TOWER, IN PARTICULAR FOR A WIND TURBINE

A tower, in particular for a wind turbine, may have an upper tubular tower portion and a lower lattice-like tower portion. The lower tower portion may have at least three support members. The tower may also have a transition piece connecting the upper tower portion to the lower tower portion. The support members may be arranged substantially around a vertical longitudinal axis, including rotationally symmetrically about the central longitudinal axis. Each of the support members may have at least two portions inclined relative to the perpendicular. In a first, upper of the portions the support members may enclose an angle α with the perpendicular. In a second, lower of the portions the support members may enclose an angle β with the perpendicular. The angle β may be smaller than the angle α.

The invention relates to a tower, in particular a tower for a wind turbine, comprising an upper tubular tower portion, a transition piece, and a lower, for example lattice-like, tower portion.

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 parts that may be assembled together so that the individual tower components are transportable. Transportability is a limiting factor in particular with regard to tower height, since with tower heights of more than 120 m a lower diameter of the tubular tower would exceed 4.3 m. Diameters of more than 4.3 m, however, are transportable on roads only with great difficulty, since bridges above roads and motorways often have a corresponding maximum clearance height. Without additional measures, known onshore steel tubular towers are thus limited to tower heights of approximately 120 m.

Hybrid tower designs are known from the prior art. These 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, in particular for a transition between the lower, lattice-like structure and the upper, tubular structure. Particularly with tower heights of more than 120 m, primarily only towers that have a high material requirement or a complex or overdimensioned structure are known, which in particular are costly to produce or are only transportable with relative difficulty.

DE 10 2010 015 761 A1 for example describes a stand structure for an offshore wind turbine. The stand structure comprises a central pillar, foot elements, and radial struts, which extend between the central pillar and the foot elements. The radial struts are curved convexly over their entire extent, which entails a significant manufacturing effort and high production costs. DE 10 2010 015 761 A1 also does not appear to provide a solution for providing a transition to an upper tower portion optimized in respect of the flow of forces.

In view of the prior art, the object of the invention is to propose an alternative tower which enables a reliable force flow from an upper, tubular tower portion to a lower, lattice-like tower portion, and at the same time may be produced relatively economically.

This object is achieved by a tower according to claim1. Advantageous embodiments and developments of the invention are described in the dependent claims.

The tower, in particular for a wind turbine, comprises an upper, tubular tower portion and a lower, lattice-like tower portion. The lower tower portion comprises at least three support members. The tower also comprises a transition piece connecting the upper tower portion to the lower tower portion.

The support members are arranged substantially around a vertical longitudinal axis, preferably rotationally symmetrically about the central longitudinal axis. Here, “substantially vertically” means that the support members extend from bottom to top relative to a horizontal foundation but have at least two angles of inclination relative to a vertical longitudinal axis which is orthogonal relative to the horizontal foundation. Each of the support members has at least two portions inclined relative to the perpendicular. In a first, upper of the portions the support members enclose an angle α with the perpendicular. In a second, lower of the portions the support members enclose an angle β with the perpendicular. The angles are measured such that in each case the smallest of the angles enclosed by the support member and the perpendicular is the angle α or β respectively. The angles α and β are thus typically acute angles, that is to say angles that are smaller than 90°. The absolute value of each of the angles α and β is greater than 0°. The angle β is smaller than the angle α. The angle α may be at least 30°, preferably at least 40°. The angle α may be at most be 90°, preferably at most 80°, particularly preferably at most 70°. The angle β is usually greater than 0° and smaller than the angle α. A support member preferably comprises so-called connection profiles on an upper edge, and these are described in greater detail further below.

Each of the support members may have, along its extent, a third portion which is inclined relative to the perpendicular. Each of the support members may enclose an angle β1with the perpendicular. The second portion lies typically between the first and the third portion. The angle β1may be smaller than the angle β. Linear support member portions can usually be manufactured more economically. A support member contour that is convex as considered from the longitudinal axis may have the advantage that wind loads, in particular those that occur at an upper end of the tower, may be better routed into the foundation, for example since stress peaks are avoided. Structural advantages of the convex support member structure and economic advantages of the linear support member may be combined by a linear approximation to a convex support member contour.

Each of the support members, along its extent beneath the third portion, may have at least one further portion, preferably n further portions, inclined relative to a perpendicular by an angle β1+n. The angles β1+nmay describe a convex curve of the outer contour. The angle β1+nin this case may be smaller than the angle β1+n−1of the portion arranged above and adjacently to the further portion. The angle β1+nlies typically in a portion that is beneath a portion, with the latter portion enclosing the angle β1+n−1relative to the perpendicular. For example, a portion with the angle β1+n−1=β4lies above a portion with the angle β1+n=β5. In this example, n is for example equal to 4, and the angle β5is smaller than the angle β4. A support member, along its extent, may thus have a convex form relative to a tower longitudinal axis, which convex form is approximated by linear portions. The portions, along the elongate extent of the support members, may alternatively or additionally have regions that are curved in part and are thus true convex regions.

Each of the support members may have, along its extent, a fourth portion which is inclined relative to the perpendicular. In the fourth portion each of the support members may enclose an angle γ with the perpendicular. The fourth portion may lie above, preferably directly above the first portion. Each of the support members, along its extent above the fourth portion, may have at least one further portion, preferably n further portions, inclined relative to the perpendicular by an angle γ1+n. The angles γ1+nmay describe a concave curve of the outer contour. The angle γ1+nmay be smaller than the angle γ1+n−1of the portion arranged beneath and adjacently to the further portion. The angle γ1+nlies typically in a portion that lies above a portion, with the latter portion enclosing the angle γ1+n−1relative to the perpendicular. For example, a portion with the angle γ1+n−1=γ4lies beneath a portion with the angle γ1+n=γ5. In this example, n is for example equal to 4, and the angle β5is smaller than the angle β4. A support member, along its extent, may thus have a concave form relative to a tower longitudinal axis, which concave form is approximated by linear portions. The portions, along the elongate extent of the support members, may alternatively or additionally have regions that are curved in part and thus are true concave regions.

