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 one plain bearing (3) which supports the rotor shaft (2) radially or axially and comprises a plurality of hydrodynamic bearing segments (6, 6a, 6b, 15), said bearing segments (6, 6a, 6b, 15) being provided on a support structure (7) which consists of a plurality of struts (9) connected to form a framework structure (8).

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 one plain bearing supporting the rotor shaft radially or axially and comprising a plurality of hydrodynamic bearing segments.

[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 sometimes 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 because access to the corresponding bearing segments is sometimes 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, the invention provides that the bearing segments are arranged on a support structure which consists of several struts connected to form a lattice structure.

[0008] Unlike the prior art, where a closed bearing ring, usually designed as a one-piece metal component, is used as the bearing housing, on which the bearing segments, which can also be referred to as bearing pads, are arranged, the invention provides a quasi-cage-like, lattice structure that forms the support structure on which the bearing segments are arranged. This support or lattice structure consists of a plurality of struts connected to one another and to the bearing segments. It is therefore a strut or bar 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 plain bearing, since the bearing pads only act locally on the rotor shaft and are positionally fixed, i.e.that, unlike with rolling bearings, no circumferential, closed raceway needs to be provided over the support structure. The lattice structure ultimately forms a type of "ring shape", i.e. it is closed around its circumference, since the individual bearing segments have to be arranged on a quasi-circular path in order to be able to position them circumferentially around the circumference of the rotor shaft. However, if primarily elongated struts are used, the "ring shape" is a closed, albeit polygonal construct. The support structure designed according to the invention as a lattice structure, constructed from struts designed and dimensioned depending on the given design of the lattice, is considerably lighter as an open structure compared to a closed, one-piece metal bearing ring made of solid material.Nevertheless, sufficient rigidity of the support structure can be easily achieved using 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 assembled position and acting on it. The struts, which are preferably made of metal, are dimensioned accordingly depending on the design of the truss, 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 has the required rigidity in both the radial and axial directions. The struts can run virtually anywhere in space; they can run in the axial direction, i.e. parallel to the longitudinal axis of the rotor shaft, or at any angle to it in order to achieve the desired stiffening.

[0009] The struts, which, as stated, can be of different lengths or can also have different cross-sections or thicknesses, are connected to one another and to the bearing segments by means of screw connections according to a first variant 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 the ends, in the area where two adjoining strut ends are fastened by means of a fastening screw or a threaded bolt that is pushed through and screwed tight using nuts. The bearing segments, which usually have a segment carrier on which the bearing sections that interact with the rotor shaft are provided, can, for example, have internally threaded bores on the segment carrier into which corresponding fastening screws, which pass through an opening or bore, can be inserted.The bolts are screwed into the holes of the strut to be fastened, whereby appropriate 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 variant of the invention, the struts can be connected to each other and to the bearing segments via welded joints. The metal struts and the segment support, which is also metal, are thus welded together in a suitable manner.

[0010] A rotor shaft is usually supported by several different hydrodynamic plain bearings. As a rule, a combination of radial bearings and axial bearings is used, although sometimes only one radial bearing is provided. For longer rotor shafts, however, two radial bearings are usually provided, which preferably support the rotor shaft radially at the ends, while one axial bearing, which acts bidirectionally in particular when axial loads from both axial directions have to be supported, is usually sufficient. 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 the plain bearing, 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 orTruss structures that are not connected to one another. The bearing-specific bearing segments are arranged on each of the separate support structures or truss structures, i.e. the radial bearing segments on a radial bearing truss structure, and the axial bearing segments on a thrust bearing truss structure. Both the radial bearing segments and the axial bearing segments are positioned around the outer circumference of the rotor shaft, with the radial bearing segments supporting the rotor shaft radially on the outer circumference of the shaft via the hydrodynamic lubricating film, while the axial bearing segments engage with corresponding bearing sections, for example in a bearing geometry formed on the outer circumference of the shaft, for example 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 pushed onto the outer circumference of the rotor shaft and fastened thereto.

[0011] In a further embodiment of this invention, two axially spaced radial bearings with respective radial bearing segments arranged on separate support structures can be provided, as well as an axial bearing axially spaced from the two radial bearings. This configuration is used for longer rotor shafts and allows the rotor shaft to be radially supported at both end regions via the separate radial bearings. The axial bearing, which is spaced from the radial bearings and whose support structure is not connected to the support structures of the radial bearing, is preferably arranged axially between the two radial bearings. However, it can also be arranged in front of a radial bearing on the rotor side or the gearbox side.

[0012] An alternative embodiment comprising different bearing types, on the other hand, provides that at least one radial bearing comprising a plurality of radial bearing segments and at least one axial bearing comprising a plurality of axial bearing segments are provided as plain bearings, wherein the radial bearing segments and the axial bearing segments are arranged on a common support structure. In this variant, the different bearing segments are not arranged on separate support structures or truss structures, but on a common support structure or truss structure. This is therefore equipped with fastening options for both the radial bearing segments and the axial bearing segments. This single, common, cage-like support structure or truss structure is therefore, viewed axially, significantly longer than two separate support structures.

