EP2123590A1 - Method for controlling the orientation movement of the rotating part of a tower crane - Google Patents

Abstract

The method involves increasing maximum value of orientation torque produced by an electric motor (16) when a tower crane is in service and while satisfying a condition that wind velocity (V) exceeds a given threshold value. The electric motor is arranged in a gear motor (15) of an orientation electro-mechanism (12) that is connected to a rotating upper part of the crane. The maximum value of the orientation torque is increased based on an angular position of a boom of the rotating part of the crane. An independent claim is also included for a motorized device for controlling orientation movement of a rotating upper part of a tower crane.

Description

The present invention relates to the technical field of tower cranes. More particularly, this invention relates to the motorized control of the steering movement of the rotating upper part of a tower crane.

A tower crane is usually composed of two main parts, which are on the one hand a non-rotating vertical pylon also designated as "mast", and on the other hand a rotating upper part, that is to say orientable around a vertical axis of rotation. The rotating upper part, mounted at the top of the mast, is itself composed of an arrow, which extends on one side of the vertical axis of rotation of this rotating part, and a counter-flange equipped with a ballast, which extends on the other side of the vertical axis of rotation. The rotation of the rotating part about this vertical axis is controlled by a motorized assembly, using electrical energy, hereinafter referred to as the "electro-orientation mechanism".

To realize the rotational mounting of the rotating part at the top of the mast of a tower crane, it is usually provided, between the arrow and the counterpart of the rotating part, an orientation ring consisting of two concentric rings, with a ring stationary connected to the top of the mast and with a movable ring secured to the rotating part, rings between which are mounted cylindrical balls or rollers.

To control the rotation of the rotational part thus mounted, the electro-orientation mechanism usually comprises an electric gear motor integral with this rotating part, which gear motor rotates a pinion with a vertical axis which meshes with a toothed wheel cut in the fixed ring of the orientation ring. Optionally, in the case where a large mechanical power must be transmitted to rotate the rotating part, two or more geared motors are provided, each geared motor rotating a pinion engaging with the same gear.

As examples of such referral mechanisms, reference is made to patent documents EP 1 422 188 and FR 2 907 109 .

When the tower crane is "out of service", that is to say outside the work periods of the crane, it is usually put "in wind vane": the rotating part is no longer braked in rotation, or it is only so reduced, so that it can move freely at any time, depending on the direction of the wind. The arrow then moves in the direction of the wind, while that the counterfleche is placed against the wind, because the surface of the arrow which is exposed to the wind is much superior to that of the counterfleche.

During periods of work of the tower crane, it is subjected to fatigue cycles, which result in particular from alternating rotations of the rotating part in one direction, in load, and returns "empty" of this rotating part. The mast of the crane then undergoes torque, which should be limited to a maximum torque value that can be supported by this mast.

For this purpose, the electro-mechanism of orientation of the crane is controlled by a computer which limits the value of the orientation torque to the maximum torque value which has been predefined.

It should also be noted that during the work periods of the crane, the rotating part thereof and in particular the boom has a significant wind, especially during the setting in motion, the effect of wind can be translate by an extra resistant couple.

The limitation of torque imposed by the computer, combined with the wind-resistant torque, causes for the crane operator a potential difficulty to control the rotation and the positioning of the boom, in particular the movement of the boom in load, in the presence of a especially if the wind has a speed greater than a certain threshold.

The patent FR 1 544 012 discloses an orientation movement control for a tower crane (without counterflash) in which, in order to overcome a torque of resistance due to a strong wind, provision is made for the actuation of an auxiliary gear unit acting on the crown toothed gear mechanism, in addition to the main geared motor unit. The addition of a second geared motor unit, occasional operation, entails a complication and an increase in cost.

The present invention aims to avoid these disadvantages, and its purpose is therefore to facilitate the driving of a tower crane, in the sense of better control of the orientation movement of the rotating part of the crane in the presence of wind, this in a simple way and in particular without addition of auxiliary gearmotor.

For this purpose, the subject of the invention is essentially a method of motorized control of the orientation movement of the rotating upper part of a tower crane, the rotating part being composed of an arrow and a counterfleche and this part rotating being associated with an electro-mechanism of orientation comprising at least one electric geared motor with electric motor and gearbox, the electric motor of which is electrically powered so as to produce an orientation torque transmitted to the rotating part of the crane, this pair having a maximum value, this method being characterized in that, when the crane is in service and for conditions comprising at least a wind speed greater than a given value, the maximum value of the steering torque that can be produced by the aforementioned electric motor is increased as long as these conditions persist.

Advantageously, the maximum value of the steering torque is increased in case of wind speed greater than a given value and for at least one additional condition, constituted by the fact that the length of the boom of the crane is greater than a value. given and / or that the moment of the load suspended under the arrow is greater than a given value or a given fraction of the maximum allowable moment.

