CRANE FOR RAISING LONGITUDINAL BODIES, FOUNDATION FOR SUCH A CRANE AND METHOD FOR RAISING OF LONGITUDINAL BODIES BY MEANS OF SUCH A CRANE

Abstract: A crane adapted for the erection of elongated bodies, preferably wind turbines, is attached to the same foundation which is used for the wind turbine. The crane comprises a jib which may be displaced forwards and backwards. The cap and the blades of the wind turbine are thereby hoisted to the top of the wind turbine tower once this has been erected. The crane is mounted on the same foundation which serves as foundation for the wind turbine once that has been erected. Bearing pedestals for seating the jib and anchoring straps for the attachment of double acting lifting and lowering devices are connected to the foundation, this foundation being additionally provided with an anchoring base for the wind turbine tower. The crane is of particular advantage for the erection of wind turbines in regions where it is difficult and costly to bring in a mobile crane for the erection of tall wind turbines or in case it is difficult to use a stationary crane in view of the anchoring and the support required for such cranes. Floating or wheeled mobile cranes need a large counterweight while stationary cranes according to the prior art require a solid anchoring at a great distance from the wind turbine foundation and put great demands to the steadiness of the support.

Description: Crane for raising longitudinal bodies, foundation for such a crane and method for raising of longitudinal bodies by means of such a crane. BACKGROUND OF THE INVENTION The present invention relates to a crane for the erection of elongated bodies to a vertical position, which crane compri¬ ses a jib which may be tilted about a first bearing with a horizontal axis of rotation, said first bearing being provided at a lower portion of the jib in connection with a support plane and at least one second bearing, said second bearing being provided at a lower portion of a double-acting lifting and lowering mechanism also in connection with the support plane, and the uppermost end of said lifting and lowering mechanism being secured to the jib. The invention further relates to a foundation and a method for use in connection with the erection of elongated bodies by means of the crane. Tall wind turbines, e.g. wind turbines having a height of up to 50 m to a hub for the turbine blades, are usually erected by means of mobile cranes or, in impassable country, by means of a helicopter. In certain parts of the world where it is desirable to erect wind turbines for energy supply reasons in a small local community, it is often impossible for mobile cranes to reach their destination due to bad or very narrow travel ways. In other places no mobile cranes whatsoever are present in the area. In that case, a helicopter may be used but it is a very expensive solution especially if the distance to be travelled is very far. Wind turbines erected at sea are usually erected by means of floating mobile cranes. Thus, in this case, it has so far been necessary not to go beyond erecting shorter wind turbines having lower performan- ce by means of conventional lorry cranes and minor mobile cranes and in consequence it has also been necessary to erect a larger number of wind turbines. As an alternative to mobile cranes, cranes which are solidly secured to the ground may be used. DE 2,602,745 describes a crane for lifting and erecting elongated objects. The crane comprises a first pair of jibs, a crossbar and a second pair of jibs which extend from an upper end of one of the first jibs. The crane is hinged to a base and following erection of the crane, the latter is secured by a pair of chains which extends from the base to the first jibs. An elongated object may subsequently be erected by hoisting the object between the second jibs. The crane described in this disclosure is associated with several drawbacks. Firstly, the crane is based on the principle that the elongated object to be erected is conveyed upwards between the second jibs as the crane is shorter than the elongated object. Thus, it is impossible to lift other parts above the elongated object following erection of the latter. Moreover it is necessary to establish an independent foundation for the crane. For known cranes or other devices which constitute elevating devices for elongated bodies, such as wind turbines, flag poles or telephone posts, it is necessary to establish an independent foundation or an independent securing point for the crane or the elevating device. Such cranes or elevating devices will appear from GB 1,270,- 205, GB 2,115,368, DE 2,255,713, FR 1,213,060, FR 3,075,866, EP 0,169,104, SE 152,198 and the above-mentioned disclosure DE 2,602,745. The cranes or other elevating devices taught in said dis¬ closures are associated with the essential drawback that it is necessary to establish at least one point for the absorp¬ tion of tensile forces, which is often situated far from the site where the elongated object is to be erected. This makes high demands to the rigidity and solidity of the support on which the point for absorbing the tensile force is establis¬ hed. It also makes high demands to the anchoring proper in this point. If the rigidity, the solidity and the achoring are insufficient in this point, it may have catastrophic consequences to both equipment and crew since, during erection, the elongated body may suddenly and without warning plunge to the ground. In particular when elongated bodies are to be erected on a foundation at sea or in e.g. marshland, it causes much trouble to erect large-size bodies. It is the object of the present invention to provide a crane and a foundation as well as a method which, in addition to enabling erection of elongated bodies and allowing subsequent lifting of other parts all or part of the way to the top of the elongated body following erection thereof, does not depend on an independent foundation for the crane and which does not involve a risk of the elongated body suddenly plunging during erection thereof. This object is obtained with a crane which is characterized in that the support plane constitutes the foundation of the elongated body, that the first bearing for the crane is anchored to the foundation by means of a first anchoring, said first anchoring for the first bearing being arranged between a mounting area for the elongated body and in an opposite edge area of the foundation seen relative to the first anchoring, and in that the at least one second bearing for the crane is anchored to the foundation by use of at least one second anchoring, said second anchoring being arranged at a distance from the first anchoring in a direc- tion from the first anchoring opposite a direction from the first anchoring to the edge area. A crane of this type is particularly suited for, and primari¬ ly developed for the erection of tall wind turbines. However, the crane according to the invention will also be useful for the erection of other elongated bodies, such as flag poles, telephone posts or other bodies. Furthermore, the crane may be used for the erection of elongated bodies which have a foundation at sea as well as on land. In the following the crane will be described with reference to the erection of wind turbines, however, without this description being regarded as limiting to the fields of application of the crane. The crane according to the invention uses the foundation of the wind turbine as its own foundation. This presents several advantages. The foundation of the wind turbine is often very rigid and very solid, i.e. it is well anchored to the ground or the sea bed, and the material used in the foundation is also very solid since the foundation is to be able to withstand very strong forces when the wind turbine is operative. Thus, it is not an issue that the foundation is not sufficiently rigid or solid to anchor the crane, too. Moreover, it is not necessary to provide the crane with any counterweight, such as it would be required in case of floating or wheeled mobile cranes. The crane according to the invention provides a further advantage relative to stationary cranes or hoisting devices by eliminating the need for providing one or more points at a substantial distance from the zone intended for the placement of the wind turbine, i.e. the wind turbine founda¬ tion. The major loading forces transferred during the erection of the wind turbine to the portions of the crane anchored to the foundation by means of the mentioned first anchoring and the second anchoring are compressive forces. The foundation can easily absorb these compressive load forces and the crane according to the invention puts no great demands on the anchoring to the foundation which is different from the situation with anchoring of cranes or other hoisting devices of the prior art which are secured by tensile forces. The crane according to the invention also makes it feasible to erect taller and larger wind turbines whith greater capacity, thus making it possible to reduce the number of wind turbines to be erected. Taller and larger wind turbines provide an advantage in reduction of the costs for producing electricity so that the price of electricity can be reduced correspondingly. The crane according to the invention is taller than the tower of the wind turbines to be erected. This makes it possible after erecting the wind turbine tower to hoist the cap and the blades of the wind turbine to the top of the tower. Obviously this would not have been possible in case of a crane shorter than the tower. The crane is primarily intended for erecting wind turbines of a height between 30 metres and 50 metres or even more. This would otherwise have necessita- ted very large mobile cranes with a capacity of close to 350 tons. In order to serve the purpose of hoisting the wind turbine