Rotor of an electric machine
Patent Information
- Application Number
- EP2023709403
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-03-30
- Filing Date
- 2023-03-06
- Publication Date
- 2025-02-05
AI Technical Summary
The existing rotor designs of electrical machines suffer from play between magnetic pockets and magnets, leading to reduced power and maximum torque, as well as potential magnet damage due to movement at high speeds, resulting in increased losses.
The rotor design incorporates deformed circumferential bridge webs within the rotor poles, which are mechanically preloaded to clamp the magnets in place, reducing play to zero and maintaining residual preload, achieved through methods like fiber winding or high-pressure injection of a molding compound, allowing for increased radial extent and smooth magnet insertion.
This solution significantly reduces clearance in magnetic pockets, enhancing the electric machine's power and maximum torque while preventing magnet damage, enabling a high-performance electric machine with improved torque output.
Smart Images
Figure 1.1
Abstract
Description
[0001] Description
[0002] title
[0003] Rotor of an electrical machine
[0004] State of the art
[0005] The invention is based on a rotor of an electrical machine according to the preamble of the main claim.
[0006] A rotor of an electrical machine is already known from JP2021125955 A2, comprising a rotor body rotatable about a rotor axis, in particular a rotor core, which is enclosed by a rotor sleeve and has a plurality of rotor poles, wherein several of the rotor poles each have at least one magnetic pocket for receiving magnets, in particular permanent magnets, wherein an outer pole segment is formed radially outside the respective magnetic pocket and an inner pole segment is formed radially inside the respective magnetic pocket, wherein magnetic pockets are provided in which the respective outer pole segment is connected to the respective inner pole segment via circumferential bridging webs located on the outer circumference. Disadvantageously, a play can remain in the magnetic pockets with respect to a pocket height between the magnetic pockets and the magnets arranged in the magnetic pockets, thereby reducing the power and maximum torque of the electrical machine.In addition, the remaining play can cause the magnets to move in the magnet pockets when rotating, causing damage, particularly to their magnet insulation, which would lead to higher losses.
[0007] Advantages of the invention
[0008] The rotor of an electrical machine according to the invention with the characterizing features of the main claim has the advantage that the power and maximum torque of the electrical machine are increased by subsequently reducing the play initially formed in the magnet pockets with respect to the pocket height. This is achieved according to the invention in that several of the circumferential bridging webs in the rotor poles of the rotor are deformed by mechanically prestressing the rotor sleeve in order to reduce the play between the magnet pockets and the magnets arranged in the magnet pockets, in particular for clamping the magnets in the magnet pockets. The magnets are clamped in the magnet pockets when the play in the magnet pockets is reduced to zero and a residual prestress remains for clamping the magnets.
[0009] The measures listed in the subclaims enable advantageous further developments and improvements of the rotor of the electric machine specified in the main claim.
[0010] According to an advantageous embodiment, the mechanical prestressing of the rotor sleeve can be achieved by winding a fiber winding of a rotor sleeve designed as a fiber composite sleeve onto the rotor body and / or alternatively by injecting a molding compound to be cured under high pressure into the magnet pockets. The injection of the molding compound can prestress or further prestress the rotor sleeve and can occur, in particular, after the fiber winding has been wound.
[0011] It is very advantageous if a web width of the deformed or to-be-deformed circumferential bridge webs is designed in such a way that deformability is achieved under the prestress of the rotor sleeve, wherein the web width is in particular less than 0.8 mm.
[0012] It is particularly advantageous if the circumferential bridge webs to be deformed and the outer pole segments located between the circumferential bridge webs to be deformed protrude radially outwards before the circumferential bridge webs are deformed, in particular by the amount of play in the magnet pocket to be reduced and in particular by means of a continuous increase in the radial extent of the outer circumference of the rotor body. The play in the respective magnet pocket is a joining gap that is provided for joining or inserting the magnets into the magnet pockets. Due to the radial protrusion of the circumferential bridge webs to be deformed and the associated outer pole segments, there is initially sufficient play in the magnet pockets for the magnets to be inserted smoothly into the magnet pockets.When generating the mechanical preload, for example when applying the rotor sleeve to the outer circumference of the rotor body, the play in the magnetic pockets is subsequently reduced in a targeted manner by the radially projecting areas.
