Title of Invention

A ROCTOR BLADE

Abstract A rotor blade The invention concerns a rotor blade and a wind power installation having a rotor blade provided with a rotor blade trailing edge, wherein the rotor blade tapers towards the rotor blade trailing edge. The invention is distinguished in that in the region of the rotor blade trailing edge, the degree of taper of the rotor blade increases in a direction towards the rotor blade trailing edge, and there is no stair-like step in the rotor blade at least in said region of use rotor
Full Text

The invention concerns a rotor blade and a wind power installation having a rotor blade, wherein the rotor blade is provided with a rotor blade trailing edge and tapers towards the rotor blade trailing edge.
Rotor blades for wind power installations are known in many different forms. Unfortunately many rotor blades in the state of the art suffer from the problem that in operation of the wind power installation and with wind strengths from about 5 to 6 m/second, they generate not Inconsiderable sound emissions, to a not Inconsiderable extent. The sound emissions which have occurred hitherto mean inter alia that wind power installations meet resistance on the part of wide classes of society and population, because of the amount of noise generated. As a consequence, wind power installations sometimes encounter difficulty in being accepted or are not accepted at all, as the authorities with responsibility for granting permission for setting up wind power installations refuse such permission because of the environmental considerations involved - noise also counts as environmental pollution. Therefore, for reasons of noise, particularly in the proximity of residential buildings, it is desirable to reduce the above-mentioned considerable levels of noise emission, in order to satisfy the statutory requirements and to Increase the acceptance of wind power installations.
Therefore the object of the present invention is to reduce the level of sound emissions of wind power Installations.
In accordance with the invention, with a rotor blade of the kind set forth 1n the opening part of this specification, that object is achieved in that in the region of the rotor blade trailing edge the degree of taper of the rotor blade Increases in a direction towards the rotor blade trailing edge, and there is no staip-like step in the rotor blade at least in that region of the rotor blade,
A particularly advantageous embodiment of the invention is distinguished in that the degree of taper of the rotor blade increases at given spacings in a di recti on towards the rotor blade trai1ing edge. In that respect, it is particularly preferable that bends in the cross-section of the trailing edge portion of the rotor blade, that is to say a portion adjacent to the rotor blade trailing edge, are formed at the respective spacings, and between said bends said portion of the rotor blade is substantially flat. Then, in this form of the invention, the planes which are disposed between the bends form very shallow angles relative to each other so that overall the assembly gives approximately the form of a convexly curved surface in respect of the cross-section of the trailing edge portion of the rotor blade.
In a further advantageous embodiment of the rotor blade according to the Invention, there are three bends each extending substantially parallel to the

rotor blade trailing edge. The embodiment represents an optimum compromise between the expenditure involved in production of the bends in the rotor blade, and a described marked reduction in the noise level of the rotor blade as it moves.
It is particularly preferred that the inclined planes which adjoin each other in the form of bends and which form the taper configuration for the rotor blade in a direction towards the rotor blade trailing edge are provided only on one side of the rotor blade. In that case it is advantageous if the bends are formed only on the suction or reduced pressure side of a rotor blade having a pressure side and a reduced-pressure side. That configuration provides for a particularly marked reduction in the level of sound emissions. In that case, it has proven to be desirable that the acute angles which the planes of the reduced-pressure side of the rotor blade, that are between the bends, form with the pressure side of the rotor blade, become increasingly more acute. In that respect, the reduction in the magnitude of the respective angles occurs from the trailing edge towards the leading of the rotor blade. The plane portion of the reduced-pressure side of the rotor blade, which is most closely adjacent to the rotor blade trailing edge, with the flat pressure side of the rotorblade.
Wind power installations provided with the rotor blade according to the invention overall exhibit a marked reduction in the noise level generated, by virtue of the reduced sound emission of the individual rotor blade. Accordingly, the wind power installation according to the invention represent a markedly reduced noise pollution aspect of the population.

Therefore, the wind power installation according to the invention considerably reduces the above discussed disadvantages of the wind power installations in the state of the art, the level of acceptance of wind power installations on the part of the people is increased and existing anti-noise requirements are more easily met.
Further advantageous embodiments of the invention are set forth in the appendant claims.
Accordingly the present invention provides a rotor blade having a rotor blade edge for a wind energy installation, the rotor blade tapering towards the rotor-blade rear edge, characterized in that, in the region of the rotor blade rear edge, the degree of taper of the rotor blade increases in the direction of the rotor- blade rear edge, in that the degree of taper increases at spacings (a,b,c) and remains constant between the points of the increase.
The invention is described in greater detail hereafter by means of an embodiment illustrated in the accompanying drawings in which; Fig. 1 is a view in cross-section through a rear portion, which is towards the rotor blade trailing edge, of an embodiment of the rotor blade according to the invention and
Fig. 2 shows a portion from Fig. 1.
Referring to Figure 1, shown therein is an embodiment of a rotor blade 1 according to the invention. Figure 1 shows only the rear part of the rotor blade 1, which is adjacent to a rotor blade trailing edge 2. The two sides of the rotor blade 1, a suction or reduced-pressure side 4 which is shown at the top in

