ES2369304B2 - REINFORCEMENT BASE FOR FUSES OF WIND TOWERS. - Google Patents

Abstract

Base reinforcement for tower shafts wind power

The invention is based on that on the section bottom of the shaft (2) corresponding to a wind tower (1), is they have lateral reinforcement elements (7 or 7 '), joined through from its upper part to the shaft itself (2), and through the part lower than the corresponding foundation base (6), setting a gap (8) between the reinforcement elements (7 or 7 ') and the own shaft (2), with an amplitude that is increasing progressively from the union of the upper part of the reinforcement elements (7 or 7 ') to the shaft (2) and the anchor of the lower end of those reinforcing elements (7 or 7 ') to the foundation base (6), thus achieving a way to reinforce the lower section of the shafts (2) of wind towers, which are subject to higher efforts, with minimal weight and consequent economic savings of material and costs.

Description

Base reinforcement for tower shafts wind power

Object of the invention

The present invention relates to a basement of reinforcement for shafts of wind towers, these may be concrete and / or steel.

The object of the invention is to achieve a Efficient and optimized solution for the bottom of the shaft corresponding to a wind tower, specifically in its union with the foundation, so that the shaft can be built as if outside a lower height and reinforce it with the basement of the invention, which is arranged externally, that is to say where It undergoes greater efforts.

It is also the object of the invention to achieve a structural solution in the most requested area, based on some semi-exempt reinforcing elements, providing advantages in terms of saving material and ease constructive

Background of the invention

The search for renewable energy sources is has increased in recent years, due to belief, every time more firmly, in the existing hypotheses about climate change and its relationship with the production of carbon dioxide and gases from greenhouse effect.

This search has promoted the appearance of new technologies that allowed to extract the maximum amount of energy from renewable energy sources such as sunlight and the wind. Not only have new technologies appeared but these are they are in a continuous process of improvement in order to increase Energy production yields.

The electricity produced by the wind turbines is based on the vertical wind profile curve, in which the wind speed is established based on the height and roughness of the wind
ground.

The wind turbine transforms a part of the energy that carries the volume of air that crosses the surface beaten by the blades, when it circulates at a speed greater than the threshold, below which, the blades do not move.

In the wind generation sector, it has produced an important and constant development during the last years, increasing the maximum power of wind turbines, reaching to unthinkable powers less than 10 years ago. This increase in power is based on two fundamental principles of generation wind as the sweep surface and the speed of the air.

The vertical wind profile has variation of parabolic slope, so that from a speed determined, the increase in wind speed with height, is Irrelevant. That is why, the dimensions of the blades and, consequently, the height of the wind turbine hubs, not it will increase unlimitedly but its roof has already been reached or is close to being achieved, since an increase in height It represents a significant increase in manufacturing costs, assembly and operation

To date, the realization of the steel shafts, due to its good fatigue behavior, its lightness and the great development of the industrial manufacturing process, Transport and assembly.

Most manufacturers make shafts of circular section and variable edge with conical shape, with the maximum diameter at the base, since it is the area with the actions of greater magnitude These shafts are made up of several subsections of the same length, generally, that are assembled at their ends either with screws or by other fixing systems.

However, despite its correct operation, concrete solutions began to be studied due to the volatility of the steel market in past years and the increase of the tough demands of large wind turbine shafts power.

The high volatility of the steel market during the years 2006 to 2008, it caused important disorders to shaft manufacturers, either because of price variability, at rise most of the time, or because of the delay in delivery of material. This forced wind turbine manufacturers to consider the concrete solution for the shafts of the wind turbines, not contemplated until that time due to the relative difference in costs between both solutions.

The need to raise the bushings of wind turbines above 80 meters, reaching 150 meters, greatly increased the magnitude of efforts, both static as dynamic, with their corresponding fatigue effects and durability. These efforts are not absorbed conveniently. for the current solutions used in lower height shafts, so the study and development of concrete shafts was obliged.

Wind turbine assembly was also started in shallow continental shelf areas, especially in the North Sea, which also increased interest in concrete shafts for durability reasons against attack Saline from sea water.

With the increase of the quality standards required in the new constructions, the introduction of the prefabricated in the wind turbines sector was a matter of time, since the quality control to which the manufacturing of the precast concrete elements is subjected, is superior , in general, that which is carried out in the works executed " In Situ ".