The angle γ is preferably smaller than the angle α. The support members may thus have an inflection point along their elongate extent. This inflection point may be approximated for example by three portions arranged successively from top to bottom. In this case the arrangement of the portion from top to bottom is as follows: the fourth portion, the first portion, the second portion. The first portion in this case may have the above-described angle α, which is greater than the angle β. The fourth portion may have the angle γ, which is likewise smaller than the angle α. The angle γ may preferably be the same as, or smaller than the angle β. The angle γ may be greater than 0°. The fourth portion may also be arranged on the upper, tubular tower portion. The first portion with the angle of inclination α then preferably lies in the region of the connection profiles, and the second portion with the angle of inclination β then preferably lies beneath the connection profiles. The fourth portion may also be arranged in the region of the transition piece. The fourth portion, the first portion and the third portion may also all be arranged in the region of the connection profiles. The fourth portion, the first portion and the third portion may also all be arranged below the connection profiles.

The upper tower portion is typically formed as a supporting structure in the form of a shell. The lower tower portion is usually formed as a lattice-like supporting structure formed of rods. Supporting structures in the form of a shell are relatively favorable, but, in the case of large diameters greater than approximately 4.3 m, may only be transported with great additional outlay, for example by longitudinal separation of the segments. Supporting structures formed of rods have the advantage that large structures may be assembled from relatively small individual parts.

The supporting structure has been developed in particular for very large hub heights and may have a hub height of at least 120 m, preferably at least 140 m, preferably at least 160 m, and/or at most 300 m. The height is preferably measured from an upper edge of a foundation to an upper edge of the upper tower portion. The tower may have a shorter hub height, in particular in the case of offshore applications. Such high hub heights may be realized in particular by the specific form of the lattice structure of the lower tower portion and/or by the transition piece and/or by a foundation described below. With such hub heights, large forces and torques typically occur and must be withstood by the tower. Of course, the tower may also be used for other purposes, for example as a transmission tower.

The height of the lower, lattice-like tower portion may correspond to at least three times, advantageously at least more than three times, preferably at least four times a maximum lateral extent of the lower, lattice-like tower portion. Much smaller ratios are also possible, depending on the system configuration. This is particularly advantageous in order to withstand the above-described high loads in the case of tall tower heights. The height is preferably measured from an upper edge of a foundation to a lower edge of the upper, tubular tower portion. It has been found that a structure which is much broader than it is tall is not necessarily able to withstand higher loads. This may be attributed in particular to unpredictable synergy effects between the transition piece, the particular outer contour, the lattice structure, the specific value ranges of the lattice structure, the support member form and/or foundation form. Due to the above-described ratio, in particular material (and land sealing) may thus be reduced as compared to the prior art, high hub heights may be achieved, and very high loads may be withstood.

The support members, for example in a cross-section perpendicular to the longitudinal axis, at a lower edge of the connection profiles of the lower tower portion, may be at a radial distance from the longitudinal axis of at least 4 m, preferably at least 6 m, particularly preferably at least 8 m and/or at most 16 m. The lower edge of the connection profiles of the lower tower portion is preferably arranged at the height at which at least a highest cross strut of the lower tower portion along the central longitudinal axis is arranged. The cross strut, in its elongate extent, may be arranged substantially parallel to the horizontal. The lower edge of the connection profiles of the lower tower portion typically has a distance of at least 70 m from a foundation upper edge.

The support members, in a cross-section perpendicular to the tower longitudinal axis, at a lower edge of the lower tower portion, may be at a radial distance from the longitudinal axis of at least 5 m, preferably at least 7 m, particularly preferably at least 9 m or for example at least 10 m, and/or at most 20 m. The lower edge of the lower tower portion is preferably defined here by the height along the central longitudinal axis at which the support members are adjacent to the foundation. The lower edge of the lower tower portion lies typically on the upper edge of the foundation, that is to say on the foundation upper edge. The central longitudinal axis of the tower may correspond to the tower longitudinal axis. This arrangement of the support members may have the advantage that the support members may pass high forces into the foundation. High tower heights, which for example are exposed to high wind loads, may thus be realized.

The radial distance at the upper edge of the lower tower portion is typically smaller than the radial distance at the lower edge of the lower tower portion.

In one embodiment, the tower may have a strip foundation. A strip foundation may have the advantage that a ground area which lies within the strip foundation or also line foundation does not have to be concreted. Thus, the area occupied by the strip foundation may for example reduce land sealing and therefore compensation measures. Due to the advantageous strip foundation, the land sealing may be reduced by more than 40% as compared to conventional foundations for wind turbines. Furthermore, material may be saved by means of a strip foundation, and therefore costs may be lowered. Alternatively, the foundation may also be formed in the manner of individual foundations in order make further cost savings or in order to provide improved accessibility of the area demarcated by the foundation. In this case the number of the individual foundations corresponds preferably to the number of the support members. Foundations in the form of surface and/or deep foundations are possible. Each of the support members may be supported by a corresponding foundation. The force-locked and frictional connection between the support members and the foundation may be realized in the manner typical for machine foundations.

The line foundation or strip foundation may have a polygonal or circular shape. Of course, other foundations which are not formed as a line foundation are also possible.

