Motor rotor and motor

Abstract

The invention relates to the technical field of motor rotors, and provides a motor rotor and a motor, the motor rotor comprises an iron core, the iron core can be divided into a plurality of fan-shaped sections with the same size, and each fan-shaped section is provided with two first mounting grooves and two second mounting grooves; the two second mounting grooves and the two third mounting grooves are located on the inner sides of the two first mounting grooves in the radial direction, the two second mounting grooves are located between the two third mounting grooves, and the motor rotor further comprises first magnetic steel, second magnetic steel and third magnetic steel. Compared with a structure that four pieces of magnetic steel are combined in pairs, finer magnetic field partition regulation and control can be achieved through subdivision arrangement of the six pieces of magnetic steel, and the problems that magnetic field coverage is uneven and harmonic suppression is insufficient when the four pieces of magnetic steel are arranged are solved. Two pieces of first magnetic steel form a V-shaped structure, four pieces of magnetic steel form a C-shaped structure, and the cooperation of the two pieces of first magnetic steel and the C-shaped structure is better than the single combination effect of the four pieces of magnetic steel. Six pieces of magnetic steel are symmetrically distributed more reasonably, stress dispersion of the rotor punching sheet is more uniform, electromagnetic performance deterioration caused by thickening of a magnetic bridge is avoided, and the rotor punching sheet can better adapt to the ultra-high-speed working condition.

Description

Technical Field

[0001] This disclosure relates to the field of motor rotor technology, and more specifically, to a motor rotor and a motor. Background Technology

[0002] In ultra-high-speed motors, the rotor's rotational energy increases quadratically with the rotational speed, placing extremely high demands on the rotor's structural strength. To ensure the rotor's structural reliability under peak speed and overspeed conditions, current technologies require increasing the thickness of the magnetic bridge to enhance its mechanical strength and prevent breakage during high-speed rotation. However, excessive magnetic bridge thickness can easily lead to magnetic circuit saturation and increased leakage flux, significantly reducing the motor's electromagnetic performance. Especially under high-speed conditions, this can exacerbate torque fluctuations and increase losses, making it impossible to simultaneously meet the dual requirements of ultra-high-speed motors for both structural strength and electromagnetic performance. Summary of the Invention

[0003] The purpose of this disclosure is to provide an electric motor rotor and an electric motor that at least partially solves the problems existing in the related art.

[0004] To achieve the above objectives, this disclosure provides an electric motor rotor, including an iron core, wherein the iron core can be divided into multiple equally sized sector segments along the circumference, and each sector segment has: Two first mounting slots, the two first mounting slots forming a V-shaped profile with the opening facing radially outward; and The two second mounting slots and two third mounting slots are located radially inside the two first mounting slots, with the two second mounting slots positioned between the two third mounting slots to collectively form a C-shaped profile with the opening facing outwards along the radial direction. The motor rotor further includes a first magnet installed in the first mounting slot, a second magnet installed in the second mounting slot, and a third magnet installed in the third mounting slot.

[0005] According to some possible embodiments, the portion of the sector segment located between the two first mounting slots is a first magnetic bridge, the portion located between the two second mounting slots is a second magnetic bridge, and the portion located between adjacent second mounting slots and the third mounting slot is a third magnetic bridge. The minimum thickness of the first magnetic bridge, the third magnetic bridge, and the second magnetic bridge decreases sequentially.

[0006] According to some possible embodiments, the minimum thickness ratio of the first magnetic bridge, the third magnetic bridge, and the second magnetic bridge is 1.2X:1:0.8Y, where the values ​​of X and Y are 0.95~1.05.

[0007] According to some possible embodiments, the second magnet is smaller in the circumferential direction than the third magnet.

[0008] According to some possible embodiments, the obtuse angle A7 formed between the two second magnets in the circumferential extension direction along the radial outward direction satisfies greater than or equal to 175°.

[0009] According to some possible embodiments, the portion of the sector segment located between the two second mounting slots is a second magnetic bridge, and the second magnetic bridge is symmetrically distributed about the centerline of the sector segment.

[0010] According to some possible embodiments, the portion of the sector segment located between adjacent second and third mounting slots is a third magnetic bridge. The third magnetic bridge has a first root and a second root on the side near the second mounting slot, and a third root and a fourth root on the side near the third mounting slot. The first root is located radially outward of the second root, and the third root is located radially outward of the fourth root. Wherein, the arc radius R3 of the first root is greater than the arc radius R3a of the third root, and the arc radius R2 of the second root is less than the arc radius R1 of the fourth root.

[0011] According to some possible embodiments, R3a, R3, R1, and R2 are each greater than or equal to 0.3 mm.

[0012] According to some possible embodiments, the portion of the sector segment located between the two second mounting slots is a second magnetic bridge, and the portion located between adjacent second mounting slots and the third mounting slot is a third magnetic bridge. The four root portions of the second magnetic bridge each have multiple arc segments; and / or, the four root portions of the third magnetic bridge each have multiple arc segments.

[0013] According to some possible embodiments, the second magnetic bridge and the third magnetic bridge each have at least two arc segments at their two root portions on the radially outer side; and / or, the second magnetic bridge and the third magnetic bridge each have at least three arc segments at their two root portions on the radially inner side.

[0014] According to some possible embodiments, the minimum thickness position of the second magnetic bridge and the root of the second magnetic bridge near the inner side in the radial direction have two symmetrical transition arcs, the transition arcs extending to the minimum thickness position, and the radius R5 of the transition arcs satisfying: R5≥1.5mm.

[0015] According to some possible embodiments, two sets of staggered ends of the first magnet on two sides arranged in the circumferential direction respectively abut against the first wall of the first mounting groove, and two sets of staggered ends are respectively spaced apart from the first wall; and / or, The second magnet has two sets of staggered ends on two sides arranged in the circumferential direction, which respectively abut against the second wall of the second mounting groove; and another set of staggered ends are spaced apart from the second wall of the groove; and / or, The two staggered ends of the third magnet on the two sides arranged in the circumferential direction respectively abut against the third wall of the third mounting groove, and the two staggered ends of the other set are spaced apart from the third wall.

[0016] According to some possible embodiments, the motor rotor also includes a carbon fiber layer sleeved around the outer periphery of the iron core, a mating hole in the middle portion of the iron core, and a rotating shaft that is shaped and inserted into the mating hole. The inner contour of the mating hole is non-circular to allow the shaft and the iron core to transmit torque.

