Rotor core with carrier polymer and insert

Abstract

A rotor core for an automotive electric motor includes a core stack comprising a plurality of laminated plates. Each laminated plate includes a plurality of holes formed therein. The plurality of holes of each laminated plate are axially aligned and define slots that extend through the core stack and are shaped to accommodate corresponding inserts. The rotor core further includes at least one insert accommodated by the slots, the insert providing radial structural stability to the plurality of laminated plates to prevent bending of portions of the plurality of laminated plates disposed adjacent to a plurality of magnet slots during operation of the rotor core due to radial forces exerted on the plurality of laminated plates. The rotor core includes a bearing polymer disposed within the holes of the rotor core, the bearing polymer providing contact between the insert and the laminated plates.

Description

Technical Field

[0001] This disclosure relates to a rotor core for use in an electric motor in an automobile. More specifically, this disclosure relates to a rotor core having a plurality of laminates, at least one insert providing radial structural stability to the plurality of laminates, and a carrier polymer providing contact between the insert and the rotor core. This disclosure also relates to a method for assembling the rotor core. Background Technology

[0002] An electric motor, such as a built-in permanent magnet motor or a synchronous motor, includes a rotor assembly with a rotor core having magnets of alternating polarity around it. Some of the rotor cores define multiple slots that act as magnetic field blocking layers. Some of these slots contain the magnets.

[0003] Due to centrifugal force, the stress level in the rotor core is typically highest at the web or bridge plates. Increasing the thickness of the web or bridge plates or increasing the radius of curvature of the slots defining the web or bridge plates can reduce this stress, but torque will also decrease due to increased magnetic leakage. Selective heat treatment of the stainless steel laminates forming the rotor core can provide additional strength without the corresponding reduction in torque and permeability caused by magnetic leakage. This translates to increased torque or increased strength by increasing the cross-section without the loss of torque / magnetic leakage, as they are now impermeable. However, this approach can significantly increase the cost of the rotor.

[0004] In another approach, inserts made of a non-magnetic material are used to provide radial structural stability for multiple laminates that are part of a core stack of the rotor core. In this method, the laminates define a set of magnet slots symmetrically arranged around the core stack, each slot housing a permanent magnet, and an insert is provided for each set of magnet slots. During rotor core operation, the inserts prevent the portion of the laminates closest to the magnet slots from bending due to radial forces applied to the laminates. However, the inserts require two seemingly contradictory features: a gap between the insert and the laminate to allow for low-cost manufacturing and assembly, and contact between the insert and the laminate to effectively transfer loads.

[0005] Therefore, although existing rotor cores have achieved their intended purpose, there is still a need in the art for an improved rotor core that includes at least one insert providing radial structural stability, wherein the rotor core is relatively simple to manufacture and assemble and is inexpensive. Summary of the Invention

[0006] According to several aspects, a rotor core for an electric motor is disclosed, the rotor core comprising a core stack including a plurality of laminates. Each laminate includes a plurality of holes formed therein. The plurality of holes of each of the laminates are axially aligned and each defines a plurality of axial magnet slots extending through the core stack, the core stack being shaped to receive corresponding permanent magnet inserts therein, and further defining slots extending through the core stack and shaped to receive the corresponding inserts. The rotor core also includes at least one insert received by the slots of the rotor core, the insert providing radial structural stability to the plurality of laminates to prevent bending of portions of the plurality of laminates adjacent to the axial magnet slots due to radial forces applied to the plurality of laminates during rotor core operation. The rotor core also includes a carrier polymer disposed within the rotor core holes, wherein the carrier polymer provides contact between the insert and the laminates.

[0007] On the other hand, the carrier polymer can be a thermoplastic polymer or a thermosetting polymer.

[0008] On one hand, the at least one insert includes a first distal end and a second distal end, wherein the first distal end of the insert is adjacent to the outer diameter of the core stack, and the second distal end of the insert is adjacent to the inner diameter of the core stack.

[0009] On the other hand, the first distal end of the insert includes a flange, and a portion of the flange is in direct contact with the laminate of the rotor core.