The use of precast concrete parts accelerates the assembly process, ensures an adequate geometry of the pieces and has a high quality of concrete. It also favors the production process, reducing costs and achieving an industrialization of the production of shafts, complicated to achieve by manufacturing on site , in each location where the wind farm is located.

Analyzing existing patents at the level worldwide, different solutions have been found whose differences with respect to the proposed model, they are explained to continuation.

Starting with the Office patents Spanish Patent and Trademark, we find patent ES 2317716 a Name of Gamesa Innovation and Technology S.L. in which it is exposed a shaft composed of two sections. The upper section is composed of a tube that can be cylindrical or Conical and lower trunk is a spatial lattice. The material constituent of both pieces is recommended to be steel. This solution differs markedly from the one presented because the geometry It is remarkably different.

Patent ES 2296531, also owned by Gamesa Innovation and Technology S.L, proposes a solution conical trunk for the shaft and made with concrete elements Prefabricated, united in work. The shaft is divided into segments of circumference joined together. This solution differs from the proposal since, although it is also made with elements of precast concrete, the shaft section is conical and not cylindrical, and does not carry the outer reinforcements that the shaft carries What is proposed. Nor do they coincide in the methods of joining pieces.

The company Vestas Wind Systems, is the owner of the patent ES 2297130, in which the formation of shafts from steel sections. This patent differs markedly from that presented, both in geometry and in the Main material used.

Patent ES 2319709, owned by the company Prefabricaciones y Contratas S.A., proposes an innovative mix shaft of precast concrete and metal structure, with a support in the tripod base, in which the possible legs are braced each. Again the solution differs markedly from the proposal since it needs bracing type crosses of San Andrés between the legs and throughout the section.

Patent ES 2246734 owned by Structural Concrete & Steel S.L., proposes the use of parts with nerves horizontal and vertical interior stiffeners of about 30-35 m in length, which together form the trunk conical shaft section. Again, this solution is limited to transfer the geometry of the frustoconical metal shafts to concrete, with the problem that this change implies. I dont know they find interactions with the recommended solution since the Reinforcements in this one are on the outer face.

From now on some patents will be analyzed German shafts for wind turbines.

Patent DE 19832921, owned by W. Bernhardt, proposes a mixed solution concrete-steel, through a hollow section of steel, which is subsequently filled with concrete, forming a section Composite Steel-Concrete-Steel. The correct union between the materials is achieved with bolts in the inside the hole, attached to both walls, so that there is a solid union between the three sections, since when concreting the hollow, the bolt heads are embedded in the solid. This solution, apart from having a truncated cone section, is far from both in the materials and in the geometry, of the proposal presented.

Patent DE 29809541, owned by R. Beyer, it also exposes a concrete shaft, consisting of sectors that are assemble, forming a truncated conical section, a distant solution notably of the proposed geometry.

Patent DE 102004048365, owned by O. Schneider, proposes a cylindrical section shaft with reinforcements annular exteriors attached to the shaft, punctually with pieces of nickel-chrome by screws. This typology is far from the recommended, since the nerves proposed stiffeners are joined by teeth in the body of tower.

Patent DE 202007003842 owned by Boehmert & Boehmert, proposes a pyramid-shaped shaft, consisting of cylindrical sections and straight sections linked together, forming a complete and closed shaft. This solution, again disagrees with the one proposed because it has a variable section and does not It has stiffeners.

Patent DE 202008001606, owned by P. Wetzel, proposes a truncated pyramid shaft, with live edges, and formed by straight panels without ribs. This solution disagrees deeply of the proposal, in the geometry of the section and in the absence of external reinforcements.

From now on some patents will be analyzed European shaft for wind turbines.

EP 1227204, owned by Ralf U. Hofmman, proposes a truncated conical shaft solution executed in situ , by means of climbing or sliding formwork. This solution differs from the proposal not only in the method of execution, but in the geometry of the section.

EP 1767729, owned by Sika Technology, proposes a trunk of conical trunk section, in which each a split type division has been made so that each shaft section consists of three segments joined by tongue and groove and with an inner filling. Again, the shaft with a transposition of the metallic solution to concrete, with the problem that the excessive amount of subsections originates in as far as the unions are concerned. There is no great similarity between this patent and the proposed solution.

