EP2659074A1

EP2659074A1 - Cross hatching structured mast

Info

Publication number: EP2659074A1
Application number: EP11853099.7A
Authority: EP
Inventors: Pertti Niemi
Original assignee: VaasaBall Wind Products Oy
Current assignee: VaasaBall Wind Products Oy
Priority date: 2010-12-28
Filing date: 2011-11-23
Publication date: 2013-11-06
Also published as: FI20106374A0; WO2012089908A1; FI122863B

Abstract

The object of the invention is a cross hatching structured mast (3, 3'), the lower part (3') of which is connected to a base (4), and which is triangular or multi-angular in cross-section in the transverse direction perpendicular to the longitudinal direction, and the upper part of which mast (3, 3') is comprised of two or more modules (300) arranged on top of one another. The module (300) is comprised of panel-type modular elements (30, 31, 32, 33, 34 and 36) removably attached in conjunction with one another by mechanical fastening elements (50, 51), which include a corner panel (30) located in each corner of the module (300). The outer edges (30a) form the corners of the module (300) over the entire longitudinal distance of the module (300) and their inner edges (300b) extend over a distance towards the centre of the module (300). In conjunction with both sides of the outer edges (30a) of each corner panel (30) are connected two pivot panels (31), on the inner edges (31b) of which are arranged bending parts. They are bent with respect to the plane determined by the corner panel (30) into a bending angle (α) in opposite directions. Support panels (32) are connected in the longitudinal direction of the module (300) in conjunction with the first and/or second end of each bending part (31), whereupon the outer surfaces (32c) of the support panels (32) of two adjacent corners pass through the same plane. Elongated connecting panels (33) are connected at both ends (33a, 33b) to the corresponding support panels (32) of the respective two adjacent corners. The reinforcing elements (36) can be fitted in conjunction with the outer edge of each corner panel and the outer edge of each pivot panel.

Description

Cross hatching structured mast

The present invention relates to a cross hatching structured mast, the lower part of which is connected to a base and which is triangular or multi-angular in cross-section in the transverse direction perpendicular to the longitudinal direction, and the mast of which is comprised of two or more modules arranged on top of one another.

Previously are known cross hatching structured masts used especially as masts for wind power plants or base stations. Structurally, cross hatching structured masts typically have a tubular structure. In other words, a mast part, that is, a module is comprised of a vertical tube positioned in each corner (three or four), between which are connected tubular connecting arms. They are connected to the vertical tubes by welding or by screw-and- nut joints. High cross hatching masts, as well as conventional masts, typically widen longitudinally downwards in their lower part area. Masts having this type of structure are manufactured, for example, by the Finnish company Rautaruukki. As another example can be mentioned the Swedish company Wibe which manufactures cross hatching masts with connecting arms connected to the vertical tubes by means of nut-and-screw joints.

One application of a cross hatching mast, known as such, of a wind power plant with a triangular cross-section is disclosed in the Applicant's Finnish patent application no. 20105751. In this application, the mast is connected to a base comprised of spherical pieces and positioned or anchored to the bottom of the sea, the structure of the base being disclosed in patent application no. 20105751. This type of cross hatching mast made of panel- type elements is lighter than conventional tubular masts and easier to mount, because it can be brought to the installation site in smaller and lighter parts than tubular masts (for example as elements which can be fitted on top of one another). A disadvantage of such cross hatching masts is, firstly, that the strength of the cross hatching mast is determined by the strength of the vertical elements and the connecting arms (in other words the material and the material thickness). Therefore, parts of different strength have to be designed and manufactured for different applications (such as wind power plant masts and base stations), which in turn increases the number of parts differing from one another. Another problem arises in joining the tubular parts together, where welding is required. Welded seams increase the risk of weak sections forming in the basic structure of tubular cross hatching masts and of a cross hatching mast comprised of panel-type elements. For example, the cross hatching masts sold under the Wibe brand are made by connecting the arms by means of lugs welded to the ends to counter-lugs welded to the vertical tubes by means of a screw-and-nut joint. All previously known masts are structurally such that they are either assembled horizontally and then lifted up with special equipment or built up, for example, of elements placed on top of one another in order from bottom to top. The aim of the present invention is to provide a cross hatching structured mast by means of which the above disadvantages are essentially avoided. The aim is thus to provide a mast, the strength of which is easy to adjust for different sites and purposes. The aim is also to provide a mast with a basic structure which does not include welded seams, and which allows the mast to be assembled in a new manner, essentially avoiding the difficult stages of assembly mentioned above.

