Brushless DC motor with a new grounding structure

Abstract

The brushless DC motor (1) according to the present invention comprises: a housing (30), wherein the housing (30) comprises a stator (10) and has a hollow unit (31), wherein a rotor (20) is arranged in the hollow unit (31), wherein the rotor (20) has a shaft (21) coupled to the center thereof; an upper bearing (22) coupled to the output side of the shaft (21) and rotatably supports the shaft; a lower bearing (23) coupled to the lower end of the shaft (21) and rotatably supports the shaft; an upper cover (40) accommodating the upper bearing (22) and covering the hollow unit (31); a lower cover (50) accommodating the lower bearing (23) and coupled to the center of the lower part of the housing (30); and a conductive material coating unit (60) coated on the housing (30) so that the upper cover (40) and the lower cover (50) can be electrically connected to each other so that the upper cover (40) and the lower cover (50) have the same potential.

Description

Technical Field

[0001] The present invention relates to a motor, and more particularly to a motor with a grounding structure, which can improve the grounding structure and more effectively protect the bearing from electrolytic corrosion, thereby improving the performance, durability, vibration and noise of the motor. Background Art

[0002] The motor generally includes a stator and a rotor. The rotor rotates under the action of the magnetic field generated by the stator. The shaft coupled to the rotor so as to rotate with the rotor has bearings installed on the upper and lower parts of the rotor to support the rotation of the shaft.

[0003] The motor is generally controlled by a drive circuit. When the drive circuit is working, a potential difference is generated between the upper and lower bearings, or an axial current is generated due to other reasons, which causes electrolytic corrosion of the bearings. When the motor is working, electrolytic corrosion will cause vibration and noise, which will have a negative impact on the performance and durability of the motor.

[0004] In order to prevent electrolytic corrosion of the bearing, Korean Patent Publication No. 10-2008-0109168 discloses a technology that protects the bearing from electrolytic corrosion by connecting the output side bracket surrounding the upper bearing and the opposite output side bracket surrounding the lower bearing with a conductive tape so that both sides have the same potential. However, the structural strength of the fastening portion at the end of the conductive tape is weak, so it is difficult to achieve the same potential on both sides. In addition, if the adhesion of the conductive tape cannot be ensured, the grounding performance will be reduced.

[0005] Korean Patent No. 10-1562736 discloses a structure in which a grounding metal member is installed outside the motor housing, and the upper and lower ends of the grounding metal member are directly connected to the upper bearing cover and the lower bearing cover. The prior art effectively grounds the upper and lower bearing covers. However, due to the structure in which the bearings are inserted outside the upper and lower bearing covers, the two bearings are easily exposed to the outside. In particular, the end of the grounding metal member slightly contacts the lower bearing cover, so the grounding member may fall off the lower bearing cover. Accordingly, the bearings may not be effectively protected from electrolytic corrosion.

[0006] Korean Patent Nos. 10-1604900 and 10-2041045 disclose a technology of installing upper and lower bearings in a housing, exposing portions of the upper and lower bearings, and connecting the exposed bearings to a grounding member at the same potential. This structure, in which the grounding member is installed at the exposed portions of the upper and lower bearings, is not desirable in terms of assemblability and productivity.

[0007] Accordingly, in order to overcome the above problems, the inventors propose a motor with an improved grounding structure that has not been proposed in the prior art. Summary of the invention

[0008] Technical issues

[0009] The object of the present invention is to provide a brushless DC motor with an improved grounding structure.

[0010] Another object of the present invention is to provide a brushless DC motor, which can make the upper cover and the lower cover have the same potential by coating with conductive material, thereby more effectively protecting the bearing from electrolytic corrosion.

[0011] Another object of the present invention is to provide a brushless DC motor with improved assemblability and productivity.

[0012] All of the above and other inherent objects of the present invention can be easily achieved through the description of the present invention as described below.

