Rotor of an electric motor and electric motor

Abstract

Rotor of an electric motor, comprising several anchor sections and several magnets (8) which, in conjunction with the armature sections (6), are assembled to form an arrangement (4) that is at least substantially ring-shaped and the magnets (8) arranged between two adjacent armature sections (6) are wedge-shaped and are applied against the armature sections (6) in the form of at least a point-like, linear and / or planar contact, characterized in that the anchor sections are formed in the form of individual loose anchor blocks (6), a plastic overmolding (12) is provided inside the ring-shaped arrangement (4) for connecting the ring-shaped arrangement (4) to a shaft and / or a hub for connecting to a shaft and the ring-shaped arrangement (4) can only be connected to the shaft or hub via the plastic overmolding (12).

Description

[0001] The present invention relates to a rotor of an electric motor and an electric motor having such a rotor. Within the scope of this disclosure, a method for producing such a rotor is also proposed, as well as an actuator unit having such an electric motor and a vehicle having such an electric motor and / or such an actuator unit.

[0002] Electric motors are known from the prior art whose rotors are equipped with cuboid-shaped permanent magnets arranged in a so-called spoke arrangement, also known as a "spoke design," buried in the armature lamination stack around the circumference of the pole-forming armature lamination stack. The armature lamination stack, in which the individual magnets are aligned vertically in the radial direction, also represents the link to a shaft through which torque is to be transmitted. The assembly comprising the armature lamination stack and the individual magnets can also be overmolded with a plastic for structural support.

[0003] DE 10 2013 212 616 A1 discloses a rotor having the features of the preamble of patent claim 1. This known rotor comprises a one-piece armature unit. The armature unit has radially outwardly extending rotor poles, between which individual magnets are arranged, with the magnets tapering radially outward. The magnets are first inserted axially into the corresponding free spaces and then radially pressed into place.

[0004] An object of the present invention is to provide an improved rotor.

[0005] This object is achieved by a rotor according to claim 1. Claims 11, 12, and 13 protect an electric motor, an actuator unit, and a vehicle. Claim 14 protects a method for producing such a rotor. Advantageous embodiments of the invention are the subject of the dependent claims.

[0006] A rotor for use in an electric motor is proposed, wherein the rotor has a plurality of pole-forming armature sections in the form of individual armature blocks and a plurality of magnets or permanent magnets which, in conjunction with the armature blocks, are assembled to form an at least substantially annular arrangement.

[0007] The individual armature blocks are loosely formed metallic armature sections of the rotor that form poles, with the armature structure being connectable to a rotor shaft. The loose metallic armature sections can each be designed as a laminated core. The laminated core can be composed of a large number of stamped sheets. In principle, however, the individual sheets can also be laser-cut sheets or sintered sheets.

[0008] It is proposed that the magnets arranged between two adjacent armature blocks be wedge-shaped and be placed against the associated armature blocks to form at least a point-shaped, linear and / or planar contact.

[0009] Due to the wedge-shaped magnets, the distances or air gaps that must be maintained in the circumferential direction between the individual armature blocks and the associated magnets according to the state of the art can be reduced to a minimum by the magnets being placed against the associated armature blocks, forming at least a point-like, linear and / or planar contact.

[0010] According to the state of the art, the circumferential dimensions of the armature blocks are selected so that the individual magnets can be inserted into the receiving shafts formed by the armature blocks without being significantly scratched. The distances or air gaps that inevitably arise between the individual magnets and the associated armature blocks after insertion, which can be approximately 0.1 to 0.3 mm, are filled with a plastic during the overmolding of the annular arrangement of the individual armature blocks and magnets. Such a thin plastic film forming between the individual armature blocks and magnets has a detrimental effect on the magnetic flux in the armature structure of the rotor.

[0011] The proposed wedge-shaped magnets allow such losses of the magnetic flux in the armature structure to be minimized.

[0012] In the case of a so-called spoke arrangement - also known as "spoke design" - of cuboid-shaped permanent magnets, which are arranged buried in the armature lamination stack over the circumference of a pole-forming armature lamination stack, also called rotor lamination stack, the magnets are each aligned at least substantially radially to the annular arrangement.

[0013] The wedge shape of the individual magnets can taper toward the outer circumference of the ring-shaped arrangement. In principle, the wedge shape of the individual magnets can also taper toward the inner circumference of the ring-shaped arrangement.

[0014] A plastic overmolding is provided inside the annular arrangement of the individual armature blocks and magnets to connect the annular arrangement to a shaft and / or a hub for connection to a shaft. Such a plastic overmolding contributes both to structural support and to weight savings for such a proposed rotor.

[0015] The metallic armature sections of the rotor are designed as individual, loose armature blocks forming poles. A plastic overmolding is mandatory inside the annular arrangement of the individual armature blocks and magnets to connect the annular arrangement to a shaft and / or a hub. This is because the annular arrangement can only be connected to the shaft or hub via the plastic overmolding as part of the rotor structure.

