MIXED MAGNETIC ROTOR WITH POLYMERUM SPRAY PRESSURE RINGS

Abstract

A motor for a vehicle includes a rotor assembly. The rotor assembly includes a rotor core comprising several laminations, the rotor core having a cylindrical housing with a rotor bore, the cylindrical housing having a first end face at a first longitudinal end and a second end face at a second longitudinal end, a groove through the housing of the rotor core, the groove extending along a longitudinal axis of the rotor core from the first longitudinal end to the second longitudinal end, a magnet arranged in the groove, an end face of the magnet being located at the first end face of the first longitudinal end, and a polymer end ring at the first longitudinal end, the polymer end ring covering the end face of the magnet at a first end face and forming a composite cage integrated into the rotor core.

Description

[0001] The present disclosure relates to electric motors used in vehicles, and in particular to a rotor arrangement of the electric motor having overmolded end rings.

[0002] An electric motor comprises a stator and a rotor that rotates around an axis within the stator. The rotor may be manufactured from a rotor assembly having axially extending slots. These slots contain magnets. End rings are arranged at opposite axial ends of the rotor to receive the magnets. To fit the end rings, the ends of the magnets generally need to be filed or ground down to be flush with the rotor's end face or to be completely within the slots. Such procedures are time-consuming and difficult to perform. Therefore, it is desirable to provide a method for forming an end ring on the rotor assembly that encloses any portions of magnets that may protrude from the slot. SUMMARY

[0003] According to an exemplary embodiment, a method for manufacturing a rotor assembly is disclosed. Several laminations are stacked to form a rotor core, the rotor core comprising a cylindrical housing with a rotor bore, and the cylindrical housing having a first end face at a first longitudinal end and a second end face at a second longitudinal end. A groove is formed through the rotor core, the groove extending from the first longitudinal end to the second longitudinal end along a longitudinal axis of the rotor core. A magnet is arranged in the groove, with an end face section of the magnet located at the first end face of the first longitudinal end. A polymer end ring is formed at the first longitudinal end to cover the end face section of the magnet at the first end face, the polymer end ring forming a composite cage that is integrated into the rotor core.

[0004] In addition to one or more of the features described here, the end face of the magnet protrudes from the groove on the first end face.

[0005] In addition to one or more of the features described here, the method also includes the adhesion of the composite cage to the rotor core on the inside of a groove.

[0006] In addition to one or more of the features described here, the polymer end ring is reinforced by a metallic rim.

[0007] In addition to one or more of the features described herein, the end face of the magnet includes an adhesive feature, the method further comprising enclosing the adhesive feature with the polymer end face ring to adhere the end face of the magnet to the polymer end face ring.

[0008] According to a further exemplary embodiment, a rotor assembly is disclosed. The rotor assembly comprises a rotor core, wherein a groove extends through a housing of the rotor core, a magnet arranged in the groove, and a polymer end ring. The rotor core contains several laminations and has a cylindrical housing with a rotor bore. The cylindrical housing has a first end face at a first longitudinal end and a second end face at a second longitudinal end. The groove extends along a longitudinal axis of the rotor core from the first longitudinal end to the second longitudinal end. The magnet is arranged in the groove, with an end face of the magnet located at the first end face of the first longitudinal end. The polymer end ring is located at the first longitudinal end, covers the end face of the magnet at the first end face, and forms a composite cage that is integrated into the rotor core.

[0009] In addition to one or more of the features described here, the end face of the magnet protrudes from the groove on the first end face.

[0010] In addition to one or more of the features described herein, the groove further comprises a first groove and a second groove, and the magnet contains a first magnet arranged in the first groove and a second magnet arranged in the second groove, wherein the first magnet and the second magnet consist of a first material and a second material respectively and / or a ferrite magnet and a neodymium magnet respectively and / or a polished magnet and an unpolished magnet respectively.

[0011] In addition to one or more of the features described here, the composite cage also has a hollow structure that allows the passage of a cooling fluid through the rotor core.

[0012] In addition to one or more of the features described here, the composite cage is filled with at least one fiberglass.

