Electric motor and household appliance

Abstract

Disclosed in the present application are an electric motor and a household appliance, the electric motor comprising a stator (200) and a rotor (100). The rotor (100) comprises a plurality of fan-shaped portions (110) and a plurality of permanent magnets (120), wherein the plurality of fan-shaped portions (110) are arranged around the rotational axis of the electric motor, and mounting slots (111) are formed between adjacent fan-shaped portions (110); the plurality of permanent magnets (120) are correspondingly arranged in the plurality of mounting slots (111). The stator (200) is sleeved on the outer side of the rotor (100) and comprises a yoke portion (210) and a plurality of tooth shoe portions (220), wherein the plurality of tooth shoe portions (220) are connected to the inner wall of the yoke portion (210) and spaced apart in the circumferential direction of the rotational axis.

Description

Motors and household appliances

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese patent applications filed on July 10, 2024, with application number 202410926692.6 entitled "Electrical Machines and Household Appliances" and application number 202421631355.6 entitled "Electrical Machines and Household Appliances", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of motor technology, and in particular to a motor and a household appliance. Background Technology

[0004] A brushless DC motor consists of a rotor and a stator, with the stator mounted on the outside of the rotor. The rotor rotates relative to the stator through the interaction of the magnetic field generated by the stator windings and the magnetic field generated by the permanent magnets of the rotor. Therefore, brushless DC motors have a simple structure and high reliability. However, existing brushless DC motors are relatively large and have low power density, making it difficult to meet the miniaturization requirements of motors. Summary of the Invention

[0005] This application aims to at least partially solve one of the technical problems existing in the prior art. To this end, this application proposes an electric motor that can reduce the size of the motor, making the motor structure more compact, which is conducive to the miniaturization design of the motor and thus improves the power density.

[0006] This application also proposes a household appliance having the aforementioned motor.

[0007] According to a first aspect of the present application, an electric motor includes: a rotor, comprising a plurality of sector-shaped portions and a plurality of permanent magnets, wherein the plurality of sector-shaped portions are arranged around the rotation axis of the motor, and a mounting groove is formed between adjacent sector-shaped portions, and the plurality of permanent magnets are correspondingly disposed in the plurality of mounting grooves;

[0008] A stator is sleeved on the outside of the rotor. The stator includes a yoke and a plurality of toothed shoe portions, which are circumferentially spaced and connected to the inner wall of the yoke along the axis of rotation.

[0009] Wherein, the number of permanent magnets is X, the number of toothed shoe parts is Y, satisfying: 0.8≤Y / X≤0.9; the diameter of the minimum circumscribed circle of the rotor is D1, and the maximum length of the permanent magnet along the radial direction of the motor is L, satisfying: 0.2≤L / D1≤0.25.

[0010] The motor according to the embodiments of this application has at least the following beneficial effects:

[0011] By positioning the permanent magnets of the rotor within mounting slots between adjacent sector sections, and with the stator fitted onto the outer side of the rotor, multiple toothed shoe sections of the stator are circumferentially connected to the inner wall of the yoke along the motor's rotation axis. Since the ratio of the number of toothed shoe sections to the number of permanent magnets affects the rotor's magnetomotive force, a ratio that is too large or too small leads to a decrease in the motor's air gap flux, thus reducing motor efficiency. Therefore, by setting the ratio of the number of toothed shoe sections to the number of permanent magnets within the range of 0.8 to 0.9, the motor's air gap flux can be increased, thereby improving motor efficiency. While maintaining motor efficiency comparable to or close to that of motors in related technologies, the stator's stack thickness can be shortened. A reduced stator stack thickness also reduces the rotor stack thickness, thus decreasing the motor's size. Similarly, the ratio of the maximum length of the permanent magnets to the diameter of the rotor's minimum circumscribed circle also affects the motor's air gap flux; a ratio that is too large or too small will result in a decrease in air gap flux. By rationally designing the ratio of the maximum length of the permanent magnet to the diameter of the minimum circumscribed circle of the rotor within the range of 0.2 to 0.25, the air gap flux of the motor can be increased, the stack thickness of the stator and rotor can be shortened, the volume of the motor can be further reduced, the structure of the motor can be made more compact, which is conducive to the miniaturization design of the motor and thus improves the power density.

