Hydrodynamic rotor shaft bearing for a rotor shaft of a wind turbine

Abstract

Hydrodynamic rotor shaft sliding bearing for a rotor shaft (2) of a wind turbine, comprising at least one sliding bearing (3) radially or axially supporting the rotor shaft (2) and comprising several hydrodynamic bearing segments (6, 6a, 6b, 15), characterized in that the bearing segments (6, 6a, 6b, 15) are arranged on a support structure (7) which consists of several struts (9) connected to form a truss structure (8).

Description

[0001] The invention relates to a hydrodynamic rotor shaft sliding bearing for a rotor shaft of a wind turbine, comprising at least one sliding bearing comprising several hydrodynamic bearing segments and supporting the rotor shaft radially or axially.

[0002] A wind turbine typically has several rotor blades arranged around a hub. The hub is connected to a rotor shaft, which in turn is coupled to a gearbox. A generator follows the gearbox, and its 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, along with the hub and the downstream drive train, rotates, causing the generator to produce electricity. This inevitably also results in the rotation of the rotor shaft, which is supported accordingly. The rotor shaft is supported by radial bearings, usually two axially spaced radial bearings that provide radial support. In addition to the radial bearings, axial bearings are sometimes also used, which preferably support the rotor shaft in both directions. An axial load, resulting from the oncoming wind, is typically applied to the rotor side.Due to changing wind or flow conditions, for example during a strong gust, the direction of the axial load can reverse, meaning that the axial load then acts from the gearbox side, i.e., the wind load acts on the rotor blades from the gearbox side. Therefore, axial bearings on both sides are advisable.

[0003] Rotor shaft support can be achieved using rolling bearings. Each bearing has several rolling elements, which, in the case of radial bearings, are guided in an outer ring and run on an inner ring connected to the rotor shaft, and in the case of axial bearings, 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 robust and complex to manufacture and assemble, but are characterized by being virtually maintenance-free.

[0004] Alternatively, the rotor shaft can also be supported by a sliding bearing using hydrodynamic sliding bearings, as described, for example, in CN 112943555 A. Such sliding bearings have several sliding bearing segments. Sliding bearings are known from various fields of application, for example, as disclosed in CN 1 07 930 775 B, for the support of millstones. However, the force collectives and dynamic conditions are completely different from those of a wind turbine. A radial bearing comprises several radial bearing segments, and an axial bearing comprises several axial bearing segments. The bearing is hydrodynamic, whereby a fluid lubricant is introduced at a sufficiently high pressure by means of a pump during operation of the bearing, or a correspondingly high lubricant pressure develops due to the geometry of a lubrication gap into which the lubricant is introduced.This led to the formation of a load-bearing lubricant film over which the rotor shaft is supported. With such hydrodynamic plain bearings, the bearing segments must be replaced when worn for maintenance purposes, which is a considerable undertaking, as access to the relevant bearing segments is sometimes difficult.

[0005] The invention is based on the problem of providing an improved hydrodynamic rotor shaft sliding bearing for a rotor shaft of a wind turbine.

[0006] To solve the problem, in a rotor shaft sliding bearing of the type mentioned above, it is provided according to the invention that the bearing segments are arranged on a support structure which consists of several struts connected to form a truss structure.

[0007] Unlike the prior art, where a closed bearing ring, usually designed as a single-piece metal component, is used as the bearing housing, on which the bearing segments, which can also be called bearing pads, are arranged, the invention provides a quasi-cage-like truss structure that forms the support structure on which the bearing segments are arranged. This support or truss structure consists of a plurality of struts connected to each other and to the bearing segments. It is therefore a strut or rod structure and consequently an open, cage-like structure that is open in both the axial and radial directions. Such an open structure according to the invention can be realized in such a hydrodynamic sliding bearing because the bearing pads only engage the rotor shaft locally and are positionally fixed, i.e.,Unlike rolling bearings, a continuous, closed raceway is not required across the support structure. The truss structure ultimately forms a kind of "ring shape," meaning it is completely closed, as the individual bearing segments must be arranged on a circular path to position them around the circumference of the rotor shaft. However, if primarily elongated struts are used, the "ring shape" is a closed, yet polygonal, structure. The support structure designed according to the invention as a truss structure, built from struts designed and dimensioned according to the specific truss configuration, is significantly lighter as an open structure compared to a closed, one-piece metal bearing ring made of solid material.Nevertheless, sufficient stiffness of the support structure can easily be achieved via the truss structure and the strut arrangement, combined with positional accuracy of the hydrodynamic bearing segments arranged on the support structure, positioned around the circumference of the rotor shaft in the assembly position, and acting upon it. The struts, which are preferably made of metal, are dimensioned accordingly depending on the truss design, whereby the truss structure is designed depending on the given bearing situation, such as the bearing size, the loads to be supported, etc., so that the support structure exhibits the required stiffness in both the radial and axial directions. The struts can run virtually arbitrarily in space; they can run axially, i.e., parallel to the longitudinal axis of the rotor shaft, or at any angle to it to achieve the desired stiffness.

