Hydrodynamic rotor shaft plain bearing for a rotor shaft, in particular of a wind turbine

Abstract

The invention relates to a hydrodynamic rotor shaft plain bearing for a rotor shaft (2), in particular of a wind turbine, the hydrodynamic rotor shaft plain bearing comprising a first and a separate second radial bearing (8, 9), each comprising a plurality of radial bearing segments (11, 14) which are supported in a bearing housing, the first and the second radial bearing each having a separate first and second radial bearing housing (10, 13), the first and the second radial bearing being axially spaced apart from one another, and wherein a first and a separate second axial bearing (17, 21) are provided which have a plurality of first and second axial bearing segments (18, 22), the first axial bearing segments supporting the rotor shaft against the one first radial bearing housing and the second axial bearing segments supporting the rotor shaft against the second radial bearing housing in the opposite direction.

Description

[0001] Hydrodynamic rotor shaft guide bearing for a rotor shaft, particularly of a wind turbine

[0002] The invention relates to a hydrodynamic rotor shaft plain bearing for a rotor shaft, in particular of a wind turbine, comprising a first and a separate second radial bearing, each comprising a plurality of radial bearing segments which are held in a bearing housing.

[0003] A wind turbine usually has several rotor blades arranged on a hub. The hub is connected to a rotor shaft, which in turn is coupled to a gearbox, followed by a generator whose rotor is connected to an output shaft of the gearbox. A gearless turbine configuration is also possible. Due to the interaction of the rotor blades with the oncoming wind, the rotor shaft, including the hub, and the downstream drive train rotate, so that the generator generates electricity. Inevitably, the rotor shaft also rotates and is mounted accordingly. On the one hand, the rotor shaft is mounted via a radial bearing, which usually consists of two axially spaced radial bearings that radially support the rotor shaft. In addition to the radial bearing, an axial bearing is sometimes also provided, which preferably allows support of the rotor shaft in both directions.Typically, an axial load is applied to the rotor side, resulting from the oncoming wind. Changing wind or flow conditions, such as a strong gust, can reverse the direction of the axial load, meaning the axial load is applied from the gearbox side, and the wind load acts on the rotor blades from the gearbox side. Therefore, axial bearings on both sides are advisable.

[0004] The rotor shaft bearings can be mounted using rolling bearings. Each bearing has several rolling elements. In the case of radial bearings, these are guided in an outer ring and run on an inner ring connected to the rotor shaft. In the case of axial bearings, these are guided on an axial bearing disk and run on a corresponding axial bearing section provided on the rotor shaft. Such rolling bearings are very solid and complex to manufacture and assemble, but are characterized by being largely maintenance-free.

[0005] Alternatively, a plain bearing for the rotor shaft using hydrodynamic plain bearings is also possible. Such plain bearings have multiple plain bearing segments. A radial bearing comprises several radial bearing segments, while an axial bearing comprises several axial bearing segments. The bearings are hydrodynamically supported, whereby a fluid lubricant is introduced by means of a pump during operation of the bearing, or a correspondingly high lubricant pressure is built up due to the geometry of a lubrication gap into which the lubricant is introduced. This leads to the formation of a load-bearing lubricant film, over which the rotor shaft is slide-mounted. With such hydrodynamic plain bearings, the bearing segments must be replaced for maintenance purposes when they wear out. This involves considerable effort, as access to the corresponding bearing segments is sometimes difficult.A hydrodynamic rotor shaft bearing arrangement is described, for example, in CN 217107882 U, which features a common bearing housing containing two combined radial-axial bearings, each of which is located at a shaft end. The surfaces of the bearing elements, also called bearing pads, of each combined bearing vary in size around the circumference. The bearing pads are smaller in one circumferential half than in the other to ensure effective support for the actual loads during operation.

[0006] The invention is based on the problem of providing an improved hydrodynamic rotor shaft plain bearing for a rotor shaft, in particular of a wind turbine.

