CN111712998B

CN111712998B - Brushless DC motor with ground protection casting mould end cover

Info

Publication number: CN111712998B
Application number: CN201980013134.8A
Authority: CN
Inventors: 张贞喆; 李京柱; 金炳秀; 梁玹诚
Original assignee: New Motech Co Ltd
Current assignee: New Motech Co Ltd
Priority date: 2018-05-02
Filing date: 2019-03-14
Publication date: 2023-06-16
Anticipated expiration: 2039-03-14
Also published as: KR102030089B1; CN111712998A; WO2019212142A1

Abstract

The brushless DC motor of the present invention includes: a housing (10) having a stator (15) therein and having a hollow portion (11), a rotor (20) coupled to a shaft (21) being located at a middle portion of the hollow portion (11); an upper bearing (22) coupled to an output side of the shaft (21) to rotatably support the shaft; an upper bearing cover (31) which accommodates the upper bearing (22) and covers the hollow portion (11); a lower bearing (23) coupled to a lower end of the shaft (21) to rotatably support the shaft; a lower bearing block (32) which accommodates the lower bearing (23) and is coupled to an intermediate projection (14) projecting from the middle of the lower portion of the housing (10); a first grounding member (50) having an upper end (50 a) coupled to the outside of the upper bearing cap (31) in a bent manner and a lower end (50 b) coupled to an intermediate portion of the lower bearing housing (32) so as to equipotential the upper bearing cap (31) and the lower bearing housing (32); and a molded end cap (42) that covers a lower portion of the intermediate protruding portion (14) and a part of the first grounding member (50).

Description

Brushless DC motor with ground protection casting mould end cover

Technical Field

The invention relates to a grounding structure of an electric motor. More particularly, the present invention relates to a motor having a grounding structure, which is more effectively prevented from electrolytic corrosion of a bearing by improving the grounding structure, and which protects a grounding member by using a mold end cap, improves performance and durability, and has characteristics of small vibration and low noise.

Background

Typically, an electric machine includes a stator and a rotor. The rotor rotates under the influence of the magnetic field formed by the stator. The shaft coupled to and rotating with the rotor has bearings for supporting rotation of the shaft mounted at upper and lower portions of the rotor.

Typically, such motors are controlled by a drive circuit. When the driving circuit operates, the bearing is corroded by electrolysis due to the potential difference generated between the upper bearing and the lower bearing or axial current generated by another reason. When the motor is operated under electrolytic corrosion, noise and vibration are generated, seriously affecting the performance and durability of the motor.

In order to prevent electrolytic corrosion of bearings, korean patent laid-open No. 10-2008-0109168 discloses a technique for preventing electrolytic corrosion of bearings, in which an output side bracket surrounding an upper bearing and an opposite output side bracket surrounding a lower bearing are connected by a conductive cloth tape so that potentials of both sides are equalized. However, the structure of the member for fixing the end portion of the conductive cloth tape is fragile, and thus there may be a problem in maintaining the equipotential.

Meanwhile, korean patent No. 10-1562736 discloses a structure in which a metal member for grounding is installed at the outside of a motor housing so that upper and lower ends of the metal member for grounding are directly connected to an upper bearing cap and a lower bearing cap. In the prior art, an effective ground connection is made between the upper and lower bearing caps, but since it has a structure in which the bearings are inserted outside the upper and lower bearing caps, the two bearings are easily exposed to the outside. In particular, since the grounding member is likely to be isolated due to the structure in which one end of the grounding metal member is in slight contact with the lower bearing cap, there may be a problem in that electrolytic corrosion of the bearing cannot be effectively prevented.

In this regard, in order to solve the above-mentioned problems, the present inventors have proposed a motor having an improved grounding structure not proposed in the prior art, which has a novel structure that can protect the ground by using a mold end cap while effectively preventing water from entering from the bearing side.

Disclosure of Invention

Technical problem

The object of the present invention is to provide an electric machine with an improved grounding structure.

Another object of the present invention is to provide a motor capable of effectively preventing water from entering a bearing side by applying a mold end cap and stably fixing a grounding member.

Another object of the present invention is to provide a motor capable of effectively maintaining equipotential properties between an upper bearing and a lower bearing by a structure of simultaneously contacting a lower bearing cover and a ground member of the bearing, thereby more effectively preventing electrolytic corrosion of the bearing.

