EP1355066A1 - Control system for a load lifting device movable between a low and a high position - Google Patents

Control system for a load lifting device movable between a low and a high position Download PDF

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Publication number
EP1355066A1
EP1355066A1 EP03290924A EP03290924A EP1355066A1 EP 1355066 A1 EP1355066 A1 EP 1355066A1 EP 03290924 A EP03290924 A EP 03290924A EP 03290924 A EP03290924 A EP 03290924A EP 1355066 A1 EP1355066 A1 EP 1355066A1
Authority
EP
European Patent Office
Prior art keywords
valve
load
damping
descent
bearing member
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.)
Withdrawn
Application number
EP03290924A
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German (de)
French (fr)
Inventor
Benedito Lazaro
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.)
Hydroperfect International Inc
Original Assignee
Hydroperfect International Inc
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Filing date
Publication date
Application filed by Hydroperfect International Inc filed Critical Hydroperfect International Inc
Publication of EP1355066A1 publication Critical patent/EP1355066A1/en
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/044—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the return line, i.e. "meter out"
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/042—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the feed line, i.e. "meter in"
    • F15B11/0426—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the feed line, i.e. "meter in" by controlling the number of pumps or parallel valves switched on
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/20507—Type of prime mover
    • F15B2211/20515—Electric motor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20538—Type of pump constant capacity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40507—Flow control characterised by the type of flow control means or valve with constant throttles or orifices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/42—Flow control characterised by the type of actuation
    • F15B2211/426—Flow control characterised by the type of actuation electrically or electronically
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/45—Control of bleed-off flow, e.g. control of bypass flow to the return line
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/46—Control of flow in the return line, i.e. meter-out control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50536—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using unloading valves controlling the supply pressure by diverting fluid to the return line
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/615—Filtering means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7052—Single-acting output members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/75—Control of speed of the output member

