CN113906654A

CN113906654A - Ungrounded motor

Info

Publication number: CN113906654A
Application number: CN202080040733.1A
Authority: CN
Inventors: 张贞喆; 李京柱; 梁玹诚; 徐广德
Original assignee: New Motech Co Ltd
Current assignee: New Motech Co Ltd
Priority date: 2019-08-05
Filing date: 2020-05-19
Publication date: 2022-01-07
Also published as: WO2021025269A1; KR102238237B1; KR20210016753A

Abstract

The electric machine (100) according to the invention comprises: a stator (1) including an upper insulator (11), a stator core (12), and a lower insulator (13); a rotor (2) rotatably mounted opposite to the stator (1); a shaft (20) coupled to said rotor (2) and rotating therewith; and a printed circuit board (3) electrically connected to the stator (1), wherein the rotor (2) includes a rotor body (21) and a magnet (22) coupled to an outer circumferential surface of the rotor body (21), and the rotor body (21) is made of an insulating material.

Description

Ungrounded motor

Technical Field

The present invention relates to an electric machine. More particularly, the present invention relates to a motor having a novel structure capable of preventing damage caused by electric corrosion of bearings and reducing noise generated in the motor by eliminating a ground structure of the motor and improving the motor to have a non-ground structure.

Background

Electric machines typically include a stator and a rotor. The magnetic field formed by the stator causes the rotor to rotate. The shaft is coupled to the rotor to rotate with the rotor, and bearings supporting the rotation of the shaft are provided at upper and lower portions of the rotor.

The motor is typically controlled by a drive circuit. When the drive circuit is operated, the bearing is electrically corroded by a potential difference generated between the bearing and the shaft or by axial flow generated due to other reasons. When the motor is operating, the electrical erosion generates noise and vibration, which adversely affects motor performance and motor durability.

In order to prevent the bearing from being electrically corroded, korean patent application No. 10-2008-0109168 discloses a technique for preventing the bearing from being electrically corroded by establishing an equal potential at both sides by connecting an output bracket enclosing an upper bearing and an opposite output bracket enclosing a lower bearing using a conductive tape. However, it is difficult to maintain the same potential because the structural strength of the parts fixing the ends of the conductive tapes is weak.

Meanwhile, korean patent No. 10-1562736 discloses a structure in which a grounded metal member is installed outside a motor case, and upper and lower ends of the grounded metal member are directly connected to an upper bearing cap and a lower bearing cap. This prior art technique achieves effective grounding between the upper and lower bearing caps, but both bearings are easily exposed to the outside because of its structure in which the bearings are nested outside the upper and lower bearing caps. In particular, since the end of the grounding metal member is in light contact with the lower bearing cap side in this structure, the grounding member may be separated, and thus the generation of the bearing electrolytic corrosion cannot be effectively prevented.

Japanese patent application No. 2013-81264 discloses a structure for maintaining equipotential by connecting a cover for closing an upper bearing and a cover for closing a lower bearing to a ground pad. Japanese patent application No. 2004-.

The above-mentioned prior art references prevent the generation of a potential difference at the bearings by using an artificial ground member, but have problems in that the use of an additional member complicates the structure of the motor and increases the manufacturing cost.

In this regard, in order to solve the above-mentioned problems, the present invention uses a motor having a novel structure, which has an ungrounded structure (not disclosed in the prior art), can prevent damage of bearings, and reduce operational noise of the motor.

Disclosure of Invention

Technical problem

An object of the present invention is to provide a motor having a structure without grounding.

Another object of the present invention is to provide a motor capable of preventing electric corrosion of a bearing by a non-grounded structure.

It is still another object of the present invention to provide a motor capable of reducing manufacturing costs and reducing operating noise of the motor.

The above objects, and others that may be inferred therefrom, are readily achieved by the following description of the present invention.

Technical scheme

The motor 100 of the present invention includes: a stator 1 including an upper insulator 11, a stator core 12, and a lower insulator 13; a rotor 2 rotatably installed opposite to the stator 1; a shaft 20 coupled to the rotor 2 and rotating together therewith; and a printed circuit board 3 electrically connected to the stator 1, wherein the rotor 2 includes a rotor body 21 and a magnet 22 coupled to an outer circumferential surface of the rotor body 21, and the rotor body 21 is made of an insulating material.

