KR20220076805A - Motor - Google Patents

Abstract

The embodiment is a housing having an opening formed on one side; a stator disposed inside the housing; a rotor disposed to correspond to the stator; a shaft coupled to the rotor; a cover covering the opening of the housing; and a bearing disposed on the cover, wherein the cover includes a body and first and second protrusions protruding in a radial direction from an inner circumferential surface of the body, and an outer ring of the bearing includes the first protrusion in the axial direction. and a chamfer disposed between the second protrusion and inclined at an upper edge of the outer ring to start a motor in contact with a lower portion of the second protrusion. Accordingly, the motor may prevent leakage between the cover and the outer ring while preventing the bearing from being separated.

Description

motor {MOTOR}

The embodiment relates to a motor.

A motor is a device that converts electrical energy into mechanical energy to obtain rotational force, and is widely used in vehicles, home electronic products, industrial devices, and the like. For example, the motor may be used in a vehicle motor such as an electronic power steering system (EPS).

The motor includes a housing, a cover disposed in the opening of the housing, a shaft, a stator disposed on an inner circumferential surface of the housing, a rotor coupled to the shaft, and a bearing disposed on an outer circumferential surface of the shaft and the like. Here, the stator induces electrical interaction with the rotor to induce rotation of the rotor, and accordingly, the shaft also rotates in association with the rotation of the rotor.

A bearing may be disposed between the cover and the shaft, and the cover may support the bearing. In this case, the motor may include a fixed part or a separation preventing structure for preventing the bearing from being separated from the cover. Here, as an example of the fixing part, a C-ring may be used.

When a fixed part such as the searing is used, since an additional part is applied to the motor, there is a problem in that the production cost increases.

In addition, when the separation prevention structure is implemented using a caulking molding method in which a portion of the cover is formed by applying a load to a portion of the cover, problems of material deformation and damage may occur due to the load. Furthermore, the risk of leakage due to deformation and damage of the material also increases. Moreover, when caulking is performed at several points, there is a problem in that the risk further increases due to non-uniformity of the load.

Accordingly, there is a demand for a motor having a structure that prevents leakage of the bearing while preventing the separation of the bearing.

The embodiment provides a motor for preventing separation of the bearing by applying a separation preventing structure for preventing separation of the bearing to the cover.

The embodiment provides a motor that provides an optimal design value for the escape prevention structure.

The problems to be solved by the embodiment are not limited to the problems mentioned above, and other problems not mentioned here will be clearly understood by those skilled in the art from the following description.

The subject is a housing having an opening formed on one side; a stator disposed inside the housing; a rotor disposed to correspond to the stator; a shaft coupled to the rotor; a cover covering the opening of the housing; and a bearing disposed on the cover, wherein the cover includes a body and first and second protrusions protruding in a radial direction from an inner circumferential surface of the body, and an outer ring of the bearing includes the first protrusion in the axial direction. and a chamfer disposed between the second protrusion and inclined at an upper edge of the outer ring is achieved by a motor in contact with a lower portion of the second protrusion.

Here, the second protrusion may include a first surface obliquely extending from the inner circumferential surface and a second surface extending in an axial direction from the first surface, and the first surface may be a plane in contact with the chamfer.

In addition, the first surface may be disposed to overlap the chamfer in the axial direction.

In addition, an angle θ between the inner circumferential surface of the body and the first surface may be 20 degrees.

In addition, a vertical distance d from the first surface to the inner circumferential surface of the body may be greater than a radially protruding length L of the second protrusion.

In addition, an inner diameter of the second protrusion may be greater than an inner diameter of the first protrusion in a radial direction and smaller than an outer diameter of the outer ring. Here, the inner diameter of the outer ring may be greater than the inner diameter of the first protrusion.

Meanwhile, the cover and the outer ring may be formed of different materials, and the strength of the outer ring may be greater than that of the cover.

In addition, the bearing and the cover may be coupled through a hot pressing method to form a cover assembly.

In the embodiment, a separation preventing structure for preventing separation of the bearing may be applied to the cover to prevent separation of the bearing.

The embodiment allows a uniform load to be applied to the outer ring of the bearing through the separation preventing structure, thereby preventing leakage between the cover and the outer ring.

Various and advantageous advantages and effects of the embodiments are not limited to the above, and will be more easily understood in the course of describing specific embodiments of the embodiments.

