This application is a National Stage completion of PCT/EP2017/000237 filed Feb. 20, 2017, which claims priority from European patent application serial no. 16000441.2 filed Feb. 24, 2016.
The invention relates to wind turbines which, besides the usual devices for damping various vibrations occurring in the installation, are fitted with novel elastic ball/pendulum bearings. These ball/pendulum bearings can in principle be used for cardanic suspension of a pendulum absorber, preferably in the tower of a wind turbine, and also for attachment of the cable of floating offshore installations to the bottom of a body of water. The invention also relates to the corresponding equipped vibration pendulum absorbers as such which have additional damping devices for decreasing or reducing torsional vibrations of the pendulum, which may occur during oscillation of the pendulum, for example in the wind turbine, in particular on impact of the pendulum.
In accordance with the prior art, pendulum bearings in wind turbines are usually suspended using shackles, which, apart from the frictional forces, do not themselves make any contribution to damping of the pendulum movement. Shackles of this type, which in their simplest embodiment are U-shaped bars which can be closed by means of a threaded or unthreaded bolt, are, however, subject to considerable wear, meaning that they must be subjected to constant monitoring, since there is a risk of the pendulum cable falling off together with the absorber mass with increasing operating time.
As an alternative to the said simple suspension. Cardan joints have in the meantime also been used in the prior art, but these have the disadvantage of being relatively complex and expensive owing to their increased wear in the region of the sliding or roller bearings used.
Elastic pendulum joints have also occasionally been proposed in the prior art, but, in their known design proposals, they introduce great rigidity into the oscillation system, which is in principle undesired for use in wind turbines, so that, due to the known relatively great temperature dependence of the elastic materials, the resonant frequency of the absorber system is influenced and altered in an unforeseeable manner depending on the temperature. This in turn requires increased complex adaptation of the oscillation system.
The object was thus to provide a pendulum absorber, in particular for use in wind turbines, having a suspension or joint bearing which has improved properties in the said respect compared with the known solutions from the prior art, where importance should be attached, in particular, to high axial strength, a low restoring moment, and a highly insignificant influence on the resonant frequency of the system and thus on substantial temperature independence.
The object set has been achieved by the subject-matters of the invention specified and described below and in the claims.
The invention thus relates to a wind turbine comprising at least one elastic bearing which is a ball/pendulum bearing, which in turn comprises a ball joint (5) having an inner joint head (5.4) and a joint socket (5.5), where the joint head has an at least hemispherical shape and is mounted in the corresponding dimensioned and shaped joint socket, and at least one, preferably two or three elastomer layers (5.1) are arranged between joint head and joint socket in such a way that at least 80%, preferably 90-100% of the area of the elastomer layer is firmly connected to the spherical areas of the joint head and joint socket, and the elastomer layer has a thickness of 5 mm-20 mm, where, in the case of the presence of a plurality of elastomer layers, these are completely or partially separated from one another by intermediate metal sheets (5.3).
In a preferred embodiment of the invention, the said ball/pendulum joint or bearing has two elastomer layers which are separated from one another by a metal sheet, which is preferably interrupted in the central region of the elastomer layer (
It has been found that such joint heads and corresponding joint sockets which have at least a hemispherical shape, but preferably a part-spherical shape with a circle radius or wrap angle of 180° to 325°, preferably 180° to 245°, or 220° to 245°, should advantageously be employed, where if possible the entire spherical surfaces are covered with an elastomer layer. Only in the case of this design measure is the pendulum bearing able to move through large angles in a small space while accommodating large forces without the resonant frequency of the system, or of the wind turbine, being significantly influenced.
