Laminated scallop and shaft knurling

Abstract

The invention relates to a laminated scallop and shaft knurling. The electric machine includes a rotor press-fitted to the knurled section of the shaft. The rotor includes a lamination stack having a plurality of laminations. Each of the laminations includes a disc defining a central bore. A slot is defined in the disc. Each slot is configured to receive a magnet that at least partially defines a magnetic pole of the electric machine. The central bore has a circumference including a plurality of scallop-shaped portions. And each scallop-shaped part is intruded into the disc. The stator is disposed radially outside the rotor.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Application Serial No. 63 / 694,505, filed September 13, 2024, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to scallops and knurled shafts. Background Technology

[0004] In the field of rotor construction used in devices such as alternators, motors, and similar electrical machines, the rotor shaft is typically pressed into a set of laminations (called a lamination stack) to create a complete rotor. Traction motors are one such type of motor, commonly used in propulsion systems.

[0005] For many years, rotors have been constructed and commercially accepted in this manner. However, the extrusion process can still cause compression, deformation, cupping, and gaps within the rotor laminations. Compression deformation, cupping, and gaps can adversely affect the overall function of the rotor and are therefore undesirable.

[0006] There is an urgent need to provide assembly improvements to minimize the undesirable effects of the extrusion operation and improve motor performance. Summary of the Invention

[0007] A lamination for an electric motor rotor is disclosed. The lamination includes a disk defining a central aperture. Slots are defined in the disk. Each slot is configured to receive a magnet that at least partially defines a magnetic pole of the motor. The central aperture has a circumference comprising a plurality of scalloped portions. Each of the plurality of scalloped portions is intruded into the disk.

[0008] Also disclosed is a rotor for an electric motor. The rotor includes a stack of laminations comprising a plurality of laminations. Each lamination includes a disk defining a central aperture. A slot is defined in the disk. Each slot is configured to receive a magnet, the magnet at least partially defining a magnetic pole of the electric motor. The central aperture has a circumference comprising a plurality of scalloped portions. Each of the plurality of scalloped portions penetrates into the disk.

[0009] An electric motor is also disclosed, comprising a rotor press-fitted to a knurled section of a shaft. The rotor includes a stack of laminations having multiple laminations. Each lamination includes a disk defining a central hole. A slot is defined in the disk. Each slot is configured to receive a magnet, which at least partially defines a magnetic pole of the motor. The central hole has a circumference including multiple scalloped portions. Each scalloped portion penetrates into the disk. A stator is radially arranged outside the rotor. Attached Figure Description

[0010] The following description should not be construed as limiting in any way. Referring to the accompanying drawings, the same elements are numbered the same:

[0011] Figure 1 A schematic cross-sectional view of an electric motor including a laminated rotor stack is shown.

[0012] Figure 2 It shows Figure 1 A partial view of the rotor laminations on the shaft of the rotor stack;

[0013] Figure 3 It shows Figure 2 The individual scalloped features of the rotor laminations; and

[0014] Figure 4 The image shows the process before the rotor laminations are installed. Figures 1-3 A sectional side view of the axis in the middle. Detailed Implementation

[0015] Figure 1 A traction motor 100 is shown schematically, including a stator 110 arranged around a rotor 120. The rotor 120 consists of a plurality of laminations 122, each lamination 122 containing a plurality of slots. Figure 2 A partial view of an exemplary stack 122 is shown.

[0016] Reference Figure 1 and Figure 2 The laminations 122 are mounted to the shaft 130. Each lamination 122 includes a plurality of slots 210 for receiving magnets 212 (e.g., permanent magnets). The magnets 212 define the rotor poles of the traction motor 100.

[0017] In motor operating mode, the electromagnetic field generated by stator 110 interacts with the magnetic field of magnet 212, driving rotor 120 to rotate. Since rotor 120 is mechanically supported on and fixed to shaft 130, the rotation of rotor 120 drives the rotation of shaft 130, and this rotation is output to any system connected to shaft 130. The operation of traction motor 100 can be controlled using any control configuration based on existing principles.

[0018] A set of stacked sheets 122 is referred to as a stack 124. To hold the stack 124 on the shaft 130, the stack 124 has a central hole 220 that is pressed against the shaft 130. At the portion of the shaft 130 that holds the stack 124, the shaft 130 is knurled. Knurling consists of small protrusions or ridges extending outward from the outer radial direction of the shaft 130. Figure 4 An exemplary knurling pattern is shown, wherein a plurality of knurls 132 extend along the surface of the shaft 130 in the region where the stack of laminations 124 are press-fitted. The knurls 132 are staggered such that a plurality of knurls are present at any given axial position relative to axis A. The axial staggered arrangement of the knurls 132 ensures that all laminations 122 mounted on the knurled portion of the shaft are in contact with the plurality of knurls 132 to maintain the press fit. In some examples, the knurled section 131 of the shaft 130 is at least as long as the stack of laminations 124.

