ROTOR BEARING UNIT FOR A WIND TURBINE AND METHOD FOR ADJUSTING THE PRELOAD IN A ROTOR BEARING UNIT

Description

State of the art

[0001] The invention relates to a rotor bearing unit for a wind turbine according to the preamble of claim 1 and a method for adjusting an axial preload in a rotor bearing unit according to the preamble of claim 13.

[0002] Rotor bearings in wind turbines serve, on the one hand, to transfer the power torque from the rotating hub to a generator located in the nacelle. The torque is transferred either directly from the hub to the generator (in a so-called direct drive) or from the hub to an intermediate gearbox acting as a torque-speed converter. On the other hand, the rotor bearings must be designed to transfer the resulting reaction forces and torques via the stationary components of the rotor bearings and the wind turbine into the foundation of the wind turbine.

[0003] Depending on the design of the wind turbine, the rotor bearing is designed with a rotating outer ring or a rotating inner ring, to which the hub is connected. The nacelle of the wind turbine is connected to the other, stationary ring of the rotor bearing. Both grease- and oil-lubricated bearings, with and without water cooling, are known.

[0004] To meet the requirements of a rotor bearing, there are essentially two known designs of rotor bearings. In the so-called moment bearing, as known for example from WO 2012 / 136632 A1, the rotor is supported by a single slewing bearing. In this design, the slewing bearing is usually designed either as a multi-row roller bearing slewing ring or as a double-tapered roller bearing, which, due to their design, are suitable for absorbing both the occurring forces and the moments. However, to ensure sufficient flexural rigidity for absorbing the occurring moments with a single bearing location, particularly large bearing rings are required, especially with high radial ring thicknesses. This makes transport and assembly of the rotor bearing on site more difficult. The bearing rings are usually only surface-hardened in the area of the rolling element raceways.The required high radial ring thickness can be used to create a bolt circle to which the bearing rings are directly screwed to a connecting structure of the hub or nacelle.

[0005] An alternative design for rotor bearings comprises at least two axially spaced slewing bearings whose outer and inner bearing rings are connected to each other via connecting structures. Adjusted tapered roller bearings or locating / loose bearings, for example, can be used as rolling bearings. Bending moments introduced into the rotor bearing are transferred to the load-side rolling bearing via the load-side rolling bearing as a pivot point and the connected connecting structure. The connecting structure acts like a lever, converting the acting moments into radial and / or axial forces acting on the load-side bearing. This bearing concept, known as a two- or multi-point bearing, has the advantage of achieving sufficiently high bending stiffness with comparatively small radial dimensions of the rolling bearings used.In such a bearing arrangement, a case-hardened rolling bearing steel is usually used for the bearing rings and a cast iron part for the connecting structures, onto or into which the bearing rings are installed, forming an interference fit. The installation of the bearing rings is a complex process involving thermal shrinking onto or into the associated connecting structure. Removing the bearing rings is only possible with considerable effort and requires, for example, the use of pressurized oil. However, removing the bearing rings carries the risk of damaging the bearing seats and thus destroying the entire rotor bearing unit. Overall, the power transmission with shrink-fitted rolling bearing rings into the connecting structure, which is usually designed as a cast component, is prone to wear, settling, and cracking.

[0006] To avoid the complex on-site assembly of the bearing rings by shrinking them on, it is known, for example, from EP 2 710 271 B1 to implement the two-point bearing concept in a ready-to-install rotor bearing unit, which has a flange on the connecting structures of the rolling bearings, referred to therein as the stator unit and rotor unit, for connection to the machine frame or hub of the wind turbine. Disadvantages of this design are regularly occurring problems resulting from so-called ring creep and a change in the axial preload of the rotor bearing unit.

[0007] Ring creep is a phenomenon that occurs in press-fitted rings under high operating forces and moments, and is more pronounced with large bearing diameters. The operating forces cause a local weakening of the press fit by bulging the bearing ring and locally displacing the bearing ring relative to the associated connecting structure. Ring creep promotes abrasion and corrosion in the fitting joint, whereby the problem itself is exacerbated over time. This can ultimately lead to bearing damage or the failure of the entire rotor bearing unit. One known measure to reduce ring creep is to enlarge the cross-section of the bearing rings in order to generate a greater contact force in the fitting joint.However, due to the maximum available radial installation space, which is usually specified by the wind turbine manufacturer, the radial ring cross-section can only be increased at the expense of the diameter and / or the length of the rollers used as rolling elements, which leads to a shorter service life of the rotor bearing unit, among other things due to increased rollover numbers.

[0008] The axial preload is an important parameter in the well-known rotor bearing unit and must be adjusted with sufficient precision. If the axial preload is too low or if axial play occurs, the rotor bearing unit loses its flexural rigidity, which can lead to shocks, axial thrust, and even tilting under varying wind loads. This places greater stress on downstream components, such as the gearbox or generator, and negatively impacts their service life and efficiency. Excessive preload adversely affects the load on the bearing components and connecting structures and also leads to increased bearing friction.

