Patent Application
20130212972
1. Field of the Invention
The present invention relates to a tower and a wind turbine generator provide with the tower.
2. Description of Related Art
Generally, a tower in a wind turbine generator is constructed by stacking and connecting a plurality of tubular tower sections in the vertical direction on a construction site. This is because a tower having several tens of meters in length is used for such as a wind turbine generator, and thus it is difficult to transport a completed tower to a construction site. For this reason, the tower is transported to the construction site in a state in which the tower is divided into the tower sections of transportable sizes.
Generally, as disclosed in PCT International Publication No. WO 2009/028092 A1 (hereinafter referred to as “Patent Literature 1”), an axial end of each tower section has a flange, and a tower is constructed by joining the flanges.
However, the connection of the tower sections by flange joint as disclosed in Patent Literature 1 has the following problem.
When receiving a wind force, the tower is bent, applying a load on a member that keeps binding at the junction between the tower sections. Although the yield strength required to address the load increases with an increase in size of the wind turbine generator, it is difficult to make the outer diameter of the tower larger than the existing size due to limitation upon transport. Under such a situation, in the case of a flange joint as disclosed in Patent Literature 1, the outer diameter of the flange is also limited by the outer diameter of the tower having limitation upon transport, and thus it is difficult to increase the number of bolts arranged at the flange. As a result, further improvement in the yield strength of the flange junction cannot be expected, and it has become difficult to meet a required yield strength.
Specification of U.S. Patent Application Publication No. US 2010/0071275 A1 (hereinafter referred to as “Patent Literature 1”) proposes connection of the tower sections by frictional joint. However, a high assembling accuracy is required to vertically install the vertical tower by directly connecting wall surfaces constituting the outer shape of the tower sections to each other. Further, the cylindrical tower section is molded by rounding and joining a steel plate. According to the manufacturing method, it is difficult to make the cross section a perfect circle. When the upper and lower tower sections having the cross section of non-perfect circle are butted each other, a misalignment between the tower sections is easy to be generated. A high manufacturing accuracy is required to sufficiently reduce the misalignment. That is, implementation of the invention described in Patent Literature 2 leads to an increase in manufacturing costs.
Specification of U.S. Patent Application Publication No. US 2011/0138729 A1 (hereinafter referred to as “Patent Literature 3”) discloses a configuration in which vertical frames and horizontal frames provided on wall surfaces of the tower sections, in place of the walls surfaces of the tower sections, are frictionally joined to each other. However, with the complicated configuration having a lot of junctions, temporary assembling needs to be performed in a factory to ensure the assembling accuracy on the construction site, disadvantageously leading to an increase in manufacturing costs.
Thus, in achieving an increase in the wind turbine generator in size without causing a substantial increase in costs, there is a demand for a connection structure for the tower sections having yield strength necessary for the junction of the tower sections.
The present invention is made in consideration of the above-mentioned situation and intends to provide a tower that includes a junction having a sufficient yield strength and that can easily ensure the accuracy of tower sections to be used, as well as to provide a wind turbine generator having the tower.
To solve the above-mentioned problems, the present invention adopts the following solutions.
A tower according to the present invention is a tower configured by stacking a plurality of tower sections in a vertical direction and connecting the tower sections to each other. The tower includes a connecting member arranged in the tower section, the connecting member dividing an inside of the tower section into a plurality of regions in a horizontal plane, and having one end connected to an inner wall of the tower section and the other end connected to the inner wall of the tower section or another connecting member, and a frictional joint part for connecting by frictional joint the connecting member to another connecting member connected to another adjacent tower section.
According to the present invention, in connecting the adjacent tower sections, since the connecting members provided in the respective tower sections are restricted each other by use of the frictional joint part for performing connection by frictional joint, the connecting operation using the frictional joint part can be performed in the inside of the tower. For this reason, the amount of operations at high elevations requiring, for example, scaffolding in the outside of the tower can be reduced, thereby increasing safety.
When outer wall surfaces constituting the outer shape of the plurality of tower sections need to be butted and directly connected to each other, it is required to match the shapes of the outer wall surfaces of the tower sections with each other at a high accuracy. On the contrary, according to the present invention, since the tower sections are connected to each other via the connecting members provided in the tower sections, the tower sections can be connected to each other without requiring a high accuracy so much. This is because it is no need to match the shapes of the outer wall surfaces of the tower sections with each other throughout their circumferences, positions of the connecting members of the upper and lower tower sections only need to match to the extent that the connecting members can be connected to each other.
