Abstract
Provided is a rotor blade for a wind turbine, with a trailing edge including a trailing edge core having several core elements arranged side by side, and with an inner and an outer laminate, wherein one core element is split into two element parts separated by a slit, whereby, seen in the direction from a blade root to a blade tip, the inner laminate runs into and through the slit and becomes the outer laminate.
Claims
1. A rotor blade for a wind turbine, with a trailing edge comprising a trailing edge core having several core elements arranged side by side, and with an inner and an outer laminate, wherein one core element is split into two element parts separated by a slit, whereby, seen in a direction from a blade root to a blade tip, the inner laminate runs into and through the slit and becomes the outer laminate.
2. The rotor blade according to claim 1, wherein the slit extends oblique to the longitudinal axis of the split core element.
3. The rotor blade according to claim 2, wherein the slit starts at or close to one end surface and extends to or close to the other end surface.
4. The rotor blade according to claim 1, wherein the split core element has a length of between one of 0.5 to 2 m, and 1 to 1.5 m.
5. The rotor blade according to claim 1, wherein the slit is curved.
6. The rotor blade according to claim 1, wherein the opposing surfaces of the two element parts correspond to each other in a form-fit manner.
7. The rotor blade according to claim 1, wherein the core elements are made of a polymer or wood.
8. The rotor blade according to claim 7, wherein the polymer is polyurethane.
9. A wind turbine, comprising a rotor with one or more rotor blades according to claim 1.
10. A rotor blade for a wind turbine, comprising: a trailing edge including a trailing edge core having a plurality of core elements, and an inner and an outer laminate, wherein the plurality of core elements includes a split core element having two element parts separated by a slit extending oblique to a longitudinal axis of the split core element, and wherein the inner laminate runs into and through the slit and becomes the outer laminate.
11. The rotor blade according to claim 10, wherein the slit is curved.
12. A rotor blade for a wind turbine, comprising: a trailing edge including a trailing edge core having a plurality of core elements, and an inner and an outer laminate, wherein the plurality of core elements includes a split core element having two element parts separated by a curved slit, and wherein the inner laminate runs into and through the curved slit and becomes the outer laminate.
13. The rotor blade according to claim 12, wherein the curved slit extends oblique to a longitudinal axis of the split core element.
Description
BRIEF DESCRIPTION
(1) Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:
(2) FIG. 1 is a principle sketch of an inventive rotor blade;
(3) FIG. 2 is a principle sketch of a partial cross section of the rotor blade of FIG. 1 taken along the line II-II;
(4) FIG. 3 is a principle sketch of a partial cross section of the blade of FIG. 1 taken along the line III-IIII;
(5) FIG. 4 is a principle sketch of a part of the rotor blade, seen from the inside of the blade, showing a part of the trailing edge core assembly with a split core element;
(6) FIG. 5 is a perspective exploded view of the split core element with its two element parts;
(7) FIG. 6 is a perspective view of the split core element of FIG. 5 with the element part attached to each other;
(8) FIG. 7 is a principle sketch of a cross section of the split core element with the laminate inserted in the slit taken along the line VII-VII of FIG. 6;
(9) FIG. 8 is a principle sketch of a cross-section taken along the lines VIII-VIII in FIG. 7;
(10) FIG. 9 is a principle sketch of a cross-section taken along the lines IX-IX in FIG. 7;
(11) FIG. 10 is a principle sketch of a cross-section taken along the lines X-X in FIG. 7;
(12) FIG. 11 is a principle sketch of a cross-section taken along the lines XI-XI in FIG. 7;
(13) FIG. 12 is a principle sketch of a cross-section taken along the lines XII-XII in FIG. 7; and
(14) FIG. 13 shows a principle sketch of an inventive wind turbine comprising three inventive rotor blades.
DETAILED DESCRIPTION
(15) FIG. 1 shows an inventive rotor blade 1, made as an integral one-piece blade. It comprises a root 2 having a cylindrical cross section. The blade 1 is attached to the hub at this root 2.
(16) In a widely known manner the blade 1, starting close to the root 2, widens and changes its cross section towards the tip 3, from a larger hollow structure in the section closer to the root 2 to a very flat air foil structure at the tip 3.
(17) Furthermore, the rotor blade 1 comprises a leading edge 4 and a trailing edge 5 which roughly changes its design due to mechanical and aerodynamic reasons, as also commonly known.
(18) For defining the respective trailing edge design, a trailing edge core 6 having several core elements 7, which are arranged side by side, seen from the root 2 to the tip 3, is inserted respectively laminated and infused in the one-piece rotor blade 1. These core elements 7 are made of a polymer, especially polyurethane. As already shown in FIG. 1, one of the core elements 7, here the core element 7a, is a split core element comprising two separate elements parts 8a, 8b, which are separated by a slit 9. This split core element 7a provides a transition region for transferring an inner laminate arranged at the inner side of the hollow blade 1 to becoming an outer laminate arranged at the outside of the blade 1.
(19) FIG. 2 shows a partial cross section of the rotor blade 1 at the trailing edge 5 taken along the line II-II. It shows one core element 7 defining the trailing edge 5 respectively the edge geometry. At the inside of the core element 7, which is curved at its inside, a laminate 10 being made of several layers of fiber mats, such as glass fiber mats, is arranged. The construction is then infused with a resin infusing the laminate 10 and the core element 7, which parts are firmly integrated respectively define the blade structure.