[0009] In the solution known from EP 2 710 271 B1, the axial preload is applied to the bearing ring mounted on the stator unit by means of a bearing clamping ring screwed to the stator unit. This adjustment of the preload is, on the one hand, imprecise and prone to errors because the locally generated axial preload depends on the radial contact forces present in the press fit of the bearing ring with the stator unit. Furthermore, it is susceptible to changes due to settlement phenomena during operation. Settling phenomena in the pressing of the bearing clamping ring can lead to a reduction in the axial preload. A further disadvantage of the known method for applying axial preload using a preload ring is that the achieved preload can usually only be determined mathematically from the geometric dimensions of the individual components.Due to the summation of component tolerances, the calculated determination of the achieved preload is only possible with inaccurate precision. A sufficiently accurate control measurement in the assembled state is also not possible. Disclosure of the invention

[0010] The object of the invention is therefore to provide a rotor bearing unit for a wind turbine and a method for adjusting the axial preload in such a rotor bearing unit, by means of which the accuracy of the adjustment of the axial preload is improved, settling phenomena and the susceptibility to maintenance are reduced and the service life of the rotor bearing unit is increased.

[0011] This object is achieved by a rotor bearing unit having the features of claim 1.

[0012] This creates a rotor bearing unit for a wind turbine, which comprises a sleeve-like inner connecting structure that extends along a central axis. The rotor bearing unit further comprises a sleeve-like outer connecting structure arranged coaxially to the inner connecting structure and two tapered roller bearings arranged at a distance from one another, each with at least one inner bearing ring fastened to the inner connecting structure and at least one outer bearing ring fastened to the outer connecting structure. At least one radially extending fastening flange with an axial fastening surface is formed on the inner and / or the outer connecting structure. According to the invention, one of the bearing rings, which has a first bolt circle, is assigned to the fastening flange.The bearing ring assigned to the mounting flange is screwed through the bolt circle into the rotor bearing unit at the axial mounting surface of the mounting flange, introducing an axial preload.

[0013] In the rotor bearing unit according to the invention, the inner and outer connecting structures with the two tapered roller bearings form a preload circle, which is closed by mounting the bearing ring assigned to the mounting flange. The axial screw connection of the bearing ring simultaneously secures the bearing ring to the connecting structure and introduces an axial preload predetermined by an undersize between the inner and outer connecting structures. The identical axial direction of action of the fastening and preload forces of the bearing ring enables a precise adjustment of a predetermined axial preload, unaffected by radial fastening forces, such as those that occur when using a press fit to fasten the bearing ring. This creates a ready-to-install rotor bearing unit with preloaded tapered roller bearings, designed for the highest cyclic loads.

[0014] The screwed mounting of the bearing ring is also advantageous because the mechanical fixation of the bearing ring prevents ring creep, thus reliably preventing it even under the highest loads. Corrosion on the mounting surface of the bearing ring and the resulting adjustment of the axial preload are thus reduced by the inventive assembly of the rotor bearing unit, thereby reducing the rotor bearing unit's maintenance requirements and extending its service life.

[0015] The screw connection is preferably designed to fully transmit the forces and moments acting on the screwed bearing ring during operation of the wind turbine via the tapered roller bearing of the screwed bearing ring. The screw connection is thus located in the force flow of the rotor bearing unit to transfer the operational forces of the wind turbine to the tower or foundation of the wind turbine. The screw connection preferably forms the sole attachment of the bearing ring to the associated connecting structure, which enables particularly simple assembly and disassembly of the bearing ring.

[0016] In preferred embodiments, the fastening flange is arranged at an axial end of the associated connecting structure, and the connecting structure terminates with the axial fastening surface in the axial direction. In this case, the connecting structure associated with the bolted bearing ring ends at the radial flange, so that the connecting structure, in particular, does not have a section that encompasses the bearing ring or supports it in the radial direction. The connecting structure, which is usually designed as a cast component, therefore has a particularly simple geometry that only needs to be finished to size in the area of the flat fastening surface. Furthermore, the overall height of the rotor bearing unit in the area of the tapered roller bearing is reduced in the radial direction to the radial dimension of the bearing ring.A height disadvantage caused by the reinforcement of the ring for the arrangement of the first bolt circle can thus be compensated for by omitting a section of the connecting structure that encompasses the bolted bearing ring. Furthermore, with the same height, larger rollers can be used as rolling elements to optimize the service life of the rotor bearing unit. The rotor bearing unit is characterized by a particularly high static and dynamic load capacity, which is particularly advantageous for large hubs.

[0017] Preferably, the bearing rings of the tapered roller bearings have an inner diameter of more than 3 meters and particularly preferably of more than 5 meters.

