Rolling bearing device

Abstract

Rolling bearing arrangement (1), in particular in a wind turbine, comprising a bearing ring (5), a connecting part (2, 3), and a layer of a powder coating (7) for electrical insulation separating the bearing ring (5) and the connecting part (2, 3) from each other, the thickness (d7) of the powder coating (7) being at least 0,05 ‰ and at most 2 ‰ of the engagement diameter (Di), wherein the thickness (d7) is at least 400 mm, wherein the bearing outer diameter is at least 300 mm, wherein the engagement diameter (Di) is measured at the contact surface between the powder coating (7) and a circumferential surface of the metal base body of the bearing ring (5).

Description

[0001] The present invention relates to a rolling bearing assembly having a bearing ring that is electrically insulated relative to another element of the rolling bearing assembly by means of a coating layer.

[0002] A rolling bearing with an electrically insulating coating is known from WO 2013 / 143807 A1. In this case, the insulating varnish is applied to the side of the bearing disc, bearing sleeve, or bearing bushing opposite to the runway section, i.e., the side not subjected to rolling element loads. In principle, according to WO 2013 / 143807 A1, it is also conceivable to coat the runway side if the coating is sufficiently stable. As methods of applying the varnish, WO 2013 / 143807 A1 lists dip coating, spraying, and injection; a possible range of coating thickness is given as 15 to 40 µm.

[0003] DE 10 2011 085 884 B4 addresses a torque transmission device with electrical insulation. Ceramic is mentioned in this case as the electrically insulating coating material. Specifically, it can be a ceramic layer based on silicon dioxide, chromium, and / or chromium nitride. As a further variation of the coating, coatings and / or varnishes based on amorphous carbon structures are also mentioned.

[0004] DE 10 2019 118 810 A1 addresses the problem of bearing ring misalignment in the circumferential direction about its axis of rotation. As a countermeasure against this bearing ring misalignment, which may lead to premature wear, it is recommended to use a form-locking member to prevent bearing ring rotation and axial displacement.

[0005] For example, various possibilities for ceramic coating of rolling bearing components are described in documents such as EP 3 239 348 B1, CN 101782106 A and JP 2014-185741 A.

[0006] EP 2 463 537 B1 discloses a corrosion-resistant bearing having a surface on which multiple strips of plastic film are directly adhered to the steel material of the bearing, the plastic films overlapping each other. The film material may be vinyl, and the adhesive may be acrylic adhesive.

[0007] DE 10 2012 221 739 A1 describes a bearing arrangement for a wind power unit, 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 power unit and a second bearing ring connected to the housing. The first bearing ring connected to the rotor has a cylindrical mounting surface through which it is mounted on a cylindrical section of the rotor. To prevent the bearing ring from easily cracking, DE 10 2012 221 739 A1 suggests machining the cylindrical mounting surface by hard turning. Furthermore, it is proposed to place an annular element made of fiber-reinforced plastic between the end face of the same bearing ring and a stepped end face formed on the rotor for axial contact.

[0008] JP 2007-315585 A proposes the use of a component made of polyamide 9T during assembly to load the bearing ring of a rolling bearing with radial force. The polyamide 9T component is located in an annular circumferential 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 surround the outer ring of the rolling bearing. This insulating sleeve serves not only for electrical insulation but also for acoustic insulation of the rolling bearing.

[0010] The objective of this invention is to provide an improved rolling bearing device with an electrically insulating layer, which is an improvement over the prior art described above, wherein the insulating layer can be manufactured in a reasonable manner with good reproducibility and geometric accuracy.

[0011] According to the present invention, the above-mentioned task is solved by a rolling bearing device having the features of claim 1. This rolling bearing device is also suitable for use in a wind power generation device according to claim 9.

[0012] The rolling bearing assembly includes a bearing ring, a connecting member, and a powder coating for electrical insulation that separates the bearing ring and the connecting member from each other. The thickness of the powder coating is at least 0.05‰ and at most 2‰ of the engagement diameter, and the thickness of the powder coating is at least 400 mm. It should be understood that if the powder coating thickness calculated based on 0.05‰ of the engagement diameter is less than 400 mm, depending on the size of the bearing ring, a minimum thickness of at least 400 mm should be selected. The engagement diameter of the bearing must be at least 300 mm, measured at the contact surface between the powder coating and a circumferential surface of the bearing ring—more precisely, its metal substrate. If the powder-coated circumferential surface of the bearing ring's metal substrate is not cylindrical but, for example, conical or drum-shaped, the median diameter of the corresponding surface is considered the engagement diameter. In any case, the connecting member is at least approximately rigidly connected to the bearing ring, and may in particular be a shaft, other rotating element, or a housing of the rolling bearing assembly or a component fixed to the housing. Accordingly, the bearing ring can be configured as the inner or outer ring of the rolling bearing assembly.