The above aim is achieved in accordance with the present invention by means of a cross hatching structured mast which is characterised in that the module is comprised of panel-type modular elements removably attached in conjunction with one another by mechanical fastening elements including at least: a corner panel located in each corner of the module, the outer edges of which form the corners of the module over the entire longitudinal distance of the module and the inner edges of which extend over a distance towards the centre of the module; two pivot panels connected in conjunction with both sides of the outer edges of each corner panel, on the inner edges of the pivot panels being arranged bending parts which are bent with respect to the plane determined by the corner panel into a bending angle in opposite directions; support panels which are connected in the longitudinal direction of the module in conjunction with the first and/or second end of each bending part, whereupon the outer surfaces of the support panels of two adjacent corners pass through the same plane; elongated connecting panels which are connected at both ends to the corresponding support panel of the respective two adjacent corners; and reinforcing elements which can be fitted in conjunction with the outer edge of each corner panel and the outer edge of each pivot panel.

A cross hatching mast having such basic structure comprised of panel-type pieces makes it possible to provide the corners of the mast with reinforcing elements, if necessary. The advantage of this is that the basic structure of the hatching can be made of similar (in strength) basic parts irrespective of the application and be reinforced according to application with reinforcing elements of specific strength. Furthermore, this type of structure makes it possible for each part of the modular element to be easily joined with mechanical joining means to form the mast and no welding work is required in the manufacture of the parts or the assembly of the mast. The module elements can, in addition, be brought to the location of the mast for assembly and thus it is easy to bring and mount the mast also to places where erection is difficult. Preferred embodiments of the present invention are disclosed in the dependent claims. A preferred embodiment of the invention is disclosed in greater detail in the following, with reference to the accompanying drawings, in which:

Figure 1A shows a general side view of the cross hatching mast according to the invention applied to a wind power plant,

Figure IB shows a top view of the cross hatching mast of Figure 1A,

Figure 2 shows a partial side view of the cross hatching mast,

Figure 2A shows a cross hatching mast module from the side,

Figure 3 shows a top view of one corner of the cross hatching mast

module in partial cross-section,

Figure 3A shows diagrammatically a lifting device when connected to the inner edges of the corner panels,

Figure 4 shows a side view of the corner panel according to the invention,

Figures 5A-5C show the pivot panel according to the invention,

Figure 6A shows a side view of the support panel according to the

invention and the connecting panels connected to it,

Figure 6B shows an end view of the support panel of Figure 6A,

Figures 7A and 7B show a side and end view of the connecting panel, Figures 8A and 8B show a top and side view of the joining panel of two

intersecting support panels, Figure 9A shows a side view of the reinforcing element according to the invention,

Figure 9B shows a side view of the cross-section of the reinforcing element according to the invention,

Figure 10a shows a top view of the fastening element of the guy wire

according to the invention, and Figure 10b shows a side view of the guy wire shown in Figure 10b.

Figure 1 thus shows a general view of the cross hatching mast according to the present invention. The cross hatching mast is marked by reference numeral 3 (30- The cross hatching mast 3 according to the invention is here applied to a wind power plant located in the sea, which is marked by reference numeral 1.