1 is a perspective view showing a motor according to an embodiment;
2 is an exploded perspective view showing a motor according to the embodiment;
3 is a cross-sectional view showing a motor according to the embodiment;
Figure 4 is an enlarged view showing area A of Figure 3,
5 is a perspective view showing a cover of a motor according to an embodiment;
6 is a bottom perspective view showing the cover of the motor according to the embodiment,
7 is a cross-sectional view showing the cover of the motor according to the embodiment,
8 is a perspective view showing the bearing of the motor according to the embodiment;
9 is a cross-sectional view illustrating a bearing of a motor according to an embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In describing the components of an embodiment of the present invention, when it is described that a component is 'connected', 'coupled' or 'connected' to another component, the component is directly connected or coupled to the other component Or, not only the case of being connected, but also the case of 'connected', 'coupled' or 'connected' due to another component between the component and the other component may be included.

In addition, when it is described as being formed or disposed on "above (above) or under (below)" of each component, top (above) or under (below) is one as well as when two components are in direct contact with each other. Also includes a case in which another component as described above is formed or disposed between two components. In addition, when expressed as "upper (upper) or lower (lower)", the meaning of not only an upper direction but also a lower direction based on one component may be included.

1 is a perspective view showing a motor according to an embodiment, FIG. 2 is an exploded perspective view showing the motor according to the embodiment, FIG. 3 is a cross-sectional view showing the motor according to the embodiment, and FIG. 4 is a region A of FIG. is an enlarged view. 1 to 3 , the x direction may mean a radial direction, and the y direction may mean an axial direction. In addition, the axial direction and the radial direction may be perpendicular to each other. Here, the axial direction may be a longitudinal direction of the shaft 400 . In addition, reference numeral C may indicate a rotation center of the shaft 400 .

1 to 4 , the motor according to the embodiment includes a housing 100 having an opening formed on one side thereof, a stator 200 disposed inside the housing 100 , and the stator 200 to correspond to the above. The rotor 300 disposed inside the housing 100 , the shaft 400 coupled to the rotor 300 , the bus bar 500 disposed under the stator 200 , and the opening of the housing 100 . It may include a cover 600 disposed to cover the shaft 400 , and a bearing 700 disposed on the cover 600 to rotatably support the shaft 400 . Here, the motor may prevent the bearing 700 from being separated from the cover 600 by using the separation preventing structure formed on the cover 600 .

In addition, the motor may further include a coupler 800 disposed at an end of the shaft 400 .

The housing 100 and the cover 600 may form the external shape of the motor.

The housing 100 may be formed in a cylindrical shape having an accommodating space therein, and an opening may be formed on the upper side with respect to the axial direction. Accordingly, the stator 200 , the rotor 300 , the shaft 400 , and the bus bar 500 may be disposed in the accommodation space.

In addition, the shape or material of the housing 100 may be variously changed. For example, the housing 100 may be formed of a metal material such as aluminum that can withstand a high temperature well.

In addition, the housing 100 may include a protrusion 110 disposed therein to support the bearing.

The protrusion 110 may be formed to have a ring-shaped cross-section, and accordingly, the housing 100 may form a pocket in which the bearing may be disposed through the protrusion 110 . Here, the bearing disposed in the housing 100 may be referred to as a housing bearing or a lower bearing.

The stator 200 may be disposed inside the housing 100 in a radial direction. In addition, the stator 200 may be supported by the housing 100 . Here, the inner side may mean a direction disposed toward the rotation center C of the motor with respect to the radial direction, and the outer side may mean a direction opposite to the inner side.

Referring to FIG. 2 , the stator 200 may include a stator core 210 , an insulator 220 disposed on the stator core 210 , and a coil 230 wound around the insulator 220 .

A coil 230 for forming a rotating magnetic field may be wound around the stator core 210 .

The stator core 210 may be formed as one core or by combining a plurality of divided cores. Alternatively, the stator core 210 may be formed in a form in which a plurality of plates in the form of thin steel plates are stacked on each other, but is not limited thereto. For example, the stator core 210 may be formed as a single piece.

The stator core 210 may include a cylindrical yoke and a plurality of teeth protruding in a radial direction from the yoke.

The plurality of teeth may be disposed to be spaced apart from each other in a circumferential direction of the yoke. Accordingly, a slot, which is a space in which the coil 230 is wound, may be formed between the respective teeth.

Meanwhile, the teeth of the stator 200 may be disposed to have an air gap with the rotor 300 . Here, the air gap may be a distance between the tooth and the rotor 300 in a radial direction.

The insulator 220 insulates the stator core 210 and the coil 230 . Accordingly, the insulator 220 may be disposed between the stator core 210 and the coil 230 .

