KR20190084786A - Motor - Google Patents

Abstract

An embodiment relates to a motor comprising: a housing; a stator disposed within the housing; a rotor disposed within the stator; a shaft coupled to the rotor; and a cover disposed on the upper side of the housing. The stator includes: a stator core including a yoke and a plurality of teeth protruding radially from the yoke; and a coil wound around the teeth. The rotor includes: a rotor core; a magnet disposed on the outer circumferential surface of the rotor core; and a shield disposed on an outer side of the magnet. The magnet is disposed to be spaced apart from the teeth by a predetermined interval (G), and the width (W) of the shield is 0.07 to 0.3 of the interval (G). Thus, the quality of the motor can be improved by reducing cogging torque and torque ripple.

Description

Motor {Motor}

An embodiment relates to a motor.

A motor is a device that obtains rotational force by converting electrical energy into mechanical energy. It is widely used in automobiles, home electronics, and industrial devices.

In particular, an electronic power steering system (hereinafter referred to as EPS) in which the above-described motor is used is driven by an electronic control unit according to operating conditions to ensure turning stability and provide quick restoring force Thereby enabling the driver to drive safely.

The motor may include a housing, a shaft, a stator disposed on an inner circumferential surface of the housing, a rotor installed on an outer circumferential surface of the shaft, and the like. Here, the stator of the motor induces electrical interaction with the rotor to induce rotation of the rotor.

The stator may include a stator core and a coil wound around the stator core.

The stator core may include a plurality of tooters forming a plurality of slots, and the rotor may include a plurality of magnets arranged to face the teeth. Here, adjacent teeth are disposed apart from each other to form a slot opening. The slot opening may be formed to prevent leakage of an adjacent intertus flux.

Fig. 1 is a view showing a magnetic flux of a stator core and a rotor disposed in a motor which is a comparative example, and Fig. 2 is a view showing area A in Fig.

Referring to FIG. 1, the motor 2, which is a comparative example, may include a stator core 10 and a rotor 20. Here, the stator core 10 may include a plurality of teeth 12 protruding in the radial direction from the yoke 11 and the yoke 11. The rotor 20 may include a rotor core 21 and a magnet 22.

However, when the magnetic flux of the magnet 22 is linked to the tooth 12 of the stator core 10 by the rotation of the rotor 20, there is a problem that the magnetic flux is uneven in one region of the tooth 12 .

As shown in Fig. 2, as the magnetic flux of the magnet connected to the tooth A leaks, the saturation phenomenon occurs in the area A1 of the tooth B and the tooth C arranged adjacent to the tooth A, respectively. That is, as the number of magnetic lines of force increases due to the leakage magnetic flux, there is a problem that unevenness of the magnetic flux occurs in the neighboring teeth.

Accordingly, the unevenness of the magnetic flux affects the cogging torque and the torque ripple of the motor, thereby deteriorating the quality of the motor.

The embodiment provides a motor that can improve the quality by reducing the cogging torque and the torque ripple.

The problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned here can be understood by those skilled in the art from the following description.

According to an embodiment of the present invention, A stator disposed in the housing; A rotor disposed within the stator; A shaft engaged with the rotor; And a cover disposed on the top of the housing, wherein the stator includes a stator core including a yoke and a plurality of teeth protruding radially from the yoke, and a coil wound around the tooth, A magnet disposed on an outer circumferential surface of the rotor core, and a shield disposed on an outer side of the magnet, wherein the magnet is spaced apart from the tooth by a predetermined gap G, 0.0 > to 0.3 < / RTI > of the gap (G).

The outer surface of the magnet may be a curved surface whose central portion protrudes toward the outside as compared with the edge region.

The distance may be a radial distance from the center C1 of the outer surface to the inner surface of the tooth.

Further, the shield may be a magnetic body.

The magnetic flux density of the shield may be 1.4 to 2.2 of the magnetic flux density of the magnet.

The inner circumferential surface of the shield may be in contact with the outer surface of the magnet.

