Extendable lattice boom crane and method for operating a crane including an extendable boom

Abstract

An extendable lattice boom (2) for a crane (1), the boom comprising a lattice base boom section (2a) and at least one lattice telescopic boom section (2b), wherein at least one telescopic boom section is adjustable relative to the base boom section between a retracted position and an extended position, in the retracted position the telescopic boom section being substantially inside the base boom section, and in the extended position the telescopic boom section being at least partially outside the base boom section, wherein a first guiding system (21) is mounted to the distal end of the base boom section, the guiding system being configured to guide the telescopic boom section along the base boom section; and wherein the proximal end of the telescopic boom section comprises a second guiding system (30), the second guiding system being configured to guide the telescopic boom section along the base boom section.

Description

Technical Field

[0001] The present invention relates to an extendable lattice boom for a crane. In many construction and maintenance fields, there is a need for larger cranes that can lift loads to increasingly greater heights. This requires the use of longer booms or extension arms attached to the boom, such as jibs. Increasing the length of the boom will inevitably pose an obstacle to the transportation of the crane. Background Art

[0002] Cranes with telescopic booms have been developed to achieve relatively large lifting heights while being able to quickly retract the boom to a transportable size. Such telescopic booms typically have two or more sections of decreasing size, with the larger sections surrounding the insertion sections of the smaller sections. The load on the boom (such as the weight of the boom and the hook load) will cause bending or tipping moments in the boom and between the sections, and the load on the boom will cause large forces to be transmitted through the guides between the telescopic sections, thus requiring significant material strength at the guides.

[0003] Generally speaking, longer booms require heavier structures in order to not only withstand the increased forces and bending moments caused by the hook load within a large outreach of the crane, but also support their own increased weight. When increasing the length of a conventional tubular telescopic boom, taking into account the material strength required for the position of the guides, such a tubular boom may become too heavy for certain applications (such as offshore applications).

[0004] Compared with tubular booms, the application of lattice booms can significantly reduce the weight of the boom. Telescopic booms with lattice sections are known, but extending the sections can be quite time-consuming. There are still difficulties in the stable guidance of the telescopic boom sections and the load transfer between the sections.

[0005] In the field of wind turbine installation, it is expected that in the near future, the lifting height required to install turbines on the top of towers will increase to 140 m to 160 m, or higher. For the ground installation of wind turbines, conventional mobile cranes with telescopic booms are usually used, and such a lifting height will require the largest available conventional mobile telescopic crane with additional lattice jibs and a luffing system.

[0006] For the offshore installation of wind turbines, a jack-up platform carrying a lattice boom type crane with a jib sling is typically used. The expected lift height for future installations exceeds the current capacity of the cranes available on existing installation jack-up platforms. If the lattice boom of such a lattice boom type crane is extended by additional sections, the longer boom will protrude from its original boom bracket in the transport position, and the crane block will not fit its original support. This can result in an increased bending moment in the boom during transportation. The protruding boom may no longer fit within the footprint of the jack-up platform and may project outside of it, which can lead to stability issues during platform transportation and / or may result in an increased bending moment in the boom. If adverse weather is encountered during transportation, the protruding boom may also come into contact with water. Additionally, the protruding boom can also cause coordination problems with the platform itself, such as the boom blocking the helideck.

[0007] A telescopic boom can partially address the above problems. However, the larger the extendable lattice boom type crane, the more time is spent on hoisting and extending the crane, and this time is wasted on crane operations, resulting in increased costs. Summary of the Invention

[0008] The object of the present invention is to solve or mitigate one or more of the above problems. In particular, the present invention aims to provide an improved extendable lattice type crane boom that allows the crane boom to be placed relatively quickly in a safe and stable manner.

[0009] For this purpose, according to a first aspect of the present invention, there is provided a telescopic lattice boom crane boom characterized by the features of claim 1. Specifically, there is provided a telescopic lattice boom crane boom for a crane, the boom comprising a lattice base boom section and at least one lattice telescopic boom section. The at least one telescopic boom section is adjustable relative to the base boom section between a retracted position and an extended position, in the retracted position the telescopic boom section being substantially inside the base boom section, and in the extended position the telescopic boom section being at least partially outside the base boom section. The distal end of the base boom section may include a first collar, to which a first guiding system is mounted, the guiding system being configured to guide the telescopic boom section along the base boom section. The guiding system may for example include a guide rail and a guiding element configured to be guided along the guide rail. The proximal end of the telescopic boom section includes a second guiding system, the second guiding system being configured to guide the telescopic boom section along the base boom section. In a creative manner, the base boom section includes a third guiding system, the third guiding system being configured to guide the telescopic boom section along the base boom section, the third guiding system being spaced apart from the first guiding section by a distance corresponding to the length of the part of the telescopic boom section that remains inside the base boom section in the extended position of the telescopic boom section. The third guiding system can increase stability during the extension and lifting of the crane boom. During the extension of the telescopic boom section from the retracted position to the extended position, the telescopic boom section can first be supported and guided by the first guiding system and the second guiding system, while the third guiding system hardly bears any load. Then, the third guiding system can take over the guiding of the second system, such that the telescopic boom section can be supported by the first guiding system and the third guiding system, while the second guiding system no longer bears the load. Thanks to the third guiding system, the crane boom can be extended and lifted in a relatively fast manner while maintaining relative stability throughout the operation. The guiding system may include a guide rail and a guiding element configured to be guided along the guide rail, wherein the guide rail is provided on one of the base boom section and the telescopic boom section, and the guiding element is provided on the other of the base boom section and the telescopic boom section. Thus, the guiding system includes cooperating parts (i.e., the guiding element and the guide rail), the cooperating parts being provided on cooperating sections (i.e., the base boom section or the telescopic boom section) such that the guiding element can be guided along the guide rail. For example, the first guiding system may include a guiding element provided on the base boom section and a guide rail provided on the telescopic boom section, wherein the guiding element of the first guiding system is mounted to the base boom section at the position of the first collar. The guiding element may be a roller, a slider or a guide, or may be embodied in other ways. The positions of the guiding element and the guide rail may also be reversed, since the guide rail may be provided at the base boom section and the guiding element of the first guiding system may be provided at the telescopic boom section. Advantageously, a collar is provided on the section to which the guiding element is mounted.Thus, when the guiding element is mounted to the base boom section, the base boom section is provided with a first collar at least at the axial position where the guiding element is mounted. The second guiding system further includes a guiding element on one of the base boom section and the telescopic boom section, and a cooperating guide rail on the other of the base boom section and the telescopic boom section. Similarly, the third guiding system includes a guiding element on one of the base boom section and the telescopic boom section, and a cooperating guide rail on the other of the base boom section and the telescopic boom section. The third guiding system is arranged on the base boom section at a certain distance from the first guiding system. Thus, the third guiding system on the base boom section can be provided with guiding elements that cooperate with the corresponding guide rails on the telescopic boom section, or vice versa. Advantageously, a second collar can be provided at the position of the guiding element to strengthen the section where the guiding element is mounted. The first guiding system and the third guiding system are mounted to the same section of the telescopic crane: the base boom section or the telescopic boom section, advantageously mounted to the base boom section. In one example, the second guiding system is mounted to the same one of the base boom section and the telescopic boom section as the first guiding system and the third guiding system are mounted to. In another example, the second guiding system is mounted to a different one of the base boom section and the telescopic boom section from the one where the first guiding system and the third guiding system are mounted to.

