KR20020046895A - A magnetic bearing and a motor using the magnetic bearing - Google Patents

Abstract

PURPOSE: A magnetic bearing and motor using such magnetic bearing is provided to achieve improved reliability by reducing vibration and noise caused due to the contact between each component. CONSTITUTION: A motor comprises a printed circuit board(110); a sleeve(100) fixed at the central surface of the printed circuit board, and which has a stator(120) arranged at the outer surface of the sleeve, wherein the stator is constituted by a core(121) and a coil(122); a rotor(200) having a magnet(220) for cooperating with the stator to generate a rotating electromagnetic force, and a shaft(500) penetrating through the center of the sleeve, wherein the magnet is fixed through a yoke(230); a rotor magnet group constituted by first to third magnets(610,620,630) arranged at the outer periphery of the shaft of the rotor; and a sleeve magnet group constituted by fourth and fifth magnets(640,650) arranged among the first to third magnets of the rotor magnet group and at the inner periphery of the sleeve.

Description

Magnetic bearing and a motor using the magnetic bearing}

The present invention relates to a magnetic bearing and a motor for a small precision device using such a magnetic bearing, and more particularly, to a magnetic bearing capable of maintaining a fully floating state in the lateral direction and the axial direction by mutual magnetic force of a magnet, and such a magnetic bearing. It relates to a motor that can maintain a stable driveability at high speed by employing.

In general, a motor is not only classified into a rotating shaft type and a fixed shaft type according to the shaft support method, but also classified into a rolling bearing support method and a sliding bearing support method according to the support method of the driving unit.

Rolling bearings are generally designed to support shafts through one or more ball bearings, and inexpensive ball bearings provide cost savings and large ball rigidity between inner and outer rings. It has the advantage that it can be used for a long time.

On the other hand, there is a problem in that high precision rotation accuracy cannot be obtained, and it is applicable to some degree of low speed rotation, but there is a problem in that it is difficult to apply to products requiring high speed rotation.

That is, when applied to a motor of a recording medium that requires high-speed rotation, not only severe vibration is caused by the gap between the ball and the inner and outer rings, but also a noise is caused.

On the other hand, the sliding bearing support method is to support a shaft by forming a metal bearing containing fluid or an oil film through oil, or a shaft through a ball bearing. While there is a disadvantage of unit price increase compared to the support method, it is possible to maintain a high degree of rotation, so that recording media that require high speed rotation such as hard disk drive (HDD) or CD-ROM in recent years It is widely adopted in the motor of).

1 shows a motor employing a general sliding bearing support method.

It includes a sleeve 10 in which the circuit board 11 is fixedly installed on the upper outer surface.

On the outer side of the sleeve 10, a stator 20 made of a coil 22 is provided.

In addition, a lower end portion of a shaft 30 in which herringbone-shaped grooves 31 and 32 are formed on upper and lower outer peripheral surfaces of the sleeve 10 is press-fitted.

A rotor 40 is positioned on the upper surface of the above-described sleeve 10, and the magnet 41 is configured to generate a rotating electromagnetic force together with the stator 20 on the lower inner surface of the rotor 40 to yoke ( 42) is fixedly installed.

In addition, the polygon mirror 50 is fixed to the upper surface of the rotor 40 by the cover 60 and the leaf spring (70).

In the conventional motor having such a configuration, when the rotor 40 is rotated at a high speed through the rotating electromagnetic force between the magnet 41 and the stator 20, the load bearing capacity is equal to the herringbone shaped portions 31 and 32 of the shaft 30. ) And the air gap formed between the inner circumferential surface of the rotor 40, that is, through the air membrane.

However, in such a conventional motor, the herringbone-shaped grooves 31 and 32 are formed on the shaft 30 in order to support the load in the radial direction, but are sufficient through the herringbone-shaped grooves 31 and 32. When no pneumatic pressure is generated or when the assembly tolerance is not accurate, a problem arises in that a contact is generated between the sleeve 10 and the rotor 40 by causing an imbalance in the force causing the rotor 40 to rise.

