Wind turbine power transmission system

Abstract

The invention relates to a wind turbine (2) comprising a nacelle (8) arranged on top of a tower (12), a rotor comprising a hub (6) and a plurality of blades (4), a main shaft (16) configured to be driven by the rotor about a main axis and supported on the nacelle (8), a generator (28) having a generator rotor and a generator stator, and a gear system (25) arranged to increase the rotational speed between the rotor and the generator rotor. The gear system (25) comprises a stationary ring gear (50), an input member (53) coupled to or driven by the main shaft (16), the input member (53) having a plurality of radially movable tooth segments (52, 63) carried in a guiding slot and engageable at an outer end with the ring gear (50), a central output member (55) within the input member (53), the central output member having an outer eccentric profile acting on and driven by inner ends of the radially movable tooth segments (52, 63), whereby through engagement with the ring gear (50) a rotational movement of the input member (53) drives the radially movable tooth segments (52, 63) and effects a rotation of the central output (55) member.

Description

Technical Field

[0001] This invention relates to a power transmission system for wind turbines. More specifically, this invention relates to a wind turbine including a novel gearbox. Background Technology

[0002] Wind turbines typically consist of a rotor with large blades driven by the wind. The blades convert the kinetic energy of the wind into rotational mechanical energy. This mechanical energy typically drives one or more generators to produce electricity. Therefore, wind turbines include a power transmission system for processing rotational mechanical energy and converting it into electrical energy. This power transmission system is sometimes referred to as the "powertrain" of the wind turbine. The part of the power transmission system that runs from the rotor to the generator is called the drivetrain.

[0003] It is often necessary to increase the rotor speed to the speed required by the generator. This is achieved through a gearbox between the rotor and the generator. Therefore, the gearbox forms part of the powertrain and converts the low-speed, high-torque input from the rotor into a low-torque, high-speed output for the generator. Wind turbines with medium- or high-speed generators typically utilize gearboxes providing gear ratios between i = 30 and i = 140, requiring gearboxes with two or three gear stages, which can be individual planetary gear sets or combinations with parallel gear stages. These gears have certain VOC (Volume of Control), weight, and therefore cost and given efficiency. There is a desire to find alternative types of gearboxes where higher gear ratios per VOC / weight can be achieved in the high-torque range of modern wind turbine technology.

[0004] US8656809B2 and US8256327B2 disclose an alternative type of gear system comprising radially moving teeth and further based on, for example, the technology of WO99 / 36711, both used to reduce high motor speeds to low speeds (gradual reduction) required for, for example, machine tool functions. For ease of reference, the technology described in US8656809B2 and US8256327B2 will be referred to hereinafter as radially moving tooth design.

[0005] The radially moving tooth design intuitively suggests that it can only operate as a reduction gear, similar to a worm gear drive. Indeed, the disclosure in US8656809B2 describes it as a reduction gear, mentioning that the radially moving tooth design allows for a very high range of drive input speeds, up to approximately 6000 rpm, and further allows for a free selection of gear ratios from approximately i = 10 to i = 200.

[0006] Using this invention, the inventors have realized that radial moving tooth design technology can also be used in speed-increasing gear devices, and is particularly advantageous in gearboxes for wind turbines to obtain compact wind turbine drive systems. Summary of the Invention

[0007] This invention relates to a wind turbine comprising: a nacelle disposed on top of a tower; a rotor including a hub and a plurality of blades; a main shaft configured to be driven by the rotor about a main shaft and supported on the nacelle; a generator having a generator rotor and a generator stator; and a gear system arranged to increase the rotational speed between the rotor and the generator rotor. The gear system includes: a fixed gear ring; an input member coupled to or driven by the main shaft, the input member having a plurality of radially movable tooth segments carried in guide slots and capable of engaging the gear ring at their outer ends; and a central output member within the input member, the central output member having an external eccentric profile acting on and driven by the inner ends of the radially movable tooth segments, thereby driving the radially movable tooth segments and achieving rotation of the central output member through engagement with the gear ring.

