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

Abstract

The invention relates to a hydrodynamic plain bearing for a rotor shaft (8), in particular of a wind turbine, comprising at least two separate radial bearings (28, 29), each of which comprises a plurality of radial bearing segments (32, 33), and an axial bearing (1) comprising a plurality of axial bearing segments (5) that are held in a bearing housing. The axial bearing comprises an axial bearing housing (2) on which a plurality of radial openings (4) are provided, and an axial bearing segment (5) is inserted into each opening (4), said axial bearing segment being radially insertable and removable.

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 at least two separate radial bearings, each comprising a plurality of radial bearing segments, and an axial bearing comprising a plurality of axial 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. 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 also provided, which usually allows the rotor shaft to be supported in both directions. Typically, an axial load is applied to the rotor side, resulting from the oncoming wind.Due to changing wind conditions or flow conditions, for example when there is a strong gust, the direction of the axial load can be reversed, i.e. the axial load is then applied from the gearbox side, so the wind load acts on the rotor blades from the gearbox side.

[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 pump is used to introduce a fluid lubricant at a correspondingly high pressure 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, which supports the rotor shaft in plain bearings. 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 for the radial support of a shaft is described, for example, in CN 218542962 U, which describes an annular, radially closed radial bearing housing with several radial bearing segments arranged on its inner circumference and projecting radially inward. Another hydrodynamic rotor shaft bearing is described, for example, in CN 217107882 U, which provides a common bearing housing in which two combined radial-axial bearings are accommodated, with each combined radial-axial bearing being arranged at a shaft end. The surfaces of the bearing elements, also called bearing pads, of each combined bearing vary in size around the circumference. Smaller bearing pads are provided in one circumferential half than in the other circumferential half in order to effectively support 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 for a wind turbine. To solve this problem, in a hydrodynamic rotor shaft plain bearing of the type described above, the invention provides that the axial bearing comprises an axial bearing housing in which several radial openings are provided, wherein an axial bearing segment is inserted into each opening and can be radially inserted and removed.

[0007] The axial bearing provided in the rotor shaft plain bearing according to the invention allows the axial bearing segments to be removed and inserted by radial movement, as the axial bearing or the axial bearing housing is designed as a separate pillow block housing or as a combined axial-radial bearing housing. It has a plurality of radial openings distributed around its circumference, preferably equidistantly, with a separate axial bearing segment radially inserted into each opening and able to be removed radially if necessary. If the axial bearing is a separate bearing and not integrated into one of the two, also separate, radial bearings, it is easily accessible due to this separation between the radial and axial guidance, which simplifies radial assembly and disassembly. Even when integrated into a common axial-radial bearing housing, easy assembly is ensured due to the radial removal capability.

[0008] It is particularly expedient if the cross-section of the openings widens from radially inward to radially outward, with each opening preferably having a cross-section that widens from the inside to the outside. Each opening is therefore not designed as a simple, cylindrical bore, for example, but has a specific cross-section that widens from the inside to the outside. It is particularly preferred that each opening has a conical cross-section. This design of the opening cross-section allows the axial bearing segments to be fitted and removed from the radial outside, i.e. they are inserted into the opening by a radial movement, with the change in cross-section and the shape of the axial bearing segments being adapted to the opening cross-section enabling precise radial positioning of each individual axial bearing segment.The final assembly position is defined by the fact that the respective axial bearing segment is inserted into the opening sufficiently far, and the corresponding cross-sections mesh positively. A tapered cross-section of the openings proves particularly useful, as this is also easy to manufacture.

[0009] In a further development of the invention, it can be provided that each axial bearing segment has an element carrier whose cross-sectional shape corresponds to the cross-section of the openings into which it is inserted, for a positive fit in the opening, wherein the element carrier has a fastening flange by means of which it can be detachably fastened to the axial bearing housing by means of fastening elements. An axial bearing segment is therefore designed in several parts and has an element carrier, which essentially represents a segment base and via which the positive connection to the axial bearing housing is made. One or two axial bearing sections are provided on the element carrier, which project radially inward and are supported on a corresponding bearing surface of the rotor shaft. During disassembly, the axial bearing segment is inserted with the element carrier into the opening until the assembly position defined by the positive cross-sectional connection is reached.The cross-section or cross-sectional shape of the element carrier corresponds to the cross-section or cross-sectional shape of the opening, so that such a positive fit is possible. Attachment is achieved using suitable fastening elements, in particular connecting screws, which screw a mounting flange provided on the element carrier to the axial bearing housing. The axial bearing housing, for example, has corresponding internally threaded holes into which the connecting screws are screwed.