[0008] The struts, which, as described, can be of different lengths or also differ in cross-section or thickness, are connected to each other and to the bearing segments by screw connections according to a first embodiment of the invention. For this purpose, corresponding fastening sections are provided on all struts and on the bearing segments. The struts can, for example, have corresponding openings or bores, preferably at their ends, in the area where two adjacent strut ends are connected by means of a through-bolt or threaded stud, which is tightened with nuts. The bearing segments, which regularly have a segment carrier on which the bearing sections interacting with the rotor shaft are provided, can, for example, have internal threaded bores in the segment carrier into which corresponding fastening screws, which pass through an opening or bore, are inserted.The strut to be fastened engages the bore and is screwed in, whereby corresponding openings and bolt or screw connections can, of course, also be provided there. Thus, various fastening options in the form of screw connections are conceivable. Alternatively, according to a second embodiment of the invention, the connection of the struts to each other and to the bearing segments can also be made via welded connections. The metal struts and the metal segment carrier are thus welded together in a suitable manner.

[0009] A rotor shaft is usually supported by several different hydrodynamic plain bearings. Typically, a combination of radial and axial bearings is used, although sometimes only one radial bearing is provided. For longer rotor shafts, however, two radial bearings are usually provided, preferably supporting the rotor shaft radially at its ends, while regularly one axial bearing, which acts bidirectionally, is sufficient, especially when axial loads from both directions need to be supported. According to the invention, it is possible for at least one radial bearing comprising several radial bearing segments and at least one axial bearing comprising several axial bearing segments to be provided as plain bearings, wherein the radial bearing segments are arranged on a first support structure and the axial bearing segments on a second support structure. According to this embodiment, the two different bearings have separate, open, cage-like support structures.Truss structures are used that are not interconnected. The bearing-specific bearing segments are arranged on each of the separate support structures or truss structures; that is, radial bearing segments on a radial bearing truss structure, and axial bearing segments on an axial bearing truss structure. Both the radial and axial bearing segments are positioned around the outer circumference of the rotor shaft. The radial bearing segments support the rotor shaft radially at its outer circumference via the hydrodynamic lubricating film, while the axial bearing segments, with corresponding bearing sections, engage, for example, in a bearing geometry formed on the outer circumference of the shaft, such as an engagement groove that provides axial bearing surfaces, and support the rotor shaft axially via the hydrodynamic lubricating film.This engagement groove can, for example, be machined directly into the outer circumference of the rotor shaft, but it can also be formed by bearing discs that are pushed onto and attached to the outer circumference of the rotor shaft.

[0010] In a further embodiment of this invention, it can be provided that two axially spaced radial bearings, each with radial bearing segments arranged on separate support structures, and an axially spaced thrust bearing are provided. This embodiment is used for longer rotor shafts and allows the rotor shaft to be radially supported at both ends via the separate radial bearings. The thrust bearing, which is spaced from the radial bearings and whose support structure is not connected to the support structures of the radial bearings, is preferably arranged axially between the two radial bearings. However, it can also be positioned upstream of a radial bearing on the rotor side or on the gearbox side.

[0011] An alternative design incorporating different bearing types provides for at least one radial bearing comprising several radial bearing segments and at least one axial bearing comprising several axial bearing segments, with the radial and axial bearing segments arranged on a common support structure. In this variant, the different bearing segments are not arranged on separate support structures or truss structures, but rather on a common support structure or truss structure. This structure is therefore equipped with mounting options for both the radial and axial bearing segments. Consequently, this single, common, cage-like support structure or truss structure is significantly longer axially than two separate support structures.