The wind power plant 1 comprises a centre part 2a, around the essentially horizontal shaft of which blades or vanes 2b are arranged to rotate. The centre part 2a and the wind power plant 1 are provided with means known as such (e.g. a generator) for recovering the energy obtained from the rotation of the blades 2b and transferring it further and thus these means are not described in any greater detail here. The upper end of the mast 3 is connected to the lower surface of the centre part 2a and it extends vertically or essentially vertically below the water level (sea level) w in contact with the base. The base is here marked with reference numeral 4 and it is supported by its lower end on the sea bottom B. The base 4 is here comprised of four spherical objects 4a, 4b, 4c and 4d. The locations of these with respect to one another are arranged in the desired positions by means of joining arms 5, 5 and 7. In a top view of the embodiment of Figures 1A and IB, the centres of the three spherical objects 4b, 4c and 4d are located essentially at the apices of an equilateral triangle. In the centre of the imaginary equilateral triangle is in addition located a fourth spherical object 4a, in conjunction with which the cross hatching mast 3 (3') of the wind power plant 1 is connected. A more detailed structure of the spherical object is described in the Applicant's earlier patent application FI 20105751 and it is, therefore, not described in greater detail here. Different variations of the base are disclosed in the Applicant's earlier application FI 20105751, which may also be applied within the scope of the present invention. For example, the arm shown in Figure 13 of the said application, which extends below sea level, can be made with the mast construction according to the invention.

Perpendicularly to the longitudinal direction, the cross-section of the mast 3 is preferably the shape of an equilateral triangle. The mast 3 is provided with guy wires 41 which are connected at their lower ends to joining parts 40 arranged in the spherical objects 4b, 4c, 4d. The number of guy wires may vary according to application.

It should be noted that the mast according to the invention is also suitable for erection on land, in which case as a base can be used, for example, footings or similar foundations cast of concrete on the ground, to which the lower ends of the guy wires can be fixed in addition to the mast. The fixing of the upper end of the guy wire 41 (guy wires) to the mast 3, 3' is described below. The general structure of the cross hatching mast 3 (3') according to the invention and especially of the module, is shown more clearly in Figures 2, 2A and 3. Figure 2 shows a partial enlargement of Figure 1A, Figure 2A shows one module 300 taken from Figure 2, and Figure 3 shows a top view of one corner of a module 300 of the cross hatching mast 3 in partial cross section. The second module 300 in Figure 2A is shown in broken lines as an example of how the modules 300 are positioned one upon the other with respect to one another. The lower part 3' of the mast 3 is preferably a part 3' separate from the mast, a so-called mast shoe 3', to which the mast can be connected as its longitudinal extension. Between the lower part 3' and the actual mast 3 can be arranged an articulation, hinging 301 or the like. The mast 3 can be turned in the horizontal direction or essentially horizontal direction, close to the surface w of the ground or water, for example, to connect the wind power plant 1 and the centre part 2 to the mast 3.

The module 300 is made of panel-type modular elements 30, 31, 32, 33, 34, 36, as material for which have preferably been used the materials

conventionally used for cross hatching structured masts, such as metal, metal alloys and/or a composite.

In this embodiment, the module 300 comprises three elongated corner panels 30, an example of which is shown in Figure 4. The corner panels 30 are each positioned in the corners of the module 300, one of which corners is shown from above in Figure 3. The outer edges 30a of the corner panels 30 form the corners of the module 300 over the entire length of the module, and preferably a base for fastening the other panel-type modular elements of the module 300. For this purpose, the outer edge 30a is provided with openings 30a' for fastening the other modular elements with mechanical fastening elements 50, such as screw-and-nut joining elements, to the corner panel 30. When looking at Figure 3, it can be seen that the inner edge 30b of the corner panels 30 extends by a distance towards the centre of the module 300.