Since the connecting member is provided so as to divide the inner region of the tower section into the plurality of regions, the section modulus of the tower section can be increased, and thus the rigidity of the tower section itself can be improved.
In the case where the frictional joint part is exposed external of the tower, in order to improve weather resistance, treatment such as touch-up coating may be needed. However, according to the present invention, since the frictional joint part exists within the tower, the treatment for improving the weather resistance of the frictional joint part can be omitted.
At a junction between the vertically stacked tower sections, the connecting members connected to each other by frictional joint denote the connecting member provided in each of the two adjacent upper and lower tower sections 2. As the frictional joint part, a splice plate installed in contact with the connecting member and a fastening bolt are generally used.
In the above-mentioned invention, it is preferred that the connecting member is in a shape of a flat plate.
By making the connecting member in the shape of a flat plate, a higher manufacturing accuracy than that of the cylindrical outer wall surface of the tower section can be ensured. This can reduce a misalignment between the connecting members in position in connecting the tower section to each other. In addition, by adopting the connecting member in the shape of a flat plate, the splice plate in close contact with the connecting member can be in a shape of a flat plate, thereby easily ensuring a sufficiently high manufacturing accuracy.
In the above-mentioned invention, it is preferred that an operating manhole is formed in the connecting member.
Even when the connecting member is in the shape of a flat plate, by forming the operating manhole in the connecting member, the operator and so on can pass through the connecting member even in operations in the tower section divided by the connecting member, which improves the workability.
In the above-mentioned invention, the connecting member may extend to a position other than a centroid of a horizontal cross section of the tower section.
Since the connecting member extends on the position other than the centroid (center in the case of the circular cross section) of the horizontal cross section of the tower section, as compared to the case where the connecting member extends on the centroid of the cross section of the tower section, a central region containing the centroid of the cross section of the tower section can be made a vacant region.
By providing a space vertically penetrating the tower, which corresponds to this vacant region, an elevator for transporting the operator and equipment necessary for operating the facility at maintenance or the like can be installed in this space, and when the tower is applied to the wind turbine generator, the wind turbine generator can be operated more easily.
In the above-mentioned invention, the tower sections on the lower side of the tower may be connected to each other by use of the connecting members, and the tower sections on the upper side of the tower may be connected to each other by use of flanges provided at respective ends.
A bending moment generated in the tower due to effect of the wind force and so on becomes larger as it is closer to the lower side of the tower, that is, the foundation part. As this bending moment is larger, the yield strength as a force necessary for keeping connection between the tower sections becomes larger. At the junction between the tower sections, which is relatively close to the foundation part of the tower, connection using the connecting members according to the present invention is suitable, and at the junction between the tower sections, which is relatively close to the top of the tower, the bending moment becomes relatively small. For this reason, a force necessary for maintaining connection between the tower sections becomes smaller. Thus, at the junction between the tower sections, which is relatively close to the top of the tower, for example, the tower sections may be connected to each other by use of the flanges provided at respective ends as conventional. With such a configuration, since the bolts are arranged along the outer periphery of the tower, the number of installed bolts can be minimized. Further, when the connecting member and the splice plate are not used, the weight of the upper portion of the tower can be reduced and the thickness of the wall surface of the tower can be minimized.
In the above-mentioned invention, the connecting member may be arranged to be in a shape of a cross when viewing the tower section in the horizontal plane (in a horizontal cross sectional view).
Alternatively, the connecting member may include a plurality of connecting members that extend in one direction to have both ends connected to the inner wall of the tower section and that are in parallel to each other.
Alternatively, the connecting member may include a first connecting member that extends in one direction to have both ends connected to the inner wall of the tower section, and a second connecting member may have one end connected to the inner wall of the tower section and the other end connected to a substantially midpoint of the first connecting member to form a substantially right angle with the first connecting member.
Alternatively, the connecting member may include a plurality of connecting members that each extend in one direction to have one end connected to the inner wall of the tower section, and that have the other ends, respectively, connected to each other.
Alternatively, the connecting member may be a plurality of connecting members that extend in one direction to have both ends connected to the inner wall of the tower section, and the plurality of connecting members may be arranged to form a polygonal shape in contact with the inner wall of the tower section when viewing the tower section in a horizontal plane (in a horizontal cross sectional view).
The present invention may be a wind turbine generator having the above-mentioned tower.
By providing the tower, the junction has a sufficient yield strength, and the accuracy of the used tower sections can be easily ensured. As a result, it is possible to realize a large-sized wind turbine generator requiring a large yield strength at the junction between the tower sections, and to reduce costs necessary for construction of the wind turbine generator.
