JP3215080B2 - Method of manufacturing electromagnetically controlled bearing and brushless DC motor using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electromagnetic bearing and a brushless DC motor using the same. More specifically, an electromagnetic force generating means using an electromagnet is fixedly installed on the outer peripheral surface of the bearing with a thermosetting resin. As a result, the distance between the shaft and the bearing is decentered in a desired direction at a certain speed or more, so that when the shaft rotates at high speed, the oil whirl phenomenon is reduced, and the dynamic characteristics of low vibration and low noise are improved. The present invention relates to a method for manufacturing a control bearing and a brushless DC motor using the same.

[0002]

2. Description of the Related Art Generally, a fluid dynamic pressure bearing used in a spindle motor is filled with a dynamic pressure generating oil between a shaft and a bearing rotatably supporting the shaft. FIG. 1 is a cross-sectional view of a conventional spindle motor, in which a bearing 1a is fitted to a center of an upper portion of a base 1 and assembled.
The shaft 2 is provided inside the bearing 1a in a rotatable state. A stator 1b constituting a stator is provided at an upper outer peripheral edge of the base 1, and a cap-shaped rotor 3 is provided at an upper end of the shaft 2. The rotor 3 is provided with a magnet 3a surrounding the stator 1b on the inner peripheral edge. When power is applied to the coil 1c wound on the stator 1b, a magnetic force is generated by the magnet 3a, and the rotor 3 is rotated about the shaft 2 as a center. Rotate.

In the conventional spindle motor configured as described above, when the shaft 2 rotates at high speed, the bearing 1
A pressure is generated by the oil filled between the first and second a. Therefore, while the shaft 2 is rotatably supported in the radial direction of rotation, and while the shaft 2 is rotating, the disc placed on the rotor 3 rotates together to reproduce the information of the disc.

However, in the case of the fluid dynamic pressure bearing, there is a disadvantage that an unstable phenomenon called oil whirl occurs at a low speed. The oil whirl phenomenon starts while the bearing eccentricity between the bearing 1a and the shaft 2 gradually decreases at a certain speed or more. This is the Sommerfeld number as speed increases
This is because the eccentricity is gradually reduced due to the decrease in. Such a phenomenon occurs because the oil rotating along the shaft 2 has a constant velocity distribution, and generally occurs mainly in a perfect circular fluid dynamic pressure bearing having no dynamic pressure generating groove on the outer peripheral surface of the shaft 2. Accordingly, there are disadvantages such as a decrease in dynamic characteristics of low vibration and low noise at high speed.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned various problems, and an object of the present invention is to provide a bearing in which a distance between a shaft and a bearing is eccentric in a desired direction at a certain speed or more. By providing an electromagnetic force generating means using an electromagnet on the outer peripheral surface of the motor, a pressure generation rate of oil is increased, and a high-speed dynamic characteristic is improved, and a brushless DC motor using the same is provided. It is in.

[0006]

To achieve the above object, according to an aspect of manufacturing method of the electromagnetic control bearing of the present invention, Sha
To force eccentrically shifted in the desired direction, in the manufacturing method of the electromagnetic control bearing having one or more electromagnetic force generating means to exert an attractive force on the shaft, it has an outer diameter and the same inner diameter of the bearing of interest Preparing a jig having an entrance on at least one side, arranging the electromagnetic force generating means coaxially through the jig inside the jig, and providing a jig inside each electromagnetic force generating means. Installing the bearing part through the entrance, charging the resin between the jig and the bearing part through the entrance of the jig, and curing the resin between the jig and the bearing part to form the electromagnetic force generating means and the bearing part. Mutually fixing; and machining the inner diameter of the bearing part to maintain a fluid flow space between the bearing part and the shaft. Comprising a step of completing the electromagnetic control bearing mutually coupled electromagnetic force generating means and the bearing portion is separated from the jig.

