Main bearing unit of a wind turbine

Abstract

The invention relates to a main bearing unit (1) of a wind turbine, the main bearing unit (1) being in the form of a plain bearing, wherein the outer bearing ring (2) of the plain bearing consists of a number of bearing segments (3, 4) which are arranged over the circumference of the outer bearing ring (2), and wherein the bearing segments (3, 4) have a bearing surface (5, 6) which is or can be set to a defined radial position (r1, r2). The aim of the invention is to develop a main bearing unit of a wind turbine in the form of a plain bearing in such a way that friction and thus wear during starting and stopping processes can be reduced. To achieve this aim, the bearing segments (3, 4) consist of a first group and a second group, and the bearing segments (3) of the first group are or can be set to a first radial position (r1) and the bearing segments (3) of the first group have a first elasticity in the radial direction (r), and the bearing segments (4) of the second group are or can be set to a second radial position (r2) which is different from the first radial position (r1) and the bearing segments (4) of the second group have a second elasticity in the radial direction (r) which is different from the first elasticity, the first radial position (r1) being greater than the second radial position (r2) and the first elasticity being greater than the second elasticity.

Description

[0001] Main bearing of a wind turbine

[0002] Description

[0003] Field of the invention

[0004] The invention relates to a main bearing of a wind turbine, wherein the main bearing is designed as a plain bearing, wherein the bearing outer ring of the plain bearing consists of a number of bearing segments which are arranged over the circumference of the bearing outer ring, and wherein the bearing segments have a bearing surface which is set or adjustable to a defined radial position.

[0005] A generic main bearing for a wind turbine is known from US 2020 / 0173425 A1.

[0006] When supporting the rotor of a wind turbine, hydrodynamic plain bearings are an attractive alternative to the frequently used rolling bearings. Such plain bearings allow bearing replacement on the tower without disassembling the rotor, which is very economically attractive. Another significant advantage of segmenting the bearing outer ring, especially for very large wind turbines, is that such plain bearings do not require very large forging and hardening facilities, and the segments are also easier to transport.

[0007] In the previously mentioned solution, the individual bearing segments of the outer ring are designed with regard to the expected maximum load and fixed in the position required by the design.

[0008] Low load conditions are not specifically considered. A problem is that mixed friction occurs during start-up and stop-up processes with hydrodynamic plain bearings, which causes a certain amount of wear on the sliding linings of the plain bearing segments. Furthermore, this introduces relatively high frictional moments into the structure. At low wind speeds, a correspondingly high frictional moment in the plain bearing can prevent the wind turbine from starting.

[0009] Due to a highly variable load direction, the individual segments of the plain bearing are exposed to different loads and are sometimes not needed at all in certain load directions.

[0010] Various solutions for the design of a plain bearing are known from DE 10 2017 223 370 A1 , US 2011 / 0188988 A1 , US 2019 / 0195204 A1 and WO 2019 / 120870 A1.

[0011] Summary of the invention

[0012] The invention is based on the object of refining a main bearing of a wind turbine, designed as a plain bearing, in such a way that friction and thus wear during start-up and stop operations can be reduced. This should enable a longer service life for a bearing of this type.

[0013] The solution to this problem by the invention provides that the bearing segments consist of a first group and a second group, wherein the bearing segments of the first group are set or adjustable to a first radial position and wherein the bearing segments of the first group have a first spring elasticity in the radial direction and wherein the bearing segments of the second group are set or adjustable to a second radial position which is different from the first radial position, and wherein the bearing segments of the second group have a second spring elasticity in the radial direction which is different from the first spring elasticity, wherein the first radial position is greater than the second radial position and wherein the first spring elasticity is greater than the second spring elasticity.

[0014] The aforementioned radial positions refer to the radial position of the bearing surfaces of the bearing segments in order to accommodate the part to be supported, in particular the rotor of the wind turbine. A larger radial position means that the bearing surface of the bearing segment is arranged closer to the part to be supported, in particular the rotor of the wind turbine. In this respect, this refers to the radial distance of the bearing surface of the bearing segment from the housing part that accommodates the bearing outer ring.

[0015] Regarding spring elasticity, it should be noted that a high spring elasticity value results in a greater spring deflection (in the radial direction) when a force is applied (from the rotor). Therefore, a higher spring elasticity means that the spring constant or spring stiffness (measured in N / m) is lower than in the case of a lower spring elasticity.

[0016] The difference between the first radial position and the second radial position is preferably between 0.1 mm and 5.0 mm.

[0017] The first spring elasticity is preferably greater than the second spring elasticity by at least a factor of 3, preferably at least a factor of 5. Accordingly, the spring constant in the case of the first spring elasticity is smaller by at least a factor of 3, preferably at least a factor of 5, than the spring constant in the case of the second spring elasticity.

[0018] The bearing segments of the first group and the bearing segments of the second group are preferably arranged axially adjacent to one another. Alternatively, however, it is also possible for the bearing segments of the first group and the bearing segments of the second group to alternate in the circumferential direction. It can also be provided that a bearing segment of the first group is followed in the circumferential direction by more than one bearing segment of the second group (or vice versa).

