Powertrain components

Abstract

The present invention describes a driveline component, comprising: a rotor shaft; a bearing unit mounted around the rotor shaft; and another driveline component connected to an end of the rotor shaft, wherein an annular face of the another driveline component is arranged opposite to an annular face of the bearing unit, with a distance between the annular faces. The driveline component is characterized by an annular arrangement of threaded holes formed in a first annular face of two opposite annular faces; a plurality of bolts, wherein each bolt comprises a bolt shaft threadedly connected to the threaded hole, a lock nut threadedly connected to the bolt shaft and fastened against the first annular face; and a bolt head arranged to contact a second one of the two opposite annular faces. The present invention also describes a wind turbine comprising such a driveline component; and a method of assembling such a driveline.

Description

Field of the Invention

[0001] The present invention describes a drivetrain component, a wind turbine including such a drivetrain component, and a method of assembling such a drivetrain. Background Art

[0002] The drivetrain of a wind turbine includes an aerodynamic rotor with rotor blades that convert wind energy into rotational movement of a hub and a rotor shaft. The rotating shaft rotates the rotor of an electric machine, thereby generating electrical power.

[0003] Large bearings are required between the rotor shaft and a fixed support structure. The inner ring of the bearing is typically connected to the rotating shaft by means of a press fit, also known as a friction fit or an interference fit. During operation of the wind turbine, the bearing is subjected to very large axial loads, especially in the "downstream" direction. To prevent damage to the bearing, the rotating shaft, and other drivetrain components, it is crucial to prevent axial displacement of the bearing assembly.

[0004] One way to do this is to close any gap between the bearing assembly and the next immovable component, such as closing the gap between the bearing assembly and the gearbox. This can be done in a variety of ways. In one method, a tightly fitting ring is placed around the shaft between the bearing assembly and the gearbox. The width of the ring is the same as the width of the gap between the bearing assembly and the gearbox, so that it can prevent the bearing assembly from shifting in the "downstream" direction, i.e., towards the gearbox. However, if the inner diameter of such a form-fitting ring is even slightly smaller than expected, it may be difficult to install such a form-fitting ring. In another method, the rotating shaft is machined to have an external thread, and the ring is machined to have a matching internal thread. The ring is then threaded onto the shaft. In this case, the width of the ring is also the same as the width of the gap between the bearing assembly and the gearbox. Although the threaded ring can be easier to install than the form-fitting ring, the manufacturing cost is significantly higher.

[0005] Accordingly, it is an object of the present invention to provide a more economical way to axially fix the position of a bearing assembly on a rotating shaft. Summary of the Invention

[0006] This object is achieved by a drivetrain component according to the present disclosure; by a wind turbine according to the present disclosure; and by a method of assembling a drivetrain according to the present disclosure.

[0007] According to the present invention, the driveline assembly comprises: a rotor shaft; a bearing unit mounted around the rotor shaft; and another driveline component connected to an end of the rotor shaft, wherein an annular face of the another driveline component is arranged to face an annular face of the bearing unit, with a substantially uniform distance therebetween. The driveline assembly of the present invention is characterized by a load transfer bridge comprising an annular arrangement of bolts, which prevents axial displacement of the bearing unit during operation of the driveline. For this purpose, the driveline assembly of the present invention comprises an annular arrangement of axial threaded holes formed in one of the opposing annular faces. Each of the plurality of bolts comprises a threaded bolt shaft, which is inserted into the threaded hole over a part of its length. Each bolt is provided with a lock nut, which is fastened against the annular face containing the threaded hole. The bolt head of each bolt is arranged to contact the another annular face.

[0008] The term "axial" should be understood as relating to the axis of the driveline shaft, and thus the expression "axial threaded hole" means that the threaded hole extends in the same direction as the rotational axis of the driveline shaft, i.e., the threaded hole is parallel to the surface of the driveline shaft. It can thus be seen that the longitudinal axis of the bolt is also substantially parallel to the rotational axis.

[0009] An advantage of the driveline assembly of the present invention is that axial displacement of the bearing unit can be prevented in an advantageous and economical manner. There is no need to provide expensive precision-machined rings. Instead, the present invention can be implemented with readily available threaded bolts and lock nuts, and it is also easy to form threaded or tapped holes. The bolts threaded into the threaded holes can be referred to as machine screws. Such fasteners can be easily obtained in a wide range of standard sizes, and the corresponding tools for forming the threaded holes are also readily available.

[0010] Since the bolts are firmly anchored at one end (e.g., in the threaded holes formed in the bearing unit) and the bolt heads physically contact the another annular face (e.g., the face of the another driveline component), the axial forces acting on the bearing unit are effectively transferred between the opposing faces, such that the position of the bearing unit will remain fixed during operation of the driveline. Thus, the bolts serve as a "load transfer bridge" between the bearing unit and the another driveline component. It should be understood hereinafter that the bolts extend between components that rotate integrally with the rotor shaft during operation of the driveline.

