JP2003299302A - Spindle motor with axial vibration preventing mechanism of rotor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an axial vibration preventing mechanism capable of actuating a magnetic pre-load for energizing a rotating shaft in an extension direction of material with a simple structure. <P>SOLUTION: In this rotor R1, a metal shaft 103 is inserted in the center of a resin turn table 101. In the shaft 103, a bent part is formed and pressed in the peripheral edge of a back yoke 105 of a clamp magnet 104 for clamping a record information disk which is disposed at the turn table 101 so as to face a motor side at the timing of assembling the rotor R into a stator S. The clamp magnet 104 is disposed at a gap surrounded by an annular groove 101a formed around the back yoke 105 and the shaft 103 of the turn table 101. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor for rotating an information recording disk, and more particularly to an axial vibration preventing mechanism and a brushless motor having the axial vibration preventing mechanism.

[0002]

2. Description of the Related Art In recent years, information recording disks (hereinafter referred to as disks) such as CD-ROMs and DVDs have come to record a large amount of information at a high density. High-speed rotation is required. In such a motor, a bearing housing is fixed to a central portion of a stator base forming a stator,
Inside the cylinder of this bearing housing, a radial bearing and a thrust bearing, which are rotatably supported by a shaft inserted in the central portion of a rotor yoke forming a rotor, are arranged, and a stator core is provided on the outer peripheral portion of the cylinder of this bearing housing. It is stuck.

In this stator core, a drive coil is wound around a plurality of arms protruding from the center of the stator core in the radial direction to form armature magnetic poles. An annular magnet is fixed to the cylindrical inner peripheral surface of the rotor yoke, and the annular magnet has magnetic poles divided in the circumferential direction, and the magnetic poles are arranged to face the armature magnetic poles of the stator.

Normally, in a disc, the in-plane weight distribution with respect to the shaft is unbalanced. Therefore, such a disc is mounted on the spindle motor, and the motor mounted with this disc is rotationally driven to read the recorded information, but as the spindle motor rotates at a high speed, the recording is performed in the direction along the shaft. The dynamic centrifugal force of the disc causes a component to induce longitudinal vibration. As a result, there is a problem that a disc information reading error occurs and the vibration and noise of the drive device itself increase.

As a method of solving this problem, a method of canceling the component force by applying a strong and stable force equal to or more than the unbalance component component as a preload to the rotor during rotation of the motor is adopted. Then, by disposing the rotor at a position where the shaft direction center of the annular magnet is shifted to the output shaft side with respect to the shaft direction center of the stator core, there is a method for increasing the attraction force in the thrust direction to obtain the preload. .

Further, a method of obtaining the preload by fixing an annular magnet around the opening of the bearing housing made of a non-magnetic material such as brass and attracting the periphery of the shaft insertion base of the rotor yoke made of a magnetic material facing each other. There is also. Further, an annular magnet is fixed to the shaft insertion base portion inside the rotor yoke, the radial bearing portion facing the magnet is formed of an iron-based sintered metal material, and the radial bearing is attracted by the magnet, There is also a method to obtain the preload.

[0007]

However, the method of displacing the magnetic center in the previous period has a drawback that the leakage magnetic flux increases and strong magnetic noise is generated, which disturbs the apparatus itself. Further, the method of fixing the annular permanent magnet around the opening of the bearing housing made of a non-magnetic material is complicated because it requires a fixing member for the permanent magnet and a bonding work, and there is a drawback that the bonded permanent magnet falls off. It was Further, the method of forming the radial bearing on the side facing the rotor yoke from an iron-based sintered metal material and attracting with the permanent magnet on the rotor yoke side has a problem that usable bearing materials are limited. Further, the iron-based sintered metal has a drawback that a strong magnetic attractive force cannot be expected because it contains a large amount of non-metals.

In view of the above, the present invention solves the above-mentioned drawbacks and has a simple structure. However, a magnetic preload for surely urging the rotating portion in the direction of extension of the shaft is exerted to provide a highly reliable shaft. A directional vibration prevention mechanism is provided.