[0017] According to some possible embodiments, the portion of the sector segment located between the two first mounting slots is a first magnetic bridge, the portion located between the two second mounting slots is a second magnetic bridge, and the portion located between an adjacent second mounting slot and a third mounting slot is a third magnetic bridge. The included angle A4 between the centerlines of the two third magnetic bridges satisfies:

[0018] Wherein, A1 is the angle of the sector segment in the circumferential direction, A2 is the obtuse angle formed between the two third magnets in the circumferential extension direction along the radial outward direction, A3 is the obtuse angle formed between the two first magnets in the circumferential extension direction along the radial outward direction, L1 is the length of the first magnet, L2 is the width of the first magnet, L3 is the length of the third magnet, L4 is the width of the third magnet, L5 is the length of the second magnet, L6 is the width of the second magnet, H0 is the distance between the center point of the minimum thickness position of the first magnetic bridge and the center point of the minimum thickness position of the second magnetic bridge, R6 is the outer radius of the iron core, K1 is a constant with a value range of 0.05-0.2, and K2 is a constant with a value range of 0.3-0.8.

[0019] According to some possible embodiments, the portion of the first mounting groove between the radially outer corner and the outer edge of the fan-shaped segment is a fourth magnetic bridge, and the portion of the third mounting groove between the radially outer corner and the outer edge of the fan-shaped segment is a fifth magnetic bridge, wherein the minimum thickness H2 of the second magnetic bridge satisfies:

[0020] Wherein, H4 is the minimum thickness of the third magnetic bridge, H3 is the maximum thickness of the third magnetic bridge, H5 is the minimum thickness of the first magnetic bridge, H6 is the minimum thickness of the fourth magnetic bridge, H7 is the minimum thickness of the fifth magnetic bridge, H1 is the maximum thickness of the second magnetic bridge, K3 is a constant with a value range of 0.5-1.2, K4 is a constant with a value range of 0.3-0.9, and K5 is a constant with a value range of 0.1-0.4.

[0021] According to some possible embodiments, the second magnetic bridge has a fifth root at a position close to the inner side of the second magnet in the radial direction, and the position of the second magnet corresponding to the fifth root has a rounded corner, the maximum distance R4 from the center of the rounded corner to the fifth root satisfies:

[0022] Wherein, the minimum thickness position of the second magnetic bridge and the root of the second magnetic bridge located radially outward have two symmetrical straight line segments, the straight line segments extending to the minimum thickness position, the included angle between the two straight line segments is A5, K6 is a constant with a value range of 0.8-1.5, and K7 is a constant with a value range of 0.9-1.4.

[0023] According to a second aspect of this disclosure, an electric motor is provided, including the motor rotor described above.

[0024] Through the above technical solution, this solution specifically addresses the contradiction between the thickness of the magnetic bridge and its electromagnetic performance in ultra-high-speed motors. Based on a precise layout of two first magnets forming a V-shape and four magnets (two second magnets + two third magnets) forming a C-shape, compared to the common four-magnet layout per cycle, it achieves a dual upgrade in mechanical strength and electromagnetic performance, offering significant advantages. Compared to the structure of four magnets combined in pairs, the subdivided arrangement of six magnets allows for more precise magnetic field zoning and control, avoiding the problems of uneven magnetic field coverage and insufficient harmonic suppression in the four-magnet layout. The V-shaped structure formed by the two first magnets precisely improves the rotor saliency and strengthens the reluctance torque, while the C-shaped structure composed of four magnets expands the magnetic field coverage and optimizes the sinusoidal nature of the air gap magnetic field. The synergy of these two elements is superior to the effect of a single combination of four magnets. Meanwhile, the symmetrical distribution of the six magnets is more reasonable, and the stress of the rotor laminations is more evenly distributed. Compared with the four-magnet layout, the magnetic bridge thickness requirement can be further reduced, which avoids the deterioration of electromagnetic performance caused by the thickening of the magnetic bridge, and can better adapt to ultra-high speed conditions, taking into account power density, operating efficiency and structural reliability.

[0025] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0026] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of an iron core exemplarily shown according to this disclosure; Figure 2 yes Figure 1 The front view of the iron core is shown in the image; Figure 3 yes Figure 1 The image shows a front view of a sector segment of the iron core. Figure 4 yes Figure 1 The image shows a front view of a sector segment of the iron core. Figure 5 yes Figure 1 The image shows a front view of a sector segment of the iron core. Figure 6 This is a schematic diagram illustrating a partial fit between a mating hole and a rotating shaft, as exemplarily shown in this disclosure. Figure 7 This is a schematic diagram of a partial fit between a mating hole and a rotating shaft, exemplarily shown according to this disclosure. Figure 8 yes Figure 4 A partial enlarged view of the third magnetic bridge in the sector segment shown in the image; Figure 9 yes Figure 1 The image shows a front view of a sector segment of the iron core. Figure 10 yes Figure 1 The image shows a front view of a sector segment of the iron core. Figure 11 yes Figure 4 A partial enlarged view of the first and second magnetic bridges in the sector segment shown in the figure; Figure 12 yes Figure 4 A partial enlarged view of the second magnetic bridge in the sector segment shown in the image; Figure 13 yes Figure 4 A partial enlarged view of the third magnetic bridge in the sector segment shown in the image; Figure 14 yes Figure 4 A partial enlarged view of the second magnetic bridge in the sector segment shown in the image; Figure 15 yes Figure 4 A partial enlarged view of the second magnetic bridge in the sector segment shown in the image; Figure 16 yes Figure 1 The image shows a front view of a sector segment of the iron core. Figure 17 yes Figure 1 The image shows a front view of a sector segment of the iron core. Figure 18 yes Figure 1 The image shows a front view of a sector segment of the iron core. Figure 19 This disclosure provides a stress gradient cloud map of the core of an electric motor rotor at peak speed; Figure 20 This is a stress gradient cloud map of the iron core of an electric motor rotor under overspeed conditions, provided in this disclosure; Figure 21 Figure 20 Enlarged view of strain contour lines at the second magnetic bridge section; Figure 22 yes Figure 21 Enlarged view of strain contour lines at the minimum thickness; Figure 23 This disclosure provides a radial displacement deformation cloud map of the iron core of an electric motor rotor at peak speed; Figure 24 This disclosure provides an equivalent stress distribution cloud map of a local region of the carbon fiber layer of the iron core of an electric motor rotor at peak speed; Figure 25 This is a curve showing the stress level of the iron core of an electric motor rotor as a function of rotational speed, as provided in this disclosure.