[0013] In addition to one or more of the features described here, the composite cage adheres to the rotor core via an inner groove.

[0014] In addition to one or more of the features described here, the polymer end ring is reinforced by a metallic rim.

[0015] In addition to one or more of the features described here, the end face of the magnet contains an adhesive feature and the polymer end face ring surrounds the adhesive feature to adhere the end face of the magnet to the polymer end face ring.

[0016] In a further exemplary embodiment, a vehicle is disclosed. The motor includes a motor comprising a stator having a stator bore and a rotor assembly arranged in the stator bore and configured to rotate within the stator.The rotor assembly includes a rotor core comprising several laminations, the rotor core having a cylindrical housing with a rotor bore, the cylindrical housing having a first end face at a first longitudinal end and a second end face at a second longitudinal end, having a groove through the housing of the rotor core, the groove extending along a longitudinal axis of the rotor core from the first longitudinal end to the second longitudinal end, containing a magnet arranged in the groove, with an end face of the magnet located at the first end face of the first longitudinal end, and containing a polymer end ring at the first longitudinal end, the polymer end ring covering the end face of the magnet at a first end face and forming a composite cage integrated into the rotor core.

[0017] In addition to one or more of the features described here, the end face of the magnet protrudes from the groove on the first end face.

[0018] In addition to one or more of the features described herein, the groove further comprises a first groove and a second groove, and the magnet contains a first magnet arranged in the first groove and a second magnet arranged in the second groove, wherein the first magnet and the second magnet consist of a first material and a second material respectively and / or a ferrite magnet and a neodymium magnet respectively and / or a polished magnet and an unpolished magnet respectively.

[0019] In addition to one or more of the features described here, the composite cage also has a hollow structure that allows the passage of a cooling fluid through the rotor core.

[0020] In addition to one or more of the features described here, the composite cage is filled with at least one glass fiber and / or the composite cage adheres to the inside of a groove on the rotor stack core.

[0021] In addition to one or more of the features described here, the polymer end ring is reinforced by a metallic rim.

[0022] In addition to one or more of the features described here, the end face of the magnet contains an adhesive feature and the polymer end face ring surrounds the adhesive feature to adhere the end face of the magnet to the polymer end face ring.

[0023] The features and advantages described above, and further features and advantages of the disclosure, will become apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Further features, advantages and details appear only as examples in the following detailed description, which refers to the drawings; they show: Fig. 1 a schematic view of an engine in accordance with an exemplary embodiment; Fig. 2 a side view of a rotor of the motor according to an illustrative embodiment; Fig. 3 a perspective top view of the rotor according to one embodiment; Fig. 4 a representation showing an injection molding process for the rotor; Fig. 5 a perspective view of the rotor core after an injection molding process; Fig. 6 a lateral cross-sectional view of the rotor core with polymer end rings according to one embodiment; Fig. 7 an enlarged view of the rotor core in the rectangle of Fig. 6; Fig. 8 a lateral cross-sectional view of the rotor core with polymer end rings according to a further embodiment; Fig. 9 a lateral cross-sectional view of a groove at a first end of the rotor core according to one embodiment; and Fig. 10 a vehicle that has the engine of Fig. 1 contains. DETAILED DESCRIPTION

[0025] The following description is merely exemplary and is not intended to limit the present disclosure, its application, or uses. It should be understood that, throughout the drawings, corresponding reference numerals denote similar or corresponding sections and features.

[0026] According to an exemplary embodiment, Fig. Figure 1 shows a schematic view of a motor 100. The motor 100 can be a motor used in a vehicle. The motor 100 includes a stator 102, which has a stator bore 104 along a longitudinal axis 108. A rotor 106 is arranged in the stator bore 104. The rotor 106 rotates within the stator 102 about the longitudinal axis 108. The rotor 106 has a rotor bore 109, and a rotor shaft 110 is arranged in the rotor bore. The rotor shaft 110 is mechanically connected to the rotor 106 and rotates with the rotor to transmit power and / or torque to various components of the vehicle, such as a power unit, a transmission, wheels, etc.