EP 2182209, owned by Martin Glück, proposes a hybrid solution with the metallic upper zone and the lower concrete area, with a conical and prestressed section seen on the inside face. This solution continues to extrapolate the Trunk solution from steel to concrete, adding prestressing seen as a tie element between sections. They are not appreciated similar to the recommended solution.

From now on some patents will be analyzed Japanese shaft for wind turbines.

JP 2000283019, proposes a solution of truncated conical shaft, formed by truncated conical caps concentric superimposed, with shear keys on the support and with sleeve type joints between the connecting pieces. This solution continue with the truncated conical section and with the truncated conical tubes described in other previous patents, with the difference that the joints reflected in the drawing are insufficient and appreciate great difference with respect to the model presented.

JP2004011210 patent, owned by Fuji Corporation proposes a succession of circular section cylinders or polygonal, and of ascending diameter from the head to the base, joined with tongue and groove and with longitudinal prestressing and circumferential. These cylinders will eventually be divided into vertical sectors This patent takes the section solution cylindrical, in order to facilitate manufacturing, however, the lack of reinforcements forces to take a considerable diameter in the base, higher than estimated with reinforcements in the model presented.

JP2005180082 patent proposes a shaft with cylindrical section in several sections, its diameter being different in each section, with a maximum value in the embedment with the foundation and a minimum at the junction with the gondola. Account also with the use of a special piece, to make the transition from one diameter to another, and the union between modules is done with prestressing seen from the inside of the shaft. Again the Detailed solution, is based on superimposed cylindrical rings to form each subsection of the shaft, and anticipates that the section Cylindrical is a good solution to lower costs, but without However, it is far from the recommended solution with reinforcements radial in the lower zone.

JP2005220715 patent proposes a solution initial at the base of the truncated conical section and a final section cylindrical section. Each of the sections divides them into trunks of cone or cylinder, composed of subsections joined together by screwed horizontal and vertical tongue and groove, as if A metal joint will be treated. This solution differs markedly from The proposed geometry.

The JP2005248687 patent proposes a shaft solution built in situ , a solution markedly different from that recommended with precast concrete parts.

JP2005330675 patent proposes a shaft cylindrical formed by overlapping sections and assembled by prestressed. In addition, how much with an energy absorption system in earthquake case, based on metal parts that absorb part of the energy of the earthquake by hysteresis. This solution estimates that the Cylindrical section is the solution to the problem but does not consider the reinforcements at the base of the recommended solution.

JP2007046292 patent proposes a solution of Trunk conical shaft, consisting of truncated conical cylinders of a piece, in the upper zone, and cylinders composed of sectors conical, in the lower zone. The assembly between the sections is performs with some tubes on hold, so that the section of the tubes at the top of the piece, is larger than that of the part inferior, constituting the union by tongue and groove between the tubes The sections are provided with a circumferential rib interior to which a prestress will also be supplemented circumferential. This solution is based on the tongue and groove joint between modules through the tubes, it lacks reinforcement in the base and the section is helped by the connecting tubes, to obtain greater rigidity, so the differences with the recommended solution are big.

JP2007120080 patent proposes a shaft troncopiramidal, since it declares polygonal section instead of cylindrical The shaft length is divided into several sections pyramids The singing solution is used again variable, but this time with polygonal section instead of circular, patent that differs markedly in the geometry of the shaft recommended.

JP2007120080 patent proposes a solution with straight pieces of trapezoidal section, whose assembly produces a polygonal section of constant edge along the shaft. It divides the length of the shaft in several cylinders which in turn are subdivided in several pieces forming a polygonal prism. The pieces that they make up the cylinders in which the shaft is divided, they join together, by metal rings located inside the shaft, equidistant along the geometry of this. This union is made with screws. Two solutions are also proposed additional. The first one would be identical to the previous one, but regardless of one in two pieces of trapezoidal section, forming an open shaft. The other solution contemplates placement of these vertical pieces, radially, and joining these with the inner metal rings, constituting, again, a section open We believe that the solution of the rings is insufficient to withstand the efforts that come from the gondola, not only by the geometry of the metal part but by the fragility of the union with the screws. In addition, both alternative solutions, notably disagree with the recommended solution, both in geometry as in bearing capacity.

