Rotor of an electric machine with fibre winding

Abstract

The present invention relates to a rotor (1) of an electric machine (10), the rotor (1) being rotatable about a rotor axis (100), the rotor (1) comprising a rotor body (2) designed to accommodate at least one permanent magnet and / or at least one electrical winding, the rotor body (2) being enclosed by a rotor sleeve (3) which comprises a resin-impregnated fibre winding, wherein fibres (5a) of the fibre winding extend around the rotor body (2) in a circumferential direction (200) at an oblique fibre angle (A) relative to the rotor axis (100), and wherein the fibre winding is formed by winding a tape (5), which is pre-impregnated with resin (5b) and which comprises, as fibres (5a), a plurality of fibre filaments, around the rotor body (3), and is designed to apply a pre-stress to the rotor body (3), characterised in that a ratio of a width b of the tape (5) to a thickness d of the tape (5) is greater than one of the values 400, 500, 600, 700, 800, or 900.

Description

[0001] R.411675

[0002] - 1 -

[0003] Description

[0004] title

[0005] Rotor of an electric machine with fiber wrapping

[0006] State of the art

[0007] The present invention relates to a rotor of an electric machine. The rotor has a fiber winding. The invention also relates to a manufacturing method for such a rotor.

[0008] Electrical machines are known in the prior art in which the rotor body is enclosed in a sleeve-shaped composite material. Fibers are wound around the rotor body, forming a fiber-reinforced composite material together with a resin. For example, the fibers can be pre-impregnated during winding. US 2022 / 0278584 A1 provides an example of fiber winding according to the known prior art.

[0009] Disclosure of the invention

[0010] The rotor of an electric machine is rotatable about a rotor axis and has a rotor body. The rotor body is designed to accommodate at least one permanent magnet and / or at least one electrical winding. The rotor body is enclosed by a rotor sleeve containing a resin-impregnated fiber winding. The rotor sleeve serves, in particular, to absorb centrifugal forces, for example, at high rotational speeds of the rotor about the rotor axis. The rotor sleeve is especially advantageous for supporting the retention of permanent magnets arranged in the rotor body, thereby increasing the stability of the rotor body. R.411675

[0011] - 2 -

[0012] The fibers of the fiber winding run circumferentially around the rotor body at an oblique angle to the rotor axis. The fiber winding is formed by wrapping the rotor body with a resin-impregnated tape comprising a multitude of fiber filaments and designed to apply a preload to the rotor body. The preload is adjustable, particularly by adjusting the winding pattern.

[0013] The ratio of the tape's width (b) to its thickness (d) is greater than 400, 500, 600, 700, 800, or 900. This results in a thin and wide tape; in other words, a flat tape.

[0014] Using tape with the aforementioned width-to-thickness ratio improves force transmission because the applied preload force is distributed more evenly across all fibers of the tape. More fibers are available for direct force transmission into the rotor body. This is particularly relevant because, when the tape is wound, the resin with which it is pre-impregnated has not yet cured, making direct force transmission crucial.

[0015] This achieves a uniform force distribution within the tape, preventing premature breakage of highly stressed fibers. This increases the preload that can be applied to the rotor.

[0016] The reduced thickness ensures that all fibers are impregnated with resin along the thickness direction. Furthermore, a higher fiber volume fraction can be achieved by using fewer fibers across the thickness. During the wrapping of the rotor with the tape, the desired pre-tension of the wrapping must be set. A suitable tensile force can be applied to the tape for this purpose using a winding device. Due to the aforementioned thickness-to-width ratio, the tape has a large contact area with components of the winding device, such as rollers or cylinders. This allows for high force transmission, especially since the tape's reduced thickness enables direct force transfer into the tape fibers. The optimal impregnation and direct force transfer also ensure optimal force transmission to all fibers. R.411675

[0017] - 3 -

[0018] The thicker the tape, the more fibers lie on top of each other in the direction of thickness. This increases the risk of fibers becoming entangled or crossing over each other. The aforementioned ratio results in a low height relative to the width, thus minimizing the number of fiber entanglements or crossing points.

[0019] In particular, the aforementioned thickness-to-width ratio allows for high tensile strength utilization. Furthermore, the tape enables precise adjustment of the rotor sleeve's target thickness. The achievable high preload and thin sleeve result in cost-effective rotor manufacturing.

[0020] The dependent claims describe preferred embodiments of the invention.

[0021] The fiber angle of the fibers in the fiber winding is specifically at least 85° and at most 88°. Using such a fiber angle results in less shrinkage of the rotor sleeve during resin curing. This leads to a lower preload loss after winding. The fibers are compressed during winding due to the preload, resulting in a tendency towards high fiber packing densities. The aforementioned fiber angles prevent the fibers from filling gaps between individual winding layers. Furthermore, this fiber angle simplifies the winding process, allowing for easier overwinding of axial gaps in the rotor body. This reduces the risk of fibers being drawn into these gaps during winding.