To each corner panel 30 are connected pivot panels 31 by means of the above-mentioned mechanical fastening elements 50. A preferred

embodiment of a single pivot panel 31 is shown in Figures 5A-5C. The pivot panels 31 are connected at their outer edges 31a in conjunction with both sides of the outer edges 30a of the corner panel, that is, on opposite sides of the corner panel 30. For this purpose, the outer edge 31a of the pivot panel is provided with openings 31a' for fastening the pivot panel 31 with mechanical fastening elements 50, such as screw-and- nut joining elements, to the corner panel 30. The planar inner edges 31b arranged as an extension of the outer edges 31a of the pivot panels 31 form the bending parts. They are at a bending angle a with respect to the plane determined by the corner panel 30 (and with respect to the outer edges 31a of the pivot panel 31). The bending parts 31b of opposing pivot panels 31 are turned in opposite directions, thus forming projections opening away from one another on their inner edges 31b. The bending angle a of the projections is preferably selected in such a way that the outer surfaces of the bending parts 31b of two pivot panels 31 in adjacent corners pass through the same or at least essentially the same plane. The bending angle of the outer edges 31a of a mast having the cross-sectional shape of an equilateral triangle is 30°.

Similarly, it may be mentioned that the bending angle a is 90° for a mast with a rectangular cross-section, 54° for a mast of pentagonal cross-section, 60° for a mast of hexagonal cross-section or 67,5° for a mast of octagonal cross-section. The bending parts 31b are also provided with openings 51' (Figure 5B) for connecting other modular elements with mechanical fastening elements. Both the corner panel 30 and the pivot panels 31 are elongated panels having a length equalling the height of the module 300. It should be noted that the height of the module 300 (length of corner panel 30 and pivot panel 31) is typically 3-6 metres, preferably 3.5-4.5 metres and most preferably 3.8 metres, but it may vary outside the said limits depending on the application.

In conjunction with the bending parts 31b of the said pivot panels 31 are connected support panels 32. A preferred embodiment of the support panel 32 is shown in Figures 6A and 6B. The support panels 32 are also connected in conjunction with the bending parts in a similar manner with mechanical fastening elements, for which purpose openings 32' are formed in the support panels 32. The positions of the openings 32' are located in the support panels 32 at points which correspond to the positions of openings 5 formed in the bending parts 31b when the support panel 32 is in place. In this embodiment, support panels 32 are arranged within the area of the first and second (upper and lower) end of the bending parts 31b of each pivot plate 31, whereupon they form extensions to the bending parts 31b in those areas. The joint of the support panels 32 is formed in such a way that the outer surfaces 32c of the support panels 32 of adjacent corners pass through the same plane. The inner edge 32b of the support panels 32 is bent to increase the rigidity of the support panel 32.

The corners of the module with the structure described above are connected to one another preferably with elongated connecting panels 33 fastened diagonally in conjunction with the support panels 32. A preferred

embodiment of a single connecting panel 33 is shown in Figures 7A and 7B. There are preferably one or two connecting panels 33 per each side (the side between two adjacent corners) of the module 300. In the example there are two of them (see Figure 2A), which are connected crosswise to the module 300 with mechanical fastening elements in such a way that the lower ends 33a of the connecting panels 33 are connected to corresponding lower support panels 32 of two adjacent corners (the outer surfaces 32c of the panels passing through the same plane) and the upper ends 33b to the opposite support panels 32 of corresponding adjacent corners (the outer surfaces 32c of the panels passing through the same said plane). There are, therefore, three pairs of connecting panels per module, the connecting panels 33 of the pair of connecting panels being crosswise on each side of the module. The intersecting connecting panels 33 are connected to one another by means of a joining panel 34 at the point where the joining panels intersect. A preferred embodiment of the joining panel 34 is shown in Figures 8A and 8B. The joining panel 34 is a square panel in which are formed openings 34', which are aligned with the openings (not shown) provided in the connecting panels 33 when the joining panel 34 is mounted in place. Thus, the connecting panels 33 and the joining panel 34 can be connected to each other by means of screw-and-nut joints through the openings and the cross hatching structure is thus made rigid.

