Connector assembly

Abstract

The invention describes a connector assembly (1) for a driveline (2, 3, 4) comprising at least a low speed shaft (20) and a planetary gear set (3) comprising an annular arrangement of peripheral gears (31P), the connector assembly comprising: a portion (11) of each first stage peripheral gear shaft (310) arranged to project from a drive end of the planetary gear set (3); an annular arrangement of axial holes (10) formed around the low speed shaft (20), where each axial hole (10) is arranged to receive a protruding portion (11) of a peripheral gear shaft (310); and wherein each axial bore (10) and a corresponding protruding portion (11) of the peripheral gear shaft (31P) are dimensioned to establish an interference fit. The invention also describes a wind turbine drive train (2, 3, 4), and a method of connecting a low speed shaft (20) of a drive train (2, 3, 4) to a planetary gear set (3).

Description

Background Art

[0001] In a common type of horizontal axis wind turbine, an aerodynamic rotor (usually including three rotor blades mounted to a hub) rotates a low-speed rotor shaft or "main shaft", which is connected via a gearbox to a high-speed generator shaft. Ideally, the gearbox would convert the low-speed rotation of the main shaft into a high-speed rotation of the gearbox shaft without any torque loss.

[0002] During operation of the wind turbine, the aerodynamic rotor transfers loads to the main shaft. These loads include the torque to be transferred to the generator to generate electrical power, as well as extraneous loads that must be transferred via the bedplate, nacelle, and tower to the foundation. For example, extraneous loads may be caused by vibration of the rotor blades, wind shear forces, etc., and manifest as vibration or displacement of the main shaft. Care is usually taken to ensure that the support structures (housing, bearings, etc.) of the drivetrain components reliably transfer all extraneous loads towards the foundation.

[0003] The purpose of the gearbox is to reduce torque and increase rotational speed. The type of gearbox discussed herein should be understood as an epicyclic gear train. Such a gearbox typically has several stages. The main components of an epicyclic gear train are: a central gear or "sun" gear, which is carried on a longitudinal central axis (in line with the low-speed and high-speed shafts of the drivetrain); and several peripheral gears or "planet" gears, each of which is carried on a longitudinal axis. The gear axes of each stage are parallel, and the peripheral gear axes are mounted to a rotating part or "planet carrier". An epicyclic gear train can have several such stages. Hereinafter, the terms "epicyclic gear train", "planetary gear set", and "planetary gear system" may be regarded as synonyms and used interchangeably.

[0004] In a drivetrain having a multi-stage planetary gear set, the low-speed shaft rotates the first-stage planet carrier, which in turn causes the peripheral gears to rotate the first-stage central gear. Each central gear is connected to the planet carrier of the next stage, except for the last central gear, which drives the high-speed generator shaft.

[0005] The first-stage planet carrier may be in the form of a rigid plate that holds the first-stage peripheral gear axes in a desired annular configuration. The first-stage planet carrier also typically acts as a cover to enclose the front end of the gearbox. Conventionally, the first-stage planet carrier is connected in some way to the low-speed shaft of the drivetrain. The connection between the low-speed shaft and the gearbox should ideally transfer all torque to the gearbox. The usual method is to use a dedicated coupling device arranged between the low-speed shaft and the gearbox to connect the low-speed shaft to the first-stage planet carrier. Such a coupling device can include an arrangement of spline teeth, cylindrical pins, multiple bolts, shrink discs, etc.

[0006] Connector components of the prior art type are indirect solutions, i.e., torque is transmitted from the main shaft via the connector component to the planet carrier of the first stage. Then, the planet carrier transmits the torque to the first stage peripheral gear. One disadvantage of the prior art connector components is that an additional intermediate part is required, thus increasing the total cost. Since such parts may be subject to wear or fatigue, additional maintenance work increases the total energy cost. In addition, even if all components are machined to a very high precision, each transmission (from the main shaft via the connector component to the first stage planet carrier and subsequently from the planet carrier to the first stage peripheral gear) may be associated with some torque loss.

