Rolling bearing assembly

Abstract

A rolling bearing assembly (1), in particular in a wind turbine, comprises a bearing ring (5), a surrounding component (2, 3), and an electrically insulating powder coating layer (7) which separates the bearing ring from the surrounding component and has a thickness (d7) of at least 0.05%o and at most 2%o of the joint diameter (Di), wherein the joint diameter is to be measured at the contact surface between the powder coating layer and the circumferential surface of a metal main part of the bearing ring, and the electrically insulating powder coating layer is applied onto the surrounding component.

Description

[0001] Rolling bearing arrangement

[0002] The invention relates to a rolling bearing arrangement with a bearing which is electrically insulated from a further element of the rolling bearing arrangement by a layer of lacquer.

[0003] WO 2013 / 143807 A1 discloses a rolling bearing with an electrically insulating lacquer coating. The insulating lacquer is applied to the side of a bearing disc, bearing sleeve, or bearing bushing that faces a running section and is therefore not subjected to the rolling elements. According to WO 2013 / 143807 A1, it is also conceivable to coat the running side if the lacquer layer is sufficiently stable. WO 2013 / 143807 A1 lists dipping, spraying, and blasting as methods for applying the lacquer; a possible thickness range of 15 to 40 µm is specified.

[0004] German patent DE 10 2011 085 884 B4 relates to a torque transmission device with electrical insulation. The electrically insulating coating material mentioned in this case is ceramic. Specifically, this could be a ceramic layer based on silicon oxide, chromium, and / or chromium nitride. Other coating options mentioned include a layer based on an amorphous carbon structure and / or a lacquer layer.

[0005] German patent DE 10 2019 118 810 A1 addresses the issue of bearing ring migration in the direction of rotation around the axis of rotation of a bearing. As a countermeasure against such migration, which could lead to premature wear, the use of positive-locking components is recommended, which prevent both rotation and axial displacement of a bearing ring.

[0006] Various methods for ceramic coating of rolling bearing components are described, for example, in documents EP 3 239 348 B1, CN 101782106 A and JP 2014-185741 A. A corrosion-protected bearing disclosed in EP 2 463 537 B1 has a surface on which several sheets of a plastic film are bonded directly to a steel part of the bearing, with the plastic films overlapping. The film material can be vinyl, and an acrylic adhesive is used as the adhesive.

[0007] DE 10 2012 221 739 A1 describes a bearing arrangement intended for use in a wind turbine, comprising at least one rolling bearing, namely a tapered roller bearing. The rolling bearing has a first bearing ring connected to the rotor of the wind turbine and a second bearing ring connected to a housing. The first bearing ring connected to the rotor has a cylindrical seating surface with which it sits on a cylindrical section of the rotor. To prevent the bearing ring from being susceptible to cracking, DE 10 2012 221 739 A1 provides for machining the cylindrical seating surface by a hard turning operation. Furthermore, it provides for arranging a ring element made of fiber-reinforced plastic between an end face of the same bearing ring and an end face of a shoulder on the rotor designed for axial contact.

[0008] JP 2007-315585 A proposes the use of a polyamide 9T element to apply a radial force to the bearing ring of a rolling bearing during assembly. The polyamide 9T element is located in an annular groove on the outer circumferential surface of the bearing ring.

[0009] A rolling bearing with an insulating sleeve is known from DE 10 2010 024 582 A1. The insulating sleeve has radially inwardly folded edges on both sides, which engage the outer ring of the rolling bearing. The insulating sleeve serves not only for electrical but also for acoustic insulation of the rolling bearing.

[0010] The invention is based on the objective of providing a rolling bearing arrangement that is further developed compared to the aforementioned prior art by means of an electrically insulating layer, wherein the insulating layer should be producible efficiently and with good reproducibility as well as geometric precision. This objective is achieved according to the invention by a rolling bearing arrangement with the features of claim 1. The rolling bearing arrangement is suitable, among other things, for use in a wind turbine according to claim 9.

