Electric machine and household appliance

Abstract

This invention discloses an electric motor and a household appliance, belonging to the field of electric motor technology. The motor includes a stator and a rotor. The stator includes a stator core, which includes a yoke and multiple teeth. The teeth are arranged at intervals along the circumference of the stator core on the inner side of the yoke, defining a rotor hole. The rotor, located within the rotor hole, includes a rotor core and multiple magnets. The rotor core has multiple magnet slots, which are arranged at intervals along the circumference of the rotor core. Each magnet is installed in a corresponding magnet slot. The minimum inner diameter of the stator core is D1, the maximum radial dimension of the magnet along the rotor core is Lm, the maximum dimension along the magnetization direction is Hm, and the circumference is π, satisfying: 16 ≤ π*(D1-2*Lm) / Hm ≤ 19. The motor designed according to the above constraints has a high magnetic load. For the same volume, the motor of this invention effectively improves operating efficiency compared to existing motors.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a motor and a household appliance. Background Technology

[0002] Currently, household appliances typically use electric motors as drive units; for example, the fan in an air conditioner is driven by an electric motor. In related technologies, to reduce size and cost, the number of stator teeth and rotor magnets in the motor is reduced; however, this also reduces the motor's efficiency. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a motor that can reduce the size of the motor without reducing efficiency, thereby reducing the cost of the motor.

[0004] The present invention also provides a household appliance having the above-mentioned motor.

[0005] According to a first aspect of the present invention, an electric motor includes a stator and a rotor. The stator includes a stator core, the stator core including a yoke and a plurality of teeth. The plurality of teeth are arranged at intervals along the circumference of the stator core on the inner side of the yoke and define a rotor hole. The rotor is disposed in the rotor hole. The rotor includes a rotor core and a plurality of magnets. The rotor core has a plurality of magnet slots, the plurality of magnet slots are arranged at intervals along the circumference of the rotor core, and the plurality of magnets are respectively installed in the corresponding magnet slots. The minimum inner diameter of the stator core is D1, the maximum radial dimension of the magnet along the rotor core is Lm, the maximum circumferential dimension of the magnet along the rotor core is Hm, and the circumference is π, satisfying: 16≤π*(D1-2*Lm) / Hm≤19.

[0006] The motor according to the first aspect of the present invention has at least the following beneficial effects: Multiple teeth of the stator core are arranged at intervals along the circumference of the stator core on the inner side of the yoke, defining a rotor hole. The rotor is rotatably mounted in the rotor hole, and multiple magnets in the rotor are respectively installed in corresponding magnet slots. The minimum inner diameter of the stator core is D1, the maximum radial dimension of the magnet along the rotor core is Lm, and the maximum circumferential dimension of the magnet along the rotor core is Hm, satisfying 16≤π*(D1-2*Lm) / Hm≤19. This formula illustrates the relationship between the inner diameter of the stator core, the radial dimension of the magnet, and the magnetization dimension of the magnet. The motor designed according to the above constraints has the characteristic of high magnetic load. Under the same volume, the motor of the present invention has higher operating efficiency than the motor of the prior art, and at the same operating power, it is smaller in size, thereby reducing manufacturing costs. It balances efficiency and cost and can be applied to household appliances such as air conditioner fans, air conditioner compressors, refrigerator compressors, and drum washing machines.

[0007] According to some embodiments of the present invention, a stator slot is formed between two adjacent teeth, and each stator slot is provided with a slot opening communicating with the rotor hole. The width of the slot opening is S1, which satisfies: 0.0115 < S1 / (π*D1) < 0.0135.

[0008] According to some embodiments of the present invention, the maximum outer diameter of the stator core is D2, which satisfies: 0.60≤D1 / D2≤0.68.

[0009] According to some embodiments of the present invention, the maximum outer diameter of the stator core is greater than or equal to 80 mm and less than or equal to 100 mm.

[0010] According to some embodiments of the present invention, the end of the tooth portion away from the yoke portion is provided with a toothed shoe, and the end face of the toothed shoe facing the rotor core includes multiple segments of first arc surfaces. The multiple segments of first arc surfaces are connected sequentially along the circumference of the stator core. The minimum distance between the first arc surface and the circumcircle of the rotor core is L1, and the maximum distance is L2, satisfying: 1 < L2 / L1 < 2.5.

[0011] According to some embodiments of the present invention, an iron core unit is formed between adjacent magnet slots. Each iron core unit has a multiple second arc surface on its end face facing the stator iron core. The multiple second arc surfaces are connected sequentially along the circumference of the rotor iron core. The minimum distance between the second arc surface and the inscribed circle of the stator iron core is L3, and the maximum distance is L4, satisfying: 1 < L4 / L3 < 2.5.