The above objects and other objects inherent in the present invention can be easily achieved by the present invention as set forth below.

Technical proposal

The brushless DC motor according to the present invention comprises:

a housing 10 having a stator 15 inside and a hollow portion 11, and a rotor 20 coupled to a shaft 21 located at a middle portion of the hollow portion 11;

an upper bearing 22 coupled to an output side of the shaft 21 to rotatably support the shaft;

an upper bearing cover 31 which accommodates the upper bearing 22 and covers the hollow portion 11;

a lower bearing 23 coupled to a lower end of the shaft 21 to rotatably support the shaft;

a lower bearing housing 32 which accommodates the lower bearing 23 and is coupled to an intermediate protrusion 14 protruding from the middle of the lower portion of the housing 10;

a first grounding member 50 having an upper end 50a coupled to the outside of the upper bearing cap 31 in a bent manner and a lower end 50b coupled to an intermediate portion of the lower bearing housing 32, for equipotential between the upper bearing cap 31 and the lower bearing housing 32; and

the end cap 42 is molded to cover both the lower portion of the intermediate protrusion 14 and a portion of the first grounding member 50.

In the present invention, it is preferable that the first grounding member 50 is located on the first groove 13, the first groove 13 is formed to be connected to the upper surface and the side surface of the housing 10, and the lower groove 13a is communicated with the first groove 13 and is formed to be connected to the bottom surface of the housing 10.

In the present invention, the molded cover 42 may have an intermediate cover portion 42a, and the intermediate cover portion 42a may cover the lower opening portion 14a, and the lower opening portion 14a may be formed such that a portion of the lower bearing housing 32 is exposed at a lower portion located in the middle of the housing 10.

In the present invention, it is preferable that the molded end cap 42 has an insertion protrusion 42b, and the insertion protrusion 42b is formed to be placed in the lower opening 14a and the lower groove 13a.

In the present invention, it is preferable that the lower end 50b has a curved shape, and the end of the curved shape is interposed between the lower bearing 23 and the lower bearing housing 32.

In the present invention, it is preferable that the lower end 50b of the first grounding member 50 is coupled to the second groove 32a formed on the lower bearing housing 32.

ADVANTAGEOUS EFFECTS OF INVENTION

The invention has the effect that the equipotential between the upper bearing and the lower bearing is effectively maintained through the novel structure of the grounding component which is simultaneously contacted with the lower bearing cover and the bearing, thereby more effectively preventing the bearing from electrolytic corrosion.

Also, the present invention has an effect of preventing the ground member from being separated by applying a mold cover on the bearing exposure portion and the ground member, thereby stably fixing the ground member and preventing the motor from water inflow.

Drawings

Fig. 1 is an exploded view of an electric machine according to the present invention;

FIG. 2 is an exploded schematic view of an electric machine according to the present invention;

FIG. 3 is a bottom exploded schematic view of an electric motor according to the present invention;

FIG. 4 is an exploded schematic view of a motor lower bearing cap side grounding structure according to the present invention; and is also provided with

Fig. 5 is a cross-sectional view taken along line A-A' of fig. 1.

The present invention will be described in detail below with reference to the drawings.

Detailed Description

Fig. 1 is an exploded view of the above-described motor 100 according to the present invention; fig. 2 is an exploded view of the above-described motor 100 according to the present invention; fig. 3 is a bottom exploded view of the above-described motor 100 according to the present invention.

As can be seen in fig. 1 to 3, the motor 100 according to the present invention may include a housing 10, a rotor 20, an upper bearing cover 31, a lower bearing housing 32, an upper protection member 41, and a mold end cover 42.