Accordingly, the coil 230 may be wound around the stator core 210 on which the insulator 220 is disposed.

The rotor 300 rotates through electrical interaction with the stator 200 . In this case, the rotor 300 may be rotatably disposed inside the stator 200 .

Referring to FIG. 3 , the rotor 300 may include a rotor core 310 and a plurality of magnets 320 disposed outside the rotor core 310 . For example, the rotor 300 may be formed of a surface permanent magnet (SPM) type in which a magnet 320 is attached to the surface of the rotor core 310 . In this case, the magnets 320 may be disposed on the rotor core 310 to be spaced apart from each other at predetermined intervals along the circumferential direction with respect to the center C.

In addition, the rotor 300 may further include a can for protecting the rotor core 310 and the magnet 320 . Here, the can may be disposed to cover the rotor core 310 to which the magnet 320 is coupled.

The rotor core 310 may be implemented in a shape in which a plurality of plates in the form of thin steel plates are stacked or in the shape of a single cylinder.

In addition, the rotor core 310 may be formed in a cylindrical shape. Here, a hole to which the shaft 400 is coupled may be formed in the center C of the rotor core 310 .

The magnet 320 forms a rotating magnetic field with the coil 230 of the stator 200 . Accordingly, the rotor 300 rotates due to the electrical interaction between the coil 230 and the magnet 320 , and the shaft 400 rotates in conjunction with the rotation of the rotor 300 , thereby generating the driving force of the motor. do. Here, the magnet 320 of the rotor 300 may be referred to as a drive magnet.

A plurality of the magnets 320 may be disposed on the outer circumferential surface of the rotor core 310 to be spaced apart from each other in a circumferential direction.

The shaft 400 may be rotatably disposed inside the housing 100 through a bearing disposed on the housing 100 and a bearing 700 disposed on the cover 600 . In addition, the shaft 400 may rotate together in conjunction with the rotation of the rotor 300 . In this case, the shaft 400 may be coupled to the hole formed in the center of the rotor core 310 in a press-fit manner.

The bus bar 500 may be disposed under the stator 200 . In addition, the bus bar 500 electrically connects the stator 200 and an external power source so that external power can be applied to the stator 200 .

The bus bar 500 may include a bus bar body (not shown) and a plurality of terminals disposed inside the bus bar body.

The bus bar body may be a mold formed through injection molding. Here, the bus bar body may be formed of a synthetic resin material such as resin. In this case, the bus bar body may be formed in a ring shape.

The plurality of terminals may be disposed on the bus bar body, and some of the terminals may be exposed from the bus bar body. Here, the terminal may be formed of a metal material.

Some of the plurality of terminals may be power terminals 510 electrically connected to an external power source. As shown in FIG. 3 , an end of the power terminal 510 may be exposed to the outside to be electrically connected to an external power source such as a connector.

The cover 600 may be disposed to cover the opening of the housing 100 . In addition, the housing 100 and the cover 600 may be coupled by a fastening member. In addition, the cover 600 may support the bearing 700 .

5 is a perspective view showing a cover of the motor according to the embodiment, FIG. 6 is a bottom perspective view showing the cover of the motor according to the embodiment, and FIG. 7 is a cross-sectional view showing the cover of the motor according to the embodiment. Here, FIG. 7 is a cross-sectional view taken along line A-A of FIG. 5 .

5 to 7 , the cover 600 includes a body 610 and a first protrusion 620 and a second protrusion 630 each protruding in a radial direction from an inner circumferential surface 611 of the body 610 . ) may be included.

Here, the first protrusion 620 and the second protrusion 630 may be disposed on the inner circumferential surface 611 to be spaced apart from each other in the axial direction. Accordingly, a portion of the bearing 700 may be disposed between the first protrusion 620 and the second protrusion 630 in the axial direction. Accordingly, the cover 600 may implement a separation preventing structure for preventing separation of the bearing 700 by using the body 610 , the first protrusion 620 , and the second protrusion 630 .

The body 610 may be formed in a plate shape in which a hole is formed. Here, since the hole is formed to pass through the body 610 in the axial direction, the body 610 may include an inner peripheral surface 611 formed by the hole formation.