[0012] According to some embodiments of the present invention, the outer contour of the stator core is a polygon, the number of sides of the polygon is the same as the number of teeth, and the sides of the polygon are arranged in a one-to-one correspondence with the teeth along the radial direction of the stator core.

[0013] According to some embodiments of the present invention, the number of teeth is greater than or equal to 12, and the number of poles of the rotor is greater than or equal to 14.

[0014] According to some embodiments of the present invention, a stator slot is formed between two adjacent teeth, each stator slot is provided with a slot opening communicating with the rotor hole, and the wall surface of the stator slot opposite to the slot opening is an arc surface or is composed of at least one section of plane.

[0015] According to some embodiments of the present invention, the height of the magnet is greater than or equal to the height of the rotor core along the axial direction of the rotor core.

[0016] According to some embodiments of the present invention, the cross-sectional shape of the magnet is square, trapezoidal, rhomboid or spindle-shaped.

[0017] A household appliance according to a second aspect of the present invention includes a motor according to a first aspect of the present invention.

[0018] The household appliance according to the second aspect of the present invention has at least the following beneficial effects: Because of the use of the aforementioned motors, household appliances can improve operating efficiency at the same cost and save on manufacturing costs, thus balancing efficiency and cost.

[0019] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is an axial schematic diagram of the motor in an embodiment of the present invention; Figure 2 This is an axial schematic diagram of the stator in an embodiment of the present invention; Figure 3 This is an axial schematic diagram of the stator core in an embodiment of the present invention; Figure 4 This is an axial schematic diagram of the rotor in an embodiment of the present invention; Figure 5 This is an axial schematic diagram of the rotor core in an embodiment of the present invention; Figure 6 This is an axial schematic diagram of the stacked laminations in an embodiment of the present invention; Figure 7 This is a schematic diagram of the core unit in an embodiment of the present invention; Figure 8 yes Figure 1 Enlarged structural diagram at point A; Figure 9 yes Figure 1 An enlarged structural schematic diagram of another embodiment at point A in the middle; Figure 10 This is a graph showing the changes in efficiency and inner magnetic bridge width as a function of π*(D1-2*Lm) / Hm in an embodiment of the present invention. Figure 11 This is a graph showing the change of cogging torque with the value of S1 / (π*D1) in an embodiment of the present invention.

[0021] Figure label: 10. Stator; 20. Rotor; 100. Stator core; 110. Yoke; 120. Tooth; 130. Tooth shoe; 131. First arc surface; 140. Rotor hole; 150. Stator slot; 151. Slot opening; 200. Stator winding; 300. Rotor core; 310. Rotor lamination; 311. Laminated lamination; 312. Left convex part; 313. Right convex part; 314. Inner convex part; 315. Positioning hole; 320. Magnet slot; 330. Core unit; 331. Second arc surface; 400. Magnet. Detailed Implementation

[0022] Embodiments of the present invention 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 the present invention, and should not be construed as limiting the present invention.

[0023] In the description of this invention, it should be understood that the terms "axial", "radial", "circumferential", "upper", "lower", "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 invention 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 limiting this invention.

[0024] In the description of this invention, the use of terms such as "first" and "second" is for the purpose of distinguishing technical features only, and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of the technical features indicated.

[0025] In the description of this invention, unless otherwise explicitly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are some embodiments of the present invention, not all embodiments.

[0027] Permanent magnet motors have been continuously developing towards miniaturization, low cost, and high efficiency. Currently, the pole-slot configuration of permanent magnet motors on the market is mainly 12 slots and 10 poles, resulting in severe homogenization. 12 slots refers to the number of slots on the inner circumferential surface of the stator core 100, and 10 poles refers to the number of magnets 400 being 12. This invention aims to provide a new slot-pole configuration structure, employing a 12-slot, 14-pole structure to reduce torque ripple.

[0028] Reference Figures 1 to 11 As shown, a first aspect of the present invention provides a motor that is applied to a household appliance, such as a refrigerator, an air conditioner, or a washing machine.

[0029] It is understood that in this embodiment, the motor includes a stator 10 and a rotor 20. The stator 10 includes a stator core 100 and a stator winding 200. The stator core 100 is arranged around the outer periphery of the rotor 20, and the stator winding 200 is wound on the teeth 120 of the stator core 100. Under the action of the alternating magnetic field generated by the stator winding 200, the rotor 20 can rotate around its own rotation axis.

[0030] The specific structure of the motor is described in detail below.