Definitions

  • the invention relates to a control system of a load lifting device placed on a carrier movable between a low position and a high position, of the type comprising a hydraulic cylinder having a piston whose movement causes the climb and descent of the load carrying member and which is likely to be connected to either a source of fluid hydraulic pressure for the rise of a load, either to the hydraulic fluid reservoir by a return circuit for the descent movement of the load, the circuit of return comprising at least a first opening valve and closing the return circuit.
  • the present invention aims to propose a control system that presents a satisfactory solution to all the problems that have just been stated.
  • control system is characterized in that the return circuit comprises a bypass valve opening and closing a lane bypass, with a flow rate lower than that of the first valve, which is mounted in parallel to this last.
  • the second valve is equipped with a restrictor or flow restrictor, the if necessary, adjustable.
  • the combination of the two valves of the return circuit is a device for amortizing changes sudden displacement of the load bearing member when from the descent of it.
  • the system comprises in the circuit supplying hydraulic fluid under pressure of the cylinder a valve likely to constitute with the valve of diversion of the return circuit a device damping abrupt movements of the carrier organ load during his climb climb.
  • the closure of the bypass valve is carried out after closure of the return valve, after the lapse of a short duration of predetermined time.
  • the bypass valve is open for a short predetermined time before the opening of the return valve.
  • the bypass valve is open respectively to a delay predetermined time after start and end of start of the pump motor.
  • the valves are solenoid valves and the opening and the closing of these valves is controlled by the excitement of coils of these valves.
  • the load lifting device is only represented by its hydraulic cylinder 1 whose movable piston 2 ensures the displacement of the carrier member charge (not shown), the control system being designated by reference 4.
  • This system includes, so known per se, a motor-pump unit 6 whose engine 7 causes a pump 8 for sending fluid hydraulic pressure under a supply circuit in hydraulic fluid under pressure in the working chamber 10 of the cylinder 1, after having sucked it from the fluid in a tank not shown.
  • the sending of fluid under pressure in the chamber 10, by the pump 8, causes the race of piston work 2 and so the climb movement of the load carrying member of the lifting device.
  • the control system 4 also comprises a circuit back of the fluid from the working chamber 10 to tank, in which a solenoid valve is mounted main return 12 and, parallel to it, a bypass solenoid valve 14 of a lower flow rate by compared to that of the valve 12.
  • the valve 14 is equipped with this end of a reducer, restrictor, flow limiter, or flow regulator 15 which is adjustable or not but, of preferably, adjustable.
  • Valves 12 and 14 are valves standards in all-or-nothing operation. Downstream of the parallel connection of the two solenoid valves 12 and 14 are also provided, in series a flow limiter 17 and a filter 18. Such a filter is also provided in the suction circuit of the pump. It bears the reference 19. It is further noted that valves 12 and 14 are also equipped with such a filter designated by the reference 20.
  • FIG. 2 additionally to the diagram of FIG. solenoid valve 22 in the fluid supply circuit under pressure of the cylinder, whose function will be explained further.
  • Figure 2 further shows at 24 a relay of starting the engine 7.
  • FIGS. 3A to 3F hereinafter will be described different modes of operation of the control system according to the invention and thus the lifting device of charge during the descent run of the carrier organ of load.
  • Figure 3A illustrates a mode of operation of the system providing a cushioning effect at the beginning and at the end of the descent movement of the carrier organ of under the effect of orders given by the operator of the load lifting device and through programming internal system.
  • the operation of the system during the descent is determined by the state of openness or of closing the solenoid valves.
  • the diagrams illustrate these states by states of excitation or non excitation of coils of valves by the flow of a current of excitation indicated by the number 1 or the absence of a excitation current, indicated by the number 0.
  • the two solenoid valves are closed, that is to say the excitation currents flowing through the coils are zero.
  • Tdd1 the operator commands the start of the downhill movement, which triggers first and foremost immediately at this moment the current flow I14 to through the coil of the bypass valve 14 and so the opening of it. Therefore fluid hydraulic can flow through this valve, to a low flow.
  • Tdd2 the excitation of the coil of the solenoid valve 12 is triggered by the flow of a excitation current I12.
  • the carrier organ goes down first at a speed relatively weak and only after the delay ⁇ Tdd programmed into the system at the determined high speed by the valve 12. In other words the speed increases gently, that is, smoothly.
  • Tdf1 the operator commands the end of the movement of descent. End order of descent or descent stop at time Tdf1 immediately stops the current I12 excitation of the main valve 12 and thus the closing of it, while the valve 14 remains open for a time delay ⁇ Tdf until time Tdf2. Therefore, at the end of the descent, the return of the fluid continues for the duration of time ⁇ Tdf, at a flow rate weaker, through the bypass valve 14. when if the duration is too long, the speed increases or decreases too slowly.
  • the system according to the invention makes it possible perfectly control the amortization phases of movement of the load bearing member both to the end of the descent, the speed of the beginning and the end then decreasing slowly depending on the choice of these length of time to achieve the damping effect.
  • the durations of time should not be too short, for avoid the abrupt shifting effect that the invention aims to eliminate.
  • Figure 3B shows the conditions of a descent of the low speed load carrying member from the beginning to the end of the descent, the return to the fluid reservoir hydraulics being made exclusively through the valve of deviation 14 which is then opened thanks to the excitement of the coil of this valve between the times Tdd1 of the beginning of the descent and the time Tdf1 of the order of the end. Being given that the descent is at low speed, a depreciation at the beginning and at the end of the organ carrying charge is not necessary.
  • Figure 3C illustrates the way in which can get a start of the descent at low speed by an order appropriate to the opening time Tdd1 of the valve of bypass 14 and then by an order given by the operator at time Tdd2 opening of the main return valve 12. From Tdd2 the descent is done at the big speed enabled by the flow at high flow through this valve 12. At time Tdf1 the operator controls the closing the valve 12 so that the return of the fluid does not can be done only through the bypass valve 14. By therefore from Tdf1 the descent continues to the low speed determined by the low flow allowed by the valve 14.
  • Figure 3D illustrates a mode of operation where the beginning and end of the descent of the organ carrying charge are amortized, as in the case of Figure 3A, but which provides, after a lapse of time ⁇ Ta a following the descent movement at low speed by a new opening only of bypass valve 14.
  • FIGs 3E and 3F illustrate two modes of functioning that have in common that the operator commands first at time Tdd1 the opening of the valve of bypass 14 and thus the beginning of the descent of the organ load carrier at low speed and then, after a longer than the delay ⁇ Tdd ensuring a damping, the opening of the valve 12 thus triggering the descent at high speed.
  • the operator gives the order to the time Tdf1 of the end of descent with depreciation, which has the effect that the valve 12 closes at this moment causing the closure from the bypass valve 14 to the time Tdf2 after a lapse of relatively short time ⁇ Tdf of depreciation.
  • the end the descent is done without depreciation.
  • Figures 4A-4E illustrate a number of modes of operation during the rise of the organ load carrier.
  • Figure 4A illustrates the control of both solenoid valves 12 and 14 with damping at the beginning and at the end of the climb.
  • the rise command starts here as in any case by the excitation of relay 24 of starting the engine 7, illustrated by the curve I24.
  • the motor starts to drive the pump 8 and then, automatically, after the delay ⁇ Tmd, the valve 14 is open during the time ⁇ Tmv.
  • Depreciation is obtained by the fact that part of the pressurized fluid sent by the pump to the cylinder 1 pass by the bypass valve 14.
  • the valve 22 in the circuit supply of the jack in pressurized fluid has for function to allow the flow of fluid from the pump to cylinder, but not in the opposite direction during the rise phase with depreciation.
  • the valve 22 constitutes thus, with the bypass valve 14 of the return circuit, a device for damping changes in movements abruptness of the load-bearing organ during its race mounted, the valve 22 being thus open to allow the flow of fluid to the cylinder, but not in the direction reverse.
  • Figure 4B illustrates the climb with a start and a end of climb amortized, the climb being done elsewhere to low speed because the bypass valve 14 remains open after opening at the beginning of the climb up to the end.
  • Figure 3C illustrates the case of a large climb speed, with damping at the beginning, as in the figure 4A, with the difference however, that the rise to great speed ends at time Tfm by opening the valve diversion 14. Then the rise continues at low speed, the start relay 24 remaining of course excited.
  • FIG. 4D illustrates a rise at low speed up to the intermediate time Tm i at which the bypass valve is closed so that the continuation of the rise is at a high speed but ends in accordance with FIG. 4b, with damping, by a new opening of the bypass valve 14 during a short programmed damping time ⁇ Tmf.
  • FIG. 4E stands out of Figure 4D in that the climb starts with depreciation, is then done at low speed and then high speed but plans a small climb end speed during the period by opening the valve diversion 14.
  • valve 22 is used as load restraint when using the climbing system. Indeed, during the start-up phase of the electric motor 7, part of the flow is brought to pass through the valve 14 for a predetermined time. In the absence of the valve 22, the load would come down during all the opening time of the valve 14 which can be called the load retaining valve. During the descent, valve 22 is simultaneously open with the valve 14.
  • bypass valve 14 still at least another bypass valve, at a rate if applicable different, to be able to obtain a climb process or of descent adaptable to certain requirements concerning the operation of the lifting device.
  • solenoid valves used in the context of the invention are standard valves that work in all or nothing.
  • a bypass valve at a small flow rate, could use a valve equipped with a flow limiter adjustable.
  • the command of a beginning or an end of climb or descent with depreciation is done by a single command the operator, who then operates a single organ provided for in this end so that, at first, one of the two valves is actuated, which leads automatically, after a predetermined time the actuation of the other valve.
  • the delay between the two actuations should be chosen so as not to be too in short, not to provoke a sudden change in operation and mechanical stresses that in result.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Forklifts And Lifting Vehicles (AREA)

Abstract

The system comprises a hydraulic actuator (1) having a piston (2) whose movement is driven by the rise and fall of the load carrying part and can be alternately connected to a hydraulic fluid pump (8) and a fluid reservoir by a return circuit comprising a first opening and closing valve (12). The return circuit comprises an opening and closing diversion valve (14) with a flow rate less than that of the first valve.

Description

L'invention concerne un système de commande d'un dispositif de levage de charge placé sur un organe porteur déplaçable entre une position basse et une position élevée, du type comprenant un vérin hydraulique ayant un piston dont le mouvement entraíne le déplacement de montée et de descente de l'organe porteur de charge et qui est susceptible d'être connecté, soit à une source de fluide hydraulique sous pression pour la montée d'une charge, soit au réservoir du fluide hydraulique par un circuit de retour pour le déplacement de descente de la charge, le circuit de retour comprenant au moins une première valve d'ouverture et de fermeture du circuit de retour.The invention relates to a control system of a load lifting device placed on a carrier movable between a low position and a high position, of the type comprising a hydraulic cylinder having a piston whose movement causes the climb and descent of the load carrying member and which is likely to be connected to either a source of fluid hydraulic pressure for the rise of a load, either to the hydraulic fluid reservoir by a return circuit for the descent movement of the load, the circuit of return comprising at least a first opening valve and closing the return circuit.