[0010] The base boom section may preferably include a second collar to which the third guiding system is mounted. The second collar can strengthen the base boom section to transfer the load from the third guiding system to the base boom section.

[0011] The first guiding system and / or the third guiding system may include guiding elements at all four chords of the corresponding base boom section or telescopic boom section where the guiding element is mounted. The guiding element can be a roller, or an x-y guiding element, or a radial guiding element, or a guiding slider, etc. The guiding elements of the first guiding system are mounted at the same axial position along the base boom section or the telescopic boom section. The guiding elements of the third guiding system are also mounted at the same axial position along the base boom section or the telescopic boom section. By providing guiding elements on all the chords of the base boom at the first collar and the second collar, a firm, stable and reliable connection can be obtained between the base boom and the telescopic boom. Such a connection can also facilitate an easier extending and lifting process, where the extending and lifting can be partially carried out simultaneously. The second guiding system may include guiding elements only at the lower chord of the telescopic boom section. Alternatively, the second guiding system may include guiding elements at the lower chord and the upper chord of the telescopic boom section (or vice versa for the base boom section).

[0012] The collar can be provided at the axial position of the guiding element for mounting the first guiding system and / or the third guiding system. The collar can include at least two bracket connections at the chord at the axial position of the guiding system. Thus, the collar can include two brackets connecting two pairs of opposite brackets. Optionally, the collar can include four brackets connecting four chords at the axial position of the guiding system. In one example, a collar can be provided to reinforce the base boom section.

[0013] The second guiding system can advantageously include at least one track mounted to at least one chord of the base boom section, wherein the length of the track is substantially shorter than the length of the part of the telescopic boom section configured to extend from the base boom section in the extended position of the telescopic boom section. For example, when the telescopic boom is approximately in the middle between the retracted position and the fully extended position, the relatively short guide rail length can allow the guiding of the telescopic boom section to be transferred from the second guiding system to the third guiding system.

[0014] Preferably, the first guiding system is an x-y guiding system. The x-y guiding system can include substantially simultaneous guiding in two substantially transverse directions, for example including a first guiding roller configured to guide the telescopic boom section along a first direction x along the base boom section, and including a second guiding roller configured to guide the telescopic boom section along a second direction y along the base boom section, the second direction being substantially transverse to the first direction x. The two directions are preferably substantially transverse to the longitudinal axis of the crane boom.

[0015] Preferably, the third guiding system is an x-y guiding system, which can allow relatively stable guiding of the telescopic boom section, especially in the extended position and / or at a relatively high boom angle, especially since the x-y guiding system can prevent rotation about the longitudinal axis, which is not the case for a radial guiding system.

[0016] More preferably, the first guiding system and / or the third guiding system can include at least one track mounted to or integrated into at least one chord of the telescopic boom section, the track being shaped such that it guides both the x guiding roller and the y guiding roller of the x-y guiding system. For example, the guide rail can have a substantially rectangular cross-section such that two adjacent guide rail sides can guide the x guiding roller along the first side of the guide rail and guide the y guiding roller along the second side adjacent to the first side.

[0017] The telescopic boom section can preferably include chords having a substantially rectangular cross-section. Tracks (e.g., the guide rails of the first guiding system or the third guiding system) can be relatively easily mounted to such substantially rectangular chords. Optionally, the chords can have a substantially circular cross-section.

[0018] The base boom section may preferably include chord members having a substantially circular cross-section, which are relatively easy to manufacture.

