Patent Application
20200263378
The application relates to a transition piece for connecting an upper tower portion with lower tower portion by means of connection profiles. The application further comprises the respective connection profiles. The transition piece is particularly suitable for a hybrid tower, e.g. for a wind turbine, wherein the upper tower portion is configured, for example, as a steel tubular tower and the lower tower portion as, for example, a lattice tower structure.
Towers for onshore wind turbines are typically embodied as tubular towers, in particular steel tubular towers. This design, also referred to as a shell construction, has the advantage that the tubular towers consist of individual segments so that the individual tower components are transportable. Transportability is a limiting factor in particular with regard to tower diameters of tall towers, since with hub heights of more than 120 m, a lower diameter of the tubular tower would exceed 4.5 m. Diameters of more than 4.5 m, however, are transportable on roads only with great difficulty, since bridges above roads and motorways often have a corresponding maximum clearance height. Onshore steel tubular towers are, without additional technical measures (e.g. additional longitudinal separation of the individual segments), thus limited to a hub height of approx. 120 m.
Hybrid tower designs, e.g. steel hybrid towers and prestressed concrete hybrid towers, are moreover known from the prior art. Steel hybrid towers have a lattice mast and a steel tubular tower. Prestressed concrete hybrid towers have a prestressed concrete tower section and a steel tubular tower section. Steel hybrid towers have the advantage that the lower tower portions, which usually have larger diameters, are made of comparatively convenient individual parts that may be assembled together and form a lattice supporting structure, and the upper tower portions are formed as a steel tubular tower. This design, however, requires technically complex solutions for a transition between the lower, lattice-like structure and the upper, tubular structure. To date, primarily only transition pieces that have a high material requirement and a complex or overdimensioned structure are known, which in particular are costly or are only transportable with relative difficulty.
EP 2 647 764 A1 for example describes a transition piece for connecting a tower with a lattice-like foundation structure in the offshore area. Here, the transition piece comprises a cylinder, wherein the cylinder has a flange at its upper end to support the tower base and is provided, on its lateral surface, with metal box sheets to pass the external forces into the foundation structure consisting of main struts and cross struts.
DE 10 2013 221 681 A1 describes a further example for a transition piece for a hybrid tower of a wind turbine. The transition piece comprises an adapter shell and multiple adapter plates, wherein in the adapter shell is configured to be tubular and the adapter shell and the adapter plates are connected to each other in a manner such that the adapter plates and the adapter shell partially overlap in the longitudinal direction of the tower. The fastening means may for example be screws, rivets, or collar pins, however advantageously screws are used, as these are releasable for maintenance of the transition piece and/or the tower. In particular in DE 10 2013 221 681 A1, it is clear that due to a small part size of the support elements used, a plurality of fastening means is necessary in order to enable a reliable force flow from the upper tower portion into the lower tower portion.
In view of the prior art, the object of the invention is to propose an alternative transition piece as well as connection profiles which enable a reliable force flow from an upper tower portion to a lower tower portion, and which at the same time are comparatively economical.
This object is achieved by a transition piece according to claim 1 and by connection profiles according to the independent claim. Advantageous embodiments and developments of the invention are described in the dependent claims.
The transition piece is connectable to an upper, tubular tower portion and to connection profiles. The connection profiles are, in turn, connectable to a lower tower portion which is preferably configured as a lattice structure. In order to connect the transition piece to the upper tower portion, the transition piece comprises an upper connection element. The upper connection element is formed in this case for example as a flange, preferably as a ring flange.
The transition piece further has a hollow structure which tapers towards the bottom. A lateral extent of the transition piece, i.e. an extent that is orthogonal to the longitudinal axis of the transition piece, decreases from the top toward the bottom.
The hollow structure may have a lower polygonal base area. The lower base area may also be configured to be round. The hollow structure may further have a round upper base area or polygonal upper base area. In a hollow structure with a polygonal upper base area, the number of corners of the lower polygonal base area is preferably lower than the number of corners of the polygonal upper base area. In a further exemplary embodiment, the hollow structure may be configured to be in the form of a frustum of a cone and have an upper and a lower base area, each configured to be round.
The polygonal or round base areas described in this application are typically arranged rotationally symmetrically about a tower longitudinal axis or a transition piece longitudinal axis.
