motor

Abstract

This invention relates to a motor comprising: a shaft; a rotor, the shaft being coupled to the rotor; and a stator disposed on the outer side of the rotor. The stator includes a stator core having a plurality of teeth and a coil wound around each of the teeth. Each tooth includes a body portion around which the coil is wound, a protrusion disposed on an end portion of the body portion, and a groove formed as a concave shape on the inner surface of the protrusion. The side surface of the protrusion includes a first surface extending from the body portion and a second surface extending from the first surface. The depth of the groove is 0.7 to 1.3 times the length of the second surface in the radial direction.

Description

[0001] This application is a divisional application of the application filed on August 8, 2018, with Chinese national application number 201880056541.2 (international application number PCT / KR2018 / 009003) and the invention title "Stator and Motor Including Stator". Technical Field

[0002] The implementation involves a stator and a motor including the stator. Background Technology

[0003] A motor is a device that generates rotational force by converting electrical energy into mechanical energy, and motors are widely used in vehicles, household appliances, industrial equipment, and so on.

[0004] In particular, the electronic power steering (EPS) system, which uses a motor, drives the motor in the electronic control unit according to driving conditions to ensure cornering stability and provide rapid restoring force. Therefore, the driver can drive the vehicle safely.

[0005] The motor includes a stator and a rotor. The stator may include teeth forming a plurality of slots, and the rotor may include a plurality of magnets arranged to face the teeth. Adjacent teeth are arranged to be spaced apart from each other to form slot openings.

[0006] In this situation, cogging torque may occur due to the difference in magnetic permeability between the stator, which is made of metallic material, and the SO air, which is an empty space, when the rotor rotates. Since cogging torque causes noise and vibration, reducing cogging torque is the most important factor in improving the quality of the motor.

[0007] However, since the performance and quality of a motor vary depending on the shape of the slots formed in the teeth, the motor must be designed to reduce cogging torque while maintaining performance. Summary of the Invention

[0008] Technical issues

[0009] The implementation aims to provide a motor capable of reducing cogging torque.

[0010] Furthermore, the embodiments aim to provide a motor that can improve motor quality by reducing cogging torque through a design that reduces the width and depth of the slot formed in each tooth based on the slot opening.

[0011] The problems to be solved by this invention are not limited to those described above, and those skilled in the art should clearly understand other problems not mentioned above based on the following description.

[0012] Technical solutions

[0013] One aspect of the implementation provides a stator including a stator core having a plurality of teeth and a coil wound around each of the teeth, wherein each of the teeth includes a body around which the coil is wound and a slide connected to the body, the slide including a plurality of grooves, and the center of curvature of the inner circumferential surface of the slide being the same as the center of the stator core.

[0014] A slot can be set to two slots.

[0015] The width of the slot can be in the range of 90% to 110% of the width of the slot opening (SO) of the tooth in the circumferential direction of the stator core.

[0016] Another aspect of the embodiment provides a motor including a shaft, a rotor having a bore, and a stator, the shaft being inserted into the bore, the stator being arranged on the outer side of the rotor, wherein the stator includes a stator core having a plurality of teeth and a coil wound around each of the teeth, each of the teeth including a body wound with the coil and a slide connected to the body, the slide including a plurality of grooves, the center of curvature of the inner circumferential surface of the slide being the same as the center of the stator core, the rotor including a cylindrical rotor core and a plurality of magnets arranged around the outer circumferential surface of the rotor core, the magnets having an inner circumferential surface in contact with the outer circumferential surface of the rotor core, and the magnets having a second angle between a first extension line and a second extension line when the angle formed by dividing the outer circumferential surface of the rotor core by the number of magnets is called a first angle, the magnets having a second angle between a first extension line and a second extension line, the first extension line and the second extension line extending from two endpoints of the inner circumferential surface of the magnet to the center point of the rotor core in a transverse cross section of the rotor core and the magnets, and the ratio of the second angle to the first angle being in the range of 0.92 to 0.95.

[0017] When the radius of curvature of the outer circumferential surface of the magnet is called the first radius and the radius of curvature of the inner circumferential surface of the magnet is called the second radius, the rotor can have a ratio of the first radius to the second radius in the range of 0.5 to 0.7 in the transverse cross section of the rotor core and the magnet.

[0018] A slot can be set to two slots.

[0019] The two slots can be arranged symmetrically based on the following reference line: the reference line passes through the center of the width of the sliding pad in the circumferential direction and the center of the stator core.

[0020] The number of vibrations in the cogging torque waveform can be three times the least common multiple of the number of magnets and the number of teeth per unit rotation period.

[0021] The width of the slot can be in the range of 90% to 110% of the width of the slot opening (SO) of the tooth in the circumferential direction of the stator core.

[0022] Multiple magnets can be arranged in a configuration on the outer peripheral surface of the rotor core, and the multiple magnets can be arranged to be spaced apart from each other by a predetermined interval.

[0023] Another aspect of the embodiment provides a motor including a shaft, a rotor connected to the shaft, and a stator disposed on the outer side of the rotor, wherein the stator includes a stator core having a plurality of teeth and a coil wound around each of the teeth, the teeth including a body portion around which the coil is wound, a protrusion disposed on an end portion of the body portion, and a groove formed as a concave shape on the inner surface of the protrusion, and the width (W2) of the groove is 0.85 to 1.1 times the distance (W21) between an end of a protrusion of one of the teeth and an end of another protrusion of another tooth adjacent to the aforementioned tooth.

[0024] Here, the width of the groove (W2) can be 1.05 to 1.1 times the distance (W21) between one end of a protrusion of one of the teeth and one end of another protrusion of another tooth adjacent to the aforementioned tooth.

[0025] The side surface of the protrusion may include a first surface extending from the body portion and a second surface extending from the first surface, the depth (D) of the groove may be 0.7 to 1.3 times the length (L) of the second surface in the radial direction, and the length (L) may be 1 / 4 of the distance (W21).

[0026] The depth (D) of the groove can be 0.175 to 0.325 times the distance (W21).

[0027] Another aspect of the implementation provides a motor including a shaft, a rotor connected to the shaft, and a stator disposed on the outer side of the rotor, wherein the stator includes a stator core having a plurality of teeth and a coil wound around each of the teeth, the teeth including a body portion around which the coil is wound, a protrusion disposed on an end portion of the body portion, and a groove formed as a concave shape on the inner surface of the protrusion, the side surface of the protrusion including a first surface extending from the body portion and a second surface extending from the first surface, and the depth (D) of the groove is 0.7 to 1.3 times the length (L) of the second surface in the radial direction.

[0028] Here, the depth (D) of the groove can be 1.1 to 1.3 times the length (L) of the second surface.

[0029] The first surface can be formed with a first tilt angle relative to the side surface of the body portion, and the second surface can be formed with a second tilt angle relative to the first surface. In this case, the first tilt angle can be different from the second tilt angle.

[0030] Another aspect of the embodiment provides a motor including a shaft, a rotor connected to the shaft, and a stator disposed on the outer side of the rotor, wherein the stator includes a stator core having a plurality of teeth and a coil wound around each of the teeth, the teeth including a body portion around which the coil is wound, a protrusion disposed on an end portion of the body portion, and a groove formed as a concave shape on the inner surface of the protrusion, the side surface of the protrusion including a first surface extending from the body portion and a second surface extending from the first surface, the width (W2) of the groove being 0.85 to 1.1 times the distance (W21) between an end of a protrusion of one of the teeth and an end of another protrusion of another tooth adjacent to the aforementioned tooth, and the depth (D) of the groove being 0.7 to 1.3 times the length (L) of the second surface in the radial direction.

[0031] Here, the ratio of the width (W2) of the groove to the depth (D) of the groove can be in the range of 3.23 to 3.38.

[0032] Another aspect of the embodiment provides a motor including a shaft, a rotor connected to the shaft, and a stator disposed on the outer side of the rotor, wherein the stator includes a stator core having a plurality of teeth and a coil wound around each of the teeth, the teeth including a body portion around which the coil is wound, a protrusion disposed on an end portion of the body portion, and a groove formed as a concave shape on the inner surface of the protrusion, and the depth (D) of the groove is 0.175 to 0.325 times the distance (W21) between an end of a protrusion of one of the teeth and an end of another protrusion of another tooth adjacent to the aforementioned tooth.

[0033] Meanwhile, the cross-section of the slot in the axial direction perpendicular to the motor shaft can have a quadrilateral shape, and the slot can be configured as two slots.

[0034] The first distance (L21) between the grooves can be equal to the second distance (L22) from one end of the protrusion to the groove.

[0035] The two slots can be arranged symmetrically based on the following baseline (CL): the baseline (CL) passes through the center of the width of the protrusion in the circumferential direction and the center of the body portion.

[0036] The inner surface can be formed with a predetermined curvature (1 / R20) based on the center C of the motor.