This type of modular structure comprised of panel-type elements makes it possible to easily reinforce the module for different applications. Thus, according to the invention, the mast 3, especially the modules 300, are provided with reinforcing elements 36, a preferred embodiment of which is shown in Figures 9A and 9B. The cross-section of the reinforcing element 36 is the shape of the letter U or a stretched letter U, which means that it can be fitted in conjunction with the outer edge 30a of the corner panel 30 of each corner and the outer edge 31a of the pivot panels 31. The reinforcing element 36 is connected to these by screw-and-nut joints, by means of which the corner panel 30 and pivot panels 31 are joined together. For this purpose, also the reinforcing element 36 is provided with openings 36' located at appropriate points. The material and thickness z of the reinforcing element 36, that is, the properties which determine the strength of the reinforcing element 36, may be selected according to application. The other elements of the basic structure of the module 300 (and mast) are always similar (e.g. similar corner panels, similar pivot panels, etc.) irrespective of the application.

The reinforcing element 36 is preferably made to receive separate fastening means 37 of the guy wires 41, shown in Figures 10A and 10B, at an optional point in the elevation of the mast 3. Here, the fastening means 37 are comprised of two panel-type elements 37a and 37b arranged at a distance from one another by means of two spacers 37c. These fastening means 37 may be fastened to the mast 3 by means of the same screw-and-nut joining means 50 as the reinforcing element 36. For this purpose, the panel-type elements 37a and 37b of the guy wire 41 fastening means, in the slot 37d between which the reinforcing elements 36 can be taken, are provided with openings 37'. The openings may be aligned with the openings 36' provided in the reinforcing element 36 for the screw-and-nut joining means 50. The fastening means 37 are also provided with lugs 37e, in which are formed attachment means 37f, such as a fastening opening, to which the guy wires 41 are fastened at their upper end.

The mast 3 made of modules 300 is preferably provided with elevator means 100 (see Figure 3). The elevator means 100 are connected to the mast 3 in conjunction with gearing 30b' formed on the inner edges 30b of the corner panels 30 of at least one corner. For this purpose, the elevator means 100 are provided with a lifting wheel (not shown) which is in contact with the operating mechanism, the lifting wheel being in contact with the gearing 30b'. In a finished mast 3, the elevator means 100 can be used in connection with the maintenance measures of the mast 3 and, for example, of a wind power plant 2.

Instead of the elevator means, it is advantageous to connect lifting means 100' to the mast 3 at its assembly stage, as shown diagrammatically in Figure 3A. The lifting means 100' can be utilised at the assembly stage of the mast 3 in the following manner. Figure 3A shows a shoe 3' supported by a spherical object 4a. As its vertical extension are positioned modules 300 which thus form the actual mast 3. Between the corner panels 30 of the modules 300 remains a space in which the lifting device 100' is fitted. The lifting device 100' comprises a foot 101, which is supported on the upper part of the spherical object 4a. In the upper part of the foot 101 are arranged actuators 102, 103 and a lifting element or elements 104, which the actuators 102, 103 move. The actuators include a motor 102 and gears 103 which are arranged to rotate the lifting element 104 (or lifting

elements), which in this case is a gearwheel. The gearwheel or gearwheels

104 are fitted in conjunction with the gearings 30b' arranged on the inner edges 30b of the corner panel 30 or panels (see Figure 4). Figure 3A shows that the foot 101 is made so high that the actuators 102, 103 positioned in the upper part of the foot 101, and especially the gearwheels 104 are located vertically on a level which is higher than the joint height of the shoe 3' (if one is used) and one module 300. Thus, the new structural feature of the mast assembled of panel-type modular elements makes it possible to assemble the mast from its lower end. This is done by utilising the gearing 30b' of the corner panels 30 in such a way that, while the gearwheels 104 rotate in the gearing 30b', the lifting device 100' lifts a finished mast part so far upwards that the next module 300 can be assembled at the lower end of the finished mast part. Once the mast 3 is completed, the lifting device 100' can be detached for use in assembling another mast and it can be replaced by an elevator which ascends on the gearings 30b' of the corner panels 30. The elevator 100 can also be mounted above the lifting device 100' during the mast assembly stage.