[0013] Means of solving the problem

[0014] The brushless DC motor 1 according to the present invention includes: a housing 30, the housing 30 includes a stator 10 and has a hollow unit 31, a rotor 20 is arranged in the hollow unit 31, and the rotor 20 has a shaft 21 coupled to its center; an upper bearing 22, coupled to the output side of the shaft 21, and supports the shaft in a rotatable manner; a lower bearing 23, coupled to the lower end of the shaft 21, and supports the shaft in a rotatable manner; an upper cover 40, accommodating the upper bearing 22 and covering the hollow unit 31; a lower cover 50, accommodating the lower bearing 23 and coupled to the center of the lower part of the housing 30; and a conductive material coating unit 60, coated on the housing 30, so that the upper cover 40 and the lower cover 50 can be electrically connected to each other, so that the upper cover 40 and the lower cover 50 have the same potential.

[0015] In the present invention, preferably, an annular upper flange accommodating unit 34 is formed along the upper circumference of the hollow unit 31 to accommodate the upper cover flange 43 of the upper cover 40, wherein the upper flange accommodating unit 34 and the upper part of the hollow unit 31 form an upper step unit 35.

[0016] In the present invention, the upper end of the conductive material coating unit 60 may have a first upper end 61 coated on the upper stepping unit 35 .

[0017] In the present invention, the upper end of the conductive material coating unit 60 may have a second upper end 62 extending from the first upper end 61 and coated on the upper flange receiving unit 34 .

[0018] In the present invention, a lower flange accommodating unit 36 ​​may be formed in the central hole 33 of the bottom unit 32 of the housing 30 so as to be coupled with the lower cover 50, a lower step unit 37 for different heights may be provided between the lower flange accommodating unit 36 ​​and the bottom surface of the bottom unit 32 of the housing 30, and the lower end of the conductive material coating unit 60 may have a first lower end 63, in which the lower step unit 37 is coated with a conductive material.

[0019] In the present invention, the lower end of the conductive material coating unit 60 may have a second lower end 64 in which the lower flange receiving unit 36 ​​extending from the first lower end 63 is coated with a conductive material.

[0020] The brushless DC motor 1 according to the present invention includes: a housing 30, the housing 30 includes a stator 10 and has a hollow unit 31, a rotor 20 is arranged in the hollow unit 31, and the rotor 20 has a shaft 21 coupled to its center; an upper bearing 22, coupled to the output side of the shaft 21, and supports the shaft in a rotatable manner; a lower bearing 23, coupled to the lower end of the shaft 21, and supports the shaft in a rotatable manner; an upper cover 40, accommodating the upper bearing 22 and covering the hollow unit 31; a lower cover 50, accommodating the lower bearing 23 and coupled to the center of the lower part of the housing 30; and a conductive material coating unit 60, coated on the housing 30, the upper cover 40 and the lower cover 50, so that the upper cover 40 and the lower cover 50 have the same potential.

[0021] Effects of the Invention

[0022] The present invention provides a novel grounding structure that contacts the upper cover and the lower cover at the same time, which can effectively keep the upper and lower bearings at the same potential, thereby more effectively protecting the bearings from electrolytic corrosion and improving assemblability and productivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a perspective view of a brushless DC motor according to the present invention.

[0024] Figure 2 is an inverted perspective view of a brushless DC motor according to the present invention.

[0025] Figure 3 1 is an exploded top perspective view of a brushless DC motor according to the present invention.

[0026] Figure 4 1 is an exploded bottom perspective view of the brushless DC motor according to the present invention.

[0027] Figure 5 3 is a top perspective view of the housing, showing the grounding structure of the upper cover of the brushless DC motor according to the present invention.

[0028] Figure 6 is an inverted perspective view of a housing, showing a grounding structure of a lower cover of a brushless DC motor according to the present invention.