[0019] At least the bearing segments of a group preferably each consist of a support element arranged on a component made of elastomer material, wherein the elastomer material component is secured to a housing part. In this case, the elasticity of at least one group of bearing segments is provided by the elastomer material component.

[0020] A particularly preferred embodiment of the invention provides that the bearing segments of the first group are provided with a fluid inlet to the bearing surface to create a hydrostatic bearing function. Accordingly, a hydrostatic bearing function is created, which ensures a virtually friction-free bearing arrangement starting from the rotor's standstill, thus preventing wear.

[0021] Friction and thus the wear that occurs during start-up and stop-stop processes can be significantly minimized by incorporating hydrostatic lubrication pockets into plain bearing segments. Plain bearing segments with hydrostatic lubrication pockets have a lower load-bearing capacity during normal operation of wind turbines than plain bearing segments without hydrostatic lubrication pockets. This is utilized very advantageously by combining hydrostatic and hydrodynamic lubrication pockets in the proposed design.

[0022] The bearing segments of the first group can be provided with adjustment means with which the first radial position can be changed. The adjustment means can comprise a hydraulic piston-cylinder system which is used for adjusting the first radial position. As a possible alternative, the adjustment means can also comprise a mechanical actuating system, in particular comprising a bucket tappet, which is used for adjusting the first radial position. With this configuration, it can be achieved that the bearing segments of the first group are retracted in their radial position towards the rotor once the engine has started up; this is particularly advantageous when the bearing segments of the first group are designed as hydrostatic elements.

[0023] The proposed hydrodynamic plain bearing thus has a load-controlled sliding surface. This creates a sliding surface that expands with increasing load, while the plain bearing segments with hydrostatic lubrication pockets—in addition to the plain bearing segments without hydrostatic lubrication pockets—ensure low wear during rotor start-up and deceleration.

[0024] Short description of the drawings

[0025] The drawings illustrate embodiments of the invention. They show:

[0026] Figure 1 shows a schematic sectional side view of a main bearing of a wind turbine according to a first embodiment of the invention, wherein only a part of the plain bearing used for the bearing is shown, and

[0027] Figure 2 shows a schematic sectional front view of the main bearing according to a second embodiment of the invention, wherein again only a part of the plain bearing used for the bearing is shown.

[0028] Detailed description of the drawings

[0029] Figure 1 shows the main bearing 1 of a wind turbine, which is designed as a plain bearing. Bearing segments 3, 4 are arranged in a housing part 11. These bearing segments form the outer bearing ring 2 and each have a bearing surface 5, 6. The bearing surfaces 5, 6 are located opposite the rotor of the wind turbine, specifically the shaft part 13, and support it. The bearing segments 3, 4 extend (not shown in Figure 1) around the entire circumference of the shaft part 13, so that the latter is fully supported.

[0030] Figure 1 shows that the bearing segments 3, 4 consist of two groups. The bearing segments 3 form a first group, and the bearing segments 4 form a second group. In the embodiment shown in Figure 1, the two groups 3, 4 are arranged next to each other in the axial direction a and are secured in the housing part 11.

[0031] It can also be seen that the surface of the bearing face 5, 6 is arranged in different radial positions in the two groups 3 and 4. In this respect, attention is initially drawn to the radial direction r, which is shown in Figure 1. In the case of bearing segments 3, i.e. in the case of the first group, there is a first radial position n, whereas in the case of bearing segments 4, i.e. in the case of the second group, there is a second radial position r2. The two radial positions n, r2 are to be understood from the perspective of the housing part 11, as can be seen from the designation shown for the two radial positions.

[0032] The first radial position n is larger than the second radial position r2. Accordingly, the surface of the bearing surface 5 is closer to the shaft part 13 than the surface of the bearing surface 6, which is slightly farther away from the shaft part 13.

[0033] It can also be seen that the bearing segments 3, 4 each consist of a support element 7 or 8, which can be provided in a conventional manner with a sliding layer in the area of ​​the bearing surface 5, 6. The support element 7, 8 is connected to a component 9 or 10, which is made of elastomer material and therefore has spring-elastic properties. By selecting a different radial height for the component 9, 10, it is achieved that the spring elasticity of the bearing segment 3 and that of the bearing segment 4 are different, whereby this is understood to mean the elasticity in the radial direction r. Since a component 9 is provided for the bearing segment 3, which has a greater extension in the radial direction r than in the case of the bearing segment 4, the bearing segment 3 has a first spring elasticity, which is greater than the second spring elasticity (for a definition in this regard, reference is made to the above explanations on the spring constant).

[0034] Thus, in the case of the embodiment shown in Figure 1, the main bearing assembly forms an axially split radial plain bearing. This consists of two groups of bearing segments 3, 4 (also referred to as pads), which are adjusted differently in their radial height and mounted with different levels of rigidity.

[0035] Bearing segment 3 is positioned higher (from the perspective of housing part 11), so it bears the load first when shaft part 13 exerts forces on bearing outer ring 2. Bearing segment 3 is mounted significantly more elastically than bearing segment 4. If the wind speed and, with it, the load, increases, bearing segment 3 consequently deflects until bearing segment 4 engages. This bearing segment is mounted less high but more rigidly and then bears the majority of the load.