The foundation, in particular the line foundation, may have a radial extent or a mean radial extent of at least 7 m, preferably at least 9 m. The radial extent may be measured for example at the foundation upper edge perpendicularly to the central longitudinal axis. The radial extent, for example in the case of a circular line foundation, may describe an outer radius of the line foundation.

A lower edge of the upper tower portion usually corresponds to an upper edge of the transition piece. The lower edge of the upper tower portion is typically connected to the upper edge of the transition piece, for example by means of a flange connection. A lower edge of the upper tower portion, or an upper edge of the transition piece, is typically arranged at a height along the longitudinal axis of at least 55 m above the foundation upper edge, preferably at least 80 m above the foundation upper edge.

The circumradius through centroids of the support members at the lower end of the connection profiles8′ is at least 250%, preferably at least 350% of the circumradius of the shell middle plane at the lower edge of the upper, tubular tower cross-section.

The transition piece and/or the support members may have regions which are curved substantially inwardly towards the longitudinal axis. This usually corresponds to a partial concave curvature. The support members, in particular the connection profiles, may additionally or alternatively be curved outwardly, that is to say away from the central longitudinal axis. This usually corresponds to a partial convex curvature. The convex and/or the concave curvature may be approximated in each case by straight portions, as already described above. A curved form may have the advantage of a continuous force flow. Stress peaks and stress concentrations may thus be counteracted.

The support members, as already mentioned above, may comprise connection profiles for connection of the support members to the transition piece. Each of the connection profiles, in a cross-section along a connection profile longitudinal axis, may have an outer contour running from top to bottom along an elongate extent, preferably continuously, and having an inflection point. This may be the case in particular if the connection profiles, along their extent, have a concave and convex curvature, for example the connection profiles, along their extent from top to bottom, initially have a concave region and then a convex region. The outer wall of the connection profiles may be curved both about the connection profile longitudinal axis as well as along the connection profile longitudinal axis. The connection profiles may be formed as a conical tube. The conical tube may taper toward the bottom. The connection profiles may also have a constant cross-section. The connection profiles may also have a cross-section that has the form of a polygon. The cross-section of the connection profiles may also have concave or convex regions. The connection profiles may also have a curved outer wall on a first outer wall which is arranged closer to the tower longitudinal axis, and may have a flat outer wall on an outer wall which is arranged further away from the tower longitudinal axis, or vice versa. The connection profile longitudinal axis may also have an inflection point. The connection profile longitudinal axis is typically the line that connects the center points of the connection profile cross-sectional areas. The cross-sections are, for example, perpendicular to the connection profile outer contour or perpendicular to at least one connection profile outer wall.

The upper tower portion may have a height that corresponds at least to the length of a rotor blade path of movement. The length of a rotor blade is preferably at least 54 m. The lower tower portion preferably reaches below the rotor blade path of movement. The lower end of the connection profiles8′ may be at a distance from the rotor blade path of movement of at least 6 m, preferably at least 8 m.

The transition piece is connectable to an upper, tubular tower portion and to the connection profiles. 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 the tower 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 cone frustum longitudinal axis.

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, at least in part have an outer lateral surface widening toward the top in the form of a frustum of a cone. The outer lateral surface may be 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 cone frustum 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 of 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. 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.

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 connection profiles of the lower tower portion may form an upper portion of the support members. Each 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 corresponding 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 lower support member portion, preferably in interlocking, integrally bonded 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 interlockingly 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, preferably releasably, at its underside to a lower support member portion. 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 lower support member portion. 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 lower support member portions in such a way that the insert on its underside may be fitted onto the upper end of the lower support member portions, onto or into the upper end. The insert and the lower support member portions may also be connected 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. The insert and the lower support member portions may additionally or alternatively be connected by means of thrust cleats. A lower support member portion may have, for example, a square profile with an edge length of 800 mm and a wall thickness of 25 mm. Each support member, in the lower support member portion in a cross-section perpendicular to a support member longitudinal axis, preferably has a lateral extent of at least 400 mm. A support member wall thickness in the lower support member portion is typically at least 10 mm, preferably at least 20 mm, and/or at most 60 mm. Of course, the support members may also have other profile forms, for example U-profiles, rectangular or round profiles.

The insert may have the task of ensuring a continuous transition from the profile element to the lower support member portion. The insert preferably has the dimensions of the lower support member portion following on subsequently 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 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 with reference to the following drawings.

FIG. 1shows a schematic view of a tower for a wind turbine. The tower comprises a transition piece1, an upper tower portion2, which is formed in a tubular manner as a supporting structure in the form of a shell, and a lower tower portion5, which is formed in a lattice-like manner, having at least three support members13, in the form of a supporting structure formed of rods. The support members13are arranged rotationally symmetrically about a central tower longitudinal axis T. The transition piece1is arranged between the upper tower portion2and the lower tower portion5. A rotor hub with rotor blades20is arranged on the upper tower portion. A rotor blade path of movement20′ lies in the upper, tubular tower portion2above an upper edge of the transition piece1. The tower has an overall tower height G of 158 m. Each of the support members13has a first, upper portion a1. In the first upper portion a1, each of the support members13encloses an angle α with the tower longitudinal axis. In the region of the first portion a1, each of the support members13is formed as a connection profile8. The angle α in the shown exemplary embodiment is 42°. Each of the support members13has a second portion a2arranged beneath the first portion a1. In the portion a2, each of the support members13encloses an angle β with the tower longitudinal axis T. In the exemplary embodiment shown, the angle β is 22° and is thus smaller than the angle α. InFIG. 1, each of the support members13, in the lower part5′ of the lower tower portion, has an angle of inclination β1relative to the central tower longitudinal axis T of 0°; in other embodiments β1may also be greater than 0°. A lower tower portion5′ may thus be inclined relative to the tower longitudinal axis T. Furthermore, a plurality of portions which have an angle of inclination relative to the tower longitudinal axis may be arranged in the lower tower portion5′. Each portion in the lower tower portion5′ preferably has an angle of inclination that in each case is greater than an angle of inclination enclosed by the support member in the portion beneath and the tower longitudinal axis T. The lower tower portion5has cross-bracings22for strengthening. The tower also has cross struts17. The lower, lattice-like tower portion may thus be braced. The lower tower portion is constructed in the manner of a supporting structure formed of rods.

