Rotor for an electric machine, in particular of a motor vehicle

Abstract

The invention relates to a rotor (10) for an electric machine, comprising a support element (12), two permanent magnets (18a, b) attached to the support element (12), which are arranged successively in the circumferential direction of the rotor (10) and are supported in a first direction extending in the axial direction of the rotor (10) on a support surface (22) of the support element (12), and a fastening element (24) connected to the support element (12) by way of bypassing the permanent magnets (18a, b), by means of which the permanent magnets (18a, b) are attached to the support element (12) such that respective edge regions (R1, R2) of the permanent magnets (18a, b) opposite each other in the circumferential direction of the rotor (10) are oriented in a second direction extending in the axial direction of the rotor (10) and opposite to the first direction on a circumferential direction of the rotor (10) between the edge regions (R1,are supported by the web area (SB) of the fastening element (24) arranged in R2.

Description

[0001] The invention relates to a rotor for an electric machine, in particular of a motor vehicle, according to the preamble of claim 1.

[0002] Such a rotor for an electric machine is already known, for example, from KR 10-2538379. The rotor has a support element and at least two permanent magnets, which are attached to the support element and are separate from the support element and, for example, also separate from each other. The permanent magnets are arranged successively in the circumferential direction of the rotor. The permanent magnets are supported, at least indirectly, and in particular directly, in a first direction extending in the axial direction of the rotor, i.e., parallel to or coinciding with the axial direction of the rotor, on a support surface of the support element, also referred to as the first support surface.The rotor also has at least one fastening element formed separately from the support element and separately from the permanent magnet and connected to the support element by bypassing the permanent magnets, by means of which the permanent magnets are attached to the support element in such a way that at least respective edge regions of the permanent magnets, which are also simply referred to as magnets and which are opposite each other in the circumferential direction of the rotor, are supported at least indirectly, in particular directly, on a web region of the fastening element arranged in the circumferential direction of the rotor between the edge regions of the permanent magnets in a second direction extending in the axial direction of the rotor and opposite to the first direction.

[0003] The state of the art also includes CN 206259839 U and DE 10 2022 202 959 A1.

[0004] The object of the present invention is to improve a rotor of the type mentioned above.

[0005] This problem is solved by a rotor with the features of claim 1. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0006] To improve a rotor of the type specified in the preamble of claim 1, the invention provides that the fastening element has a head area, also referred to as a shoulder, shoulder region, or head, which extends radially outwards from the web region, in particular directly, and on which at least respective sub-regions of the permanent magnets are supported at least indirectly, in particular directly, in the radial direction outwards of the rotor. For example, the head area projects beyond the web region on both sides in the circumferential direction of the rotor extending around the axial direction, whereby the sub-regions of the permanent magnets are at least partially overlapped, i.e., covered, by the head area in the radial direction outwards of the rotor.As a result, the permanent magnets are fixed to the support element not only in the first direction and thus not only in the axial direction of the rotor, but also in the radial direction of the rotor outwards, which prevents unwanted movements of the permanent magnets, especially relative to the support element, even at high rotational speeds of the rotor and thus also at high centrifugal forces acting on the permanent magnets.

[0007] The characteristic that the fastening element is attached to the support element bypassing the permanent magnets means that the fastening element is not attached to the support element via the permanent magnets, or not solely via them. This allows, for example, a force path along which forces can be transmitted between the fastening element and the support element to bypass the permanent magnets, i.e., not via the permanent magnets, from the support element to the fastening element and vice versa. Thus, the aforementioned forces can be transmitted along this force path from the fastening element to the support element and vice versa without the forces flowing or traveling along this path via any of the permanent magnets.The forces arise, for example, as a result of the permanent magnets being attached to the support element by means of the fastening element and / or when a force acts on the fastening element or the support element in an axial direction.

[0008] Since the edge regions of the permanent magnets overlap the web region in the second direction and are thus supported at least indirectly, and in particular directly, by the web region, a positive fit is created between the respective edge region and the web region, and thus between the respective permanent magnet and the fastening element, so that the permanent magnets are positively fixed to the support element by means of the fastening element. For this purpose, it is provided, for example, that the web region, viewed in a cross-sectional plane that runs parallel to the axial direction of the rotor, is wedge-shaped, in particular such that, viewed in the cross-sectional plane, the web region has a wedge-shaped cross-section that tapers, for example, in the first direction. This allows the permanent magnets to be held particularly advantageously and securely on the support element in the axial direction of the rotor.Additionally, it is conceivable that the permanent magnets are bonded to the support element by means of a material bond, in particular by gluing to the support element. This allows for a particularly strong fixation of the permanent magnets to the support element.