In particular, the processing of the grouts 31, 32 and the rotor 40 for generating the pneumatic pressure is very difficult, as well as the contact of the motors due to the contact between the parts when the floating force is generated by the air gap formed therebetween. This results in a problem that the driving characteristics become very poor.

In addition, although the polygon mirror 50 is seated on the upper surface of the rotor 40 through the cover 60 and the leaf spring 70, it is difficult to overcome the centrifugal force generated when the rotor 40 rotates at high speed. This causes a problem that the mirror 50 is disengaged.

The present invention was created in order to solve the conventional problems as described above, the object of the present invention can not only improve the degree of rotation of the rotor, but also prevent the wear of the sleeve in advance, and in particular the mutual The present invention provides a magnetic bearing capable of fundamentally eliminating mechanical loss and noise generated when the motor rotates by maintaining a fully floating state in which the magnetic force alone does not contact each other in the lateral and axial directions. There is a purpose.

1 is a cross-sectional view of a general motor.

2 is a cross-sectional view showing a motor of a core type according to the present invention.

3 is a cross-sectional view showing another embodiment of FIG.

4 is a cross-sectional view showing a motor of a coreless type according to the present invention.

5 is a cross-sectional view showing another embodiment of FIG.

6 to 8 are schematic diagrams showing the operating principle of the motor according to the present invention.

9 is a graph showing the magnetic flux density at the symmetry point of each magnet in the motor according to the present invention.

10 to 11 are graphs showing the operating characteristics of the motor according to the present invention.

<Explanation of symbols for main parts of drawing>

100: sleeve 110: circuit board

120: stator 121: core

122: coil 200: rotor

220: magnet 230: yoke

300: polygon mirror 310: hanging groove

400: cover 410: locking groove

500: shaft 600: (plural) magnet

610-650: first to fifth magnets

One embodiment of the present invention for realizing the above object is a circuit board; A sleeve fixedly installed at a center surface of the circuit board and having a stator including a core and a coil at an outer surface thereof; A rotor having a magnet for generating a rotating electromagnetic force together with the stator, fixedly installed through a yoke, and having a shaft integrally formed at a center surface thereof through a center surface of the sleeve; A rotor magnet group provided in plural at predetermined intervals on an outer circumferential surface of the shaft of the rotor; Characterized in that it comprises a sleeve magnet group provided on the inner peripheral surface of the sleeve corresponding to each of the magnets constituting the rotor magnet group.

Each magnet constituting the rotor magnet group and the sleeve magnet group of the present invention is characterized by being composed of a ratio of n + 1: n.

The magnets constituting the rotor magnet group and the sleeve magnet group of the present invention are characterized by being composed of a ratio of n: n + 1.

The rotor magnet group and the sleeve magnet group of the present invention are characterized in that magnetic poles are arranged to have a repulsive force with each other.

The magnets constituting the rotor magnet group and the sleeve magnet group of the present invention are characterized in that they are permanent magnets.

The upper surface of the rotor of the present invention is characterized in that the polygon mirror is pressed by the cover seated.

Another embodiment of a motor using a magnetic bearing according to the present invention includes a circuit board; A sleeve fixed to a center surface of the circuit board and provided with a stator including a coil on an outer surface thereof; A rotor having a magnet for generating a rotating electromagnetic force together with the stator, fixedly installed through a yoke, and having a shaft integrally formed at a center surface thereof through a center surface of the sleeve; A rotor magnet group provided in plural at predetermined intervals on an outer circumferential surface of the shaft of the rotor; Characterized in that it comprises a sleeve magnet group provided on the inner peripheral surface of the sleeve corresponding to each of the magnets constituting the rotor magnet group.

Each magnet constituting the rotor magnet group and the sleeve magnet group of the present invention is characterized by being composed of a ratio of n + 1: n.

The magnets constituting the rotor magnet group and the sleeve magnet group of the present invention are characterized by being composed of a ratio of n: n + 1.

The rotor magnet group and the sleeve magnet group of the present invention are characterized in that magnetic poles are arranged to have a repulsive force with each other.