JP2008101363 patent proposes a solution of shaft divided into several prismatic sections, each being They divided into several vertical panels. These panels will have a part of his armor seen, bars that would be joined together by executing the filling of the board with a mortar and mechanical binding anchors.

This solution is composed of panels vertical, but these lack ribbed reinforcements such as solution that is recommended, in addition to having a joining method, which differs from the one presented.

JP2002122066 patent proposes a shaft of cylindrical section throughout the section, with reinforcements radial in the lower zone. This solution divides the shaft into several cylindrical prisms that are subsequently joined by a longitudinal post. At the bottom, some are placed T-shaped reinforcements, attached to the foundation by post-tensioned and attached to the shaft, with bolts.

This solution also adopts the shaft cylindrical as an optimal solution, providing it with reinforcing parts exterior at the base that help transmit loads to the foundation. The geometry differs from that recommended in this patent, in the following aspects:

to.

The reinforcements are external parts attached to the shaft at full height, at opposite of the solution that was recommended, where the external parts of reinforcement are semi-exempt, that is, they only join the shaft of discontinuously, providing effective reinforcements with less material.

b.

The reinforcements have a "T" shaped section contrary to what proposed in the patent application, in which the reinforcements they will have a rectangular or trapecial section, but never in "T"

C.

The reinforcements are screwed to the shaft only by the outer face of this one, realizing this union with radial anchors to the axis length of the shaft, such anchors being prestressed, either with bolts, bar or cable. However, in the proposed solution the reinforcements are attached to the shaft by teeth that are assembled in embedded in the shaft section.

d.

The reinforcements only carry prestressed in their union to the foundation, when contrary to the proposed solution in which the prestressing goes from the foundation to the top of the reinforcement, entering inside the shaft towards the special piece that supports the pre-tensioned anchors.

and.

The reinforcements do not carry longitudinal prestressing but only carry it transverse for attachment to the shaft, unlike the solution proposal, in which the stiffening or reinforcement ribs carry prestressing tendons throughout their length.

F.

All the sections of the shaft are the same, unlike in the solution proposal in which there is a notably more rigid special piece, whose function is to anchor the longitudinal prestresses of reinforcement nerves in the head.

From now on some patents will be analyzed North American shaft for wind turbines.

US 7464512, proposes a solution of metal shaft composed of several sectors that when joined together, They create the entire section. This proposal divides the shaft into several longitudinal sections, each of which is subdivided into several polygonal geometry caps. Each of these sectors metallic, covers an angle of between 90 and 120 degrees and has a polygonal section with a fold at each end, in which it makes the union by means of screws with the adjacent pieces. Eventually reinforcements will be placed inside the shaft with the in order to stiffen the joints. Although not specified in the text, in the drawings a tripod type geometry can be seen in the area of the base, to brace the shaft at medium height.

This solution differs markedly from the proposal, since the section is made of steel and not concrete prefabricated. Nor does the method of stiffening of the shank.

US patent 2009000227 proposes a shaft mixed, divided into three sections. The lower section is conical and of concrete, the intermediate section is metallic of cylindrical section and The upper one is also made of steel but with a truncated conical section.

This solution uses a solution Conical trunk, different from that recommended and lacks reinforcements in base.

US patent 2009031639 proposes a solution new shaft, with truncated pyramid section in the lower section and cylindrical section of steel or concrete, in the upper section. He lower section, is divided into tubular sections, which they are formed by a succession of straight and curved pieces, intertwined with each other, which form the entire section. These pieces It is joined by circumferential prestressing.

The geometry of this solution differs notably from the proposed proposal.

US Patent 2007181767 describes a prefabricated foundation for wind turbine shafts, in whose part the top would anchor the shaft.

This solution cannot be compared with the recommended, since it has the objective of transferring the loads to the terrain through prefabricated parts as opposed to requested where the basement transmits the loads to the foundation, so that later it transmits them to the land.

From now on some patents will be analyzed International of shafts for wind turbines.

WO 0201025, proposes a trunk conical concrete shaft with longitudinal prestressing, anchored in the foundation and made in situ .

This geometry differs from the one recommended and not It is formed by a succession of prefabricated pieces.

