FR3049593A1 - FOLDABLE STRUCTURE FOR COMPOSING A TOWER CRANE - Google Patents

Abstract

This foldable structure (1) comprises: two structural elements (2.1, 2.2), a hinge member (4) for making the structural elements (2.1, 2.2) movable between unfolded and folded configurations. The collapsible structure (1) further comprises a first (10) and a second (12) cable guiding member (10) for guiding a first (6.1) and a second (6.2) portion of a traction cable (6). ). The pulling cable (6) has an intermediate portion (6.3) between the first (10) and second (12) cable guide members (10). The second cable guide member (12) is movable relative to the first cable guide member (10) between elongation and shortening positions. The intermediate portion (6.3) is longer in the extension position than in the shortening position. A return member (14) recalls the first cable guide member (10) in an extended position.

Description

The present invention relates to a foldable structure for composing a tower crane. Furthermore, the present invention relates to a tower crane whose mast comprises such a foldable structure.

In the state of the art, for example FR2252279A1, some tower cranes have a foldable structure. The collapsible structure comprises structural members, a traction cable, and a hinge member, which is connected to the structural members so that the structural members are movable between an unfolded configuration and a collapsed configuration.

Between the unfolded configuration and the folded configuration, the length of the traction cable, measured between two reference points on the foldable structure, undergoes a relatively large variation, which may be of the order of a few tens of centimeters. Indeed, the traction cable has a longer length in folded configuration than unfolded configuration.

However, if the traction cable is stretched when the structural elements are in the unfolded configuration, then the passage in folded configuration will induce an overvoltage in the traction cable, and this overvoltage may damage the traction cable or other components, as the pulleys guiding the traction cable and / or the supports of these pulleys. In addition, residual forces in the pulling cable impose increasing power to unfold or fold the foldable structure.

Conversely, if the traction cable is not stretched enough when the structural elements are in unfolded configuration, the winding of the traction cable on its drum can be altered, which can increase the risk of attachment between the traction cable. and another component of the structure, and further reduce the service life of the traction cable.

Moreover, in the case where the tower crane includes a telescopic mast portion, the pulling cable withstands great efforts during telescoping, then retractable locks take up these great efforts after telescoping. However, when the telescoping movement is stopped too early, the towing cable may be too tight, which can be dangerous during the working phases of the tower crane, for example when lifting a load. Conversely, when the telescoping movement is stopped too late, the pulling cable may be unrolled too much and may roll up on its drum.

The present invention is intended in particular to solve, in whole or in part, the problems mentioned above.

For this purpose, the subject of the present invention is a foldable structure, for composing a tower crane, the foldable structure comprising at least: two structural elements configured to compose a part of the structure of the tower crane, an articulation member mechanically connected to the structural elements so that the structural elements are movable between an unfolded configuration and a folded configuration, a traction cable configured to exert a tensile force on components of the tower crane, the foldable structure being characterized in that it further comprises at least: a first cable guide member configured to guide a first portion of the pull cable, a second cable guide member configured to guide a second portion of the pull cable, the pull cable having a intermediate portion extending between the first cable guide member and the second guide member the second cable guiding member being movable relative to the first cable guiding member between an elongation position and a shortening position, so that the intermediate portion is longer when the second guiding member is cable is in the extended position only when the second cable guide member is in the position of shortening; and a return member configured to exert a return force of the first cable guide member to the extension position.

The second cable guide member is generally further away from the first guide member in the extended position than in the shortened position.

In unfolded configuration, the relatively high tension exerted on the traction cable moves the second cable guiding member into a shortened position, while in the folded configuration the relatively low tension exerted on the traction cable allows the return member placing the second cable guide member in an extended position.

Thus, such a foldable structure makes it possible to compensate for or absorb the variation of the length of the traction cable during the passage from the unfolded configuration to the folded configuration.

Moreover, such a foldable structure makes it possible to guarantee that, during the transition from the unfolded configuration to the folded configuration, the traction cable relaxes sufficiently to minimize its wear, but not excessively, so as not to risk a problem of winding on. the drum.

In the present application, the term "traction cable" designates a structural and flexible element configured to transmit at least one traction force. A towing cable is sometimes referred to as a "rope". The pulling cable may for example be a cable for lifting the suspended load, or a cable for distributing the load along the boom of the tower crane, or a cable for telescoping the mast of the crane. tower crane to slide a mast section out of another mast section.

According to one variant, the structural elements are sections of the mast of the tower crane. Alternatively to this variant, the structural elements are sections of the boom of the tower crane.

In unfolded configuration, the sections of the mast or the sections of the boom are substantially aligned, so that they extend in the extension of one another and substantially co-linear with the longitudinal direction of the mast or the mast. arrow.

In folded configuration, two sections of the mast or the arrow form between them an angle less than 90 degrees, for example equal to 45 degrees. In a completely folded position, the structural elements can be juxtaposed or superimposed. In the fully folded position, the structural elements can be arranged substantially parallel to each other.

