Lagerring

Abstract

Bearing ring (1) with an elongated sensor element (2) extending along at least a portion of a surface (3) of the bearing ring (1), wherein the connection between the sensor element (2) and the bearing ring (1) is established by a metallic material (4), the metallic material (4) being connected to the bearing ring (1) by material bonding in the same way as to the sensor element (2), characterized in that the sensor element (2) is arranged in a groove (5) which is machined in the bearing ring (1), the groove (5) extending from the surface (3) of the bearing ring (1), the metallic material (4) enclosing the sensor element (2) and forming a flat metallic strip (6) such that the metallic material together with the flat metallic strip forms an omega structure, and the flat metallic strip (6) being arranged on or in the surface (3) of the bearing ring (1) and covering the groove (5).

Description

Technical environment

[0001] The invention relates to a bearing ring with an elongated sensor element that extends along at least a part of a surface of the bearing ring, wherein the connection between the sensor element and the bearing ring is established by a metallic material, wherein the metallic material is connected to the bearing ring as well as to the sensor element by a material bond. background

[0002] It is known, for example, from WO 2014 / 108 170 A1, WO 2013 / 186 256 A1, or WO 2014 / 090 324 A1, to equip a bearing ring with a glass fiber element to enable the measurement of various physical parameters. This allows for parameter monitoring using a fiber Bragg grating (FBG) method. This method enables the monitoring of temperatures as well as loads on the machine assembly.

[0003] This requires connecting an optical fiber to the component. To monitor temperatures, it is essential that a thermal coupling is established between the optical fiber and the machine assembly. To monitor loads, the optical fiber must be firmly connected to the component being monitored.

[0004] Problems arise particularly in the latter case, as the optical fiber is usually equipped with several coaxially arranged cover layers. A typical design includes a cladding that surrounds the optical fiber (core) itself; this cladding is coated with a cover layer. Reinforcing fibers (for example, made of aramid) are then arranged around the outer perimeter of the coating. Finally, the reinforcing fibers are encased in a hollow cylindrical cable jacket.

[0005] When a fiberglass element of this type is connected to the component, a certain elasticity is inherent between the glass core and the component. Accordingly, measuring the loads due to this elasticity is particularly problematic. This is especially true when the component is not flat or planar, but has a convex shape. This is typically the case with bearing rings, particularly those of rolling bearings.

[0006] Another problem arises when the bearing ring has small dimensions. In this case, machining the grooves for embedding the fiberglass into the bearing ring often removes a significant amount of steel, resulting in a substantial reduction in bearing stiffness and strength. Small bearing rings with such grooves can be easily damaged and therefore have a short service life.

[0007] High-temperature bonding of glass fibers for the fiber Bragg grating process is also always challenging. Conventional polymer adhesives do not meet the requirements for accurate temperature measurement.

[0008] Ultimately, the installation and durability of the bearings, both during and after installation, is often a problem.

[0009] There is no known design to date that solves the aforementioned problems. Bonding methods are known for small bearings, but bonding the fiberglass to the bearing ring primarily protects against oil and grease rather than providing robust integration and high-temperature applications. Summary of the invention

[0010] It is an object of the present invention to propose a bearing ring of the type mentioned above, designed in such a way that a contact is established between the glass fiber core and the component, which has sufficient stiffness but only minimally affects the mechanical strength of the bearing ring. Accordingly, accurate measurement of the loads should be possible, while the mechanical stiffness of the bearing ring is not significantly reduced. Thus, a long service life of the bearing ring should be maintained.

[0011] A solution according to the invention is characterized in that the sensor element is arranged in a groove which is machined in the bearing ring, wherein the groove extends from the surface of the bearing ring, wherein the metallic material surrounds the sensor element and has a flat metallic strip, and wherein the flat metallic strip is arranged on or in the surface of the bearing ring and covers the groove.

[0012] Furthermore, the metallic material, together with the flat metallic strip, forms an omega structure.

[0013] Preferably, the sensor element is arranged on or in an outer cylindrical surface of the bearing ring.

[0014] Preferably, the sensor element is a fiber optic cable or has one.

[0015] The metallic material for connecting the sensor element to the bearing ring and the flat metallic strip are preferably formed in one piece. The metallic material is arranged around the sensor element. It encases the sensor element and can consist of at least two different layers. An outer layer can be made of steel, in particular stainless steel. An inner layer can be made of nickel.

[0016] The metallic material can be fixed in the groove using an adhesive. In this case, the adhesive can be a ceramic adhesive or a high-temperature adhesive.

[0017] The metallic material can be fastened in the groove by means of a soldering material, in particular by means of a vacuum soldering material.