If these conditions are fulfilled, the method of the invention provides, in particular, that the orientation torque can be increased, within the limit of the maximum value then increased, as a function of the angular position of the arrow and the wind direction, this in particular to increase the motor torque of the geared motor in the phases of "upwelling" by the arrow.

• une vitesse du vent supérieure à 50 km/heure,
• une longueur de flèche supérieure à 40 mètres,
• un moment de charge supérieur à 80% du moment de charge maximal admissible.

As an example of implementation of the method of the invention, the conditions to be met for an increase in the maximum value of the orientation torque can be:

• a wind speed greater than 50 km / h,
• an arrow length greater than 40 meters,
• a load moment greater than 80% of the maximum allowable load moment.

It is specified that "load moment" means the product of the weight of the load, lifted by the crane, by the span which is the horizontal distance between this load and the crane mast (or the axis of the crane). rotation of the rotating part).

The various parameters, taken into account in the method of the invention, are provided by appropriate sensors and / or by calculation. In particular, with regard to the charging moment, this can be obtained by calculation, from the weight of the load given by a ring strain gauge, and the range measured by a potentiometer located on the winch which serves to move the carriage along the arrow. One can also use a moment sensor that directly provides the load moment by measuring the displacement of the torque bars.

With the method of the invention, the maximum value of the torque that can be provided by the motor of the electro-orientation mechanism is increased for example by 15%, when the previously defined conditions are met. The mechanism then becomes capable of delivering more torque, provided that the crane operator requests a speed instruction such that this higher torque must be reached. No auxiliary gearmotor is necessary.

However, it is necessary to avoid the continuous use of such an increased torque value, because of the fatigue problems of the mason exposed above. Such inappropriate use may in particular result from a switch off, by the user, of the link between an output of a computer processing the information from the sensors to give the authorization to increase the torque, on the one hand , and an input of an actuator such as a frequency converter which controls the electric motor of the electro-orientation mechanism, on the other hand. For this purpose, the method of the invention advantageously further comprises a comparison between the state of the input of the actuator, such as a frequency converter, and the order given by the computer, and in the case where the state of this entry does not correspond to the order given by the computer, it occurs an automatic setting in degraded mode of the electro-orientation mechanism, for example by reducing its speed.

The invention also relates to a device for implementing the method defined above, in a motorized control device for the orientation movement of the rotating upper part of a tower crane, this device generally comprising known an electro-orientation mechanism which comprises at least one electric gear motor with electric motor and gearbox, the electric motor of which is electrically powered so as to produce an orientation torque transmitted to the rotating part of the crane, this pair having a maximum value, an actuator such as a frequency converter being provided for controlling the motor of the electro-orientation mechanism, this device being characterized by the fact that it comprises a computer provided with inputs that allow it to determine the wind speed and other parameters such as the length of the boom of the crane and the moment of the load suspended under the boom, and an output which is connected to an input of the actuator such as a frequency converter and which is suitable to deliver to this actuator, as a function of the parameters processed, an order authorizing an increase in the maximum value of the orientation torque.

Thanks to these specific means, the device of the invention makes it possible to increase punctually the engine torque of the electro-orientation mechanism, controlled by the frequency converter, to facilitate the driving of the crane in the presence of a wind of a certain strength.

• Figure 1 est une vue d'ensemble, de côté, d'une grue à tour pouvant être équipée du dispositif de commande conforme à la présente invention ;
• Figure 2 est une vue en plan par-dessus de la grue à tour de la figure 1 ;
• Figure 3 est un schéma synoptique du dispositif de commande selon l'invention, avec illustration de l'électro-mécanisme d'orientation dans une réalisation particulière ;
• Figure 4 est un autre schéma explicatif, illustrant la « logique » de fonctionnement du dispositif de commande selon l'invention, en particulier dans sa fonction d'autorisation d'une valeur maximale augmentée pour le couple d'orientation.

The invention will be better understood with the aid of the description which follows, with reference to the appended schematic drawing representing, by way of example, an embodiment of this device for controlling the orientation movement of the rotating part of the device. a tower crane:

• Figure 1 is an overall view, from the side, of a tower crane that can be equipped with the control device according to the present invention;
• Figure 2 is a plan view over the tower crane of the figure 1 ;
• Figure 3 is a block diagram of the control device according to the invention, with illustration of the electro-orientation mechanism in a particular embodiment;
• Figure 4 is another explanatory diagram, illustrating the "logic" of operation of the control device according to the invention, in particular in its authorization function of an increased maximum value for the steering torque.