According to one variant, the structural elements extend substantially along disjoint planes.

Alternatively, the hinge member comprises a nasion pivot arranged to rotate the structural elements relative to each other.

Alternatively, the first cable guide member and the second cable guide member are arranged such that the side of the first cable guide member guiding the pull wire is opposite the side of the second guide wire guide member. the traction cable.

In other words, the traction cable has a first portion that is in contact with a portion of the first cable guide member and a second portion that contacts a portion of the second cable guide member, and the first portion portion is opposed to the second portion.

According to one variant, the traction cable extends along each structural element when the structural elements are in unfolded configuration. For example, when the structural elements are sections of a mast of a tower crane in service configuration, the pulling cable extends in a slightly inclined direction (eg 0 to 20 °) with respect to a vertical direction ; and when the structural elements are sections of an arrow in the service configuration, the pulling cable extends substantially parallel to the boom, which can extend at an angle of deflection of between 0 and 90 degrees with respect to a boom. horizontal direction.

According to a variant, at least one of the structural elements is composed of an outer portion and an inner portion, the outer portion having a larger cross-section than the inner portion, the inner portion being configured to slide in the outer portion according to a telescoping direction.

According to one embodiment, at least one structural element has generally an elongate shape.

According to one variant, each structural element generally has an elongated shape.

According to one embodiment, the first cable guide member and the second cable guide member are connected to a common structural member.

In other words, the first cable guide member and the second cable guide member are connected to the same structural member selected from said two structural members. Therefore this same structural element is common to the first cable guide member and the second cable guide member.

According to one embodiment, the first cable guide member is fixedly connected to said common structural member, and wherein the second cable guide member is movably connected to said common structural member.

According to one embodiment, the foldable structure further comprises a third cable guide member arranged so that, in the shortening position, the second cable guide member is closer to the first cable guide member than the third member cable guide.

According to a variant, the first cable guiding member comprises an element configured to guide a traction cable in displacement without excessive wear of the traction cable. According to one variant, the second cable guiding member comprises an element configured to guide a traction cable in displacement without excessive wear of the traction cable. According to a variant, the third cable guiding member comprises an element configured to guide a traction cable in displacement without excessive wear of the traction cable.

According to a variant, the first cable guiding member has a guide groove adapted to receive a portion of the traction cable. According to a variant, the second cable guiding member has a guide groove adapted to receive a portion of the traction cable. According to a variant, the third cable guiding member has a guide groove adapted to receive a portion of the traction cable.

According to a variant, the first cable guiding member is configured to fulfill a function of angle of return, so that the strands of the traction cable located on either side of the first cable guiding member form an angle between them. According to a variant, the second cable guiding member is configured to fulfill a function of angle deflection, so that the strands of the traction cable located on either side of the second cable guiding member form an angle between them. According to a variant, the third cable guiding member is configured to fulfill a function of angle of return, so that the strands of the traction cable located on either side of the third cable guiding member form an angle between them.

According to a variant, the foldable structure further comprises at least a fourth cable guiding member, the fourth cable guiding member being movable relative to the first cable guiding member between an elongation position and a shortening position.

According to one embodiment, the first cable guide member, the second cable guide member and the third wire guide member are substantially aligned when the second cable guide member is in the shortened position.

According to one embodiment, the second cable guide member is movable at least pivotally about a pivot axis remote from the second cable guide member.

According to a variant, the foldable structure further comprises a lever which is integral with the second cable guide member. Thus, such a lever makes it possible to obtain the pivoting of the second cable guide member.

According to one embodiment, the pivot axis is connected to the third cable guide member.

According to one embodiment, the first cable guide member is a first pulley, wherein the second cable guide member is a second pulley.

According to one variant, the third cable guiding member is a third pulley.

A pulley is a rotatable member arranged to rotate about a pulley axis.

According to a variant, the first pulley and the second pulley are arranged so that the axis of rotation of the first pulley and the axis of rotation of the second pulley are parallel and so that the first portion of the traction cable and the second portion of the traction cable are substantially coplanar.

Alternatively to pulleys, the first and / or the second cable guide member is a non-rotatable sliding member, for example comprising a sliding coating on which the pulling cable can slide, and thus move. A non-rotatable sliding member may be a rounded piece (e.g. rolled steel sheet) defining a minimum radius of curvature for winding the towing cable. Such a piece is sometimes called "harness".

Alternatively again to pulleys, the first and / or second cable guide member may be a roll which is generally cylinder-shaped and which may be composed for example of plastic or steel.

According to a variant, the return member is arranged so that a point of application of the return force is connected to the second cable guide member. According to a variant, a part of the return member may be mechanically connected to the lever which rotates the second cable guide member. In particular, when the second cable guide member comprises a second pulley, the return member can be arranged so that the point of application of the return force is close to the groove of the second pulley.