The present invention is not limited to the embodiments disclosed, but may be applied in many ways within the scope of protection determined by the claims presented.

Claims

1. A cross hatching structured mast (3, 3 , the lower part (3') of which is connected to a base (4), and which is triangular or multi-angular in cross- section in the transverse direction perpendicular to the longitudinal direction, and the upper part of which mast (3, 3 is comprised of two or more modules (300) arranged on top of one another, characterised in that the module (300) is comprised of panel-type modular elements (30, 31, 32, 33, 34 and 36) removably attached in conjunction with one another by

mechanical fastening elements (50, 51) including at least:

- a corner panel (30) located in each corner of the module (300) and the outer edges (30a) of which form the corners of the module (300) over the entire longitudinal distance of the module and the inner edges (30b) of which extend over a distance towards the centre of the module (300),

- two pivot panels (31) connected in conjunction with both sides of the outer edges (30a) of each corner panel (30), on the inner edges (31b) of the pivot panels being arranged bending parts, which are bent with respect to the plane determined by the corner panel (30) into a bending angle (a) in opposite directions,

- support panels (32) which are connected in the longitudinal direction of the module (300) in conjunction with the first and/or second end of each bending part (31), whereupon the outer surfaces (32c) of the support panels (32) of two adjacent corners pass through the same plane, - elongated connecting panels (33) which are connected at both ends (33a, 33b) to the corresponding support panel (32) of the respective two adjacent corners, and - reinforcing elements (36) which can be fitted in conjunction with the outer edge of each corner panel and the outer edge of each pivot panel.

2. A mast (3, 3 as claimed in claim 1, characterised in that the inner edge of the corner panel is provided with means in conjunction with which the elevator 100 can be connected.

3. A mast (3, 30 as claimed in claim 1 or 2, characterised in that the inner edge (30b) of the corner panel (30) is provided with means (30b0 in conjunction with which can be connected a lifting device (1000 at the assembly stage of the mast (3, 30 for lifting two or more joined modules (300) upwards to assemble and/or join the next module (300) to the lower end of the joined modules (300).

4. A mast (3, 30 as claimed in any of the above claims 1 to 3,

characterised in that the said bending angle of the bending part may be selected from at least the following angles: 30° for a mast of triangular cross-section, 90° for a mast of rectangular cross-section, 54° for a mast of pentagonal cross-section, 60° for a mast of hexagonal cross-section or 67,5° for a mast of octagonal cross-section.

5. A mast (3, 30 as claimed in any of the above claims 1 to 4,

characterised in that the material and/or thickness (z) of the reinforcing element (36) may be selected to meet the strength requirements of the application of the mast (3, 30-

6. A mast (3, 3 as claimed in any of the above claims 1 to 5,

characterised in that the mechanical fastening elements are screw-and-nut fastening elements and that each modular element (30, 31, 32, 33, 34, 36) is provided with openings for passing the screw-and-nut fastening elements through them.

7. A mast (3, 3 as claimed in any of the above claims 1 to 6,

characterised in that to the reinforcing element (36) can be fastened the fastening means (37) of the guy wires (41) of the mast (3, 30 at optional points in the longitudinal direction of the mast (3, 3 and in an optional number in accordance with how many guy wires are required for the respective structural solutions.

8. A mast as claimed in claim 7, characterised in that the fastening means (37) comprise openings (370 which may be aligned with the openings (360 provided in the reinforcing element for passing the screw-and-nut fastening elements (50, 51) through them, and attachment means (37f), to which the end of a guy wire (41) may be fastened.