[0012] According to some embodiments of this application, the number of permanent magnets is 14, and a winding groove is formed between adjacent toothed shoe portions, the number of which is 12.

[0013] According to some embodiments of this application, the minimum width of the permanent magnet along the circumferential direction of the motor is W1, which satisfies: 0.35≤W1 / L≤0.45.

[0014] According to some embodiments of this application, the toothed shoe portion includes a tooth portion and a shoe portion. One end of the tooth portion is connected to the yoke portion, and the other end of the tooth portion is connected to the shoe portion. The minimum width of the tooth portion along the circumferential direction of the motor is W3, and the height of the tooth portion along the axial direction of the motor is H1. The tooth cross-sectional area S1 is defined as W3*H1. The height of the permanent magnet along the axial direction of the motor is H2, and the magnetic flux area S2 is defined as L*H2, satisfying: 0.2≤S1 / S2≤0.3.

[0015] According to some embodiments of this application, the mounting groove has a slot at one end away from the rotation axis. Along the circumference of the motor, the minimum width of the slot is W2, and the minimum width of the permanent magnet is W1, satisfying: 0.5≤W2 / W1≤0.6.

[0016] According to some embodiments of this application, the fan-shaped portion has protrusions on both sides of the end away from the rotation axis, the protrusions extend circumferentially along the motor, and the slot is formed between the two protrusions located in the same mounting groove.

[0017] According to some embodiments of this application, on a projection plane perpendicular to the rotation axis of the rotor, the orthographic projection of the stator is a regular polygon, and the number of sides of the regular polygon is equal to the number of the toothed shoe portions.

[0018] According to some embodiments of this application, the diameter of the largest inscribed circle of the regular polygon is D2, and the diameter of the largest inscribed circle of the stator's orthographic projection is D3, satisfying: 0.55≤D3 / D2≤0.65.

[0019] According to some embodiments of this application, the motor further includes a winding, and a winding groove is formed between adjacent toothed shoe portions, the winding being wound around the toothed shoe portion through the winding groove.

[0020] The household appliance according to a second aspect of this application includes the motor described in the above embodiments.

[0021] The household appliances according to the embodiments of this application have at least the following beneficial effects:

[0022] In the motor employing the first aspect embodiment, the permanent magnets of the rotor are positioned within mounting slots between adjacent sector sections. The stator is fitted onto the outer side of the rotor, and multiple toothed shoe sections of the stator are circumferentially connected to the inner wall of the yoke along the rotation axis of the motor. Since the ratio of the number of toothed shoe sections to the number of permanent magnets affects the magnetomotive force of the rotor, a ratio that is too large or too small leads to a decrease in the air gap flux of the motor, resulting in reduced motor efficiency. Therefore, by setting the ratio of the number of toothed shoe sections to the number of permanent magnets within the range of 0.8 to 0.9, the air gap flux of the motor can be increased, thereby improving the motor efficiency. While ensuring that the motor efficiency is the same as or close to that of motors in related technologies, the stator stack thickness can be shortened. A reduction in the stator stack thickness also reduces the rotor stack thickness, thus reducing the motor's volume. The ratio of the maximum length of the permanent magnets to the diameter of the minimum circumscribed circle of the rotor also affects the air gap flux of the motor; a ratio that is too large or too small will lead to a decrease in the air gap flux. By rationally designing the ratio of the maximum length of the permanent magnet to the diameter of the minimum circumscribed circle of the rotor within the range of 0.2 to 0.25, the air gap flux of the motor can be increased, the stack thickness of the stator and rotor can be shortened, the volume of the motor can be further reduced, the structure of the motor can be made more compact, which is conducive to the miniaturization design of the motor and thus improves the power density.