[0010] On the other hand, the flange includes a flat surface and two bevels, and only the two bevels of the flange of the insert are in direct contact with the laminate of the rotor core.

[0011] On the other hand, the first distal end of the insert includes a flange, and a portion of the flange is in direct contact with the carrier polymer.

[0012] On one hand, a portion of the second distal end of the insert is in direct contact with the carrier polymer.

[0013] On the other hand, the second distal end of the insert includes a flange having a flat surface and two bevels, and only the two bevels of the flange of the insert are in direct contact with the carrier polymer.

[0014] On the other hand, the second distal end of the insert includes a flange, and a portion of the flange is in direct contact with the carrier polymer.

[0015] On one hand, the insert includes a pair of outwardly protruding bumps disposed on opposite sides of the insert, positioned directly above the magnetic flux guide in the middle of the rotor core.

[0016] On the other hand, a portion of each of the pair of outwardly protruding bumps is in direct contact with a portion of the carrier polymer, and the portion of the carrier polymer in direct contact with the pair of outwardly protruding bumps restricts the movement of the intermediate flux guide of the rotor core.

[0017] On the other hand, the insert includes a pair of hook-shaped protrusions disposed on opposite sides of the insert.

[0018] On the one hand, each of the pair of hook-shaped protrusions of the insert directly contacts and engages with a portion of the intermediate flux guide of the rotor core.

[0019] On the other hand, the insert includes a first pair of hook-shaped protrusions and a second pair of hook-shaped protrusions disposed on opposite sides of the insert.

[0020] On the other hand, each of the first pair of hook-shaped tabs engages with and is in direct contact with the carrier polymer, wherein the carrier polymer is disposed along an end surface defined by the outer flux guide of the rotor core.

[0021] On one hand, each of the second pair of hook-shaped tabs is in direct contact with the carrier polymer, wherein the carrier polymer is disposed along the outer surface defined by the intermediate flux guide of the rotor core.

[0022] On the other hand, the rotor core defines an inner flux guide, an intermediate flux guide, and an outer flux guide.

[0023] On the other hand, the intermediate flux guide defines a first retaining tab that protrudes inward toward the inner flux guide, and the outer flux guide defines a second retaining tab that protrudes outward toward the intermediate flux guide.

[0024] On the other hand, the carrier polymer is disposed between the first retaining tab and the magnetic insert.

[0025] On one hand, a method for assembling a rotor core is disclosed, the method comprising creating a temperature difference between the rotor core and at least one insert. The method includes receiving at least one insert through a slot in the rotor core. This temperature difference results in an interference fit between a first distal end and a second distal end of the at least one insert and the slot in the rotor core. The method further includes placing the rotor core into a die tool, wherein the die tool includes a plurality of rams. The method further includes applying a radial pressure to the outer diameter of the rotor core by the plurality of rams. Finally, the method includes injecting a carrier polymer into a gap feature within the rotor core while the plurality of rams apply the radial pressure to the outer diameter of the rotor core.

[0026] Further applicability will become apparent from the description provided herein. It should be understood that the above description and specific examples are for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0027] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way.

[0028] Figure 1 This is a perspective view of a core stack of rotor cores according to an exemplary embodiment of the present disclosure;

[0029] Figure 2 Is as such Figure 1 A front view of a single hole in a portion of the core stack shown;

[0030] Figure 3 Is it like this? Figure 2 The front view of the hole shown, according to an exemplary embodiment of the present disclosure, includes a plurality of magnetic inserts, a radial insert, and a carrier polymer;

[0031] Figure 4 According to an exemplary embodiment of this disclosure, such as Figure 3 A schematic diagram of the insert shown is presented.