Referring to FIG. 4 , the inner circumferential surface 611 may contact the outer circumferential surface 721 of the outer ring 720 of the bearing 700 . Accordingly, the body 610 may support the outer ring 720 of the bearing 700 . Here, the inner circumferential surface 611 may be formed to have a predetermined inner diameter, and the inner diameter of the inner circumferential surface 611 may be the same as the outer diameter of the outer ring 720 , but is not limited thereto. For example, in consideration of the coupling of the cover 600 and the bearing 700 according to the hot pressing method, the inner diameter of the inner circumferential surface 611 before hot pressing may be smaller than the outer diameter of the outer ring 720 .

The first protrusion 620 may be formed to protrude inward from the inner circumferential surface 611 of the body 610 . Here, the first protrusion 620 may be disposed below the inner circumferential surface 611 in the axial direction. Accordingly, the first protrusion 620 may support the lower side of the outer ring 720 of the bearing 700 .

Also, the first protrusion 620 may protrude from the inner circumferential surface 611 of the body 610 to have a predetermined length in a radial direction. Here, the upper surface 621 of the first protrusion 620 may be in contact with the lower surface (lower surface) of the outer ring 720 .

In addition, the first protrusion 620 may be formed to protrude more inward than the inner circumferential surface of the outer ring 720 . For example, the outer side of the first protrusion 620 is disposed to overlap the outer ring 720 in the axial direction, and the inner side of the first protrusion 620 has an outer part of the ball 730 of the bearing 700 and It may be arranged to overlap in the axial direction.

Referring to FIG. 6 , the first protrusion 620 may be formed in a ring shape. Accordingly, the first protrusion 620 may uniformly support the outer ring 720 without being biased to one side.

Meanwhile, since the first protrusion 620 is formed to protrude inward and has a ring shape, it may be formed to have a predetermined inner diameter D1. Here, the inner diameter of the first protrusion 620 may be referred to as a first inner diameter.

The second protrusion 630 may be formed to protrude inward from the inner circumferential surface 611 of the body 610 . Here, the second protrusion 630 may be disposed above the inner circumferential surface 611 in the axial direction. Accordingly, the second protrusion 630 may support the upper side of the outer ring 720 of the bearing 700 .

Also, the second protrusion 630 may protrude from the inner circumferential surface 611 of the body 610 to have a predetermined length L in a radial direction. Here, the second protrusion 630 may contact the upper side of the outer ring 720 . In this case, the length L of the second protrusion 630 may be derived by a calculation using a coefficient of thermal expansion according to the material of the cover 600 .

In addition, the second protrusion 630 may be formed to protrude more inward than the outer circumferential surface 721 of the outer ring 720 . In this case, the second protrusion 630 may be disposed outside the inner circumferential surface 722 of the outer ring 720 . Accordingly, the second protrusion 630 may be disposed to overlap the outer ring 720 in the axial direction. In detail, the second protrusion 630 may be disposed to overlap the chamfer 725 of the outer ring 720 in the axial direction.

Referring to FIG. 5 , the second protrusion 630 may be formed in a ring shape. Accordingly, the second protrusion 630 may uniformly support the outer ring 720 without being biased to one side. That is, since the second protrusion 630 formed in a ring shape uniformly supports the outer ring 720 , it is possible to suppress the occurrence of leakage compared to the method of fixing the bearing 700 through caulking at multiple points.

Also, since the second protrusion 630 is formed to protrude inward and has a ring shape, it may be formed to have a predetermined inner diameter D2. Here, the inner diameter of the second protrusion 630 may be referred to as a second inner diameter.

And, since the second protrusion 630 is formed to protrude to have a predetermined length L based on the inner circumferential surface 611, the inner diameter D2 of the second protrusion 630 and the bearing 700 The outer diameter of may be formed to have a predetermined ratio. For example, a ratio of the inner diameter D2 of the second protrusion 630 to the outer diameter of the bearing 700 may be 29.9 to 29.95:30. Here, the outer diameter of the bearing 700 may be the outer diameter of the outer peripheral surface 721 of the outer ring 720 .

Referring to FIG. 7 , the second protrusion 630 includes a first surface 631 extending obliquely from the inner circumferential surface 611 , a second surface 632 extending in the axial direction from the first surface, and the second surface 632 . It may include an upper surface 633 extending outward from the upper side of the two surfaces 632 . Here, the upper surface 633 of the second protrusion 630 may be a plane parallel to the upper surface 621 of the first protrusion 620 , but is not limited thereto.

The first surface 631 may be inclined to have a predetermined angle θ with the inner peripheral surface 611 . Assuming that the length L of the second protrusion 630 has a preset length, the contact area between the inclined first surface 631 and the chamfer 725 is a second surface 631 without the first surface 631 . Since it is larger than the contact area between the protrusion 630 and the outer ring 720 , the fixing force between the second protrusion 630 and the bearing 700 is relatively improved by the first surface 631 . Here, the first surface 631 may be referred to as a first inclined surface.