[0029] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION

[0030] Figure 1 is a perspective view of a brushless DC motor 1 according to the present invention. Figure 2 is an inverted perspective view of the brushless DC motor 1 according to the present invention. Figure 3 1 is an exploded top perspective view of the brushless DC motor 1 according to the present invention. Figure 4 1 is an exploded bottom perspective view of the brushless DC motor 1 according to the present invention.

[0031] like Figure 1 to Figure 4 As shown, the brushless DC motor 1 according to the present invention may include a stator 10 , a rotor 20 , a housing 30 , an upper cover 40 , a lower cover 50 and a conductive material coating unit 60 .

[0032] The stator 10 includes a plurality of teeth 11 protruding toward the shaft 21 and a printed circuit board 12 electrically connected to the stator. The printed circuit board 12 is electrically connected to a connector 13, and a wire 14 is electrically connected to the connector 13 to receive and transmit external power or signals.

[0033] The rotor 20 is located inside the stator 10 and rotates under the action of the changing magnetic field generated by the stator 10. To this end, the rotor 20 includes a magnet facing the stator 10 inside it. The shaft 21 passes through the center of the rotor 20 coupled thereto. Accordingly, the rotor 20 and the shaft 21 rotate together as a unit. The upper end of the shaft 21 is coupled to a load such as a fan. That is, the upper end of the shaft 21 is the output side. The upper bearing 22 is coupled to the portion below the upper end of the shaft 21 to support the rotation of the shaft 21. The lower bearing 23 is coupled to the lower end of the shaft 21 to support the rotation of the shaft 21.

[0034] The housing 30 includes a hollow unit 31 having a gap at the center, and a bottom unit 32 covering the lower part of the hollow unit 31. The rotor 20 coupled to the shaft 21 so as to rotate with the shaft 21 is located inside the hollow unit 31. A center hole 33 is opened at the center of the bottom unit 32 so that the lower cover 50 is coupled to the bottom unit 32. On the inner circumferential surface of the center hole 33, a plurality of press-fit protrusions 33A protruding toward the shaft 21 are formed at fixed intervals.

[0035] The stator 10 is installed on a side surface facing the rotor 20 in the housing 30 . Figure 3 and Figure 4 The stator 10 and the housing 30 are shown as separate components. However, it is preferred that the stator 10, the printed circuit board 12 and the connector 13 are manufactured integrally with the housing 30 by injection molding in an insert mold.

[0036] The upper cover 40 made of a conductive metal material is coupled to cover the top of the hollow unit 31 of the housing 30. The upper cover 40 includes a disc-shaped upper cover body 41, a lower protruding unit 42 protruding downward from the upper cover body 41, an upper cover flange 43 forming the outer circumference of the upper cover body 41, an upper bearing insertion unit 44 having a shape protruding upward from the center of the upper cover body 41, and an upper shaft through hole 45 through which the shaft 21 can pass.

[0037] The upper bearing 22 is internally coupled with an upper bearing insertion unit 44 having a protruding shape. Figure 3 The upper bearing 22 is shown coupled from the lower side to the upper bearing insertion unit 44. However, the present invention is not necessarily limited thereto, and may be modified so that the center portion of the upper bearing insertion unit 44 of the upper cover 40 is open to the top so that the upper bearing 22 is coupled from the upper side of the upper cover 40.

[0038] The lower cover 50 made of conductive material includes a cup-shaped lower cover body 51 with an open top, a lower cover flange 52 extending from the top circumference of the lower cover body 51, a lower bearing insertion unit 53 as an internal space of the lower cover body 51 for inserting a lower bearing, and a lower shaft through hole 54 formed at the bottom center of the lower cover body 51 for the shaft 21 to pass through. A plurality of press-fit grooves 52A are provided at fixed intervals on the lower cover flange 52. The press-fit grooves 52A are grooves into which the press-fit protrusions 33A are press-fitted, and the press-fit protrusions 33A are formed on the inner side of the central hole 33 of the bottom unit 32 of the housing 30.