[0027] Explanation of reference numerals in the attached figures 1-Iron core; 101-Sector segment; 102-Matching hole; 21-First mounting slot; 22-Second mounting slot; 23-Third mounting slot; 31-First magnet; 32-Second magnet; 321-Rounded corner; 33-Third magnet; 41-First magnetic bridge; 42-Second magnetic bridge; 421-Fifth root; 43-Third magnetic bridge; 431-First root; 432-Second root; 433-Third root; 434-Fourth root; 44-Fourth magnetic bridge; 45-Fifth magnetic bridge; 51-Carbon fiber layer; 52-Shaft. Detailed Implementation

[0028] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0029] In this disclosure, unless otherwise stated, the terms "radial" and "circumferential" are used in relation to the electronic rotor itself; that is, "radial" refers to the diameter direction of the motor rotor, and "circumferential" refers to the circumferential direction of the motor rotor. The directional terms used, such as "inner" and "outer," can refer to the structure of the corresponding component itself, or they can be defined based on the actual direction in which the component is used. For example, "located on the inner side" of the two first mounting slots means, radially, on the side of the first mounting slot closest to the motor rotor's axis; the two second mounting slots are located between the two third mounting slots to jointly form a C-shaped profile with the opening facing "outer" radially, where "outer" refers to the side furthest from the motor rotor's axis.

[0030] In addition, the terms "first," "second," etc., used in this disclosure are for distinguishing one element from another and do not have sequential or importance. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0031] Reference Figures 1-3 This disclosure provides a motor rotor, including an iron core 1. The iron core 1 can be divided into multiple sector segments 101 of equal size along the circumference, that is, each sector segment 101 has the same circumferential angle in the circumferential direction. The number of sector segments 101 can be six, eight, etc. The iron core 1 can be formed by stacking (welding or riveting) multiple laminations of the same structure, and the laminations are the basic structural units constituting the iron core 1. Each sector segment 101 has two first mounting slots 21 and two second mounting slots 22 and two third mounting slots 23 located radially inside the two first mounting slots 21. The two first mounting slots 21 form a V-shaped profile with the opening facing outwards radially, that is, the two first mounting slots 21 are at an angle to each other. Two second mounting slots 22 are located between two third mounting slots 23 to jointly form a C-shaped profile with the opening facing radially outward. That is, adjacent second mounting slots 22 and third mounting slots 23 are at an angle to each other rather than parallel (if adjacent second mounting slots 22 and third mounting slots 23 are parallel to each other, then the two second mounting slots 22 and the two third mounting slots 23 together form a V-shaped profile with the opening facing radially outward). The motor rotor also includes a first magnet 31 installed in the first mounting slot 21, a second magnet 32 ​​installed in the second mounting slot 22, and a third magnet 33 installed in the third mounting slot 23.

[0032] By employing the aforementioned technical solution, the contradiction between the thickness of the magnetic bridge and electromagnetic performance in ultra-high-speed motors is specifically addressed. A precise layout, consisting of two first magnets (31) forming a V-shape and four magnets (two second magnets (32) + two third magnets (33)) forming a C-shape, achieves a dual upgrade in mechanical strength and electromagnetic performance compared to the common four-magnet layout per cycle, demonstrating significant advantages. Compared to the structure of four magnets combined in pairs, the subdivided arrangement of six magnets allows for more precise magnetic field zoning and control, avoiding the problems of uneven magnetic field coverage and insufficient harmonic suppression in a four-magnet layout. The V-shape structure formed by the two first magnets (31) precisely improves the rotor saliency and enhances reluctance torque, while the C-shape structure of the four magnets expands magnetic field coverage and optimizes the sinusoidal nature of the air gap magnetic field. The synergy of these two elements surpasses the effect of a single combination of four magnets. Meanwhile, the symmetrical distribution of the six magnets is more reasonable, and the stress of the rotor laminations is more evenly distributed. Compared with the four-magnet layout, the magnetic bridge thickness requirement can be further reduced, which avoids the deterioration of electromagnetic performance caused by the thickening of the magnetic bridge, and can better adapt to ultra-high speed conditions, taking into account power density, operating efficiency and structural reliability.

[0033] Specifically, this disclosure has at least the following advantages: (1) Lower torque pulsation: The air gap magnetic field is more sinusoidal, the motor magnetomotive force waveform is smoother, and the harmonic content is relatively lower, which results in lower motor torque pulsation and better NVH. (2) Higher torque density: The motor fundamental winding coefficient is higher and the air gap magnetic field is more sinusoidal. Under the same volume and amount of magnets, the output torque density and power density are higher. (3) Lower harmonic losses: Lower iron loss and magnet loss at high speeds, resulting in better efficiency and temperature rise control; (4) More flexible mechanical design: With more magnetic bridges, the stress and leakage magnetic design is more flexible, and it is easier to achieve a balance between high-speed strength and electromagnetic performance; Structurally, this disclosure reduces the amount of magnets used (increased quantity but reduced overall mass), resulting in lower cost, easier achievement of different motor performance characteristics, and easier adjustment of performance parameters. In terms of strength, the core 1 exhibits more uniform overall deformation, lower stress levels, and longer fatigue life.

[0034] Reference Figure 4In the embodiments of this disclosure, each sector segment 101 has multiple magnetic bridges. The portion of the sector segment 101 located between two first mounting slots 21 is the first magnetic bridge 41, the portion located between two second mounting slots 22 is the second magnetic bridge 42, and the portion located between adjacent second mounting slots 22 and third mounting slots 23 is the third magnetic bridge 43. The portion of the first mounting slot 21 located radially towards the outer edge and the outer edge of the sector segment 101 is the fourth magnetic bridge 44, and the portion of the third mounting slot 23 located radially towards the outer edge and the outer edge of the sector segment 101 is the fifth magnetic bridge 45. It should be noted that the two edges of the magnetic bridge are either the inner edge of the corresponding mounting slot or the outer edge of the sector segment 101. The first magnetic bridge 41, second magnetic bridge 42, and third magnetic bridge 43 each have four roots. The roots refer to the connection transition area between the magnetic bridge and the lamination body (pole / yoke), which is the critical part where stress concentration is most severe, directly determining the high-speed strength and fatigue life of the motor rotor. Since the roots are well known to those skilled in the art, they will not be described in detail here.

