JP3519457B2 - Spindle motor - Google Patents

Abstract

PURPOSE:To raise reliability, and also, downsize a motor by preventing the leakage of lubricant fluid in a dynamic-pressure bearing part by simple constitution. CONSTITUTION:This spindle motor has a fixed pole, which has a cylindrical periphery an annular collar, which is extended outward substantially vertically from one end of this fixed pole, a sleeve member 6, which is made in roughly cylindrical shape and is set around the fixed pole, and one end of which is received by the collar, and a rotor hub 7, which is fixed to this sleeve member 6 and to which rotating load is applied. Dynamic-pressure bearings by liquid lubricant are provided between the sleeve member 6 and the fixed pole and between one end of the sleeve member 6 and the collar. A annular member is provided at the other end of the fixed pole. By this annular member, the axial shifting of the sleeve member is regulated. And, a labyrinth seal is constituted of the annular member and the sleeve member 6, and this prevents the leakage of the fluid lubricant.

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 rotatably driving a recording disk, a rotary polygon mirror, etc. Regarding a spindle motor.

[0002]

2. Description of the Related Art Spindle motors for rotational drive of magnetic disks, polygon mirrors, etc. have recently required rotational drive at a high rotational speed due to the demand for higher capacity and higher accuracy, which has resulted in dynamic pressure. Various spindle motors having a bearing structure have been proposed. This dynamic pressure bearing has, as disclosed in, for example, Japanese Patent Laid-Open No. 3-60349, an example in which a circumferential sliding contact surface between a rotor and a stator is provided.
Herringbone-shaped grooves are engraved, and the rotor rotates to increase the pressure of the lubricant filled in the grooves to function as a radial dynamic pressure bearing. Also, as the dynamic bearing in the thrust direction, a spiral groove is provided on the end face side of the rotary shaft of the rotor, and the pumping action accompanying the rotation of the rotary shaft increases the pressure in this portion to levitate the shaft.

[0003]

However, in the spindle motor having the above construction, the fluid lubricant intervening in the dynamic pressure bearing easily leaks to the outside of the motor, and once it leaks to the outside of the motor, the magnetic disk or the polygon mirror. Contaminate etc. and give serious trouble. Therefore, although a sealing means such as an O-ring is used to prevent leakage of the fluid lubricant, it is complicated and complicated in terms of assembly and configuration. On the other hand, with the recent trend toward smaller and lighter devices, there is an increasing demand for smaller and thinner spindle motors. In such a state, it is more difficult in terms of space to reduce the size of the motor while preventing the lubricant from leaking out.

The present invention has been made in view of the above-mentioned problems existing in the prior art. The problem is that the motor is miniaturized while being interposed in the dynamic pressure bearing portion. It is an object of the present invention to provide a spindle motor that can prevent leakage of a fluid lubricant that is generated by a simple configuration.

[0005]

In order to solve the above-mentioned problems, a spindle motor according to the present invention comprises a fixed support having a cylindrical surface-shaped outer peripheral portion and substantially one end of the fixed support with respect to the cylindrical surface. An annular flange portion that is formed to extend vertically outward, a sleeve member that is formed in a substantially cylindrical shape and is externally fitted to a fixed column, and one end of which is received by the flange portion, and is fixed to this sleeve member. A rotor hub to which a rotational load is attached. A radial dynamic pressure bearing using a fluid lubricant is provided between the sleeve member and the fixed support, and only one thrust dynamic pressure bearing using a fluid lubricant is provided between one end of the sleeve member and the flange. It is provided. Further, a cylindrical peripheral wall extending in the extension direction of the fixed column is formed on the outer peripheral side of the flange portion, and the cylindrical peripheral wall is close to the outer peripheral surface of the sleeve in the radial direction at a portion near one end of the sleeve. , The radial surface of the collar part where the bearing surface of the thrust dynamic pressure bearing is formed is
The outer peripheral portion is connected to the cylindrical peripheral wall. An annular member having an outer diameter larger than the inner diameter of the corresponding sleeve member is externally fitted to the other end of the fixed column, and the annular member and the sleeve member are brought into contact with each other, so that the annular member has an axis of the sleeve member. In the state where the directional movement is restricted and the annular member and the sleeve member are not in contact with each other, a labyrinth seal is formed by a minute gap between the annular member and the sleeve member, and the rotor hub has no levitation force due to the thrust dynamic pressure bearing. The magnetic force acts in the opposite direction.

