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 (2), in particular of a wind turbine, comprising at least two separate radial bearings (5, 6), each of which comprises a plurality of radial bearing segments (9, 11), and at least one axial bearing (7) comprising a plurality of axial bearing segments (14, 15) that are held in a bearing housing, wherein each radial bearing (5, 6) has a separate radial bearing housing (8, 10), and the axial bearing (7) has a separate axial bearing housing (13), said axial bearing (7) being located axially between the two radial bearings (5, 6) and being axially spaced therefrom.

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 at least one 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 preferably 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 or flow conditions, for example, during a strong gust, the direction of the axial load can be reversed, meaning that the axial load is applied from the gearbox side, meaning the wind load acts from the gearbox side onto the rotor blades. 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 is also possible using hydrodynamic plain bearings, as described, for example, in CN 112943555 A. Such plain bearings have multiple plain bearing segments. A radial bearing comprises multiple radial bearing segments, while an axial bearing comprises multiple axial bearing segments. The bearing is hydrodynamic, for which a fluid lubricant is introduced at a correspondingly high pressure 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, via 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 if accessibility to the corresponding bearing segments is difficult.

[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 rotor shaft plain bearing of the type mentioned at the outset, it is provided according to the invention that each radial bearing has a separate radial bearing housing and the axial bearing has a separate axial bearing housing, wherein the axial bearing is arranged axially between the two radial bearings and is axially spaced from them.

[0008] According to the invention, the three bearings provided, i.e., the two radial bearings and the axial bearing, are separate bearing units, meaning they are not connected to one another. Rather, each radial bearing has a separate radial bearing housing, just as the axial bearing has a separate axial bearing housing. The two radial bearings are axially spaced from one another; the first radial bearing is positioned near the end of the rotor shaft to which the hub is connected, while the second radial bearing is located near the other end of the rotor shaft, which is coupled to the gearbox. The axial bearing is arranged between the two radial bearings and axially spaced from both, so that a corresponding gap is created between the axial bearing and both radial bearings.Since each bearing has a separate bearing housing, accessibility is fundamentally improved compared to arrangements in which, for example, the axial bearing and one of the radial bearings are provided in a combined bearing arrangement, as provided for example in CN 11294355 A. Since, according to the invention, all bearings are separate, easier, individual accessibility is provided. Furthermore, the inventive arrangement of the axial bearing between the two radial bearings and axially spaced from the two radial bearings enables maintenance personnel to enter the area between the bearings and reach the bearings, which is particularly useful in the case of the axial bearing when the axial bearing segments have to be moved axially in and out of the axial bearing housing.

[0009] As described, the axial bearing is arranged, axially speaking, between the two radial bearings and spaced apart from them. To enable the axial bearing to provide axial support, an axial bearing geometry is provided in this area of ​​the rotor shaft in a further development of the invention, against which the axial bearing engages axially. The rotor shaft is therefore provided with a specific bearing geometry, which is provided in the area between the radial bearings and against which the axial bearing segments engage. Preferably, axial bearing segments are provided in two separate, circumferential row arrangements, so that the axial bearing segments engage the bearing geometry from both sides and can support the rotor shaft in both axial directions.

[0010] In a specific embodiment, the bearing geometry can be provided integrally on the rotor shaft in the form of a step, a collar, a flange, or a thickened portion. The rotor shaft is thus provided with a corresponding geometry that forms one or preferably two axial bearing surfaces that are integral with the rotor shaft, meaning that no separate bearing element is attached to the rotor shaft to implement the bearing geometry.

[0011] 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.

[0012] As described, each radial bearing and the axial bearing have a separate bearing housing. According to a first variant of the invention, the radial bearing housings and the axial bearing housing are preferably one-piece. The housings are thus one-piece or single-material metal housing elements, which are cast, for example, as cast components or machined from a corresponding solid material.

