Ungrounded Motor

Abstract

The motor (100) according to the present invention comprises: a stator (1) comprising an upper insulator (11), a stator core (12) and a lower insulator (13); a rotor (2) mounted relative to the stator (1) and capable of rotating; a shaft (20) coupled to the rotor (2) and rotating together with the rotor (2); 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 to the outer peripheral surface of the rotor body (21), and the rotor body (21) is made of insulating material.

Description

Technical Field

[0001] The present invention relates to a motor, and more particularly to a motor with a novel structure, which can prevent damage caused by electrical corrosion of bearings and reduce noise generated in the motor by eliminating the grounding structure of the motor and improving the motor to have an ungrounded structure. Background Art

[0002] The motor usually consists of a stator and a rotor. The magnetic field formed by the stator causes the rotor to rotate. The shaft is coupled to the rotor and rotates with the rotor. The upper and lower parts of the rotor are equipped with bearings to support the rotation of the shaft.

[0003] The motor is usually controlled by a drive circuit. When the drive circuit is working, the potential difference between the bearing and the shaft or the axial flow caused by other reasons causes the bearing to corrode. When the motor is working, the electrocorrosion generates noise and vibration, which has an adverse effect on the motor performance and durability.

[0004] In order to prevent the electrical corrosion of the bearing, Korean Patent Application No. 10-2008-0109168 discloses a technology for preventing the electrical corrosion of the bearing, which establishes equal potential on both sides by connecting the output bracket of the closed upper bearing and the opposite output bracket of the closed lower bearing using a conductive tape. However, since the structural strength of the parts fixing the ends of the conductive tape is weak, it is difficult to maintain equal potential.

[0005] Meanwhile, 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. This prior art achieves effective grounding between the upper bearing cover and the lower bearing cover, but since the structure is that the bearings are nested outside the upper bearing cover and the lower bearing cover, the two bearings are easily exposed to the outside. In particular, since the end of the grounding metal member in this structure is slightly in contact with the side of the lower bearing cover, the grounding member may be separated, and thus the occurrence of electrical corrosion of the bearing cannot be effectively prevented.

[0006] 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 grounding plate. Japanese Patent Application No. 2004-229429 discloses a structure for maintaining ground potential by connecting a bearing, a bearing cover, and a stator core.

[0007] The above-mentioned prior art references prevent potential differences from being generated at the bearings by using artificial grounding members, but there is a problem in that the use of additional members makes the motor structure complicated and increases the manufacturing cost.

[0008] In this regard, in order to solve the above problems, the inventors propose to use a motor with a new structure, which has a non-grounding structure (not disclosed in the prior art) to prevent bearing damage and reduce the working noise of the motor. Summary of the invention

[0009] Technical issues

[0010] An object of the present invention is to provide a motor with an ungrounded structure.

[0011] Another object of the present invention is to provide a motor capable of preventing electrical corrosion of bearings through an ungrounded structure.

[0012] Another object of the present invention is to provide a motor that can reduce manufacturing costs and reduce motor operating noise.

[0013] The above-mentioned object and other objects inferred therefrom can be easily achieved through the following description of the present invention.

[0014] Technical Solution

[0015] The motor 100 described in the present invention includes: a stator 1, including an upper insulator 11, a stator core 12 and a lower insulator 13; a rotor 2, which is installed relative to the stator 1 and can rotate; a shaft 20, which is coupled to the rotor 2 and rotates together with it; and a printed circuit substrate 3, which is electrically connected to the stator 1, wherein the rotor 2 includes a rotor body 21 and a magnet 22 coupled to the outer peripheral surface of the rotor body 21, and the rotor body 21 is made of insulating material.

[0016] In the present invention, preferably, 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.

[0017] In the present invention, preferably, a plurality of balancing holes 21B penetrating along the axial direction are formed on the rotor body 21 symmetrically with respect to the shaft 20 .

[0018] In the present invention, the shaft 20 may be sealed using the insulating tube 20A.