[0013] In this embodiment of the invention, it is also conceivable in a further development that two axially spaced radial bearings with respective radial bearing segments and one axial bearing axially spaced from both radial bearings are provided, wherein the radial bearing segments and the axial bearing segments are arranged axially spaced from each other on the common support structure. Here, too, two radial bearings with separate radial bearing segments are used for the radial bearing of longer rotor shafts, while only one axial bearing, preferably acting bidirectionally, is provided for the axial bearing. The specific radial bearing segments of the two radial bearings are arranged at axially spaced positions on the common framework structure, as are the axial bearing segments. In this case, the axial bearing segments are preferably arranged axially between the radial bearing segments.

[0014] Each axial bearing preferably has two bearing sections pointing in opposite directions, i.e., it is designed as a bidirectional axial bearing that can support loads in both axial directions. The hydrodynamic lubricating film, via which the rotor shaft is slide-mounted, is built up via the bearing sections. For this purpose, the rotor shaft has a suitable bearing geometry. This 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; it provides 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, to implement the bearing geometry, no separate bearing element needs to be attached to the rotor shaft. Alternatively, it is conceivable for the bearing geometry to be 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 firmly connected to it. The bearing disc provides one or both axial bearing surfaces. Two axially spaced bearing discs can also be provided, with an engagement groove formed between them.

[0015] The invention will be explained below using exemplary embodiments with reference to the drawings. The drawings are schematic representations and show: Figure 1 shows a schematic diagram of a rotor shaft plain bearing according to the invention of a first embodiment, in a plan view, and

[0016] Figure 2 shows a schematic diagram of a rotor shaft plain bearing according to the invention of a second embodiment in a side view.

[0017] Figure 1 shows a schematic diagram 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 integrated, for example, in 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. When wind flows in, this is known to cause the rotor blades to rotate, which is transmitted via the hub to the rotor shaft, which 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 the case of such an application is usually achieved via at least two radial bearings and at least one axial bearing.

[0018] Figure 1 shows the basic structure of such a hydrodynamic plain bearing 3, which in the example shown is a radial bearing 4, comprising a plurality of radial bearing segments 6, which are preferably equidistantly distributed around the outer circumference 5 of the rotor shaft 2 and can also be referred to as radial pads. The radial bearing segments 6 are held in a fixed position on a support structure 7, wherein the support structure 7 is designed as a lattice structure 8, i.e. as an open, cage-like structure. It consists of a plurality of separate struts 9, which are connected both to one another and to the axial bearing segments 6. The struts 9 are preferably made of metal and, in the example shown, have different lengths, just as they also run differently in space to form the cage-like, open lattice structure 8.The struts 9 run both axially, i.e., parallel to the longitudinal axis of the rotor shaft 2, and at different angles thereto, as clearly shown in Figure 1. The lattice structure 8 is fixed in position, preferably by screwing, to a suitable support 10, for example, a base frame of a nacelle of the wind turbine. The struts 9 have fastening sections at their ends (not shown in detail), via which the struts 9 are connected to one another at their ends, on the one hand, and are fastened to the radial bearing segments 6, on the other hand. The radial bearing segments 6 have corresponding segment supports 11 for this purpose, on which the actual bearing sections 12 are arranged, via which the hydrodynamic lubricating film, via which the rotor shaft 2 is radially mounted, is formed. The fastening is preferably effected via screw connections, i.e., the struts 9 are screwed to one another, as well as to the respective segment supports 11.As fastening sections, the struts have, 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 through, which is then tightened with a nut. Similarly, each segment support 11 also has corresponding fastening sections, for example, through-holes or internally threaded holes.

[0019] As a result of the lattice structure and the corresponding spatial arrangement and connection of the struts 9, both among themselves and with the radial bearing segments 6 or their segment supports 11, an extremely rigid lattice construction is obtained overall, which ensures that the individual radial bearing segments 6 are arranged in a fixed position on the support structure and are therefore arranged in a positionally stable manner relative to the rotor shaft 2. At the same time, the lattice structure 8 is cage-like and open and therefore lighter than a conventionally used, closed bearing ring, on whose inner circumference the radial bearing segments are arranged in the prior art and which is formed from a solid metal material.

[0020] Although Figure 1 shows an example of a radial bearing 3, the structure of an axial bearing is the same, only the design of the axial bearing segments used is slightly different with regard to their bearing sections, since the axial bearing segments are intended to provide axial support, preferably bidirectional support, of 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 bearing sections of the axial bearing segments, pointing in opposite directions, engage or which are supported by the hydrodynamic lubricating film formed by the axial bearing segments. The structure of the support structure 7 in the form of the lattice 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 supports are also connected.

