Rotor structure and electric machine

Abstract

The utility model relates to a rotor structure for motor has rotor core, the rotor core includes first punching sheet and second punching sheet, first punching sheet and second punching sheet have a plurality of magnet slot for arranging magnet respectively, the magnet slot is arranged in V shape and has bottom connecting section in V shape bottom, wherein, first winding hole pair is equipped with in the radial both sides of bottom connecting section of first punching sheet, a plurality of first winding hole pair is wound by carbon fiber, forms first core section, the second core section that constitutes by second punching sheet has the slot that leaves in the position that corresponds to first winding hole pair in axial direction, the slot that leaves is used to accommodate the protruding section that carbon fiber protrudes first core section axial end surface, thereby uses carbon fiber to replace the magnetic bridge to bear centrifugal force at stress concentration place, therefore, the performance of motor has been improved.

Description

Technical Field

[0001] This utility model relates to the field of motor technology, and in particular to a motor rotor structure using carbon fiber winding, aiming to solve the problems related to the magnetic bridge structure faced by electric vehicle drive motors in increasing speed, thereby improving the overall performance of the motor. Background Technology

[0002] In the electric vehicle field, to reduce costs and increase power density, the rotational speed of drive motors is constantly increasing. Conventional laminations in motors (as shown in patent CN202010711374) suffer from stress concentration issues, with stress primarily concentrated at the magnetic bridge. From an electromagnetic performance perspective, a narrower magnetic bridge is better, as it reduces the passage of magnetic lines of force and improves electromagnetic performance; however, from a mechanical performance perspective, a wider magnetic bridge is better, as it increases the cross-sectional area to ensure strength. As motor speeds increase, the magnetic bridge must be widened to meet mechanical performance requirements, but this leads to a decrease in motor performance, creating a performance trade-off.

[0003] To address this issue, different manufacturers have proposed different solutions. Tesla's patent (WO 2021 / 225902 A1) uses carbon fiber to wrap the outer circumference of the motor rotor. The carbon fiber is pre-tensioned, which can apply inward pressure to the rotor core throughout the product's lifespan, offsetting some of the centrifugal force during rotor rotation. Furthermore, its elastic modulus is higher than that of silicon steel sheets, limiting the elastic deformation of silicon steel sheets at high speeds and reducing the stress on the silicon steel sheets. Simultaneously, eliminating the axial magnetic bridge alleviates the leakage magnetic problem and improves electromagnetic performance. Hitachi's patent (US2020266677) is similar to Tesla's, also eliminating the magnetic bridge and wrapping carbon fiber around the outer circumference of the rotor core, but first using adhesive materials to bond the dispersed parts.

[0004] However, these patents involving carbon fiber surface coating also have problems. To ensure normal motor rotation, a certain gap is required between the stator's inner diameter and the rotor's outer diameter. Furthermore, due to the mechanical properties of carbon fiber, a certain air gap must be maintained when it's wrapped around the rotor's outer diameter. This means the actual magnetic gap between the stator and rotor is the sum of the mechanical gap and the carbon fiber layer thickness. Compared to conventional structures, both Tesla's and Bosch's patented structures increase the magnetic gap between the stator and rotor, significantly degrading motor performance. Simultaneously, conventional structures are limited by the properties of silicon steel sheets, making it difficult to solve the strength problem at the magnetic bridge. Utility Model Content

[0005] Therefore, the technical problem to be solved by this utility model is to provide a novel rotor structure that can overcome the problems in the prior art, and eliminate the magnetic isolation bridge or greatly reduce the width of the magnetic isolation bridge while ensuring the strength of the rotor structure.