Referring to Figures 1 and 2 , a tower crane comprises, in general, a mast 2 and a rotating part 3, mounted at the top of the mast 2. In the example shown, the mast 2 rises above a base frame fixed 4, which also carries a base ballast 5. This mast 2 is constituted by the assembly of a number of superposed mast elements, and it comprises a telescoping cage 6 for raising the mast by adding mast elements.

The rotating part 3 of the crane consists of an arrow 7 directed towards "the front", and a counter-flange 8 aligned with the arrow 7 but directed to the opposite, that is to say towards "the rear ", this rotating part 3 being orientable about a vertical axis A which coincides with the central axis of the mast 2. The arrow 7 serves as a runway for an arrow carriage 9, under which is suspended a lifting hook 10 which can be hung a load C. Thus, the load C can be moved in a horizontal movement called "distribution" (arrow D ), and also according to a vertical movement called lifting (arrow H). The counterfleche 8 is equipped at the rear with a ballast 11 which at least partially balances the weight of the boom 7 and the load C lifted by the hook 10.

Referring also to the figure 3 (bottom right), an electro-orientation mechanism 12 is disposed between the rotating part 3 and the top of the mast 2, this mechanism 12 also being located between the arrow 7 and the counter-flap 8. The orientation mechanism 12 comprises a fixed orientation ring 13, carried by the top of the mast 2, and a rotating pivot 14 integral with the rotating part 3. In the illustrated example, this mechanism 12 also comprises two similar geared motors 15, carried by the rotating pivot 14, each geared motor 15 consisting of an electric motor 16 and a gearbox 17. The output shaft of each gearbox 17 carries a pinion with a vertical axis, which meshes with a toothed wheel 18 cut in the ring gear. orientation 13. The two geared motors 15, more particularly their electric motors 16, are controlled by a frequency converter 19. The latter is itself controlled by the crane operator, posted in the driver's cab 20 of the crane, in particular for receiving r start and stop commands, and direction of rotation, as well as a speed reference.

According to the invention, and as shown by figure 3 it is associated with the frequency converter 19 a computer 21 with specific functions, which comprises various inputs 22, 23, 24 and an output 25, which is connected to an input of the frequency converter 19.

A first input 22 of the computer 21 is connected to an anemometer 26 which is carried by the crane, and which thus provides the computer 21 with a signal V representative of the wind speed in the immediate environment of the crane.

A second input 23 of the computer 21 is connected to a sensor 27 which indicates the range L, that is to say the horizontal distance between the boom carriage 9, thus the load C on the one hand, and the vertical axis On the other hand.

A third input 24 of the computer 21 is connected to a stress gauge torque ring 28, placed on a pulley which supports the lifting cable, which provides a signal representative of the weight P of the load C suspended from the lifting hook 10.

Thus, the computer 21 determines the instantaneous wind speed, and simultaneously it calculates the load moment, as a product of the range L and the weight P of the load C, in other words by multiplying the signal L received at the second input 23 by the signal P received at the third input 24.

The computer 21 "also" knows the parameter constituted by the total length Lf of the arrow 7, on which the wind is measured.

• longueur Lf de la flèche > x mètres
• vitesse du vent V > Y m/seconde
• moment de charge P x L > Z % de la valeur maximale admissible.

The computer 21 can thus perform a logical operation, symbolically illustrated on the figure 4 which consists of checking the meeting of three conditions:

• length Lf of the arrow> x meters
• wind speed V> Y m / second
• load moment P x L> Z% of the maximum permissible value.

If these three conditions are simultaneously met, the output 25 of the computer 21 delivers an operating authorization signal S with a maximum increased orientation torque, for example a torque increased by 15% compared to the usual maximum value. This authorization signal S is brought to an input of the frequency converter 19 which drives the respective electric motors 16 of the geared motors 15.

To control the geared motors 15, the computer 21 can also take into account two other parameters, which are the instantaneous angular position (angle "alpha 1") of the arrow 7, and the direction of the wind (angle "alpha 2"). The angular position "alpha 1" of the arrow 7 may be provided by an orientation sensor associated with the electro-orientation mechanism 12, such as the sensor described in the patent document. FR 2 907 109 supra. The direction of the "alpha 2" wind is indicated by a specific sensor of the "wind vane" type installed on the crane.

The computer 21 can thus determine, by comparing the "alpha 1" orientation of the arrow 7 and the "alpha 2" wind direction, whether a controlled rotation of the arrow 7 corresponds to a rise to the wind requiring a driving torque most important. If the authorization for increasing the maximum value of the orientation torque is present (in case of meeting the conditions explained above), an order in the form of the signal S is emitted and the engine torque can thus be effectively increased in the phases of upwelling. This command is coupled to the speed control and in particular to the speed setpoint given by the crane operator.