[0019] Advantageously, the second guiding system may be a radial guiding system provided on the chord members of the base boom section and / or the telescopic boom section, substantially at 45° with respect to the upper or lower side of the boom. The radial guiding system may for example include at least one, preferably two guiding rollers, which are connected to the chord member on the lower side of the telescopic boom section at a substantially horizontal position of the boom. At least one radial guiding roller is configured to roll or slide in contact with the chord member on the lower side of the base boom section at an angle of approximately 45°. The chord member may be provided with tracks to guide the rolling or sliding contact of the guiding rollers on the chord member. Other configurations of the radial guiding system are also possible.

[0020] The lower side of the extensible boom is the side that turns downwards when the extensible boom is retracted and in the transport position. When the extensible boom enters the working position as part of a crane, with the extensible boom substantially upright but still slightly inclined, the lower side is also the side on which a load can be lifted.

[0021] The extensible lattice boom crane boom may further include a locking system configured to lock at least one telescopic boom section relative to the boom section in at least the extended position, such that boom loads can be transferred through the chord members. Such a locking system can provide a firm locking of the extensible boom in at least the extended position and can be relatively easy and quick in operation. The telescopic boom section can be locked relative to the base boom section in at least the extended position. However, locking in the retracted position and / or intermediate positions is also possible. As an alternative to locking the telescopic boom section in the retracted position, a stop element may be provided against which the telescopic boom section can abut in order to place the telescopic boom section in the retracted position. In order to be able to lock in these positions, the telescopic boom section may for example be provided with a plurality of apertures arranged to receive locking pins from the locking system. The apertures of the telescopic boom section are preferably provided at predetermined positions on its chord members such that they can receive the locking pins in the desired positions of the telescopic boom section.

[0022] The locking system may preferably include a plurality of pins, each pin being configured to at least partially protrude through a respective pin receiving hole in at least the extended position of the boom, the pin receiving holes being provided in one of the first collar and the telescopic boom section, wherein the pin receiving holes are dimensioned at least 10 mm larger than the cross-sectional dimension of the respective pin. The pin receiving holes can have various forms, such as substantially circular holes, or slotted holes, or oval-shaped holes, or any other variant of holes, wherein in at least one radial direction, the hole is dimensioned at least 10 mm, preferably 20 mm, more preferably at least 30 mm larger than the cross-section of the respective pin, so as to provide sufficient play or clearance in the connection to ensure relatively easy insertion or detachment of the pin. Additional dimensions can be provided in one direction, such as creating a slotted hole or an elliptical hole or an oval-shaped hole, or additional dimensions can be provided in a plurality of radial directions relative to the cross-section of the pin, or additional dimensions can be provided in all radial directions of the hole, thereby creating an enlarged hole relative to the cross-sectional dimension of the pin.

[0023] The locking system may include a support structure at the distal end of the base boom section, on which a support structure locking pin is mounted and extends from the support structure towards the chord of the telescopic boom section. When the telescopic boom section is in the extended position, the locking pin is placed in alignment with the pin receiving holes in the chord of the telescopic boom section. The telescopic boom section is preferably provided with pin receiving holes which are arranged in or integrated within the chord and are configured to receive the locking pins. The locking pins can, for example, be engaged with a hydraulic or electric actuating device. The locking pins can be engaged in the retracted and / or extended and / or intermediate positions of the telescopic boom section relative to the base boom section. When the locking pins are engaged, the guides of the first guiding system and the third guiding system remain in contact with their respective guide rails. Thus, the axial boom load can be directly transferred via the chord through the locking pins. When the pins are engaged, shear or lateral loads can be transferred through the guides of the guiding system. When the locking pins are engaged, the telescopic system no longer needs to be actuated, so the axial load transfer is mainly accomplished via these locking pins through the chord, rather than via the guides and / or via the telescopic system. Basically, the guides of the first guiding system and the third guiding system and / or the telescopic system are not subjected to the axial boom load in the extended position, but will still be subjected to lateral loads.

[0024] Optionally, the support structure can be provided at the proximal end of the telescopic boom section, wherein the telescopic boom section has a locking pin connected thereto and extending therefrom towards the chord of the base boom section, or before the telescopic boom section. Optionally, the support structure can be provided at the distal end of the base boom section, the base boom section having a locking pin connected to the telescopic boom section (e.g., at the chord of the telescopic boom section) and extending therefrom towards the support structure.

[0025] The locking system can advantageously include as many pins as there are chords in the telescopic boom section, each chord being configured to receive only one pin. The base boom section and the telescopic boom section can have, for example, four chords. Then, only four pins may be required to safely lock the telescopic boom section relative to the base boom section. Due to the third guiding system, there is no longer a need for additional locking pins to counteract the bending load forces on the telescopic boom section, as may be the case with prior art extendable booms that require additional locking pins.

[0026] The extendable lattice boom crane boom preferably further includes a telescoping system arranged to adjust at least one telescopic boom section between the retracted position and the extended position, wherein the telescoping system includes at least one winding system. The winding system can include a wire rope pulley system with a winch. The wire rope can be rove between a pulley mounted within the base boom section and a pulley mounted on the telescopic boom section. Pulling in the wire rope with the winch can, for example, cause the telescopic boom section to be pulled out of the base boom section, thus extending the boom while moving along the guide. During retraction of the telescopic boom section, the winch can be operated to release the wire rope allowing the telescopic boom section to move inside the base boom section, typically downward due to gravity. In an alternative embodiment, the telescoping system can include a hydraulic cylinder or a rack and pinion system instead of a winding system. The telescoping system can preferably include two winding systems, each being disposed on opposite sides of the base boom section, preferably on the sides of the base boom section, which is beneficial for balancing the load distribution. Preferably, a single winch is used for the two winding systems such that the two winding systems effectively form a single combined telescoping system disposed on both sides of the base boom section.

