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TEPZZ86Z54A_T(11) EP 2 863 054 A1

(12) EUROPEAN PATENT APPLICATION

(43) Date of publication: 22.04.2015 Bulletin 2015/17

(21) Application number: 14003472.9

(22) Date of filing: 09.10.2014

(51) Int Cl.:F03D 11/04 (2006.01) E04H 12/00 (2006.01)

(84) Designated Contracting States: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TRDesignated Extension States: BA ME

(30) Priority: 18.10.2013 ES 201300989

(71) Applicant: Gamesa Innovation & Technology, S.L.31621 Sarriguren (ES)

(72) Inventor: Unanua Hermoso de Mendoza, Pablo31621 Sarriguren (ES)

(54) REINFORCED HOLLOW FOR A WIND TURBINE TOWER

(57) Reinforced hollow for a wind turbine tower com-prising a lower ring (2) that determines an opening (3)for the installation of an access door (not represented)inside the tower (1). The hollow incorporates at least onestructural element (4) that is fastened on both sides ofthe opening (3) of the towers lower ring (2), providingthe rigidness necessary to attach a door and permit thereduction of the thickness of the ring by 10-20%.

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Description

Field of the invention.

[0001] The present invention is related with wind tur-bine tower doors and, particularly with the hollows cutinto wind turbines to install these doors.

Background of the invention.

[0002] Conventional wind turbines comprise a towerfirmly anchored to the ground, a nacelle at the top of thetower, and a rotor equipped with at least one blade. Re-cent tendencies in wind turbine construction entail in-creased power and towers of greater height.[0003] Wind turbine towers are constructed in sec-tions, which comprise flanges and rings, that determinea thickness of 15-60 mm depending on the height of thetower and the rotor installed in the wind turbine. Eachsection is coupled to the adjacent section (upper and/orlower) by flanges that are bolted together.the lower part of the wind turbine tower has an accessdoor that enables workers to enter the wind turbine toundertake maintenance tasks. This access door is in-stalled in a hollow or through opening made into the lowerring of the tower. The problem addressed here is the lossof ring strength and rigidness when this hollow is made.[0004] Wind turbine tower manufacturers normallytend to reinforce this area with frames for the door or byincreasing the thickness of the ring in the area, but thisextra rigidness proves complex and expensive to pro-duce.[0005] An example of solutions of this sort is describedin patent CA 2464623, which claims a structural member(frame) that is welded onto the hole made on the lowerpart of the tower to accommodate a door.[0006] Other solutions are known such as the one de-scribed in patent EP 1856410, which proposes a lowerring manufactured in two parts onto which a door frameis mounted so that one of the parts of the ring, the oneonto which the door will be mounted, will be thicker thanthe other part of the ring. This thus permits a thinner frameto be installed depending on the increase in ring thick-ness. However, this solution is inefficient, since it sub-stantially increases the weight and mass of this lowertower ring.

Description of the invention

[0007] One object of the invention is to provide at leastone structural element that enables the incorporation ofa door to the towers lower ring that would enable the ringthickness to be reduced.[0008] Another object of the invention is to provide atleast one structural element that enables the incorpora-tion of a door to the towers lower ring without the needto have previously installed a door frame.[0009] For the foregoing, the invention envisions the

incorporation of at least one structural element compris-ing a pair of beams to provide the rigidness necessaryto attach a door to the towers lower ring and thus permitthe reduction of the ring thickness by 10-20%.[0010] The structural element is mounted by weldingon both sides of the lower ring opening and can be mount-ed inside or outside the tower. This welded coupling isfurther strengthened by applying currently known Stateof the Art methods for enhancing resistance to fatiguesuch as Burr Grinding or Tig Dressing.[0011] The door, in turn, can be secured either to theopening in the ring or to the structural element, and doorhinges can be secured to either the ring or structural el-ement.[0012] These and other aspects of the invention will bedescribed in more detail with the help of the drawingsshown below.

Brief description of the drawings

[0013]

Figure 1 illustrates an front view of a wind turbinetower with a hollow in the lower ring for incorporatingthe access door.

Figures 2 and 3 are front and side views of the windturbine hollow according to the invention.

Figure 4 is a cross section illustrating the hollow onthe lower ring of the tower according to the invention.

Description of a preferential embodiment.

[0014] Figure 1 illustrates the lower ring (2) of a windturbine tower (1) that has an opening (3) for subsequentlyinstalling an access door (not represented).[0015] The invention, as illustrated in figure 2, incor-porates at least one structural element (4) comprising apair of beams on both sides of the opening (3) of thelower ring (2) that can be mounted either inside or outsidethe tower and provide the rigidness necessary to be ableto install a door on the lower ring (2) of the tower.[0016] Each one of the structural elements (4), i.e.,each beam, mounted on the sides of the opening (3) inthe lower ring (2) of the tower, determines its upper (5)and lower (6) inclined edges (see figure 3). This inclina-tion within a range of 1/4 - 1/5 guarantees the minimiza-tion of maximum stress while augmenting the resistanceto fatigue of the structural element (4).The beams preferentially determine a length (L) of 3-5meters in height and a thickness (e) of 20-35mm, thoughthis would depend on the size of the opening (3) madein the lower ring (2).[0017] The structural element (4) is fastened to the low-er ring (2) from inside the tower through welding, althoughit could also be done from the outside, complementingthis welding in both cases with conventional techniques

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such as Burr Grinding or Tig Dressing.[0018] The door hinges (not represented) can be fas-tened to the ring (2) or the structural reinforcement ele-ment (4) of the invention.

Claims

1. Reinforced hollow for a wind turbine tower of the typethat comprises a lower ring (2) that determines anopening (3) for installing an access door (not repre-sented) inside the tower (1), characterized becauseit incorporates at least one structural element (4) thatis fastened on both sides of the opening (3) of thelower ring (2) in the tower and because this structuralelement (4) comprises at least two beams.

2. Reinforced hollow for a wind turbine tower accordingto the first claim, characterized because the struc-tural element (4) is welded to the ring (2).

3. Reinforced hollow for a wind turbine tower accordingto the first claim, characterized because the struc-tural element beams (4) determine their upper (5)and lower (6) inclined ends.

4. Reinforced hollow for a wind turbine tower accordingto the third claim, characterized because the slopeof the ends (5, 6) of the beams on the structural el-ement (4) are in a range of 1/4 to 1/5.

5. Reinforced hollow for a wind turbine tower accordingto the first claim, characterized because the accessdoor hinges (not represented) can be fastened to thestructural element (4) or directly to the lower ring (2)in the tower (1).

6. Reinforced hollow for a wind turbine tower accordingto the first claim, characterized because the beamson the structural element (4) determine a length (L)of 3-5 meters in height and a thickness (e) of 20-35mm.

7. Reinforced hollow for a wind turbine tower accordingto the first claim, characterized because the struc-tural element (4) can be fastened inside or outsidethe tower (1).

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REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the readers convenience only. It does not form part of the Europeanpatent document. Even though great care has been taken in compiling the references, errors or omissions cannot beexcluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description

CA 2464623 [0005] EP 1856410 A [0006]

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