Stator and rotor structure of motor

Abstract

The utility model discloses a stator and rotor structure of a motor, and relates to the technical field of motors. The stator and rotor structure of the motor comprises a rotor and a stator surrounding the circumferential side of the rotor, an air gap is formed between the outer wall surface of the rotor and the inner wall surface of the stator, the air gap comprises a plurality of air gap sections arranged in the circumferential direction of the rotor, and the size of each air gap section is gradually increased in the direction from the middle to the edge. According to the stator and rotor structure, the plurality of air gap sections in the stator and rotor structure can be combined into air gaps with non-uniform sizes, and the magnetic flux density distribution in the air gaps is closer to sine waves, so that the cogging torque of the motor can be reduced; simultaneously; the non-uniform air gaps help to optimize the sinusoidal property of the back electromotive force waveform of the motor, weaken higher harmonics and make the fundamental wave proportion high, so that the ripple torque is reduced, the torque pulsation is reduced, and the motor runs more smoothly.

Description

Technical Field

[0001] This application relates to the field of motor technology, and in particular to a stator and rotor structure for an electric motor. Background Technology

[0002] An electric motor is a drive device that generates torque through the interaction between a magnetic field and an electric current. When current passes through the windings of the motor stator, a magnetic field is generated. The magnetic field interacts with the permanent magnets on the motor rotor to generate torque, thereby driving the rotor to rotate.

[0003] In existing technology, the rotor of a motor has a perfectly circular outer profile, forming a uniform air gap with the stator. The dimensions of each segment of this uniform air gap are the same. However, the magnetic flux density distribution within the uniform air gap is closer to a trapezoidal wave, with more harmonics, resulting in increased cogging torque and a poor back electromotive force waveform. Utility Model Content

[0004] To overcome the shortcomings of the prior art, this application provides a stator-rotor structure with non-uniform air gap size.

[0005] The stator and rotor structure of the electric motor provided in this application adopts the following technical solution:

[0006] A stator-rotor structure for an electric motor includes a rotor and a stator surrounding the rotor. An air gap is formed between the outer wall of the rotor and the inner wall of the stator. The air gap includes a plurality of air gap segments arranged circumferentially around the rotor, and the size of each air gap segment gradually increases from its center to its edge.

[0007] By adopting the above technical solution, multiple air gap segments can be combined to form an air gap with uneven size. The magnetic flux density distribution in this air gap is closer to a sine wave, which is beneficial to reducing the cogging torque of the motor. At the same time, the uneven air gap helps to optimize the sinusoidal nature of the back electromotive force waveform of the motor, weaken higher harmonics, and make the fundamental wave account for a higher proportion, thereby reducing ripple torque, reducing torque pulsation, and making the motor run more smoothly.

[0008] In one specific implementation, the plurality of air gap segments include a plurality of first air gap segments and a plurality of second air gap segments, the plurality of first air gap segments and the plurality of second air gap segments being arranged at intervals around the circumference of the rotor, wherein the length of the first air gap segment in the circumferential direction of the rotor is greater than the length of the second air gap segment in the circumferential direction of the rotor.

[0009] By adopting the above technical solution, the non-uniformity of the air gap is further improved, thereby more effectively reducing the cogging torque of the motor and further optimizing the sinusoidal nature of the back EMF waveform of the motor.

[0010] In one specific implementation, the outer wall of the rotor includes a plurality of arc-shaped first walls and a plurality of arc-shaped second walls, the plurality of first walls and the plurality of second walls being arranged circumferentially around the rotor at intervals, the chord length of the first walls being greater than the chord length of the second walls, a first air gap segment being formed between the first walls and the inner wall, and a second air gap segment being formed between the second walls and the inner wall.

[0011] In one specific implementation, a positioning groove is provided on the first wall surface, and the positioning groove extends along the axial direction of the rotor.

[0012] By adopting the above technical solutions, the harmonic content of the motor can be reduced, the cogging torque of the motor can be reduced, and the back EMF waveform of the motor can be optimized, making the back EMF waveform of the motor more sinusoidal. At the same time, the positioning slot can also play a positioning role. During the magnet insertion process, the positioning slot can restrict the rotor rotation and facilitate the insertion of magnets.