[0018] Furthermore, the fastening flange is preferably arranged on the connecting structure on the side radially remote from the other connecting structure. This arrangement of the fastening flange facilitates the assembly of the bolted bearing ring. Furthermore, embodiments of the rotor bearing unit with particularly low radial heights are possible, in which the sleeve-like inner or outer connecting structure has a larger inner or smaller outer diameter than the inner or outer rings of the tapered roller bearings. The sleeve-like base body of the connecting structures preferably extends as an axial support between the bearing rings within their radial height.

[0019] To set a predetermined axial preload, the mounting surface of the mounting flange can be custom-machined, and the bearing ring can be bolted directly to it. Alternatively, an adapter ring for adjusting the axial preload of the rotor bearing unit can be inserted into the screw connection between the mounting flange and the bearing ring. This has the advantage that the axial preload can be adjusted during assembly and / or in the event of settling during operation by replacing or remachining the adapter ring, without the need to completely disassemble the rotor bearing unit.

[0020] In some embodiments, the tapered roller bearings are arranged in an O-arrangement, the inner connecting structure is designed with at least one mounting flange that is bolted to the inner bearing ring of one of the two tapered roller bearings, and the remaining bearing rings are fastened to the respective associated connecting structure by means of a press fit. In this bearing arrangement, the bearing rings are bolted to an inner bearing ring within the preload circle formed by the bearings and the connecting structures, which inner bearing ring closes the preload circle after assembly of the remaining components. This design combines the advantages of radially small, shrunken bearing rings with the simple and precise adjustment of the axial preload by screwing the last, bolted bearing ring to be assembled.Alternatively, an X arrangement of the tapered roller bearings is also conceivable, in which case at least one of the outer rings is screwed to the outer connecting structure in the manner according to the invention.

[0021] In other embodiments, the tapered roller bearings are arranged in an O-arrangement, the inner connecting structure is formed with two mounting flanges that are bolted to the inner bearing rings of the two tapered roller bearings, and the outer bearing rings are secured in the outer connecting structure by means of a press fit. Alternatively, an X-arrangement of the tapered roller bearings is conceivable, in which case the two outer rings are bolted to the outer connecting structure in the manner according to the invention.

[0022] In further embodiments, the inner and outer connecting structures are each designed with two mounting flanges to which the inner and outer bearing rings of the two tapered roller bearings are bolted. Consequently, both bearing rings of the two tapered roller bearings are bolted to the connecting structures, completely eliminating the need for complex, close-tolerance machining of mating surfaces for a press fit and the assembly of bearing rings by press fitting, for example, by thermal shrinking. This enables easy installation and removal of the bearing rings, even in the field if necessary.

[0023] A further advantage of using at least one, preferably two, fully bolted tapered roller bearings is the modular design. The connecting structures and the tapered roller bearings are connected to one another via bolt circles as standardized interfaces and can be selected separately to suit the specific application. Furthermore, when further developing the rotor bearing unit, no new casting patterns need to be created for the connecting structures, even if changes are made to the bearing rings used, as long as the bolt circle remains unchanged. This makes it easy to use bearings with different support angles, longer rollers, larger diameters, etc., without changing the connecting structures. Conversely, the bearing spacing can be adjusted for the same tapered roller bearings by using longer or shorter connecting structures.The prerequisites for the simple construction of a modular system for different turbine types are thus met.

[0024] Preferably, the bearing ring bolted to the inner or outer connecting structure has an additional bolt circle for fastening the rotor bearing unit in a wind turbine. To accommodate the additional bolt circle, the bolted bearing ring has an increased radial height, which reinforces the bearing ring and increases the flexural rigidity of the rotor bearing unit.

[0025] The object is further achieved by a wind turbine having a tower, a nacelle attached to the tower, and a rotor attached to the nacelle, wherein the rotor is rotatably mounted on the nacelle via a rotor bearing unit according to the invention. The rotor bearing unit according to the invention can be supplied in particular as a ready-to-install unit and mounted in the wind turbine by screwing it to the nacelle and rotor.

[0026] In preferred embodiments, the nacelle and the rotor each have a connecting structure for mounting the rotor bearing unit, and the rotor bearing unit is attached to the nacelle and / or the rotor by screwing the fastening flange to the associated bearing ring. The screws of the screw connection extend through the fastening flange, the bearing ring, and fastening holes in the respective connecting structure. In this case, the screw connection of the bearing ring to the connecting structure simultaneously serves to fasten the rotor bearing unit to the associated connecting structure. The screw connection thus not only transmits the operational forces within the rotor bearing unit, but also simultaneously ensures the transmission of the forces to the adjacent components of the wind turbine.