[0032] Figure 5 According to an exemplary embodiment of this disclosure, such as Figure 3 An enlarged view of a portion of the rotor core shown;

[0033] Figure 6 This is an alternative embodiment of the insert installed within the rotor core according to an exemplary embodiment of the present disclosure;

[0034] Figure 7 This is another embodiment of the insert installed within the rotor core according to an exemplary embodiment of the present disclosure;

[0035] Figure 8 This is a process flow diagram illustrating a method for assembling the rotor core according to an exemplary embodiment of the present disclosure;

[0036] Figure 9 This is a schematic diagram of the magnetic insert according to an exemplary embodiment of the present disclosure and the insert assembled to the rotor core before the injection of the carrier polymer; and

[0037] Figure 10 This is a schematic diagram of the rotor core disposed within a mold tool according to an exemplary embodiment of the present disclosure. Detailed Implementation

[0038] The following description is exemplary in nature and is not intended to limit this disclosure, application, or use.

[0039] refer to Figure 1 The image shows a rotor core 10 for an electric motor. The rotor core 10 comprises a core stack 12 having a plurality of identical laminates 14. In one embodiment, the electric motor including the rotor core 10 is part of an automobile. For example, the rotor core 10 may be part of a starter, alternator, or automobile starter / generator. Each of the laminates 14 is made of an ferrous material such as, but not limited to, steel or non-oriented electrical steel. The laminates 14 are arranged adjacent to each other along a central axis 16 to define the core stack 12. Each of the laminates 14 includes a plurality of holes 17 formed therein. (See also...) Figure 1 and Figure 2 The laminates 14 are aligned relative to each other along the central axis 16 such that the holes 17 of each of the laminates 14 are axially aligned with the corresponding holes 17 of the adjacent laminates 14, thereby defining a plurality of axial magnet slots 18, slots 20 and a plurality of gap features 22 (the gap features are in Figure 2 (shown in dashed lines).

[0040] Continue to refer to Figure 1 and Figure 2 Each of the magnet slots 18, slots 20, and gaps 22 in each hole 17 extends axially through the core stack 12 parallel to the central axis 16. Each magnet slot 18 is shaped to accommodate a corresponding permanent magnet insert 40 (see [link to relevant documentation]). Figure 3 Each hole 17 has a slot 20 that extends axially through a core stack 12 parallel to the central axis 16 and is shaped to receive a corresponding insert 42 (see...). Figure 3 The rotor core 10 includes at least one insert 42. The gap feature 22 of each hole 17 also extends axially through the core stack 12 in a direction parallel to the central axis 16. The gap feature 22 provides a gap during assembly when the magnetic insert 40 is inserted into the corresponding magnet slot 18 and the insert 42 is inserted into the corresponding slot 20. As described below, once the magnetic insert 40 and the insert 42 are assembled to the rotor core 10, the carrier polymer 44 (see...) Figure 3 Then at least a portion of the gap feature 22 can be filled. As described above, the carrier polymer 44 is disposed within the hole 17 of the rotor core 10 to provide contact between the magnetic insert 40 and the laminate 14, and between the insert 42 and the laminate 14.

[0041] In one embodiment, the carrier polymer 44 may be a thermoplastic polymer or a thermosetting polymer. Examples of thermoplastic polymers serving as the carrier polymer 44 include, but are not limited to: polyamide, polyamide-imide, polyimide (thermoplastic), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyphthalamide (PPA), polyolefin, polypropylene, acrylonitrile-butadiene-styrene (ABS), polycarbonate (PC), polyvinyl chloride (PVC), and polyethylene. Examples of thermosetting polymers serving as the carrier polymer 44 include, but are not limited to: epoxy, phenolic, bismaleimide, benzoxazine, polyurethane, polyester, and polyimide. In one embodiment, the carrier polymer 44 may further include a reinforcing material; however, it should be understood that the reinforcing material is optional. The reinforcing material may be fibrous or granular. Examples of fibrous reinforcing materials include, but are not limited to: basalt and carbon fiber. Some examples of granular reinforcing materials include, but are not limited to: calcium carbonate / carbonate, mica, silicates, calcium sulfate, calcium metasilicate, clay, hydrated magnesium silicate, silicon dioxide, aluminum oxide, aluminum nitride, silicon nitride, and boron nitride.

