Wind turbine blade connector assembly

Abstract

It comprises bushings in at least a first circumferential row in a blade portion and suitable for receiving studs in a hub portion. Bushings comprise an elongated body with lateral faces, lateral faces inclined to each other and major and minor faces into which the lateral faces converge. The connector assembly allows an efficient releasable connection of blade root and hub in a wind turbine rotor.

Claims

1. A wind turbine blade connector assembly for connecting a blade portion to a hub portion in a wind turbine rotor, the connector assembly comprising: a plurality of bushings arranged in a first row and in a second row along a circumference of one of the blade portion or the hub portion and suitable for receiving corresponding studs, wherein the bushings comprise an elongated body having major and minor faces and two lateral faces, the lateral faces extending at least partially into one of the blade portion or the hub portion, and the lateral faces being inclined to each other and converging into the respective major and minor faces, the bushings in the first row arranged upside-down relative to the bushings in the second row and between the bushings in the second row such that the major faces of the bushings in the first row alternate with the minor faces of the bushings in the second row; the body of each bushing configured for receipt of a triangular pattern of three studs, wherein a first stud is adjacent the minor face and second and third studs are spaced apart and adjacent the major face; and wherein the plurality of bushings thereby provide an outer ring of the studs and a concentric inner ring of the studs interspaced between the outer ring of studs.

2. The connector assembly of claim 1, wherein the body of at least some of the bushings has a substantially trapezoidal shaped cross-section.

3. The connector assembly of claim 1, wherein the body of at least some of the bushings has rounded edges.

4. The connector assembly of claim 3, wherein the body of at least some of the bushings is bell shaped.

5. The connector assembly of claim 1, wherein a cross-section of the body of at least some of the bushings is symmetrical about an axis passing through a centre of the blade portion corresponding to the plane containing the cross-section.

6. The connector assembly of claim 1, wherein at least one of the major and minor faces of the body of at least some of the bushings tapers towards one end of the bushing.

7. The connector assembly of claim 1, wherein the body of the bushings are configured for threadably receiving the studs.

8. A wind turbine comprising a rotor including a blade and a hub, the blade and the hub being connected to each other by means of the blade connector assembly of claim 1.

9. A method for connecting a blade portion to a hub portion in a wind turbine rotor, the method comprising at least the following steps: providing a first layer of fibre materials in a mould; providing a first row of bushings on the first layer of fibre materials along a circumference, the bushings comprising an elongated body having major and minor faces and two lateral faces and configured for receipt of three studs in a triangular pattern wherein a first stud is adjacent the minor face and second and third studs are spaced apart and adjacent the major face, the lateral faces inclined to each other and converging into the respective major and minor faces; providing a second layer of fibre materials over the first row of bushings; providing a second row of the bushings on the second layer of fibre materials arranged upside-down relative to and between the first row of bushings row such that the major faces of the bushings in the first row alternate with the minor faces of the bushings in the second row; providing a third layer of fibre materials over the second row of bushings; heating the mould during a given period of time; cooling the mould during a given period of time; and wherein the plurality of bushings thereby provide an outer ring of the studs and a concentric inner ring of the studs interspaced between the outer ring of studs.

10. The method of claim 9, wherein the fibre materials are pre-impregnated fibre materials.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Particular embodiments will be described in the following by way of non-limiting examples, with reference to the appended drawings, in which:

(2) FIG. 1 is a perspective view of one bushing that is part of a first embodiment of a blade connector assembly;

(3) FIG. 2 is a perspective view of a partial ring structure formed of a series of bushings corresponding to a second embodiment of a blade connector assembly;

(4) FIG. 3 is a perspective view of a partial ring structure formed of a series of bushings corresponding to a third embodiment of a blade connector assembly;

(5) FIG. 4 is a perspective view of a partial ring structure of bushings corresponding to a fourth embodiment of a blade connector assembly;

(6) FIG. 5 is a front elevational view of one bushing of the embodiment of the blade connector assembly in FIG. 3;

(7) FIG. 6 is a front elevational view from a blade root side in which two ring structures of bushings are shown;

(8) FIG. 7 is a side elevational view of a blade root; and

(9) FIG. 8 is a longitudinal sectional view of one bushing according to the embodiment of the blade connector assembly in FIG. 3 taken along line AA′ in FIG. 7.

DETAILED DESCRIPTION OF EMBODIMENTS

(10) The figures enclosed herein show four possible embodiments of the present blade connector assembly. Like reference numerals refer to like elements throughout the following description.

(11) The blade connector assembly has been designated by reference numeral 100 in the drawings. The present blade connector assembly 100 is part of a wind turbine rotor. A typical wind turbine rotor includes a blade 105 (shown in general in FIG. 7) and a hub (not shown in the figures). The blade 105 and the hub can be releasably connected to each other through respective blade and hub portions by means of the present blade connector assembly 100 which will be disclosed fully below.

(12) In general, the blade and hub portions may be any suitable portions thereof for proper releasable connection. In the examples shown in the drawings, the blade portion is the blade root 110 and the hub portion is a portion in the outer end surface of the rotor hub. The blade root 110 may comprise a flange portion 115 as shown in FIGS. 7 and 8. Although not shown, the hub portion comprises a corresponding flange portion. Both flange portions form the interface of the blade—hub connection.

(13) The blade connector assembly 100 comprises a number of bushings or inserts 200. As shown in the figures, the bushings 200 are elongated metal pieces. The bushings 200 are sized and shaped for receiving corresponding bolts or studs 300. Studs 300 are in turn attached to the hub portion. Two studs 300 are visible in FIG. 8.