The housing 10 has a hollow portion 11 in which a space in the middle is hollow, and an annular flange portion 12 protrudes upward along an upper portion of the hollow portion 11. A rotor 20 coupled to the shaft 21 and rotating together with the shaft 21 is located within the hollow 11. The first recess 13 is where the first grounding member 50 is placed. The first groove 13 is formed by the flange portion 12 or a portion adjacent to the flange portion 12 to be connected to the upper surface and the side surface of the case 10. Meanwhile, the lower portion of the first grounding member 50 is located on the lower groove 13a communicating with the first groove 13 and is formed on the bottom surface of the housing 10. The lower protrusion 14 protrudes downward in the middle of the lower surface of the housing 10. The lower groove 13a communicating with the first groove 13 may be shaped to extend upward to the lower opening portion 14a of the intermediate protruding portion 14. A lower opening portion 14a is opened on the bottom surface of the middle protrusion portion 14, wherein the bottom surface of the lower bearing housing 32 is exposed at the lower opening portion 14a. The middle protrusion 14 protrudes upward from the bottom surface of the housing 10, and the lower bearing housing 32 is coupled in a space therein.

The stator 15 is located inside the housing 10, and the housing 10 is positioned facing the side surface of the rotor 20. The stator 15 is electrically connected to the printed circuit substrate 15a, and the connector 15b is connected to leads (not shown) connected to an external power source, which is mounted to provide an external power source to the printed circuit substrate 15 a. Fig. 3 shows the stator 15 and the housing 10 as separate parts. However, preferably, the stator 15, the printed circuit substrate 15a, and the connector 15b are made by injection molding, and are integrally molded with the housing 10 in an insert mold.

The rotor 20 includes magnets positioned facing the stator. The shaft 21 is penetratingly coupled to a middle portion of the rotor 20. Thus, the rotor 20 and the shaft 21 are one unit and rotate together. A load, such as a fan, is coupled to the upper end of the shaft 21. That is, the upper end of the shaft 21 becomes the output side. An upper bearing 22 for supporting the rotation of the shaft 21 is coupled to the bottom of the upper end of the shaft 21. A lower bearing 23 is coupled to a lower end of the shaft 21 to support rotation of the shaft 21.

The upper bearing cap 31 is coupled to cover the hollow portion 11 of the housing 10 with a conductive material. The circumferential portion of the upper bearing cap 31 is coupled to the flange portion 12 of the housing 10. The middle portion of the upper bearing cap 31 has an upwardly protruding shape, and the upper bearing 22 is coupled to an inner portion of the protruding shape. As shown in fig. 2, the upper bearing 22 is coupled to the lower side of the upper bearing cap 31, but the coupling shape is not limited thereto, and the protruding shape of the middle portion of the upper bearing cap 31 may be changed so that the upper bearing 22 is coupled to the upper side of the upper bearing cap 31. The upper portion of the upper bearing cap 31 is covered by an upper protection member 41 to be protected.

The lower bearing housing 32 is made of an electrically conductive material and has a cup shape with an upper opening, and the lower bearing 23 is coupled in the intermediate space. The lower bearing housing 32 has a second groove 32a opened on the bottom surface thereof, and the second groove 32a is coupled to the lower end 50b of the first ground member 50. A lower opening portion 32b is opened in the middle of the bottom surface of the lower bearing housing 32, and the second groove 32a and the lower opening portion 32b have a shape connected to each other. The bottom surface portion of the lower bearing housing 32 is exposed to the outside through the lower opening portion 14b of the bottom surface of the housing 10. The exposed portion is covered with a molded end cap 42. The intermediate cover portion 42a of the molded end cap 42 is coupled to cover the lower opening portion 14a. The upper protection member 41 and the mold end cap 42 may be made of rubber or plastic made of an elastic material.

As shown in fig. 2 and 3, the molded end cap 42 has an intermediate cover portion 42a, and the intermediate cover portion 42a is a member that covers the lower opening 14a of the housing 10. Also, the mold end cap 42 has a lower groove 13a communicating with the first groove 13 so as to insert a component coupled to the bottom surface of the first ground member 50 housing 10, and the insert protrusion 42b is shaped in a protruding manner to be fitted with the lower opening 14a. This structure of the molded end cap 42 prevents water from entering the lower opening 14a side. Meanwhile, by firmly fixing the lower portion of the first grounding member 50 to the lower groove 13a, the coupling of the lower end portion of the first grounding member 50 and the lower bearing housing 32 can be prevented from being separated.

Fig. 4 is an exploded view of the grounding structure of the lower bearing housing 32 side of the motor 100 according to the present invention; fig. 5 is a cross-sectional view taken along line A-A' of fig. 1.