In a particular embodiment of the invention, the elastomer layer (5.1) between the spherical joint head (5.4) and the spherical joint socket (5.5) may have different stiffness, in particular with respect to the axial orientation of the pendulum and the horizontal orientation of the pendulum perpendicular thereto, or in other words with respect to the centre of the respective sphere compared with the edges. The can be achieved in accordance with the invention by two measures. On the one hand, the elastomer material can be of different stiffness at the point in question, or the regions in question, so that the deflection properties of the pendulum can be influenced thereby without the damping properties of the pendulum absorber changing significantly at the same time. Different stiffnesses can be achieved, for example, through the use of elastomer material having different Shore hardness.
On the other hand, it may be provided that the elastomer material contains specifically positioned (for example at the zenith of the joint head sphere) chambers which can be filled from the outside with a fluid under pressure via a valve (
The chambers may also in principle form due to the injection of fluid in a region in which elastomer layer and metal of the joint bearing are not firmly connected to one another, or in with a region inside the elastomer layer in which elastomer material only lies on one another and can be stretched under pressure to form a chamber.
The invention furthermore relates to a corresponding wind turbine in which the ball/pendulum bearing is part of a pendulum vibration absorber which comprises a pendulum rod (2) and an absorber mass (1), where the pendulum absorber is able to move freely in all directions around the elastic ball/pendulum bearing, and preferably has a device in the region of the ball/pendulum bearing which reduces or prevents torsional vibrations of the absorber.
In a first embodiment of this type (
In a further embodiment of the invention, the device comprises at least three spring elements (8), which are distributed essentially uniformly around the pendulum rod (2) in the region of the pendulum joint (5) and are arranged in such a way that torsional movements of the pendulum (2) can be damped or prevented (
Essentially the same effect is achieved by the further embodiment according to the invention of
In a very specific simple embodiment of the invention, the device for damping torsional movements of the pendulum comprises a pendulum yoke (2.2)(2.3) having elastic stop elements (10) in the region of the pendulum joint (5), as depicted, for example, in
In further embodiment of the invention, the said devices for damping the torsional movement of the pendulum can be formed by combinations of the said embodiments. In particular, the use of a pendulum yoke can be combined with a spring device or a connecting rod device.
The described pendulum joints according to the invention are also eminently suitable for use in offshore platforms of various use, for example wind turbines or oil rigs for movable attachment of the platform to the sea bed. The invention thus also relates to an offshore platform (18), in particular for wind turbines, which is anchored via cables (15) to the sea or ocean bed (12) via foundations (11), with each cable (15) being attached, by means of cable attachments (14), to the platform via a said upper ball joint (17) according to the invention and to the foundation via a said lower ball joint (16) according to the invention. An application of this type is depicted in
The invention also relates to a corresponding pendulum vibration absorber, comprising a pendulum rod (2) or pendulum cable, at least one absorber mass (1) and an elastic ball joint (5) at the upper end of the pendulum rod/pendulum cable, where
comprises at least one torsion lever (2.1) which is installed essentially perpendicular to the pendulum rod (2) and has an elastic torsion bearing for pitch movements (6) and an elastic torsion bearing for axial rotational movements (7) of the pendulum (1, 2), or
has at least three spring elements (8) which are distributed essentially uniformly around the pendulum rod (2) in the region of the pendulum joint (5) and are arranged in such a way that torsional movements of the pendulum (2) are damped or prevented, or
has at least three connecting rods (9) with elastic spherical bearings (9.1, 9.2) which are distributed essentially uniformly around the pendulum rod (2) in the region of the pendulum joint (5) and are arranged in such a way that torsional movements of the pendulum (2) are damped or prevented, or
has a pendulum yoke (2.2)(2.3) having elastic stop elements (10) in the region of the pendulum joint (5) and is arranged in such a way that torsional pendulum movements are damped or prevented, or
comprises combinations of the device elements from (ii) to (iv), in particular (ii) and (iv), or (iii) and (iv).
Finally, the invention also relates to wind turbines and pendulum vibration absorbers which, apart from the torsion damping elements described, additionally have damping elements which are capable of damping the various vibrations occurring in the installation. These can be prior-art eddy current dampers, hydraulic dampers or other temperature-independent dampers (e.g. WO 2013/023728, WO 2014/102016, WO 2016/023628).