[0037] In a motor, the rotor magnets can be set to eight magnets, and the stator teeth can be set to twelve teeth.

[0038] Beneficial effects

[0039] The implementation method can provide the following beneficial effects: by forming slots in the stator teeth to increase the order of the main tooth slots, the tooth cogging torque can be significantly reduced.

[0040] According to the implementation method, when slots are arranged in the teeth of the stator of a six-pole nine-slot motor, the beneficial effect of preventing a significant increase in cogging torque can be provided when the main tooth cogging order is "ninth".

[0041] Furthermore, according to the implementation, the quality of the motor can be improved by reducing cogging torque through the design of the width and depth of the slot formed in each tooth based on the slot opening. For example, the motor can reduce cogging torque by defining the relationship between the width and depth of the slot and the slot opening.

[0042] In addition, the motor can reduce cogging torque by defining the relationship between the depth of the groove and the length of the protrusion.

[0043] The various advantages and effects of the embodiments are not limited to a detailed description, and should be readily understood through a detailed description of the embodiments. Attached Figure Description

[0044] Figure 1 The diagram illustrates a motor according to the first embodiment.

[0045] Figure 2 It is a diagram illustrating the first and second angles.

[0046] Figure 3 This is a diagram showing the first angle.

[0047] Figure 4 The figure shows a graph comparing the value of torque corresponding to the rate of reduction of magnet width with the value of torque ripple.

[0048] Figure 5 It is a diagram illustrating the optimal shape of the outer peripheral surface of a magnet for reducing torque ripple.

[0049] Figure 6 and Figure 7 It is a graph showing the torque pulsation generated under high-speed rotation conditions.

[0050] Figure 8 This is a table that compares the cogging torque and torque ripple of the comparative example with those of the example.

[0051] Figure 9 It is a graph showing the torque pulsation of the motor according to the first embodiment under high-speed rotation conditions.

[0052] Figure 10 It is a diagram illustrating the grooves of the teeth.

[0053] Figure 11 This is a table showing the number of main gear orders increased by the motor according to the first embodiment.

[0054] Figure 12 It is a diagram showing the width of the groove.

[0055] Figure 13a and Figure 13b The figure shows a curve illustrating how the cogging torque waveform varies with the width of the slot.

[0056] Figure 14 This is a diagram illustrating a sliding tile with an inner circumferential surface formed by a curved surface.

[0057] Figure 15 This table compares the cogging torque of a motor where the inner circumferential surface of the sliding pad is formed by a flat surface with the cogging torque of a motor where the center of curvature of the inner circumferential surface of the sliding pad coincides with the center of the stator core.

[0058] Figure 16 This table compares the cogging torque deviation and output of a motor where the inner circumferential surface of the sliding pad is flat, with the cogging torque deviation and output of a motor where the curvature center of the inner circumferential surface of the sliding pad coincides with the center of the stator core.

[0059] Figure 17 This is a diagram showing the improved state of cogging torque in a motor according to the first embodiment, corresponding to the main cogging order.

[0060] Figure 18 The diagram illustrates a motor according to the second embodiment.

[0061] Figure 19 The illustration shows a cross-sectional view of a motor according to the second embodiment.

[0062] Figure 20 This is a cross-sectional view of the stator of a motor according to the second embodiment.

[0063] Figure 21 It's a diagram. Figure 3 A magnified view of region A1.

[0064] Figure 22 It is a graph showing how the cogging torque varies with the angle between the body portion and the protrusion of the stator core, which is arranged in a motor according to the second embodiment.

[0065] Figure 23 The diagram shows a curve illustrating how the cogging torque waveform varies according to a first tilt angle between the body portion and the protrusion of the stator core arranged in the motor according to the second embodiment.

[0066] Figure 24 This is a table showing the changes in cogging torque and torque when the width of the slot in the motor according to the second embodiment is 0.85 to 0.95 times the width of the slot opening.

[0067] Figure 25 This is a graph showing the cogging torque when the width of the slot in the motor according to the second embodiment is 0.85 to 0.95 times the width of SO.

[0068] Figure 26 This is a graph showing the cogging torque waveform of a motor in a comparative example.

[0069] Figure 27 This is a graph showing the cogging torque waveform of the motor according to the second embodiment when the width of the slot is 0.9 times the width of SO.

[0070] Figure 28 This is a table showing the variation of cogging torque and torque when the width of the slot in the motor according to the second embodiment is 1.05 to 1.1 times the width of SO.

[0071] Figure 29 It is a graph showing the change in cogging torque when the width of the slot in the motor according to the second embodiment is 1.05 to 1.1 times the width of SO.

[0072] Figure 30 This is a graph showing the cogging torque waveform of the motor according to the second embodiment when the width of the slot is 1.1 times the width of SO.

[0073] Figure 31 This is a table showing the variation of cogging torque and torque when the depth of the slot in the motor according to the second embodiment is 0.7 to 0.9 times the length of the second surface in the radial direction.

[0074] Figure 32 It is a graph showing the cogging torque when the depth of the slot in the motor according to the second embodiment is 0.7 to 0.9 times the length of the second surface in the radial direction.

[0075] Figure 33 It is a graph showing the cogging torque waveform when the depth of the slot in the motor according to the second embodiment is 0.9 times the length of the second surface in the radial direction.

[0076] Figure 34 This is a table showing the variation of cogging torque and torque when the depth of the slot in the motor according to the second embodiment is 1.1 to 1.3 times the length of the second surface in the radial direction.

[0077] Figure 35 It is a graph showing the cogging torque when the depth of the slot in the motor according to the second embodiment is 1.1 to 1.3 times the length of the second surface in the radial direction.

[0078] Figure 36 It is a graph showing the cogging torque waveform when the depth of the slot in the motor according to the second embodiment is 1.3 times the length of the second surface in the radial direction.

[0079] Figure 37 This is a table showing the variation of cogging torque and torque when the depth of the slot in the motor according to the second embodiment is 0.65 mm and the width of the slot is 0.85 to 1.1 times the width of SO.

[0080] Figure 38 It is a graph showing the cogging torque when the depth of the slot in the motor according to the second embodiment is 0.65 mm and the width of the slot is 0.85 to 1.1 times the width of SO.

[0081] Figure 39 It is a graph showing the cogging torque waveform when the depth of the slot in the motor according to the second embodiment is 0.65 mm and the width of the slot is 1.1 times the width of SO.

[0082] Figure 40 This is a table showing the variation of cogging torque and torque when the width of the slot in the motor according to the second embodiment is 2.2 mm and the depth of the slot is 0.7 to 1.3 times the length of the second surface in the radial direction.

[0083] Figure 41 It is a graph showing the cogging torque when the width of the slot in the motor according to the second embodiment is 2.2 mm and the depth of the slot is 0.7 to 1.3 times the length of the second surface in the radial direction.

[0084] Figure 42 It is a graph showing the cogging torque waveform when the width of the slot in the motor according to the second embodiment is 2.2 mm and the depth of the slot is 1.3 times the length of the second surface in the radial direction. Detailed Implementation

[0085] In the following, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0086] However, the technical concept of the present invention is not limited to the described embodiments but can be implemented in various different forms, and one or more components between embodiments can be selectively combined and replaced without departing from the technical scope of the present invention.

[0087] Furthermore, unless explicitly defined and described, the terms (including technical and scientific terms) used in the embodiments of this invention may be interpreted as meaning commonly understood by one of ordinary skill in the art to which this invention pertains, and commonly used terms such as those defined in dictionaries may be interpreted in light of the contextual meaning of the relevant art.

[0088] Furthermore, the terminology used herein is intended to describe implementation methods and not to limit the invention.

[0089] In this disclosure, unless the context clearly indicates otherwise, the singular form may include the plural form, and when described as “at least one (or more) of A, B and C”, this may include one or more of all combinations that can be combined with A, B and C.

[0090] Furthermore, when describing the components of embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc., may be used.

[0091] These terms are intended to distinguish one component from others, but the nature, order, or sequence of components are not limited by these terms.

[0092] Furthermore, when a component is described as “connected,” “linked,” or “attached” to another component, this can include not only the component being directly connected, linked, or attached to another component, but also the component being “connected,” “linked,” or “attached” to another component through another component between the component and the other component.

[0093] Furthermore, when a component is described as being "above" or "below" another component, the term "above" or "below" includes not only cases where the two components are in direct contact with each other, but also cases where one or more additional components are formed or arranged between the two aforementioned components. Additionally, when described as "above" or "below," the term "above" or "below" is based on the premise that a component can point not only upwards but also downwards.

[0094] In the following, embodiments of the invention will be described in detail with reference to the accompanying drawings. Regardless of the number of drawings, the same reference numerals are assigned to the same or corresponding parts, and repeated descriptions of the same or corresponding parts will be omitted herein.

