Cable anchoring system

Abstract

The invention relates to a cable anchoring system (3) comprising: - a frame (2), - a drum (1) rotatably mounted on the frame about an axis of rotation (X), the drum having a lateral surface (S) about an axis (Y) parallel to the axis of rotation (X), the drum being adapted to allow cable movement by winding and / or unwinding said cable along a portion of the lateral surface, by rotation of said drum about the axis of rotation (X) in response to a variation in the mechanical tension of the cable, - at least one torsion spring (10a, 10b, 10c, 10d) arranged between the drum and the frame so as to compensate for the variation in cable tension. Figure for the abstract: Fig 7A

Description

Title of the invention: Cable anchoring system technical field

[0001] The invention relates to a cable anchoring system, a lifting device comprising such an anchoring system and a lifting machine comprising said anchoring system. STATE OF THE ART

[0002] The lifting and handling of containers can be carried out using a spreader, commonly called a "spreader," connected by cables to a crane, typically a Ship-to-Shor (STS) crane, for unloading containers from a ship or loading containers onto a ship. Motors mounted on the crane raise or lower the spreader via the cables. Twist locks are also attached to the spreader. Opening and closing the twist locks secures and releases a container. The twist locks are typically powered by a hydraulic unit, most often mounted on the spreader.The hydraulic unit can also be adapted to force the extension or contraction of the grab frame during use, so as to adapt the grab frame for handling containers of different sizes. The hydraulic unit is advantageously powered from the crane via a cable: one end of the cable is wound around a reel mounted on the crane, and the other end is connected to the grab frame, advantageously via a frame (commonly called a "head block") under which the grab frame is mounted. Alternatively, the lifting devices are entirely electric, and their power supply from the crane is also provided by such a cable.The cable may also include a data bus, for example a CAN bus (according to the Anglo-Saxon acronym "Controller Area Network"), responsible for transmitting locking or unlocking information to the hooking devices as well as any other information necessary for operating the crane (weighing, lighting, etc.).

[0003] In order to avoid damaging the cable, the unwinding and winding of the cable around the reel must ensure that the cable remains taut during all lifting, unloading, loading, etc., operations of the containers. The unwinding and winding of the cable around the reel must follow the movements of the gripping frames are most often managed automatically by controlling the reel according to a theoretical model which calculates the torque to be applied to the reel as a function of the operating phase and the position of the crane on its stroke.

[0004] However, since the movement of the gripping frame is often controlled manually by the crane operator, some movements of the gripping frame cannot be immediately compensated for by the reel. This is particularly true in the event of sudden movements of the gripping frame when said frame is subjected to shocks, for example if the container misses the slipway and strikes the container ship's rails.

[0005] A cable anchoring system is therefore mounted on the chassis under which the gripping frame is mounted. This anchoring system may include a cylindrical drum advantageously mounted to rotate relative to the chassis by means of bearings, for example, ball bearings. Under the effect of cable tension, for example, in the event of a sudden movement of the gripping frame, said drum is set in rotation about its axis of rotation. The rotational movement of the drum induces the winding and / or unwinding of the cable around said drum, thus providing a certain amount of cable travel.

[0006] The anchoring system may further include a compression spring coupled to one or more shock absorbers, for example hydraulic, metallic, or elastic shock absorbers (tensioners), adapted to dampen the cable's movement. More specifically, when the reel pulls or pushes on the cable and the drum is set in rotation, the compression spring provides a restoring force on the drum proportional to the extension of the compression spring under the effect of the drum's rotation, and the shock absorber absorbs the shock.

[0007] However, such anchoring systems, whose size is limited by the dimensions of the chassis on which they are mounted, do not allow sufficient cable movement, particularly in the event of impacts. Indeed, the movement afforded to the cable by the anchoring system is typically around 40 mm in the direction of cable unwinding when the reel pulls on the cable and 40 mm in the direction of cable winding when the reel releases the tension on the cable. This results in rapid cable wear, requiring frequent and costly maintenance.

[0008] Furthermore, the compression spring is subjected to high stresses and consequently has a short service life, which may be less than one year of use, assuming approximately 2000 hours of spring use per year. It is then necessary to change the anchoring system or replace the spring. The bearing service life is also shorter than expected.

[0009] Furthermore, the compression spring and / or other damping means that the anchoring system may include can prove to be cumbersome. BRIEF DESCRIPTION OF THE INVENTION

[0010] An object of the invention is to design a cable anchoring system, preferably adapted to be mounted on a crane chassis intended to support a gripping frame, allowing a greater deflection of the cable than the anchoring systems previously described and which remains compact and easily manufacturable.

[0011] To this end, the invention proposes a cable anchoring system comprising:

[0012] - a frame,

[0013] - a drum mounted to rotate on the chassis around an axis of rotation, the drum presenting a lateral surface around an axis parallel to the axis of rotation, the drum being adapted to allow cable movement by winding and / or unwinding said cable along a portion of the lateral surface, by rotation of said drum around the axis of rotation in response to a variation in cable tension,

[0014] - at least one torsion spring arranged between the drum and the frame so as to compensate for variations in cable tension.

[0015] Under the effect of the drum's rotational movement around its axis of rotation, the torsion spring generates a torsion angle around said axis of rotation to compensate for the variation in cable tension. Conversely, a compression spring generates elongation, and to be able to compensate for the variation in cable tension, said compression spring must be supplemented with clevises and / or pivot joints. Furthermore, torsion springs are compact, and increasing the cable's travel by winding and / or unwinding said cable around the lateral surface amounts to increasing the angular offset between the extreme torsion angles of said torsion spring, which does not result in any additional bulk or manufacturing difficulties for said torsion springs.Conversely, increasing the cable's travel with a compression spring increases the length of the compression spring, and therefore its size, and / or brings the compression spring closer to the axis of rotation. This implies that the compression spring must be able to withstand significantly greater forces. Such a compression spring is difficult to manufacture. The anchoring system incorporating the torsion spring(s) is therefore simpler to manufacture, more adaptable, and less bulky.

