Roller-shaped rolling element for use in a rolling bearing

Abstract

The invention relates to a roller-shaped rolling element (1) for use in a rolling bearing having a central axis (2) and a recess (3) formed about the central axis, wherein a sensor (4) for detecting loads on the rolling element and an inductive generator (20) for providing electrical energy for the sensor are arranged in the recess, wherein the generator comprises at least one hollow cylindrical coil carrier, around which a coil (22) is wound at least in sections along the extension direction thereof, and a permanent magnet (24) associated with the coil, wherein the permanent magnet is arranged within the coil carrier such that it can be moved along the extension direction and the extension direction of the coil carrier is orientated linearly independently of the central axis of the rolling element.

Description

[0001] DESCRIPTION

[0002] title

[0003] Roller-shaped rolling element for use in a rolling bearing

[0004] State of the art

[0005] The present invention relates to a roller-shaped rolling element for use in a rolling bearing, for example for wind turbines.

[0006] To optimize rolling bearings with regard to material fatigue and thus their service life, precise knowledge of the internal loads 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 boundaries, i.e., into or out of the bearing.

[0008] Furthermore, determining the internal load conditions of a rolling bearing or rolling element is a complex process, requiring numerous modifications to the bearing, for example, to one of the bearing rings and / or the cage. Additionally, according to current technology, determining the internal loads of a rolling bearing necessitates the inclusion of a recess in one of the bearing's many rolling elements. Such a roller-shaped rolling element with a recess can be referred to as a measuring roller. One or more sensors or a sensor module are arranged within the recess. The recess typically includes a central through-bore around the rolling element's central axis. A generator or battery is also located within the recess to supply energy to the sensor(s). Such a generator usually comprises several coils and magnets past which the coils move.

[0009] A rolling element with such a generator is known, for example, from DE 10 2022 204 576 A1. In the generators known from the prior art, the relative motion between the rotating rolling element and the cage is used to generate electrical energy. This requires a magnetic interaction between coils attached to the rolling element and magnets mounted on the cage.

[0010] A disadvantage of state-of-the-art generators is that the cage can move relative to the measuring roller during operation, for example by more than 10 mm, which can cause the coils to move outside the engagement range of their associated magnets. Such magnetic decoupling of the coils from the magnets results in the generator no longer supplying energy to the sensor(s). Consequently, the sensors can no longer be operated, or at least the data supply is degraded, since the intermittent power failure prevents data from being provided by the sensor(s), at least temporarily.

[0011] Disclosure of the invention

[0012] It is therefore an object of the present invention to provide a reliable energy supply for determining the internal load conditions in a rolling element.

[0013] This problem is solved by a roller-shaped rolling element for use in a rolling bearing, having a central axis and a recess formed around the central axis, wherein at least one sensor for detecting loads on the rolling element and an inductive generator for providing electrical energy to the sensor are arranged in the recess, wherein the generator comprises at least one hollow cylindrical coil carrier around which a coil is wound at least sectionally along its extension direction, and a permanent magnet associated with the coil, wherein the permanent magnet is arranged to be movable within the coil carrier along the extension direction and the extension direction of the coil carrier is aligned linearly independent of the central axis of the rolling element.

[0014] The rolling element according to the invention offers the advantage of a compact design, since the generator can be arranged entirely within the recess of the rolling element without requiring any mechanical, electrical, or magnetic interaction that extends across the boundaries of the rolling element. Therefore, no lines or other components of the generator protrude from the rolling element or even from the rolling bearing.

[0015] During the rotation of the rolling element, the permanent magnet begins to slip or slide relative to the coil due to its own gravity, thereby inducing current. The rolling element according to the invention presents a significantly reduced risk of energy supply failure, since the permanent magnet is arranged within the coil carrier of the rolling element. Decoupling of the permanent magnet and the associated coil is prevented by the arrangement of the magnet in the hollow cylindrical coil carrier. The coil therefore cannot move out of the permanent magnet's sphere of influence. The rolling element according to the invention thus ensures an autonomous energy supply for the sensor.

