Wind turbine

Abstract

A wind turbine comprising a chassis having a cylindrical frame connection flange and a shaft having a cylindrical shaft connection flange wherein the shaft connection flange is secured to the frame connection flange by a threaded connection wherein the frame connection flange is provided with a first row of first through-holes arranged at an outer first frame radius and a second row of first through-holes arranged at an outer second frame radius. The shaft connection flange is provided with a first row of first threaded blind holes arranged at an outer first shaft radius, the frame connection flange is provided with a second row of second threaded blind holes arranged at an intermediate second frame radius, and the shaft connection flange is provided with a second row of second through holes arranged at an intermediate second shaft radius, the frame connection flange is provided with a third row of third threaded blind holes arranged at an inner third frame radius, and the shaft connection flange is provided with a third row of third through holes arranged at an inner third shaft radius, where the through holes are flush with the threaded holes, and the threaded connections extend through the through holes and are screwed into the threaded blind holes.

Description

Technical Field

[0001] The present invention relates to a wind turbine comprising a hollow base frame having a cylindrical frame connection flange with a frame front surface and a hollow shaft having a cylindrical shaft connection flange with a shaft front surface, wherein the shaft connection flange is fixed to the frame connection flange by a threaded connection, the threaded connection being arranged in axially extending holes provided in the frame connection flange and the shaft connection flange. Background Art

[0002] Modern wind turbines typically include a direct-drive generator, typically consisting of an outer rotor and an inner stator. The rotor is coupled to a hub containing multiple rotor blades that interact with the blowing wind. As is generally known, the rotating hub drives the rotor, which rotates around the stator, thereby generating electricity. The wind turbine comprises a stationary hollow shaft that carries the stator and rotor, which is mounted in corresponding bearings, allowing the rotor to rotate about the shaft and stator. The hollow shaft is connected to a stationary base frame, which is mounted atop the tower and can rotate about the tower's longitudinal axis, allowing the entire drive train to be adjusted in position. The hollow base frame has a cylindrical frame connection flange with a front face of the frame. Furthermore, the hollow shaft has a cylindrical shaft connection flange with a front face of the shaft. The base frame and hollow shaft are secured to each other via suitable threaded connections, which are arranged in axially extending holes provided in the corresponding frame and shaft connection flanges. These holes are arranged in various rows, some extending 360° around the respective flanges, while others do not. These holes include through-holes in one flange and corresponding threaded blind holes in the other flange, with screws or bolts extending through the through-holes and screwed into the threaded blind holes. Furthermore, these holes include corresponding through-holes in both flanges, with bolts extending through both through-holes and secured with corresponding nuts screwed onto the ends of both flanges. This requires extensive machining, particularly on the chassis side, where up to four separate rows of different holes must be drilled. Furthermore, placing the screws and bolts is quite cumbersome, especially on the chassis side. The screws must be inserted into a row of through-holes and then screwed into the threaded blind holes of the shaft flanges. Furthermore, tightening the bolts extending through the two through-holes of the flanges from the chassis side is quite cumbersome, requiring the nuts to be tightened from the inside of the chassis, where space is sometimes limited. Summary of the Invention

[0003] It is therefore an object of the present invention to provide a wind turbine having an improved flange connection between the chassis and the shaft.

[0004] To achieve this object, the wind turbine as described above is characterized in that

[0005] the frame connection flange is provided with a first row of first through holes extending from the frame front surface to an opposite face of the frame connection flange and arranged at an outer first frame radius, and the shaft connection flange is provided with a first row of first threaded blind holes extending from the shaft front surface into the shaft connection flange and arranged at an outer first shaft radius corresponding to the outer first frame radius,

[0006] the frame connection flange is provided with a second row of second threaded blind holes extending from the frame front surface into the frame connection flange and arranged at an intermediate second frame radius, and the shaft connection flange is provided with a second row of second through holes extending from the shaft front surface to an opposite face of the shaft connection flange and arranged at an intermediate second shaft radius corresponding to the intermediate second frame radius,

[0007] the frame connection flange is provided with a third row of third threaded blind holes extending from the frame front surface into the frame connection flange and arranged at an inner third frame radius, and the shaft connection flange is provided with a third row of third through holes extending from the shaft front surface to the opposite face of the shaft connection flange and arranged at an inner third shaft radius corresponding to the inner third frame radius,

[0008] wherein the through hole is flush with the threaded hole and the screw connection extends through the through hole and is screwed into the threaded blind hole.