[0095] Figure 1 This diagram illustrates a motor according to the first embodiment. Figure 2 It is a diagram illustrating the first and second angles, and Figure 3 This is a diagram showing the first angle.

[0096] Reference Figures 1 to 3According to the first embodiment, the motor 1 may include a shaft 100, a rotor 200 and a stator 300.

[0097] Shaft 100 can be connected to rotor 200. When electromagnetic interaction is generated in rotor 200 and stator 300 through the supply of current, rotor 200 rotates, and therefore shaft 100 rotates by means of rotational interlock with rotor 200. Shaft 100 can be connected to the vehicle's steering shaft to transmit power to the steering shaft. Shaft 100 can be supported on bearings.

[0098] The rotor 200 rotates due to electrical interaction with the stator 300. The rotor 200 is arranged within the stator 300. The rotor 200 may include a rotor core 210 and a magnet 220 coupled to the rotor core 210. The rotor 200 can be implemented in a type where the magnet 220 is coupled to the outer peripheral surface of the rotor core 210. In this type of rotor 200, to prevent separation of the magnet 220 and increase the coupling force, a separate can assembly 230 can be coupled to the rotor core 210. Alternatively, the rotor 200 can be integrally formed with the magnet 220 and the rotor core 210 through a dual injection of the magnet 220 and the rotor core 210.

[0099] The rotor 200 can be implemented in a type where a magnet is attached to the interior of the rotor core. This type of rotor 200 can be provided with a recess into which the magnet 220 is inserted in the rotor core 210.

[0100] Simultaneously, the rotor 200 can be configured such that the magnets 220 are arranged in a stage within the rotor core 210, which is a single cylindrical article. Here, a stage means that the magnets 220 can be arranged such that there is no skewing on the outer peripheral surface of the rotor 200. Therefore, the height of the rotor core 210 based on its longitudinal section can be formed to be equal to the height of the magnets 220 based on their longitudinal section. That is, the magnets 220 can be implemented to cover the entire rotor core in the height direction (axial direction). Here, the axial direction can be the length direction of the shaft 100.

[0101] The stator 300 can be arranged on the outer side of the rotor 200. The stator 300 causes electrical interaction with the rotor 200 to induce the rotation of the rotor 200.

[0102] The sensing magnet 400 is a device coupled to the shaft 100 for interlocking with the rotor 200 to detect the position of the rotor 200. This sensing magnet may include a magnet and a sensing plate. The magnet may be coaxially coupled to the sensing plate. The sensing magnet 400 may include a main magnet and a secondary magnet, the main magnet being arranged adjacent to a hole forming an inner circumferential surface in the circumferential direction, and the secondary magnet being formed at the edge of the main magnet. The main magnet may be arranged in the same manner as the drive magnet inserted into the rotor of the motor. The secondary magnet is more subdivided than the main magnet and includes a plurality of magnetic poles. Therefore, the rotation angle can be further subdivided and measured, and the motor drive can be made smoother.

[0103] The sensing plate can be formed of a disk-shaped metal material. A sensing magnet can be attached to the upper surface of the sensing plate. Furthermore, the sensing plate can be attached to a shaft 100. A hole through which the shaft 100 passes is formed in the sensing plate.

[0104] A sensor for detecting the magnetic force of a sensing magnet can be mounted on a printed circuit board (PCB) 500. In this case, the sensor can be a Hall integrated circuit (IC). The sensor detects changes in the north and south poles of the main or auxiliary magnet to generate a sensing signal. The PCB 500 can be attached to the lower surface of the housing cover and mounted above the sensing magnet, such that the sensor faces the sensing magnet.

[0105] According to the first embodiment, the motor 1 can reduce cogging torque and torque pulsation by reducing the width of the magnet 220, thereby increasing the frequency of the cogging torque waveform per unit cycle. A detailed description follows. In describing the embodiment, the width of the magnet 220 can be defined as the length of the arc formed by the contact between the inner circumferential surface of the magnet 220 and the rotor core 210.

[0106] Reference Figure 2 and Figure 3 Multiple magnets 220 are attached to the outer peripheral surface of the rotor core 210. Furthermore, the stator 300 may include multiple teeth 320. The magnets 220 may be arranged to face the teeth 320.

[0107] For example, motor 1 can be a six-pole, nine-slot motor comprising six magnets 220 and nine teeth 320. The number of teeth 320 corresponds to the number of slots. Furthermore, the north and south poles of the magnets 220 can be arranged alternately along the circumferential direction of the rotor core 210.

[0108] The inner peripheral surface 211 of the magnet 220 contacts the outer peripheral surface of the rotor core 210. The width of the magnet 220 of the motor 1 according to the first embodiment can be described by a first angle R11 and a second angle R12.

[0109] First, the first angle R11 represents the angle obtained by dividing the angle formed by the outer peripheral surface of the rotor core 210—360 degrees—by the number of magnets 220. For example, when the number of magnets 220 is six, the first angle R11 is 60 degrees. The arc length of the rotor core 210 corresponding to the first angle R11 becomes a reference for setting the width of the magnets 220. In this case, taking into account the width of the protrusions used to guide the magnets 220, the actual width of the magnets 220 can be increased or decreased on the outer peripheral surface of the rotor core 210.

[0110] Next, the second angle R12 refers to the angle between the first extension line L11 and the second extension line L12. Here, the first extension line L11 refers to an imaginary line extending from the endpoint of either side of the inner circumferential surface 211 to the center point C of the rotor core 210 on the transverse section of the magnet 220. Here, the transverse section of the magnet 220 refers to the cross-section cut from the magnet 220 in a direction perpendicular to the axial direction of the motor.

[0111] The arc length of the rotor core 210 corresponding to the second angle R12 becomes another reference for setting the width of the magnet 220, the second angle R12 being the angle between the first extension line L11 and the second extension line L12.

[0112] The first angle R11 becomes a conventional reference angle for setting the width of the magnet 220, and the second angle R12 becomes a reference angle for setting the width of the magnet 220 to have a width smaller than the width of the magnet 220 set based on the first angle R11.

[0113] Figure 4 The figure shows a graph comparing the value of torque corresponding to the rate of reduction of magnet width with the value of torque ripple.

[0114] Reference Figure 4 In the case of a six-pole nine-slot motor, it can be observed that torque ripple below the baseline B, which represents the target torque ripple, is measured at points where the ratio of the second angle R12 to the first angle R11 is in the range of 0.92 to 0.95.

[0115] Furthermore, it can be observed that the torque measured at points where the ratio of the second angle R12 to the first angle R11 is in the range of 0.92 to 0.95 is higher than the baseline A representing the target reference torque, thus ensuring that the measured torque meets the required torque.

[0116] Figure 5 It is a diagram illustrating the optimal shape of the outer peripheral surface of a magnet for reducing torque ripple.

[0117] Reference Figure 5The point on the outer peripheral surface of the magnet 220 that is furthest from the center C of the rotor core 210 to the outer peripheral surface of the magnet 220 is called the Figure 5 P10. Connect the center C of rotor core 210 to Figure 5 The imaginary reference line of P10 is called Figure 5 Z.

[0118] Typically, the outer peripheral surface of the magnet 220 is designed to run along... Figure 5 The S11 arrangement. Figure 5 S11 represents having in Figure 5 On the baseline Z, from the first starting point P11 away from the center C to... Figure 5 The line of the circumference of the circle with radius F11 of P10.

[0119] Meanwhile, the outer peripheral surface of the rotor magnet 220 according to the embodiment is designed to run along... Figure 5 The S12 arrangement. Figure 5 S12 represents having in Figure 5 On the baseline Z, from the second starting point P12 away from the center C to... Figure 5 The line of the circumference of the first radius F12 of P10. Here, the second starting point P12 is arranged outside the first starting point P11 along the radial direction of the rotor core 210.

[0120] The shape of the outer peripheral surface of magnet 220 is used to reduce torque pulsation under high-speed conditions.

[0121] Figure 6 and Figure 7 It is a graph showing the torque pulsation generated under high-speed rotation conditions.

[0122] Reference Figure 6 and Figure 7 Along the outer peripheral surface of the magnet, including the magnet Figure 5 In the case of a motor formed by S11, such as Figure 6 Region A and Figure 7 As shown in region A, it can be determined that the noise increases significantly in the 800Hz frequency band. 800Hz represents the state where the motor is rotating at 2900 revolutions per minute (RPM), and it can be observed that torque pulsation increases significantly at high speeds.

[0123] Reference Figure 5 In order to reduce torque pulsation in the rotor according to the embodiment, the shape of the outer peripheral surface of the magnet 220 is changed to have a radius of curvature smaller than that of a conventional magnet, for example... Figure 5 S12.

[0124] Specifically, when the second radius F13 is 1, the magnet 220 can be designed such that the first radius F12 is in the range of 0.5 to 0.7. Here, the first radius F12 is the radius of curvature of the outer peripheral surface of the magnet 220, and the first radius F12 is derived from... Figure 5 The distance from the second starting point P12 to P. The second radius F13 corresponds to the radius of curvature of the inner circumferential surface of magnet 220.