[0009]

In order to solve the above-mentioned problems, a spindle motor provided with an axial vibration preventing means for a rotor part in which a rotor yoke and a turntable are integrated as described in claim 1. In this case, the base end of the rotary shaft fixed to the rotor part is received by the stator base of the stator part, the magnetic generator or the magnetic attractor is arranged on the turntable, and the magnetic part or the magnetic attractor is opposed to the stator part side. It can be achieved by arranging a magnetic adsorbent or a magnetic generator.

The magnetic generator arranged on the turntable can achieve the object by arranging a disk chucking magnet as described in claim 2. Further, as described in claim 3, a back yoke is arranged on the turntable, the periphery of the back yoke is bent toward the stator portion side, and the magnetic attraction member or the magnetic generation member arranged on the stator portion side is arranged. The object can be achieved by a spindle motor provided with an axial vibration preventing mechanism for a rotating portion that is close to the body. Further, as described in claim 4, the object can be achieved by integrally forming the back yoke on the turntable.

Further, as described in claim 5, the problem can be achieved by interspersing the magnetic generators or magnetic adsorbents arranged on the turntable outside the rotary shaft. The scattered magnetic generators or magnetic attractants may be rod-shaped magnets magnetized in the axial direction according to the sixth aspect. The magnetic attraction body arranged on the turntable is made of a disk chucking iron plate according to claim 7, and the object can be achieved by attracting the iron plate to the magnetic field generation body arranged on the stator side. .

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the invention will be described with reference to the drawings.

FIG. 1 is a vertical sectional view of a motor showing a first embodiment of the present invention. The brushless motor of FIG.
In outline, the turntable 101 and the rotor yoke 1
02, a rotor portion R1 and a stator base 151.
And a stator core S, which includes a stator core 152. In the rotor portion R1, a turntable 101 made of synthetic resin is integrally formed with a cup-shaped rotor yoke 102 and a back yoke 105. Further, the rotor yoke 102 made of a magnetic material is formed in a cup shape, and the bottom portion thereof is attached to the bottom portion of the turntable 101 by insert molding or the like, and the drive magnet 106 is fixed to the inner peripheral side surface thereof.

In the back yoke 105, the outer tubular portion is long, and the inner tubular portion forms an annular groove shorter than the outer tubular portion. The bottom portion is the bottom portion of the annular groove 101a of the turntable 101. In addition, the outer cylinder is exposed from the turntable 101, and the inner cylinder is buried in the turntable. The metal shaft 103 is inserted into the central hole formed in the turntable 101. Further, the annular groove 101a formed on the turntable 101 and the back yoke 1
In the space surrounded by 05, the clamp magnet 10
4 is adhered and fixed to the back yoke 105 with an adhesive or the like.

On the other hand, in the stator portion S, a stator core 15 in which plate-shaped magnetic metal plates are punched and laminated by a press
A coil 153 is wound around 2. The central annular portion 152 a of the stator core 152 has a stator base 151.
Is press-fitted into the bearing housing 154 attached to the radial housing 1.
A part of 55 is press-fitted. And the thrust bearing 1
56 is press-fitted.

A suction plate 157 made of a magnetic metal plate is press-fitted at the end of the radial bearing 155 so as to face the outer cylindrical portion of the back yoke 105 formed integrally with the turntable 101. Further, as shown in FIG. 2, the bearing housing 154 may be formed to have a height that covers the vicinity of the upper end of the radial bearing 155, and the absorption plate 157 may be press-fitted to the end of the bearing housing 154.