The magnets constituting the rotor magnet group and the sleeve magnet group of the present invention are characterized in that they are permanent magnets.

The upper surface of the rotor of the present invention is characterized in that the polygon mirror is pressed by the cover is seated.

The magnetic bearing according to the present invention includes a rotating member including a shaft; A fixing member rotatably supporting the shaft; A rotating member side magnet group having at least two magnets having a ring shape spaced apart on the circumference of the shaft; And a fixing member side magnet group fixedly mounted to the fixing member adjacent to the circumference of the shaft, the fixing member side magnet group having at least two magnets having a ring shape that is alternately arranged with the at least two magnets of the rotating member side magnet group. It is characterized by what has been done.

Each magnet constituting the rotating member side magnet group and the fixing member side magnet group of the present invention is characterized by being composed of a ratio of n + 1: n.

Each magnet constituting the rotating member side magnet group and the fixing member side magnet group of the present invention is characterized by being composed of a ratio of n: n + 1.

The rotating member side magnet group and the fixing member side magnet group of the present invention are characterized in that magnetic poles are arranged to have a repulsive force with each other.

Magnetic bearings, characterized in that the plurality of magnets constituting the rotating member side magnet group and the fixing member side magnet group of the present invention is a permanent magnet

Hereinafter, a preferred embodiment of a magnetic bearing and a motor using such a magnetic bearing according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a cross-sectional view showing a core type motor according to the present invention, and FIG. 3 is a cross-sectional view of a motor showing another embodiment of FIG. 2. As shown, the motor according to the present invention has a circuit on one side of a lower surface thereof. The substrate 110 is fixedly installed, and the outer surface includes a sleeve 100 on which a stator 120 including a core 121 and a coil 122 wound around the core 121 is fixed.

A rotor 200 is positioned above the sleeve 100, and a boss is formed on the upper surface of the rotor 200 so that a polygon mirror 300 is seated thereon. ) To support the pressure, the cover (400) is coupled.

At this time, the polygon mirror 300 is firmly coupled to the boss and is prevented from being separated by the rotation moment during the rotation of the rotor 200.

Meanwhile, the magnet 220 is fixedly installed on the lower inner surface of the rotor 200 via the yoke 230 so as to generate a rotating electromagnetic force together with the above-described stator 120, and at the center lower surface of the sleeve 100. The shaft 500 is integrally provided to penetrate the center plane.

At this time, when the rotor 200 is rotated about the sleeve 100 to ensure the load bearing capacity, the rotor magnet group is installed on the rotor 200 side, and the rotor magnet group is opposed to A sleeve magnet group is provided on the inner circumferential surface side of the sleeve 100.

That is, the rotor 200 is to form an air film by the magnetic force acting between the rotor magnet group and the sleeve magnet group is to rise and rotate through it is given a load-bearing capacity.

Looking at the installation state of these magnets, a rotor magnet group consisting of a plurality of magnets are formed on the outer circumferential surface of the shaft 500 integrally provided on the lower center surface of the rotor 200, the rotor magnet group is a rotor as shown in the drawings The first and second magnets 610, 620, and 630 are installed at upper, middle, and lower positions of the outer circumferential surface.

In addition, a sleeve magnet group is formed on an inner circumferential surface of the sleeve 100, and the sleeve magnet group includes fourth, fifth magnets 640, 650 arranged between the first, second, and third magnets 610, 620, 630 of the rotor magnet group. It is composed.

That is, as shown in FIGS. 2 to 5, three magnets 610, 620, and 630 having a ring shape are formed on the rotor 200 at a predetermined interval, and between the three magnets 610, 620, and 630 on the sleeve 100 side. Two ring-shaped magnets 640 and 650 are configured to correspond to the space of the magnet.

This formula can be expressed as 'rotor side: sleeve = n + 1: n', and on the contrary, the magnet on the sleeve side has one more number than the magnet provided on the rotor side. : Sleeve = n: n + 1 '.

As described above, the reason for configuring the number of magnets on the rotor 200 side and the number of magnets provided on the sleeve 100 side differently may induce optimal efficiency in consideration of the total height of the magnetic bearing and the floating magnetic force. Because

On the other hand, the magnet on the rotor 200 side and the magnet on the sleeve 100 side are preferably adjusted according to the characteristics and capacity of the motor.

