MORTENSEN, Henning (Grenåvej 247, Randers SØ, DK-8960, DK)
| Claims 1. A support assembly for handling a tower crane of a type which in use is hoisted or otherwise raised up a wind turbine tower for use in handling components of a wind turbine during installation or service, the support assembly comprising a first support which supports an end of the crane having a pivoting structure which is pivotable between a transport position where the crane is substantially horizontal to a lifting position where the crane is substantially vertical, the pivoting structure having a locking structure which releasably engages the crane end. 2. A support assembly according to claim 1 wherein a second support is provided for supporting an opposite end of the crane in the transport position. 3. A support assembly according to claim 1 or 2 wherein the first crane support comprises a pivoting engagement structure which engages the crane end in use and which is pivotably connected to a base part. 4. A support assembly according to claim 3 wherein the releasable locking structure is provided on the engagement structure. 5. A support assembly according to claim 4 wherein the locking structure comprises a releasable clamp for gripping the crane end. 6. A support assembly according to any preceding claim wherein the first crane support is provided with a pivot locking device which is able to lock the pivoting engagement structure in one or other of the transport position and in the lifting position. 7. A support assembly according to claim 6 wherein the pivot locking device is adapted to automatically lock the pivoting engagement structure in the lifting position as the crane completes an initial pivoting operation into its vertical position. 8. A support assembly according to any preceding claim wherein the support or supports is/are carried on or form part of a truck or vessel for transporting the crane. 9. A support assembly according to claim 8 wherein the first support is carried on or forms part of a rear bogie of a truck. 10. A support assembly according to claim 9 wherein a second crane support for the opposite upper end of the crane forms part of or is carried on a front bogie of the truck. 11. A truck having a support assembly according to claim 10 having front and rear bogies supporting respectively opposite ends of the crane, wherein the truck rear bogie is separated from the truck front bogie, whereby during transport the crane is suspended between front and rear bogies. 12. A method of handling a crane for use in installation or service of components of a wind turbine, the crane being supported in a transport position on a support assembly having a first support which pivotably supports an end of the crane and a second support for an opposite end of the crane, the method comprising the steps of: securing a hoisting cable or cable assembly, an upper end of which is connected at the wind turbine nacelle or tower, to the crane at a lifting point thereon which is at or near the opposite end of the crane; conducting an initial lifting operation of the crane with the hoisting assembly so that the opposite end of the crane lifts off the second support and the crane pivots about the first support into a substantially vertical lifting orientation. 13. A method according to claim 12 further comprising hoisting the crane up the tower into an operating position on the tower or nacelle. 14. A method according to claim 12 or 13 wherein the first support comprises a base part and an engagement structure pivotably connected thereto provided with a releasable crane locking structure which holds the crane end thereon, the method involving release of the locking structure when in the substantially vertical orientation prior to hoisting up the tower. 15. A method according to any one of claims 12 to 14 wherein the first support is provided with a pivot locking device which locks the pivotable engagement structure in the transport position and in the lifting position, the method involving release of the pivot locking device prior to the initial lifting operation, and engagement of the pivot locking device when the crane reaches the vertical lifting orientation. 16. A method according to claim 15 wherein the pivot locking device is adapted to automatically lock the first support as the crane undergoes the initial lifting operation and the support arrives at the lifting orientation. 17. A method according to any one of claims 12 to 16 wherein the hoisting cable assembly is itself hoisted up to the nacelle using an internal nacelle crane. 18. A method according to any one of claims 12 to 17 wherein the crane is provided with a hoist motor which drives the crane hoisting operation. 19. A method according to claim 13 wherein the hoisting of the crane up the tower is preceded by the securing of a control line to a lower end of the crane, which is played out on hoisting maintaining a degree of tension in the control line so as to prevent undue movement of the crane relative to the tower. |
Components
Field of the Invention
The invention relates to a support assembly for handling of a tower crane of the type which in use is hoisted up the tower for handling of components of a wind turbine generator during installation or service, and to a handling method involving such a crane as part of a hoisting operation.
