EP0252841B1 - Automatic control device of the retardation of the rotation of a boom and/or counter-boom of hoisting machines - Google Patents

Description

The present invention relates to a method and a device for controlling slowdown and automatic stopping of the rotation of jibs and / or counter-jibs of lifting devices.

The current recommendations, defined by the safety organizations, impose to slow down and then automatically stop the lifting devices when they are exposed to a risk of collision between them, interactive system, or with a fixed obstacle, for example a building, or quite simply when their load will reach, during its displacement, an area whose overflight by the load is prohibited, for example a schoolyard or any other public place.

This is the case of cranes that are encountered on building sites and public works. The different zones are determined in situ.

• - une surface comprise entre le cercle décrit par le point d'extension maximal du chariot porte-charge Emax, et le cercle décrit par le chariot lorsqu'il va tangenter l'espace interdit pendant la rotation et,
• - l'angle a compris entre les points où le cercle d'Emax coupe le bord de l'espace interdit.

In the case of an obstacle A (fig. 1) materialized for example by a building or by a space prohibited from overflight for the load by a regulation, the prohibited zone ZI for the load will be schematically defined by:

• - an area between the circle described by the maximum extension point of the Emax load-carrying trolley, and the circle described by the trolley when it is tangent to the prohibited space during rotation, and
• - the angle included between the points where the Emax circle intersects the edge of the prohibited space.

In order to stop the movement of the arrow at the latest when entering this zone, a slowdown zone is also defined in the vicinity thereof. This slowdown zone ZR will be defined by an angle of rotation a + 2Γ, being an angle of rotation situated on either side of the angle a, and by the circle described by the carriage at a certain distance, determined by the type of crane, less than where it will pitch the prohibited area.

In the case of an interactive system, i.e. the case where the loads of two cranes can fly over the same area, (Fig. 2), we define, in order to avoid a collision, a dangerous area ZD determined as above for the "high" crane, that is to say, the one whose boom travels in a higher plane, and, for the low crane, only by the angle aE of rotation of its boom or its counter-arrows between the ends of the ZD area. ZR slowdown zones _! and ZR _@ are determined identically. However, in this case, the ZD zone is only prohibited when loading the high crane when the boom or jib of the low crane is already there and when the boom or jib of the low crane is loaded. the high crane is already there. On the other hand, the movement must be slowed down anyway when the load of the high crane or the jib or the jib of the low crane enters the ZR zones! or ZR _@ respectively, the stop being ordered for one of the cranes only when the other crane is already interfering with the ZD area.

• - un capteur de position angulaire dont on a initialement positionné le "0" sur le site et qui mesure l'angle d'orientation de (rotation) de la flèche;
• - un capteur de mesure de distance du chariot distributeur (porte-charge) sur la flèche à partir du fût ou d'un point déterminé par le constructeur ;
• - un capteur de hauteur de charge indiquant la distance de la charge à la flèche ou à un point déterminé par le constructeur, en mesurant la longueur du câble déroulé.

The cranes that are currently encountered on construction sites are provided with an integrated retarder system operating for example by eddy currents. The slowing down and possible stopping of the boom rotation, distribution and lifting are then controlled by an electronic zone determination system comprising:

• - an angular position sensor which was initially positioned "0" on the site and which measures the orientation angle of (rotation) of the boom;
• - a sensor for measuring the distance from the distributor carriage (load carrier) on the boom from the barrel or from a point determined by the manufacturer;
• - a load height sensor indicating the distance of the load to the boom or to a point determined by the manufacturer, by measuring the length of the unwound cable.

The information obtained by these sensors is sent to the zone determination device which processes them, preferably in analog, to trigger the operations imposed by the different zones (prohibited, dangerous, slowing down).

The zone determination device automatically controls the crane slowdown system when all of the parameters it has received from the sensors and which it has processed indicate that it has crossed the braking zone limit and the obligation to slow down the movements and possibly stop them. This is the subject of patent FR-A-2,517,659. The zone determination device then sends a signal acting on the voltage of the retarder and possibly on that of the stop systems.

But there exists on the market a type of apparatus on which the slowing down and the stopping of the orientation are left to the initiative of the operator. These cranes have either two motors for orientation in each of the two directions, or a single motor whose direction of rotation is reversed for this purpose.