[0016] The individual, loose anchor blocks can each be anchored in the plastic overmolding on an inner side facing the rotor center axis, at least by means of an anchoring means. The at least one anchoring means can extend from the associated anchor block into the plastic overmolding. The at least one anchoring means can be, for example, eyelet-shaped, hook-shaped and / or pin-shaped. The anchoring means can, for example, be in the shape of a half ring or in the shape of an essentially solid ring. Additionally or alternatively, the anchoring means can also have other designs that fall under the term eyelet shape, such as a part-circular design. In principle, however, other anchoring forms are also conceivable.A combination of eyelet-shaped anchoring forms alongside other anchoring forms is also conceivable, such as pin-shaped and / or hook-shaped anchoring forms. All of these different anchoring forms ensure a solid form fit with the overmolded plastic and thus a solid anchoring of the individual anchor blocks in the plastic section of the rotor.

[0017] According to one embodiment, the armature blocks and the magnets are individually and alternately assembled to form a substantially annular arrangement. A single magnet can expediently be arranged between each two adjacent armature blocks.

[0018] According to a further embodiment, each individual armature block can be formed from a plurality of stamped sheets or sheet sections that are assembled to form the armature block. However, the armature blocks can also be formed from a solid material, although this would likely increase the manufacturing costs for such an armature block. In any case, a corresponding sheet metal cut or a corresponding design of the individual armature blocks can be designed to optimize the magnetic flux.

[0019] The aforementioned plastic overmolding can be made of an overmolded thermoplastic or thermosetting plastic.

[0020] An electric motor with a rotor of the type described above is also proposed.

[0021] Furthermore, an actuator unit with an electric motor of the type described above is proposed. An actuator unit is understood to be an actuating unit that, in addition to an electric motor of the type described above, also has control electronics. This can, for example, be an actuating unit for a so-called cooling water control valve, which, in addition to an electric motor with the proposed rotor described above, also includes control electronics.

[0022] Furthermore, a vehicle with an electric motor and / or an actuator unit of the type described above is proposed.

[0023] Furthermore, a method for producing a rotor of the type described above is proposed, in which a tool comprising at least one substantially circular tool inner wall is used to assemble a plurality of armature sections in the form of individual armature blocks forming poles and a plurality of wedge-shaped magnets into an at least substantially annular arrangement. The individual armature blocks are placed against the tool inner wall, with at least one wedge-shaped magnet being arranged between each two adjacent armature blocks and being placed against the armature blocks to form an at least point-shaped, linear, and / or planar contact.

[0024] This process allows the outer diameter of the ring-shaped arrangement of the individual armature blocks and magnets to be adjusted very precisely, in contrast to the state of the art.

[0025] According to the state of the art, this outer diameter is subject to fluctuations due to manufacturing, which also have a negative effect on the air gap that forms between the rotor and stator when the rotor is installed in a stator.

[0026] According to one embodiment, each individual magnet is pressed in the radial direction against the respectively associated armature block by means of an associated tool mandrel in order to ensure at least point-like, line-like and / or planar contact.

[0027] Pressing a magnet onto the workpiece using such a mandrel requires only a relatively small amount of force, with a maximum force of approximately 10 N being considered sufficient. Therefore, there is no risk of severe jamming of the individual magnets, so scratching of the respective magnet surfaces is avoided, or at least virtually avoided.

[0028] Internally, the rotor is overmolded with a plastic for structural connection to a shaft and / or hub, forming a substantially ring-shaped arrangement of the individual armature blocks and magnets. Such a plastic overmold contributes both to structural support and to weight savings for such a proposed rotor.

[0029] The rotor uses armature sections in the form of individual, loose armature blocks that form poles. Such plastic overmolding is essential, especially since the ring-shaped arrangement of individual armature blocks and magnets is only connected to the shaft or hub via the plastic overmolding.

[0030] The invention will be explained in detail below with reference to the figures. Further advantageous developments of the invention will become apparent from the dependent claims and the following description of preferred embodiments. These are shown in: Fig. 1 a plan view of a proposed ring-shaped arrangement of individual armature blocks and magnets of a rotor, Fig. 2 a perspective view of the arrangement of Fig. 1 and Fig. 3 a representation of a proposed rotor with a supporting plastic structure.

[0031] Fig. 1 and Fig. 2 illustrate an exemplary, substantially ring-shaped arrangement 4 comprising a total of ten metallic armature blocks 6 forming poles and ten permanent magnets 8, this arrangement 4 being part of a ten-pole rotor 2 (cf. Fig. 3) is for use in an electric motor.