[0035] In this disclosure, the minimum thickness of the first magnetic bridge 41, the third magnetic bridge 43, and the second magnetic bridge 42 decreases sequentially; that is, the minimum thickness of the first magnetic bridge 41 is greater than the minimum thickness of the third magnetic bridge 43, and the minimum thickness of the third magnetic bridge 43 is greater than the minimum thickness of the second magnetic bridge 42. Here, minimum thickness refers to the minimum distance between the two edges of the adjacent mounting groove of the magnetic bridge. This design has at least the following advantages: 1. Ensure that the second magnetic bridge 42 and the third magnetic bridge 43 near the inside have a thinner thickness in order to control the leakage flux of the magnetic bridge, especially the central magnetic bridge (second magnetic bridge 42), and improve the peak performance of the motor. 2. In terms of electromagnetic performance: The first magnetic bridge 41 is the thickest to prevent premature magnetic saturation and ensure effective transmission of the main magnetic flux; the third magnetic bridge 43, with an appropriate thickness, can undertake part of the current shunting or auxiliary magnetic conduction and control the magnetic flux of this path; the second magnetic bridge 42, with its thinner thickness, can increase the magnetic reluctance at this point, which helps to reduce inter-pole leakage magnetic flux and improve the air gap magnetic density of the motor. 3. In terms of strength performance: This ensures that the overall deformation of the iron core 1 is relatively uniform at high speeds, and it is easier to achieve a lower stress level and a higher fatigue life through local optimization at the root of the magnet. 4. It can also ensure the uniformity of local deformation of the magnetic bridge at high speed. That is, while controlling the thickness of the magnetic bridge, it ensures that the magnetic bridge is at a relatively low speed at high speed. When rotating at high speed, the direction of the combined tension of each magnetic bridge part is as far along the center line of the magnetic bridge as possible (extending radially), thereby minimizing the local bending moment and stress concentration of each magnetic bridge, and thus evenly bearing the centrifugal tension.

[0036] This disclosure does not limit the specific ratio of the minimum thicknesses of the first magnetic bridge 41, the second magnetic bridge 42, and the third magnetic bridge 43. For example, in some embodiments, the ratio of the minimum thicknesses of the first magnetic bridge 41, the third magnetic bridge 43, and the second magnetic bridge 42 can be 1.2X:1:0.8Y, where the values ​​of X and Y are 0.95 to 1.05. For example, when X and Y are both 1, the ratio of the minimum thicknesses of the three can be 1.2:1:0.8. In addition, in some other embodiments, the ratio of the minimum thicknesses of the three can also be 6:5:4. This disclosure does not limit this.

[0037] In this disclosure, when the motor rotor is at high speed, the entire shaft is subjected to circumferential tensile stress generated by centrifugal force, causing circumferential and radial deformation of the iron core 1. Simultaneously, due to the presence of the mounting slot, the inner region of the iron core 1 is connected to the outer magnetic bridge via the second magnetic bridge 42, the third magnetic bridge 43, and the fifth magnetic bridge 45. However, the radial and circumferential deformations of the inner and outer regions of the iron core 1 at the connection point of the third magnetic bridge 43 are not identical. This deformation mismatch generates a local bending moment effect at the third magnetic bridge 43 (generated by tensile force towards the second magnet 32), leading to a high-stress zone at the four root regions of the third magnetic bridge 43 under the combined influence of circumferential tensile stress, tensile stress along the centerline, and local bending and torsional loads. As the motor rotor enters ultra-high-speed operation, the deformation mismatch in each region becomes even more pronounced, and the stress concentration effect becomes more significant. Based on this technical problem, this disclosure optimizes various data of the motor rotor as follows: In some embodiments of this disclosure, the circumferential dimension of the second magnet 32 ​​may be smaller than the circumferential dimension of the third magnet 33. Here, the circumferential dimension refers to the length of the side of the magnet closest to the circumferential direction. For example, in Figure 17 In the illustrated embodiment, the second magnet 32 ​​and the third magnet 33 each have a long side (length) and a short side (width). The extension direction of the long side is closer to the circumferential direction, while the extension direction of the short side is closer to the radial direction. Therefore, this specifically refers to the fact that the length of the long side of the second magnet 32 ​​is smaller than the length of the long side of the third magnet 33. This design allows control over the angle between the two third magnet bridges 43, i.e., the angle between the centerlines of the two third magnet bridges 43. Controlling this angle within a certain range prevents excessively large angles from causing prominent bending and torsional deformation of the core 1, leading to a surge in stress and ensuring the motor rotor strength meets the design requirements for ultra-high speeds.

[0038] Reference Figure 16In some embodiments of this disclosure, the obtuse angle A7 formed between the two second magnets 32 in their circumferential extension directions can be greater than or equal to 175°, such as 175°, 178°, 180°, etc. This design is beneficial to both electromagnetic performance and the strength of the core 1. It should be noted that the second magnets 32 have two approximately radially extending width sides and two approximately circumferentially extending length sides. The circumferential extension direction of the second magnets 32 is also the direction of their length sides. The obtuse angle formed between the length sides of the two second magnets 32 is A7. A2 and A3 mentioned below can also refer to A7. The circumferential extension direction of the corresponding magnets also refers to the direction of the length sides of the corresponding two magnets. A2 and A3 are also obtuse angles formed by the length sides of the corresponding two magnets in their radial direction, which will not be explained further below.

[0039] Reference Figure 3 In some embodiments of this disclosure, the portion of the sector segment 101 located between the two second mounting slots 22 is a second magnetic bridge 42, which can be symmetrically distributed about the centerline of the sector segment 101. Here, the centerline of the sector segment 101 refers to its central symmetry line, that is, the centerline can divide the sector segment 101 into two equal parts in the circumferential direction. With this design, since the second magnetic bridge 42 is a central magnetic bridge, its force is symmetrical, and therefore the symmetrical distribution of the structure is more conducive to meeting the strength requirements of the motor rotor at ultra-high speeds.

