Root bushing for a blade root of a wind turbine rotor blade, a blade root, a wind turbine rotor blade and a wind turbine

Abstract

A root bushing for a blade root of a wind turbine rotor blade, including a cylindrical bushing body and a flat contact body is provided. The contact body is provided on a face of the bushing body. This has the advantage that due to the provision of the contact body, the contact area between the root bushing and the pitch bearing is increased. In another embodiment, the root bushing includes a central bore which protrudes through the bushing body and the contact body. In another embodiment, an outer wall of the bushing body is provided with a connection structure for connecting the root bushing to a composite material of the wind turbine rotor blade.

Claims

1. A root bushing for a blade root of a wind turbine rotor blade, comprising a cylindrical bushing body, and a flat contact body comprising a rectangular shape, wherein the contact body is provided on a face of the bushing body, wherein a cross-sectional area of the contact body is bigger than a cross-sectional area of the bushing body, wherein the bushing body has a first face and a second face, wherein the contact body is provided at the first face, and wherein the second face comprises a taper that reduces a cross section of the bushing body with increased distance from the first face, wherein an outer wall of the bushing body comprises notches configured to connect the root bushing to a composite material of the wind turbine rotor blade, and wherein the notches end prior to the second face and prior to the taper.

2. The root bushing according to claim 1, wherein the bushing body comprises a rectangular cross section.

3. The root bushing according to claim 1, wherein the root bushing comprises a central bore which protrudes through the bushing body and the contact body.

4. The root bushing according to claim 3, wherein the central bore comprises a thread.

5. The root bushing according to claim 1, wherein the bushing body is arranged perpendicular to the contact body.

6. The root bushing according to claim 1, wherein the bushing body and the contact body are made of one piece.

7. The root bushing according to claim 1, wherein the root bushing is made of a metal alloy.

8. A blade root of a wind turbine rotor blade, comprising a root bushing according to claim 1.

9. A wind turbine rotor blade comprising a blade root according to claim 8.

10. A wind turbine comprising a blade root according to claim 8.

11. A wind turbine rotor blade comprising a root bushing according to claim 1.

12. A wind turbine comprising a wind turbine rotor blade according to claim 11.

13. A wind turbine comprising a root bushing according to claim 1.

14. The root bushing according to claim 1, wherein the notches surround the bushing body completely.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further embodiments, features and advantages of the present invention will become apparent from the subsequent description and dependent claims, taken in conjunction with the accompanying drawings, in which:

(2) FIG. 1 is a perspective view of a wind turbine according to one embodiment;

(3) FIG. 2 is a perspective view of a wind turbine rotor blade according to one embodiment;

(4) FIG. 3 is an end view of the wind turbine rotor blade according to FIG. 2;

(5) FIG. 4 is a perspective view of a root bushing according to one embodiment;

(6) FIG. 5 is another perspective view of the root bushing according to FIG. 4;

(7) FIG. 6 is a cross-sectional view of the root bushing according to FIG. 4; and

(8) FIG. 7 is a cross-sectional view of a pitch bearing according to one embodiment.

DETAILED DESCRIPTION OF INVENTION

(9) In the Figures, like reference numerals designate like or functionally equivalent elements, unless otherwise indicated.

(10) FIG. 1 shows a wind turbine 1 according to an embodiment.

(11) The wind turbine 1 includes a rotor 2 connected to a generator (not shown) arranged inside a nacelle 3. The nacelle 3 is arranged at the upper end of a tower 4 of the wind turbine 1.

(12) The rotor 2 includes three blades 5. The blades 5 are connected to a hub 6 of the wind turbine 1. Rotors 2 of this kind may have diameters ranging from, for example, 30 to 160 meters. The blades 5 are subjected to high wind loads. At the same time, the blades 5 need to be lightweight. For these reasons, blades 5 in modern wind turbines 1 are manufactured from fiber-reinforced composite materials. Therein, glass fibers are generally preferred over carbon fibers for cost reasons. Oftentimes, glass fibers in the form of unidirectional fiber mats are used.

(13) FIG. 2 shows a blade 5 according to one embodiment.

(14) The blade 5 includes an aerodynamically designed portion 7, which is shaped for optimum exploitation of the wind energy and a blade root 8 for connecting the blade 5 to the hub 6. The blade 5 may be fixed to the hub 6 by means of bolts.

