JPH0837755A - Spindle motor - Google Patents

Abstract

PURPOSE:To surely prevent the leaking of such a fluid lubricant as oil, etc., from a hydrodynamic pressure bearing with a simple structure. CONSTITUTION:A spindle motor is provided with a shaft member 2 fixed to a housing 1 and rotor hub 3 which is rotationally supported by the member 2 through fluid lubricant. The member 2 is provided with a thrust plate 6 and both end faces 38 and 39 of the plate 6 are substantially formed at right angles against the axial direction of the member 2. The rotor hub 3 is provided with a sleeve 8 which is supported by a hydrodynamic pressure bearing in the radial direction together with the member 2 and a thrust cover 7 which supports the hub 3 with a plate 6 and sleeve 8 through a hydrodynamic pressure bearing while the cover 7 controls the position of the hub 3 in the axial direction. A clearance 73 is formed over the entire periphery of the plate 6 on the outer peripheral end side and a hole section 20 which makes the clearance 73 communicate with the outside of the motor is formed at one end section of the sleeve 8 corresponding to the clearance 73. The opening of the hole section 20 on the clearance side is formed in an erected state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor using a fluid dynamic pressure bearing suitable for rotationally driving a recording disk such as an optical / magnetic disk driving device.

[0002]

2. Description of the Related Art A spindle motor for rotationally driving an optical / magnetic disk or the like is required to prevent rattling of a rotor hub in the disk mounting direction, that is, the axial direction and to be rotatably supported with high accuracy. Therefore, as the bearing means of the rotor hub, a dynamic pressure bearing means using a fluid lubricant such as oil has been adopted, instead of the conventional ball bearing. The dynamic pressure bearing means is composed of a radial dynamic pressure bearing that supports dynamic pressure in the radial direction with respect to the rotary shaft, and a thrust dynamic pressure bearing that positions and supports the dynamic pressure in the rotary shaft direction.

[0003]

In the spindle motor having the above-mentioned structure, oil is usually injected as a fluid lubricant into the motor. However, the biggest cause of fluid dynamic pressure bearing failure is This oil may leak out of the motor. For example, air may be mixed into the oil of the fluid dynamic bearing when the fluid dynamic bearing is assembled or when the motor is rotated. In such a case, if the temperature of the fluid dynamic bearing portion rises or if the pressure outside the motor is lower than the fluid dynamic bearing portion, the air will expand significantly and oil will be pushed out of the fluid dynamic bearing. , Oil leakage occurs. On the other hand, an impact load or a centrifugal force may be applied to the motor from the outside of the motor for some reason. In this case as well, the oil that cannot be held by the fluid dynamic pressure bearing portion scatters and causes oil leakage.

When an oil leak occurs, the amount of oil retained in the fluid dynamic bearing decreases, which makes it difficult to support the bearing accurately and stably, and further shortens the life of the bearing. In addition, the oil leaked to the outside of the motor contaminates the disk storage chamber and causes a read / write failure of the disk. The present invention has been made in view of the above problems existing in the prior art, and the problem is that fluid lubrication resulting from a pressure difference between the inside and outside of the motor and a load applied from the outside of the motor. An object of the present invention is to provide a spindle motor that can eliminate leakage of a chemical with a simple configuration.
Still another object of the present invention is to provide a highly reliable spindle motor capable of obtaining stable and highly accurate rotation support by preventing leakage of a fluid lubricant.