[0013] In one specific implementation, the rotor has multiple magnetic grooves circumferentially arranged on it, and the multiple magnetic grooves correspond one-to-one with the multiple first walls. Each magnetic groove has a magnetic end at both ends, and the two magnetic ends correspond to the two second walls on both sides of the corresponding first wall. A magnetic bridge is formed between each magnetic end and the corresponding second wall, and the size of the magnetic bridge gradually increases along the edge of the second wall towards the middle.

[0014] By adopting the above technical solution, the magnetic bridge helps to reduce the cogging torque of the motor, reduce torque pulsation, and optimize the sinusoidal nature of the motor's back electromotive force waveform.

[0015] In one specific implementation scheme, the inner diameter of the stator is D1, and the range of D1 is 27-29 mm.

[0016] By adopting the above technical solutions, the back EMF phase voltage of the motor can be increased, the cogging torque of the motor can be reduced, and the operating efficiency of the motor can be improved.

[0017] In one specific implementation, the stator includes an annular sleeve portion and a plurality of stator teeth spaced apart on the inner circumferential side of the sleeve portion. The distance between the end face of the stator teeth away from the sleeve portion and the inner surface of the sleeve portion is L1, and the range of L1 is 8 to 9 mm.

[0018] By adopting the above technical solutions, the cogging torque of the motor can be reduced and the operating efficiency of the motor can be improved.

[0019] In one specific implementation, the stator tooth includes a support portion disposed on the sleeve portion and extending radially inward along the sleeve portion, and a toothed shoe disposed at the end of the extension direction of the support portion. The width of the support portion is W1, and the range of W1 is 6-7 mm.

[0020] By adopting the above technical solutions, the cogging torque of the motor can be reduced, the output torque and efficiency of the motor can be balanced, and the motor can achieve greater output torque and higher operating efficiency.

[0021] In one specific implementation, there is a gap between each pair of adjacent toothed shoes, the size of which is W2, and W2 ranges from 2.5 to 3.5 mm.

[0022] By adopting the above technical solution, the effective voltage value of the back electromotive force of the motor can be improved.

[0023] In one specific implementation, the thickness of the toothed shoe in the radial direction of the sleeve portion is H3, and the range of H3 is 0.8 to 1.5 mm.

[0024] By adopting the above technical solution, the phase voltage of the back electromotive force of the motor can be improved.

[0025] In summary, this application includes at least one of the following beneficial technical effects:

[0026] 1. Multiple air gap segments can be combined to form an air gap with uneven size. The magnetic flux density distribution in this air gap is closer to a sine wave, which is beneficial to reducing the cogging torque of the motor.

[0027] 2. Uneven air gap helps optimize the sinusoidal nature of the motor's back EMF waveform, weakens higher harmonics, and increases the proportion of the fundamental wave, thereby reducing ripple torque, lowering torque pulsation, and making the motor run more smoothly. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the stator and rotor structure according to an embodiment of this application.

[0029] Figure 2 This is a schematic diagram of the rotor according to an embodiment of this application.

[0030] Figure 3 This is a schematic diagram of the stator according to an embodiment of this application.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1. Rotor; 11. First wall surface; 12. Second wall surface; 2. Stator; 21. Sleeve part; 22. Stator tooth; 221. Support part; 222. Tooth shoe; 3. Air gap; 31. First air gap section; 32. Second air gap section; 4. Positioning groove; 5. Magnet groove; 6. Magnetic end; 7. Magnetic isolation bridge; 8. Shaft hole. Detailed Implementation

[0033] The present application will be further described in detail below with reference to the accompanying drawings.

[0034] See Figure 1 As shown, a stator and rotor structure of an electric motor is shown, including a rotor 1 and a stator 2 surrounding the rotor 1. An air gap 3 is formed between the outer wall of the rotor 1 and the inner wall of the stator 2. The air gap 3 includes a plurality of air gap segments arranged circumferentially around the rotor 1, and the size of each air gap segment gradually increases from its center to its edge.

[0035] In this embodiment, the multiple air gap segments include four first air gap segments 31 and four second air gap segments 32. The four first air gap segments 31 and four second air gap segments 32 are arranged at intervals around the circumference of the rotor 1. The length of the first air gap segment 31 in the circumferential direction of the rotor 1 is greater than the length of the second air gap segment 32 in the circumferential direction of the rotor 1.