[0027] In some embodiments, the nacelle and the rotor have a connecting structure for mounting the rotor bearing unit, and the rotor bearing unit is fastened to the nacelle and / or the rotor by means of a second screw connection of the respective connecting structure to a second bolt circle of the bearing ring screwed to the connecting structure.

[0028] In terms of the method, the object is achieved by a method for adjusting an axial preload in a rotor bearing unit according to the invention, in which the axial preload of the rotor bearing unit is determined and, if it deviates from a target range, is adjusted within the target range by installing at least one adjusting ring in the screw connection between the mounting flange and the bearing ring or by remachining the mounting surface. Since the axial mounting surface of the mounting flange not only forms an anchoring point for the bearing ring, but also influences the axial preload of the rotor bearing unit via its axial positioning, the axial preload of the bearing unit can be adjusted by simply remachining the mounting surface and / or inserting a suitable adjusting ring.The appropriate adapter ring can, for example, be selected from a set of prefabricated adapter rings of varying thicknesses or assembled as a ring package from the set of prefabricated adapter rings. This eliminates rework and saves time during assembly. Preferably, the preload is determined in a partially assembled state of the rotor bearing unit before mounting the last, bolted bearing ring by measuring the axial distance between two reference surfaces. The reference surfaces are located on the mounting flange and the other, already mounted bearing ring of the tapered roller bearing, which is formed by mounting the bolted bearing ring.By measuring the partially assembled rotor bearing unit, the axial preload can be determined with particular precision, as tolerances do not need to be calculated; instead, the actual values of the partially assembled rotor bearing unit can be used. Especially considering the fact that the connecting structures, which are usually manufactured as cast parts, are manufactured with significantly larger tolerances than the bearing ring, which is then screwed together, the vast majority of the factors influencing the axial preload are taken into account when measuring in the partially assembled state.

[0029] Alternatively or additionally, the axial preload can be recorded in the assembled state of the rotor bearing unit by a measuring roller inserted as a rolling element in one of the tapered roller bearings, depending on the circumferential angle of the tapered roller bearing. Measuring rollers used as rolling elements are designed to detect the load on the measuring roller in the bearing depending on the position. When measuring the rotor bearing unit in the no-load state, the variance of the measured values over one revolution can be used to conclude that the axial preload is uneven. During use in a wind turbine, time-dependent changes in the measured values at the same position, in particular, can indicate a change in the axial preload that occurred during operation, which may require readjustment of the axial preload.

[0030] Alternatively or additionally, the axial preload in the assembled state of the rotor bearing unit can be determined by means of strain gauges and / or measuring washers on the screw connection by means of a differential measurement over time.

[0031] Further advantageous embodiments can be found in the following description and the subclaims.

[0032] The invention is explained in more detail below with reference to the embodiments shown in the attached figures. Brief description of the drawings

[0033] Fig. 1 schematically shows a wind turbine according to the invention, the rotor of which is rotatably mounted on the nacelle via a rotor bearing unit according to the invention, Fig. 2 schematically shows a first embodiment of the rotor bearing unit according to the invention with two tapered roller bearings, wherein one of the inner bearing rings is screwed to the inner connecting structure with the insertion of an adapter ring, Fig. 3 schematically shows a second embodiment of the rotor bearing unit according to the invention, wherein the inner and outer bearing rings of the tapered roller bearings are screwed to the respectively associated inner or outer connecting structure, Fig. 4 schematically shows a third embodiment of the rotor bearing unit according to the invention, wherein the inner bearing rings of both tapered roller bearings are screwed to the inner connecting structure, Fig. 5 schematically shows a variant of the embodiment according to Fig. 3, whereby the bearing ring screwed to the outer connecting structure has an additional bolt circle for attachment to a connecting structure of a wind turbine. Embodiments of the invention

[0034] In the various figures, identical parts are always provided with the same reference symbols and are therefore usually named or mentioned only once.

[0035] In Fig. 1 a wind turbine 100 is shown with a tower 110, a nacelle 120 attached to the tower 110 and a rotor 130 attached to the nacelle 120. The rotor 130 is rotatably mounted on the nacelle 120 via a rotor bearing unit 1 according to the invention, as described below with regard to the Fig. 2 to 5 shown embodiments are described in more detail.

[0036] In Fig. 2 is a first embodiment of the rotor bearing unit 1 according to the invention for a wind turbine 100 (cf. Fig. 1). The rotor bearing unit 1 comprises a sleeve-like inner connecting structure 2 which extends along a central axis A, a sleeve-like outer connecting structure 3 arranged coaxially to the inner connecting structure 2 and two tapered roller bearings 4, 5 arranged at a distance from one another, each with at least one inner bearing ring 6, 7' fastened to the inner connecting structure 2 and at least one outer bearing ring 8', 9' fastened to the outer connecting structure 3. A radially extending fastening flange 10 with an axial fastening surface 14 is formed on the inner connecting structure 2. A bearing ring 6 of the bearing rings 6, 7', 8', 9' is assigned to the fastening flange 10 and has a first bolt circle 16.The bearing ring 6 assigned to the fastening flange 10 is screwed to the axial fastening surface 14 of the fastening flange 10 through the bolt circle 16, with an axial preload being introduced into the rotor bearing unit 1.