[0040] Reference Figure 8 In this disclosure, the third magnetic bridge 43 is a lateral magnetic bridge. As mentioned above, at high speeds, its deformation is a localized bending and torsional deformation pulled towards the second magnetic bridge 42 (center). Therefore, the third magnetic bridge 43 cannot be made symmetrically distributed. Its four parts are subjected to circumferential tension generated by centrifugal force and the aforementioned localized bending and torsional effects, resulting in different high stress concentration areas and different stress optimization characteristics. Therefore, it needs to be made asymmetrical to meet strength requirements. Specifically, refer to... Figure 8In some embodiments of this disclosure, the side of the third magnetic bridge 43 near the second mounting groove 22 may have a first root 431 and a second root 432, and the side of the third magnetic bridge 43 near the third mounting groove 23 may have a third root 433 and a fourth root 434. The first root 431 is located radially outward of the second root 432, and the third root 433 is located radially outward of the fourth root 434. The arc radius R3 of the first root 431 may be greater than the arc radius R3a of the third root 433, and the arc radius R2 of the second root 432 may be smaller than the arc radius R1 of the fourth root 434. This design counteracts the aforementioned tensile force towards the second magnetic bridge 42, thereby better ensuring the matching of deformation and stress under ultra-high-speed operating conditions. It needs to be explained that the arc segment at the root consists of a main arc with a larger radius and a connecting arc with a slightly smaller radius. The main arc is the key part of stress concentration, and its size determines the stress level. Here, the "arc segment radius" refers to the radius of the main arc with the larger radius at the corresponding root.

[0041] In this disclosure, the aforementioned R3a, R3, R1, and R2 can be greater than or equal to 0.3 mm, for example, 0.3 mm, 0.4 mm, and 0.5 mm. This design can avoid the corresponding stress surge and strength reduction, thereby ensuring the fatigue life of the motor rotor within the peak speed range.

[0042] As the rotational speed increases, the strain in the magnetic bridge section of core 1, especially at the second magnetic bridge 42 and the third magnetic bridge 43, increases rapidly. This area is subjected to circumferential pressure from centrifugal force and tensile force along the magnetic bridge direction. These forces in both directions generate local bending moments at the root of the magnetic bridge, leading to high stress concentration and creating a hazardous area. To address this issue, refer to... Figure 8 , Figures 11-15 In some embodiments of this disclosure, the four roots of the second magnetic bridge 42 may each have multiple arc segments. Similarly, the four roots of the third magnetic bridge 43 may each have multiple arc segments. This multi-arc design allows for smooth local transitions under bending and torsional deformation, minimizing stress concentration and reducing stress levels. The multiple arc segments can be combined tangentially.

[0043] When the motor rotor is operating, the inner side experiences a greater centrifugal force, while the outer side experiences a relatively smaller centrifugal force. Therefore, the average stress level at the root near the inner side is higher than that at the root near the outer side. Based on this, in some embodiments, the two outermost roots of the second magnetic bridge 42 and the third magnetic bridge 43 may each have at least two arc segments. The two innermost roots of the second magnetic bridge 42 and the third magnetic bridge 43 may each have at least three arc segments.

[0044] Reference Figures 14-15In some embodiments of this disclosure, there are two symmetrical transition arcs between the minimum thickness position of the second magnetic bridge 42 and its radially inner root. These transition arcs extend to the minimum thickness position, meaning they are adjacent to it. The radius R5 of these transition arcs satisfies the condition that R5 ≥ 1.5 mm, for example, 1.5 mm, 2 mm, or 3 mm. It should be noted that there are multiple arc segments between the minimum thickness position of the second magnetic bridge 42 and its radially inner root, and the transition arc refers to the one closest to the minimum thickness position. A larger radius R5 for the aforementioned transition arc results in better electromagnetic performance (less leakage flux, better electromagnetic performance), but is detrimental to strength (thinner magnetic bridge, higher stress, lower lifespan). Using the aforementioned R5 dimension allows for a low-stress design while employing a thin-walled magnetic bridge (ensuring performance).

[0045] Reference Figure 5 In some embodiments of this disclosure, two sets of staggered ends of two sides of the first magnet 31 arranged circumferentially can respectively abut against the first groove wall of the first mounting groove 21, while the other set of staggered ends can be spaced apart from the first groove wall. That is, the first mounting groove 21 and the first magnet 31 are not shape-matched; the inner contour of the first mounting groove 21 is heterogeneous, thereby satisfying that the positions of the first magnet 31 near one set of diagonals abut against the first groove wall (see P1 / P2 in the figure), while the positions of the first magnet 31 near the other set of diagonals are spaced apart from the first groove wall. Here, "arranged circumferentially" means that the two sides of the first magnet 31 are generally arranged circumferentially, rather than absolutely arranged circumferentially. For example, in Figure 5 and Figure 17In this embodiment, the first magnet 31 has two long sides (length) and two short sides (width). The two sides arranged circumferentially refer to the two short sides, while the two long sides are arranged radially. "Two staggered ends" refers to the radially inner position of one of the two short sides and the radially outer position of the other, meaning the line connecting the two staggered ends is approximately equal to the diagonal of the first magnet 31. The explanation of "circumferentially arranged" and "two staggered ends" in the second magnet 32 ​​and the third magnet 33 is similar and will not be repeated below. Similarly, in some embodiments of this disclosure, one set of two staggered ends of the two circumferentially arranged sides of the second magnet 32 ​​can respectively abut against the second groove wall of the second mounting groove 22 (see P3 / P4 in the figure), and another set of two staggered ends can be spaced apart from the second groove wall. Two sets of staggered ends on two sides of the third magnet 33, arranged circumferentially, can abut against the third groove wall of the third mounting groove 23 (see P5 / P6 in the figure), while the other set of staggered ends can be spaced apart from the third groove wall. This design is simple in structure, precise in positioning, easy to process, and reduces damage to the positioning structure during stamping and assembly. Here, the positioning structure mainly refers to the limiting of the magnet in the short side direction (the long side direction is conventional contact and does not need to be considered), specifically the structural part where the stamped magnetic bridge groove contacts the short side of the magnetic bridge.