According to one embodiment, the third cable guide member is a third pulley, the pivot axis being collinear with the axis of rotation of the third cable guide member.

According to one embodiment, the foldable structure further comprises a support which is secured to a structural element and which comprises at least a first rotary bearing, the first cable guide member being rotatable on the first rotary bearing.

According to one embodiment, the return member comprises at least one gas cylinder.

According to a variant, the gas cylinder has a first portion secured to the first cable guide member and a second portion secured to the second cable guide member.

According to a variant, the return member comprises two gas cylinders located on either side of the first and second cable guide members.

According to an alternative to this embodiment, the return member is a compression spring arranged to work in compression.

In the embodiment where the second cable guide member is pivotally movable about a pivot axis, the return member may be a torsion spring arranged to work in torsion around the pivot axis. .

According to one embodiment, the foldable structure further comprises an abutment arranged to stop the displacement of the second cable guide member in the extended position.

According to one embodiment, the foldable structure further comprises a sensor configured to generate an abutment signal when the second cable guide member is in contact with the abutment.

According to one variant, the sensor is selected from the group consisting of an electric contactor, a capacitive sensor, an inductive sensor, a roller position sensor and an optical sensor.

According to one embodiment, at least one of said structural elements defines a passage configured to receive the traction cable and to house the first cable guide member, the second cable guide member and the return member.

The traction cable can thus extend inside each structural element.

Alternatively to this embodiment, the traction cable may extend outside each structural element. In this alternative, the first cable guide member and the second cable guide member are mounted on one or more of the outer surfaces defined by the structural members.

According to one embodiment, a difference between: the length of the intermediate portion of the traction cable when the second cable guide member is in the extended position; and the length of the intermediate portion of the traction cable when the second cable guide member is in the shortened position is between 0.2 m and 1.0 m.

Furthermore, the invention relates to a tower crane whose mast comprises a foldable structure according to the invention. In addition, the invention relates to a tower crane whose boom comprises a foldable structure according to the invention.

The embodiments and variants mentioned above may be taken individually or in any combination technically possible.

The present invention will be well understood and its advantages will also emerge in the light of the description which follows, given solely by way of nonlimiting example and with reference to the appended figures, in which identical reference signs correspond to elements structurally and / or functionally identical or similar. In the accompanying figures: FIG. 1 is a schematic view of a foldable structure according to the invention in unfolded configuration; Figure 2 is a schematic view of the foldable structure of Figure 1 in a partially folded configuration; Figure 3 is a perspective view of a portion of the foldable structure of Figure 1, wherein a second cable guide member is in the extended position; Figure 4 is a perspective view, at an angle identical to Figure 3, of the portion of the foldable structure of Figure 3, wherein the second cable guide member is in the position of shortening; Figure 5 is a sectional view of a part of the foldable structure of Figure 1 in unfolded configuration, wherein the second cable guide member is in the extended position; Figure 6 is a section similar to Figure 5 of the portion of the foldable structure of Figure 1 in unfolded configuration, wherein the second cable guide member is in the position of shortening; Figure 7 is a section similar to Figure 5 of the portion of the foldable structure of Figure 1 in folded configuration, wherein the second cable guide member is in the position of shortening; Figure 8 is a view, on a larger scale and rotated 90 degrees, of detail VIII in Figure 6; Figure 9 illustrates a foldable structure according to a second embodiment of the invention; and Figure 10 illustrates an unfolding method implementing a foldable structure according to the invention.

Figures 1 to 8 illustrate a foldable structure 1, to compose a tower crane symbolized by the reference 100 in Figure 1. The foldable structure 1 here forms a mast tower crane 100. As shown in Figure 1, the foldable structure 1 extends in a longitudinal direction X1 when in working configuration.

The foldable structure 1 comprises two structural elements 2.1, 2.2, a hinge member 4 and a pulling cable 6. The structural element 2.1 forms a first structural element and the structural element 2.2 forms a second structural element. When the foldable structure 1 is in an unfolded configuration (FIG. 1), the structural element 2.1 forms a lower structural element and the structural element 2.2 forms an upper structural element.

As shown in Figures 1 and 2, the structural element 2.2 is itself composed of an outer portion 2.21 and an inner portion 2.22. The outer portion 2.21 has a larger cross-section than the inner portion 2.22. The inner portion 2.22 is configured to slide in the outer portion 2.22 in a telescoping direction which is parallel to the longitudinal direction X1. The structural element 2.2 therefore composes a telescopic mast portion of the tower crane 100. The pulling cable 6 is here a cable for telescoping the outer portion 2.22 outside the inner portion 2.21.