Figure 1 and a pressure side 6 which 1s shown at the underneath in Figure 1, come together at the rotor blade trailing edge 2, The two sides of the rotor blade 1 meet at an acute angle a. The angle a is formed by a plane 8 which contains the substantially flat pressure side 6 of the rotor blade 1, and an inclined plane a. The plane a contains a portion 4a of the reduced-pressure side 4 of the rotor blade 1. the portion 4a being directly adjacent to the rotor blade trailing edge 2. The portion 4a which 1s of a substantially flat configuration therefore determines 1n a portion A the degree of taper of the rotor blade 1 towards the rotor blade trailing edge 2. A portion 4b of the reduced-pressure side 4 adjoins the portion 4a steplessly, that is to say without forming a stair-like step. The portion B is part of a plane b which forms an angle (I with the plane 8. The angle 3 is smaller than the angle a so that the portion 4b of the reduced-pressure side 4 includes, with the pressure side 6, a more acute angle than is the case between the portion 4a and the plane 8. Therefore, in the region 8 in Figure 1, the degree of taper of the rotor blade 1 is determined by the gradient of the portion 4b. The degree of taper in the region B of the portion 4b is smaller than in the region A of the portion 4a. Within each of the respective regions B and A respectively however, the degree of taper is almost constant as the portions 4b and 4a of the reduced-pressure side 4 dre. in themselves, substantially flat.
The portion 4b 1s then in turn followed in a direction towards the rotor blade leading edge (not shown) in a stepless configuration - in the above-defined sense - by the next portion 4c of the reduced-pressure side 4, the portion 4c also being in the form of ar inclined plane. The portion 4c is part of a plane c which forms an angle y with the plane 8. The angle Y is in turn smaller than the angie B. The region C of the rotor blade 1, the dimensions of which are determined by the length of the portion 4c of the reduced-pressure side 4, also has an almost constant degree of taper of the rotor blade 1. as the portion 4c and the pressure-side 6 disposed in opposite relationship in that region are also substantially flat.
After the portion 4c, as viewed from the rotor blade trailing edge 2, the portion 4c is again steplessly adjoined by a portion 4d. The foregoing descr1ption relating to the portions 4a to 4c also correspondingly applies to the portion 4d. Depending on the respective requirements made on the rotor blade 1, the above-described successive arrangement of inclined planes within the reduced-pressure side 4, which Include increasingly more acute angles with the pressure side 5, car be continued as desired. It should be emphasised in this respect that the drawing shows the actual configurations and relationships in greatly exaggerated form for the sake of enhanced clarity of the drawing.

Figure 2 shows a view on an enlarged scale of a part as Indicated at 10 in Figure 1, for further clarification. It will be particularly clear from Figure 2 that there is no change in leve" in the form of a step between the inclined plane 4a and the inclined plane 4b, but the portions 4a and 4b adjoin each other at a bend 12 in the reduced-pressure side 4. It will also be clear that the angle a between the portion 4a and the pressure side 6 is greater than the angle B which is Included between the portion 4b of the reduced-pressure side 4 and the pressure side 6.


WE CLAIM:
1. A rotor blade having a rotor blade edge (2) for a wind energy installation, the rotor blade tapering towards the rotor-blade rear edge, characterized in that, in the region of the rotor blade rear edge (2), the degree of taper of the rotor blade increases in the direction of the rotor- blade rear edge, in that the degree of taper increases at spacings (a,b,c) and remains constant between the points (12) of the increase.
2. The rotor blade as claimed in claim 1, wherein the degree of taper increases in the form of at least one bend (12) in the rotor blade (1).
3. The rotor blade as claimed in claim 1, wherein the bend(s) extend(s) substantially parallel to the rotor-blade rear edge (2).
4. The rotor blade as claimed in claims 2 & 3, wherein three bends (12) are provided.
5. The rotor blade as claimed in claims 2 to 4 , wherein the bend(s) (12) is/are provided on only one side (4, 6) of the rotor blade (1).
6. The rotor blade as claimed in claims 2 to 5, wherein the bend(s) (12) is/are provided only on the suction side (4).

7. The rotor blade as claimed in any one of the preceding claims, wherein one side (4, 6) of the rotor-blade rear edge portion (14) is substantially planar.
8. The rotor blade as claimed in any one of the preceding claims, wherein the substantially planar side(4, 6) of the rotor-blade rear edge portion (14) forms angles (a, p, y) with the other side(6, 4), angles becoming increasingly acute in the direction of the rotor-blade front edge, as seen from the rotor-blade rear edge (2).
9. A wind energy installation having a rotor, which has one or more rotor blades (1) according to one of the preceding claims.
10. A rotor blade, substantially as herein described with reference
to the accompanying drawings.


Documents:

2198-MAS-1998 AMENDED CLAIMS 20-09-2010.pdf

2198-mas-1998 abstract-duplicate.pdf

2198-mas-1998 abstract.pdf

2198-mas-1998 claims-duplicate.pdf

2198-mas-1998 claims.pdf

2198-mas-1998 correspondence-others.pdf

2198-mas-1998 correspondence-po.pdf

2198-mas-1998 description (complete)-duplicate.pdf

2198-mas-1998 description (complete).pdf

2198-mas-1998 drawings-duplicate.pdf

2198-mas-1998 drawings.pdf

2198-mas-1998 form-19.pdf

2198-mas-1998 form-2.pdf

2198-mas-1998 form-3.pdf

2198-mas-1998 form-4.pdf

2198-mas-1998 form-6.pdf

2198-mas-1998 petition.pdf


Patent Number 200280
Indian Patent Application Number 2198/MAS/1998
PG Journal Number 08/2007
Publication Date 23-Feb-2007
Grant Date 19-May-2006
Date of Filing 01-Oct-1998
Name of Patentee ALOYS WOBBEN
Applicant Address ARGESTRASSE 19, 26607 AURICH,
Inventors:
# Inventor's Name Inventor's Address
1 ALOYS WOBBEN NEARGESTRASSE 19, 26607 AURICH
PCT International Classification Number F03D11/02
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 197 43 694.3 1997-10-02 Germany