Shaft of bled motor

Abstract

The present invention relates to a shaft of a BLDC motor, and more specifically, to a shaft of a BLDC motor that can insulate not only between the outer surface of the shaft and the inner surface of the ball bearing, but also between the lower surface of the head part and the upper surface of the ball bearing, as a single component. The shaft of the BLDC motor according to the present invention comprises: a cylindrical body; a head portion provided on the upper part of the body and having a larger diameter than the body; a shaft coupling portion provided on the lower part of the body and coupled to a drive shaft; an upper insulator formed on the outer surface of the portion of the body where an upper ball bearing is mounted; and a lower insulator provided on the outer surface of the portion of the body where a lower ball bearing is mounted; wherein the upper part of the upper insulator is characterized by having a diameter expansion portion formed therein.

Description

Technology Field

[0001] The present invention relates to a shaft of a BLDC motor, and more specifically, to a shaft of a BLDC motor that can insulate not only between the outer surface of the shaft and the inner surface of the ball bearing, but also between the lower surface of the head part and the upper surface of the ball bearing, as a single component. Background Technology

[0003] Generally, a motor is a device that converts electrical energy into mechanical energy to obtain rotational force, and it is widely used in household electronic products as well as industrial equipment, and is broadly divided into DC motors and AC motors.

[0004] In DC motors, brushed motors function to rectify current by allowing it to flow through the coils through contact between the commutator and the brushes, but they have the disadvantage of brush wear. To overcome this disadvantage, brushless BLDC motors are known.

[0005] BLDC motors are widely used these days because they have high torque and excellent controllability, as well as the ability to achieve speed

[0004] .

[0006] BLDC motors are classified into internal and external types depending on the position of the rotor. Internal BLDC motors have a smaller outer diameter of the rotor compared to external BLDC motors, which allows for a smaller moment of inertia and is suitable for applications requiring fast response. However, high-speed rotation is difficult due to limitations in the mechanical strength of the permanent magnets and the adhesion strength with the rotor. On the other hand, external BLDC motors have a larger outer diameter of the rotor, which results in a larger moment of inertia, but they are suitable for high-speed applications because permanent magnets can be attached to the inside of the rotor.

[0007] Figure 1 shows a cross-sectional view of a general BLDC motor according to the prior art.

[0008] As illustrated in FIG. 1, a BLDC motor (10) according to the prior art comprises a shaft (11) forming a rotation axis, a rotor (16) having a permanent magnet (16a) that is provided to pass through the center of the shaft (11) and rotates around the shaft to form a magnetic field, a stator core (15) having a coil (not shown) wound thereon that is provided to be spaced apart from the permanent magnet (16a) and generates torque through interaction with the magnetic field of the permanent magnet (16a), a bearing bracket (14) inserted and mounted in the internal hollow of the stator core (150), and a ball bearing (13) in which an inner ring (13b) is externally fitted to the shaft (11) and an outer ring (13c) is internally fitted to the bearing bracket (14) to perform rotation of the shaft (11).

[0009] That is, the shaft (11) is rotatably installed via a ball bearing (13) and fixed to the center of the rotor (16) so as to rotate together with the rotor (16), and the rotor (16) has a permanent magnet (16a) installed inside that is alternately magnetized with N and S poles.

[0010] In addition, a control board (not shown) is provided inside the housing, which is equipped with a driving circuit that applies current to a coil (not shown) and a magnetic field detection element such as a Hall sensor that detects the magnetic field of a permanent magnet (16a).

[0011] In a conventional BLDC motor (10) having the configuration as described above, current is supplied to a coil wound on a stator core (15) by a driving circuit of a control board, and the generated magnetic flux is transmitted through the core (15) to an upper permanent magnet (16a), thereby causing the rotor (16) to rotate. At this time, a signal regarding the magnetic pole of the permanent magnet (16a) detected by a magnetic pole detection element installed on the control board is transmitted to the driving circuit of the control board, and power is supplied to the coil with a different polarity so that the coil has a different magnetic pole, thereby enabling the continuous rotation of the rotor (16).

[0012] However, a BLDC motor according to the prior art having the above configuration had the following problems.

[0013] When the shaft (11) rotates at high speed together with the rotor (16), induced charges generated by the high-speed rotation of the rotor (16) are formed along the outer surface (11a) of the shaft (11), and these induced charges are moved to the ball bearing (13), and a fine scratch is formed on the ball (13a) inside the ball bearing (13) due to the instantaneous discharge (spark) of these induced charges.

