EP1710197B1 - Safety device for crane trolley - Google Patents

Description

The present invention relates generally to the field of tower cranes with a distributing boom, along which is movable a carriage driven by a cable. More particularly, this invention relates to a safety device for the carriage of such a crane, that is to say a device whose function is to automatically immobilize the carriage on the boom of the crane, in case accidental breaking of the cable of displacement of this truck.

In a tower crane, in use, the boom is never perfectly horizontal. On the one hand, even for use in a theoretically horizontal position, the bending of the mast and the boom itself place this boom in a slightly inclined position. In particular, if the raised load is located below the front half of a theoretically horizontal boom, the front portion of the boom tilts down. On the other hand, for some tower cranes, there are possibilities of operation with more or less raised boom, so inclined to the horizontal.

It is understood that in case of accidental breakage of the carriage moving cable, it will immediately, under the effect of its own weight and that of the load possibly raised at this time, describe an accelerated rolling movement along of his running track on the arrow. Such a movement can lead to extremely dangerous situations (collisions, shocks, crane destabilization, drop of the hoisted load, etc.), if it is not immediately braked and stopped. To deal with this problem, systems have already been proposed which, in the event of breakage of the cable for moving the carriage, intervene automatically to brake and / or to stop the carriage. Known achievements of such systems are, among others, described in the patents GB 972436 and FR 1446400 .

Existing systems, such as that of the first aforementioned document GB 972436 , which discloses a crane according to the preamble of claim 1, for the most part use a so-called rocker member. It is a lever mounted to pivot on the carriage about a horizontal axis, and normally held in an inactive position by the carriage moving cable; when the cable breaks, the lever is released and it tilts, by the effect of gravity, so as to engage in the horizontal lattice of the boom of the crane, to stop the truck.

Such a device retains disadvantages. In particular, when the rocker is released and comes into action, there is a significant risk that it bounce first on the horizontal lattice of the boom, this being due to the large number of bars that make up the lattice, and to the length of the rocker. But if the truck does not stop immediately, its movement along the arrow will be accelerated, and the rocker will be less and less effective to stop the truck. If the rocker finally manages to penetrate into the horizontal lattice of the boom, the kinetic energy of the truck (which is an increasing function of the speed of the truck) will twist and break the rocker, which will become ineffective to stop the truck.

The more strongly the carriage accelerates, the less reliable the tipper device is, and as it is understood, this device operates particularly in a very random manner in the case of a raised boom crane.

The patent FR 1446400 , mentioned above, discloses a crane cart safety device which is based on a somewhat different principle. In this device, a lever is pivotally mounted about a horizontal axis on the carriage and it carries brake shoes provided to cooperate with the longitudinal elements of the boom, in case of breakage of the carriage moving cable. Braking of the carriage is thus effected by a frictional contact between parts usually painted steel, so with a low coefficient of friction, hence a braking efficiency itself low. In addition, when the brake lever is released to stop the truck, the lever will bounce off the boom members and oscillate around its pivot axis, further reducing the speed and efficiency of braking. Finally, by its very principle, such a system at best achieves only a more or less strong braking of the carriage by friction against elements of the crane boom, and not a certain stop by abutment contact with an obstacle element in pursuit of moving the carriage.

In conclusion of the foregoing, current systems regardless of their details remain of limited effectiveness and are unreliable.

It is also known, for lifts of materials or people, platform or nacelle rolling on an inclined runway, safety devices of the type "parachute", intervening in case of breakage of the cable. Thus, the patent GB 1015255 discloses a movable finger device, engageable in the teeth of a rack in case of breakage of the cable, the movable finger having a terminal ring through which the cable.

Such a device ensures only a braking and a "mono-directional" stop, that is to say that it intervenes only in the direction of the down the platform or nacelle, while for a crane boom, the truck must be braked and stopped in a "bi-directional" manner, according to the direction of inclination of the boom portion on which the carriage is located. In addition, the addition of a rack is acceptable in the case of a compact hoist, but would be a complex and very expensive solution in the case of a crane boom, whose length can reach 40 to 80 meters .

The present invention aims to eliminate these disadvantages, and it is therefore intended to provide a safety device for a crane truck, which has a very high reliability, and which is particularly effective, this device providing a braking and a stop "bi- directional "and also working very satisfactorily if the boom of the crane is strongly raised, knowing that the more the boom is inclined, the greater the risk in case of rupture of the cable is important.