[0027] The extendable lattice boom crane boom can further include a measuring system configured to detect the position of the telescopic boom section relative to the base boom section. Such a measuring system can include, for example, a camera for visual inspection, or a closed-circuit television system, or any other suitable measuring system. The measuring system can send feedback of its measurements to a control system that can control the extension or retraction of the extendable boom in a partially or fully automated manner, or under the control of a human operator.

[0028] Instead of a single telescopic boom section, the extendable crane boom can also include a plurality of telescopic boom sections having reduced dimensions, preferably having a reduced cross-sectional dimension, and / or having a similar or reduced longitudinal dimension, each being movable relative to another to extend or retract the boom. A similar guiding system between two adjacent telescopic boom sections can be used between the telescopic boom section and the base boom section. The locking system and the telescoping system can also be modified and / or added for the plurality of telescopic boom sections.

[0029] According to another aspect of the present invention, there is provided a crane having the features of claims 15 to 18. Such a crane can provide one or more of the above advantages. The crane includes an extendable lattice boom crane as described above. The lattice boom can be moved between a transport position and a working position, wherein the lattice boom is in a substantially retracted and substantially horizontal position and is extended in the working position. The crane further includes a crane base to which the extendable lattice boom is pivotally connected such that the crane boom can rotate about an axis that is substantially horizontal between the transport position and the working position. The crane base can also optionally be made rotatable about a substantially vertical axis. The crane further includes a boom lifting system arranged to rotate the extendable boom between the transport position and the working position, and a load lifting system configured to lift a load. The boom lifting system can preferably be connected to the distal end of the base boom section and the distal end of the telescopic boom section, which can provide a relatively stable, well-balanced and reliable crane. Optionally, the boom lifting system can also be connected to one of the distal end of the base boom section and the distal end of the telescopic boom section. The boom lifting system can also be configured to be controlled by a control unit during operation of the telescopic system to follow the telescopic system to facilitate the movement of the telescopic boom section. Thus, the crane operator may only need to operate the telescopic system, and the boom lifting system is controlled by the control unit to automatically follow to facilitate the movement of the telescopic boom section. Thus, an optimal angle of about 80° of the crane boom can be maintained during the telescopic operation.

[0030] Advantageously, a measurement system can be provided to determine the actual position of the telescopic crane boom section relative to the base boom section. The measurement can provide feedback to the crane operator regarding the actual position, and the crane operator can adjust the crane operation based on this information. Additionally, the measurement system can be configured to control the reduction of the speed of the telescopic system when approaching the desired extension position. This can assist the crane operator in approaching the desired extension position and can reduce the risk of failure or damage.

[0031] The control unit that relies on the operation of the telescopic recovery system to control the operation of the boom lifting system can be part of the measurement system or can be provided as a separate control unit. In a preferred embodiment, a measurement system is provided that is configured to control the operation of the crane and provide an output of measurement parameters (such as the telescopic boom speed) to an output unit (such as the user interface of the crane operator).

[0032] An extensible crane boom can generally be provided with a lifting element, to which a lifting system can be mounted, and which can be connected to a crane base, preferably to a winch at the crane base. In the mounted position, when the boom is mounted to the crane base, one or more chords of the boom are upper chords on the side of the boom where the lifting element is provided. The chords on the opposite side are lower chords in the mounted state.

[0033] In a preferred embodiment of the crane, the crane base can be mounted around the legs of a jack-up platform. Even in a harsh offshore environment, such a crane base can provide a relatively compact but efficient crane. The crane base can also be mounted on a standard pedestal with a slewing bearing arrangement. However, arranging the crane base around one leg of the jack-up platform provides a space-efficient solution for utilizing the deck space of the jack-up platform.

[0034] According to another aspect of the invention, there is provided a jack-up platform having the features of claims 18 to 19. Such a jack-up platform can provide one or more of the above advantages.

[0035] According to yet another aspect of the invention, there is provided a method of operating a crane having the features of claims 20 to 23. Such a method can provide one or more of the above advantages. In a preferred embodiment of the method, operation of the telescoping system is started when the extensible lattice boom has reached a boom angle of at least approximately 30 degrees, preferably at least approximately 50 degrees, more preferably at least approximately 55 degrees, relative to the substantially horizontal position. The method can also include fixing the length of the boom sling of the boom lifting system. Since the length of the boom sling of the boom lifting system is fixed, for example at a boom angle of approximately 50 degrees or greater or less relative to the substantially horizontal position, operation of the telescoping system can cause the extensible boom to be lifted by fixing the length of the boom sling of the boom lifting system. Description of the Drawings

[0036] The invention will be further elucidated with reference to the drawings of exemplary embodiments. Corresponding elements are denoted by corresponding reference numerals.

[0037] Figure 1 A side view showing a first embodiment of a crane including an extensible crane boom according to the invention in different positions;

[0038] Figure 2 Shows Figure 1 A perspective view of the distal end of the base boom section of the extensible boom of the crane shown;

[0039] Figure 3 Shows Figure 1 A perspective view of the proximal end of the telescoping section of the extensible boom of the crane shown;

[0040] Figure 4 shows Figure 1 a perspective detail view of a third guiding system of an extensible boom;

[0041] Figure 5 shows Figure 1 a perspective view of a base boom section of an extensible boom of the crane shown;

[0042] Figure 6 shows a perspective view of Figure 1 a part of an extensible boom in a first intermediate position;

[0043] Figure 7 shows a perspective view of Figure 1 a part of an extensible boom in a second intermediate position. DETAILED DESCRIPTION