[0023] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0024] The present application will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0025] Figure 1 is a schematic diagram of the structure of a motor according to an embodiment of this application;

[0026] Figure 2 is a schematic diagram of the rotor structure according to an embodiment of this application, wherein one of the permanent magnets is separated from the mounting slot;

[0027] Figure 3 is a schematic diagram of the stator structure according to an embodiment of this application;

[0028] Figure 4 is a schematic diagram of the structure of a permanent magnet according to an embodiment of this application;

[0029] Figure 5 is a schematic diagram showing the effect of different values ​​of L / D1 on motor efficiency in one embodiment of this application;

[0030] Figure 6 is a schematic diagram showing the effect of different values ​​of W1 / L on the efficiency and demagnetizing current of the motor according to an embodiment of this application.

[0031] Figure 7 is a schematic diagram showing the effect of different values ​​of S1 / S2 on motor efficiency in one embodiment of this application;

[0032] Figure 8 is a schematic diagram of the effect of different values ​​of W2 / W1 on the back EMF and cogging torque of the motor according to an embodiment of this application.

[0033] Figure 9 is a schematic diagram showing the effect of different values ​​of D3 / D2 on motor efficiency in one embodiment of this application.

[0034] Reference numerals: Rotor 100; Sector 110; Mounting slot 111; Protrusion 112; Slot 113; Permanent magnet 120; Stator 200; Yoke 210; Gear shoe 220; Gear 221; Shoe 222; Winding slot 230; Winding 240. Detailed Implementation

[0035] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0036] In the description of this application, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0037] In the description of this application, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0038] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0039] Referring to Figures 1, 2, and 3, a motor according to an embodiment of this application can be used in household appliances such as air conditioners, refrigerators, fans, and exhaust fans. The motor of this embodiment includes a rotor 100 and a stator 200. The rotor 100 includes multiple sector-shaped portions 110 and multiple permanent magnets 120. The multiple sector-shaped portions 110 are arranged around the rotation axis of the motor, and mounting grooves 111 are formed between adjacent sector-shaped portions 110. The multiple permanent magnets 120 are correspondingly mounted in the multiple mounting grooves 111. The stator 200 is sleeved on the outside of the rotor 100. The stator 200 includes a yoke 210 and multiple toothed shoe portions 220. The yoke 210 is annular, and the multiple toothed shoe portions 220 are circumferentially connected to the inner wall of the yoke 210 along the rotation axis of the motor. Winding grooves 230 are formed between adjacent toothed shoe portions 220, and the windings 240 of the stator 200 are wound around the toothed shoe portions 220 through the winding grooves 230. The magnetic field generated by the permanent magnet 120 can interact with the magnetic field generated by the winding 240, thereby driving the rotor 100 to rotate relative to the stator 200.

[0040] The number of permanent magnets 120 is X, and the number of toothed shoe parts 220 is Y, satisfying: 0.8≤Y / X≤0.9. For example, the value of Y / X can be 0.8, 0.81, 0.83, 0.85, 0.87, 0.88, or 0.9. The diameter of the minimum circumscribed circle of the rotor 100 is D1, and the maximum length of the permanent magnet 120 along the radial direction of the motor is L, satisfying: 0.2≤L / D1≤0.25. For example, the value of L / D1 can be 0.2, 0.21, 0.22, 0.23, 0.24, or 0.25.