[0019] In alternative examples, knurling 132 may include other geometries (e.g., rhomboid or trapezoidal geometries). In some examples, all knurling 132 are identical. In other examples, knurling 132 may be formed using a combination of various geometries and sizes.

[0020] Laminates 122 are stacked together by welding, interlocking, or bonding to form a laminate stack 124. During the assembly of the traction motor 100, the laminate stack 124 is press-fitted onto the shaft 130. The laminate stack 124 may become damaged if the circumference of the center hole 220 is circular and the press-fit force is too high. Similarly, if incorrectly sized knurling 132 is used, the laminate stack 124 formed in the final assembly may become loose. To improve manufacturing efficiency, standardized knurling dies may be used in some examples to form the knurling. In this case, the possibility of inappropriate press-fit force increases.

[0021] To reduce the possibility of excessive pressure fit and force requirements, and to increase the range of standardized knurling dies that can be used for a given stack 124, each stack 122 includes a plurality of scallop-shaped features 230. The scallop-shaped features are circumferential portions of the central hole 220 that extend radially outward into the stack 122 and away from the center of the central hole 220.

[0022] In one example, the scallop-shaped feature is essentially elliptical (i.e., forming an arc that is part of an elliptical arc). Using an elliptical scallop-shaped portion as the scallop-shaped feature minimizes stress concentration on the inner circumference of the stack 124 while providing sufficient press fit to keep the stack 124 stationary relative to the axis 130. In alternative examples, the scallop-shaped feature may include other geometries (e.g., rhomboid or trapezoidal geometries). In some examples, all scallop-shaped features are identical in shape and size. In other examples, the scallop-shaped feature may be formed using a combination of various geometries and sizes.

[0023] Continue to refer to Figures 1-2 and Figure 4 , Figure 3 It shows Figure 2 A partially enlarged view of segment 201 is shown. Segment 201 comprises a single scalloped portion 230, and a depth 231 from the radially outermost portion of the knurling 132 to the scalloped portion 230 and a depth 233 from the shaft 130 to the scalloped portion 230 are shown. When considering manufacturing tolerances, each scalloped portion 230 is defined to have a sufficient length of depth 233 to ensure that depth 231 is greater than zero. Although shown in the example as an arcuate shape intruding into the circumference of the central bore 220, it should be understood that the scalloped portion 230 may also be implemented with alternative shapes. For example, in some alternative examples, the edge of each scalloped portion may be defined by a straight edge aligned with the radius of the shaft 130, and the scalloped portion will include the same arcuate shape as the circumference of the central bore 220 at the location of the scalloped portion 230.

[0024] The intrusion of the scalloped portion 230 allows the interference fit between the center hole 220 of the stack 124 and the individual knurling 132 of the shaft 130 to be the same as in a configuration without the scalloped portion 230, while minimizing the pressing force required to press the stack 124 into place. This, in turn, allows the knurling 132 to be formed on the shaft using standard knurling tools without the risk of improper press fit and increased force.

[0025] The scallop-shaped portion 230 serves to allow the stack 124 to skip or not contact a certain proportion of the knurling 132 at any given axial position on the shaft 130. In some examples, the scallop-shaped portion 230 is sized such that the amount of knurling 132 it skips is in the range of 55%-65% of the knurling 132 at a given axial position. In other examples, the scallop-shaped portion 230 is sized such that it skips approximately 58% of the knurling 132 at a given axial position.

[0026] In some examples, the number of scallop-shaped portions 230 on each stack 122 is an integer multiple of the number of magnetic poles of that stack 122. For example, if the stack 122 defines a four-pole motor, the number of scallop-shaped portions 230 on each stack can be four, eight, twelve, sixteen, twenty, or any other multiple of four. In some specific embodiments, the number of magnetic poles is equal to the number of scallop-shaped portions 230.

[0027] In some examples, each lamination 122 in the stack 124 includes the same number and size of scallop-shaped portions 230. In these examples, when the stack 124 is assembled, the scallop-shaped portions 230 of each lamination 122 are aligned with the scallop-shaped portions 230 of each other lamination in the stack 124, such that the scallop-shaped portions 230 of the entire stack 124 are located in the same radial position.