[0037] The tapered roller bearings 4, 5 are in Fig. 2arranged in an O-arrangement. The inner connecting structure 2 is formed with a fastening flange 10, which is screwed to the inner bearing ring 6 of one of the two tapered roller bearings 4, and the remaining bearing rings 7', 8', 9' are fastened to the respective associated connecting structure 2, 3 by means of a press fit. If only one bearing ring in the rotor bearing unit 1 is screwed to the associated connecting structure, the upwind-side bearing ring on the stationary connecting structure is preferably selected for the screw connection because experience has shown that this bearing ring is particularly susceptible to ring migration. In the preferred O-arrangement of the tapered roller bearings, this is the upwind-side inner ring 6.

[0038] The bearing ring 6, like all bolted bearing rings 6, 7, 8, 9 described in this disclosure, is preferably made of an induction-hardenable rolling bearing steel, for example 42CrMo4, and has an induction-hardened bearing raceway for the rolling elements 22. On the shrunken bearing rings 7', 8', 9', the bearing raceways are usually case-hardened along with the entire surface. Induction hardening of the raceways in this case would lead to intolerable hardening distortion due to the small ring cross-section. The use of induction-hardenable rolling bearing steels for the bolted bearing rings 6, 7, 8, 9 has the advantage of better machinability, which makes it easier to machine the bolt circle 16, for example.Induction hardenable rolling bearing steels, in particular 42CrMo4, have high static and dynamic strengths and high notched impact toughnesses, so that high cyclic strengths can be achieved in the bearing areas of the rotor bearing unit 1.

[0039] The screw connection of the bearing ring 6 is designed to withstand the forces generated during operation of the wind turbine 100 (cf. Fig. 1 ) to fully transmit the forces and moments acting on the screwed bearing ring 6 via the tapered roller bearing 4 of the screwed bearing ring 6.

[0040] As in Fig. 2 As shown, the fastening flange 10 is preferably arranged at an axial end of the associated connecting structure 2 and the connecting structure 2 terminates with the axial fastening surface 14 in the axial direction.

[0041] The fastening flange 10 is preferably arranged on the connecting structure 2 on the side radially remote from the other connecting structure 3. A fastening flange on the inner connecting structure 2 therefore preferably extends radially inward, and a fastening flange on the outer connecting structure 3 preferably extends radially outward.

[0042] As also in Fig. 2 As shown, an adjusting ring 15 for adjusting the axial preload of the rotor bearing unit 1 can be inserted in the screw connection between the fastening flange 10 and the bearing ring 6.

[0043] The inner and / or outer connecting structures 2, 3 can additionally have functional attachments 27. These can be, for example, a flange for connecting to the rotor of a generator or to a transmission input on the rotating connecting structure of the rotor bearing unit. Another functional attachment can be, for example, a locking device, by which relative movement of the outer and inner connecting structures can be mechanically blocked.

[0044] In Fig. 3 A second embodiment of the rotor bearing unit 1 according to the invention is shown. In this embodiment, the inner connecting structure 2 and the outer connecting structure 3 are each formed with two fastening flanges 10, 11; 12, 13. The inner bearing rings 6, 7 and the outer bearing rings 8, 9 of the two tapered roller bearings 4, 5 are screwed to the fastening flanges 10, 11; 12, 13.

[0045] In a wind turbine 100 (cf. Fig. 1 ), whose nacelle 120 and rotor 130 each have a connecting structure 160, 170 for mounting the rotor bearing unit 1, the rotor bearing unit 1 can be fastened to the nacelle 120 and / or the rotor 130 by means of the screw connection of the fastening flange 11, 12 to the associated bearing ring 7, 8, wherein screws 18 of the screw connection extend through the fastening flange 11, 12, the bearing ring 7, 8 and fastening bores 19 in the respective connecting structure 160, 170. By using the same screw connection 21 for fastening the bearing ring to the connecting structure and the connecting structure, radial installation space and manufacturing costs are saved.

[0046] The exclusive use of bolted bearing rings 6, 7, 8, 9 simplifies the geometry of the connecting structures 2, 3 in this exemplary embodiment. Axial bolting creates an inner and an outer ring stack consisting of two bearing rings and the inner or outer connecting structure 2, 3 arranged between them. This allows simple casting patterns for the connecting structures 2, 3 to be combined with standard bearings or ready-to-install sealed bearings, allowing developments for new turbine generations to be implemented more quickly. Furthermore, the axial dimensions of the connecting structures 2, 3 are reduced to the area between the tapered roller bearings 4, 5, which offers advantages in production, logistics, assembly, and also in the quality of the cast components. All bearing rings 6, 7, 8, 9 can be easily assembled and disassembled without endangering the rotor bearing unit 1.Rings or connecting structures made of any material can be used on both sides of the bearing rings. To prevent radial displacement of the bearing rings in the screw connection, the axial ring contact surfaces can be blasted and / or coated to increase the coefficient of friction.