Background of the Invention
Wind turbine generators (hereinafter 'wind turbines') of commercial mega-watt scale comprise a rotor which is mounted for rotation atop a tall tower on a main shaft held on a nacelle. The nacelle also houses the main operative components including a gearbox, if provided, and generator, converter etc. In the erection of wind turbines it is necessary to lift the various components of the turbine, including tower sections themselves as the tower is erected, and the various operative components. As the size of wind turbines grows ever larger these components become larger and heavier, and more challenging to erect and service.
Commonly, stand-alone service cranes are used for the lifting of major
components on turbine erection. These have the disadvantage of needing to be significantly taller then the tower, and require significant time to erect, may suffer problems of access in difficult to reach places, with the result that they are an expensive and somewhat inflexible solution.
The turbine typically also has an internal crane within the nacelle which is suitable for the lifting of relatively small components. Such cranes are not however of sufficient capacity, dimension or positioning to be able to handle major components including turbine blades or generators.
It has been proposed to provide dedicated cranes which can be hoisted or otherwise raised up the tower (or in certain versions can self-climb up) to an appropriate position on the tower for the task in hand, or up to the position of the nacelle, and which is secured to the tower and/or nacelle in a working position where it is able to handle turbine component installation, replacement and repair, including of major turbine components.
In Applicant's WO2009/080047 the contents of which are hereby incorporated by reference there is disclosed a tower crane having a main body from which extends a work platform, with a pair of gripping arms which serve to clamp tightly around the tower when in the working position. The crane is hoisted through the use of an intermediate pulley assembly, whereby the small capacity internal nacelle crane is used to hoist this intermediate pulley assembly up to the nacelle, and this intermediate pulley assembly then used to hoist the crane body. A hoist motor on the crane can provide the drive for the hoisting operation. The crane is carried to the site on a truck and hoisted from the truck, with a guiding cable secured to the crane and being played out from a drum on the truck as the crane is hoisted, serving to guide the crane and prevent undue swinging of the crane which might otherwise cause damage to the crane and tower.
The present invention seeks to provide a support assembly to be used in handling of a crane of this type for use in crane transport and hoisting, and to a method of handling of the crane.
Summary of the Invention
According to the present invention there is provided support assembly for handling a tower crane of a type which in use is hoisted or otherwise raised up a wind turbine tower for use in handling components of a wind turbine during installation or service, the support assembly comprising a first support which supports an end of the crane having a pivoting structure which is pivotable between a transport position where the crane is substantially horizontal to a lifting position where the crane is substantially vertical, the pivoting structure having a locking structure which releasably engages the crane end.
The support assembly allows the crane to be conveniently transported with the pivotable support allowing the crane to be raised in an initial hoisting operation to an upright orientation with the load at least partly taken on the support, and then lifted off the support as the crane is hoisted up the tower.
A second support is preferably provided for supporting an opposite end of the crane in the transport position from which the crane is hoisted on the initial hoisting operation.
In the preferred embodiment the first crane support comprises a pivoting engagement structure which engages the crane end and which is pivotably connected to a base part. The engagement structure, which may be in the form of a platform-like body, has a releasable locking structure which holds the crane end on the engagement structure, for example in the form of a releasable clamp for gripping the crane end.
The first crane support may be provided with a pivot locking device which is able to lock the pivoting engagement structure in one or other of the transport position and the lifting position, and this may be adapted to automatically lock the pivoting engagement structure of the support in the lifting position as the crane completes an initial pivoting operation into its vertical position. The support assembly may be carried on or form part of a truck or vessel for transporting the crane. In the case of a truck the first support may be carried on or form part of a rear bogie of a truck, whilst the second crane support for the opposite upper end of the crane forms part of or is carried on a front bogie of the truck. In a preferred structure the front and rear bogies support respectively the opposite ends of the crane, and where the truck rear bogie is separated from the truck front bogie during transport the crane is then suspended between front and rear bogies. This allows the vertical clearance of the crane when in its transport position to be minimised.
In a further aspect the invention resides in a method of handling a crane for use in installation or service of components of a wind turbine, the crane being supported in a transport position on a support assembly having a first support which pivotably supports an end of the crane and a second support for an opposite end of the crane, the method comprising the steps of: securing a hoisting cable or cable assembly, an upper end of which is connected at the wind turbine nacelle or tower, to the crane at a lifting point thereon which is at or near the opposite end of the crane; conducting an initial lifting operation of the crane with the hoisting assembly so that the opposite end of the crane lifts off the second support and the crane pivots about the first support into a substantially vertical lifting orientation. Further, the crane may then be hoisted up the tower into an operating or working position on the tower or nacelle.
