Fluid Film Bearings and Wind Turbines

Abstract

Fluid film bearing and wind turbine. A fluid film bearing, in particular a fluid film bearing for a rotor hub (3) in a wind turbine (1), comprises an inner part (6) supporting a rotating outer part (7), wherein the inner part (6) comprises a plurality of radial pads (8, 9, 28, 29) distributed along the outer circumference of the inner part (6), each of the radial pads (8, 9, 28, 29) having at least one radial pad sliding surface (10, 30, 31), wherein the radial pad sliding surface (10, 30, 31) supports at least one outer part sliding surface (14, 32, 33) of the outer part (7) in a radial direction.

Description

Technical Field

[0001] The present invention relates to a fluid film bearing, in particular a fluid film bearing for a rotor hub in a wind turbine, the fluid film bearing comprising an inner part supporting a rotating outer part. The present invention also relates to a wind turbine. Background Art

[0002] A wind turbine typically comprises a tower, a nacelle mounted on top of the tower and a rotor hub with mounted rotor blades, which can rotate relative to the nacelle to generate electricity. The hub can be coupled to a gearbox driving a generator, or the wind turbine can be a direct drive turbine. In the second case, the hub directly drives the rotor of the generator. In particular in direct drive wind turbines, it can be advantageous to use a rotor that is arranged outside the stator and directly coupled to the hub. In this case, the arrangement of the rotor and the hub needs to be rotatably supported by at least one bearing.

[0003] Document WO 2013 / 034391 A2 discloses a direct drive wind turbine using a single sliding bearing. In this bearing, a plurality of closely spaced pads are mounted on a rotating outer ring of the bearing connected to a hub. The concave sliding surfaces of these pads slide on the sliding surfaces of the inner components. Details about pads that can be used for such an arrangement are disclosed, for example, in document WO 2018 / 166660 A1.

[0004] Any kind of plain bearing, especially plain bearings for relatively heavy and relatively strongly loaded components such as the hub of a wind turbine, will lead to a certain wear of the sliding surfaces, especially the pads. Although this wear can be reduced by using fluid film bearings instead of ordinary plain bearings, a certain amount of wear is still unavoidable, especially when using hydrodynamic bearings, because the fluid film only builds up in these bearings after a certain rotational speed is reached. This is particularly true because the pads usually have acute angles on the edges of the sliding surface to ensure that their shape matches the sliding surface of the internal component. Therefore, it is generally necessary to replace the pads of such bearings at certain intervals.

[0005] In the bearings discussed previously, such replacement can be problematic because the pads either need to be accessed from the outside of the hub or a dedicated crawl space needs to be provided within the hub to access the pads. Summary of the invention

[0006] It is therefore an object of the present invention to provide a bearing which may allow easier access to the pads, in particular when used as a bearing for a hub in a wind turbine, and which may allow lower wear.

[0007] This problem is solved by the fluid film bearing initially discussed, wherein the inner component comprises a plurality of radial pads distributed along the outer circumference of the inner component, each of the radial pads having at least one radial pad sliding surface, wherein the radial pad sliding surface supports at least one outer component sliding surface of the outer component in a radial direction.

[0008] Using pads mounted to an inner component (which may be particularly static) rather than an outer component (which may be particularly rotatable) allows easier access to the pads, particularly when fluid film bearings are used in wind turbines. In this case, the inner component typically has a nearly tubular shape in the region of the bearing. The inner component thus forms a natural crawling space, or even a larger access space, for personnel to access the walls of the inner component to which the pads may be mounted. As discussed in more detail below, mounting the pads on the inner component may also help avoid sharp angles at the circumferential ends of the radial pad sliding surfaces of the pads, which may also help reduce wear.

[0009] Pads for bearings, such as the radial pads and optional axial pads discussed below, typically include a contact member forming a sliding surface of the pad and a support member for mounting the contact member to the mounting surface. The connection between the contact member and the support member typically allows the contact member to tilt in at least one direction to compensate for slight misalignments and tolerances of internal and external components. The contact member can be connected to the support member, such as by a pivot, a ball-and-socket connection, or a flexible support. Various methods for providing such pads are known in the prior art and will therefore not be discussed in detail. It should be noted that in some cases, only the contact member is considered to be a pad and the support member is considered to be a pad support. Because the connection between the contact member and the support member is not the focus of the present invention, and these components can also be formed as a single piece, such as in the case of a flexible support, the combination of these components will be referred to as a pad.

[0010] The radial pad sliding surfaces, the outer component sliding surfaces, and other sliding surfaces discussed below can be coated to further reduce friction, for example, with babbitt, white metal, polymer, or some other material. Different sliding surfaces can be coated with different materials or the same material. It is also possible to leave some or all of the sliding surfaces uncoated or otherwise surface treated.