[0007]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

The electromagnetic control bearing 11 is configured as follows. An inner wall that surrounds and supports the shaft 12, maintains an inner wall surrounding the shaft 12, and an outer wall that surrounds the inner wall and fixes the bearing 11, and connects the inner wall and the outer wall so that the shaft can rotate inside. The upper and lower walls are located between the inner wall and the outer wall, and the shaft 12 is used to generate a constant dynamic pressure in the fluid between the shaft 12 and the inner wall.
One or more electromagnetic force generating means 19 for applying an attractive force in the radial direction of rotation, and a thermosetting resin 31 filled between the inner wall and the outer wall so that the electromagnetic force generating means 19 is fixed. It is composed of Here, the inner wall is formed of a bearing 11a having an inner diameter and having a fluid flow space between the inner wall and the shaft, and the outer wall is reinforced to prevent deformation when the thermosetting resin 31 expands in a hardening process. jig 30 a is used. Also, a polycoat is preferably used as the thermosetting resin.

The electromagnetic force generating means 19 suppresses the oil whirl phenomenon that occurs when the shaft 12 rotates at a certain speed or more. The eccentricity increases by pulling the shaft 12 in a desired direction. In the electromagnetic force generating means 19, a large number of electromagnets 20 for generating an electromagnetic force are radially provided on the outer peripheral surface of the bearing portion 11a. Each of the electromagnets 20 is formed in a rectangular shape, and each of the electromagnets 20 is provided with a pair of electromagnetic force generating portions 21 that are divided on both sides in front of the shaft 12. A coil 22 is wound around each electromagnetic force generating unit 21, and these coils 22
Power is applied at a rotation speed of 2.

When the amount of eccentricity decreases in the process of rotating the shaft 12 at high speed, power is selectively applied to each coil 22, and at the same time, an electromagnetic force is generated by the electromagnetic force generation unit 21 to move the shaft 12 to the electromagnet 20. Pull to the side. Further, a sensing coil 23 for generating an induced current is provided for each electromagnetic force generating unit 21. The sensing coil 23 generates an induced current according to a difference in distance between the shaft 12 and the electromagnet 20, and power is applied to the coil 22 according to a change amount of the induced current.
Such an induced current is amplified by the amplifier 25 and then input to the controller 24. The controller 24 applies power to each of the electromagnets 20 based on a distance difference between the electromagnet 20 and the shaft 12. More specifically, power is applied to the coil 22 of the electromagnet 20 in response to a control signal sent from the controller 24, an electromagnetic force is generated by the electromagnetic force generation unit 21, and the shaft 12 is pulled in a desired direction. For example, the shaft 12
In the process of rotating, it can be pulled in any direction and rotated in an eccentric state. Then, the compressibility of the oil 13 can be increased by causing the shaft 12 to be continuously decentered toward the respective electromagnets 20, that is, to idle in a scroll state inside the bearing 11.

The motor provided with the electromagnetic control bearing of the present invention is configured as follows.

Bearing part 1 constituting bearing 11
Strengthening jig 30 a of 1a and the electromagnet 20 is furnished is assembled is inserted into the base 10 constituting the motor. As a method of assembling the reinforcing jig 30 a inside the base 10,
How fitting, after inserting the reinforcing jig 30 a in the base 10, and a method of assembling concluded simultaneously the outer peripheral surface with screws. A stator 14 around which a coil 15 is wound is provided on the outer periphery of the base 10. Then, the shaft 12 is rotatably inserted into the bearing 11,
Oil 13 that generates dynamic pressure is filled between the shaft 12 and the bearing.

A hub 16 is coupled to the upper end of the shaft 12 in a fitting manner, and a rotor 17 is provided on the outer periphery so as to be rotated together therewith. The rotor 17 is located coaxially with the stator 17 and has a cylindrical wall surrounding the stator, a magnet 18 attached to the inside of the cylindrical wall and having a gap between itself and the stator 14, and a rotatable shaft for rotating the magnet. 12 supported by a hub 16. Therefore, when power is applied to the coil 15, a magnetic force is generated by the magnet 18, and the rotor 17 rotates at high speed together with the shaft 12.