[0013] It is also advantageous if the radially protruding areas on the outer circumference of the rotor body are smoothed into a cylindrical outer circumference by a backlash-reducing radial displacement of the outer pole segments. This achieves a constant air gap between the rotor and a stator of the electric machine and a homogeneous pressure distribution in the rotor sleeve along its circumference. Furthermore, the radial displacement of the outer pole segments reduces the backlash in the magnet pockets, thus increasing the power and maximum torque of the electric machine.
[0014] It is very advantageous if the magnetic pockets with circumferential bridge webs to be deformed have a pocket height prior to the deformation of the bridge webs that is designed such that the magnets can be inserted into the respective magnetic pocket with clearance relative to the pocket height. This allows the magnets to be inserted into the magnetic pockets without friction, thus avoiding damage to the magnetic surfaces. The invention makes it possible to subsequently significantly reduce the inherent clearance in the rotor's magnetic pockets, thus enabling the creation of an electric machine with high power and high maximum torque.
[0015] It is also advantageous if the magnetic pocket is designed to accommodate a V-shaped, C-shaped, U-shaped, or arcuate magnetic layer comprising a plurality of magnets and is designed without radial webs, in particular without a radial bridging web extending in the radial direction in the region of a pole center of the respective rotor pole. In this way, the radial displaceability of the outer pole segments is achieved for magnetic layers, with deformation of the respective circumferential bridging webs.
[0016] It is also advantageous if an additional magnetic pocket is provided radially outside the respective magnetic layer, in particular for accommodating a single magnet. In this way, the power and maximum torque of the electric machine can be increased even further. Furthermore, it is advantageous if holding means, in particular holding lugs, are formed in the respective magnetic pocket for positioning the magnets in the respective magnetic pocket. In this way, the magnets are held in the correct position in the magnetic pockets. Filling the cavities in the magnetic pockets with a molding compound or adhesive is no longer necessary.
[0017] It is advantageous if the magnets are each attached with an adhesive to at least one broad side of the respective magnet pocket, especially to the broad side facing the respective outer pole segment. A sufficiently high preload of the rotor sleeve prevents the magnets from being pressed against the holding means due to centrifugal forces when the rotor rotates, thus preventing them from being subjected to local mechanical pressure. The inventive design with the adhesive allows the preload of the rotor sleeve to be reduced.
[0018] drawing
[0019] An embodiment of the invention is shown in simplified form in the drawing and explained in more detail in the following description.
[0020] Fig.l shows a rotor of an electrical machine to which the invention can be applied,
[0021] Fig.2 a detailed view of a detail I according to Fig.l before a deformation of the bridge webs according to the invention and
[0022] Fig.3 is a detailed view of a detail I according to Fig.l after deformation of the bridge webs according to the invention.
[0023] Description of the embodiment
[0024] Fig.l shows a rotor of an electrical machine according to the invention with bridge webs deformed according to the invention.
[0025] The rotor 1 of an electric machine 2 according to the invention comprises a rotor body 4, in particular a rotor core, which is rotatable about a rotor axis 3 and is enclosed by a rotor sleeve 5 and has a plurality of rotor poles 6. The rotor body 4 is arranged, for example, on a rotor carrier 9, for example a rotor shaft, and is connected to the rotor carrier 9 in a force-fitting and / or form-fitting manner.
[0026] In at least several of the rotor poles 6, in particular in all rotor poles 6, at least one magnetic pocket 7 is provided for receiving magnets 8, in particular permanent magnets. According to the exemplary embodiment, in at least one of the rotor poles 6, for example all rotor poles 6, two magnetic pockets 7 are provided, of which the radially inner magnetic pocket 7 is designed, for example, to receive a V-shaped, C-shaped, U-shaped or arc-shaped magnetic layer 18 comprising a plurality of magnets 8, and of which the radially outer magnetic pocket 7 is provided for receiving a single magnet 8 (with respect to a cross-section of the magnetic pocket 7 according to Fig. 1). As an alternative to the embodiment according to Fig. 1, the respective rotor pole 6 can comprise only the radially outer magnetic pocket 7 according to Fig. 1 or only the radially inner magnetic pocket 7 according to Fig. 1.
