Rolling element for use in a rolling-element bearing

Abstract

The invention relates to a rolling element (1) for use in a rolling-element bearing, the rolling element having a central axis (2) and a recess (3) formed about the central axis (2), wherein a sensor module (10) having a sensor printed circuit board is arranged in the recess (3), at least two proximity sensors being connected to the sensor printed circuit board, wherein the recess (3) has an inner wall (110) having at least two planar inner wall sections (111, 112) which lie opposite one another in parallel, and the proximity sensors each have a planar active sensor surface, each planar active sensor surface being assigned to a corresponding one of the planar inner wall sections (111, 112) and being arranged opposite said wall section at a spacing, for measuring the spacing (4) between each proximity sensor and its respective assigned inner wall section (111, 112).

Description

[0001] DESCRIPTION

[0002] title

[0003] Rolling elements for use in a rolling bearing

[0004] State of the art

[0005] The present invention relates to a rolling element for use in a rolling bearing, in particular in a large rolling bearing, such as those used, for example, in tunnel boring machines or wind turbines.

[0006] To optimize rolling bearings with regard to material fatigue and consequently their service life, precise knowledge of the internal stresses on the rolling elements is necessary. Long-term measurements can be performed to generate the relevant data. However, these measurements are very resource-intensive, especially in terms of time. Therefore, long-term measurements are considered inefficient.

[0007] Furthermore, long-term measurements require the use of complex measuring equipment on the rolling bearings, which can partially restrict the bearing's function. For example, electrical cables or other components may protrude beyond the bearing's boundaries, i.e., into or out of it. Moreover, determining the internal load conditions of a rolling bearing or rolling element in this way is a complex and time-consuming process, particularly involving numerous modifications to the bearing, such as to one of the bearing rings and / or the cage.

[0008] Another state-of-the-art method for determining the internal load conditions of rolling bearings involves the use of so-called measuring rollers. A measuring roller is a rolling element with a through-hole in which one or more sensors or a sensor module are arranged to detect the loads on the rolling bearing. The measurement of the deformation of the through-hole serves as a measure of the current load on the row of rolling elements into which the measuring roller is inserted. The electrical energy required for the sensors is supplied by batteries or a generator. Measuring rollers have the advantage that they represent only a minor modification to the rolling bearing and can provide real load measurements during operation over extended periods.

[0009] Various measuring principles are known for measuring the deformation of the measuring roller. For example, DE 10 2017 210 286 A1 describes a sensor roller with cantilever beams that bear against the radially inner surface of the roller bore on opposite sides. Changes in the radial dimension of the bore cause bending of the cantilever beams, which can be measured, for example, by strain gauges. A disadvantage of such a mechanical measurement is that a rotating roller under load also exerts lateral stresses on the cantilever beams, which can distort the measurement.

[0010] EP 3 508 831 A1 therefore describes a roller with integrated load sensing based on proximity sensors. The proximity sensors are arranged on the outer cylindrical surface of a sensor module housing, which is mounted with a small radial clearance to an inner cylindrical surface of a roller bore. Deformation of the inner cylindrical surface of the roller bore changes the distances to the proximity sensors, allowing the deformation to be detected. A disadvantage of this measurement method is that the proximity sensors can only detect the deformation at very specific points on the cylindrical surface, and therefore the sensitivity of the proximity sensors is limited in inductive and / or capacitive applications, thus restricting the measurement accuracy.

[0011] To achieve particularly high measuring accuracy, a rolling element with an inductively measuring sensor is known from EP 3 857 197 B1. The sensor has a conductor track arranged on a circuit board and a conductive measuring contact located on the bore wall. The measuring contact is adapted to the contour of the bore wall on a surface facing away from the circuit board and has a measuring surface parallel to the circuit board on a surface facing the circuit board. The measuring contact serves to transmit the deformations of the bore wall into a displacement of the measuring surface relative to the conductor track on the circuit board. In this way, a defined geometry of two parallel surfaces is created, which is scanned by a large-area sensor. Since the sensitivity of inductive (and also capacitive) sensors increases with the active sensor area, particularly high measuring accuracy can be achieved in this way.A disadvantage, however, is that the measuring contacts are moving parts that adhere to the bore wall by magnetic force. When used in bearings subjected to strong vibrations or shocks—for example, in tunnel boring machines—the measuring contacts can detach from the bore wall, potentially damaging the measuring electronics and reducing the service life. There is also a risk that the measuring contacts could become jammed against the sensor or its housing during relative movement.