[0011] In order to allow smooth rotation of the inner and outer components relative to each other, preferably all used sliding surfaces are substantially parallel to the circumferential direction of the bearing. Due to tolerances during production, misalignment of components, etc., small angles, e.g. less than 1 degree, may occur between the surfaces of the respective sliding surfaces and the circumferential direction.

[0012] In order to provide support in the radial direction, the corresponding radial pad sliding surface and the sliding surface of the external component supported by the radial pad sliding surface need to be arranged at a certain angle to the radial direction. By using sliding surfaces that are orthogonal to the radial direction, purely radial support is achieved. Tilting the sliding surface to a certain extent in the axial direction, also known as a tapered sliding bearing, can allow combined radial support and axial support. The radial pad sliding surface can be arranged, for example, at an angle of 30° to 60° to the radial direction, such as an angle of approximately 45°. By selecting this angle, the relative amount of radial support and axial support can be adjusted. It should be noted that because of the mounting of the pad contact component to the support component as discussed above, the radial pad sliding surface can typically be slightly inclined, for example less than 1° or 5°.

[0013] The outer part may have a plurality of outer part sliding surfaces arranged at an angle to each other. Different radial pads, preferably different radial pad groups, may support different outer part sliding surfaces. It is also possible to use only radial pads to support one or some of the outer part sliding surfaces and to use other pads, in particular axial pads discussed below, to provide axial support to the outer part.

[0014] In a fluid film bearing, it is necessary to provide lubricant to the contact area between the different sliding surfaces. Various methods of this lubrication are known in the prior art and will not be discussed in detail. The lubrication may be, for example, water immersion lubrication, direct lubrication, lubrication by a spray bar or some other kind of lubrication. Preferably, oil is used as a lubricant in the fluid film bearing. The fluid film bearing may preferably be a hydrodynamic bearing, or alternatively a hydrostatic bearing. A combination of these bearing types may also be used, in which some of the pads are lubricated by hydrodynamic lubrication and some of the pads are lubricated by hydrostatic lubrication. In order to avoid excessive leakage of lubricant, the connections between the different components of the bearing are preferably sealed. For simplicity, the seals between the components are not shown or discussed in this application, as the implementation of such seals is well known in the prior art.

[0015] In a fluid film bearing, the support of one sliding surface against another involves an indirect transmission of force, since a thin lubricating film is arranged between the surfaces. In some cases, such as at low rotational speeds in a hydrodynamic bearing, or when the pump supplying the lubricant in a hydrostatic bearing is not running, the respective sliding surfaces may be in direct contact and the support may therefore be achieved by a direct exchange of forces.

[0016] Preferably, the radial pad sliding surface has a convex shape. When the sliding surface has a convex shape, a tangent line at any point of the sliding surface does not intersect the sliding surface. Compared to pads having a sliding surface with a convex shape, such as the prior art pads discussed above, sharp angles at the edges of the radial pad sliding surface are avoided, which can help to increase the service life of the pad.

[0017] Preferably, in a cross-sectional plane orthogonal to the rotational axis of the bearing, the radial pad sliding surface may have the shape of a segment of a circle. Preferably, this is true for each cross-sectional plane orthogonal to the rotational axis intersecting the radial pad sliding surface. The direction of the rotational axis may also be referred to as the axial direction.

[0018] In the cross-sectional plane or planes in question, the outer part sliding surface may have a rounded shape, resulting in similar shapes of the two sliding surfaces and thus in improved support.

[0019] In the case when the outer component has a plurality of outer component sliding surfaces, wherein at least one of the outer component sliding surfaces is supported by a radial pad sliding surface, the inner component may additionally include a first group of axial pads and a second group of axial pads distributed along the circumference of the inner component, each of the axial pads having an axial pad sliding surface, wherein the axial pad sliding surfaces of the first group of axial pads axially support a first one of the outer component sliding surfaces not supported by the radial pad sliding surface, and wherein the axial pad sliding surfaces of the second group of axial pads axially support a second one of the outer component sliding surfaces not supported by the radial pad sliding surface.

[0020] The use of additional axial pads may be particularly advantageous when the outer component sliding surfaces supported by the radial pad sliding surfaces are approximately orthogonal to the radial direction, since in this case the radial pads may provide no axial support or only very limited axial support. At least a portion of the respective outer component sliding surfaces supported by the respective set of axial pad sliding surfaces may be approximately orthogonal to the axial direction, for example, arranged at an angle of at least 80° or at least 85° to the axial direction.

[0021] Preferably, two sets of axial pads support the sliding surface of the outer component lying opposite to each other and / or facing in opposite directions, thus providing axial support in both directions.

[0022] The outer component may form an annular protrusion extending in the radial direction toward the inner component, wherein the outer component sliding surfaces are formed on the radial end of the protrusion and on both axial ends of the protrusion, wherein a first set of axial pads are arranged on one side of the protrusion and a second set of axial pads are arranged on the opposite side of the protrusion in the axial direction. In other words, the axial pad sliding surfaces support the protrusion from both sides, thus providing axial support in both directions. The outer component sliding surfaces formed on the radial ends of the protrusion may be supported by the radial pad sliding surfaces.