[0008] Compared to conventional gears used in wind turbines, the radially moving gear design introduces new fundamental principles. Instead of rotating gears, a large number of individual tooth segments are used to connect between the input and output, ensuring that each tooth segment is utilized multiple times during a single rotation around the center. This provides a gear system that can handle transmission ratios between 10 and approximately 100 with exceptionally high power density and stiffness in a single stage. Furthermore, the gear system is very compact, exhibiting an excellent power-to-size ratio.

[0009] The key to using radially moving gear designs in machine tools with power ranges of several kW is the absence of backlash in the system. Machine tools and robots require extremely precise positioning, which does not allow for any backlash, and furthermore, backlash can be destructive due to potential vibrations.

[0010] Through this invention, the inventors discovered that, conversely, for purposes in MW-class wind turbines, the load on the gears needs to be more controlled, and in operating modes, the gears will never contact the opposite side. Therefore, in wind turbines, backlash is advantageously introduced by taking back the unloaded tooth surface and thus making fine adjustments to optimize efficiency.

[0011] Compared to typical wind turbine gearboxes that include conventional gears, significant VOC savings can be seen to achieve the same ratio as radially moving gear design systems. This is generally considered in light of the already apparent substantial advantages in power density and VOCs. Since the internal components are made from standard steel typically used in gearboxes using standard hardening processes, the cost per kg will be similar to that of gearboxes today, at least after the introduction of this technology.

[0012] An additional feature that is highly advantageous for use in wind turbines is that the radially moving tooth design offers unique possibilities for drive scalability, namely through:

[0013] 1. For a given torque, reduce the outer diameter by providing multiple rows of tooth segments.

[0014] 2. Scale torque by the number of tooth segments.

[0015] 3. Scale the torque by the number of tooth rows.

[0016] An additional feature that is highly advantageous for use in wind turbines is that the radially moving tooth design exhibits beneficial noise and vibration characteristics.

[0017] In a preferred embodiment of the invention, the input member is an annular input member, i.e., a generally annular member. Furthermore, the tooth segments are mounted such that they can be radially displaced outward and inward within guide slots in the input member.

[0018] In embodiments of the invention, each radially movable tooth segment is connected to an inclined pad via a flexible connection (preferably a cylindrical joint-like connection); the inclined pad is adapted to slide along the output member. In other embodiments, a spherical joint-like connection may also be applicable.

[0019] In embodiments of the invention, the output member has a generally circular cross-section and at least one eccentricity, preferably at least two eccentricities. In various embodiments, the output member has at least one eccentricity that acts on when the radially movable tooth segment moves into a corresponding tooth in the gear ring during rotation of the input member, in order to transmit torque and set a selectable gear ratio. In various embodiments, the number of eccentricities can be at least two, at least three, or even at least four. Thus, the gear ratio can be set or changed. This gear ratio can also be adjusted by varying the number of tooth segments and the number of internal teeth on the gear ring.

[0020] In embodiments of the invention, the output component is coupled to at least one additional gear stage, such as a parallel gear stage. The invention allows the new gear system to function as a standalone full gearbox, or to be coupled with known gear stages (e.g., planetary gear stages or parallel gear stages). Any such combination is also within the scope of the invention.

[0021] In embodiments of the invention, backlash is permitted between the unloaded tooth surface and the rear tooth surface of the gear ring. In known systems using radially moving tooth designs, precision is essential, and backlash is not permissible. In wind turbines, this is not a situation where a simpler and more durable design is allowed. This backlash along the circumferential direction can be, for example, at least 0.5 mm, such as at least 1 mm.

[0022] In an embodiment of the invention, the gear system has a speed-increasing transmission ratio between i = 10 and i = 150, preferably between i = 20 and i = 75, for example between 25 and 50.

[0023] In an embodiment of the invention, the gear system has a plurality of radially movable tooth segments between 10 and 200, preferably between 40 and 100.