The two structural elements 2.1, 2.2 are configured to compose a part of the structure of the tower crane. In the example of Figures 1 to 8, each structural element 2.1, 2.2 has an overall elongate shape. The structural elements 2.1 and 2.2 are here sections of the mast of the tower crane 100. When the tower crane 100 is in working configuration, the structural element 2.1 is a lower section of the mast and the structural element 2.2 is a upper section of the mast. The articulation member 4 is mechanically connected to the structural elements 2.1, 2.2 so that the structural elements 2.1.2.2 are movable between an unfolded configuration (Figure 1) and a folded configuration. 2 illustrates a configuration in which the foldable structure 1 is partially folded, the structural elements 2.1 and 2.2 forming between them an angle of about 60 degrees. Figure 7 illustrates a configuration in which the foldable structure 1 is folded, the structural elements 2.1 and 2.2 forming between them an angle A2 approximately equal to 10 degrees. The hinge member 4 here comprises a pivot connection arranged to pivot the structural elements relative to each other and about a hinge axis Y4 which is substantially orthogonal to the longitudinal direction X1 of the mast. the tower crane 100 in working configuration (Figure 1).

The traction cable 6 is configured to exert a traction force on components of the tower crane 100. The traction cable 6 extends along each structural element 2.1 and 2.2 when the structural elements 2.1 and 2.2 are in configuration unfolded (Figures 1, 5 and 6). When the tower crane 100 is in the service configuration, the traction cable 6 extends in a direction X6 which is slightly inclined, here about 2 degrees with respect to the longitudinal direction X1.

The foldable structure 1 further comprises a first cable guide member 10 and a second cable guide member 12.

The first cable guiding member 10 is configured to guide a first portion 6.1 of the pulling cable 6. The second cable guiding member 12 is configured to guide a second portion 6.2 of the pulling cable 6. The pulling cable 6a in addition an intermediate portion 6.3 which extends between the first cable guide member 10 and the second cable guide member 12.

In use, the dimensions and positions of the first and second portions 6.1 and 6.2 and the intermediate portion 6.3 change as a function of the movements of the traction cable 6 with respect to the first and second cable guide members 10 and 12.

The second cable guide member 12 is movable relative to the first cable guide member 10 between an extension position (Fig. 5) and a shortening position (Fig. 6). Due to this mobility, the intermediate portion 6.3 is longer when the second cable guiding member 12 is in the extended position (FIG. 5) than when the second cable guiding member 12 is in the shortening position (FIG. ), as shown in a comparison of Figures 5 and 6.

Similarly, the first and second portions 6.1 and 6.2 of the traction cable 6, which are respectively wound on the first and second guide members 10 and 12, are longer in the shortening position (FIG. 6) than in the position of lengthening (Figure 5).

The second cable guide member 12 is generally further away from the first guide member 10 in the extended position (FIG. 3) than in the shortened position (FIG. 4). The terms "elongation" and "shortening" indicate that the portion of the cable present in the foldable structure is larger in the extended position (FIG. 5) than in the shortened position (FIG. 6).

A difference between: the length of the intermediate portion 6.3 of the traction cable 6 when the second cable guide member 12 is in the extended position (FIG. 5); and the length of the intermediate portion 6.3 of the traction cable 6 when the second cable guide member 12 is in the shortening position (FIG. 6) is here approximately equal to 0.2 m.

The first cable guide member 10 and the second cable guide member 12 are arranged such that the side of the first cable guide member 10 guiding the pull cable 6 (first portion 6.1) is opposite the side of the second member. cable guide 12 guiding the traction cable 6 (second portion 6.2).

The first cable guide member 10 and the second cable guide member 12 are here connected to the structural element 2.1 which is therefore common to the first and second cable guide members 10 and 12. In the example of FIGS. at 8, the first cable guide member 10 is fixedly connected to the common structural member 2.1, while the second cable guide member 12 is movably connected to the common structural member 2.1.

The foldable structure 1 further comprises a return member 14 and a support 18. The return member 14 is configured to exert a return force F14, symbolized in FIG. 6, of the first cable guide member 10 towards the position lengthening (Figure 5). When the foldable structure is in the service configuration, the return member 14 exerts the return force F14 on the first cable guide member 10 towards the extension position (FIG. 5). The return member 14 here comprises two gas cylinders 14.1 and 14.2. The gas cylinders 14.1 and 14.2 are parallel and they extend on either side of the support 18 and on either side of the first 10 and the second 12 cable guide members.

Each gas cylinder 14.1 or 14.2 has a first end integral with the first cable guide member 10 and a second end integral with the second cable guide member 12.

The support 18 is secured to the common structural element 2.1. In the example of Figures 1 to 8, the support 18 is secured to a rear plate 2.11 component 2.1 structural element. The back plate 2.11 is located on the side opposite the arrow when the tower crane 100 is in the service configuration. In the shortening position (FIG. 6), the second cable guiding member 12 abuts against the rear plate 2.11.

The support 18 comprises a first rotary bearing 20. The first cable guide member 10 is rotatable on the first rotary bearing 20. The first rotary bearing 20 here comprises a ball bearing or roller. As shown in FIG. 3, the first cable guiding member 10 is equipped with a shaft and a pin for cooperating with the first rotary bearing 20.