• un élément mobile d'arrêt en forme de tige guidé en translation sur le chariot dans une direction sensiblement orthogonale à la direction longitudinale de la flèche, et sollicité, par des moyens à ressort, ou des moyens d'actionnement, dans le sens de son engagement dans le treillis de la flèche ; et
• des moyens de détection et de déclenchement, portés par le chariot et aptes à détecter la rupture du câble, ces moyens étant conçus pour retenir normalement l'élément mobile d'arrêt en position reculée par rapport au treillis de la flèche, et pour libérer cet élément mobile d'arrêt et autoriser son engagement dans le treillis de la flèche, sous l'effet des moyens à ressort ou des moyens d'actionnement, en cas de rupture du câble.

To this end, the subject of the invention is a safety device for a tower crane truck with a distributing boom, the device having the function of automatically immobilizing the truck on the boom of the crane, in the event of accidental breakage of the crane cable. displacement of this carriage, this device comprising, mounted on the carriage, a movable stop element released in case of ruputre of the cable and then engage in a lattice of the boom, so as to be stopped by a transverse element of this lattice, the device being characterized in that it comprises, in combination:

• a movable rod-shaped stop element guided in translation on the carriage in a direction substantially orthogonal to the longitudinal direction of the boom, and biased by spring means, or actuating means, in the direction of its direction; engagement in the lattice of the spire; and
• detection and triggering means, carried by the carriage and able to detect the rupture of the cable, these means being designed to normally retain the mobile stop element in the retracted position relative to the lattice of the boom, and to release this movable stop member and allow its engagement in the mesh of the boom, under the effect of the spring means or actuating means, in case of breakage of the cable.

Thus, the invention provides a safety device for a crane truck in which the functions of detecting the breaking of the cable and of stopping the carriage as a result of the breakage of the cable are clearly separated. which allows an optimal realization with a very high reliability. In particular, the safety device works very well even if the boom is raised strongly, the action of the spring means is not influenced by the inclination of the boom, and the design of this device also avoids any unexpected operation if the cable is only relaxed, without being broken. In addition, the solution of the invention remains simple and economical, because it uses the existing mesh of the boom of the crane, regardless of the length of the boom, no additional element such as a rack being necessary.

In one embodiment of the invention, the movable stop member is slidably mounted on the carriage in a direction contained in a longitudinal vertical plane of the boom, and is thus intended to engage in case of breakage. cable, in the horizontal lattice of the arrow.

According to one variant, the movable stop element is slidably mounted on the carriage in a direction transverse to a longitudinal vertical plane of the boom, and is thus designed to engage, in the event of breakage of the cable, in a trellis side of the arrow.

In all cases, the release of the movable stop member, under the effect of biasing means including spring, its commitment certain between the transverse bars or diagonals of the lattice concerned the arrow. If the movable stop element released is then between two consecutive bars, its engagement through the lattice is immediate. If at the moment of its release the movable stop element is opposite a bar of the lattice, the movement of the carriage and the action of the spring means that this movable element will be put in place in the meantime between the bars which is immediately following. Any risk of bouncing of the movable element, and delayed stopping of the carriage, is thus excluded.

The cable rupture detection and triggering means are mechanically feasible, in the form of a rocker lever pivotally mounted on the carriage about an axis orthogonal to the direction of sliding of the movable stop element, the tilting lever having a first arm which cooperates with the cable, and a second arm which, except in the event of breakage of the cable, cooperates with a retaining shoulder formed on the movable stop element, maintaining the spring means in a state under stress. With regard to the spring means, these are advantageously constituted by a helical spring, mounted around the movable stop member formed as a cylindrical rod, and normally kept compressed between the aforementioned shoulder of the mobile stop member and a guide member of the movable stop member.

In a variant, the means for detecting cable rupture and tripping can be made electrically or hydraulically, that is to say in the form of a detection lever similar to that previously mentioned, but acting by means of intermediate of an electrical switch, or its hydraulic equivalent, to release the mobile stop member, and allow its engagement in the structure of the arrow. In this case, the spring means replaceable by actuating means of the movable stopping element, constituted by a pneumatic cylinder or hydraulic or electric.

• Figure 1 est une vue d'ensemble, de côté, d'une grue à tour à flèche relevable, équipée du dispositif de sécurité objet de l'invention ;
• Figure 2 représente, en vue de côté, en tant que détail D de la figure 1, le chariot et une portion de la flèche de la grue, en situation normale ;
• Figure 3 est une vue en perspective du chariot avec son dispositif de sécurité, en situation normale ;
• Figure 4 est une vue de côté similaire à la figure 2, mais en situation de rupture de câble ;
• Figure 5 est une vue en perspective, similaire à la figure 3, du chariot avec son dispositif de sécurité, en situation de rupture de câble.