[0023] The protrusion forms the outer ring of the bearing. In a cross-sectional plane orthogonal to the circumferential direction of the bearing, the protrusion may particularly have an I-shaped cross section.

[0024] Alternatively, the outer component can form an annular outer segment and two annular protrusions extending in a radial direction from the outer segment toward the inner segment, wherein the outer component sliding surface is formed on the annular outer segment and the inner surfaces of the annular protrusions face each other, wherein the first group of axial pads and the second group of axial pads are arranged between the annular protrusions.

[0025] The radial pad sliding surface can support the external component sliding surface formed on the annular outer section. The axial pad sliding surface of the corresponding group of axial pads can support the corresponding external component sliding surface arranged on the corresponding protrusion. Because the external component sliding surfaces arranged on the protrusion face each other, axial support can be provided in both axial directions.

[0026] The outer section and the two projections may form an outer ring of the bearing which has a U-shaped cross section in a section plane orthogonal to the circumferential direction.

[0027] Preferably, the radial pads are arranged at a different circumferential position than the axial pads. This may allow the bearing to be shorter in the axial direction, since the axial pads do not need to be placed next to the radial pads in the axial direction, but may for example be placed at the same or similar axial position and displaced from the radial pads in the circumferential direction. The gained space in the axial direction may also be used to provide a larger radial pad sliding surface for each radial pad.

[0028] Because the axial pads and radial pads can be placed at similar positions in the axial direction and thus can be arranged in a line in the circumferential direction, this configuration can be considered as a tandem configuration. This configuration can be combined with the U-shaped and I-shaped outer rings discussed above.

[0029] In principle, radial pads and axial pads may alternate in the circumferential direction. However, in wind turbine applications, it may be advantageous to use a relatively small number of radial pads, so that multiple axial pads or different groups of pairs of axial pads may be arranged between a pair of radial pads.

[0030] All axial pads may be arranged at different circumferential positions. Preferably, members of the first and second groups of axial pads may alternate in the circumferential direction. This may be used to further shorten the length of the bearing in the axial direction, in particular when used with a U-shaped outer ring of the bearing as discussed above as the outer component. In this case, for example, the two groups of axial pads may be only slightly offset relative to each other in the axial direction, so that the distance between the two protrusions of the U-shaped ring only needs to be slightly larger than the extension of a single axial pad in the axial direction.

[0031] Each radial pad may have exactly one radial pad sliding surface, wherein a normal to the radial pad sliding surface may be inclined relative to a radial direction, wherein the radial pad sliding surfaces of a first set of radial pads may face a first axial end of the bearing, and wherein the radial pad sliding surfaces of a second set of radial pads may face a second axial end of the bearing.

[0032] The normal to the radial pad sliding surface may be tilted with respect to the radial direction at an angle less than 90° and greater than 0°, preferably at an angle between 30° and 60°, for example at an angle of about 45°. By increasing the tilt angle, a stronger support of the pad in the axial direction is achieved, while decreasing the angle provides stronger support in the radial direction. The tilting of the radial pads towards different ends of the bearing for different sets causes the radial pad sliding surfaces to face different directions. Thus, the two sets of radial pads provide axial support in both directions while still providing radial support.

[0033] The outer component may form an annular protrusion extending in a radial direction toward the inner component and forming two outer component sliding surfaces, wherein normals of the outer component sliding surfaces are inclined relative to the radial direction toward different ends of the bearing, wherein each of the outer component sliding surfaces is supported in an axial direction and in a radial direction by one of a plurality of sets of radial pads, wherein the outer component sliding surfaces face each other or face away from each other.

[0034] The projection can in particular form an outer ring of the bearing which has a tapered I-shaped or U-shaped cross section in a cross-sectional plane orthogonal to the circumferential direction. The outer part sliding surface can in particular be arranged in a V-shape in this cross-sectional plane, either at the axial end of the projection, for example when forming a ring with a tapered I-shape, or in a recess formed by the projection, for example when forming a ring with a tapered U-shape.

[0035] The first set of radial pads may be arranged at a different circumferential position than the second set of radial pads. This may allow the bearing to be shortened in the axial direction, particularly when using a tapered U-shaped outer ring as discussed above, because different sets of pairs of radial pads providing axial support from both sides do not need to be arranged at the same circumferential position, and therefore also do not need to be arranged at different axial positions, but may be arranged in tandem along the circumference of the inner component.

[0036] The external component may be formed, in particular cast, as one piece and comprise a hub for a wind turbine. This may simplify the assembly of the wind turbine and potentially reduce the necessary amount of material and thus in particular the weight of the bearing and the hub. In addition, the external component may be attached to the hub of the wind turbine, for example by a flange connection.