[0010] If the cross-sectional shape already provides a corresponding anti-twist feature, meaning that a thrust bearing segment or element carrier can only be inserted in a defined position, no further anti-twist measures are required. However, if the opening shape is conical, and so is the shape of the element carrier, it is advisable to provide an anti-twist feature to secure the position of the thrust bearing segment in the opening. Such an anti-twist feature could, for example, be a recess in the mounting flange into which a projection on the thrust bearing housing engages when a thrust bearing segment is inserted. This allows the exact mounting position to be defined and adopted before the actual fastening.

[0011] Preferably, each axial bearing segment has two axial bearing sections that are axially directed in opposite directions and that bear against axial bearing surfaces of the rotor shaft. These two axial bearing sections provide bidirectional axial support, i.e., support in both directions of the rotor shaft. A corresponding bearing geometry is formed on the rotor shaft, providing two axially adjacent bearing surfaces on which the two axial bearing sections can engage. This provides a two-sided axial support against loads applied from both axial directions with one axial bearing.

[0012] According to the invention, the two bearing surfaces can be formed via two groove flanks of an engagement groove provided on the outside of the rotor shaft, into which the axial bearing sections engage, or via two groove flanks of an engagement groove formed between the rotor shaft and a gear shaft connected to it, into which the axial bearing sections engage. What both designs have in common is the formation of a corresponding groove that is axially delimited by groove flanks, wherein the groove flanks form the actual bearing surfaces on which the axial bearing sections are supported. This engagement groove can either be formed entirely on the outer circumference of the rotor shaft, but it can also be formed between the rotor shaft and a gear or gear shaft connected to it, which has a corresponding annular flange.To form the engagement groove on the outer circumference of the rotor shaft, such a groove can, for example, be integrally machined into the outer circumference of the rotor shaft, or an annular disk can be placed and fastened on the rotor shaft, which, together with a step formed on the rotor shaft, forms the groove, just as the groove can also be formed using two annular disks that are fastened to the rotor shaft. An engagement groove formed at one end of the rotor shaft can, for example, be formed using a collar formed on the end of the rotor shaft and an annular flange of a gear shaft. Different options for forming such an engagement groove are therefore conceivable, which in turn offers the possibility of arranging the engagement groove and thus the axial bearing at different positions relative to the length of the rotor shaft.

[0013] As described, the axial bearing can have a separate axial bearing housing. According to the invention, the axial bearing housing and thus the axial bearing can be arranged axially between the two radial bearings, which in turn have separate radial bearing housings. The two radial bearings or radial bearing housings are arranged axially spaced from one another. One is preferably located in the region of the end closest to the rotor, while the other is preferably located in the region of the end closest to the gearbox. Accordingly, there is sufficient axial spacing between the two radial bearings, into which the axial bearing can be easily integrated. A sufficient gap is formed between the axial bearing and the respective radial bearing, allowing a maintenance personnel to access it for maintenance purposes.Alternatively, it is conceivable that the separate axial bearing housing is arranged at an end of the rotor shaft facing the gearbox, axially adjacent to the separate radial bearing housing of the adjacent radial bearing. In this variant, the axial bearing is therefore arranged between the rear radial bearing (downwind side) and the gearbox. The axial bearing housing arranged at the end facing the gearbox can be connected to the radial bearing housing. This means that the axial bearing housing is bolted to the radial bearing housing, or a common housing is provided for the radial and axial bearings. In a further development of this variant, it is also conceivable that the gearbox is also bolted to the axial bearing housing.

[0014] In addition to the rotor shaft plain bearing, the invention further relates to an axial bearing for a rotor shaft plain bearing of the type described above. This is characterized in that the axial bearing housing has a plurality of radial openings, with an axial bearing segment inserted into each opening, which can be radially inserted and removed. It is particularly preferred if the cross section of each opening widens from radially inward to radially outward, with each opening preferably having a cross section that widens conically outward.