[0009] The wind turbine of the present invention features an improved flange connection between the chassis and the shaft. This flange connection comprises only three rows of holes, provided in both the frame-connecting flange and the shaft-connecting flange. Each threaded connection comprises two corresponding holes (i.e., a through-hole and a threaded blind hole) and a screw extending through the through-hole and threaded into the threaded blind hole. Flush through-holes are not provided for receiving bolts, requiring the bolts to be tightened from both sides using nuts.

[0010] The three rows include a first row, a second row, and a third row. The first row includes a first through-hole in the frame connection flange and a first threaded blind hole in the shaft connection flange, the first through-hole extending from the front surface of the frame to the opposite surface of the frame connection flange, and a first threaded blind hole extending from the front surface of the shaft into the shaft connection flange. These two holes are of course arranged at the same radius, which is the outer first radius, so that the first through-hole of the frame connection flange is arranged at the outer first frame radius, and the first threaded blind hole of the shaft connection flange is arranged at the outer first shaft radius, which corresponds to the outer first frame radius. These combinations of through-holes and threaded blind holes constitute the first row. In this row, the connecting screws are inserted from the chassis side through the through-holes in the frame connection flange and screwed into the threaded blind holes in the shaft connection flange.

[0011] The second row includes a second threaded blind hole in the frame connection flange, extending from the frame front surface into the frame connection flange. The second threaded blind hole is arranged at the middle second frame radius. The second row also includes a second through hole in the shaft connection flange, extending from the shaft front surface to the opposite side of the shaft connection flange. The second through hole is arranged at the middle second shaft radius, which of course corresponds to the middle second frame radius. In this row, the connection screw is inserted from the shaft side through the through hole in the shaft connection flange and screwed into the threaded blind hole in the frame connection flange.

[0012] Finally, the third row includes: a third threaded blind hole in the frame connection flange, which, like the second threaded blind hole, extends from the front surface of the frame into the frame connection flange; and a third through-hole in the shaft connection flange, which again extends from the front surface of the shaft to the opposite side of the shaft connection flange. These holes are, of course, arranged at the corresponding third radius, the inner third frame radius, and the inner third shaft radius. In this row, the connection screws are also inserted from the shaft side through the through-holes in the shaft connection flange and screwed into the threaded blind holes in the frame connection flange.

[0013] The threaded connection according to the invention therefore comprises only a combination of through holes and threaded blind holes and screw connections, wherein, unlike the prior art, only one row for inserting the screws is accessible from the chassis side, which makes the arrangement of the screws or the connection easier.

[0014] According to an embodiment of the present invention, a frame connection flange is attached to a cylindrical base portion, and a shaft connection flange is attached to a cylindrical shaft portion, wherein the frame connection flange includes a radially outer frame flange portion and a radially inner flange portion separated by the frame flange portion, and wherein the shaft connection flange includes a radially outer frame flange portion and a radially inner flange portion separated by the shaft flange portion, wherein an outer first frame radius is located in the radially outer frame portion, and an intermediate second shaft radius and an inner third shaft radius are located at the inner shaft flange portion. The base portion includes a cylindrical base portion connected to the frame connection flange, the frame connection flange extending radially relative to the base portion such that the frame connection flange includes a radially outer frame flange portion and a radially inner frame flange portion. A similar arrangement is provided on the shaft, comprising a cylindrical shaft portion to which the shaft connection flange is attached, the shaft connection flange extending radially relative to the shaft portion and having a radially outer shaft flange portion and a radially inner shaft flange portion. As described above, the first row of holes arranged at the outer first frame radius and the outer shaft radius are provided in the corresponding outer frame flange part and the outer shaft flange part, wherein the second and third rows of holes are arranged at the middle second frame radius and the middle second shaft radius (second row), or at the inner third frame radius and the inner third shaft radius (third row), respectively. Therefore, as mentioned above, the threaded connections of the outer first row inserted from the chassis side are inserted from the outside of the chassis, where there is enough space for inserting and tightening the screws. Tightening can be done easily. The threaded connections provided at the middle hole and the inner hole are accessible from the inside of the hollow shaft, which also allows easy screwing. There is no need to tighten from the inner chassis part (which, as mentioned above, is sometimes difficult), so that EHS statistics (EHS = Environment, Health and Safety) can be improved.