[0016] According to other advantageous but optional features, considered alone or in combination: - at least one torsion spring comprises a first part mounted on the chassis and a second part mounted on the drum, the second part being adapted to pivot relative to the first part; - the anchoring system includes at least two torsion springs arranged in series; - a first part of a first spring is mounted on the chassis, a first part of a second spring is mounted on the drum, and a second part of the first spring is rigidly linked to a second part of the second spring; - each torsion spring comprises a rigid, hollow outer shaft, a rigid central shaft housed inside the rigid, hollow outer shaft, and a damper configured to dampen a torsional movement of the rigid, hollow outer shaft relative to the rigid central shaft; - the torsion spring damper comprises a plurality of elastomer elements arranged between the rigid central axis and the rigid, hollow external axis; - each torsion spring comprises a first hollow, square-based metallic prism forming the rigid, hollow external axis, a second prism forming the central axis arranged in the first prism with an angular offset from the first prism, and each elastomer element is a cylinder arranged between the first prism and the second prism, in each corner of the first prism; - the anchoring system comprises two torsion springs in series, the second square-based prism of the first torsion spring being connected to the second square-based prism of the second torsion spring; - at least one torsion spring is configured to dampen the forces generated by the rotation of the drum around the axis of rotation between a first stop position of the drum and a second stop position of the drum, the first stop position and the second stop position being angularly offset from the axis of rotation by an angle between 0° and 90°, preferably between 0° and 60°; - the anchoring system includes at least two sets of torsion springs arranged in parallel, a first part of each set of torsion springs being mounted on the chassis and a second part of each set of torsion springs being mounted on the drum; - the anchoring system further includes a compression spring and / or a tension spring comprising a first part mounted on the chassis and a second part mounted on the drum.

[0017] Another object of the invention relates to a lifting device comprising:

[0018] - a gripping frame comprising at least one load-holding device to lift,

[0019] - a cable anchoring system as described above comprising a chassis and a drum, the chassis being fixed to the gripping frame and the drum being fixed to the chassis,

[0020] - a reel adapted to be fixed on a lifting device,

[0021] - a cable, a first end of the cable being anchored to the drum of the system anchoring by fixed winding of at least two turns around the lateral surface of the drum and a second end of the cable being wound around the reel.

[0022] Another object of the invention relates to a lifting device, such as a crane, a gantry or a forklift, comprising a lifting device as described above. BRIEF DESCRIPTION OF THE FIGURES

[0023] Other features and advantages of the invention will become apparent from the detailed description that follows, with reference to the accompanying drawings, in which:

[0024] [Fig.1A]

[0025] [Fig.1B]

[0026] [Fig.1C]

[0027] - Figures IA, IB and IC illustrate an example of the application of an anchoring system cable according to the invention in which said system is fixed on a gripping frame itself mounted on a crane;

[0028] - Figures 2A, 2B and 2C represent a particular embodiment of the system anchoring of a cable according to the invention in which the lateral surface of the drum has a circular shape and an axis of rotation of the drum relative to the frame passing through the center of the circle: [Fig.2A] represents the neutral position of the drum, [Fig.2B] represents the case of the application by the cable of a subtraction on the drum causing the rotation of said drum in the direction of the winding of the cable, [Fig.2C] represents the case of the application by the cable of an overtraction on the drum causing the rotation of said drum in the direction of the unwinding of the cable;

[0029] - Figures 3A, 3B and 3C represent a particular embodiment of the system anchoring of a cable according to the invention in which the lateral surface of the drum has a circular shape and an axis of rotation of the drum relative to the frame offset from the center of the circle: [Fig.3A] represents the neutral position of the drum, [Fig.3B] represents the case of the application by the cable of a subtraction on the drum causing the rotation of said drum in the direction of the winding of the cable, [Fig.3C] represents the case of the application by the cable of an overtraction on the drum causing the rotation of said drum in the direction of the unwinding of the cable;

[0030] - Figures 4A, 4B and 4C represent a particular embodiment of the system cable anchoring according to the invention, wherein the lateral surface of the drum has an elliptical shape and the axis of rotation of the drum relative to the frame is offset from the center of the ellipse: [Fig. 4A] represents the neutral position of the drum, [Fig. 4B] represents the case of the application of a subtraction by the cable on the drum causing the rotation of said drum in the direction of the winding of the cable, [Fig.4C] represents the case of the application by the cable of an over-traction on the drum causing the rotation of said drum in the direction of the unwinding of the cable;

[0031] - [Fig. 5] represents a cable anchoring system in which said system includes a drum having an elliptical shape and an axis of rotation offset from the center of the ellipse, as well as a compression spring adapted to dampen cable movement by winding and / or unwinding the cable around a portion of the ellipse;

[0032] - Figure 6 represents a particular embodiment of a torsion spring comprising a first hollow, square-based metallic prism, a second hollow, square-based metallic prism housed inside the first prism with an angular offset from the first prism, and four elastomer cylinders arranged between the first prism and the second prism, in the corners of the first prism;

[0033] - Figures 7A, 7B, 7C and 7D represent a particular embodiment of the anchoring system of the invention in which said system comprises a drum having an elliptical shape and an axis of rotation offset from the center of the ellipse as well as two sets of torsion springs adapted to dampen a deflection of the cable by winding and / or unwinding the cable around a portion of the ellipse and arranged along the axis of rotation of the drum so as to allow the rotation of said drum relative to the frame, each set of torsion springs comprising two torsion springs mounted in series, [Fig.7B] representing the neutral position of the drum, [Fig.7C] representing the case of the application by the cable of a subtraction on the drum causing the rotation of said drum in the direction of the winding of the cable, [Fig.7D] representing the case of the application by the cable of an overtraction on the drum causing the rotation of said drum in the direction of the unwinding of the cable;

[0034] - [Fig.8] represents a particular embodiment of the anchoring system according to the invention wherein at least one torsion spring is a metallic spring, the anchoring system further comprising a shaft and a bearing, the shaft and bearing being configured to guide the rotation of the drum relative to the chassis around its axis of rotation.