[0039] The conductive material coating unit 60 for electrically connecting the upper cover 40 and the lower cover 50 to have the same potential is a conductive material coated on the housing 30 so that the upper cover 40 and the lower cover 50 can be electrically connected to each other. For the conductive material, a material such as conductive ink or conductive paint can be used to coat the outer surface of the housing 30 to electrically connect the upper cover 40 and the lower cover 50. In the present invention, the conductive material coating unit 60 can be coated by the following two embodiments.

[0040] In an embodiment, Figure 1 and Figure 2 In the embodiment, the upper surface, the side surface, and the lower surface of the housing are uniformly formed with a conductive material coating unit 60 made by coating a conductive material, and a portion of the upper cover flange 43 of the upper cover 40 and a portion of the side surface of the lower cover 50 are also formed with the conductive material coating unit 60. In the case where the conductive material coating unit 60 is coated in this manner, the conductive material is coated after the upper cover 40 and the lower cover 50 are assembled to the housing 30. Accordingly, assemblability can be improved, and the upper cover 40 and the lower cover 50 can be more easily electrically connected to each other.

[0041] In another embodiment, Figure 3 and Figure 4In the embodiment, before the upper cover 40 and the lower cover 50 are assembled to the housing 30, a conductive material coating unit 60 is formed in the housing 30. The conductive material coating unit 60 has a specific upper and lower end structure. In this embodiment, the upper cover 40 and the lower cover 50 are electrically connected to the conductive material coating unit 60 while being assembled to the housing 30. Figure 5 and Figure 6 Describe the structure in more detail.

[0042] Figure 5 FIG. 3 is a top perspective view of the housing 30, showing the grounding structure of the upper cover of the brushless DC motor 1 according to the present invention. Figure 5 As shown, the housing 30 of the present invention is open at the top and has a hollow unit 31, i.e., an internal space. The upper flange accommodating unit 34 is formed in a ring shape along the upper circumference of the hollow unit 31. The height of the upper flange accommodating unit 34 is lower than the upper part of the housing 30, and an upper stepping unit 35 is provided for different heights. The upper cover flange 43 of the upper cover 40 is provided in the upper flange accommodating unit 34. The outermost circumference of the upper cover flange 43 is press-fitted with the upper stepping unit 35.

[0043] The upper end of the conductive material coating unit 60 includes a first upper end 61 and a second upper end 62. The first upper end 61 is a portion where the conductive material is coated on the upper stepping unit 35, and the second upper end 62 is a portion extending from the first upper end 61 where the conductive material is coated on the upper flange receiving unit 34.

[0044] In the present invention, the upper end of the conductive material coating unit 60 may be the first upper end 61 , or the upper end of the conductive material coating unit 60 may be the second upper end 62 further extending from the first upper end 61 , thereby improving the electrical connection reliability between the conductive material coating unit 60 and the upper cover 40 .

[0045] Figure 6 3 is an inverted perspective view of the housing 30, showing the grounding structure of the lower cover 50 of the brushless DC motor 1 according to the present invention.

[0046] The housing 30 of the present invention includes a bottom unit 32 having a center hole 33. A plurality of press-fit protrusions 33A are formed on the inner circumference of the center hole 33 so as to be press-fitted with the press-fit grooves 52A of the lower cover 50. The lower cover flange 52 of the lower cover 50 is disposed in the lower flange accommodating unit 36. The height of the lower flange accommodating unit 36 ​​is higher than the lower portion of the housing 30.

[0047] The lower flange accommodating unit 36 ​​and the bottom surface of the bottom unit 32 have different heights, and the lower stepping unit 37 is provided for the different heights. The lower cover flange 52 of the lower cover 50 is provided in the lower flange accommodating unit 36. Preferably, a plurality of press-fitting protrusions 33A are formed in the lower stepping unit 37.