The collapsible structure 1 further comprises a third cable guiding member 16 which is arranged such that, in the shortening position (FIG. 6), the second cable guiding member 12 is closer to the first cable guiding member 10 the third cable guide member 16. In other words, the distance between i) the second cable guide member 12 and ii) the first cable guide member 10 is smaller than the distance between iii) the third cable guide member 16 and iv) the first cable guide member 10. The support 18 comprises a third rotary bearing 23. The third cable guide member 16 is rotatable on the third rotary bearing 23.

The first cable guiding member 10, the second cable guiding member 12 and the third cable guiding member 16 are here substantially aligned when the second cable guiding member 12 is in a shortened position (Fig. 6).

In the example of Figures 1 to 8, the first cable guide member 10 is a first pulley, the second cable guide member 12 is a second pulley and the third cable guide member 16 is a third pulley. The structural element 2.1 defines a first passage 2.10 which is configured to receive the traction cable 6 and to accommodate the first 10, second 12 and third 16 cable guide members, the support 18 and the return member 14. From furthermore, the structural element 2.2 defines a second passage 2.20 which is configured to receive the pulling cable 6. The pulling cable 6 extends partly inside the structural elements 2.1 and 2.2.

Each of the first, second and third cable guide members 10, 12 and 16 is configured to guide the pulling cable 6 in motion without excessive wear of the pulling cable 6. Each of the first, second and third cable guide members 10 , 12 and 16 has a guide groove 10.0, 12.0 and 16.0 adapted to respectively receive first 6.1, second 6.2 and third 6.4 portions of the traction cable 6.

The first cable guide member 10 is configured to perform a deflection function, so that the strands of the traction cable 6 located on either side of the first cable guide member 10 form an angle between them. . Likewise, the second and third cable guiding members 12 and 16 are each configured to perform a deflection function.

As shown in FIG. 7, to guide the traction cable 6 between the structural elements 2.1 and 2.2 when the foldable structure is in the folded configuration (FIG. 7), the articulation member 4 comprises a guiding portion 4.6 and the elements 2.1 and 2.2 each comprise a pad 2.16 or 2.26 which are located on either side of the hinge member 4. The guide portion 4.6 and the pads 2.16 and 2.26 are configured to guide the pulling cable 6 when the foldable structure is in folded configuration (Figure 7).

Furthermore, the first cable guide member 10 (first pulley), the second cable guide member 12 (second pulley) and the third cable guide member 16 (third pulley) are arranged: so that the axis of rotation Y10 of the first pulley, the axis of rotation Y12 of the second pulley and the axis of rotation Y16 of the third pulley are parallel, and so that the first portion 6.1 of the traction cable 6, the second portion 6.2 the traction cable 6 and the third portion 6.4 of the traction cable 6 are substantially coplanar (in the plane of Figure 5 or 6).

The second cable guide member 12 is pivotally movable about a pivot axis Y30. The pivot axis Y30 is remote from the second cable guide member 12. To obtain this pivoting, the foldable structure 1 comprises a lever 30 which is integral with the second cable guide member 12. The lever 30 is composed of two flanges side members which are here integral with the pulley constituting the second cable guide member 12. The lever 30 comprises a second rotary bearing 22. The second cable guide member 12 is rotatable on the second rotary bearing 22. The organ 14 is here arranged so that a point of application P 14.4 of the return force F14 is connected to the second cable guide member 12. In this case, one end of the return member 14 is mechanically connected to the lever 30 which rotates the second cable guide member 12. In addition, the return member 14 is arranged so that the application point P 14.4 of the biasing force F14 is close to the throat 12.0 of the second pulley.

In the example of Figures 1 to 8, the pivot axis Y30 is connected to the third cable guide member 16. In addition, the pivot axis Y30 is collinear with the axis of rotation Y16 of the third guide member Therefore, the pivot axis Y30 is orthogonal to the longitudinal direction X1 of the mast of the tower crane 100 in working configuration (FIGS. 1, 5 and 6).

In addition, the foldable structure 1 comprises a stop 24 which is arranged to stop the movement of the second cable guide member 12 in the extended position (FIGS. 3, 5 and 8). The stop 24 is arranged in an adjustable and removable manner. The return member 14 further comprises an abutment plate 14.5, which is connected to the gas cylinders 14.1 and 14.2 and which is arranged to abut against the abutment 24 in the extended position (Figures 3 and 5).

In addition, the collapsible structure 1 comprises a sensor 26 which is configured to generate a stop signal when the second cable guide member 12 is in contact with the stopper 24 (FIGS. 3, 5 and 8). The sensor 26 is here an electric contactor. The sensor 26 is arranged in an adjustable and removable manner.

When the tower crane 100 is in telescoping phase, the inner portion 2.22 of the structural element 2.2 rises out the outer portion 2.21. The traction cable 6 is then strongly stretched because it is subjected to a high tensile force F6. As shown in FIG. 6, this traction force F6 induces a cable force F12 on the second cable guide member 12. At the same time, the return member 14 produces a return force F14 on the second cable guide member 12.