Il est connu d'équiper notamment des gerbeurs d'un tel système de commande. Cependant, il s'est avéré que tout changement brusque du mouvement de la fourche porteuse de la charge d'un gerbeur, notamment l'arrêt du mouvement de descente de la fourche peut occasionner des vibrations dans de la structure mécanique et ainsi des sollicitations mécaniques importantes.It is known to equip such stackers with such control system. However, it turned out that everything abrupt change in fork movement the load of a stacker, including the stopping of the movement of down the fork can cause vibrations in mechanical structure and solicitations important mechanical

Pour remédier à cet inconvénient, il est connu d'utiliser comme valve de retour une valve retardée. Or, il s'est avéré qu'un tel système de commande a pour défaut majeur que le retard et ainsi la distance que parcourt la fourche entre l'instant de commande de l'arrêt et l'arrêt réel varie en fonction de la température environnante et de la charge. Il est également connu d'utiliser dans le circuit de retour une valve proportionnelle ce qui a pour inconvénient majeur de rendre plus complexe le système et d'augmenter son coût.To remedy this drawback, it is known to use as a return valve a delayed valve. But he turned out that such a control system is lacking major than the delay and thus the distance traveled by the fork between the moment of control of the stop and the stop actual varies according to the surrounding temperature and load. It is also known to use in the return circuit a proportional valve which has for major disadvantage of making the system more complex and to increase its cost.

La présente invention a pour but de proposer un système de commande qui présente une solution satisfaisante à l'ensemble des problèmes qui viennent d'être énoncés.The present invention aims to propose a control system that presents a satisfactory solution to all the problems that have just been stated.

Pour atteindre ce but, le système de commande est caractérisé en ce que le circuit de retour comprend une valve de dérivation d'ouverture et de fermeture d'une voie de dérivation, d'un débit plus faible que celui de la première valve, qui est monté en parallèle à cette dernière. To achieve this goal, the control system is characterized in that the return circuit comprises a bypass valve opening and closing a lane bypass, with a flow rate lower than that of the first valve, which is mounted in parallel to this last.

Selon une caractéristique de l'invention, la seconde valve est équipée d'un restricteur ou limiteur de débit, le cas échéant ajustable.According to one characteristic of the invention, the second valve is equipped with a restrictor or flow restrictor, the if necessary, adjustable.

Selon une caractéristique avantageuse de l'invention, la combinaison des deux valves du circuit de retour constitue un dispositif d'amortissement des changements brusques du déplacement de l'organe porteur de charge lors de la descente de celui-ci.According to an advantageous characteristic of the invention, the combination of the two valves of the return circuit is a device for amortizing changes sudden displacement of the load bearing member when from the descent of it.

Selon une autre caractéristique avantageuse de l'invention, le système comprend dans le circuit d'alimentation en fluide hydraulique sous pression du vérin une valve susceptible de constituer avec la valve de dérivation du circuit de retour un dispositif d'amortissement des mouvements brusques de l'organe porteur de charge lors de sa course de montée.According to another advantageous characteristic of the invention, the system comprises in the circuit supplying hydraulic fluid under pressure of the cylinder a valve likely to constitute with the valve of diversion of the return circuit a device damping abrupt movements of the carrier organ load during his climb climb.

Selon encore une autre caractéristique de l'invention, pour obtenir un amortissement de l'arrêt de l'organe porteur de charge lors de sa descente, la fermeture de la valve de dérivation est réalisée après la fermeture de la valve de retour, après l'écoulement d'une courte durée de temps prédéterminée.According to yet another characteristic of the invention, to get a cushion of the organ stop load carrier during his descent, the closure of the bypass valve is carried out after closure of the return valve, after the lapse of a short duration of predetermined time.

Selon une autre caractéristique de l'invention, pour amortir le début du déplacement de descente de l'organe porteur de charge, la valve de dérivation est ouverte pendant un court délai de temps prédéterminé avant l'ouverture de la valve de retour.According to another characteristic of the invention, for cushion the beginning of the descent movement of the organ load carrier, the bypass valve is open for a short predetermined time before the opening of the return valve.

Selon encore une autre caractéristique avantageuse de l'invention, pour amortir le début et l'arrêt du déplacement de montée de l'organe porteur de charge, la valve de dérivation est ouverte respectivement à un délai de temps prédéterminé après le début et la fin du démarrage du moteur de la pompe.According to yet another advantageous characteristic of the invention, to dampen the start and stop of the movement of the load carrying member, the bypass valve is open respectively to a delay predetermined time after start and end of start of the pump motor.

Selon une autre caractéristique de l'invention, les valves sont des électrovalves et l'ouverture et la fermeture de ces valves est commandée par l'excitation des bobines de ces valves.According to another characteristic of the invention, the valves are solenoid valves and the opening and the closing of these valves is controlled by the excitement of coils of these valves.

L'invention sera mieux comprise, et d'autres buts, caractéristiques, détails et avantages de celle-ci apparaítront plus clairement dans la description explicative qui va suivre faite en référence aux dessins schématiques annexés donnés uniquement à titre d'exemple illustrant deux modes de réalisation de l'invention et dans lesquels :

  • la figure 1 est une représentation schématique d'un premier mode de réalisation du système de commande d'un dispositif de levage de charge selon l'invention ;
  • la figure 2 est une représentation schématique d'un deuxième mode de réalisation d'un système de commande d'un dispositif de levage de charge selon l'invention ;
  • les figures 3A à 3F illustrent schématiquement différents états de fonctionnement du système de commande selon la figure 1, lors de la descente de l'organe porteur de charge du dispositif de levage, selon l'invention, et
  • les figures 4A à 4E illustrent schématiquement différents états de fonctionnement du système de commande selon l'invention, lors de la montée de l'organe porteur de charge du dispositif de levage.
The invention will be better understood, and other objects, characteristics, details and advantages thereof will appear more clearly in the explanatory description which follows, with reference to the appended schematic drawings given solely by way of example, illustrating two modes of embodiment of the invention and in which:
  • Figure 1 is a schematic representation of a first embodiment of the control system of a load lifting device according to the invention;
  • Figure 2 is a schematic representation of a second embodiment of a control system of a load lifting device according to the invention;
  • FIGS. 3A to 3F schematically illustrate different operating states of the control system according to FIG. 1, during the descent of the load-bearing member of the lifting device, according to the invention, and
  • FIGS. 4A to 4E schematically illustrate various operating states of the control system according to the invention, during the rise of the load-bearing member of the lifting device.