[0007] Accordingly, an object of the present invention is to provide an improved method of connecting a main shaft assembly to a planetary gear set.

[0008] This object is achieved by the claimed connector component and by the claimed method of connecting the low-speed shaft of a drive train to a planetary gear set. Summary of the Invention

[0009] The connector component of the present invention is intended for use in a drive train comprising at least a low-speed shaft and a planetary gear set. The planetary gear set may have multiple stages, each comprising an annular arrangement of peripheral gears. Hereinafter, even if the planetary gear set has only one stage, it will be referred to as the "first stage". The low-speed shaft drives the first stage of the planetary gear set. Each stage of the planetary gear set drives the next stage. Hereinafter, it should be understood that each peripheral gear includes an axially extending shaft and a toothed outer surface that engages a ring gear and a central gear.

[0010] According to the present invention, the connector component includes a portion of each first stage peripheral gear shaft that is arranged to project "backward" (i.e., in the direction of the low-speed shaft) from the drive end of the planetary gear set. This portion of the connector component of the present invention can be regarded as an annular arrangement of cylindrical protrusions extending from the front of the gearbox. The connector component further includes: an annular arrangement of axial holes formed around the low-speed shaft, wherein each axial hole is arranged to receive an exposed portion of the peripheral gear shaft; and an interference fit between each exposed portion and the corresponding axial hole. In the connector component of the present invention, each axial hole and the corresponding protruding portion are dimensioned to establish an interference fit.

[0011] The connector component of the present invention is particularly suitable for implementation in large drive trains where high torque must be transmitted from the low-speed shaft to the planetary gear set. The large drive train can be configured in a power generation facility such as a wind turbine.

[0012] One advantage of the connector assembly of the present invention is that the torque from the low-speed shaft is substantially directly transmitted to the first stage of the planetary gear set. The present invention is based on the recognition that the low-speed shaft can perform the function of the planet carrier, i.e., the low-speed shaft can hold the first-stage outer gear shafts in a desired annular structure. This is facilitated by manufacturing the gearbox such that the first-stage planetary shafts extend outward or "backward" from the front of the gearbox, thereby exposing these "extra lengths" for use in the connector assembly of the present invention. Thus, in a driveline using the connector assembly of the present invention, the planetary gear set does not require a carrier frame for the first-stage planetary gear shafts.

[0013] Since the exposed or protruding portion of the outer gear shaft is inserted into the axial hole, this exposed portion of the outer gear shaft may hereinafter be more simply referred to as a "planetary shaft insert", "shaft insert", or "axial insert".

[0014] According to the present invention, a method of connecting a low-speed shaft of a driveline to a planetary gear set of the driveline includes the steps of: providing outer gear shafts in an annular arrangement, wherein each outer gear shaft of the first stage has an exposed portion protruding from the carrier; forming an annular arrangement of axial holes around the low-speed shaft, wherein each axial hole is arranged to receive a planetary shaft insert; inserting each planetary shaft insert into a corresponding axial hole; and establishing an interference fit between each axial insert and the corresponding axial hole.

[0015] The present invention also describes a wind turbine driveline that includes a low-speed assembly having a low-speed or input shaft, a planetary gear set, and a generator assembly having a high-speed output or "torque shaft". The wind turbine driveline also includes an embodiment of the mounting arrangement of the present invention between the input shaft and the planetary gear set. The terms "main shaft", "low-speed shaft", and "input shaft" may be used interchangeably herein. Similarly, the terms "torque shaft", "generator shaft", and "output shaft" may be used interchangeably.

[0016] Particularly advantageous embodiments and features of the present invention are given by the dependent claims, as disclosed in the following description. Features of different claim categories may be combined as appropriate to give additional embodiments not described herein.

[0017] As used in the context of the present invention, the term "axial" should be understood to mean "parallel to the main axis of the driveline", i.e., parallel to the common axis of rotation of the input shaft, sun gear, and output shaft.