[0022] The tape width b is preferably in the range of 10 mm to 30 mm. A width b between 15 mm and 25 mm is particularly advantageous. The wider tape facilitates impregnation with resin. Furthermore, a high tensile force can easily be applied to the tape during winding, thus ensuring a high tensile strength in the winding.

[0023] Preferably, the thickness d of the tape is at most 0.05 mm. Particularly preferably, the thickness d is in the range between 0.01 mm and 0.03 mm. Thus, R.411675

[0024] - 4 - a film-like tape with high tensile strength is provided, which can be optimally wound around the rotor body.

[0025] Advantageously, the number of filaments in the tape ranges from 12,000 to 24,000. This high fiber count allows the tape, and consequently the finished rotor sleeve, to withstand high tensile forces. This significantly increases the speed stability of permanent magnet synchronous machines, as the magnets in the rotor of such machines are optimally held.

[0026] The resin content of the tape is preferably between 15 and 25%. The tape is therefore primarily composed of fibers. Due to the aforementioned width-to-thickness ratio, a minimal amount of resin is sufficient for optimal fiber impregnation.

[0027] Advantageously, the fibers are wound onto the rotor body in several layers. Within each layer, the fibers run parallel to one another. Furthermore, the fibers in a first layer have a fiber angle of at least +85° and at most +88°, and the fibers in a second layer have a fiber angle of at least -85° and at most -88°. The second layer is applied directly to the first layer. Thus, multiple layers of fibers are achieved, resulting in reliable adhesion. The aforementioned fiber angles, which have opposite signs but the same magnitude in each layer, ensure optimal stability and improved force absorption.

[0028] The fibers of the fiber wrapping begin and / or end on an axial disk of the rotor body. The axial disk of the rotor body, in particular, forms the end of the rotor body in the axial direction. The fiber wrapping thus has a defined beginning and / or end at the axial end of the rotor body. Complete wrapping of the rotor body is therefore achievable. Due to the wide and thin tape and the associated shallower winding angle, any gaps between the axial disk and the rotor core can be easily wound over without the fibers becoming pulled in or breaking. R.411675

[0029] - 5 -

[0030] The fibers used are primarily carbon fibers or glass fibers. These fibers exhibit high tensile strength and low weight. Therefore, carbon fibers or glass fibers are ideally suited for use in the rotor sleeve.

[0031] The invention also relates to an electric machine. The electric machine has a stator and a rotor as described above. Due to the rotor sleeve as described above, the electric machine exhibits high speed stability. Furthermore, the rotor sleeve is simple and inexpensive to manufacture.

[0032] Finally, the invention relates to a method for manufacturing a rotor for an electric machine. The method comprises the following steps: First, a rotor body is provided. The rotor body is designed to accommodate at least one permanent magnet and / or at least one electrical winding. The rotor body is also rotatable about a rotor axis. Next, a rotor sleeve is manufactured for the rotor body. This is done by winding a fiber-containing tape under pretension along a circumferential direction around the rotor body. The tape used has a width-to-thickness ratio greater than 400, 500, 600, 700, 800, or 900. The rotor therefore exhibits high speed stability. The rotor sleeve can be manufactured simply and cost-effectively by wrapping it around the rotor body.

[0033] Brief description of the drawings

[0034] Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawings. The drawing shows:

[0035] Figure 1 shows a schematic view of an electric machine according to an embodiment of the invention.

[0036] Figure 2 is a schematic view of a cross-section of a [structure / piece] designed for a [condition / project].

[0037] The tapes used in the rotor sleeve of the electric machine

[0038] Figure 3 shows a schematic view of the winding of the rotor body of the electric machine to produce the rotor sleeve, R.411675

[0039] - 6 -

[0040] Figure 4 shows a first schematic view of the tape used for a rotor sleeve of the electric machine, and

[0041] Figure 5 shows a second schematic view of the tape used for a rotor sleeve of the electric machine.

[0042] Embodiments of the invention

[0043] Preferably, all identical components, elements and / or units in all figures are provided with the same reference numerals.

[0044] Figure 1 schematically shows an electric machine 10 according to an embodiment of the invention. The electric machine 10 has a stator 9 and a rotor 1 driven by the stator 9. The rotor 1 is rotatable about a rotor axis 100, wherein the rotor axis 100 is, in particular, a central axis of the electric machine 10. The rotor 1 has a rotor body 2 and, in particular, a rotor shaft 1a. The rotor body 2 is mounted on the rotor shaft 1a. Furthermore, the rotor body 2 is designed to accommodate at least one permanent magnet and / or at least one electrical winding. The rotor 1 is, for example, provided with permanent magnets (not shown), making the electric machine 10, for example, a permanent magnet synchronous machine.