[0041] Understandably, the ratio of the number of toothed shoe sections 220 to the number of permanent magnets 120 affects the magnetomotive force (MOF) of the rotor 100. When Y / X is less than 0.8, the number of toothed shoe sections 220 is relatively small, while the number of permanent magnets 120 is relatively large. This means the number of motor windings 240 decreases, the winding coefficient decreases, and although the number of permanent magnets 120 is large, the number of windings 240 that can cooperate with each other is too small, resulting in a decrease in the magnetic field utilization rate of the permanent magnets 120, which in turn leads to a decrease in air gap flux and magnetomotive force. When Y / X is greater than 0.9, the number of permanent magnets 120 is relatively small, while the number of toothed shoe sections 220 is relatively large. Although the number of windings 240 increases, the number of permanent magnets 120 decreases, resulting in a decrease in the magnetic field utilization rate of the windings 240, which in turn leads to a decrease in air gap flux and magnetomotive force. Therefore, by setting the ratio of the number of toothed shoe sections 220 to the number of permanent magnets 120 within the range of 0.8 to 0.9, the air gap flux of the motor can be increased, thereby improving the efficiency of the motor. If the motor efficiency is the same as or close to that of motors in related technologies, the stacking thickness of stator 200 can be shortened. When the stacking thickness of stator 200 is reduced, the stacking thickness of rotor 100 will also be reduced, thus reducing the size of the motor.

[0042] The ratio of the maximum length of the permanent magnet 120 to the diameter of the minimum circumscribed circle of the rotor 100 also affects the air gap flux of the motor. For example, referring to Figure 5, the horizontal axis represents different values ​​of L / D1, and the vertical axis represents the motor efficiency. Figure 5 shows that as the value of L / D1 gradually increases within the range of 0.05 to 0.4, the motor efficiency first increases and then decreases. The curves in Figure 5 are explained as follows:

[0043] When L / D1 is less than 0.2, the maximum length of the permanent magnet 120 is short, the diameter of the minimum circumscribed circle of the rotor 100 is large, the space utilization of the mounting slot 111 is low, and the volume of the permanent magnet 120 is small. This results in lower magnetic energy provided by the permanent magnet 120, reduced air gap flux, decreased motor output capacity, and lower efficiency. When L / D1 is greater than 0.4, the maximum length of the permanent magnet 120 is long, and the diameter of the minimum circumscribed circle of the rotor 100 is small. This results in a smaller radial dimension of the rotor 100. Limited by the length of the mounting slot 111, the volume of the permanent magnet 120 cannot be effectively increased but will instead shorten, leading to a decrease in the magnetic energy provided by the permanent magnet 120, a decrease in air gap flux, decreased motor output capacity, and lower efficiency. Therefore, both excessively large and small L / D1 ratios lead to reduced motor efficiency. By limiting the ratio of the maximum length of the permanent magnet 120 to the diameter of the minimum circumscribed circle of the rotor 100 to the range of 0.2 to 0.25, the air gap flux of the motor can be increased, thereby improving the motor efficiency. When the motor's performance is sufficient, the size of the motor can be further reduced by shortening the stack thickness of the stator 200 and rotor 100 and adopting a scheme to reduce excess efficiency. This makes the motor structure more compact, which is conducive to the miniaturization design of the motor and thus improves the power density.

[0044] It should be noted that the value of L / D1 ranges from 0.2 to 0.25, provided that the ratio of the number of toothed shoe portions 220 to the number of permanent magnets 120 is between 0.8 and 0.9, for example, the number of permanent magnets 120 is 14 and the number of winding slots 230 is 12. Under this condition, the permanent magnets 120 have a larger number of poles, which can provide a larger air gap magnetic flux. Furthermore, a reasonable design of the L / D1 ratio range can further improve the efficiency of the motor. When the motor efficiency already meets the corresponding usage requirements and has a significant margin, the efficiency can be appropriately sacrificed by shortening the stacking thickness of the stator 200 and the rotor 100, allowing for a reduction in the axial size of the motor, which is beneficial for miniaturization. Therefore, the motor in this embodiment achieves miniaturization while still meeting the corresponding usage requirements in terms of operating efficiency.