[0009] The invention is based in particular on the following findings and considerations: In conventional fixing concepts, where permanent magnets of electric machines are fixed to support elements of the electric machines, the permanent magnets are connected to the respective support element solely by adhesive bonding. This limits the possible, and especially the maximum, rotational speed due to mechanical stresses resulting from centrifugal forces. Consequently, at very high rotor speeds and if no appropriate countermeasures are taken, the permanent magnets can detach from the support element. This prevents the desired functionality from being guaranteed.Attaching permanent magnets to the support element solely by adhesive bonding leads to a temperature dependency, meaning that the rotor's limiting temperature is largely determined by the adhesive used to bond the permanent magnets to the support element. This reduces or negatively impacts the mechanical performance of the electric machine. Fixing the permanent magnets to the support element using an external clamping ring is costly, prone to tolerance issues, and susceptible to the clamping ring breaking. The invention avoids these problems and disadvantages.The invention enables the permanent magnets to be firmly fixed to the support element, thus preventing unwanted relative movements between the respective permanent magnet and the support element, even at very high rotational speeds and therefore also under very high centrifugal forces acting on the respective permanent magnets. The invention provides a particularly advantageous method of fixing the permanent magnets to the support element, also referred to as magnetic fixing, whereby this magnetic fixing is mechanically robust and prevents unwanted relative movements between the respective permanent magnet (also simply referred to as a magnet) and the support element. This results in a particularly high rotational speed stability of the rotor as well as particularly high performance, especially from a mechanical perspective.In addition, the limiting temperature of the rotor is not determined by any adhesive used to connect the permanent magnets to the support element, thus enabling an improvement in the thermal resilience of the rotor compared to conventional solutions.

[0010] Also disclosed is an electric machine, in particular for a motor vehicle, wherein the electric machine has at least one rotor according to the invention. Advantages and advantageous embodiments of the disclosed electric machine are to be regarded as advantages and advantageous embodiments of the rotor according to the invention, and vice versa.

[0011] Preferably, the electric machine is designed as an axial flux machine, which is also referred to as an axial flux motor (AFM).

[0012] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention.

[0013] The drawing shows in: Fig. 1. Partial schematic sectional view of a rotor for an electrical machine designed as an axial flux machine, in particular of a motor vehicle; Fig. 2 a schematic perspective view of the rotor's permanent magnets; and Fig. 3 A schematic perspective view of a mounting element of the rotor.

[0014] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0015] Fig. Figure 1 shows a partial schematic and perspective sectional view of a rotor 10 for an electric machine designed as an axial flux machine, in particular for a motor vehicle. The electric machine, preferably designed as an axial flux machine, in its fully manufactured state comprises a rotor and a stator, by means of which, for example, the rotor 10 can be driven and thus rotated about a machine axis relative to the stator. For example, the electric machine can provide drive torques via its rotor 10 for, in particular, purely electric propulsion of the motor vehicle.

[0016] The rotor 10, whose axial direction coincides with the machine's axis of rotation, has a support element 12. In this case, the support element 12 comprises a rotor carrier 14 and a laminated core 16, wherein the rotor carrier 14 and the laminated core 16 are connected to one another, in particular such that relative movements between the rotor carrier 14 and the laminated core 16 are prevented. In principle, it would be conceivable for the rotor carrier 14 to be made of a plastic or a fiber-reinforced plastic. The laminated core 16 is made of a sheet, in particular a soft magnetic sheet. For example, the laminated core 16 is formed from individual sheet segments, which are, for example, formed separately from one another and connected to one another, in particular by means of a plastic.

[0017] The rotor 10, whose radial direction is perpendicular to the machine's axis of rotation and thus perpendicular to the rotor's axial direction, also has permanent magnets 18a, b. The permanent magnets 18a, b are separate from each other and separate from the support element 12. Where the axial direction is mentioned before and below, this refers, unless otherwise specified, to the axial direction of the rotor 10, whose circumferential direction is around the machine's axis of rotation and thus around the rotor's axial direction. Where the radial direction is mentioned before and below, this refers, unless otherwise specified, to the radial direction of the rotor 10. Where the circumferential direction is mentioned before and below, this refers, unless otherwise specified, to the circumferential direction of the rotor 10.The respective permanent magnet 18a, which is formed separately from the carrier element 12, is attached to the carrier element 12, and thus fixed. This can be seen from the figure. Fig. Figure 1 shows that the permanent magnets 18a, b are arranged consecutively in the circumferential direction, with the permanent magnets 18a, b being spaced apart from each other in the circumferential direction. The permanent magnets 18a, b are supported at least indirectly, and in this case directly, in a first direction extending in the axial direction and illustrated by an arrow 20, on a support surface 22 of the support element 12. In the embodiment shown in the figures, the support surface 22 extends in a plane perpendicular to the axial direction. The support surface 22 is also referred to as the first support surface. In the embodiment shown in the figures, the support surface is formed, for example, by the laminated core 16. For example, in the axial direction, the laminated core 16 is arranged between the respective permanent magnet 18a, b and the rotor carrier 14.