[0005]

In order to achieve the above object, a spindle motor according to the present invention comprises a housing,
A spindle comprising a shaft member fixed to the housing, a rotor hub rotatable relative to the shaft member, and a hydrodynamic bearing unit interposed between the shaft member and the rotor hub. In the motor, the shaft member is provided with a thrust plate that projects outward in the radial direction, and the rotor hub includes a sleeve rotatably supported by the shaft member and a thrust cover that covers the thrust plate. A radial bearing portion is provided between the sleeve and the shaft member, and a thrust bearing portion is provided between the end portion of the sleeve and the thrust plate and between the thrust cover and the thrust plate, respectively. And an annular space defined by the sleeve and the thrust cover is provided on the outer peripheral side of the thrust plate. The annular space is provided with a communication hole for making the pressure in the annular space substantially equal to the pressure outside the motor, and the opening of the communication hole that opens into the annular space is the annular space. It projects inward from the inner surface that defines

According to the spindle motor of the present invention, there is provided one in which the communication hole communicates with the inside of the motor. Further, the sleeve is provided with a spindle motor in which an end of a cylindrical member for communicating the annular space with the inside of the motor is projected into the annular space.
Further, in the spindle motor, it is desirable that an oil repellent agent that repels the fluid lubricant of the thrust bearing portion is applied to the surfaces of the sleeve and the thrust cover that define the annular space. Further, it is desirable to provide a plurality of uneven portions at intervals in the circumferential direction on the surface defining the outer peripheral surface of the annular space.

[0007]

According to the spindle motor of the present invention, two thrust bearing portions for axially regulating the rotor hub to support the dynamic pressure bearing, that is, between the end portion of the sleeve and the thrust plate, and between the thrust cover and the thrust plate are provided. And a fluid lubricant are separately interposed between and. These fluid lubricants communicate with the annular space formed on the outer peripheral side of the thrust plate. Moreover, the annular space is provided with a communication hole that substantially equalizes the pressure inside and outside the motor. The communication hole eliminates a pressure difference between the inside and the outside of the motor. That is, even if bubbles are contained in the fluid lubricant, they are easily defoamed in this gap. Further, even if there is an atmospheric pressure change element due to a rise in the temperature of the motor or the like, a pressure difference is not substantially generated, so that the fluid lubricant is prevented from being pushed out and leaking.

If, for some reason, an impact load or a centrifugal force is exerted from the outside of the motor, the fluid lubricant retained on both end faces of the thrust plate scatters or leaks into the annular space. However, since the opening of the communication hole is provided so as to project inside, the fluid lubricant is stored in the annular space without passing over the opening and leaking to the outside of the motor. Then, the stored fluid lubricant is easily recovered in the original holding portion, and the fluid lubricant is not depleted. Since the communication hole communicates with the inside of the motor, even if fluid lubricant leaks from the opening, it stays inside the motor, preventing accidents that it leaks directly to the outside of the motor. , There is no pollution in the disc room. By the way, by mounting a tubular member in the opening forming the communication hole, it can be easily constructed, and the assembling / working efficiency can be improved. Further, when an oil repellent agent that repels the fluid lubricant is applied to the inner surface of the annular space, the friction resistance of the fluid lubricant scattered in the annular space decreases,
It becomes easy to collect the original holding portion. Further, by providing the uneven portion on the surface that defines the outer peripheral surface of the annular space, the collectability of the fluid lubricant can be improved with the rotation of the motor without being restricted by the posture and direction of the motor.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a spindle motor according to the present invention will be described with reference to the accompanying drawings. 1 and 2 show a spindle motor of a first embodiment for driving a magnetic disk, for example, and FIG. 1 is a sectional view showing the whole thereof.
FIG. 2 is an enlarged cross-sectional view of an essential part showing a part of FIG. 1 in an enlarged manner. In FIGS. 1 and 2, a member 1 is a housing forming a part of a magnetic disk drive device, and is directly or indirectly attached to a base member of the drive device. The housing 1 is made of, for example, an aluminum alloy. A boss portion 22 that projects annularly is integrally formed in the center of the housing 1, and a hole portion 23 is formed in the boss portion 22. One end (lower part) of the shaft 2 is fitted and fixed in the hole 23. Shaft 2
Is formed of, for example, an iron-based alloy material. The housing 1 and the shaft 2 serve as a stationary member of the present spindle motor.

