METHOD FOR APPLYING A BEARING PRELOAD TO A BEARING UNIT AND BEARING UNIT

Description

[0001] The invention relates to a method for applying a bearing preload to a bearing unit and to a bearing unit.

[0002] The storage unit is in particular a large storage unit and specifically a storage unit of a wind turbine and in particular a main bearing of a wind turbine.

[0003] In this context, large bearing units are generally understood to be rolling bearings designed for high load capacities, for example, several tons, and typically having a diameter greater than 0.5 meters, preferably greater than 1 meter, preferably greater than 1.5 meters, and particularly greater than two meters. The diameter is defined as the inner diameter of the (smallest) bearing ring of the large bearing unit.

[0004] The main bearing of a wind turbine is a large bearing unit. It supports the rotor of the wind turbine, which has or is connected to a rotor hub. The individual rotor blades are attached to the hub, capturing the wind energy and transferring it into a rotational movement of the rotor hub. The rotor may have a rotating shaft, for example, and is supported by the main bearing relative to a bearing housing, such as a separate housing or a section of a machine frame. Alternatively, the rotor may be supported by the main bearing relative to a stationary shaft.

[0005] Preloaded spherical bearing arrangements have long been part of the state of the art. They are constructed, for example, from tapered roller bearings or angular contact ball bearings. Spherical bearing arrangements have at least two bearings, which are typically spaced apart axially. Large bearing units in so-called X or O arrangements, each consisting of at least two bearings, are known. In most cases, the preload is applied via a sliding bearing ring. During assembly, this ring is moved axially until the desired preload is achieved. In an O arrangement, the preload is applied by moving an inner ring, while in an X arrangement, it is applied by moving an outer ring.

[0006] Such a prestressed, slanted main bearing unit of a wind turbine can be found in EP 2710271 B1.

[0007] In large bearing units, the bearing seats are typically designed as press fits with a large overpressure to prevent ring creep and thus fretting corrosion and wear in the bearing seat. This means that a relatively large axial force is required to move the bearing rings. In addition, the desired preload force must be applied. The forces required to axially move the bearing ring to generate the desired preload force are applied, for example, by hydraulic presses.

[0008] In rolling bearing technology, shaft nuts (also called slotted nuts) have long been considered state of the art and are defined by various standards (e.g., DIN 981). These shaft nuts are used, for example, to fix rolling bearings axially. In the case of preloaded bearing arrangements such as angular contact ball bearings or tapered roller bearings in X or O configurations, shaft nuts are also used to introduce a defined bearing preload into the system.

[0009] These types of shaft nuts have a metric or trapezoidal thread on their inner diameter. Applying a defined torque to the nut can generate an axial force for preloading a bearing. Alternatively, the nut can be rotated through a defined angle to create a defined preload path determined by the thread pitch.

[0010] Shaft nuts are primarily used for small bearings with diameters of up to a few hundred millimeters, as the required preload forces are relatively low and easily applied. A tightening torque that can be applied using standard methods is sufficient.

[0011] In bearing applications with large bearings, i.e., diameters greater than 0.5 m up to several meters, very high torques are required to achieve the necessary preload force of up to several hundred kN, sometimes even several thousand kN, via a nut. In addition to the preload force, high frictional forces in the bearing seat must also be overcome, as such bearing rings are often designed with a strong press fit. If the nut needs to be adjustable under operating load, for example, during the operation of a wind turbine with a mounted and possibly rotating hub, even higher forces are required.

[0012] EP 3 489 534 B1 describes a shaft nut for adjusting the preload of a main bearing in a wind turbine, incorporating a special thread geometry to reduce friction. This allows the required tightening torque for applying or changing the bearing preload to be reduced. However, very high tightening torques are still required, necessitating an expensive and large tightening tool.

[0013] From EP 2 278 180 B1, which discloses the features of the preamble of claims 1 and 13, the adjustment of a bearing preload using a hydraulic clamping device can be seen. A clamping ring is first attached to the shaft by means of screws. A piston is hydraulically pressed against a bearing ring and the bearing ring is hydraulically fixed in the desired position.

[0014] German patent DE 20 2015 001 277 U1 also describes a hydraulically assisted adjustment of the bearing preload. Hydraulic pressure is applied to a bearing ring via a pressure chamber, thus adjusting it. The resulting axial position is fixed using screws that are supported against a housing body.

[0015] According to US 2,694,430 A, a shaft nut is screwed on and the bearing preload is adjusted. To secure the shaft nut, it has a flexible section that is pushed away from the shaft nut by means of a screw, so that the threaded parts of the shaft nut and the shaft are clamped against each other, thus securing the position.

[0016] Based on this, the invention aims to enable the application of a preload to a bearing unit, in particular a large bearing unit, specifically a wind turbine, using a clamping ring designed, for example, as a shaft nut, whereby only low tightening torques are required for the clamping ring.