[0044] Figure 1Shows a side view of a first embodiment of a crane 1, which crane includes an extendable crane boom 2 in different positions according to the present invention. The crane 1 includes a crane base 3 to which the extendable lattice boom 2 is rotatably connected. The crane base 3 can be mounted around the legs 4 of a self-elevating platform, for example as a slewing platform, but can also be mounted in different ways, such as on a standard pedestal with a slewing bearing, on a self-elevating platform, or on any other structure that requires a crane of this type. The lattice boom 2 can be moved between a transport position T, in which the lattice boom 2 is in a substantially retracted and substantially horizontal position, and a working position W, in which the telescopic boom section 2b is in an extended position E via an intermediate position I. To effect the movement of the crane boom, the crane 1 further includes a boom lifting system 5, which is arranged to move the extendable boom 2 between the transport position and the working position. The boom lifting system includes at least one, preferably two, boom lifting winches 11 mounted on the crane base. The boom lifting system 5 can include two parallel wire rope and pulley systems, both connected to the distal end of the extendable boom and / or the distal end of the base boom section 2a. The crane 1 is also equipped with a load lifting system 6 configured to lift a load. The load lifting system 6 can include at least one main lifting winch 10, a head assembly 7 mounted on the distal end of the extendable crane boom 2, and an optional auxiliary lifting system 8 including an auxiliary lifting winch, which optional auxiliary lifting system 8 can be configured to lift a smaller load, to a greater height, and at a faster speed than the main load lifting system. For example, the main lifting system can be configured to lift a load of up to approximately 2500 tons to a height of approximately 115 m above ground / deck, or a load of up to approximately 1250 tons to a height of approximately 156 m above ground / deck. This configuration allows the installation of offshore wind turbines of up to approximately 16 MW. It will be understood that this is merely an example and that smaller or larger configurations are possible. The extendable boom 2 includes a lattice base boom section 2a and at least one lattice telescopic boom section 2b. Each of the lattice base boom section 2a and the lattice telescopic boom section 2b includes longitudinal chords 15 at each corner of the boom sections 2a, 2b, specifically four chords 15, which are interconnected with a truss 16. The diameter of the chords 15a of the base boom section 2a is generally greater than the diameter of the chords 15b of the telescopic boom section 2b. The telescopic boom section 2b can be adjusted relative to the base boom section 2a between a retracted position R, in which the telescopic boom section 2b is substantially inside the base boom section 2a, and an extended position E, in which the telescopic boom section 2b is at least partially outside the base boom section 2a.In the above example of a lifting system configured to lift loads of up to 2500 tons, the total boom length in the retracted position can be, for example, approximately 95 m, while the total boom length in the maximum extended position can be, for example, approximately 135 m long, or longer or shorter. The boom lifting system 5 is connected to the distal end of the base boom section 2a and to the distal end of the telescopic boom section 2b, more specifically, to the head assembly 7 on the telescopic boom section 2b and to the support structure 9 on the distal end of the base boom section 2a. As shown, in the working position W, when the extension process of the telescopic boom section 2b has been completed, the crane boom 2 forms an angle α with the substantially horizontal transport position of the crane boom 2, the angle being in the range of approximately 75° to 85°, preferably an angle of approximately 80°. Said position can be considered as the starting position for lifting the load, and if necessary, the boom angle can be adjusted again to reduce the boom angle. The transport position and the working position also allow defining an upper side 17 and a lower side 18 of the extensible boom 2, the lower side 18 being the side on which the extensible boom 2 is turned downwards in the transport position, and the upper side 17 of the extensible boom 2 being the opposite side of the lower side 18. The boom lifting system 5 is at least partially mounted on the upper side 17 of the extensible boom 2, while the load is lifted along the lower side 18 of the extensible boom 2. The extensible crane boom 2 also includes a telescopic system 12 which is arranged to adjust at least one telescopic boom section 2b between said retracted position and said extended position. The telescopic system 12 includes at least one winding system, preferably including two winding systems, each provided on opposite sides of the base boom section 2a, preferably on the lateral sides of the base boom section 2a (see. Figure 4)。The telescoping system 12 can be configured to extend the extensible boom 2 relatively quickly from the retracted position (R) to the extended position (E). The telescoping system 12 also includes at least one telescoping winch 13. The winding system can be configured such that pulling in the wire rope 14 by means of the winch 13 can, for example, cause the telescopic boom section 2b to be at least partially pulled out of the base boom section 2a, thereby at least partially extending the boom while moving along the guiding system. During retraction of the telescopic boom section 2b, the winch 13 can be operated to release the wire rope, which allows the telescopic boom section to move inside the base boom section. To speed up operations that may be important in a harsh offshore environment, it is desirable to start extending the telescopic boom section 2b during hoisting of the extensible boom 2 (i.e., during movement of the extensible boom 2 from the transport position T to the working position W), or to start retracting the telescopic boom section 2b into the base boom section 2a when the boom 2 moves from the working position W to the transport position T. For prior art extensible boom cranes, this combined movement of extending the telescopic boom section and hoisting the boom can lead to deformation and sagging, especially at lower boom angles. With the present invention, due to the innovative combination of the three guiding systems, the telescopic boom section can be started to be extended even at relatively low boom angles, which will be further explained below.