This cable stress F12 pushes the second cable guide member 12 into the shortening position (FIG. 6). Taking into account the lever arms L12.16 and L14.16 respectively for the cable effort F12 and the return force F14, the moment generated (F 12 x L12.16) by the cable effort F12 around the pivot axis Y30 is greater than the generated moment (F12 x L14.16) by the return force F14 around the pivot axis Y30. Consequently, the second cable guide member 12 is pressed against the rear plate 2.11 and / or the support 18.

In this position of shortening (Figure 6), the forces exerted on the traction cable 6 are large, which induces significant friction against the first 10 and second 12 cable guide members. However, the traction cable 6 is little wound on the first, second and third pulleys. Thus, the pulling cable 6 has only a small length in contact with the first 10 and second 12 cable guiding members, which makes it possible to minimize the wear of the pulling cable 6 in the shortening position (FIG. 6).

In use, when the tower crane 100 is in working configuration, the inner 2.21 and outer 2.22 portions of the structural element 2.2 are mutually locked by means of a not shown stop which transmits the forces of the inner portion 2.21 to the outer portion 2.22. In this working configuration, the tower crane 100 can lift and move unrepresented loads.

The traction cable 6 is weakly tensioned because it then undergoes a low or zero tensile force F6. The return member 14 produces the return force F14 on the second cable guide member 12. In particular, the "effective" component of the cable force F12 which is orthogonal to the lever arm L12.16 (around the pivot axis Y30) is smaller in the extended position (FIG. 5) than in the shortened position (FIG. 6).

Taking into account the lever arms L12.16 and L14.16 respectively for the cable effort F12 and the return force F14, the moment generated (F12 x L14.16) by the return force F14 is greater that the generated moment (F12 x L12.16) by the cable F12 force around the pivot axis Y30 around the pivot axis Y30. Consequently, the second cable guide member 12 is pushed into the extended position (FIG. 5) and abuts against the stop 24.

In this extension position (FIG. 5), the forces exerted on the traction cable 6 are small, which induces weak friction against the first 10 and second 12 cable guide members. Thus, even if the traction cable 6 is wound a lot on the first, second and third pulleys, the wear of the traction cable 6 remains negligible in the extension position (FIG. 5).

When the second cable guide member 12 abuts against the stop 24, the sensor 26 generates a stop signal, which is received by a control unit not shown. The control unit can either inform the operator of the tower crane 100 or control an automatic sequence of positioning of the components of the tower crane 100.

When the tower crane 100 goes into folded configuration (Figure 7), the structural elements 2.1 and 2.2 form between them an angle A2 approximately equal to 10 degrees. As shown in FIG. 7, the traction cable 6 is guided between the structural elements 2.1 and 2.2 by the guide portion 4.6 belonging to the articulation member 4 and by the studs 2.16 and 2.26 situated on either side of the articulation member 4.

The length of the traction cable 6 undergoes a significant variation due to the change of angle (folding) of the structural elements 2.1 and 2.2. If the guide element 12 were not mobile, significant forces could be induced in the traction cable 6. Thanks to the mobility of the guide element 12, the variation imposed on the length of the first and second portions 6.1 and 6.2 and the intermediate portion 6.3 induces a traction force F6 significant but less important than in the telescoping phase.

As shown in FIG. 6, this traction force F6 induces a cable force F12 on the second cable guide member 12. At the same time, the return member 14 produces a return force F14 on the second cable guide member 12.

This cable stress F12 pushes the second cable guide member 12 into a shortening position (FIG. 7). Taking into account the lever arms L12.16 and L14.16 respectively for the cable effort F12 and the return force F14, the moment generated (F12x L12.16) by the cable force F12 around the pivot axis Y30 is larger than the generated moment (F12 x L14.16) by the return force F14 about the pivot axis Y30. Consequently, the second cable guide member 12 is pressed against the rear plate 2.11 and / or the support 18.

During folding, the mechanism actuating the traction cable 6 is inactive. The structural element 2.2 arrives on a mechanical stop not shown, which limits the angle between the structural elements 2.1 and 2.2. The foldable structure 1 is arranged so that the tensile force F6 in the shortening position is sufficient to maintain the second cable guide member 12 in a position pressed against the support 18 despite the gravity pushing the second cable guide member 12 to return to the extended position (Figure 5).