A notch 60 is formed on the outer peripheral side of the upper end of the boss portion 22 of the housing 1, and the notch 6 is formed.
The stator 4 is externally fitted and fixed to 0. Stator 4
Is composed of a stator core 18 formed by laminating a plurality of electromagnetic steel sheets, and a (armature) coil 17 wound around the stator core 18. A flexible circuit board 10 is attached and fixed to a lower portion of the housing 1, and an end portion of the flexible circuit board 10 is provided so as to extend to the outside of the motor. Therefore, the coil wire 61 drawn out from the coil 17 is
4 is electrically connected to the flexible circuit board 10 located at the lower portion of the motor through the hole 16 formed in the hole 4, and is electrically led to the outside of the motor.

The other end (upper part) of the shaft 2 fixed to the housing 1 is formed so as to have a reduced diameter, and a hole 11 is bored in its axial center part. The hole 11 is screwed and fixed to an upper lid of a magnetic disk drive (not shown). On the other end (upper part) side of the shaft 2, a thrust plate 6 is integrally formed so as to project radially outwardly over the entire circumference. The shaft 2 and the thrust plate 6 are configured coaxially.
The upper and lower end surfaces 38, 39 of the thrust plate 6 are formed substantially at right angles to the shaft 2. That is, the upper and lower end surfaces 38, 39 are formed substantially parallel to each other. A groove 33 having a substantially V-shaped cross section is formed on the outer peripheral portion 32 of the thrust plate 6 over the entire circumference.

Although not shown in the drawings, the upper and lower end surfaces 38, 39 are moved by grooves having a substantially V shape, a herringbone shape, or a double helical shape provided at predetermined intervals in the circumferential direction (not shown). A pressure groove is formed. On the other hand, the dynamic pressure groove 1 having a similar herringbone-shaped groove is also provided on the outer peripheral portion 24 at the substantially central portion of the shaft 2.
9 and 19 are provided at predetermined intervals in the circumferential direction, and these are provided in two rows aligned in the vertical direction.

Next, the rotor hub 3 which is rotatably supported by the shaft 2 is composed of a bearing-supported sleeve 8, a thrust cover 7, a hub 9 and a rotor magnet 5. The sleeve 8 is formed by using, for example, a copper-based alloy, and has a cylindrical hanging portion 29 and the hanging portion 2
9 and a cylindrical peripheral wall (large diameter peripheral wall) 48 which is formed to have a diameter larger than that of 9 and is provided coaxially therewith. The hanging portion 29 and the large-diameter peripheral wall 48 are connected and fixed by a base portion 21 which is integrally formed like these.

The thrust cover 7 has a substantially disc shape, and has a hole 62 at the center thereof for inserting the end of the shaft 2. The thrust cover 7 is fixed to the sleeve 8 on the outer peripheral side thereof. That is, the thrust cover 7
The lower end surface 63 on the outer peripheral side of the base portion 21 of the sleeve 8.
The outer peripheral end portion 37 of the thrust cover 7 and
The upper inner peripheral wall 56 of the large diameter peripheral wall 48 is brought into contact with and held. Then, the upper wall 47 of the large-diameter peripheral wall 48 is caulked to the shaft side (inside) by plastic deformation processing or the like, and the thrust cover 7 is tightly fixed to the sleeve 8. At this time, the lower end surface 42 of the thrust cover 7 and the upper end surface 43 of the hanging portion 29 of the sleeve 8 are arranged to face the upper and lower end surfaces 38, 39 of the thrust plate 6 with a slight clearance, respectively, and in these respective clearances. Is filled with oil as a fluid lubricant. An arcuate portion 70 is formed on the lower end surface 42 of the thrust cover 7 on the shaft 2 side (inner circumferential side). The arcuate portion 70 forms an oil storage groove by the upper end surface 38 of the thrust plate 6. Eggplant