cap and wings to the top of the tower, the crane must be adapted to tilt forwards or backwards to a position where the crane hoisting gear is located in front of or behind the erected wind turbine tower and not immediately there above. The wind turbine cap and the wind turbine blades will be placed on the ground in front of or behind the tower base and the hoisting gear lifting means, such as a hook or the like will be located in front of or behind the tower, positioned to elevate the wind turbine cap and the wind turbine blades to the top of the tower. Having elevated the wind turbine cap and blades to the desired altitude, the crane will be tilted in order to displace the wind turbine cap, respectively the blades, horizontally to the position relative to the tower, respectively to the wind turbine cap, wherein the respective parts are to be placed. After the erection of the tower and the fitting of wind turbine cap and blades on to the tower, the crane is ge¬ nerally no more required. The crane is disconnected from the foundation by lowering the crane to a position where the jibs extend along the surface of the ground or the sea and the bearing is dismantled. The crane may then be transported to another wind turbine foundation, attached there and erected. The crane is then ready to erect another wind turbine. A crane with the features mentioned secures that the loadings to the foundation will be distributed in the best possible manner without requiring the provision of further relief for tensile or compressive forces spaced from the foundation, such as it is necessary with other stationary cranes and hoisting devices and without requiring the use of a counter¬ weight, generally necessary in connection with mobile cranes. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in further detail below referring to the enclosed drawings, whereon Fig. 1A shows a first schematic plan view of a crane according to the invention attached to a founda¬ tion for an elongated body, Fig. IB illustrates a second schematic plan view of a crane according to the invention attached to a foundation for an elongated body, Fig. 2 is a top plan view of a foundation according to the invention for an elongated body, Fig. 3A is a first plan view of a particular embodiment of a crane according to the invention, and Fig. 3B is a sectional view of a particular embodiment of a crane according to the invention. Figures 1A and IB illustrate one embodiment of a crane 1 according to the invention as seen from the side and from a position behind the crane respectively. The crane 1 comprises two jibs 2 and a crossbar 3 connected between the jibs at their top ends 2' . The jibs 2 and the crossbar 3 are manufac¬ tured from a suitable steel profile. Other materials than steel may also be used. The jibs 2 are by their lower ends 2'' attached to a bearing pedestal 4 by means of bearings 5 with horizontal axes of revolution A. The bearings 5 are journal bearings but might also have been other types of bearings, e.g. ball bearings or roller bearings. The bearing pedestal 4 is attached to a foundation 6. The foundation 6 is in fact the very foundation intended for supporting an elongated body (no ' t shown in the drawing) to be erected by means of the crane 1. In the following portion of the specification the elongated body will be exemplified by a tower for a wind turbine without this being intented to admit any limitation in the field of applications for the crane. The crane l further comprises two telescopic hydraulic jacks 7 (only one of them shown in the drawings) extending between the jibs 2 and anchoring straps 8 attached to the foundation 6. The hydraulic jacks 7 are intended to serve the main purpose of tilting the jibs 2 forwards and backwards during the mounting of a wind turbine cap (not illustrated in the drawings) and an assembly of wind turbine blades (not illustrated in the drawings) . The hydraulic jacks 7 are intended also to serve a secondary purpose in assisting during the elevation and the lowering of the crane l before and after the erection of the wind turbine tower respectively (not illustrated in the drawings) . Each of the hydraulic jacks 7 comprises a piston (not illustrated in the drawings) together with a piston rod 9 and an anchoring eyelet 10 connected to the anchoring strap 8 and a cylinder 11 with an anchoring eyelet 12 attached to a strap 13 on the jibs 2. The conncection to the anchoring strap 8 and to the jibs 2 respectively, is implemented by means of bearings 14, 15 with horizontal pivot axes, preferably journal bearings. Other bearings may alternatively be used. The crane 1 further comprises a winch 16 located in the embodiment illustrated at the lower end 2'' of the jibs 2. The winch 16 operates a wire 17 extending upwards along the jibs 2 and parallel to them through a tackle 18 arranged at the crossbar 3 and further downwards towards the foundation 6. The wire 17 is provided