[0015] According to a preferred embodiment, the first, second and third rows extend around the entire circumferential portion of the respective frame flange and shaft flange. All three rows extend around 360°, thus describing complete concentric circles. The holes in each row are evenly distributed at equidistant positions. According to an alternative, only one or two of the first, second and third rows extend around the entire circumferential portion, while the remaining row or rows extend only around a portion of the circumferential portion. According to this embodiment, only one or two rows describe a complete 360° circle, while the remaining row or two rows extend only around a portion of the circumferential portion, which may be approximately 180° or 270°. Therefore, different row arrangements or hole arrangements are possible, which can be adapted to the mechanical needs of the connection.

[0016] Preferably, each threaded connection includes a threaded bolt-like screw threaded into the corresponding threaded hole and a nut threaded on the bolt and supported on the corresponding opposite sides of the corresponding flange portion. This type of threaded connection allows the threaded bolt-like screw to be tightly screwed into the threaded hole to be tightly fixed in the threaded hole, and then the nut to be screwed onto the threaded bolt-like screw to be securely tightened because the nut is supported on the corresponding opposite sides of the corresponding flange portion when being tightened.

[0017] According to a preferred embodiment, an intermediate annular plate is sandwiched between the frame front surface and the shaft front surface, wherein the threaded connections extend through the plate in corresponding through-holes, which of course are flush with the corresponding through-holes and threaded holes of the rows. The frame front surface and the shaft front surface do not directly abut each other, but the intermediate annular plate is sandwiched between these two front surfaces. The threaded connections extend through the plate in corresponding holes, so that the intermediate plate is not only sandwiched between the front surfaces, but is also directly fixed by means of the threaded connections extending through the plate. Of course, these plate through-holes are flush with their corresponding through-holes and threaded holes of the rows. The plate is an anti-ovalization plate, which reduces any possible ovalization of the flange connection due to loads acting on the shaft and the chassis. The intermediate plate also supports to keep any variations in the air gap between the rotor and the stator as small as possible.

[0018] Preferably, the plate extends at least partially further into the interior of the chassis and axle than the frame connection flange and the axle connection flange. This provides better reinforcement of the flange area or flange connection while still providing a central opening large enough to allow maintenance personnel to enter the axle from the chassis through the opening.

[0019] In addition to the central opening, the plate itself may comprise one or more further openings. Such further openings may for example be used to pass any items, such as cables etc., through the area.

[0020] The intermediate plate is preferably made of steel, while the hollow shaft and the chassis are preferably made of cast metal.

[0021] The wind turbine is preferably a direct drive turbine comprising a direct drive generator, preferably comprising an outer rotor and an inner stator. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other objects and features of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. However, the accompanying drawings are only schematic diagrams, which are designed only for illustrative purposes and do not limit the present invention. The accompanying drawings show:

[0023] Figure 1 is a partial view of a wind turbine according to the present invention;

[0024] Figure 2 yes Figure 1an enlarged section II of FIG. 1 showing the flange connection between the chassis and the shaft; and

[0025] Figure 3 is a schematic diagram of a wind turbine according to the present invention. DETAILED DESCRIPTION

[0026] Figure 1 A partial view of a wind turbine 1 according to the present invention is shown, comprising a hollow base frame 2 secured to a tower (not shown). Attached to the base frame 2 is a hollow shaft 3, which, like the base frame 2, is also stationary. The stationary shaft 3 carries a stator 4, which is also stationary, and a rotor 5, which is rotatably arranged relative to the stator 4 via corresponding bearings. The stator 4 and rotor 5 are part of a direct-drive generator 6. The rotor 5 is directly coupled to a hub 7, to which a plurality of rotor blades 8 are attached. When wind blows, the rotor blades interact with the wind and begin to rotate. This rotation is transmitted via the hub 7 to the directly coupled rotor 5, which rotates around the stationary stator 4, causing the generator 6 to generate electricity, as is generally known.

[0027] The chassis 2 is connected to the shaft 3 via a flange connection 9 which is specific to the invention and is Figure 2 3. This partial view shows a portion of the chassis 2 and a portion of the shaft 3. The chassis 2 comprises a cylindrical frame portion 10 to which a frame connection flange 11 is attached, the chassis 2 being a one-piece structure. The frame connection flange 11 comprises a radially outer frame flange portion 12 extending radially to the outside of the chassis 2 and a radially inner frame flange portion 13 extending to the inside of the chassis 2. In addition, the frame connection flange 11 comprises a frame front surface 14 which, like the frame connection flange 11, is of course also cylindrical.