Where the first support comprises a base part and an engagement structure pivotably connected thereto provided with a releasable crane locking structure which holds the crane end on the engagement structure, the method involves release of the crane lock structure when in the substantially vertical orientation prior to hoisting up the tower.
The first support may be provided with a pivot locking device which locks the pivotable engagement structure in the transport position or in the lifting position, the method involving release of the pivot locking device prior to the initial lifting operation, and engagement of the locking device when the crane reaches the vertical lifting orientation. The locking device may be adapted to automatically lock the first support as the crane undergoes the initial lifting operation and the support arrives at the lifting orientation. It is preferably arranged that the hoisting cable assembly is itself hoisted up to the nacelle using an internal nacelle crane, in the manner of Applicant's
WO2009/080047. The crane is preferably provided with an internal hoist motor which drives the crane hoisting operation. The hoisting of the crane up the tower may be preceded by the securing of one or more control lines to a lower end of the crane, played out on hoisting maintaining a degree of tension in the control line so as to prevent undue movement of the crane relative to the tower.
Brief Description of the Drawings Embodiments of the invention are now described, by way of example only with reference to the following drawings in which:
Figure 1 shows a tower crane when fitted in a working position at the top of a tower;
Figure 2 shows a tower crane when supported on a truck according to a first embodiment of the invention where the crane forms a structural part between front and rear truck bogies;
Figure 3 shows the tower crane being lifted from the truck through an initial pivoting operation where it pivots over a support part forming part of the rear truck bogie;
Figure 4 shows the tower crane in a vertical orientation as it is about to be lifted off the rear bogie;
Figure 5 shows the tower crane lifted off the rear bogie and moving up the tower; and
Figure 6 shows a tower crane transported on a flatbed type truck incorporating the supports according to a second embodiment of the invention; Figure 7 shows a tower crane on supports according to a further embodiment of the invention adapted for offshore loading/unloading; and
Figure 8 shows a tower crane on supports for offshore loading according to a still further embodiment of the invention.
Detailed Description of the Preferred Embodiments
As discussed above, the invention relates to the handling of a dedicated crane of a type where the entire crane is hoisted or otherwise raised up a wind turbine tower (hereinafter 'tower crane') for use in particular in effecting installation, replacement or repair of components of the wind turbine, including major wind turbine components.
As illustrated in Figure 1 there is shown a crane when installed on the tower of a wind turbine at a working position immediately below the turbine nacelle. The crane generally indicated 2 comprises a main body 4 of elongate form. The crane main body 4 carries a movable crane arm 6 which is mounted at an upper end of the main body 4 in a manner whereby it can pivot relative to the main body 4 about a generally horizontal axis. As illustrated it is shown in a folded
configuration in which it would be transported, and hoisted or lowered, but in use the arm is extended into a generally horizontal orientation. Although not illustrated, the crane arm 6 may be constituted by a number of individual telescoping arm sections whereby the arm can be extended or retracted as desired to adjust its working reach. The end of the crane arm may carry a pulley over which is led a lifting cable (not shown). The main body 4 also carries a gripping means 8 for gripping the tower, such as flexible tensionable bands which encircle the tower as described in detail in Applicant's co-pending Danish patent application PA 2010 70176 . Alternatively, they may be in the form of gripping arms such as hydraulically operated clamp arms, as described in detail in Applicant's WO2009/080047. It will be appreciated that a variety of other means of securing the crane to the tower or nacelle may alternatively or additionally be utilised, such as making direct connection into hardpoints on the tower or nacelle or being suspended therefrom. At upper and lower ends the crane main body 4 has upper and lower flange elements 9 and 10 respectively, with surfaces of arcuate form which in use face the tower and form tower-abutting surfaces. These flanges also carry cable connections, such as pulleys, blocks or the like with the upper flange 9 carrying a block around which is led cables associated with crane hoisting, constituting a lifting point 1 1 for the crane. The crane is provided with a lifting motor arranged to wind the cable onto a drum, whereby the crane is lifted by means of the power of this motor. The lower end of the crane has a cable connection point associated with a control cable used during the lifting process used to control the movement of the lower end of the crane as it is hoisted, as is described further below.