[0045] To increase the rotational speed stability, the rotor body 2 is enclosed by a rotor sleeve 3. The rotor sleeve 3 extends completely around the rotor body 2 in the circumferential direction 200 and rests against the rotor body 2 along its entire circumference 200. This improves the stability of the rotor body 2, in particular supporting the retention of the permanent magnets and / or the electrical winding. This ensures an air gap between the rotor 1 and the stator 9, especially at high rotational speeds, thus improving the rotational speed stability of the rotor 1 and the electrical machine.

[0046] The rotor sleeve 3 comprises a resin-impregnated fiber winding, with fibers 5a of the fiber winding running circumferentially 200° around the rotor body 2. R.411675

[0047] - 7 -

[0048] The fibers have an orientation oblique to the rotor axis 100, which will be explained in more detail later.

[0049] The fiber winding of the rotor sleeve 3 is formed by wrapping the rotor body 2 with a tape 5 pre-impregnated with resin 5b, a cross-section of which is shown in Figure 2. The tape 5 comprises a plurality of fiber filaments as fibers 5a and is designed to apply a prestress to the rotor body 3. The fibers 5a are, for example, carbon fibers or glass fibers.

[0050] The tape 5 has a ratio of its width b to its thickness d that is greater than 400, 500, 600, 700, 800, or 900. For example, the width b of the tape 5 is in the range of 10 mm to 30 mm, or between 15 mm and 25 mm. The thickness d of the tape 5 is, for example, at most 0.05 mm, or in the range of 0.01 mm to 0.03 mm. Thus, a relatively wide and flat tape 5 is provided.

[0051] As shown in Figure 3, the tape 5, and thus also the fibers 5a of the tape 5, are wound around the rotor body 3 at an oblique fiber angle A to the rotor axis 100 in the circumferential direction 200. The fiber angle A of the fibers 5a of the tape 5 is at least 85° and at most 88°. In particular, it is provided that the fibers 5a are wound onto the rotor body 2 in several layers 6, 7. In Figure 3, a first layer 6 is shown as a solid line and a second layer 7 as a dashed line.

[0052] Within each layer 6, 7, the fibers 5a are oriented parallel to each other. In the first layer 6, the fibers 5a have a fiber angle A of at least +85° and at most +88°. In the second layer 7, the fibers 5a have a fiber angle A of at least -85° and at most -88°. The second layer 7 is applied directly to the first layer 6. Thus, a counter-rotating pattern of the fibers 5a is realized in layers 6, 7. It is particularly advantageous for the fibers 5a of the fiber wrapping to begin and / or end on an axial disk 8 of the rotor body 2. The axial disks 8, in particular, represent axial ends of the rotor body 2.

[0053] Due to the small thickness d and the large width b of the tape 5, which is given by the previously described ratio of thickness d and width b, R.411675

[0054] - 8 - Ensure good impregnation of all fibers 5a across the entire thickness d of the tape 5. The small thickness d also allows for an increase in the fiber volume fraction of fibers 5a, as there are fewer fibers 5a across the thickness d of the tape 5 than with conventional tapes. Due to the high fiber volume fraction, the tape 5 can withstand high tensile forces. The small thickness d of the tape 5 also allows for precise adjustment of the overall thickness of the rotor sleeve 3. For this purpose, a corresponding number of layers 6, 7 must be provided.

[0055] A further advantage of the small thickness d of the tape 5 relative to its width b, due to the aforementioned ratio, is a reduction in the number of intersection points of the fibers 5a across the thickness d of the tape 5. Figure 4 schematically shows an intersection of two fibers 5a in the direction of the width b of the tape 5. Figure 5 schematically shows an intersection of two fibers 5a in the direction of the thickness d of the tape 5. Such intersections represent weak points of the fibers 5a. The aforementioned ratio of thickness d to width b of the tape 5, and the resulting small thickness d and large width b of the tape 5, inevitably leads to fewer intersections. This, in turn, leads to a high utilization of the tensile strength of the tape 5.

[0056] The fiber angle A is shallow compared to the prior art. This allows for optimal winding over gaps on the surface of the rotor body. Such gaps typically extend circumferentially, resulting in an axial distance with respect to the rotor axis 100 between the winding surfaces of the rotor body 3, the winding surfaces being designed to receive the fiber wrapping of the rotor sleeve. The risk of the tape 5 or fibers 5a of the tape 5 penetrating such a gap is minimized or eliminated.