[0047] Otherwise, the statements regarding the first embodiment apply accordingly.

[0048] Fig. 4 shows a third embodiment of the rotor bearing unit according to the invention, in which the tapered roller bearings 4, 5 are arranged in an O arrangement, the inner connecting structure 2 is formed with two fastening flanges 10, 11 which are screwed to the inner bearing rings 6, 7 of the two tapered roller bearings 4, 5, and the outer bearing rings 8', 9' are fastened in the outer connecting structure 3 by means of a press fit.

[0049] Otherwise, the statements regarding the first and second embodiments apply accordingly.

[0050] Fig. 5 shows a variant of the second embodiment, in which the bearing ring 8 screwed to the outer connecting structure 3 has a second bolt circle 17 for fastening the rotor bearing unit 1 in a wind turbine 100 (cf. Fig. 1 ). In the case shown, the second bolt circle 17 serves to fasten the rotor bearing unit 1 to the connecting structure 160 of the hub 150. Depending on the position of the screwed bearing ring 6, 7, 8, 9 in the rotor bearing unit and the type of wind turbine, the second bolt circle 17 can also be provided on a screwed inner bearing ring 6, 7 and / or serve for fastening to the other connecting structure 170.

[0051] With the Fig. 5In the variant shown, a wind turbine 100 is created with a rotor bearing unit 1, in which the nacelle 120 and the rotor 130 each have a connecting structure 160, 170 for mounting the rotor bearing unit 1 and the rotor bearing unit 1 is fastened to the nacelle 120 and / or the rotor 130 by means of a second screw connection 20 of the respective connecting structure 160, 170 on the second bolt circle 17 of the bearing ring 8 screwed to the connecting structure 3.

[0052] A separate second bolt circle 17 for connection to the adjacent structure 160, 170 offers particular advantages in terms of flexibility in the design of the adjacent structure 160, 170, since the adaptation of the rotor bearing unit 1 to a given bolt circle of the adjacent structure 160, 170 is easier. Furthermore, the assembly of the rotor bearing unit 1 can be simplified by a separate bolt circle 17, and the guidance of the force flow under operational loads can be optimized.

[0053] The rotor bearing unit is mounted in the Figures 2 to 5shown O-arrangement of the tapered roller bearings 4, 5 in the following steps: First, the bearing rings 7 or 7', 8 or 8' and 9 or 9' are fastened to the respectively assigned connecting structures 2, 3. To do this, the bearing rings 7', 8', 9' to be fastened with a press fit - if available - are first mounted on the associated connecting structure 2, 3 by thermal shrinking. For the correct axial positioning of the bearing rings, shaft shoulders are provided on the connecting structures 2, 3, which form mechanical stops for the bearing rings 7', 8', 9'. The mechanical stops are positioned on the side of the bearing ring 7', 8', 9' in such a way that they can absorb the forces acting on the bearing ring 7', 8', 9' under the effect of the axial preload. If necessary, the shrunk-on or shrunk-in bearing rings 7', 8`, 9' can each be additionally secured by retaining rings 26.

[0054] The remaining bearing rings 7, 8, 9 are screwed to the respective associated flange 11, 12, 13 of the associated connecting structure 2, 3. For this purpose, screws are passed through the bolt circle 16 of the bearing ring 7, 8, 9 and holes in the fastening flange 11, 12, 13. If the screw connection is also intended to fasten the rotor bearing unit 1 to the connecting structure 160, 170 of the hub 150 or nacelle 120, a smaller number of assembly screws can initially be used ex works, which are then replaced by screws 18 during on-site assembly of the rotor bearing unit 1 in the wind turbine. Separate holes (not shown) can also be provided in the bearing ring and connecting structure for the assembly screws.

[0055] The connecting structures 2, 3 with the mounted bearing rings 7, 8, 9 are then inserted into each other and the rolling elements 22 of the rolling bearing 5 are inserted.

[0056] Now the axial preload in the rotor bearing unit 1 is adjusted by determining the axial preload of the rotor bearing unit 1 and, if it deviates from a target range, adjusting it to the target range by fitting an adjusting ring 15 in the last screw connection 21 between the fastening flange 10 and the bearing ring 6 or by remachining the fastening surface 14.