[0019] In the present invention, preferably, the insulating tube 20A is covered on the shaft 20 , and the covering range is from the part coupled with the upper bearing 4 to the part coupled with the lower bearing 7 .

[0020] Advantageous Effects of the Invention

[0021] The beneficial effects of the motor with an ungrounded structure of the present invention are to prevent bearing electrical corrosion, reduce manufacturing costs and reduce the working noise of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a perspective view of the motor according to the present invention;

[0023] Figure 2 is an exploded top perspective view of the motor of the present invention;

[0024] Figure 3 It is an exploded bottom perspective view of the motor of the present invention;

[0025] Figure 4 is an exploded perspective view of the motor rotor of the present invention;

[0026] Figure 5 A perspective view showing the coupling of the rotor, shaft and bearing of the motor according to the present invention;

[0027] Figure 6 A graph showing noise measurement results of the motor of the present invention compared with a conventional motor;

[0028] Figure 7 FIG. 5 is a graph showing vibration measurement results of the motor according to the present invention compared with a conventional motor.

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

[0030] Figure 1 FIG. 1 is a perspective view of the motor 100 according to the present invention. Figure 2 It is an exploded top perspective view of the motor 100 according to the present invention. Figure 3 It is an exploded bottom perspective view of the motor 100 according to the present invention.

[0031] like Figure 1-Figure 3 As shown, the motor 100 of the present invention comprises 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 .

[0032] The stator 1 includes a stator core 12 and upper and lower insulators 11 and 13 coupled to the upper and lower portions of the stator core 12. A coil (not shown) is wound around a portion protruding inside the stator 1, and the coil end is electrically connected to the printed circuit board 3.

[0033] The rotor 2 is placed inside the stator 1, and the rotor 2 rotates by interacting with the changing magnetic field generated in the stator 1. The rotor 2 includes a rotor body 21 and a magnet 22 coupled to the outer peripheral surface of the rotor body 21. The shaft 20 is coupled to the central portion of the rotor body 21. When the rotor 2 rotates, the shaft 20 rotates together with the rotor 2. The upper side of the shaft 20 rotates by the support of the upper bearing 4, and the lower side rotates by the support of the lower bearing 7. The upper bearing 4 is coupled to the bearing seat 5, and the bearing seat 5 is fixedly installed in the upper protrusion 102 formed in a protruding shape on the upper part of the housing 10. The lower bearing 7 is coupled to the central portion of the bearing cover 8, and the internal space 103 opened from the lower side to the lower part of the housing 10 is covered with the bearing cover 8. The upper damper 6 is coupled to the upper protrusion 102 of the housing 10, and the lower damper 9 is coupled to the bearing cover 8 to mitigate the vibration of the motor.

[0034] The printed circuit substrate 3 is placed on the upper part of the upper insulator 11 of the stator 1. Preferably, the stator 1 is placed in an in-mold injection mold, the printed circuit substrate 3 is placed on the upper part of the stator 1, and is electrically connected to the coil (not shown), and is molded by resin to produce the shape of the housing 10. More preferably, the housing 10 is produced by placing the bearing seat 5 on the upper part of the center of the stator 1 and using in-mold injection molding.

[0035] A lead wire drawing member 101 is installed on one side of the housing 10. The lead wire drawing member 101 guides the lead wires so that the printed circuit board 3 is electrically connected to the external power supply. An upper protrusion 102 for accommodating the bearing seat 5 is formed at the center of the upper part of the housing 10. The shaft 20 can extend from the upper part of the center of the upper protrusion 102. The upper bearing 4 supporting the upper side of the rotatable shaft 20 is inserted into the bearing seat 5 by force, and then the bearing seat 5 is installed inside the upper protrusion 102.

[0036] The inner space 103 forming the inner space of the housing 10 is open to the lower side, and the rotor 2 coupled to the shaft 20 is rotatably placed in the inner space 103. The portion open to the lower side of the inner space 103 is covered with a bearing cover 8. The lower bearing 7 supporting the lower part of the shaft 20 is coupled to the center of the bearing cover 8.