Sur la figure 1 le dispositif de levage de charge est seulement représenté par son vérin hydraulique 1 dont le piston mobile 2 assure le déplacement de l'organe porteur de charge (non représenté), le système de commande étant désigné par la référence 4. Ce système comporte, de façon connue en soi, un groupe moto-pompe 6 dont le moteur 7 entraíne une pompe 8 destinée à envoyer du fluide hydraulique sous pression par un circuit d'alimentation en fluide hydraulique sous pression dans la chambre de travail 10 du vérin 1, après l'avoir aspiré du fluide dans un réservoir non représenté. L'envoi du fluide sous pression dans la chambre 10, par la pompe 8, provoque la course de travail du piston 2 et ainsi le mouvement de montée de l'organe porteur de charge du dispositif de levage.In Figure 1 the load lifting device is only represented by its hydraulic cylinder 1 whose movable piston 2 ensures the displacement of the carrier member charge (not shown), the control system being designated by reference 4. This system includes, so known per se, a motor-pump unit 6 whose engine 7 causes a pump 8 for sending fluid hydraulic pressure under a supply circuit in hydraulic fluid under pressure in the working chamber 10 of the cylinder 1, after having sucked it from the fluid in a tank not shown. The sending of fluid under pressure in the chamber 10, by the pump 8, causes the race of piston work 2 and so the climb movement of the load carrying member of the lifting device.

Le système de commande 4 comporte également un circuit de retour du fluide de la chambre de travail 10 au réservoir, dans lequel sont montées une électrovalve principal de retour 12 et, en parallèle à celle-ci, une électrovalve de dérivation 14 d'un débit plus faible par rapport à celui de la valve 12. La valve 14 est équipée à cette fin d'un réducteur, restricteur, limiteur de débit, ou régulateur de débit 15 qui est ajustable ou non mais, de préférence, ajustable. Les valves 12 et 14 sont des valves standards à fonctionnement en tout ou rien. En aval du montage en parallèle des deux électrovalves 12 et 14 sont également prévus, en série un limiteur de débit 17 et un filtre 18. Un tel filtre est également prévu dans le circuit d'aspiration de la pompe. Il porte la référence 19. On constate en outre que les valves 12 et 14 aussi sont équipées d'un tel filtre désigné par la référence 20.The control system 4 also comprises a circuit back of the fluid from the working chamber 10 to tank, in which a solenoid valve is mounted main return 12 and, parallel to it, a bypass solenoid valve 14 of a lower flow rate by compared to that of the valve 12. The valve 14 is equipped with this end of a reducer, restrictor, flow limiter, or flow regulator 15 which is adjustable or not but, of preferably, adjustable. Valves 12 and 14 are valves standards in all-or-nothing operation. Downstream of the parallel connection of the two solenoid valves 12 and 14 are also provided, in series a flow limiter 17 and a filter 18. Such a filter is also provided in the suction circuit of the pump. It bears the reference 19. It is further noted that valves 12 and 14 are also equipped with such a filter designated by the reference 20.

Le mode de réalisation représenté sur la figure 2 comporte, supplémentairement au schéma de la figure 1 une électrovalve 22 dans le circuit d'alimentation en fluide sous pression du vérin, dont la fonction sera expliquée plus loin. La figure 2 montre en outre en 24 un relais de démarrage du moteur 7.The embodiment shown in FIG. 2 additionally to the diagram of FIG. solenoid valve 22 in the fluid supply circuit under pressure of the cylinder, whose function will be explained further. Figure 2 further shows at 24 a relay of starting the engine 7.

Concernant les électrovalves 12, 14, 22, elles comportent une bobine d'excitation non représentée.Concerning the solenoid valves 12, 14, 22, they comprise a not shown excitation coil.

En se référant aux figures 3A à 3F on décrira ci-après différents modes de fonctionnement du système de commande selon l'invention et ainsi du dispositif de levage de charge pendant la course de descente de l'organe porteur de la charge.Referring to FIGS. 3A to 3F, hereinafter will be described different modes of operation of the control system according to the invention and thus the lifting device of charge during the descent run of the carrier organ of load.

La figure 3A illustre un mode de fonctionnement du système procurant un effet d'amortissement au début et à la fin du déplacement de descente de l'organe porteur de charge, sous l'effet des ordres donnés par l'opérateur du dispositif de levage de charge et grâce à la programmation interne du système. Le fonctionnement du système lors de la descente est déterminé par l'état d'ouverture ou de fermeture des électrovalves. Les schémas illustrent ces états par les états d'excitation ou non excitation des bobines des valves par l'écoulement d'un courant d'excitation indiqué par le chiffre 1 ou l'absence d'un courant d'excitation, indiqué par le chiffre 0.Figure 3A illustrates a mode of operation of the system providing a cushioning effect at the beginning and at the end of the descent movement of the carrier organ of under the effect of orders given by the operator of the load lifting device and through programming internal system. The operation of the system during the descent is determined by the state of openness or of closing the solenoid valves. The diagrams illustrate these states by states of excitation or non excitation of coils of valves by the flow of a current of excitation indicated by the number 1 or the absence of a excitation current, indicated by the number 0.