[0057] In the described partially assembled state of the rotor bearing unit 1, the axial preload is determined before mounting the last, bolted bearing ring 6 by measuring an axial distance D between two reference surfaces F1, F2, which are arranged on the mounting flange 10 and the already mounted, other bearing ring 8 of the tapered roller bearing 4, which is formed by the assembly of the bolted bearing ring 6. The preload results - in an O-arrangement of the tapered roller bearings - from the remaining axial undersize of the inner components 2, 6, 7 of the rotor bearing unit 1 compared to the outer components 3, 8, 9, taking into account the geometric dimensions of the last-to-mounted bearing ring 6.

[0058] Preferably, the reference surface F1 is formed by the fastening surface 14 on the fastening flange 10 associated with the bearing ring 6 to be mounted last, and the reference surface F2 is one of the end faces of the other bearing ring 8. Furthermore, the distance D between the reference surfaces F1, F2 is preferably measured at several locations distributed over the circumference of the rotor bearing unit 1 or continuously over the circumference. Depending on the position, the fastening surface 14 can be reworked or the adapter ring 15 can be manufactured accordingly.

[0059] After reworking the mounting surface 14 and / or inserting the adapter ring 15, the rotor bearing unit 1 can be finally assembled by mounting the last bearing ring 6.

[0060] Even after final assembly and / or during operation, the axial preload in the rotor bearing unit 1 can be monitored and readjusted if necessary. For this purpose, the axial preload in the assembled state of the rotor bearing unit 1 can preferably be recorded by a measuring roller 23, which is inserted as a rolling element 22 into one of the tapered roller bearings 4, 5, as a function of the circumferential angle of the tapered roller bearing 4, 5.

[0061] Alternatively or additionally, the axial preload in the assembled state of the rotor bearing unit 1 can be determined by means of strain gauges 24 and / or measuring washers 25 on the screw connection through a differential measurement over time. For this purpose, at least one reference measurement is taken under load after installation of the rotor bearing unit in the wind turbine 100. The results of subsequent measurements under comparable load conditions can then be compared with the reference measurement. If the deviations exceed a permissible maximum, the axial preload is readjusted / readjusted.

[0062] All of the embodiments shown in the figures can also be implemented with an X-arrangement of the tapered roller bearings, within the scope of a skilled person's knowledge. In an X-arrangement, the last bearing ring to be installed, which is bolted, must be attached to the outer connecting structure.

[0063] Furthermore, the skilled person will be aware that the solutions presented in the figures can be used for both internally rotating and externally rotating rotor bearing units with grease or oil lubrication. For this purpose, suitable sealing systems must be provided on the tapered roller bearings of the rotor bearing unit. List of reference symbols

[0064] 1 Rotor bearing unit 2 Inner connecting structure 3 Outer connecting structure 4, 5 Tapered roller bearing 6, 7, 7' Inner bearing ring 8, 8', 9, 9' Outer bearing ring 10, 11, 12, 13 Mounting flange 14 Mounting surface 15 Adapter ring 16 First bolt circle 17 Second bolt circle 18 Screws 19 Mounting holes 20, 21 Screw connection 22 Rolling element 23 Measuring roller 24 Strain gauge 25 Measuring washer 26 Retaining ring 27 Functional attachment 100Wind turbine 110Tower 120Nacelle 130Rotor 140Rotor blade 150Hub 160Connecting structure of the hub 170Connecting structure of the nacelle A Axis of the rotor bearing unit D Distance F1, F2 Reference surface

Claims

1. Rotor bearing unit for a wind turbine (100) comprising a sleeve-like inner connecting structure (2) extending along a central axis (A), a sleeve-like outer connecting structure (3) arranged coaxially to the inner connecting structure (2) and two tapered roller bearings (4, 5) arranged axially spaced from one another, each with at least one inner bearing ring (6, 7, 7') fastened to the inner connecting structure (2) and at least one outer bearing ring (8, 8', 9, 9') fastened to the outer connecting structure (3), wherein at least one radially extending mounting flange (10, 11, 12, 13) with an axial mounting surface (14) is formed on the inner (2) and / or the outer connecting structure (3), characterized in the mounting flange (10, 11, 12, 13) is assigned one of the bearing rings (6, 7, 8, 9), which has a first bolt circle (16) through which the bearing ring (6, 7, 8, 9) assigned to the mounting flange (10, 11, 12, 13) is screwed to the axial mounting surface (14) of the mounting flange (10, 11, 12, 13) while introducing an axial preload into the rotor bearing unit (1).

2. Rotor bearing unit according to claim 1, characterized in that the screw connection is designed to fully transmit the forces and torques acting on the screwed bearing ring (6, 7, 8, 9) during operation of the wind turbine (100) via the tapered roller bearing (4, 5) of the screwed bearing ring (6, 7, 8, 9).

3. Rotor bearing unit according to claim 1 or 2, characterized in that the mounting flange (10, 11; 12, 13) is arranged at an axial end of the associated connecting structure (2; 3) and the connecting structure (2; 3) terminates with the axial mounting surface (14) in the axial direction.