[0017] The problem is solved according to the invention by a method for applying a bearing preload to a bearing unit and by a bearing unit. The bearing unit is, in particular, a large bearing unit, specifically of a wind turbine, and especially a main bearing unit of such a wind turbine. The bearing unit extends along an axis of rotation in an axial direction and has at least one adjustable bearing ring, which is axially displaceable along a ring carrier for applying the bearing preload. The ring carrier has a thread, which, at least in one embodiment, is part of an optional threaded element. A threaded clamping ring is provided for applying the bearing preload; this clamping ring can be screwed onto the thread of the ring carrier and thus screwed against the bearing ring.

[0018] Furthermore, in a first step, axial play is set between the bearing ring and the clamping ring and / or between the bearing ring and the threaded element onto which the clamping ring is screwed. The threaded element is attached to a main part of the ring carrier. In general, the first step therefore establishes axial play, i.e., an axial distance between the bearing ring and the clamping ring or the threaded element.

[0019] In the state prior to the first step, the clamping ring is typically already in contact with the bearing ring, meaning it has already been screwed against the bearing ring. It is also possible that axial play exists even before the first step.

[0020] In a further step, the clamping ring is screwed against the bearing ring. Due to the previously set axial play, the clamping ring is unloaded, so that in the subsequent step, the clamping ring can be screwed against the bearing ring without any load. "Unloaded" means that the clamping ring exerts no axial force on the bearing ring. Since the bearing ring is not displaced during this further tightening, only a small torque needs to be applied.

[0021] According to the invention, the bearing preload is applied, i.e., changed, by means of at least one auxiliary clamping element. Various possibilities and variations exist for this purpose. This embodiment with the auxiliary clamping element utilizes the fact that the force required to generate the preload is applied not by the clamping ring, but by means of the at least one auxiliary clamping element. The clamping ring is therefore always rotated without load, meaning that it does not generate / change the preload on the bearing ring during rotation, and in particular, does not increase the preload. After the preload force has been generated and adjusted via the auxiliary clamping element, the clamping ring is typically screwed against the bearing ring, at least bearing against it. The auxiliary clamping element is then typically removed. The set preload force is then held by the clamping ring and thus applied to the bearing ring during subsequent operation.

[0022] An axial force is exerted by means of at least one auxiliary clamping element. To enable this, one, and in particular two, abutments are provided against which the auxiliary clamping element is supported. These abutments are typically connected, at least indirectly, to the bearing ring on one side and the clamping ring on the other, so that the exerted force is transferred to these two components. Alternatively, one or both abutments are formed by the bearing ring and / or the clamping ring.

[0023] To adjust the bearing preload, the bearing ring is axially displaced using the auxiliary clamping element, thus increasing the bearing preload. The auxiliary clamping element therefore exerts an axial force. In principle, the bearing ring can also be displaced in the opposite axial direction in the same way, for example to reduce the bearing preload.

[0024] The advantages and preferred designs listed below in connection with the process can also be applied analogously to the storage unit and vice versa.

[0025] When the term "applying bearing preload" is used here, it refers specifically to setting the preload during the initial assembly of the bearing unit. This also includes adjusting the bearing preload of an already assembled bearing unit, particularly under operational stress, i.e., under load. In a wind turbine, for example, this means that the bearing preload is applied, especially in the assembled state, where the weight of the blades, hub, and rotor shaft acts on the bearing unit. Preferably, the bearing preload is adjusted without rotating the hub, i.e., when the turbine is not in operation in the strict sense.

[0026] The bearing unit is preferably a pre-tensioned, slanted large bearing unit in an X or O arrangement consisting of two spaced-apart bearings as described in the introductory description, such as that described in EP 2 710 271 B.

[0027] Preferably, several auxiliary clamping elements are provided, distributed evenly around the circumference. At least 3, preferably at least 6, 8, or even at least 12 auxiliary clamping elements are provided. The axial force required to generate the axial play is therefore generated successively by these multiple auxiliary clamping elements. These are preferably bolt-shaped, and specifically designed as screw bolts or in the manner of a hydraulic piston in a hydraulic system. The required force is thus generated, for example, mechanically or hydraulically.

[0028] In the preferred embodiment, the clamping ring is a shaft nut with an internal thread, and the ring carrier is designed as a shaft with an external thread at its end. This shaft can be stationary, but is preferably a rotating shaft during operation, which is particularly connected to the hub of a wind turbine. In this embodiment, the bearing ring is therefore typically an inner ring that is adjusted, as is typically the case with an O-arrangement.

[0029] Alternatively, the clamping ring is designed as a ring with an external thread, and the ring carrier is an outer part of the bearing unit surrounding the clamping ring with an internal thread; specifically, this is a bearing housing. In this case, the bearing ring is, in particular, an outer ring that is adjusted to generate the bearing preload, as is typically the case with an X-arrangement.