[0035] For reasons of legibility, the drawings are not necessarily drawn to scale. DETAILED DESCRIPTION OF IMPLEMENTATION METHODS

[0036] The invention relates to a cable anchoring system comprising a frame and a drum, the drum being adapted to be mounted on the frame and to anchor the cable on said frame.

[0037] With reference to Figures IA, IB and IC, the chassis 2 is preferably a chassis adapted for mounting on a gripping frame 4, said gripping frame 4 comprising one or more fastening members 5, said fastening members being adapted for gripping a load. The fastening members 5 of the gripping frame 4 may, for example, comprise four rotating latches adapted for gripping a container.During use, the gripping frame 4 is connected to a lifting device 6, for example a crane, by means of lifting 7 for said gripping frame 4. These lifting means 7 are adapted to allow movement of the gripping frame 4 relative to the lifting device 6, typically raising or lowering said gripping frame 4. This movement can be remotely controlled by an operator, for example a crane operator positioned in the cab or in a control room from which they operate several cranes alternately. Alternatively, this movement can be managed completely automatically without the intervention of said operator. The lifting means 7 for the gripping frame 4 may include cables and one or more motors mounted on the lifting device 6.

[0038] According to an embodiment not shown in Figures IA, IB, and IC, a second gripping frame can be connected to the lifting device 6 by means of lifting said second gripping frame, said lifting device 6 further comprising an intermediate platform. Such a configuration is particularly advantageous when the lifting device is an STS crane: the gripping frame 4 is used to move a container between the ship and the platform, while the second gripping frame is used to move said container between the platform and the quay.

[0039] The cable 3 comprises one or more conductive links for the transfer of power and / or data. Each conductive link may be in the form of an electrically conductive wire, an optical fiber, or any other suitable form. Preferably, the cable comprises at least one conductive power link and one conductive control link for the gripping devices 5 of the gripping frame 4. When the drum 1 is in use, i.e., when the drum 1 is mounted on the chassis 2, the chassis 2 mounted on a gripping frame 4, and the gripping frame 4 connected to a lifting device 6, one end of the cable is anchored to the chassis 2 via the drum 1, and a second end of the cable 3 is wound around a reel mounted on the lifting device 6.More specifically, the drum according to the invention comprises a lateral surface (S) situated around an axis (Y), such that when the drum 1 is in use, the first end of the cable 3 is wound around said lateral surface (S).

[0040] The cable reel mounted on the lifting device is typically an electronically controlled reel comprising a motor that winds or unwinds the cable so as to keep the cable taut regardless of the operating phase of the gripping frame (for example, during lifting, lowering, starting, or stopping). A control unit calculates a torque setpoint to be applied based on said operating phase. The torque value must be high enough to keep the cable taut without damaging it. The torque setpoint is sent to a frequency converter, which translates it into a current to be supplied to the motor. A change in the torque setpoint, for example, when the position of the gripping frame changes or the operating phase changes, results in a change in the motor current.Such a control loop exhibits a non-zero response time, which is the sum of at least one response time related to the electronics and one response time related to the conversion of the setpoint into current. The response time related to the electronics is estimated to be around 75 ms. This response time does not allow the reel to react quickly enough in certain situations, for example, during sudden movements of the gripping frame, such as in the event of shocks or gusts of wind, thus generating tension in the cable.

[0041] The drum 1 is therefore adapted to be mounted rotatably on the frame 2 around an axis of rotation (X) parallel to the axis (Y), so that when the drum 1 is in use, the drum 1 can be freely rotated around the axis of rotation (X) under the effect of a tension in the cable 3 not immediately compensated by the winder, thus allowing a movement of the cable 3 by the winding and / or unwinding of said cable around the lateral surface (S) along a portion of the lateral surface (S).

[0042] More specifically, the drum, in a position described as neutral, can be subjected to a tensile force from the cable due to the torque imposed on said cable by the winder, which keeps said cable taut. Mechanical tension on the cable is understood as a variation in the tension applied by the cable on the drum compared to the tension applied to said drum in the neutral position. This can be under-tension (a configuration corresponding to slack in the cable) or over-tension (a configuration in which the winder pulls on the cable with a tension greater than the theoretical resultant of the setpoint). Such mechanical tension will cause a rotational movement of the drum around the axis of rotation (X) relative to this neutral position.In the case of under-tension, the rotational movement around the axis of rotation (X) will be in the direction of winding to take up the slack in the cable until it eventually reaches a first stop position. In the case of over-tension, the rotational movement around the axis of rotation (X) will be in the direction of winding to take up the slack in the cable until it eventually reaches a first stop position. In the case of over-tension, the rotational movement around the axis of rotation (X) will be in the direction of winding. rotation (X) will be in the direction of cable unwinding to release cable until possibly reaching a second stop position.

[0043] By way of example, the first and second stop positions are angularly offset from the axis of rotation (X) by an angle between 0° and 60°, preferably by an angle between 0° and 90°.