[0031] Reference Figure 1 As shown, it can be understood that the stator core 100 is one of the key components of the motor, and it is the core part of the stator 10 of the motor. The stator core 100 includes a yoke 110 and a plurality of teeth 120. The plurality of teeth 120 are arranged at intervals along the circumference of the stator core 100 on the inner side of the yoke 110, and the plurality of teeth 120 define the rotor hole 140.

[0032] Reference Figures 1 to 3As shown, a stator slot 150 is formed between two adjacent teeth 120. The stator slot 150 is used for winding the stator winding 200, and the teeth 120 provide mechanical support for the stator winding 200. The stator winding 200 is fixed in the stator slot 150 and wound on the teeth 120 to prevent it from shifting or being damaged due to vibration, centrifugal force, or other factors during motor operation.

[0033] The main function of the stator core 100 is to serve as part of the magnetic circuit, conducting the magnetic field. When current flows through the stator winding 200, an alternating magnetic field is generated. This magnetic field is conducted through the stator core 100, forming a closed magnetic circuit inside the motor. The stator core 100 conducts the magnetic field generated by the stator winding 200 into the air gap, where it interacts with the magnetic field of the rotor 20's magnet 400, thereby generating torque and driving the motor to rotate.

[0034] In some embodiments, the stator core 100 is typically made of stacked, mutually insulated silicon steel sheets, which are generally thin sheets with a thickness of 0.35 mm to 0.5 mm. The shape and size of these silicon steel sheets are determined according to the design requirements of the motor. For example, in a 12-slot motor, there are 12 stator slots 150 on the silicon steel sheets for winding the stator winding 200.

[0035] In some embodiments, the stator core 100 is manufactured by methods including full-circle stamping, segmented stacking followed by round assembly, and straight strip stamping followed by bending into a circle. Full-circle stamping involves stamping silicon steel sheets into a full-circle shape, then stacking multiple full-circle silicon steel sheets together to form the stator core 100. Segmented stacking followed by round assembly involves dividing the stator core 100 into several small blocks, each small block being formed by stacking multiple silicon steel sheets. These small blocks are then processed through welding and other processes to form a complete stator core 100. Straight strip stamping followed by bending into a circle involves stamping silicon steel sheets into straight strips, then bending the straight silicon steel sheets into a circle, and finally stacking multiple circular silicon steel sheets together to form the stator core 100.

[0036] Reference Figures 4 to 7 As shown, the rotor core 300 is circumferentially spaced with multiple core units 330. It is understood that in some embodiments, the multiple core units 330 are arranged around the rotation axis to form the entire rotor core 300. Adjacent core units 330 may be connected or disconnected, or some core units 330 may be connected while others are not. On a projection plane perpendicular to the rotation axis of the rotor core 300, the projection of the core units 330 is approximately fan-shaped. Viewed along a direction parallel to the rotation axis, the core units 330 may also be arranged at equal intervals, with each adjacent core unit 330 forming a magnet slot 320. Multiple magnets 400 correspond one-to-one with the multiple magnet slots 320, and the magnets 400 are installed in the magnet slots 320, thus embedding the magnets 400 within the rotor core 300.

[0037] Specifically, the rotor core 300 includes multiple rotor laminations 310, which are stacked sequentially along the axial direction of the rotor core 300, thereby forming the rotor core 300.

[0038] Reference Figures 4 to 7 As shown, it can be understood that this is to facilitate subsequent processing and manufacturing of the motor. In some embodiments, each rotor lamination 310 is provided with a positioning hole 315. During assembly, positioning pins pass through the positioning holes 315 of each rotor lamination 310 to fix the position of the rotor lamination 310, allowing multiple rotor laminations 310 to be positioned and stacked sequentially, thereby facilitating motor manufacturing. The shape of the positioning hole 315 can be one of a circle, rectangle, trapezoid, or polygon. In this embodiment, the positioning hole 315 is circular, and the inner wall of the positioning hole 315 is provided with a groove to facilitate quick positioning of the rotor lamination 310.

[0039] In some embodiments, the rotor core 300 is further provided with injection molding holes, which facilitate the injection molding of the rotor core 300, magnet 400, and shaft into a single unit. The gaps between the core units 330 in the rotor core 300, as well as the gaps between the rotor core 300 and the shaft, can be filled by injection molding material.

[0040] In some embodiments, the rotor core 300 is provided with polybutylene terephthalate (PBT) coated reinforcing holes, which are distributed on the contact surface between the magnet 400 and the magnet slot 320. Since the rotor 20 rotates at high speed during motor operation, the magnet 400 is subjected to various forces such as centrifugal force and vibration. Providing reinforcing holes on the contact surface between the magnet 400 and the magnet slot 320 allows the PBT material to better fill these areas, increasing the contact area and thus improving the fixation strength of the magnet 400 within the magnet slot 320.