In the case of a tower crane, for example, when the boom slewing motors turn in one direction, the speed increases. The driver has a control lever allowing him to accelerate the movement (in general 1 to 5 speed ratios). If he has to brake this orientation movement, he must for that reason proceed to the counter-orientation, that is to say that he reverses by himself the direction of orientation of his machine either by switching off the engine active and putting into service the one that turns in the opposite direction, either by reversing the current in the single motor. The dosage of this feedback is left to the initiative of the driver who must anticipate in order to obtain the cut-off at the latest at the zone limit.

In order to comply with the recommendations in force, it is necessary to proceed with an automatic slowing down of the orientation, of the distribution (movement of the carriage) and possibly of the lifting and at the same time cancel the operation that the operator of the machine could execute Security. The zone determination system known from patent FR-A-2 517 659 is unsuitable for the aforementioned machines because they do not have an integrated independent braking system which can be automatically controlled. On the other hand, there are no devices on the market to solve this problem.

The object of the invention is to allow the ra slowdown and automatic stopping of vehicles when safety requires by adapting the known zone determination system to vehicles not equipped with an auxiliary brake reacting to its control signal.

This object is achieved according to the invention in that the crane drive motor (s) are directly controlled by adding to the parameters used in the control system, angular indications and distance indications, an additional parameter which is the arrow orientation speed.

The acquisition of the speed value can be obtained by a tachometer, a DC servo motor or any other means.

The measurement carried out is therefore a function of the orientation speed of the machine (the boom of a crane for example) and makes it possible first of all to define the direction of rotation. The braking of the rotation is then done by pulses controlling the motor in counter-orientation.

• Figure 1 : un schéma représentant les zones interdites et de ralentissement dans le cas d'un obstacle ou d'un lieu interdit de survol ;
• Figure 2 : un schéma représentant les zones dangereuses et de ralentissement dans le cas d'un système interactif ;
• Figure 3 : la forme du signal de mesure linéaire, dans l'exemple, en fonction de la vitesse mesurée ;
• Figure 4 : le signal de commande sous la forme d'un train d'impulsions ;
• Figure 5 : un schéma d'une première forme de réalisation du dispositif selon l'invention,
• Figure 6 : un schéma d'une seconde forme de réalisation du dispositif selon l'invention.
• Les figures 7 et 8 illustrent schématiquement une troisième forme de réalisation de l'invention.

The invention will be better understood by means of the description below of an exemplary embodiment with reference to the appended drawing in which we see:

• Figure 1: a diagram representing the prohibited and slowdown zones in the case of an obstacle or a prohibited place of overflight;
• Figure 2: a diagram representing the danger and slowdown zones in the case of an interactive system;
• Figure 3: the shape of the linear measurement signal, in the example, as a function of the measured speed;
• Figure 4: the control signal in the form of a pulse train;
• FIG. 5: a diagram of a first embodiment of the device according to the invention,
• Figure 6: a diagram of a second embodiment of the device according to the invention.
• Figures 7 and 8 schematically illustrate a third embodiment of the invention.

The speed measurement makes it possible to determine in which direction the machine is oriented, either to the right or to the left.

Figure 3 shows the measurement signal as a function of the slewing speed of the boom of a crane. By convention, the positive (increasing) signal corresponds to a rotation to the right and the negative (decreasing) signal corresponds to a rotation to the left. The tension increases or decreases depending on the orientation speed.

In FIG. 3, the values Vo, Vi, V ₂ ... V _x correspond to the speeds from which the driver changes to the higher gear to accelerate the movement, that is to say, first gear from V ₀ to V ₁ , second ratio from V ₁ to V ₂ , etc.

When the zone determination system indicates to it the crossing of the limit of a slowdown zone, the device according to the invention, which receives the measurement signal of the arrow's orientation speed, emits an output signal formed by a train of pulses towards the drive motor or motors, making it possible to carry out the counter-orientation, and to obtain braking and possibly stopping. The width Ti of each pulse will determine a braking activation time and the period T2 the time after which the braking is activated again. The whole train of pulses thus formed corresponding to the total braking time.

Indeed, it is not safe to suddenly stop the rotation when the speed is greater than a certain value. The amplitude of the pulses is constant and braking is done by short strokes of duration Ti.

Between the values V ₀ and V ₁ , a speed V _R is defined above which it will be necessary to slow down.

Between the values V ₀ and V _R (fig. 3), the speed is low and the boom can be stopped. From V _R we will have to proceed with the counter-orientation, therefore a gradual slowing down. possibly up to a stop.

According to the invention, the pulse duration Ti and the repetition period T ₂ will be modulated as a function of the orientation speed.

Between V ₀ and V _R , Ti = 0 and T ₂ is theoretically infinite.