Avant le début de la descente de l'organe porteur de charge, les deux électrovalves sont fermées, c'est-à-dire les courants d'excitation traversant les bobines sont zéro. A l'instant du temps Tdd1 l'opérateur commande le début du mouvement de descente, ce qui déclenche tout d'abord et immédiatement à cet instant l'écoulement du courant I14 à travers la bobine de la valve de dérivation 14 et ainsi l'ouverture de celle-ci. Par conséquent du fluide hydraulique peut s'écouler à travers cette valve, à un faible débit. Après un délai de temps ΔTdd prédéterminé, à l'instant de temps Tdd2, l'excitation de la bobine de l'électrovalve 12 est déclenchée, par l'écoulement d'un courant d'excitation I12. Etant donné que le retour du fluide de la chambre de travail 10 au réservoir se fait tout d'abord à un débit relativement faible à travers la valve de dérivation 14 et seulement ensuite, après la durée de temps prédéterminée relativement courte Tdd, à un débit plus élevé à travers la valve de retour principal 12, l'organe porteur descend tout d'abord à une vitesse relativement faible et seulement après le délai ΔTdd programmé dans le système à la grande vitesse déterminée par la valve 12. Autrement dit la vitesse accroít doucement, c'est-à-dire sans à coup. A l'instant de temps Tdf1, l'opérateur commande la fin du déplacement de descente. L'ordre de fin de descente ou d'arrêt de descente au temps Tdf1 provoque immédiatement l'arrêt du courant d'excitation I12 de la valve principale 12 et ainsi la fermeture de celle-ci, tandis que la valve 14 reste encore ouverte pendant un délai de temps ΔTdf jusqu'au temps Tdf2. Par conséquent, à la fin de la descente, le retour du fluide continue pendant la durée de temps ΔTdf, à un débit plus faible, à travers la valve de dérivation 14. lorsque si la durée est trop longue, la vitesse accroít ou décroít trop lentement.Before the start of the descent of the carrier organ charge, the two solenoid valves are closed, that is to say the excitation currents flowing through the coils are zero. At the instant of time Tdd1 the operator commands the start of the downhill movement, which triggers first and foremost immediately at this moment the current flow I14 to through the coil of the bypass valve 14 and so the opening of it. Therefore fluid hydraulic can flow through this valve, to a low flow. After a predetermined time delay ΔTdd, at the instant of time Tdd2, the excitation of the coil of the solenoid valve 12 is triggered by the flow of a excitation current I12. Since the return of the fluid from the working chamber 10 to the tank is done first of all at a relatively low flow through the bypass valve 14 and only then, after the duration predetermined time relatively short Tdd, at a rate higher through the main return valve 12, the carrier organ goes down first at a speed relatively weak and only after the delay ΔTdd programmed into the system at the determined high speed by the valve 12. In other words the speed increases gently, that is, smoothly. At the moment of time Tdf1, the operator commands the end of the movement of descent. End order of descent or descent stop at time Tdf1 immediately stops the current I12 excitation of the main valve 12 and thus the closing of it, while the valve 14 remains open for a time delay ΔTdf until time Tdf2. Therefore, at the end of the descent, the return of the fluid continues for the duration of time ΔTdf, at a flow rate weaker, through the bypass valve 14. when if the duration is too long, the speed increases or decreases too slowly.

On comprendra aisément, en maintenant constantes les durées de temps ΔTdd et ΔTdf, par exemple à l'aide d'un dispositif électronique pourvu d'un quartz de stabilisation, le système selon l'invention permet de maítriser parfaitement les phases d'amortissement du déplacement de l'organe porteur de charge aussi bien à la fin qu'au début de la descente, la vitesse du début et à la fin diminuant alors doucement en fonction du choix de ces durées de temps pour obtenir l'effet d'amortissement. Les durées de temps ne doivent pas être trop courtes, pour éviter l'effet de changement de vitesse brusque que l'invention vise à éliminer.It will be easy to understand, by keeping constant the durations of time ΔTdd and ΔTdf, for example using a electronic device provided with a quartz crystal stabilization, the system according to the invention makes it possible perfectly control the amortization phases of movement of the load bearing member both to the end of the descent, the speed of the beginning and the end then decreasing slowly depending on the choice of these length of time to achieve the damping effect. The durations of time should not be too short, for avoid the abrupt shifting effect that the invention aims to eliminate.

La figure 3B montre les conditions d'une descente de l'organe porteur de charge à petite vitesse du début à la fin de la descente, le retour au réservoir du fluide hydraulique se faisant exclusivement à travers la valve de déviation 14 qui est alors ouverte grâce à l'excitation de la bobine de cette valve entre les temps Tdd1 du début de la descente et le temps Tdf1 de l'ordre de la fin. Etant donné que la descente se fait à faible vitesse, un amortissement au début et à l'arrêt de l'organe porteur de charge n'est pas nécessaire.Figure 3B shows the conditions of a descent of the low speed load carrying member from the beginning to the end of the descent, the return to the fluid reservoir hydraulics being made exclusively through the valve of deviation 14 which is then opened thanks to the excitement of the coil of this valve between the times Tdd1 of the beginning of the descent and the time Tdf1 of the order of the end. Being given that the descent is at low speed, a depreciation at the beginning and at the end of the organ carrying charge is not necessary.

La figure 3C illustre la manière selon laquelle on peut obtenir un début de la descente à faible vitesse par un ordre approprié au temps Tdd1 d'ouverture de la valve de dérivation 14 et ensuite par un ordre donné par l'opérateur au temps Tdd2 d'ouverture de la valve de retour principale 12. A partir de Tdd2 la descente se fait à la grande vitesse permis par l'écoulement à grand débit à travers cette valve 12. Au temps Tdf1 l'opérateur commande la fermeture de la valve 12 si bien que le retour du fluide ne peut se faire qu'à travers la valve de dérivation 14. Par conséquent à partir de Tdf1 la descente continue à la petite vitesse déterminée par le débit faible permis par la valve 14.Figure 3C illustrates the way in which can get a start of the descent at low speed by an order appropriate to the opening time Tdd1 of the valve of bypass 14 and then by an order given by the operator at time Tdd2 opening of the main return valve 12. From Tdd2 the descent is done at the big speed enabled by the flow at high flow through this valve 12. At time Tdf1 the operator controls the closing the valve 12 so that the return of the fluid does not can be done only through the bypass valve 14. By therefore from Tdf1 the descent continues to the low speed determined by the low flow allowed by the valve 14.

La figure 3D illustre un mode de fonctionnement où le début et la fin de la descente de l'organe porteur de charge sont amortis, comme dans le cas de la figure 3A, mais qui prévoit, après un laps de temps d'arrêt ΔTa une suite du déplacement de descente à petite vitesse par une nouvelle ouverture seulement de la valve de dérivation 14.Figure 3D illustrates a mode of operation where the beginning and end of the descent of the organ carrying charge are amortized, as in the case of Figure 3A, but which provides, after a lapse of time ΔTa a following the descent movement at low speed by a new opening only of bypass valve 14.