[0011] The rolling bearing assembly comprises a bearing ring, an surrounding component, and an electrically insulating powder coating layer separating the bearing ring from the surrounding component. The powder coating layer has a thickness of at least 0.05‰ and at most 2‰ of the joint diameter, the joint diameter being measured at the contact surface between the powder coating layer and a circumferential surface of the bearing ring—more precisely, its metallic base body. In cases where the powder-coated circumferential surface of the metallic base body of the surrounding component is not cylindrical, but, for example, conical or convex, the mean diameter of the corresponding surface is considered the joint diameter. In any case, the surrounding component to which the bearing ring is at least approximately rigidly connected can be, for example, a shaft, another rotating element, or a housing or housing-mounted component of the rolling bearing assembly.Accordingly, the bearing ring can be designed as the inner or outer ring of the rolling bearing assembly. The electrically insulating powder coating is applied to the surrounding component.

[0012] It has been shown that the powder coating, which separates a bearing ring of the rolling bearing arrangement from an surrounding component, not only serves electrical insulation, but also represents an efficient, rationally and reliably implementable measure against bearing ring migration.

[0013] The migration of bearing rings, that is, movements of the bearing ring relative to a component that is essentially rigidly connected to the bearing ring, can generally be attributed to micro-movements of the bearing ring and / or the component connected to it. Such micro-movements of bearing components are caused, for example, by mechanical loads that act on the bearing ring via the rolling elements during operation. For background information on the migration of rolling bearing rings, please refer to the following publication:

[0014] Research Report FVA 479 IV, IGF No. 16985 BR, Research Association for Drive Technology eV, Remedial Measures for Rolling Bearing Wandering, Definition and Design of Constructive and Tribological Remedial Measures against Tangential Wandering Movements of Rolling Bearing Rings, 2015

[0015] Within the scope of the research project, various solutions, including positive-locking solutions, were developed and their effectiveness was investigated experimentally and using complex 3D finite element analyses. A steel intermediate ring, positioned between a bearing ring and an surrounding structure, was examined using simulation and experimentation.

[0016] Such a steel intermediate ring is not a component of the rolling bearing arrangement according to the application. Rather, the function of such a separate ring is at least largely taken over by the powder coating layer located on the surrounding component, whereby the mechanical and electrical properties of the powder coating layer exert additional effects, including a damping effect, which cannot be achieved with a steel ring due to material limitations.

[0017] Applying the powder coating to the surrounding component is possible using various known methods. In particular, the powder coating can be sprayed onto the surface of the base body of the surrounding component. Optionally, the area to be coated with powder coating is a metallic coating of the surrounding component. For the assembly of the bearing rings, it may be necessary to heat the bearing rings – depending on the selected fit. If the required assembly temperature exceeds the thermal resistance of the electrically insulating layer, this could significantly impair the layer or its function. Therefore, it is recommended to apply the relevant layer to the surrounding component(s). For examples of methods for coating metallic components with powder coating, reference is made to DE 198 01 620 C1.Various compositions of powder coating are disclosed, for example, in documents EP 0 696 622 B1 and DE 43 22 437 C1.

[0018] In various possible configurations of the rolling bearing arrangement, the powder coating exhibits a modulus of elasticity of less than 25 GPa. The coefficient of friction p of the powder coating, based on frictional contact with the adjacent metallic surface of the surrounding component, which can be a steel or cast part, is, for example, 0.3 or higher. The dielectric strength of the powder coating can be 5 kV / mm or higher.

[0019] The bearing ring adjacent to the powder-coated surrounding component is, for example, a large bearing ring with thin walls relative to the overall dimensions of the bearing, particularly in a wind turbine. Due to the lower stiffness of the surrounding components compared to other large bearings, thin-walled large bearings can exhibit increased micro-slip. To compensate for these micro-movements, a minimum thickness of the elastic, flow-insulating powder coating is necessary. Layer thicknesses of more than 1‰, based on the diameter of the powder-coated element, measured at the contact surface between the element and the powder coating, combined with a powder coating modulus of elasticity of less than 25 GPa, have proven particularly effective.