[0027] Fig. Figure 2 shows a side view 200 of the rotor 106 according to an illustrative embodiment. The rotor 106 comprises several laminations 202a-202n stacked one above the other along the longitudinal axis 108 to form a rotor core 204. The rotor core 204 has a cylindrical housing extending from a first longitudinal end 206 to a second longitudinal end 208. The rotor core 204 has a first end face 210 at the first longitudinal end 206 and a second end face 212 at the second longitudinal end 208. A rotor bore 214 of the rotor core 204 (in which the rotor shaft 110 is arranged) is indicated by dashed lines. Several grooves are formed within the housing of the rotor core 204 to accommodate magnets. For illustration, a groove 216 within the rotor core 204 is indicated by dashed lines. The groove 216 runs from the first end face 210 to the second end face 212 and passes through each of the multiple sheets 202a-202n.

[0028] A first end ring 218 of the rotor 106 is formed on the first end face 210 and a second end ring 220 is formed on the second end face 212.

[0029] The first end ring 218 and / or the second end ring 220 can be a polymer end ring that is formed during an injection stage as part of the manufacture of the rotor.

[0030] Fig. Figure 3 shows a perspective top view 300 of the rotor 106 according to one embodiment. The perspective view 300 shows one or more slots in the rotor core 204. The slots 216 are generally arranged in groups. For illustration, groups G1-G8 are shown. The slots 216 can have a selected arrangement within each group. Each slot has a magnet arranged therein. The magnets extend along the longitudinal axis 108 of the rotor. A magnet within a slot can be a single magnet or multiple magnets stacked within the slot along the longitudinal axis.

[0031] For illustration, the slots 216 of group G1 are explained. A first main slot 302 and a second main slot 304 form a first V-shape, with an open end of the first V-shape facing the outer edge 310 of the rotor core 204. A first secondary slot 306 and a second secondary slot 308 form a second V-shape, with an open end of the second V-shape facing the outer edge 310. A first main magnet 312 is arranged within the first main slot 302, and a second main magnet 314 is arranged within the second main slot 304. A first secondary magnet 316 is arranged within the first secondary slot 306, and a second secondary magnet 318 is arranged within the second secondary slot 308. Cooling channels, such as the cooling channel 320, are arranged circumferentially at locations between the groups.

[0032] The slots can accommodate different types of magnets. For example, a first slot can hold a first magnet made of a first material, and a second slot can hold a second magnet made of a second material. In one embodiment, the first material can be ferrite and the second material neodymium. The first magnet can be a polished magnet, and the second magnet an unpolished magnet. For example, the ferrite magnet can be polished, and the neodymium magnet unpolished.

[0033] Fig. Figure 4 shows a diagram 400 illustrating an injection molding process for the rotor. An injection mold 402 is shown, containing a central cylinder 404 arranged along the central axis 108 of the rotor core 204. A polymer is injected from the central cylinder 404 into the slots 216 via various branches, sub-branches, and nozzles. A branch 406 extends radially outward from the central cylinder 404 above the first end face 210 of the rotor core 204. Although only one branch is shown, several branches can extend from the central cylinder 404. The branch 406 has one or more sub-branches 408a-408c. Each of the one or more sub-branches 408a-408c has one or more nozzles extending to the first end face and into a corresponding slot 216.A first sub-branch 408a contains a first nozzle 410 for injection into the first main groove 302 and a second nozzle 412 for injection into the first secondary groove 306. The second sub-branch 408b contains nozzles (nozzles 414, 416, 418 are visible) for each of the grooves. The third sub-branch 408c contains a nozzle 420 for injecting the polymer into the second main groove 304 and a nozzle 422 for injecting the polymer into the second secondary groove 308.

[0034] Fig. Figure 5 shows a perspective view 500 of the rotor core 204 after an injection molding process. The polymer 502 shown covers the various grooves 216 of the rotor core 204 and also encloses the magnets.

[0035] While the Fig. 3-5 where the polymer within the slots of the rotor core does not show polymer end rings, it is understood that the methods disclosed herein relate to the injection of polymer to form a single structure which includes the polymer end rings and also a cage structure within the slots of the rotor core.