Further, the fixed column and / or the sleeve member on the inner side of the motor of the annular member are
It is desirable to provide an annular groove that prevents leakage of the fluid lubricant.

[0007]

According to the spindle motor of the present invention, one end of the sleeve member that rotates relative to the fixed strut is received by the flange of the fixed strut, and the other end of the sleeve member is restricted in axial movement by the annular member. is recieving. Therefore, the sleeve member is prevented from coming off and coming off by the annular member,
Due to the collar portion and the annular member, the sleeve member is positioned at both ends of the sleeve member and is held within the range. That is, the sleeve member is positioned at a predetermined position in the axial direction. Therefore, as compared with the prior art in which the thrust (regulation) plate is provided inside the sleeve member, the structure is simplified, and the motor can be downsized, and particularly the height (thickness direction) dimension can be minimized. .

Since the annular member constitutes a labyrinth seal that cooperates with the sleeve member, it is possible to reliably prevent leakage of the fluid lubricant, and it is necessary to adopt a special dedicated structure. Because there is no,
The size of the motor can be reduced more easily.

Further, since the fixed column and / or the sleeve member is provided with the annular groove for preventing the leakage of the fluid lubricant, in addition to the Rabin rinse seal structure, more effective leakage prevention can be achieved.

[0010]

Embodiments of the spindle motor according to the present invention will be described below with reference to the accompanying drawings. 1 and 2 show a spindle motor according to the first embodiment, which is used for rotating a magneto-optical disk, for example. 1 is a sectional view showing the entire spindle motor, and FIG. 2 is an enlarged sectional view showing the main part of FIG. In these drawings, the member 1 is a shallow plate-shaped bracket and is made of, for example, stainless steel. The bracket 1 is provided with an overhanging portion 21 formed to overhang in the outer peripheral direction, and the overhanging portion 21 is attached and fixed to a disk drive device (not shown). The bracket 1 itself may be the base member of the disk drive device.

A cylindrical wall 15 is provided at the center of the bracket 1.
Is provided with a hole 13 that penetrates in the up-down direction in the center. Then, the lower end portion 30 of the shaft 2 is fitted and fixed in the hole portion 12. The shaft 2 is a fixed column for the rotor 3 (of the rotating member), has a substantially cylindrical shape, and has a cylindrical surface-shaped outer peripheral portion (hereinafter referred to as an outer peripheral portion) 28. At the lower part of the shaft 2, a flange portion 23 that is defined substantially perpendicular to the shaft 2 is integrally provided. The flange portion 23 has a substantially constant thickness, and is formed in an annular shape that projects in the outer peripheral direction with respect to the shaft 2. The flange 23 may be separately provided and fixed to the shaft 2.

When the lower end portion 30 of the shaft 2 is fitted and fixed in the hole portion 12 of the bracket 1, the shaft 2 is positioned by the lower surface 41 of the collar portion 23, and thus is erected on the bracket 1 substantially vertically. It The shaft 2 is formed of, for example, stainless steel similarly to the bracket 1. The upper end surface 22 of the collar portion 23 is formed so as to define a plane substantially perpendicular to the outer peripheral portion 28 of the shaft 2, and the sleeve 6 is received on the upper end surface 22. The upper end surface 22 receives the sleeve 6 in the thrust (vertical direction in the figure) direction, and hence is hereinafter referred to as a thrust receiving surface. Although not shown, the thrust receiving surface 22 is engraved with herringbone-shaped dynamic pressure grooves at regular intervals in the circumferential direction. Further, in a substantially central portion of the shaft 2, a herringbone-shaped dynamic pressure groove (groove) 19 is formed in upper and lower two rows in an outer peripheral portion 28 at regular intervals in the circumferential direction.