[0045] Figure 2 shows Figure 1 a perspective view of the distal end of the base boom section 2a of the extensible boom 2 of the illustrated crane 1. The distal end of the base boom section 2a includes a first collar 20 to which a first guiding system 21 is mounted. The first collar 20 includes a section strengthening structure of a lattice-type boom section such that the collar can withstand the load of additional structures (such as the first guiding system) mounted to the collar. The first guiding system 21 is configured to guide the movement of the telescopic boom section 2b along the base boom section 2a. Additionally, the first guiding system can include a set of guiding elements 22 on the base boom section 2a and corresponding guide rails on the telescopic boom section 2b, or vice versa (see Figure 4)). The guide element 22 or guide 22, for example, can be implemented as a roller and is configured to perform a guiding movement, such as a rolling movement or a sliding movement, on or along a corresponding guide rail on the telescopic boom section. The first guiding system 21 can, for example, include a set of guides 22 for each chord. The corresponding tracks of the first guiding system can be mounted on or integrated into each longitudinal chord of the telescopic boom section. The first guiding system can advantageously be an x-y guiding system, where each set of guides includes at least two guides, such as rollers, which are configured to guide the telescopic boom section in movement along two substantially transverse directions. In an innovative way, the base boom section 2a includes a third guiding system 24, which is configured to guide the telescopic boom section 2b in movement along the base boom section 2a. The third guiding system also includes a set of guide elements or guides 25 on the base boom section 2a and corresponding guide rails on the telescopic boom section 2b, or vice versa. The third guiding system 24, in particular a set of guides 25 of the third guiding system, is spaced apart from the first guiding system 21 by a distance corresponding to the length of the portion of the telescopic boom section that remains inside the base boom section 2a in the extended position of the telescopic boom section 2b. The base boom section 2a preferably includes a second collar 26 to which the third guiding system 24, in particular a set of guides 25 of the third guiding system 24, is mounted. The second collar 26 can include one or more sectional trusses, preferably as many sectional trusses as there are chords of the base boom section, for example four. The third guiding system 24 is also preferably an x-y guiding system. The first guiding system and the third guiding system are preferably of the same type. Thus, both the first guiding system 21 and the third guiding system 24, especially the guiding elements of the corresponding first guiding system 21 and third guiding system 24 on the base boom section 2a, as will be shown below, can share the same guide rails provided on the telescopic boom section 2b. The extensible crane boom can also include a locking system 27, which is configured to lock at least one telescopic boom section 2b relative to the base boom section 2a in at least the extended position. Additionally, the locking system 27 can include a plurality of pins, each pin being configured to at least partially protrude through a corresponding pin receiving hole 28 provided in one of the first collar 20 and the telescopic boom section 2b, at least in the extended position of the boom. In the case where the plurality of pins protrude from the first collar, the size of the pin receiving hole 28 in the telescopic boom section 2b can advantageously be at least 10 mm larger than the cross-sectional size of the corresponding pin, such that the locking and unlocking of the pins can be relatively easily accomplished without frictional forces hindering the movement of the pins into and / or out of the pin receiving hole 28. Optionally, the plurality of pins can also protrude from the telescopic boom section, while the pin receiving holes are present in the first collar. Also in this case, the size of these pin receiving holes can be at least 10 mm larger than the cross-sectional size of the corresponding pin.The locking system may preferably include as many pins as there are chord members of the telescopic boom section, each chord member being configured to receive only one pin. As will be further shown, the telescopic boom section 2b of the present embodiment has four chord members 29, and thus the first collar 28 includes four pin receiving holes 28, each pin receiving hole being configured to receive a pin, the pin being configured to lock the position of the telescopic boom section 2b relative to the base boom section 2a.

[0046] Figure 3 is shown Figure 1 A perspective view of the proximal end of the telescopic section 2b of the extensible boom 2 of the illustrated crane 1 is shown. The proximal end of the telescopic boom section includes a second guiding system 30, which is configured to guide the movement of the telescopic boom section 2b along the base boom section 2a. The second guiding system also includes a set of guides and corresponding tracks, where the guides are provided on the telescopic boom section 2b and the tracks are provided on the base boom section 2a, or vice versa. Contrary to the first guiding system and the third guiding system, the second guiding system may be a radial guiding system. In the present embodiment, a set of guides 31 (in particular rollers) are provided on the chord members 32, in particular on the lower chord member 32a of the telescopic boom section 2b, at a substantially 45° angle with respect to the upper or lower side of the boom. The guides may also but not necessarily be provided on the upper chord member of the telescopic boom section. The guide rails of the second guiding system 30 may be provided on a part of the length of the chord members of the base boom section 2a, which preferably has a substantially circular cross-section. The guide rails are correspondingly mounted at a substantially 45° angle with respect to the upper or lower side of the boom. Optionally, the guides and the guide rails may be switched.

[0047] Figure 4 is shown Figure 1 A detailed perspective view of the third guiding system of the extensible boom is shown. Contrary to the base boom section, the telescopic boom section 2b preferably has chord members with a substantially rectangular cross-section. The guide rails 33 of the first guiding system 21 and / or the third guiding system 24 may be mounted on or may be integrated into the chord members 32 of the telescopic boom section 2b. The rails 33 may be shaped such that they guide the x-guiding rollers and the y-guiding rollers of the x-y guiding system. Specifically, the guide rails 33 may include two adjacent guiding sides, which are substantially transverse to each other. Such guide rails 33 may then be placed at the outer edges of the chord members of the telescopic boom section 2b having a substantially rectangular cross-section. Preferably, the guide rails 33 on the chord members of the telescopic boom section 2b may engage with the corresponding guides of the first guiding system 21 and the third guiding system 24.