[0006] The aforementioned technical problem is solved by an improved motor rotor structure. In the rotor structure according to this invention, the rotor core is composed of a first lamination and a second lamination. Each of the first and second laminations has multiple magnet slots arranged in a V-shape, and the magnet slots have a bottom connecting section at the bottom of the V-shape. A pair of first winding holes is provided on both radially sides of the bottom connecting section of the first lamination. Multiple first laminations are wound with carbon fiber passing through the first winding holes to form a first core segment. The second core segment, composed of the second lamination, has a slot at a position corresponding axially to the first winding hole pair, for accommodating the protruding section of the carbon fiber winding the first core segment that protrudes from the axial end face of the first core segment. By providing winding holes at the bottom connecting section and winding with carbon fiber, the magnetic isolation bridge is eliminated or its width is greatly reduced. The carbon fiber passes through the winding holes and is wound around the original magnetic isolation bridge of the lamination to replace the original load-bearing function of the magnetic isolation bridge structure, thereby maintaining the strength of the lamination with carbon fiber and effectively solving the strength problem that may be caused by changes in the magnetic isolation bridge structure. The carbon fiber winding and slotted design ensures proper axial assembly of the first and second core sections, resulting in a more compact rotor structure and improved motor performance, such as increased torque output and reduced losses. Compared to traditional lamination structures, this design eliminates the magnetic bridge structure, reducing rotor leakage flux. Therefore, electromagnetic performance is improved at the same speed. Furthermore, because carbon fiber is used instead of silicon steel sheets to bear centrifugal force at stress concentration points, the maximum motor speed can also be increased.

[0007] According to a preferred embodiment of this invention, the second lamination has a second pair of winding holes. Multiple second laminations can be wound with carbon fiber through the second pair of winding holes to form a second core segment, and the second pair of winding holes does not overlap with the first pair of winding holes in the axial direction. This structural design ensures that the first and second core segments can be arranged alternately in the axial direction. The alternating arrangement of the core segments helps to stabilize the motor performance under different operating conditions. For example, at high speeds, it can better balance the interaction between centrifugal force and electromagnetic force, reduce vibration and energy loss, improve the operating efficiency and reliability of the motor, and make the output performance of the motor more stable and uniform. Preferably, the second lamination also has a third pair of winding holes, which are arranged on both sides of the empty slot. The presence of the third pair of winding holes further optimizes the stress distribution. During motor operation, especially at high speeds, the rotor bears complex stresses. The third pair of winding holes works synergistically with the second pair of winding holes, making the winding method of carbon fiber on the second lamination more scientific and reasonable, effectively dispersing stress, avoiding stress concentration in local areas, thereby enhancing the strength and durability of the rotor structure, extending the service life of the motor, and reducing maintenance costs. Furthermore, it can be considered that the magnet groove of the first lamination axially accommodates the second and third winding hole pairs of the second lamination, thereby allowing the protruding sections of the second and third winding hole pairs to be accommodated by the magnet groove of the first core segment. This correspondence ensures the accuracy and coordination of the first and second core segments during assembly.

[0008] According to a preferred embodiment of this utility model, the first and second core segments are arranged alternately in the axial direction. This alternating arrangement creates a complementary and balanced structure for the rotor cores. During motor operation, it can evenly withstand various forces, such as centrifugal force and electromagnetic force, reducing vibration and imbalance caused by structural inhomogeneity. Further preferably, the thickness of the second core segment is between two and three times the axial width of the protruding section of the carbon fiber wound around the first core segment. The first and second core segments are staggered and avoid each other at the positions where the carbon fiber is wound. Due to the axial space of the carbon fiber, the thickness of each core segment cannot be too low, otherwise there will not be enough space for avoidance. However, since the force and deformation at the winding point will be unevenly distributed axially after the carbon fiber is wound, the thickness of each core segment should not be too high either. Additionally, if the motor has skewed poles, the first core segment is at both ends of the rotor core's axial direction. This design provides the necessary space and structural support for the motor under skewed pole operation conditions. If the motor does not have skewed poles, the first and second core segments are at the two ends of the rotor core's axial direction, respectively. In skew-free operation, this structural layout provides a more balanced structure and performance at both ends of the rotor. The distribution of different core segments at both ends allows for the comprehensive utilization of their respective characteristics, which is beneficial for optimizing motor performance under normal operating conditions, such as improving efficiency and reducing losses. Additionally, the first and second core segments can be fixed using self-adhesive bonding. Self-adhesive bonding simplifies the rotor core fixing process, reduces additional fixing components, and lowers manufacturing complexity and cost.