Moreover, a determination method for determining dimensions of the foldable structure 1, for example by means of a sketch, is described below in relation to FIG. 8: trace the path of the traction cable 6 along the elements 2.1 and 2.2, on the one hand in folded configuration (Figure 7) and on the other hand in unfolded configuration (Figures 1 and 5); calculating the difference in length of the traction cable 6 caused by the change to the folded configuration (FIG. 7); position the point P16 in one of the angles of the first 2.10 or second 2.20 passage during the creation of a tensile cable tension system 6; in addition, the point P16 is positioned at a distance from the path of the traction cable 6 equal to a pulley radius (third cable guide member 16); position the offset point P10 to an opposite angle of the first 2.10 or second 2.20 passage, for example at a distance equal to twice the diameter of the second pulley constituting the second cable guide member 12; position the point P12 in folded configuration (Figure 7) with the second pulley 12 abuts against the back plate 2.11 and / or the support 18; trace the path of the traction cable in folded configuration (Figure 7); rotate the lever 30 to the maximum taking into account the available space and the acceptable winding angle for the traction cable 6 on the second pulley 12; adapt the radius of the second pulley 12 according to the size and the position of the point P10; trace the path of the traction cable 6 with its adapted radius; calculating the difference in the length of the traction cable 6 induced by the transition from the extension position (FIG. 5) to the shortening position (FIG. 6); if this difference in the length of the traction cable is not substantially identical to the variation of the length of the traction cable 6 due to the folding of the structural elements 2.1 and 2.2, adjust the dimensions and locations of the first, second and third pulleys in position d elongation (Figure 5); after having defined the position of elongation (FIG. 5) and the position of shortening (FIG. 6) of the second pulley, position the point P14.3 in order to maximize the length of the lever arm of the return member 14 in position lengthening (Figure 5); point P14.3 represents one end of the gas cylinders 14.1 and 14.2; plotting the support direction of the force F14 exerted by the return member 14, so that this support direction is substantially orthogonal to the line carrying the points P16 and P12; select a return member 14 (e.g. gas cylinder) according to the standard dimensions available on the market position the point P14.4 which represents another end of the gas cylinders 14.1 and 14.2; adjusting the locations of the points P14.3 and P14.4 according to the space required for the return member 14 and the fastening stresses to the support 18; to verify by calculation the conditions for setting the shortening position (moment of the cable force F12 greater than the moment of the return force F14) in the telescoping phase; the difference must be significant, for example a ratio at least equal to 2 of the moment due to the force of the cable F12 on the moment due to the return force F14; check by calculation the conditions of setting elongation position (moment of lower cable effort F12 at the moment of the return force F14); the cable force F12 is then considered to be zero and the moment due to the return force F14 must be greater than the moment generated by the gravity; the difference must be significant, for example a ratio of at least 2; and positioning the abutment 24 in an extended position (FIG. 5) near the point P14.4 and as a function of the space requirement or available space, in order to limit or avoid the generation of secondary moments; the secondary moments are calculated with a lever arm measured between i) the point of contact of the traction cable 6 with the respective pulleys and ii) the direction of the return force F14; these lever arms are less than a few tens of millimeters.

However, in the context of the invention, other methods of determination can be implemented to determine dimensions of the foldable structure 1.

Figure 9 illustrates a foldable structure 1 according to a second embodiment. Insofar as the foldable structure 1 of FIG. 9 is similar to the foldable structure 1 of FIGS. 1 to 8, the description of the foldable structure 1 given above in relation to FIGS. 1 to 8 can be transposed to the structure Foldable 1 of Figure 9, with the notable differences noted below.

The foldable structure 1 of FIG. 9 differs from the foldable structure 1 of FIGS. 1 to 8, especially since the foldable structure 1 of FIG. 9 comprises only a first cable guide member 10 and a second cable guide member 12. But the foldable structure 1 of Figure 9 does not include a third cable guide member, unlike the foldable structure 1 of Figures 1 to 8.

Thus, in the foldable structure 1 of FIG. 9, the traction cable 6 is guided only by a first pulley and a second pulley. Consequently, in the structural element 2.2, the traction cable 6 follows an oblique direction which forms an angle A6.1 with respect to the longitudinal direction 1 of the foldable structure 1. The angle A6.1 is here approximately equal to 30 degrees. This solution is particularly suitable in the case where there are few constraints to define the space available inside the structural element 2.2.

FIG. 10 illustrates a sequence of the different phases or configuration of the foldable structure 1 of FIGS. 1 to 8: 1002) the foldable structure 1 is in folded configuration; the second cable guide member 12 is in the shortening position (FIG. 7) against the support 18; 1004) after unfolding, the foldable structure 1 is in unfolded configuration; the second cable guide member 12 is in the extended position (FIG. 5) and abuts against the stop 24; the sensor 26 generates a stop signal; 1006) during the telescoping of the outer portion 2.22 of the structural element 2.2, the foldable structure 1 is in unfolded configuration and the outer portion 2.22 is in the out position outside the inner portion 2.21; the traction cable 6 is stretched, so the second cable guide member 12 is in the position of shortening (Figure 6) against the support 18; 1008) after locking the outer portion 2.22 relative to the inner portion 2.21, the foldable structure 1 remains unfolded configuration; maintaining the control of the retraction movement of the outer portion 2.22 has the effect of relaxing the pulling cable 6, so the second cable guiding member 12 is in the extended position (Figure 5) against the stop 24; the sensor 26 generates a stop signal; 1010) after unlocking, the foldable structure 1 remains in unfolded configuration; the traction cable 6 is stretched, so the second cable guide member 12 is in the position of shortening (Figure 6) against the support 18; and 1012) after complete unfolding, the foldable structure 1 is still in unfolded configuration; the outer portion 2.22 is in mechanical abutment against the inner portion 2.21 of the structural element 2.2; the traction cable 6 is then expanded, so the second cable guide member 12 is in the extended position (FIG. 5) against the abutment 24, the sensor 26 generates a stop signal.