[0024] In embodiments of the invention, the gear system has at least two rows of radially movable tooth segments, for example, at least three rows. In various embodiments, the number of rows can be a single number, as shown, but two, three, four, or five rows also offer significant advantages in allowing for flexible use of the same element at various torque levels. In some embodiments, the number of radially movable tooth segments per row is between 12 and 60.

[0025] In embodiments of the present invention, the diameter of the gear ring is between 1000 mm and 3500 mm, preferably between 1500 mm and 2500 mm.

[0026] In embodiments of the invention, the movable tooth segment is cylindrical, with a diameter between 10 cm and 20 cm and a length between 20 cm and 50 cm. Needless to say, the dimensions involved in the process are much larger than those used for machining. In machining, a typical tooth segment has a maximum diameter of 2 cm and a maximum length of 5 cm.

[0027] In embodiments of the invention, the outer tooth profile of the tooth segment and / or the tooth profile of the inner teeth of the gear ring have tooth profiles relative to the gear set axis, which enable surface contact in the engagement region, wherein the surface contact is achieved by designing a logarithmic spiral. The advantage of radially moving tooth designs is that they do not utilize the commonly used involute tooth surface, but instead use a tooth profile following a logarithmic spiral. This allows for greater surface contact in the engagement region.

[0028] In embodiments of the present invention, regardless of the selected radius of the gear set axis (M), the outer tooth surface profile of the tooth surface region of the tooth segment and the inner tooth surface profile of the tooth system of the gear ring correspond to a common logarithmic spiral (Ln) with a pitch angle (α).

[0029] In embodiments of the invention, a uniform load distribution exists during the stroke of the tooth segment because the tooth segment shifts along a logarithmic spiral (Ln), and the tooth surfaces of the tooth segment and the inner teeth of the gear ring that come into contact with each other always have the same pitch angle (α).

[0030] In embodiments of the invention, the pitch angle (α) is between 15° and 75°, such as between 20° and 40°. In other embodiments, (α) may be between 30° and 60°.

[0031] In an embodiment of the invention, the tooth segment has an end curve that is tangentially supported against the tooth surface and incorporated into its outer tooth surface profile.

[0032] In an embodiment of the present invention, the root fillet of the gear ring is disposed between the corresponding tooth surface contours of the inner teeth of the gear ring, wherein the curvature of the root fillet of the gear ring is less than the end curve of the tooth segment.

[0033] In embodiments of the invention, a coating is used at at least one of the following interfaces: tooth segment to gear ring, tooth segment to input member, and tilt pad to output member. Friction loss can be reduced by using a coating on appropriate contact surfaces.

[0034] In an embodiment of the invention, the wind turbine (2) has a nominal power of at least 2MW, for example at least 4MW.

[0035] In an embodiment of the present invention, the wind turbine further includes:

[0036] A support structure, the support structure including at least one bearing, the at least one bearing supporting the main shaft for rotation about the main shaft and constraining other movements;

[0037] The gear system thereon has a gearbox housing rigidly connected to the support structure.

[0038] In an embodiment of the invention, the support structure further includes a bearing housing surrounding at least one bearing, with the gearbox housing suspended from the bearing housing.

[0039] As described above, the generator is connected to the output component. The generator has a generator rotor and a generator stator located within a generator housing, and in a preferred embodiment, the generator housing is rigidly coupled to and suspended from the gearbox housing; however, in other embodiments, the generator housing may alternatively be positioned near the gearbox, wherein the generator rotor is connected to the output component.

[0040] In an embodiment of the present invention, at least one bearing includes a first bearing and a second bearing spaced apart within a bearing housing.

[0041] In an embodiment of the present invention, the gear ring is integrated with or rigidly connected to the bearing housing, and the input member is integrated with or rigidly connected to the spindle.

[0042] In an embodiment of the present invention, the gear system is fully integrated within the bearing housing, such that the gear ring is positioned between the first bearing and the second bearing along the rotation axis of the main shaft.