[0020] The height of the ring cross-section of the bearing ring can be less than 15% of the outer diameter of the same bearing ring in the rolling bearing arrangement according to the application.

[0021] The rolling bearing assembly is suitable not only for use in wind turbines, for example as rotor main bearings or wind turbine gearbox bearings, but also in other stationary or mobile systems and machines, such as motor vehicles, agricultural machinery, construction machinery, watercraft, or rail vehicles. In all cases, the powder coating applied to the interface between the bearing ring and the surrounding component makes a significant contribution to the wear resistance of the rolling bearing assembly.

[0022] The invention will now be explained in more detail with reference to two drawings. These show:

[0023] Fig. 1 shows a simplified representation of a rolling bearing arrangement with a bearing ring and an surrounding component which is mechanically damped and electrically insulated by means of a powder coating layer.

[0024] Fig. 2 shows a rolling bearing arrangement in a further embodiment, with a bearing ring and an surrounding component which is mechanically damped and electrically insulated by means of a powder coating layer, in a simplified representation.

[0025] A rolling bearing arrangement, designated by reference numeral 1, is designed as an angular contact roller bearing in the embodiment shown in Fig. 1 and is intended for use in a wind turbine (not shown). A shaft 2 is connected to a rotor of the wind turbine. A housing 3 is part of the rolling bearing arrangement 1, but is not considered part of the rolling bearing designated by 4, namely the tapered roller bearing, which is part of the rolling bearing arrangement 1.

[0026] Components of the rolling bearing 4 are an inner ring 5 and numerous rolling elements 6, i.e., tapered rollers, which are guided in a cage (not shown). In the arrangement according to Figure 1, the rolling elements 6 roll directly in the housing 3. In an alternative configuration (not shown), the rolling bearing 4 can include an outer ring as an additional bearing ring, in addition to the inner ring 5. Optionally, a further row of rolling elements 6 is present. Particularly in such cases, there can be multiple inner rings and / or outer rings, or one of the bearing rings 5 ​​can be split. The only bearing shown in Figure 1, i.e., the inner ring 5, has an inner diameter Di and an outer diameter Da. The central axis of the inner ring 5, and thus of the entire rolling bearing arrangement 1, is designated MA. A denotes the height of the ring cross-section of the inner ring 5. The height A thus corresponds to half the difference between the outer diameter Da and the inner diameter Di.In Figure 1, the diameters Da and Di are not shown to scale.

[0027] Between the shaft 2, which is generally referred to as the surrounding component of the rolling bearing assembly 1, and the inner circumferential surface of the metallic base body of the inner ring 5, there is a powder coating layer 7, which has a thickness d? shown exaggerated in Figure 1. The outer diameter of the powder coating layer 7 represents the joint diameter of the rolling bearing assembly 1 and is identical to the inner diameter Di of the inner ring 5.

[0028] The powder coating layer 7 is applied to the surrounding component, here the shaft 5, before the rolling bearing assembly 1 is mounted. The possibility of the powder coating layer 7 extending further than the width of the inner ring 5 is indicated in Figure 1.

[0029] Within the rolling bearing assembly 1, the powder coating layer 7 serves as an electrical insulating layer. Furthermore, the powder coating layer 7 exhibits significant mechanical damping properties. Thanks to these latter properties, the powder coating layer 7 absorbs micro-movements to a technically relevant degree during operation of the rolling bearing assembly 1, thus effectively counteracting any movement of the bearing ring 5 on the shaft 2. If any micro-slip occurs at all, its effects are limited to an extremely low level by the wear resistance provided by the powder coating layer 7 in the mating surface of the rolling bearing assembly 1, and this level does not affect the service life of the rolling bearing assembly 1.