The hollow structure may have an inner lateral surface. The inner lateral surface may, for example widen from the top towards the bottom. The inner lateral surface may for example be made of one or more several inner sheets, while the outer surface of the hollow structure may be made of outer sheets. This allows, for example, for a shell structure. It may also be provided for the hollow structure to comprise only one layer, i.e. the hollow structure may be configured as a single-layer shell. The outer lateral surface may then, for example, describe an outer side of a component forming the single shell, e.g. a sheet, and the inner lateral surface may describe the inner side of the component forming the single shell, e.g. the sheet. An outer side of this shell may have the same form as an inner surface of this shell. It may, however, also be provided that the shell is shaped such that an inner face has a different form than an outer surface of the shell. This may, for example, be realized by components cast as a shell.
The inner lateral surface may for example be configured in the form of a frustum of a cone such that the transition piece has an inner lateral surface widening toward the top in the form of a frustum of a cone. An upper base area is typically configured to be circular and a lower base area is also configured to be circular. A diameter of the lower base area is typically smaller than a diameter of the upper base area so that the inner lateral surface widens from the bottom toward the top. A lateral surface configured in this way may be advantageous in avoiding stress peaks on corners and edges and to thus optimize a force flow.
The frustoconical inner lateral surface, accordingly, may be an inner lateral surface of a hollow cone frustum, which at least in some regions may have an outer lateral surface in the form of a frustum of a cone. The hollow cone frustum may form a supporting structure of the transition piece. The upper tower portion, as is usual for steel tubular towers, preferably has a ring flange. The frustoconical inner lateral surface of the transition piece is typically arranged rotationally symmetrically about a hollow structure longitudinal axis. In one exemplary embodiment, in which the hollow structure has a frustoconical inner lateral surface, the hollow structure longitudinal axis may correspond in particular to a cone frustrum longitudinal axis of the frustoconical inner lateral surface.
The inner lateral surface may alternatively have a round upper base area and a polygonal lower base area. The transition from a polygonal lower base area up to the round base area may be smooth, such that the inner lateral surface may be configured to be substantially curved. The inner lateral surface may, however, also comprise edges and steps. Thus, a transition from the polygonal lower base area to the round upper base area may be realized in a more economical manner, e.g. by means of sheets adjoining one another.
The lower polygonal base area of the inner lateral surface or the hollow structure, or of the outer lateral surface, may for example be configured to be a triangle, a rectangle, a pentagon or a hexagon. The round upper base area of the inner lateral surface or the hollow structure, or of the outer lateral surface, may for example be configured to be circular or elliptical.
The base areas may be at least partially or entirely configured to be through-openings or be closed, for example by a sheet.
It may also be provided that the lower as well as the upper base area are configured to be polygonal. In this case, the polygonal upper base area typically has a higher number or corners than the polygonal lower base area. Thus, the polygonal upper base area may better approach a round shape of the upper tower portion.
The polygonal upper base area has, for example, at least five corners, preferably at least eight corners, particularly preferably at least twelve corners.
The hollow structure may have an exterior form that widens towards the top. The hollow structure may then, for example, have an outer lateral surface widening toward the top in the form of a frustum of a cone. The outer lateral surface may be also configured such that a lower base area is polygonal and an upper base area is round or also polygonal. The upper or lower base area of the outer lateral surface may then have the form of the upper or lower base area of the inner lateral surface. Die outer lateral surface of the transition piece may enclose an angle of at least 15°, preferably an angle of at least 20°, with the longitudinal axis of the outer lateral surface. This angle between the outer lateral surface and the longitudinal axis of the outer lateral surface may, for example, enclose at the most 45°, preferably at the most 60°.
The transition piece may further have at least one outer connection face for connecting the transition piece to the support members.
The at least one connection face is typically arranged at an outer side of the hollow structure and below the upper connection element.
The connection face may, for example, be configured to be a ring flange on the outer side of the transition piece. Moreover, connection face of various configurations may be provided. In an exemplary embodiment of the transition piece, the transition piece may have at least three outer connection faces which may be arranged on an outer side of the transition piece substantially rotationally symmetrically about the hollow structure longitudinal axis. The transition piece preferably has a plurality of collars which protrude on the outer side of the transition piece. The collar may have a closed form and for example may form a flange in the form of a frame. The connection face then forms a surface of the collar or flange. The collars are preferably formed integrally with the transition piece. The outer connection faces are consequently part of the transition piece. At each the outer connection faces, the transition piece is connectable to a connection profile which is connectable to the lower tower portion. To this end, the connection profiles, for example, may have a flange, the form of which corresponds to the form of the collar, in particular to the connection faces. A surface of the flange of the connection profile may be placed against the connection face and may be connected thereto, for example by means of welded connections or screw connections. The connection profiles may also have a frame-like flange on an upper side, the form of said flange corresponding to the collar of the transition piece so that the frame-like flange of the connection profile is insertable, for example interlockingly, into the collar of the transition piece. Additionally or alternatively, an integrally bonded connection may be provided. In addition, or alternatively, plug-in connections, screw connections, snap-action connections, adhesively bonded connections, or welded connections may be used. The connection profiles may also be connectable to the transition piece by means of shear cleats. In this case, the frame-like flange may form the shear cleat.