[0125] For example, when from the center C of rotor core 210 to Figure 5 When the distance to P10 is 20 mm, the first radius F12 can be 11.2 mm, and the second radius F13 can be 17.2 mm. Therefore, the distance from the center C of the rotor core 210 to the second starting point P12 corresponds to 8.8 mm.

[0126] Under the above conditions, the measurement results of cogging torque and torque pulsation of the six-pole nine-slot motor are as follows.

[0127] Figure 8 This is a table that compares the cogging torque and torque ripple of the comparative example with those of the example.

[0128] Reference Figure 8 , Figure 8 MW represents the ratio of the second angle R12 to the first angle R11, and Figure 8 MOF refers to the distance from the center C of the rotor core 210 to the second starting point P12.

[0129] In the comparative example, the condition is that the ratio of the second angle R12 to the first angle R11 is 0.885, and the distance from the center C of the rotor core 210 to the second starting point P12 is 5.3 mm.

[0130] In the example case, the condition is that the ratio of the second angle R12 to the first angle R11 is 0.93, and the distance from the center C of the rotor core 210 to the second starting point P12 is 8.8 mm.

[0131] Under the above conditions, the cogging torque, torque pulsation, and torque measurement results of the comparative examples are as follows.

[0132] First, it is shown that there is no significant difference between the maximum torque of the comparative example and the maximum torque of the example. However, it is shown that the cogging torque and torque ripple are significantly reduced. In particular, it is shown that the high-speed torque ripple is significantly reduced from 0.1758 Nm (comparative example) to 0.0054 Nm (example). This is much lower than the target reduction in torque ripple.

[0133] Figure 9It is a graph showing the torque pulsation of the motor according to the first embodiment under high-speed rotation conditions.

[0134] Reference Figure 9 ,and Figure 7 Unlike region A, noise is significantly reduced in the 800Hz frequency band, and thus torque ripple is reduced.

[0135] Figure 10 It is a diagram illustrating the grooves of the teeth.

[0136] Reference Figure 1 and Figure 10 The stator 300 may include a stator core 300a and a coil 330.

[0137] The stator core 300a can be formed by stacking multiple plates in the form of thin steel sheets. Alternatively, the stator core 300a can be formed by joining or connecting multiple separate cores.

[0138] An annular yoke 310 can be disposed in the stator core 300a, and teeth 320 can be provided protruding from the yoke 310 toward the center of the stator core 300a. A coil 330 is wound around the teeth 320. Multiple teeth 320 can be arranged at regular intervals along the inner circumferential surface of the annular yoke 310. Although in Figure 3 The diagram shows a total of twelve teeth 320, but the invention is not limited to this and various modifications can be made according to the number of magnetic poles of the magnet 220.

[0139] The magnet 220 can be attached to the outer peripheral surface of the rotor core 210. The distal end of the tooth 320 is configured to face the magnet 220.

[0140] Reference Figure 10 The tooth 320 may include a body 321 and a sliding pad 322. Figure 1 The coil 330 is wound around the body 321. The sliding plate 322 is arranged at the far end of the body 321. The far end surface of the sliding plate 322 is arranged to face the magnet 220. Figure 1 The winding gap P of the coil 330 is formed between adjacent teeth 320. The slips of adjacent teeth 320 are arranged to be spaced apart from each other to form a slot opening (SO). SO is the inlet of the winding gap P, and the nozzle for winding the coil is inserted into SO. Here, the body 321 of the tooth 320 can be referred to as the first body.

[0141] The inner circumferential surface of the sliding pad 322 may include a groove 323. The groove 323 may be formed as a concave shape on the inner circumferential surface of the sliding pad 322. The shape of the groove 323 is shown as square, but the invention is not limited thereto. Furthermore, the groove 323 may be arranged along the axial direction of the stator core 310. In other words, the groove 323 may be arranged to be as long as it extends from the upper end of the stator core 310 along the height direction of the stator core 310 to the lower end.

[0142] Two slots, 323, can be installed. (See reference.) Figure 10 The two slots 323 can be arranged symmetrically based on the reference line L of the center of the width of the body 321 passing through the tooth 320 and the center C of the stator core 310. The slots 323 are used to correspond to SO that causes changes in magnetic flux density, thereby increasing the frequency of the cogging torque waveform per unit cycle and thus significantly reducing the cogging torque.

[0143] Figure 11 This is a table showing the number of main gear orders increased by the motor according to the first embodiment.

[0144] Reference Figure 11 In the case of a six-pole, nine-slot motor, the main cogging order corresponds to eighteen, which is the least common multiple of six and nine. Six represents the number of magnets 220, and nine represents the number of slots. Here, the main cogging order refers to the number of vibrations in the cogging torque waveform per unit rotation (one revolution) of the motor. The number of vibrations indicates the number of repetitions of the cogging torque waveform that forms a peak. Furthermore, the number of slots corresponds to the number of teeth 320.

[0145] In the case of a six-pole nine-slot motor with two slots 323, since the number of slots is considered to increase from nine to twenty-seven due to the two slots 323, the main gear order increases threefold from 18 to 54. As mentioned above, since the main gear order increases threefold due to the two slots 323, it means that the number of vibrations of the cogging torque waveform increases threefold, thus significantly reducing the cogging torque.

[0146] Figure 12 It is a diagram showing the width of the groove, and Figure 13a and Figure 13b The figure shows a curve illustrating how the cogging torque waveform varies with the width of the slot.

[0147] Reference Figure 12 and Figure 13a and 13bThe width W11 of slot 323 is set to be between 90% and 110% of the width W12 of SO. Here, the width W11 of slot 323 refers to the distance from one side end of the inlet of slot 323 in the circumferential direction of stator core 310 to the other side end of the inlet of slot 323. Here, the width W12 of SO refers to the distance from one side end of the inlet of SO in the circumferential direction of stator core 310 to the other side end of the inlet of SO.

[0148] like Figure 13a As shown, when the width W11 of slot 323 deviates from the width W12 of SO by 90% to 110%, the following problem occurs: the cogging torque waveform includes a stator component, that is, it includes the number of main cogging orders equal to the number of magnetic poles of magnet 220.

[0149] However, as Figure 13b As shown, when the width W11 of slot 323 is within 90% to 110% of the width W12 of SO, it can be determined that only the cogging torque waveform corresponding to the main tooth cogging order "54" is detected.

[0150] When the slot 323 is included in the sliding pad 322, under the condition that the rotor 200 is included but not skewed and the main tooth order is "9", there is a problem that the magnitude and distribution of the tooth cogging torque increase.

[0151] Figure 14 This is a diagram illustrating a sliding tile with an inner circumferential surface formed by a curved surface.

[0152] Reference Figure 14 According to the first embodiment, the motor 1 is configured such that the center of curvature of the inner peripheral surface of the sliding pad 322 is aligned with... Figure 2 The center C of the stator core 310 coincides with the center of the stator core 310. Specifically, the center of the imaginary circle O connecting the inner circumferential surfaces of the plurality of sliding tiles 322 coincides with the center of the stator core 310. Figure 2 The center C of the stator core 310 coincides.

[0153] Figure 15 This table compares the cogging torque of a motor in which the inner circumferential surface of the sliding pad is formed by a flat surface with the cogging torque of a motor in which the center of curvature of the inner circumferential surface of the sliding pad 322 coincides with the center of the stator core 310.

[0154] Figure 15 Column A represents the case where the inner circumferential surface of the sliding bearing is a flat surface in a motor comprising six magnetic poles and nine slots, and a rotor that is not skewed. Furthermore, Figure 15 Column B indicates the case where the center of curvature of the inner circumferential surface of the sliding bearing coincides with the center C of the stator core 310 in a motor that includes six magnetic poles and nine slots and a rotor that is not skewed.

[0155] Reference Figure 15 In column A, the cogging torque is significantly reduced at the 18th major tooth cogging order, but the problem is that the cogging torque increases more significantly at the 9th major tooth cogging order compared to the reference value.

[0156] Reference Figure 15 From column B, it can be determined that, compared with the reference value, the cogging torque has a reducing effect at the 18th primary tooth cogging order and even at the 9th primary tooth cogging order.

[0157] Figure 16 This table compares the deviation and output of the cogging torque of a motor in which the inner circumferential surface of the sliding pad is a flat surface with the deviation and output of the cogging torque of a motor in which the curvature center of the inner circumferential surface of the sliding pad 322 coincides with the center C of the stator core 310.

[0158] Figure 16 Column A represents the case where the inner circumferential surface of the sliding bearing is a flat surface in a motor comprising six magnetic poles and nine slots, and a rotor that is not skewed. Furthermore, Figure 16 Column B indicates the case where the center of curvature of the inner circumferential surface of the sliding pad coincides with the center C of the stator core 310 in a motor comprising six magnetic poles and nine slots, and a rotor that is not skewed.