[0044] The lateral surface (S) of the drum in a plane (P) perpendicular to the axis of rotation (X) may have a circular shape. Alternatively, the lateral surface (S) may have an ovoid or elliptical shape in the plane (P), or any other shape whose radius of curvature is not constant.

[0045] The axis of rotation (X) can intersect the plane (P) at the center of a circle with a radius equal to the radius of curvature of the portion of the lateral surface along which the cable is wound and / or unwound and tangent to said portion. For example, if the lateral surface has a circular shape in the plane (P), the axis of rotation (X) can intersect the plane (P) at the center of the lateral surface.

[0046] Alternatively, the axis of rotation (X) can intersect the plane (P) at any other point in the plane (P).

[0047] Figures 2A, 2B, and 2C illustrate a particular example of a drum in use on a frame, in which the drum has a circular shape in plane (P) and the axis of rotation (X) intersects plane (P) at the center of the circle. In particular, [Fig. 2A] represents the configuration in which the drum is in a neutral position. [Fig. 2B] represents the case of cable undertension: the drum rotates from said neutral position in the direction of cable winding around the axis of rotation (X) to wind the slack cable. [Fig. 2C] represents the case of cable overtension: the drum rotates from the neutral position in the direction of cable unwinding around the axis of rotation (X) to unwind cable.

[0048] Figures 3A, 3B, and 3C represent another specific example of a drum in use on a frame, in which the drum still has a circular shape in plane (P), but the axis of rotation (X) does not intersect plane (P) at the center of the circle. In particular, [Fig. 3A] represents the configuration in which the drum is in the neutral position. [Fig. 3B] represents the case of cable undertension. [Fig. 3C] represents the case of cable overtension.

[0049] By way of further example, Figures 4A, 4B, and 4C represent a case in which the drum has an elliptical shape in plane (P) and the axis of rotation (X) does not intersect plane (P) at the center of the ellipse, but at the center of a circle with a radius equal to the radius of curvature of the portion of the lateral surface (S) of the cable winding and / or unwinding and tangent to said portion. Figure 4A represents the neutral position of the drum, Figure 4B the case of cable undertension, and Figure 4C the case of cable overtension.

[0050] Preferably, the drum is arranged such that, during use of said drum, a first portion of the first end of the cable remains wound around said surface (S) in all phases of chassis use, and a second portion of said cable, extending from the first portion, winds and / or unwinds along the portion of the lateral surface (S) due to the rotational movement of the drum around the axis of rotation (X) between the first and second stop positions. By way of example, the first portion of the first end of the cable has a length at least equal to two complete turns of the surface (S), preferably greater than two and a half turns. The first portion of the first end is advantageously long enough to cancel the tension of the cable at the end of said cable by a so-called capstan effect.The capstan effect, known in itself, establishes the relationship between a holding force applied to one end of a cable wound around the lateral surface of a block, for example a block with a circular cross-section or a block with a non-circular cross-section (for example an elliptical cross-section), and a load force applied to an opposite end of said cable, which depends on the coefficient of friction of the cable on the lateral surface of the block.

[0051] The anchoring system according to the invention further comprises at least one torsion spring arranged between the drum and the frame. When a sudden tension on the cable on the drum causes the drum to rotate about said axis of rotation (X) in the direction of the cable winding or unwinding (where the sudden tension on the cable is understood as a change in mechanical tension relative to the equilibrium tension that keeps the cable taut), the torsion spring is configured to generate a restoring force on said drum that tends to compensate for said change in tension. Thus, through the drum, the torsion spring limits the tension in the cable and keeps the cable taut, thereby preventing damage to the cable. Preferably, the torsion spring or the set of torsion springs generates all the restoring forces on the drum.Alternatively, the anchoring system may further include a compression spring and / or a tension spring, such that said compression spring and / or said tension spring generate at least part of the restoring forces on the drum.

[0052] More specifically, under the effect of the mechanical tension of the cable and the resulting rotation of the drum around the axis of rotation (X), each torsion spring deforms, generating a torsion angle and therefore a restoring force on the drum proportional to said torsion angle, which tends to cancel out said torsion angle and return the drum to its initial position. In the direction of cable winding, the torsion spring can deform until it reaches a The first limiting torsion angle. In the direction of cable unwinding, the torsion spring can deform until it reaches a second limiting torsion angle. In one variant, the first and second limiting torsion angles correspond respectively to a first and second stop position of the drum rotating about the axis of rotation (X). In other words, the rotation of the drum about the axis of rotation (X) is blocked in one direction by the torsion spring when the torsion spring has reached the first limiting torsion angle, and the rotation of the drum is blocked in the other direction when the torsion spring has reached the second limiting torsion angle.In a preferred embodiment, the first and second stop positions are reached by the drum rotating about the axis of rotation (X) slightly before the torsion spring reaches its first and second limiting angles of torsion. This embodiment advantageously prevents premature wear of the torsion spring. In practice, the first and second stop positions can be fixed by external mechanical stops, for example, progressive rubber stops well known to those skilled in the art, which absorb the shock when the drum reaches its stop position. Typically, the first - respectively second - stop position and the first - respectively second - limiting torsion angle are angularly offset by about 4°.

[0053] The arrangement of the torsion spring(s) between the drum and the frame can be designed so that each torsion spring is in the middle of its deformation range when the drum is in the neutral position. This allows for equivalent travel in the direction of cable winding and in the direction of cable unwinding.

[0054] By way of example, if the first and second stop positions are angularly offset from the axis of rotation (X) by an angle of 90°, the midpoint of the deformation range of each torsion spring is preferably associated with a drum position of 45°. By way of further example, if the first and second stop positions are angularly offset from the axis of rotation (X) by an angle of 60°, the midpoint of the deformation range of each torsion spring is preferably associated with a drum position of 30°.