After folding of the structural elements 2.1 and 2.2, the operating cycle of the foldable structure 1 can then start again with step 1002). The operating cycle can be performed manually by an operator or automatically by the control unit.

Of course, the present invention is not limited to the particular embodiments described in the present patent application, nor to embodiments within the scope of those skilled in the art. Other embodiments may be envisaged without departing from the scope of the invention, from any element equivalent to an element indicated in the present patent application.

Claims (16)

1. Foldable structure (1), to compose a tower crane, the foldable structure (1) comprising at least: two structural elements (2.1, 2.2) configured to compose a part of the structure of the tower crane, a body of articulation (4) mechanically connected to the structural elements (2.1, 2.2) so that the structural elements (2.1, 2.2) are movable between an unfolded configuration and a folded configuration, a traction cable (6) configured to exert a force of traction on components of the tower crane, the foldable structure (1) being characterized in that it further comprises at least: a first cable guiding member (10) configured to guide a first portion (6.1) of the cable a second cable guide member (12) configured to guide a second portion (6.2) of the pulling cable (6), the pulling cable (6) having an intermediate portion (6.3) which extends between the first guide member of the cable (10) and the second cable guide member (12), the second cable guide member (12) being movable relative to the first cable guide member (10) between an extension position and a position shortening, so that the intermediate portion (6.3) is longer when the second cable guide member (12) is in the extended position than when the second cable guide member (12) is in the shortened position; and a return member (14) configured to exert a biasing force of the first cable guide member (10) toward the extension position. Foldable structure (1) according to the preceding claim, wherein at least one structural element (2.1, 2.2) has an overall elongate shape. Foldable structure (1) according to any one of the preceding claims, wherein the first cable guide member (10) and the second cable guide member (12) are connected to a common structural member (2.1). 4. foldable structure (1) according to the preceding claim, wherein the first cable guide member (10) is fixedly connected to said common structural member (2.1), and wherein the second cable guide member (12). is movably connected to said common structural element (2.1). Foldable structure (1) according to any one of the preceding claims, further comprising a third cable guide member (16) arranged such that, in a shortened position, the second cable guide member (12) is closer to the first cable guide member (10) than the third cable guide member (16). 6. foldable structure (1) according to the preceding claim, wherein the first cable guide member (10), the second cable guide member (12) and the third cable guide member (16) are substantially aligned when the second cable guide member (12) is in a shortened position. Foldable structure (1) according to any one of the preceding claims, wherein the second cable guide member (12) is movable at least pivotally about a pivot axis (Y30) remote from the second guide member. of cable (12). 8. foldable structure (1) according to claims 6 and 7, wherein the pivot axis (Y30) is connected to the third cable guide member (16). Foldable structure (1) according to any one of the preceding claims, wherein the first cable guide member (10) is a first pulley, wherein the second cable guide member (12) is a second pulley. 10. foldable structure (1) according to claims 8 and 9, wherein the third cable guide member (16) is a third pulley, the pivot axis (Y30) being collinear with the axis of rotation (Y16). the third cable guide member (16). 11. foldable structure (1) according to any one of the preceding claims, further comprising a support (18) which is secured to a structural member (2.1, 2.2) and which comprises at least a first rotary bearing (20), the first cable guide member (10) being rotatable on the first rotational bearing (20). 12. Foldable structure (1) according to any one of the preceding claims, wherein the return member (14) comprises at least one gas cylinder (14.1, 14.2). 13. Foldable structure (1) according to any one of the preceding claims, further comprising a stop (24) arranged to stop the movement of the second cable guide member (12) in the extended position. 14. foldable structure (1) according to the preceding claim, further comprising a sensor (26) configured to generate a stop signal when the second cable guide member (12) is in contact with the stop (24). Foldable structure (1) according to any one of the preceding claims, wherein at least one of said structural elements (2.1, 2.2) defines a passage (2.10, 2.20) configured to receive the traction cable (6) and for accommodating the first cable guide member (10), the second cable guide member (12) and the return member (14). Foldable structure (1) according to any one of the preceding claims, wherein a difference between: the length of the intermediate portion (6.3) of the traction cable (6) when the second cable guide member (12) is in the lying position; and the length of the intermediate portion (6.3) of the pulling cable (6) when the second cable guide member (12) is in the shortening position is between 0.2 m and 1.0 m.