[0048] The lower end of the conductive material coating unit 60 includes a first lower end 63 and a second lower end 64. The first lower end 63 is a portion where the conductive material is coated on the lower stepping unit 37, and the second lower end 64 is a portion extending from the first lower end 63 where the conductive material is coated on the lower flange receiving unit 36.

[0049] In the present invention, the lower end of the conductive material coating unit 60 may be the first lower end 63, or the lower end of the conductive material coating unit 60 may be the second lower end 64 further extended from the first lower end 63, which improves the reliability of electrical connection between the conductive material coating unit 60 and the lower cover 50. In addition, preferably, in order to improve the reliability of electrical connection, the second lower end 64 is coated, including the press-fit protrusion 33A formed in the lower stepping unit 37.

[0050] It should be noted that the above description of the present invention is only an example for understanding the present invention and is not intended to limit the scope of the present invention. The protection scope of the present invention is defined by the appended claims, and it should be understood that simple modifications or changes within the scope of the claims belong to the scope of the present invention.

Claims

1. A brushless DC motor, comprising: A housing (30), the housing (30) includes a stator (10) and has a hollow unit (31) inside, a rotor (20) is arranged in the hollow unit (31), and the rotor (20) has a shaft (21) coupled to the center thereof; an upper bearing (22) coupled to the output side of the shaft (21) to rotatably support the shaft; a lower bearing (23) coupled to the lower end of the shaft (21) to rotatably support the shaft; An upper cover (40) accommodating the upper bearing (22) and covering the hollow unit (31); A lower cover (50) accommodating the lower bearing (23) and coupled to the center of the lower portion of the housing (30); as well as The conductive material coating unit (60) is coated on the housing (30) so that the upper cover (40) and the lower cover (50) can be electrically connected to each other, and the upper cover (40) and the lower cover (50) have the same potential.

2. The brushless DC motor according to claim 1, wherein: An annular upper flange accommodating unit (34) is formed along the upper circumference of the hollow unit (31) to accommodate the upper cover flange (43) of the upper cover (40), wherein the upper flange accommodating unit (34) and the upper part of the hollow unit (31) form an upper stepping unit (35).

3. The brushless DC motor according to claim 2, wherein: The upper end of the conductive material coating unit (60) has a first upper end (61) coated on the upper stepping unit (35).

4. The brushless DC motor according to claim 3, wherein: The upper end of the conductive material coating unit (60) has a second upper end (62) extending from the first upper end (61) and coated on the upper flange receiving unit (34).

5. The brushless DC motor according to claim 1, wherein: A lower flange accommodating unit (36) is formed in the central hole (33) of the bottom unit (32) of the housing (30) so as to be coupled with the lower cover (50), and a lower stepping unit (37) for different heights is provided between the lower flange accommodating unit (36) and the bottom surface of the bottom unit (32) of the housing (30), and the lower end of the conductive material coating unit (60) has a first lower end (63), and in the first lower end (63), the lower stepping unit (37) is coated with a conductive material.

6. The brushless DC motor according to claim 5, wherein: The lower end of the conductive material coating unit (60) has a second lower end (64), in which a conductive material is coated on the lower flange receiving unit (36) extending from the first lower end (63).

7. A brushless DC motor, comprising: A housing (30), the housing (30) includes a stator (10) and has a hollow unit (31) inside, a rotor (20) is arranged in the hollow unit (31), and the rotor (20) has a shaft (21) coupled to the center thereof; an upper bearing (22) coupled to the output side of the shaft (21) to rotatably support the shaft; a lower bearing (23) coupled to the lower end of the shaft (21) to rotatably support the shaft; An upper cover (40) accommodating the upper bearing (22) and covering the hollow unit (31); A lower cover (50) accommodating the lower bearing (23) and coupled to the center of the lower portion of the housing (30); as well as The conductive material coating unit (60) is coated on the housing (30), the upper cover (40) and the lower cover (50), so that the upper cover (40) and the lower cover (50) can have the same potential.

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