Figure 2 illustrates the crane 2 being transported by a truck 12 on which is arranged a crane support assembly which includes a supports for opposite ends of the crane. More particularly, the end of the crane which is uppermost in operating use of the crane is supported through a support structure 16 which is arranged on the truck front bogie 14. As illustrated, this engages a part of the crane arm 6. This has the form of a fork-like cradle which is pivotably mounted on the front bogie 14 and which receives a part of the crane arm between the forks of the support 16, which is held therein by a clamping structure or other form of engagement. The opposite end of the crane, which in operating use is the lower crane end, is carried on a rear support 17 arranged on the truck rear bogie18, in a manner whereby the crane itself is suspended between and forms a load- bearing element between front and rear bogies 14,18. Arranging the crane 2 suspended between front and rear bogies allows the vertical clearance of the crane in its transport orientation to be minimised, and significantly reduced as compared to a crane sitting on top of a flat bed truck. Rear support 17 comprises a base part 18 which is integrated with or carried on the truck rear bogie 19 and is provided with a pivoting engagement structure 24 in the form of a platform-like element. This is connected through member 20 extending between a fork-like structure 22 of the base part 18 to a pivoting connection thereby forming a pivoting joint. This engagement structure 24 is movable between a transport position as shown in Figure 2 in which it extends generally horizontally, and a lifting position as shown in Figures 4 and 5 in which it is generally upright. The engagement structure 24 engages and locks to the crane end, being provided with a locking structure. In one form this locking structure comprises movable clamping fingers 26 operable to grip the crane end. They may be hydraulically operated. A support pivot locking mechanism (not shown) is further provided to releasably lock the pivoting engagement structure 24 relative to the base part 18 in either the horizontal transport position or in the upright lifting position. It may be arranged that this support pivot locking mechanism automatically locks in these positions as the engagement structure is pivotably moved between positions, as further discussed below.
It will be appreciated that a variety of other mechanical structures may be provided to effect this locking engagement of the tower end. For example, a lip structure may be provided on the platform of the engagement structure 24 to engage one side of the crane end (for example a lower side as it lies in the horizontal transport position), and which may engage in particularly adapted formations on the crane end 10, and with a clamping or gripping arrangement on the opposite side of the platform, which likewise may engage in adaptations on the crane. As a further alternative, instead of clamping or gripping structures, there may be provided fasteners such as bolts, screws, shackles or locking pins making a releasable locking connection with the crane end 10. Moreover, although a planar- like platform structure on which the crane end rests is shown this may equally have a frame-like structure with appropriate adaptations or formations to effect the connection functions. The crane 2 is transported as illustrated in Figure 2 with the crane supported between front and rear bogies 14, 19 and with the rear or first support 17 supporting the lower crane end with the engagement structure 24locked in its transport position. As the truck arrives at the wind turbine tower it is maneuvered into position with its rear bogie 19 closely adjacent the tower base. A cable or wire connection is then established between the tower crane 2 and a crane in the nacelle or a separate crane arranged alongside the nacelle. In the preferred technique, in accordance with the principles adopted in Applicant's
WO2009/080047 the internal nacelle crane is used to hoist a larger capacity intermediate hoisting assembly, which is in turn used to hoist the tower crane. Thus, a cable is lowered from the nacelle internal crane and connected to the intermediate hoisting assembly, which is hoisted and when in position secured to the nacelle and/or tower and then used to lift the crane 2. The intermediate hoisting assembly comprises a cable assembly of greater load-bearing capacity then the nacelle internal crane, being connected to the crane at its main lifting point 1 1 and being played out as the assembly is hoisted.