[0018] Another possibility has proven to be an advantageous embodiment of the present invention for assembling the arrangement: The groove for receiving the sensor element can be easily machined with tight dimensions to accommodate the sensor. Before embedding the sensor housing in the groove, the bearing can first be heated to increase the groove dimensions; meanwhile, the sensor housing can either be at room temperature or even cooled (frozen) to shrink in size. This allows for easy assembly when the sensor housing is inserted into the bearing groove. When the assembled bearing returns to room temperature or is heated to the same high temperature, the assembly can be tightly fitted together.

[0019] The flat metallic strip can have a surface that is flush with the surface of the bearing ring; this also applies if the flat metallic strip is additionally covered by a foil (i.e., made of stainless steel).

[0020] Alternatively, the flat metallic strip can protrude from the surface of the bearing ring to a predetermined height.

[0021] The flat metallic strip can be connected to the bearing ring by means of material bonding. In this case, a particularly preferred embodiment proposes that the flat metallic strip be connected to the bearing ring by welding, in particular spot welding.

[0022] According to the invention, the sensor, in particular an optical sensor / fiber optic sensor (FBG sensor), is indirectly embedded in the bearing ring.

[0023] The invention provides an efficient solution for small-format bearing rings or high-temperature applications, and guarantees robustness of the attachment of the fiber optic sensors during the bearing installation process.

[0024] Preferably, harsh environmental conditions of the bearing application, such as underwater, as a wind turbine, in a high-temperature steel production facility, etc., are not problematic due to the proposed design concept.

[0025] It is also an advantage that a miniature groove on the bearing ring is sufficient to position the sensor; this groove is machined into the bearing ring for the installation of the sensor.

[0026] In the case of temperature measurement, the sensor can be glued into the groove using a special adhesive (for example, ceramic adhesive or high-temperature adhesive) or by using a soldering technology (such as vacuum soldering). The sensor is thus material-bonded in the groove.

[0027] As mentioned above, the sensor arrangement has an inverted / upside-down shape like an Omega (Ω) due to the metal strip (see below). Fig. 2) The metallic strip is preferably designed as a thin stainless steel disc; this design allows a perfect fit / integration into the miniature groove in the outer surface of the bearing ring.

[0028] In the case of measuring strain loads using the fiber optic sensor, it is advantageous that the sensor is centered within and uniformly within the omega structure of the sensor element (see also below). Fig. 2) is embedded.

[0029] It is also possible to cover the flat metallic strip with a piece of foil (preferably also made of stainless steel) so that the sensor structure is covered and protected.

[0030] Two side surfaces of the metal strip (the “feet” of the “omega”) can be spot-welded (or attached by alternative welding techniques) to the two lateral sides of the miniature groove.

[0031] The bare fibers outside the sensor area can be covered by an epoxy packing material or alternatively by a high-temperature material, such as ceramic strands, to protect the fiber.

[0032] The described bearing ring with the integrated sensor structure can be fitted tightly into a housing. A small clearance (sometimes negative clearance, i.e., an interference fit) can be used to secure the sensor fiber bonding and also as an efficient structure for durability after installation.

[0033] A key advantage of the proposed structure is that the concept according to the invention makes a significant contribution to the bearing's service life and strength. This is particularly, but not exclusively, important in the case of small-format bearings. Integrating the sensor results in less damage to the bearing structure and reduced stress on the bearing structure, thus extending its service life.

[0034] Another advantage is the contribution to the transfer of tensile stress from the tensile stress in the bearing ring to the optical fiber sensor. Brief description of the drawings

[0035] The drawings show an embodiment of the invention. Fig. Figure 1 shows a radial cross-sectional view through a rolling bearing, and Fig. Figure 2 shows an enlarged view of the area “X” according to Fig. 1. Detailed description of the invention

[0036] The figures show a rolling bearing 9, which in the present embodiment is a deep groove ball bearing (of course other types of bearings are also possible), and which has an outer bearing ring 1, an inner bearing ring 7 and rolling elements 8 arranged between the bearing rings 1 and 7.

[0037] A sensor element 2 is mounted in the outer bearing ring 1, specifically in its radial outer surface 3. The sensor element 2 is an optical fiber and enables the measurement of loads in the bearing ring 1. These loads are monitored using either a fiber Bragg grating (FBG) method or a chemical composition rasterization (CCG) method, both of which are known per se. Reference is made, for example, to US 6,923,048 B2, which explains this technology in more detail.