[0042] In one non-limiting embodiment, the supporting polymer 44 has a tensile strength of at least about 40 MPa and, in one specific embodiment, at least about 60 MPa. In one exemplary embodiment, the supporting polymer 44 has a compressive strength of at least about 75 MPa and, in one specific embodiment, at least about 150 MPa. In one embodiment, the supporting polymer 44 has a glass transition temperature of about 120°C and, in one specific embodiment, about 150°C. In one exemplary embodiment, the supporting polymer 44 has a density of about 5000 kg / m³ and, in one specific embodiment, about 5000 kg / m³. In one exemplary embodiment, the supporting polymer 44 is non-magnetic. In one embodiment, the supporting polymer 44 is also non-conductive. In another embodiment, the supporting polymer 44 may produce non-corrosive byproducts.

[0043] In such Figure 1 In the illustrated embodiment, the core stack 12 includes eight symmetrical sets of 21 magnet slots 18. However, it should be understood that... Figure 1 This is merely an exemplary description, and the core stack 12 is not limited to eight sets of 21 magnet slots 18. Figure 1 and Figure 2 Each group 21 is shown to include four magnet slots 18 arranged in a V-shape. See details. Figure 2Each magnet slot 18 in group 21 further defines an outer flux guide 32, an intermediate flux guide 34, and an inner flux guide 36. The outer flux guide 32 is disposed near the outer diameter 58 of the core stack 12, the inner flux guide 32 is disposed near the inner diameter 59 of the core stack 12, and the intermediate flux guide 34 is disposed between the inner flux guide 32 and the inner flux guide 36. The outer, intermediate, and inner flux guides provide channels for the magnetic flux current running through the rotor core.

[0044] refer to Figure 2 and Figure 3 The slot 20 of the aperture 17 is formed to receive the insert 42. The rotor core 10 includes at least one insert 42 configured to provide radial structural stability to the plurality of laminates 14 to prevent the portion of the laminates 14 adjacent to the plurality of magnet slots 18 from bending due to radial forces applied to the laminates 14 during operation of the rotor core 10. More specifically, the insert 42 is associated with each group 21 of the magnet slots 18 of the rotor core 10. The insert 42 is configured to provide support to the outer flux guide 32, the intermediate flux guide 34, and the inner flux guide 36 of the rotor core 10 to prevent the outer flux guide 32, the intermediate flux guide 34, and the inner flux guide 36 from bending outward due to centrifugal forces when the rotor core 10 rotates during operation.

[0045] In one embodiment, each insert 42 is made entirely of austenitic or non-magnetic material. It should be understood that the efficiency of the magnetic flux current in the rotor core 10 decreases when ferrous or magnetic materials are connected to the poles of a magnet. Since the inserts 42 are made entirely of non-magnetic material, this efficiency loss is avoided, and the rotor core 10 can be designed with smaller magnets, thus reducing costs, and the inserts 42 can be made larger. In another exemplary embodiment, each of the inserts 42 is made entirely of high-strength ferrous material. In this embodiment, the rotor core 10 can rotate at higher speeds without increasing magnetic leakage.

[0046] Each of the inserts 42 includes one or more features configured to engage with a portion of the rotor core 10. Figure 3 and Figure 4 In the exemplary embodiment shown, the insert 42 includes a first distal end 50, a second distal end 52, a body portion 54 extending between the first distal end 50 and the second distal end 52, and a pair of opposing sides 56. See details. Figure 3The first distal end 50 of the insert 42 is disposed near the outer diameter 58 of the core stack 12, while the second distal end 52 of the insert 42 is disposed near the inner diameter 59 of the core stack 12. The insert 42 also includes a pair of outwardly protruding bumps 90 disposed on opposite sides 56 of the insert 42, directly above the intermediate flux guide 34 of the rotor core 10. The insert 42 also includes a pair of hook-shaped tabs 92 disposed on opposite sides 56 of the insert 42.

[0047] Continue to refer to Figure 3 and Figure 4 The first distal end 50 of the insert 42 includes a flange 60, a portion of which directly contacts the laminate 14 of the rotor core 10. Specifically, the flange 60 includes a flat surface 62 and two beveled surfaces 64. Only the two beveled surfaces 64 of the flange 60 of the insert 42 directly contact the laminate 14 of the rotor core 10. That is, the two beveled surfaces 64 of the flange 60 of the insert 42 have a metal-to-metal contact with the rotor core 10. Conversely, the flat surface 62 of the flange 60 of the insert 42 does not contact the laminate 14 of the rotor core 10. Instead, a gap 66 is located between the flat surface 62 of the flange 60 and the uppermost surface 68 of the slot 20. The gap 66 allows easy fitting of the insert 42 into the corresponding slot 20.