In addition, to avoid continuously using a torque value thus increased, the state of the input of the frequency converter 19 is constantly monitored, through a return link 30, to ensure that this input has not been switched off by the user. If the state of this input does not correspond to the order S given to the output 25 of the computer 21, then the electromechanism of orientation 12 is automatically put in degraded mode by the computer 21. In particular, the computer 21 sends then at another input of the frequency converter 19 a particular speed setpoint Vc, imposing a speed reduction for the orientation movement of the rotating part 3 of the crane.

• en prenant en compte des paramètres plus ou moins nombreux et divers, pour autoriser l'augmentation temporaire de la valeur maximale du couple d'orientation ;
• en modifiant le nombre des motoréducteurs de l'électro-mécanisme d'orientation, le motoréducteur pouvant notamment être unique si sa puissance est suffisante pour la mise en rotation de la partie tournante ;
• en remplaçant le calculateur spécifique par des fonctions correspondantes incorporées dans une unité de traitement remplissant aussi d'autres fonctions de commande et de contrôle de la grue ;
• en remplaçant le variateur de fréquence par tout « actionneur » analogue, conçu pour piloter un ou plusieurs moteurs électriques ;
• en utilisant tous types appropriés de capteurs pour la mesure, directe ou indirecte, des grandeurs intervenant dans le procédé, par exemple pour la détermination du moment de charge.

It would not depart from the scope of the invention, as defined in the appended claims:

• taking into account more or less numerous and various parameters, to allow the temporary increase of the maximum value of the orientation torque;
• by modifying the number of geared motors of the electro-orientation mechanism, the geared motor can in particular be unique if its power is sufficient for rotating the rotating part;
• replacing the specific computer with corresponding functions incorporated in a processing unit which also fulfills other functions of control and control of the crane;
• replacing the frequency converter with any similar "actuator" designed to drive one or more electric motors;
• using all appropriate types of sensors for measuring, directly or indirectly, quantities involved in the process, for example for determining the charging moment.

Claims (5)

Motorized control method of the orientation movement of the rotating upper part (3) of a tower crane, the rotating part (3) being composed of an arrow (7) and a counterfleche (8) and this part rotating member (3) being associated with an electro-orientation mechanism (12) comprising at least one electric geared motor (15) with an electric motor (16) and a gearbox (17), the electric motor (16) of which is electrically powered producing an orientation torque transmitted to the rotating part (3) of the crane, this torque having a maximum value, characterized in that, when the crane is in use and for conditions comprising at least one wind speed (V ) greater than a given value, the maximum value of the steering torque that can be produced by the above-mentioned electric motor (16) is increased as long as these conditions persist. Control method according to Claim 1, characterized in that the maximum value of the steering torque is increased in the event of a wind speed (V) greater than a given value and for at least one additional condition consisting in the fact that the length (Lf) of the boom (7) of the crane is greater than a given value and / or the moment (L x P) of the load (C) suspended under the boom (7) is greater than a given value or at a given fraction of the maximum allowable time. Control method according to claim 1 or 2, characterized in that the steering torque is increased, within the limit of the maximum value then increased, according to the angular position (alpha 1) of the arrow (7), and the wind direction (alpha 2), in particular to increase the motor torque of the geared motor (15) in the phases of "upwelling" by the arrow (7). Control method according to one of Claims 1 to 3, characterized in that it comprises a comparison between the state of an input of an actuator, such as a frequency converter (19), which controls the electric motor ( 16) of the electro-orientation mechanism (12), and the order (S) given by a computer (21) processing information from sensors (26,27,28) to give an authorization to increase the torque, and in the case where the state of this input does not correspond to the order (S) given by the computer (21), an automatic degraded mode of the electro-orientation mechanism (12), for example by reducing its speed. Motorized control device for the steering movement of the upper rotating part (3) of a tower crane, the device comprising an electro-orientation mechanism (12) comprising at least one electric geared motor (15) with an electric motor ( 16) and gearbox (17), the electric motor (16) of which is electrically powered so as to produce an orientation torque transmitted to the rotating part (3) of the crane, this torque having a maximum value, an actuator such as a frequency converter (19) being provided for the control of the motor (16) of the electro-orientation mechanism (12), characterized in that , for the implementation of the method according to one of claims 1 at 4, it comprises a computer (21) provided with inputs (22, 23, 24), which enable it to determine the wind speed (V) and other parameters such as the length (Lf) of the arrow ( 7) of the crane and the moment (L x P) of the load (C) suspended under the arrow (7), and an output (25) which is connected to an input of the actuator such as a frequency converter (19) and which is able to deliver to this actuator, as a function of the parameters treated, an order (S) allowing an increase of the maximum value of the orientation torque.

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