[0018] In the following, it may be assumed that the wind turbine is a horizontal-axis wind turbine. Without restricting the invention in any way, it may be assumed that the aerodynamic rotor of the wind turbine has a diameter of approximately 180 m - 240 m or even larger. The aerodynamic rotor of the wind turbine is connected to the front end or "drive end" of the low-speed shaft. The planetary gear set is dimensioned accordingly and may include several stages. For example, the gearbox may be implemented as a single-stage planetary gear set with three planetary gears. In another example, the gearbox may be implemented as a three-stage planetary gear set having seven planetary gears in the first stage, five planetary gears in the second stage, and three planetary gears in the third stage.

[0019] The axial hole may be formed as a dedicated annular structure that is mounted around the rear end of the low-speed shaft as a flange. For optimal torque transmission, this connection must be very firm so that these parts act as a single physical entity. However, manufacturing such a component may be associated with considerable expense. Thus, in a particularly preferred embodiment of the invention, the annular arrangement of the axial hole is formed in a rear flange that has already been formed as part of the low-speed shaft. This approach may be more suitable when the design of the low-speed shaft already includes a rear flange for the purpose of holding the rear bearing and / or for providing a seal for the bearing lubricant. Similarly, the input shaft of the low-speed assembly may already have a rear flange for connection to an intermediate structure or a prior art connector assembly: in such a case, instead of such an intermediate structure, this flange is reused as described herein to support the planetary shaft in its annular configuration.

[0020] In a large wind turbine as described above, at the interface between the input shaft and the gearbox, the diameter of the input shaft flange may be approximately 1.5 m - 2 m, and the diameter of the exposed portion of the first-stage planetary shaft may be approximately 200 mm - 300 mm. However, it should be noted that these exemplary dimensions are used to describe the type of drive train in which the invention may be advantageously configured.

[0021] During the assembly phase, by pushing the gearbox in the direction of the low-speed shaft (or vice versa), the annular structure of the exposed peripheral gear shaft portion is inserted into the corresponding annular arrangement of the axial hole. In an interference fit (also known as a "friction fit" or "press fit"), the mating parts fit closely together to obtain a joint that is maintained by friction once the parts are pushed together.

[0022] In a preferred embodiment of the invention, the diameter of the axial hole substantially corresponds to the diameter of the corresponding planetary shaft insert, i.e., the diameter of the axial hole is understood to be at most only slightly larger than the diameter of the shaft insert. The diameter of the axial hole may even be slightly smaller than the diameter of the corresponding planetary shaft insert.

[0023] In any such embodiment, it may be difficult to push all the planetary shaft inserts into the axial holes simultaneously. Thus, in another preferred embodiment of the present invention, the outer end of each exposed portion is provided with an annular chamfer, which facilitates the entry of the shaft insert into the axial hole. Any suitable technique, such as plastic deformation, thermal assembly (cooling or heating the parts), etc., can be employed to assist in the assembly of the input shaft and the planetary gear set. The entry of the insert into the axial hole can be further facilitated by a dry lubricant (e.g., molybdenum disulfide, graphite, etc.) or by a film of grease or oil.

[0024] In a particularly preferred embodiment of the present invention, the diameter of the axial hole exceeds the diameter of its planetary shaft insert. The difference in diameter can be up to 100 mm, or may be smaller, for example 40 mm. Since the axial insert and the axial hole are assumed to share a longitudinal axis, there is a space between the axial hole and the axial insert. The interference fit can be achieved in a variety of ways. In a preferred embodiment of the present invention, the connector assembly includes a cylindrical sleeve between such an axial hole and its insert. Preferably, the wall thickness of the sleeve is chosen such that the sleeve fills the space between the axial hole and the axial insert. In the examples given above, when the difference in diameter is 100 mm, a sleeve wall thickness of 50 mm is appropriate; when the difference in diameter is 40 mm, a sleeve wall thickness of 20 mm is appropriate. During the assembly process, by pushing the gearbox in the direction of the low-speed shaft (or vice versa), the annular structure of the exposed peripheral gear shaft portion is inserted into the corresponding annular arrangement structure of the axial hole. Subsequently, the cylindrical sleeve is inserted into the space between each axial hole and the insert. To assist in this step, the cylindrical sleeve may include an axial slit extending from one end to the other end. Here, the assembly can also be facilitated by a suitable lubricant between the sleeve and the axial hole and / or between the insert and the sleeve.