WO 0204766 proposes a shaft pre-fabricated concrete trunk, consisting of sections of identical height and variable edge, joined together by longitudinal prestressing

This section, again because it is an imitation of the existing solutions in steel, but transferred to concrete, with the problems involved. This geometry differs from that recommended because it lacks
of reinforcements in the base and has variable section.

WO 03069099 proposes several solutions for the shaft, all of them prefabricated. The first of they consist of a trunk shaft, truncated pyramid, formed by longitudinal pieces of constant section and between one and several bankruptcies in the transverse direction, which, when assembled, form a closed section This sequence of sections, result of assembly, are placed keeping the cloths, so the edges in geometry, they are maintained throughout the entire shaft.

Another variant of the previous solution, consists in breaking these edge alignments, placing the sections rotated a certain angle, thus avoiding the formation of edges constants along the alignment.

This patent also indicates a solution of cylindrical shaft, divided into vertical sections, each being They divided into 8 cylinder sectors, assembled together. For avoid the appearance of weak points in the shaft, avoid creation of constant joints along the shaft, placing each stretch to the tresbolillo, avoiding the coincidence of the joints vertical in adjacent sections. In other drawings the shaft solution formed by a succession of cylindrical sections with specific section reductions, maintaining the same exploded view than in the constant cylindrical solution.

While this patent describes a multitude of solutions formed by panels that, when assembled, they form a composite section, these panels do not have the ribs of the recommended solution.

WO 2007025947 patent proposes a shaft in situ , with concreting by pump with vertical upward flow. With this system, the different sections into which the shaft has been divided are successively concreted, causing the set parts to rise due to concrete pressure. In addition, it is essential to tighten the head of the built shaft, to avoid bending that could collapse the shaft during the concreting phase or lifting at each interface.

In this patent, a geometry in itself is not defined, but rather a method of making spindles for wind turbines in situ , which is clearly far from the recommended solution.

WO 20100.32075, proposes a shaft of mixed pyramidal section, concrete-steel. This solution creates an open shaft, in which the section takes the form of a tetrahedron, in which the rising edges, are sectors circular concrete and these are braced together, with a latticework in each of the planes that form the pyramid. Of this mode you get a lighter section, which takes advantage of the singing total section, but that is more complex in its assembly and design, since although the concrete pieces are all the same in the entire height of the shaft, the lattices are of variable edge from The base to the head.

The differences between this solution and the recommended, they are remarkable, not only in geometry but in the Composition of the materials used.

WO 2010044380, proposes different solutions that will be analyzed in detail. The development of the patent, describing a section prismatic shaft solution octagonal and constant singing. This shaft so defined, would be divided, longitudinally, into rings of a certain height, and in turn, each ring would consist of 4 caps in the form of "C" joined with circumferential post-tensioning. The alternate rings they would have nerve reinforcements on their outer face, and the union among all the rings, both the ribs and the smooth ones, are would perform with longitudinal posts.

The next proposed solution consists of a cylindrical shaft, also divided into rings, but with a reinforcement helical on the entire outer face of the prefabricated, from the base up to the head

Other proposed solutions are similar to different patents set forth above, either by means of a shaft truncated pyramid, truncated cone and an original shaft with circular reinforcements of variable diameter, of doubtful utility structural.

Analyzing all these typologies exposed in The patent described, we found no reasonable resemblance regarding to the proposed proposal, since reinforcements are not described continuous stiffeners of the shaft, in contact with the foundation.

From now on, some patents of different countries, with geometries similar to those of the shafts for wind turbines

The GB 741869 patent proposes different solutions that will be analyzed in detail. The first of claims that it is a reinforced concrete structure for chimneys or hollow columns, unlike the solution recommended that the concrete is longitudinally prestressed and It is made with prefabricated elements.

In the second of the claims it is stated that the maximum height at which the buttresses reach is, approximately one third of the total height, because the only solicitation that the chimney must withstand is the action of the wind, when in the recommended solution, this length is not discussed, since that this depends a lot on the type of wind turbine that is going to place in head and of the loads that this transmits to the shaft.

The third claim indicates that the Reinforcement song varies from foundation to head, as in the recommended one, but with the difference that nerves are lightened, compared to the massifs of the patent English

In the fourth claim, it is stated that the width of the reinforcements is approximately one quarter of the cylinder diameter, when this ratio in the solution advocated has not been exposed, due to the diversity of actions different that can be requested depending on the type of turbine Let it mount.