[0007] To solve the problem, in a hydrodynamic rotor shaft plain bearing of the type mentioned at the outset, it is provided according to the invention that the first and the second radial bearing each have a separate first and second radial bearing housing, wherein the first and the second radial bearing are axially spaced from one another, and that a first and a separate second axial bearing are provided, which have a plurality of first and second axial bearing segments, wherein the first axial bearing segments support the rotor shaft against the first radial bearing housing and the second axial bearing segments support the rotor shaft in the opposite direction against the second radial bearing housing.

[0008] According to the invention, the two radial bearings are provided as separate units, each having a separate radial bearing housing, i.e., they are not integrated into a common bearing housing. They are axially spaced from one another, i.e., one radial bearing is arranged in the region of a first end of the rotor shaft near the rotor, and the other radial bearing is arranged in the region of a second end of the rotor shaft near the gearbox. Thus, there is a sufficient distance between the two bearings, allowing easy access to both radial bearings, since a maintenance person can enter this space and reach the bearings to perform any maintenance work.

[0009] In addition to the two separate radial bearings, two separate axial bearings are also provided as separate units, each having a plurality of first and second axial bearing segments, with axial support being provided bidirectionally, i.e. in both directions, via these axial bearings. The arrangement according to the invention is such that the first axial bearing segments support the rotor shaft against the first radial bearing housing, and the second axial bearing segments support the rotor shaft in the opposite direction against the second radial bearing housing. The radial bearing housings are firmly connected, in particular screwed, to a corresponding support, for example the base frame of a nacelle of a wind turbine. The radial bearing housings are therefore rigid, positionally fixed support elements that, in addition to providing radial support and guidance, also serve as support elements for the axial support via the two axial bearings.The first axial bearing segments support the rotor shaft axially against the first radial bearing housing, while the second axial bearing segments support the rotor shaft in the opposite direction against the second radial bearing housing. The radial bearing housings therefore have a dual function, i.e., they also serve as the rotor-side axial bearing or axial support. This enables a compact bearing design.

[0010] In a further embodiment of the invention, it can be provided that the first axial bearing segments support a radial flange of the rotor shaft against the first radial bearing housing. The first radial bearing with the first radial bearing housing is arranged at the rotor-side end of the rotor shaft, so that the first axial bearing is also arranged at the rotor-side end. The often conical rotor shaft has a radial flange at this end, i.e. a corresponding axial support plane, which can also be referred to as a shoulder, whereby the connection to a hub of the rotor in the case of a wind turbine is made at this radial flange. This radial flange is used as a second axial support element alongside the first radial bearing housing, i.e. the first axial bearing segments are arranged in this area so that the radial flange of the rotor shaft can be axially supported against the first radial bearing housing.

[0011] The arrangement can be such that the first axial bearing segments are arranged on the first radial bearing housing. In this case, the axial bearing segments are also fixed in position, since the first radial bearing housing is fixed in position. The radial flange therefore slides with its support surface on the axial bearing segments or the hydrodynamic lubricating film formed on them as the rotor shaft rotates.

[0012] Alternatively, it is also conceivable for the first axial bearing segments to be arranged on the radial flange. In this case, the arrangement is the reverse of that described above. The axial bearing segments rotate with the rotor shaft or the radial flange and in turn slide on the fixed axial support surface of the first radial bearing housing or the lubricating film formed thereon. In a further development of this variant, it is conceivable for one or more locking receptacles to be provided on the radial flange on a first radius, with the first axial bearing segments being arranged on the radial flange on a second radius. In order to lock the rotor or the entire rotating train, for example for maintenance purposes, it is fundamentally possible to provide a suitable locking device by means of which the rotor can be locked in defined positions relative to the first radial bearing housing.This locking device comprises, for example, a plurality of locking receptacles formed on the radial flange, wherein a locking element arranged on the radial bearing housing and movable via an adjusting element releasably engages in one of these locking receptacles for locking. If such locking receptacles are provided on the radial flange, the axial bearing segments are arranged on a different, preferably slightly larger, radius.