Les figures 3E et 3F illustrent deux modes de fonctionnement qui ont en commun que l'opérateur commande tout d'abord au temps Tdd1 l'ouverture de la valve de dérivation 14 et ainsi le début de la descente de l'organe porteur de charge à petite vitesse et ensuite, après un délai de temps supérieur au délai ΔTdd assurant un amortissement, l'ouverture de la valve 12 déclenchant ainsi la descente à grande vitesse. Selon la figure 3E l'opérateur donne l'ordre au temps Tdf1 de la fin de descente avec amortissement, ce qui a pour effet que la valve 12 se ferme à cet instant en entraínant la fermeture de la valve de dérivation 14 au temps Tdf2 après un laps de temps relativement court ΔTdf d'amortissement. Dans le cadre du mode de fonctionnement selon la figure 3F, la fin de la descente se fait sans amortissement. L'opérateur commande au temps Tdf1 la fermeture de la valve principale 12, et, plus tard, donne l'ordre de fermeture de la valve de dérivation 14 au temps Tdf2.Figures 3E and 3F illustrate two modes of functioning that have in common that the operator commands first at time Tdd1 the opening of the valve of bypass 14 and thus the beginning of the descent of the organ load carrier at low speed and then, after a longer than the delay ΔTdd ensuring a damping, the opening of the valve 12 thus triggering the descent at high speed. According to Figure 3E the operator gives the order to the time Tdf1 of the end of descent with depreciation, which has the effect that the valve 12 closes at this moment causing the closure from the bypass valve 14 to the time Tdf2 after a lapse of relatively short time ΔTdf of depreciation. In the framework of the operating mode according to Figure 3F, the end the descent is done without depreciation. The operator time control Tdf1 closing the main valve 12, and later gives the closing order of the valve bypass 14 at time Tdf2.

Les figures 4A à 4E illustrent un certain nombre de modes de fonctionnement lors de la montée de l'organe porteur de charge.Figures 4A-4E illustrate a number of modes of operation during the rise of the organ load carrier.

La figure 4A illustre la commande des deux électrovalves 12 et 14 avec amortissement au début et à la fin de la montée. La commande de la montée débute ici comme dans tous les cas par l'excitation du relais 24 de démarrage du moteur 7, illustrée par la courbe I24. On obtient le début de la montée amortie lorsque, après l'excitation du relais 24, après un délai ΔTmd d'une courte durée prédéterminée, on ouvre au temps Tmd2 la valve de dérivation 14. Puis on ferme cette valve après un délai approprié ΔTmv. Pour un début de montée amorti, le délai de temps ΔTmd est programmé. Autrement dit, il suffit que l'opérateur commande au temps Tmd1 le début de la montée pour que le relais 24 soit excité, le moteur commence à entraíner la pompe 8 et ensuite, automatiquement, après le délai ΔTmd, la valve 14 soit ouverte pendant le temps ΔTmv. L'amortissement est obtenu par le fait qu'une partie du fluide sous pression envoyée par la pompe au vérin 1 passe par la valve de dérivation 14. La valve 22 dans le circuit d'alimentation du vérin en fluide sous pression a pour fonction de permettre l'écoulement du fluide de la pompe au vérin, mais non pas dans le sens inverse au cours de la phase de montée avec amortissement. La valve 22 constitue ainsi, avec la valve de dérivation 14 du circuit de retour, un dispositif d'amortissement des changements de mouvements brusques de l'organe porteur de charges lors de sa course de montée, la valve 22 étant donc ouverte pour permettre l'écoulement de fluide au vérin, mais non pas dans le sens inverse.Figure 4A illustrates the control of both solenoid valves 12 and 14 with damping at the beginning and at the end of the climb. The rise command starts here as in any case by the excitation of relay 24 of starting the engine 7, illustrated by the curve I24. We gets the start of the amortized climb when, after the excitation of the relay 24, after a delay ΔTmd of a short predetermined time, the valve valve is opened at time Tmd2 diversion 14. Then we close this valve after a delay appropriate ΔTmv. For a start of amortized climb, the delay time ΔTmd is programmed. In other words, it is enough that the operator orders at time Tmd1 the start of the climb for the relay 24 to be excited, the motor starts to drive the pump 8 and then, automatically, after the delay ΔTmd, the valve 14 is open during the time ΔTmv. Depreciation is obtained by the fact that part of the pressurized fluid sent by the pump to the cylinder 1 pass by the bypass valve 14. The valve 22 in the circuit supply of the jack in pressurized fluid has for function to allow the flow of fluid from the pump to cylinder, but not in the opposite direction during the rise phase with depreciation. The valve 22 constitutes thus, with the bypass valve 14 of the return circuit, a device for damping changes in movements abruptness of the load-bearing organ during its race mounted, the valve 22 being thus open to allow the flow of fluid to the cylinder, but not in the direction reverse.

Sur la figure 4A la fin de la montée est également amortie. Pour que la phase finale de la montée puisse se dérouler de cette façon, l'opérateur actionne au temps Tmfl un organe de commande pour que, à cet instant de temps, le relais de démarrage 24 cesse d'être excité. Ceci entraíne la fin de l'alimentation du vérin 1 en fluide hydraulique sous pression et provoque également à cet instant de temps l'ouverture de la valve de dérivation 14 pendant un délai de temps prédéterminé ΔTmf. Dans le cadre du mode de fonctionnement selon la figure 4A, le début et la fin, de la montée sont amortis et la montée se fait à grande vitesse du fait que, à l'exception des phases de début et la fin la valve de dérivation 14 est fermée.In Figure 4A the end of the climb is also damped. For the final phase of the climb to take place scroll down this way, the operator operates at Tmfl time a control member so that, at this moment of time, the Start relay 24 ceases to be energized. This leads the end of the supply of the jack 1 in hydraulic fluid under pressure and also causes at this moment of time the opening of the bypass valve 14 during a delay predetermined time ΔTmf. As part of the mode of operation according to Figure 4A, the beginning and the end, of the ascent are amortized and the climb is done with great speed of the fact that, with the exception of the beginning and the end of the bypass valve 14 is closed.

La figure 4B illustre la montée avec un début et une fin de montée amortis, la montée se faisant par ailleurs à petite vitesse du fait que la valve de dérivation 14 reste ouverte après son ouverture au début de la montée jusqu'à la fin.Figure 4B illustrates the climb with a start and a end of climb amortized, the climb being done elsewhere to low speed because the bypass valve 14 remains open after opening at the beginning of the climb up to the end.