[0037] The outer ring of the bearing, which may be formed by a protrusion of an external component as discussed above, may be a forged steel ring, which may be hardened to obtain a surface resistant to wear and damage, for example. Alternatively, it may be a cast iron ring, which may be coated with a coating to obtain a surface resistant to wear and damage. Other implementations are also possible.

[0038] The radial pads and / or the axial pads may be mounted to the body of the inner component by inserting the respective radial pad or axial pad between a support structure formed by the body and the respective outer component sliding surface, or by inserting the respective radial pad or axial pad into a respective opening of the body, which is opened on the respective outer component sliding surface, and fixing a base plate or some other support structure supporting the respective pad to the back side of the body facing away from the respective sliding surface. The proposed attachment for the pads allows the pads to be easily repaired and / or replaced, in particular when used in a wind turbine, and will be discussed in more detail later.

[0039] The invention also relates to a wind turbine comprising a rotor having a rotor hub, which is connected to a further component of the wind turbine using a fluid film bearing according to the invention, wherein the hub is part of an external component or an external component mounted to the fluid film bearing. The connection between the hub and the external component is preferably torsion-proof. The connection between the internal component and the further component is preferably also torsion-proof. Further components may be, for example, a nacelle of the wind turbine and / or a stator of a generator. Preferably, the external component is also connected to the rotor of the generator via a torsion-proof connection to provide a directly driven wind turbine or an input stage to a gearbox.

[0040] The hub may be connected to further components by just one bearing. The fluid film bearing in question is well suited as the sole bearing for supporting the hub of a wind turbine. A single bearing arrangement may reduce the complexity and cost of the wind turbine. If multiple bearings are used, the fluid film bearing according to the invention may be used as the main bearing closest to the hub.

[0041] The hub and / or the inner component and / or the further components may form an interior space allowing personnel to access the inner component, wherein the radial and / or axial pads are mounted to one or more further components of the inner component in such a way that personnel can replace them from within the interior space.

[0042] With regard to the installation and replacement of pads, two exemplary options will be discussed. In a first configuration, the pad is moved to its final position or removed from the position in a direction substantially parallel to the sliding surface of the respective pad. For example, an axial pad having an axial pad sliding surface substantially orthogonal to the axial direction of the bearing can be replaced by pulling the pad out in the radial direction or by inserting the pad in the radial direction. Radial pads that essentially provide pure radial support, for example, pads having a radial pad sliding surface substantially orthogonal to the radial direction can be placed in the final position or removed from the position in the axial direction. The advantage of this method is that the respective pad can be inserted between a fixed support structure and a sliding surface of an external component, thereby forming a kind of sandwich in which the back side of the pad is supported by a fixed surface.

[0043] However, it may also be advantageous to be able to remove or place at least some of the pads in a direction approximately orthogonal to the sliding surface of the respective pad. This may be achieved, for example, by providing an opening in the support structure carrying the pad that extends to the sliding surface of the external component, inserting the pad into the opening, and securing the pad in the opening by securing a plate or some other support member of the pad to the material around the opening. This may be useful, for example, for removing a pad when forces from the sliding surface of the external component act on the respective pad. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. However, the accompanying drawings are only schematic diagrams designed for illustrative purposes and do not limit the present invention. The accompanying drawings show:

[0045] Figure 1 is an exemplary embodiment of a wind turbine according to the present invention, comprising an exemplary embodiment of a fluid film bearing according to the present invention,

[0046] Figure 2 yes Figure 1 A perspective view of the internal components of the bearing is shown.

[0047] Figure 3 yes Figure 1 The general shape of the radial pads used in the bearings shown, and

[0048] Figures 4 to 13 are detailed views of various further embodiments of a fluid film bearing according to the invention, which may be used in embodiments of a wind turbine according to the invention. DETAILED DESCRIPTION

[0049] Figure 1A detailed view of a wind turbine 1 is shown, which comprises a rotor hub 3, which is rotatably connected to a further component 5 of the wind turbine 1 using a fluid film bearing 2. The hub 3 is mounted to an outer part 7 of the bearing 2 using a torque-proof connection. For example, a flange connection may be used. Alternatively, the hub 3 and the outer part 7 may be formed (e.g. cast) as a single piece.

[0050] The outer part 7 is also connected to the structure 4 using a torsion-proof connection. The structure 4 may be used to carry the rotor of the generator of the wind turbine 1. For the sake of simplicity and clarity, Figure 1 The rotor is not shown.

[0051] The inner part 6 of the bearing has an annular shape and can be formed in one piece with the further component 5 or connected thereto using a torque-proof connection. The further component 5 can in particular be or carry a stator of a generator of the wind turbine 1, which is not shown for the sake of simplicity and clarity.

[0052] Because the focus of the present invention is on the implementation of the various sliding surfaces 10, 14 and 16-19, details regarding fluid film bearing lubrication, such as seals and a pump that may optionally be used to deliver the lubricant, are omitted from the drawings.