An embodiment of a tower in a wind turbine generator according to the present invention will be described below with reference to the drawings.
As shown in
The tower 3 is configured by stacking a plurality of cylindrical tower sections 2 in the vertical direction and connecting the tower sections 2 to each other.
As shown in
The vertically adjacent tower sections 2 are connected to each other by frictional joint. Specifically, the tower sections 2 are fastened by use of high-tensile bolts (frictional joint part) 24 so that splice plates (frictional joint part) 22 extending over the connecting walls 20 provided in the vertically adjacent tower sections 2 are brought into close contact with the connecting walls 20 from both the surfaces thereof and pressed onto the connecting walls 20 to cause a frictional force.
As shown in
An operating manhole 32 is formed in a lower portion of the connecting wall 20. Thereby, in operations within the tower sections 2 divided by the connecting walls 20, operator can pass through the connecting walls 20, improving the workability.
Although a gap exists between the upper and lower tower sections 2 and between the upper and lower connecting walls 20 in
Flanges 34 are provided at both upper and lower ends on the outer wall surface of the tower section 2. The flanges 34 can receive a load caused in stacking the tower sections 2. In order to prevent rain and so on from entering a gap between the tower sections 2, an elastic body such as rubber and resin not shown may be inserted into the gap between the tower sections 2 or may apply a calking agent to the gap. In this embodiment, since a force generated between the tower sections 2 by bending of the tower 3 can be held by the connecting walls 20 and the splice plates 22, the flanges 34 may be omitted.
It is preferred that a thickness of the splice plate 22 is, for example, about 50% of a thickness of the wall surface of the tower section 2. The thickness of the wall surface of the tower section 2 becomes larger as it is closer to the bottom of the tower 3, and the thickness of the wall surface in the vicinity of the junction between the lowermost tower sections 2 is about 50 mm. Thus the thickness of the splice plate 22 used in this junction is about several tens of mm (for example, 15 mm).
A height of the splice plate 22 can be adjusted according to an installation area of the high-tensile bolts 24 required to obtain the frictional force corresponding to the bending force generated in the tower 3. Since the degree of freedom in installing the high-tensile bolts 24 is high as described above, the number of bolts can be appropriately adjusted and widely circulated and low-cost bolts such as M16 and M20 can be used. Although a hexagonal bolt is generally used as the high-tensile bolt 24, a torque shear type bolt may be used in place of the hexagonal bolt. By using the torque shear type bolt, the construction performance can be further improved.
As described above, this embodiment achieve the following effects.
Since the connecting walls 20 are provided in the inside of the tower section 20, the fastening operation of the high-tensile bolts 24 can be performed within the tower section 2. For this reason, the fastening operation of the high-tensile bolts 24 in the outside of the tower 3 can be prevented, and touch-up coating of the externally exposed high-tensile bolts 24 can be omitted. This can reduce the amount of the operator's operations at high elevations.
Since members in the shapes of flat plates are used as the connecting walls 20, it is possible to reduce a misalignment between the connecting walls 20 butted in connecting the tower sections 2 to each other. Further, by using the members in the shapes of flat plates as the connecting walls 20, the splice plates 22 brought into close contact with the connecting walls 20 can have the shapes of flat plates, and therefore the operation of bringing the connecting walls 20 into close contact with the splice plates 22 is also easily performed, which is excellent in workability. As a result, construction costs can be reduced.
Since the connecting walls 20 are provided so as to divide the region in the tower section 2 into a plurality of regions, the section modulus of the tower section 2 can be increased, thereby increasing the rigidity of the tower section 2 itself.
As shown in
The bending moment generated in the tower 3 due to the effect of the wind force and so on becomes larger as it is closer to the lower side of the tower 3, that is, the foundation B. As the bending moment is larger, a force necessary for maintaining connection between the tower sections 2 becomes larger. At the junction between the tower sections 2c and 2d, which is relatively close to the foundation B of the tower 3, connection using the connecting walls 20 is suitable, and at the junction between the tower sections 2a and 2b, which is relatively close to the top of the tower 3, the bending moment becomes relatively small. As a result, the force necessary for maintaining connection between the tower sections 2 becomes small. For this reason, at the junction between the tower sections 2a and 2b, which is relatively close to the top of the tower 3, for example, the tower sections 2 may be connected to each other only by conventional flange joint. With such a configuration, since the bolts are arranged along the outer periphery of the tower 3, the number of bolts installed bolts can be minimized. Further, since the connecting walls 20 and the splice plates 22 are not used, the weight of the upper portion of the tower 3 can be reduced and the thickness of the wall surface of the tower 3 can be minimized.