[0043] Although the gear system itself is very compact, an even more compact solution can be achieved by fully integrating the gear system into the bearing housing. In this solution, the generator can be positioned directly behind the bearing housing. Attached Figure Description

[0044] The above and other aspects of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0045] Figure 1 This is a perspective view of an example wind turbine.

[0046] Figure 2 It is used for Figure 1 A perspective view of the power transmission system of a wind turbine.

[0047] Figure 3 yes Figure 2 Cross-sectional view of the power transmission system.

[0048] Figure 4 This is a perspective view of a power transmission system according to an embodiment of the present invention.

[0049] Figure 5 The cross-section is schematically shown as a portion of a gear mechanism according to an embodiment of the present invention.

[0050] Figure 6 A schematic plan view showing an embodiment of an internal gear ring system with a tooth surface profile and a gear ring is provided.

[0051] Figure 7 It shows Figure 6 A schematic magnified detail shown in the tooth area, and

[0052] Figure 8 Alternative embodiments of the invention are shown.

[0053] Note that the same or similar features are indicated by the same reference numerals in different figures. Detailed Implementation

[0054] Figure 1An example of a wind turbine 2 is shown. Although an offshore wind turbine is shown, it should be noted that the following description is also applicable to other types of wind turbines. The wind turbine 2 includes a rotor comprising blades 4 mounted to a hub 6, which is supported by a nacelle 8 on a tower 12. Wind causes the rotor (blades 4 and hub 6) to rotate about a main shaft 14. Figure 2 The rotational energy is transmitted to the power transmission system (or "power system") 10 housed in the engine room 8.

[0055] Figure 2 and Figure 3 A prior art power transmission system 10 is shown, which includes a main shaft 16 coupled to a hub 6. Figure 1 The power transmission system 10 also includes a first bearing 18 and a second bearing 20 supporting the main shaft 16, a bearing housing 22 surrounding the first bearing 18 and the second bearing 20, and a gearbox 24 having an input member driven by the main shaft 16. The gearbox 24 increases the rotational speed between the main shaft 16 and the generator 28. It should be noted that... Figures 1 to 3 The components shown, such as the rotor, hub 6, main shaft 16 and nacelle 8, are shown only as examples and can be varied in design within the scope of the invention.

[0056] The type of input component depends on the specific gearbox design. Figure 3 The prior art gearbox is shown with a planetary carrier using a first planetary gear stage, wherein the ring gear is fixed to the housing, which causes the sun gear to increase its rotational speed to transmit to the next stage of the gearbox.

[0057] Figure 4 It shows something similar to Figure 2 The power transmission system 10 of the prior art system is replaced by a gear system 25 according to the present invention, which includes radially moving tooth gears. Note that the other components of the power transmission system are the same, namely the generator 28 and the bearing housing 22 including the main shaft 16. Note that although the axial width of the new gear system is much smaller than that of the prior art gearbox, Figure 2 and Figure 4 The gear ratios of the gearboxes are comparable. Therefore, it is clearly visible, even visually, that the new gearbox, which includes a radially moving tooth design, offers significant savings in both volume and weight compared to conventional gearboxes in wind turbines.

[0058] The basic functions of radially moving tooth design gears are described in detail in US8656809B2 and US8256327B2, and additional details regarding the operation of radially moving tooth design gears can be found in these documents.

[0059] Figure 5A portion of a coaxial gear set R with a radially moving tooth design is shown and will now be described in the context of embodiments of the invention, wherein the radially moving tooth design is used to increase the relative speed between hub 6 and generator rotor.

[0060] The gear ring 50 is a fixed component, and is a component fixed to or formed as part of the gearbox housing. Its tooth segments are equipped with tooth surfaces following a logarithmic spiral 56. A plurality of identical cylindrical tooth segments 52, also equipped with tooth surfaces following a logarithmic spiral, are received by the gear carrier 53, which serves as an input component. Furthermore, the tooth segments 52 are mounted such that they can be radially displaced outward and inward within guide slots in the gear carrier 53.