[0053] In order to radially support the outer component 7, the inner component 6 comprises a plurality of radial pads 8, 9 distributed along the outer circumference of the inner component. In principle, a uniform distribution of radial pads 8, 9 along the circumference can be used. However, it may be advantageous to use a non-uniform distribution, for example, because the main load in the radial direction is usually caused by the gravity acting on the hub 3.

[0054] Each of the radial pads 8, 9 has a respective radial pad sliding surface 10, which supports an outer part sliding surface 14 of the outer part 7 in the radial direction. The sliding surfaces 10, 14 can, for example, be coated to improve the robustness of the sliding surfaces and / or to further reduce friction. Although the sliding surfaces 10, 14 are not usually in direct contact during normal operation, because a thin lubricant film is arranged between the sliding surfaces 10, 14, contact between the sliding surfaces 10, 14 can occur, for example, at slow rotation or when a pump for conveying lubricant is not working.

[0055] The radial pad sliding surface 10 does have a convex shape, especially in Figure 2 and Figure 3 Seen in Figure 2 and Figure 3 A schematic diagram showing the general shape of the inner part 6 without the outer part 7 and the individual radial pads 8, 9 is shown. Figure 3 As shown, in a cross-sectional plane orthogonal to the axial direction of the bearing, the radial pad sliding surface 10 at least approximates the shape of a segment 15 of a circle. Figure 1 In the figure, the axial direction coincides with the horizontal direction.

[0056] The convex shape of the radial pad sliding surface 10 closely matches the shape of the outer component sliding surface 14 (which is at least approximately circular in the same cross-sectional plane). Another advantage of using a convex surface is that sharp angles at the edges 24, 25 of the radial pad sliding surface 10 are avoided. This can help reduce wear of the radial pad sliding surface 10 and the outer component sliding surface 14.

[0057] about Figure 3 With reference to the general shape of the radial pads 8, 9 shown, it should be noted that pads for bearings, and therefore radial pads 8, 9 and other pads to be described later, typically allow a certain amount of tilting of the sliding surface of the corresponding pad relative to a support member of the pad, which is used to support the pad against a mounting surface or some other mounting point. The sliding surface is typically provided by a contact member mounted to the support member (for example, by a pivot or ball-and-socket connection). Flexible support can also be provided for the contact member. In this case, the contact member and the support member can be formed of the same material and connected by a thinner member of the same material to allow a certain amount of flexing. Although some of the examples that follow will show these different components, in general, the exact type of connection between the contact member and the support member is not essential to the discussed features of the radial pads 8, 9, and the features of the axial pads 20-23 to be discussed later. Therefore, in Figures 1 to 3 In some of the following figures, for simplicity, all pads 8, 9, 20-23 are shown as a single piece of material.

[0058] In reference Figures 1 to 3 In the example discussed, the radial pads 8, 9 are radially inserted into through holes 12 of the body 11 of the inner part 6 of the bearing. Preferably, they comprise a base plate 13, which can be screwed or bolted to the body 11. Since the radial forces exerted on the radial pad sliding surface 10 must be absorbed by the connecting elements for connecting the base plate 13 to the body 11, it is preferred to use a plurality of connecting elements distributed around the circumference of the through hole 12, such as a plurality of screws or bolts.

[0059] In the example discussed, the radial pad sliding surface 10 and the outer component sliding surface 14 are substantially orthogonal to the radial direction and can therefore support the outer component 7 and therefore the hub 3 only in the radial direction. In order to provide axial support to the outer component 7 and therefore the hub 3, the outer component 7 has two further sliding surfaces 16, 17, which are substantially orthogonal to the axial direction of the bearing 2. The outer component sliding surface 17 is supported by the axial pad sliding surface 19 of the first set of axial pads 20, 21. The outer component sliding surface 16 is supported by the axial pad sliding surface 18 formed by the second set of axial pads 22, 23. Thus, the outer component 7 is supported in both axial directions.

[0060] exist Figure 1 In the cross-sectional plane shown orthogonal to the circumferential direction of the bearing, the annular outer member 7 has a shape similar to the letter "I" and forms a protrusion extending in the radial direction toward the inner member 6. The outer member sliding surface 14 is formed on the radial end of the protrusion, and the outer member sliding surfaces 16, 17 are formed on the axial ends of the protrusion.

[0061] The axial pads 20-24 can be replaced by radially removing them or inserting them through the through holes 26 of the body 11 of the inner component 6 so that they are sandwiched between the body 11 and the outer component 7. In order to allow for easy maintenance of the radial pads 8, 9 and the axial pads 20-24, the hub and the inner component and further components or subsets of these components can form an internal space 27 to allow personnel to access the inner component 6. As previously mentioned, the radial pads 8, 9 and the axial pads 20-24 are all radially inserted into the body 11 of the inner component 6 and can therefore be easily accessed from such an internal space. As discussed later, for example with reference to Fig.12 and Fig.13 , other methods for mounting the pad may also be used.