The upper tubular tower portion may be formed for example as a steel tubular tower, in particular as a supporting structure in the form of a shell. The transition piece may be formed at least in part as a supporting structure in the form of a shell. The transition piece is typically formed predominantly as a supporting structure in the form of a shell. The transition piece may be a symbiosis (or advantageous fusion/combination) of supporting structure in the form of a shell and supporting structure formed of rods.
Die frustoconical inner lateral surface of the transition piece may enclose an angle of at least 15°, preferably at least 24°, with the hollow structure longitudinal axis. This angle between the frustoconical lateral surface and the hollow structure longitudinal axis may, for example, enclose at the most 45°, preferably at the most 60°.
The transition piece may have an inspection opening. Installation and maintenance staff may thus enter inside the transition piece. An inspection opening may be provided for example on an underside of the transition piece. For example, a circular base area of the cone frustum may have a recess, which may serve as an inspection opening. A radius of a circular inspection opening may be designed in accordance with Rule 113-004 of the DGUV (German Social Accident Insurance Association), Annex 7, “Minimum Requirements for Access with Fall Arrest Personal Protective Equipment”. A radius is preferably at least 300 mm. Inspection openings may also be provided in the connection profiles and/or in the frustoconical lateral surface. Each of the connection profiles may have an inspection opening. Connection regions, for example screw flanges, between the transition piece and the connection profiles may thus be accessible for installation and maintenance staff.
The connection faces may protrude on the outer side of the transition piece. A plurality of collars may protrude from the outer side of the transition piece, and the collars may form at least three, preferably closed, protruding flanges in the form of a frame. The flanges may fully or partially frame a corresponding region of the outer side of the transition piece. The flanges, in a plan view, may have different forms, and for example may have a triangular, rectangular, square, circular, elliptical or polygonal form, or also a combination of these forms. A surface of these collars or frame-like flanges may form the corresponding connection face. The form of the connection face, as described above, preferably corresponds to a connection face of the connection profiles. The connection profiles may be connected to the transition piece at the connection faces for example by flange connections, shear cleats and/or by welded connections.
The outer side of the transition piece has typically elongate shapings between the connection faces. The shapings preferably extend from an upper side of the transition piece to an underside of the transition piece. The curvature of the embodiments is preferably continuous and in particular does not have any edges. Stress peaks in the transition piece may thus be avoided. The shaping, also referred to as a recess, may have a constant recess radius of curvature over the height of the transition piece. It is also possible that the radius of curvature of the shaping changes over the height of the transition piece. The radius of curvature is defined here as the radius of what is known as a circle of curvature, which best approximates the form of the shaping in a cross-section transverse to the longitudinal axis. The radius of curvature may be at least 0.2 m. The radius of curvature may also be at least 0.5 m. The radius of curvature is typically at most 1 m. The radius of curvature is preferably 0.5 m.
The transition piece may be formed integrally. For example, this may have the advantage that stability is increased and the installation effort is reduced. Nevertheless, the transition piece may also be separable. In such a case, the individual parts preferably may be screwed together or welded together. Interlocking connections for connection of the individual parts are also conceivable. Multi-part transition pieces may have the advantage that maximum dimensions are not limited by transport conditions, as already explained above.
The transition piece is suitable for towers that are used onshore and/or offshore. In an onshore application, the transition piece, along a longitudinal axis, preferably along the cone frustum axis, typically has a height of at least 2.5 m, preferably of at least 3 m. The transition piece may also have a maximum height along the longitudinal axis of 4.7 m, preferably of 4 m. This has the advantage that the transition piece, when already assembled or in a one-piece embodiment, is transportable relatively easily and may be transported on roads and under bridges overland. In an offshore application the height may be much greater, for example up to 7 m.
In one specific embodiment, the transition piece may have a total height along a longitudinal axis which corresponds to at least 50% of a diameter of the upper tower portion. The diameter of the upper tower portion is usually the diameter of the upper tower portion at a lower edge of the upper tower portion (without ring flanges). The total height of the transition piece may preferably correspond to at least 80% of the diameter of the upper tower portion. The total height of the transition piece typically corresponds to at most 150% of the diameter of the upper tower portion. Maximum transport dimensions may thus be observed, and at the same time stress peaks in the transition piece and/or in a tower comprising the transition piece are avoided. The transition piece may have much larger dimensions, particularly in offshore applications.