[0055] A torsion spring advantageously has a smaller footprint than the conventionally used compression spring (see [Fig. 5] with the compression spring 8 comprising a first part fixed to the frame and a second part fixed to the drum), particularly when the torsion spring is arranged along the axis of rotation (X). Indeed, a compression spring has a limited extension or compression length: increasing the travel available to the cable Therefore, maintaining a fixed distance between the compression spring and the axis of rotation (X) requires either increasing the length of the compression spring and thus its size, or moving the spring closer to the axis of rotation (X). In the latter case, however, the compression spring must be able to withstand a very high force to counterbalance that of the cable. Indeed, the cable tension can be on the order of 2000 N along the cable axis, and the tension on the spring, potentially even greater, is all the greater the closer the spring is to the axis of rotation. In order to withstand such a force, the compression spring must therefore have a greater wire thickness, which also significantly increases its length and therefore its size, and also poses manufacturing challenges for the compression spring.

[0056] In addition, the compression spring, like any spring, should preferably be used in its linearity zone without reaching its stop positions in order not to excessively reduce the life of said spring, which requires increasing the length of said compression spring even further.

[0057] By way of example, consider a conventional anchoring system comprising a compression spring with a free length of 240 mm and an extension amplitude of 86 mm, in which the position of the compression spring is such that it must pivot slightly at each end to follow the movement of the drum, but where the ratio between the spring stroke and the cable stroke remains approximately 1:1. Such a cable anchoring system therefore provides a cable travel of approximately 86 mm. To increase the cable travel to 630 mm without changing the position of the compression spring, it would therefore be necessary to replace the 240 mm long compression spring with a compression spring of (240 x 630) / 86 mm, or approximately 1.9 m.

[0058] Alternatively, if one wanted to maintain an actual spring length of 240 mm while providing a cable travel of 630 mm, the compression spring would have to be positioned approximately 7 to 8 times closer to the axis of rotation, which would multiply the stresses experienced by the compression spring proportionally. In such a configuration, the compression spring would necessarily need to have a much larger wire diameter, and therefore ultimately a spring length probably greater than the desired 240 mm. A compression spring with such characteristics is either impossible or extremely difficult to manufacture. Furthermore, all the compression spring's fastening elements subjected to these significant stresses would also have to be dimensioned to withstand said significant stresses, which would drastically increase the cost of the overall anchoring system. Finally, the risk of failure of such an anchoring system would be very high.

[0059] The force exerted on the torsion spring directly generates an angle of rotation, and increasing the cable's travel is equivalent to increasing this angle of rotation, which has no effect on the overall dimensions. Furthermore, the torsion spring can easily be positioned along the axis of rotation (X) inside the drum, resulting in minimal space requirements.

[0060] As previously mentioned, the stresses to which the compression spring, or at least one torsion spring, on the anchoring system are subjected are significant. To prevent the service life of a compression spring used under such conditions from being excessively reduced, it is necessary to use said compression spring only within its operating range and to increase the wire diameter of said compression spring. Thus, a compromise must be made between the size of the compression spring and its service life. In contrast, the torsion spring of the anchoring system according to the invention operates precisely under the conditions for which it was designed, namely alternating torsion, so that an anchoring system comprising such a torsion spring can achieve longer service lives.

[0061] More specifically, in a first embodiment, the anchoring system comprises a torsion spring arranged along the axis of rotation (X). A first part of said torsion spring is mounted on the chassis and a second part of said torsion spring is mounted on the drum, the second part being adapted to pivot relative to the first part.

[0062] Thus arranged, the first and second stop positions can correspond to the extreme pivoting positions of the second part of the torsion spring relative to the first part. According to a preferred alternative, the first and second stop positions are located between the extreme pivoting positions of the second part of the spring relative to the first part (for example, by means of external mechanical stops as previously mentioned). Advantageously, not rotating the drum to its extreme positions avoids unnecessarily reducing the service life of the torsion spring.

[0063] In a second embodiment of the anchoring system according to the invention, the cable anchoring system comprises at least two torsion springs mounted in series and arranged along the axis of rotation (X). In the variant where the anchoring system comprises two torsion springs mounted in series, a first portion of a first torsion spring may be mounted on the frame, a first portion of a second torsion spring may be mounted on the drum, and a second portion of the first torsion spring may be rigidly connected to a second portion of the second torsion spring, the first portion of the first torsion spring—respectively, of the second torsion spring - being adapted to pivot relative to the second part of the first torsion spring - respectively of the second torsion spring.

[0064] For a given lateral surface (S), the arrangement of two torsion springs in series advantageously doubles the angle between the first and second stop positions relative to the axis of rotation (X), and thus increases the length measured in the plane (P) of the portion of the lateral surface (S) along which the cable is wound and / or unwound. In other words, this increases the cable's travel. Thus, if the angle between the first and second stop positions relative to the axis of rotation (X) with a torsion spring is between 0° and 30°, connecting two torsion springs in series advantageously increases the angle between the first and second stop positions to between 0° and 60°.

[0065] In other embodiments, the anchoring system comprises at least three torsion springs mounted in series, so as to further increase the angle between the first and second stop positions, and thus the travel available to the cable. However, in such embodiments, at least one torsion spring in the series arrangement—referred to as the central torsion spring—is not fixed to either the drum or the frame, so that the torsion springs and connecting parts on either side of said central spring must bear the load on said central torsion spring and withstand the forces generated by said central torsion spring. The embodiment with only two torsion springs in series is therefore the preferred embodiment.