[0046] Reference Figures 1-3In some embodiments of this disclosure, the motor rotor may further include a carbon fiber layer 51 sleeved around the outer periphery of the iron core 1. Its core function is to provide high-strength radial constraint, withstand high-speed centrifugal force, protect the rotor lamination structure, and reduce the stress level at the root of the magnetic bridge, thereby reducing the magnetic bridge width to decrease leakage flux, improve motor power density, and increase high-speed efficiency. It can also improve the radial stiffness of the motor rotor and reduce windage losses during high-speed rotation, improving NVH performance and reducing losses. Furthermore, it can share the stress load on the magnetic bridge, reducing the design pressure on the magnetic bridge thickness, and mitigating problems such as magnetic circuit saturation and increased leakage flux caused by thickening the magnetic bridge. This balances structural strength and electromagnetic performance, improving overspeed safety margin and fatigue life. Since the energy generated by the motor rotor speed is quadratically related to the speed, it is difficult for ultra-high-speed motors to simultaneously meet the fatigue life requirements at peak speed and the safety margin design requirements for fracture speed under overspeed conditions, while satisfying the motor's electromagnetic performance. To meet the fatigue performance of the rotor laminations within the peak speed and the safety margin for overspeed fracture, not only is a thicker magnetic bridge design required, but also a thicker carbon fiber layer. However, to increase the airflow between the motor stator and rotor, the thickness of the carbon fiber layer 51 needs to be reduced. To reduce the thickness of the carbon fiber layer 51, the stress on it under high-speed conditions needs to be reduced; therefore, the degree of deformation mismatch between the core 1 and the carbon fiber layer 51 needs to be controlled. To address this technical problem, in this disclosure, the middle portion of the core 1 may have a mating hole 102, and the motor rotor may also include a rotating shaft 52 that is shape-matched and inserted into the mating hole 102. The inner contour of the mating hole 102 can be non-circular to allow the rotating shaft 52 and the core 1 to transmit torque. Here, "non-circular" can refer to multiple arc segments connected sequentially, or it can also be as follows: Figure 6 and Figure 7 The multiple arc segments and multiple straight segments shown are connected in sequence. With this design, the torsion is transmitted through the non-circular contour between the rotating shaft 52 and the mating hole 102, which can reduce the local stiffness mismatch problem caused by the torsion transmission of the flat key. At high speed, the amount of deformation mismatch between the outer side of the iron core 1 and the carbon fiber layer 51 is much lower than that of conventional flat key torsion transmission, and there is no high stress concentration problem in the torsion transmission part.

[0047] Having understood the aforementioned basic structure, the following section will introduce how to optimize the design of certain dimensions of the motor rotor.

[0048] In some embodiments of this disclosure, the included angle A4 between the centerlines of the two third magnetic bridges 43 can satisfy:

[0049] Among them, reference Figure 9 A1 is the circumferential angle of sector segment 101. (Refer to...) Figure 10A2 is the obtuse angle formed between the two third magnets 33 in the circumferential extension direction, extending radially outward. That is, the angle between the two long sides of the two third magnets 33 in the circumferential extension direction, for example, the angle between the two long sides of the magnets 33 on the radially outer side, or the angle between the two long sides of the magnets 33 on the radially inner side. (Refer to...) Figure 10 A3 is the obtuse angle formed between the two first magnets 31 in the circumferential extension direction, extending radially outward. That is, the angle between the two long sides of the two first magnets 31 in the circumferential extension direction, for example, the angle between the two long sides of the magnets 31 that are radially closer to the outer side, or the angle between the two long sides of the magnets 31 that are radially closer to the inner side. (Refer to...) Figure 17 L1 is the length of the first magnet 31, L2 is the width of the first magnet 31, L3 is the length of the third magnet 33, L4 is the width of the third magnet 33, L5 is the length of the second magnet 32, and L6 is the width of the second magnet 32. (Refer to...) Figure 11 H0 is the distance between the center point of the minimum thickness position of the first magnetic bridge 41 and the center point of the minimum thickness position of the second magnetic bridge 42. (Refer to...) Figure 9 R6 is the outer radius of core 1. K1 is a constant with a value range of 0.05-0.2, and K2 is a constant with a value range of 0.3-0.8. The values ​​of K1 and K2 can be adapted to the actual needs of the motor design. By adjusting the included angle A4 between the centerlines of the two third magnetic bridges 43, it is ensured that at high speeds, the combined tension direction of the inner and outer sides of core 1 connected at the third magnetic bridge 43 is along the centerline of the third magnetic bridge 43, minimizing the local bending moment of the third magnetic bridge 43 (minimizing the tension towards the second magnet 32), thereby reducing the high stress level in the four root regions of the third magnetic bridge 43. Based on A4, the local deformation mismatch problem at the root of the third magnetic bridge 43 can be further optimized by optimizing the minimum thickness H4 of the third magnetic bridge 43 and optimizing the matching combination of R1, R2, R3 and R3a mentioned above. Without increasing the thickness of the magnetic bridge, a lower stress level and a longer fatigue life can be achieved in the four root regions of the third magnetic bridge 43.

[0050] As the rotor speed further increases to ultra-high speeds, a plastic region gradually appears in the center of the second magnetic bridge 42. This means that under ultra-high speed conditions, the second magnetic bridge 42 is the most vulnerable part, where plastic strain accumulates rapidly. Once the speed exceeds the ultra-high speed limit, the plastic strain at the second magnetic bridge 42 quickly reaches the material's fracture strain, leading to breakage. To ensure sufficient local fracture safety margin for the second magnetic bridge 42 under ultra-high speed conditions, and to ensure a relatively small minimum thickness H2 of the second magnetic bridge to guarantee corresponding electromagnetic performance, the design of H2 is related to many factors. The specific optimization scheme is as follows: Reference Figure 4 and Figure 12 In this disclosure, the portion of the first mounting groove 21 between its radially outer corner and the outer edge of the fan-shaped segment 101 is the fourth magnetic bridge 44, and the portion of the third mounting groove 23 between its radially outer corner and the outer edge of the fan-shaped segment 101 is the fifth magnetic bridge 45. The minimum thickness H2 of the second magnetic bridge 42 satisfies:

[0051] Among them, reference Figure 13 H4 is the minimum thickness of the third magnetic bridge 43, and H3 is the maximum thickness of the third magnetic bridge 43, as shown in the reference. Figure 18 H5 is the minimum thickness of the first magnetic bridge 41, H6 is the minimum thickness of the fourth magnetic bridge 44, and H7 is the minimum thickness of the fifth magnetic bridge 45. (Refer to...) Figure 12 H1 is the maximum thickness of the second magnetic bridge 42, K3 is a constant with a value range of 0.5-1.2, K4 is a constant with a value range of 0.3-0.9, and K5 is a constant with a value range of 0.1-0.4. For different motors, K3-K5 can be adapted to the actual design requirements of the motor.

[0052] After optimization using the aforementioned formula, it is possible to ensure low stress and long lifespan of the iron core 1 while maintaining the electromagnetic performance of the motor rotor. That is, while reducing the minimum thickness H2 of the second magnetic bridge 42, the stress requirements under high-speed conditions can be met. To alleviate the stress level in the root region of the second magnetic bridge 42, which is located radially closer to the inner side, a circular arc structure can be used for transition in this region.