[0018] The rotor 10 also has at least one fastening element 24, which is separate from the permanent magnets 18a, b and separate from the support element 12. The permanent magnets 18a, b are fastened to the support element 12 by means of this fastening element such that at least the respective circumferentially opposing, spaced-apart, and mutually facing edge regions R1 and R2 of the permanent magnets 18a, b are supported, at least indirectly, in a second axially extending direction opposite to the first direction and illustrated by an arrow 26, on a web region SB of the fastening element 24 arranged circumferentially between the edge regions R1 and R2. Thus, the edge regions R1 and R2 are overlapped, i.e., covered, in the second direction by the web region SB arranged circumferentially between the edge regions R1 and R2.

[0019] The fastening element 24, which is formed separately from the support element 12 and separately from the permanent magnets 18a, b, is connected to the support element 12 without involving the permanent magnets 18a, b. In the embodiment shown in the figures, the fastening element 24 is screwed to the support element 12 without involving the permanent magnets 18a, b. For this purpose, the fastening element 24 has through-holes 28. Preferably, each through-hole 28 is a thread release hole, so that, for example, no thread is arranged in each through-hole 28. Each through-hole 28 is associated with a screw hole in the support element 12, wherein a first thread is arranged in each screw hole. In particular, the first thread is an internal thread.Furthermore, each through-opening 28 is associated with a screw element (not shown in the figures). The screw elements are formed separately from one another. Each screw element is separate from the permanent magnets 18a, b and separate from the support element 12. Each screw element, for example, penetrates the respective through-opening 28 to which it is assigned and engages in the screw opening of the support element 12 associated with that through-opening 28, such that a second thread of the respective screw element, corresponding to the first thread arranged in the respective screw opening, is screwed, in particular directly, to the first thread arranged in the respective screw opening into which the respective screw element engages.In particular, the respective second thread is an external thread, such that, for example, the respective external thread is screwed directly into the respective corresponding internal thread. The respective screw element surrounds the permanent magnets 18a, b and is screwed to the support element 12, bypassing the permanent magnets 18a, b.

[0020] To fix the permanent magnets 18a, b particularly firmly to the support element 12, the fastening element 24 has a head section KB, also referred to as the head, shoulder, shoulder area, or fixing shoulder, which extends radially outwards from the web area SB. At least the respective sub-sections T1 and T2 of the permanent magnets 18a, b are supported at least indirectly, and in this case directly, in a radial outwards direction by the head section KB. For this purpose, the sub-sections T1 and T2 of the permanent magnets 18a, b are overlapped, i.e., covered, by the head section KB in a radial outwards direction.

[0021] Out of Fig. Figure 1 shows that the web area SB, viewed in a cross-sectional plane perpendicular to the axial direction, has a wedge-shaped cross-section Q. This wedge shape is such that the cross-section Q tapers in the first direction and consequently widens in the second direction. Similarly, the respective permanent magnets 18a and 18b are also wedge-shaped in the cross-sectional plane, such that each permanent magnet 18a and 18b has a wedge-shaped cross-section Q2, tapering in the second direction and widening in the first. This results in a positive locking relationship between the web area SB and the edge areas R1 and R2, and thus with the permanent magnets 18a and 18b, thereby firmly fixing the permanent magnets 18a and 18b to the support element 12.

[0022] Out of Fig. 2 It is evident that each side surface SF of the respective permanent magnet 18a, b, which forms or limits the respective cross-section Q2 in the circumferential direction, forms an angle α1 with the axial direction, which has a value different from 0 degrees and 180 degrees. Preferably, the angles α1 of the side surfaces SF of the permanent magnets 18a, b are equal. From Fig. Figure 3 shows that each additional side surface SF2 of the web area SB, forming or limiting the cross-section Q in the circumferential direction, encloses a further angle α2 with the axial direction, wherein preferably the angles α2 of the side surfaces SF2 of the web area SB are equal. Preferably, the respective angle α1 corresponds to the respective angle α2. It is evident that the respective side surface SF of the respective permanent magnet 18a, b is overlapped in the second direction by the respective side surface SF2 of the web area SB, wherein the respective side surface SF and the respective side surface SF2, by which the respective side surface SF is overlapped in the second direction, are parallel to each other. This allows the permanent magnets 18a, b to be fixed particularly firmly to the support element 12.