The stator 4 is mounted on the cylindrical wall 15 of the bracket 1 and the step portion 16 provided below the cylindrical wall 15. The stator 4 is composed of a stator core 11 in which a plurality of magnetic poles are formed and stacked to have a predetermined thickness, and a coil 10 wound around the stator core 11. The bottom part of the stator core 11 is received by the step part 16 of the bracket 1, and the inner peripheral part thereof is fitted and fixed to the outer peripheral part of the cylindrical wall 15. A groove 32 is annularly provided at a corner between the step 16 and the cylindrical wall 15. Groove 32
Is a relief portion in processing the step portion 16 and the cylindrical wall portion 15, but is also an adhesive agent collecting groove when the stator 4 is fixed to the bracket 1 with an adhesive agent. As is clear from the drawing, the cylindrical wall 1 to which the collar portion 23 of the shaft 2 is fixed
A similar groove 33 is also provided at the lower end of the inner peripheral portion 42 of FIG.

An annular projection wall 20 is provided on the upper surface (inside the motor) of the flat portion 24 of the bracket 1 so as to correspond to the outer peripheral side of the stator core 11, that is, the magnetic pole tooth side. The annular projecting wall 20 forms a partition wall provided so that the resin molding material with which the upper surface of the flat portion 24 is filled does not flow out. This resin mold filling maintains the insulation between the stator 4 and the bracket 1, and reduces the influence of electromagnetic vibration of the stator 4 on the bracket 1. The lead end pulled out from the coil 10 of the stator 4 is
Although not shown, it is provided so as to crawl on the upper surface of the flat portion 24 and is led out of the motor.

The rotor 3 which is rotatably supported comprises an inverted cup-shaped hub 7, a substantially cylindrical sleeve 6, and a rotor magnet 5 provided on the hub 7. The hub 7 is made of, for example, a ferromagnetic martensitic stainless steel, and has a hollow hole 43 formed in the center. A recording disk (not shown) is mounted on the yoke portion 8 of the hub 7. The recording disk is tightly fixed to the hub 7 by screwing a clamp member (not shown) into a hole 9 formed in the yoke 8. The seal member 14 attached to the inner wall 25 of the hub 7 is for sealing the hole 9, and thereby closes the inside and outside of the motor. In the inner peripheral wall 26 of the hanging portion 44 in the yoke portion 8,
The rotor magnet 5 is mounted in a ring shape.

The rotor magnet 5 is arranged to face the stator 4 in the radial direction, and a predetermined magnetic pole is magnetized in the circumferential direction. The rotor magnet 5 is positioned and fixed in the radial direction and the height direction (axial direction) by the inner peripheral wall 26 and the step portion 27 of the yoke portion 8. A groove portion 31 is provided at a corner between the step portion 27 and the inner peripheral wall 26, and this groove portion is for the same reason as the groove portions 32 and 33 already described. The rotor magnet 5 may be formed in an annular shape, or may be formed by combining a plurality of segment magnets.

The sleeve 6, which is integrally fixed coaxially with the hub 7, is fitted and fixed to the inner peripheral portion 37 of the hole 43 of the hub 7. The inner peripheral portion 29 of the sleeve 6 has a cylindrical surface shape (inner peripheral portion), and is fitted to correspond to the cylindrical surface shape (outer peripheral portion) of the outer peripheral portion 28 of the shaft 2. The lower lower end surface 35 forming one end portion of the sleeve 6 is (the collar portion 23
It is received and held by the thrust receiving surface 22. A groove 40 is annularly provided on the shaft upper end portion 45 side of the sleeve 6, and a groove 39 is annularly provided on the inner side of the motor (downward in the drawing) through the step portion 46. . The groove portion 39 is hereinafter referred to as an annular groove 39. The sleeve 6 is made of phosphor bronze, for example.

Lower peripheral portion 47 of sleeve 6 in the figure
Corresponds to the cylindrical wall 15 of the bracket 1 and has a relief shape with a reduced diameter. The lower peripheral portion 47 is provided with an annular groove 48 and an annular groove 49 in order from the top to the bottom of the drawing. The outer peripheral portion 50 at the lower end and the inner peripheral portion 42 (of the cylindrical wall 15) are provided close to each other in the radial direction.

On the other hand, on the upper end portion 45 side of the shaft 2, a thrust ring 18 which is an annular member is externally fitted and fixed in correspondence with the groove portion 40 of the sleeve 6. The thrust ring 18 is formed of, for example, a steel material or a copper alloy. A groove 38 is annularly provided on the shaft 2 inside the motor of the thrust ring 18. The groove portion 38 is hereinafter referred to as an annular groove 38.