[0032] The individual anchor blocks 6 are loosely formed and assembled from a plurality of, for example, stamped sheets, so that they form anchor plate stacks. By means of a substantially centrally formed elongated hole 10 in the individual anchor plates, these anchor plates are assembled to form the individual anchor blocks 6 by being stacked on top of one another using a corresponding fixing pin (not shown here) that extends through such an elongated hole 10. The individual elongated holes 10 are aligned radially edgewise with respect to the annular arrangement 4.

[0033] The individual lamination layers of such an armature lamination stack are held together by means of a stamping - not shown here - which is produced by means of a punch and extends in an axial direction X - X of the annular arrangement 4 over the entire length of an associated armature lamination stack, so that a positive connection is created between the individual lamination layers, which holds the lamination layers together.

[0034] A wedge-shaped, ground permanent magnet 8 is arranged between each two adjacent armature blocks 6 and applied against the armature blocks 6, ensuring at least point-like, linear, and / or surface-like contact in each case. The wedge angle with respect to the individual magnets 8 is, for example, 2°. Due to tolerances, ideal full-surface contact between the magnets 8 and the associated armature blocks 6 via their contact surfaces cannot be achieved. Rather, only locally achievable, at least point-like, linear, and / or surface-like contact can be achieved.

[0035] In any case, this is an improvement over the prior art, according to which the armature blocks are designed circumferentially so that the individual magnets can be inserted into the receiving shafts formed by the armature blocks without being significantly scratched. The distances or air gaps that inevitably arise between the individual magnets and the associated armature blocks after insertion, which can be approximately 0.1 to 0.3 mm, are filled with a plastic during the overmolding of the annular arrangement of the individual armature blocks and magnets. Such a thin plastic film between the individual armature blocks and magnets has a detrimental effect on the magnetic flux in the armature structure of the rotor.

[0036] Fig. 3 illustrates an example of a ten-pole rotor 2 in a so-called collector design with the Fig. 1 and Fig. 2. A rotor in such a collector design collects the magnetic field lines of two adjacent magnets and then bundles them radially and conducts them into a stator. The north pole formed on the side of an armature block 6 by the collector design ultimately represents a north pole that is twice as strong as that of a single magnet 8. Furthermore, a plastic overmolding 12 is provided inside the annular arrangement 4 for connection to a shaft (not shown here) and / or a hub for connection to a shaft. In this embodiment, the annular arrangement 4 can only be connected to the shaft or hub via the plastic overmolding 12. In this respect, the plastic overmolding 12 is absolutely necessary in this case and functions as a direct or indirect link to the shaft (not shown here), via which torque is to be transmitted.The advantage of such an embodiment is that, due to the lack of metallic connecting sections to the shaft formed internally to the annular arrangement 4, no magnetic leakage to the shaft occurs. This also improves the magnetic flux in such a rotor.

[0037] The plastic overmolding contributes to the structural support of the metal connecting sections and, on the other hand, to the weight savings of such a proposed rotor. The plastic overmolding allows the metal armature structure to be designed with exceptional precision.

[0038] In the Fig. 1, Fig. 2, Fig. In the annular arrangement 4 of the individual armature blocks 6 and magnets 8 shown in Figure 3, the respective armature blocks 6 are concave on an inner side facing a rotor center axis X-X. The concave design of the inner side is defined by two mutually inclined side sections that form a V-shape. These individual V-shapes form a polygonal shape with a total of 10 corners with respect to the arrangement 4, which forms a positive connection with the plastic overmolding 12. In this respect, such a V-shape also represents an anchoring means with respect to the plastic overmolding 12.

[0039] In addition or alternatively to such an internally concave design of the anchor blocks, the respective anchor blocks can also be provided with at least one anchoring means (not shown here) on an inner side facing a rotor center axis XX, which extends from the associated anchor block into the plastic overmolding. For an illustration of such an anchoring, reference is hereby made to the German patent application with the application number DE 10 2016 209 174.3, which is hereby incorporated by reference into the disclosure of the present invention.

[0040] Furthermore, the grooves formed on the outside of the rotor 2 between each two adjacent armature blocks 6, which are formed by the two armature blocks 6 and the magnet 8 arranged therebetween, can be filled and thus covered during the plastic overmolding 12. These resulting injection-molded sections 14, which fill and cover the grooves, are flush with the outside of the armature blocks 6, for example.

[0041] Fig. Figure 3 further illustrates a tool with a circular inner tool wall 20, to which the individual armature blocks 6 and magnets 8 are placed, approximately one after the other, to form the annular arrangement 4, by placing such an armature block 6 on a fixing pin (not shown here) that extends through the elongated hole 10 of the associated armature block 6. The elongated hole 10 enables a radial displacement of the associated armature block 6 to bear against the inner tool wall 20. Each individual magnet 8 is further assigned a tool mandrel (not shown here), via which the magnet 8 is pressed in the radial direction against the respectively associated armature blocks 6, so that at least a local point-like, linear and / or surface-like contact with the armature blocks 6 is created. Although the individual tool mandrels in the Fig. 3 are not shown, but the through holes 18 created by the individual tool mandrels are shown. These holes are created when the tool mandrels are removed from the tool after the plastic overmolding process. Thus, the tool mandrels can be imagined as replacing the through holes 18.