[0030] According to a preferred embodiment, the axial play is adjusted in the first step using at least one auxiliary clamping element. The auxiliary clamping element therefore has a dual function: firstly, adjusting the axial play, and secondly, generating the preload. Preferably, this occurs simultaneously; that is, when adjusting the axial play, an axial force is exerted on the bearing ring, and in particular, the ring is also displaced. At least in some embodiments, the clamping ring is not rotated to establish the axial play between the bearing ring and the clamping ring.

[0031] According to a preferred embodiment, the bearing unit and the auxiliary clamping element are designed such that the at least one auxiliary clamping element can be supported, at least indirectly, by the clamping ring and is also supported by it during the method for generating the axial play. That is, the clamping ring forms a support for the at least one auxiliary clamping element.

[0032] According to a first preferred variant, the bearing ring is displaced axially in the first step. Thus, the bearing preload is set, and in particular increased, by displacing the bearing ring in the first step. For this purpose, the auxiliary clamping element bears directly against the bearing ring and presses it axially. That is, the bearing ring forms the second abutment.

[0033] Preferably, especially in this first variant, the clamping ring has a through-hole, for example a threaded bore, through which the (respective) auxiliary clamping element is passed. In this case, the clamping ring is therefore directly designed as one of the abutments.

[0034] Preferably, at least one auxiliary clamping element is designed as a screw, preferably with a fine thread. This screw is screwed through the threaded bore in the clamping ring. One end of the screw is preferably supported directly against the bearing ring, so that during a tightening operation an axial force is generated on the bearing ring, pushing it away from the clamping ring in the axial direction and thereby displacing it, thus increasing the bearing preload.

[0035] In a practical design, after the axial play has been adjusted, at least one auxiliary clamping element is loosened and, for example, if it is a screw, turned back or withdrawn in some other way. Generally, this relieves the auxiliary clamping element, and the clamping ring is then free to rotate on the thread of the ring carrier. The clamping ring is then screwed in towards the bearing ring, overcoming the axial play, in particular until it rests against it.

[0036] After the bearing ring has been moved using at least one auxiliary clamping element, the bearing ring remains in the desired axial position, set by at least one auxiliary clamping element, solely due to friction, depending on the current conditions.

[0037] Under certain conditions, particularly under load during operation, at least one locking element is preferably provided to secure the axial position of the bearing ring in the desired position during the process. Preferably, several such locking elements are distributed around the circumference of the bearing ring.

[0038] Preferably, at least one or more locking elements are arranged – preferably only – in (main) load zones where increased stress occurs, especially during operation. A bearing ring is typically subjected to a higher (axial) load in some areas around its circumference than in others. These areas with the higher load constitute the main load zones. Therefore, the locking elements are preferably not arranged uniformly around the circumference.

[0039] The locking element is, in particular, a radial bolt that passes through the ring carrier in a radial direction. The ring carrier therefore has a through-hole through which the locking element can be inserted. The locking element provides frictional and / or positive locking of the bearing ring.

[0040] The thread formed on the ring carrier is, for example, an integral part of a one-piece, particularly monolithic, ring carrier, and is thus, for example, directly applied to the shaft. In a preferred alternative, a separate threaded element is provided, which is attached at its end to a main part of the ring carrier, particularly detachably, e.g., by screws, and forms the ring carrier with this main part. The clamping ring is screwed onto this threaded element.

[0041] According to a second preferred embodiment, in such a design with a threaded element, the threaded element is preferably displaced axially in the first step of adjusting the axial play using the auxiliary clamping element or, alternatively, the clamping ring. Thus, unlike in the first embodiment, the threaded element, and not the bearing ring, is displaced axially in the first step, specifically in the opposite direction to the axial play, so that the axial play between the threaded element and the main part, and thus the bearing ring, is established. For this purpose, the threaded element is loosened beforehand, meaning it is not attached to the main part, so that it can be displaced relative to it.

[0042] According to a first embodiment, the clamping ring, together with the threaded element, is pushed away from the main part of the ring carrier and thus from the bearing ring. This creates the axial play between the bearing ring and the clamping ring. This is achieved, for example, with the aid of a pulling device, in which, for instance, pulling screws are guided through threaded bores in the threaded element and are supported on the main part.

[0043] In this first design, the clamping ring is first offset relative to the bearing ring. It is then screwed back onto the bearing ring.

[0044] According to an alternative second embodiment, the threaded element is pushed away from the main part by means of the clamping ring, i.e., by screwing the clamping ring in the direction of the bearing ring. It is supported against the bearing ring, so that the (loosely guided) threaded element is pushed away and the axial play to the main part and thus to the bearing ring is adjusted.