(15) FIG. 3 shows an end view of the blade root 8.

(16) The blade root 8 includes a plurality of root bushings 9 for a releasable connection of the blade 5 to the hub 6. The root bushings 9 are embedded in the blade root 8 so that bolts (not shown) can be screwed into an internal thread of the root bushings 9 for a firm but releasable engagement therewith. The number of root bushings 9 is arbitrarily. In FIG. 3 only three root bushings 9 are shown.

(17) FIGS. 4 and 5 are perspective views of a root bushing 9. FIG. 6 is a longitudinal section of a root bushing 9.

(18) In the following, FIGS. 4 to 6 are referred to at the same time. The root bushing 9 includes a bushing body 10. The bushing body 10 includes a basic portion 11 and an extension portion 12. The basic portion 11 is cylindrical or tube shaped. The basic portion 11 preferably has a half square half circular or rectangular cross-section. The extension portion 12 is slanted and has a gradually reduced cross-section to a pointed or nearly pointed end 13. Thus, the extension portion 12 has a gradually increased flexibility. Preferably, the basic portion 11 and the extension portion 12 are made of one piece.

(19) The bushing body 10 has a half square half circular or a rectangular cross-section with a central bore 14. The central bore 14 includes a thread 15 for connecting the bushing body 10 to the hub 6 by means of a bolt (not shown). The bushing body 10 has two faces 16, 17. The face 16 is a first or distal face 16 of the bushing body 10 and the face 17 is a second or proximal face 17 of the bushing body 10. The second face 17 is tapered and pointed to the end 13.

(20) The root bushing 9 further includes a contact body 18. The contact body 18 provides an interface between a pitch bearing (not shown) of the hub 6 and the root bushing 9. The contact body 18 is provided on the face 16 of the bushing body 10. In particular, the contact body 18 is connected to the front face 16. The central bore 14 protrudes through the contact body 18 and the bushing body 10. The bushing body 10 and the contact body 18 are made of one piece.

(21) The contact body 18 is flat or even and has a ring-segment shape. Alternatively, the contact body 18 may have a trapezoidal or even a rectangular cross-section, wherein a cross-sectional area of the contact body 18 is bigger than a cross-sectional area of the bushing body 10. The bushing body 10 is arranged perpendicular to the contact body 18. For simplification, in FIGS. 4 to 6 the contact body 18 is shown with a rectangular shape.

(22) An outer wall 19 of the root bushing body 10 is provided with a connection structure 20 for connecting the root bushing 9 to a composite material of the wind turbine blade 5. The connection structure 20 has a plurality of notches 21 that are arranged on a circumference of the bushing body 10. The connection structure 20 increases a surface of the outer wall 19. A foam core 22 can be placed in the bushing body 10, in particular in the central bore 14. Due to the connection structure 20, the connection between the root bushing 9 and the composite material is improved.

(23) FIG. 7 shows a sectional view of a pitch bearing 23 of the hub 6.

(24) The contact body 18 has a face 24 which directly contacts a face 25 of the pitch bearing 23. Due to the fact that the contact body 18 has a bigger cross-sectional area than the bushing body 10, a contact area 26 which is framed with dotted lines for a better understanding is increased in comparison to known root bushings. In FIG. 7 the root bushing 9 is shown with an offset from the pitch bearing 23. Normally, the contact body 18 is firmly pressed against the pitch bearing 23. The contact area 26 has a ring-segment shape.

(25) The root bushing 9 also provides an increased bending stiffness since the cross-section of the contact body 18 is wider and higher than that of the root bushing body 10. Since the contact area 26 is enlarged, an easier positioning of the root bushing 9 relatively to the pitch bearing 23 is ensured. The increased contact area 26 increases connection stiffness and bending stiffness of the assembly which both increase fatigue life of the connecting bolt.

(26) Although the present invention has been described in accordance with preferred embodiments, it is obvious for the person skilled in the art that modifications are possible in all embodiments.

REFERENCE NUMERALS

(27) 1 wind turbine 2 rotor 3 nacelle 4 tower 5 blade 6 hub 7 portion 8 blade root 9 root bushing 10 bushing body 11 basic portion 12 extension portion 13 end 14 bore 15 thread 16 face 17 face 18 contact body 19 wall 20 connection structure 21 notch 22 foam core 23 pitch bearing 24 face 25 face 26 contact area.