For improved transportability overland, the transition piece may typically have, perpendicularly to the longitudinal axis, a lateral extent of at least 3.5 m, preferably at least 4 m, and/or at most 5.5 m, preferably at most 4.5 m. The greatest lateral extent is usually on an upper side facing the tubular tower portion. The transition piece has its smallest lateral extent typically on an underside which faces the lower, lattice-like tower portion. The transition piece may have much greater lateral extents, particularly in offshore applications.
The transition piece may also have a lateral extent perpendicularly to the longitudinal axis, which in each position along the height of the transition piece corresponds to at least 0% of the diameter of the upper tower portion, in the region of the connection element to the upper tower portion preferably at least 105% of the diameter of the upper tower portion. The maximum lateral extent perpendicular to the longitudinal axis is typically, in each position along the height of the transition piece, at most 120% of the diameter of the upper tower portion. The diameter of the upper tower portion is usually the diameter of the upper tower portion at a lower edge of the upper tower portion. A good transportability overland may thus be achieved, in particular also on roads that have a clear width of only 5.5 m.
The present invention further comprises a connection profile to connect a transition piece, preferably a transition piece according to specifications mentioned above, with a lower tower portion. The connection profile may have an upper flange, the surface of which corresponds to the connection faces of the transition piece in such a way that the connection profile may be flange-mounted at an upper edge to the transition piece at the connection faces. The connection profile may also have a lower connection element, for example a lower flange. The lower connection element may be formed for example in such a way that it is connectable to a support member, preferably in interlocking and/or force-locked fashion. The connection profile may have an upper profile element, which is connectable to the transition piece, and a lower insert. An insert recess may be formed on an underside of the profile element and may correspond at least in some regions to an outer contour of the insert, in such a way that the insert may be connected in interlocking and/or integrally bonded fashion to the upper profile element. The insert may be connected to the upper profile element for example via one or more welded connections, preferably at least in some regions along the insert recess. The insert is typically connectable to a lower tower portion, preferably releasably, at its underside. A releasable connection, for example a screw connection, has the advantage that the transition piece and the connection profiles may be transported independently of one another and may be relatively easily assembled at a place of installation. A cross-section of the insert may preferably correspond to a cross-section of the support members. For example, a continuous force flow may thus be achieved, since a force offset is substantially avoided. In particular, the lower tower portion may have a lattice structure which comprises at least three support members extending over the length of the lower tower portion. The form of the insert may preferably correspond to a form of an upper end of the support members in such a way that the insert on its underside may be fitted onto the upper end of the support members, onto or into the upper end. The insert and the support members may also be connectable by an integrally bonded connection, for example welding, an interlocking connection, for example by being fitted in or on, and/or a force-locked connection, for example be flange-mounting, screwing, riveting, or the like. In addition, or alternatively, plug-in connections, screw connections, snap-action connections, adhesively bonded connections, or welded connections may be used. The insert and the support members may additionally or alternatively be connectable by means of thrust cleats. A support member may have, for example, a square profile with an edge length of 800 mm and a wall thickness of 25 mm. Each support member preferably has, in a cross-section perpendicular to a support member longitudinal axis, a lateral extent of at least 400 mm. A support member wall thickness is typically at least 10 mm, preferably at least 20 mm, and/or at most 60 mm. Of course, support members having other profile forms, for example U-profiles, rectangular or round profiles, may also be used.
The insert may have the task of ensuring a continuous transition from the profile element to the support member of the lattice structure located underneath. The insert preferably has the dimensions of the support attached below.
The connection profiles may have a cross-section that changes along the extent of the connection profiles, preferably continuously. It may be provided that a cross-section size and/or a cross-section shape change along the extent of the connection profile. In a cross-section, a connection profile in one specific embodiment has a triangular shape, widening upwardly. The upper triangle edge may be convex in this case. The lower tip of the triangle may be rounded, preferably concavely rounded. The side edges of the triangle may be of equal length or may have different lengths. The upper, preferably convex edge in a lateral extent may be longer than the lateral edges. The connection profiles may have a quadrangular or polygonal form in a cross-section. The form preferably widens towards the top in a cross-section. Quadrangular or polygonal cross-section forms may also have concave and/or convex regions. The connection profiles may be formed as a welded construction. The connection profiles may have welded-together wall panels with a wall thickness of at least 10 mm and/or at most 60 mm. The wall panels of a connection profile may have different wall thicknesses. A cross-sectional area of the connection profile, in a cross-section perpendicular to a longitudinal axis of the connection profile, preferably decreases from top to bottom along this longitudinal axis. This has the advantage that a force flow may be optimized and at the same time only as much material as is necessary is used. This may lead to material savings and thus to cost savings. The connection profiles typically have a length along their extent of at least 1 m, preferably at least 8 m and/or at most 12 m. In particular for offshore applications, the connection profiles may also have a length along their extent of more than 12 m.