[0021] In the case of a rotor shaft bearing of such a longer rotor shaft, which comprises, for example, two axially spaced radial bearings and an axial bearing preferably arranged axially therebetween, all three hydrodynamic plain bearings can be separate bearings, ie they have separate support structures 7 in the form of the lattice structures 8 with the radial bearing segments or axial bearing segments arranged thereon.

[0022] As an alternative to such a design with separate plain bearings and correspondingly separate framework 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 framework structure 8, i.e., to integrate the radial bearing segments and the axial bearing segments into a common framework structure 8. Figure 2 shows an example of such a hydrodynamic rotor shaft plain bearing 1 according to the invention.

[0023] This rotor shaft plain bearing 1 comprises a first radial bearing 4a comprising a plurality of 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 framework structure 8, i.e., in the region of the inner circumference of the framework structure 8. Furthermore, a second radial bearing 4b is provided, which is axially spaced from the first radial bearing 4a. This second radial bearing 3b comprises a plurality of separate radial bearing segments 6b, which are arranged in a second section 13b of the common framework structure 8.

[0024] The rotor shaft plain bearing 1 further comprises an axial bearing 14, comprising a plurality of axial bearing segments 15, which are also distributed around the circumference of the rotor shaft 2 or the inner circumference of the truss structure 8. 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 connected to one another in the same manner as described for Figure 1, as well as to the corresponding radial bearing segments 6a, 6b and the axial bearing segments 15, which all have corresponding segment supports, preferably via the described screw connections.

[0025] The three different bearing types are visible, i.e. the two radial bearings 4a, 4b and the axial bearing 14 or the radial bearing segments 6a, 6b interacting with the rotor shaft 2 and the axial bearing segments 15, all axially spaced from one another, so that the respective radial bearing and the axial bearings are located at different length positions on the rotor shaft.

[0026] In the example shown, two radial bearings 4a, 4b and one axial bearing 14 are used. However, it would also be equally 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 area of ​​one end of the rotor shaft and to arrange another, separate radial bearing, as described for Figure 1, at the other end of the rotor shaft.

[0027] As described, the truss structure 8, be it a separate truss structure 8 or a common truss structure 8, has an open strut structure. This enables, in addition to corresponding lightweight construction, also a certain degree of accessibility for maintenance personnel to the individual radial and axial bearing segments, since these are not arranged on a bearing housing that is radially closed to the outside, but are fixed via the strut structure in a way that is openly accessible radially and axially. This enables simplified maintenance and, if necessary, simplified replacement, since the radial and axial bearing segments can also be released from their screw connections to the struts 9 if necessary, although this can advantageously only be done locally, i.e. a local release of the connection is easily possible, while the truss structure 8 otherwise remains unaffected.

[0028] List of reference symbols Rotor shaft plain bearing Rotor shaft Plain bearing , 4a, 4b Radial bearing Outer circumference , 6a, 6b Radial bearing segment Support structure Truss structure Strut 0 Support 1 Segment support 2 Bearing section 3a, 13b, 13c Section 4 Axial bearing 5 Axial bearing segment

Claims

Patent claims 1 . Hydrodynamic rotor shaft plain bearing for a rotor shaft (2), in particular of a wind turbine, comprising at least one plain bearing (3) radially or axially supporting the rotor shaft (2) and comprising a plurality of 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 a plurality of struts (9) connected to form a lattice structure (8).

2. Hydrodynamic rotor shaft plain bearing according to claim 1, characterized in that the struts (9) are connected to one another and to the bearing segments via screw connections or welded connections.

3. Hydrodynamic rotor shaft plain bearing according to claim 1 or 2, characterized in that at least one radial bearing (4, 4a, 4b) comprising a plurality of radial bearing segments (6, 6a, 6b) and at least one axial bearing (14) comprising a plurality of axial bearing segments (15) are provided as plain 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 in that two axially spaced radial bearings (4, 4a, 4b) with respective radial bearing segments (6, 6a, 6b) which are arranged on separate support structures (8), and an axial bearing (15) which is axially spaced from both radial bearings (4, 4a, 4b) and is preferably arranged axially between the two radial bearings (4, 4a, 4b).

5. Hydrodynamic rotor shaft plain bearing according to claim 1 or 2, characterized in that at least one radial bearing (4, 4a, 4b) comprising a plurality of radial bearing segments (6, 6a, 6b) and at least one axial bearing (14) comprising a plurality of axial bearing segments (15) are provided as plain 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 plain bearing according to claim 5, characterized in that two axially spaced radial bearings (4, 4a, 4b) with respective radial bearing segments (6, 6a, 6b) and an axial bearing (14) axially spaced 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 one another 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 plain bearing according to one of the preceding claims, characterized in 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 in that a bearing geometry, on which the axial bearing (15) engages, is provided in one piece on the rotor shaft in the form of a step, a collar or a thickening, wherein the rotor shaft (2) preferably 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 fastened to the rotor shaft (2).

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