In addition, the rotor magnet group and the sleeve magnet group is a magnetic pole is formed to have a repulsive force to each other.

At this time, the magnetization direction of the magnets 600 described above is configured to magnetize the magnetic poles in the left and right directions, that is, the inner and outer directions, as shown in FIG. 2, and the present invention is not limited thereto. The magnetic pole may be configured to magnetize in the downward direction.

That is, if the structure having a repulsive force can be formed between the rotor magnet group and the sleeve magnet group, the shape or magnetic pole arrangement of the magnet may be variously modified.

On the other hand, the gap between the magnets vary depending on the material and the magnetic flux density value of the magnet from 0 to twice the length of the magnet axis direction, the gap can be adjusted using a spacer of the nonmagnetic material.

According to the present invention having such a configuration, the rotor 200 rotates at high speed through a rotating electromagnetic force between the magnet 220 and the stator 120, and at the same time, the rotor 200 is provided on the outer circumferential surface of the plurality of magnets 600, that is, the shaft 500. The magnetic force between the 1, 2, 3 magnets (610, 620, 630) and the fourth and fifth magnets (640, 650) formed on the inner circumferential surface of the sleeve 100, that is, through the resilience between each other while giving a load bearing capacity is given a stable rotation .

Therefore, it is possible to prevent the contact between the rotor 200 and the sleeve 100 that may occur when rotating through the air film of the conventional herringbone group.

On the other hand, Figures 4 to 5 is a diagram showing a coreless type of motor according to the present invention, showing a flat motor with a slim size (slim).

As shown in the figure, the flat motor includes a thin circuit board 110 printed with a circuit pattern, and a tubular sleeve 100 is coupled to the center of the circuit board 110.

On the other hand, as shown in the figure is provided with a stator 120 made of a bonded coil 122 is provided on the upper side of the circuit board 110, the lower outer surface of the sleeve 100 by a winding machine does not require a core. do.

A rotor 200 is positioned above the sleeve 100, and a boss is formed on the upper surface of the rotor 200 so that a polygon mirror 300 is seated thereon.

On the other hand, the magnet 220 to the yoke 230 to generate a rotating electromagnetic force with the above-described stator 120 in a direction facing the upper surface of the lower surface of the rotor 200, that is, the upper surface of the circuit board 110 as seen in the figure. It is fixedly installed through).

Such, the center surface of the rotor 200 is provided integrally coupled to the shaft 500 provided through the center surface of the sleeve (100).

At this time, the rotor 200 is to ensure a stable driving characteristics by floating by the magnetic force when the rotor 200 is rotated about the sleeve 100, and the rotor magnet group is largely installed on the rotor 200 side, and And a sleeve magnet group installed on an inner surface of the sleeve 100 opposite to the rotor magnet group.

Looking at the installation state of the rotor magnet group and the sleeve magnet group, the rotor magnet group consisting of a plurality of magnets is formed on the outer peripheral surface of the shaft 500 integrally provided on the lower center surface of the rotor 200, this rotor As shown in the drawing, the magnet group includes first, second, and third magnets 610, 620, and 630 installed at upper, middle, and lower positions of the outer circumferential surface of the rotor 200.

In addition, a sleeve magnet group is formed on an inner circumferential surface of the sleeve 100, and the sleeve magnet group includes fourth, fifth magnets 640, 650 arranged between the first, second, and third magnets 610, 620, 630 of the rotor magnet group. It is composed.

In particular, the rotor magnet group and the sleeve magnet group is formed to have a repulsive force between each other, the magnetization direction of each magnet group is shown in Figure 4 as shown in the left, right direction, that is, the inner and outer direction The stimulus is configured to magnetize.

In addition, as shown in FIG. 5, the magnetic poles may be magnetized in the up and down directions as viewed in the drawing.

That is, if the structure having a repulsive force can be formed between the rotor magnet group and the sleeve magnet group, the shape or magnetic pole arrangement of the magnet may be variously modified.