[0012] In this embodiment of the invention, it is also conceivable that two axially spaced radial bearings, each with its own radial bearing segment, and one axially spaced axially spaced axially from both radial bearings are provided, with the radial bearing segments and the axial bearing segments arranged axially spaced from one another on the common support structure. Thus, here too, two radial bearings with separate radial bearing segments are used for the radial support of longer rotor shafts, while only one axial bearing, preferably bidirectional, is provided for the axial support. The specific radial bearing segments of the two radial bearings are arranged at axially spaced positions on the common truss structure, as are the axial bearing segments. Preferably, the axial bearing segments are arranged axially between the radial bearing segments.

[0013] Each axial bearing preferably has two bearing sections oriented in opposite directions, thus being designed as a bidirectional axial bearing capable of supporting loads in both axial directions. The hydrodynamic lubricating film, over which the rotor shaft is supported, is built up across these bearing sections. For this purpose, the rotor shaft has a suitable bearing geometry. This shaft-side bearing geometry can be formed integrally on the typically conical rotor shaft in the form of a step, a collar, a flange, or a thickening, 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 needs to be attached to the rotor shaft to implement this bearing geometry. Alternatively, it is conceivable that the bearing geometry is implemented in the form of at least one bearing disk attached to the rotor shaft.In this variant, a separate bearing element in the form of a bearing disc is arranged on the rotor shaft and rigidly connected to it, with the bearing disc providing one or both axial bearing surfaces. Alternatively, two axially spaced bearing discs can be provided, between which an engagement groove is formed.

[0014] The invention is explained below with reference to exemplary embodiments and the drawings. The drawings are schematic representations and show: Fig. 1 a schematic representation of a rotor shaft sliding bearing according to the invention of a first embodiment, in a top view, and Fig. 2 A schematic representation of a rotor shaft sliding bearing of a second embodiment according to the invention in a side view.

[0015] Fig. Figure 1 shows a schematic representation of a hydrodynamic rotor shaft plain bearing 1 according to the invention, which serves to support a rotor shaft 2. The rotor shaft 2 is, for example, integrated into the drive train of a generator of a wind turbine and is connected at one end to a hub on which several rotor blades are arranged, and at the other end to a gearbox. As is known, when wind flows towards the rotor shaft, the rotor blades rotate, and this rotation is transmitted via the hub to the rotor shaft, which in turn drives the gearbox and ultimately the generator. The rotor shaft must therefore be supported by suitable bearings, in this case hydrodynamic plain bearings, which in such an application is regularly achieved by at least two radial bearings and at least one axial bearing.

[0016] Fig. Figure 1 shows the basic structure of such a hydrodynamic sliding bearing 3, which in the example shown is a radial bearing 4 comprising several radial bearing segments 6, which can also be referred to as radial pads, preferably distributed equidistantly around the outer circumference 5 of the rotor shaft 2. The radial bearing segments 6 are fixedly mounted on a support structure 7, which is designed as a truss structure 8, i.e., as an open, cage-like structure. It consists of a plurality of separate struts 9, which are connected both to each other and to the axial bearing segments 6. The struts 9 are preferably made of metal and, in the example shown, have different lengths, as well as different orientations in space to form the cage-like, open truss structure 8. The struts 9 extend both axially, i.e., parallel to the longitudinal axis of the rotor shaft 2, and at different angles to it, as Fig. Figure 1 clearly shows. The truss structure 8 is fixed in position, preferably bolted, to a suitable support 10, for example a base frame of a nacelle of the wind turbine.

[0017] The struts 9 have fastening sections at their ends (not shown in detail) by which the struts 9 are connected to each other at their ends and are also attached to the radial bearing segments 6. The radial bearing segments 6 have corresponding segment carriers 11 on which the actual bearing sections 12 are arranged. The hydrodynamic lubricating film, over which the rotor shaft 2 is radially supported, is formed in each of these sections. Fastening is preferably achieved via screw connections; that is, the struts 9 are screwed to each other as well as to the respective segment carriers 11. The fastening sections of the struts include, for example, through-holes, with two struts abutting each other at their ends so that the through-holes are aligned and a threaded bolt or screw can be inserted and tightened with a nut.Similarly, each segment carrier also has 11 corresponding fastening sections, for example through holes or internal threaded holes.