[0027] In each rotor pole 6, an outer pole segment 10 is formed radially outside the respective magnetic pocket 7 relative to the rotor axis 3, and an inner pole segment 11 is formed radially inside the same magnetic pocket 7. In at least several of the magnetic pockets 7, the respective outer pole segment 10 is connected to the respective inner pole segment 11 of the same rotor pole 6 via circumferential bridge webs 12 located on the outer circumference of the rotor 1.
[0028] According to the invention, several of the circumferential bridge webs 12 in the rotor poles 6 of the rotor 1 are deformed by a mechanical prestressing of the rotor sleeve 5 in order to reduce a play 13 between the magnet pockets 7 and the magnets 8 arranged in the magnet pockets 7, in particular for clamping the magnets 8 in the magnet pockets 7.
[0029] The mechanical prestressing of the rotor sleeve 5 can be achieved by winding a fiber winding of a rotor sleeve 5 designed as a fiber composite sleeve onto the rotor body 4 or, alternatively, by injecting a hardening molding compound under high pressure into the magnet pockets 7. A web width B of the deformed or to-be-deformed circumferential bridge webs 12 is designed such that deformability is achieved under the prestressing of the rotor sleeve 5. In particular, the web width B of the deformed or to-be-deformed circumferential bridge webs 12 is provided in the range of less than 0.8 mm.
[0030] In the case of a magnetic pocket 7 designed for a magnetic layer 18, the invention provides for this pocket to be designed without radial webs. This means that the magnetic layer 7 does not have a radial bridging web extending radially relative to the rotor axis 3 in the region of a pole center 6.1 of the respective rotor pole 6.
[0031] Fig.2 shows a detailed view of a detail I according to Fig.1 before deformation of the bridge webs according to the invention.
[0032] The circumferential bridge webs 12 to be deformed and the outer pole segments 10 located between the circumferential bridge webs 12 to be deformed are designed to project radially outward relative to the remaining outer circumferential regions prior to deformation, in particular by the amount of play 13 to be reduced in the respective magnet pocket 7 and in particular by means of a continuous increase in the radial extent of the outer circumference of the rotor body 4. The radially continuous projection can be achieved, for example, with a continuous transition or with an inclined ramp in the contour of the outer circumference. The laminations of the rotor core 4 are cut or punched out with the projecting regions 10, 12 in the contour of the outer circumference.
[0033] The magnetic pockets 7 with circumferential bridge webs 12 to be deformed have, before the deformation of the bridge webs 12, a pocket height H which is designed such that the magnets 8 can be inserted into the respective magnetic pocket 7 with play 13 with respect to the pocket height H.
[0034] Retaining means 14, in particular retaining lugs, for positioning the magnets 8 in the respective magnetic pocket 7 can be provided in the respective magnetic pocket 7. Furthermore, the magnets 8 can each be attached with an adhesive 15 to at least one broad side 7.1 of the respective magnetic pocket 7, in particular to the broad side 7.1 facing the respective outer pole segment 10. Fig. 3 shows a detailed view of a detail I according to Fig. 1 after deformation of the bridge webs according to the invention.
[0035] By applying the mechanical preload according to the invention, the radially projecting regions 12, 10 on the outer circumference of the rotor body 4 are smoothed into a cylindrical outer circumference by a play-reducing radial displacement of the outer pole segments 10. This smoothing causes the deformed circumferential bridge webs 12 to locally deflect radially inward, for example, forming a dent or indentation.
