Motor

Abstract

The present invention may provide a motor comprising: a shaft; a rotor coupled to the shaft; and a stator disposed corresponding to the rotor; wherein the stator comprises a stator core, an insulator coupled to the stator core, and a coil disposed on the insulator; wherein the stator core comprises a yoke and a plurality of teeth protruding from the yoke, and the teeth comprise a first surface and a second surface facing the rotor, and a first distance, which is the shortest distance from the center of the shaft to the first surface, is greater than a second distance, which is the shortest distance from the center of the shaft to the second surface, and the plurality of teeth comprises a first tooth and a second tooth, and the first distance of the first tooth is different from the first distance of the second tooth.

Description

Technology Field

[0001] The example relates to a motor. Background Technology

[0002] A motor comprises a stator and a rotor. The stator may include teeth forming multiple slots, and the rotor may include multiple magnets facing the teeth. Adjacent teeth are spaced apart to form slot open spaces. During the rotation of the rotor, cogging torque can occur due to the difference in air permeability between the metal stator and the empty slot open spaces. Since this cogging torque is a cause of noise and vibration, reducing it is of paramount importance for improving motor quality. The problem to be solved

[0003] Accordingly, the embodiment aims to solve the above-mentioned problems and to provide a motor capable of reducing cogging torque.

[0004] The problems that the embodiments aim to solve are not limited to those mentioned above, and other problems not mentioned herein will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0005] An embodiment for achieving the above objective may provide a motor comprising a shaft, a rotor coupled to the shaft, and a stator disposed corresponding to the rotor, wherein the stator comprises a stator core, an insulator coupled to the stator core, and a coil disposed on the insulator, wherein the stator core comprises a yoke and a plurality of teeth protruding from the yoke, wherein the teeth comprise a first surface and a second surface facing the rotor, wherein a first distance, which is the shortest distance from the center of the shaft to the first surface, is greater than a second distance, which is the shortest distance from the center of the shaft to the second surface, and wherein the plurality of teeth comprises a first tooth and a second tooth, and the first distance of the first tooth is different from the first distance of the second tooth. Effects of the invention

[0006] According to the embodiment, by increasing the main order of cogging, an advantageous effect of significantly reducing cogging torque is provided.

[0007] According to the embodiment, by making the depth of the groove (first distance) placed in the first tooth and the depth of the groove placed in the second tooth different, there is an advantage of significantly reducing the cogging torque. Brief explanation of the drawing

[0008] FIG. 1 is a side cross-sectional view of a motor according to an embodiment, FIG. 2 is a plan view of the stator and rotor illustrated in FIG. 1, FIG. 3 is a drawing showing the first surface and the second surface of the first tooth, FIG. 4 is a drawing showing the first and second surfaces of the second tooth, FIG. 5 is a diagram illustrating the cogging torque and maximum torque corresponding to the change in length of the second notch in a motor according to an embodiment. FIG. 6 is a graph showing the cogging torque of a motor according to an embodiment corresponding to a change in the length of the second notch compared to a comparative example. FIG. 7 is a graph showing the waveform of cogging torque according to the rotation angle in a motor according to a comparative example in which the depth of the notches of all teeth is constant at 0.5 mm. FIG. 8 is a graph showing the waveform of the cogging torque according to the rotation angle when the depth of the second notch is 102% of the depth of the first notch. Specific details for implementing the invention

[0009] The direction parallel to the length direction (up-down direction) of the shaft is called the axial direction, the direction perpendicular to the axial direction with respect to the shaft is called the radial direction, and the direction following a circle with a radius in the radial direction with respect to the shaft is called the circumferential direction.

[0010] FIG. 1 is a side cross-sectional view of a motor according to an embodiment.

[0011] Referring to FIG. 1, the motor according to the embodiment may include a shaft (100), a rotor (200), a stator (300), a bus bar (400), a bus bar holder (500), and a housing (600).