[0013] While the first axial bearing is arranged close to the rotor, the second axial bearing is arranged at the other shaft end, i.e. close to the gearbox. In order to achieve the best possible axial support in this area as well, a further development of the invention can provide for the second axial bearing segments to be arranged on a radially extending bearing carrier which is arranged on the second radial bearing housing, wherein the axial bearing segments support the second radial bearing housing against a bearing geometry provided on the rotor shaft. At this shaft end, unlike the shaft end close to the rotor, no corresponding radial flange is provided which can serve as a support plane. Instead, a suitable bearing geometry with a smaller radius is provided there, the radius of which, however, is significantly smaller than that of the second radial bearing housing.Since the radial bearing housing is also part of the axial support on this side, a corresponding, radially extending bearing carrier is provided, on which the second axial bearing segments are arranged. This bearing carrier is arranged on the second radial bearing housing and is designed such that the axial bearing segments attached to it interact with the bearing geometry of the rotor shaft. The bearing carrier, which is ring- or disc-shaped, is expediently screwed to the second radial bearing housing, for which purpose corresponding connection interfaces are provided on it and on the radial bearing housing. Appropriate fastening options for the axial bearing segments are also provided.

[0014] The shaft-side bearing geometry can be formed integrally in the form of a step, a collar, a flange, or a thickened portion on the usually conical rotor shaft, providing an axial bearing surface. For example, the rotor shaft has a groove into which the bearing carrier and, with it, the axial bearing segments engage. Accordingly, no separate bearing element is required to implement the bearing geometry.

[0015] Alternatively, it is conceivable for the bearing geometry to be implemented in the form of a bearing disk attached to the rotor shaft. In this variant, a separate bearing element in the form of a bearing disk is arranged on the rotor shaft and firmly connected to it, with the bearing disk providing one or both axial bearing surfaces.

[0016] The invention is explained below using exemplary embodiments with reference to the drawings. The drawings are schematic representations and show:

[0017] Figure 1 is a schematic diagram of a rotor shaft plain bearing according to the invention of a first embodiment,

[0018] Figure 2 is a schematic diagram in the form of a partial view of a rotor shaft plain bearing according to the invention of a second embodiment, and

[0019] Figure 3 is a plan view of the radial flange of the rotor shaft from Figure 2.

[0020] Figure 1 shows a schematic diagram of a hydrodynamic rotor shaft plain bearing 1 according to the invention, by means of which a rotor shaft 2, for example a rotor shaft of a wind turbine, is held. The rotor shaft 2 has a first end 3, on which a radial flange 4 is arranged, which, in the case of a wind turbine shown here, is connected to a hub 5 on which a plurality of rotor blades 6 are arranged. The rotor shaft 2 has a second end 7, which, in the case of an arrangement in a wind turbine, is coupled to a gearbox or an input shaft of the gearbox. The rotor shaft is to be mounted radially and axially in a suitable manner. To implement the radial bearing, a first radial bearing 8 is provided, which is arranged adjacent to the first end 3, and a second radial bearing 9, which is arranged adjacent to the other end 7. The two radial bearings 8, 9 are hydrodynamic plain bearings.

[0021] The first radial bearing 8 has a separate, annular first bearing housing 10, on which a plurality of first radial bearing segments 11 are arranged, distributed around the circumference of the radial bearing housing 10, which are therefore necessarily also distributed around the outer circumference 12 of the rotor shaft 2. The second radial bearing 9 also has a separate second radial bearing housing 13, on which a plurality of second radial bearing segments 14 are arranged, distributed around the inner circumference of the annular radial bearing housing 13, which are also distributed around the outer circumference 12 of the rotor shaft 2.The radial bearing segments 11, 14, which can also be referred to as radial bearing pads, allow the formation of a hydrodynamic lubricating film in a bearing gap between the respective radial bearing segments 11, 14 and the outer circumference 12 of the rotor shaft 2, wherein the lubricant forming this lubricating film is conveyed to this lubricating gap by means of a pump, into which the lubricant is actively drawn as a result of the shaft rotation. The two radial bearings 8, 9 or the radial bearing housings 10, 13 are axially spaced from one another, resulting in a gap 15 that a maintenance person can easily access for maintenance purposes. During such maintenance, it may be necessary to replace the radial bearing segments 11, 14, for which purpose they are usually pulled radially out of the respective radial bearing housing 10, 13 and new radial bearing segments are radially inserted.