A fluid lubricant such as oil is provided between the outer peripheral portion 28 of the shaft 2 and the inner peripheral portion 29 of the sleeve 6 which is fitted onto the outer peripheral portion 28 of the shaft 2 and the shaft 2 and the sleeve 6. Along with the relative rotation with respect to, a radial dynamic pressure bearing is formed by the dynamic pressure groove 19. In addition, between the lower end surface 35 of the sleeve 6 and the thrust receiving surface 22 of the collar portion 23,
A similar oil is provided so as to intervene, and a thrust dynamic pressure bearing that floats the sleeve 6 in the upward direction in the drawing by the relative rotation of these is configured. The hub 7 is rotatably supported by the shaft 2 by these dynamic pressure bearings.

In the above dynamic pressure bearing, the dynamic pressure groove is provided on the shaft 2 side and the flange portion 23 side, that is, on the stationary side of the motor. On the contrary, in the sleeve 6 on the rotating side. The dynamic pressure groove may be formed on the peripheral portion 29 side (radial dynamic pressure bearing) and the lower end surface 35 side of the sleeve 6 (thrust dynamic pressure bearing). It is also possible to employ a combination of these.

Next, the features of the present spindle motor will be further described with reference to FIG. First, the above-mentioned thrust ring 18 is externally fitted and fixed to the upper end portion 45 side of the shaft 2. Normally, when the hub 7 (or the sleeve 6) is rotationally driven, the hub 7 (or the sleeve 6) is slightly floated in the upward direction of the drawing and rotationally supported by the thrust dynamic pressure bearing. In that case, the stepped portion 46 of the sleeve 6 and the lower end portion 51 of the thrust ring 18 are positioned with a gap so that they do not come into contact with each other. It should be noted that the stator 4 and the rotor magnet 5 are positioned in advance so that their magnetic centers in the axial direction are slightly deviated from each other.
Always receives an acting force so that it is pulled to the lower side of the figure (bracket 1 side). The levitation force acting in the opposite direction of this acting force, that is, the levitation force by the thrust dynamic pressure bearing, is balanced at a predetermined portion by the acting force.

However, when the hub 7 (or the sleeve 6) tries to come out of the shaft 2 for some reason, the thrust ring 18 causes the hub 7 (or the sleeve 6) to come out.
Limit the movement in the axial direction (vertical direction in the figure). That is, the lower end portion 51 of the thrust ring 18 and the step portion 46 of the sleeve 6 come into contact with each other to limit the movement of the sleeve 6. Therefore, the movement limitation of the sleeve 6 can be freely determined by arbitrarily setting the gap between the thrust ring 18 and the step portion 46.

As described above, the sleeve 6 is positioned from both sides in the axial direction by the thrust ring 18 and the collar portion 23. Since the thrust ring 18 is provided at the shaft end portion (shaft upper end portion 45) of the motor, the structure is simple and no extra space is required, so that the motor can be downsized. . In particular, the dimensional height of the motor in the axial direction can be minimized. Therefore, the outer diameter of the thrust ring 18 is
It suffices that the inner diameter of the inner peripheral portion 19 of the sleeve 6 is set larger than the inner diameter of the sleeve 6. For example, the outer diameter of the shaft 2 into which the thrust ring 18 is fitted is not limited. That is, the fitting portion of the thrust ring 18 may be reduced in diameter. At least the lower end portion 51 of the thrust ring 18, which may come into contact with the step portion 46 of the sleeve 6, may be coated with Teflon resin or the like having high wear resistance.

Another operation of the thrust ring 18 will be described below. In the annular groove 38 of the shaft 2 and the annular groove 39 of the sleeve 6, the fluid lubricant of the radial dynamic pressure bearing (according to the shaft 2 and the sleeve 6) has an end portion 52 (an end portion on the outside of the motor) on which the fluid lubricant is located. It is provided so as not to leak from That is, the opening of the end portion 52 is set to have an obtuse angle by the annular grooves 38 and 39.
(It is set to about 180 degrees in the illustrated example.) Therefore, the end portion 52
In the above, the fluid lubricant that is about to leak does not easily leak because it tends to be spherical due to the surface tension.
(If the opening of the end portion 52 has an acute angle, the fluid lubricant easily leaks into the fan-shaped gap between the sleeve 6 and the shaft 2 due to the capillary phenomenon.) Therefore, the annular groove 38, 39 serves as a means for preventing leakage of the fluid lubricant.