[0159] Reference Figure 16 In column A, as the result of three sample tests, it can be observed that the deviation between the maximum value (0.0107 N / m) and the minimum value (0.0028 N / m) of the cogging torque is very large at the 9th main cogging order.

[0160] At the same time, refer to Figure 16 In column B, as the result of the three sample tests, it can be observed that the deviation between the maximum value (0.0012 N / m) and the minimum value (0.0003 N / m) of the cogging torque is not too large at the 9th main cogging order.

[0161] In addition, Figure 16 In column B, it can be determined that, with Figure 16 Compared to column A, the output increased by up to approximately 1%.

[0162] Figure 17 It is a graph showing the improvement state of cogging torque in the motor according to the first embodiment, corresponding to the main cogging order.

[0163] Figure 17 The red bar indicates the cogging torque when the inner circumferential surface of the sliding pad in a motor that includes six magnetic poles and nine slots, and a rotor that is not skewed, is a flat surface. Figure 17The blue bar indicates the cogging torque when the center of curvature of the inner circumferential surface of the sliding bearing in a motor comprising six magnetic poles and nine slots, and a rotor that is not skewed, coincides with the center C of the stator core 310.

[0164] Reference Figure 17 The cogging torque indicated by the red bar and the cogging torque indicated by the blue bar are not significantly different from each other at the 6th and 18th main tooth cogging orders. On the other hand, it can be determined that at the 9th main tooth cogging order, the cogging torque indicated by the blue bar is significantly reduced compared to the cogging torque indicated by the red bar, thus significantly improving the cogging torque reduction performance.

[0165] Figure 18 The diagram illustrates a motor according to the second embodiment, and Figure 19 This illustration shows a cross-sectional view of the motor according to the second embodiment. Figure 19 It is along Figure 18 The cross-sectional view taken from line AA. Figure 18 In this context, the y-direction refers to the axial direction, and the x-direction refers to the radial direction. Furthermore, the axial direction is perpendicular to the radial direction.

[0166] Reference Figure 18 and Figure 19 According to the second embodiment, the motor 1a may include a housing 1100, a cover 1200, a stator 1300 disposed on the inner side of the housing 1100, a rotor 1400 disposed on the inner side of the stator 1300, a shaft 1500 connected to the rotor 1400, and a sensing portion 1600. Here, "inner side" means a direction arranged radially toward the center C, and "outer side" means a direction opposite to the inner side.

[0167] The housing 1100 and the cover 1200 can form the external shape of the motor 1a. Here, the housing 1100 can be formed into a cylindrical shape with an opening formed on the upper part of the housing 1100.

[0168] The cover 1200 can be arranged to cover the open upper portion of the housing 1100.

[0169] Therefore, the housing 1100 is connected to the cover 1200 so that an accommodating space can be formed in the interior of the housing 1100. Furthermore, as... Figure 19 As shown, the stator 1300, rotor 1400, shaft 1500, and sensing part 1600 can be arranged in the accommodating space.

[0170] The housing 1100 can be formed in a cylindrical shape. A recess for accommodating the lower portion of the support shaft 1500 for the bearing 10 can be provided in the lower portion of the housing 1100. Furthermore, a recess for accommodating the upper portion of the support shaft 1500 for the bearing 10 can even be provided in a cover 1200, which is arranged in the upper portion of the housing 1100.

[0171] The stator 1300 can be supported on the inner circumferential surface of the housing 1200. Furthermore, the stator 1300 is arranged on the outer side of the rotor 1400. That is, the rotor 1400 can be arranged on the inner side of the stator 1300.

[0172] Figure 20 The illustration shows a cross-sectional view of the stator of the motor according to the second embodiment, and Figure 21 It's a diagram. Figure 20 A magnified view of region A1.

[0173] Reference Figures 18 to 21 The stator 1300 may include a stator core 1310, a coil 1320 wound around the stator core 1310, and an insulator 1330 disposed between the stator core 1310 and the coil 1320.

[0174] The coil 1320 that forms the rotating magnetic field can be wound around the stator core 1310. Here, the stator core 1310 can be formed by a single core or by connecting multiple separate cores.

[0175] Furthermore, the stator core 1310 can be formed by stacking multiple plates in the form of thin steel sheets, but the invention is not limited thereto. For example, the stator core 1310 can be formed from a single article.

[0176] The stator core 1310 may include a yoke 1311 and a plurality of teeth 1312.

[0177] The yoke 1311 can be formed in a cylindrical shape. Therefore, the yoke 1311 may include an annular cross-section.

[0178] The teeth 1312 can be arranged to project radially (x-direction) from the yoke 1311 based on a center C. Furthermore, a plurality of teeth 1312 can be arranged to be spaced apart from each other circumferentially on the inner circumferential surface of the yoke 1311. Therefore, slots can be formed between the teeth 1312, in which a coil 1320 can be wound. In this case, the teeth 1312 can be set to twelve teeth, but the invention is not necessarily limited thereto.

[0179] The tooth 1312 can be arranged to face the magnet 1420 of the rotor 1400. In this case, the inner surface 1314a of the tooth 1312 is arranged to be radially spaced from the outer peripheral surface of the magnet 1420 by a predetermined distance. Here, the inner surface 1314a can be formed with a predetermined curvature 1 / R20 based on the center C of the motor 1a. Therefore, the length of the inner surface 1314a can be obtained by a formula used to calculate the length of an arc.

[0180] The coil 1320 is wound around each tooth in the tooth 1312.

[0181] Reference Figure 20 The tooth 1312 may include a body portion 1313 wound by a coil 1320, a protrusion 1314 disposed on an end portion of the body portion 1313, and a groove 1315 formed as a concave shape on the inner surface 1314a of the protrusion 1314. In this case, the protrusion 1314 may include a first region 1314c and a second region 1314d, with a first surface 1314b formed in the first region 1314c and the second region 1314d protruding inward from the first region 1314c in a radial direction. Here, the body portion 1313 may be referred to as the body, and the protrusion 1314 may be referred to as a sliding piece.

[0182] The body portion 1313 can be arranged to protrude from the yoke 1311 in the radial direction (x direction) based on the center C. Furthermore, the body portions 1313 can be arranged to be spaced apart from each other in the circumferential direction on the inner circumferential surface of the yoke 1311.

[0183] In addition, coil 1320 can be wound around body portion 1313.

[0184] The protrusion 1314 may extend inward from the end portion of the body portion 1313.

[0185] Reference Figure 20 and 21 The protrusions 1314 are arranged spaced apart from each other so that an opening can be formed on the inner side of the slot. Here, the opening means SO. For example, SO can refer to the space between one end of the protrusion 1314 of one of the plurality of teeth 1312 and the other end of the protrusion 1314 of another tooth 1312 adjacent to the aforementioned tooth 1312.

[0186] Therefore, SO means the space between the end point P20 of one protrusion 1314 and the end point P20 of another protrusion 1314 arranged adjacent to the aforementioned one protrusion 1314. SO can be arranged with a predetermined distance W21. The distance W21 of SO can be referred to as the distance between the protrusions 1314 or as the width of SO.

[0187] like Figure 20 As shown, the protrusion 1314 may include a first region 1314c and a second region 1314d based on the radial direction, with a first surface 1314b formed in the first region 1314c. Furthermore, a groove 1315 may be formed in the second region 1314d, which includes an inner surface 1314a and a second surface 1314e. Here, the inner surface 1314a of the protrusion 1314 may be formed with a predetermined curvature 1 / R20 based on the center C of the motor 1a.

[0188] In addition, the side surface of the protrusion 1314 may include a first surface 1314b extending from the body portion 1313 and a second surface 1314e extending from the first surface 1314b.

[0189] The first surface 1314b of the first region 1314c can be formed to have a first tilt angle θ1 relative to the side surface 1313a of the body portion 1313. Furthermore, the second surface 1314e of the second region 1314d can be formed to have a second tilt angle θ2 relative to the first surface 1314b.

[0190] The first tilt angle θ1 can be an obtuse angle on the outer side between the side surface 1313a and the first surface 1314b of the body portion 1313. Furthermore, the second tilt angle θ2 can be an obtuse angle on the inner side between the first surface 1314b and the second surface 1314e.

[0191] In this case, the first tilt angle θ1 may be different from the second tilt angle θ2, but the present invention is not limited to this. For example, considering the performance of the motor 1a due to the tooth 1312 and the cogging torque, the first tilt angle θ1 and the second tilt angle θ2 may be the same tilt angle.

[0192] The first region 1314c is the region connected to the end portion of the body portion 1313, and the first region 1314c may include first surfaces 1314b formed on both sides in the circumferential direction. Figure 20 As shown, the first region 1314c is arranged between the body portion 1313 and the second region 1314d.