[0009] Furthermore, the technical problem to be solved by this utility model can also be solved by an electric motor having a rotor structure including the above-mentioned features. Attached Figure Description

[0010] The preferred embodiments of this utility model are further illustrated below with reference to the accompanying drawings. The drawings are as follows: Figure 1 A top view and a partial enlarged view of the first lamination designed according to this utility model are shown; Figure 2 A top view and a partial enlarged view of the second lamination designed according to this utility model are shown; Figure 3 A partial cross-sectional view of the rotor core designed according to this utility model is shown; Figure 4 A partial perspective view of the rotor core designed according to this utility model is shown.

[0011] Unless otherwise stated, the "axial", "radial" and "circumferential" directions mentioned in this utility model are all relative to the rotation axis of the rotor. Detailed Implementation

[0012] This utility model relates to a rotor structure for an electric motor, the rotor having a rotor core formed by stacking different laminations. In an embodiment of this utility model, the rotor core includes a first lamination 1 (such as...). Figure 1 (as shown) and second lamination 2 (as shown) Figure 2 (As shown). Figure 1 The diagram shows a top view and a partial enlarged view of the first lamination 1. Multiple magnet slots 11 for accommodating magnets are arranged on the circumference of the first lamination 1, each slot 11 being arranged in a V-shape. As shown, a bottom connecting section 12 is provided at the bottom of the V-shape of the magnet slot. Here, the width of the original magnetic isolation bridge is reduced or eliminated by the bottom connecting section. To maintain the strength of the lamination, a pair of winding holes 13 are provided on both radial sides of the bottom connecting section 12. Carbon fiber 3 is wound through the winding holes 13 to the first core segment 100 composed of multiple first laminations 1.

[0013] Figure 2 The diagram shows a top view and a partial enlarged view of the second lamination 2. The second lamination 2 has a magnet groove 21 that coincides axially with that of the first lamination 1, and this magnet groove also has a bottom connecting section 22. The second lamination 2 has a recessed groove 23 at an axial position corresponding to the first winding hole pair 13, for accommodating the protruding section 31 of the carbon fiber 3 wound around the first winding hole pair 13. Figure 2 As shown, the second lamination 2 also has a second winding hole pair 24. Multiple second laminations 2 are wound together by carbon fiber 3 passing through these second winding hole pairs 24 to form a second core segment 200. These second winding hole pairs 24 do not overlap with the first winding hole pair 13 in the axial direction, ensuring that the first core segment 100 and the second core segment 200 can be alternately arranged in the axial direction. Furthermore, the second lamination 2 also has a third winding hole pair 25, which is located on both sides of the slot 23, separate from the second winding hole pairs 24, to balance stress distribution.

[0014] Figure 3This is a partial cross-sectional view of the rotor core. The rotor core is composed of a first core segment 100 and a second core segment 200 arranged alternately in the axial direction. As mentioned earlier, multiple first laminations 1 are formed by winding carbon fiber 3 around first winding holes 13 to form the first core segment 100. Since the carbon fiber 3 surrounds the first core segment 100, protruding segments 31 are formed at both ends of the first core segment 100 in the axial direction. The second lamination 2 has a slot 23 at a position corresponding to the first winding hole pair 13 in the axial direction to accommodate the protruding segments 31. Therefore, the first core segment 100 and the second core segment 200 are staggered and avoid each other at the positions where the carbon fiber is wound. Furthermore, due to the axial space of the carbon fiber, the thickness of each core segment cannot be too low, otherwise there will not be enough clearance space. That is, the thickness d of the second core segment is set according to the axial thickness of the protruding segment 31. For example, the thickness d of the second core segment is greater than the axial thickness of the two protruding segments 31, so that sufficient clearance space can be formed. Furthermore, after winding carbon fiber 3, the stress and deformation at the winding point will be unevenly distributed axially. Therefore, each stack of iron core should not be too thick.