[0048] like Figure 3 As shown, a portion of the second distal end 52 of the insert 42 is in direct contact with the carrier polymer 44. Specifically, the second distal end 52 of the insert 42 includes a flange 70 having a flat surface 72 and two bevels 74. The two bevels 74 and the flat surface 72 of the flange 60 of the insert 42 are not in direct contact with the laminate 14 of the rotor core 10. However, the two bevels 74 of the flange 60 of the insert 42 are in direct contact with the carrier polymer 44. During assembly, the gap feature 22 is located at the distal end 80 of the groove 20 (see...). Figure 2 This acts as a tolerance device to facilitate assembly when fitting the insert 42 into the corresponding slot 20. (Reference) Figure 2 and Figure 3 Then the gap feature 22 is filled with the carrier polymer 44. Figure 3 As shown, the flat surface 72 of the flange 70 of the insert 42 does not contact the laminate 14 of the rotor core 10, but the gap 76 is located between the flat surface 72 of the flange 60 and the lowermost surface 82 of the groove 20.

[0049] For details, please refer to the following: Figure 4 A portion of each of the pair of outwardly projecting protrusions 90 is in direct contact with a portion of the carrier polymer 44. Specifically, each outwardly projecting protrusion 90 defines a pair of bevels 84, 86 connected by a flat surface 88. The upper bevel 84 is located near the first distal end 50 of the insert 42, while the lower bevel 86 is located near the hook-shaped protrusion 92 of the insert 42. Figure 3 As shown, the ramps 84, 86 and the flat surface 88 of each of the outwardly protruding bumps 90 do not directly contact the laminate 14 of the rotor core 10. The lower ramp 86 and a portion of the flat surface 88 of each of the plurality of outwardly protruding bumps 90 of the insert 42 directly contact the carrier polymer 44. Specifically, during assembly, the gap feature 22 located between the intermediate flux guide 34 and the flux guide bump 94 of the hole 17 ( Figure 2 This acts as a tolerance device to facilitate assembly when the insert 42 is inserted into the corresponding slot 20. (Reference) Figure 2 and Figure 3 The gap feature 22, which is provided between the intermediate flux guide 34 and the flux guide bump 94, is then filled with the carrier polymer 44.

[0050] refer to Figure 3 and Figure 4 The hook-shaped protrusion 92 of the insert 42 directly contacts and engages with a portion of the intermediate flux guide 34 of the rotor core 10. (Reference) Figure 4 Each of the hook-shaped tabs 92 includes an outwardly extending portion 100 and an upwardly extending support 102. The upwardly extending support 102 defines an inner surface 104. (See reference) Figure 3 and Figure 4 The inner surface 104 of the upwardly extending support 102 of each hook-shaped tab 92 is in direct contact with a surface 106 of the support 98 of the intermediate flux guide 34. That is, the pair of hook-shaped tabs 92 in the insert 42 have a metal-to-metal contact with the rotor core 10. The engagement between the hook-shaped tabs 92 of the insert 42 and the corresponding supports 98 of the intermediate flux guide 34 provides structural stability and prevents the intermediate flux guide 34 from bending outwards due to centrifugal force during operation.