[0062] In the examples discussed above, the radial pad sliding surface 10 is substantially orthogonal to the radial direction. Therefore, it is necessary to use additional axial pads 20-23 to achieve axial support for the outer part 7 and, therefore, for the hub 3. Figure 4 An alternative embodiment is shown in which the outer component 7 has a tapered shape, thereby forming two outer component sliding surfaces 32, 33, which are substantially parallel to the circumferential direction of the bearing 2, but arranged at a certain angle to the radial direction and the axial direction of the bearing 2. By using a pair of radial pads 28, 29, in which the respective normals of the respective radial pad sliding surfaces 30, 31 are inclined relative to the radial direction, the pair of radial pads 28, 29 is sufficient to provide both radial support and axial support. A plurality of these pairs of radial pads 28, 29 can be arranged spaced along the circumference of the inner component 6.

[0063] To allow for easy maintenance, the radial pads 28, 29 are mounted in through holes 38, 39 of the body 11 of the inner component 6. As previously mentioned, the base plate 13 may be used to attach the respective pads 28, 29 to the body 11 by bolts, screws or other means.

[0064] Figure 4A more detailed structure of the individual pads 28, 29 is also shown. Each of the pads 28, 29 comprises a support member 36 comprising a base plate 13 for fixing the respective pad 28, 29 to the body 11. The respective sliding surfaces 30, 31 are provided by respective contact members 34, which may, for example, be coated to provide the respective sliding surfaces 30, 31. The connecting section 35 connecting the contact section 34 and the support section 36 may, for example, implement a ball-and-socket connection or some other means to allow a slight tilting of the respective radial pad sliding surface 30, 31. By removing the radial pads 28, 29, as indicated by arrow 37, for example, from Figure 1 The interior space 27 is shown removed so that they can be easily repaired.

[0065] Figure 5 shows a slight variation of the previously discussed embodiment. Since most features are similar to Figure 4 The embodiments shown are identical so the same labels are used for the different components. The main difference between these embodiments is the mounting of the pads 28, 29 to the body 11 of the inner member 6. Although reference is made to Figure 4 The embodiment discussed allows particularly easy removal of the pads 28, 29, since they can be removed even when loaded by forces from an external component via the pad sliding surfaces 30, 31, but has the disadvantage that the fixing means for fixing the respective base plate 13 to the body 11 require support of the pads 28, 29 against any forces exerted by the external component 7 on the radial pad sliding surfaces 30, 31.

[0066] When using Figure 5 In the embodiment shown, the forces applied by the outer part 7 via the radial pad sliding surfaces 30, 31 are directly transmitted to the body 11 of the inner part 6. In this case, the pads 28, 29 cannot move parallel to the axis of the support. Figure 5 As shown by the arrow 37 in FIG. 1 , they are removed orthogonally to the axis. The pads 28, 29 can be removed, for example, through a common opening 40. Figure 1 The interior space 27 is shown close up.

[0067] Figure 6 , Figure 7 and Figure 8 An alternative embodiment is shown, in which different pad sets are used for radial and axial support, which is different from the reference Figures 1 to 3 The main difference between these embodiments is the shape of the outer part 7. Figures 1 to 3 In the embodiment of the present invention, the outer member 7 has an I-shape in a cross-sectional plane orthogonal to the circumferential direction of the bearing 2, but according to Figures 6 to 8 The embodiment of the invention uses an outer part 7 having a U-shape in this cross-sectional plane, which is composed of an annular outer section 41 and two protrusions 42, 43 extending from the annular outer section 41 toward the inner part 6, as shown in FIG. Figure 6 and Figure 7 shown.

[0068] As in the previously discussed embodiments, the radial pads 8, 9 providing radial support for the outer member 7 and the axial pads 20-23 providing axial support are arranged at different positions along the circumferential direction of the bearing 2. This can be seen, for example, from Figure 8 As can be seen clearly in FIG. 6 , the figure shows a perspective view of the inner part 6. Thus, Figure 6 and Figure 7 Cross sections of the bearing 2 at different locations along its circumference are shown to illustrate the interaction of the radial pads 8 and the axial pads 20 , 22 with the outer component 7 .

[0069] like Figure 6 As shown, the outer component sliding surface 14 is formed by an annular outer section 41. The radial pad 8 is mounted to the body 11 of the inner component 6 in substantially the same manner as in the previously discussed embodiments. Because there is a relatively large gap 45 between the protrusions 42, 43 and the radial pad 8, only the radial pad sliding surface 14 interacts with the outer component 7.

[0070] like Figure 7 As shown, the axial pads 20, 22 are sandwiched between a support ring 44 formed by the body 11 of the inner component 6 and corresponding protrusions 42, 43 of the outer component 7. Because there is a sufficiently large gap 46 between the axial pads 20, 22 and the annular outer section 41 of the outer component 7, the axial pads 20, 22 interact only with the protrusions 42, 43 to axially support the outer component 7. The respective axial pad sliding surfaces 18, 19 support the respective outer component sliding surfaces 16, 17. Figure 7 The axial outer member sliding surfaces 16, 17 in the embodiment face each other, and according to Figures 1 to 3 In the embodiment of FIG. 1 , the outer part sliding surfaces 16 , 17 which provide the same function face away from each other.