As a matter of course, the present invention is not limited to connection between the tower sections only by flange joint or only by frictional joint, and flange joint and frictional joint may be used in combination as needed.
Positions of the connecting walls 20 may be changed as follows.
As shown in
As represented by a dotted line, the connecting wall 20 orthogonal to the three connecting walls 20 arranged in parallel may be provided. By arranging the fourth connecting wall 20 in this manner, it is possible to increase the rigidity of the junction between the tower sections 2 also in the direction orthogonal to the direction in which the rigidity of the junction is improved by the other three connecting walls 20.
As shown in
Since the inner region of the tower section 2 is divided into two by the diameter and no connecting wall 20 exists in one of the divided regions, a relatively large space in the tower section 2 can be ensured. That is, since a large vertically-penetrating space can be ensured, the elevator for transporting the operator and equipment necessary for operating the facility at maintenance or the like can be installed in this space, and when the tower is applied to the wind turbine generator, the wind turbine generator can be operated more easily.
As shown in
By arranging the connecting walls 20 in this manner, the shape of the connecting walls 20 can be made uniform, thereby reducing manufacturing costs.
As shown in
That is, a first connecting wall (first connecting member) 20a extending in the vertical direction in this figure and a second connecting wall (second connecting member) 20b extending in the horizontal direction in this figure so as to be orthogonal to the first connecting wall 20a are provided. The second connecting wall 20b is offset from the center O toward the first connecting wall 20a.
With such an arrangement, as compared to the case where the connecting walls 20 are connected to each other at the center O of the cross section of the tower section 2, a region containing the center O of the cross section of the tower section 2 can be increased.
By providing a space vertically penetrating the tower 3 corresponding to the region, an elevator for transporting the operator and equipment necessary for operating the facility at maintenance or the like can be installed, and when the tower is applied to the wind turbine generator, the wind turbine generator can be operated more easily.
As shown in
That is, a connecting wall 20c extending in the vertical direction in this figure and connecting walls 20d and 20e that are connected to an end (lower end in this figure) of the connecting wall 20c and extend in diagonal directions in this figure are provided. A connection point of these connecting walls 20c, 20d, and 20e is offset from the center O toward the connecting walls 20c. With such an arrangement, as compared to the case where the connecting walls 20 are connected to one another at the center O of the cross section of the tower section 2, a region containing the center O of the cross section of the tower section 2 can be increased. By providing a space vertically penetrating the tower 3 in this region, the elevator for transporting the operator and equipment necessary for operating the facility at maintenance or the like can be installed, and when the tower is applied to the wind turbine generator, the wind turbine generator can be operated more easily.
As shown in
By arranging the connecting walls 20 in this manner, a space can be ensured in the center of the tower 3. By arranging an elevator in this space, equipment and jigs used in the nacelle 6 can be easily transported. Further, a ladder for allowing the operator to move to the nacelle 6 can be provided in the space at the center of the tower 3.
As shown in
By arranging the connecting walls 20 in this manner, a space can be ensured in the center of the tower 3. By arranging an elevator in this space, equipment and jigs used in the nacelle 6 can be easily transported. Further, a ladder for allowing the operator to move to the nacelle 6 can be provided in the space at the center of the tower 3.
Although as the polygon in contact with the inner surface of the tower section, the rectangle is used in sixth Modified Example and the triangle is used in seventh Modified Example, a polygon of pentagon or more can be similarly adopted. The length of sides of the polygon is not necessarily uniform and may be appropriately changed.
Further, in the polygons described in these Modified Examples, the connecting wall 20 may be arranged at any position parallel to any side of the polygons.
Although the tower applied to the wind turbine generator has been described in the above-mentioned embodiment and Modified Examples, the tower according to the present invention is not necessarily applied to the wind turbine generator. The tower according to the present invention can be preferably applied to tower-like structures such as a lighthouse and a radio tower.
Although the connecting member is described as the connecting wall in the shape of a flat plate in this embodiment, the connecting member is not necessarily limited to a flat plate. In addition to the flat plate, for example, the connecting member can be in a shape of a member such as a beam that is lower than the above-mentioned connecting wall in height, or a plate having curvature or irregularity.
For example, as shown in
The tower according to the present invention and the wind turbine generator having the tower are not limited to the above-mentioned embodiment and may be appropriately changed so as not to deviate from the subject matter.