[0013] It has been shown that the powder coating that separates one bearing ring from a connecting component in the rolling bearing assembly is not only for electrical insulation, but also an efficient, reasonable and reliable measure to prevent bearing ring migration.

[0014] The slippage of bearing rings, that is, the movement of bearing rings relative to the components with which they are substantially rigidly connected, is generally attributable, in particular, to minute movements of the bearing rings and / or the components connected to them. The cause of such minute movements in bearing components is, for example, the mechanical loads applied to the bearing rings by the rolling elements during operation. Regarding the topic of slippage in rolling bearing rings, the following publications are mentioned as background information: Research report FVA 479 IV, IGF No. 16985 BR, German Association for Research in Transmission Technology (Forschungsvereinigung Antriebstechnik e. V.): "Remedies for Rolling Bearing Misalignment—Definition and Design of Structural and Tribological Remedies for Tangential Misalignment of Rolling Bearing Rings", 2015 Within the framework of this research project, several solutions were developed, including a form-locking scheme, and their effectiveness was investigated through experiments and complex three-dimensional finite element analysis. A steel intermediate ring positioned between a bearing ring and its surrounding structure was studied through simulation and experiments.

[0015] This steel intermediate ring is not a component of the rolling bearing assembly described in this application. Instead, the powder coating on the bearing ring at least largely performs the function of the independent ring, wherein the mechanical and electrical properties of the powder coating produce additional effects, including damping, which cannot be achieved by a steel ring due to material limitations.

[0016] A variety of methods known per se can be used to apply a powder coating to a bearing ring. In particular, the powder coating can be sprayed onto the substrate surface of the bearing ring. Alternatively, the surface to be coated with the powder coating can also be a metallic coating of the bearing ring.

[0017] Regarding the possibility of applying powder coating to metal parts, DE 198 01 620 C1 is cited as an example. Different formulations of powder coating are disclosed, for example, in EP 0 696 622 B1 and DE 43 22 437 C1.

[0018] Known powder coatings are limited in their thickness, significantly below 400 µm. Surprisingly, however, a thickness greater than 400 µm is required to effectively prevent bearing ring migration, depending on the bearing size, given the necessary elastic allowance. These thicknesses were previously unattainable in a process-reliable manner due to the flowability and adhesion characteristics of powder coatings. However, through optimization and corresponding investment, these thicknesses have been achieved for the aforementioned applications.

[0019] In various possible embodiments of the rolling bearing assembly, the elastic modulus of the powder coating is less than 25 GPa. The coefficient of friction µ of the powder coating relative to the adjacent metal surfaces of the connecting parts is, for example, 0, 3, or greater, and the connecting parts can be, in particular, steel or castings. The electrical breakdown strength of the powder coating can be 5 kV / mm or greater.

[0020] The powder-coated bearing ring, relative to the overall size of the bearing, is a thin-walled, large bearing ring used in wind power generation devices. This application is characterized by a joint diameter of at least 300 mm, and particularly greater than 1000 mm. In thin-walled, large bearings, the lower stiffness of surrounding components compared to other large bearings can increase minute slippage. To compensate for these minute movements, a minimum layer thickness of the elastic, conductive, and insulating powder coating is required. A combination of a layer thickness greater than 1‰ relative to the diameter of the powder-coated element (measured at the contact surface between the element and the powder coating) and a powder coating elastic modulus of less than 25 GPa has proven particularly effective.

[0021] The height of the annular cross section of the bearing ring with powder coating can be less than 15% of the outer diameter of the same bearing ring. Attached Figure Description

[0022] Figure 1. A simplified schematic of a rolling bearing device, wherein one bearing ring is mechanically damped and electrically insulated by a powder coating. Detailed Implementation

[0023] The rolling bearing assembly, generally indicated by reference numeral 1, is configured as an angular contact roller bearing assembly in this embodiment and is used in a wind power generation device (not shown further). In this case, shaft 2 is connected to the rotor of the wind power generation device. Housing 3 is part of rolling bearing assembly 1 but is not included in the rolling bearing 4, i.e., tapered roller bearing 4, which is part of rolling bearing assembly 1.

[0024] The rolling bearing 4 comprises an inner ring 5 and a plurality of rolling elements 6, namely tapered rollers, which are guided by a cage (not shown). Figure 1 In the arrangement shown, the rolling elements 6 roll directly within the housing 3. In a configuration not shown, the rolling bearing 4 may include an outer ring in addition to the inner ring 5, serving as another bearing ring. Optionally, another row of rolling elements 6 may also be present. In particular, in this case, multiple inner and / or outer rings may exist, or one of the bearing rings 5 ​​may be split.

[0025] Figure 1 The only bearing ring shown in the diagram, namely inner ring 5, has an inner diameter D. i and outer diameter D a The central axis of the inner ring 5 and the entire rolling bearing assembly 1 is denoted by MA. The height of the annular section of the inner ring 5 is denoted by A. Therefore, height A corresponds to the outer diameter D. a With inner diameter D i Half the difference. Figure 1 In the middle, diameter D a D i Not shown to scale.