[0061] The gear carrier 53 represents the input shaft and is physically connected to the main shaft 16, rotating at the same speed as the main shaft 16. All gear segments 52 rest on the same inclined pads 54 guided by the eccentric shaft 55. The camshaft may also be designated as having a basic diameter r1 and one or more eccentricities e, such that the maximum eccentricity r2 is r1 + e.

[0062] A sliding bearing is provided between the outer contour of the eccentric shaft 55 and the inclined pad 54. The rotating carrier 53 drives the tooth segment 52, and the tooth segment 52 is thus driven by the eccentric shaft 55, which serves as the output element, rotating at an increased speed compared to the carrier 53. Depending on the design parameters used, the rotation directions between the carrier 53 and the output shaft 55 can be the same or opposite.

[0063] The tilting pads ensure that the force from the radially inward movement of the tooth segment is distributed over a large area of ​​the output shaft. The tilting pads are tiltable to follow the output shaft eccentricity in all rotational positions. Each of the tilting pads is characterized as a cylinder, thus creating a cylindrical joint-like connection for each individual tooth segment, with a corresponding notch in the radially innermost portion of the tooth segment. Furthermore, the tilting pads have a sliding surface that contacts the output shaft. The sliding surface on the tilting pads can be achieved by a coating or a layer of material having a low coefficient of friction on the tilting pads. Alternatively, specific individual sliding pads can be attached to the tilting pads. Or, the entire tilting pad can be made of a material with a low coefficient of friction.

[0064] In some embodiments, the inclined pads are connected to each other to form a ring structure, while in other embodiments they are simply positioned adjacent to each other to fill the entire circumference of the output shaft.

[0065] Figure 6 and Figure 7 A schematic diagram of the logarithmic spiral Ln originating from the gear set axis M of the coaxial gear set R is given. The logarithmic spiral Ln can have any desired pitch angle α.

[0066] As a function of a constant pitch angle α, the outer tooth profiles 61 and 62 of tooth segment 63 and the inner tooth profiles 64 and 65 of inner tooth 70 preferably conform to the profile or path of a logarithmic spiral Ln. Here, tooth profiles 61, 62 and 64, 65 are shown to be mirror-symmetric with respect to the central axis A. However, this is not necessarily the case for wind turbines, where the gearbox does not need to be able to move in both directions.

[0067] Independent of the selected radius r, each radius starting from the gear set axis M of the coaxial gear set R intersects the tooth profiles 61 or 62 and 64 or 65 with the same pitch angle α. The pitch angle α can be freely chosen or defined as a function of the selected logarithmic spiral Ln.

[0068] The displacement of tooth segment 63 along the logarithmic spiral Ln of its tooth surfaces 64 and 65 relative to the tooth surfaces 61 and 62 of internal tooth 70, respectively, results in tooth surface regions with the same pitch angle α always being opposite each other. Therefore, very good tooth surface contact is always present.

[0069] This results in no linear rolling in the standard gear, but rather a flat displacement between the tooth segment 63 and the internal tooth 70 of the gear ring 50, which provides very high torque transmission and has less wear than in the standard gear.

[0070] Furthermore, the root fillet 71 of the gear ring is tangentially adapted to the contours 64 and 65 of the gear ring 50, and is formed in the region of the tooth root 73 of the internal tooth 70 between two adjacent tooth systems 72.

[0071] The curvature here is preferably less than the end curve 74 of tooth segment 63. The end curve 74 of tooth segment 63 is adapted to the tooth surface profiles 61, 62 in a tangential manner. Thus, a low-bump transition is ensured between each up-and-down movement of tooth segment 63.

[0072] The contact area should be as large as possible to transmit the maximum possible force and torque, especially in the area of ​​the tooth system 72 of the gear ring 50. In addition, due to the low-bump tooth segment 63 stroke movement, the tooth segment 63 automatically retracts due to the design of the tooth surface profile.