[0066] By way of example, a travel angle between the first and second stop positions of between 0° and 60° allows a portion of length between 0 and approximately 630 mm, measured in plane (P), to be swept when the radius of curvature of the portion of the lateral surface (S) measures 575 mm, the cable diameter is 50 mm, and the distance measured in plane (P) between the cable and the line in plane (P) parallel to said cable that intersects the axis of rotation (X) is advantageously equal to the radius of curvature of said portion of the lateral surface (S). Indeed, the arc length of the portion of cable 1 can be calculated as follows: r00671 / 2xt575r25)xnx60 lvvu / ji _ ----__----- 628.32 mm 630 mm

[0068] Such a length allows the cable to have a travel of approximately 300 mm in the direction of cable winding and 300 mm in the direction of cable unwinding. The inventors consider this travel to be the ideal travel for the cable from the neutral position. Indeed, the ideal travel for keeping the cable taut and preventing damage is equal to the product of the maximum speed of the gripping frame and the reaction time of the feedback loop of the electronically controlled reel. The maximum linear speed Given that the speed given by the motors to the gripping frame is typically between 150 m / min (2.5 m / s) and 240 m / min (4 m / s), and that the reaction time of the electronically controlled reel is approximately 75 ms, the ideal travel from the neutral position is indeed around 300 mm in both the unwinding and winding directions of the cable on the drum. Arranging two or more torsion springs in series advantageously provides the cable with such travel while minimizing its overall size. As mentioned previously, such a length of travel is not reasonably achievable with a compression spring.

[0069] Each torsion spring may comprise a metal spring arranged along the axis (X). For example, and as shown in [Fig. 8], the cable anchoring system comprises a single metal torsion spring 10, a first coil 11b of one end of said metal spring being rigidly connected to the frame 2 and a second coil 11b of a second end of said spring being rigidly connected to the drum 1. In this configuration, the anchoring system may further comprise a shaft 12 rigidly connected to the frame 2 and oriented along the axis of rotation (X), and a bearing (not shown) rigidly connected to the drum 1. In this way, the bearing and the shaft 12 provide rotational guidance of the drum 1 relative to the frame 2 along the axis of rotation (X). Alternatively, the shaft may be rigidly connected to the drum and the bearing rigidly connected to the frame. The shaft 12 is, for example, arranged inside the coils of the metal torsion spring 10.Preferably, the anchoring system of [Fig.8] further includes at least one shock absorber (not shown), for example a hydraulic, pneumatic, metallic or elastic shock absorber (tensioners), which allows shocks to be absorbed.

[0070] The first and second stop positions of the drum can be fixed respectively by the first and second limiting torsion angles of the metal torsion spring 10 (permanent deformation of said spring). Alternatively, the diameter of the shaft 12 can be judiciously chosen so that the first and second stop positions correspond to the torsion angles of the torsion spring 10 at which said torsion spring is "blocked" by the shaft 12. In a preferred embodiment, the cable anchoring system further comprises at least two mechanical stops that block the rotation of the drum before the single metal spring 10 reaches the first and second limiting torsion angles.Each mechanical stop includes, for example, a first part attached to the chassis and a second part attached to the drum: when the drum rotates around the axis of rotation (X), the second part of the mechanical stop comes to block against the first part of the mechanical stop, thus stopping the rotation of the drum in a position of . stop. Preferably, at least one mechanical stop is a progressive rubber stop well known to those skilled in the art.

[0071] Alternatively and advantageously, each torsion spring may comprise a rigid, hollow outer shaft, a rigid central shaft housed inside the rigid, hollow outer shaft, and a damper configured to dampen a torsional movement of the rigid, hollow outer shaft relative to the rigid central shaft. On the anchoring system, the rigid central shaft and the rigid, hollow outer shaft are oriented along the axis of rotation (X).

[0072] In the particular configuration where the anchoring system comprises a single torsion spring including a rigid, hollow outer shaft, a rigid central shaft housed inside the rigid, hollow outer shaft, and a damper as previously described, the rigid central shaft can be mounted on the drum and the rigid, hollow outer shaft can be mounted on the frame, such that the torsion / pivoting of the rigid, hollow outer shaft relative to the rigid central shaft about the axis of rotation (X) ensures the rotational guidance of the drum relative to the frame about the same axis. In other words, the torsion spring in this configuration plays the dual role of bearing to guide the rotational movement of the drum relative to the frame and of damper of the forces generated by said movement. Alternatively, the rigid central shaft can be mounted on the frame and the rigid, hollow outer shaft can be mounted on the drum.

[0073] Such a torsion spring, comprising a rigid central shaft housed inside a rigid, hollow external shaft, advantageously eliminates the need for other means of rotating the drum relative to the frame, such as roller bearings or bushings (see [Fig. 5], in which roller bearings 9 are used in conjunction with the compression spring 8, the roller bearings 9 enabling the drum to rotate around the axis of rotation (X), and the compression spring damping this movement). Indeed, such roller bearings or bushings are not suitable for the operating conditions of the anchoring system mounted on a gripping frame (continuous operation at a limited angle of rotation without ever completing full revolutions, and frequent vibrations) and wear out rapidly, thus limiting the service life of the anchoring system.Alternatively, the choice can be made to oversize the bearings—in other words, to use larger bearings with larger balls—so that these bearings can withstand the high static loads to which they are subjected on the operating anchoring system, due to working within a limited angle of rotation, without excessively reducing the service life of the anchoring system. However, such oversized bearings are more expensive and bulkier. Conversely, the... Torsion springs, classically used in vibration pads, are perfectly suited to such conditions of use.