[0015] Finally, it can be provided that each axial bearing segment has an element carrier whose cross-sectional shape corresponds to the cross-section of the opening into which it is inserted, for a positive reception in the opening, wherein the element carrier has a fastening flange via which it is detachably fastened to the axial bearing ring by means of fastening elements.

[0016] All statements made in the context of the description of the rotor shaft plain bearing according to the invention with regard to the axial bearing described therein also apply equally to the axial bearing according to the invention.

[0017] The invention is explained below using exemplary embodiments with reference to the drawings. The drawings are schematic representations and show:

[0018] Figure 1 is a schematic diagram in perspective of an axial bearing according to the invention,

[0019] Figure 2 is a partial view of the axial bearing from Figure 1,

[0020] Figure 3 is a partial view of the axial bearing from Figure 1 with a view of the inner circumference,

[0021] Figure 4 is a partial view of a rotor shaft plain bearing according to the invention, showing the mounted axial bearing,

[0022] Figure 5 is a perspective view of a rotor shaft with mounted axial bearing, Figure 6 is a schematic diagram of a first rotor shaft plain bearing according to the invention,

[0023] Figure 7 is a schematic diagram of a second rotor shaft plain bearing according to the invention,

[0024] Figure 8 is a schematic diagram of a third rotor shaft plain bearing according to the invention, and

[0025] Figure 9 shows a schematic diagram of a fourth rotor shaft plain bearing according to the invention.

[0026] Figure 1 shows a schematic diagram of an axial bearing 1 according to the invention, which is designed and suitable for a rotor shaft plain bearing, in particular a rotor shaft of a wind turbine. The axial bearing 1 comprises an annular, in the example separate axial bearing housing 2, on which two radially projecting fastening sections 3 are arranged, offset by 180°, via which the axial bearing housing 2 is firmly screwed to a support, for example a base frame of a nacelle of a wind turbine. The annular axial bearing housing 2 has a plurality of separate openings 4, which radially penetrate the axial bearing housing 2 and are preferably designed as circular bores. The openings 4 are arranged equidistantly around the circumference of the axial bearing housing 2. An axial bearing segment 5 is inserted into each opening 4 from the radial outside, as the further Figures 2-4 show.Each axial bearing segment 5 has two axial bearing sections 6 which, in the assembled position, protrude on the inner circumference, as shown in particular in Figure 2, which are directed in opposite directions and which run or are supported on corresponding bearing surfaces which are formed, for example, directly on the rotor shaft, via a corresponding hydrodynamic lubricating film. This therefore enables bidirectional axial bearing support. Since, as Figure 1 shows, a large number of individual axial bearing segments 5 are provided around the circumference of the axial bearing housing 2, a preferably symmetrical support is provided around the circumference. Figure 4 shows a partial view of a rotor shaft plain bearing 7 according to the invention, part of which is the axial bearing 1 according to the invention, which is shown here in its assembled position on a rotor shaft 8.A bearing geometry 9 is formed on the rotor shaft 8, comprising an engagement groove 10, which is formed by a step 11 formed integrally on the rotor shaft 8 and a separate annular disc 12 fastened to the rotor shaft 8 via screw connections or a clamping ring, so that two bearing surfaces 13, 14 are formed, on which the two bearing sections 6 of each axial bearing segment 5 are axially supported.

[0027] Figure 4 shows, in particular, details regarding the arrangement of each axial bearing segment 5 on the axial bearing housing 2. Each opening 4 is circular in cross-section and has a conical cross-section that widens from radially inward to radially outward. This means that, viewed from the radial outside, each opening 4 is quasi funnel-shaped and slightly constricted in diameter. Each axial bearing segment 5 is designed to be shaped so that it can be inserted into this conical opening 4 with a form-fitting fit from the radial outside. For this purpose, each axial bearing segment 5 has an element carrier 15, which is designed as a kind of truncated cone and engages with a form-fitting fit in the conical opening 4. The element carrier 15 has a section 16 on which the two axial bearing sections 6 are arranged.On the opposite side, the element carrier 15 has a fastening flange 17, via which the respective axial bearing segment 5 is firmly connected to the axial bearing housing 2 using suitable fastening screws 18. The rotational position of the respective axial bearing segment 5 is defined by an anti-rotation device 19, for example a pin or projection projecting from the axial bearing housing 2, which engages in a corresponding recess in the fastening flange 17, before it is finally fixed in place using the fastening screws 18. The axial bearing segments 5 can therefore be easily inserted from the radial outside into the respective conical opening 4, where they can be received with a form-fitting fit and finally fixed in place. Radial removal is equally simple. For handling each axial bearing segment 5, a tool holder 20 is preferably provided on the fastening flange 17, to which a lifting tool, for example, can be attached.