[0011] An embodiment of a wind turbine of the present invention comprises such a driveline assembly. Since there is no need to provide expensive machining rings to inhibit axial displacement of the bearing unit and the assembly of the driveline is simpler, the total production cost of such a wind turbine can be advantageously reduced.

[0012] According to the invention, such a drive train is assembled or manufactured as follows: A bearing unit is mounted around a rotor shaft, and another drive train component is mounted to the non-driven end of the rotor shaft such that an annular face of the another drive train component is spaced apart from an opposing annular face of the bearing unit by a distance. The method according to the invention is characterized in a prior step of forming an annular arrangement of threaded holes in the first annular face and providing a corresponding number of threaded bolts or machine screws. A lock nut is threadedly connected to each bolt shaft, and each bolt is threadedly connected to one of the threaded holes. These steps are preferably carried out before mounting the another drive train component to the rotor shaft. At this stage, the exposed length of the bolts can be adjusted to be less than the distance between the opposing annular faces. After mounting the another drive train component to the rotor shaft, the bolts are rotated such that each bolt head abuts against the second annular face. Then, the lock nut is tightened against the first annular face.

[0013] Advantages of the method according to the invention are the low cost of providing the threaded holes and the fasteners; another advantage is the effectiveness of the load transfer bridge formed by the bolts extending between the bearing unit and the another drive train component.

[0014] Particularly advantageous embodiments and features of the invention are given by the dependent claims, as disclosed in the following description. Features of different claim categories can be combined appropriately to give other embodiments not described herein.

[0015] In the following, it can be assumed that the drive train assembly is part of a wind turbine, i.e., the rotor shaft is rotated by an aerodynamic rotor (rotor blades and hub). In the following, without restricting the invention in any way, it can be assumed that such a wind turbine is implemented as a geared wind turbine, and the another drive train component is a rotating component of a gearbox unit. The step of rotating the bolts and / or the step of tightening the lock nuts can be carried out after mounting the drive train in the nacelle of the wind turbine.

[0016] The rotor shaft of a drive train or power train can be considered to have a "driven end" and a "non-driven end". In the case of a wind turbine, the driven end is rotated by the aerodynamic rotor. In a geared wind turbine, the non-driven end of the rotor shaft is connected to the gearbox unit. In the following, when referring to the direction of the driven end, the terms "upwind" and "upstream" can be used, while when referring to the direction of the non-driven end, the terms "downwind" and "downstream" can be used.

[0017] Although the threaded holes can be formed in the bearing unit or another driveline component, for simplicity, it should be assumed hereinafter that the threaded holes are formed in the bearing unit and the bolt head will contact the annular face of another driveline component. Additionally, it should be assumed that the threaded holes are formed within the rotating housing portion of the bearing unit and the bolt head will contact the annular face of the rotating gearbox flange. Preferably, the threaded holes are equidistantly spaced around the rotating housing portion of the bearing unit.

[0018] The term "fully extended bolt" is used herein to refer to such a bolt that has been rotated so that its bolt head bears against the gearbox flange and its lock nut has been tightened against the rotating housing portion of the bearing unit.

[0019] The depth of the threaded holes will depend on the material thickness of the bearing unit housing. The length of the bolt preferably includes the clearance width (between the opposing faces of the bearing unit and the gearbox flange) plus most of the threaded hole depth, rather than the entire depth, to facilitate the assembly of the driveline. For example, the bolt length can include the clearance length plus 90% of the threaded hole depth.

[0020] Preferably, during the final assembly stage of the driveline, each bolt head is rotated, for example using a torque wrench, so that its outer surface firmly bears against the annular face of the gearbox flange. The contact area between the bolt head and the annular face can be optimized by using a suitable large number of bolts and / or by selecting bolts with advantageously large bolt heads.

[0021] In another preferred embodiment of the present invention, the rotor shaft is formed to include an outer annular ridge in the upwind direction of the bearing unit to prevent axial displacement of the bearing unit in the upstream direction during the operation of the driveline.

[0022] For example, in a 5MW wind turbine, the inner diameter of the bearing unit can be on the order of 900mm - 1300mm. For such a wind turbine with an embodiment of the driveline assembly of the present invention, the load transfer bridge preferably includes 10 - 16 bolts arranged in an annular pattern bridging the gap between the bearing unit and the gearbox flange. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. However, it should be understood that the drawings are designed solely for the purpose of illustration and not as a definition of the limitations of the present invention.