[0028] The shaft 3 includes a cylindrical shaft portion 15 to which a shaft connection flange 16 is attached, and is a one-piece structure. The shaft connection flange 15 includes a radially outer shaft flange portion 17 extending radially to the outside of the shaft 3 and a radially inner shaft flange portion 18 extending to the inside of the shaft 3. In addition, the shaft connection flange 16 includes a shaft front surface 19, which is also cylindrical like the shaft connection flange 16.

[0029] Figure 2 The flange connection 9 shown in FIG. 1 on the downwind side comprises various holes arranged in a specific arrangement of three rows. These rows comprise through holes arranged in one connection flange and threaded blind holes arranged in the other connection flange.

[0030] In detail, the frame connection shaft 11 includes a first row Ia in the outer frame flange portion 12, comprising first through-holes 20 arranged at an outer first frame radius. In the opposing shaft connection flange 16, a first row Ib comprising first threaded blind holes 21 is provided in the outer shaft flange portion 17, these first threaded blind holes 21 being arranged at an outer first shaft radius, where the first shaft radius corresponds to the first frame radius. A threaded connection 22, comprising a threaded bolt-like screw 23, is inserted into the first through-hole 20 and screwed into the first threaded hole 21. A nut 24 and a washer 25 are arranged at the threaded free end of the screw 23, with the nut 24 being tightened to tighten the threaded connection and securely secure the two flanges.

[0031] Furthermore, the frame-connecting shaft 11 includes a second row IIa in the inner frame flange portion 13, comprising second threaded blind holes 26 disposed at the intermediate second frame radius. In the opposing shaft-connecting flange 16, a second row IIb is provided in the inner shaft flange portion 17, comprising second through-holes 27 disposed at the intermediate second shaft radius, where the second shaft radius corresponds to the second frame radius. A threaded connection 28, comprising a threaded, bolt-like screw 29, is inserted into the second through-hole 27 and screwed into the second threaded hole 26. A nut 29 and a washer 30 are arranged at the threaded free end of the screw 28, with the nut 29 being tightened to tighten the threaded connection and securely secure the two flanges.

[0032] Finally, the frame-connecting shaft 11 includes a third row IIIa in the inner flange portion 13, comprising third threaded blind holes 31, arranged at the inner third frame radius. In the opposing shaft-connecting flange 16, a third row IIIb is provided in the inner shaft flange portion 17, comprising third through-holes 32, arranged at the inner third shaft radius, where the third shaft radius corresponds to the third frame radius. A threaded connection 33, comprising a threaded, bolt-like screw 34, is inserted into the third through-hole 32 and screwed into the third threaded hole 31. A nut 35 and a washer 36 are arranged at the threaded free end of the screw 34, with the nut 35 being tightened to tighten the threaded connection and securely secure the two flanges.

[0033] Between the two flanges 11, 16, an intermediate annular plate 37 is sandwiched between the frame front face 14 and the shaft front face 19, wherein the corresponding threaded connections 23, 28 and 33 extend through the plate 37 exactly at the first, second and third radii in corresponding through-holes 38, 39 and 40 provided in the plate 37. This plate 37, preferably made of steel, has the purpose of resisting ovalization, since it reinforces the flange connection 9 against any ovalization caused by any load acting on the flange connection 9. By this reinforcement, the size of the air gap provided between the stator 4 and the rotor 5 is also maintained.

[0034] like Figure 2 As shown, the flange connection of the present invention comprises only one through hole in each row and a corresponding flush threaded blind hole. Thus, in each flange 11, 16, only three holes need to be drilled, observed at one circumferential position, which is less complex than the known flange connection of the chassis to the shaft.

[0035] All three rows may extend completely around 360° around the respective flange 11, 16. In an alternative, it is possible that only one or two rows extend 360°, while the remaining rows extend only around a portion of the circumference, for example around 180° or 270°, as desired taking into account mechanical requirements.

[0036] Figure 3 A schematic diagram of the intermediate plate 37 is shown. As mentioned above, this plate is annular. It includes a central opening 41 through which maintenance personnel can reach the shaft from the chassis. Opening 41 is designed so that plate 37 extends further into the interior of chassis 2 or shaft 3 than flanges 11 and 16. This protrusion further enhances the reinforcement effect. If desired, additional openings 42 can be provided through which items such as cables can be passed.

[0037] Although the present invention has been described in detail with reference to the preferred embodiments, the present invention is not limited to the disclosed examples, and those skilled in the art can derive other variations from the disclosed examples without departing from the scope of the present invention.