[0036] The embodiment according to Figure 2 illustrates that instead of an axial offset of the bearing segments 3, 4, an offset in the circumferential direction U can also be provided. In Figure 2, only a total of three bearing segments are shown, namely one bearing segment 3 and two bearing segments 4, although, of course, bearing segments 3, 4 are arranged over the entire circumference of the shaft part 13.

[0037] Figure 2 also indicates (by a double arrow) that adjustment means 12 can be provided for the first radial position n. This offers the possibility of moving the bearing segments 3 back into their radial position after the rotor has started up, so that the bearing load is predominantly absorbed by the bearing segments 4. The manner in which the adjustment of the bearing segments 3 in the radial direction r is essentially arbitrary. For example, bucket tappets can be used for this purpose. This also allows the rigidity to be influenced. This is particularly advantageous when classic hydrodynamic segments are used for the bearing segments 4, while hydrostatic plain bearing segments are used for the plain bearing segments 3.

[0038] In this case, it is advantageous to install plain bearing segments 3 with hydrostatic lubrication pockets of greater height (first radial position n) and a more elastic bearing together with plain bearing segments 4 without hydrostatic lubrication pockets of lower height (second radial position r2) and less elastic bearing. During takeoffs with low wind loads, the hydrostatic plain bearing segments 3 are primarily in contact. At high wind loads, the elastically mounted plain bearing segments 3 with hydrostatic lubrication pockets deflect, and the more load-bearing plain bearing segments 4 without hydrostatic lubrication pockets come into contact.

[0039] The plain bearing segments 3 with hydrostatic lubrication pockets can, as explained, be mounted, for example, on hydraulic bucket tappets or hydraulic cylinders so that they can be extended for starting and stopping operations.

[0040] List of reference symbols

[0041] 1 Main bearing of the wind turbine

[0042] 2 bearing outer ring

[0043] 3 bearing segment

[0044] 4 bearing segment

[0045] 5 storage space

[0046] 6 storage space

[0047] 7 Support element

[0048] 8 support element

[0049] 9 Component

[0050] 10 components

[0051] 11 Housing part

[0052] 12 Adjustment means for the first radial position

[0053] 13 Shaft part a axial direction r radial direction

[0054] U circumferential direction ri first radial position

[0055] T2 second radial position

Claims

Patent claims 1. Main bearing (1) of a wind turbine, wherein the main bearing (1) is designed as a plain bearing, wherein the bearing outer ring (2) of the plain bearing consists of a number of bearing segments (3, 4) arranged over the circumference of the bearing outer ring (2), and wherein the bearing segments (3, 4) have a bearing surface (5, 6) which are set or adjustable to a defined radial position (n, r2), characterized in that the bearing segments (3, 4) consist of a first group and a second group, wherein the bearing segments (3) of the first group are set or adjustable to a first radial position (n), and wherein the bearing segments (3) of the first group have a first spring elasticity in the radial direction (r), and wherein the bearing segments (4) of the second group are set or adjustable to a second radial position (r2) which is different from the first radial position (n),and wherein the bearing segments (4) of the second group have a second spring elasticity in the radial direction (r) which is different from the first spring elasticity, wherein the first radial position (n) is greater than the second radial position (r2) and wherein the first spring elasticity is greater than the second spring elasticity., 2. Main bearing according to claim 1, characterized in that the difference between the first radial position (n) and the second radial position (r2) is between 0.1 mm and 5.0 mm.

3. Main bearing according to claim 1 or 2, characterized in that the first spring elasticity is at least a factor of 3, preferably at least a factor of 5, greater than the second spring elasticity.

4. Main bearing according to one of claims 1 to 3, characterized in that the bearing segments (3) of the first group and the bearing segments (4) of the second group are arranged axially (a) next to one another.

5. Main bearing according to one of claims 1 to 3, characterized in that the bearing segments (3) of the first group and the bearing segments (4) of the second group alternately follow one another in the circumferential direction (U).

6. Main bearing according to one of claims 1 to 5, characterized in that at least the bearing segments (3, 4) of a group each consist of a support element (7, 8) which is arranged on a component (9, 10) made of elastomer material, wherein the component (9, 10) made of elastomer material is fixed to a housing part (11).

7. Main bearing according to one of claims 1 to 6, characterized in that the bearing segments (3) of the first group are provided with a fluid inflow onto the bearing surface (5) in order to produce a hydrostatic bearing function.

8. Main bearing according to one of claims 1 to 7, characterized in that the bearing segments (3) of the first group are provided with adjusting means (12) with which the first radial position(s) can be changed.

9. Main bearing according to claim 8, characterized in that the adjusting means comprise a hydraulic piston-cylinder system which is used for adjusting the first radial position(s).

10. Main bearing according to claim 8, characterized in that the adjusting means comprise a mechanical adjusting system, in particular comprising a bucket tappet, which is used for adjusting the first radial position(s).

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