Once the intermediate hoisting assembly has been hoisted and locked in its lifting position on the nacelle or tower, the crane 2 is then able to be hoisted, with the lifting drive provided by the crane motor. More particularly, from the transport position of Figure 2 the pivot lock of the engagement structure 24 is released, as is the locking of the upper end of the crane from the forks of the front support 16. As shown in Figure 3, the upper end of the crane is hoisted from the support 16, this initial lifting of the crane 2 causing the crane to pivot in the rear support 17. The crane progressively pivots until the upright position shown in Figure 4, at which position the support 17 locks with the engagement structure 24 in its vertical orientation. During this pivoting a significant proportion of the weight is carried by the support 17 and hence rear bogie 14. It may be arranged that an automatic locking is effected when the vertical orientation is reached. At this position, or earlier if so desired, control lines 28 on the front support 16 are attached to the lower end of the crane, these serving as a guide to constrain the lower end of the crane 2 during lifting.
From the Figure 4 position the crane lower end is released from its connection with the engagement structure 24 by releasing the clamping fingers 26 of the locking structure holding the crane end on the platform, the crane then being hoisted off the support 17 and up the tower. The control lines 28 are played out , guiding the lower crane end so that it does not impact or swing dangerously relative to the tower, whereby damage to crane or tower might result. When the crane reaches its working position, it is secured in position through locking and /or gripping means which engage the nacelle and/or tower, or by other
appropriate strucures. In a preferred form the crane may include at its upper end, preferably on the flange, a docking structure whereby the upper end may engage a part of the nacelle, such as a locking pin arrangement. In addition the gripping structures 8 on the crane body encircle or partly encircle and tightly grip the tower. The control lines 28 may then be removed by lowering to the ground or retracting into the crane body or into the nacelle. The crane arm 6 can be unfolded into an operating position ready for conducting a handling operation of installing, removing or otherwise handling a component of the wind turbine.
Lowering of the crane is carried out by a reversal of the hoisting operation including folding of the crane arm 6, re-attaching of control lines 28 between the lower end of the crane and truck, securing of the hoisting cables to the crane lifting point 1 1 and taking up any slack whereby the crane weight is taken by the lines, release of the docking structures and release of the tower gripping means 8. The crane is then lowered through controlled release or unwinding of the hoisting cables, with the crane moving down the tower and the slack in the control lines 28 taken up. The crane is lowered onto the support 17 which has the
engagement structure 24 in its locked vertical position, and the clamping connection of the clamping fingers 26 with the crane lower end re-established. The pivot locking of the engagement structure 24 is then released, continued lowering allowing the crane to pivot with the engagement structure 24 until the upper end of the crane re-engages the attachment point on the front support 16, whereupon the crane is returned to its transport position. Although the truck of the afore described embodiment has an arrangement of separate front and rear bogies with the support assembly carried on the front and rear bogies, as shown in Figure 6 it may be arranged that the structures are incorporated into a more conventional arrangement of a flat bed truck with connected front and rear bogies 14' and 19', but where this is adapted to incorporate the front support 16 with its cradle structure for the crane upper end at or near a forward position on the truck over the front bogie14'. The pivoting support 17 for the lower end of the crane is then incorporated into or on the rear of the truck over the rear bogie 19. Hoisting and lowering is effected in the same manner as described above.
The same technique is applicable to hoisting of a crane for use in servicing wind turbines in the offshore environment. In this case the front and rear support structures 16, 17 can be carried on the deck of a boat or barge or other floating structure 30 which is brought alongside the base of the tower for offloading of the crane. Figure 7 shows support structures incorporated into front and rear bogies where the pivoting rear support 17 is identical to the rear bogie structure of Figure 2. The front support 16 is incorporated into a non-driven front bogie arrangement, including an identical arrangement of cradle to receive the upper end of the crane.
In a still further embodiment as illustrated in Figure 8 the support assembly can be separated from any road transport bogie arrangement, and can be provided as dedicated support structures which rest on or are incorporated as deck fittings of the boat or barge, but comprise essentially the same functional components of pivoting rear support 17' for the crane lower end and front support for the crane upper end . It may alternatively be arranged that the motor for lifting the crane is provided at the ground, with appropriate cabling and pulleys whereby operation of the motor drives a drum on which the cable is wound, lifting the crane.
While the invention has been particularly shown and described with reference to the preferred embodiments thereof it will be understood by those skilled in the art that the foregoing and other changes in form and detail may be made without departing from the scope of the invention.