[0038] Independent of the grammatical use of the term, individuals with both male and female gender identities are included within the term.

Claims

1. A wind turbine comprising a hollow base frame (2) having a cylindrical frame connection flange (11) with a frame front surface (14) and a hollow shaft (3) having a cylindrical shaft connection flange (16) with a shaft front surface (19), wherein the shaft connection flange (16) is fixed to the frame connection flange (11) by a threaded connection arranged in axially extending holes provided in the frame connection flange (11) and the shaft connection flange (15), characterized in that: - the frame connection flange (11) is provided with a first row (Ia) of first through holes (20), which extend from the frame front surface (14) to the opposite face of the frame connection flange (11) and are arranged at an outer first frame radius, and the shaft connection flange (16) is provided with a first row (Ib) of first threaded blind holes (21), which extend from the shaft front surface (19) into the shaft connection flange (16) and are arranged at an outer first shaft radius corresponding to the outer first frame radius, - the frame connection flange (11) is provided with a second row (IIa) of second threaded blind holes (26), which extend from the frame front surface (14) into the frame connection flange (11) and are arranged at an intermediate second frame radius, and the shaft connection flange (16) is provided with a second row (IIb) of second through holes (27), which extend from the shaft front surface (19) to the opposite face of the shaft connection flange (16) and are arranged at an intermediate second shaft radius corresponding to the intermediate second frame radius, - the frame connection flange (11) is provided with a third row (IIIa) of third threaded blind holes (31), which extend from the frame front surface (14) into the frame connection flange (11) and are arranged at an inner third frame radius, and the shaft connection flange (16) is provided with a third row (IIIb) of third through holes (32), which extend from the shaft front surface (19) to the opposite face of the shaft connection flange (16) and are arranged at an inner third shaft radius corresponding to the inner third frame radius, - wherein the through hole (20, 27, 32) is flush with the threaded hole (21, 26, 31) and the threaded connection (22, 28, 33) extends through the through hole (20, 27, 32) and is screwed into the threaded blind hole (21, 26, 31).

2. The wind turbine according to claim 1, characterized in that The frame connection flange (11) is attached to a cylindrical base portion (10), and the shaft connection flange (16) is attached to a cylindrical shaft portion (15), wherein the frame connection flange (11) includes a radially outer frame flange portion (12) and a radially inner frame flange portion (13) separated by the frame flange portion (10), and wherein the shaft connection flange (16) includes a radially outer shaft flange portion (17) and a radially inner shaft flange portion (18) separated by the shaft flange portion (15), wherein the outer first frame radius is located in the radially outer frame portion (12), and the intermediate second shaft radius and the inner third shaft radius are located at the inner shaft flange portion (18).

3. The wind turbine according to claim 1 or 2, characterized in that The first row, the second row and the third row (Ia, Ib, IIa, IIb, IIIa, IIIb) extend around the entire circumferential portion of the corresponding frame connecting flange (11) and the shaft connecting flange (16), or wherein only one or two of the first row, the second row and the third row (Ia, Ib, IIa, IIb, IIIa, IIIb) extend around the entire circumferential portion, and the remaining one or more rows (Ia, Ib, IIa, IIb, IIIa, IIIb) extend only around a portion of the circumferential portion.

4. A wind turbine according to any one of the preceding claims, characterised in that Each threaded connection (22, 28, 33) comprises a threaded bolt-like screw (23, 29, 34) screwed into a corresponding threaded hole (21, 26, 31) and a nut (24, 29, 36) screwed onto the screw (23, 29, 34) and supported on corresponding opposite sides of the corresponding flange portion (12, 18).

5. A wind turbine according to any one of the preceding claims, characterised in that An intermediate annular plate (37) is sandwiched between the frame front surface (14) and the shaft front surface (19), wherein the threaded connections (22, 28, 33) extend through the plate (37) in respective through holes.

6. The wind turbine according to claim 5, characterized in that The plate (37) at least partially extends further into the interior of the base frame (2) and the shaft (3) than the frame connection flange (11) and the shaft connection flange (16).

7. A wind turbine according to claim 5 or 6, characterized in that The plate (37) includes one or more openings (42).

8. A wind turbine according to any one of claims 5 to 7, characterized in that The plate (37) is made of steel.

9. A wind turbine according to any one of the preceding claims, characterised in that The wind turbine is a direct drive turbine.

Images