The reference numerals used in the figures, in the text and in the claims are described briefly below:
Further details of the invention are described below, in particular with reference to
The absorber system described has a low restoration moment at the same time as high axial strength, so that the influence of the elastomer on the resonant frequency has only a very insignificant influence on the resonant frequency of the system and thus the temperature dependence also becomes negligibly small.
This property is achieved by one or more hemispherical elastomer layers stacked one above the other. Owing to the large sphere envelope surface area and the particularly thin layers, high axial stiffnesses are thus achieved, which enables the transmission of correspondingly large axial forces.
The ratio of the axial stiffness to the torsional stiffness increases with increasing wrap angle, which is why wrap angles of the ball elements of greater than 220°, in particular between 220° and 325°, or 220° and 245° are particularly suitable. An embodiment of this type is depicted in
The cardanic stiffness of the absorber can be reduced further by introduction of a fluid (5.6), since no elastomer deformation takes place in the region of the fluid. The elastomer deformation only takes place in the region outside the fluid, so that only a relatively small elastomer region is deformed, which causes lower push forces and thus lower cardanic forces. As depicted in
A conventional pendulum absorber usually has an absorber mass which strikes the wall of the tower of the wind turbine via a stop system. In this case, it may occur that the absorber strikes the curvature tangentially and thus experiences a relatively large torsion moment. This torsion moment is transmitted to the ball joint via the pendulum rod. However, the ball joint has only low torsional stiffness, meaning that it is necessary to absorb this by means of a further construction. The angle of rotation of the absorber must not be too great here in order not to stress the connection to the dampers. The solution according to the invention is depicted in
As an alternative to one or more torsion levers, as described, it is also possible to employ spring elements or elastic elements, as shown in
The embodiment in accordance with
A completely different application for the elastic ball/pendulum bearings is the connection and attachment of offshore platforms, in particular in connection with wind turbines or possibly other floating installations (
The elastomer layers in the ball/pendulum bearings according to the invention can have different thicknesses, which, however, vary predominantly between 5 mm and 20 mm. If two layers are used, the inner layer advantageously has only about 50-70% of the thickness of the outer layer, which is vulcanised to the joint socket. An elastic inner layer has a thickness of between 4.5 and 9 mm, whereas an elastic outer layer can have a thickness of between 6 and 12 mm. The Shore hardnesses of the elastomers used in the ball/pendulum bearings according to the invention can be between 50 and 100 Shore A.
Number | Date | Country | Kind |
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16000441 | Feb 2016 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2017/000237 | 2/20/2017 | WO |
Publishing Document | Publishing Date | Country | Kind |
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WO2017/144167 | 8/31/2017 | WO | A |
Number | Name | Date | Kind |
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3025090 | Langen | Mar 1962 | A |
9302940 | Bullerjahn et al. | Apr 2016 | B2 |
11603821 | Mitsch | Mar 2023 | B2 |
20080296901 | Liu | Dec 2008 | A1 |
20170219045 | Glanzner | Aug 2017 | A1 |
20200158083 | Nitsche | May 2020 | A1 |
20220228393 | Hansen | Jul 2022 | A1 |
Number | Date | Country |
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1 105 738 | Apr 1961 | DE |
1 008 747 | Jun 2000 | EP |
2013023728 | Feb 2013 | WO |
2014102016 | Jul 2014 | WO |
2016023628 | Feb 2016 | WO |
Entry |
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English machine translation of EP 1 008 747 A2, Apr. 15, 2022. |
Machine Translation of EP 1,008,747 B1, retrieved from the Espacenet (May 20, 2023) (Year: 2023). |
International Search Corresponding to PCT/EP2017/000237 dated Jun. 28, 2017. |
Written Opinion Corresponding to PCT/EP2017/000237 dated Jun. 28, 2017. |
Number | Date | Country | |
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20190055982 A1 | Feb 2019 | US |