[0045] In both configurations, the threaded element is then clamped axially against the main part using at least one auxiliary clamping element. The clamping ring rests against the bearing ring and displaces it axially, thus transmitting the axial force.

[0046] The auxiliary clamping element is preferably supported on the threaded element on one side and on the main part of the ring carrier on the other.

[0047] In this version, the clamping ring is then screwed towards the bearing ring, specifically until it rests against it. This process moves the clamping ring further forward axially on the threaded element.

[0048] In a subsequent step, the threaded element is then adjusted axially relative to the ring carrier using the clamping ring. The clamping ring presses against the bearing ring, thus increasing the bearing preload. Therefore, in this second variant, the preload is only applied in this additional step. Auxiliary clamping elements, particularly fasteners such as screws or, alternatively, hydraulic rams, are provided for this purpose. These allow the threaded element to be moved axially towards the main part of the ring carrier.

[0049] These auxiliary clamping elements are preferably also used, for example, for fastening to the main part. Typically, the threaded element is attached to the main part by means of axial screws. These then serve to apply the required preload force and to move the threaded element in the axial direction.

[0050] The steps for adjusting the axial play in the first step and, if necessary, the subsequent free screwing of the clamping ring against the bearing ring, as well as the application of the axial force by means of the auxiliary clamping elements and the resulting displacement of the bearing ring, are preferably repeated in order to successively apply the desired bearing preload.

[0051] Generally, in the first step, an axial play is typically set in the range of several tenths of a millimeter to a few millimeters (maximum 5 mm, preferably maximum 2 mm, and preferably maximum 1 mm). To adjust the bearing preload, the bearing ring is typically offset axially by these values.

[0052] In a preferred embodiment, if necessary, the axial clearance between the clamping ring and the bearing ring is first established, in particular by turning back or loosening the clamping ring. Subsequently, the bearing ring is displaced against the axial direction by means of the auxiliary clamping element, thus reducing the bearing preload.

[0053] In contrast to the two previously described variants, where an increase in bearing preload is set, this method therefore reduces the bearing preload.

[0054] In both variants for increasing bearing preload, the axial force generated by the auxiliary clamping elements is generally transferred to the bearing ring via the clamping ring, which rests against the bearing ring (without rotational movement of the clamping ring).

[0055] Reducing bearing preload involves an axial pulling action on the bearing ring, rather than the axial pushing action required when increasing preload. Both increasing and reducing bearing preload are performed as needed. Reducing bearing preload is particularly important during testing or adjustment procedures, for example, on prototypes.

[0056] The auxiliary clamping elements are preferably designed as screws that can be screwed into corresponding threaded holes in the bearing ring and are also screwed in during adjustment. Their screw heads are supported against a counter-bearing, so that when the screws are turned, the bearing ring is displaced in the opposite axial direction. The counter-bearing is preferably formed by the clamping ring, which has suitable openings / bores through which the auxiliary clamping elements are guided. As an alternative to the screw design, other variants are also possible, in which bolts are positively connected to the bearing ring, for example, in the manner of a bayonet fitting, and are pulled out in the opposite axial direction by means of a release device. In this variant as well, the bolts are preferably guided through bores in the clamping ring and are gripped, for example, by means of the release device.

[0057] Preferably, the clamping ring is designed to accommodate both (first) auxiliary clamping elements for increasing bearing preload and (second) auxiliary clamping elements for reducing bearing preload. In addition to bores, particularly threaded bores for (first) auxiliary clamping elements designed as screws, further simple bores for the (second) auxiliary clamping elements may be provided. The (threaded) bores for the (first) auxiliary clamping elements can also be used simultaneously as bores for the second auxiliary clamping elements, which may then have, for example, a smaller, adapted diameter.

[0058] On the bearing ring side, several receptacles are preferably formed around the circumference, into which the respective (second) auxiliary clamping element can be inserted (screwed in) and / or positively engaged with its tip. The corresponding bores within the clamping ring must be aligned coaxially with these receptacles. This means that the bores within the clamping ring have the same distribution around the circumference as the receptacles in the bearing ring. Coaxial alignment is achieved, for example, by a defined setting of a rotational position of the clamping ring when turning back / loosening.

[0059] To reduce friction between the bearing ring and the ring carrier during axial adjustment, a device with a friction-reducing element is provided and designed, which can be pressed between the bearing ring and the ring carrier. This friction-reducing element is, for example, a liquid lubricant such as oil, which is used, for instance, in the manner of an oil pressure dressing. Alternatively, it is a sliding element.