[0041] Reference Figure 5 and Figure 6 As shown, it can be understood that the rotor laminations 310 are composed of multiple laminations 311 arranged at equal intervals around the rotation axis of the rotor core 300. The laminations 311 are provided with an inner protrusion 314 at one end of the radial direction close to the rotation axis, and a left protrusion 312 and a right protrusion 313 at the other end of the radial direction away from the rotation axis. The left protrusion 312 is located at the end line of the counterclockwise radial direction, and the right protrusion 313 is located at the end line of the clockwise radial direction.

[0042] Laminates 311 are stacked along the axial direction of rotor core 300 to form core unit 330. The left convex portion 312 and right convex portion 313 of all laminates 311 are stacked to form outer magnetic bridge. The inner convex portion 314 of all laminates 311 are stacked along the axial direction to form inner magnetic bridge. The inner magnetic bridge and all outer magnetic bridges are arranged opposite each other at both ends of the radial direction of core unit 330.

[0043] It is understood that both the outer and inner magnetic bridges are disconnected, meaning that there is no connection between all adjacent core units 330; each core unit 330 is an independent unit. In some other embodiments, the core units 330 may be connected to each other to maintain the integrity of the rotor core 300.

[0044] An installation space, called a magnet slot 320, is formed between the two opposing walls of two adjacent core units 330. On a projection plane perpendicular to the rotation axis of the rotor core 300, the projection of the magnet slot 320 is approximately rectangular. Two inner magnetic bridges exist at the radial end of the magnet slot 320 closest to the central axis, and an outer magnetic bridge exists at the radial end of the magnet slot 320 furthest from the central axis.

[0045] Reference Figure 4 and Figure 5 As shown, in this embodiment, the 14 core units 330 can collectively define 14 magnet slots 320, so that the motor having the rotor core 300 needs to be equipped with 14 magnets 400, and the 14 magnets 400 are arranged one-to-one in the 14 magnet slots 320. In another embodiment, there may be a gap between the magnets 400 and the core units 330, and other materials may be filled between them, so that the relative positions of the magnets 400 are fixed, or the relative positions of the magnets 400 and the core units 330 are fixed.

[0046] For example, see Figure 4 The maximum dimension of magnet 400 along the radial direction of the motor can correspond to the maximum dimension of magnet slot 320 along the radial direction of the motor, so that the inner and outer magnetic bridges can block magnet 400 and prevent magnet 400 from being thrown out of magnet slot 320 when the motor rotates.

[0047] It is understandable that, viewed along the axial direction of the rotor core 300, the cross-sectional shape of the magnet 400 can be square, trapezoidal, or spindle-shaped, and the corresponding magnet slot 320 should also be rectangular, trapezoidal, or spindle-shaped. In this embodiment, both the magnet 400 and the magnet slot 320 are rectangular. Compared with some irregularly shaped magnets 400, rectangular magnets are easier to process and manufacture, and have lower costs.

[0048] Reference Figures 1 to 4As shown, the minimum inner diameter of the stator core 100 is D1, the maximum radial dimension of the magnet 400 along the rotor core 300 is Lm, and the maximum dimension of the magnet 400 along the magnetization direction is Hm. The circumference is π, satisfying: 16 ≤ π*(D1 - 2*Lm) / Hm ≤ 19. The above formula constrains the relationship between the inner diameter D1 of the stator 100, the radial dimension Lm of the magnet 400 along the rotor core 300, and the dimension Hm of the magnet 400 along the magnetization direction. Motors designed according to this formula have a higher magnetic load. Magnetic load refers to the magnitude of the magnetic flux in the air gap of the motor, a key parameter in motor design and performance evaluation, closely related to many performance characteristics such as electromagnetic torque, power, and efficiency. Increasing the magnetic load of the motor can effectively increase the electromagnetic torque, which is very important for home appliance applications requiring increased torque output.

[0049] It should be noted that, referring to Figure 3 As shown, in this embodiment, the minimum inner diameter of the stator core 100 can be understood as the diameter of the minimum inscribed circle of the stator core 100. (Refer to...) Figure 4 As shown, in this embodiment, the magnetization direction of the magnet 400 is the circumferential direction of the rotor core 300. This magnetization direction is perpendicular to the direction of the rotor core 300. The maximum radial dimension of the magnet 400 along the rotor core 300 can be understood as the maximum width dimension of the magnet 400, and the maximum circumferential dimension of the magnet 400 along the rotor core 300 can be understood as the maximum thickness dimension of the magnet 400.