According to the present invention having such a configuration, the rotor 200 rotates at high speed through a rotating electromagnetic force between the magnet 220 and the stator 120, and at the same time, the rotor 200 is provided on the outer circumferential surface of the plurality of magnets 600, that is, the shaft 500. The first, second, and third magnets 610, 620, 630 and the fourth and fifth magnets 640 and 650 formed on the inner circumferential surface of the sleeve 100 are injured through mutual repulsive force.

Therefore, since the contact between the rotor 200 and the sleeve 100 can be prevented in advance, it is possible to ensure stable driving characteristics of the motor.

In addition, since the polygon mirror 300 which rotates together with the rotor 200 is fixedly installed to the boss of the rotor 200, it is reliably prevented from being separated by the rotation moment.

Referring to the operation of the motor according to the invention made as described above are as follows.

6 to 7 are schematic diagrams showing the operation principle of the motor according to the present invention. FIG. 6 is a flux line when it is assumed that the shaft of the motor is moved upwards by a small distance, and FIG. 7 shows that the shaft of the motor is magnetic. It shows the flux line with stable driving due to the normal operation of the bearing.

That is, as shown in FIG. 6, when a centrifugal force occurs during vibration or high speed rotation, an asymmetric unstable state is achieved in the sleeve.

As described above, in the asymmetrical state, a force to maintain the symmetrical structure is generated by the repulsive force between the rotor magnet group and the sleeve magnet group, so that the shaft can be maintained in a stable position as shown in FIG. 7.

Meanwhile, FIG. 8 illustrates a direction of magnetic force according to an air gap between the magnets constituting the rotor magnet group and the sleeve magnet group, and as shown in FIG. 8, each of the rotor magnet group and the sleeve magnet group as shown in FIG. In the case of forming a gap between the magnets, that is, a square air gap shown by a dotted line in the drawing, the direction of the magnetic force is about 45 degrees.

FIG. 11 is a graph shown based on the motor shown in FIG. 3 and illustrates a magnetic flux density in an air gap (air gap) between a rotor magnet group provided in the rotor and a sleeve magnet group provided in the sleeve. SIMULATION) shows the result.

That is, FIG. 11 illustrates an air gap between three magnets 610, 620, and 630 provided in the rotor 100, and two magnets 640 and 650 provided in the sleeve 100. As a result of showing the magnetic flux density at the air gap, the magnetic flux density at 4 points of symmetry of each magnet has a minimum value of about 0.15T, and the magnetic flux density at the center of each magnet has a maximum value of about 0.45T. have.

Therefore, the magnitude of the force acting between the magnets is 0.45T-0.15T = 0.3T because the magnitude of the force acting on the max-min value is 45 °, which is the intermediate direction between the transverse direction and the axial direction as shown in FIG. Since it is directed toward, it is possible to have an ideal vector direction and a sufficient value to stably induce the floating of the shaft.

Therefore, the floating force pushing each other in the vertical direction and the horizontal direction is generated by the repulsive force generated between the magnets, so that it is possible to maintain the always floating state from the initial assembly to the high speed rotation.

Therefore, it is possible to prevent the occurrence of mechanical loss and noise due to interference or friction between parts, and in particular, to prevent the contact between the parts in advance to ensure a stable driving characteristics of the motor.

Meanwhile, FIGS. 10 to 11 are graphs showing the operating characteristics of the motor according to the present invention. FIG. 10 shows the stiffness in the axial direction, and FIG. 11 shows the stiffness in the radial direction.

In the magnetic bearing according to the present invention, the air gap may be preferably about 0.2 mm in both the axial direction and the radial direction. As shown in FIG. 10, the Axial Magnetic force acting in the air gap when the air gap is 0.2 [mm] Since = 1.45 [N], the stiffness coefficient = force / distance = 7,250 [N / m], and as shown in FIG. 11, the radial magnetic force acting in the air gap when air gap = 0.2 [mm] is 1.75 [N]. ], The stiffness coefficient = force / distance = 8,750 [N / m].