[0073] A preferred aspect of the invention is that the outer profile of the tooth segment, particularly in the region of the tooth surface, follows a logarithmic spiral profile. A logarithmic spiral represents a curve that intersects all radii originating from the origin at the same pitch angle α. Its path is defined by the formula r = e^aα, where tanα = 1 / a, a is a real constant, and a > 0.

[0074] The pitch angle α can be selected as needed, ranging from 15° to 75°, for example, from 30° to 60°, via a corresponding function of the logarithmic spiral. As a result, it can also affect the different tooth surface geometries of the internal gear system and tooth segments. In other embodiments, the pitch angle α can be selected as needed, ranging from 15° to 45°, such as from 20° to 40° or from 25° to 35°.

[0075] This profile is also used as the profile of the tooth system, particularly the internal tooth system of the gear ring. Thus, in the engagement area between the two tooth surfaces of the tooth segment and the tooth system of the gear ring, complete surface contact is achieved between the tooth surface profile of one tooth segment and the tooth surface profile of the tooth system.

[0076] The logarithmic spiral geometry ensures complete surface contact during the radial movement of the tooth segments into the internal tooth system of the gear ring, independent of the gear radius and size. Furthermore, it achieves optimal load distribution (pressure distribution), resulting in very good transmission of high torque. Additionally, wear is likely to be lower than in conventional wind turbine gearboxes, and at least the final wear will be uniform across the tooth surfaces. This can lead to longer service life and less maintenance required, which is of paramount importance in the wind turbine industry, where downtime should be minimized.

[0077] Assuming the gear ring has z2 = 80 tooth segments and the central shaft characteristic z1 = two maximum eccentricities, the transmission ratio between carrier 53 and shaft 55 is calculated as follows:

[0078]

[0079] Each tooth segment 52 has line contact with the internal tooth system of the gear ring (see...). Figure 7 Because the tooth profile follows a logarithmic spiral, it develops into a fully hydrodynamic contact, i.e., using surface contact instead of line contact. There is no rolling contact as known from involute gears. Due to the cylindrical shape of the tooth segments and the inclined pads, each tooth segment can align with the gear ring around its own axis. Therefore, an ideal load distribution factor can be achieved, similar to Khβ = 1.0 in involute gears, where the typical value is approximately 1.15.

[0080] It should be noted that the short lever of force between the head of tooth segment 52 and the supporting tooth carrier 53 is one reason for the ultimate stiffness of the gear design, which has a positive effect on the dynamics of the wind turbine.

[0081] In a preferred embodiment, the output member 55 is radially arranged within the tooth carrier 53 forming the input member and is coaxial with the tooth carrier 53.

[0082] The desired gear ratio can be selected by choosing a different number of tooth segments relative to the teeth of the gear ring 50 or the output member 55, and in particular by selecting the outer contour of the output member 55. The gear ratio can be selected or set by selecting different tooth engagements or by means of engaging different numbers of tooth segments.

[0083] In the figures shown above, only one row of tooth segments is used in the system. However, it should be noted that multiple rows of tooth segments arranged in the axial direction can also be advantageous. For example, regarding scalability, the same system can be expected to double the transmittable torque by doubling the number of rows of tooth segments. Therefore, within the scope of the invention, one, two, or three rows of tooth segments, and even more, are optional embodiments.

[0084] Furthermore, it should be noted that gearboxes with radially moving tooth designs, as shown herein, can be advantageously combined with standard gearboxes used in wind turbines. For example, a radially moving tooth design gear stage can be combined with a parallel gear stage or two parallel gear stages. If desired, combinations with planetary gear stages can also be used.

[0085] Figure 8 Alternative embodiments are disclosed, which make the wind turbine power transmission system more efficient than... Figure 4 It is more compact. Alternatively, the new gearbox is fully integrated into the spindle housing / bearing housing.