[0036] Fig. Figure 6 shows a side cross-sectional view 600, which shows a tool configuration of the rotor core 204 for forming polymer end rings according to one embodiment. A tooling device 602 encloses sections of the rotor core 204. The rotor core 204 has a groove 216 and contains a magnet stack 606 within the groove. The magnet stack 606 contains several magnets 606a-606d that are stacked within the groove 216 along the longitudinal axis 108 of the rotor core 204. An end magnet 606a, or upper magnet of the magnet stack 606, has a section that projects from the groove 604 and over the first end face 210 of the rotor core 204. Similarly, the end magnet 606d can have a section that projects from the groove 604 under the second end face 212.

[0037] The tooling fixture 602 surrounds the ends of the rotor core 204, the rotor bore, and the cooling channel 320. The tooling fixture 602 includes a conduit 608 for introducing the polymer into the rotor core 204. A nozzle 610 extends through the conduit 608 of the tooling fixture 602. The nozzle 610 introduces a polymer 502 into the conduit 608. The polymer 502 spreads over the first end face 210 of the rotor core 204 to form a first end ring 218. The polymer 502 also flows into and through the groove 604 and between the magnets 606a-606d to bind the magnets in place within the groove. The polymer 502 flows between the magnets and forms layers (e.g., layer 612) between adjacent magnets (e.g., end magnet 606a and magnet 606b). The polymer 502 flows out of the groove 604 at the second longitudinal end 208 to spread over the second end face 212 of the rotor core 204 and form the second end ring 220. Fig. Figure 7 shows a magnification of an area defined by rectangle 620.

[0038] The polymer 502 can assume the form of a composite cage by flowing into the slots of the rotor core. The composite cage can have a hollow structure that allows the passage of a cooling fluid through the rotor core. According to one embodiment, the polymer is filled with at least one glass fiber. The composite cage adheres to an inner surface of the slot 604 on the rotor core.

[0039] Fig. Figure 7 shows an enlarged view 700 of the rotor core 204 within the rectangle 620 of Fig. 6. The enlarged view 700 shows the groove 216 on the first end face 210. An end magnet 606a is arranged in the groove 216. An end section 702 of the end magnet 606a projects from the first end face 210 out of the groove 216 by a distance d. The first end ring 218 forms a polymer cover that covers the end section 702 of the end magnet 606a.

[0040] Fig. Figure 8 shows a side cross-sectional view 800 of the rotor core 204 with polymer end rings according to a further embodiment. The side cross-sectional view 800 shows a first metal ring 802, which provides reinforcement for the polymer of the first end ring 218, and a second metal ring 804, which provides reinforcement for the polymer of the second end ring 220. The metal ring can be located between the polymer 502 and the rotor core. Alternatively, the polymer 502 can be located between the metal ring and the rotor core. The metal can be aluminum according to various embodiments. Therefore, the first end ring 218 is a bi-material (i.e., it contains the polymer of the first end ring 218 and the metal of the first metal ring 802). Similarly, the second end ring 220 is a bi-material (i.e., it contains the polymer of the second end ring 220 and the metal of the second metal ring 804).

[0041] Fig. Figure 9 shows a side cross-sectional view 900 of a groove 902 at a first end of the rotor core according to one embodiment. An end magnet 904 is arranged in the groove and includes an adhesion feature 906 that promotes adhesion between the polymer 502 and the end magnet 904. According to one embodiment, the adhesion feature 906 may include a notch 908 or a rough surface at the end of the magnet. The polymer 502 completely encloses the portion of the magnet that protrudes from the groove containing the notch 908. According to another embodiment, the adhesion feature 906 may be an adhesive substance. The end of the magnet may be degreased and then treated with silane, a conversion coating, a resin, or another adhesion-promoting chemical. The resin may be a polyurethane or an acrylic that is inherently metal-adherent. The polymer may completely enclose the portion of the magnet that protrudes from the electrical steel core.

[0042] Fig. 10 shows a vehicle 1000, which has the engine of Fig. 1 contains.