[0193] Reference Figure 20 and Figure 21 The first tilt angle θ1 between the body portion 1313 and the protrusion 1314 can be in the range of 145° to 155°. For example... Figure 21 As shown, the first tilt angle θ1 between the side surface 1313a of the body portion 1313 and the first surface 1314b of the protrusion 1314 can be in the range of 145° to 155°.

[0194] Figure 22It is a graph showing how the cogging torque varies with the angle between the body portion and the protrusion of the stator core, which is arranged in a motor according to the second embodiment.

[0195] Reference Figure 22 It can be observed that the cogging torque decreases significantly in the range of 145° to 155° between the first tilt angle θ1 between the side surface 1313a of the body portion 1313 and the first surface 1314b of the protrusion 1314.

[0196] Figure 23 The diagram shows a curve illustrating how the cogging torque waveform varies according to a first tilt angle between the body portion and the protrusion of the stator core arranged in the motor according to the second embodiment.

[0197] When the first tilt angle θ1 between the side surface 1313a of the body portion 1313 and the first surface 1314b of the protrusion 1314 changes from 145° to 155°, it can be determined that the amplitude of the cogging torque waveform gradually decreases.

[0198] The second region 1314d is the portion of the protrusion 1314 that extends inward from the first region 1314c. The second region 1314d may include an inner surface 1314a and a second surface 1314e, and a groove 1315 is formed on the inner surface 1314a.

[0199] In this case, the second region 1314d can be formed with a predetermined length L20.

[0200] The length L20 can be the length of the second surface 1314e. Specifically, the length L20 can be set to the length from the inner edge of the first surface 1314b to the edge of one side of the inner surface 1314a.

[0201] Furthermore, the radial length L20 of the second surface 1314e can be 1 / 4 of the SO distance W21. In this case, the length L20 can be referred to as the depth of the protrusion 1314.

[0202] The groove 1315 can be formed to be concave outward in the radial direction on the inner surface 1314a.

[0203] like Figure 20 and Figure 21 As described above, two cross-sections of the groove 1315 in the axial direction perpendicular to the shaft 1500 have been shown as two examples of rectangular shapes, but the invention is not necessarily limited thereto. For example, considering the cogging torque, the groove 1315 can be formed as one groove 1315 or two or more grooves 1315. Alternatively, the groove 1315 can be formed as a semi-circular shape with a predetermined radius or as a parabolic shape.

[0204] Reference Figure 21 The groove 1315 can be formed into a quadrilateral shape having a predetermined width W22 based on the circumferential direction and a predetermined depth D based on the radial direction.

[0205] The two slots 1315 can be symmetrically arranged based on a baseline CL that passes through the center of the circumferential width of the protrusion 1314 and the center of the body portion 1313.

[0206] Furthermore, the first distance L21 between the grooves 1315 formed on the inner surface 1314a in the circumferential direction can be equal to the second distance L22 from one end of the protrusion 1314 to the groove 1315. In this case, the first distance L21 and the second distance L22 can be the distance between the inner surfaces 1314a in the circumferential direction.

[0207] Due to the width W22 of slot 1315, the cogging torque of motor 1a can be reduced.

[0208] The width W22 of the groove 1315 can be 0.85 to 1.1 times the distance between one end of a protrusion 1314 of the plurality of teeth 1312 and one end of another protrusion 1314 of the plurality of teeth 1312 adjacent to the aforementioned protrusion 1314. For example, the width W22 of the groove 1315 can be 0.85 to 1.1 times the distance W21 formed between the protrusions 1314. That is, this can be expressed as distance W21:width W22 = 1:0.85 to 1.1.

[0209] Figure 24 This is a table showing the variation of cogging torque and torque when the width of the slot in the motor according to the second embodiment is 0.85 to 0.95 times the width of SO. Figure 25 This is a graph showing the cogging torque when the width of the slot in the motor according to the second embodiment is 0.85 to 0.95 times the width of SO. Figure 26 It is a graph showing the cogging torque waveform of a motor in a comparative example, and Figure 27 This is a graph showing the cogging torque waveform of the motor according to the second embodiment when the width of the slot is 0.9 times the width of SO. Here, as a comparative example, the motor is configured such that the width of SO is equal to the width of the slot, and both the width of SO and the width of the slot can be set to 2 mm. Furthermore, the depth of the slot is 0.5 mm. In this case, Figure 25 The value of 43.8mN represents the cogging torque of the motor in the comparison example.

[0210] The width W22 of the groove 1315 can be formed in the range of 0.85 to 0.95 times the distance W21 of SO. That is, this can be expressed as distance W21:width W22 = 1:0.85 to 0.95.

[0211] Reference Figure 24 and Figure 25 Compared to the motor in the comparative example, the cogging torque of the motor 1a according to the second embodiment can be reduced by a maximum of 14.6% (W22 = 1.8 mm). For example, it can be determined that the cogging torque of the motor 1a decreases until the width W22 of the slot 1315 of the motor 1a reaches 1.8 mm and then increases again. In this case, it can be determined that the torque of the motor 1a according to the second embodiment does not change much compared to the torque of the motor in the comparative example, which is 5.94 Nm.

[0212] Figure 26 It is a graph showing the pulsation (repetitive torque waveform) of the cogging torque of the motor in the comparative example, and Figure 27 This is a graph showing the pulsation (repetitive torque waveform) of the cogging torque of the motor according to the second embodiment. (Refer to...) Figure 26 and Figure 27 It can be determined that the amplitude between the maximum and minimum values ​​of the cogging torque of motor 1a is smaller than the amplitude between the maximum and minimum values ​​of the cogging torque of the motor in the comparative example.

[0213] Figure 28 This is a table showing the changes in cogging torque and torque when the width of the slot in the motor according to the second embodiment is 1.05 to 1.1 times the width of SO. Figure 29 This is a graph showing the variation of cogging torque when the width of the slot in the motor according to the second embodiment is 1.05 to 1.1 times the width of SO. Figure 30 This is a graph showing the cogging torque waveform of the motor according to the second embodiment when the width of the slot is 1.1 times the width of SO.

[0214] The width W22 of the groove 1315 can be formed in the range of 1.05 to 1.1 times the distance W21 of SO. That is, this can be expressed as distance W21:width W22 = 1:1.05 to 1.1.

[0215] Reference Figure 28 and Figure 29Compared to the motor in the comparative example, the cogging torque of the motor 1a according to the second embodiment can be reduced by up to 66.7% (W2 = 2.2 mm). For example, it can be determined that the cogging torque of the motor 1a decreases until the width W22 of the slot 1315 of the motor 1a reaches 2.2 mm and then increases again. In this case, it can be determined that the torque of the motor 1a according to the second embodiment does not change much compared to the torque of the motor in the comparative example, which is 5.94 Nm.

[0216] Figure 30 This is a graph showing the pulsation (repetitive torque waveform) of the cogging torque of the motor according to the second embodiment. (Refer to...) Figure 26 and Figure 30 It can be determined that the amplitude between the maximum and minimum values ​​of the cogging torque of motor 1a is smaller than the amplitude between the maximum and minimum values ​​of the cogging torque of the motor in the comparative example.

[0217] Therefore, when the width W22 of the groove 1315 is 1.05 to 1.1 times the distance between one end of a protrusion 1314 of a plurality of teeth 1312 and one end of another protrusion 1314 of a plurality of teeth 1312 adjacent to the aforementioned protrusion 1314, the cogging torque is effectively reduced, thereby improving the quality of the motor 1a.

[0218] Specifically, the cogging torque of motor 1a is reduced to the maximum extent when the width W22 of slot 1315 is 2.2 mm. That is, the cogging torque of motor 1a is reduced to the maximum extent when the width W22 of slot 1315 is 1.1 times the distance W21 of SO.

[0219] Due to the depth D of the slot 1315, the cogging torque of the motor 1a can be reduced.

[0220] The depth D of the groove 1315 can be 0.7 to 1.3 times the radial length L20 of the second surface 1314e. For example, the depth D of the groove 1315 can be formed in the range of 0.7 to 1.3 times the length L20 from the edge of one side of the first surface 1314b of the protrusion 1314 to the inner surface 1314a. That is, this can be expressed as length L20:depth D = 1:0.7 to 1.3.

[0221] Furthermore, since the radial length L20 of the second surface 1314e can be set to 1 / 4 of the distance W21 of SO, the radial depth D of the groove 1315 can be formed to be 0.175 to 0.325 times the distance W21 of SO formed between the protrusions 1314.

[0222] Figure 31This table shows the variation of cogging torque and torque when the depth of the slot in the motor according to the second embodiment is 0.7 to 0.9 times the length of the second surface in the radial direction. Figure 32 This is a graph showing the cogging torque when the depth of the slot in the motor according to the second embodiment is 0.7 to 0.9 times the length of the second surface in the radial direction. Figure 33 This is a graph showing the cogging torque waveform when the depth of the slot in the motor according to the second embodiment is 0.9 times the radial length of the second surface. Here, the motor provided as a comparative example has a protrusion depth equal to the slot depth, and the length of the second surface and the slot depth can be set to 0.5 mm. In this case, Figure 32 The value of 43.8mN represents the cogging torque of the motor in the comparison example.