[0086] Similar to Figure 3 The power transmission system 80 includes a first bearing 88 and a second bearing 90 supporting a main shaft 86, and a bearing housing 92 surrounding the first bearing 88 and the second bearing 90. In this embodiment, the gearbox is integrated into the power transmission system such that the main shaft 86 is directly fixed to the gear carrier 81 within the bearing housing 92 and rotates together with the gear carrier 81. The gearbox operates similarly to the above principle, wherein the gear ring 82 is fixed to or integrated with the bearing housing 92, and the tooth segment 83 is radially moved, thereby increasing the rotational speed of the output shaft eccentric segment 84 compared to the rotational speed of the main shaft. This eccentric segment 84 is coupled to or integrated with the output shaft 85, which is then further coupled to a generator (not shown). Furthermore, a bearing (not shown) for the output shaft 85 will be present, for example, between the output shaft 85 and the main shaft 86.

[0087] The gear ring 82 is designed as an integral part of the bearing housing 92, with the necessary teeth machined into the bearing housing 92. Alternatively, the gear ring 82 can be flanged or bolted to the bearing housing 92 as a separate part, for example by including machined grooves in the bearing housing 92 to receive the gear ring 82. Connection via semi-elastic elements to equalize deflection and / or suppress noise is also possible.

[0088] The gear carrier 81 can be designed as an integral part of the spindle 86. The holes for the gear segments 83 can be machined radially into the spindle 86. Alternatively, the gear carrier 81 can be made as a separate part and connected between two parts of the spindle 86.

[0089] The axial position of the gear system 25 within the bearing housing can be set based on desired parameters. Depending on the system dimensions and other parameters, the ideal axial position can be varied and adjusted accordingly, as shown in 87. In one embodiment, the position of the gear system 25 is between 30% and 70% of the distance between the first bearing 88 and the second bearing 90. In other embodiments, the position of the gear system 25 is less than 25% of the distance between the first bearing 88 and the second bearing 90 (measured from either one).

[0090] The above embodiments are merely examples of the invention as defined by the following claims. Based on this description, those skilled in wind turbine design will understand other examples, modifications, and advantages. In view of the foregoing, details of any particular embodiment should not be construed as necessarily limiting the scope of the following claims.

Claims

1. A wind turbine (2) comprising: a nacelle (8) arranged on top of a tower (12); a rotor comprising a hub (6) and a plurality of blades (4), a main shaft (16) configured to be driven by the rotor about a main shaft axis and supported on the nacelle (8), a generator (28) having a generator rotor and a generator stator, and a gear system (25) arranged to increase the rotational speed between the rotor and the generator rotor; wherein the gear system (25) comprises: a stationary ring gear (50), an input member (53) coupled to or driven by the main shaft (16), the input member having a plurality of radially movable tooth segments (52, 63) carried in a guide slot and engageable at an outer end with the ring gear (50), a central output member (55) located within the input member (53), the central output member having an outer eccentric profile acting on and driven by inner ends of the radially movable tooth segments (52, 63), whereby through engagement with the ring gear (50) a rotational movement of the input member (53) drives the radially movable tooth segments (52, 63) and effects a rotation of the central output member (55).

2. A wind turbine according to claim 1, wherein, The input member is an annular input member.

3. Wind turbine (10) according to claim 1 or 2, wherein Each radially movable tooth segment (52, 63) is connected to an inclined pad (54) by a flexible connection; the inclined pad (54) is adapted to slide along the output member (55).

4. Wind turbine according to claim 1 or 2, wherein The output member (55) is substantially circular in cross section with at least one eccentricity.

5. A wind turbine according to claim 1 or 2, wherein, The output member (55) is coupled to at least one further gear stage.

6. A wind turbine according to claim 1 or 2, wherein, The gear system exhibits a backlash between a non-loaded tooth face and a trailing tooth face of the ring gear.

7. A wind turbine according to claim 1 or 2, wherein The gear system (25) has a speed increasing transmission ratio between i = 10 and i = 150.