[0030] The powder coating layer 7 can be applied by a spray process and has a

[0031] The elastic modulus is less than 25 GPa. The dielectric strength of powder coating layer 7 is at least 5 kV / mm. The coefficient of friction p of powder coating layer 7 against shaft 2 is greater than 0.3.

[0032] Compared to the overall dimensions of the rolling bearing assembly 1, the inner ring 5 is a relatively thin bearing ring. This is reflected in the fact that the height A of the ring cross-section of the bearing ring 5 adjacent to the surrounding component coated with powder coating 7 is less than 15% of the outer diameter Da of the same bearing ring 5. As can be seen in Figure 1, the height A is to be measured without the powder coating 7.

[0033] Alternatively or in addition to the surrounding component shown in Figure 1, which is in contact with the inner ring 5, another surrounding component, which is in contact with the outer ring of the rolling bearing 4 (not shown), can be coated with a powder coating layer 7 in an analogous manner.

[0034] Figure 2 shows a further embodiment of a rolling bearing arrangement, comprising a bearing ring and an surrounding component which is mechanically damped and simultaneously electrically insulated by means of a powder coating layer. The end faces of the surrounding component can also be at least partially covered by the powder coating layer 7. The thickness of the end-face powder coating layer 7 does not necessarily correspond to the thickness d? on the circumferential surface of the bearing ring 5.

[0035] List of reference signs

[0036] 1 Rolling bearing arrangement

[0037] 2 shaft, surrounding component

[0038] 3 cases

[0039] 4 rolling bearings

[0040] 5 Bearing ring, inner ring

[0041] 6 rolling elements, roller

[0042] 7 powder coating layers

[0043] A Height of the ring cross-section of the inner ring

[0044] The inner diameter of the inner ring, joint diameter

[0045] What is the outer diameter of the inner ring (d)? What is the thickness of the powder coating layer?

[0046] MA Central Axis

Claims

Patent claims 1. Rolling bearing arrangement (1) comprising a bearing (5), an surrounding component (2, 3), and an electrically insulating powder coating layer (7) separating the bearing (5) from the surrounding component (2, 3), which has a thickness (d?) of at least 0.05% and at most 2% of the joint diameter (Di), wherein the joint diameter (Di) is to be measured at the contact surface between the powder coating layer (7) and a circumferential surface of a metallic base body of the bearing ring (5), wherein the electrically insulating powder coating layer (7) is applied to the surrounding component.

2. Rolling bearing arrangement (1 ) according to claim 1 , characterized in that the powder coating layer (7) has a modulus of elasticity of less than 25 GPa.

3. Rolling bearing arrangement (1 ) according to claim 1 or 2, characterized in that the powder coating layer (7) has a coefficient of friction p towards the adjacent metallic surface of the surrounding component (2, 3) of more than 0.

3.

4. Rolling bearing arrangement (1 ) according to one of claims 1 to 3, characterized in that the electrical breakdown strength of the powder coating layer (7) is at least 5 kV / mm.

5. Rolling bearing arrangement (1 ) according to one of claims 1 to 4, characterized in that the height (A) of the ring cross-section of the bearing ring (5) adjacent to the surrounding component (2, 3) provided with the powder coating layer (7) is less than 15% of the outer diameter (Da) of the bearing ring (5).

6. Rolling bearing arrangement (1 ) according to one of claims 1 to 5, characterized in that the bearing ring (5) is an inner ring and the surrounding component (2) is a shaft.

7. Rolling bearing arrangement (1 ) according to one of claims 1 to 5, characterized in that the bearing ring (5) is an outer ring and the surrounding component is a housing (3) or a housing-fixed component.

8. Rolling bearing arrangement (1 ) according to one of claims 1 to 7, characterized in that it is designed as an angular contact roller bearing.

9. Wind turbine comprising at least one rolling bearing arrangement (1 ) according to claim 1 .

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