at the remote end 19 with catching means 20, e.g. a hook as illustrated in the drawings. The winch 16 together with the wire 17 and the hook 20 are used during erection of the wind turbine tower and subsequently during the mounting of the wind turbine cap and blades on top of the tower. Figure 2 illustrates a foundation 6 according to the in¬ vention. The foundation 6 is provided with a wind turbine anchoring base 21. Anchoring base 4' for the bearing pedestal 4 for the jibs 2 and anchoring block 8' for the anchoring strap 8 for the hydraulic jacks 7 are embedded into the foundation 6. Reference is again made to figures 1A and IB. The foundation 6 illustrated in these drawings is adapted for large wind turbines and has a height h of about l metre and a width b of about 9 metres in both directions and is buried below a refence surface such as the surface of the ground J to a depth d of between l.5 and 2.0 metres measured from the ground surface to a top side 22 of the foundation 6. The bearing pedestals 4 and the anchoring straps 8 comprise distance pieces 23, 24 extending from the foundation 6 top side 22 to the ground surface J. Bearing pedestals 4 and anchoring straps 8 are secured to the foundation 6 in an arrangement permitting the wind turbine tower to extend between the jibs 2 and the hydraulic jacks 7. The anchoring straps 8 are located to either side of the anchoring base 21 for the wind turbine tower and bearing pedestals 4 have been displaced relative hereto with the horizontal axis of revolution A oriented parallel to the horizontal axis of revolution B for the bearings 14 in the anchoring strap 8. A brief description of the use of the crane 1 and the foundation 6 according to the invention will now be presen¬ ted. The initial step is the provision of the foundation 6 according to the invention. The foundation is cast on the site intended for the wind turbine following the excavation of a pit of an appropriate size and depth. Simultaneously the bearing pedestals 4 and the anchoring straps 8 are embedded in the foundation together with the anchoring base 21 for the wind turbine tower. Once the foundation 6 has set, it is possible to erect and secure the wind turbine tower to the foundation. The crane jibs 2 are mounted in the bearing pedestals 4 while the jibs are placed extending along the ground surface J. The top ends 2 of the jibs are then elevated from the ground surface by pulling the jibs by means of chains or other means connected to pulling apparatuses and to the jibs 2. Once the jibs have been elevated sufficiently, the hydraulic jacks 7 are connec¬ ted between the anchoring straps 8 embedded in the foundation and the straps 13 on the jibs 2. It is then possible to use the hydraulic jacks 7 to elevate the jibs further to the maximum elevation where the gripping means 20 on the wire 17 extends downwards to a position located just above the foundation anchoring base. In this position the jibs are inclined to an angle relative to the surface of the ground. The wind turbine tower is then placed in a position located below the crane and extending along the ground surface J. The gripping means 20 is moved downwards to the top of the wind turbine tower and the tower is erected by the winch 16 pulling the wire 17 with the gripping means towards the crossbar 3 at the upper ends 2 of the jibs. Following erection of the tower to a vertical position the tower is secured to the anchoring base 21. The following steps comprise the mounting of the wind turbine cap on top of the tower and the mounting on to the cap of a rotatable boss with a hub holding the wind turbine blades. Following completion of the stage of operation mentioned above gripping means 20 is located just above the wind turbine tower and is therefore not located in a position where it can readily be moved down to the surface of the ground for the purpose of hoisting the wind turbine cap and the blades to the intended location on top of the tower. The jibs 2 are therefore tilted forwards by the action of the hydraulic jacks 7 reducing the angle α. Gripping means 20 is hereby displaced forwards to a position in front of the tower from where it may be moved down towards the ground surface. The wind turbine cap is initially placed in front of the wind turbine tower base ready to be hoisted to the top of the tower after having moved the gripping means downwards and connected it to the wind turbine cap situated in front of the tower base. Once the wind turbine cap has been elevated completely to the top of the tower, the jibs 2 are tilted backwards by the action on the hydraulic jacks 7 with the purpose of displacing the wind turbine cap to a position immediately above the tower top. The wind turbine cap is then secured to the top of the tower. The last step is the attachment of the wind turbine blades. The blades are attached the the hub while the hub and the blades all are situated on the surface of the