On the outer peripheral end side of the thrust plate 6, a gap (annular space) 73 is formed over the entire circumference so as to surround it.
Are formed. The gap 73 includes a lower end surface 80 of the thrust cover 7, an inner peripheral wall 71 (a peripheral wall 48 of the sleeve 8),
The base portion 21 of the sleeve 8 and the bottom surface 72 form an annular shape. A hole portion 20 penetrating in the axial direction is formed in the base portion 21 of the sleeve 8 corresponding to the gap 73, and communicates with the outside of the motor. In addition, this hole 2
0 communicates with a dynamic pressure generating portion (described later) formed by the lower end surface 42 of the thrust cover 7 and the thrust plate 6, and the thrust plate 6 and the upper end surface 43 of the sleeve 8. The hole 20 is centered on the axis of the shaft 2,
A plurality of bases 21 are evenly arranged in the circumferential direction, and in the present embodiment, they are provided at two locations in a 180-degree rotational symmetry (shown on the left and right in FIG. 1). And hole 2
On the side of the gap 73 in 0, as shown in the drawing, a raised portion 74 that is raised in a cylindrical shape is formed. The hole 20 is the rotor 3
In consideration of the rotational movement balance, when a plurality of them are provided, it is desirable that they are evenly arranged in the circumferential direction.

According to this embodiment, the lower end surface 42 of the thrust cover 7 and the upper end surface 38 of the thrust plate 6, and the lower end surface 39 of the thrust plate 6 and the upper end surface 43 of the hanging portion 29 (of the sleeve 8) are thrust. A dynamic pressure bearing means is configured, which restricts the position of the rotor hub 3 in the axial direction and supports the rotation of the rotor hub 3 in the axial direction by the dynamic pressure bearing.
As the thrust dynamic pressure bearing, the dynamic pressure groove may be provided on the thrust cover 7 and the sleeve 8 (the hanging portion 29 thereof) side instead of being provided on the thrust plate 6.

On the other hand, the inner peripheral portion 5 of the hanging portion 29 of the sleeve 8
3 and the outer peripheral portion 24 of the shaft 2 are arranged to face each other along the axial direction with a slight gap. Then, this gap is filled with oil as a fluid lubricant. As a result, the rotor hub 3 is supported by the shaft 2 in the radial direction in a dynamic pressure bearing manner. In this embodiment, as the radial dynamic pressure bearing, the dynamic pressure groove is provided on the shaft 2 side, but conversely, it may be provided on the sleeve 8 side.

A hub 9 made of aluminum alloy or the like is fixed to the outer peripheral portion of the large-diameter peripheral wall 48 of the sleeve 8.
The rotor magnet 5 is annularly arranged on the inner peripheral portion 64 of the hub 9. The rotor magnet 5 is magnetized with a predetermined number of magnetic poles in the circumferential direction. The rotor magnet 5
Is brought into contact with the lower end 49 of the large-diameter peripheral wall 48 of the sleeve 8 for axial height positioning, that is, is fixed to the hub 9 corresponding to the height position of the stator 4.
Therefore, when a required signal is applied to the lead-out end of the flexible circuit board 10, the stator 4 and the rotor magnet 5 are connected.
The rotor hub 3 is rotationally driven by the electromagnetic action of and. A magnetic disk (not shown) is fitted and mounted on the outer peripheral portion 28 of the hub 9, is received by the flange portion 12 formed below, and is fixed by already known clamping means.

As described above, the spindle motor of the present invention is supported by the radial and thrust dynamic pressure bearings, and a predetermined portion is filled with oil as a fluid lubricant. In order to prevent the filled oil from leaking to the outside of the motor, and in addition to this, in order to maintain stable bearing support, the same FIG. 1 and FIG. 2 are used in the spindle motor of the present invention. The configuration described below is made. In these drawings, one of the radial dynamic pressure bearings (the lower side of the drawings; the outside of the motor) will be described first. Outer peripheral portion 24 of shaft 2 and sleeve 8
Between the hanging part 29 of the
0 is provided. The void 50 is formed by forming concave portions 65 and 66 over the entire circumference in the outer peripheral portion 24 of the shaft 2 and the inner peripheral portion 53 of the hanging portion 29, and arranging these to face each other in the radial direction. . Moreover, an oil repellent that repels oil is applied to the surfaces of the recesses 65 and 66.