Further, the thrust ring 18 is arranged close to the sleeve 6, which further improves the sealing performance. Therefore, even if the fluid lubricant flows out from the end portion 52, the leakage is prevented between the thrust ring 18 and the sleeve 6. That is, the leak is doubly blocked.

The sealing performance of the thrust ring 18 is
This is because the thrust ring 18 and the sleeve 6 form a labyrinth seal, and specifically, the thrust ring 18 and the step portion 46, and the thrust ring 18 and the groove portion 4 are included.
A minute gap of 0 is provided in both the axial direction and the radial direction. By the way, the shortest axial distance (gap size) is
0.03 mm, the shortest radial distance (gap size)
Is set to 0.05 mm. Needless to say, if these values are small, the sealing performance is improved. Therefore, the thrust ring 18 is the same as the sleeve 6 described above.
In addition to restricting the movement of the fluid, the leakage of the fluid lubricant can be prevented more effectively. In addition, in this embodiment, in order to further prevent the leakage of the fluid lubricant, the annular groove 3
An oil repellent agent that repels a fluid lubricant is applied to the surfaces of 8, 39, the stepped portion 46 and the groove portion 40, and the surface of the thrust ring 18 facing these (inside the motor in the figure).

As described above, the thrust ring 18 also functions as a sealing means (labyrinth seal) for preventing the leakage of the fluid lubricant, and a high sealing performance can be obtained with a simple structure. In addition to this, since a dedicated structure associated therewith is not required, the space does not become bulky, and the size of the motor described above can be further reduced.

On the other hand, the end portion 53, which is on the thrust dynamic pressure bearing side and is on the outer side of the motor, is surrounded by the cylindrical wall 15 on the outer peripheral side. Therefore, the radial gap between the lower peripheral portion 50 of the sleeve 6 and the inner peripheral portion 42 of the cylindrical wall 15 serves as a reservoir 54 for the fluid lubricant. Therefore, when the motor is driven to rotate, both the radial and thrust dynamic pressure bearings retain the fluid lubricant in the dynamic pressure groove, but when the rotation is stopped, the fluid lubricant that is no longer retained is retained in this reservoir. Is stored in the department. For this reason, a large amount of fluid lubricant is retained in the dynamic pressure bearing portion, so that it is possible to realize a long-life dynamic pressure bearing without exhaustion. An annular groove 34 is provided at the corner between the outer peripheral portion 28 of the shaft 2 and the thrust receiving surface 22 (of the collar portion 23). This groove 34
Is a relief portion for obtaining the right-angled workability of both, and also serves as a holding portion for the fluid lubricant. As a result, both the action of reducing the viscous resistance of the fluid lubricant and the storage are obtained.

The fluid lubricant stored in the storage portion 54 leaks over the outside of the motor, that is, the cylindrical wall 15 due to a change in the internal pressure due to the movement of the motor by the rotation / stop operation of the motor and the temperature rise inside the motor. To be acted upon. However, in the lower outer peripheral portion 47 of the sleeve 6,
The annular grooves 49 and 48 are provided, and the gap between them and the inner peripheral portion 42 of the cylindrical wall 15 prevents leakage. That is, even if the fluid lubricant in the reservoir portion 54 tries to leak out and moves upward in the drawing, first, the gap between the annular groove 49 and the inner peripheral portion 42 is suddenly opened (set to an obtuse angle). (Has the same function as the annular grooves 38 and 39 described above).
Therefore, it becomes spherical due to the surface tension and does not easily leak. Further, due to the gap between the annular groove 48 and the inner peripheral portion 42 provided on the upper portion thereof, the leakage is prevented in two stages.