8. A wind turbine according to claim 1 or 2, wherein, The gear system (25) has between 10 and 200 radially movable tooth segments (52, 63).

9. A wind turbine according to claim 1 or 2, wherein, The gear system (25) has at least two rows of radially movable tooth segments.

10. A wind turbine according to claim 1 or 2, wherein, The gear system (25) has at least one row of radially movable tooth segments, and wherein the number of radially movable tooth segments per row is between 12 and 60.

11. A wind turbine according to claim 1 or 2, wherein, The diameter of the ring gear is between 1000 mm and 3500 mm.

12. A wind turbine according to claim 1 or 2, wherein, The movable tooth segments (52, 63) are cylindrical, have a diameter between 10 cm and 20 cm and a length between 20 cm and 50 cm.

13. A wind turbine according to claim 1 or 2, wherein, The tooth face profile (61, 62) of the outer tooth face of the tooth segments and / or the tooth face profile (64, 65) of the teeth (13) of the inner toothing (72) of the ring gear (50) have a gear profile with respect to the gear set axis (M) that enables a face contact in the region of engagement, wherein the face contact is realized by a logarithmic spiral.

14. A wind turbine according to claim 1 or 2, wherein, The outer tooth flank profile (61, 62) of the tooth face area of the tooth segment (52, 63) and the inner tooth system profile of the tooth system of the ring gear correspond to a common logarithmic spiral (Ln) with a pitch angle (a), regardless of the chosen radius of the gear set axis (M).

15. A wind turbine according to claim 14, wherein, The pitch angle (a) is between 15° and 75°.

16. A wind turbine according to claim 1 or 2, wherein, A coating is used in at least one of the following interfaces: tooth segment (52, 63) to ring gear (50), tooth segment (52, 63) to input member (53), and tilt pad (54) to output member (55).

17. A wind turbine according to claim 1 or 2, wherein, The wind turbine (2) has a nominal power of at least 2 MW.

18. The wind turbine of claim 1, further comprising: a support structure comprising at least one bearing (18, 20) supporting the main shaft (16) for rotation about the main shaft axis and constraining other motions; wherein the gear system has a gear box housing rigidly coupled to the support structure.

19. A wind turbine according to claim 18, wherein, The support structure further comprises a bearing housing (22) surrounding the at least one bearing (18, 20), the gear box housing being suspended from the bearing housing (22).

20. A wind turbine according to claim 19, wherein, The at least one bearing comprises a first bearing (18) and a second bearing (20) spaced apart within the bearing housing (22).

21. A wind turbine according to claim 19 or 20, wherein, The ring gear (50) is integrated with or rigidly coupled to the bearing housing (22), and the input member (53) is integrated with or rigidly coupled to the main shaft (16).

22. The wind turbine of claim 20, wherein, The gear system (25) is fully integrated within the bearing housing (22) such that the ring gear (50) is positioned between the first bearing (18) and the second bearing (20) along the rotational axis of the main shaft (16).

23. The wind turbine (10) according to claim 3, wherein, The flexible connection is a cylindrical joint-like connection.

24. The wind turbine of claim 4, wherein, The output member (55) has a cross-section with at least two eccentricities.

25. A wind turbine according to claim 1 or 2, wherein, The output member (55) is coupled to one parallel gear stage.

26. A wind turbine according to claim 1 or 2, wherein, The gear system (25) has a step-up transmission ratio between i = 20 and i = 75.

27. A wind turbine according to claim 1 or 2, wherein, The gear system (25) has a number of radially movable tooth segments (52, 63) between 40 and 100.

28. A wind turbine according to claim 1 or 2, wherein, The diameter of the ring gear is between 1500 mm and 2500 mm.

29. The wind turbine of claim 14, wherein, The pitch angle (a) is between 20° and 40°.

30. A wind turbine according to claim 1 or 2, wherein, The wind turbine (2) has a nominal power of at least 4 MW.

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