FIG. 2shows a perspective view of the tower for a wind turbine which corresponds substantially to that ofFIG. 1and differs from the tower inFIG. 1in respect of details that will be described hereinafter. Any features of the towers shown in the following drawings may also be applied to the tower1, and vice versa. A first transition region B1describes the transition from the upper tower portion2to the transition piece1. A second transition region B2describes the transition from an upper part of the support members13—the connection profile8—to a lower part5′ of the lower tower portion5. The lower tower portion5has at least three cross struts17. At the lower end of the connection profile8′ of the lower tower portion5, the support members13each have a radial distance perpendicularly to the longitudinal axis of 8 m. The lower end of the connection profiles8′ has a distance to a foundation upper edge18′ of a foundation18of 80 m. A lower edge of the upper tower portion has a distance of 90 m to the foundation upper edge18′. A wind turbine19is mounted on an upper side of the upper tower portion. In this case, a hub of a rotor of the wind turbine has a distance to the foundation upper edge18′ of 160 m. A rotor blade20has a length of 65 m. At the lower edge of the lower tower portion5, that is to say at the foundation upper edge18′, the support members have a radial distance of 10 m to the central tower longitudinal axis T. The upper, tubular tower portion2has a tube diameter of 4 m.

The tower is designed in such a way that it withstands subsequent extreme loads at hub height (coordinate system corresponding toFIG. 2); the described extreme load combination may act on the supporting structure from all directions, for which reason the coordinate system is rotated about the y-axis or the central tower longitudinal axis T:

The total weight of the tower, without the foundation, is 438 t. The lattice structure of the lower tower portion5has steel profiles. A structural steel S 355 is preferred in this case. The cross strut17is a round profile with a diameter of 390 mm and a wall thickness of 17 mm. The support members are square hollow profiles. The support members have different material cross-sections along their extent. Each support member, at the foundation upper edge18′, thus has a profile edge length of 793 mm and a wall thickness of 36 mm. At the height of the upper edge17, each support member of the shown example has the same profile edge length of 793 mm, but a wall thickness of 25 mm. In other exemplary embodiments, the profile edge length and/or the wall thickness may of course vary over the extent of the support members. However, the wall thickness of the support members is preferably at least 20 mm and/or at most 60 mm. The support members may also have round cross-sections. The profile diameters may correspond to the above-mentioned profile edge lengths.

FIG. 3shows a section AA of the tower ofFIG. 1 or 2. The section AA represents a cross-section of the lower tower portion5. The centroid of the support members13is described by a circumradius Ru. The circumradius Ru at the lower end of the connection profile is 8 m for the exemplary embodiment. The circumradius of the shell mid-surface at the lower edge of the upper tower portion is 2 m. The circumradius of the support members13at the lower end of the connection profiles8′ is 4 times the circumradius of the shell mid-surface at a lower end of the upper tower portion.

FIG. 4shows an exemplary form of a first transition region B1and a second transition region B2, preferably for a tower corresponding toFIG. 1 or 2. The first transition region B1has an inwardly curved surface relative to the central tower longitudinal axis T. The upper tower portion2is connected via the transition piece1to the connection profiles8. The transition piece1, the connection profiles8, and the lattice-like structure of the lower tower portion5are merely shown schematically. A first radius of curvature r1describes the radius of a circle k1which best approximates the concave form of the first transition region B1.

The second transition region B2has an outwardly curved surface relative to the central tower longitudinal axis T. The connection profiles8are connected in this region B2to the lower tower portion5. A circle k2best approximates the convex curvature of the transition region B2. The circle k2has a radius of curvature r2.

The radius of curvature r1is preferably greater than the radius of curvature r2.

In one specific technical embodiment the radiuses of curvature are preferably approximated by straight elements. The connection profiles8may, however, also be curved.

FIG. 5shows an exemplary embodiment of a support member13. The support member13has a first, upper portion a1. In the portion a1, the support member13encloses an angle α with the tower longitudinal axis T. In a second portion a2, which is beneath the portion a1, the support member13encloses an angle β with the tower longitudinal axis T. The angle β is smaller than the angle α. In a further portion a2′, the support member encloses an angle β1with the tower longitudinal axis T. The angle β1is smaller than the angle β. In a portion a2″ beneath the portion a2′, the support member encloses an angle32. The angle β2is smaller than the angle β1. In a portion a2′″ beneath the portion a2″, the support member encloses an angle β3. The angle β3is smaller than the angle β2. In this way, the support member may, for example, approximate a convex curvature by means of linear portions. The portions a1, a2, a2′ and/or a2″ may lie in the region of the connection profile8. However, they may also be arranged at least in part beneath the connection profile. In particular, the portion a1is typically part of the connection profile.

FIG. 6shows an exemplary embodiment of a support member13. The support member13has a first, upper portion a1. In the portion a1, the support member13encloses an angle α with the tower longitudinal axis T. In a second portion a2, which is beneath the portion a1, the support member13encloses an angle β with the tower longitudinal axis T. The angle β is smaller than the angle α. In a further portion a2′, the support member encloses an angle β1with the tower longitudinal axis T. The angle β1is smaller than the angle β. In a portion a2″ beneath the portion a2′, the support member encloses an angle β2. The angle β2is smaller than the angle β1. In this way, the support member may, for example, approximate a convex curvature by means of linear portions. The portions a1, a2, a2′ and/or a2″ may lie in the region of the connection profile8. However, they may also be arranged at least in part beneath the connection profile. In particular, the portion a1is typically part of the connection profile.