According to the present invention thus constructed, an electromagnetic force generating means 19 for forcibly eccentrically moving the shaft 12 in a desired direction is provided inside the bearing 11. The electromagnetic force generating means 19 prevents the dynamic pressure of the oil 13 from decreasing due to the decrease in the amount of eccentricity during the rotation of the shaft 12 at high speed, and suppresses the oil whirl phenomenon. Such an electromagnetic force generating means 19 is composed of a large number of electromagnets 20 provided radially inside the bearing 11, and each of these electromagnets 2
0 is provided with a pair of electromagnetic force generating parts 21 in front of the shaft 12. When a power is applied to the coil 22 wound around the electromagnetic force generating unit 21, an electromagnetic force is generated. Each electromagnetic force generating unit 21 is provided with a sensing coil 23 for generating an induced current. The sensing coil 23 generates an induced current when a distance difference between the shaft 12 and each electromagnet 20 occurs. The induced current is sent to a controller 24 via an amplifier 25, and the electromagnetic force is adjusted according to the amount of the induced current.

The control process of the shaft 12 will be described as follows. When the shaft 12 rotates at high speed, a phenomenon occurs in which the amount of eccentricity decreases. At this time, many electromagnets 20
An induced current is generated by a distance difference from the shaft 12 or a rotation speed in the sensing coil 23 provided in the controller 25. The induced current is amplified by an amplifier 25 and output to a controller 24. Then, the controller 24 sends a signal to the microcomputer for applying power to the coil 22 where the distance difference occurs. Therefore, power is applied to the coil 22 and the electromagnetic force generating unit 2
In step 1, an electromagnetic force is generated to pull the shaft 12 in a desired direction. Accordingly, the shaft 12 is forcibly eccentric with respect to the bearing 11 to increase the dynamic pressure of the oil 13 and reduce the oil whirl phenomenon, thereby improving the dynamic characteristics at the time of high-speed rotation. In addition, the pressure of the oil 13 increases as the shaft 12 is continuously eccentric by the power supply applied to each electromagnet 20 and rotates in a scroll state.

The manufacturing method of the fluid dynamic bearing device according to the present invention is as follows.

FIG. 3 is an exploded perspective view of the bearing of the present invention, FIGS. 4 and 5 are cross-sectional views showing a manufacturing process of the bearing of the present invention, and FIG. 6 is a flowchart showing a manufacturing process of the bearing of the present invention. is there. A step (100) of preparing a jig ( not shown ) having the same inner diameter as the outer diameter of the intended bearing 11 and having an inlet on at least one side, and having an inlet on at least one side inside the jig ( not shown ). Disposing at least one or more bearing reinforcing jigs 30a having the same outer diameter as the outer diameter of the bearings in the jig ( not shown) (11).
0), and each electromagnetic force generating means 1 is provided inside the reinforcing jig 30a.
(9) coaxially disposing 9 through a jig entrance ( not shown);
Installing the bearing portion 11a through the jig entrance (130).

Here, the jig ( not shown) is formed in the form of an octagonal pipe, and electromagnetic force generating means 19 is disposed on each of the corresponding inner sides. In this process, the electromagnetic force generating means 19 face each other. The tip surfaces of the electromagnetic force generating portions 21 of the electromagnetic force generating means 19 are formed in an arc shape so as to be in contact with the outer peripheral surface of the bearing portion 11a.

Next, a step (140) of charging a resin between the reinforcing jig 30a and the bearing portion 11a through a jig entrance ( not shown ), the reinforcing jig 30a and the bearing portion 1 are performed.
A step 150 of curing the resin between the shafts 1a to fix the reinforcing jig 30a, the electromagnetic force generating means 19 and the bearing 11a to each other (150), and processing an inner diameter of the bearing 11a to form a fluid flow space between the bearing 12a and the shaft 12. Is maintained (160), and the bearing portion 11a having the reinforcing jig 30a and the electromagnetic force generating means 19 is connected to a jig ( not shown).
And a step (170) to complete the electromagnetic control bearing separate from the grayed.