[0223] The depth D of the groove 1315 can be formed in the range of 0.7 to 0.9 times the distance L20 from the second surface 1314e. That is, this can be expressed as length L20:depth D = 1:0.7 to 0.9.

[0224] Furthermore, when the length L20 of the second surface 1314e is 1 / 4 of the distance W21 of SO, the depth D of the groove 1315 can be formed in the range of 0.175 times to 0.225 times the distance W21 of SO.

[0225] Reference Figure 31 and Figure 32 Compared to the motor in the comparative example, the cogging torque of the motor 1a according to the second embodiment can be reduced to a maximum of 37.9% (D = 0.45 mm). For example, it can be determined that the cogging torque of the motor 1a decreases until the depth D of the slot 1315 of the motor 1a reaches 0.45 mm and then increases again. In this case, it can be determined that the torque of the motor 1a according to the second embodiment does not change much compared to the torque of the motor in the comparative example, which is 5.94 Nm.

[0226] Figure 33 This is a graph showing the pulsation (repetitive torque waveform) of the cogging torque of the motor according to the second embodiment. (Refer to...) Figure 26 and Figure 33 It can be determined that the amplitude between the maximum and minimum values ​​of the cogging torque of motor 1a is smaller than the amplitude between the maximum and minimum values ​​of the cogging torque of the motor in the comparative example.

[0227] Figure 34 This table shows the variation of cogging torque and torque when the depth of the slot in the motor according to the second embodiment is 1.1 to 1.3 times the length of the second surface in the radial direction. Figure 35This is a graph showing the cogging torque when the depth of the slot in the motor according to the second embodiment is 1.1 to 1.3 times the length of the second surface in the radial direction. Figure 36 It is a graph showing the cogging torque waveform when the depth of the slot in the motor according to the second embodiment is 1.3 times the length of the second surface in the radial direction.

[0228] The depth D of the groove 1315 can be formed in the range of 1.1 to 1.3 times the distance L20 from the second surface 1314e. That is, this can be expressed as length L20:depth D = 1:1.1 to 1.3.

[0229] Furthermore, when the length L20 of the second surface 1314e is 1 / 4 of the distance W21 of SO, the depth D of the groove 1315 can be formed in the range of 0.275 times to 0.325 times the distance W21 of SO.

[0230] Reference Figure 34 and Figure 35 Compared to the motor in the comparative example, the cogging torque of the motor 1a according to the second embodiment can be reduced by a maximum of 42.0% (D = 0.65 mm). For example, it can be determined that the cogging torque of the motor 1a decreases until the depth D of the slot 1315 of the motor 1a reaches 0.65 mm and then increases again. In this case, it can be determined that the torque of the motor 1a according to the second embodiment does not change much compared to the torque of the motor in the comparative example, which is 5.94 Nm.

[0231] Figure 36 This is a graph showing the pulsation (repetitive torque waveform) of the cogging torque of the motor according to the second embodiment. (Refer to...) Figure 26 and Figure 36 It can be determined that the amplitude between the maximum and minimum values ​​of the cogging torque of motor 1a is smaller than the amplitude between the maximum and minimum values ​​of the cogging torque of the motor in the comparative example.

[0232] Figure 37 This table shows the changes in cogging torque and torque when the groove depth in the motor according to the second embodiment is 0.65 mm and the groove width is 0.85 to 1.1 times the width of SO. Figure 38 This is a graph showing the cogging torque when the groove depth in the motor according to the second embodiment is 0.65 mm and the groove width is 0.85 to 1.1 times the width of SO. Figure 39 It is a graph showing the cogging torque waveform when the depth of the slot in the motor according to the second embodiment is 0.65 mm and the width of the slot is 1.1 times the width of SO.

[0233] like Figure 34 and Figure 35 As shown, when the depth D of groove 1315 is 0.65 mm, the cogging torque is minimized as much as possible. Therefore, as Figures 37 to 39 As shown, the cogging torque of motor 1a can be determined based on the case where the depth D of groove 1315 is 0.65 mm, depending on the variation of the width W22 of groove 1315. That is, the depth D of groove 1315 of motor 1a is fixed, and therefore the cogging torque and the torque due to the variation of the width W22 of groove 1315 and the critical value can be determined. In this case, the distance W21 of SO can be 2 mm, and the length L20 of the second surface 314e, i.e., the depth of the protrusion 1314, can be 0.5 mm.

[0234] Reference Figure 37 and Figure 38 Compared to the motor in the comparative example, the cogging torque of the motor 1a according to the second embodiment can be reduced by a maximum of 53.0% (W2 = 2.2 mm). For example, it can be determined that the cogging torque of the motor 1a decreases until the width W22 of the slot 1315 of the motor 1a reaches 2.2 mm and then increases again. In this case, it can be determined that the torque of the motor 1a according to the second embodiment does not change much compared to the torque of the motor in the comparative example, which is 5.94 Nm.

[0235] Figure 39 This is a graph showing the pulsation (repetitive torque waveform) of the cogging torque of the motor according to the second embodiment. (Refer to...) Figure 26 and Figure 39 It can be determined that the amplitude between the maximum and minimum values ​​of the cogging torque of motor 1a is smaller than the amplitude between the maximum and minimum values ​​of the cogging torque of the motor in the comparative example.

[0236] Figure 40 This table shows the variation of cogging torque and torque when the width of the slot in the motor according to the second embodiment is 2.2 mm and the depth of the slot is 0.7 to 1.3 times the length of the second surface in the radial direction. Figure 41 This is a graph showing the cogging torque when the width of the slot in the motor according to the second embodiment is 2.2 mm and the depth of the slot is 0.7 to 1.3 times the length of the second surface in the radial direction. Figure 42 It is a graph showing the cogging torque waveform when the width of the slot in the motor according to the second embodiment is 2.2 mm and the depth of the slot is 1.3 times the length of the second surface in the radial direction.

[0237] like Figure 28 and Figure 29 As shown, when the width W22 of the groove 1315 is 2.2 mm, the cogging torque is minimized as much as possible. Therefore, as Figures 40 to 42As shown, the cogging torque of motor 1a can be determined based on the case where the width W22 of groove 1315 is 2.2 mm, depending on the variation of groove depth D. That is, the width W22 of groove 1315 of motor 1a is fixed, and therefore the cogging torque and the torque variation due to groove depth D and critical value can be determined. In this case, the distance W21 of SO can be 2 mm, and the length L20 of the second surface 314e, i.e., the depth of protrusion 1314, can be 0.5 mm.

[0238] Reference Figure 40 and Figure 41 Compared to the motor in the comparative example, the cogging torque of the motor 1a according to the second embodiment can be reduced by a maximum of 53.4% ​​(D = 0.65 mm). For example, it can be determined that the cogging torque of the motor 1a decreases until the depth D of the slot 1315 of the motor 1a reaches 0.65 mm and then increases again. In this case, it can be determined that the torque of the motor 1a according to the second embodiment does not change much compared to the torque of the motor in the comparative example, which is 5.94 Nm.

[0239] Figure 42 This is a graph showing the pulsation (repetitive torque waveform) of the cogging torque of the motor according to the second embodiment. (Refer to...) Figure 26 and Figure 42 It can be determined that the amplitude between the maximum and minimum values ​​of the cogging torque of motor 1a is smaller than the amplitude between the maximum and minimum values ​​of the cogging torque of the motor in the comparative example.

[0240] Therefore, it can be determined that the large variation in the cogging torque of motor 1a is due to the width W22 of groove 1315 rather than the depth D of groove 1315. Therefore, motor 1a can preferably reduce the cogging torque by adjusting the size of the width W22 of groove 1315 rather than the size of the depth D of groove 1315.

[0241] Furthermore, in motor 1a, when the width W22 of groove 1315 is 2.2 mm and the depth D of groove 1315 is 0.65 mm, the cogging torque is reduced by as much as possible by 53.4%. That is, in motor 1a, when the width W22 of groove 1315 is 1.1 times the distance W21 of SO and the depth D of groove 1315 is 1.3 times the depth of protrusion 1314, the cogging torque is reduced as much as possible.

[0242] Here, the length L20 of the second surface 1314e can be set to the length from the inner edge of the first surface 1314b to the edge of one side of the inner surface 1314a. Furthermore, since the length L20 can be 1 / 4 of the distance W21 of SO, the cogging torque is minimized as much as possible when the depth D of the groove 1315 is 0.325 times the distance W21 of SO.