[0012] Hereinafter, "inner side" refers to the direction from the housing (600) toward the shaft (100), which is the center of the motor, and "outer side" refers to the opposite direction of the inner side, which is the direction from the shaft (100) toward the housing (600).

[0013] The shaft (100) can be coupled with the rotor (200). When an electromagnetic interaction occurs between the rotor (200) and the stator (300) through the supply of current, the rotor (200) rotates and the shaft (100) rotates in conjunction with it.

[0014] The rotor (200) rotates through electrical interaction with the stator (300). The rotor (200) may be positioned corresponding to the stator (300) and may be positioned inside. The rotor (200) may include a rotor core (210) and a magnet (220) positioned in the rotor core (210).

[0015] The stator (300) is positioned on the outside of the rotor (200). The stator (300) may include a stator core (310), an insulator (320), and a coil (330). The insulator (320) is seated on the stator core (310). The coil (330) is mounted on the insulator (320). The coil (330) causes electrical interaction with the magnet (220) of the rotor (200).

[0016] The busbar (400) can be placed on the stator (300). The busbar (400) is electrically connected to the coil (330). The busbar (400) can also be connected to an external power source.

[0017] The busbar holder (500) supports the busbar (400). The busbar holder (500) may be an annular member containing the busbar (400) inside.

[0018] The housing (600) may be positioned on the outside of the stator (300). The housing (600) may be a cylindrical member with one side open.

[0019] FIG. 2 is a plan view of the stator (300) and rotor (200) illustrated in FIG. 1.

[0020] Referring to FIG. 2, the stator core (310) may include a yoke (311) and a tooth (312). The tooth (312) may protrude from the inner circumference of the yoke (311) toward the center (C) of the stator (300). There may be multiple teeth (312). The number of teeth (312) may be varied in correspondence with the number of magnets (220). The stator core (310) may be formed by combining multiple segmented cores that include such a yoke (311) and a tooth (312).

[0021] Cogging torque appears in the form of a wave having amplitude and frequency, and the cogging main order refers to the number of vibrations of the cogging torque waveform per unit rotation (1 rotation) of the motor. As the cogging main order increases, it means that the number of vibrations of the cogging torque waveform increases, so the cogging torque can be significantly reduced. The cogging main order can be determined by the number of magnets (220) and the number of teeth (312). While increasing this cogging main order can reduce the cogging torque, the number of magnets (220) and the number of teeth (312) are fixed, so the cogging main order is also fixed.

[0022] FIG. 3 is a drawing showing the first surface (S1) and the second surface (S2) of the first tooth (312), and FIG. 4 is a drawing showing the first surface (S1) and the second surface (S2) of the second tooth (312).

[0023] Referring to FIGS. 3 and 4, among the plurality of teeth (312), teeth (312) adjacent to each other in the circumferential direction are defined as the first tooth (312A) and the second tooth (312B). The first tooth (312A) and the second tooth (312B) each include a first surface (S1) and a second surface (S2), and the first surface (S1) and the second surface (S2) are defined as the inner surfaces of the teeth (312) positioned facing the magnet (220). The first distance (R1), which is the shortest distance from the center of the shaft (100) to the first surface (S1), is greater than the second distance (R3), which is the shortest distance from the center of the shaft (100) to the second surface (S2).

[0024] The motor according to the embodiment aims to reduce the magnitude of the cogging torque by increasing the frequency through a shape change (recessed notch) in the first tooth (312A) and the second tooth (312B) to increase the cogging main order.

[0025] The first surface (S11) of the first tooth (312A) can form two first notches (H1). The first notches (H1) are formed concavely in the second surface (S21). The first surface (S11) of the first tooth (312A) can be placed on the first circumference (O1). And the second surface (S21) of the first tooth (312A) can be placed on the third circumference (O3). The radius of the first circumference (O1) is larger than the radius of the third circumference (O3). Both of the two first surfaces (S11) can be placed on the first circumference (O1) at regular intervals in the circumferential direction. And all of the three second surfaces (S21) can be placed on the third circumference (O3) at regular intervals in the circumferential direction.