[0024] Figure 1 An embodiment of the driveline assembly of the present invention is shown;

[0025] Figure 2 Shows Figure 1 a more detailed view of the load transfer bridge;

[0026] Figure 3 shows a stage during the assembly of the Figure 1 powertrain;

[0027] Figure 4 shows Figure 1 another stage during the assembly of the

[0028] Figure 5 powertrain; shows an alternative implementation of the powertrain component of the present invention;

[0029] Figure 6 shows a powertrain component of the prior art;

[0030] Figure 7 shows another powertrain component of the prior art.

[0031] In the drawings, the same reference numerals always denote the same objects. The objects in the figures are not necessarily drawn to scale. DETAILED DESCRIPTION

[0032] Figure 1 shows a cross-section through a relevant area of a wind turbine powertrain, showing details of the junction between the rotor shaft 2 and the gearbox unit 4. The gearbox unit 4 is mounted to the rotor shaft 2 by bolts (not shown). The figure shows a bearing unit 3 in a suitable position around the shaft 2. The bearing unit 3 includes a fixed outer ring 31R and a housing body part 31, and a rotating inner ring 30R and an inner housing part 30. In this exemplary embodiment, the bearing unit 3 is configured as a double-row spherical roller bearing.

[0033] The interference fit between the bearing unit 3 and the rotor shaft 2 ensures that the inner ring 30R and the inner housing part 30 move as a single entity with the rotating shaft 2. The fixed housing body part 31 of the bearing unit 3 can be connected to another fixed part, such as to a base frame or to a nacelle for example.

[0034] During the operation of the wind turbine, the bearing unit 3 is subjected to various types of loads and care must be taken to prevent axial displacement. The figure shows an annular protrusion at the upwind side of the bearing unit 3, which is used to prevent axial displacement of the bearing unit in the upwind direction. However, the significant forces acting on the bearing unit 3 are mainly in the downwind direction (indicated by the arrow pointing to the right). The displacement of the bearing unit 3 is prevented by the powertrain component of the present invention shown herein. The load transfer bridge 1 is provided in the form of an annular arrangement of bolts 11 that extend into threaded holes 10 formed in the inner housing 30 of the bearing unit 3 on the downwind side. The bolts 11 are threaded along their length and each bolt 11 carries a lock nut 12. The bolt heads 11H are pressed against the annular face 40F of the gearbox flange 40 of the gearbox unit 4.

[0035] During the installation process, the position of each bolt 11 is fixed as follows: After the bearing unit 3 is arranged in place on the rotor shaft 2, as Figure 2 shown, the bolts 11 (each carrying a lock nut 12) are threaded into the threaded holes 10 such that the exposed bolt length is shorter than the clearance D between the bearing unit 3 and the (not yet installed) gearbox flange 40. Each bolt 11 is turned into its threaded hole 10 so as not to interfere with the subsequent steps of installing the gearbox flange.

[0036] The length of the bolt 11 can be determined by the distance D to be bridged between the opposing faces 30F, 40F plus 80% - 90% of the depth of its threaded hole 10.

[0037] Figure 3 A perspective view of the partial assembly is shown, in which fourteen such bolts 11 are positioned for insertion into fourteen threaded holes 10 spaced equidistantly around the bearing housing 30.

[0038] The gearbox unit is then installed by connecting the gearbox flange 40 to the non-driven end of the rotor shaft 2. Once the gearbox flange 40 is connected to the rotor shaft 2, each bolt 11 is turned until its head 11H bears against the gearbox flange surface 40F. The bolt 11 can be turned to a torque of several Nm so as to actively press the bolt head 11H against the flange surface 40F. The lock nuts 12 are then turned to fasten them against the surface 30F of the bearing housing 30. This stage is shown in Figure 4 By means of the bolts 11 constructed in this way, a load transfer bridge 1 is formed to prevent axial displacement of the bearing unit 3 in the downwind direction (indicated by the arrow pointing to the right).

[0039] During the maintenance process, the bolts 11 and the lock nuts 12 can be turned appropriately (loosened or tightened) to compensate for any change in the clearance between the bearing unit 3 and the gearbox flange 40.

[0040] Figure 5 An alternative embodiment of the load transfer bridge 1 of the present invention is shown, in which the threaded holes 10 are formed in the gearbox flange 40 and the bolt head 11H bears against the annular face 30F of the inner bearing housing part 30.