[0016] In some embodiments, the induced current can be rectified by diodes and used to charge an internal capacitor—in particular, a long-term capacitor, such as a GREENCAP. Alternatively or additionally, an accumulator can also be used. In these embodiments, any temporary interruptions in energy generation can also be bridged. A further advantage of a rolling element according to the invention is that the internal load conditions of the rolling element or rolling bearing can be determined without any modifications to the rolling bearing. For example, nothing needs to be changed in the cage or cage design. Likewise, nothing needs to be changed in the bearing rings. This eliminates the need for complex, inefficient, and costly long-term measurements, thus saving time and money.

[0017] A roller-shaped rolling element according to the invention can, in particular, be cylindrical or frustoconical with regard to its external shape. However, the invention can also be used in all other roller-shaped rolling elements, such as spherical rollers, toroidal rollers, barrel rollers, etc. The central axis of the rolling element can be parallel to an axis of rotation of the rolling bearing or intersect the axis of rotation.

[0018] The permanent magnet can be cylindrical, cuboid, or prismatic. It can have a constant cross-section over its entire length or several different cross-sections, for example, two, three, or four.

[0019] The coil carrier allows the permanent magnet to be moved smoothly without large gaps. Particularly in applications with (strong) vibrations, this protects the generator and its components from mechanical damage. The result is a robust overall design. Furthermore, winding the coil on the coil carrier helps maintain the coil's shape. The coil carrier thus increases the coil's mechanical stability and shape retention.

[0020] The preferred material for the coil support is plastic. Materials that exhibit strong magnetic shielding, such as ferromagnetic materials, are unsuitable for the coil support. The coil support can be made of a material that generates little friction between the permanent magnet and the coil support, for example, PTFE. The coil support can be manufactured from a plastic, for example, using additive manufacturing. The hollow cylindrical coil support has the shape of a general hollow cylinder. In particular, the base can be circular, ellipse, or polygon, for example, a quadrilateral. Preferably, the base of the coil support is adapted to the cross-section of the permanent magnet.In particular, it is conceivable that the coil has a cuboid-shaped inner channel with a square or rectangular cross-section, and that the coil support and the associated permanent magnet each have a square or rectangular cross-section corresponding to the cross-section of the inner channel.

[0021] According to a further preferred embodiment of the present invention, the hollow cylindrical coil carrier is closed at its ends by covers. These covers create a compact generator. Furthermore, the covers ensure or at least enhance the mechanical integrity of the generator's moving parts. The covers limit the maximum travel of the permanent magnet in both directions. This limits the centrifugal forces emanating from the permanent magnet. In particular, these centrifugal forces can be less than the permanent magnet's own weight. As a result, mechanical stresses in the generator are minimized, leading to optimized energy supply and a lower risk of failure. The two covers also protect the coil and the permanent magnet from contamination, bearing grease, or other substances, especially solids such as solid particles.The covers can, for example, be formed as a single piece with the coil carrier.

[0022] In alternative embodiments, the covers can each have at least one blind hole into which a respective end section of the at least one hollow cylindrical coil carrier is received. The covers are preferably made of a plastic. A blind hole within the meaning of the invention includes recesses with a circular, square, or rectangular cross-section. A blind hole within the meaning of the invention is therefore not limited to a bore in the narrow sense: a blind hole within the meaning of the invention cannot therefore be produced solely by means of a drilling machine.In a preferred embodiment of the present invention, a first blind hole has a first bore base and a first bore opening, wherein an inner diameter is formed on a side facing the first bore base and a further inner diameter is formed on a side facing the first bore opening, the further inner diameter of the first blind hole being larger than the inner diameter of the first blind hole. Likewise, a second blind hole can have a second bore base and a second bore opening, wherein an inner diameter is formed on a side facing the second bore base and a further inner diameter is formed on a side facing the second bore opening, the further inner diameter of the second blind hole being larger than the inner diameter of the second blind hole.

[0023] Preferably, the inner diameter of the first blind hole and the inner diameter of the second blind hole are equal. Furthermore, the remaining inner diameter of the first blind hole and the remaining inner diameter of the second blind hole are preferably equal. The coil support can be designed as a bridge or connecting element between the first and second blind holes, the coil support providing an inner surface, a constant inner diameter, and a constant inner cross-section for optimized sliding of the permanent magnet. For this purpose, the coil support is arranged—at least partially—in the first and—at least partially—in the second blind hole. The length of the permanent magnet is less than the distance between the bottom of the first and second holes.