[0025] In the above embodiments, the axial insert is assumed to be of a cylindrical shape. Each exposed portion of the peripheral gear shaft can simply be an extension of the gear shaft, i.e., the gear shaft has the same diameter along its length. Preferably, the exposed portion of the first-stage planetary gear shaft can have a smaller diameter, for example a diameter of approximately 200 mm - 300 mm, such that the axial hole diameter does not need to be too large.

[0026] During operation of the wind turbine, external load forms such as vibrations may be transmitted from the aerodynamic rotor to the input shaft. In order to prevent such vibrations from loosening the interference fit and causing axial displacement of the gearbox, the present invention preferably includes axial fixing means to prevent axial displacement of the planetary gear set relative to the input shaft. In one possible embodiment, an annular arrangement of fasteners may be used, wherein each fastener extends through the input shaft flange and the first stage carrier frame in an axial direction. One or more fasteners may be arranged in the space between any two adjacent shaft inserts. Such fasteners may provide additional "stiffness" to the connection between the input shaft and the planetary gear set.

[0027] In another preferred embodiment of the invention, the planet shaft insert is long enough to extend a certain distance beyond the axial bore, and the axial securing means utilizes the outer end of the axial insert present on the upwind side of the rear flange of the low speed shaft or on the side facing the hub. For example, a through hole may be formed along the diameter of the outer end of the shaft insert just beside the low speed shaft flange, and a close fitting pin or rod may be pushed into the through hole. The axial securing means as described above may be configured to supplement the connection between the input shaft and the planetary gear set.

[0028] In a particularly preferred embodiment, the outer end of the axial insert is threaded to match the threads of a suitable nut, for example a DIN 981 slotted nut, such as a KM40 nut, a KMT40 nut, etc. After the gearbox and input shaft are pushed together and the interference fit is achieved, a nut is screwed onto the outer end of each axial insert. To assist in this step, an access opening may be provided in the housing of the spindle assembly. The input shaft may be rotated to bring the outer end of the axial insert into a favorable position. The technician then places the nut onto the outer end and applies sufficient torque to tighten it. The input shaft is then rotated a sufficient amount to position the outer end of the next axial insert, and so on. During this assembly stage, additional fasteners as described above may be used to hold the input shaft and gearbox together while the locking nut is screwed onto the axial insert.

[0029] Instead of a conventional first stage planet carrier, which must hold the planet gear shafts in the required annular configuration as described above, the gearbox can be equipped with a simple first stage cover having a circular opening shaped to fit around the protruding extensions of the planet gear shafts. In this case, the purpose of such a cover is to seal the gearbox against dust and moisture, for example during testing and / or transport phases. In another preferred embodiment of the invention, the input shaft can be closed by a plate which also serves to cover the front end of the first stage of the gearbox. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for the purpose of illustration and not as a definition of the limits of the present invention.

[0031] Figure 1 shows a simplified schematic view of a wind turbine drivetrain;

[0032] Figure 2 illustrates an embodiment of the connector assembly of the present invention;

[0033] Figure 3 shows a simplified exploded view of an embodiment of the connector assembly of the present invention;

[0034] Figures 4 - 6 shows various possible interference fit connections in an embodiment of the connector assembly of the present invention;

[0035] Figure 7 shows a prior art drivetrain.

[0036] In the drawings, like reference numerals throughout the drawings indicate like elements. The elements in the drawings are not necessarily drawn to scale. Detailed Description

[0037] Figure 1 is a simplified schematic view of a wind turbine 5, which shows the main components of its drivetrain: the aerodynamic rotor 50 is arranged to rotate the low-speed shaft 20 or the main shaft 20; the main shaft 20 is connected to a multi-stage gearbox 3, and the last stage of the gearbox 3 is connected to the high-speed shaft 40 of the generator 4. The purpose of the gearbox 4 is to transfer torque from the main shaft 20 to the generator shaft 40 while converting the low speed of the main shaft 20 into a higher speed of the generator shaft 40. One goal of drivetrain design is to minimize torque losses. External loads are transferred from the drivetrain components through various support structures (only very basically shown) to the seat plate 510 of the nacelle 51, and from there into the tower 52 and forward into the foundation.