[0071] Fig. 9 Shown is a reference Figures 6 to 8 Variations of the discussed embodiments. Only a small circumferential section of the bearing 2 is shown, with a portion of the outer component 7 cut away, to show the arrangement of the axial pads 20-22 and one of the radial pad sliding surfaces 10. To improve clarity, the different pads 20-22 are shown in a little more detail, rather than simply as outlines as in the previous examples.

[0072] according to Fig. 9 The main difference between the embodiment of the present invention and the previously discussed embodiment is the different arrangement of the axial pads 20-22. In the previous embodiment, two axial pads 20, 22 are arranged at corresponding circumferential positions, and both axial pads 20, 22 are supported by the support ring 44. Fig. 9The embodiment of the present invention instead places all axial pads 20-22 at different circumferential positions. Thus, the first set of axial pads 20, 21 (whose axial pad sliding surfaces 19 bear against the outer component sliding surface 17) is placed in parallel with the second set of axial pads 22, 23 (whose axial pad sliding surfaces 18 bear against the outer component sliding surface 17). Fig. 9 The outer component sliding surface 16 hidden by the protrusion 42 in the bearing can be located at different circumferential positions. Using only a single axial pad 20-22 at each circumferential position can reduce the width of the bearing, which can be advantageous in some cases.

[0073] For previous reference Figure 4 and Figure 5 A similar reduction in the width of the bearing 2 can also be achieved with the embodiment discussed, which uses two outer member sliding surfaces 32, 33 which are arranged at an angle to both the radial and axial directions, thus supporting the outer member 7 in both the axial and radial directions. Fig.10 and Fig.11 Describing this embodiment, Fig.10 and Fig.11 The cross sections orthogonal to the circumferential direction of the bearing 2 are shown at different circumferential positions. Figure 4 and Figure 5 The same reference numerals are used for components that serve the same or similar purposes.

[0074] and Figure 4 and Figure 5 A first difference of the embodiment shown is the shape of the outer part 7. Instead Figure 4 and Figure 5 Instead of the tapered I-shape shown, the outer part 7 now has a tapered U-shape with two protrusions with tapered ends forming the two outer part sliding surfaces 32, 33. Fig.10 and Fig.11 In the embodiment of FIG. 3 , the outer part sliding surfaces 32 , 33 face each other.

[0075] Due to this arrangement of the outer component sliding surfaces 32, 33, the two radial pads 28, 29 cannot be placed at the same position in the circumferential direction of the bearing 2. Instead, they are displaced a certain distance in the circumferential direction. Preferably, the radial pads are arranged in such a way that Fig.10 The pads are oriented as shown and Fig.11 The pads alternate in the orientation shown.

[0076] Fig.12 A further variation of the fluid film bearing 2 discussed is shown. The overall design of this bearing is similar to that of reference Figures 1 to 3 The bearing in question has an approximately I-shaped outer member 7 supported by radial pads 8 and pairs of axial pads 20, 22. Fig.12 In the example shown, the axial pads 20, 22 and the radial pads 8 are arranged at the same circumferential position. Different circumferential positions can also be used for the radial pads 8 and the axial pads 20, 22, and / or the axial pads 20, 22 for axial support in different directions can be placed at different circumferential positions.

[0077] refer to Figures 1 to 3 Examples and bases discussed Fig.12 The main difference between the embodiments of the present invention is the way in which the axial pads 20, 22 are mounted to the body 11 of the inner component 6. Instead of inserting them radially between the outer component 7 and the body 11, they are inserted into the axial opening 48 of the body 11 and attached to the body 11 via a base plate 13 extending above the opening, for example by fixing the base plate 13 to the body 11 with screws or bolts. This method has been described with reference to Figure 1 The radial pads 8 are discussed.

[0078] The inner part 6 is connected to the further component 5 via a connection 47 located outside the axial pad 20, thus allowing the radial pad 8 and the axial pads 20, 22 to be removed from the inner space 27 in the respective directions indicated by the arrows 37, as shown in reference Figure 1 discussed.

[0079] Fig.13 A further variant of the bearing 2 is shown in FIG. Fig.12 The main difference of the bearing 2 shown is the different mounting of the radial pads 8. Instead of attaching the radial pads by the base plate 13, the support sections 36 of the radial pads 8 are supported directly by the body 11 of the inner component 6. This can be advantageous when it is expected that the radial pads 8 will be strongly loaded, since otherwise these strong loads would have to be supported by the screws or bolts fixing the base plate 13 to the body 11.