[0060] Exemplary embodiments of the invention are explained in more detail below with reference to the figures. These show schematic representations of: Fig. 1 a partial sectional view through a bearing unit, specifically a main bearing of a wind turbine, Fig. 2A a top view of a clamping ring designed as a shaft nut, Fig. 2 Legs sectional view along section line AA in Fig 2AFigures 3A to 3D show partial sectional views of the bearing unit in the area of ​​an adjustable bearing ring to illustrate the adjustment of the bearing preload according to a first variant; Figure 4 shows a partial sectional view of the bearing unit in the area of ​​the adjustable bearing ring with a threaded element; Figures 5A to 5B show partial sectional views of the bearing unit in the area of ​​an adjustable bearing ring to illustrate the adjustment of the bearing preload tension according to a second variant; Figures 6A to 6B show partial sectional views in the area of ​​the adjustable bearing ring to illustrate a device for reducing sliding friction; and Figures 7A to 7E show partial sectional views in the area of ​​the adjustable bearing ring to illustrate different variants for securing the axial position of the bearing ring.

[0061] The one in Fig 1The bearing unit 2, shown in a half-section, is designed as an O-arrangement roller bearing. It is, in particular, a main bearing unit for a wind turbine, as described, for example, in EP 2 710 271 B1. The bearing unit 2 comprises a bearing housing 4 as an outer part and a shaft 6 as an inner part. The shaft 6 is designed as a hollow shaft. The bearing housing 4 and the shaft 6 are rotatably mounted to one another via two bearings 8. Depending on the embodiment, either the shaft 6 or the bearing housing 4 rotates about an axis of rotation 10, thus forming a rotor, while the other component forms a stator. In the case of a wind turbine, a hub with rotor blades attached to it is mounted on the rotor, often the shaft 6.

[0062] The two bearings 8 are spaced apart from each other in an axial direction 12, which runs parallel to the axis of rotation 10, by, for example, at least half the bearing diameter. Each of the bearings 8 has an inner ring 14, an outer ring 16, and rolling elements 18. For the two bearings 14, 16, bearing seats are formed at fixed axial positions on the bearing housing 4 and on the shaft 6, respectively, which are defined, for example, by stops for a respective bearing ring 14, 16. In the exemplary embodiment, a total of three of the four bearing rings 14, 16 rest against such a stop. Only one of the bearing rings, namely the inner ring 14 shown on the right half of the image in the exemplary embodiment, is designed as a bearing ring 20 that is adjustable axially in the direction 12. To adjust a bearing preload, this ring is displaced in the axial direction 12. The force generated in this way is transmitted via the bearings, the bearing housing 4, and the shaft 6.

[0063] A clamping ring 22 is provided for adjusting and maintaining the bearing preload; in this embodiment, it is designed as a shaft nut. This clamping ring 22 has an internal thread by which it can be screwed onto a thread 24, which is formed at the end of the shaft 6.

[0064] Since both the bearing housing 4 and the shaft 6 are each designed to accommodate a bearing ring 16, 14, they can also be referred to as ring carriers within the meaning of the present application. Specifically, the shaft 6 forms a ring carrier for the adjustable bearing ring 20. In an X-arrangement, an outer ring 16 would form the adjustable bearing ring 20. In this case, the outer part, i.e., the bearing housing 4, would therefore form the ring carrier for the adjustable bearing ring 20.

[0065] From a top view of the clamping ring 22 in the axial direction 12, it can be seen that it has several threaded holes 26 distributed around its circumference, each with an internal thread. In the exemplary embodiment, 4 threaded holes 26 are shown; preferably, the number is larger and is, for example, more than 8 or even more than 12. The individual threaded holes 26, which are shown in the enlarged view according to the Fig 2B They are clearly visible and each runs in the axial direction 12.

[0066] To adjust the preload according to a first preferred embodiment, screws 28 are provided as auxiliary clamping elements, each of which is screwed into and through a threaded bore 26. The method for adjusting the bearing preload according to this first embodiment is described by reference to the Figures 3A to 3B explains: Fig 3A shows a starting position, as it also appears in the Fig 1The clamping ring 22 is screwed onto the thread 24 and preferably rests against the adjustable bearing ring 20. A dashed guideline indicates the axial zero position of the bearing ring 20.

[0067] In In a first step, the screws 28 are screwed into the threaded bores 26 and tightened so that they exert an axial force on the bearing ring 20 and displace it by an axial play a in the axial direction 12. This increases the bearing preload. This means that the bearing preload is applied in this first step using the auxiliary clamping elements designed as screws 28. The clamping ring 22 remains fixed in its previous axial position and is not rotated.

[0068] In In the next step, screws 28 are loosened again and, in particular, removed, as shown in the Fig 3C is shown.

[0069] The axial play a, set in the first step, and the resulting distance between the bearing ring 20 and the clamping ring 22, allows the latter to rotate freely on the thread 24. In the final step, the clamping ring 22 is screwed further onto the thread 24 in the axial direction 12 until it rests against the bearing ring 20 again. This secures it in its desired axial position.