[0038] Figure 2 is a cross-sectional view of the drivetrain of an exemplary embodiment, which shows the low-speed component 2 and the gearbox 3. The low-speed component 2 includes a main shaft 20 rotated by the aerodynamic rotor of the wind turbine. The main shaft 20 is supported by a rigid housing 21 and bearings 221, 222 at each end of the housing 21.

[0039] At the hub end of the main shaft 20, a front flange 201 is formed to connect the shaft 20 to the hub of the aerodynamic rotor. At the other end, a rear flange 202 is formed for connection to the gearbox 3.

[0040] Here, the gearbox 3 is a three-stage planetary gear train. In this exemplary embodiment, the first gearbox stage 31 is configured with seven planetary gears 31P around its sun gear 31C; the second gearbox stage 32 is configured with six planetary gears 32P around its sun gear 32C; and the third gearbox stage 33 is configured with three planetary gears 33P around its sun gear 33C. In a construction familiar to those skilled in the art, each stage includes a ring gear such that the teeth of the planetary gears mesh with the teeth of the ring gear and also with the teeth of the sun gear. Of course, various configurations of such planetary gear sets are possible. For example, the number of planetary gears in the first stage 31 can be determined by the diameter of the main shaft 20, which in turn is determined by the size of the pneumatic rotor.

[0041] Each first-stage planetary gear 31P includes a shaft 310 that is formed to include a portion 11 that projects "backward" from the front or drive end of the gearbox 3. In the connector assembly 1 of the present invention, these projecting portions 11 or axial inserts 11 extend through axial holes 10 formed in the rear flange 202 of the main shaft 20. The figure clearly shows the axial inserts 11 of the first-stage planetary gear shafts extending through the axial holes 10. The diameter 10D of the axial holes 10 is substantially the same as the diameter 11D of the axial inserts 11 of the first-stage planetary shafts 310 to achieve an interference fit 1 between the axial inserts 11 and the axial holes 10. With this connection, torque is directly transmitted from the main shaft 20 to the first stage 31 of the planetary gear train 3. By directly mounting the first-stage planetary shafts 310 to the rear flange 202 of the main shaft 20, the present invention maximizes the amount of torque transmitted from the main shaft 20 to the gearbox 3, thereby optimizing torque transmission in this part of the drivetrain. In fact, the flange 202 of the input shaft 20 serves as a carrier frame for the first-stage planetary gears 31P.

[0042] In this exemplary embodiment, the cover plate 24 closes the end of the input shaft 20 and also serves as a cover plate for the first stage 31 of the planetary gear set 3. The figure also indicates an access opening 210 in the housing 21 of the low-speed assembly, which is provided to provide access to the axial inserts 11 during the assembly and disassembly phases.

[0043] Figure 3 Shows Figure 2 A simplified exploded view of the drivetrain assembly of the present invention. The figure shows the front end of the main shaft 20 and the gearbox 3 in an assembled or disassembled stage. Here, the first stage of the gearbox has seven planetary gears, and each planetary gear shaft 310 is manufactured to have a portion 11 that extends through a circular opening in the cover plate 313, as shown here. Instead of or in addition to the above Figure 2The cover plate 24 described in [[ ]] can be configured as cover plate 313. Of course, cover plate 313 can be implemented in substantially the same manner as the carrier frame of a conventional planetary gear set without necessarily implementing the functions of the carrier frame. For clarity, other details of the gearbox are not shown.

[0044] This figure shows an annular arrangement of equally spaced axial holes 10 formed in the rear flange 202 of the low-speed shaft 20. Each axial hole 10 is arranged to receive an axial insert 11 of the first-stage planetary shaft 310, that is, seven axial holes 10 are equally spaced to receive seven axial inserts 11 protruding from the gearbox 3.