[0042] For clarification, it should be expressly mentioned at this point that only a relatively small amount of force is required to press the individual magnets 8 together using the associated tool mandrel, with a force of no more than approximately 10 N being considered sufficient. Therefore, there can be no question of severe jamming of the individual magnets, so that scratching of the respective magnet surfaces or contact surfaces of the magnets 8 is avoided, or at least almost completely avoided.

[0043] In the embodiment according to Fig.3, the plastic 12, which has a through hole 16 coaxial with the longitudinal axis X-X of the rotor 2, can be injection-molded onto a shaft and / or hub (not shown here) for connection to a shaft. The relevant connection options to a hub are known to those skilled in the art, so they will not be discussed further.

[0044] Although exemplary embodiments have been explained in the preceding description, it should be noted that numerous modifications are possible. Furthermore, it should be noted that the exemplary embodiments are merely examples and are not intended to limit the scope of protection, applications, or structure in any way. Rather, the preceding description provides the skilled person with a guide for implementing at least one exemplary embodiment, whereby various modifications, particularly with regard to the function and arrangement of the described components, can be made without departing from the scope of protection as it results from the claims and equivalent combinations of features.

Claims

[1] Rotor of an electric motor, comprising several anchor sections and a plurality of magnets (8) which, in conjunction with the armature sections (6), are assembled to form an at least substantially annular arrangement (4) and the magnets (8) arranged between two adjacent armature sections (6) are wedge-shaped and are applied against the armature sections (6) to form at least a point-shaped, linear and / or planar contact, characterized by , that the anchor sections are designed in the form of individual loose anchor blocks (6), a plastic overmoulding (12) is provided inside the annular arrangement (4) for connecting the annular arrangement (4) to a shaft and / or a hub for connection to a shaft, and the annular arrangement (4) can only be connected to the shaft or hub via the plastic overmolding (12). [2] Rotor according to claim 1, characterized by that the magnets (8) are aligned at least substantially radially to the annular arrangement (4). [3] Rotor according to claim 1 or 2, characterized by that the wedge shape of the magnets (8) tapers towards the outer circumference of the annular arrangement (4). [4] Rotor according to one of the preceding claims, characterized by that the individual, loose anchor blocks (6) are each anchored on an inner side facing a rotor center axis (X - X) at least by means of an anchoring means in the plastic encapsulation (12). [5] Rotor according to claim 4, characterized by that the at least one anchoring means extends from the associated anchor block (6) into the plastic encapsulation (12). [6] Rotor according to claim 5, characterized by that the at least one anchoring means is eyelet-shaped, hook-shaped and / or pin-shaped. [7] Rotor according to one of the preceding claims, characterized by that the armature blocks (6) and the magnets (8) are individually and alternately assembled to form the substantially annular arrangement (4). [8] Rotor according to claim 7, characterized by that a single magnet (8) is arranged between each two adjacent armature blocks (6). [9] Rotor according to one of the preceding claims, characterized by that each individual anchor block (6) is formed from a plurality of punched sheets which are assembled to form the anchor block (6). [10] Rotor according to one of the preceding claims, characterized by that the plastic overmolding (12) is formed from an overmolded thermoplastic or thermosetting plastic. [11] Electric motor with a rotor (2) according to one of claims 1 to 10. [12] Actuator unit with an electric motor according to claim 11. [13] Vehicle with an electric motor according to claim 11 and / or an actuator unit according to claim 12. [14] Method for producing a rotor according to one of claims 1 to 10, in which, by means of a tool comprising at least one substantially circular tool inner wall (20), a plurality of armature sections in the form of individual loose armature blocks (6) and a plurality of wedge-shaped magnets (8) are assembled to form an at least substantially annular arrangement (4) by placing the individual armature blocks (6) against the tool inner wall (20), wherein at least one wedge-shaped magnet (8) is arranged between each two adjacent armature blocks (6) and is placed against the armature blocks (6) to form a point-shaped, linear and / or planar contact,wherein, lying inside the substantially annular arrangement of the individual armature blocks (6) and the individual magnets (8), the rotor (2) is overmolded with a plastic (12) for structural connection to a shaft and / or hub for connection to a shaft, and wherein the annular arrangement (4) is connected to the shaft or hub only via the plastic overmold (12). [15] Method according to claim 14, wherein each individual magnet (8) is pressed by means of an associated tool mandrel (18) in the radial direction against the respectively associated armature block (6) in order to ensure the point-shaped, linear and / or planar contact.

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