[0070] Based on the Fig 3B It can be seen that the screw 28 is screwed in until it stops against the clamping ring 22, i.e., until its head rests against the clamping ring 22. This defines a predetermined axial play a. Alternatively, the length of the screw 28 is chosen so that it is not screwed in until it stops. In this case, the axial play a is adjusted by a defined angle of rotation.

[0071] In the Figure 1In sections 3A to 3D, the thread 24 is directly machined into the shaft 6. According to a preferred embodiment, as described in the Fig 4 As shown, a threaded element 30, in particular annular, is provided, which is attached at its end to a main part 32 of the shaft 6 (ring carrier), in particular by means of fastening screws 36. The main part 32 together with the threaded element 30 forms the shaft 6 (ring carrier).

[0072] The adjustment of the bearing preload in a design according to Fig 4 This is done, for example, analogously to the procedure used for the Figures 3A to 3B was described.

[0073] Based on the Figures 5A to 5B A second variant of the method for adjusting the bearing preload is described. This variant builds upon the design with the threaded element 30.

[0074] In this variant, the first step generally involves setting an axial play between the threaded element 30 and the main part 32. For this purpose, fastening elements, specifically the fastening screws 36, which secure the threaded element 30 to the main part 32, are first loosened so that it can be moved relative to the main part 32.

[0075] In this rearward displacement of the threaded element 30, the clamping ring 22 is also displaced rearward according to a first embodiment variant, as shown in the Fig 5B This is illustrated. For this purpose, for example, an additional trigger device, not shown in detail here, is provided, with the help of which the threaded element 30 together with the clamping ring 22 is moved backwards.

[0076] To form this pull-off device, threaded bores are provided through the threaded element 30, through which pull-off elements, such as pull-off screws, are then inserted, bearing against the end face of the main part 32. These threaded bores and the pull-off elements are provided, for example, in addition to the normal fastening screws 36.

[0077] Starting from the position in Fig 5B The clamping ring 22 is then rotated towards the bearing ring 20 until it rests against it. Subsequently, the bearing preload is adjusted by sliding the bearing ring 20 using the auxiliary clamping elements, which are preferably formed by the fastening elements (fastening screws 36).

[0078] For this purpose, the threaded element 30 is moved back towards the main part 32, for example by means of the fastening screws 36, by the axial play a.

[0079] Alternatively to the one in the Fig 5B In the depicted situation, the axial play a is adjusted by rotating the clamping ring 22, which simultaneously bears against the bearing ring 20, thus pushing the threaded element 30 backwards. In this configuration, the clamping ring 22 is therefore continuously in contact with the bearing ring 20.

[0080] Adjusting the bearing preload generally requires axial displacement of the bearing ring 20 on the shaft 6. To minimize friction, a device for reducing (sliding) friction is provided, as schematically illustrated in the Figures 6A to 6B is explained. Figures 6A and 6B This shows a type of oil pressure assembly in which a lubricant, such as oil, is pressed into circumferential annular grooves 28 in a parting plane between shaft 6 and bearing ring 20 at a defined pressure. The annular grooves 28 are either in the shaft 6 ( Fig 6A ) or in bearing ring 20 ( Fig 6B) designed. The lubricant is supplied via radial (oil pressure) bores 40, which are connected to a corresponding pressure device for providing and generating the required lubricant pressure.

[0081] In the first variant, as it relates to the Figures 3A to 3C As explained, under certain conditions securing the axial position is advantageous until the clamping ring 22 is rotated against the bearing ring 20 (see also...). Figures 3C and 3D ).

[0082] To secure the axial position (in the step according to Fig 3C ) is a locking element 44 and preferably several such locking elements 44 are formed distributed around the circumference. This is shown by the Figures 7A to 7E explained in more detail. The safety elements 44 are in accordance with the Figures 7A to 7Din particular designed as bolts or screws, which are preferably guided radially through the (hollow) shaft 6 from the inside. In general, the locking elements 44 secure the axial position of the bearing ring 20 by friction and / or by positive locking. Specifically, the locking elements 44 are screws, as shown in the Figures 7A to 7D as shown. Alternatively, it could also be hydraulically actuated locking elements, such as retractable bolts or friction elements, as is the case, for example, in the embodiment of the Fig. 7E is planned.

[0083] According to the variant of Fig 7A The locking elements 44 are merely clamped against the bearing ring 20, so that only a friction-fit connection is formed. In the variants according to the Figures 7B to 7DA positive locking mechanism is provided in each case, in which the locking element 44 forms a positive locking connection with a portion of the bearing ring 20. Specifically, this portion has recesses or spaces on its underside into which the locking element engages with an end face. Preferably, a section of the underside of the bearing ring 20 is oriented obliquely with respect to the axial direction 12. Alternatively or additionally, the locking element 44 also has an oblique, in particular a conical, tip on its end face. This tip interacts with the obliquely oriented section.