[0022] The radial bearing housings 10, 13 are arranged in a fixed position on a support 16, in this case a base frame of a nacelle of the wind turbine. They are thus arranged in a fixed position, along with the radial bearing segments 11, 14 arranged in the radial bearing housings 10, 13. Due to this fixed position, the radial bearing housings 10, 13 can serve as support elements, via which the rotor shaft 2 can be supported in both axial directions via suitable axial bearings.

[0023] To implement this axial support, a first axial bearing 17 is provided in the region of the end 3 closest to the rotor. The axial bearing 17 comprises a plurality of separate axial bearing segments 18, which, in the exemplary embodiment shown in Figure 1, are arranged on an end face 19 of the first radial bearing housing 10. They are directed towards a running surface 20 of the radial flange 4, so that during shaft rotation, the radial flange 4 runs axially on the axial bearing segments 18, which in turn are fixed in position, or on the hydrodynamic lubricating film formed between them. The first radial bearing housing 10 therefore serves as a support element against which the rotor shaft 2 is axially supported and slide-mounted via the radial flange 4. The axial bearing segments 18 are, of course, fastened to suitable fastening interfaces of the first radial bearing housing 10.

[0024] To provide support in the other axial direction, a second axial bearing 21 is provided. This also comprises a plurality of separate second axial bearing segments 22, which are arranged on a bearing carrier 23, which is designed as a sufficiently stable, annular disk-shaped carrier. The bearing carrier 23, in turn, is fastened to corresponding interfaces of the second radial bearing housing 13 using suitable fastening means such as screw connections; it is therefore also fixed in position, as are the second axial bearing segments 22. A bearing geometry 24 is formed on the rotor shaft 2, for which purpose a radial groove 25 is introduced into the rotor shaft 2, which forms a step with an axial bearing surface 26. As can be seen, the bearing carrier 23 and, with it, the axial bearing segments 22 arranged thereon engage in this groove 25, so that the axial bearing segments 22 are positioned axially adjacent to the bearing surface 26.During operation, the bearing surface 26 can run axially on the second axial bearing segments 22 or the hydrodynamic lubricating film formed therebetween, and is supported by a sliding bearing. Here, too, the second radial bearing housing 13, which is fixed in position as described, ultimately serves as a support element on which the second axial bearing segments 22 and, via these, the rotor shaft 2 are ultimately supported. Both the first radial bearing housing 10 and the second radial bearing housing 13 therefore have a dual function: first, the radial mounting and bearing of the radial bearing segments 11, 14, and, second, the function of a support element for the axial support and bearing of the rotor shaft 2 via the axial bearings 17, 21.

[0025] It can be seen that the first axial bearing segments 18 and the second axial bearing segments 22 are directed in opposite directions, just as the running surface 20 of the radial flange 4 and the bearing surface 26 of the bearing geometry 24 are directed in opposite directions, so that a bidirectional support and sliding bearing of the rotor shaft 2 is possible via the two axial bearings 18, 21.

[0026] In the embodiment shown in Figure 1, the axial bearing segments 18 are arranged as described on the first radial bearing housing 10. During operation, the running surface 20 of the radial flange 4 slides on the fixed axial bearing segments 18. An alternative embodiment is shown in Figure 2. There, too, the first axial bearing 17 is arranged at the end 3 closest to the rotor, such that the radial flange 4 is supported against the first radial bearing housing 10, which here too is arranged in a fixed position on the carrier 16. In this variant, however, the first axial bearing segments 17 are fastened to the radial flange 4 and axially aligned so that they face a running surface 27 of the first radial bearing housing 10. The axial bearing segments 18 rotate here together with the rotor shaft 2 or the radial flange 4; they run, supported by the hydrodynamic lubricating film, on the bearing surface 27 of the first radial bearing housing 10.Again, the first radial bearing housing 10 has a dual function, namely, on the one hand, the holding and support of the radial bearing segments 11 and, on the other hand, that of an axial support element for the axial bearing on this side.