FIG. 7 is a sectional view of a bearing device according to another embodiment of the present invention, in which a jig 32 is formed in a cylindrical shape. When the jig 32 is formed in a cylindrical shape, when the jig 32 is connected to the inner peripheral surface of the base 10 constituting the motor, the assemblability is improved because the base 10 is cylindrical. In a bearing device according to another embodiment of the present invention, a large number of guide grooves 33 are formed on the inner peripheral surface of a cylindrical jig 32. These guide grooves 33 are formed in a form corresponding to one side surface of the electromagnet 20. Therefore, when the electromagnet 20 is coupled to these guide grooves 33, it is fixed so as not to move, and then each electromagnet 20 is fixed.
After inserting the bearing portion 11a between the bearing portions 11a
A thermosetting resin 31 is filled between 1a and the jig 32. When the thermosetting resin 31 cures, the bearing portion 11a and the electromagnets 20 are fixed in the jig 32 in a state where they do not move. Then, the inner peripheral surface of the bearing portion 11a is precisely machined and the shaft 12 is rotatably inserted. A bearing device according to another embodiment of the invention is completed.

[0021]

As described above, according to the present invention,
After arranging a large number of electromagnets and bearings inside a jig coupled to the base, and fixing them with a thermosetting resin, the bearing is completed. After such a bearing is fixedly installed inside the base, if the shaft is rotatably supported on the inner peripheral surface of the bearing, dynamic pressure is generated during the rotation of the shaft and the shaft can be rotated. To support. When the amount of eccentricity decreases during the rotation of the shaft, power is applied to the coil of each electromagnetic force generating means, and the shaft is pulled in a desired direction to increase the amount of eccentricity. Therefore, the dynamic pressure increases, resulting in low noise at high speed rotation,
The dynamic characteristics of low vibration are improved, and there are effects that the bearing can be simply configured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a conventional motor bearing device.

FIG. 2 is a sectional view of a motor according to the present invention.

FIG. 3 is an exploded perspective view of the electromagnetic control bearing of the present invention.

FIG. 4 is a cross-sectional view illustrating a manufacturing process of the electromagnetically controlled bearing of the present invention.

FIG. 5 is a sectional view showing a manufacturing process of the electromagnetically controlled bearing of the present invention.

FIG. 6 is a flowchart showing a manufacturing process of the electromagnetically controlled bearing of the present invention.

FIG. 7 is a cross-sectional view of an electromagnetic control bearing according to another embodiment of the present invention.

[Explanation of symbols]

11 electromagnetic control bearing 11a bearing portion 12 the shaft 13 Oil 14 stator 15 coils 16 hub 17 rotor 18 magnet 19 electromagnetic force generating means 20 electromagnet 21 electromagnetic force generating portion 22 the coil 23 sensing coils 24 controller 25 amplifies device 3 0a reinforced jig 31 heat Curable resin

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16C 32/00-32/06 F16C 17/02 H02K 7/09 H02K 21/22 H02K 29/00

Claims (12)

