Source: https://patents.google.com/patent/EP1295032B1
Timestamp: 2018-04-23 03:42:59
Document Index: 419709339

Matched Legal Cases: ['art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art. 102']

EP1295032B1 - Blade of a wind turbine - Google Patents
EP1295032B1
EP1295032B1 EP20010948133 EP01948133A EP1295032B1 EP 1295032 B1 EP1295032 B1 EP 1295032B1 EP 20010948133 EP20010948133 EP 20010948133 EP 01948133 A EP01948133 A EP 01948133A EP 1295032 B1 EP1295032 B1 EP 1295032B1
EP20010948133
EP1295032A1 (en )
The present invention relates to a blade of a wind turbine, comprising a connection part provided at one end with connection means, for connection to the shaft/hub of a wind turbine, and a wind-energy-absorbing profile which is optimized for the wind flow and extends from the other end of the connection part, the connection part being provided with a member that is designed in such a way that the assembly comprising the member and the connection part can absorb wind energy, which member comprises a rib that projects from the connection part as specified in the preamble of claim 1.
Such a blade is known from US 3874816A, which discloses a rigid blade root end member fitted on the downstream side of the blade. This end member serves mainly to reinforce the blade structures, which in the case of this US patent specification is made of flexible material such as cloth and clamped on the connection part.
In the prior art, where the blade is made of a rigid, non-deformable material, and where the wind-energy-absorbing profile is expensive to produce and is of an elongated design, it is opted to fit a connection part between the wind-energy-absorbing part and the shaft/hub of the wind turbine. On the one hand, the connection part is cheap to produce and, on the other hand, it is designed in such a way that simple connection is possible, large torques being effectively transmitted. Since the torque of the aerodynamic forces increases with decreasing distance from the shaft, and since the surface area passed through by a blade part decreases - and consequently so does the share in the energy output - with decreasing distance from the shaft, the blade cross section in the direction from tip to connection end acquires an optimization which runs from generally aerodynamic to generally structural. In particular, this connection part will comprise a tube. Since the connection part is situated near the centre of rotation of the wind turbine, the loss that occurs through the cross section not being optimized for the wind flow is less than the costs necessary for making a profile that is optimized for the wind flow, such as that fitted on the other side of the connection part. If the connection part is, for example, a tube, the costs of that tube per metre are many times lower than the costs of the wind-energy-absorbing, wing-like profile fixed on it. In addition, it is simple to connect a tube in a particularly sturdy manner to the remaining pan of the structures, by means of, for example, a flange. The term connection part in the description and claims should be understood as meaning that part of a blade that is optimized for the structures, and not so much optimized for the absorption of wind energy. Such a part is characterized by a low natural speed, and it absorbs little in the way of wind forces. In general, it can be said that it does not comprise the part from the free end onwards with increasing chord, but it does comprise the part beyond the maximum chord, in other words the part with decreasing or invariable chord. The connection part can be connected with a separate flange to the aerodynamice wind-energy-absorbing profile.
According to the invention, the existing connection part is retained in principle unchanged, except that it is provided with a member. According to an advantageous embodiment of the invention, said member can be a simple rib which is fitted on the connection part. Such a rib can be of a slightly curved shape, or it can simply be of a design that extends perpendicular to the connection section. Such a member comprises a rib that extends from the connection part, fitted in an area bounded, on the one hand, by the surface of the wind-energy-absorbing profile in its most effective position and bounded, on the other hand, by the surface clamped down by the rotor shaft and the axis of the wind-energy-absorbing profile, comprising the quadrant lying between the sharp rear edge of the aerodynamic profile and the pressure side of the rotor blade. The term most effective position should be understood as meaning the position in which the most wind energy is absorbed by the profile. Such a position must be distinguished from, for example, the feathering position of a wind-energy-absorbing profile. The position of the rib as described above differs from the structures according to US 3,874,816, in which the rib is fitted in the downstream direction.
In the case of new structuress to be produced, the connection part and the member can be made as a unit from fibre reinforced resin. In the case of known structures, if the connection part comprises a circular tube, a strip of material extending from it can be fitted on it, for example by welding or gluing. According to the invention, the height of such a strip is preferably 0.05 - 0.3 times the (external) diameter or thickness of the connection part. More particularly, the height is approximately 0.1 times the diameter of the connection part.
It has been found that in such a way, particularly in the case of wind turbines with a capacity of more than 50 kW, the output can be increased by 1.5% or more. The costs of fitting such a rib arc many times lower than the additional output because such a simple change always pays. It should be pointed out that it is possible to provide existing blades with such a projecting rib, for example during an overhaul.
The rib can be designed in various ways, such as a flat strip, (partially) triangular profile, block profile, sailcloth and the like. Furthermore, the rib may be made flexible or otherwise, since it docs not form part of the strength-providing structures of the blade. Forces exerted upon the strip are transmitted to the blade or connection part.