Meanwhile, the magnet of the motor is provided in six, and the tooth may be provided in nine.

The motor according to the embodiment having the above-described configuration can improve the quality of the motor by limiting the width of the can formed on the basis of the distance between the inner circumferential surface of the tooth and the outer surface of the magnet, thereby reducing cogging torque and torque ripple.

Further, the shield is provided as a magnetic body so that magnetic flux is linked to the tooth, so that leakage of the magnetic flux can be prevented.

In addition, the magnetic flux density of the shield is limited based on the magnetic flux density of the magnet, thereby further improving the quality of the motor.

1 is a view showing a magnetic flux of a stator core and a rotor disposed in a motor as a comparative example,
Fig. 2 is a view showing area A in Fig. 1,
3 is a view showing a motor according to an embodiment,
4 is a cross-sectional view showing the line AA in Fig. 3,
Fig. 5 is a view showing the arrangement relationship of the stator core and the rotor of the motor according to the embodiment,
6 is a view showing a stator and a rotor in a region B in Fig. 5,
7 is a view showing magnetic force lines disposed in a stator core and a rotor of a motor according to an embodiment,
8 is a graph showing the cogging torque of the motor according to the embodiment,
9 is a graph showing the torque ripple of the motor according to the embodiment,
10 is a table showing the cogging torque and the change rate of the motor according to the embodiment,
11 is a table showing the torque ripple and rate of change of the motor according to the embodiment,
12 is a table showing the torque of the motor according to the embodiment.

The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated and described in the drawings. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms including ordinal, such as second, first, etc., may be used to describe various elements, but the elements are not limited to these terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the second component may be referred to as a first component, and similarly, the first component may also be referred to as a second component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

In the description of the embodiments, when an element is described as being formed "on or under" another element, the upper or lower (lower) (on or under) all include that the two components are in direct contact with each other or that one or more other components are indirectly formed between the two components. Also, when expressed as 'on or under', it may include not only an upward direction but also a downward direction based on one component.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings, wherein like or corresponding elements are denoted by the same reference numerals, and redundant description thereof will be omitted.

Fig. 3 is a view showing a motor according to the embodiment, and Fig. 4 is a cross-sectional view showing the line A-A in Fig. In Fig. 3, the y direction indicates the axial direction, and the x direction indicates the radial direction. The axial direction and the radial direction are perpendicular to each other.

3 and 4, the motor 1 according to the embodiment includes a housing 100, a cover 200, a stator 300 disposed inside the housing 100, a rotor (not shown) disposed inside the stator 400, a shaft 500 coupled to the rotor 400, and a sensor unit 600. Herein, the inside means a direction disposed toward the center C with respect to the radial direction, and the outside means a direction opposite to the inside.

The housing (100) and the cover (200) can form the outer shape of the motor (1). Here, the housing 100 may be formed in a cylindrical shape having an opening formed at an upper portion thereof.

The cover 200 may be disposed to cover the open top of the housing 100.

Therefore, a receiving space can be formed in the interior by the coupling of the housing 100 and the cover 200. 3, a stator 300, a rotor 400, a shaft 500, and a sensor unit 600 may be disposed in the accommodation space.

The housing 100 may be formed in a cylindrical shape, and the stator 300 may be supported on the inner circumferential surface thereof. A pocket portion for receiving the bearing 10 supporting the lower portion of the shaft 500 may be provided on the lower portion of the housing 100.

The cover 200 disposed at the upper portion of the housing 100 may also be provided with a pocket for receiving the bearing 10 supporting the upper portion of the shaft 500.

The stator 300 may be supported by the inner circumferential surface of the housing 200. The stator 300 is disposed outside the rotor 400. That is, the rotor 400 may be disposed inside the stator 300.

Fig. 5 is a diagram showing the arrangement relationship of the stator core and the rotor of the motor according to the embodiment, and Fig. 6 is a view showing the stator and the rotor in the area B of Fig.