In the present invention, it is preferable that the rotor body 21 is formed by injection molding, and the shaft 20 and the magnet 22 are placed in an in-mold injection mold.

In the present invention, it is preferable that the plurality of balance holes 21B opened to penetrate in the axial direction are formed symmetrically with respect to the shaft 20 of the rotor body 21.

In the present invention, the shaft 20 may be sealed using the insulating tube 20A.

In the present invention, it is preferable that the insulating tube 20A is sleeved (cover) on the shaft 20 ranging from a portion coupled with the upper bearing 4 to a portion coupled with the lower bearing 7.

Advantageous effects of the invention

The motor with the ungrounded structure has the advantages of preventing the bearing from electric corrosion, reducing the manufacturing cost and reducing the working noise of the motor.

Drawings

FIG. 1 is a perspective view of an electric machine according to the present invention;

FIG. 2 is an exploded top perspective view of the motor of the present invention;

FIG. 3 is an exploded bottom perspective view of the motor of the present invention;

FIG. 4 is an exploded perspective view of the rotor of the motor of the present invention;

fig. 5 is a perspective view showing a coupling condition of a rotor, a shaft and a bearing of the motor according to the present invention;

FIG. 6 is a graph showing noise measurements of the motor of the present invention compared to a conventional motor;

fig. 7 is a graph showing vibration measurement results of the motor of the present invention compared with a conventional motor.

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

Detailed Description

Fig. 1 is a perspective view of a motor 100 according to the present invention. Fig. 2 is an exploded top perspective view of the motor 100 of the present invention. Fig. 3 is an exploded bottom perspective view of the motor 100 of the present invention.

As shown in fig. 1 to 3, the motor 100 according to the present invention includes a stator 1, a rotor 2, and a printed circuit substrate 3, wherein the stator 1 and the printed circuit substrate 3 are disposed in a housing 10.

The stator 1 includes a stator core 12, and upper and

lower insulators

11 and 13 coupled to upper and lower portions of the stator core 12. A coil (not shown) is wound around a portion protruding to the inside of the stator 1, and the coil end is electrically connected to the printed circuit substrate 3.

The rotor 2 is placed inside the stator 1 and the rotor 2 is rotated by interaction with the changing magnetic field generated in the stator 1. The rotor 2 includes a rotor body 21 and a magnet 22 coupled to an outer circumferential surface of the rotor body 21. The shaft 20 is coupled with a central portion of the rotor body 21. When the rotor 2 rotates, the shaft 20 rotates together with the rotor 2. The shaft 20 is supported for rotation on the upper side by the upper bearing 4 and on the lower side by the lower bearing 7. The upper bearing 4 is coupled with a bearing housing 5, and the bearing housing 5 is fixedly installed in an upper protrusion 102 formed in a protruding shape at an upper portion of the housing 10. The lower bearing 7 is coupled to a center portion of the bearing cover 8, and an inner space 103 opened from a lower side to a lower portion of the housing 10 is covered with the bearing cover 8. The upper damper 6 is coupled with the upper protrusion 102 of the housing 10, and the lower damper 9 is coupled with the bearing cap 8 to mitigate motor vibration.

The printed circuit board 3 is placed on the upper portion of the upper insulator 11 of the stator 1. Preferably, the shape of the case 10 is manufactured by placing the stator 1 in an in-mold injection mold, placing the printed circuit board 3 on the upper portion of the stator 1, forming an electrical connection with a coil (not shown), and molding with resin. More preferably, the housing 10 is manufactured by in-mold injection molding by placing the bearing housing 5 at the upper portion of the center of the stator 1.

A lead drawer 101 is installed at one side of the case 10, and the lead drawer 101 guides the lead to electrically connect the printed circuit substrate 3 with an external power source. An upper protrusion 102 for receiving the bearing housing 5 is formed at the center of the upper portion of the housing 10. The shaft 20 may protrude from an upper portion at the center of the upper protrusion 102. The upper bearing 4 supporting the upper side of the rotatable shaft 20 is forcibly inserted into the bearing housing 5, and then the bearing housing 5 is installed inside the upper protrusion 102.

The inner space 103 forming the inner space of the housing 10 is opened to a lower side, and the rotor 2 coupled with the shaft 20 is rotatably disposed in the inner space 103. The portion opened to the lower side of the internal space 103 is covered with a bearing cover 8. A lower bearing 7 supporting a lower portion of the shaft 20 is coupled to the center of the bearing cap 8.