[0057] Likewise, the aforementioned shallow fiber angle A allows for a reduction in shrinkage behavior or preload loss of the rotor sleeve 3. When the rotor body 2 is wrapped with the tape 5, the resin of the tape 5 is not yet cured. This can cause individual fibers 5a to slip. If the fiber angle A were close to 90°, the fibers 5a of the individual layers 6, 7 would be almost parallel to each other. This leads to the penetration of fibers 5a into the gaps between other fibers 5a not only within a layer 6, 7 of the wrapping, but also between the layers 6, 7 of the wrapping. This is described in R.411675.

[0058] - 9 - by the aforementioned fiber angle A, a reduced prestress loss occurs during the curing of the hardener. This increases the torque density, resulting in a stable rotor 1. This also reduces the manufacturing costs of the rotor 1.

[0059] Figure 6 schematically shows how the tape 5 is guided over two rollers 10 during the winding process. To ensure that the tape 5 can be wound onto the rotor body 2 with high tension, optimal force is applied directly to all fibers 5a. This force application is particularly enhanced by the previously described ratio between the width b and thickness d of the tape 5, as the large width provides excellent contact with the rollers 10. The thinness d allows for direct force application to the fibers 5a. This enables high utilization of the tensile strength of the tape 5 and the fibers 5a. The rotor sleeve 3 can be manufactured simply and cost-effectively. The high pretension and the thin tape result in cost reductions.

[0060] The number of fibers 5a, especially the fiber filaments, in tape 5 is, for example, between twelve thousand and twenty-four thousand. The resin mass content of tape 5 is, for example, between 15 and 25%. Thus, there is a high proportion of fibers 5a in tape 5, enabling it to withstand high tensile forces.

Claims

R.411675 - 10 - Claims 1. Rotor (1) of an electric machine (10), wherein the rotor (1) is rotatable about a rotor axis (100), the rotor (1) having a rotor body (2) designed to receive at least one permanent magnet and / or at least one electrical winding, wherein the rotor body (2) is enclosed by a rotor sleeve (3) comprising a resin-impregnated fiber winding, wherein fibers (5a) of the fiber winding run circumferentially (200) around the rotor body (2) at an oblique fiber angle (A) to the rotor axis (100), wherein the fiber winding is formed by wrapping the rotor body (3) with a tape (5) pre-impregnated with resin (5b), which comprises a plurality of fiber filaments as fibers (5a) and is provided for applying a pre-tension to the rotor body (3), characterized in that the ratio of a width b of the tape (5) to a thickness d of the tape (5) is greater than one of the values ​​400, 500, 600, 700, 800 or 900.

2. Rotor (1) according to claim 1 , characterized in that the fiber angle (A) of the fibers (5a) is at least 85° and at most 88°.

3. Rotor (1) according to one of the preceding claims, characterized in that a width b of the tape (5) is in the range between 10mm and 30mm, in particular between 15mm and 25mm.

4. Rotor (1) according to one of the preceding claims, characterized in that the thickness d of the tape (5) is at most 0.05mm, in particular in the range between 0.01 mm and 0.03mm.

5. Rotor (1) according to one of the preceding claims, characterized in that the number of fibers (5a), in particular the fiber filaments, in the tape (5) is in the range between 12,000 and 24,000. R.411675 - 11 - 6. Rotor (1) according to one of the preceding claims, characterized in that the resin mass content of the tape (5) is between 15 and 25%.

7. Rotor (1) according to claim 1, characterized in that the fibers (5a) are wound onto the rotor body (2) in several layers (6, 7), wherein the fibers (5a) run parallel to each other within each layer (6, 7), wherein the fibers (5a) in a first layer (6) have a fiber angle (A) of at least +85° and at most +88° and wherein the fibers in a second layer (7), in particular applied directly to the first layer (6), have a fiber angle (A) of at least -85° and at most -88°.

8. Rotor (1) according to one of the preceding claims, characterized in that the fibers (5a) of the fiber wrapping begin and / or end on an axial disk (8) of the rotor body (2).

9. Rotor (1) according to one of the preceding claims, characterized in that the fibers (5a) are carbon fibers or glass fibers.

10. Electric machine (10) comprising a stator (9) and a rotor (1) according to one of the preceding claims.

11. Method for manufacturing a rotor (1) of an electric machine (10), comprising the following steps: Providing a rotor body (2) configured to receive at least one permanent magnet and / or at least one electrical winding and rotatable about a rotor axis (100), and Manufacturing a rotor sleeve (3) of the rotor body (2) by winding under pretension a tape (5) comprising fibers (5a) along a circumferential direction (200) around the rotor body (2), characterized in that a ratio of a width b of the tape to a thickness d of the tape (5) is greater than one of the values ​​400, 500, 600, 700, 800 or 900.

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