In the fifth claim it is said that the piece will carry six buttresses, when in the recommended solution, no indication has been made as to the number of ribbed reinforcements.

The sixth claim refers to the stiffeners form at the same time with the cylindrical section, when contrary to the recommended solution in which reinforcements are join the cylinder with a gear that transmits the efforts flush.

The FR 2504966 patent proposes different solutions that will be analyzed in detail. One of the claims indicates that it is a chimney or similar, made with reinforced concrete elements, a statement that is far from the recommended solution indicating that it is concrete prestressing made with prefabricated parts.

Another claim indicates that there is a ring piece, in the area where reinforcements end, placed on a sealer, but in the sections, this piece has the same hollow free than the rest and there is also talk of a number of ribs not less than 3 and that have reinforcement braces, solution that is far from the recommended one since the special piece has solid interiors for anchoring the cables of prestressing of the reinforcements and goes together in solidarity with the rest of the structure. Both solutions also differ in that reinforcements are not armed but prestressed, with a prestressed longitudinal.

It is claimed that the flush union between reinforcements and the body is done with armed, unlike in the recommended solution in which this union is made with a teeth between the reinforcements and the body.

Another point indicates that the union of armor is made with sleeves, which differs markedly from the recommended solution since the unions will be made with continuous prestressing between anchors, so they are not applicable the sleeves

In general, large differences are appreciated between this patent and the recommended one.

Description of the invention

The recommended solution has been conceived to join the upper section of the shaft of the tower, meanwhile bottom, with the foundation, in order to avoid the realization of large pieces of variable edge for the shaft. In this way the Tower structure can be manufactured with more sized pieces moderate, with the simple addition of reinforcements in the area of basement, simplifying transport work and elevation.

The reinforcing elements are joined by their upper end to the lateral and external surface of the shaft, while on the bottom they are attached to the corresponding foundation or base of the wind tower, so that each reinforcing element is distancing itself, that is, separating from the upper end of union to the shaft, to the lower end of union to the base or foundation, establishing a gap whose amplitude it is progressively growing from the commented end of union upper than the shaft to the referred lower end of union to the base or foundation.

In this way it is achieved that the shaft can have a uniform configuration throughout its height, preferably cylindrical, bringing the manufacturing and construction process It is much simpler than the usual solution with trunk-conical configuration.

The reinforcement elements are sectional transverse rectangular or even trapezoidal, being in all semi-exempt cases, that is to say that they join in a timely or linear way, but with a development limited to the shaft and the foundation, thus also simplifying the construction and manufacture of pieces.

The commented semi-reinforcement reinforcement elements they can materialize in concrete, steel, mixed, or even in other types of appropriate materials, always helping the section main to withstand the efforts transmitted by the turbine of the wind turbine.

In short, based on the proposed solution manufacturing is much easier than when the shaft of the tower is trunk-conical, since the geometry of all the pieces that make up the main section will be identical each other, so in the case of precast concrete parts may reduce investment in molds, while in case of shaft Metallic rings contain less welds. They are also provided collection, transport and assembly due to the versatility of the pieces.

Also noteworthy is the fact that reinforcement elements, by establishing a gap between them and the fuste, suppose a great lightening, since it optimizes the distribution of its volume, which results in weight savings and in material.

It is also worth noting the fact that reinforcements can present a variable song, depending on their height, its preferably rectangular section being uniform, trapecial, as said before, without ruling out other sections that fit the material generally chosen for the building.

Regarding the union of the elements of reinforcement to the shaft, they will be made by teeth that assembled in boxes established for this purpose in the section of own shaft. In addition, the reinforcing elements according to the invention carry prestressed from the foundation to the top of the same, entering inside the shaft towards a piece special that will support the anchors of the prestressed.

Description of the drawings

To complement the description that is being performing and in order to help a better understanding of the characteristics of the invention, according to a preferred example of practical realization of it, is accompanied as an integral part of said description, a set of drawings where with character Illustrative and not limiting, the following has been represented:

Figure 1.- Shows a representation side elevation schematic of a wind turbine tower with the reinforcement base in which the reinforcement elements proper are semi-exempt, all done according for the purpose of the invention.