3 to 6, the stator 300 includes a stator core 310, a coil 320 wound around the stator core 310, an insulator 330 disposed between the stator core 310 and the coil 320, . ≪ / RTI >

The stator core 310 may be wound with a coil 320 forming a rotating magnetic field. Here, the stator core 310 may be formed of one core or a plurality of divided cores may be combined.

In addition, the stator core 310 may be formed by stacking a plurality of plates in the form of thin steel plates, but the present invention is not limited thereto. For example, the stator core 310 may be formed as a single unit.

The stator core 310 may include a cylindrical yoke 311 and a plurality of teeth 312.

The tooth 312 may protrude from the yoke 311 in the radial direction (x direction) with respect to the center C of the stator core 310. The plurality of teeth 312 may be spaced apart from each other on the inner circumferential surface of the yoke 311 along the circumferential direction. Accordingly, a slot, which is a space through which the coil 320 can be wound, can be formed between each of the teeth 312. At this time, the number of teeth 312 may be nine but is not limited thereto.

Meanwhile, the teeth 312 may be disposed so as to face the magnet 420 of the rotor 400. The inner surface 312a of the tooth 312 is spaced apart from the outer surface 421 of the magnet 420 by a predetermined gap G. In this case,

The coil 320 is wound on each of the teeth 312.

The insulator 330 insulates the stator core 310 and the coil 320. Accordingly, the insulator 330 may be disposed between the stator core 310 and the coil 320.

Thus, the coil 320 can be wound on the tooth 312 of the stator core 310 in which the insulator 330 is disposed.

The rotor 400 is disposed inside the stator 300. The shaft 500 may be coupled to the center.

The rotor 400 may include a rotor core 410, a magnet 420 disposed on the outer circumferential surface of the rotor core 410, and a shield 430 disposed outside the magnet 420. Here, the shield 430 may be referred to as a can or a rotor can. The number of the magnets 420 may be six, but is not limited thereto.

The rotor core 410 may be formed by laminating a plurality of plates in the form of a thin steel plate. Of course, the rotor core 410 may be fabricated as a single core composed of one cylinder.

A hole to which the shaft 500 is coupled may be formed at the center of the rotor core 410. A protrusion for guiding the arrangement of the magnet 420 may protrude from the outer circumferential surface of the rotor core 410.

The magnet 420 may be attached to the outer circumferential surface of the rotor core 410. At this time, the plurality of magnets 420 may be disposed along the circumference of the rotor core 410 at regular intervals.

The magnet 420 may be disposed radially away from the tooth 312 of the stator 300.

The outer surface 421 of the magnet 420 and the inner surface 312a of the tooth 312 may be spaced apart from each other by a predetermined gap G as shown in FIG. An air gap may be formed between the outer surface 421 of the magnet 420 and the inner surface 312a of the tooth 312. [ The air gap may mean the gap G between the outer surface 421 of the magnet 420 and the inner surface 312a of the tooth 312.

On the other hand, the outer surface 421 of the magnet 420 may be formed as a curved surface whose central portion protrudes toward the outer side as compared with the edge region.

The gap G may be a radial distance from the center C1 of the outer surface 421 of the magnet 420 to the inner surface 312a of the tooth 312. [

The outer surface 421 of the magnet 420 may be in contact with the inner circumferential surface 431 of the shield 430. 6, the center C1 side of the outer side surface 421 of the magnet 420 is in contact with the inner circumferential surface 431 of the shield 430 and the side of the outer side surface 421 of the magnet 420 is in contact with the inner circumferential surface 431, And is spaced apart from the inner circumferential surface 431 of the shield 430.

The shield 430 surrounds the magnet 420 and fixes the magnet 420 so that the magnet 420 is not separated from the rotor core 100. In addition, the shield 430 can prevent the magnet 420 from being exposed.

The shield 430 may be formed in a cylindrical shape and the inner peripheral surface 431 of the shield 430 may contact the outer surface 421 of the magnet 420.