[0045] Referring to Figure 2, in the embodiment of this application, the minimum width of the permanent magnet 120 along the circumference of the motor is W1, satisfying: 0.35 ≤ W1 / L ≤ 0.45. For example, the value of W1 / L can be 0.35, 0.36, 0.37, 0.39, 0.4, 0.42, or 0.45. Referring to Figure 6, the horizontal axis in Figure 6 represents different values ​​of W1 / L, the vertical axis on the left represents the motor efficiency, and the vertical axis on the right represents the motor demagnetizing current. The curves with squares in Figure 6 represent the trend of motor efficiency, and the curves with dots represent the trend of demagnetizing current. As can be seen from Figure 6, as the value of W1 / L gradually increases within the range of 0.2 to 0.6, the motor efficiency first increases and then decreases, while the demagnetizing current gradually increases. The curves in Figure 6 are explained as follows:

[0046] When W1 / L is less than 0.35, the permanent magnet 120 is too narrow and too long, leading to an increased leakage flux coefficient, poor demagnetization resistance of the motor, lower demagnetization current, and reduced motor efficiency. When W1 / L is greater than 0.45, the permanent magnet 120 is too narrow and too short, resulting in insufficient installation space and uneven magnetic field distribution, further reducing motor efficiency. Therefore, by appropriately designing the W1 / L ratio to be within the range of 0.35 to 0.45, it is possible to increase the motor's demagnetization resistance, improve the demagnetization current, and simultaneously enhance motor efficiency.

[0047] Referring to Figures 2, 3, and 4, in the embodiments of this application, the toothed shoe portion 220 includes a tooth portion 221 and a shoe portion 222. One end of the tooth portion 221 is connected to the inner sidewall of the yoke portion 210, and the other end of the tooth portion 221 is connected to the yoke portion 210. Along the circumferential direction of the motor, the minimum width of the tooth portion 221 is W3; along the axial direction of the motor, the maximum height of the tooth portion 221 is H1, and the tooth cross-sectional area S1 is defined as W3 * H1. The height of the permanent magnet 120 along the axial direction of the motor is H2, and the magnetic flux area S2 is defined as L * H2, satisfying: 0.2 ≤ S1 / S2 ≤ 0.3. For example, the values ​​of S1 / S2 can be 0.2, 0.22, 0.24, 0.26, 0.28, 0.3, etc. Referring to Figure 7, the horizontal axis in Figure 7 represents different values ​​of S1 / S2, and the vertical axis represents the efficiency of the motor. As shown in Figure 7, as the value of S1 / S2 gradually increases within the range of 0.05 to 0.45, the motor efficiency first increases and then decreases. The curves in Figure 7 are explained as follows:

[0048] It should be noted that the sector 110 and the toothed shoe 220 are typically made of silicon steel, thus possessing excellent magnetic permeability and capable of guiding the direction of the magnetic circuit. The magnetic field generated by the permanent magnet 120 typically passes through the sector 110 and enters the air gap, then from the air gap into the toothed shoe 220, and then flows back from the adjacent toothed shoe 220 to the air gap, before entering the adjacent sector 110 and returning to the permanent magnet 120, thereby forming a complete loop.

[0049] Therefore, when S1 / S2 is less than 0.2, the tooth cross-sectional area is too small and the magnetic flux area is too large, making the tooth section 221 prone to oversaturation. This results in some magnetic flux not being able to pass through, meaning some magnetic fields cannot be effectively utilized, wasting magnetomotive force and reducing the motor's power density and efficiency. When S1 / S2 is greater than 0.3, the tooth cross-sectional area is too large and the magnetic flux area is too small. Increasing the tooth cross-sectional area requires reducing the area of ​​the winding slot 230. However, an excessively large tooth cross-sectional area leads to low magnetic circuit saturation in the tooth section 221, wasting the area of ​​the winding slot 230, and reducing the number of windings. This affects the magnetic field strength generated by the winding 240, further reducing the motor's efficiency.