The support member13also has a fourth portion a3. In the portion a3, the support member encloses an angle γ with the tower longitudinal axis T. The angle γ is smaller than the angle α. An inflection point thus lies on the support member. Each of the support members, along its extent above the portion a3, may have at least one further portion a3′ with the angle γ1, preferably n further portions inclined relative to a perpendicular by an angle γ1+n. The angle γ1+nmay be smaller than the angle γ1+n−1of the portion arranged beneath and adjacently to the further portion. The support member, along its extent, may thus have a concave form relative to a tower longitudinal axis, which concave form is approximated by linear portions. The portions, along the elongate extent of the support members, may alternatively or additionally have regions that are curved in part and thus are true concave regions.

In the transition between the fourth portion a3and the first portion a1, the form of the support member approximates a concave curvature. The form of the support member approximates a convex curvature between the portions a1, a2, a2′ and a2″. The portions a3, a1and a2′ may all be part of the connection profile8. The connection profile8may additionally also comprise the portion a2″. The portion a3and n further portions above the portion a3may be part of the connection profile8and/or part of the transition piece1and/or part of the upper tower portion2.

InFIG. 7the transition piece1for connection of the upper tower portion2to the lower tower portion5is shown. The transition piece1has an inner lateral surface3, which widens upwardly in the form of a frustum of a cone, here in the z direction. The inner lateral surface3has a smooth surface. In the shown example a hollow cone frustum, that of the inner lateral surface3, has a wall thickness of 40 mm. At an upper portion of the transition piece1, the transition piece1has an upper connection element6. Here, the upper connection element6is formed as a ring flange via which an upper tubular tower portion is connectable to the transition piece1, in particular by screwing and/or welding. The transition piece1is rotationally symmetrical about a cone frustum longitudinal axis K. The transition piece1also has four outer connection faces7arranged on an outer side4rotationally symmetrically about the cone frustum longitudinal axis K. The connection faces7protrude from the outer side4. The connection faces7preferably extend practically over the entire height of the transition piece1. The connection faces7may form a flange which extends substantially from an upper end of the transition piece1to a lower end of the transition piece1. The connection faces7may be connected to corresponding bearing faces of the connection profile8(seeFIGS. 11a-11d). To this end, the connection profiles8may be screwed on and/or welded on, for example to the transition piece1.

The connection faces7are, at least within a vertical projection of the connection profile longitudinal axis (L), arranged entirely below the connection element6and oriented in the force flow direction. This allows for a relatively simple force flow from the upper, tubular tower portion2to the support members13. 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 side4of the transition piece1has elongate shapings9between the connection faces7. In the shown example the shapings9extend from an upper edge of the transition piece1to a lower edge of the transition piece1. 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 shapings9have a smooth inner face without edges or protrusions, such that stress peaks caused by notch stresses may be substantially avoided or reduced. The shown shapings9are curved inwardly (concavely) in the direction of the cone frustum longitudinal axis K. The form of the shown shaping9inFIG. 1, in a cross-section perpendicularly to the cone frustum longitudinal axis K, in this case may be elliptical or circular for example, at least in some regions. The outer contour of the transition piece in a cross-section perpendicular to the cone frustum longitudinal axis K may also describe a parabolic form in the region of the shaping.

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 piece1inFIG. 7has a maximum lateral extent A of 4.8 m. The height H of the transition piece1is 3.5 m. The connection face7protrudes with a collar height h of 20 cm relative to a framed outer side4′ of the transition piece. In this case, the framed outer side4′ is the outer side of the transition piece that is framed by the protruding connection faces7. The framed outer side4′ may have, in particular, the form of a region of an outer lateral surface of a cone frustum that widens towards the top. The framed outer side4′, for example, in this case may constitute regions of an outer lateral surface of a cone frustum comprising the inner lateral surface3. In the region of the framed outer sides4′, the inner lateral surface3has a wall thickness of 40 mm.

FIG. 8shows a side view of the transition piece1ofFIG. 7in the xz plane. The connection faces7, inFIG. 2, lie in a plane that is inclined relative to the xz plane and that encloses an angle ε with the z axis. The connection faces7have a concavely rounded groove7′ at an upper edge, and have a concavely rounded groove7″ at a lower edge. The framed outer face4′ is framed by the protruding connection faces7.

FIG. 9shows a plan view of the transition piece from above in an xy plane. Here, the inner lateral surface3is clearly visible. The cone frustum comprised by the inner lateral surface3has an opening3′ at a lower end. The form of the opening3′ corresponds here substantially to the lower circular base area of the cone frustum. A radius r of this circular opening3′ corresponds in the shown example to a radius r′ of the four shapings9. In other embodiments the radius r may be different from the radius r′ of the concavely rounded groove.

FIG. 10shows a detail of a hybrid tower with an upper tubular tower portion2, the transition piece1, and a lower, lattice-like tower portion5with support members which are formed in an upper portion as connection profiles8. The upper tower portion2is connected here to the transition piece1via the upper connection element6, formed here as a ring flange, by means of screws. Furthermore, the transition piece1, in particular with use of the transition piece1in a tower that is used in the offshore sector, may be connected at the connection faces7to the connection profiles8by welded connections. The connection profiles8are in turn connected at an underside to the lower portion5′ of the support members. The connection profiles8and the connection of the connection profiles8to the lower portion5′ of the support members will be explained in greater detail in particular in the following drawings.