Meanwhile, the angle θ between the inner circumferential surface 611 of the body 610 and the first surface may be 15 to 25 degrees. Preferably, the angle θ formed between the inner peripheral surface 611 of the body 610 and the first surface 631 may be 20 degrees.

If the angle θ between the inner circumferential surface 611 of the body 610 and the first surface 631 is less than 15 degrees, the possibility of the bearing 700 being separated may increase.

In addition, when the angle θ exceeds 25 degrees, an excessive load may be applied to the bearing 700 by the second protrusion 630 by a hot press-fit method. Accordingly, there is a possibility that the second protrusion 630 may be deformed due to the reaction force caused by the load, and the deformation may cause the bearing 700 to be detached from the cover 600 . Here, the reaction force may be applied perpendicularly to the first surface 631 . Therefore, it is preferable that the angle θ is optimally 20 degrees in consideration of this problem.

Meanwhile, the first surface 631 is a surface corresponding to the chamfer 725 formed on the outer ring 720 of the bearing 700 , and may be a plane in contact with the chamfer 725 . Accordingly, referring to FIG. 4 , the first surface 631 may be disposed to overlap the chamfer 725 of the outer ring 720 in the axial direction.

The second surface 632 may be formed to extend in an axial direction from an upper end of the first surface 631 . Here, the second surface 632 may be a plane formed to have the inner diameter D2. In this case, the second surface 632 may be referred to as a vertical surface.

The bearing 700 may be disposed between the shaft 400 and the cover 600 in the radial direction. Accordingly, the bearing 700 may rotatably support the shaft 400 . Here, the bearing 700 may be referred to as an upper bearing or a cover bearing.

In addition, the bearing 700 may be disposed on the cover 600 through a hot press-fit method. Accordingly, the cover 600 and the bearing may form a cover assembly, and the cover assembly may be coupled to the housing 100 .

8 is a perspective view illustrating a bearing of a motor according to an embodiment, and FIG. 9 is a cross-sectional view illustrating a bearing of a motor according to the embodiment. Here, FIG. 9 may be a cross-sectional view taken along line B-B of FIG. 8 .

8 and 9 , the bearing 700 includes an inner ring 710 in contact with the outer circumferential surface of the shaft 400 , an outer ring 720 supported by the cover 600 , and the inner ring 710 . It may include a ball 730 disposed between and the outer ring (720).

In addition, the inner ring 710 and the outer ring 720 of the bearing 700 may be formed of a different material from the cover 600 . Here, the strength of the inner ring 710 and the outer ring 720 may be greater than the strength of the cover 600 . Accordingly, even when the cover 600 and the bearing 700 are coupled by a hot press-fit method, deformation of the bearing 700 can be prevented.

However, since the strength of the cover 600 is relatively lower than the strength of the outer ring 720, there is a possibility that the cover 600 may be deformed by the reaction force formed when the hot press-fit method is coupled, but the cover ( 600 may suggest one of the methods to solve this problem through the angle θ of the first surface 631 formed to be inclined.

For example, the vertical distance d from the first surface 631 to the inner peripheral surface 611 based on the direction of the reaction force applied perpendicularly to the first surface 631 is the second protrusion 630 . Since it is larger than the projection length L in the radial direction of , it is possible to more easily respond to the reaction force. In detail, when the bending moment is considered, the protrusion length L in the radial direction from the corner to the inner circumferential surface 611 based on the corner where the first surface 631 and the second surface 632 meet is It may be smaller than the vertical distance d in the vertical direction of the first surface 631 . Here, the vertical distance d is defined as a distance in the vertical direction with respect to the first surface 631 from the corner where the first surface 631 and the second surface 632 meet to the inner peripheral surface 611. can

That is, by forming the first surface 631 on the second protrusion 630 to be inclined to have a predetermined angle θ, the vertical distance d from the first surface 631 to the inner peripheral surface 611 is The second protrusion 630 may be formed to be larger than the protrusion length L in the radial direction. Accordingly, it is possible to easily respond to the reaction force and prevent deformation of the second protrusion 630 due to the reaction force.

The inner ring 710 may be supported by an outer circumferential surface of the shaft 400 .

The outer ring 720 may be supported by the inner circumferential surface 611 , the first protrusion 620 , and the second protrusion 630 of the cover 600 .