[0051] Figure 5This is an enlarged view of the outer flux guide 32, the intermediate flux guide 34, the inner flux guide 36, and the inner magnetic insert 40. A first magnetic insert 40A is disposed between the outer flux guide 32 and the intermediate flux guide 34, while a second magnetic insert 40B is located between the intermediate flux guide 34 and the inner flux guide 36. A flux guide protrusion 94 is disposed within the first magnet slot 18A and holds the first magnetic insert 40A within the rotor core 10. Similarly, a flux guide protrusion 114 is also disposed within the second magnet slot 18B of the rotor core 10 and holds the second magnetic insert 40B within the rotor core 10. (Reference) Figure 2 and Figure 5 The gap feature 22 located between the first magnet slot 18A and the intermediate flux guide 34 fills the carrier polymer 44 during assembly. The intermediate flux guide 34 tends to move radially outward toward the first magnetic insert 40A, especially if a gap exists between the intermediate flux guide 34 and the first magnetic insert 40A. The carrier polymer 44 occupies the gap between the intermediate flux guide 34 and the first magnetic insert 40A and prevents movement of the intermediate flux guide 34. Instead, the carrier polymer 44 exerts centrifugal force on the outer flux guide 32.

[0052] Figure 6 This is an alternative embodiment of the insert 142, which is part of the rotor core 10. In such... Figure 6 In the illustrated embodiment, the first distal end 150 of the insert 142 is in direct contact with the carrier polymer 144, which in turn increases the stiffness of the external flux guide 32. Specifically, the first distal end 150 of the insert 142 includes a flange 160 having a flat surface 162 and two bevels 164. The two bevels 164 of the first distal end 150 of the insert 142 are not in direct contact with the laminate 14 of the rotor core 10. Instead, the two bevels 164 of the flange 160 of the insert 142 are in direct contact with the carrier polymer 144. A gap 166 is located between the flat surface 162 of the flange 160 and the uppermost surface 168 of the groove 20.

[0053] Continue to refer to Figure 6The second distal end 152 of the insert 142 includes a flange 170, a portion of which is in direct contact with the carrier polymer 144. Specifically, the flange 170 includes a flat surface 172 and two beveled surfaces 174. The two beveled surfaces 174 and the flat surface 172 of the flange 170 of the insert 142 contact the laminate 14 of the rotor core 10. That is, the second distal end 152 of the flange 170 has a metal-to-metal contact with the rotor core 10.

[0054] The insert 142 further includes a first pair of hook-shaped tabs 190 and a second pair of hook-shaped tabs 192 disposed on opposite sides 156 of the insert 142. Each of the first pair of hook-shaped tabs 190 defines an upwardly extending support 202 that engages with a carrier polymer 144 disposed along an end surface 196 defined by the external flux guide 32. Specifically, each of the first pair of hook-shaped tabs 190 includes an outwardly extending portion 200 and the upwardly extending support 202. The upwardly extending support 202 defines an inner surface 204. The inner surface 204 of each of the upwardly extending supports 202 of the first pair of hook-shaped tabs 190 is in direct contact with the carrier polymer 144. Each of the first pair of hook-shaped tabs 190 includes a bottom surface 206 defined by the outwardly extending portion 200. Each bottom surface 206 of the first pair of hook-shaped tabs 190 engages with a carrier polymer 144 disposed along a portion of an upper surface 208 defined by an intermediate magnetic flux guide 34.

[0055] Each of the second pair of hook-shaped tabs 192 includes an outward extension 210 and an upward extension bracket 212. The upward extension bracket 212 defines an inner surface 214. The inner surface 214 of the upward extension bracket 212 of each of the second pair of hook-shaped tabs 192 is in direct contact with the carrier polymer 144, which is disposed along the outer surface 216 of the bracket 220 defined by the intermediate flux guide 34. The engagement of the second pair of hook-shaped tabs 192 of the insert 142 with the corresponding bracket 220 of the intermediate flux guide 34 provides structural stability and prevents the intermediate flux guide 34 from bending outward due to centrifugal force when the rotor core 10 rotates during operation.