[0050] Understandably, a motor designed according to the above formula can reduce its size without sacrificing efficiency, thereby lowering the motor's cost. (Refer to...) Figure 10 As shown, the efficiency gradually decreases with increasing π*(D1-2*Lm) / Hm. When π*(D1-2*Lm) / Hm increases from 16 to 19, the efficiency drops from 81.2% to 80.4%. Conversely, the width of the inner magnetic bridge gradually increases with increasing π*(D1-2*Lm) / Hm. When π*(D1-2*Lm) / Hm increases from 16 to 19, the width of the inner magnetic bridge increases from 0.3 mm to 1.2 mm. From the perspective of motor efficiency, a smaller value of π*(D1-2*Lm) / Hm indicates higher motor efficiency. However, as the value of π*(D1-2*Lm) / Hm decreases, the width of the inner magnetic bridge also gradually decreases, significantly reducing manufacturability.

[0051] It is understandable that π*(D1-2*Lm) represents the circumference of the inner diameter of rotor 20. If the inner diameter of rotor 20 remains unchanged, π*(D1-2*Lm) / Hm needs to be reduced, and the corresponding value of Hm needs to be increased. That is, the maximum dimension of magnet 400 in the magnetization direction becomes larger, magnet 400 becomes wider, and the space left for the inner magnetic bridge of rotor core 300 will become smaller, that is, the width of the inner magnetic bridge decreases.

[0052] Reference Figure 10 As shown, in order to balance motor efficiency and manufacturability, while improving motor efficiency, the width of the inner magnetic bridge should be easy to manufacture. Therefore, the value of π*(D1-2*Lm) / Hm should be between 16 and 19. For example, the value of π*(D1-2*Lm) / Hm can be 16, 17, 18, 19, etc., depending on the specific situation.

[0053] To illustrate with a specific example, the minimum inner diameter D1 of the stator core 100 is 57mm, the cross-sectional shape of the magnet 400 is rectangular, the maximum dimension Hm of the magnet 400 in the magnetization direction is 5mm, and the radial dimension Lm of the magnet 400 is 15.25mm. At this time, the value of π*(D1-2*Lm) / Hm is 16.642, which meets the numerical range of the formula 16≤π*(D1-2*Lm) / Hm≤19.

[0054] Reference Figures 1 to 3 As shown, a stator slot 150 is formed between two adjacent teeth 120. The stator slot 150 has a slot opening 151 communicating with the rotor hole 140. The width of the slot opening 151 is S1. The width S1 of the slot opening 151 and the inner diameter D1 of the stator core 100 satisfy the following relationship: 0.0115 < S1 / (π*D1) < 0.0135. The above relationship defines the relationship between the width S1 of the slot opening 151 and the inner diameter of the stator core 100. (π*D1) represents the circumference of the inner circle of the stator core 100. The ratio of the width S1 of the slot opening 151 of the stator core 100 to the circumference of the inner circle of the stator core 100 is between 0.0115 and 0.0135.

[0055] It should be noted that cogging torque is the torque generated by the interaction between the magnet 400 and the stator core 100 when the permanent magnet motor winding is not energized. It is caused by the tangential component of the interaction force between the magnet 400 and the armature teeth. Cogging torque will cause the motor to vibrate and generate noise, resulting in speed fluctuations, which will affect the smooth operation and performance of the motor.

[0056] Reference Figure 11 As shown, Figure 11 The graph shows the variation of cogging torque as a function of S1 / (π*D1), from... Figure 11 It can be seen that when S1 / (π*D1) is between 0.009 and 0.013, the cogging torque is inversely proportional to S1 / (π*D1); when S1 / (π*D1) is between 0.013 and 0.017, the cogging torque is directly proportional to S1 / (π*D1). Based on this, in this embodiment of the invention, the value of S1 / (π*D1) is limited to greater than 0.0115 and less than 0.0135. At this value, the cogging torque is always less than 2 mN·m, effectively reducing the cogging torque and thus lowering the noise during motor operation.

[0057] In this embodiment, the width of the slot 151 of the stator slot 150 is 2.2mm, and the inner diameter D1 of the stator core 100 is 57mm. At this time, the value of S1 / (π*D1) is 0.0123, which conforms to the relationship 0.0115<S1 / (π*D1)<0.0135. At this time, the cogging torque is 1mN·m, the cogging torque is effectively reduced, and the motor noise is effectively suppressed.