[0013] Alternatively, it is conceivable for each radial bearing housing and the axial bearing housing to consist of several housing segments that are connected to one another. For example, each bearing housing can consist of two housing segments, each rotating at 180°, or three housing segments, each rotating at 120°, or four housing segments, each rotating at 90°. This segment design simplifies the manufacture of the respective bearing housing, be it a radial bearing housing or an axial bearing housing, as corresponding segments are easier to produce than a one-piece, ring-shaped complete housing. The segment design also allows for simple production in larger quantities. In the assembled position, the corresponding housing segments are, of course, firmly connected to one another.The housing segments can be connected via screw connections. For this purpose, corresponding connecting sections are provided on the housing segments, where the fastening elements extending between the housing segments can be arranged in the form of screw connections. The connecting sections can, for example, have simple holes through which threaded bolts are inserted and then screwed on both sides with nuts. Alternatively, the connecting sections can also have internal threads that allow screwing in, etc. As an alternative to the use of screw connections, it is also conceivable to weld the housing segments together in the assembled position, i.e., to connect them via welded joints.

[0014] The radial bearing housings and / or the axial bearing housing, or, if the respective housings are designed in the segmental construction, their housing segments, are preferably metal cast components which are cast using appropriate molds.

[0015] The invention is explained below using an exemplary embodiment with reference to the drawing. The drawing is a schematic representation and shows a hydrodynamic rotor shaft plain bearing according to the invention in the form of a schematic diagram.

[0016] The figure shows a schematic diagram of a hydrodynamic rotor shaft plain bearing 1 according to the invention, via which a rotor shaft 2, for example a rotor shaft of a wind turbine, is mounted. The rotor shaft 2 has a first end 3, which, in the case of an arrangement in a wind turbine, is connected to a hub on which the rotor blades are arranged. The rotor shaft 2 has a second end 4, which, in the case of an arrangement in a wind turbine, is coupled to a gearbox or an input shaft of the gearbox.

[0017] The rotor shaft 2 is to be supported both radially and axially. To achieve this, a first radial bearing 5 is provided, which is arranged adjacent to the first end 3, and a second radial bearing 6 is arranged adjacent to the second end 4. An axial bearing 7 is arranged between the two radial bearings 5, 6 and is axially spaced from both radial bearings 5, 6, as shown in the figure. The two radial bearings 5, 6 and the axial bearing 7 are hydrodynamic plain bearings. The first radial bearing 5 has a first separate radial bearing housing 8, on which a plurality of first radial bearing segments 9 are arranged, distributed around the inner circumference of the annular radial bearing housing 8, which are therefore necessarily also distributed around the outer circumference 12 of the rotor shaft 2. The second radial bearing 6 also has a separate radial bearing housing 10, on which a plurality of second radial bearing segments distributed around the inner circumference of the annular radial bearing housing 10

[0018] 11 are arranged, which are also distributed around the outer circumference 12 of the rotor shaft 2. The radial bearing segments 9, 11, 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 segment 9, 11 and the outer circumference

[0019] 12 of the rotor shaft 2, wherein this lubricating film is formed by means of a pump which conveys the lubricant to this lubricating gap, into which the lubricant is actively drawn as a result of the shaft rotation.

[0020] The axial bearing 7 also has a separate, annular axial bearing housing 13, on which first axial bearing segments 14 and second axial bearing segments 15 are accommodated opposite one another in two radially encircling row arrangements. A bearing geometry 16, which is formed on the rotor shaft 2 and provides two axial bearing surfaces 17, engages between the axial bearing segments 14, 15. In the area of ​​these bearing surfaces 17, a lubrication gap is formed between the axial bearing segments 14, 15, into which a lubricant is introduced by means of a pump and by means of which a supporting lubricant film is built up during rotation of the rotor shaft 2. This lubricant film serves for the axial plain bearing via the axial bearing segments 14, 15, which can also be referred to as axial bearing pads.The bearing geometry 16 can be implemented as a single piece on the rotor shaft 2 in the form of a flange, shown here, which protrudes radially from the outer circumference 12 of the rotor shaft 2 and extends between the row arrangements of the axial bearing segments 14, 15. Alternatively, the arrangement of a separate bearing disk forming a corresponding flange is also conceivable.