[0048] Figure 5 is shown Figure 1A perspective view of a base boom section 2a of an extendable boom 2 of a crane 1 is shown. As in the previous figures, the lattice-type trusses between the longitudinal chords 29 are not shown for clarity. The second collar 26 may also include two additional cross-sectional trusses or reinforcing structures. As shown before, the base boom section 2a includes a chord 29 having a substantially circular cross-section. The second guide system 30 also includes at least one track 34 (preferably at least two tracks 34) mounted to at least one chord 29 of the base boom section 2a (preferably mounted to the lower chord 29a of the base boom section 2a). The guide rails 34 are preferably mounted at a substantially 45° angle relative to the upper or lower side of the boom so that they can engage the guides 31 of the radial guide system. The length of the guide rails 34 may be significantly shorter than the length of the telescopic boom section portion configured to extend from the base boom section 2a in the extended position E of the telescopic boom section 2b. The guide rail 34 may extend from a proximal end 35 of the base boom section 2a along the chord 29 of the base boom section 2a (eg, over less than half the length of the base boom section 2a).

[0049] Figure 6 Shown in the first intermediate position Figure 1 When the extendable boom is moved from the retracted position R (as shown in FIG. Figure 1 When it moves to the extended position E, as shown in Figure 6 As shown in the intermediate position of FIG. 1 , the telescopic boom section 2b is first guided by the first guide system 21 and the second guide system 30, in the retracted position the telescopic boom section 2b is substantially located inside the base boom section 2a, and in the extended position the telescopic boom section is at least partially located outside the base boom section. The guide 25 of the third guide system 24 can engage with the guide rail 33, but the third guide system 24 is hardly subjected to any load. At this stage of the extension of the telescopic boom, the crane boom is statically uncertain.

[0050] Figure 7 Shown in the second intermediate position Figure 1 A perspective view of a portion of an extendable boom. When the telescopic boom section 2b is in Figure 6When further extending after the first intermediate position shown, the guide member 31 of the second guide system 30 will exceed the length of the corresponding guide rail 34 of the second guide system 30 at a certain point, causing the second guide system to stop guiding. The movement of the telescopic boom section 2b is then guided by the first guide system 21 and the third guide system 24. The second guide system 30 no longer bears any load. When the guide member 31 of the second guide system 30 has substantially reached the third guide system 24 and / or the second collar 26, the telescopic boom section 2b has reached its extended position E. When the extendable crane boom 2 is in a substantially upright position, particularly when the extendable crane boom 2 has a boom angle α of substantially 80 degrees relative to the horizontal plane, the extension of the telescopic boom section 2b from the base boom section 2a can be completed. However, the present invention also allows for earlier extension of the telescopic crane boom, particularly starting from a boom angle α of substantially 30 degrees, or more preferably starting from a boom angle α of substantially 50 degrees. More specifically, due to the present invention, the lifting of the crane boom from the transport position T to the working position W can be accomplished by the length of the boom sling of the fixed boom lifting system 5, measuring the boom sling from the boom lifting winch 11 to the crane boom. For example, the boom lifting system 5 can be activated to lift the crane boom from the transport position T to the first intermediate position at a boom angle α within a range of approximately 30 degrees to approximately 55 degrees relative to the horizontal plane. Then, the boom lifting system 5 can be configured to hold the sling at a constant length, for example, by placing a brake on the boom lifting winch 11. Then, the locking pin of the locking system 27 can be removed from the pin receiving hole 28, and the locking system 27 has held the telescopic boom 2 in the retracted position R. Next, the telescopic system 12 can be activated and the extension of the telescopic boom can be started. The start of the extension of the telescopic boom in combination with the boom lifting system being configured to keep the length of the sling rope constant will cause the crane boom to continue to be lifted towards the working position of the crane boom. Therefore, by at least partially performing the extension of the telescopic boom during the lifting of the crane boom, or even better by at least partially performing the lifting of the crane boom by extending the telescopic boom, time can be saved in preparing the crane for the lifting operation, and at the same time, due to the improved extendable crane boom, these lifting and extension operations can be kept relatively stable and safe.

[0051] For the purposes of clear and concise description, the features described herein are part of the same or separate embodiments. However, it should be understood that the scope of the present invention may include embodiments having combinations of all or some of the described features. It can be understood that the illustrated embodiments have the same or similar components, except where they are described as different.

[0052] In a claim, any reference sign placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of other features or steps than those listed in a claim. Further, the words "a" and "an" shall not be construed as limited to "only one", but rather are used to denote "at least one", and do not exclude a plurality. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage. A person skilled in the art will recognize many variations. All variations are to be understood as included within the scope of the invention defined by the following claims.

Claims

1. An extensible lattice crane boom for a crane, the boom comprising a lattice base boom section and at least one lattice telescopic boom section, wherein the at least one telescopic boom section is adjustable relative to the base boom section between a retracted position and an extended position, in which the telescopic boom section is substantially inside the base boom section in the retracted position and at least partially outside the base boom section in the extended position. Wherein the distal end of the base boom section includes a first guiding system configured to guide the movement of the telescopic boom section along the base boom section; Wherein the proximal end of the telescopic boom section includes a second guiding system configured to guide the movement of the telescopic boom section along the base boom section; Wherein the base boom section includes a third guiding system configured to guide the movement of the telescopic boom section along the base boom section, the third guiding system being spaced from the first guiding system by a distance corresponding to the length of the part of the telescopic boom section that remains inside the base boom section in the extended position of the telescopic boom section. Wherein, The first guiding system includes a first guide rail and a cooperating first guiding element configured to be guided along the first guide rail, the first guide rail being provided on one of the base boom section and the telescopic boom section, and the first guiding element being provided on the other of the base boom section and the telescopic boom section; Wherein the second guiding system includes a second guide rail and a cooperating second guiding element configured to be guided along the second guide rail, the second guide rail being provided on one of the base boom section and the telescopic boom section, and the second guiding element being provided on the other of the base boom section and the telescopic boom section; and Wherein the third guiding system includes a third guide rail and a cooperating third guiding element configured to be guided along the third guide rail, the third guide rail being provided on one of the base boom section and the telescopic boom section, and the third guiding element being provided on the other of the base boom section and the telescopic boom section.