[0053] In some embodiments of this disclosure, the second magnetic bridge 42 has a fifth root 421 located radially inward of the second magnet 32, and the second magnet 32 ​​has a rounded corner 321 at the position corresponding to the fifth root 421. The maximum distance R4 between the center of the rounded corner 321 and the fifth root 421 can satisfy the following:

[0054] The second magnetic bridge 42 has two symmetrical straight line segments between its minimum thickness position and its radially outer root. These segments extend to the minimum thickness position, meaning they are adjacent to it. The angle between the two segments is A5. K6 is a constant with a value ranging from 0.8 to 1.5, and K7 is a constant with a value ranging from 0.9 to 1.4. K6 and K7 can be adapted to the specific design requirements of different motors. Regarding A5, at this position, the minimum thickness position of the second magnetic bridge 42 is represented by a pair of parallel straight line segments. Radially outward, there is first a transition arc, followed by a straight line tangent to this transition arc. The angle between these two lines is A5.

[0055] The R4 dimension comprehensively reflects the transition characteristics of the fifth root portion of the minimum thickness H2 of the second magnetic bridge 42, and is an important indicator of the motor rotor stress and electromagnetic performance. Through the optimization of the above formula, the second magnetic bridge 42 can be made to have sufficient fracture safety margin under overspeed conditions, while ensuring the corresponding electromagnetic performance.

[0056] To better demonstrate that the optimized electronic rotor using the above technical solution has superior technical performance, motion simulation was performed on the motor rotor obtained according to the above optimization scheme. Specifically, in the simulation stress cloud diagram mentioned below, the stress is represented by letters A, B, C, D, E, F, G... in that order, and the specific values ​​can be referred to the corresponding numerical labels in the figure. This point will not be elaborated further below.

[0057] The stress gradient cloud diagram of the motor rotor at peak speed is shown below. Figure 19 As shown, the location of maximum strain is at the first root 431, where stress is concentrated in a very small area, indicating a large stress gradient. The strain at this location meets the fatigue design requirements. Under overspeed conditions, as the rotational speed increases further, the strain will increase further, and the maximum strain will shift to the middle of the second magnetic bridge 42 (where the contour lines are further back and most densely distributed). Figure 20 As shown, the second magnetic bridge 42 is the most dangerous part. Figure 21 This is an enlarged view of the strain contour lines at location 42 of the second magnetic bridge. Figure 22 These are the strain contour lines at the minimum thickness. The area at the minimum thickness of the second magnetic bridge 42 is a region with significant strain concentration (high density of contour lines), and the corresponding strain meets the safety margin for fracture strain. At peak speed, the radial displacement deformation of the motor rotor is as follows: Figure 23 As shown, the radial deformation cloud map corresponding to the adopted electromagnetic topology scheme and torsion transmission scheme is relatively uniform. Specifically, the radial deformation of the entire rotor is much more uniform compared to the rotor scheme with a keyed design in related technologies. The keyed rotor exhibits severely uneven stiffness distribution on the inner side, which on the one hand leads to excessive stress at the keyed laminations, and on the other hand leads to deformation mismatch, thus increasing the stress in the carbon fiber layer 51. Regarding the carbon fiber layer 51, as can be seen from the figure, the current design scheme results in a relatively uniform overall stress distribution with no large stress gradient distribution. Therefore, the stress distribution in the carbon fiber layer 51 is relatively uniform and the stress level is relatively low, and the stress distribution contour lines are also relatively uniform. Figure 24 As shown, Figure 24 It is an equivalent stress distribution cloud map of a local area of ​​the carbon fiber layer. The design requirements can be met by using conventional carbon fiber.

[0058] The curve showing the change in rotor stress level of the motor with rotational speed is as follows: Figure 25As shown, the horizontal axis represents rotational speed, V_max represents the overspeed condition, and the curves represent the strain-rotational speed changes at the points of interest as the rotational speed increases. There are three curves in the figure. Curve A specifically represents the part with the largest strain at the root of core 1, specifically the part with the larger strain between the first root (431) and the third root (433). B1 and B2 both represent the stress at the center of the second magnetic bridge (42). The difference between them is that they correspond to different positions on the inner edge of core 1, for example, at... Figures 6-7 In the illustrated embodiment, the inner edge of the core 1 includes a straight segment and a circular arc segment. B1 refers to the two second magnetic bridges 42 corresponding to the inner straight segment, and B2 refers to the four second magnetic bridges 42 corresponding to the inner circular arc segment. The allowable design strain is the value corresponding to the design criteria. If it is lower than this value, it indicates that the design requirements are met. This value depends on the material itself and the design safety margin, while also considering static strength and fatigue performance under long-term operation. Furthermore, if the strain value is below the inflection point of its respective curve (the appearance of the inflection point indicates a rapid decrease in the local structure's resistance to fracture), it indicates relative safety. If it exceeds the inflection point, there is a phenomenon where the strain increases rapidly with a slight increase in rotational speed (accelerated fracture stage), which is more dangerous. It can be seen that at the peak rotational speed (V), the strain is lower than the inflection point; under overspeed conditions, it is near but lower than the inflection point, which can simultaneously ensure the long-life design requirements under normal operating conditions and the fracture safety margin under overspeed conditions.

[0059] As can be seen from the above scheme and simulation results, the motor rotor disclosed herein, through topology design, has a thinner carbon fiber layer 51, a smaller stator and rotor air gap, and a smaller magnetic bridge thickness, especially the inner magnetic bridge thickness. This can simultaneously meet the requirements of long life design and high-speed external characteristics of the motor, and has good economic performance and engineering applicability.

[0060] According to a second aspect of this disclosure, an electric motor is provided, including the aforementioned motor rotor, since the motor has all the beneficial effects of the aforementioned motor rotor, which will not be repeated here.

[0061] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0062] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0063] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A motor rotor, characterized in that, Includes an iron core, which can be divided into multiple equally sized sector segments along its circumference, each sector segment having: Two first mounting slots, the two first mounting slots forming a V-shaped profile with the opening facing radially outward; and The two second mounting slots and two third mounting slots are located radially inside the two first mounting slots, with the two second mounting slots positioned between the two third mounting slots to collectively form a C-shaped profile with the opening facing outwards along the radial direction. The motor rotor further includes a first magnet installed in the first mounting slot, a second magnet installed in the second mounting slot, and a third magnet installed in the third mounting slot.