[0074] Preferably, the torsion spring damper comprises a plurality of elastomer elements arranged between the rigid central axis and the rigid external axis, for example four elastomer elements.

[0075] An elastomer is an elastic polymer material. Natural or synthetic rubber and neoprene are examples of elastomers within the meaning of the present invention.

[0076] Torsion springs incorporating elastomer elements offer several advantages over metal springs. For example, torsion springs incorporating elastomer elements have been specifically designed to withstand and absorb the continuous vibrations and shocks that are the typical conditions encountered by the spring when mounted on the frame during use on a lifting device. In comparison, steel springs, under the same conditions of continuous vibration and shock, quickly show their limitations: continuous stress induces cracks much more rapidly in metal springs than in elastomer elements. Thus, torsion springs incorporating elastomer elements wear out less quickly than steel springs.

[0077] Furthermore, elastomer elements exhibit very low susceptibility to corrosion. Thus, springs incorporating elastomer elements require very little maintenance and their service life is not reduced even when used in corrosive environments, such as by the sea. In comparison, metal springs, particularly compression springs, are much more susceptible to corrosion, and paint treatments are insufficient to satisfactorily improve corrosion resistance: an impact, a nick, or poor paint adhesion can be enough to initiate corrosion and cracking of the metal.Other known physico-chemical processes aimed at increasing corrosion resistance, particularly those involving heating, are prohibited so as not to impair the material's characteristics, especially its ability to withstand regular deformations in compression or elongation.

[0078] It is possible to dimension such a torsion spring with elastomer elements, in particular by choosing the material and dimensions of the elastomer elements, so as to obtain the desired angle between the first and second stop positions, for example 30° or even 45°, and so that said torsion spring is able to withstand the forces to which it will be subjected in use on the lifting equipment without impacting the overall size of said torsion spring on the chassis and without compromising the manufacturability of said torsion spring. In the case of the compression spring, Increasing the resistance of the compression spring implies increasing the diameter of the compression spring wire and therefore its size as well as its manufacturing difficulty.

[0079] Finally, unlike a metal spring, a torsion spring incorporating elastomer elements is more resistant to overload than a metal spring, and the failure of an elastomer element allows continued operation in a degraded mode, whereas the breakage of the metal spring in a torsion or compression spring, which is a single component, immediately shuts down the system. Operation in degraded mode allows continued operation, possibly at reduced speed, while the replacement of the faulty part is arranged.

[0080] Each elastomer element acts not only as a spring, generating a restoring force proportional to the angle of torsion that compensates for variations in the cable's stress, but also as a damper, generating a dissipative force proportional to the speed of the torsional movement, thus preventing the cable from reaching the stops at full speed. Therefore, unlike compression springs and metallic torsion springs, torsion springs incorporating such elastomer elements advantageously eliminate the need for additional dampers such as hydraulic, pneumatic, metallic, or elastic shock absorbers (tensioners).

[0081] More specifically, with reference to [Fig. 6], each torsion spring 10 may comprise a first hollow, square-based metallic prism 11, a second hollow, square-based metallic prism 12 housed inside the first prism 11 with an angular offset from the first prism 11 forming the central axis, and each elastomer element may be an elastomer cylinder 13 arranged between the first prism 11 and the second prism 12, in each corner of the first prism. In this case, the first prism 11 may be rigidly connected to the frame—reciprocally to the drum—and the second prism 12 to the drum—reciprocally to the frame. Such a torsion spring configuration comprising a second prism housed inside a first prism and an elastomer element in each corner of the first prism advantageously allows a large angle of movement, on the order of 30° per torsion spring.

[0082] In the particular configuration in which two torsion springs are mounted in series, the second internal prism 12 of the first torsion spring can be connected to the second internal prism 12 of the second torsion spring. The first external prisms 11 of the first and second torsion springs can, for their part, be connected to the drum and the chassis, respectively. Such a configuration of the first prisms 11 and second prisms 12 is particularly advantageous, since each first prism 11 can be very easily attached to the drum, or to the chassis, respectively, for example by means of a bracket and two assemblies comprising bolts or rivets or welding. In addition, the second 12 prisms can be easily connected by techniques known to those skilled in the art, for example by means of a square-based shaft and two axial stops.

[0083] Alternatively, the first prism 11 of the first torsion spring can be connected to the first prism 11 of the second torsion spring and the second prism 12 of the first torsion spring and the second prism 12 of the second torsion spring can be connected respectively to the drum and the chassis.

[0084] Alternatively, the first prism 11 of the first torsion spring can be connected to the chassis, respectively to the drum, and the second prism 12 of the second torsion spring can be connected to the drum, respectively to the chassis, the second prism 12 of the first torsion spring being connected to the first prism 11 of the second torsion spring.

[0085] The torsion springs that both guide the rotation of the drum around the axis of rotation (X) and compensate for variations in cable tension are not limiting the scope of the invention. The invention extends to any anchoring system comprising a torsion spring configured to guide the rotation of the drum and compensate for variations in cable tension.

[0086] In addition to the embodiments of the cable anchoring system described above, each spring may comprise two sets of springs mounted in parallel, a first portion of the first set of springs and the second set of springs being connected to the frame and a second portion of the first set of springs and the second set of springs being connected to the drum, each of the first and second sets of springs being able to be understood as a single spring or as at least two springs mounted in series. For the same angle of rotation of the drum around the axis (X), the parallel mounting advantageously allows the spring force to be doubled. Furthermore, the parallel mounting allows the forces acting on the frame to be distributed on both sides of the drum and thus minimizes the shear forces on the springs.