(57) [Claims] The shaft is forcibly eccentric in a desired direction.
Because, in the manufacturing method of the electromagnetic control bearing having one or more electromagnetic force generating means to exert an attractive force on the shaft, 1) has an outer diameter and the same inner diameter of the bearing of interest, an inlet on at least one side 2) arranging the electromagnetic force generating means coaxially inside the jig through an entrance of the jig, and 3) through a jig entrance inside each of the electromagnetic force generating means. Installing a bearing part; 4) charging resin between the jig and the bearing part through an inlet of the jig; and 5) curing resin between the jig and the bearing part to generate electromagnetic force generating means and a bearing. 6) machining the inner diameter of the bearing portion to maintain a fluid flow space between the bearing portion and the shaft; And b) separating the mutually coupled electromagnetic force generating means and the bearing portion from the jig to complete an electromagnetic control bearing. 2. The manufacturing of the electromagnetically controlled bearing according to claim 1, wherein a bearing portion having an uneven surface on an outer peripheral surface is installed inside the electromagnetic force generating means in order to strengthen the bonding force of the resin. Method. 3. A brushless DC motor, comprising: a stator on which a coil is wound; a base for fixing the stator to an upper part; a shaft which is a rotation axis of the motor; A rotor having a cylinder-shaped wall surrounding the magnet, a magnet attached to the inside of the cylinder-shaped wall, and having a gap between the stator and the stator, and a hub rotatably supporting the magnet on the shaft; Maintaining a fluid flow space such that the shaft is rotatable therein and surrounding and supporting the shaft, an outer wall surrounding the inner wall and capable of securing a bearing system; and In order to generate a constant dynamic pressure in the fluid between the shaft and the inner wall, located between the upper and lower end walls to be connected and the inner and outer walls. One or more electromagnetic force generating means for applying an attractive force in the radial direction of rotation of the shaft; and a thermosetting resin filled between the inner wall and the outer wall so that the electromagnetic force generating means is fixed. A bearing system installed through the stator above the base so that the shaft rotates coaxially with the stator; and when the dynamic pressure decreases during the high-speed rotation of the shaft. A controller for supplying current to the electromagnetic force generating means and controlling the shaft to be pulled. 4. The brushless D according to claim 3 , wherein said electromagnetic force generating means comprises an electromagnetic force generating unit and a coil winding said electromagnetic force generating unit.
C motor. 5. The electromagnetic force generating means is wound around the electromagnetic force generating unit and the electromagnetic force generating unit, and is adapted to induce when a size of a fluid flow space formed between the shaft and the inner wall of the bearing changes. A sensing coil for generating a current;
An amplifier connected to the sensing coil for amplifying the induced current and controlling the controller based on the amplified amount of the induced current; and an amplifier wound around the electromagnetic force generator and responsive to a control signal of the controller. 4. A brushless DC motor according to claim 3, further comprising a coil for generating an electromagnetic force to pull the shaft to one side. 6. The inner wall of the bearing is formed of a bearing having an inner diameter and a fluid flow space between the bearing and the shaft, and the outer wall is formed by expansion when the thermosetting resin is cured. 4. A brushless DC according to claim 3 , wherein the brushless DC is constituted by a reinforcing jig for suppressing deformation.
motor. 7. The brushless DC motor according to claim 3 , wherein two or more of said electromagnetic force generating means are provided at a constant angle in a radial direction about said shaft. 8. The brushless D according to claim 7 , wherein said electromagnetic force generating means comprises an electromagnetic force generating section and a coil winding said electromagnetic force generating section.
C motor. 9. The electromagnetic force generating means is wound around the electromagnetic force generating portion and the electromagnetic force generating portion, and is induced when a size of a fluid flow space formed between the shaft and the inner wall of the bearing changes. A sensing coil for generating a current;
An amplifier connected to the sensing coil for amplifying the induced current and controlling the controller based on the amplified amount of the induced current; and an amplifier wound around the electromagnetic force generator and responsive to a control signal of the controller. The brushless DC motor according to claim 7, further comprising a coil that generates electromagnetic force to pull the shaft to one side. 10. The apparatus according to claim 1, wherein two or more electromagnetic force generating means are provided in the axial direction of the shaft.
3. The brushless DC motor according to 3 . 11. The brushless DC motor according to claim 10 , wherein said electromagnetic force generating means includes an electromagnetic force generating unit and a coil winding said electromagnetic force generating unit. 12. The electromagnetic force generating means is wound around the electromagnetic force generating unit and the electromagnetic force generating unit, and is adapted to induce when a size of a fluid flow space formed between the shaft and the inner wall of the bearing changes. A sensing coil for generating a current, connected to the sensing coil to amplify the induced current,
An amplifier configured to be controlled by the controller by the amplified induced current amount, wound around the electromagnetic force generation unit, and generates an electromagnetic force according to a control signal of the controller to move the shaft to one side. The brushless DC motor according to claim 10, comprising a coil to be pulled.