Regarding setting the opening to an obtuse angle, it is necessary to set an angle exceeding 90 degrees.
Desirable for improving leakage prevention of fluid lubricant. Then, by applying an oil repellent agent that repels the fluid lubricant to the surfaces of the annular grooves 48 and 49 and the inner peripheral portion 42 of the cylindrical wall 15, it is possible to further improve the leakage prevention effect.

By the way, in this embodiment, the gap size in the radial direction of the reservoir 54 is 0.1 mm. Moreover, the annular groove 4
The groove depth of 8, 49 is set to 0.2 mm. The groove depth can be appropriately set according to various conditions such as the filling amount and viscosity of the fluid lubricant used. Further, such a groove shape can also be freely set so that the opening angle defined by the cylindrical wall 15 (inner peripheral portion 42) is maximized.

As described above, in the spindle motor of the first embodiment, the fluid lubricant filled in both the radial and thrust dynamic pressure bearings has the end portions 52 and 53 on the outer side of the motor.
In, the leakage is effectively prevented. Since the thrust ring 18 is provided especially on the upper end portion 45 side of the shaft 2, the motor can be downsized. Also, the lower end portion 3 of the shaft 2
On the 0 side, the cylindrical wall 15 forms the reservoir 54 that stores the fluid lubricant. Therefore, fluid depletion, long life, and high reliability can be obtained.

Next, FIG. 3 shows a spindle motor of a second embodiment which is a modification of FIG. 2, and the drawing is an enlarged sectional view of the same. The difference between FIG. 3 and FIG. 2 is as follows, and the description of the overlapping portions and parts will be omitted. Also, in FIG. 3, the same parts and members as in FIG. 2 are given the same numbers as in FIG. In FIG. 3, as the stationary member 60, the shaft portion 55 and the bracket portion 56 are integrally formed. This is a so-called integrated base type in which, for example, the lower frame of the optical / magnetic disk drive also serves as the bracket of the spindle motor. On the flat portion 57 of the bracket portion 56, the stator 62 with an air-core coil is attached via the substrate 63.

On the other hand, a hub portion 59 and a sleeve portion 58 are integrally formed on the rotating member side. And the hub portion 5
The inner wall 65 of 9 faces the stator 62 in the axial direction,
A disk-shaped rotor magnet 61 is attached. Thus, by integrally forming the members, it is desirable to reduce the number of parts, simplify the shape, and reduce the size. In addition, in the second embodiment, a so-called axial gap type motor is adopted, and it is possible to further reduce the size by implementing such a configuration. Of course, a combination of both the configurations of FIGS. 2 and 3 can be adopted. In FIG. 3, the structure of the radial and thrust dynamic pressure bearings, the thrust ring 18 and the cylindrical wall portion 6 are shown.
4 and the like have the same configuration as that in FIG. 2, and the same action and effect as the leakage prevention of the fluid lubricant are also the same.

Next, FIGS. 4 and 5 show a spindle motor according to still another embodiment, which is an enlarged sectional view of the periphery of the attachment portion of the thrust ring. In addition, in the following FIGS. 4 (a) to 4 (d) and FIG. 5, the same numbers are given to the same portions and members. Figure 4
(A) differs from the thrust ring mounting structure shown in FIGS. 1 to 3 in the following points. That is, in FIG. 4A, the sleeve 72 and the shaft 7
A reservoir 78 for storing a fluid lubricant is formed at an end 79 of the dynamic pressure bearing between the reservoir and the bearing 3. In the illustrated example, the storage portion 78 is formed by forming a cutout-shaped groove on the sleeve 72 side, but it may be formed by forming a cutout on the shaft 73 side. By the way, in the embodiment, the radial gap of the reservoir 78 is set to about 0.2 mm. As a result, since the fluid lubricant can be retained also on the upper end side of the shaft 2, it is possible to more sufficiently prevent leakage of the fluid lubricant due to movement and rotation of the motor and pressure change inside the motor. The holding amount of the fluid lubricant is increased, the life is extended, and the reliability is improved.