[0087] By way of example, Figures 7A to 7D represent the particular configuration in which the spring comprises a first set of springs consisting of a first torsion spring 10a mounted in series with a second torsion spring 10b and a second set consisting of a third torsion spring 10c mounted in series with a fourth torsion spring 10d, the first and second sets of springs being mounted in parallel with each other. Furthermore, the four springs are arranged along the axis of rotation (X). In particular, [Fig. 7B] represents the configuration in which the drum is in the neutral position. [Fig. 7C] represents the case of cable undertension. [Fig. 7D] represents the case of cable overtension.

[0088] In [Fig. 7A], such a torsion spring configuration is shown in combination with a particular embodiment of the drum in which said drum has an elliptical shape in plane (P) and the axis of rotation (X) intersects said plane (P) at the center of the circle tangent to the winding and / or unwinding portion of the cable, with a radius equal to the radius of curvature of said portion. However, any combination of torsion springs with a drum having any other shape remains within the scope of the invention.

[0089] As previously mentioned, the first stop position and the second stop position may correspond to the limiting torsion angles of the torsion spring or the assembly of torsion springs. Alternatively, the first stop position and the second stop position may be slightly offset so as never to reach the limiting torsion angles of the torsion springs, for example by means of mechanical rubber stops as previously described.

[0090] The invention also relates to a lifting device comprising: - a gripping frame, - an anchoring system comprising a frame and a drum as previously described, the frame being fixed to the gripping frame and the drum to the frame, - a reel adapted to be fixed to the lifting equipment, - a cable, one end of the cable being anchored to the drum of the anchoring system by fixed winding of at least two turns around the lateral surface of the drum and a second end of the cable being wound around the reel.

[0091] Finally, the invention relates to a lifting device comprising a lifting mechanism as described above. According to a particular embodiment of the invention, the lifting device is a crane, a gantry crane, or a forklift truck. The lifting device is, for example, a crane used for loading or unloading containers onto a container ship.

[0092] According to a particular embodiment of the lifting device, said lifting device comprises, in addition to the lifting device as previously described, a second gripping frame and an intermediate platform. For example, the lifting device is an STS crane and the gripping frame of the lifting device is used to move a container between the ship and the intermediate platform, while the second gripping frame is used to move said container between the platform and the quay.

[0093] In a particular embodiment of the lifting device with two gripping frames, the second gripping frame is included in a second lifting device, said second lifting device being able to be made according to any of the lifting device embodiments previously described.

[0094] Alternatively, the lifting device does not include a second reel, so the second gripping frame is not supplied by a cable connected to a reel. For example, the second gripping frame is supplied by a second cable that is deposited in a basket.

Claims

Demands

1. A cable anchoring system (3) comprising: - a frame (2), - a drum (1) rotatably mounted on the frame about an axis of rotation (X), the drum having a lateral surface (S) about an axis (Y) parallel to the axis of rotation (X), the drum being adapted to allow cable movement by winding and / or unwinding said cable along a portion of the lateral surface, by rotation of said drum about the axis of rotation (X) in response to a variation in the mechanical tension of the cable, - at least two torsion springs (10, 10a, 10b, 10c, 10d) arranged between the drum and the frame so as to compensate for the variation in the tension of the cable, the two torsion springs being arranged in series.

2. Cable anchoring system according to the preceding claim, wherein a first part of a first spring is mounted on the chassis, a first part of a second spring is mounted on the drum, and a second part of the first spring is rigidly linked to a second part of the second spring.

3. Cable anchoring system according to any one of claims 1 to 2, wherein each torsion spring (10) comprises a rigid hollow outer shaft (11), a rigid central shaft (12) housed inside the outer shaft (11), and a damper configured to dampen a torsional movement of the rigid hollow outer shaft relative to the rigid central shaft.

4. Cable anchoring system according to the preceding claim, wherein the torsion spring damper comprises a plurality of elastomer elements (13) arranged between the rigid central axis (12) and the rigid hollow external axis (11).

5. A cable anchoring system according to the preceding claim, wherein each torsion spring comprises a first hollow, metallic, square-based prism forming the rigid, hollow outer axis, a second prism forming the central axis arranged in the first prism with an angular offset from the first prism, and wherein each elastomer element is a cylinder arranged between the first prism and the second prism, in each corner of the first prism.

6. Cable anchoring system according to the preceding claim, comprising two torsion springs in series, the second square-based prism of the first torsion spring being connected to the second square-based prism of the second torsion spring.

7. A cable anchoring system according to any one of the preceding claims, wherein at least one torsion spring is configured to dampen the forces generated by the rotation of the drum about the axis of rotation (X) between a first stop position of the drum and a second stop position of the drum, the first stop position and the second stop position being angularly offset from the axis of rotation (X) by an angle between 0° and 90°, preferably between 0° and 60°.

8. Cable anchoring system according to any one of the preceding claims, comprising at least two sets of torsion springs arranged in parallel, a first part of each set of torsion springs being mounted on the chassis and a second part of each set of torsion springs being mounted on the drum.

9. Cable anchoring system according to any one of the preceding claims further comprising a compression spring and / or a tension spring comprising a first part mounted on the chassis and a second part mounted on the drum.

10. Lifting device comprising: - a gripping frame (4) including at least one attachment member for a load to be lifted, - a cable anchoring system according to any one of the preceding claims comprising a chassis (2) and a drum (1), the chassis being fixed to the gripping frame and the drum being fixed to the chassis, - a reel adapted to be fixed to a lifting device, - a cable (3), a first end of the cable being anchored to the drum (1) of the anchoring system by fixed winding of at least two turns around the lateral surface of the drum and a second end of the cable being wound around the reel.

11. Lifting equipment (6), such as a crane, gantry crane or forklift, comprising a lifting device according to claim 10.

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