[0026] The first surface (S12) of the second tooth (312B) can form two second notches (H2). The second notches (H2) are formed concavely on the second surface (S22) of the second tooth (312B). The first surface (S12) of the second tooth (312B) can be placed on the second circumference (O2). And the second surface (S22) of the second tooth (312B) can be placed on the third circumference (O3). The radius of the second circumference (O2) is larger than the radius of the third circumference (O3). Both of the two first surfaces (S12) can be placed on the second circumference (O2) at regular intervals in the circumferential direction. And all of the three second surfaces (S22) can be placed on the third circumference (O3) at regular intervals in the circumferential direction.

[0027] In the motor according to the embodiment, the first distance (R1) of the first tooth (312A) and the first distance (R2) of the second tooth (312B) are different. Also, the radius of the first circumference (O1) and the radius of the second circumference (O2) are different. Consequently, the radius of the first circumference (O1), the radius of the second circumference (O2), and the radius of the third circumference (O3) are all different.

[0028] The depth of the first notch (H1) is defined as the difference between the first distance (R1) of the first tooth (312A) and the second distance (R3) of the second tooth (312B). And the depth of the second notch (H2) is defined as the first distance (R2) of the second tooth (312B) and the second distance (R3) of the second tooth (312B).

[0029] Meanwhile, the plurality of first surfaces (S11) arranged on the first tooth (312A) may each have the same circumferential length (L1). Additionally, the plurality of first surfaces (S12) arranged on the second tooth (312B) may each have the same circumferential length (L2). Furthermore, the circumferential length (L1) of the first surface (S11) of the first tooth (312A) and the circumferential length (L2) of the first surface (S11) of the second tooth (312B) may be the same.

[0030] The circumferential length (L1) of the first surface (S11) of the first tooth (312A) and the circumferential length (L2) of the first surface (S12) of the second tooth (312B) may be greater than the circumferential length (L3) of the second surface (S2).

[0031] The circumferential length (L3) of the second surface (S12) of the first tooth (312A) and the circumferential length (L3) of the second surface (S22) of the second tooth (312B) may be the same.

[0032] In this way, the motor according to the embodiment has a different depth of the first notch (H1) of the first tooth (312A) and the depth of the second notch (H2) of the second tooth (312B), so the cogging torque waveform by the first tooth (312A) and the cogging torque waveform by the second tooth (312B) are different, and the two different cogging torque waveforms influence each other to cause a change in the cogging torque.

[0033] FIG. 5 is a diagram showing the cogging torque and maximum torque corresponding to the change in length of the second notch (H2) in a motor according to an embodiment, and FIG. 6 is a graph showing the cogging torque of the motor according to an embodiment corresponding to the change in length of the second notch (H2) in comparison with a comparative example.

[0034] Referring to FIGS. 5 and 6, the motor according to the comparative example corresponds to a motor in which the length of the notch placed on all teeth is constant at 0.5 mm, so that all teeth are symmetrically arranged. The motor according to the embodiment corresponds to a motor in which the depth of the first notch (H1) of the first tooth (312A) is constant at 0.5 mm, and the depth of the second notch (H2) of the second tooth (312B) is different from the depth of the first notch (H1), so that all teeth (312) are asymmetrically arranged.

[0035] It can be confirmed that the cogging torque decreases when the depth of the second notch (H2) is within the range of 50% or more and less than 100% of the depth of the first notch (H1), or within the range of more than 100% and less than or equal to 134%. For example, when the depth of the first notch (H1) is 0.5mm, it can be confirmed that a cogging torque (T2) smaller than the cogging torque (T1: 81.54mNm) of the comparative example is detected when the depth of the second notch (H2) is within the range of 0.26mm to 0.65mm. When the depth of the first notch (H1) is 0.5mm, if the depth of the second notch (H2) is smaller than 0.26mm or larger than 0.65mm, a cogging torque larger than the cogging torque (T1: 81.54mNm) of the comparative example is detected.