[0028] In one embodiment, a four-pole motor is constructed using a stack 124 of laminations 124 having eight scallop-shaped portions 230 on a central hole 220. The shaft 130 has a total of 224 knurlings 132 at each axial position. Each scallop-shaped portion 230 skips 14 knurlings 132 on the shaft 130, resulting in a total of 112 knurlings 132 being skipped at each axial position of the shaft 130.

[0029] The term "approximately" is intended to include the degree of error associated with a measurement of a specific quantity based on the equipment available at the time of submission of this application. For example, "approximately" may include a range of ±8% of a given value.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. Unless the context explicitly requires it, the singular forms “a” and “an” and “the” herein include the plural forms. It is further understood that the terms “comprising” and / or “including” as used herein indicate only the presence of the stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or combinations thereof.

[0031] While the present invention has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes can be made without departing from the scope of this disclosure, and equivalents can replace its elements. Furthermore, many modifications can be made without departing from the essential scope of this disclosure. Therefore, the present invention is not limited to the specific embodiments disclosed as the best mode for carrying out the invention, but rather the invention will include all embodiments falling within the scope of the claims.

Claims

1. A lamination for an electric motor rotor, the lamination comprising: A disc, with a central hole; Slots, defined in the disk, wherein each slot is configured to receive a magnet, the magnet at least partially defining the magnetic poles of the motor; and The central hole has a circumference comprising a plurality of scallop-shaped portions, each of which penetrates the disc.

2. The stacked sheets according to claim 1, wherein, The number of scallop-shaped parts is an integer multiple of the number of magnetic poles of the motor.

3. The stacked sheets according to claim 2, wherein, The number of scallop-shaped parts is equal to the number of magnetic poles of the motor.

4. The stacked sheets according to claim 1, wherein, One of the plurality of scallop-shaped parts is elliptical.

5. A rotor for an electric motor, the rotor comprising: A stack of stacked pieces, comprising multiple stacked pieces; and Each of the stacked plates includes: a disk defining a central hole, a slot defined in the disk, each slot being configured to receive a magnet that at least partially defines the magnetic poles of the motor, and the central hole having a circumference including a plurality of scallop-shaped portions, each of the plurality of scallop-shaped portions penetrating into the disk.

6. The rotor according to claim 5, wherein, Each of the plurality of stacked plates includes the same number of scallop-shaped portions as each of the other stacked plates.

7. The rotor according to claim 6, wherein, The scalloped portion of each stack of sheets is radially aligned with the scalloped portion of each other stack.

8. The rotor according to claim 5, wherein, The number of scallop-shaped portions in each stack is an integer multiple of the number of magnetic poles of the motor.

9. The rotor according to claim 8, wherein, The number of scallop-shaped portions in each stack is equal to the number of magnetic poles of the motor.

10. An electric motor, comprising: A rotor, press-fitted to a knurled section of a shaft, the rotor comprising a stack of laminations having multiple laminations, wherein each lamination includes a disk defining a central hole, a slot defined in the disk, each slot being configured to receive a magnet, the magnet at least partially defining a magnetic pole of the motor, and the central hole having a circumference comprising a plurality of scalloped portions, each of the plurality of scalloped portions penetrating into the disk; and The stator is arranged radially outside the rotor.

11. The motor according to claim 10, wherein, The knurled section of the shaft includes shaped knurling protruding from the outer surface of the shaft, and each of the scallop-shaped sections skips multiple knurlings at an axial position of the scallop-shaped section.

12. The motor according to claim 11, wherein, The number of knurlings skipped by each scallop-shaped section is 55%-65% of the total number of knurlings at the axial position of the scallop-shaped section.

13. The motor according to claim 11, wherein, The number of knurlings skipped by each scallop-shaped section is approximately 58% of the total number of knurlings at the axial position of the scallop-shaped section.

14. The motor according to claim 11, wherein, The knurling is evenly distributed around the axis in the knurling section, such that the number of knurlings at each axial position in the knurling section is the same.

15. The motor according to claim 11, wherein, The knurled section of the shaft is at least as long as the total length of the plurality of stacked sheets.

16. The motor according to claim 10, wherein, Each of the plurality of scallop-shaped parts is elliptical.

17. The motor according to claim 10, wherein, Each of the plurality of stacked pieces includes the same number of scallop-shaped portions as each of the other stacked pieces.

18. The motor according to claim 17, wherein, The scalloped portion of each stack of sheets is radially aligned with the scalloped portion of each other stack.

19. The motor according to claim 10, wherein, The number of scallop-shaped portions in each stack is an integer multiple of the number of magnetic poles of the motor.

20. The motor according to claim 19, wherein, The number of scallop-shaped portions in each stack is equal to the number of magnetic poles of the motor.

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