[0028] Figure 5 shows a partial view of the rotor shaft bearing 7 from Figure 4, showing the complete rotor shaft 8 and the axial bearing 1 arranged on it. The rotor shaft 8 has a first end 21, on which an annular flange 22 is provided, via which the rotor shaft 8 can be connected to a hub on which several rotor blades are arranged. The rotor shaft 8 further has a second end 23, via which the rotor shaft 8 can be connected to an input shaft of a transmission, which will be discussed below.

[0029] Figure 6 shows a first embodiment of a hydrodynamic rotor shaft plain bearing 7 according to the invention. It shows the rotor shaft 8, to whose annular flange 22 a hub 24, to which several rotor blades 25 of a wind turbine are attached, is flanged. At the other end of the rotor shaft 8, a gearbox 26 is connected to the rotor shaft 8, in which the shaft rotation is converted, with a generator 27 being driven via an output shaft of the gearbox 26.

[0030] The rotor shaft 8 is supported radially by a first radial bearing 28, which is arranged adjacent to the annular flange 22, and a second radial bearing 29, which is arranged adjacent to the gearbox 26. The two radial bearings 28, 29 each have a radial bearing housing 30, 31, in which a plurality of radial bearing segments 32, 33 are arranged distributed around the circumference. The radial bearing housings 30, 31 are fixedly connected or screwed to a support 34, here a base frame of a nacelle of the wind turbine. It can be seen that there is a sufficient axial distance and space between the two radial bearings 28, 29, in which the axial bearing 1 according to the invention is arranged, which is only shown in outline here. The axial bearing 1 is also firmly connected or screwed to the support 34 via its axial bearing housing 2.In the example shown, a corresponding bearing geometry 9 is again formed on the rotor shaft 8, which here is formed by two bearing disks 35, 36 that define an engagement groove into which the axial bearing sections 6 of the axial bearing 1 engage. In this embodiment, the axial bearing 1 is arranged axially between the two radial bearings and spaced from them.

[0031] Figure 7 shows a second embodiment of a rotor shaft plain bearing 7 according to the invention, wherein the same reference numerals are used for the same components. The basic structure is the same as described for Figure 6, only the positioning of the radial bearings 28, 29 and the axial bearing 1 is different. In this embodiment, the axial bearing 1 is located on the downwind side, i.e., it is offset toward the gearbox 26 and is located between the second radial bearing 29 and the gearbox 26. Accordingly, the bearing geometry 9 is also axially positioned accordingly.

[0032] In the embodiment according to Figure 8, which also shows a rotor shaft plain bearing 7 according to the invention, the arrangement of the radial bearings 28, 29 and the axial bearing 1 is provided according to Figure 7. Here, however, the axial bearing housing 2 is axially connected or screwed to the second radial bearing housing 31 on the one hand. Likewise, the gearbox 26 and its housing are axially connected or screwed to the axial bearing housing 2. The bearing geometry 9 is formed here by a step 37 formed at the end of the rotor shaft 8, for which a corresponding collar is formed at the shaft end, and a flange 38 of a gearbox input shaft 39. This therefore also results in an engagement groove 10 into which the axial bearing sections 6 engage and on whose groove flanks they are axially supported.