The invention will be better understood with the aid of the description which follows, with reference to the appended schematic drawing showing, by way of example, one embodiment of this safety device for a crane truck:

• Figure 1 is an overview, from the side, of a luffing tower tower crane, equipped with the safety device object of the invention;
• Figure 2 represents, in side view, as detail D of the figure 1 , the carriage and a portion of the boom of the crane, in normal situation;
• Figure 3 is a perspective view of the truck with its safety device, in normal situation;
• Figure 4 is a side view similar to the figure 2 but in cable rupture situation;
• Figure 5 is a perspective view, similar to the figure 3 , of the carriage with its safety device, in cable breakage situation.

The figure 1 represents a liftable luffing tower crane to which the present invention is applied.

In generally known manner, this crane comprises mainly: a fixed base frame 2, bearing on the ground 3; a rotating frame 4 rotatably mounted on the fixed base frame 2; a folding mast 5, articulated by its lower part on the rotating frame 4; a dispensing arrow 6, which in the example shown is an arrow 6 hinged about a horizontal axis on the top of the mast 5 and thus made liftable; a device 7 for retaining the arrow 6, in the horizontal position or in the desired inclination (the figure 1 representing the arrow 6 in the raised position).

Referring also to figures 2 and following, the arrow 6 which is here triangular section comprises two lower ribs 8, and a single upper chord 9. The two lower chords 8 are connected to each other by transverse bars 10 or "cross", regularly spaced so as to form a "horizontal" lattice (with reference to the arrow itself in horizontal position). Each of the two lower ribs 8 is connected to the upper chord 9 by diagonal slits 11, so as to also form two lateral lattices.

The two lower ribs 8 form a raceway, for an arrow carriage 12 thus made movable along the entire length of the arrow 6. The carriage 12 is moved along the arrow 6 by means of a cable 13 called "cable distribution "motorized by means of a winch here not detailed, the distribution cable 13 decomposing into a front distribution cable 13a and a rear distribution cable 13b. The crane further comprises a hoisting rope 14, which forms at least two vertical strands under the carriage 12, and on which is suspended a lifting block 15, provided with a hook 16 to which a load (not shown) to be raised can be suspended. .

The boom carriage 12 is equipped with a safety device, generally designated by the reference 17, which serves to automatically immobilize the carriage 12 in case of accidental breakage of the distribution cable 13. The safety device 17, and its operation, are illustrated in particular by the Figures 2 to 5 , which is now referred to.

The safety device 17 is here carried by the rear portion of the frame 18 of the carriage 12, that is to say its nearest part of the top of the mast 5 of the crane. This safety device 17 mainly consists of a movable stop element 19 and a rocker lever 20.

The movable stop member 19 is in the form of a cylindrical rod, slidably mounted along an axis A whose direction is contained in a longitudinal vertical plane of the arrow 6, and oriented perpendicularly to the direction of movement of the carriage 12, in other words to the longitudinal direction of the arrow 6. The movable stop member 19 is slidably mounted in a guide block 21 integral with the frame 18 of the carriage 12, and it also slidably traverses a guide tab 22 fixed under the frame 18 of the carriage 12.

On the movable stop member 19 is formed an annular shoulder 23, which takes place between the guide block 21 and the guide lug 22. A coil spring 24 is mounted around the movable stop member 19, the spring 24 being placed and compressed between the annular shoulder 23 and the guide lug 22.

The rear portion of the frame 18 of the carriage 12 carries, close to the movable stop member 19, a short axis 25 orthogonal to the sliding direction A of this movable stop element 19, the axis 25 being more particularly oriented in the direction of travel of the carriage 12. The rocking lever 20 is pivotally mounted by an intermediate sleeve 26 on the axis 25. This rocker lever 20 has a first arm 27 which, starting from the hinge sleeve 26, forms several successive bends and passes on the distribution cable 13, more particularly on the rear distribution cable 13b. The rocking lever 20 also has a second arm 28, opposite to the previous one and of shorter length, which is provided to cooperate with the annular shoulder 23 of the movable stop element 19.

The figures 2 and 3 represent the components previously described in their normal position, that is to say the position they occupy as long as the distribution cable 13, in particular here the rear distribution cable 13b, is intact and normally stretched, thus allowing the motorized control of the displacement of the carriage 12 on its raceway. The rocker lever 20 is then held in its position by the support of its first arm 27 on the cable 13, more particularly the rear distribution cable 13b, which is tensioned. The corresponding position of the second arm 28 of the rocking lever 20, which bears against the annular shoulder 23 of the movable stop element 19, is such that this movable stop element 19 is kept lowered, while the spring 24 is compressed. Given the lowered position of the movable stop member 19, and as shown in particular by the figure 2 the upper end 19a of this element 19 remains below the plane containing the crosspieces 10 of the "horizontal" lattice of the arrow 6. The carriage 12 can thus move freely along the arrow 6, forwards or the rear according to the arrow F, rolling by its rollers 29 on the raceway formed by the two lower ribs 8, connected by the cross members 10.