FIG. 4B shows a structure in which the corners of the thrust ring 71 and the stepped portion 74 in FIG. As a result, the passage length of the facing gap portion is increased, so that the sealing performance of the labyrinth seal formed by the thrust ring 71 and the sleeve 72 is improved. In addition, the annular groove provided on the shaft 73 side is shown in FIG.
In FIG. 4B, an annular groove 77 having a triangular cross section is used in FIG.
Is formed as an annular groove 81 having a rectangular cross section. The opening at the end 79 between the shaft 73 and the sleeve 72 is set to an obtuse angle as in FIG. 4A, so that leakage of the fluid lubricant is prevented. The annular groove 81 is also provided radially inward of the shaft 73,
As shown by the dotted line 80, the diameter of the shaft 73 may be reduced and the outer ring 71 may be fitted with the thrust ring 71.

In FIG. 4C, a peripheral groove 82 having a V-shaped cross section is provided on the outer peripheral portion of the thrust ring 71. Accordingly, the groove portion 83, that is, the inner peripheral portion 8 of the sleeve 72.
The labyrinth seal performance in the gap between No. 5 and the outer peripheral portion of the thrust ring 71 is improved. Further, since the gap between the sleeve 72 and the inner peripheral portion 85 is suddenly opened by the peripheral groove 82, the leakage preventing effect of the surface tension of the fluid lubricant can be obtained.

In FIG. 4D, the thrust ring 71 is
A peripheral groove 84 having a rectangular cross section is provided.
This has the same effect as (c). In particular, in FIG. 4D, since the circumferential groove 84 has a large amount of voids, the air flow is retained in the voids, so that the labyrinth seal performance can be further improved.

In FIGS. 4A to 4D, the annular groove 77 (81) is provided on the shaft 73 side and the annular groove 74 is provided on the sleeve 72 side in correspondence with the end portion 79. In FIG. 5, the annular groove 76 is provided only on the sleeve 72 side. Therefore, the outer periphery of the shaft 73 can be used as it is without any processing. (The annular groove 76 also serves as the stepped portion of the sleeve 72 in the illustrated example.) A gap formed by the thrust ring 71, the sleeve 72, and the shaft 73 causes the retention of the air flow, and the fluid lubricant. Prevent the leakage of.
Further, the labyrinth seal structure formed by the gap 87 between the thrust ring 71 and the sleeve 72 further prevents leakage. Further, a portion 78 in FIG. 5 is a storage portion formed by the shaft 78 and the sleeve 72. The cutout portion of the reservoir 78 is provided on the sleeve 72 side because it is used without processing the shaft 73 side, but it may be provided on the shaft 73 side.

Next, FIGS. 6 and 7 are enlarged sectional views of the cylindrical wall 15 at the lower end of the shaft and the lower portion of the sleeve 6 described in FIGS. The same parts and members in FIGS. 6 and 7 are given the same numbers. In FIG. 6A, the gap between the cylindrical wall 90 and the sleeve lower end outer peripheral portion 91 is configured as a storage portion 95 of the fluid lubricant, but the difference from FIGS. The annular groove 93 for preventing leakage is provided on the side of the cylindrical wall 90.

In FIG. 6B, a recess 94 is provided in the cylindrical wall 90 instead of the annular groove 93. As a result, the holding amount of the storage portion 95 is increased, and the same leakage 42 blocking action is provided on the upper side of the recess 94.

In each of FIGS. 7A to 7C, the cylindrical wall 90 is positioned on the outer peripheral side of the sleeve lower end outer peripheral portion 91 to form the storage portion 95. At that time, the sleeve 6 side is shaped so as not to escape from the cylindrical wall 90. Then, in FIG. 7A, the annular groove 9 is provided on the sleeve 6 side.
7, 98 are formed to prevent double leakage of the fluid lubricant.

In FIG. 7B, the annular grooves 99 and 100 are provided on the cylindrical wall 90 side, and in FIG. 7B, the annular grooves 88 and 89 are formed on the sleeve 6 side and the cylindrical side. The recesses 96 are formed on both sides of the wall 90 and below the annular groove 89. Needless to say, the cylindrical wall portion 90 may be provided on the flange portion of the shaft in addition to being integrally provided on the bracket.

As described above, in the spindle motor of the present invention, various configurations and combinations can be made, and thereby, the holding of the fluid lubricant and the leakage prevention are improved while the motor is downsized. . The various embodiments of the spindle motor according to the present invention have been described above.
Design changes and modifications can be freely made without departing from the spirit of the present invention.