[0026] A powder coating 7 is provided between the shaft 2 (generally referred to as the connecting component of the rolling bearing assembly 1) and the inner circumferential surface of the metal substrate of the inner ring 5, which has a powder coating layer 7. Figure 1 The thickness d7 is shown in an exaggerated manner. The outer diameter of the powder coating 7 constitutes the engagement diameter of the rolling bearing assembly 1, and is related to the inner diameter D of the inner ring 5. i same.

[0027] Before assembling the rolling bearing assembly 1, the powder coating 7 is applied to the inner ring 5. Alternatively, the powder coating 7 can also be applied to the shaft 2. The powder coating 7 has a greater potential for extension relative to the width of the inner ring 5. Figure 1 The text contains some indication.

[0028] Within the rolling bearing assembly 1, the powder coating 7 serves as an electrical insulating layer. Furthermore, the powder coating 7 also possesses significant mechanical damping characteristics. Thanks to these latter characteristics, the powder coating 7 absorbs minute movements to a technically relevant degree during the operation of the rolling bearing assembly 1, thereby effectively counteracting the slippage of the bearing ring 5 on the shaft 2. If minor slippage does occur, its impact is limited to an extremely low level, not affecting the durability of the rolling bearing assembly 1, due to the wear resistance established in the mating joints of the rolling bearing assembly 1 by means of the powder coating 7.

[0029] The powder coating 7 can be applied by a spraying process, and its elastic modulus is less than 25 GPa. The electrical breakdown strength of the powder coating 7 is at least 5 kV / mm. The coefficient of friction µ of the powder coating 7 relative to shaft 2 is greater than 0.3.

[0030] Compared to the overall dimensions of the rolling bearing assembly 1, the inner ring 5 represents a relatively thin bearing ring. This is reflected in the fact that the annular cross-sectional height A of the bearing ring 5 with powder coating 7 is smaller than the outer diameter D of the same bearing ring 5. a 15%. For example... Figure 1 As shown, height A was measured without taking into account the powder coating 7.

[0031] As a response Figure 1 As an alternative or supplement to the inner ring 5 visible in the diagram, the related (but not shown) outer ring of the rolling bearing 4 may also be coated with powder coating 7 in a similar manner. In a manner not shown, the end face of the bearing ring 5 may also be at least partially covered by powder coating 7. In this case, the thickness of the powder coating 7 on the end face is not necessarily the same as the given thickness d7 of the circumferential surface of the bearing ring 5. Explanation of reference numerals in the attached figures 1 Rolling bearing assembly 2 axes, connecting components 3. Shell 4 Rolling bearings 5. Bearing ring, inner ring 6. Rolling elements, rollers 7. Powder Coating A Inner ring section height Di refers to the inner diameter of the inner ring and the mating diameter. Da Inner ring outer diameter d7 Powder coating thickness MA central axis

Claims

1. A rolling bearing device (1), It includes a bearing ring (5), A connecting component (2, 3), And a powder coating (7) for electrical insulation that separates the bearing ring (5) from the connecting parts (2, 3) The thickness (d7) of the powder coating (7) is at least 0.05‰ and at most 2‰ of the bonding diameter (Di). Furthermore, the thickness (d7) is at least 400 mm. Furthermore, the joint diameter (Di) is at least 300 mm. The engagement diameter (Di) is measured at the contact surface between the powder coating (7) and the metal substrate of the bearing ring (5) at one circumferential surface.

2. The rolling bearing device (1) according to claim 1, Its features are, The elastic modulus of the powder coating (7) is less than 25 GPa.

3. The rolling bearing device (1) according to claim 1 or 2, Its features are, The coefficient of friction µ of the powder coating (7) relative to the adjacent metal surfaces of the connecting parts (2, 3) is greater than 0.

3.

4. The rolling bearing device (1) according to any one of claims 1 to 3, Its features are, The electrical breakdown strength of the powder coating (7) is at least 5 kV / mm.

5. The rolling bearing device (1) according to any one of claims 1 to 4, Its features are, The cross-sectional height (A) of the bearing ring (5) covered by the powder coating (7) is less than 15% of the outer diameter (Da) of the bearing ring (5).

6. The rolling bearing device (1) according to any one of claims 1 to 5, Its features are, The bearing ring (5) is the inner ring, and the connecting component (2) is a shaft.

7. The rolling bearing device (1) according to any one of claims 1 to 5, Its features are, The bearing ring (5) is the outer ring, and the connecting component is the housing (3) or a component fixed to the housing.

8. The rolling bearing device (1) according to any one of claims 1 to 7, Its features are, The rolling bearing assembly (1) is configured as an angular contact roller bearing assembly.

9. A wind power generation device, It includes At least one rolling bearing device (1) according to claim 1.

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