[0018] As a result of the truss structure and the corresponding spatial arrangement and connection of the struts 9, both among themselves and with the radial bearing segments 6 and their segment carriers 11 respectively, an extremely rigid truss structure is created, which ensures that the individual radial bearing segments 6 are fixed in position on the support structure and are therefore positioned precisely relative to the rotor shaft 2. At the same time, the truss structure 8 is cage-like and open, and therefore lighter than a conventionally used, closed bearing ring, on the inner circumference of which, in the prior art, the radial bearing segments are arranged and which is formed from a solid metal material.

[0019] Although Fig. As Figure 1 shows an exemplary radial bearing 3, the construction of an axial bearing is the same; only the design of the axial bearing segments used differs slightly with regard to their positional sections, since the axial bearing segments are intended to provide axial support, preferably bidirectional support, for the rotor shaft 2. For this purpose, the axial bearing segments, which can also be referred to as axial pads, engage in a suitable bearing structure formed on the rotor shaft 2, for example, a circumferential groove that provides two axial bearing surfaces on which the oppositely oriented bearing sections of the axial bearing segments engage or are supported by the hydrodynamic lubricating film formed over the axial bearing segments. The structure of the support structure 7 in the form of the truss structure 8 is, however, comparable to that of an axial bearing, i.e.,, that the truss structure of such an axial bearing also consists of a large number of separate, interconnected struts, to which the axial bearing segments or their segment carriers are also connected.

[0020] In a rotor shaft bearing arrangement of such a longer rotor shaft, which for example comprises two axially spaced radial bearings and a preferably axially arranged axial bearing between them, all three hydrodynamic sliding bearings can be separate bearings, i.e., they have separate support structures 7 in the form of the truss structures 8 with the radial bearing segments or axial bearing segments arranged thereon.

[0021] As an alternative to such a design with separate plain bearings and correspondingly separate truss structures, it is also conceivable to design the different bearing types, i.e., at least one radial bearing and at least one axial bearing, with a common support structure 7 or a common truss structure 8, i.e., to integrate the radial bearing segments and the axial bearing segments in a common truss structure 8. An example of such a hydrodynamic rotor shaft plain bearing 1 according to the invention is shown. Fig. 2.

[0022] This rotor shaft plain bearing 1 comprises a first radial bearing 4a comprising several first radial bearing segments 6a distributed around the circumference of the rotor shaft (not shown in detail here), which are arranged in a first section 13a of the common truss structure 8, i.e., in the region of the inner circumference of the truss structure 8. A second radial bearing 4b is also provided, which is axially spaced from the first radial bearing 4a. This second radial bearing 3b comprises several separate radial bearing segments 6b, which are arranged in a second section 13b of the common truss structure 8.

[0023] The rotor shaft plain bearing 1 further comprises an axial bearing 14, comprising several axial bearing segments 15, which are also arranged distributed around the circumference of the rotor shaft 2 and the inner circumference of the truss structure 8, respectively. The axial bearing segments 15 are arranged on a third section 13c of the truss structure 8. All three sections 13a, 13b, and 13c are formed by corresponding struts 9, i.e., the common truss structure is again a cage-like, open strut structure. The struts 9 are arranged in the same way as for the Fig. 1 described below and connected to the corresponding radial bearing segments 6a, 6b and the axial bearing segments 15, all of which have corresponding segment carriers, preferably via the described screw connections.

[0024] The three different bearing types are evident, namely the two radial bearings 4a, 4b and the axial bearing 14, or the radial bearing segments 6a, 6b and the axial bearing segments 15 that interact with the rotor shaft 2, all axially spaced apart from each other, so that the respective radial bearing and the axial bearings are located at different length positions of the rotor shaft.