[0056] Figure 7 This is an alternative embodiment of the insert 342, which is part of the rotor core 10. In such... Figure 7 In the illustrated embodiment, the pair of hook-shaped protrusions 92 located on opposite sides 56 of the insert 42 are omitted (e.g., Figure 3(As shown). The intermediate flux guide 34 defines a first retaining tab 370 protruding inward toward the inner flux guide 36, while the outer flux guide 36 defines a second retaining tab 374 protruding outward toward the intermediate flux guide 34. The first retaining tab 370 defines a side surface 372. A carrier polymer 344 is disposed between the side surface 372 of the first retaining tab 370 and the side surface 378 of the second magnetic insert 40B. When the intermediate flux guide 34 wishes to slide / shear between the magnetic inserts 40A and 40B, the magnet of the second magnetic insert 40B resists the movement of the intermediate flux guide 34. Reference Figure 3 and Figure 7 Since the first retaining tab 370 and the second retaining tab 374 hold the second magnetic insert 40B in place, the flux guiding tab 114 disposed in the second magnet slot 18B of the rotor core 10 can be omitted (see Figure 3 The intermediate magnetic flux guide 34 is constrained in two orthogonal directions, namely a first direction D1 and a second direction D2, wherein the first direction D1 is aligned with the magnetic inserts 40A and 40B. The insert 42 restricts the movement of the intermediate magnetic flux guide 34 in the first direction D1 by contacting the pair of outwardly protruding bumps 90 with a portion of the carrying polymer 44. The second magnetic insert 40B, located between the intermediate magnetic flux guide 34 and the inner magnetic flux guide 36, can be used to restrict movement in the second direction D2 by the first retaining tab 370 and the carrying polymer 344.

[0057] The method for assembling the rotor core 10 is as follows. Figure 8 A process flow diagram of a method 400 for assembling the rotor core 10 is shown, and Figure 9 This is a schematic diagram of assembling the magnetic insert 40 and the insert 42 into the rotor core before injecting the carrier polymer 44. Figure 10 This is a schematic diagram of the rotor core 10 placed inside the mold tool 500, wherein a plurality of slides 550, which are part of the mold tool, apply pressure to the rotor core 10.

[0058] refer to Figure 8 and Figure 9 The method 400 begins at block 402. In block 402, a temperature difference is created between the rotor core 10 and the insert 42, wherein the rotor core 10 is cooled and the insert 42 is heated. Specifically, in one embodiment, a temperature difference of approximately 100°C may be generated between the rotor core 10 and the insert 42. Cooling the rotor core 10 causes contraction, while heating the insert 42 causes expansion. The method 400 then proceeds to block 404.

[0059] In frame 404, the insert 42 is subsequently received within the slot 20 of the rotor core 10. (Reference) Figure 9 The temperature difference causes an interference fit between the first distal end 50 and the second distal end 52 of the insert 42 and the slot 20 of the rotor core 10. Furthermore, the temperature difference between the rotor core 10 and the insert 42 causes beneficial stress to be generated in the bridging portion 48 of the rotor core 10. Method 400 then proceeds to block 406.

[0060] In block 406, the magnetic insert 40 is received within a corresponding magnet slot 18 of the rotor core 10. It should be understood that the magnetic insert 40 may also be inserted into the rotor core 10 prior to insert 42. Method 400 then proceeds to block 408.

[0061] In frame 408, the rotor core 10 is then placed within the mold tool 500 (see [link]). Figure 10 The mold tool 500 may be part of a compression molding machine or an injection molding machine. The mold tool 500 includes a top plate 502 and a bottom plate 504. Figure 10 As shown, the central axis 16 of the rotor core 10 is oriented perpendicular to the top plate 502 and bottom plate 504 of the mold tool 500. The top plate 502 of the mold tool 500 includes a flow channel 510 that allows molten polymer to flow into the gap feature 22 of the rotor core 10 (see Figure 22). Figure 2 The method 400 then proceeds to block 410.

[0062] In frame 410, a plurality of slides 550 apply radial pressure to the outer diameter 58 of the rotor core 10. (Reference) Figure 9 The plurality of slide blocks 550 apply a vertical pressure P1 to the outer diameter 58 of the rotor core 10 in a direction aligned with each end 78 of the first distal end 50 of the insert 42. This is done for each magnetic pole 46 of the rotor core 10. A tilting pressure P2 is also applied to the outer diameter 58 of the rotor core 10 in a direction aligned with the intermediate flux guide 34. The amounts of the vertical pressure P1 and the tilting pressure P2 applied to the outer diameter 58 of the rotor core 10 depend on the required preload stress S in the bridging portion 48. Specifically, the vertical pressure P1 and the tilting pressure P2 are applied to the rotor core 10 such that the required preload stress S in the bridging portion 48 is opposite to the stress borne by the bridge plate during operation of the rotor core 10. The method 400 then proceeds to block 412.