[0036] In this way, the four first air gap sections 31 and the four second air gap sections 32 can be combined to form an air gap 3 with uneven size. The magnetic flux density distribution in the air gap 3 is closer to a sine wave, which is beneficial to reducing the cogging torque of the motor. At the same time, the uneven air gap 3 helps to optimize the sinusoidal nature of the back electromotive force waveform of the motor, weaken the higher harmonics, and make the fundamental wave account for a higher proportion, thereby reducing ripple torque, reducing torque pulsation, and making the motor run more smoothly.

[0037] The table below shows a comparison of relevant parameters between motors in the prior art and the motor of this embodiment.

[0038] Cogging torque back potential Existing technology 146.4246 114.9230 This embodiment 77.0737 115.4406

[0039] As can be seen from the table above, the motor in this embodiment has a lower cogging torque and its back EMF is also improved compared to motors in the prior art.

[0040] In this embodiment, as Figure 1-2As shown, the outer wall of rotor 1 includes four arc-shaped first walls 11 and four arc-shaped second walls 12. The four first walls 11 and four second walls 12 are arranged circumferentially around rotor 1. The chord length of the first walls 11 is greater than the chord length of the second walls 12. A first air gap section 31 is formed between the first walls 11 and the inner wall, and a second air gap section 32 is formed between the second walls 12 and the inner wall. The outer wall formed by the four first walls 11 and the four second walls 12 is in a quincunx shape, thereby ensuring that the air gap 3 formed between the outer wall of rotor 1 and the inner wall of stator 2 can be a non-uniform air gap 3.

[0041] In this embodiment, combined with Figure 2 As shown, a positioning groove 4 is formed in the middle of the first wall surface 11, extending along the axial direction of the rotor 1. The positioning groove 4 is a semi-circular groove with a radius of R1, ranging from 0.9 to 1.3 mm. By setting the positioning groove 4, the harmonic content of the motor can be reduced, the cogging torque of the motor can be reduced, and the back EMF waveform of the motor can be optimized, making the back EMF waveform closer to a sine curve. Simultaneously, the positioning groove 4 also serves a positioning function. During the magnet insertion process, if the rotor 1 lacks circumferential positioning, the rotor 1 may rotate axially, increasing the difficulty of magnet insertion. By setting the positioning groove 4, the rotation of the rotor 1 can be restricted, facilitating magnet insertion. Furthermore, the multiple positioning grooves 4 on the rotor 1 can be designed with different sizes, allowing for positioning based on different groove sizes to distinguish magnet polarity or for other process positioning.

[0042] The table below shows the motor-related parameters obtained when the radius R1 of the positioning slot 4 takes different values.

[0043] R1(mm) Cogging torque back potential 0.5 77.0819 160.7298 0.7 64.5281 163.7298 0.9 51.1055 165.8315 1.0 48.0690 165.9855 1.1 41.4407 165.2398 1.3 38.9520 161.6954 1.5 58.1646 163.3101

[0044] As can be seen from the table above, the cogging torque of the motor reaches its lowest point when the radius of the positioning slot 4 is 1.3mm, at which point the back EMF of the motor is also relatively good.

[0045] In this embodiment, combined with Figure 2 As shown, a shaft hole 8 is formed at the center of the rotor 1. Four magnetic slots 5 are formed around the circumference of the rotor 1 around the shaft hole 8. The four magnetic slots 5 correspond one-to-one with four first wall surfaces 11. Each magnetic slot 5 has a magnetic end 6 at both ends. The two magnetic ends 6 correspond to the two second wall surfaces 12 on both sides of the corresponding first wall surface 11. A magnetic isolation bridge 7 is formed between each magnetic end 6 and the corresponding second wall surface 12. The size of the magnetic isolation bridge 7 gradually increases from the edge to the center of the second wall surface 12. The magnetic isolation bridge 7 helps to reduce the cogging torque of the motor, reduce torque ripple, and optimize the sinusoidal nature of the back electromotive force waveform of the motor.

[0046] In this embodiment, as Figure 3 As shown, the inner diameter of stator 2 is D1, which ranges from 27 to 29 mm. Within this inner diameter range, stator 2 can increase the back EMF phase voltage of the motor, reduce the cogging torque of the motor, and improve the operating efficiency of the motor.

[0047] The table below shows the motor-related parameters obtained when the inner diameter D1 of stator 2 takes different values.