9, the outer ring 720 has an outer peripheral surface 721 and an inner peripheral surface 722 that are spaced apart from each other in a radial direction, an upper surface 723 and a lower surface 724 that are spaced apart from each other in the axial direction, and the outer peripheral surface A chamfer 725 connecting the 721 and the upper surface 723 may be included.

As the bearing 700 is formed in a ring shape, the outer circumferential surface 721 of the outer ring 720 may be formed to have a predetermined outer diameter D3. Here, the outer diameter D3 of the outer peripheral surface 721 may be the outer diameter of the bearing 700 .

As the bearing 700 is formed in a ring shape, the inner circumferential surface 722 of the outer ring 720 may be formed to have a predetermined inner diameter D4 . Here, the inner diameter D4 of the inner circumferential surface 722 may be greater than the inner diameter D1 of the first protrusion 620 .

The upper surface 723 may be a surface connecting the outer peripheral surface 721 and the upper side of the inner peripheral surface 722 together with the chamfer 725 . In this case, the upper surface 723 may be provided as a flat surface.

The lower surface 724 may be a surface connecting the outer peripheral surface 721 and the lower side of the inner peripheral surface 722 . In this case, the lower surface 724 may be provided as a flat surface.

The chamfer 725 may be a surface connecting the outer peripheral surface 721 and the upper surface 723 . Also, the chamfer 725 may be in contact with the first surface 631 and may be flat. In addition, the chamfer 725 is disposed to face the first surface 631 , and may be a surface corresponding to the first surface 631 .

The chamfer 725 may extend inwardly from the upper end of the outer circumferential surface 721 . At this time, the chamfer 725 may be inclined to have a predetermined angle with the outer circumferential surface 721 , and the angle formed between the outer circumferential surface 721 and the chamfer 725 is the inner circumferential surface 611 of the cover 600 . and the angle θ formed by the first surface 631 may be the same. Here, the chamfer 725 may be referred to as an outer ring inclined surface or a second inclined surface.

Meanwhile, the chamfer 725 may be formed by chamfering the upper edge of the outer ring 720 .

The ball 730 is disposed between the inner ring 710 and the outer ring 720 , so that the bearing 700 can rotatably support the shaft 400 .

The coupler 800 may be coupled to an end of the shaft 400 .

The coupler 800 may be coupled to an external device (not shown). Accordingly, the coupler 800 may transmit the rotational force of the shaft 400 to an external device.

Although the above has been described with reference to the preferred embodiment of the present invention, those skilled in the art can variously modify and change the present invention within the scope without departing from the spirit and scope of the present invention as described in the claims below. You will understand that it can be done.

100: housing
200: stator
300: rotor
400: shaft
500: bus bar
600: cover
610: body 620: first protrusion
630: second protrusion 631: first surface
632: second side
700: bearing
710: inner ring 720: outer ring
721: outer circumference 722: inner circumference
725: chamfer
730: ball
800: coupler

Claims (9)

a housing having an opening formed on one side;
a stator disposed inside the housing;
a rotor disposed to correspond to the stator;
a shaft coupled to the rotor;
a cover covering the opening of the housing; and
a bearing disposed on the cover;
The cover includes a body, and a first protrusion and a second protrusion protruding in a radial direction from the inner circumferential surface of the body,
The outer ring of the bearing is disposed between the first projection and the second projection in the axial direction,
A chamfer inclined at an upper edge of the outer ring is in contact with a lower portion of the second protrusion. According to claim 1,
The second protrusion includes a first surface obliquely extending from the inner circumferential surface, and a second surface extending in the axial direction from the first surface,
The first surface of the motor is a plane in contact with the chamfer. 3. The method of claim 2,
The first surface of the motor overlaps the chamfer in the axial direction. 3. The method of claim 2,
The angle (θ) between the inner peripheral surface of the body and the first surface is 20 degrees motor. 3. The method of claim 2,
A distance (d) in a vertical direction from the first surface to the inner circumferential surface of the body with respect to the first surface is greater than a projection length (L) in a radial direction of the second projection. 3. The method of claim 2,
In the radial direction, the inner diameter of the second protrusion is greater than the inner diameter of the first protrusion and smaller than the outer diameter of the outer ring. 7. The method of claim 6,
The inner diameter of the outer ring is greater than the inner diameter of the first protrusion motor. According to claim 1,
The cover and the outer ring are formed of different materials,
The strength of the outer ring is greater than the strength of the cover motor. According to claim 1,
A motor in which the bearing and the cover are coupled through a hot pressing method.

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