2. The motor rotor according to claim 1, characterized in that, The portion of the sector-shaped segment located between the two first mounting slots forms a first magnetic bridge, the portion located between the two second mounting slots forms a second magnetic bridge, and the portion located between an adjacent second mounting slot and a third mounting slot forms a third magnetic bridge. The minimum thickness of the first magnetic bridge, the third magnetic bridge, and the second magnetic bridge decreases sequentially.

3. The motor rotor according to claim 2, characterized in that, The ratio of the minimum thickness of the first magnetic bridge, the third magnetic bridge, and the second magnetic bridge is: 1.2X:1:0.8Y, where the values ​​of X and Y range from 0.95 to 1.

05.

4. The motor rotor according to claim 1, characterized in that, The second magnet has a smaller circumferential dimension than the third magnet.

5. The motor rotor according to claim 1, characterized in that, The obtuse angle A7 formed between the two second magnets in the circumferential extension direction along the radial outward direction satisfies greater than or equal to 175°.

6. The motor rotor according to claim 1, characterized in that, The portion of the sector segment located between the two second mounting slots constitutes a second magnetic bridge, and the second magnetic bridge is symmetrically distributed about the centerline of the sector segment.

7. The motor rotor according to claim 1, characterized in that, The portion of the sector-shaped segment located between adjacent second and third mounting slots forms a third magnetic bridge. The third magnetic bridge has a first root and a second root on the side near the second mounting slot, and a third root and a fourth root on the side near the third mounting slot. The first root is located radially outward of the second root, and the third root is located radially outward of the fourth root. Wherein, the arc radius R3 of the first root is greater than the arc radius R3a of the third root, and the arc radius R2 of the second root is less than the arc radius R1 of the fourth root.

8. The motor rotor according to claim 7, characterized in that, R3a, R3, R1, and R2 are each greater than or equal to 0.3 mm.

9. The motor rotor according to claim 1, characterized in that, The portion of the sector segment located between the two second mounting slots is a second magnetic bridge, and the portion located between adjacent second mounting slots and the third mounting slot is a third magnetic bridge. The four root portions of the second magnetic bridge each have multiple arc segments; and / or, the four root portions of the third magnetic bridge each have multiple arc segments.

10. The motor rotor according to claim 9, characterized in that, The second magnetic bridge and the third magnetic bridge each have at least two arc segments at their two outermost root portions in the radial direction; and / or, the second magnetic bridge and the third magnetic bridge each have at least three arc segments at their two innermost root portions in the radial direction.

11. The motor rotor according to claim 9, characterized in that, The second magnetic bridge has two symmetrical transition arcs between the minimum thickness position and the root of the second magnetic bridge on the radially inner side, the transition arcs extending to the minimum thickness position, and the radius R5 of the transition arcs satisfying: R5≥1.5mm.

12. The motor rotor according to claim 1, characterized in that, The first magnet has two sets of staggered ends on two sides arranged in the circumferential direction, which respectively abut against the first wall of the first mounting groove; and another set of staggered ends are spaced apart from the first wall of the groove; and / or, The second magnet has two sets of staggered ends on two sides arranged in the circumferential direction, which respectively abut against the second wall of the second mounting groove; and another set of staggered ends are spaced apart from the second wall of the groove; and / or, The two staggered ends of the third magnet on the two sides arranged in the circumferential direction respectively abut against the third wall of the third mounting groove, and the two staggered ends of the other set are spaced apart from the third wall.

13. The motor rotor according to claim 1, characterized in that, It also includes a carbon fiber layer sleeved around the outer periphery of the iron core, the middle portion of the iron core having a mating hole, and the motor rotor also includes a rotating shaft that is shaped and inserted into the mating hole. The inner contour of the mating hole is non-circular to allow the shaft and the iron core to transmit torque.

14. The motor rotor according to any one of claims 1-13, characterized in that, The portion of the sector segment located between the two first mounting slots is a first magnetic bridge, the portion located between the two second mounting slots is a second magnetic bridge, and the portion located between an adjacent second mounting slot and a third mounting slot is a third magnetic bridge. The included angle A4 between the centerlines of the two third magnetic bridges satisfies: Wherein, A1 is the angle of the sector segment in the circumferential direction, A2 is the obtuse angle formed between the two third magnets in the circumferential extension direction along the radial outward direction, A3 is the obtuse angle formed between the two first magnets in the circumferential extension direction along the radial outward direction, L1 is the length of the first magnet, L2 is the width of the first magnet, L3 is the length of the third magnet, L4 is the width of the third magnet, L5 is the length of the second magnet, L6 is the width of the second magnet, H0 is the distance between the center point of the minimum thickness position of the first magnetic bridge and the center point of the minimum thickness position of the second magnetic bridge, R6 is the outer radius of the iron core, K1 is a constant with a value range of 0.05-0.2, and K2 is a constant with a value range of 0.3-0.

8.

15. The motor rotor according to claim 14, characterized in that, The portion of the first mounting groove between its radially outer corner and the outer edge of the fan-shaped segment forms a fourth magnetic bridge; the portion of the third mounting groove between its radially outer corner and the outer edge of the fan-shaped segment forms a fifth magnetic bridge; and the minimum thickness H2 of the second magnetic bridge satisfies: Wherein, H4 is the minimum thickness of the third magnetic bridge, H3 is the maximum thickness of the third magnetic bridge, H5 is the minimum thickness of the first magnetic bridge, H6 is the minimum thickness of the fourth magnetic bridge, H7 is the minimum thickness of the fifth magnetic bridge, H1 is the maximum thickness of the second magnetic bridge, K3 is a constant with a value range of 0.5-1.2, K4 is a constant with a value range of 0.3-0.9, and K5 is a constant with a value range of 0.1-0.

4.

16. The motor rotor according to claim 15, characterized in that, The second magnetic bridge has a fifth root at a position close to the inner side of the second magnet in the radial direction. The second magnet has a rounded corner at a position corresponding to the fifth root. The maximum distance R4 from the center of the rounded corner to the fifth root satisfies the following condition: Wherein, the minimum thickness position of the second magnetic bridge and the root of the second magnetic bridge located radially outward have two symmetrical straight line segments, the straight line segments extending to the minimum thickness position, the included angle between the two straight line segments is A5, K6 is a constant with a value range of 0.8-1.5, and K7 is a constant with a value range of 0.9-1.

4.

17. An electric motor, characterized in that, The motor rotor includes any one of claims 1-16.

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