[0084] In the execution variant according to the Fig 7DThe tip of the locking element 44 rests against a chamfered or rounded edge of the bearing ring 20. This edge also forms a chamfered section. Due to the chamfered or rounded design of the respective section and / or the face of the locking element 44, an axial tolerance length is formed over which the positive locking action can be achieved.

[0085] In the execution variant according to the Fig. 7EA friction element, which is preferably ring-shaped and circumferential, is clamped against the bearing ring 20 as a locking element 44. Alternatively, one or more discrete friction elements distributed around the circumference can be used. The at least one friction element has, for example, a friction-enhancing surface / coating, such as a diamond coating. The friction element is clamped against the underside of the bearing ring 20 as required. This can be done mechanically, for example, but preferably hydraulically, as is done in Fig. 7E As shown. Similar to the oil pressure bandage, a bore 40 is provided here as well, through which a fluid is injected and presses the friction element radially outwards.

[0086] Alternatively or additionally to frictional engagement, a positive-locking connection is formed between the at least one friction element and the bearing ring. Specifically for this purpose—but also in the case of a purely frictional connection—a particularly ring-shaped section of the underside of the bearing ring 20, which is arranged opposite the friction element, is preferably specially prepared. For example, a (ring) surface is formed that is preferably set back somewhat from another bearing surface of the bearing ring 20, with which it rests on the ring carrier (shaft 6). This (ring) surface also has, for example, a friction-enhancing surface or is designed for a positive-locking connection. For the positive-locking connection, interlocking projections / indentations, e.g., grooves and slots with a suitable fine structure, are provided.

[0087] In summary, the present invention is based on the principle that the bearing preload is applied by means of the clamping ring 22, which is designed in particular as a shaft nut. To adjust the preload, the auxiliary clamping element, in particular in the form of a screw (28, 36), is used, and an axial play a is initially created. The shaft nut is generally rotatable on its associated threaded component in a state that is virtually load-free, i.e., without preload. The invention includes two main variants: In the first main variant, as described in the Figures 3A to 3DAs shown, the bearing ring 20 is displaced by the axial play a using the auxiliary clamping element. For this purpose, the clamping screw 28 is screwed through the shaft nut and displaces the bearing ring 20. After loosening the auxiliary clamping element / the clamping screws 28, the clamping ring 22 is moved without load towards the bearing ring 20, in particular the shaft nut is screwed without load towards the bearing ring 20.

[0088] In the second main variant, as it relates to the Figures 5A to 5DAs described, the threaded element 30 is provided, onto which the clamping ring 22 (shaft nut) is screwed. Using a puller (not shown) or alternatively with the clamping ring 22, the threaded element 30 is moved so that the axial distance a between the threaded element 30 and the shaft 6 is adjusted. Here too, the shaft nut is rotated without load (either the threaded element is moved by turning the shaft nut against the axial direction 12, or the shaft nut is screwed back towards the bearing ring 20 after the threaded element 30 has been moved). Subsequently, with the shaft nut in contact with the bearing ring 20, the bearing preload is transferred to the bearing ring 20, in particular by means of the fastening screws 36.

[0089] All variants are characterized by the fact that the shaft nut 22 is rotated without load in the direction of the bearing ring 20. This means that no axial force is transmitted to the bearing ring 20 to change the preload during rotation. "Rotating in the direction of the bearing ring" here refers specifically to an axial relative movement of the clamping ring on the bearing ring. Alternatively—especially in the variant with the threaded element 30, which in one variant is axially displaced by rotating the clamping ring 22—"rotating in the direction of the bearing ring" refers to rotation without axial relative movement between the bearing ring and the clamping ring. In all cases, the bearing preload is generated and changed by the auxiliary clamping element and not by the clamping ring. The clamping ring essentially serves only to maintain the bearing preload set by the auxiliary clamping element.

[0090] The invention is not limited to the embodiment described above. Rather, other variants of the invention can also be derived by a person skilled in the art without departing from the subject matter of the invention. In particular, all individual features described in connection with the embodiment can also be combined with one another in other ways without departing from the subject matter of the invention. The invention is defined by the following claims. Reference symbol list

[0091] 2 Bearing unit 4 Bearing housing 6 Shaft 8 Bearing 10 Rotation axis 12 Axial direction 14 Inner ring 16 Outer ring 18 Rolling element 20 Adjustable bearing ring 22 Clamping ring 24 Thread 26 Threaded bore 28 Screw 30 Threaded element 32 Main part 36 Fastening screw 38 Ring groove 40 Bore 42 Sliding element 44 Locking element