[0045] To assemble the mounting arrangement 1 of the present invention, seven axial inserts 11 are inserted into the axial holes 10 of the rear flange 202. An interference fit between the axial holes 10 and the axial inserts 11 can be established in various ways. The annular arrangement of additional fasteners 16 (only one is shown here for clarity) inserted through the matching holes 160, 161 in the input shaft flange 20 and the cover plate 313 can assist in the assembly of the driveline.

[0046] Figure 4 An exemplary embodiment is shown in which an interference fit is formed between the cylindrical surfaces of the axial insert 11 and the axial hole 10, that is, the diameter 10D of the axial hole 10 and the diameter 11D of the axial insert 11 are substantially the same (the diameter 11D of the axial insert 11 can even slightly exceed the diameter 10D of the axial hole 10). Here, each axial insert 11 has a threaded outer end 110 and a chamfer 12. The chamfer 12 helps the axial insert 11 to pass through the axial hole 10. Since the axial insert diameter 11D is substantially the same as the axial hole diameter 10D, the axial insert 11 can be easily passed through the axial hole 10 with a suitable lubricant as explained above. Once the axial insert 11 is pushed through to the far side of the flange 202, a nut 14 is screwed onto the outer end 110 of each axial insert 11, and sufficient torque is applied to tighten the nut 14 to complete the assembly. The purpose of the nut 14 is to prevent displacement in the axial direction during the operation of the driveline. The interference fit 1 between the flange 202 and the axial insert 11 of the first-stage planetary shaft 310 is used to transfer substantially all of the torque from the main shaft 20 to the first stage 31 of the gearbox 3.

[0047] Figure 5Another exemplary embodiment is shown, in which the interference fit 1 is formed by a sleeve 15 placed between the axial insert 11 and the corresponding axial hole 10. Here, the diameter 10D of the axial hole 10 is larger than the diameter 11D of the axial insert 11, and this diameter difference is compensated for by the wall thickness of the cylindrical sleeve 15. Here, the sleeve 15 may have a longitudinal slit to facilitate insertion between the axial insert 11 and the axial hole 10. In this embodiment, the sleeve 15 may be chamfered at both axial inserts to further facilitate the assembly process.

[0048] In this case, the outer end 110 of each axial insert 11 is also threaded. As explained above Figure 4 Once the outer end 110 of the axial insert 11 has been pushed past the distal side of the flange 202, a nut 14 is screwed onto each outer end 110 and sufficient torque is applied to tighten the nut 14, thus completing the assembly.

[0049] Figure 6 Another exemplary embodiment is shown, in which the axial insert 11 is tapered. Here, the diameter 10D of the axial hole 10 may be much larger than the smallest diameter 11D of the tapered axial insert 11. Pushing the gearbox and the low-speed shaft together is relatively simple. In this embodiment, the interference fit 1 is formed by a tapered sleeve 15 placed between each tapered axial insert 11 and the corresponding axial hole 10. Here, the space between the axial hole 10 and the axial insert 11 is compensated for by the tapered sleeve 15. In this embodiment, an axial stop is established by a pin 13 or a rod 13 extending diametrically through the outer end 110 of the axial insert 11.

[0050] FIG. 7 shows a part of a prior art wind turbine drive train, which includes a planetary gear set 73 between a low-speed component 72 and a high-speed component 74. In a conventional manner, the front end of the planetary gear set 73 includes a rotating carrier frame 730 to support the annular arrangement of the peripheral gear shafts 731. Here, the low-speed shaft 720 and the front-end planet carrier 730 are coupled by an intermediate member 70. However, as explained in the introduction, the intermediate member 70 between the low-speed shaft 720 and the planetary gear set 73 causes some torque losses. In addition, the necessary maintenance and repair routines for the intermediate member 70 also increase the total energy cost.

[0051] Although the present invention has been disclosed in the form of preferred embodiments and variations thereof, it will be understood that many additional modifications and variations can be made thereto without departing from the scope of the present invention.