FIG. 3 is an exploded perspective view showing an assembling procedure of the rotor portion R1 according to the embodiment shown in FIG. (1) First, the rotor yoke 102 and the back yoke 105
Is attached to a molding die, and the turntable 101 is formed by resin molding. A plurality of holes 102a are provided on the annular surface forming the bottom surface of the rotor yoke 102 for the purpose of improving the connection with the turntable 101, and the resin of the turntable 101 is provided on the cylindrical surface of the back yoke 105. A plurality of holes 105a are provided so as to flow in. (2) Next, the drive magnet 106 is fixed to the inner peripheral portion of the rotor yoke 102 with an adhesive or the like. (3) Next, the clamp magnet 104 is adhered and fixed to the back yoke 105 forming the bottom of the annular groove 101a of the turntable 101 with an adhesive or the like. (4) After that, attach the shaft 103 to the turntable 10
Press into the central hole of No. 1. The work procedures (2) and (3) may be replaced with each other.

Therefore, since the bent portion of the back yoke 105 of the clamp magnet 104 faces the suction plate 157 which is press-fitted into the radial bearing 155, the rotor yoke 102 is fixed to the shaft 10.
3 will always be biased in the axial direction. That is, since the shaft 103 is pressed against the thrust bearing 156, vibration in the axial direction is suppressed even when the rotor R rotates at high speed, and thus vertical vibration of the shaft 103 can be suppressed.

The back yoke 105 and the suction plate 157 are also provided.
Is a plate pressure such that the magnetic flux of the clamp magnet 104 is not saturated. Back yoke 105 bending part and suction plate 15
By adjusting the gap with respect to 7, it is possible to appropriately suppress the above-mentioned vertical vibration. The back yoke on which the magnet is mounted may be provided separately on the inner peripheral side and / or the outer peripheral side, or a plurality of holes may be provided in the circumferential direction.

FIG. 4 is a longitudinal sectional view showing a second embodiment, in which the clamp magnet 204 is used as a direct magnetic attraction force source instead of the back yoke 105 shown in FIG. . The same elements as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Then, the through hole 201a provided in the turntable 201 has the same structure as the turntable 201. A clamp magnet 204 for clamping the placed information recording disk is inserted. This clamp magnet 20
4 is fixed by abutting on a protrusion 201b provided on the turntable. The protrusions 201b are for preventing the clamp magnet 204 from coming off and for positioning during assembly.

FIG. 5 is a perspective view of the procedure for assembling the rotor portion R2 according to the second embodiment. (1) First, the rotor yoke 202 is attached to a molding die, and the turntable 201 is formed by resin molding. A plurality of holes 202a are provided on the annular surface forming the bottom surface of the rotor yoke 202 for the purpose of improving the connection with the turntable 201. (2) Next, the drive magnet 106 is fixed to the inner peripheral portion of the rotor yoke 202 with an adhesive or the like. (3) Next, the clamp magnet 204 is inserted into the through hole 201a formed in the turntable 201, and adhered and fixed with an adhesive or the like. (4) After that, attach the shaft 203 to the turntable 20.
Press into the central hole of No. 1. The work procedures (2) and (3) may be replaced with each other.

Therefore, since the opening of the clamp magnet 204 on the stator side is faced so as to always attract the attraction plate 157 press-fitted into the radial bearing 155, the rotor yoke 202 is always attached in the axial direction of the shaft. Will be encouraged. That is, since the shaft 203 is pressed against the thrust bearing 156, vibration in the axial direction is suppressed even when the rotor R2 rotates at high speed, and thus vertical vibration of the shaft 203 can be suppressed. The suction plate 157 has a plate pressure that does not saturate the magnetic flux of the clamp magnet 204. By adjusting the gap between the opening of the clamp magnet 204 on the stator side and the attraction plate 157, the above-mentioned vertical vibration can be appropriately suppressed.

FIG. 6 shows a modification of the second embodiment. The modification shown in FIG. 6 is configured by a magnetic body 274 and a suction magnet 257, respectively, instead of the clamp magnet 204 and the suction plate 157 shown in FIG. Even with this configuration, since the opening of the magnetic body 274 on the stator side is opposed to always attract the attraction magnet 257 press-fitted into the radial bearing 155, the rotor yoke 202 is arranged in the axial direction of the shaft. Will always be urged. That is, the shaft 203
By being pressed against the thrust bearing 156, the axial vibration is suppressed even when the rotor R2 rotates at high speed, and thus the vertical vibration of the shaft 203 can be suppressed.