[0024] Preferably, the coil carrier has an inner diameter that is selected to match the inner diameter of the blind holes. Preferably, the coil carrier has an outer diameter that is equal to the wider inner diameter of the blind holes. This allows for a smooth transition between the coil carrier and the blind holes, which optimizes the (back-and-forth) sliding of the permanent magnet. The coil carrier preferably has a constant wall thickness along its entire length or cylinder height, which is equal to the difference between the inner diameter and the wider inner diameter of the blind holes. The (back-and-forth) sliding allows the permanent magnet to cyclically impact the first and second hole bottoms. To prevent wear, breakage, or other damage, e.g.,On the permanent magnet, a spring, for example a helical spring, can be arranged in the first bore base and / or the second bore base. Alternatively, a rubber or elastomer, for example a disc-shaped one, can be arranged in the first bore base and / or the second bore base. In preferred embodiments, the recess comprises a through-opening with a maximum internal dimension and an end-face receptacle for the generator, wherein the permanent magnet is movable along its direction of extension over a total extent that is greater than the maximum internal dimension of the through-opening. Arranging the generator in an end-face receptacle of the rolling element offers the advantage of good accessibility to the generator, particularly for any repairs or replacements. This results in quick assembly and disassembly and thus also cost savings.The generator in the rolling element, when assembled, is preferably arranged such that a front face of the generator is flush with the end face of the rolling element. The end-face receptacle for the generator allows its radial dimension to extend beyond the largest inner dimension of the through-hole. This enables a greater overall range of motion for the permanent magnet without further weakening the rolling element structurally. A greater overall range results in a higher (falling) velocity of the permanent magnet and thus an increased energy output from the generator. The largest inner dimension of the through-hole is preferably selected to accommodate the sensor and any electronics required for controlling the sensor.

[0025] Preferably, the total extent is between 20% and 50% of the largest outer diameter of the rolling element. While a minimum extent of 20% of the rolling element diameter is advantageous for sufficient energy supply, the maximum extent should not exceed 50% of the outer diameter. This is because the centrifugal force exerted by the permanent magnet increases proportionally to the total extent, causing the rolling element speed to decrease until the centrifugal force exceeds the weight of the permanent magnet. The aforementioned range has proven advantageous for ensuring a continuous energy supply in typical applications of large-diameter bearings.

[0026] Preferably, the generator is arranged completely within a central circular cylindrical subvolume of the rolling element, which subvolume has a radius of 50% of the largest outer diameter of the rolling element around the central axis.

[0027] In preferred embodiments, the coil is wound on a section along its direction of extension on the coil carrier, in the range of 10% to 50% of its total extension. It is therefore preferred that the permanent magnet exits the coil at both ends during its movement. In this way, the induced voltage achieved by the movement of the permanent magnet can be increased.

[0028] According to a further preferred embodiment of the present invention, the direction of extension of the coil carrier forms an angle between 60° and 90°, preferably between 80° and 90°, with the central axis of the rolling element in a longitudinal section of the rolling element. The larger the angle enclosed between the central axis and the direction of extension, the higher the achievable energy yield per revolution of the rolling element. A substantially perpendicular arrangement of the direction of extension and the central axis is therefore preferred.

[0029] Preferably, the generator comprises at least two coils, each coil being associated with a permanent magnet. In particular, the multiple coils can be arranged in parallel to one another. The coils can be connected electrically in series to generate a desired voltage, especially for the sensor. Alternatively, a parallel connection can be provided to adjust the generated current.

[0030] According to a further preferred embodiment of the present invention, the generator comprises four coils and four permanent magnets, each associated with one of the four coils. A further object of the invention is a rolling bearing with a rolling element according to one of the preceding embodiments. A rolling element according to the invention can be used, in particular, in a rolling bearing of wind turbines or tunnel boring machines, but is not limited to these fields of application or industries.

[0031] 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 shown. The drawings merely illustrate an exemplary embodiment of the invention, which does not limit the essential concept of the invention.

[0032] Brief description of the drawings

[0033] Figure 1 schematically shows an embodiment of a rolling element according to the invention in a perspective view.

[0034] Figure 2 schematically shows a generator embedded in the rolling element according to Figure 1 in a perspective sectional view.