Fig. 4 is an exploded perspective view of the rotor 2 of the motor according to the present invention. Fig. 5 is a perspective view showing the coupling of the rotor 2, the shaft 20 and the bearings 4 and 7 of the motor according to the present invention. Referring to fig. 4 and 5, the rotor 2 of the present invention includes a rotor body 21 and a magnet 22.

The rotor body 21 is made of an insulating material such as rubber and is cylindrical. Preferably, the magnet 22 is coupled to an outer circumferential side of the rotor body 21 and has a ring shape. A shaft coupling hole 21A vertically penetrating and coupled to the shaft 20 is formed at the center of the rotor body 21. A plurality of balance holes 21B penetrating in the axial direction may be formed around the shaft coupling hole 21A. The balance hole 21B functions to prevent heat generation inside the rotor, thereby achieving smooth rotation while the rotor rotates. The number of the balance holes 21B is not particularly limited, but it is preferable that the balance holes 21B are opened symmetrically with respect to the shaft 20. Preferably, the rotor body 21 is made by in-mold injection molding, and the shaft 20 and the magnet 22 are placed in the in-mold injection mold.

An insulating tube 20A made of an insulating material may be coupled to an outer circumference of the shaft 20. Preferably, the insulating tube 20A may be made of the same material as the rotor body 21, and more preferably, the insulating tube 20A may be integrally formed with the rotor body 21 in an in-mold injection mold. Preferably, the insulating tube 20A is formed to be fitted over the shaft 20 in a range from a portion coupled with the upper bearing 4 to a portion coupled with the lower bearing 5.

As can be seen from comparing the motor of the present invention manufactured by the above method with the conventional motor, the bearing can be prevented from being electrically corroded without the grounding structure, and the noise and vibration of the motor can be reduced. Fig. 6 and 7 show experimental results of noise and vibration comparison.

FIG. 6 is a graph illustrating noise measurements of the motor 100 of the present invention compared to a conventional motor; fig. 7 is a graph of vibration measurement results.

In order to measure noise and vibration, the motor 100 according to the present invention uses the rotor body 21 made of rubber molded by an in-mold injection mold, but does not use the insulating tube 20A. Compared to the above-mentioned motors, the motors of the prior art have a rotor made of ferrite magnets. Part (a) of fig. 6 is a graph showing the result of noise measurement using the motor according to the present invention, and part (b) of fig. 6 is a graph showing the result of noise measurement using a conventional motor. From the results, it can be seen that the noise of the motor of the present invention is reduced by about 1.2dB compared to the conventional motor. Further, part (a) of fig. 7 is a graph showing the results of vibration measurement using the motor according to the present invention, and part (b) of fig. 7 is a graph showing the results of vibration measurement using a conventional motor. From the results, it can be seen that the vibration of the motor of the present invention is reduced by about 16.9um/s compared to the conventional motor.

The above-described embodiments of the present invention are merely illustrative examples that are helpful for understanding the present invention, and are not intended to limit the scope of the present invention. The scope of the invention is defined by the appended claims. Further, it should be understood that simple modifications or alterations to the present invention are still within the scope of the present invention.

Claims

1. A kind of motor is disclosed, which comprises a motor,

the method comprises the following steps:

a stator (1) including an upper insulator (11), a stator core (12), and a lower insulator (13);

a rotor (2) rotatably mounted opposite to the stator (1);

a shaft (20) coupled to said rotor (2) and rotating therewith; and

a printed circuit board (3) electrically connected to the stator (1),

wherein the rotor (2) comprises a rotor body (21) and a magnet (22) coupled with the outer peripheral surface of the rotor body (21),

the rotor body (21) is made of an insulating material.

2. The electric machine according to claim 1, wherein the rotor body (21) is formed by injection molding, and the shaft (20) and the magnet (22) are placed in an in-mold injection mold.

3. The electric machine according to claim 1, wherein a plurality of balancing holes (21B) opened through in the axial direction are formed symmetrically with respect to the shaft (20) on the rotor body (21).

4. The machine according to claim 1, wherein the shaft (20) is sealed with an insulating tube (20A).

5. The motor according to claim 4, wherein the insulating tube (20A) is fitted over the shaft (20) in a range from a portion coupled with the upper bearing (4) to a portion coupled with the lower bearing (7).