2. The extensible lattice crane boom according to claim 1, wherein the base boom section includes a first collar to which the first guiding system is mounted, and / or wherein the base boom section includes a second collar to which the third guiding system is mounted.

3. The extensible lattice crane boom according to the preceding claim 1, wherein the second guide rail is mounted to at least one chord of the base boom section, and the length of the second guide rail is significantly shorter than the length of the part of the telescopic boom section configured to extend from the base boom section in the extended position of the telescopic boom section.

4. The extendable lattice boom crane boom according to claim 1 above, wherein the first guiding element of the first guiding system and / or the third guiding element of the third guiding system are mounted on the chord of the base boom section, and wherein the first guiding element and / or the third guiding element are arranged at the same axial distance along the base boom section.

5. The extendable lattice boom crane boom according to claim 1 above, wherein the first guiding system is an x-y guiding system.

6. The extendable lattice boom crane boom according to claim 1 above, wherein the third guiding system is an x-y guiding system.

7. The extendable lattice boom crane boom according to claim 5, wherein the first guide rail is mounted to at least one chord of the telescopic boom section or integrated into at least one chord of the telescopic boom section, and the first guide rail is shaped to guide both the x guiding roller and the y guiding roller of the x-y guiding system.

8. The extendable lattice boom crane boom according to claim 1 above, wherein the telescopic boom section includes chords having a substantially rectangular cross-section.

9. The extendable lattice boom crane boom according to claim 1 above, wherein the base boom section includes chords having a substantially circular cross-section.

10. The extendable lattice boom crane boom according to claim 1 above, wherein the second guiding system is a radial guiding system, arranged on the chords of the base boom section and / or the telescopic boom section, at an angle of approximately 45° with respect to the upper or lower side of the boom.

11. The extendable lattice boom crane boom according to claim 1 above, further comprising a locking system configured to lock the at least one telescopic boom section relative to the boom section in at least the extended position.

12. The extendable lattice boom crane boom according to claim 11, wherein the locking system includes a plurality of pins, each pin being configured to at least partially extend through a corresponding pin receiving hole provided in the first collar and one of the telescopic boom sections at least in the extended position of the boom, and wherein the pin receiving hole is sized at least 10 mm larger than the cross-sectional size of the corresponding pin.

13. The extendable lattice boom crane boom according to claim 12, wherein the locking system includes as many pins as the telescopic boom section has chords, and each chord is configured to receive only one pin.

14. The extendable lattice boom crane boom according to claim 1 above, further comprising a telescoping system arranged to adjust the at least one telescopic boom section between the retracted position and the extended position, wherein the telescoping system includes at least one winding system.

15. The extendable lattice boom crane boom according to claim 14, wherein the telescoping system includes two winding systems, each winding system being arranged on opposite sides of the base boom section.

16. The extensible lattice boom crane according to claim 6, wherein the third guide rail is mounted to at least one track of at least one chord of the telescopic boom section, or integrated into at least one track of at least one chord of the telescopic boom section, and the third guide rail is shaped to guide both the x-guide roller and the y-guide roller of the x-y guiding system.

17. A crane, which comprises: the extensible lattice boom crane according to any one of the preceding claims; wherein the lattice boom crane is movable between a transport position and a working position, in the transport position the lattice boom crane is in a substantially retracted and substantially horizontal position, and in the working position a load can be lifted; a crane base, to which the extensible lattice boom crane is pivotally connected; a boom lifting system arranged to move the extensible crane boom between the transport position and the working position; a load lifting system configured to lift a load.

18. The crane according to claim 17, wherein the boom lifting system is connected to the distal end of the base boom section and the distal end of the telescopic boom section.

19. The crane according to any one of the preceding claims 17 to 18, wherein the crane base is mountable around the legs of a self-elevating platform.

20. A self-elevating platform comprising the crane according to any one of the preceding claims 17 to 19.

21. The self-elevating platform according to claim 20, wherein the crane base is mounted around the legs of the self-elevating platform.

22. A method of operating a crane, the crane comprising the extensible lattice boom crane according to any one of the preceding claims 1 to 16, wherein the extensible lattice boom comprises a lattice base boom section and at least one lattice telescopic boom section, the method comprises the steps of: bringing the extensible lattice boom from a transport position to a working position; operating a telescopic system to adjust the at least one telescopic boom section relative to the base boom section from a retracted position, in which the telescopic boom section is substantially inside the base boom section, to an extended position, in which the telescopic boom section is substantially outside the base boom section; wherein the operation of the telescopic system and the operation of bringing the extensible lattice boom from the transport position to the working position are at least partially simultaneous.

23. The method of operating a crane according to claim 22, wherein the operation of the telescopic system is started when the extensible lattice boom has reached at least approximately 30 degrees relative to a substantially horizontal position.

24. The method of operating a crane according to claim 22 or 23, wherein the length of the boom sling of the boom lifting system is fixed when the extensible lattice boom has reached at least approximately 30 degrees relative to a substantially horizontal position.

25. The method of operating a crane according to any one of the preceding claims 22, further comprises the steps of: The telescopic boom section is locked relative to the base boom section in the extended position of the telescopic boom section by inserting a plurality of pins substantially simultaneously through respective pin receiving holes provided in a chord member of one of the telescopic boom section and the base boom section.

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