[0036] To produce the rotor 1 according to the invention, the magnets 8 are inserted into the magnet pockets 7 of the rotor body 4 with the clearance according to the invention. The magnets 8 can have an insulating coating. Alternatively, magnets 8 can be used without an insulating coating and, when inserted into the magnet pockets 7, can be insulated from the rotor body 4 with insulating paper, an insulating film, or an insulating laminate. After the magnets 8 have been inserted, a fiber winding 5.1, for example, is wound onto the rotor body 4 under pretension to produce the rotor sleeve 5 designed as a fiber composite sleeve, whereby the contour of the outer circumference of the rotor 1, particularly in the area of the radially projecting regions 12, 10, is deformed radially inward, deforming the circumferential bridge webs 12 and reducing the clearance in the magnet pockets 7. By winding the fiber winding 5.1 of the rotor sleeve 5, the magnets 8 are clamped into the magnet pockets 7, for example, possibly together with the insulating paper, foil, or laminate. After winding the fiber winding 5.1, the turns of the fiber winding 5.1 can be connected to each other using a curable composite material 5.2.
Claims
Claims 1. Rotor (1) of an electric machine (2), with a rotor body (4) rotatable about a rotor axis (3), in particular a rotor lamination stack enclosed by a rotor sleeve (5) and having several rotor poles (6), wherein several of the rotor poles (6) each have at least one magnet pocket (7) for receiving magnets (8), in particular permanent magnets, wherein radially outside the respective magnet pocket (7) a pole outer segment (10) and radially inside the respective magnet pocket (7) a pole inner segment (11) is formed, wherein magnet pockets (7) are provided in which the respective pole outer segment (10) is connected to the respective pole inner segment (11) via circumferential bridge webs (12) located on the outer circumference, characterized in thatthat several of the circumferential bridge webs (12) in the rotor poles (6) of the rotor (1) are deformed by a mechanical preload of the rotor sleeve (5) to reduce a clearance (13) between the magnet pockets (7) and the magnets (8) arranged in the magnet pockets (7), in particular to clamp the magnets (8) in the magnet pockets (7).
2. Rotor according to claim 1, characterized in that the mechanical preload of the rotor sleeve (5) is generated by winding a fiber winding (5.1) of a rotor sleeve (5) designed as a fiber composite sleeve onto the rotor body (4) or by injecting a molding compound to be hardened under high pressure into the magnet pockets (7).
3. Rotor according to one of the preceding claims, characterized in that a web width (B) of the deformed or to be deformed circumferential bridge webs (12) is designed such that deformability under the preload of the rotor sleeve (5) is achieved, wherein the web width (B) is in particular less than 0.8mm.
4. Rotor according to one of the preceding claims, characterized in that the circumferential bridge webs (12) to be deformed and the pole outer segments (10) located between the circumferential bridge webs (12) to be deformed project radially outwards before deformation, in particular by the amount of the clearance (13) to be reduced in the magnet pocket (7) and in particular with a Continuous increase of a radial extent of the outer circumference of the rotor body (4). Rotor according to claim 4, characterized in that the radially projecting areas (10, 12) on the outer circumference of the rotor body (4) are smoothed to a cylindrical outer circumference by a clearance-reducing radial displacement of the pole outer segments (10). Rotor according to one of the preceding claims, characterized in that the magnet pockets (7) with circumferential bridge webs (12) to be deformed have a pocket height (H) before the deformation of the bridge webs (12) which is designed such that the magnets (8) can be inserted into the respective magnet pocket (7) with clearance with respect to the pocket height (H).A rotor according to any one of the preceding claims, characterized in that the magnet pocket (7) is provided for receiving a V-shaped, C-shaped, U-shaped, or arc-shaped magnet layer (18) comprising several magnets (8) and is designed without radial bridges, in particular without a radially extending radial bridge in the region of a pole center (6.1) of the respective rotor pole (6). A rotor according to claim 7, characterized in that a further magnet pocket (7) is provided radially outside the respective magnet layer (18), in particular for receiving a single magnet (8). A rotor according to any one of the preceding claims, characterized in that retaining means (14), in particular retaining lugs, for positioning the magnets (8) in the respective magnet pocket (7) are formed in the respective magnet pocket (7).Rotor according to one of the preceding claims, characterized in that the magnets (8) are each attached with an adhesive (15) to at least one broad side (7.1) of the respective magnet pocket (7), in particular to the broad side (7.1) facing the respective pole outer segment (10). Electric machine (2) with a rotor (1) according to one of the preceding claims.