[0037] Figure 4 It is an exploded perspective view of the motor rotor 2 according to the present invention. Figure 5 FIG. 2 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. Figure 4 and Figure 5 The rotor 2 of the present invention includes a rotor body 21 and a magnet 22 .

[0038] The rotor body 21 is made of insulating materials such as rubber and is cylindrical. Preferably, the magnet 22 is coupled to the outer peripheral side of the rotor body 21 and is annular. A shaft coupling hole 21A is provided at the center of the rotor body 21 to couple with the shaft 20 in a vertical penetration manner. A plurality of balancing holes 21B may be provided around the shaft coupling hole 21A and are axially penetrated. The function of the balancing hole 21B is to prevent heat from being generated inside the rotor, thereby achieving smooth rotation while the rotor rotates. There is no specific restriction on the number of balancing holes 21B, however, it is preferred that the balancing holes 21B are symmetrically provided 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 an in-mold injection mold.

[0039] The insulating tube 20A made of insulating material can be coupled to the outer circumference of the shaft 20. Preferably, the insulating tube 20A can be made of the same material as the rotor body 21, and more preferably, the insulating tube 20A can be integrally formed with the rotor body 21 in an in-mold injection mold. Preferably, the insulating tube 20A is molded and sleeved on the shaft 20, and the sleeve range is from the part coupled with the upper bearing 4 to the part coupled with the lower bearing 7.

[0040] By comparing the motor of the present invention manufactured according to the above method with a conventional motor, it can be seen that, in the absence of a grounding structure, electrical corrosion of the bearing can be prevented and motor noise and vibration can be reduced. Figure 6 and Figure 7 Experimental results of noise and vibration comparison are shown.

[0041] Figure 6 A graph showing noise measurement results of the motor 100 of the present invention compared with a conventional motor; Figure 7 This is a graph of vibration measurement results.

[0042] In order to measure noise and vibration, the motor 100 of the present invention uses a rotor body 21 made of rubber formed by in-mold injection molding, but does not use an insulating tube 20A. Compared with the above motor, the motor described in the prior art has a rotor made of ferrite magnets. Figure 6 Part (a) is a graph showing the noise measurement results of the motor according to the present invention. Figure 6 Part (b) of FIG. 1 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 1.2 dB compared with the conventional motor. In addition, Figure 7 Part (a) is a graph showing the result of vibration measurement using the motor of the present invention, Figure 7 Part (b) is a graph showing the results of vibration measurement using a conventional motor. From the results, it can be seen that compared with the conventional motor, the vibration of the motor of the present invention is reduced by about 16.9 um / s.

[0043] The specific embodiments of the present invention described above are only provided for explanation of 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 present invention is limited by the scope of the attached invention claims. In addition, it should be understood that simple modifications or changes to the present invention still belong to the scope of the present invention.

Claims

1. A motor, include: A stator (1) comprising an upper insulator (11), a stator core (12) and a lower insulator (13); a rotor (2) mounted opposite to the stator (1) and capable of rotating; a shaft (20) coupled to the rotor (2) and rotating therewith; as well as a printed circuit board (3) electrically connected to the stator (1), The rotor (2) comprises a rotor body (21) and a magnet (22) coupled to the outer peripheral surface of the rotor body (21). The rotor body (21) is made of insulating material. 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. The shaft (20) is sealed by using an insulating tube (20A), wherein the insulating tube (20A) is made of the same material as the rotor body (21), and the insulating tube (20A) is integrally formed with the rotor body (21) in an in-mold injection mold. The insulating tube (20A) is sleeved on the outer circumference of the shaft (20), and the sleeve range is from the part coupled with the upper bearing (4) to the part coupled with the lower bearing (7).

2. The motor according to claim 1, wherein: A plurality of balancing holes (21B) penetrating along the axial direction are formed on the rotor body (21) symmetrically with respect to the shaft (20).

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