[0012] Disclosure of the invention

[0013] The object of the present invention is to provide a rolling element with sensors for load measurement for use in a rolling bearing, which has high measuring accuracy and is at the same time particularly robust.

[0014] This problem is solved by a rolling element for use in a rolling bearing with a central axis and a recess formed around the central axis, wherein a sensor module with a sensor board is arranged in the recess, to which at least two proximity sensors are connected. According to the invention, the recess has an inner wall with at least two parallel, flat inner wall sections. The proximity sensors each have a flat active sensor surface, which is assigned to the flat inner wall sections and arranged opposite them at a distance, for measuring the distance between the proximity sensors and the respective assigned inner wall section.By forming the recess with two parallel, opposing, flat inner wall sections, each assigned at least one proximity sensor with a flat, active sensor surface, planar scanning of the inner wall sections with a defined gap geometry is enabled. The sum of the measured values ​​from the two proximity sensors assigned to the opposing inner wall sections is a measure of the rolling element's deformation, independent of the sensor module's current position within the recess. Therefore, displacements of the sensor module within the recess in the proximity sensor's measuring direction, for example, due to vibrations, have no effect on the measurement result.

[0015] The flat, active sensor surface of the proximity sensors is essentially parallel to the corresponding inner wall section, enabling large-area scanning of the inner wall section at a consistently small distance across the entire active sensor surface. Both the small distance and the size of the sensor area contribute to increased measurement accuracy. Because the inner wall sections are designed as flat measuring surfaces for high-precision measurement, enhanced accuracy can be achieved without moving parts inside the rolling element. This results in a particularly robust and accurate measuring roller that can withstand even strong vibrations, such as those generated by tunnel boring machines, over the long term.

[0016] In advantageous embodiments, the flat active sensor surface has a size of at least 1 cm². 2 , preferably at least 1.5 cm 2and especially preferably at least 2 cm 2 The sensitivity of the proximity sensors can be further increased by increasing the size of the sensor area. Even a size of 1 cm 2 exhibits a significantly increased measurement accuracy compared to a point measurement, such as is possible against a cylindrical bore surface.

[0017] The proximity sensors can, for example, be capacitive sensors and detect the distance to the inner wall of the recess, particularly when the rolling element is under load and the gap size changes accordingly. The proximity sensors can also be inductive, or one of the two sensors can be inductive and the other capacitive. Furthermore, additional proximity sensors can be spaced apart along a direction parallel to the central axis. This offers the advantage of detecting changes in the gap size at different positions, thus providing a more comprehensive view.

[0018] Preferably, the recess has a rectangular cross-section. A rectangular cross-section of the recess provides two pairs of parallel, opposing, flat inner wall sections. Thus, the deformation of the rolling element can, in principle, be determined independently of each other in two directions perpendicular to the central axis. In particular, a square cross-section of the recess is conceivable.

[0019] Furthermore, a rectangular cross-section of the recess makes relative movement of the sensor module with respect to the rolling element more difficult due to positive locking. Compared to a recess with a circular cross-section, as is common in the prior art, a rectangular cross-section of the recess offers greater resistance to rotation. Particularly in applications involving vibration, resistance to rotation can be of great importance for the functionality of the sensor module.

[0020] According to a preferred embodiment of the invention, the rectangular cross-section of the recess has rounded corners. The rounded corners offer the advantage of stress reduction in the base body of the rolling element, as stress peaks at the corners can be avoided or at least significantly reduced. This combines the advantages of a cylindrical and a cuboid recess, namely torsional rigidity with lower stresses in the base body of the rolling bearing.

[0021] Preferably, the proximity sensors in the area of ​​the active sensor surfaces each have at least one flat coil for inductive distance measurement. Flat coils are particularly suitable for the area-wide scanning of flat inner wall sections, as they require little space and at the same time provide a large active sensor area.

[0022] In preferred embodiments, the sensor module comprises a housing with a housing surface having at least two parallel, flat surface sections, which are spaced apart from the inner wall sections, with the proximity sensors arranged in the area of ​​the surface sections. In this embodiment, the housing protects the electronics arranged on the sensor board and simultaneously provides a stable base for the arrangement of the proximity sensors.

[0023] Furthermore, it is preferable to fill the housing volume with an electrical potting compound. An epoxy resin, for example, can be used as the potting compound. Filling the internal volume with an electrical potting compound provides more robust protection against vibrations for components of the rolling element, such as the sensor module. Once the potting compound has cured, the components of the rolling element are embedded, resulting in greater mechanical stability.