[0035] Embodiments of the invention

[0036] In the various figures, identical parts are always marked with the same reference symbols and are therefore usually only named or mentioned once.

[0037] Figure 1 schematically shows a perspective view of an embodiment of a rolling element 1 according to the invention. The rolling element 1 shown is particularly suitable for use in a rolling bearing. The rolling element illustrated in Figure 1 is designed as a cylindrical roller by way of example and can therefore be used in a roller bearing. The invention is applicable in the same way to other roller shapes, such as tapered rollers, spherical rollers, etc. The rolling element 1 has a central axis 2 and a recess 3 formed around the central axis 2. The central axis 2 can be understood as the axis of rotation of the rolling element 1. The rolling element 1 rotates about the central axis 2 while moving about an axis of rotation of the tapered roller bearing in which the rolling element 1 is arranged. During its movement, the rolling element 1 rolls on the respective running surfaces of an inner and outer ring of the rolling bearing.

[0038] A sensor 4 for detecting loads on the rolling element 1 is arranged in the recess 3. Furthermore, an inductive generator 20 for supplying energy to said sensor 4 is arranged in the recess 3. The generator 20 comprises four coils 22 arranged parallel to one another. In other words, the coil axes of all four coils 22 are arranged parallel to one another, with the coil axes located at the center of a respective inner channel of each coil 22. The generator 20 also comprises four permanent magnets 24, each assigned to one of the four coils 22. The permanent magnets 24 are arranged within their respective assigned coils 22 and are movable relative to the coils 22. The generator 20 also has a first cover 271 and a second cover 272.

[0039] The recess 3 comprises a through-opening 31 with a maximum internal dimension R. The recess 3 further comprises an end-face receptacle 32 for the generator 20. In the illustrated embodiment, the rolling element 1 has an opening on each of two opposite sides, the two end faces of the rolling element 1, wherein the two openings form the through-opening 31 of the recess 3, which has a circular cross-section in a plane perpendicular to the central axis 2, constant along the central axis 2. The generator 20 is arranged in the end-face receptacle 32 on one of the two end faces. Preferably, a surface section of the generator 20, here a surface section of the first cover 271 and the second cover 272, is flush with an end face of the rolling element 1. An end-face arrangement of the generator 20 facilitates the assembly and disassembly of the generator 20, for example, in the case of repair.As can be seen in the figure, the permanent magnet 24 is movable along the extension direction 25 over a total extension E that is greater than the largest inner dimension R of the through-hole 31. The total extension E lies between 20% and 50% of the largest outer diameter D of the rolling element 1. The generator 22 is arranged completely within a central circular cylindrical subvolume of the rolling element, which has a radius of 50% of the largest outer diameter D of the rolling element 1 around the central axis 2.

[0040] Figure 2 schematically shows the generator 20 embedded in the rolling element 1 of Figure 1 in a perspective sectional view. The coils 22 are wound around hollow cylindrical coil carriers 26 made of plastic by 3D printing. The permanent magnets 24 can move up and down within the coil carriers 26, with the up and down movement of the permanent magnets 24 being caused by the rotation of the rolling element 1 in a gravitational field.

[0041] The coil is preferably wound on the coil carrier 26 along a section along the extension direction 25, which lies in the range of 10% to 50% of the total extension E. The permanent magnet preferably has a length that lies in the range of 10% to 35% of the total extension.

[0042] The hollow cylindrical coil carriers 26 are closed at their ends by covers 271, 272. The covers 271, 272 each have several blind bores S1, S2 into which a respective end section of the hollow cylindrical coil carriers 26 is received.

[0043] The first cover 271, made of plastic, has four first blind holes S1. The second cover 272, made of the same plastic as the first cover 271, also has four second blind holes S2. Each first blind hole S1 is coaxial with a second blind hole S2 and thus forms a pair. The coil supports 26 are thin-walled and are partially located in a first blind hole S1 and partially in a second blind hole S2. The coil supports 26 act as bridging elements between a first blind hole S1 and a second blind hole S2.

