpositionen der hydraulischen Einrichtung durch Überwachen des amperometrischen Werts eines einem Elektromotor zugeführten Stroms erfaßt und gespeichert werden, welcher die Hydraulikpumpe (1) antreibt, daß der Strom abrupt ansteigt, wenn diese Endpositton erreicht wird, und die amperometrisch erfaßten Endanschläge der Bewegung für darauffolgende Bewegungen genutzt werden, um eine geeignete stufenlose Geschwindigkeitsänderung mit dem Ziel einzuleiten, abrupte Stoßbelastungen oder Kontaktbelastungen an den Endpositionen zu vermeiden.
  5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, daß der Einsatz einer zu Beginn festgelegten stufenlosen Geschwindigkeitsänderungsabfolge sichergestellt wird, und daß die Bewegung beim ersten Mal langsamer ausgeführt wird, bevor die Endanschläge erreicht werden, so daß Stoßbelastungen auch bei diesem ersten Mal vermieden werden.
  6. Verfahren nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, daß die Bewegung normalerweise angehalten wird, bevor die mechanisch definierten Endanschläge erreicht werden.
  7. Vorrichtung zur Durchführung des Verfahrens nach Anspruch 1, welche eine Steuereinrichtung in Form eines Computers (4) und eine Meßeinrichtung in Form eines Spannungssensors umfaßt, welcher die Motorspannung des zum Bewegungsantrieb dienenden Motors erfaßt, dadurch gekennzeichnet, daß sie einen amperometrischen Stromsensor (9) für den dem Motor zugeführten Strom zur Erfassung der mechanischen Endpositionen oder der mechanischen Anschläge oder von Hindernissen bei der Bewegung umfaßt.
EP19970850047 1996-03-28 1997-03-26 Anordnung an Gabelhubwagen Expired - Lifetime EP0798260B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9601184 1996-03-28
SE9601184A SE510194C2 (sv) 1996-03-28 1996-03-28 Anordning vid truckar

Publications (3)

Publication Number Publication Date
EP0798260A2 EP0798260A2 (de) 1997-10-01
EP0798260A3 EP0798260A3 (de) 1998-12-16
EP0798260B1 true EP0798260B1 (de) 2003-05-28

Family

ID=20401978

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19970850047 Expired - Lifetime EP0798260B1 (de) 1996-03-28 1997-03-26 Anordnung an Gabelhubwagen

Country Status (3)

Country Link
EP (1) EP0798260B1 (de)
DE (1) DE69722298T2 (de)
SE (1) SE510194C2 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007051042A1 (de) 2007-10-25 2009-04-30 Jungheinrich Ag Verfahren zur Sensierung des Endanschlags eines hydraulischen Hubzylinders bei einem Flurförderzeug

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19952591B4 (de) * 1999-11-02 2004-07-15 Conti Temic Microelectronic Gmbh Hydrauliksystem
DE602005019047D1 (de) 2005-09-20 2010-03-11 Atlet Ab Verbessertes Kontrollsystem für ein Flurförderfahrzeug
US8935058B2 (en) * 2011-02-16 2015-01-13 Crown Equipment Corporation Materials handling vehicle estimating a speed of a movable assembly from a lift motor speed
FR2975089B1 (fr) * 2011-05-10 2013-04-26 Manitou Bf Dispositif de mesure de bras telescopique de manutention
DE102021132437A1 (de) 2021-12-09 2023-06-15 Jungheinrich Aktiengesellschaft Verfahren zum Betreiben eines Flurförderzeugs

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3675803A (en) * 1970-04-06 1972-07-11 Cascade Corp Load-handling apparatus with reach mechanism
JPH0742056B2 (ja) * 1989-06-15 1995-05-10 三菱電機株式会社 流体圧エレベータ制御装置
DE4220333A1 (de) * 1992-06-22 1993-12-23 Marco Systemanalyse Entw Verfahren zum Bestimmen des Kolbenweges in einem hydraulischen Arbeitszylinder
DE4306680C2 (de) * 1993-03-04 1995-02-16 Jungheinrich Ag Verfahren zur Bestimmung der Hubhöhe eines höhenverstellbaren Lastaufnahmemittels eines Flurförderzeugs

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007051042A1 (de) 2007-10-25 2009-04-30 Jungheinrich Ag Verfahren zur Sensierung des Endanschlags eines hydraulischen Hubzylinders bei einem Flurförderzeug
DE102007051042B4 (de) 2007-10-25 2023-01-26 Jungheinrich Aktiengesellschaft Verfahren zur Sensierung des Endanschlags eines hydraulischen Hubzylinders bei einem Flurförderzeug

Also Published As

Publication number Publication date
SE9601184D0 (sv) 1996-03-28
EP0798260A2 (de) 1997-10-01
SE510194C2 (sv) 1999-04-26
DE69722298D1 (de) 2003-07-03
EP0798260A3 (de) 1998-12-16
DE69722298T2 (de) 2004-04-01
SE9601184L (sv) 1997-09-29

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