[0050] Therefore, by rationally designing the S1 / S2 ratio to be within the range of 0.2 to 0.3, the occurrence of magnetic circuit oversaturation or low magnetic circuit saturation can be reduced, thereby improving magnetic flux utilization and thus increasing the motor's operating efficiency. When the motor's efficiency already meets the corresponding usage requirements and has a significant margin, the efficiency can be appropriately sacrificed by shortening the stacking thickness of the stator 200 and the rotor 100, allowing for a reduction in the motor's axial dimensions and facilitating miniaturization. Therefore, the motor in this embodiment achieves miniaturization while still meeting the corresponding usage requirements in terms of operating efficiency.

[0051] Referring to FIG2, in the embodiment of this application, a slot 113 is formed at the end of the mounting groove 111 away from the rotation axis of the motor. For example, both sides of the end of the sector 110 away from the rotation axis are provided with protrusions 112, which extend circumferentially along the motor. A slot 113 is formed between two protrusions 112 located in the same mounting groove 111. The protrusions 112 are used to restrict the permanent magnet 120 from detaching from the mounting groove 111, thereby improving the stability and reliability of the permanent magnet 120 connection. As an alternative embodiment, each sector 110 may also be provided with only one protrusion 112, and each mounting groove 111 may have one protrusion 112, depending on the actual situation.

[0052] Referring to Figure 2, in the embodiment of this application, along the circumference of the motor, the minimum width of the slot 113 is W2, and the minimum width of the permanent magnet 120 is W1, satisfying: 0.5 ≤ W2 / W1 ≤ 0.6. For example, the value of W2 / W1 can be 0.52, 0.54, 0.55, 0.56, 0.58, 0.6, etc. Referring to Figure 8, the horizontal axis in Figure 8 represents different values ​​of W2 / W1, the vertical axis on the left represents the back EMF of the motor, and the vertical axis on the right represents the cogging torque of the motor. The curves with triangular symbols in Figure 8 represent the trend of the back EMF of the motor, and the curves with diamond symbols represent the trend of the cogging torque. As can be seen from Figure 8, as the value of W2 / W1 gradually increases within the range of 0.35 to 0.75, both the back EMF and the cogging torque of the motor gradually increase. The curves in Figure 8 are explained as follows:

[0053] When W2 / W1 is less than 0.5, the minimum width of slot 113 is small, and the minimum width of permanent magnet 120 is large, resulting in a smaller cogging torque. However, the protrusion 112 protrudes a long distance, making it prone to magnetic leakage, which reduces the magnetic field utilization of permanent magnet 120 and consequently lowers the motor's back electromotive force (EMF). It should be noted that back EMF refers to the electromotive force generated when the armature coil cuts magnetic lines of force during motor rotation. The direction of the EMF is opposite to the power supply voltage, hence the name back EMF. Cogging torque refers to the periodic torque fluctuations and vibrations generated during motor operation, resulting from the interaction between the magnetic field of permanent magnet 120 on rotor 100 and the cogging of stator 200, producing torque in the circumferential direction. This torque fluctuation reduces control accuracy and increases starting resistance under low-speed control conditions, leading to unstable motor operation. When W2 / W1 is greater than 0.6, the minimum width of slot 113 is larger and the minimum width of permanent magnet 120 is smaller. Although leakage flux is reduced and back electromotive force is increased, cogging torque will also increase, resulting in unstable motor operation and greater noise.

[0054] By rationally designing the W2 / W1 ratio to be within the range of 0.5 to 0.6, the cogging torque can be controlled within a reasonable range, thereby improving the problem of excessive motor noise and increasing the motor's back EMF, thus improving motor efficiency. Therefore, by sacrificing the efficiency margin of the motor to shorten the stacking thickness of the stator 200 and rotor 100, the motor can be miniaturized while still meeting the corresponding application requirements.