[0014] When the product is shipped, the ball (13a) inside the ball bearing (13) is processed to be very smooth. However, due to the instantaneous discharge of the induced charge as described above, fine scratches are formed on the ball (13a) inside the ball bearing (13). If the instantaneous discharge caused by the induced charge is performed continuously, the scratches formed on the ball (13a) increase in number and size.

[0015] In this way, when scratches occur on the ball (13a) inside the ball bearing (13), there was a problem in that noise was generated due to friction between the inner ring (13b) and the outer ring (13c) during the rotation process of the ball (13a) rotating and revolving due to the high-speed rotation of the shaft (11).

[0016] In addition, if there is a scratch on the ball (13a) inside the ball bearing (13), the rotation of the ball bearing (13) itself may not be smooth, and this naturally leads to a product defect. Prior art literature

[0018] Registered Patent No. 10-1869017 Registered Patent No. 10-1667289 Registered Patent No. 10-0963295 Registered Patent No. 10-0961653 The problem to be solved

[0019] The present invention has been devised to solve the aforementioned problems, and the objective of the present invention is to provide a BLDC motor shaft that can prevent galvanic corrosion of the bearing by insulating the outer surface of the shaft with an insulator so that the induced charge formed on the outer surface of the shaft is not transferred to the ball bearing while the BLDC motor shaft rotates at high speed together with the rotor.

[0020] Another objective of the present invention is to provide a shaft of a BLDC motor that can insulate not only the outer surface of the shaft and the inner surface of the ball bearing, but also the lower surface of the head and the upper surface of the ball bearing, with a single component. means of solving the problem

[0022] To solve the above technical problem, the shaft of a BLDC motor according to the present invention comprises: a cylindrical body; a head portion provided on the upper part of the body and having a larger diameter than the body; a shaft coupling portion provided on the lower part of the body and coupled to a drive shaft; an upper insulator formed on the outer surface of the portion of the body where an upper ball bearing is mounted; and a lower insulator provided on the outer surface of the portion of the body where a lower ball bearing is mounted; wherein the upper part of the upper insulator is characterized by having a diameter expansion portion formed therein.

[0023] In addition, it is preferable that an insulating groove be formed in the body at a location where the upper insulator or the lower insulator is provided.

[0024] In addition, it is preferable that the above insulating groove be in the shape of a polygonal column.

[0025] In addition, the insulating groove is preferably formed in a cylindrical shape with a diameter smaller than that of the body, and at least one chamfered portion is formed.

[0026] In addition, it is preferable that the length of the upper insulator is smaller than the height of the upper ball bearing.

[0027] In addition, it is preferable that the outer diameter of the diameter expansion portion is equal to or smaller than the outer diameter of the head portion.

[0028] In addition, it is preferable that the length of the lower insulator is smaller than the height of the lower ball bearing.

[0029] In addition, it is preferable that the outer diameter of the upper insulator or lower insulator be the same as the outer diameter of the body.

[0030] In addition, it is preferable that the upper insulator or the lower insulator be formed by insert injection molding into the body. Effects of the invention

[0032] According to the present invention, as the shaft of a BLDC motor rotates at high speed together with the rotor, the induced charge formed on the outer surface of the shaft is insulated so that it is not transferred to the ball bearing, thereby preventing galvanic corrosion of the bearing, improving the durability of the bearing, and preventing noise generation.

[0033] In particular, a diameter expansion portion is formed in the upper insulator that is insert-molded on the upper part of the shaft, so that insulation can be provided not only between the outer surface of the shaft and the inner surface of the ball bearing, but also between the lower surface of the head portion and the upper surface of the ball bearing.

[0034] Accordingly, since there is no separate washer assembly, assembly is improved, and there is a reduction in manufacturing time and cost reduction effect. Brief explanation of the drawing

[0036] Figure 1 is a cross-sectional view showing the configuration of a conventional BLDC motor. Figure 2 shows the shaft of a BLDC motor according to the present invention. FIGS. 3 and FIGS. 4 show various embodiments of the shaft illustrated in FIGS. 2. FIGS. 5 to 7 are perspective and cross-sectional views of a BLDC motor to which an embodiment according to the present invention is applied. Specific details for implementing the invention

[0037] Hereinafter, the shaft of a BLDC motor according to the present invention will be described in detail with reference to the attached drawings.

[0038] Referring to FIG. 2, the shaft (100) of the BLDC motor (200) according to the present invention includes a body (110), a head portion (120) provided on the upper part of the body (110), and a shaft coupling portion (130) provided on the lower part of the body (110).

[0039] The body (110) is formed in a cylindrical shape overall, and the head portion (120) formed on the upper part of the body (110) is formed in a cylindrical shape with a diameter larger than that of the body (110).