From V _R to V ₂ , Ti and T ₂ will have a certain value.

From V ₂ to V ₃ , T ₁ will increase and T ₂ decrease, and so on until Vx. When the speed of rotation falls to V _R , and below this value, the arrow will be stopped (prohibited zone) or turn in idle (dangerous zone).

The higher the orientation speed, the longer the time T _i and the shorter the time T ₂ . As soon as the speed decreases as a result of braking, the time Ti is reduced and T ₂ increases. This is repeated in stages until V _R is reached. At this time, the speed is reduced to a value such that the low speed is maintained or that the machine is stopped automatically, under conditions conforming to the manufacturer's data.

The device intended for implementing the method according to the invention is shown in FIG. 5, in the case of a crane with 5 speed ratios.

In FIG. 5, M is the member for measuring the orientation speed of the crane jib, RL and RL 'are output members (relays) making it possible to act directly on the machine, for a counter-orientation to the left (RL), and a counter-orientation to the right (RL '). The components Bi to Bs are monostable flip-flops enabling the times Ti and T ₂ to be defined. Each scale has its own train of pulses corresponding to the speed interval to which it is assigned. (Bi from V _R to V ₂ , B ₂ from V ₂ to V ₃ ... etc.). The elements Ci to C ₅ are comparators making it possible to define the thresholds, initialized at the start, from which the process must be triggered.

The speed measuring device M permanently sends a signal V, a function of speed, to the comparators Ci to Cs. As long as the limit of a slowdown zone is not reached, the zone determination device sends a signal I to the comparators C ₁ to C ₅ which blocks their output; no signal is then transmitted to the flip-flops Bi to B ₅ which are not activated.

As soon as the zone determination device detects the crossing of the limit of a slowdown zone, the signal I is no longer transmitted to the comparators which become operational.

Depending on the value of the signal V sent to the comparators by the speed measuring device M, the comparator corresponding to this value emits a signal Z, or Z ', depending on the sign of V, which is sent to one of the two flip-flops Bn or B 'n, (n = 1 to 5) corresponding to the comparators, that is to say the flip-flop Bn when V is positive (orientation to the right) to obtain a counter-orientation to the left or to the flip-flop B ' _n when V is negative (orientation to the left) to obtain a counter-orientation to the right. The rocker thus activated will emit on the one hand a signal inhibiting the rockers corresponding to lower values of V, and on the other hand the train of pulses corresponding to the speed interval which is assigned to it, it is that is to say with determined times T ₁ and T ₂ . This train of pulses will act through the relay RL or RL 'on the supply of the engine or engines of the machine.

The device works as follows:

When the boom of the crane approaches a prohibited area, by turning to the right for example, it rotates at a speed greater than Vs. As soon as it crosses the threshold of the slowdown zone ZR, the zone determination system signals this crossing and no longer sends the signal I to the braking control device according to the invention. The latter receiving the speed indication signal V from the measuring member M, its comparator C ₅ (corresponding to a speed greater than or equal to V ₅ ), thus activated, in turn activates the rocker B _s by a signal Z and inhibits flip-flops B ₁ to B ₄ by a signal l '. The flip-flop Bs sends a pulse train of width T ₁ and of period T ₂ to the relay RL which will command a counter-orientation to the left. The speed of rotation of the arrow progressively falling below Vs will therefore be between V ₄ and v ₅ , it is the comparator corresponding to V ₄ which takes over, activates the flip-flop B ₄ which inhibits by a signal the flip-flops B ₁ to Bs. The time T ₁ takes a lower value and T ₂ a larger value. It is the same when the speed drops below V ₃ then V ₂ and V _R. Arrived below this last value, in the example described, the crane can be stopped immediately without danger or remain at low speed. The embodiment of the device according to the invention shown in FIG. 6 comprises only a single comparator controlled by the member for measuring the orientation speed M and by the device for determining zones.

In this exemplary embodiment, the comparator C, as soon as the signal I is interrupted, activates one or the other of the flip-flops B and B ′, whose pulse train is no longer determined but varies as a function of the value of the signal V transmitted by the measuring member M. As in the previous example, the times Ti and T ₂ will vary according to the value of V but instead of varying in stages, they will vary gradually so that 'at any instantaneous speed V corresponds a value T ₁ and a value T ₂ .

The embodiment schematically illustrated in FIGS. 7 and 8 takes up the operating principle of the previous example as shown in FIG. 6. However, in this case, the flip-flops B and B 'no longer deliver trains of pulses whose values of Ti and T ₂ are determined as a function of the orientation speed but a single pulse which only disappears when the speed is equal to 0. T ₂ is then always zero.