Referring to fig. 4 and 5, the first ground member 50 is coupled to the lower groove 13a along the first groove 13 of the housing 10. The first grounding member 50 of the side surface portion of the housing 10 is open with a grounding hole 50c. The second grounding member 51 is inserted into the grounding hole 50c so as to penetrate the side surface of the housing 10 and is coupled to the core portion of the stator 15 in the housing 10. This structure can be confirmed from fig. 5. As shown in fig. 5, the second grounding member 51 is a bolt, but the second grounding member is not necessarily limited to a bolt, but other members such as a pin or a screw may be used as long as it can be coupled to the grounding hole 50c to equipotential the stator core and the first grounding member 50.

The upper end portion 50a of the first grounding member 50 has a curved shape, and as shown in fig. 5, the upper end portion 50a is press-fitted between the flange portion 12 of the housing 10 and the outer peripheral portion of the upper bearing cap 31 coupled thereto. The lower end 50b of the first ground member 50 has an end bent in a "U" shape, and the bent portion is coupled to the second groove 32a of the lower bearing housing 32.

The first ground member 50 is coupled along the first groove 13 and the lower groove 13a, and the first ground member 50 has a curved shape so as to pass through the lower opening portion 14a with its end coupled to the second groove 32a of the lower bearing housing 32. As described above, the lower end 50b is an end coupled to the second groove 32a, and the lower end 50b is "U" shaped.

As shown in fig. 4, the bent portion of the end of the lower end portion 50b of the first grounding member 50 is in contact with the bottom surface portion 23a of the lower bearing 23. Preferably, the end of the lower end 50b of the first grounding member 50 is interposed between the lower bearing 23 and the lower bearing housing 32 so as to be in simultaneous contact with both members. With this structure, the lower end portion of the first grounding member 50 is ensured to form firm coupling, and electrical contact is stably maintained.

The description of the invention provided above is merely to provide examples that facilitate an understanding of the invention and is not intended to limit the scope of the invention. The description of the present invention should be defined by the appended claims, and it should be noted that simple modifications or changes made to the present invention within the scope of the claims fall within the scope of the invention as claimed.

Claims

1. A brushless direct current motor is provided, which comprises a motor,

comprising the following steps:

a housing (10) having a stator (15) therein and having a hollow portion (11), a rotor (20) coupled to a shaft (21) being located at a middle portion of the hollow portion (11);

an upper bearing (22) coupled to an output side of the shaft (21) to rotatably support the shaft;

an upper bearing cover (31) which accommodates the upper bearing (22) and covers the hollow portion (11);

a lower bearing (23) coupled to a lower end of the shaft (21) to rotatably support the shaft;

a lower bearing block (32) which accommodates the lower bearing (23) and is coupled to an intermediate projection (14) projecting from the middle of the lower portion of the housing (10);

a first grounding member (50) having an upper end (50 a) coupled to the outside of the upper bearing cap (31) in a bent manner and a lower end (50 b) coupled to an intermediate portion of the lower bearing housing (32) so as to equipotential the upper bearing cap (31) and the lower bearing housing (32); and

a molded end cap (42) which covers a lower portion of the intermediate protruding portion (14) and a part of the first grounding member (50) at the same time,

the lower end portion (50 b) of the first grounding member (50) has an end portion bent in a U-shape, the bent portion being coupled to a second groove (32 a) formed in the lower bearing housing (32),

the first grounding member (50) is located on a first groove (13), the first groove (13) is shaped to be connected to an upper surface and a side surface of the housing, and a lower groove (13 a), the lower groove (13 a) communicates with the first groove (13) and is shaped to be connected to a bottom surface of the housing (10),

the molded end cap (42) has an intermediate cover part (42 a), the intermediate cover part (42 a) is a member for covering a lower opening part (14 a), the lower opening part (14 a) is formed so that a part of a lower bearing seat (32) is exposed on a lower part positioned in the middle of the housing (10),

the molded end cap (42) has an insertion protrusion (42 b), the insertion protrusion (42 b) is formed to be placed in the lower opening (14 a) and the lower groove (13 a),

the intermediate covering portion (42 a) covers a bottom surface portion of the lower bearing housing (32) exposed through the lower opening portion (14 a).

2. A brushless dc motor according to claim 1, wherein an end of the lower end portion (50 b) is interposed between the lower bearing (23) and the lower bearing housing (32).