[0023] Out of Fig. 3 It is also clearly visible that the head area KB extends beyond the bridge area SB on both sides in the circumferential direction, which means that the fastening element 24 is at least essentially T-shaped.

[0024] It is conceivable that the head region KB, like the bridge region SB or similarly to the bridge region SB, is wedge-shaped or conical, so that, for example, each end surface EF of the respective permanent magnet 18a, b, which terminates radially outwards at its respective end surface EF, is supported in the second direction at least indirectly, or in this case directly, by a respective second support surface AF of the head region KB and thus by the head region KB itself. Viewed in a respective cross-sectional plane in which the axial direction runs, the respective end surface EF runs obliquely to the axial direction.Furthermore, it is preferably provided that the respective second support surface AF, viewed in the section plane, runs parallel to the respective end surface EF, which is overlapped in the second direction by the respective corresponding support surface AF and is thus supported in the second direction, at least indirectly, and in particular directly, by the respective corresponding support surface AF. This ensures that the permanent magnets 18a, b are positively fixed to the carrier element 12 in the first direction not only by the web area SB, but also by the head area KB, so that undesirable relative movements between the carrier element 12 and the respective permanent magnets 18a, b can be avoided at high rotational speeds of the rotor 10.Furthermore, it would be conceivable that a radial inner surface of the respective permanent magnet 18a, b is conical or wedge-shaped and is inserted into a corresponding conical or wedge-shaped recess in an inner area of ​​the support element 12, forming a positive fit, particularly from the outside, whereby a particularly advantageous fixing of the permanent magnets 18a, b on the support element 12 can be achieved.

[0025] In Fig. 1 Arrows 30 illustrate a normal force which, for example, acts from the fastening element 24 on the respective permanent magnets 18a, b by means of the fastening element 24 being clamped in the first direction against the support element 12 and via the web area SB against the edge areas R1 and R2, whereby the permanent magnets 18a, b are clamped in the first direction against the support element 12. Reference symbol list 10 Rotor 12 support element 14 rotor carriers 16 sheet metal packages 18a, b Permanent magnet 20 Arrow 22 Support surface 24 Fastening element 26 Arrow 28 Passage opening 30 Arrow KB header T1 sub-area T2 sub-area SB Steg area Q cross-section Q2 cross-section R1 Edge area R2 edge area EF end surface SF, SF2 side surface AF support surface α1 angle α2 angle QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] KR 10-2538379

[0002] CN 206259839 U

[0003] DE 10 2022 202 959 A1

[0003]

Claims

Rotor (10) for an electric machine, comprising a support element (12), with at least two permanent magnets (18a, b) formed separately from and attached to the support element (12), which are arranged successively in the circumferential direction of the rotor (10) and are supported at least indirectly in a first direction extending in the axial direction of the rotor (10) on a support surface (22) of the support element (12), and with a fastening element (24) formed separately from the support element (12) and separately from the permanent magnets (18a, b) and connected to the support element (12) by way of bypassing the permanent magnets (18a, b), by means of which the permanent magnets (18a, b) are attached to the support element (12) such that at least respective edge regions (R1, R2) of the permanent magnets (18a, b) opposite each other in the circumferential direction of the rotor (10)b) are supported at least indirectly in a second direction extending in the axial direction of the rotor (10) and opposite to the first direction on a web area (SB) of the fastening element (24) arranged in the circumferential direction of the rotor (10) between the edge regions (R1, R2), characterized in that the fastening element (24) has a head region (KB) extending outwards in the radial direction of the rotor (10) to the web area (SB), on which at least respective sub-regions (T1, T2) of the permanent magnets (18a, b) are supported at least indirectly outwards in the radial direction of the rotor (10). Rotor (10) according to claim 1, characterized in that the web area (SB) and the head area (KB) are formed in one piece. Rotor (10) according to claim 1 or 2, characterized in that a respective end surface (EF) of the respective permanent magnet (18a, b), which in the radial direction of the rotor (10) terminates outwards at its respective end surface (EF), is supported in the second direction at least indirectly on the head region (KB). Rotor (10) according to claim 3, characterized in that the respective end surface (EF) is viewed in a respective section plane in which the axial direction of the rotor (10) runs, is inclined to the axial direction of the rotor (10). Rotor (10) according to claim 4, characterized in that the respective end surface (EF) is supported at least indirectly in the second direction by a respective, corresponding second support surface (AF) of the head area (KB) is supported, the respective second support surface (AF) of which, viewed in the section plane, runs parallel to the respective end surface (EF).

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