Therefore, even if the oil in the dynamic pressure groove 19 tries to leak to the outside of the motor (downward direction in the drawing), the outer peripheral portion 24 of the shaft 2 and the inner peripheral portion 53 of the hanging portion 29.
Since the gap between and is abruptly opened by the gap 50, and because the oil repellent is applied to the recesses 65 and 66, leakage due to surface tension is prevented. A groove 51 is provided in the inner peripheral portion 53 of the hanging portion 29 on the inner side of the motor in the gap 50, that is, on the upper side in the drawing. This groove 51 is accompanied by rotation and stop of the motor.
This is a storage groove in which the oil held in the dynamic pressure groove 19 moves and the excess oil is stored by the movement.
The groove 51 is formed such that the gap between the groove 51 and the outer peripheral portion 24 of the shaft 2 is larger than that of the dynamic pressure bearing portion and the oil can be retained by the tension due to the capillary phenomenon. In this embodiment, 0.0
The gap is set to 5 mm.

A gap 54 is formed on the other side of the radial dynamic pressure bearing (upper side in the figure; inside the motor), similar to the gap 50. The void 54 is formed at the corner between the root of the thrust plate 6 and the sleeve 8. The operation is similar to that of the gap 50, and the groove 52 provided in the hanging portion 29 is an oil storage groove. The lower side of the thrust dynamic pressure bearing is connected to the upper end surface 43 which is one end side of the hanging portion 29 of the sleeve 8.

In the thrust dynamic pressure bearing, the thrust plate 6 is sandwiched between the upper end 38 and the lower end face 42 of the thrust cover 7 and between the lower end face 39 of the thrust plate 6 and the upper end face 43 of the hanging part 29 ( That is, the dynamic pressure generating portion) is filled with oil. Particularly in the case of thrust dynamic pressure bearings, the gap between the dynamic pressure bearings changes due to the load of the rotor hub 3 as the motor rotates and stops. Moreover, the amount of oil held in the central portion of the dynamic pressure generating portion (where the dynamic pressure generating groove is provided) changes between when the dynamic pressure is generated by rotation and when the rotation is stopped. Therefore, the oil that cannot be retained in the dynamic pressure generation section
Dynamic pressure generating part and the base side of the thrust plate 6 (shaft 2
Side), that is, in the gap 75 between the arcuate portion 70 of the thrust cover 7 and the upper end surface 38 of the thrust plate 6.

The gap 75 increases inward in the radial direction, and is provided so that the amount of oil retained by the capillary phenomenon is balanced at a predetermined portion. That is, since the gap 75 continuously changes in accordance with the amount of oil, a desired amount of oil is maintained. Then, the oil amount can be smoothly moved with respect to the fluctuation and movement of the oil amount. For this reason, oil is prevented from leaking to the outside of the motor, that is, to the upper side in the figure. In addition, oil leakage is further prevented by the labyrinth seal configuration in which the space is formed in the key shape between the thrust cover 7 and the shaft 2 by the hole portion 62. On the other hand, on the lower side of the thrust plate 6 when the motor rotation is stopped, the gap with the upper end surface 43 of the sleeve 8 becomes large, and in addition to being held in this gap itself, it is also held in the groove 76.