Fig. 2 shows a cross section along the line II-II of Fig. 1,
Fig. 3 shows a variant of the structures according to Fig.1,
In Fig. 1 a blade of a wind turbine according to the invention is illustrated by 1. It is composed of a connection part 2. Connection to a hub 3, which forms part of a shaft 4 behind which the actual generator is connected, is possible by means of a flanged connection (not shown). At the other side, connection part 2 is connected to the wind-energy-absorbing profile 5 of the blade 1, In the embodiment shown, the profile is illustrated as a wing profile, and it will be understood that any other shape can be achieved. The axis of the blade is indicated by 7.
In the example shown here, the connection part 2 is of a circular design and comprises a simple tube. In the general prior an, this tube was of a smooth design, without any further measure being taken.
According to the invention, it is proposed that a member or rib 6 be fitted on the tube 2. It is also proposed that Vortex generators 8 be fitted in the position shown. The vortex generators (not drawn to scale) can be punched out of a strip material, the base material being fixed to the conncction part 2, for example by means of an adhesive layer. The vortex generators (not drawn to scale) extend perpendicular to the plane of the connection part 2, preferably at an angle of 15° relative to the plane perpendicular to the longitudinal axis 7. The angle can be either positive or negative. The member or the rib 6 according to the invention is shown in detail in Fig. 2. Its height is drawn slightly out of proportion. As a matter of fact, according to the invention it is preferable for said height to be h 0.05 - 0.3 of the diameter of the cylinder. In particular, said height will be approximately one tenth of the diameter.
With reference to Fig. 4, an example will be given below of a rib that extends spirally around the connection part. The 94-270° line corresponds to the rotor shaft. The coordinates system here is fixed relative to the blade axis and does not rotate with the blade twist. At 5% of the total length of the blade, the position of the rib is 158°. At 10% of the total length of the blade, the position is 122°, and at 30% of the length of the blade it is 103°.
It must be understood that this relates only to an example, and that considerable modifications are possible within the range hatched in Fig. 4. Deviations up to 34% relative to this preferred position are possible.
Blade (1, 11, 21, 31) of a wind turbine, comprising a connection part (2, 12, 22) provided at one end with connection means, for connection to the shaft (4)/hub (3, 13, 23) of a wind turbine, and a wind-energy-absorbing profile (5, 15, 25) which is optimized for the wind flow and extends from the other end of the connection part, the connection part being provided with a member (6, 16, 26, 36) that is designed in such a way that the assembly comprising the member (6, 16, 26, 36) and the connection part can absorb wind energy, which member comprises a rib (6, 16, 26, 36) that projects from the connection part, characterized in that said rib (6, 16, 26, 36) is arranged in a plane that forms an angle, which on the pressure side lies between 45° and 135° to the chordal plane of said wind-energy-absorbing profile.
Blade according to Claim 1, in which said angle lies between 45° and 135°.
Blade (1, 11, 21, 31) according to Claim 1, in which said rib is fitted in a plane that forms an angle of approximately 90° to the chordal plane of said wind-energy-absorbing profile.
Blade according to one of the preceding claims, in which said connection part comprises a substantially circular cross section.
Blade according to one of the preceding claims, in which said connection part comprises the transition from a circular to an aerodynamic profile.
Blade according to one of the preceding claims, in which the height (h) of the rib (6, 16, 26) lies between 0.05 and 0.3 times the diameter (d) or thickness of the connection part.
Blade according to one of the preceding claims, in which said connection part is provided with vortex-producing generators (8).
Blade according to one of the preceding claims, designed as a flexible part.
Method for producing a blade (1, 11, 21) of a wind turbine, comprising the provision of a blade (1, 11, 21) comprising a connection part (2, 12, 22) provided at one end with connection means, for connection to the shaft (4)/hub (3, 13, 23) of a wind turbine, and a wind-energy-absorbing profile (5, 15, 25) which is optimized for the wind flow and extends from the other end of the connection part, the connection part being provided with a member (6, 16, 26, 36) that is designed in such a way that the assembly comprising the member (6, 16, 26, 36) and the connection part can absorb wind energy, which member comprises a rib (6, 16, 26, 36) that projects from the connection part, wherein said rib (6, 16, 26, 36) is arranged in a plane that forms an angle, which on the pressure side lies between 45° and 135° to the chordal plane of said wind-energy-absorbing profile, wherein after the provision of the connection part a rib is provided on it in such a way that the assembly comprising the rib (6, 16m 26) and the connection part can generate wind energy.
EP20010948133 2000-06-28 2001-06-28 Blade of a wind turbine Revoked EP1295032B1 (en)
EP1295032A1 true EP1295032A1 (en) 2003-03-26
EP1295032B1 true EP1295032B1 (en) 2006-12-13
EP20010948133 Revoked EP1295032B1 (en) 2000-06-28 2001-06-28 Blade of a wind turbine
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2007-10-24 26 Opposition filed
2011-08-31 R26 Opposition filed (correction)
2015-07-08 R26 Opposition filed (correction)
2017-08-02 GBPR Gb: patent revoked under art. 102 of the ep convention designating the uk as contracting state
2017-08-02 27W Revoked