[0038] For fastening the glass fiber 2 in or to the bearing ring 1, a small groove 5 is machined into the outer surface 3 of the bearing ring 1, extending around the entire circumference of the bearing ring 1. The sensor element 2 together with its housing (see Fig. 2) is then placed in this groove and secured therein by using an adhesive or solder. The adhesive or solder is designated with the reference numeral 12 in Fig. 2 is designated.

[0039] Sensor element 2 with its casing is shown in detail in Fig. Figure 2 shows the optical fiber 2 as such, which is encased in a fiber sheath 10. The sheath 10 is then enveloped by a metallic material 4. This metallic material 4 consists of two different metal layers. The first outer layer 4' is made of steel, and the second inner layer 4'' is enveloped by the first layer 4' and is made of nickel.

[0040] According to an important aspect, the material of the first layer 4' is designed to form a metallic strip 6. As in Fig. As can be seen in Figure 2, the entire sensor assembly, including the metal strip 6, fits into the groove 5. The metal strip 6 itself is covered by a steel foil 11 in the illustrated embodiment.

[0041] In the illustrated embodiment, a flush surface is provided, that is, the upper surface of the metal strip 6, and more precisely that of the steel foil 11, is flush with the surface 3 of the bearing ring 1.

[0042] Accordingly, the bearing element 2 is firmly fixed in the groove of the bearing ring 1 and can be installed in the usual manner, for example in a housing. If this is done by means of an interference fit, the fastening of the sensor assembly is further improved. Reference symbol list 1 bearing ring (outer bearing ring) 2 Sensor element (glass fiber; fiber core) 3 Surface of the bearing ring 4 metallic material 4' first layer of the metallic material 4'' second layer of metallic material 5 Nut 6 metallic strips 7 Bearing ring (inner bearing ring) 8 rolling elements 9 rolling bearings 10 Fiber sheath 11 steel foil 12 Adhesive / Soldering material

Claims

Bearing ring (1) with an elongated sensor element (2) extending along at least a portion of a surface (3) of the bearing ring (1), wherein the connection between the sensor element (2) and the bearing ring (1) is established by a metallic material (4), the metallic material (4) being connected to the bearing ring (1) by material bonding in the same way as to the sensor element (2), characterized in that the sensor element (2) is arranged in a groove (5) which is machined in the bearing ring (1), the groove (5) extending from the surface (3) of the bearing ring (1), the metallic material (4) enclosing the sensor element (2) and forming a flat metallic strip (6) such that the metallic material together with the flat metallic strip forms an omega structure, and the flat metallic strip (6) being arranged on or in the surface (3) of the bearing ring (1) and covering the groove (5). Bearing ring (1) according to claim 1, characterized in that the sensor element (2) is arranged on or in an outer cylindrical surface (3) of the bearing ring (1). Bearing ring (1) according to claim 1 or 2, characterized in that the sensor element (2) is or comprises a glass fiber. Bearing ring (1) according to one of claims 1 to 3, characterized in that the metallic material (4) for connecting the sensor element (2) to the bearing ring (1) and the flat metallic strip (6) are manufactured in one piece. Bearing ring (1) according to one of claims 1 to 4, characterized in that the metallic material (4) surrounding the sensor element (2) consists of at least two different layers (4', 4''). Bearing ring (1) according to claim 5, characterized in that an outer layer (4') consists of steel, in particular stainless steel, which is designed to form the metallic strip (6). Bearing ring (1) according to claim 5 or 6, characterized in that an inner layer (4'') consists of nickel. Bearing ring (1) according to one of the preceding claims, characterized in that the metallic strip (6) is covered by a foil, in particular a steel foil (11). Bearing ring (1) according to one of claims 1 to 8, characterized in that the metallic material (4) is fastened in the groove (5) by means of an adhesive (12). Bearing ring (1) according to claim 9, characterized in that the adhesive (12) is a ceramic adhesive or a high-temperature adhesive. Bearing ring (1) according to one of claims 1 to 8, characterized in that the metallic material (4) is fastened in the groove (5) by means of a soldering material (12), in particular by means of a vacuum soldering material. Bearing ring (1) according to one of claims 1 to 11, characterized in that the flat metallic strip (6) or the foil (11) has a surface which is flush with the surface (3) of the bearing ring (1). Bearing ring (1) according to one of claims 1 to 11, characterized in that the flat metallic strip (6) or the foil (11) protrudes from the surface (3) of the bearing ring (1) with a predetermined height. Bearing ring (1) according to one of claims 1 to 13, characterized in that the flat metallic strip (6) is connected to the bearing ring (1) by material bonding. Bearing ring (1) according to claim 14, characterized in that the flat metallic strip (6) is connected on its side surfaces to the bearing ring (1) on lateral sides of the groove (5) by welding, in particular by spot welding.

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