[0043] The terms "a" and "an" do not denote a limit on the number of elements, but rather indicate the presence of at least one of the referenced element. The term "or" means "and / or" unless clearly indicated otherwise by context. A reference to "an aspect" in the application text means that a specific element (e.g., a feature, a structure, a step, or a property) described in connection with that aspect is contained in at least one aspect described therein and may or may not be present in other aspects. It should also be understood that the described elements in the various aspects may be combined in any suitable manner.

[0044] When an element, such as a layer, a thin layer, an area, or a substrate, is described as "attached" to another element, it may be located directly adjacent to that element, or there may be intervening elements. Conversely, when an element is described as "directly adjacent" to another element, there are no intervening elements.

[0045] Unless otherwise specified herein, all testing standards shall be the most recent valid standard as of the filing date of this application or, if priority is claimed, as of the filing date of the earliest priority application in which the testing standard appears.

[0046] Unless otherwise defined, technical and scientific terms used herein have the same meaning as would normally be understood by a person skilled in the field to which this disclosure belongs.

[0047] While the disclosure described above has been described with reference to exemplary embodiments, those skilled in the art will understand that various modifications can be made and elements can be replaced by their equivalents without altering its scope. Furthermore, many adaptations can be made to fit a particular situation or material to the instructions given in the disclosure without deviating from its essential scope. Therefore, it is intended that the present disclosure is not limited to the specific embodiments disclosed, but includes all embodiments that fall within its scope.

Claims

[1] Method for manufacturing a rotor assembly comprising: Stacking several laminations to form a rotor core, wherein the rotor core has a cylindrical housing with a rotor bore, the cylindrical housing having a first end face at a first longitudinal end and a second end face at a second longitudinal end; Forming a groove through the rotor core, wherein the groove runs from the first longitudinal end to the second longitudinal end along a longitudinal axis of the rotor core; Arranging a magnet in the groove, wherein an end face of the magnet is located at the first end face of the first longitudinal end; and Forming a polymer end ring at the first longitudinal end to cover the end section of the magnet at the first end face, the polymer end ring forming a composite cage integrated into the rotor core. [2] Method according to claim 1, wherein the end section of the magnet protrudes from the groove at the first end face. [3] Method according to claim 1, further comprising adhering the composite cage to the rotor core on an inner side of a groove. [4] Method according to claim 1, wherein the end section of the magnet includes an adhesive feature, which further comprises enclosing the adhesive feature with the polymer end ring to adhere the end section of the magnet to the polymer end ring. [5] Rotor arrangement comprising: a rotor core containing several laminations, wherein the rotor core has a cylindrical housing with a rotor bore, the cylindrical housing having a first end face at a first longitudinal end and a second end face at a second longitudinal end; a groove through the cylindrical housing of the rotor core, wherein the groove runs from the first longitudinal end to the second longitudinal end along a longitudinal axis of the rotor core; a magnet arranged in the groove, wherein an end face of the magnet is located at the first end face of the first longitudinal end; and a polymer end ring at the first longitudinal end, wherein the polymer end ring covers the end section of the magnet at the first end face and extends into the groove to form a composite cage integrated into the rotor core. [6] Rotor arrangement according to claim 5, wherein the end section of the magnet protrudes from the groove at the first end face. [7] Rotor arrangement according to claim 5, wherein the groove further comprises a first groove and a second groove and the magnet comprises a first magnet arranged in the first groove and a second magnet arranged in the second groove, and wherein the first magnet and the second magnet (i) consist of a first material or a second material and / or (ii) a ferrite magnet or a neodymium magnet and / or (iii) a polished or an unpolished magnet. [8] Rotor arrangement according to claim 5, wherein the composite cage further comprises a hollow structure that allows the passage of a cooling fluid through the rotor core. [9] Rotor arrangement according to claim 5, wherein the polymer end ring is reinforced by a metallic rim. [10] Rotor arrangement according to claim 5, wherein the end section of the magnet includes an adhesive feature and the polymer end ring surrounds the adhesive feature to adhere the end section of the magnet to the polymer end ring.

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