[0025] In the example shown, two radial bearings 4a, 4b and one axial bearing 14 are used. However, it would also be conceivable to combine only one radial bearing and one axial bearing in a common truss structure 8. In the case of supporting a longer rotor shaft, for example, the rotor shaft of a wind turbine, it would be conceivable to arrange such a combined radial-axial bearing in the region of one end of the rotor shaft, and another, separate radial bearing, as shown for the Fig. 1 described, to be arranged at the other end of the rotor shaft.

[0026] As described, the truss structure 8, whether a separate truss structure 8 or a combined truss structure 8, features an open strut structure. This allows, in addition to a correspondingly lightweight construction, a degree of accessibility for maintenance personnel to the individual radial and axial bearing segments, since these are not arranged in a radially outwardly closed bearing housing, but are fixed via the strut structure with radial and axial access. This facilitates simplified maintenance and, if necessary, also simplified replacement, as the radial and axial bearing segments can be detached from their bolted connections to the struts 9 if required. Advantageously, this can be done only locally, meaning that a local disassembly of the connection is easily possible while the rest of the truss structure 8 remains unaffected. Reference symbol list 1 Rotor shaft plain bearing 2 Rotor shaft 3 plain bearings 4, 4a, 4b radial bearings 5 External circumference 6, 6a, 6b Radial bearing segment 7 Support structure 8 Timber frame structure 9 Strut 10 carriers 11 Segment carriers 12 storage section Sections 13a, 13b, and 13c 14 axial bearings 15 Axial bearing segment

Claims

[1] Hydrodynamic rotor shaft bearing for a rotor shaft (2) of a wind turbine, comprising at least one bearing (3) radially or axially supporting the rotor shaft (2) and comprising several hydrodynamic bearing segments (6, 6a, 6b, 15), characterized by , that the bearing segments (6, 6a, 6b, 15) are arranged on a support structure (7) which consists of several struts (9) connected to form a truss structure (8). [2] Hydrodynamic rotor shaft plain bearing according to claim 1, characterized by , that the struts (9) are connected to each other and to the bearing segments via screw connections or via welded connections. [3] Hydrodynamic rotor shaft bearing according to claim 1 or 2, characterized by, that at least one radial bearing (4, 4a, 4b) comprising several radial bearing segments (6, 6a, 6b) and at least one axial bearing (14) comprising several axial bearing segments (15) are provided as sliding bearings, wherein the radial bearing segments (6, 6a, 6b) are arranged on a first support structure (8) and the axial bearing segments (15) are arranged on a second support structure (8). [4] Hydrodynamic rotor shaft plain bearing according to claim 3, characterized by , that two axially spaced radial bearings (4, 4a, 4b) with respective radial bearing segments (6, 6a, 6b) arranged on separate support structures (8), and an axial bearing (15) spaced axially from both radial bearings (4, 4a, 4b), which is preferably arranged axially between the two radial bearings (4, 4a, 4b). [5] Hydrodynamic rotor shaft bearing according to claim 1 or 2, characterized by, that at least one radial bearing (4, 4a, 4b) comprising several radial bearing segments (6, 6a, 6b) and at least one axial bearing (14) comprising several axial bearing segments (15) are provided as sliding bearings, wherein the radial bearing segments (6, 6a, 6b) and the axial bearing segments (15) are arranged on a common support structure (8). [6] Hydrodynamic rotor shaft sliding bearing according to claim 5, characterized by , that two axially spaced radial bearings (4, 4a, 4b) with respective radial bearing segments (6, 6a, 6b) and an axial bearing (14) spaced axially from both radial bearings (4, 4a, 4b), wherein the radial bearing segments (6, 6a, 6b) and the axial bearing segments (15) are arranged axially spaced from each other on the common support structure (8), and wherein preferably the axial bearing segments (15) are arranged axially between the radial bearing segments (6, 6a, 6b). [7] Hydrodynamic rotor shaft bearing according to one of the preceding claims, characterized by , that each axial bearing segment (15) has two bearing sections pointing in opposite directions. [8] Hydrodynamic rotor shaft plain bearing according to one of claims 3 to 7, characterized by , that a bearing geometry on which the axial bearing (15) engages is provided integrally on the rotor shaft in the form of a step, a collar or a thickening, wherein preferably the rotor shaft (2) has a groove in which the bearing section engages to form the step, or that the bearing geometry is realized in the form of at least one bearing disk attached to the rotor shaft (2).

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