[0058] In some embodiments, the maximum outer diameter of the stator core 100 is greater than or equal to 80 mm and less than or equal to 100 mm. For example, the maximum outer diameter of the stator core 100 can be 80 mm, 85 mm, 90 mm, 100 mm, etc. This setting can limit the installation size and power rating of the motor, making the motor suitable for scenarios with requirements for installation space and power output. During motor operation, the current flowing through the stator winding 200 generates electromagnetic forces, which act on the stator core 100. Sufficient outer diameter ensures that the stator core 100 has sufficient mechanical strength to resist these forces, preventing deformation of the stator core 100 and thus ensuring the uniformity of the air gap magnetic field of the motor. Within this outer diameter range, the stator core 100 can better cooperate with the rotor 20 to construct a reasonable magnetic circuit. The magnetic field generated by the stator winding 200 can more effectively interact with the magnets 400 in the rotor core 300. A suitable outer diameter of the stator core 100 can make the magnetic field strength distribution more reasonable, reduce magnetic leakage, and thus improve the electromagnetic torque output of the motor.

[0059] In some embodiments, the ratio of the minimum inner diameter to the maximum outer diameter of the stator core 100 is greater than or equal to 0.60 and less than or equal to 0.68, i.e., satisfying: 0.60 ≤ D1 / D2 ≤ 0.68. This makes the dimensional design of the outer and inner diameters of the stator core 100 more reasonable. For a 12-slot, 14-pole motor, designing D1 / D2 within this range can improve motor performance while controlling costs, resulting in a higher cost-performance ratio. For a specific example, the inner diameter of the stator core 100 can be selected as 57mm, and the outer diameter as 88mm, with an inner diameter to outer diameter ratio of 0.64, satisfying the aforementioned constraint condition.

[0060] It should be noted that when the outer contour of the stator core 100 is not circular, the maximum diameter of the outer circumference of the stator core 100 is used as the outer diameter of the stator core 100, for example... Figure 3 In the embodiment shown, the outer contour of the stator core 100 is polygonal, with a maximum outer diameter of [missing information]. Figure 3 The diameter at the location marked D2 in the middle.

[0061] Reference Figure 1 and Figure 8As shown, the rotor 20 and stator 10 are combined to form a motor. The rotor 20 is rotatably mounted in the stator 10 of the motor, that is, the rotor 20 rotates within the stator 10. In the stator core 100, the end of the toothed portion 120 away from the yoke 110 is provided with a toothed shoe 130. The end face of the toothed shoe 130 facing the rotor core 300 includes multiple segments of first arc surfaces 131, which are connected sequentially along the circumference of the stator core 100. Let the minimum distance between the first arc surface 131 and the circumcircle of the rotor core 300 be L1, and the maximum distance between the first arc surface 131 and the circumcircle of the rotor core 300 be L2. L1 and L2 satisfy the constraint condition 1 < L2 / L1 < 2.5. It should be noted that the minimum distance L1 represents the minimum air gap between the circumcircle of the stator core 100 and the rotor core 300, and the maximum distance L2 represents the maximum air gap between the circumcircle of the stator core 100 and the rotor core 300. It should also be noted that the circumcircle of the rotor core 300 is a circle tangent to all points on the outer edge of the rotor core 300's outline.

[0062] When measuring L1 and L2, the distance between the contour line of the first arc surface 131 and the outer contour line of the rotor core 300 can be measured using vernier calipers. The reading at the position where the contour line of the first arc surface 131 and the outer contour line of the rotor core 300 are closest is L1, and the reading at the position where the contour line of the first arc surface 131 and the outer contour line of the rotor core 300 are farthest is L2. This constraint condition makes the outer contour line of each tooth shoe 130, i.e., the first arc surface segment, beveled. The first arc surface 131 is not a complete arc, and the radii of each arc segment are not equal. Bendling the outer contour line of the tooth shoe 130 can effectively adjust the air gap magnetic permeability distribution. After the air gap magnetic permeability distribution is changed, the distribution of the air gap magnetic field will also be more reasonable. The beveling treatment can make the air gap magnetic field closer to a sinusoidal distribution, which is beneficial to reducing the torque pulsation of the motor. The beveling treatment can change the shape and relative position relationship of the stator slot 150, making the interaction between the magnet 400 and the stator slot 150 smoother. From an energy perspective, cogging torque is generated by the change of magnetic field energy with the position of rotor 20. Arc cutting can adjust the distribution of magnetic field energy and reduce the gradient of magnetic field energy change with the position of rotor 20, thereby effectively reducing cogging torque.