At least one wall of the connection profile, in a cross-section perpendicular to a longitudinal axis of the connection profile, may have a convexly shaped outer contour at least in some regions. A force flow from the upper tower portion, via the transition piece, into the lower tower portion may thus be improved. Material may then be saved on account of such a force flow optimization.
At least one wall of the connection profile, in a cross-section perpendicular to a longitudinal axis of the connection profile, may have a concavely shaped outer contour at least in some regions. A force flow from the upper tower portion, via the transition piece, into the lower tower portion may thus be improved. Stress peaks may be avoided by such an optimization of the force flow, and material may be saved.
The at least one wall of the connection profile, in a cross-section perpendicular to a longitudinal axis of the connection profile, may have both a concavely shaped outer contour at least in some regions and a convexly shaped outer contour at least in some regions. Stress peaks may also be avoided by concavely curved forms.
The wall of the connection profile may be flat or curved once or more. A multiple curvature of the connection profiles may be realized in particular by a first curvature, for example by a design of the connection profiles that is concave and/or convex along the longitudinal axis, in combination with a curvature perpendicular to the longitudinal axis of the connection profiles.
In order to save material, the connection profiles may preferably be hollow, at least in some sections.
In order to save material, the walls of the connection profiles may be provided with recesses. The recesses may, for example, be covered with thin-walled sheets in order to protect the interior of the connection profiles from weather exposure. The connection profiles may be configured to be braced sheet metal constructions in order to reduce the sheet thickness of the profile elements.
In particular in the case of an offshore application of the transition piece, the connection profiles may be formed integrally with the transition piece. The connection profiles, for example, may be welded to the transition piece instead of, or in addition to flange connections.
Exemplary embodiments will be explained in greater detail below with reference to the drawings.
In the drawings:
In
The connection faces 7 are, at least within a vertical projection of the connection profile longitudinal axis (L), arranged entirely below the connection element 6 and oriented in the force flow direction. This allows for a relatively simple force flow from the upper, tubular tower portion 2 to the support members 13.
The transition piece has its maximum lateral extent on an upper side. The lateral extent of the transition piece decreases from the upper side to the lower side. The outer side 4 of the transition piece 1 has elongate shapings 9 between the connection faces 7. In the shown example the shapings 9 extend from an upper edge of the transition piece 1 to a lower edge of the transition piece 1. In other embodiments the shapings may also extend only in some regions from an upper edge to a lower edge of the transition piece. The shapings 9 have a smooth inner face without edges or protrusions, such that stress peaks caused by notch stresses may be substantially avoided or reduced. The shown shapings 9 are curved inwardly (concavely) in the direction of the hollow structure longitudinal axis K. The form of the shown shaping 9 in
The transition piece may consist, for example, of steel (for example structural steel S355), cast steel (for example nodular cast iron), reinforced concrete, fiber-plastics composite, or may contain combinations thereof. The transition piece is typically manufactured from steel. To this end, individual parts are usually cut to size, shaped, and joined together. The individual parts are typically joined together by welding; alternative possible joining methods, however, include screwing, riveting and adhesive bonding, for example.
The transition piece 1 in
The outer lateral surface thus transitions/is reshaped from a lower base area in the shape of a polygon to a circle (positioned at the top). This construction (in this instance a single-layer shell) allows for a comparatively simple force flow from a connection face 6 to connection profiles 8. This also allows for a variable reaction to the number of support members 13 and connection profiles 8 and the amount of 3D-shaped sheets in the connection profiles 8 can be reduced.
The other features described above, in particular with regard to the transition piece of
Due to its topology, the transition piece allows for a merging of the lower edge of the upper tubular tower portion 2, the upper side of the connection profile 8, the upper side of an outer lateral surface of the hollow structure and the upper connection element 6 at an upper panel edge S1 without significant offset. The transition piece further allows for merging of the lower edge of the connection profile 8 with the lower edge of the outer lateral surface of the hollow structure at a lower panel edge S2 without significant offset.
The application further comprises the following aspects:
| Number | Date | Country | Kind |
|---|---|---|---|
| 17195030.6 | Oct 2017 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/076865 | 10/2/2018 | WO | 00 |