[0027] In a wind turbine, as shown by way of example in the figures, it is sometimes necessary to lock the rotor in certain positions, for example for maintenance purposes. For this purpose, a locking device is provided which allows the entire rotor assembly to be fixed in specific rotational positions. In the example shown, this locking device can act between the first radial bearing housing 10 and the radial flange 4. For this purpose, it is possible (see Figure 3, which shows a view of the radial flange in the direction of the hub 5), to arrange a plurality of separate locking receptacles 28 on the radial flange 4, distributed around the circumference, preferably equidistantly, wherein a corresponding locking element, such as a locking pin or the like that is linearly movable via an actuating element, is arranged on the first radial bearing housing 10 and can be inserted into a corresponding locking receptacle 28 to lock the assembly against rotation.As Figure 3 shows, the locking receptacles 28 are arranged distributed over a first radius around the longitudinal axis of the rotor shaft 2. The axial bearing segments 18, however, are located on a second, larger radius in the example. A reversed arrangement, relative to the radius of the arrangement, would also be conceivable. The axial bearing segments are also arranged equidistantly around the circumference of the rotor shaft 2 (this generally applies to the arrangement of all first and second axial bearing segments 18, 22). In this way, the integration of both the axial bearing segments and the locking receptacles 28 together on the radial flange 4 is possible.

[0028] List of reference symbols

[0029] Rotor shaft plain bearing rotor shaft near-rotor end

[0030] Radial flange

[0031] hub

[0032] Rotor blade second end

[0033] Radial bearing Radial bearing Bearing housing Radial bearing segment Outer circumference

[0034] Radial bearing housing Radial bearing segment space

[0035] Carrier thrust bearing thrust bearing segment end face

[0036] Running surface Axial bearing Axial bearing segment Bearing carrier Bearing geometry Groove

[0037] Storage area Storage area Locking receptacle

Claims

Patent claims 1 . Hydrodynamic rotor shaft plain bearing for a rotor shaft (2), in particular of a wind turbine, comprising a first and a separate second radial bearing (8, 9), each comprising a plurality of radial bearing segments (11, 14) which are held in a bearing housing, characterized in that the first and the second radial bearing (8, 9) each have a separate first and a second radial bearing housing (10, 13), wherein the first and the second radial bearing (8, 9) are axially spaced from one another, and in that a first and a separate second axial bearing (17, 21) are provided, which have a plurality of first and second axial bearing segments (18, 22), wherein the first axial bearing segments (18) support the rotor shaft (2) against the first radial bearing housing (10) and the second axial bearing segments (22) support the rotor shaft (2) in the opposite direction against the second radial bearing housing (13).

2. Hydrodynamic rotor shaft plain bearing according to claim 1, characterized in that the first axial bearing segments (18) support a radial flange (4) of the rotor shaft (2) against the first radial bearing housing (10).

3. Hydrodynamic rotor shaft plain bearing according to claim 2, characterized in that the first axial bearing segments (18) are arranged on the first radial bearing housing (10).

4. Hydrodynamic rotor shaft plain bearing according to claim 2, characterized in that the first axial bearing elements (18) are arranged on the radial flange (4).

5. Hydrodynamic rotor shaft plain bearing according to claim 4, characterized in that one or more locking receptacles (28) are provided on the radial flange (4) on a first radius, wherein the first axial bearing segments (18) are arranged on the radial flange (4) on a second radius.

6. Hydrodynamic rotor shaft plain bearing according to one of the preceding claims, characterized in that the second axial bearing segments (22) are arranged on a radially extending bearing carrier (23) which is arranged on the second radial bearing housing (13), wherein the axial bearing segments (22) support the second radial bearing housing (13) against a bearing geometry (24) provided on the rotor shaft (2).

7. Hydrodynamic rotor shaft plain bearing according to claim 6, characterized in that the bearing geometry (24) is provided in one piece on the rotor shaft (2) in the form of a step, a collar or a thickening.

8. Hydrodynamic rotor shaft plain bearing according to claim 7, characterized in that the rotor shaft (2) has a groove (25) into which the bearing carrier (23) engages to form the step.

9. Hydrodynamic rotor shaft bearing according to claim 6, characterized in that the bearing geometry is realized in the form of at least one bearing disc fastened to the rotor shaft (2).

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