[0063] In frame 412, when the plurality of slides 550 apply radial pressure to the outer diameter 58 of the rotor core 10, the bearing polymer 44 ( Figure 3The material is injected into the gap feature 22 within the rotor core 10. The method 400 then proceeds to block 414.

[0064] In frame 414, the plurality of slides 550 cease applying pressure to the rotor core 10, the carrier polymer 44 solidifies, and the rotor core 10 is removed from the die tool 500. The method 400 then terminates.

[0065] Referring generally to the accompanying drawings, the disclosed rotor core and method of assembling the rotor core offer various technical effects and benefits. Specifically, the disclosed rotor core provides a gap between the insert and the laminate. Providing a gap between the insert and the rotor core results in low manufacturing and assembly costs. Furthermore, although a gap is provided between the insert and the rotor core during assembly, a load-bearing polymer is subsequently injected into the gap. The load-bearing polymer provides contact between the insert and the laminate to effectively transfer loads during rotor core operation.

[0066] The descriptions in this disclosure are exemplary in nature only, and any changes made without departing from the spirit and scope of this disclosure shall fall within its scope. Such changes should not be considered as departing from the spirit and scope of this disclosure.

Claims

1. A rotor core for an electric motor, comprising: A core stack comprising multiple laminates, wherein each laminate includes multiple holes formed therein, and wherein the multiple holes of each laminate are axially aligned and each hole defines multiple axial magnet slots extending through the core stack, the core stack being shaped to receive a corresponding permanent magnet insert therein, and defining a slot extending through the core stack and shaped to receive a corresponding insert. At least one insert received by the slot of the rotor core, the at least one insert providing radial structural stability to the plurality of laminates to prevent bending of portions of the plurality of laminates located adjacent to the plurality of axial magnet slots during operation of the rotor core due to radial forces applied to the plurality of laminates; and A carrier polymer disposed within the cavity of the rotor core, wherein the carrier polymer provides contact between the insert and the laminate; The plurality of axial magnet slots define an outer magnetic flux guide, a middle magnetic flux guide, and an inner magnetic flux guide. The outer magnetic flux guide is disposed near the outer diameter of the core stack, the inner magnetic flux guide is disposed near the inner diameter of the core stack, and the middle magnetic flux guide is disposed between the inner magnetic flux guide and the outer magnetic flux guide. The insert includes a pair of outwardly protruding bumps, which are disposed on opposite sides of the insert and located directly above the intermediate magnetic flux guide.

2. The rotor core according to claim 1, wherein, The carrier polymer is one of a thermoplastic polymer and a thermosetting polymer.

3. The rotor core according to claim 1, wherein, The at least one insert includes a first distal end and a second distal end, wherein the first distal end of the insert is configured to be adjacent to the outer diameter of the core stack, and the second distal end of the insert is configured to be adjacent to the inner diameter of the core stack.

4. The rotor core according to claim 3, wherein, The first distal end of the insert includes a flange, and a portion of the flange is in direct contact with the plurality of laminates of the rotor core.

5. The rotor core according to claim 4, wherein, The flange includes a flat surface and two beveled surfaces, wherein only the two beveled surfaces of the flange of the insert are in direct contact with the laminate of the rotor core.

6. The rotor core according to claim 3, wherein, The first distal end of the insert includes a flange, and a portion of the flange is in direct contact with the carrier polymer.

7. The rotor core according to claim 3, wherein, A portion of the second distal end of the insert is in direct contact with the carrier polymer.

8. The rotor core according to claim 7, wherein, The second distal end of the insert includes a flange having a flat surface and two bevels, wherein only the two bevels of the flange of the insert are in direct contact with the carrier polymer.

9. The rotor core according to claim 3, wherein, The second distal end of the insert includes a flange, and a portion of the flange is in direct contact with the carrier polymer.

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