[0055] Referring to Figure 3, in the embodiment of this application, the orthographic projection of the stator 200 on the projection plane perpendicular to the rotation axis of the rotor 100 is a regular polygon, and the number of sides of the regular polygon is equal to the number of toothed shoe portions 220. It can be understood that the laminations of the stator 200 are arranged in a straight strip shape during stamping, and then the laminations are bent into rings, with multiple laminations stacked axially to form the stator core. Compared to directly stamping ring-shaped laminations, producing laminations using straight strips allows for a denser material arrangement and improves material utilization. Setting the orthographic projection of the stator 200 as a regular polygon, with the number of sides equal to the number of toothed shoe portions 220, makes the overall structure of the stator 200 symmetrical and uniform, facilitating installation.

[0056] Referring again to Figure 3, in this embodiment, the diameter of the largest inscribed circle of the regular polygon is D2, and the diameter of the largest inscribed circle of the stator 200's orthographic projection is D3, satisfying: 0.55 ≤ D3 / D2 ≤ 0.65. For example, the value of D3 / D2 can be 0.55, 0.56, 0.58, 0.59, 0.61, 0.63, or 0.65. Referring to Figure 9, the horizontal axis in Figure 9 represents different values ​​of D3 / D2, and the vertical axis represents the motor efficiency. As can be seen from Figure 9, as the value of D3 / D2 gradually increases within the range of 0.4 to 0.8, the motor efficiency first increases and then decreases. The curve in Figure 9 is explained as follows:

[0057] When D3 / D2 is less than 0.55 (i.e., D3 is small and D2 is large), the space enclosed in the middle of the stator 200 is small, requiring a corresponding reduction in the radial dimension of the rotor 100. The volume of the permanent magnet 120 also decreases accordingly, leading to a reduction in the magnetic load on the rotor 100 and a decrease in motor efficiency. When D3 / D2 is greater than 0.65 (i.e., D3 is large and D2 is small), although the space enclosed in the middle of the stator 200 is large and the radial dimension of the rotor 100 increases, the area of ​​the winding slot 230 decreases, and the volume of the winding 240 decreases, resulting in increased copper losses and a similar decrease in motor efficiency.

[0058] Therefore, by reasonably designing the values ​​of D3 / D2 to be within the range of 0.55 to 0.65, the radial dimension of the rotor 100 can be kept within a suitable range, increasing the magnetic load; at the same time, the volume of the winding 240 can also be kept within a suitable size, reducing copper losses, thereby improving the motor's operating efficiency. When the motor's efficiency already meets the corresponding usage requirements and has a large margin, the efficiency of the motor can be appropriately sacrificed by shortening the stacking thickness of the stator 200 and the rotor 100, so that the axial dimension of the motor can be reduced, which is beneficial to the miniaturization design of the motor. Therefore, the motor in this embodiment achieves miniaturization while still meeting the corresponding usage requirements in terms of operating efficiency.

[0059] This application discloses an embodiment of a household appliance, which may include an air conditioner, refrigerator, fan, exhaust fan, etc., and includes the motor described in the above embodiments. The household appliance of this application uses the motor described in the above embodiments. The motor has permanent magnets 120 of the rotor 100 located in mounting grooves 111 between adjacent sector portions 110. The stator 200 is sleeved on the outside of the rotor 100, and multiple toothed shoe portions 220 of the stator 200 are circumferentially connected to the inner wall of the yoke portion 210 along the rotation axis of the motor. Since the ratio of the number of toothed shoe portions 220 to the number of permanent magnets 120 affects the magnetomotive force of the rotor 100, a ratio that is too large or too small will reduce the air gap magnetic flux of the motor, thus reducing the efficiency of the motor. Therefore, by setting the ratio of the number of toothed shoe portions 220 to the number of permanent magnets 120 to be in the range of 0.8 to 0.9, the air gap magnetic flux of the motor can be increased, thereby improving the efficiency of the motor. While maintaining motor efficiency comparable to or close to that of motors in related technologies, the thickness of the stator 200 can be shortened. Reducing the stator 200 thickness also reduces the rotor 100 thickness, thus decreasing the motor's overall size. The ratio of the maximum length of the permanent magnet 120 to the diameter of the minimum circumscribed circle of the rotor 100 also affects the motor's air gap flux; a ratio that is too large or too small will decrease the air gap flux. By rationally designing the ratio of the maximum length of the permanent magnet 120 to the diameter of the minimum circumscribed circle of the rotor 100 within the range of 0.2 to 0.25, the motor's air gap flux can be increased, the thickness of the stator 200 and rotor 100 shortened, and the motor's size further reduced. This results in a more compact motor structure, facilitating miniaturization and ultimately increasing power density.