As the shield 430 is formed in a cylindrical shape, the shield 430 has a predetermined width W in the radial direction.

The radial width W of the shield 430 may be 0.07 to 0.3 of the gap G. [ For example, G: W = 1: 0.07 to 0.3. At this time, the gap G may be 0.8 mm.

Meanwhile, the shield 430 may be a magnetic body having magnetism. Accordingly, the shield 430 having a magnetic property prevents the magnetic flux from leaking by causing the magnetic flux to be linked to the tooth 312 disposed to face the magnet 420.

Therefore, saturation of the magnetic flux in one region of the other tooth 312 disposed adjacent to the one tooth 312 is prevented. Accordingly, since the shield 430 can reduce the number of lines of magnetic force, the magnetic flux of the magnet 420 can be made uniform.

As shown in FIG. 7, it can be confirmed that the magnetic shield 430 is prevented from saturation in the region B1 by causing the magnetic flux to be bridged to the tooth 312 disposed to face the magnet 420.

 When the magnetic flux density of the magnet 420 is 1, the magnetic flux density of the shield 430 may be 1.4 to 2.2 of the magnetic flux density of the magnet 420. Here, the magnetic flux density of the magnet 420 may be 1.3T. The grade of the magnet 420 may be N48H.

FIG. 9 is a graph showing the torque ripple of the motor according to the embodiment, FIG. 10 is a table showing the cogging torque and the change rate of the motor according to the embodiment, and FIG. 11 is a table showing the torque ripple and rate of change of the motor according to the embodiment. 8, 88 mNm represents the cogging torque of the motor 2, which is a comparative example. In Fig. 9, 123.5 mNm represents the torque ripple of the motor 2, which is a comparative example.

At this time, the gap G is 0.8 mm. The magnetic flux density of the magnet 420 is 1.3T.

Compared to the motor 1 according to the embodiment and the motor 2 according to the comparative example, there is a difference in that the motor 1 according to the embodiment includes the shield 430.

Referring to FIGS. 8 and 10, it can be confirmed that the cogging torque of the motor 1 according to the embodiment is declining and is optimal when the width W of the shield 430 is 0.1 mm. At this time, the caulking torque is improved by 11% when the magnetic flux density of the shield 430 is 2.0T, and the caulking torque is improved by 23% when the magnetic flux density of the shield 430 is 3.0T.

When the magnetic flux density of the shield 430 is 2.0 to 3.0 T, the width W of the shield 430 is lower than a cogging torque of 88 mNm of the motor 2, which is a comparative example, in a predetermined range.

Accordingly, the width W of the shield 430 of the motor 1 according to the embodiment is 0.07 to 0.3 with respect to the gap G and the magnetic flux density of the shield 430 is 1.4 to 1.4 times the magnetic flux density of the magnet 420. [ At 2.2, the cogging torque can be optimally reduced. Accordingly, the motor 1 can exhibit optimum performance.

Referring to FIGS. 9 and 11, it can be seen that the torque ripple of the motor 1 according to the embodiment is lowered, and that the width W of the shield 430 is the optimum value at 0.1 mm. At this time, the torque ripple is improved by 11% when the magnetic flux density of the shield 430 is 2.0T, and the torque ripple is improved by 20% when the magnetic flux density of the shield 430 is 3.0T.

When the magnetic flux density of the shield 430 is 2.0 to 3.0 T, the width W of the shield 430 is lower than a torque ripple of 123.5 mNm of the motor 2, which is a comparative example, in a predetermined range.

Accordingly, the width W of the shield 430 of the motor 1 according to the embodiment is 0.07 to 0.3 with respect to the gap G and the magnetic flux density of the shield 430 is 1.4 to 1.4 times the magnetic flux density of the magnet 420. [ At 2.2, the torque ripple can be optimally reduced. Accordingly, the motor 1 can exhibit optimum performance.