[0041] Figure 6 and Figure 7 each show prior art methods of preventing axial displacement of a bearing assembly. Similar to the structure explained above in Figures 1 - 5 this figure shows the rotor shaft 2 of a wind turbine with a bearing unit 3 in place. In Figure 6In [description], the axial displacement of the bearing unit 3 is prevented by a form-fitting ring 60 arranged around the rotor shaft 2. Since the inner diameter of the ring 60 should ideally be the same as the outer diameter of the shaft 2, it may be very difficult to mount the thin ring 60 onto the large rotor shaft 2. In Figure 7 In [description], the axial displacement of the bearing unit 3 is prevented by a threaded ring 70 arranged around the rotor shaft 2. The large external thread of the rotor shaft 2 and the large internal thread of the ring 70 must be machined to high precision, requiring expensive tools and significantly increasing the total cost.

[0042] Although the invention has been disclosed in the form of preferred embodiments and their variations, it will be understood that many additional modifications and variations can be made thereto without departing from the scope of the invention. For example, although the invention has been described using the example of a wind turbine drivetrain, the load transfer bridge formed by bolts and threaded holes can be implemented in other types of drivetrains in which the axial displacement of the bearing unit is prevented.

[0043] For the sake of clarity, it should be understood that the use of "a" or "an" throughout this application does not exclude a plurality, and "comprising" does not exclude other steps or elements.

Claims

1. A drive train component, comprising: - a rotor shaft (2); - a bearing unit (3) mounted around the rotor shaft (2); - another drive train component (40) connected to an end of the rotor shaft (2), wherein an annular face (40F) of the another drive train component (40) is arranged to face an annular face (30F) of the bearing unit (3), with a distance (D) between the two opposing annular faces (30F, 40F); Characterized in that - an annular arrangement of threaded holes (10) formed in a first annular face which is one of the two opposing annular faces (30F, 40F); - a plurality of bolts (11), wherein each bolt (11) includes a bolt shaft (11S) threadedly connected to the threaded hole (10), a lock nut (12) threadedly connected to the bolt shaft (11S) and fastened against the first annular face, and a bolt head (11H) arranged to contact a second annular face which is the other of the two opposing annular faces (30F, 40F).

2. The powertrain assembly according to claim 1, wherein, The bolt head (11H) is pressed against the second annular face.

3. The powertrain assembly according to claim 1 or 2, wherein, The bolt head (11H) includes a flat surface parallel to the second annular face.

4. The drive train assembly according to claim 1 or 2, wherein, The longitudinal axis (10A) of each threaded hole (10) is parallel to the rotational axis (2A) of the drive train component.

5. The driveline assembly according to claim 1 or 2, wherein, The threaded holes (10) are formed in an inner housing portion (30) of the bearing unit (3).

6. The powertrain assembly according to claim 1 or 2, wherein, The length of the bolt (11) is the sum of the distance (D) between the opposing annular faces (30F, 40F) and a part of the depth (10D) of the threaded hole (10).

7. The powertrain assembly according to claim 1 or 2, wherein, The threaded holes (10) are equally spaced apart.

8. The driveline assembly according to claim 1 or 2, wherein, The rotor shaft (2) includes means for preventing axial displacement of the bearing unit (3) towards the drive end of the rotor shaft (2).

9. A wind turbine, comprising a drive train component according to any one of claims 1 to 8.

10. The wind turbine according to claim 9, which is implemented as a gear-driven wind turbine.

11. The wind turbine according to claim 10, wherein, The annular arrangement of the bolts (11) extends between the bearing unit (3) and a flange of the gearbox unit (4).

12. The wind turbine according to any one of claims 9 to 11, wherein, The inner diameter of the bearing unit (3) is at least 200 mm.

13. The wind turbine according to any one of claims 9 to 11, comprising an annular arrangement of at least 4 threaded holes (10) in the first annular face.

14. The wind turbine according to claim 13, comprising an annular arrangement of at least 8 threaded holes (10) in the first annular face.

15. A method of assembling a drive train component according to any one of claims 1 to 8, the method comprising the steps of: - mounting a bearing unit (3) around a rotor shaft (2); - connecting another drive train component (40) to the rotor shaft (2) such that an annular face (40F) of the another drive train component (40) is spaced a distance (D) from an opposing annular face (30F) of the bearing unit (3); Characterized in that - a prior step of forming an annular arrangement of threaded holes (10) in the first annular face; - Provide a plurality of bolts (11), wherein each bolt (11) includes a bolt shaft (11S) and a bolt head (11H); - Thread a lock nut (12) onto each bolt shaft (11S); - Rotate each bolt (11) in the threaded hole (10) to press the bolt head (11H) of the bolt (11) against the second annular surface; - Fasten each lock nut (12) against the second annular surface.

16. The method according to claim 15, wherein, The drive train assembly is a wind turbine drive train assembly, and wherein the step of rotating the bolts (11) and / or the step of fastening the lock nuts (12) is performed after installing the drive train assembly in the nacelle of the wind turbine.

Images