La figure 3C illustre le cas d'une montée à grande vitesse, avec amortissement au début, comme sur la figure 4A, avec la différence cependant, que la montée à grande vitesse prend fin au temps Tfm par ouverture de la valve de dérivation 14. Puis la montée continue à petite vitesse, le relais de démarrage 24 restant bien entendu excité.Figure 3C illustrates the case of a large climb speed, with damping at the beginning, as in the figure 4A, with the difference however, that the rise to great speed ends at time Tfm by opening the valve diversion 14. Then the rise continues at low speed, the start relay 24 remaining of course excited.

La figure 4D illustre une montée à petite vitesse jusqu'au temps intermédiaire Tmi auquel la valve de dérivation est fermée de façon que la suite de la montée se fasse à grande vitesse mais prend fin conformément à la figure 4b, avec amortissement, par une nouvelle ouverture de la valve de dérivation 14 pendant un bref délai d'amortissement programmé ΔTmf.FIG. 4D illustrates a rise at low speed up to the intermediate time Tm i at which the bypass valve is closed so that the continuation of the rise is at a high speed but ends in accordance with FIG. 4b, with damping, by a new opening of the bypass valve 14 during a short programmed damping time ΔTmf.

Le mode de fonctionnement de la figure 4E se distingue de la figure 4D par le fait que la montée débute avec amortissement, se fait ensuite à petite vitesse puis à grande vitesse mais prévoit une fin de montée à petite vitesse pendant la période par ouverture de la valve de dérivation 14. The operating mode of FIG. 4E stands out of Figure 4D in that the climb starts with depreciation, is then done at low speed and then high speed but plans a small climb end speed during the period by opening the valve diversion 14.

Pour revenir à la valve 22, on voit que cette valve est utilisée en retenue de charge lors de l'emploi du système en montée. En effet, pendant la phase de démarrage du moteur électrique 7, une partie du débit est amenée à passer par la valve 14 pendant un temps déterminé. En l'absence de la valve 22, la charge descendrait pendant tout le temps d'ouverture de la valve 14 qui peut donc être appelée valve de retenue de charge. Lors de la descente, la valve 22 est simultanément ouverte avec la valve 14.To return to the valve 22, we see that this valve is used as load restraint when using the climbing system. Indeed, during the start-up phase of the electric motor 7, part of the flow is brought to pass through the valve 14 for a predetermined time. In the absence of the valve 22, the load would come down during all the opening time of the valve 14 which can be called the load retaining valve. During the descent, valve 22 is simultaneously open with the valve 14.

Il est à noter que de diverses modifications peuvent être apportées à l'invention telle que décrite ci-dessus et représentée sur les figures. Il est possible de prévoir parallèlement à la valve de dérivation 14 encore au moins une autre valve de dérivation, à un débit le cas échéant différent, pour pouvoir obtenir un processus de montée ou de descente adaptable à certaines exigences concernant le fonctionnement du dispositif de levage. Il est à noter que les électrovalves utilisés dans le cadre de l'invention sont des valves standards ayant un fonctionnement en tout ou rien. A titre de valve de dérivation, à petit débit, on pourrait utiliser une valve équipée d'un limiteur de débit réglable. Il est essentiel dans le cadre de l'invention, que la commande d'un début ou d'une fin de montée ou de descente avec amortissement se fait par une seule commande de l'opérateur, qui actionne alors un seul organe prévu à cette fin pour que, dans un premier temps, une des deux valves soit actionnée, ce qui entraíne automatiquement, après un temps prédéterminé l'actionnement de l'autre valve. Il est à noter que le délai entre les deux actionnements doit être choisi de façon à ne pas être trop bref, pour ne pas provoquer un changement brusque du fonctionnement et les sollicitations mécaniques qui en résulteraient.It should be noted that various modifications may be made to the invention as described above and shown in the figures. It is possible to predict parallel to the bypass valve 14 still at least another bypass valve, at a rate if applicable different, to be able to obtain a climb process or of descent adaptable to certain requirements concerning the operation of the lifting device. It is to highlight that the solenoid valves used in the context of the invention are standard valves that work in all or nothing. As a bypass valve, at a small flow rate, could use a valve equipped with a flow limiter adjustable. It is essential in the context of the invention, that the command of a beginning or an end of climb or descent with depreciation is done by a single command the operator, who then operates a single organ provided for in this end so that, at first, one of the two valves is actuated, which leads automatically, after a predetermined time the actuation of the other valve. It should be noted that the delay between the two actuations should be chosen so as not to be too in short, not to provoke a sudden change in operation and mechanical stresses that in result.

Claims (10)