[0040] The shaft coupling part (130) is a component provided at the lower part of the body (110) and coupled with a drive shaft (not shown).

[0041] Additionally, it can be seen that the body (110) is provided with an upper insulator (140) and a lower insulator (150) at the top and bottom, respectively. The upper ball bearing and shaft (body, insulating groove) and the lower ball bearing and shaft (body, insulating groove) are insulated by the upper insulator (140) and the lower insulator (150), respectively.

[0042] The upper insulator (140) and the lower insulator (150) are firmly formed with a thickness of 0.6 mm to 1.0 mm using a known insulating material such as polyamide, and in this embodiment, they are integrally formed by insert injection molding on the shaft (100). At this time, the diameter expansion portion (141) is also integrally formed on the upper insulator (140).

[0044] In particular, it can be seen that the upper insulator (140) has a diameter expansion portion (141) formed on its upper side. That is, the diameter expansion portion (141) is formed by being bent outward from the top of the upper insulator (140).

[0045] In the above body (110), an insulating groove (11, 112) is formed at the location where the upper insulator (140) and the lower insulator (150) are joined.

[0046] In this way, since insulating grooves (111, 112) are formed in the body (110), even if the upper insulator (140) and the lower insulator (150) are formed to be 0.6mm to 1.0mm, their outer diameters can be formed to be the same as the outer diameter of the body (110) and not larger.

[0047] Various embodiments such as those shown in FIG. 3 and FIG. 4 may be applied as means to increase the adhesion of the upper insulator (140) and the lower insulator (150) to the body (110).

[0048] For example, it can be seen that the insulating grooves (111) formed on the upper and lower parts of the body (110) are in the shape of polygonal columns. That is, the cross-sectional shape in the direction perpendicular to the axial direction of the shaft (100) is polygonal (see FIG. 3).

[0049] In another form, the insulating groove (112) formed on the upper and lower parts of the body (110) may be formed in a cylindrical shape with a diameter smaller than that of the body (110), and chamfered portions (112a) may be formed on both facing sides (see FIG. 4). Unlike what is shown in FIG. 4, only one chamfered portion (112a) may be formed, or three or more may be formed.

[0050] By forming the insulating grooves (111, 112) in this way, the adhesion between the upper insulator (140) and the lower insulator (150) can be increased.

[0051] FIGS. 5 to 7 show a BLDC motor (200) to which a shaft (100) according to the present invention is applied.

[0052] As described above, the BLDC motor (200) comprises a shaft (100) forming a rotation axis, a rotor (210) having a permanent magnet that is provided to rotate around the shaft (100) and form a magnetic field by passing through the center of the shaft (100), a stator (220) having a coil (not shown) wound thereon that is provided to be spaced apart from the permanent magnet and generates torque by interaction with the magnetic field of the permanent magnet, a bracket (260) inserted and mounted in the internal hollow of the stator (220), and an upper ball bearing (240) and a lower ball bearing (250) having an inner ring that is externally fitted to the shaft (100) and an outer ring that is internally fitted to the bracket (260) to perform rotation of the shaft (100).

[0053] That is, the shaft (100) is rotatably installed via ball bearings (240, 250) and fixed to the center of the rotor (210) so as to rotate together with the rotor (210), and the rotor (210) has permanent magnets installed inside that are alternately magnetized with N and S poles.

[0054] In addition, a control board (not shown) equipped with a driving circuit that applies current to a coil (not shown) and a magnetic pole detection element such as a Hall sensor that detects the magnetic pole of a permanent magnet is provided inside the housing.

[0055] In the BLDC motor (200) configured in this manner, current is supplied to the coil wound on the stator (220) by the driving circuit of the control board, and the generated magnetic flux is transmitted through the stator (220) to the upper permanent magnet, thereby causing the rotor (210) to rotate. At this time, a signal regarding the magnetic pole of the permanent magnet detected by the magnetic pole detection element installed on the control board is transmitted to the driving circuit of the control board, and power is supplied to the coil with a different polarity so that the coil has a different magnetic pole, thereby enabling the continuous rotation of the rotor (210).

[0056] Meanwhile, according to the present invention, it can be seen that an upper insulator (140) is provided between the upper ball bearing (240) and the shaft (100) to provide insulation.

[0057] In particular, the upper insulator (140) has a diameter expansion portion (141) formed at the top and is assembled by being placed between the lower surface of the head portion (120) and the upper surface of the upper ball bearing (240).