[0046]

Since the spindle motor of the present invention has the above-mentioned structure, it has the following effects. That is, according to the spindle motor of the present invention, the sleeve 6 rotating relative to the shaft 2 has the shaft lower end portion 30 received by the flange portion 23, and the shaft upper end portion 45 has the axial movement restricted by the thrust ring 18. receive. Therefore, the sleeve 6 (and thus the hub 7) is the thrust ring 1
8 prevents the retainer from coming off in advance, and axially positions the sleeve 6 at both ends. Therefore, as compared with the prior art in which the thrust regulating plate is provided inside the sleeve 6, the structure is simplified and the motor can be downsized.

Since the thrust ring 18 forms a labyrinth seal in cooperation with the sleeve 6, it is possible to reliably prevent the leakage of the fluid lubricant, and it is not necessary to adopt a special dedicated structure. . Further, by using the leak-preventing annular grooves 38, 39 or the like in one or both of the shaft 2 and the sleeve 6, the leak-preventing effect can be further enhanced. As described above, according to the spindle motor of the present invention, with a simple configuration, it is possible to more easily realize the downsizing of the motor without being bulky, and it is possible to effectively prevent the leakage of the fluid lubricant.

[Brief description of drawings]

FIG. 1 is a sectional view showing an entire spindle motor according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is an enlarged sectional view of a main part of a spindle motor showing another embodiment.

FIG. 4 is an enlarged cross-sectional view of a main part showing a part of a spindle motor according to another embodiment of the present invention, showing different embodiments in (a) to (d).

FIG. 5 is an enlarged sectional view of a main part of a spindle motor according to still another embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view of a main part of a spindle motor according to still another embodiment of the present invention, showing different embodiments in (a) and (b).

FIG. 7 is an enlarged cross-sectional view of a main part of a spindle motor according to still another embodiment of the present invention, showing different embodiments from (a) to (c).

[Explanation of symbols]

1 bracket 2 shafts 3 rotor 4 stator 5 rotor magnet 6 sleeve 7 hub 38, 39, 48, 49 annular groove

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-133515 (JP, A) JP-A-3-157513 (JP, A) JP-A-3-159552 (JP, A) JP-A-5- 288214 (JP, A) JP-A-5-240241 (JP, A) JP-A-6-253489 (JP, A) JP-A-6-33941 (JP, A) Actual Kaihei 5-55772 (JP, U) Actual Kaihei 6-28336 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02K 5/10 H02K 5/167 H02K 7/08

Claims (2)

(57) [Claims] 1. A fixed strut having a cylindrical surface-shaped outer peripheral portion, an annular collar portion extending outward from one end of the fixed strut substantially perpendicularly to the cylindrical surface, and a substantially cylindrical shape. A sleeve member that is formed on the fixed support column and is externally fitted to the fixed strut, and one end of which is received by the flange portion; and a rotor hub that is fixed to the sleeve member and to which a rotational load is attached. A radial dynamic pressure bearing using a fluid lubricant is provided between the member and the fixed column, and only one thrust dynamic pressure bearing using a fluid lubricant is provided between one end of the sleeve member and the flange. In the spindle motor provided with, a cylindrical peripheral wall extending in the extension direction of the fixed column is formed on the outer peripheral side of the flange portion, and the cylindrical peripheral wall is provided at a portion near one end of the sleeve. Radially adjacent to the outer peripheral surface of the sleeve, the radially expanding surface of the flange portion where the bearing surface of the thrust dynamic pressure bearing is formed is connected to the cylindrical peripheral wall at the outer peripheral portion thereof, An annular member having an outer diameter larger than the inner diameter of the corresponding sleeve member is externally fitted to the other end of the fixed strut, and the annular member is brought into contact with the annular member by the contact between the annular member and the sleeve member. A labyrinth seal is formed by a minute gap between the annular member and the sleeve member in a state where the axial movement of the sleeve member is limited and the annular member and the sleeve member are not in contact with each other, and the rotor hub has A spindle motor, wherein a magnetic force in a direction opposite to the levitation force of the thrust dynamic pressure bearing is acting. 2. An annular groove for preventing leakage of the fluid lubricant is provided in the fixed support column and / or the sleeve member on the inner side of the motor of the annular member.
The described spindle motor.