(20) FIG. 3 shows another principle sketch of a cross section at the trailing edge 5 taken along the line III-III of the rotor blade 1. While the cross section of FIG. 2 is taken, seen from the root 2, in a region in front of the split core element 7a, the cross section of FIG. 3 is taken in a region behind the split core element 7a. As is clearly shown in FIG. 3, the cross-section geometry has rapidly changed from the flat back geometry shown in FIG. 2 to an air foil geometry shown in FIG. 3. The core element 7 is very flat and small, compared to the core element 7 of FIG. 2. The laminate 10, which is now an outer laminate, is now arranged at the outside of the core element 7 respectively the blade. The transition from the laminate 10 being an inner laminate as shown in FIG. 2 to be an outer laminate as shown in FIG. 3 is realised without any discontinuity by means of the split core element 7a, as will now be described.
(21) FIG. 4 shows as a partial principle sketch the rotor blade 1 from the inside of the hollow blade structure. The blade extends to the left towards the root 2, as shown by the arrow pointing to the left and by the reference sign 2 for the root 2, and extends to the right towards the tip 3, as shown by the arrow pointing to the right and the reference number 3.
(22) The figure shows the trailing edge core 6 with the respective core elements 7 and the inventive split core element 7a, which core elements 7, 7a are arranged side by side. In the area to the left of the split core element 7a, the laminate 10 is arranged at the inside, i.e. at the surface shown in FIG. 4, while the laminate 10 is arranged at the outside of the blade in the region to the right of the split core element 7a.
(23) The split core element 7a itself is shown in detail in the FIGS. 5 and 6. As already mentioned, the split core element 7a comprises two separate element parts 8a, 8b, which are separate from each other by means of a slit 9, when being installed in the blade 1. The slit 9 extends from close to one end surface 11 of the split core element 7a to the other end surface 12 and ends close to this end surface. It runs oblique to the longitudinal axis of the core element and is curved, i.e. the opposing surfaces 13, 14 of the element parts 8a, 8b are both curved and, from their geometry, correspond to each other, so that they are form-fitted to each other, as shown in FIG. 6. This ascertains that the laminate introduced into the slit and the resin matrix has the same thickness throughout the whole slit length and height.
(24) The laminate 10 inserted into the slit 9 is shown in principle by the dashed line in FIG. 6. As is clearly shown, it transfers from the inner side to the outer side when it extends through the slit 9, seen in the longitudinal direction.
(25) The slit core element 7a has a length of 0.5-2 m, especially of 1-1.5 m, thus also the slit has a comparable length.
(26) FIG. 7 shows a principle sketch of a cross section taken along the line VII-VII of FIG. 6. It shows the split core element 7a with the element parts 8a, 8b and with the laminate 10 inserted into the slit 9. As can clearly be seen, a smooth and continuous transfer or transition of the laminate 10 from the inner side to the outer side can be realised. The laminate 10 is shown by means of several layers of fiber mats 18, such as glass fiber mats, with the whole arrangement being infused with a resin during the mould process, as commonly known.
(27) Again, the direction to the left runs towards the root 2, while the direction to the right runs to the tip 3, as shown by means of the respective arrows pointing to the left and right and being marked with the reference numbers 2 and 3.
(28) The FIGS. 8-12 show respective cross sections taken along the lines VIII-VIII to XII-XII as marked in FIG. 7. The cross section according to FIG. 8, being closer to the root than the cross section of FIG. 12 being closer to the tip, shows the split core element 7a, while the cross section is taken at a position, into which the slit 9 does not extend, see FIG. 7. The laminate 10 is an inner laminate 10a and is arranged at the inside of the blade respectively the core element 7a.
(29) The cross section according to FIG. 9 is taken in a position, where the split core element 7a is already split respectively into which the slit 9 extends. As can clearly be seen, the laminate 10 is arranged in the slit and sandwiched between the element parts 8a, 8b.
(30) The cross section according to FIG. 10 is taken closer to the longitudinal middle of the split core element 7a. The geometry of the respective element parts 8a, 8b has changed due to the slit 9 running through the split core element 7a oblique to its longitudinal direction. Still the laminate 10 is in the slit 9 and sandwiched between both element parts 8a, 8b.
(31) FIG. 11 shows a cross section, which is taken closer to the tip side end of the split core element 7a. Again, the geometry of the element parts 8a, 8b has changed, the laminate 10 is still inserted in the slit 9.
(32) Finally, the cross section according to FIG. 12 is taken in an end area, into which, comparable to FIG. 8, the slit 9 does not extend. As is shown, the split core element 7a is in this part solely made by the element part 8b. The laminate 10 is now completely at the outside of the split core element 7a respectively the blade 1 and is an outer laminate 10b.
(33) As shown by the FIGS. 7-12, the integration of the inventive split core element into the trailing edge core allows for a smooth transfer of the inner laminate 10a arranged at the inside to become the outer laminate 10b arranged at the outside without any mechanical discontinuity. This ascertains that higher loads, as shown by the arrows F in FIG. 7, can be taken also in this transition region. Thus the mechanical stability can also be maintained in the region running to the tip, where in the conventional art, due to the layer-by-layer-transfer by ramping the respective layers up and down and overlapping them seen from the inside to the outside, a mechanical discontinuity is given being negative for the overall mechanical properties of the blade.
(34) Finally, FIG. 13 shows an inventive wind turbine 15 comprising a rotor 16 having three inventive rotor blades 1 attached to a hub 17.
(35) Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.
(36) For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.