[0036] It can be confirmed that the cogging torque is reduced compared to the comparative example when the depth of the second notch (H2) is within 50% to 134% of the depth of the first notch (H1), but the maximum torque is not significantly different from the comparative example, so there is no significant effect on the performance of the motor.

[0037] When the depth of the second notch (H2) is 102% of the depth of the first notch (H1), for example, when the depth of the first notch (H1) is 0.5 mm, the depth of the second notch (H2) is 0.51 mm, the cogging torque (G) is reduced by 16.16% compared to the comparative example, showing the greatest reduction.

[0038] FIG. 7 is a graph showing the waveform of cogging torque according to the rotation angle in a motor according to a comparative example in which the depth of the notches of all teeth (312) is 0.5 mm, and FIG. 8 is a graph showing the waveform of cogging torque according to the rotation angle when the depth of the second notch (H2) is 102% of the depth of the first notch (H1).

[0039] Referring to FIGS. 7 and 8, when the depth of the second notch (H2) is 102% of the depth of the first notch (H1), for example, when the depth of the first notch (H1) is 0.5 mm and the depth of the second notch (H2) is 0.51 mm, it can be seen that the amplitude of the cogging torque waveform corresponding to the rotation angle is smaller and more uniform than in the comparative example.

[0040] Thus, when the depth of the second notch (H2) is set to a range of 50% or more and less than 100% of the depth of the first notch (H1), or a range of more than 100% and less than or equal to 134%, there is an advantage of reducing cogging torque while securing the maximum torque of the motor.

[0041] The aforementioned embodiments can be used in various devices, such as vehicles or home appliances. Explanation of the symbols

[0042] 100: Shaft 200: Rotor 300: Status 310: Status Core 320: Insulator 311: York 312: Tooth 312A: 1st tooth 312B: Second Tooth 330: Coil S1: 1st side S2: 2nd side H1: 1st notch H2: 2nd notch

Claims

Claim 1 A motor comprising: a shaft; a rotor coupled to the shaft; and a stator disposed corresponding to the rotor; wherein the stator comprises a stator core, an insulator coupled to the stator core, and a coil disposed on the insulator; wherein the stator core comprises a yoke and a plurality of teeth protruding from the yoke, and the teeth comprise a first surface and a second surface facing the rotor, wherein a first distance, which is the shortest distance from the center of the shaft to the first surface, is greater than a second distance, which is the shortest distance from the center of the shaft to the second surface, and wherein the plurality of teeth comprises a first tooth and a second tooth, and the first distance of the first tooth is different from the first distance of the second tooth. Claim 2 In claim 1, the first tooth and the second tooth are alternately arranged in the circumferential direction. Claim 3 In claim 2, the difference between the first distance of the first tooth and the second distance of the first tooth is within the range of 50% or more and less than 100% of the difference between the first distance of the second tooth and the second distance of the second tooth, or within the range of more than 100% and less than or equal to 134%. Claim 4 In claim 1, the first surface of the first tooth is disposed on the first circumference, and the first surface of the second tooth is disposed on the second circumference, and the radius of the first circumference and the radius of the second circumference are different from each other. Claim 5 In claim 4, the second surface of the first tooth and the second surface of the second tooth are arranged on a third circumference, and the radius of the first circumference, the radius of the second circumference, and the radius of the third circumference are different from each other. Claim 6 In claim 1, the first surface and the second surface are alternately arranged along the circumferential direction. Claim 7 A motor according to claim 1, wherein a plurality of first surfaces are spaced apart along the circumferential direction and a plurality of second surfaces are spaced apart along the circumferential direction. Claim 8 In claim 1, a plurality of the first surfaces are arranged on the same circumference of a motor. Claim 9 A motor according to claim 1, wherein the circumferential length of the first surface of the first tooth and the circumferential length of the first surface of the second tooth are the same, and the circumferential length of the second surface of the first tooth and the circumferential length of the second surface of the second tooth are the same. Claim 10 A motor according to claim 1, wherein the circumferential length of the first surface is greater than the circumferential length of the second surface.

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