FIGS. 11ato 11cshow the connection profile8from different perspectives.FIG. 11ashows the connection profile in a perspective side view.FIG. 11bshows the connection profile8in a view from below;FIG. 11cshows the connection profile8in a view from above. The connection profile comprises a profile element11and an insert10. On an underside of the profile element, an insert recess may be provided, which may correspond at least in some regions to an outer contour of the insert. The insert may thus be inserted with an accurate fit into the profile element and connected to the upper profile element. The insert preferably may be welded to the upper profile element at least in some regions along the insert recess. Additionally or alternatively, the insert may be connected to the profile element by means of plug-in connections, screw connections, snap-action connections and/or adhesively bonded connections. In one embodiment, the profile elements11may, entirely or in part, also be formed as a supporting structure formed of rods. The connection profile8is preferably hollow. In particular in the plan view ofFIG. 5c, it is clear that the connection profile8, here in particular the profile element11, of the shown exemplary embodiment comprises a curved wall11′, in particular a wall curved convexly about a longitudinal axis L. The profile element11, on the side opposite the convexly curved wall11′, also comprises a concavely curved wall11″, that is to say a concavely curved groove. The profile element11, however, may also have side edges which are not curved, as may be seen for example inFIG. 5a. The profile element11may also be curved along the longitudinal axis L, and therefore may have flat, single-curved and also double-curved walls. A cross-section of the connection profile8perpendicular to the longitudinal axis L may change continuously along its extent. A cross-sectional area of the connection profile8perpendicular to the longitudinal axis L typically decreases from top to bottom. Material may thus be saved since this is arranged depending on the effective loading. In this case, for example wind forces which act on an upper end of the upper tower portion are passed from the upper tower portion, through the transition piece1, through the connection profiles8, into the lower tower portion5and onwards into a foundation. The insert10, as mentioned above, is preferably welded to the profile element11at a contour of the insert10′ facing the profile element11. At an underside10″ of the insert, the insert typically has an opening, into which a lower support member portion5′ may be inserted. A lower support member portion5′ preferably may thus be connected to the insert with an accurate fit. It is additionally advantageous to releasably connect the support member to the insert by a flange connection, in particular by screwed flanges.

FIG. 11dshows the connection profile8, which comprises the upper profile element11and the insert10, and the support member13in an exploded view. The insert recess12corresponds to the contour10′ of the insert10facing the profile element11. The underside10″ of the insert10is connectable to the lower support member portion5′. The insert10, to this end, has an L-flange on its underside10″, which L-flange corresponds to a support member flange13′. A connection of this kind is described in greater detail inFIG. 9.

FIG. 12shows a perspective view of the transition piece with four connection profiles8. In the shown example, four connection profiles are arranged rotationally symmetrically about the cone frustum longitudinal axis K. In another exemplary embodiment, only three or more than four connection profiles8may also be arranged about the cone frustum axis K.FIG. 13shows a lower tower portion5which has four support members13. The fourth support member is hidden in the view shown inFIG. 7by the support member13′. The number of the support members13and the number of the connection profiles8always match, since each connection profile8, as described above, is part of the corresponding support member13. A longitudinal axis L of the connection profile8, in the shown example, encloses an angle α with the cone frustum axis K.

FIG. 14shows a schematic view of a cross-section along the cone frustum longitudinal axis K of a transition piece1which corresponds substantially to that in the previous drawings. Four connection profiles8are connected to the transition piece. Four outer connection faces7of the transition piece1are arranged on an outer side4of the transition piece substantially rotationally symmetrically about the cone frustum longitudinal axis K. The transition piece has four collars14, which protrude on the outer side4of the transition piece1. Each collar14has a closed form in this case and forms a frame-like flange. The connection face in this case forms a surface of the collar14, or frame-like flange. The collars14are formed integrally with the transition piece1. At each of the outer connection faces7, the transition piece1is connectable to a connection profile8. To this end, the connection profiles8have a flange15, the form of which corresponds to the form of the collar14. A surface of the flange15of the connection profile8is placed against the connection face7and is connected thereto, for example by means of welded connections (in particular in the case of towers that are used offshore) or screw connections (in particular in the case of towers that are used onshore). The connection profiles8also have a frame-like flange16on an upper side, the form of said flange corresponding to the collar14of the transition piece in such a way that the frame16of the connection profile8is inserted with an accurate fit into the collar14of the transition piece1.

FIG. 15shows a detailed view of a connection between the lower support member portion5′ of the lower tower portion5, for example in the form of a supporting structure formed by rods, and the connection profile8.FIG. 15may also show a connection between the connection profile8and the transition piece1. For the sake of clarity, the reference signs used inFIG. 15correspond to those of a connection between the lower support member portion5′ and the connection profile8. The detailed view is shown in a cross-section along a support member longitudinal axis TA. Here, the connection profile8, at its lower end8′, has an inwardly protruding L-flange15′. The L-flange15′ may be arranged for example at the lower end10″ of the insert10. The L-flange15′ has a bearing face15″, against which a corresponding flange5′″ of the lower tower portion5rests. The flange5′″ is arranged on the uppermost support member13of the lower support member portion5′. Due to the L form of the L-flange15′, the connection profile8is insertable into the lower tower portion5. The L-flange15′ corresponds to the flange5′″ of the lower support member portion5′ in such a manner that the lower tower portion5is connectable to the connection profile8frictionally, for example by means of a flange connection. The L-flange15′ and the flange5′″ also have coaxial holes. A screw is inserted through the coaxially corresponding holes and is fixed by means of a nut. The lower support member portion5′ and the connection profile8are thus additionally connected frictionally. The detailed view D shows this connection in an enlarged view. A connection of this kind may also be provided between the transition piece1and the connection profile8. The transition piece1may thus be connected to the connection profile interlockingly and/or frictionally. To this end, the connection profile8, at its upper end, has an above-described L-flange15′, and the connection faces7of the transition piece1form a corresponding flange, which corresponds substantially to the flange5′″ of the above description.