[0024] The housing may have an opening for pouring the electrical potting compound into the internal volume. This opening may be centrally located on a first section of the housing surface, i.e., equidistant from all edges of that section.

[0025] In an advantageous embodiment of the invention, the housing has a further rectangular cross-section in a plane perpendicular to the central axis, the further rectangular cross-section preferably having rounded corners. The further rectangular cross-section can correspond to the rectangular cross-section of the recess. For example, an edge length of the rectangular cross-section of the housing or the sensor module can be 0.97, 0.98, or 0.99 times as long as an edge length of the rectangular cross-section of the recess arranged parallel to it. In other words, a gap can be formed between an inner wall of the recess and a housing surface.

[0026] In preferred embodiments, the flat coils are formed on carrier films that are bonded to the respective surface section of the module housing. In alternative embodiments, the flat coils are each formed on a printed circuit board, and the housing has recesses in the area of ​​the surface sections for receiving the printed circuit boards. In particular, the printed circuit boards inserted into the recesses can be flush with the surrounding housing surface.

[0027] In an advantageous embodiment of the present invention, the housing has at least two elastic positioning elements for positioning the sensor module in the recess. Three or more positioning elements, such as O-rings or rectangular pre-formed rings, particularly made of an elastomer or rubber, can also be arranged in the gap. The centering elements can function as sealing elements and prevent contaminants, bearing grease or oil, and other particles from entering the recess, or at least make their entry more difficult. Furthermore, the gap can be kept constant over the entire length of the recess, particularly when the rolling element is unloaded, by means of several positioning elements.

[0028] According to an advantageous embodiment of the invention, the recess extends from a first opening on a first end face of the rolling element over the entire length of the rolling element parallel to the central axis to a second opening on a second end face of the rolling element. The first and second openings can be arranged parallel to each other. Furthermore, the two openings can be coplanar with each end face of the rolling element.

[0029] This results in the recess being designed as a through-hole, which can be produced, for example, by wire EDM. The overall advantage is that the sensor module can be inserted and removed from either side. The rolling element can have a recess on each of its end faces, configured symmetrically around the central axis. For example, each of the two recesses can have a cylindrical outer surface and a base parallel to the end faces, with an opening of the recess located centrally in each base. A cover can be located in each recess, which is screwed to the sensor module. The sensor module can be securely and detachably connected to the rolling element by means of the screws on both sides.

[0030] Another object of the present invention is a rolling bearing with a rolling element according to one of the embodiments described above.

[0031] Another object of the present invention is the use of a rolling element mentioned above in a tunnel boring machine or a wind turbine.

[0032] Further details, features, and advantages of the invention will become apparent from the drawings and from the following description of a preferred embodiment with reference to the drawings. The drawings merely illustrate an exemplary embodiment of the invention, which does not limit the essential concept of the invention.

[0033] Brief description of the drawings

[0034] Figure 1 schematically shows an embodiment of an invention.

[0035] Rolling element in a perspective sectional view.

[0036] Figure 2 shows schematically and in a perspective view the

[0037] Sensor module arranged in the rolling element according to Figure 1.

[0038] Figure 3 schematically shows the sensor module according to Figure 2 with the housing open. Figure 4 schematically shows a sensor module according to a second embodiment in an exploded view.

[0039] Embodiments of the invention

[0040] In the various figures, identical parts are always marked with the same reference symbols and are therefore usually only named or mentioned once.

[0041] Figure 1 schematically shows an embodiment of a rolling element 1 according to the invention in a perspective sectional view. The rolling element 1 according to Figure 1 is, by way of example, a tapered roller. Therefore, the rolling element 1 can be used in a tapered roller bearing. However, the invention can be used in any roller-shaped rolling element, such as cylindrical rollers, toroidal rollers, or barrel rollers.

[0042] The rolling element 1 has a central axis 2 around which it can rotate. The rolling element 1 also has a recess 3 which is symmetrically formed around the central axis 2.

[0043] A sensor module 10 with a sensor board 18 is arranged in the recess 3, to which a total of four proximity sensors S1, S2, S3, S4 are connected. The recess 3 has an inner wall 110 with two parallel, opposing, flat inner wall sections 111, 112, and the proximity sensors S1, S2, S3, S4 each have a flat active sensor surface, which is assigned to the flat inner wall sections 111, 112 and arranged opposite them at a distance. The proximity sensors S1, S2, S3, S4 are designed to measure the distance 4 between the proximity sensors S1, S2, S3, S4 and their respective assigned inner wall sections 111, 112.