[0015] Figure 4 This is a partial three-dimensional schematic diagram of the rotor core section. For example... Figure 2 As shown, the second lamination 2 has a second winding hole pair 24 and a third winding hole pair 25. Multiple second laminations 2 are wound with carbon fiber 3 through the second winding hole pair 24 and the third winding hole pair 25 respectively, forming a second core segment 200. The second winding hole pair 24 and the third winding hole pair 25 do not overlap with the first winding hole pair 13 in the axial direction, and the second winding hole pair 24 and the third winding hole pair 25 are located on opposite sides of the first winding hole pair 13 in the axial direction. The second winding hole pair 24 and the third winding hole pair 25 are positioned within the magnet slot 11, thus creating a clearance, allowing the first core segment 100 and the second core segment 200 to be arranged alternately in the axial direction. If the motor has skewed poles, the axial ends of the rotor core are the first core segment 100; if the motor does not have skewed poles, the axial ends are the first core segment 100 and the second core segment 200, respectively. The first core segment 100 and the second core segment 200 are fixed by self-adhesion, simplifying the manufacturing process and ensuring structural stability.

[0016] While possible embodiments have been described exemplarily in the foregoing description, it should be understood that numerous variations of the embodiments exist through combinations of all known and readily conceived technical features and implementation methods. Furthermore, it should be understood that the exemplary embodiments are merely examples and do not in any way limit the scope, application, or construction of this invention. The foregoing description is more intended to provide those skilled in the art with technical guidance for transforming at least one exemplary embodiment, wherein various changes can be made, particularly regarding the function and structure of the components, without departing from the scope of the claims.

[0017] List of reference numerals 1. First film processing 2 Second film processing 3 carbon fiber 11 Magnet slot of the first lamination 12 Bottom connecting section of the first lamination 13 First winding hole pair 21. Magnet slot of the second lamination 22 Bottom connecting section of the second lamination 23 Empty slots 24 Second winding hole pair 25 Third winding hole pair 100 First Iron Core Section 200 Second Iron Core Section 31 protruding segments d. Thickness of the second core section

Claims

1. A rotor structure for an electric motor, having a rotor core, the rotor core comprising a first lamination (1) and a second lamination (2), the first lamination (1) and the second lamination (2) each having a plurality of magnet slots (11, 21) for accommodating magnets, the magnet slots (11, 21) being arranged in a V-shape and having bottom connecting sections (12, 22) at the bottom of the V-shape, wherein, A first winding hole pair (13) is provided on both radial sides of the bottom connecting section (12) of the first lamination (1). Multiple first laminations (1) are wound with carbon fiber (3) through the first winding hole pair (13) to form a first iron core section (100). The second iron core section (200) composed of the second lamination (2) has a slot (23) in the axial direction corresponding to the first winding hole pair (13). The slot (23) is used to accommodate the protruding section (31) of the carbon fiber (3) protruding from the axial end face of the first iron core section (100).

2. The rotor structure according to claim 1, characterized in that, The second lamination (2) has a second winding hole pair (24), and a plurality of the second laminations (2) are wound with carbon fiber (3) through the second winding hole pair (24) to form the second core segment (200), wherein the second winding hole pair (24) does not overlap with the first winding hole pair (13) in the axial direction.

3. The rotor structure according to claim 2, characterized in that, The second lamination (2) has a third winding hole pair (25), and the second winding hole pair (24) and the third winding hole pair (25) are located on both sides of the empty slot (23).

4. The rotor structure according to claim 3, characterized in that, The magnet groove (11) of the first lamination (1) axially accommodates the second winding hole pair (24) and the third winding hole pair (25).

5. The rotor structure according to any one of claims 1 to 4, characterized in that, The first core segment (100) and the second core segment (200) are arranged alternately in the axial direction.

6. The rotor structure according to claim 5, characterized in that, The thickness (d) of the second core segment (200) is between 2 and 3 times the axial width of the protruding segment (31).

7. The rotor structure according to claim 5, characterized in that, If the motor has skewed poles, then the two axial ends of the rotor core are the first core segment (100).

8. The rotor structure according to claim 5, characterized in that, If the motor has no skewed poles, then the two axial ends of the rotor core are the first core segment (100) and the second core segment (200), respectively.

9. The rotor structure according to claim 5, characterized in that, The laminations of the first core segment (100) and the laminations of the second core segment (200) are fixed by adhesive bonding.

10. An electric motor, characterized in that, The motor has the rotor structure as described in any one of claims 1 to 9.

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