Therefore, since the magnetic force generated in the air gap is 1 [N] or more, it has a sufficient value for injuries, and since the axial and radial stiffness coefficients have almost the same values, it has a satisfactory performance as an operating characteristic as a magnetic bearing.

As described above, according to the motor according to the present invention, the rotor is rotated while being given the load bearing capacity by the repulsive force of a plurality of magnets provided between the shaft and the sleeve, thereby ensuring stable driving characteristics of the motor. Since the contact between the two can be prevented in advance, the vibration and noise can be largely suppressed. As a result, the reliability of the product can be greatly improved.

Claims (17)

A circuit board; A sleeve fixedly installed at a center surface of the circuit board and having a stator including a core and a coil at an outer surface thereof; A rotor having a magnet for generating a rotating electromagnetic force together with the stator, fixedly installed through a yoke, and having a shaft integrally formed at a center surface thereof through a center surface of the sleeve; A rotor magnet group provided in plural at predetermined intervals on an outer circumferential surface of the shaft of the rotor; A sleeve magnet group provided on an inner circumferential surface of a sleeve corresponding to each magnet constituting the rotor magnet group; Motor comprising a. The motor of claim 1, wherein each of the magnets constituting the rotor magnet group and the sleeve magnet group has a ratio of n + 1: n. The motor according to claim 1, wherein each magnet constituting the rotor magnet group and the sleeve magnet group has a ratio of n: n + 1. The motor according to claim 1, wherein the rotor magnet group and the sleeve magnet group are arranged with magnetic poles to have a repulsive force therebetween. The motor of claim 1, wherein the plurality of magnets constituting the rotor magnet group and the sleeve magnet group are permanent magnets. The motor of claim 1, wherein a polygon mirror that is pressed and supported by a cover is mounted on an upper surface of the rotor. A circuit board; A sleeve fixed to a center surface of the circuit board and provided with a stator including a coil on an outer surface thereof; A rotor having a magnet for generating a rotating electromagnetic force together with the stator, fixedly installed through a yoke, and having a shaft integrally formed at a center surface thereof through a center surface of the sleeve; A rotor magnet group provided in plural at predetermined intervals on an outer circumferential surface of the shaft of the rotor; A sleeve magnet group provided on an inner circumferential surface of a sleeve corresponding to each magnet constituting the rotor magnet group; Motor comprising a. 8. The motor of claim 7, wherein each of the magnets constituting the rotor magnet group and the sleeve magnet group has a ratio of n + 1: n. 8. The motor of claim 7, wherein each of the magnets constituting the rotor magnet group and the sleeve magnet group has a ratio of n: n + 1. 8. The motor of claim 7, wherein the rotor magnet group and the sleeve magnet group have magnetic poles arranged to have a repulsive force therebetween. 8. The motor of claim 7, wherein the plurality of magnets constituting the rotor magnet group and the sleeve magnet group are permanent magnets. 8. The motor of claim 7, wherein a polygon mirror that is press-supported by a cover is mounted on an upper surface of the rotor. A rotating member including a shaft; A fixing member rotatably supporting the shaft; A rotating member side magnet group having at least two magnets having a ring shape spaced apart on the circumference of the shaft; A fixing member side magnet group fixedly mounted to the fixing member adjacent to the circumference of the shaft, the fixing member side magnet group having at least two magnets having a ring shape alternately arranged with the at least two magnets of the rotating member side magnet group; Magnetic bearing comprising a. 14. The magnetic bearing according to claim 13, wherein each magnet constituting the rotating member side magnet group and the fixing member side magnet group is composed of a ratio of n + 1: n. 14. The magnetic bearing according to claim 13, wherein each magnet constituting the rotating member side magnet group and the fixing member side magnet group is composed of a ratio of n: n + 1. The magnetic bearing according to claim 13, wherein the rotating member side magnet group and the fixing member side magnet group are provided with magnetic poles so as to have a repulsive force therebetween. 14. The magnetic bearing according to claim 13, wherein the plurality of magnets constituting the rotating member side magnet group and the fixing member side magnet group are permanent magnets.