[0080] According to Fig.12 Another difference of the embodiment is that the connection element 47 is placed in the additional component 5. Fig.13 In the embodiment shown, the axial pads 20 are therefore located outside the inner space 27 formed by the further component 5 and the bearing 2. Although such an arrangement may make replacement of the axial pads 20 more cumbersome, it may be advantageous in some cases, for example when a further component 5 of small diameter is required.

[0081] Obviously, the features discussed with respect to the various embodiments may be combined in various ways. The connection of the inner and outer components to the various other components of the wind turbine 1 may also vary. For example, the outer component 7 may be formed as one piece with the hub and / or the structure 4, or the outer component 7 may be connected to one or both of these pieces by different connections, such as by flange connections. Correspondingly, the further component 5 and the inner component 6 may be provided as one piece, or they may be connected by flanges, etc.

[0082] Although the present invention has been described in detail with reference to the preferred embodiments, the present invention is not limited to the disclosed examples, and those skilled in the art can derive other variations from the disclosed examples without departing from the scope of the present invention.

Claims

1. A fluid film bearing, comprising an inner part (6) supporting a rotating outer part (7), wherein the inner part (6) comprises a plurality of radial pads distributed along the outer circumference of the inner part (6), each of the radial pads having at least one radial pad sliding surface (10, 30, 31), wherein the outer part (7) has a plurality of outer part sliding surfaces, wherein the radial pad sliding surfaces (10, 30, 31) support at least one of the outer part sliding surfaces of the outer part (7) in a radial direction, wherein the inner part (6) further comprises a first group of axial pads and a second group of axial pads distributed along the circumference of the inner part (6), each of the axial pads having an axial pad sliding surface (18, 19), wherein the axial pad sliding surface (19) of the first group of axial pads axially supports a first one of the outer part sliding surfaces not supported by the radial pad sliding surface (10), and wherein the axial pad sliding surface (18) of the second group of axial pads axially supports a second one of the outer part sliding surfaces not supported by the radial pad sliding surface (10), characterized in that The outer component (7) forms an annular outer section (41) and two annular protrusions (42, 43) extending from the outer section (41) toward the inner component (6) in the radial direction, wherein the outer component sliding surface is formed on the annular outer section (41), and the inner faces of the annular protrusions (42, 43) face each other, wherein the first group of axial pads and the second group of axial pads are arranged between the annular protrusions; The radial pad and / or the axial pad are mounted to the body (11) of the internal component (6) by inserting the corresponding radial pad or axial pad between the support structure formed by the body (11) and the corresponding external component sliding surface, or by inserting the corresponding radial pad or axial pad into the corresponding opening of the body (11), the corresponding opening being opened on the corresponding external component sliding surface, and fixing the bottom plate (13) or some other supporting structure supporting the corresponding pad (8, 9, 20-23, 28, 29) to the back side of the body (11) facing away from the corresponding external component sliding surface.

2. The fluid film bearing according to claim 1, characterized in that: The radial pad sliding surface (10, 30, 31) has a convex shape.

3. The fluid film bearing according to claim 1 or 2, characterized in that: The radial pads are arranged at different circumferential positions than the axial pads.

4. The fluid film bearing according to claim 1 or 2, characterized in that: All axial pads are arranged at different circumferential positions.

5. The fluid film bearing according to claim 1 or 2, characterized in that: Each radial pad has exactly one radial pad sliding surface (30, 31), wherein the normal of the radial pad sliding surface (30, 31) is inclined relative to the radial direction, wherein the radial pad sliding surfaces (30) of a first group of radial pads face the first axial end of the fluid film bearing (2), and wherein the radial pad sliding surfaces (31) of a second group of radial pads face the second axial end of the fluid film bearing (2).

6. The fluid film bearing according to claim 5, characterized in that: The first set of radial pads are arranged at a different circumferential position than the second set of radial pads.

7. The fluid film bearing according to claim 1 or 2, characterized in that: The outer component (7) is formed in one piece and comprises a rotor hub (3) for a wind turbine (1).

8. The fluid film bearing according to claim 1 or 2, characterized in that: The fluid film bearing is used in a rotor hub (3) in a wind turbine (1).

9. The fluid film bearing according to claim 7, characterized in that: The outer part (7) is cast as a single piece.

10. A wind turbine comprising a rotor having a rotor hub (3), the rotor hub (3) being connected to a further component (5) of the wind turbine (1) using a fluid film bearing (2) according to any one of claims 1 to 9, wherein the rotor hub (3) is part of the outer part (7) or is mounted to the outer part (7) of the fluid film bearing (2).

11. The wind turbine according to claim 10, characterized in that The rotor hub (3) is connected to the further component (5) via exactly one fluid film bearing (2).

12. A wind turbine according to claim 10 or 11, characterised in that The rotor hub (3) and / or the inner component (6) and / or the further component (5) form an inner space (27) allowing a person to access the inner component (6), wherein the radial pads and / or the axial pads are mounted to one or more further components of the inner component (6) in such a way that a person can replace them from within the inner space (27).

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