ground J. The jibs 2 are again tilted forwards by the action of the hydrau- lie jacks. The gripping means 20 is also displaced forwards to a position in front of the tower and in front of the wind turbine cap and then moved downwards to the ground surface J. The hub with the blades has previously been placed in front of the wind turbine base ready to be hoisted upwards to the wind turbine cap once the gripping means has been moved downwards and has been connected to the blades. Once the blades have been elevated to the wind turbine cap, the jibs may be moved into a position where the blades are located just at the intended position. The blades are then secured. Alternatively, the jibs 2 may be tilted by the action of the hydraulic jacks 7 in order to bring the blades into the proper intended position adjacent to the wind turbine cap. The operation carried out to erect the wind turbine could also be divided into more stages than mentioned above. Once the wind turbine has been completely assembled, the crane has served its purpose and the jibs are tilted forwards to a position where the jibs 2 again extend along the ground surface J. The hydraulic jacks 7 and the jibs 2 are dis- connected from the foundation 6. They may subsequently be connected to another foundation also provided with bearing pedestals 4 and anchoring straps 8 ready to assist during erection of another wind turbine. Figures 3A and 3B illustrate a particular embodiment of a crane according to the invention as seen from the side and as seen from a position above the means for securing the crane to a foundation 6 for a wind turbine respectively. The crane 1 comprises a jib 2 provided in the upper end 2' with a conventional hoisting gear 25. The jib 2 according to this embodiment is composed of five mutually telescopic parts 26. The jib 2 is by the lower end 2'' attached to a bearing pedestal 4 by means of a bearing 5 with a horizontal axis of revolution A. The bearing 5 may be any kind of bearing, preferably a journal bearing. The bearing pedestal 4 is one part of a bearing assembly 27 attached to the foundation 6 by means of at least one anchoring beam 28 extending horizontal¬ ly. The bearing assembly 27 may rotate relative to the anchoring beam 28 about a vertical axis B. The crane 1 may be provided with more anchoring beams 28 as illustrated in figure 3B. The foundation 6 is the very foundation intended for supporting an elongated body (not illustrated in the drawing) which is to be erected assisted by the crane. The dot-and-dash line 29 illustrates the outline of a wind turbine tower which would be the prefered elongated body which the crane 1 is adapted to elevate. The crane further comprises two telescopic hydraulic jacks 7 (only one illustrated in the drawings) extending on respec¬ tive sides of the jib 2 between the jib and anchoring straps 8 constituting together with bearing pedestal 4 parts of the bearing assembly 27. The hydraulic jacks 7 serve the ex¬ clusive purpose of tilting the jib 2 forwards and backwards during the fitting of the wind turbine cap and the wind turbine blades (neither of them illustrated in the drawings) . The crane is furthermore provided with integrated hydraulic jacks (not illustrated in the drawings) extending internally in the jib 2 and adapted for displacing the telescopic parts 26 of the jib mutually. The crane 1 is attached to the foundation 6 by fitting the anchoring beams 28 with bolts 30 extending from the founda¬ tion 6 and through bolt holes 31 in the anchoring beams 28. In the embodiment illustrated in figure 3B the anchoring beams 28 can be displaced telescopically from a first position to a second position with the purpose of securing an extended supporting surface. This is however only feasible in case the wind turbine foundation has apropriate dimensions. The operation of the crane according to the embodiment of the invention illustrated in figures 3A and 3B is essentially similar to the operation of the crane according to the embodiment of the invention illustrated schematically in the figures 1A and IB. In the above the invention has been described with reference to a schematic particular embodiment of the crane and of the foundation. These embodiments are not intended to limit the scope of the invention which is defined in the claims but is merely intended to illustrate feasible embodiments of the invention. The crane may comprise one, two as illustrated or more jibs. The crossbar could be dispensed with or it could be replaced by a further jib extending forwards and not transversely relative to the jibs. The hydraulic jacks could be replaced by other double acting control means and might be implemented in the form of one, two as illustrated or more devices. The winch illustrated in figures 1A and IB could be located at other positions related to the crane instead of at the lower end of the jibs and the gripping means might comprise other means than a hook.