[0044] The recess 3 has a rectangular cross-section in a plane perpendicular to the central axis 2, with the rectangular cross-section having rounded corners. Avoiding sharp corners can reduce notch stresses or stress peaks in a base body 11 of the rolling element 1. The recess 3 has a constant cross-section along the entire length of the rolling element 1, meaning that the recess has the same rectangular cross-section not only in one plane, but in all planes arranged perpendicular to the central axis.

[0045] A sensor module 10 is arranged in the recess, which is described in more detail in Figures 2 and 3. The sensor module 10 comprises a housing 12, which has a further rectangular cross-section in a plane perpendicular to the central axis 2, the further rectangular cross-section also having rounded corners. The further rectangular cross-section of the housing 12 is slightly smaller than the rectangular cross-section of the recess 3, so that the sensor module 10 can be inserted into and removed from the recess 3. In other words, a gap 4 is formed between an inner wall of the recess 3 and a housing surface of the sensor module 10.

[0046] An internal volume 123 of the housing 12 is filled with an electrical potting compound, for example, an epoxy resin, which is not visible in Figure 1 for clarity. The cured epoxy resin stiffens the internal volume and thus prevents bending or movement of individual parts or components of the sensor module 10. Even under strong vibrations, such as those prevalent in tunnel boring machines, the sensor module 10 can withstand the high loads. The rolling element 1 has a recess on each of its two end faces, which is intended, for example, to receive a cover, although the covers are not illustrated in Figure 1. The covers can be screwed tightly to the sensor module 10 to fix it in the recess 3.

[0047] Figure 2 shows a schematic and perspective view of the sensor module 10, which is arranged in the rolling element 1 according to Figure 1. The housing 12 is multi-part and comprises at least an upper shell 14 and a lower shell 15, wherein the upper shell 14 and the lower shell 15 are connected to each other at two connection points 19. The connection is made by means of a screw at each point, the screws of which are not shown in Figure 2.

[0048] The housing 12 has a housing surface 120 comprising a first surface section 121 and a second surface section 122 arranged parallel to the first surface section 121. The first section 121 is located on the top side of the housing 12 with respect to Figure 2, whereas the second section 122 is located on the bottom side of the housing 12. Both sections 121 and 122 are planar, i.e., two-dimensional surfaces. A first proximity sensor S1 is arranged on the first section 121, and a second proximity sensor S2 is arranged on the second section 122. The proximity sensors shown comprise flat coils for inductive distance measurement in the region of their planar active sensor surface. The flat coils are formed on carrier films that are bonded to the surface sections 121 and 122.

[0049] Furthermore, the housing 12 has a housing opening 16 through which the epoxy resin can be poured into the interior volume of the housing 12. After the epoxy resin has cured, all components of the sensor module 10 arranged within the interior volume, in particular a sensor circuit board 18 (printed circuit board PCB), are stiffened and mechanically stabilized, making the sensor module 10 more robust against stresses, especially vibrations. The housing 12 also has two positioning elements 17 made of an elastic material that completely encircle the housing 12. The two positioning elements 17 are each arranged in an end section of the housing 12 and also prevent or at least impede the ingress of bearing grease or bearing oil or other particles into the gap 4. The two positioning elements 17 preferably space the housing surface 120 evenly from the inner wall of the recess 3.

[0050] When the rolling element 1 is subjected to load, particularly in a radial direction, the distance 4 between the flat inner wall sections 111, 112 and the surface sections 121, 122 changes. The proximity sensors S1 and S2, and S3 and S4, respectively, detect the change in gap size across their entire active sensor area and each generates a corresponding deformation signal. For optimized and comprehensive detection of the gap size, the housing 12 or the sensor module 10 has an additional pair of proximity sensors S3 and S4.

[0051] The active area of ​​the proximity sensors is preferably at least 1 cm². 2 , preferably at least 1.5 cm 2 and especially preferably at least 2 cm 2 .

[0052] Figure 3 schematically shows a sensor board 18 arranged in the sensor module 10 according to Figure 2. The electrical connection between the sensors S1, S2, S3, S4, which are designed as films, and the sensor board 18 is made by means of a ribbon cable and pin connectors. The pin connectors can be connected to pin sockets formed on the sensor board 18, which are not shown in Figure 3.