In case of accidental breakage of the distribution cable 13, as illustrated by the figures 4 and 5 , the rocker lever 20 no longer bears by its first arm 27 on the cable, and the lever 20 thus released pivots in the direction of the arrow F1, so that its second arm 28 deviates from the annular shoulder 23 and releases itself the mobile stop element 19. Under the effect of the expansion of the spring 24, the movable stop member 19 is displaced upwardly along the axis A, so that its upper part protrudes further from the guide block 22 and introduced through the "horizontal" lattice of the arrow 6, in the gap between two crosspieces 10 of this lattice. Thus, during the start of recoil of the carriage 12, along the arrow F2, the movable stop member 19 will quickly abut against the first crosspiece 10 encountered, which will prevent further rolling of the carriage 12 .

If by chance, the upper end 19a of the movable stop member 19, biased by the spring 24, is opposite a cross member 10 at the moment of its release, the momentary continuation of the movement of the carriage 12 and the action of the spring 24 causes the movable stop member 19 to be put in place in the immediately following interval between this cross member 10 and the next cross member 10, and will abut against this next cross member 10.

Thus, in all cases, the carriage 12 will be quickly stopped, by the meeting of an obstacle belonging to the structure of the arrow 6. It is also noted that, under the effect of the spring 24, the movable element of stop 19 will remain maintained in the up position until the first intervention, so that no further retreat of the carriage 12 is possible. Finally, as is easily understood, the described operation is not disturbed by the inclination of the arrow 6.

Claims (8)

1. Tower crane with slewing jib or lattice, with a safety device (17) fitted to a trolley (12) and having the function of automatically immobilizing the trolley (12) on the crane jib (6) in the event of accidental breakage of the travel cable (13) of this trolley (12), the device (17) comprising, mounted on the trolley (12), a mobile arresting element (19) which is released if the cable (13) breaks and then engages in a lattice of the jib (6), in such a way as to be arrested by a transverse element (10; 11) of this lattice, said crane being characterized in that the safety device (17) comprises, in combination:

   • a mobile arresting element (19) in the form of a rod guided translationally on the trolley (12) in a direction (A) approximately orthogonal to the longitudinal direction of the jib (6), and urged by spring means (24) or by actuating means in the direction of its engagement in the lattice of the jib (6); and

   • detection and trigger means (20), carried by the trolley (12) and able to detect breakage of the cable (13), these means (20) being designed to retain the mobile arresting element (19) normally in the retracted position relative to the lattice of the jib (6), and to release this mobile arresting element (19) and allow it to engage in the lattice (10; 11) of the jib (6) under the action of the spring means (24) or actuating means, in the event of breakage of the cable (13).
2. Tower crane according to Claim 1, characterized in that the mobile arresting element (19) is mounted such that it can slide on the trolley (12) in a direction (A) contained in a vertical longitudinal plane of the jib (6), the mobile arresting element (19) thus being designed to engage, in the event of breakage of the cable (13), in the horizontal lattice (10) of the jib (6).
3. Tower crane according to Claim 1, characterized in that the mobile arresting element (19) is mounted in such a way as to slide on the trolley (12) transversely with respect to a vertical longitudinal plane of the jib (6), the mobile arresting element (19) thus being designed to engage, in the event of breakage of the cable (13), in a lateral lattice (11) of the jib (6).
4. Tower crane according to any one of Claims 1 to 3, characterized in that the cable breakage detection and trigger means are realized mechanically, in the form of a rocker lever (20) mounted so as to pivot on the carriage (12) about an axis (25) orthogonal to the direction of sliding (A) of the mobile arresting element (19), the rocker lever (20) possessing a first arm (27) that engages with the cable (13), and a second arm (28) which, except in the event of breakage of the cable (13), engages with a retaining shoulder (23) formed on the mobile arresting element (19) and so keeps the spring means (24) in the stressed condition.
5. Tower crane according to Claim 4, characterized in that the safety device (17) comprises spring means consisting of a helical spring (24) mounted around the mobile arresting element (19) which is constructed as a cylindrical rod, and normally kept compressed between the aforementioned shoulder (23) of the mobile arresting element (19) and a guide member (22) which guides this mobile arresting element (19).
6. Tower crane according to any one of Claims 1 to 3, characterized in that the cable breakage detection and trigger means are realized electrically or hydraulically, with a detection lever acting via an electric switch, or via its hydraulic equivalent.
7. Tower crane according to Claim 6, characterized in that it comprises actuating means for the mobile arresting element (19), consisting of a pneumatic or hydraulic or electric actuator.
8. Tower crane according to any one of Claims 1 to 7, characterized in that this crane is a tower crane with a luffing and slewing jib (6).

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