Claims: PATENT CLAIMS 1. A crane for the erection of elongated bodies to a vertical position, which crane comprises a jib which may be tilted about a first bearing with a horizontal axis of rotation, said first bearing being provided at a lower portion of the jib in connection with a support plane and at least one second bearing, said second bearing being provided at a lower portion of a double-acting lifting and lowering mechanism also in connection with the support plane, and the uppermost end of said lifting and lowering mechanism being secured to the jib, c h a r a c t e r i z e d in that the support plane constitutes the foundation of the elongated body, that the first bearing for the crane is anchored to the foundation by means of a first anchoring, said first an¬ choring for the first bearing being arranged between a mounting area for the elongated body and in an opposite edge area of the foundation seen relative to the first anchoring, and in that the at least one second bearing for the crane is anchored to the foundation by use of at least one second anchoring, said second anchoring being arranged at a distance from the first anchoring in a direction from the first anchoring opposite a direction from the first anchoring to the edge area. 2. A crane according to claim 1, c h a r a c t e r i ¬ z e d in that the double acting lifting and lowering mechanism comprises a hydraulic telescopic jack with a piston comprising an anchoring eyelet connected to the anchoring strap by means of a bearing and a cylinder also comprising an anchoring eyelet connected to a strap on the jib by means of a bearing. 3. A crane according to claim 1 or claim 2, c h a - r a c t e r i z e d in, that at least one jib comprises a first and a second jib each of said jibs extending from a respective lower end adjacent to the supporting surface upwards to a respective upper end, and in that a crossbar extends between the respective upper ends of the first and the second jib. 4. A crane according to any of the preceding claims, c h a r a c t e r i z e d in that the bearing pedestal and the anchoring strap comprise distance pieces extending from a top side of the foundation to bearings provided in the bearing pedestal and in the anchoring strap respectively. 5. A crane according to any of the preceding claims, c h a r a c t e r i z e d in that the crane is provided with a winch arranged adjacent to the jib, said winch being provided with a wire extending from the winch through a tackle arranged adjacent to an upper end of the jib and down¬ wards towards the foundation. 6. A crane according to any of the preceding claims, c h a r a c t e r i z e d in that at least one of the jibs is provided with a further jib in the upper end, said further jib extending forwards relative to the jib. 7. A crane according to any of the preceding claims, c h a r a c t e r i z e d in that the bearings for connec- ting the jib to the bearing pedestal and for connecting the anchoring eyelet to the anchoring strap and for connecting the anchoring eyelet to the strap on the jib respectively, comprise journal bearings. 8. A crane according to any of the preceding claims, c h a r a c t e r i z e d in that the bearing pedestal, the anchoring strap and the strap on the jib are disconnectable. 9. A foundation for a crane according to any of the preceding claims, c h a r a c t e r i z e d in that the foundation comprises an anchoring base for an elongated body and furthermore at least one bearing pedestal and at least one anchoring strap. 10. A method for the erection of a wind turbine whereby a crane and a foundation according to any of the preceding claims are used, said wind turbine comprising a wind turbine tower, a wind turbine cap and wind turbine blades, c h a ¬ r a c t e r i z e d in that the wind turbine tower is erected to a vertical position by means of the gripping means, that the crane is tilted forwards lowering the angle a and that the wind turbine cap is hoisted to the top of the wind turbine tower also by means of the gripping means, that the crane is tilted backwards and the wind turbine cap mounted on top of the tower, that the crane is tilted forwards again, that a hub with the wind turbine blades is hoisted to the wind turbine cap also by means of the gripping means and that the hub with the wind turbine blades is mounted in the wind turbine cap.

Inventors: OLESEN JOHN THOMAS, OLESEN, JOHN, THOMAS
Applicants: MICON AS, OLESEN JOHN THOMAS, MICON A/S, OLESEN, JOHN, THOMAS
Application year: 1995
Main classification: E04H12
IPC codes: B66C23, F03D1