[0048] D1(mm) Back potential phase voltage Cogging torque efficiency 27 5.454 0.075096 84.773 28 5.517 0.090016 83.746 29 5.641 0.12131 82.253 30 5.559 0.16203 80.496 31 5.068 0.18656 76.964 32 3.736 0.18913 68.999

[0049] As can be seen from the table above, when the inner diameter of stator 2 is 27-29mm, the back EMF phase voltage is relatively high, while the cogging torque is relatively small, and the motor operating efficiency is also relatively high.

[0050] In this embodiment, combined with Figure 3 As shown, the stator 2 includes an annular sleeve portion 21 and a plurality of stator teeth 22 spaced apart on the inner circumferential side of the sleeve portion 21. The distance between the end face of the stator teeth 22 away from the sleeve portion 21 and the inner surface of the sleeve portion 21 is L1, and the range of L1 is 8 to 9 mm. The stator teeth 22 within this range can reduce the cogging torque of the motor and improve the operating efficiency of the motor.

[0051] The table below shows the motor-related parameters obtained when the distance L1 takes different values.

[0052] L1(mm) Cogging torque efficiency Output torque 7.5 0.071627 87.351 2.7873 8 0.072094 86.441 2.7519 8.5 0.075096 84.773 2.6704 9 0.089536 83.522 2.5379 9.5 0.11995 81.659 2.2643 10 0.15663 79.877 1.9405

[0053] As shown in the table above, as L1 continuously increases, the cogging torque increases significantly, while the efficiency decreases. The table also indicates that performance is better when L1 is between 7.5 and 8.0 mm. However, in actual manufacturing processes, if L1 is too small, the area of ​​the winding slots between adjacent stator teeth 22 will decrease, affecting the wire diameter and number of turns, thus impacting the slot fill factor and limiting the winding scheme. Therefore, in this embodiment, L1 is set to a range of 8–9 mm. At this range, the cogging torque is relatively small, the motor operating efficiency is high, and the process feasibility is high.

[0054] In this embodiment, combined with Figure 3 As shown, the stator tooth 22 includes a support portion 221 disposed on the sleeve portion 21 and extending radially inward along the sleeve portion 21, and a toothed shoe 222 disposed at the end of the extension direction of the support portion 221. The width of the support portion 221 is W1, and the range of W1 is 6-7 mm. The toothed shoe 222 within this width range can reduce the cogging torque of the motor, balance the output torque and efficiency of the motor, and enable the motor to achieve greater output torque and higher operating efficiency.

[0055] The table below shows the motor-related parameters obtained when the width W1 of the support part 221 takes different values.

[0056] W1(mm) Cogging torque efficiency Output torque 5 0.097808 87.554 3.7947 5.5 0.087043 87.802 3.9518 6 0.07904 88.137 4.0765 6.5 0.074129 88.351 4.1479 7 0.071406 88.584 4.1981

[0057] As can be seen from the table above, the motor operates more efficiently when the width of the support part 221 is 6-7mm. At this time, the motor's cogging torque is also in a favorable state, balancing the motor's output torque and efficiency, ensuring that the motor can achieve greater output torque and higher efficiency.

[0058] In one specific implementation, W1 is designed to be 6.4mm. In this case, the support portion 221 can have sufficient strength and magnetic conductivity, and the support portion 221 will not be too wide and compress the winding space between the support portions 221.

[0059] In this embodiment, combined with Figure 3 As shown, there is a gap between each pair of adjacent toothed shoes 222, with a gap size of W2 ranging from 2.5 to 3.5 mm. Toothed shoes 222 within this size range can increase the effective voltage value of the motor's back electromotive force.

[0060] The table below shows the motor-related parameters obtained when the clearance dimension W2 takes different values.

[0061] W2(mm) Back potential phase voltage Cogging torque 2.5 8.011 0.063386 3 8.02 0.075096 3.5 7.975 0.086751 4 7.878 0.098005

[0062] As can be seen from the table above, when the gap size W2 is between 2.5 and 3.5 mm, the effective voltage value of the back electromotive force is relatively large, while the cogging torque is relatively small. Meanwhile, the effect of W2 on motor efficiency does not change significantly within a small range.