FIG. 16shows, in a perspective view, a lower region of a connection profile8, which is connected to a lower portion of the support member13via a flange connection. The shown connection profile8does not have an insert10, but in another embodiment could also be formed having an insert10. The shown connection profile8, at a lower end8′, has a flange in the form of a baseplate. This flange corresponds to a support member flange13′ at the upper end of the lower support member portion5′. The flange of the connection profile8rests flat on the support member flange13′. The flanges, for example, may be connected by means of screw connections.

FIG. 17shows an alternative transition piece1in a perspective view. The transition piece1has an upper connection element6in the form of ring flange. The transition piece further comprises a hollow structure which tapers towards the bottom, with an outer lateral surface3″ which widens towards the top. The inner lateral surface3also widens towards the top. The upper base areas of the outer and the inner lateral surfaces are configured to be circular. The lower base area3′″ of the outer lateral surface has a triangular shape. The lower base area3′″ of the inner lateral surface3″″ also has a triangular shape. The hollow structure1′ is formed by three sheets which are welded to one another at the edges23a,23b,23c. The sheets are each rounded in a manner such that a transition from the lower triangular shape to the upper circular shape is realized.

The outer lateral surface thus transitions/is reshaped from a lower base area in the shape of a polygon to a cone (positioned at the top). This construction (in this instance a single-layer shell) allows for a comparatively simple force flow from a connection face6to connection profiles8. This also allows for a variable reaction to the number of support members13and connection profiles8and the amount of 3D-shaped sheets in the connection profiles8can be reduced significantly.

FIG. 18shows the transition piece ofFIG. 17in a side view in an xz plane,FIG. 19shows the transition piece ofFIGS. 17 and 18in a plan view in the xy plane. The triangular shape of the lower base area of the inner lateral surface is easily visible in the plan view. The transition piece further has an inspection opening3′.

FIG. 20shows the transition piece of the previous figures in a view from the bottom, such that the outer lateral surface3″ is easily visible. The triangular shape of the base area3′″ of the outer lateral surface3″ and the inspection opening3′ are also easily visible. Die outer lateral surface has a circular upper base area. The sheets of the hollow structure are bent three-dimensionally and adjoin one another in a manner such that the outer lateral surface widens towards the top and describes, in part, a smooth transition from a polygonal base area towards a circular base area at the top.

The other features described above, in particular with regard to the transition piece ofFIGS. 7 to 10, may be combined with the transition piece ofFIGS. 17 to 22.

FIG. 21shows, in a side view, the transition piece ofFIGS. 17 to 21, wherein connection profiles are connected to the transition piece.FIG. 22shows the transition piece ofFIGS. 17 to 20with assembled connection profiles in a plan view. The connection profiles may, for example, be welded and/or screwed to the transition piece. A connection via adhesive bonding is also conceivable. The connection profiles ofFIGS. 21 and 22substantially correspond to the those of the figures described above. The connection profiles8have, inter alia, a convexly curved wall11′ like the connection profiles ofFIG. 11and are configured to be hollow. Moreover, a cross section decreases from the top toward the bottom along the connection profile longitudinal axis L. However, the wall11″ across from the wall11′ is not curved concavely but configured to be flat, as opposed to the walls of the connection profiles of the figures above. The connection profiles further have side panels with recesses in order to save material and to reduce the weight of the connection profiles. In order to reduce the sheet thickness of the profile elements, the connection profiles8may be configured to be braced sheet metal constructions.

FIG. 23shows a schematic view of a transition piece1according to the embodiments above, which transition piece is connected to an upper tubular tower portion2via the upper connection element6. The transition piece1is connected to support members13of a lower, lattice-like tower portion via connection profiles8. Due to its topology, the transition piece allows for a merging of the lower edge of the upper tubular tower portion2, the upper side of the connection profile8, the upper side of an outer lateral surface of the hollow structure and the upper connection element6at an upper panel edge S1without significant offset. The transition piece further allows for merging of the lower edge of the connection profile8with the lower edge of the outer lateral surface of the hollow structure at a lower panel edge S2without significant offset.