[0021] The radial bearing housings 8, 10 and the axial bearing housing 13 are fixedly mounted on a support 18, for example, a base frame, by means of suitable screw connections. These support 18 may be, for example, a base frame of a wind turbine nacelle. They are thus fixedly mounted, along with the radial bearing segments 9, 11 and axial bearing segments 14, 15, which are fixedly mounted in the radial bearing housings 8, 10 and the axial bearing housing 13. However, the radial bearing segments 9, 11 and the axial bearing segments 14, 15 are detachably mounted in the respective radial bearing housing 8, 10 or axial bearing housing 13, so that they can be removed and replaced as needed.The removal of the radial bearing segments 9, 11 preferably takes place radially, for which purpose corresponding precautions have been taken on the part of the radial bearing housings 8, 10 that allow radial accessibility to the radial bearing segments 9, 11, so that these can each be pulled radially out of the respective radial bearing housing 8, 10 and new radial bearing segments can be inserted radially. In contrast, the axial bearing segments 14, 15 are preferably removed axially from the axial bearing housing 13, for which purpose corresponding precautions have also been taken on the axial bearing housing 13 that allow axial accessibility to the axial bearing segments 14, 15. These precautions allow the axial bearing segments 14, in the example shown, to be removed to the left from the axial bearing housing 13 and new axial bearing segments inserted, and the axial bearing segments 15, in the example shown, to be removed to the right from the axial bearing housing and new axial bearing segments inserted.As an alternative to the removal directions of the radial bearing segments 9, 11 (radial) and the axial bearing segments 14, 15 (axial) described above, it is of course also conceivable to implement reversed removal directions, ie that appropriate precautions are taken to allow axial removal of the radial bearing segments 9, 11 and radial removal of the axial bearing segments 14, 15.

[0022] As described and as the figure shows, the radial bearing housings 8, 10 are arranged axially spaced from the axial bearing housing 13, i.e., a first intermediate space 19 is formed between the first radial bearing 5 and the axial bearing 7, and a second intermediate space 20 is formed between the second radial bearing 6 and the axial bearing 7. Each of these intermediate spaces 19, 20 is accessible to maintenance personnel, which simplifies maintenance, particularly when any bearing segments are to be removed axially.The radial bearing housings 8, 10 and the axial bearing housing 13 are preferably metal cast components, which can either be designed as a single piece as closed, one-piece housings, or which are multi-part in segment construction, i.e. consist of several separate housing segments which are assembled and connected to form the ring shape, forming the complete housing, which is preferably done by screw connections, but is also possible in principle by welded connections.

[0023] List of reference symbols

[0024] Rotor shaft plain bearing Rotor shaft first end second end Radial bearing Radial bearing Axial bearing

[0025] Radial bearing housing Radial bearing segment Radial bearing housing Radial bearing segment Outer circumference Axial bearing housing Axial bearing segment Axial bearing segment

[0026] Bearing geometry bearing surface carrier

[0027] space space

Claims

Patent claims 1. Hydrodynamic rotor shaft plain bearing for a rotor shaft (2), in particular of a wind turbine, comprising at least two separate radial bearings (5, 6), each comprising a plurality of radial bearing segments (9, 11), and at least one axial bearing (7) comprising a plurality of axial bearing segments (14, 15) which are held in a bearing housing, characterized in that each radial bearing (5, 6) has a separate radial bearing housing (8, 10) and the axial bearing (7) has a separate axial bearing housing (13), wherein the axial bearing (7) is arranged axially between the two radial bearings (5, 6) and is axially spaced from them.

2. Hydrodynamic rotor shaft plain bearing according to claim 1, characterized in that the rotor shaft (2) has an axial bearing geometry (16) on which the axial bearing (7) engages axially.

3. Hydrodynamic rotor shaft plain bearing according to claim 2, characterized in that the bearing geometry (16) is provided in one piece on the rotor shaft (2) in the form of a step, a collar, a flange or a thickening.

4. Hydrodynamic rotor shaft plain bearing according to claim 2, characterized in that the bearing geometry (16) is realized in the form of at least one bearing disc fastened to the rotor shaft (2).

5. Hydrodynamic rotor shaft plain bearing according to one of the preceding claims, characterized in that the radial bearing housings (8, 10) and the axial bearing housing (13) are one-piece, or consist of several housing segments which are connected to one another.

6. Hydrodynamic rotor shaft plain bearing according to claim 5, characterized in that the housing segments are connected to one another via screw or welded connections.

7. Hydrodynamic rotor shaft bearing according to one of the preceding claims, characterized in that the radial bearing housings (8, 10) and / or the axial bearing housing (13), or their housing segments, are metal cast components.

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