Figure 2.- Shows a side view in detail of the bottom of the shaft, as well as the base of foundation and external reinforcement elements, made of according to the object of the invention.

Figures 3 and 4.- They show each section cross-sections corresponding to the union of the elements of reinforcement to the shaft, and the separation or gap established between said reinforcement elements and the corresponding foundation base to the They join them.

Figure 5.- Shows a variant of realization of the lower reinforcement basement represented in the figure 2, this embodiment variant corresponding to elements of reinforcement of smaller width and attached to the shaft through points by means of a lattice of bars.

Figure 6.- Shows, finally, a detail in section of the embodiment represented in the previous figure in what which concerns the union between the reinforcement elements and the shank.

Preferred Embodiment of the Invention

As you can see in the referred figures, the wind tower referenced in general with the number (1) includes a shaft (2) in whose upper part the corresponding one is mounted wind turbine (3) with the blades (4) that form the corresponding wind turbine rotor. The shaft (2) is fixed on the ground (5) a through a base or foundation (6), forming all the set of the wind tower (1).

Well, according to the invention, the shaft (2) and in correspondence with the lower section thereof, is complemented by reinforcing elements (7) according to a radial arrangement and longitudinal, those reinforcement elements (7) being of section preferably rectangular, without discarding other configurations

In any case, the reinforcing elements (6) they are joined by their part or upper section to the lateral surface of the shaft (2), while at the bottom they join the base of foundation (6), with the special feature that the elements reinforcement (7) from its upper connection to the shaft (2) to its union to the foundation base (6) they run obliquely, that is with progressive separation of the shaft itself (2), causing gaps (8) between said shaft and the inner edge of the elements of reinforcement (7), as clearly depicted in Figure 1, resulting in these reinforcing elements (7) being semi-exempt, being fixed to the lateral surface of the shaft (2) by its section superior, based on accommodation in cavities established for this purpose on the lateral surface of said shaft (2) while on the bottom part is embedded on the foundation itself (6).

In a variant embodiment shown in the Figures 5 and 6, can be seen as the reinforcing elements (7 ') they are smaller in terms of their section, and join as in the previous case to the shaft (2) through the section or upper part of said reinforcing elements, while for the bottom are fixed to the corresponding foundation base (6), remaining also the gaps or spaces (8) between the shaft and the reinforcement elements themselves (7 '), with the special particularity that in this case or embodiment variant such reinforcement elements (7 ') are also connected with braces in lattice (9), but always keeping the gaps (8) where it is not It establishes union.

Finally say that it is evident that in the different unions between the reinforcement elements themselves semi-axes (7 or 7 '), the shaft (2) and the foundation base (6), are will carry out with the complement of the corresponding meetings in order to get a totally resistant and practical structure in your functionality and construction process.

Claims (4)

1. Basis of reinforcement for shafts of wind towers, where the shaft (2) of the wind tower (1) mounts a wind turbine (3, 4) on top to obtain electrical energy based on the force of the wind that it affects the blades (4) of the wind turbine, and where the shaft (2) is of uniform section, preferably circular, and is constituted in concrete, said shaft (2) being mounted on a foundation base (6) and provided with its lower part with lateral and external reinforcements in the longitudinal direction, characterized in that the lateral reinforcements of the shaft (2), materialized in semi-exemplary elements (7 or 7 ') of concrete, are fixed to said shaft by means of teeth that are assembled in established holes for this purpose in the section of the shaft itself, while at its lower end they are attached to the corresponding foundation base (6), establishing a gap (8) between each reinforcement element (7 or 7 ') and the shaft (2). growing since the union d the reinforcement element itself (7 or 7 ') with the shaft (2) to the foundation base (6), said reinforcement elements being provided to include prestressed from the foundation to the top thereof, entering inside of the shaft towards a special piece that will support the anchors of the prestresses. 2. Reinforcement base for wind tower shafts, according to claim 1, characterized in that the reinforcement elements (7 or 7 ') are rectangular in section. 3. Reinforcement base for wind tower shafts, according to previous claims, characterized in that the reinforcement elements (7 or 7 ') are of uniform section throughout their length. 4. Reinforcement base for wind tower shafts, according to claims 1 and 2, characterized in that the reinforcement elements (7 or 7 ') are of variable section throughout their length.