[0060] Since the household appliance adopts all the technical solutions of the motor in the above embodiments, it has at least all the beneficial effects brought about by the technical solutions in the above embodiments, which will not be repeated here.

[0061] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application.

Claims

1. An electric motor, including: The rotor includes multiple sector-shaped sections and multiple permanent magnets. The sector-shaped sections are arranged around the rotation axis of the motor, and mounting slots are formed between adjacent sector-shaped sections. The multiple permanent magnets are correspondingly disposed within the mounting slots. A stator is sleeved on the outside of the rotor. The stator includes a yoke and a plurality of toothed shoe portions, which are circumferentially spaced and connected to the inner wall of the yoke along the axis of rotation. Wherein, the number of permanent magnets is X, the number of toothed shoe parts is Y, satisfying: 0.8≤Y / X≤0.9; the diameter of the minimum circumscribed circle of the rotor is D1, and the maximum length of the permanent magnet along the radial direction of the motor is L, satisfying: 0.2≤L / D1≤0.

25.

2. The motor according to claim 1, wherein, The number of permanent magnets is 14, and a winding groove is formed between adjacent toothed shoe portions, the number of which is 12.

3. The motor according to claim 1 or 2, wherein, The minimum width of the permanent magnet along the circumference of the motor is W1, which satisfies: 0.35≤W1 / L≤0.

45.

4. The motor according to any one of claims 1 to 3, wherein, The toothed shoe portion includes a tooth portion and a shoe portion. One end of the tooth portion is connected to the yoke portion, and the other end of the tooth portion is connected to the shoe portion. The minimum width of the tooth portion along the circumferential direction of the motor is W3, and the height of the tooth portion along the axial direction of the motor is H1. The tooth cross-sectional area S1 is defined as W3*H1. The height of the permanent magnet along the axial direction of the motor is H2, and the magnetic flux area S2 is defined as L*H2, satisfying: 0.2≤S1 / S2≤0.

3.

5. The motor according to any one of claims 1 to 4, wherein, The mounting groove has a slot at one end away from the rotation axis. The minimum width of the slot along the circumference of the motor is W2, and the minimum width of the permanent magnet is W1, satisfying: 0.5≤W2 / W1≤0.

6.

6. The motor according to claim 5, wherein, Both sides of the fan-shaped portion away from the rotation axis are provided with protrusions, which extend along the circumference of the motor. The slot is formed between the two protrusions located in the same mounting groove.

7. The motor according to any one of claims 1 to 6, wherein, On a projection plane perpendicular to the rotation axis of the rotor, the orthographic projection of the stator is a regular polygon, and the number of sides of the regular polygon is equal to the number of the toothed shoe portions.

8. The motor according to claim 7, wherein, The diameter of the largest inscribed circle of the regular polygon is D2, and the diameter of the largest inscribed circle of the stator's orthographic projection is D3, satisfying: 0.55≤D3 / D2≤0.

65.

9. The motor according to any one of claims 1 to 8 further includes a winding, wherein a winding groove is formed between adjacent toothed shoe portions, and the winding is wound around the toothed shoe portion through the winding groove.

10. A household appliance, including a motor as claimed in any one of claims 1 to 9.

Images