As can be seen in FIG. 7, the entrance to a prohibited zone ZI is located at an angle a _i of the predetermined origin O. An angle α _{∅ is} then determined slightly less than the angle α ₁ (for example 50) from which the orientation movement must be slowed down to a stop, this must imperatively occur at the latest when the angle ai is reached. We also determine an angle β∅ corresponding to the entry into the deceleration zone from which we will have to slow down the orientation until the stop between α∅ and α ₁ . A speed Vi is then defined below which the deceleration will be automatic if at the entrance to the deceleration zone the orientation speed V of the arrow is greater than Vi. Preferably, Vi has a value of about 30% of the nominal orientation speed.

The device works as follows:

When the boom approaches the slowdown zone which begins in β∅, the crane operator actuates the manipulator to carry out the counter-orientation. The arrow then enters the deceleration zone with a speed V.

If this speed V is less than the speed Vi, the zone determination device continues to send the signal 1 to the comparator C which also receives the signal V corresponding to the orientation speed. The scales B and B 'are always inhibited and the crane operator continues to carry out the counter-orientation until the crane comes to a complete stop before reaching the angle α∅. However, it can only use the ratios corresponding to the speeds between V _∅ and V ₄ mentioned above for this.

The zone determination device also limits the speed ratios of the carriage to the ratio 1 by preventing the use of the ratios 2 and 3.

If, when the angle α∅ is reached with still a speed V not zero, the counter-orientation is immediately triggered and the device for determining the zones causes the orientation to stop immediately by applying the brakes which immobilize the boom before the angle α ₁ is reached.

In the case where the orientation speed V is greater than V ₁ when the arrow enters the deceleration zone, that is to say when the orientation angle θ of the arrow is equal to β _∅ , the system proceeds to automatic counter-orientation. The zone determination device no longer sends a signal 1 to comparator C which immediately transmits a signal Z or Z 'to flip-flop B or B' according to the sign of signal V. The counter-orientation is triggered by the relay RL or RL 'until the boom stops completely, for example with an angle e = β ₁ . If the manipulator is still engaged in the direction of the danger when V reaches the value 0, the crane operator will not can no longer restart the orientation to the ZI zone. When it has brought the manipulator back to neutral, it can restart the orientation because the zone selection device again sends the signal I to the comparator C which no longer transmits the signal Z to the scale, and the counter-orientation is cut . However, it can no longer use the ratios corresponding to the speeds Vs to Vs in the direction of the danger (or V ₄ to V _s depending on the type of machine). It can no longer operate the carriage except at speed 1. On the other hand, it can use these ratios to accentuate the counter-orientation in order to obtain an angle e less than or equal to β ₁ when stationary. After restarting, if the speed V remains below V ₁ , the crane operator will be able to continue the orientation until e = α∅. If on the other hand V approaches V _i , an alarm signal is triggered for a speed V = V _AL slightly less than V _{1 in} order to warn the crane operator that he will exceed the speed limit. If despite this it allows the speed to increase, the system triggers, as soon as Vi is reached, the counter-orientation process until it stops. The stopping can occur for example in V ₂ according to FIG. 8. The restarting is carried out as previously until e reaches the value α∅. If the speed V is not zero for this value of e, the counter-orientation is triggered up to a zero speed. The brakes automatically drop to lock the boom if the speed is zero without the counter-orientation being engaged.

For the limiting case where the speed at the entry of the deceleration zone would be maximum, the angle β∅ is determined so that the counter-orientation allows the complete stop at a point β1 then located between α∅ and α ₁ .

In all cases the orientation in the opposite direction of the arrow can be carried out at high speed, (up to V5) and, when the stop has occurred between α∅ and ai, the brakes are then automatically disengaged service.

The same operating process can be applied to the embodiment of the device according to FIG. 5. In this case, the flip-flops B ₁ to B ₅ and B ' ₁ to B' ₅ emit a single pulse.

But then, the pulses of each rocker are stopped for the values of speeds which cause, by the comparators Ci to C ₅ , the change of rocker. The pulse of the flip-flop B ₁ (or B'i) being of course stopped when V = 0. The time interval between the deactivation of a flip-flop and the deactivation of the next flip-flop is quite small for that one can consider that one is in the presence of a single impulse between the moment when B _s (for example) is activated and that when Bi is deactivate.