[0063] Reference Figure 1 and Figure 9As shown, in the rotor core 300, core units 330 are formed between adjacent magnet slots 320. Each core unit 330 includes multiple second arc surfaces 331 on its end face facing the stator core 100. These multiple second arc surfaces 331 are connected sequentially along the circumference of the rotor core 300. Let the minimum distance between the second arc surface 331 and the inscribed circle of the stator core 100 be L3, and the maximum distance be L4, satisfying the constraint condition 1 < L4 / L3 < 2.5. It should be noted that the minimum distance L3 represents the minimum air gap between the inscribed circle of the stator core 100 and the rotor core 300, and the maximum distance L4 represents the maximum air gap between the inscribed circle of the stator core 100 and the rotor core 300. It should also be noted that the inscribed circle of the stator core 100 is a circle tangent to all points on the inner edge of the stator core 100.

[0064] When measuring L4 and L3, the reading at the point where the contour line of the second arc surface 331 of the core unit 330 is closest to the inner contour line of the stator core 100 is L3, and the reading at the point where the contour line of the second arc surface 331 of the core unit 330 is furthest from the inner contour line of the stator core 100 is L4. This constraint results in the outer contour line of each core unit 330 being curved, meaning the outer contour line of the core unit 330 is not a complete arc, and the radii of each arc segment are unequal. From an electromagnetic perspective, curving the outer contour line of the core unit 330 can adjust the intensity and direction distribution of the magnetic field of the rotor 20, making the magnetic field coupling more optimized. The curved rotor 20 allows the magnetic field generated by the magnet 400 to interact more effectively with the magnetic field generated by the stator winding 200, reducing magnetic field harmonics and thus improving torque pulsation. From an aerodynamic perspective, the arc-cut surface of the rotor 20 allows air to flow more smoothly, reducing air resistance and lowering losses during motor operation.

[0065] Reference Figures 1 to 3 As shown, the outer contour of the stator core 100 is a polygon, and the number of sides of the polygon is the same as the number of teeth 120. Along the radial direction of the stator core 100, the sides of the polygon correspond one-to-one with the teeth 120. Compared with a circle, the polygonal outer contour structure allows for more regular die arrangement when the stator core 100 is manufactured using a straight bar process, which can save stator die material and reduce costs.

[0066] In some embodiments, the number of teeth 120 is greater than or equal to 12, and the number of poles of the rotor 20 is greater than or equal to 14. (Refer to...) Figure 1In this embodiment, the number of teeth 120 is 12, and the number of poles of the rotor 20 is 14. That is, the motor in this embodiment is a 12-slot, 14-pole motor. Compared with the widely used 12-slot, 10-pole motor, the 12-slot, 14-pole motor can reduce torque ripple. It is understood that the more poles and slots there are, the smaller the cogging torque will be. Generally, increasing the least common multiple of the poles and slots can reduce the cogging torque.

[0067] In terms of torque, the 12-slot 14-pole motor, due to its higher pole count, can generate greater electromagnetic torque under the same stator size and current conditions. This allows the motor to output more power within a given size, making it more suitable for applications with high torque requirements, such as household appliances. The 12-slot 14-pole motor also has a lower manufacturing cost than the 12-slot 10-pole motor. For example, the axial length of a commercially available 12-slot 10-pole motor is 14.5mm, while the 12-slot 14-pole motor of this invention, with the same efficiency, has an axial length of only 12mm, reducing the motor size by 17%.

[0068] In some embodiments, the wall surface of the stator slot 150 opposite to the slot opening 151 is an arc surface or composed of at least one section of a plane. This configuration, compared to conventional sharp right-angled walls, allows for a smoother distribution of magnetic field lines. From a magnetic field theory perspective, magnetic field lines are closed curves; a smooth wall surface can guide the magnetic field lines more naturally through the stator slot 150, reducing magnetic field distortion near the slot opening 151. Cogging torque is generated by the change in magnetic field energy with the rotor 20's position. The new slot wall design can adjust the distribution of magnetic field energy, reducing the gradient of magnetic field energy change with the rotor 20's position, thereby effectively reducing cogging torque.

[0069] Reference Figures 1 to 3 As shown, in this embodiment, the stator slot 150 is a V-shaped slot. Specifically, in this embodiment, the included angle between the two bottom walls of the stator slot 150 is a right angle, which facilitates automated winding. It is understood that in some other embodiments, the stator slot 150 may be a flat-bottomed slot or a round-bottomed slot, which can be selected according to the actual application requirements.