The material and type of the bearing used in the present invention are not restricted by ferrous sintered bearings, copper sintered bearings, resin bearings, composite material bearings, dynamic pressure bearings, static pressure bearings and the like.

[0025]

As described above, according to the present invention, it is not necessary to obtain the attraction force in the thrust direction by disposing the rotor at the position where the center of the annular magnet in the shaft direction is displaced toward the output shaft side. Since it is possible to prevent the increase of the leakage magnetic flux and reduce the generation of strong magnetic noise, it becomes difficult for the leakage magnetic flux to hinder the device itself.

Further, since the suction plate made of a magnetic material is arranged around the opening of the bearing housing by press fitting, there is no need for the fixing member and the bonding work for the annular permanent magnet as in the prior art.

Further, according to the mechanism of the present invention, since a sufficient magnetic preload can be obtained, the radial bearing on the side facing the rotor yoke is made of a ferrous sintered metal material and attracted by the permanent magnet on the rotor yoke side. You don't have to take a method.
Therefore, the usable bearing material is not limited.

[0028]

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a motor showing a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing a modified example of the first embodiment of the present invention.

FIG. 3 is an assembly procedure diagram of the first embodiment.

FIG. 4 is a vertical sectional view of a motor showing a second embodiment of the present invention.

FIG. 5 is an assembly procedure diagram of the second embodiment.

FIG. 6 is a vertical cross-sectional view showing a modified example of the second embodiment of the present invention.

[Explanation of symbols]

101 turntable 101a annular groove 102 rotor yoke 103 shaft 104 clamp magnet 105 back yoke 157 absorption plate 401 turntable 401a through hole 402 rotor yoke 403 shaft 404 Clamp magnet

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3J102 AA01 AA07 BA03 BA17 BA18                       CA02 CA09 DA02 DA10 FA16                       GA03                 5H019 AA06 CC03 EE14 FF01 FF03                 5H605 AA05 BB05 BB14 BB19 CC02                       CC10 DD09 EA02 EB06 EB17                       EB39 FF01 GG18                 5H621 GA01 GA16 GA17 HH01 JK07                       JK15 JK18

Claims (7)

[Claims] 1. In a spindle motor comprising an axial vibration preventing means for a rotor portion, which is a combination of a rotor yoke and a turntable, a base of a rotary shaft fixed to the rotor portion is received by a stator base of a stator portion, and a turn is provided. A magnetic generator or a magnetic attractor is disposed on the table, and the magnetic attractor or the magnetic attractor is disposed on the side of the stator so as to face the magnetic attractor or the magnetic attractor. Spindle motor with prevention mechanism. 2. The magnetic generator disposed on the turntable is a disk chucking magnet.
A spindle motor provided with an axial vibration preventing mechanism for a rotating part according to. 3. A back yoke is arranged on the turntable, and the periphery of the back yoke is bent toward the stator portion side and is close to the magnetic attraction body or the magnetic generation body arranged on the stator portion side. Item 3. A spindle motor provided with an axial vibration preventing mechanism for a rotating part according to item 2. 4. The spindle motor according to claim 3, wherein the back yoke is integrally formed with the turntable. 5. The spindle motor with an axial vibration preventing mechanism for a rotating part according to claim 1, wherein the magnetic generators or magnetic attractors arranged on the turntable are scattered outside the rotating shaft. . 6. A spindle motor having an axial vibration preventing mechanism for a rotating part according to claim 5, wherein the scattered magnetic generators or magnetic attractants are rod-shaped magnets magnetized in the axial direction. 7. The magnetic attraction body arranged on the turntable is made of a disk chucking iron plate, and the iron plate is attracted to the magnetic generator arranged on the stator side. A spindle motor equipped with an axial vibration prevention mechanism for the rotating part.