The application further comprises the following aspects:1. A tower, in particular for a wind turbine, comprising an upper tubular tower portion (2) and a lower lattice-like tower portion (5) having at least three support members (13), and comprising a transition piece (1) connecting the upper tower portion (2) to the lower tower portion (5), wherein the support members (13) are arranged substantially around a vertical tower longitudinal axis (T), preferably rotationally symmetrically, wherein each of the support members (13) has at least two portions inclined relative to the perpendicular and in a first, upper of the portions (a1) encloses an angle α with the perpendicular, in a second, lower of the portions (a2) encloses an angle β with the perpendicular, and the angle β is smaller than the angle α.2. The tower according to aspect1, characterized in that each of the support members (13), along its extent, has a third portion (a2′) which is inclined relative to a perpendicular and in which each of the support members (13) encloses an angle β1with the perpendicular, wherein the second portion (a2) lies between the first portion (a1) and the third portion (a2′) and the angle β1is smaller than the angle β.3. The tower according to aspect1or2, characterized in that each of the support members (13), along its extent beneath the third portion (a2′), has at least one further, preferably n further portions inclined relative to a perpendicular by an angle β1+n, wherein the angle β1+nis smaller than the angle β1+n−1the portion of arranged above and adjacently to the further portion.4. The tower according to one of the previous aspects, characterized in that each of the support members (13) along its extent has a fourth portion which is inclined relative to a perpendicular and in which each of the support members (13) encloses an angle γ with the perpendicular, wherein the fourth portion lies above, preferably immediately above the first portion (a1) and the angle γ is smaller than the angle α.5. The tower according to one of the previous aspects, characterized in that each of the support members (13) has, along its extent and above the fourth portion, at least one further, preferably n further portions inclined relative to a perpendicular by the angle γ1+n, wherein the angle γ1+nis smaller than an angle γ1+n−1of a portion arranged beneath and adjacently to the further portion.6. The tower according to any one of the preceding aspects, characterized in that the tower has a total height (G) of at least 120 m, preferably at least 140 m, preferably at least 160 m.7. The tower according to any one of the preceding aspects, characterized in that the height of the lower, lattice-like tower portion (5) corresponds to at least three times, preferably at least four times a maximum longitudinal extent of the lower, lattice-like tower portion.8. The tower according to any one of the preceding aspects, characterized in that the support members (13) in an upper support member portion have connection profiles (8) for connection of the support members (13) to the transition piece (1), wherein each of the connection profiles (8), at a lower edge, is at a radial distance from the tower longitudinal axis of at least 4 m, preferably at least 8 m and/or at most 16 m.9. The tower according to any one of the preceding aspects, characterized in that a radial distance of the support members (13) from a tower longitudinal axis (T) at a lower edge of the lower, lattice-like tower portion is at least 5 m, preferably at least 10 m and/or at most 20 m.10. The tower according to any one of the preceding aspects, characterized in that a circumradius (Ru) through centroids of the support member cross-sectional areas at a lower end of the connection profiles (8′) is at least 250%, preferably at least 350% of a circumradius of a shell middle plane at a lower edge of the upper, tubular tower cross-section.11. The tower according to any one of the preceding aspects, characterized in that the upper tower portion (2) has a height that corresponds at least to the length of the rotor blade path of movement (20′), wherein the length of a rotor blade (20) is at least 40 m.12. The tower according to any one of the preceding aspects, characterized in that the tower has a strip foundation (18) and/or individual foundations, which are arranged centrally beneath each of the support members (13).13. The tower according to aspect12, characterized in that the strip foundation (18) has a radial extent of at least 9 m, preferably at least 12 m.14. The tower according to any one of the preceding aspects, characterized in that the upper tower portion (2) is formed as a supporting structure in the form of a shell and/or the lower tower portion (5) is formed as a supporting structure formed of rods.15. The tower according to any one of the preceding aspects, characterized in that the transition piece (1) for connection of the upper tower portion to the lower tower portion comprisesan upper connection element (6) to connect the transition piece (1) to the upper tower portion (2) andhas an inner lateral surface (3) widening upwardly in the form of a frustum of a cone andat least three outer connection faces (7), which are arranged on an outer side (4) of the transition piece (1) substantially rotationally symmetrically about a cone frustum longitudinal axis and at which the transition piece (1) is connected to one each of the support members.16. The tower according to aspects12, characterized in that the transition piece (1) has elongate shapings (9) on the outer side (4) between the connection faces (7), which shapings preferably extend from a top side of the transition piece (1) to an underside of the transition piece (1).17. The tower according to any one of the preceding aspects, characterized in that the transition piece (1) is formed integrally.18. The tower according to any one of the preceding aspects, characterized in that the support members (13) have connection profiles (8) in an upper support member portion, for connection of the support members (13) to the transition piece, wherein a cross-section of each of the connection profiles (8) changes continuously along an elongate extent along a connection profile longitudinal axis (L) of the connection profile (8), preferably from the top toward the bottom.19. The tower according to any one of the preceding aspects, characterized in that the support members (13) in an upper support member portion have connection profiles (8) for connection of the support members (13) to the transition piece, wherein each of the connection pieces (8), in a cross-section along a connection profile longitudinal axis (L), has an outer contour running, preferably continuously, from top to bottom along an elongate extent and having a turning point.

LIST OF REFERENCE SIGNS

1transition piece1′ hollow structure2upper tubular tower portion2′ lower edge of the transition piece3inner lateral surface3′ opening3outer lateral surface3′″ lower base area of the outer lateral surface3″″ lower base area of the inner lateral surface4outer side4′ framed outer side5lower lattice-like tower portion5′ lower support member portion5′″ flange at the upper edge of the lower tower portion6upper connection element7connection face7′ concavely rounded groove at upper edge7″ concavely rounded groove at lower edge8connection profile8′ lower end of the connection profile9elongate recess10insert10′ the contour of the insert facing the profile element10″ underside of the insert11profile element11′ wall12insert recess13support member13′ support member flange14collar of the transition piece15connection profile flange15′ L-flange of the connection profile15″ bearing face of the L-flange16frame-like flange17cross strut18foundation18′ foundation surface19wind turbine20rotor blade20′ rotor blade path of movement21connection lines22cross-bracings23a, b, cedgesA lateral extent of the transition piecea1first, upper portiona2second, lower portionB1first transition regionB2second transition regionG total tower heightH height of the transition pieceK cone frustum longitudinal axisL connection profile longitudinal axisT central tower longitudinal axisTA support member longitudinal axisr1radius of curvature of the first circle of curvaturer2radius of curvature of the second circle of curvatureRu circumradius through the centroid of the support member cross-sectionsαi,βj,γkangle between support member and tower longitudinal axis, with i, j, k elements N+ε angle between connection faces and cone frustum longitudinal axisk1first circle of curvature for the concave outer contourk2second circle of curvature for the convex outer contourh collar heightr radius of the opening3′S1upper panel edgeS2lower panel edge