[0070] Reference Figure 1As shown, along the axial direction of the rotor core 300, the height of the magnet 400 is greater than or equal to the height of the rotor core 300. When the height of the magnet 400 is equal to the height of the rotor core 300, both end faces of the magnet 400 are flush with both end faces of the rotor core 300. When the height of the magnet 400 is greater than the height of the rotor core 300, at least one end face of the magnet 400 protrudes beyond the end face of the rotor core 300. This allows for a more efficient arrangement of the magnets 400 within the rotor core 300, improving the utilization rate of the magnetically conductive material. In this embodiment, the rotor core 300 is made of magnetically conductive materials such as silicon steel. Silicon steel has excellent magnetic permeability, which can guide the magnetic field and improve the efficiency and performance of the motor.

[0071] In this embodiment, the height of the magnet 400 is greater than the height of the rotor core 300 along the axial direction of the rotor core 300. This arrangement allows more magnetic field to pass through the rotor core 300, thus making fuller use of the magnetic permeability of the silicon steel material, reducing magnetic field leakage and waste, improving the utilization rate of the silicon steel magnetic material, and reducing the manufacturing cost of the motor. Simultaneously, because the magnet 400 has a longer conduction path within the rotor core 300, it can enhance the magnetic field strength inside the motor to a certain extent. A stronger magnetic field can increase the motor's torque output, enabling the motor to provide greater power with the same volume and input power, making it suitable for more household appliances.

[0072] The household appliance of the second aspect of the present invention includes the motor of the first aspect of the present invention. The household appliance may be a refrigerator, an air conditioner, a washing machine, etc., and the motor may be specifically applied to an air conditioner fan, a refrigerator compressor, an air conditioner compressor, etc.

[0073] Because the household appliances adopt all the technical solutions of the motors in the above embodiments, they have at least all the beneficial effects brought about by the technical solutions in the above embodiments.

[0074] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention 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 the present invention.

Claims

1. An electric motor, characterized in that, include: A stator includes a stator core, the stator core including a yoke and a plurality of teeth, the plurality of teeth being arranged circumferentially on the inner side of the yoke and defining a rotor hole; A rotor is disposed in the rotor hole. The rotor includes a rotor core and a plurality of magnets. The rotor core is provided with a plurality of magnet slots. The plurality of magnet slots are arranged at intervals along the circumference of the rotor core. The plurality of magnets are respectively installed in the corresponding magnet slots. Wherein, the minimum inner diameter of the stator core is D1, the maximum radial dimension of the magnet along the rotor core is Lm, the maximum circumferential dimension of the magnet along the rotor core is Hm, the circumference is π, and the following condition is met: 16≤π*(D1-2*Lm) / Hm≤19.

2. The motor according to claim 1, characterized in that, A stator slot is formed between two adjacent teeth. Each stator slot has a slot that communicates with the rotor hole. The width of the slot is S1, which satisfies: 0.0115 < S1 / (π*D1) < 0.0135.

3. The motor according to claim 1, characterized in that, The maximum outer diameter of the stator core is D2, which satisfies: 0.60≤D1 / D2≤0.

68.

4. The motor according to claim 1 or 3, characterized in that, The maximum outer diameter of the stator core is greater than or equal to 80 mm and less than or equal to 100 mm.

5. The motor according to claim 1, characterized in that, The toothed part is provided with a toothed shoe at the end away from the yoke. The end face of the toothed shoe facing the rotor core includes multiple segments of first arc surfaces. The multiple segments of first arc surfaces are connected sequentially along the circumference of the stator core. The minimum distance between the first arc surface and the circumcircle of the rotor core is L1, and the maximum distance is L2, satisfying: 1 < L2 / L1 < 2.

5.

6. The motor according to claim 1, characterized in that, Adjacent magnet slots form core units. Each core unit has multiple second arc surfaces on its end face facing the stator core. These multiple second arc surfaces are connected sequentially along the circumference of the rotor core. The minimum distance between the second arc surface and the inscribed circle of the stator core is L3, and the maximum distance is L4, satisfying: 1 < L4 / L3 < 2.

5.

7. The motor according to claim 1, characterized in that, The outer contour of the stator core is a polygon, the number of sides of the polygon is the same as the number of teeth, and the sides of the polygon and the teeth are arranged in a one-to-one correspondence along the radial direction of the stator core.

8. The motor according to claim 1 or 7, characterized in that, The number of teeth is greater than or equal to 12, and the number of poles of the rotor is greater than or equal to 14.

9. The motor according to claim 1, characterized in that, A stator slot is formed between two adjacent teeth, and each stator slot is provided with a slot opening that communicates with the rotor hole. The wall surface of the stator slot opposite to the slot opening is an arc surface or is composed of at least one section of a plane.

10. A household appliance, characterized in that, Includes the motor as described in any one of claims 1 to 9.

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