12 is a table showing the torque of the motor according to the embodiment. At this time, the torque of the motor 2, which is a comparative example, is 4.01 Nm.

12, the width W of the shield 430 of the motor 1 according to the embodiment is 0.07 to 0.3 with respect to the gap G and the magnetic flux density of the shield 430 is greater than the magnetic flux When the density is 1.4 to 2.2, it is confirmed that the performance deterioration of the motor 1 is insignificant.

Therefore, the motor 1 can improve the quality by reducing the cogging torque and the torque ripple while the performance of the motor 1 is not different from that of the motor 2 of the comparative example.

The shaft 500 may be coupled to the rotor 400. When an electromagnetic interaction occurs between the rotor 400 and the stator 300 through the current supply, the rotor 400 rotates and the shaft 500 rotates in conjunction therewith. At this time, the shaft 500 can be supported by the bearing 10.

The shaft 500 may be connected to the steering shaft of the vehicle. Accordingly, the rotation of the shaft 500 allows the steering shaft to receive power.

The sensor unit 600 senses the magnetic force of the sensing magnet installed rotatably and cooperatively with the rotor 400 to detect the current position of the rotor 400, thereby sensing the rotated position of the shaft 500.

The sensor unit 600 may include a sensing magnet assembly 610 and a printed circuit board (PCB) 620.

The sensing magnet assembly 610 is coupled to the shaft 500 to cooperate with the rotor 400 so that the position of the rotor 400 is detected. At this time, the sensing magnet assembly 610 may include a sensing magnet and a sensing plate. The sensing magnet and the sensing plate may be coupled to each other with a coaxial axis.

The sensing magnet may include a main magnet disposed in the circumferential direction adjacent to the hole forming the inner circumferential surface and a sub magnet formed at the edge. The main magnet can be arranged in the same manner as the drive magnet inserted in the rotor 400 of the motor. The submagnet is divided into more poles than the main magnet. As a result, it is possible to measure the rotational angle more finely and measure it, and it is possible to smoothly drive the motor

The sensing plate may be formed of a disc-shaped metal material. A sensing magnet may be coupled to the upper surface of the sensing plate. And the sensing plate may be coupled to the shaft 500. Here, a hole through which the shaft 500 penetrates is formed in the sensing plate.

A sensor for sensing the magnetic force of the sensing magnet may be disposed on the printed circuit board 620. At this time, the sensor may be provided as a Hall IC. The sensor may generate a sensing signal by detecting a change in the N and S poles of the sensing magnet.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the appended claims. It will be understood that the present invention can be changed. It is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

1: motor 10: bearing
100: Housing
200: cover
300:
310: stator core 311: yoke
312: Tooth
320: Coil
400: rotor 410: rotor core
420: Magnet 430: Shield
500: Shaft
600:

Claims (7)

housing;
A stator disposed in the housing;
A rotor disposed within the stator;
A shaft engaged with the rotor; And
And a cover disposed on the upper portion of the housing,
The stator
A stator core including a yoke and a plurality of teeth protruding radially from the yoke;
And a coil wound around the tooth,
The rotor
Rotor core,
A magnet disposed on an outer peripheral surface of the rotor core,
And a shield disposed outside the magnet,
Wherein the magnet is spaced apart from the tooth by a predetermined gap G,
And the width (W) of the shield is 0.07 to 0.3 of the gap (G). The method according to claim 1,
Wherein the outer surface of the magnet is a curved surface whose central portion is protruded outwardly as compared with the edge region. 3. The method of claim 2,
Wherein the distance is a radial distance from a center (C1) of the outer surface to an inner surface of the tooth. The method of claim 3,
Wherein the shield is a magnetic body. 5. The method of claim 4,
And the magnetic flux density of the shield is 1.4 to 2.2 of the magnetic flux density of the magnet. 6. The method of claim 5,
And the inner circumferential surface of the shield is in contact with the outer surface of the magnet. The method according to claim 1,
Wherein the magnet is provided in six, and the tooth is provided in nine.

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