[0053] Figure 4 schematically shows a second embodiment of a sensor module 10 for use in a rolling element according to Figure 1. The sensor module 10 according to Figure 4 differs from the embodiment shown in Figure 2 in that the flat coils of the proximity sensors S1, S2, S3, S4 are each formed on a printed circuit board and the housing 12 has indentations 124, 125 in the area of ​​the surface sections 121, 122 for receiving the printed circuit boards.

[0054] Furthermore, the explanations relating to the first embodiment according to Figs. 1 to 3 apply accordingly to the second embodiment according to Fig. 4.

[0055] Reference symbol list

[0056] 1 rolling element

[0057] 2 Central axis

[0058] 3 Exclusion

[0059] 4 distance

[0060] 10 Sensor module

[0061] 11 Basic body of the rolling element

[0062] 12 cases

[0063] 14 Upper shell

[0064] 15 Bottom tray

[0065] 16 Housing opening

[0066] 17 Positioning element

[0067] 18 Sensor board

[0068] 19 liaison point

[0069] 110 inner wall

[0070] 111 Interior wall section

[0071] 112 Interior wall section

[0072] 120 Housing surface

[0073] 121 First surface section

[0074] 122 Second surface section

[0075] 123 internal volume

[0076] 124 indentation

[0077] 125 indentation

[0078] 51 First proximity sensor

[0079] 52 Second proximity sensor

[0080] 53 Third proximity sensor

[0081] 54 Fourth proximity sensor

Claims

PATENT CLAIMS 1. Rolling element (1) for use in a rolling bearing with a central axis (2) and a recess (3) formed around the central axis (2), wherein a sensor module (10) with a sensor board (18) is arranged in the recess (3), to which at least two proximity sensors (S1, S2, S3, S4) are connected, characterized in that the recess (3) has an inner wall (110) with at least two parallel, planar inner wall sections (111, 112), and the proximity sensors (S1, S2) each have a planar active sensor surface, which are assigned to the planar inner wall sections (111, 112) and arranged opposite them at a distance, for measuring the distance (4) between the proximity sensors (S1, S2, S3, S4) and the respective assigned inner wall section (111, 112).

2. Rolling element (1) according to claim 1, wherein the planar active sensor surface has a size of at least 1 cm² 2, preferably at least 1.5 cm 2 and especially preferably at least 2 cm 2 exhibits.

3. Rolling element (1) according to claim 1 or 2, wherein the recess (3) has a rectangular cross-section, preferably with rounded corners.

4. Rolling element (1) according to one of the preceding claims, wherein the proximity sensors (S1, S2, S3, S4) each have at least one flat coil for inductive measurement of the distance (4) in the area of ​​the active sensor surfaces.

5. Rolling element according to one of claims 1 to 4, wherein the sensor module (10) comprises a housing (12) with a housing surface (120) having at least two mutually parallel, planar surface sections (121 , 122) which are spaced apart from the inner wall sections, wherein the proximity sensors (S1 , S2, S3, S4) are arranged in the area of ​​the surface sections (121 , 122).

6. Rolling element (1 ) according to claim 5, wherein an internal volume (123) of the housing (12) is filled with an electrical potting compound.

7. Rolling element (1 ) according to claim 5 or 6, wherein the housing (12) has a further rectangular cross-section in a plane perpendicular to the central axis (2), wherein the further rectangular cross-section preferably has rounded corners.

8. Rolling element (1 ) according to one of claims 5 to 7 and claim 4, wherein the flat coils are formed on carrier films which are glued onto the respective surface section (121 , 122).

9. Rolling element (1 ) according to one of claims 5 to 7 and claim 4, wherein the flat coils are each formed on a printed circuit board and the housing (12) has indentations (124, 125) in the area of ​​the surface sections (121 , 122) for receiving the printed circuit boards.

10. Rolling element (1 ) according to one of claims 5 to 9, wherein the housing (12) is supported on the inner wall (110) via at least two elastic positioning elements (17) for positioning the sensor module (10) in the recess (3).

11. Rolling element (1) according to one of the preceding claims, wherein the recess (3) extends from a first opening at a first end face of the rolling element (1) over an entire length of the rolling element (1) parallel to the central axis (2) to a second opening at a second end face of the rolling element (1).

12. Rolling bearing (100) with a rolling element (1 ) according to one of the preceding claims.

13. Use of a rolling bearing (100) according to claim 11 in a tunnel boring machine or a wind turbine.

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