4. Rotor bearing unit according to one of claims 1 to 3, characterized in that the mounting flange (10, 11, 12, 13) is arranged on the connecting structure (2; 3) on the side radially facing away from the respective other connecting structure (3; 2).

5. Rotor bearing unit according to one of claims 1 to 4, characterized in that an adjustment ring (15) is inserted in the screw connection between the mounting flange (10, 11, 12, 13) and the bearing ring (6; 7; 8; 9) for adjusting the axial preload of the rotor bearing unit (1).

6. Rotor bearing unit according to one of claims 1 to 5, characterized in that the tapered roller bearings (4, 5) are arranged in an O arrangement, the inner connecting structure (2) is formed with at least one mounting flange (10, 11) which is screwed to the inner bearing ring (6; 7) of one of the two tapered roller bearings (4; 5), and the remaining bearing rings (7; 6, 8, 9) are fastened to the respectively assigned connecting structure (2, 3) by means of an interference fit.

7. Rotor bearing unit according to one of claims 1 to 6, characterized in that the tapered roller bearings (4, 5) are arranged in an O arrangement, the inner connecting structure (2) is formed with two mounting flanges (10, 11) which are screwed to the inner bearing rings (6, 7) of the two tapered roller bearings (4, 5), and the outer bearing rings (8, 9) are fastened by means of an interference fit in the outer connecting structure (3).

8. Rotor bearing unit according to one of claims 1 to 6, characterized in that the inner (2) and the outer connecting structure (3) are each formed with two mounting flanges (10, 11; 12, 13), to which the inner (6, 7) and the outer bearing rings (8, 9) of the two tapered roller bearings (4, 5) are screwed.

9. Rotor bearing unit according to one of claims 1 to 8, characterized in that the bearing ring (6, 7; 8, 9) screwed to the inner (2) or outer connecting structure (3) has a second bolt circle (17) for fastening the rotor bearing unit (1) in a wind turbine (100).

10. Wind energy installation having a tower (110), a nacelle (120) fastened to the tower and a rotor (130) fastened to the nacelle (120), characterized in that the rotor (130) is rotatably mounted on the nacelle (120) via a rotor bearing unit (1) according to one of claims 1 to 9.

11. Wind energy installation according to claim 10, characterized in that the nacelle (120) and the rotor (130) have a connecting structure (160, 170) for mounting the rotor bearing unit (1) and the rotor bearing unit (1) is fastened to the nacelle (120) and / or the rotor (130) by means of the screw connection of the mounting flange (10, 11, 12, 13) with the associated bearing ring (6, 7, 8, 9), wherein screws (18) of the screw connection extend through the mounting flange (10, 11, 12, 13), the bearing ring (6, 7, 8, 9) and fastening holes (19) in the respective adjacent construction (160, 170).

12. Wind energy installation according to claim 10 with a rotor bearing unit (1) according to claim 9, characterized in that the nacelle (120) and the rotor (130) have a connecting structure (150, 160) for mounting the rotor bearing unit (1) and the rotor bearing unit (1) is fastened to the nacelle (120) and / or the rotor (130) by means of a second screw connection (20) of the respective connecting structure (160, 170) to the second bolt circle (17) of the bearing ring (6, 7, 8, 9) screwed to the connecting structure (2, 3).

13. Method for setting an axial preload in a rotor bearing unit (1) according to one of claims 1 to 9, characterized in that the axial preload of the rotor bearing unit (1) is determined and, in the event of deviation from a target range, is set to the target range by mounting at least one adjusting ring (15) in the screw connection (21) between the mounting flange (10, 11, 12, 13) and the bearing ring (6, 7, 8, 9) or by reworking the mounting surface (14).

14. Method according to claim 13, characterized in that the preload in a partially mounted state of the rotor bearing unit (1) is determined before mounting the screwed bearing ring (6, 7, 8, 9) to be mounted last by measuring an axial distance (D) between two reference surfaces (F1, F2), which are arranged on the mounting flange (10, 11, 12, 13) and the already mounted other bearing ring (7, 6, 9, 8) of the tapered roller bearing (4, 5), which is formed by the mounting of the screwed bearing ring (6, 7, 8, 9).

15. Method according to claim 13 or 14, characterized in that the axial preload in the assembled state of the rotor bearing unit (1) is taken up by a measuring roller (23) inserted as a rolling element (22) in one of the tapered roller bearings (4, 5) as a function of the circumferential angle of the tapered roller bearing (4, 5).

16. Method according to one of claims 13 to 15, characterized in that the axial preload in the assembled state of the rotor bearing unit (1) is determined by means of strain gauges (24) and / or measuring washers (25) on the screw connection by means of a differential measurement over time.