[0044] The permanent magnets 24 are cylindrical and can slide between a first bore base B1 of the first blind hole S1 and a second bore base B2 of the second blind hole S2. The coil carriers 26 enable the permanent magnets 24 to slide in a guided manner along a respective direction 25. To allow the permanent magnets 24 to slide smoothly, the blind holes S1 and S2 each have two different inner diameters. On a side facing the first bore base B1, the first blind hole S1 has an inner diameter that is smaller than a further inner diameter formed in a section of the first blind hole S1 that surrounds the coil carrier 26 in Figure 2. The difference between the further inner diameter and the inner diameter of the first blind hole corresponds exactly to one wall thickness of the hollow cylindrical coil carrier 26.

[0045] Figure 2 schematically and exemplarily shows the free ends 23 of the coils 22. The two-sided sliding of the permanent magnets 24 induces an electric current or generates an electric voltage in the coils 22. The electric current can be supplied directly to the sensor 4 or indirectly, i.e., via intermediate storage, for example in a capacitor or a battery. In this way, an autonomous power supply for the sensor 4 is ensured.

[0046] Reference symbol list

[0047] 1 rolling element

[0048] 2 Central axis

[0049] 3 Exclusion

[0050] 4 Sensor

[0051] 20 Generator

[0052] 22 coil

[0053] 23 free ends

[0054] 24 permanent magnets

[0055] 25 Direction of extension

[0056] 26 coil carriers

[0057] 31 Passage opening

[0058] 32 recording

[0059] 271 First Cover

[0060] 272 Second cover

[0061] B1 First drilling site

[0062] B2 Second borehole

[0063] D largest outer diameter

[0064] E Total extension of coil carrier

[0065] R largest internal dimension of passage opening

[0066] 51 First blind hole drilling

[0067] 52 Second blind hole drilling

Claims

PATENT CLAIMS 1. Roller-shaped 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 at least one sensor (4) for detecting loads on the rolling element (1) and an inductive generator (20) for providing electrical energy to the sensor (4) are arranged in the recess (3), wherein the generator (20) comprises at least one hollow cylindrical coil carrier (26) around which a coil (22) is wound at least sectionally along its extension direction (25), and a permanent magnet (24) associated with the coil (22), wherein the permanent magnet (24) is arranged to be movably arranged within the coil carrier (26) along the extension direction (25) and the extension direction (25) of the coil carrier (26) is aligned linearly independently of the central axis (2) of the rolling element (1).

2. Roller-shaped rolling element (1 ) according to claim 1 , wherein the hollow cylindrical coil carrier (26) is closed at its ends by covers (271 , 272).

3. Roller-shaped rolling element (1 ) according to claim 2, wherein the covers (271 , 272) are formed integrally with the coil carrier (26).

4. Roller-shaped rolling element (1 ) according to claim 2, wherein the covers (271 , 272) each have at least one blind bore (S1 , S2) into which a respective end section of the at least one hollow cylindrical coil carrier (26) is received.

5. Roller-shaped rolling element (1 ) according to one of the preceding claims, wherein the recess (3) comprises a through-opening (31 ) with a maximum internal dimension (R) and an end-face receptacle (32) for the generator (20), wherein the permanent magnet is movable along the extension direction (25) over a total extension (E) which is greater than the maximum internal dimension (R) of the through-opening (31 ).

6. Roller-shaped rolling element (1 ) according to claim 5, wherein the total extent (E) is between 20% and 50% of a maximum outer diameter (D) of the rolling element (1 ).

7. Roller-shaped rolling element (1 ) according to claim 5 or 6, wherein the coil is wound on the coil carrier (26) on a section along the extension direction (25) which lies in the range of 10% to 50% of the total extension (E).

8. Roller-shaped rolling element (1 ) according to one of the preceding claims, wherein the generator is arranged completely within a central circular cylindrical partial volume of the rolling element (1 ) which has a radius of 50% of a largest outer diameter (D) of the rolling element (1 ) around the central axis (2).

9. Roller-shaped rolling element (1 ) according to one of the preceding claims, wherein the extension direction (25) of the coil carrier (26) forms an angle between 60° and 90°, preferably between 80° and 90°, with the central axis of the rolling element (1 ) in a longitudinal section of the rolling element (1 ).

10. Roller-shaped rolling element (1 ) according to one of the preceding claims, wherein the generator (20) comprises at least two coils (22), each of the coils (22) being associated with a permanent magnet (24).

11. Rolling bearing with a roller-shaped rolling element (1) according to one of the preceding claims.

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