We can consider other forms of operation of the device according to the invention. For example, instead of initially setting a deceleration zone, it is possible to design a device in which the length of the deceleration zone will depend on the speed. Thus, the angular distance to the prohibited zone limit, could be integrated with the speed of rotation thereof to determine the moment when the deceleration is commanded.

Claims (11)

1. A method for automatically slowing down and stopping the slewing, change of reach and, optionally, the hoisting action, of machinery used on building sites, such as cranes, not provided with auxiliary slowing mechanisms, the method including measurement of the angle of orientation, of the length of travel of the truck, and, optionally, of the height of the hoist, and also including comparison of the measured values with predetermined values which depend on the limits of forbidden zones over which the load must not be carried, or dangerous zones, this measurement and comparison serving to determine the moment at which the movement of the machinery must be slowed down before being stopped altogether, should this prove necessary, characterised in that the angular speed (V) of slewing of the machinery is measured and that the value of this measurement is used in order to determine the force of the braking action, brought about by counter-slewing, a signal controlling the slowing down being sent to a relay acting upon the motor or motors of the machinery, either to bring it to a stop before it reaches the limit of the forbidden zone over which the load or the jib must not be carried, or to impose a speed reduction when crossing a dangerous zone.

2. A method for automatic slowing down and stopping in accordance with Claim 1, characterised in that the signal which controls the slowing down, as sent to the relay. that controls the power supply to the motor or motors of the machinery, consists of a train of pulses of variable length (T!) and frequency (T_@).

3. Method in accordance with Claim 2, characterised in that a given pulse length (T) of the pulses governing the braking action and a given frequency (T_@) of the train of pulses correspond to a given step in the speed of slewing of the jib.

4. Method in accordance with Claim 2, characterised in that a fixed pulse width of the pulses governing the braking action and a fixed frequency of the train of pulses correspond to a given speed of the jib.

5. Method in accordance with Claim 1, characterised in that the signal controlling the slowing down, as sent to the relay controlling the power supply to the motor or motors of the machinery, consists of a pulse whose duration is determined by the instant at which the angle of orientation and the speed of slewing simultaneously reach a value prescribed for each, and by that at which the speed is zero.

6. Apparatus for automatically slowing down and stopping the rotation of the jib and/or counter-jib of hoisting machines such as cranes and also for slowing down and stopping the change of reach and, optionally, for determining the height to which the load can be hoisted, under the control of means for demarcating zones, characterised in that it comprises an instrument (M) which detects the speed of slewing of the jib, and at least one comparator (C), activated by the means for demarcating zones, which compares the speed value (V) transmitted by the speed-detecting instrument (M) with a predetermined value so as to emit a control signal (Z,Z') to at least one monostable device (B or B') which in turn emits at least one pulse whose duration is a function of the measured speed (V) and which acts upon a relay device (RL,RL') so as to intervene in the power supply to the motor or motors of the crane in the sense to achieve a counter-slewing effect.

7. Apparatus in accordance with Claim 6, characterised in that the monostable device or devices (B,B', B1 to B5, B'1 to B'5) emit a train of pulses whose width and frequency are a function of the measured speed (V).

8. Apparatus in accordance with Claim 7, characterised in that it comprises several comparators (C1-5) which correspond to fixed intervals of speed, each comparator (Cl-5) controlling a monostable (Bl-5, B'1-5) for each direction of rotation, the monostable thus controlled emitting in addition a signal (I') for inhibiting the monostables (B4-1, B'4-1) that correspond to slower speeds of rotation.

9. Apparatus in accordance with Claim 6, characterised in that the monostables (Bl to B5, B'1 to B'5) emit in sequence a pulse whose duration is determined, for the first monostable that is triggered, by the instant at which the angle and the speed of slewing reach a value prescribed for each of them and by that at which the next monostable in the sequence takes over; for the last monostable that is triggered, the duration of the pulse is determined by the moment at which the device starts to operate and by that at which the speed is nulled, and, for the intervening monostables, by their operating times corresponding to the designed intervals of speed of operation.

10. Apparatus according to Claim 6, characterised in that it comprises a single comparator (c) which controls a monostable device (B,B') for each direction of rotation of the jib, the activated monostable (B or B') emitting a train of pulses which is determined by a prescribed value (V) of the signal that it receives from the speed-detecting instrument.

11. Apparatus according to Claim 9, characterised in that the monostables (B,B') emit a pulse whose duration is determined by the instant at which the angle and the speed of slewing simultaneously reach a value prescribed for each, and by that at which the speed is zero.

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