[0052] For the sake of clarity, it is to be understood that the use of "a", "an", or "one" throughout this application does not exclude a plurality, and "comprising" does not exclude other steps or elements.

Claims

1. A connector assembly (1) for a driveline (2, 3, 4), the driveline including at least a low-speed shaft (20) and a planetary gear set (3), the planetary gear set including an annular arrangement of outer gears (31P), the connector assembly including: - A portion (11) of each first-stage outer gear shaft (310) arranged to project from the drive end of the planetary gear set (3); - An annular arrangement structure of axial holes (10) formed around the low-speed shaft (20), wherein each axial hole (10) is arranged to receive the projecting portion (11) of the outer gear shaft (310); and wherein, - The dimensions of each axial hole (10) and the corresponding projecting portion (11) of the outer gear shaft (31P) are set to establish an interference fit.

2. The connector assembly according to the preceding claim, wherein, The annular arrangement structure of the axial holes (10) is formed in the flange (202) of the low-speed shaft (20).

3. The connector assembly according to any one of the preceding claims, wherein, The diameter (10D) of the axial hole (10) exceeds the diameter (11D) of the projecting portion (11) of the outer gear shaft (31P) by at most 60 mm, more preferably at most 40 mm.

4. The connector assembly according to any one of the preceding claims, including a cylindrical sleeve (15) between an axial hole (10) and a corresponding projection (11) of the outer gear shaft (31P).

5. The connector assembly according to any one of the preceding claims, wherein, The cylindrical sleeve (15) includes an axial slit extending along the length of the sleeve (15).

6. The connector assembly according to any one of the preceding claims, wherein, The diameter (10D) of the axial hole (10) substantially corresponds to the diameter (11D) of the projecting portion (11) of the outer gear shaft (31P).

7. The connector assembly according to any one of the preceding claims, including an annular chamfer (12) around a projection (11) of the outer gear shaft (31P).

8. The connector assembly according to any one of the preceding claims, including axial fixing means (13, 14) adapted to prevent axial displacement of the planetary gear set (3) relative to the low-speed shaft (20).

9. The connector assembly according to any one of the preceding claims, wherein, The axial fixing means includes a threaded connection between each projecting portion (11) and a complementary nut (14).

10. The connector assembly according to any one of the preceding claims, including a plurality of fasteners (16) between the low-speed shaft (20) and a housing (313) of the planetary gear set (3), wherein, The fastener (16) is arranged in the space between two adjacent outer gear shafts (31P).

11. A wind turbine driveline (2, 3, 4), including: - A low-speed assembly (2); - A planetary gear set (3) driven by the low-speed shaft (20) of the low-speed assembly (2); and - A generator assembly (4) driven by the output shaft (33C) of the planetary gear set (3); characterized in that, - A connector assembly (1) according to any one of claims 1 to 10, which connects the low-speed shaft (20) and the planetary gear set (3) by an interference fit.

12. The wind turbine driveline according to the preceding claim, wherein, The planetary gear set (3) includes a plurality of stages (31, 32, 33).

13. The wind turbine drive train according to claim 11 or claim 12, wherein, The first stage (31) of the planetary gear set (3) includes at least three outer gears (31P), more preferably at least five outer gears (31P), each of the outer gears having a projecting portion (11) extending in the direction of the low-speed assembly (2).

14. A method of connecting a low speed shaft (20) of a drive train (2, 3, 4) to a planetary gear set (3), the planetary gear set (3) including an annular arrangement of a first stage outer gear (31P), the method including the steps of: - Arranging a portion (11) of each outer gear shaft (310) to project from the drive end of the planetary gear set (3); - Forming an annular arrangement structure of axial holes (10) around the low-speed shaft (20), wherein each axial hole (10) is arranged to receive the projecting portion (11) of the outer gear shaft (310); - Inserting each projecting portion (11) into the corresponding axial hole (10); and - Forming an interference fit between each projecting portion (11) and the corresponding axial hole (10).

15. The method according to the previous claim, including the steps of: The connection is enhanced by means (13, 14) for preventing axial displacement of the planetary gear set (3) relative to the low-speed shaft (20).

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