[0033] The design of the rotor shaft plain bearing 7 according to Figure 9 differs from that according to Figure 8 only in that the axial bearing housing 2 is only axially connected to the second radial bearing housing 31 of the second radial bearing 29. It is therefore flange-mounted thereto. In this variant, the gearbox housing is not connected to the axial bearing housing 2; however, the flange 38 of the gearbox input shaft 39 also forms part of the bearing geometry 9 for forming the engagement groove 10, into which the axial bearing sections 6 of the axial bearing 1 engage. List of reference symbols

[0034] Thrust bearing Thrust bearing housing Mounting section Opening Thrust bearing segment Thrust bearing section Rotor shaft plain bearing Rotor shaft

[0035] Bearing geometry engagement groove step

[0036] Ring disc Bearing surface Bearing surface Element carrier Section Mounting flange Mounting screw

[0037] Anti-twist device tool holder first end ring flange second end

[0038] hub

[0039] Rotor blade Gearbox Generator Radial bearing Radial bearing Radial bearing housing Radial bearing housing Radial bearing segment Radial bearing segment Carrier Bearing disc Bearing disc Stage Flange Gearbox input shaft

Claims

Patent claims 1 . Hydrodynamic rotor shaft plain bearing for a rotor shaft (8), in particular of a wind turbine, comprising at least two separate radial bearings (28, 29), each comprising a plurality of radial bearing segments (32, 33), and an axial bearing (1) comprising a plurality of axial bearing segments (5) which are held in a bearing housing, characterized in that the axial bearing comprises an axial bearing housing (2) on which a plurality of radial openings (4) are provided, wherein an axial bearing segment (5) is inserted into each opening (4) and can be radially inserted and removed.

2. Hydrodynamic rotor shaft plain bearing according to claim 1, characterized in that the openings (4) widen in their cross section from radially inward to radially outward, wherein each opening (4) preferably has a cross section widening conically outwards.

3. Hydrodynamic rotor shaft plain bearing according to claim 1 or 2, characterized in that each axial bearing segment (5) has an element carrier (7) whose cross-sectional shape corresponds to the cross-section of the opening (4) into which it is inserted, for a positive reception in the opening (4), wherein the element carrier (17) has a fastening flange (17) via which it is detachably fastened to the axial bearing housing (2) by means of fastening elements (18).

4. Hydrodynamic rotor shaft plain bearing according to one of the preceding claims, characterized in that each axial bearing segment (5) has two axial bearing sections (6) which are directed axially in opposite directions and which bear against axial bearing surfaces (13, 14) of the rotor shaft (8).

5. Hydrodynamic rotor shaft plain bearing according to claim 4, characterized in that the two bearing surfaces (13, 14) are connected via two groove flanks of a the outside of the rotor shaft (8) provided engagement groove (10), in which the axial bearing sections (6) engage, or over two groove flanks of an engagement groove (10) formed between the rotor shaft (8) and a gear shaft (27) connected thereto, in which the axial bearing sections (6) engage.

6. Hydrodynamic rotor shaft plain bearing according to one of the preceding claims, characterized in that the axial bearing housing (2) is a separate bearing housing, wherein the axial bearing (1) is arranged axially between the two radial bearings (28, 29), which in turn have separate radial bearing housings (30, 31), or that the axial bearing housing (2) is a separate bearing housing which is arranged at an end (23) of the (8) rotor shaft directed towards a gearbox (26) axially adjacent to the separate radial bearing housing (31) of the adjacent radial bearing (29).

7. Hydrodynamic rotor shaft plain bearing according to claim 6, characterized in that the axial bearing housing (2) arranged at the end (23) directed towards the gear (26) is connected to the radial bearing housing (31), wherein optionally a housing of the gear (26) is connected to the axial bearing housing (2).

8. Axial bearing for a rotor shaft plain bearing according to one of the preceding claims, comprising an annular axial bearing housing (2), characterized in that the axial bearing housing (2) has a plurality of radial openings (4), wherein an axial bearing segment (5) is inserted into each opening (4) and is radially insertable and removable.

9. Axial bearing according to claim 8, characterized in that the cross section of each opening (4) widens from radially inward to radially outward, wherein preferably each opening (4) has a cross section widening conically outwards.

10. Axial bearing according to claim 8 or 9, characterized in that each axial bearing segment (5) has an element carrier (15) whose cross-sectional shape corresponds to the cross-section of the opening (4) into which it is inserted, for a positive reception in the opening (4), wherein the element carrier (15) has a fastening flange (17) via which it is detachably fastened to the axial bearing housing (2) by means of fastening elements (18).

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