Claims

1. Method for applying a bearing preload to a bearing unit (2), in particular a main bearing unit of a wind turbine, wherein the bearing unit (2) extends along an axis of rotation (10) in an axial direction (12) and has a bearing ring (20) which, for the application of the bearing preload, is adjustable along a ring carrier, which is in particular in the form a shaft (6), in the axial direction (12), wherein the ring carrier has a thread (24), which may be part of an optional threaded element (30), and a clamping ring (22), in particular in the form of a shaft nut, is, for the application of the bearing preload, screwable against the bearing ring (20), characterized in that, - in a first step, at least one of the components selected from the clamping ring (22), the bearing ring (20) and the thread (24) or threaded element (30) is moved axially such that, i) in the first step, first of all an axial clearance between the bearing ring (20) and the clamping ring (22) is set and, in a further step, the clamping ring (22) is screwed against the bearing ring (20) without load, or, ii) in a first step, an axial clearance between the bearing ring (20) and the thread (24) or threaded element (30) is set, wherein - the bearing preload is set with the aid of an auxiliary clamping element.

2. Method according to the preceding claim, wherein the bearing ring is moved in the axial direction with the aid of the auxiliary clamping element for setting the bearing preload, and an axial force for setting the bearing preload is transmitted to the bearing ring.

3. Method according to either of the preceding claims, characterized in that the axial clearance is set with the aid of the auxiliary clamping element.

4. Method according to one of the preceding claims, characterized in that the at least one auxiliary clamping element is supported at least indirectly against the clamping ring when the axial clearance is realized and is passed in particular therethrough.

5. Method according to one of the preceding claims, characterized in that, in the first step for setting the axial clearance, the at least one auxiliary clamping element is supported against the bearing ring and exerts a clamping force on, and consequently displaces, the bearing ring in the axial direction.

6. Method according to one of the preceding claims, characterized in that the auxiliary clamping element is a screw and is screwed in particular through the clamping ring.

7. Method according to one of the preceding claims, characterized in that, after the first step for setting the axial clearance, the auxiliary clamping element is loosened again before, in the further step, the clamping ring is screwed against the bearing ring.

8. Method according to one of the preceding claims, characterized in that, after the first step for setting the axial clearance, the axial position of the bearing ring is secured with the aid of at least one securing element, wherein preferably the at least one securing element is a radial pin which is passed through the ring carrier and which secures the bearing ring in a frictionally engaging and / or form-fitting manner.

9. Method according to one of the preceding claims, characterized in that the ring carrier has a main part to which the threaded element is fastened and the clamping ring is screwed onto the threaded element, and in that, in the first step for setting the axial clearance, the threaded element is displaced axially and the axial clearance is set.

10. Method according to the preceding claim, characterized in that the threaded element is displaced axially with the aid of the auxiliary clamping element or alternatively with the aid of the clamping ring, wherein preferably, after the first step, the threaded element is moved together with the clamping ring in the axial direction such that the clamping ring is pressed against the bearing ring and displaces the latter in the axial direction.

11. Method according to one of the preceding claims, characterized in that the steps for setting the axial clearance and for applying the bearing preload with the aid of the at least one auxiliary clamping element are repeated multiple times.

12. Method according to one of the preceding claims, in which, according to requirement, in the first step, the axial clearance between the clamping ring and the bearing ring is formed in particular by turning back / releasing the clamping ring, and in that subsequently the bearing ring is moved counter to the axial direction by means of the auxiliary clamping element to reduce the bearing preload.

13. Bearing unit (2), in particular main bearing unit of a wind turbine, which extends along an axis of rotation (10) in an axial direction (12) and has a bearing ring (20) which, for the application of the bearing preload, is adjustable along a ring carrier in the axial direction (12), wherein the ring carrier has a thread (24), which may be part of an optional threaded element (30), and a clamping ring (22), in particular in the form of a shaft nut, is, for the application of the bearing preload, screwable against the bearing ring (20), characterized in that provision is made of a counterbearing for at least one auxiliary clamping element, against which the auxiliary clamping element can be supported at least temporarily, in such a way that the bearing preload can be applied via the auxiliary clamping element, wherein at least one of the components selected from the clamping ring (22), the bearing ring (20) and the thread (24) or threaded element (30) is able to be moved axially such that, i) in a first step, an axial clearance between the bearing ring (20) and the clamping ring (22) is settable, so that the clamping ring (22) is screwable on the thread (24) of the ring carrier in the direction of the bearing ring (20) without load, or ii) in a first step, an axial clearance between the bearing ring (20) and the thread (24) or threaded element (30) is settable.

14. Bearing unit according to the preceding claim, characterized in that the counterbearing is formed by the clamping ring, and the auxiliary clamping element is able to be passed in particular through the clamping ring.

15. Bearing unit according to either of the two preceding claims, characterized in that a threaded element is fastened to the ring carrier and the clamping ring is screwed onto the threaded element, and in that, for setting the axial clearance, the threaded element is axially displaceable with the clamping ring fastened thereto.