[0063] In one specific implementation, W2 is designed to be 3mm. This is because, in actual production, if W2 is too small, it is easy to puncture the wire coating and affect the wire path of the winding nozzle. If the actual production wire diameter is larger, W2 can be designed to be 3-3.5mm.

[0064] In this embodiment, combined with Figure 3 As shown, the thickness of the toothed shoe 222 in the radial direction of the sleeve portion 21 is H3, and the range of H3 is 0.8 to 1.5 mm. The toothed shoe 222 within this thickness range can improve the phase voltage of the motor's back electromotive force.

[0065] The table below shows the motor-related parameters obtained when the thickness H2 of the toothed shoe 222 takes different values.

[0066] H3 Back potential phase voltage 0.5 4.631 1 4.811 1.5 4.776 2 4.765 2.5 4.758 3 4.751

[0067] As can be seen from the table above, the back electromotive force phase voltage of the motor is the highest when the thickness H3 of the toothed shoe 222 is 1mm. Therefore, the thickness H3 of the toothed shoe 222 is preferably 1mm.

[0068] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A rotor-stator structure of an electric machine comprising a rotor (1) and a stator (2) surrounding the rotor (1) on the side thereof, characterized in that: An air gap (3) is formed between the outer wall surface of the rotor (1) and the inner wall surface of the stator (2). The air gap (3) includes a plurality of air gap segments arranged circumferentially around the rotor (1). The size of each air gap segment gradually increases from its center to its edge. The plurality of air gap segments include a plurality of first air gap segments (31) and a plurality of second air gap segments (32). The plurality of first air gap segments (31) and the plurality of second air gap segments (32) are arranged at intervals around the circumference of the rotor (1). The length of the first air gap segment (31) in the circumferential direction of the rotor (1) is greater than the length of the second air gap segment (32) in the circumferential direction of the rotor (1). The outer wall of the rotor (1) includes multiple arc-shaped first walls (11) and multiple arc-shaped second walls (12). Multiple magnetic grooves (5) are formed around the rotor (1) in its circumference. The multiple magnetic grooves (5) correspond one-to-one with the multiple first walls (11). Each magnetic groove (5) has a magnetic end (6) at both ends. The two magnetic ends (6) correspond to the two second walls (12) on both sides of the corresponding first wall (11). A magnetic bridge (7) is formed between each magnetic end (6) and the corresponding second wall (12). The size of the magnetic bridge (7) gradually increases from the edge to the middle of the second wall (12).

2. A stator-rotor structure of an electric machine according to claim 1, characterized in that: The plurality of first wall surfaces (11) and the plurality of second wall surfaces (12) are arranged circumferentially around the rotor (1), the chord length of the first wall surface (11) is greater than the chord length of the second wall surface (12), the first air gap section (31) is formed between the first wall surface (11) and the inner wall surface, and the second air gap section (32) is formed between the second wall surface (12) and the inner wall surface.

3. A stator-rotor structure for an electric machine according to claim 2, characterized in that: A positioning groove (4) is provided on the first wall surface (11), and the positioning groove (4) extends along the axial direction of the rotor (1).

4. A stator-rotor structure of an electric machine according to claim 1, characterized in that: The inner diameter of the stator (2) is D1, and the range of D1 is 27~29mm.

5. A stator-rotor structure of an electric machine according to claim 1, characterized in that: The stator (2) includes an annular sleeve portion (21) and a plurality of stator teeth (22) spaced apart on the inner circumferential side of the sleeve portion (21). The distance between the end face of the stator teeth (22) away from the sleeve portion (21) and the inner surface of the sleeve portion (21) is L1, and the range of L1 is 8~9mm.

6. A stator-rotor structure for an electric machine according to claim 5, characterized in that: The stator tooth (22) includes a support portion (221) disposed on the sleeve portion (21) and extending radially inward along the sleeve portion (21), and a toothed shoe (222) disposed at the end of the extension direction of the support portion (221). The width of the support portion (221) is W1, and the range of W1 is 6~7mm.

7. A stator-rotor structure for an electric machine according to claim 6, characterized in that: There is a gap between each pair of adjacent toothed boots (222), the size of which is W2, and the range of W2 is 2.5~3.5mm.

8. A stator-rotor structure of an electric machine according to claim 6, characterized in that: The toothed shoe (222) has a thickness of H3 in the radial direction of the sleeve portion (21), and the range of H3 is 0.8~1.5mm.

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