Système de commande d'un dispositif de levage de charges, placé sur un organe porteur déplaçable entre une position basse et une position élevée, du type comprenant un vérin hydraulique (1) ayant un piston (2) dont le mouvement entraíne le déplacement de montée et de descente de l'organe porteur de charge et qui est susceptible d'être connecté alternativement à une source de fluide hydraulique sous pression pour la montée d'une charge et au réservoir du fluide hydraulique par un circuit de retour pour le déplacement de descente de la charge, le circuit de retour comprenant au moins une première valve (12) d'ouverture et de fermeture du circuit de retour ainsi qu'une valve de dérivation (14) d'ouverture et de fermeture présentant un débit plus faible que celui de la première valve (12) et qui est montée en parallèle à cette dernière, caractérisé en ce que tant la première valve (12) que la valve de déviation (14) sont des valves à fonctionnement en tout ou rien, et en ce qu'il comprend des moyens d'amortissement de changement de mouvement brusque de l'organe porteur de charge par la commande d'ouverture et de fermeture des valves par rapport au mouvement brusque de l'organe porteur de charge.A control system for a load lifting device, placed on a carrier member movable between a low position and a high position, of the type comprising a hydraulic cylinder (1) having a piston (2) whose movement causes the upward movement and descent of the load-bearing member and which is capable of being alternately connected to a source of hydraulic fluid under pressure for the rise of a load and to the reservoir of the hydraulic fluid by a return circuit for the descent displacement of the charge, the return circuit comprising at least a first valve (12) opening and closing the return circuit and a bypass valve (14) opening and closing having a lower flow rate than the one of the first valve (12) and which is mounted in parallel thereto, characterized in that both the first valve (12) and the deflection valve (14) are valves operated in all or nothing, and in that it comprises means for damping abrupt change of movement of the load-bearing member by the opening and closing control of the valves relative to the sudden movement of the load-bearing member. Système selon la revendication 1, caractérisé en ce que la valve de dérivation (14) est équipée d'un réducteur restricteur, limiteur de débit ou régulateur de débit (15), le cas échéant ajustable.System according to Claim 1, characterized in that the bypass valve (14) is equipped with a restrictor, a flow restrictor or a flow regulator (15), where appropriate adjustable. Système selon l'une des revendications 1 ou 2, caractérisé en ce que la combinaison des deux valves (12, 14) du circuit de retour constitue un dispositif d'amortissement des changements brusques du déplacement de l'organe porteur de charge lors de la descente de celui-ci.System according to one of claims 1 or 2, characterized in that the combination of the two valves (12, 14) of the return circuit is a device for damping abrupt changes in the displacement of the load-bearing member during the descent of it. Système selon l'une des revendications 1 à 3, caractérisé en qu'il comprend en outre, dans le circuit d'alimentation en fluide hydraulique sous pression du vérin hydraulique (1), une valve (22) susceptible de constituer avec la valve de dérivation (14) du circuit de retour un dispositif d'amortissement des changements de mouvements brusques de l'organe porteur de charges lors de sa course de montée, la valve (22) étant ouverte pour permettre l'écoulement de fluide au vérin, mais non pas dans le sens inverse.System according to one of claims 1 to 3, characterized in that it further comprises, in the hydraulic fluid supply circuit under pressure of the hydraulic cylinder (1), a valve (22) capable of constituting with the valve of bypass (14) of the return circuit means for damping abrupt changes in the load carrying member during its upward stroke, the valve (22) being open to allow fluid flow to the cylinder, but not in the opposite direction. Système selon l'une des revendications 1 à 4, caractérisé en ce que, pour obtenir un amortissement de l'arrêt de l'organe porteur de charge lors de sa descente, la fermeture de la valve de dérivation (14) est réalisée après la valve de retour principal (12), après l'écoulement d'une durée d'un temps d'amortissement prédéterminé (ΔTdf).System according to one of claims 1 to 4, characterized in that , to obtain a damping of the stopping of the load-bearing member during its descent, the closing of the bypass valve (14) is carried out after the main return valve (12), after the lapse of a duration of a predetermined damping time (ΔTdf). Système selon l'une des revendications 1 à 5, caractérisé en ce que, pour obtenir un amortissement du début du déplacement de descente de l'organe porteur de charge, la valve de dérivation (14) est ouverte à un délai de temps prédéterminé (ΔTdd) avant l'ouverture de la valve de retour principal (12).System according to one of Claims 1 to 5, characterized in that , in order to obtain damping of the start of the descent movement of the load-bearing member, the bypass valve (14) is open at a predetermined time ( ΔTdd) before opening the main return valve (12). Système selon l'une des revendications 1 à 6 caractérisé en ce que, pour obtenir un amortissement du début et de l'arrêt du déplacement de montée de l'organe porteur de charges, la valve de dérivation (14) est ouverte respectivement à un délai de temps prédéterminé (ΔTmd, ΔTmf) après le début et la fin du démarrage du moteur (7) de la pompe (8).System according to one of Claims 1 to 6, characterized in that , to obtain damping of the start and stop of the upward movement of the load-bearing member, the bypass valve (14) is respectively open to a predetermined time delay (ΔTmd, ΔTmf) after the beginning and the end of the starting of the motor (7) of the pump (8). Système selon l'une des revendications 1 à 7, caractérisé en ce que, pour obtenir un amortissement du début du déplacement de montée de l'organe porteur de charge, la valve de déviation (14) est ouverte à un délai de temps prédéterminé (ΔTmd) après le début du démarrage du moteur (7) de la pompe (8), puis est fermée après un délai prédéterminé (ΔTmv).System according to one of Claims 1 to 7, characterized in that , to obtain a damping of the start of the upward movement of the load-bearing member, the deflection valve (14) is open at a predetermined time ( ΔTmd) after starting the motor (7) of the pump (8), and is then closed after a predetermined time (ΔTmv). Système selon l'une des revendications 1 à 8, caractérisé en ce que, pour obtenir un amortissement de l'arrêt du déplacement de montée de l'organe porteur de charge, la valve de déviation (14) est ouverte pendant un délai de temps prédéterminé (ΔTmf) après la fin du démarrage du moteur (7) de la pompe (8).System according to one of claims 1 to 8, characterized in that , to obtain damping of the stop of the upward movement of the load-bearing member, the deflection valve (14) is open for a period of time predetermined (ΔTmf) after the end of the starting of the motor (7) of the pump (8). Système selon l'une des revendications 1 à 7 caractérisé en ce que les valves (12, 14) sont des électrovalves et l'ouverture et la fermeture de ces valves est commandée par l'excitation des bobines de ces valves.System according to one of claims 1 to 7 characterized in that the valves (12, 14) are solenoid valves and the opening and closing of these valves is controlled by the excitation of the coils of these valves.
EP03290924A 2002-04-15 2003-04-14 Control system for a load lifting device movable between a low and a high position Withdrawn EP1355066A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0204684 2002-04-15
FR0204684A FR2838419B1 (en) 2002-04-15 2002-04-15 SYSTEM FOR CONTROLLING A LOAD LIFTING DEVICE PLACED ON A CARRIER MOVABLE BETWEEN A LOW POSITION AND A HIGH POSITION

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EP1355066A1 true EP1355066A1 (en) 2003-10-22

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EP (1) EP1355066A1 (en)
FR (1) FR2838419B1 (en)

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US7344000B2 (en) * 2004-09-23 2008-03-18 Crown Equipment Corporation Electronically controlled valve for a materials handling vehicle
US20100300279A1 (en) * 2009-06-02 2010-12-02 George Kadlicko Point Of Use Actuator
KR101914467B1 (en) 2011-02-16 2018-11-05 크라운 이큅먼트 코포레이션 Materials handling vehicle estimating a speed of a movable assembly from a lift motor speed
DE102018104586A1 (en) 2018-02-28 2019-08-29 Jungheinrich Aktiengesellschaft Truck with at least one hydraulic mast lifting cylinder
CA3039305A1 (en) * 2018-04-06 2019-10-06 The Raymond Corporation Auxiliary hydraulic circuit filtering systems and methods
JP7131429B2 (en) * 2019-02-25 2022-09-06 株式会社島津製作所 Hydraulic system and method of controlling hydraulic system

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FR2838419A1 (en) 2003-10-17
FR2838419B1 (en) 2004-10-29

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