[0058] Therefore, it can be seen that the lower surface of the head portion (120) and the upper surface of the upper ball bearing (240) are insulated by the diameter expansion portion (141).

[0059] In other words, without a separate insulating part such as an insulating washer, the upper insulator can insulate the outer surface of the shaft (100) and the inner surface of the upper ball bearing (240), and at the same time insulate the lower surface of the head part (120) and the upper surface of the upper ball bearing (240), thereby improving assembly and productivity and reducing manufacturing costs.

[0060] It is preferable that the length of the upper insulator (140) be smaller than the height of the upper ball bearing (240).

[0061] Likewise, it is preferable to form the length of the lower insulator (150) smaller than the height of the lower ball bearing (250).

[0062] In addition, it can be seen that the diameter expansion portion (141) of the upper insulator (140) is formed with an outer diameter smaller than the outer diameter of the head portion (120).

[0063] In addition, a lower washer (271) and a snap ring (272) are coupled to the lower part of the lower ball bearing (250) in the shaft coupling part (130). The lower washer (271) is a component that protects the lower ball bearing (250) to prevent it from being damaged.

[0064] According to the present invention, the bushing (230) connecting the rotor to the shaft and the upper ball bearing (240) are spaced apart so as not to come into contact. Furthermore, the upper insulator (140) and the lower insulator (150) are provided to completely isolate the ball bearings (240, 250).

[0065] Therefore, the induced charge formed by the rotation of the shaft (100) is transferred to the ball bearings (240, 250), preventing the balls inside the ball bearings from being electrolytically corroded, so that a smooth state can always be maintained.

[0066] In addition, the shaft (100), which is integrally formed by insert injection molding of the upper insulator (140) and the lower insulator (150), can rotate more smoothly together with the ball bearings (240, 250).

[0067] Although the present invention has been described in detail above only with respect to the specific embodiments described, it is obvious to those skilled in the art that various modifications and variations are possible within the scope of the technical spirit of the invention, and it is natural that such modifications and variations fall within the scope of the appended claims. Explanation of the symbols

[0069] 100: Shaft 110: Body 111, 112: Insulating groove 112a: Chamfered part 120: Head section 130: Shaft coupling 140: Upper insulator 141: Diameter expansion part 150: Lower insulator 200: BLDC motor 210: Rotor 220: Status 230: Bushing 240: Upper ball bearing 250: Lower ball bearing 260: Bracket 271: Bottom washer 272: Snap ring

Claims

Claim 1 A shaft of a BLDC motor comprises: a cylindrical body; a head portion provided on the upper part of the body and having a diameter larger than that of the body; a shaft coupling portion provided on the lower part of the body and coupled to a drive shaft; an upper insulator formed on the outer surface of the portion of the body where an upper ball bearing is mounted; and a lower insulator provided on the outer surface of the portion of the body where a lower ball bearing is mounted; wherein the upper insulator includes a diameter expansion portion that is bent outward from the upper end of the upper insulator and interposed between the lower surface of the head portion and the upper surface of the upper ball bearing, and is characterized by insulating the outer surface of the body and the inner surface of the upper ball bearing, while simultaneously insulating the lower surface of the head portion and the upper surface of the upper ball bearing by the diameter expansion portion. Claim 2 A shaft of a BLDC motor according to claim 1, characterized in that an insulating groove is formed in the body at a position where the upper insulator or the lower insulator is provided. Claim 3 A shaft of a BLDC motor according to claim 2, characterized in that the insulating groove is formed in a polygonal column shape to increase the adhesion between the upper insulator and the lower insulator. Claim 4 A shaft of a BLDC motor according to claim 2, wherein the insulating groove is formed in a cylindrical shape with a diameter smaller than that of the body, and chamfered portions are formed on both opposing sides to increase the adhesion between the upper insulator and the lower insulator. Claim 5 A shaft of a BLDC motor according to claim 1, characterized in that the length of the upper insulator is smaller than the height of the upper ball bearing. Claim 6 A shaft of a BLDC motor according to claim 1, characterized in that the outer diameter of the diameter expansion portion is equal to or smaller than the outer diameter of the head portion, the length of the lower insulator is smaller than the height of the lower ball bearing, and the outer diameter of the upper insulator or the lower insulator is equal to the outer diameter of the body. Claim 7 A shaft of a BLDC motor according to claim 1, characterized in that the bushing coupled to the shaft and the upper ball bearing are installed spaced apart so as not to come into contact. Claim 8 delete Claim 9 A shaft of a BLDC motor according to claim 1, characterized in that the upper insulator or the lower insulator is formed by insert injection molding on the body.

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