[0243] Meanwhile, the width W22 of the groove 1315 can be 0.85 to 1.1 times the distance W21 of SO formed between the protrusions 1314, and the depth D of the groove 1315 can be 0.7 to 1.3 times the length L20 of the second surface.

[0244] When the depth D of the slot 1315 is 0.65 mm and the width W22 of the slot 1315 is in the range of 2.1 mm to 2.2 mm, the cogging torque of the motor 1a is significantly reduced.

[0245] The ratio of the width W22 to the depth D of the groove 1315 can be in the range of 3.23 to 3.38. Therefore, when the width W22 of the groove 1315 is 3.23 to 3.38 times the depth D of the groove 1315, the cogging torque of the motor 1a is optimally reduced. That is, this can be expressed as the depth D:width W22 of the groove 1315 = 1:3.23 to 3.38.

[0246] Insulator 1330 isolates stator core 1310 from coil 1320. Therefore, insulator 1330 can be arranged between stator core 1310 and coil 1320.

[0247] Therefore, the coil 1320 can be wound around the teeth 1312 of the stator core 1310, and the insulator 1330 is arranged in the stator core 1310.

[0248] The rotor 1400 is arranged on the inner side of the stator 1300. Furthermore, the rotor 1400 may include a hole in its central portion into which the shaft 1500 is inserted. Thus, the shaft 1500 can be coupled to a slot in the rotor 1400.

[0249] Reference Figure 19 The rotor 1400 may include a rotor core 1410 and a magnet 1420 disposed on the outer peripheral surface of the rotor core 1410.

[0250] The rotor 1400 can be classified into the following types according to the connection method between the rotor core 1410 and the magnet 1420.

[0251] like Figure 19 As shown, the rotor 1400 can be implemented in a type in which the magnet 1420 is coupled to the outer peripheral surface of the rotor core 1410. In this type of rotor 1400, to prevent the magnet 1420 from separating and to increase the coupling force, a separate can assembly (not shown) can be coupled to the rotor core 1410. Alternatively, the rotor 1400 can be integrally formed with the magnet 1420 and the rotor core 1410 by dual injection of the magnet 1420 and the rotor core 1410.

[0252] Alternatively, the rotor 1400 can be implemented in a type in which the magnet 1420 is coupled to the interior of the rotor core 1410. This type of rotor 1400 can be provided with a recess into which the magnet 1420 is inserted in the rotor core 1410.

[0253] The rotor core 1410 can be formed by stacking multiple plates in the form of thin steel sheets. Alternatively, the rotor core 1410 can be manufactured as a single core comprising a single cylindrical section.

[0254] Alternatively, the rotor core 1410 can be made in a form in which multiple pucks (unit cores) forming a skew angle are stacked.

[0255] Alternatively, the rotor core 1410 may include a hole formed to allow the shaft 1500 to be inserted into it.

[0256] The magnet 1420 can be configured to have eight magnets 1420, but the present invention is not limited to this.

[0257] Shaft 1500 can be connected to rotor 1400. When electromagnetic interaction is generated in rotor 1400 and stator 1300 through current supply, rotor 1400 rotates, and therefore shaft 1500 rotates by rotational interlock with rotor 1400. In this case, shaft 1500 can be supported on bearing 10.

[0258] Shaft 1500 can be connected to the vehicle's steering shaft. Therefore, the steering shaft can receive power due to the rotation of shaft 1500.

[0259] The sensing unit 1600 can detect the magnetic force of a sensing magnet that is installed to interlock with the rotor 1400 in a rotatable manner to determine the current position of the rotor 1400, thereby detecting the rotational position of the shaft 1500.

[0260] The sensing section 1600 may include a sensing magnet assembly 1610 and a PCB 1620.

[0261] The sensing magnet assembly 1610 is coupled to the shaft 1500 to be interlocked with the rotor 1400 to detect the position of the rotor 1400. In this case, the sensing magnet assembly 1610 may include a sensing magnet and a sensing plate. The sensing magnet may be coaxially coupled to the sensing plate.

[0262] The sensing magnet may include a main magnet and a secondary magnet. The main magnet is adjacent to an arrangement of holes forming an inner circumferential surface in the circumferential direction, and the secondary magnet is formed at the edge of the main magnet. The main magnet may be arranged in the same manner as the drive magnet inserted into the rotor 1400 of the motor. The secondary magnet is more subdivided than the main magnet and includes a number of magnetic poles. Therefore, the rotation angle can be further subdivided and measured, and the motor drive can be made smoother.

[0263] The sensing plate can be formed of a disc-shaped metal material. A sensing magnet can be attached to the upper surface of the sensing plate. Furthermore, the sensing plate can be attached to a shaft 1500. Here, a hole through which the shaft 1500 passes is formed in the sensing plate.

[0264] A sensor for detecting the magnetic force of a sensing magnet can be mounted on a PCB 1620. In this case, the sensor can be configured as a Hall IC. Furthermore, the sensor can generate a sensing signal by detecting changes in the north and south poles of the sensing magnet.

[0265] Although described with reference to embodiments of the invention, it should be understood that those skilled in the art can devise various alternatives and modifications of the invention without departing from the spirit and scope of the invention as defined by the appended claims. Furthermore, any differences relating to these various alternatives and modifications should be interpreted as falling within the scope of the invention as defined by the appended claims.

[0266] Description of reference numerals in the attached figures

[0267] 100 and 1500: Shaft; 200 and 1400: Rotor; 210 and 1410: Rotor core; 220 and 1420: Magnet; 300 and 1300: Stator; 310 and 1310: Stator core; 320 and 1320: Gear; 321: Body; 322 and 1314: Slipper; 323 and 1315: Slot; 330 and 1330: Coil

Claims

1. A motor, comprising: axis; Rotor, the shaft being connected to the rotor; as well as The stator is arranged on the outer side of the rotor. The stator includes a stator core with multiple teeth and a coil wound around each of the teeth. The rotor includes a rotor core and a plurality of magnets arranged on the outer peripheral surface of the rotor core. Each tooth in the tooth includes a body portion around which the coil is wound, a protrusion disposed on an end portion of the body portion, and two grooves formed as concave shapes on the inner surface of the protrusion. The side surface of the protrusion includes a first surface extending from the body portion and a second surface extending from the first surface; The depth (D) of the groove is 0.7 to 1.3 times the radial length (L20) of the second surface. The rotor's magnets are configured to be eight magnets; The teeth of the stator are configured to be twelve teeth; The slot is configured to be spaced apart from a baseline (CL) passing through the center of the body portion; and The length (L20) of the second surface in the radial direction is 1 / 4 of the distance (W21) between an end of the first protrusion of one of the plurality of teeth and an end of the second protrusion of another tooth adjacent to the end of the first protrusion of the tooth.

2. The motor according to claim 1, wherein: Each magnet has an inner peripheral surface that contacts the outer peripheral surface of the rotor core, and when the angle formed by dividing the outer peripheral surface of the rotor core by the number of magnets is called a first angle, the magnet has a second angle between a first extension line and a second extension line, the first extension line and the second extension line extending from the two endpoints of the inner peripheral surface of the magnet to the center point of the rotor core in the transverse cross-section of the rotor core and the magnets. The ratio of the second angle to the first angle is in the range of 0.92 to 0.

95.

3. The motor according to claim 2, wherein, When the radius of curvature of the outer peripheral surface of the magnet is referred to as the first radius, and the radius of curvature of the inner peripheral surface of the magnet is referred to as the second radius, the rotor has a ratio of the first radius to the second radius in the range of 0.5 to 0.7 on the rotor core and the transverse cross section of the magnet.

4. The motor according to claim 3, wherein, The cogging torque waveform has multiple vibrations, the number of which is three times the least common multiple of the number of magnets and the number of teeth per unit rotation period.

5. The motor according to claim 1, wherein, The ratio of the width (W22) of the groove to the depth (D) of the groove is in the range of 3.23 to 3.

38.

6. The motor according to claim 5, wherein, The depth (D) of the groove is 0.175 to 0.325 times the distance (W21).

7. The motor according to claim 1, wherein, The groove has a quadrilateral shape in its cross-section perpendicular to the axial direction of the shaft.

8. The motor according to claim 7, wherein, The two grooves are arranged symmetrically based on the baseline (CL), which passes through the center of the circumferential width of the protrusion and the center of the body portion.

9. The motor according to claim 7, wherein, The first distance (L21) between the grooves is equal to the second distance (L22) from one end of the protrusion to the groove.

10. The motor according to claim 2, wherein, The first surface has a first tilt angle (θ1) relative to the side surface of the body portion, and the second surface has a second tilt angle (θ2) relative to the first surface. The first tilt angle (θ1) is an exterior angle, and the second tilt angle (θ2) is an interior angle. The first tilt angle (θ1) is in the range of 145° to 155°.

11. The motor according to claim 1, wherein, The center of curvature of the inner circumferential surface of the protrusion coincides with the center of curvature of the stator core.

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