(14) As shown in the embodiments of FIGS. 2 and 3, the bushings 200 of the blade connector assembly 100 are arranged in one row or ring structure R1. The ring structure R1 may be a single structure or it may comprise a number of ring segments each having a number of bushings 200 that, when placed to one another, form a complete ring structure R1. FIGS. 2 and 3 diagrammatically show part of such a ring structure R1, that is, a ring segment.

(15) As shown in FIG. 1, the elongated body of bushing 200 comprise two lateral faces 200a, 200b extending into the blade portion 110. As best shown in FIG. 8, each bushing 200 extends from the flange portion 115 into the blade root 110. The lateral faces 200a, 200b of bushings 200 are substantially inclined to each other and they converge into respective major and minor faces 200c, 200d as it can be clearly seen in FIG. 5.

(16) The above configuration results in trapezoidal prism shaped bushings 200 as shown in FIGS. 1-5, that is, a prism having a substantially trapezoidal shaped cross section (see again FIG. 5 of the drawings). In general, the cross-section of the body of the bushings 200 is substantially symmetrical about an axis y passing through the centre C of the blade portion 110 corresponding to the plane P containing the cross-section of the bushing 200.

(17) Although several triangle-like shapes are possible, the most preferred embodiment as shown in FIG. 5 is the one in which the cross-section of the bushing 200 is shaped in the form of an equilateral triangle. This results in that the bushings 200 are arranged along the circumference of the blade root 110 in two bolt circles R1, R2 as it will explained further below. In this arrangement, the bushings 200 are placed to each other such that the corresponding confronting faces of adjacent bushings 200 are substantially parallel to each other. Other arrangements are of course possible, such as the one on which the bushings 200 are shaped in cross-section in a form other than an equilateral triangle such that they become arranged with the corresponding confronting faces of adjacent bushings 200 not parallel to each other as shown in FIG. 6.

(18) In the particular embodiment shown in FIGS. 1 and 8, the elongated body of the bushing 200 tapers towards one end of the blade root 110. As specifically shown in FIG. 5, the trapezoidal body of the bushing 200 has rounded edges for the purposes of reducing stress concentrations.

(19) The bushings 200 are provided with stud receiving holes 250. In the embodiments of FIGS. 1 and 2, the bushings 200 are each provided with one stud receiving hole 250, while in the embodiments of FIGS. 3-8, the bushings 200 are each provided with three stud receiving holes 250.

(20) Holes 250 formed in the body of the bushings 200 have inner threads for threadably receiving the corresponding bolts or studs 300. To this effect, studs 300 are provided with corresponding threaded portions 310 as shown in FIG. 7.

(21) In the embodiment in which several stud receiving holes 250 are provided, e.g. three, said holes 250 can be arranged very close to each other as shown in the cross-sectional view of FIG. 5. The distance d between the centres of each stud receiving holes 250 is significantly reduced due to the triangular shaped cross section of the body of the bushing 200. The small value of distance d allows the bushings 200 to be compact in size that is, with a reduced height h, i.e. having a short distance between major and minor faces 200c, 200d.

(22) A further embodiment of the present blade connector assembly 100 is shown in FIG. 4. In this embodiment, the bushings 200 of the blade connector assembly 100 are arranged in two rows or ring structures R1, R2 along the circumference of the flange portion 115 in the blade root 110.

(23) The provision of ring structures R1, R2 results in two bolt circles being provided having different diameters. As illustrated in FIG. 4, the bushings 200 of one ring structure R1 may have complementary shapes to those of the other ring structure R2, that is, the bushings 200 of one ring structure R1 are arranged upside-down relative to the bushings 200 of the other ring structure R2 and fitted ones between others as shown in FIG. 4. As stated above, rings R1, R2 may each be formed of a single structure or they may comprise a number of segments each having a number of bushings 200 defining complete ring structures R1, R2.

(24) In the arrangement shown in FIG. 4, the bushings 200 in different rows R1, R2 define a space between which fibre material such as prepreg fibres 400 is arranged. The prepreg fibres 400 allow an easier positioning of bushings 200 due to lower changes in bushing thickness during blade connection manufacturing process.

(25) The blade—hub connection can be carried out by providing a first layer of prepreg fibres 400 into a mould and then placing a first row R1 of bushings 200 thereon according to required positions. A second layer of prepreg fibres 400 is then placed such as shown in FIG. 4 of the drawings. A second row R2 of bushings 200 are subsequently placed on the second layer of prepreg fibres 400 such that shapes of bushings 200 in different rows R1, R2 are complimentary and defining said space between the rows R1, R2 of bushings 200 for the fibres 400. Finally, a third layer of prepreg fibres 400 is provided on the second row R2 of bushings 200. The mould and therefore the resulting structure are heated up during a given period of time. The mould and therefore the resulting structure is thereafter cooled down during a given period of time.

(26) Although only a number of particular embodiments and examples of the present connector assembly have been disclosed herein, it will be understood by those skilled in the art that other alternative embodiments and/or uses and obvious modifications and equivalents thereof are possible. Furthermore, the present disclosure covers all possible combinations of the particular embodiments described.

(27) Reference signs related to drawings and placed in parentheses in a claim, are solely for attempting to increase the intelligibility of the claim, and shall not be construed as limiting the scope of the claim. Thus, the scope of the present disclosure should not be limited by particular embodiments, but should be determined only by a fair reading of the claims that follow.