An annular gap (annular space) 73 is provided on the outer peripheral end side of the thrust plate 6, and the oil retained on the upper and lower end surfaces of the thrust plate 6 is provided on the outer peripheral portion 32.
Are separated from each other and are communicated with the gaps 73, respectively. The gap 73 communicates with the outside air through the hole 20. Therefore, the dynamic pressure generating portions, which are oil holding portions, have substantially the same pressure as the outside air of the motor, and the atmospheric pressure difference is eliminated. Therefore, the oil does not include bubbles and the like, and the oil is not pushed out and moved due to the temperature rise of the motor. That is, oil leakage is prevented. Bubbles contained in the oil are defoamed in the gap 73. A V-shaped groove 33 is formed on the outer peripheral portion 32 of the thrust plate 6, and an oil repellent agent that repels oil is applied to this portion, so that the oil retained on the upper side of the thrust plate moves downward. Is prevented. In addition to the fact that the oil repellent is applied easily, the V-shaped structure is provided on both end surfaces 38, 39 (of the thrust plate 6) of the outer peripheral portion 32.
It is to prevent the movement and leakage of oil by making the surface angle with respect to.

If the impact load or the centrifugal force is applied from the outside of the motor, the oil on the upper end surface 38 side of the thrust plate 6 is
When it falls into the lower gap 73, the bottom surface 72 of the sleeve 8
Accepted by. Since the hole 20 is raised (raised portion 74), it is prevented that the hole 20 gets over the hole and leaks to the outside of the motor. And, as shown in the figure,
The hole 20 communicates with the inside of the motor (on the side of the stator 4), and vents to the outside of the motor through the space between the hub 9 and the housing 1. A portion corresponding to an outlet from the inside of the motor to the outside of the motor, that is, the flange portion 12 of the hub 9 and the step portion 77 of the housing 1.
Is a labyrinth seal structure that faces each other with a minute gap in the radial direction. For this reason, the leakage of oil is further prevented even at this portion. That is, since the hole 20 communicates with the inside of the motor, even if the oil leaks from the hole 20, the oil has a labyrinth seal structure,
Doubly prevented from leaking. Therefore, clean air in the disc chamber is not polluted. The oil that has accumulated on the bottom surface 72 is easily collected by the dynamic pressure generation unit (both upper and lower sides) due to the rotation of the motor, the change in posture, and the like. Therefore, oil depletion can be prevented, reliability can be secured, and highly accurate bearing support can be realized. In order to collect the oil scattered and accumulated in the gap 73, the bottom surface 72 is
The lower end surface 80 and the upper and lower end surfaces 38 and 39 (of the thrust plate 6) are formed to extend in a plane shape in the radial direction. Although not shown in the figure, for example, by providing a stepped structure in which the bottom surface 72 (which is the direction of gravity's action) is slightly projected toward the gap 73 side (upward in the drawing), the recoverability of oil is further improved. It goes without saying that you can do it.

The inner diameter of the hole 20 is preferably as small as possible. However, in consideration of workability, the inner diameter of the hole 20 is about 0.3 mm in this embodiment. The height of the raised portion 74 from the bottom surface 72 is preferably as high (long) as possible, but similarly, in the present embodiment, it is 1 to 2.
It is formed in mm. The oil splashed and dropped into the gap 73 under the impact load and centrifugal force is
The lower end surface 80 of the thrust cover 7 and the inner peripheral wall 7 of the peripheral wall 48
1 and the bottom surface 72 of the base portion 21 of the sleeve 8 and the like, but by applying an oil repellent agent that repels oil to the inner wall surfaces, the bottom surface 72 (which is the direction of gravity)
Easily gather and stay. That is, the friction of the oil with respect to the inner wall surface is reduced, and the oil tends to stay in a spherical shape. Therefore, the oil on the bottom surface 72 is easily collected in the upper and lower dynamic pressure generating portions due to the rotation of the motor, the change in posture, and the like.

The raised portion 74 of the hole 20 shown in FIGS. 1 and 2.
3 has a tubular shape (cylindrical shape) as shown in FIG. 3, but may have a substantially conical shape as shown in FIG. 4A (second embodiment). In the case of the second embodiment, the hole portion 20 has a cylindrical inner peripheral surface, and the raised portion 78 is formed as shown in the figure, so that in addition to the same effect as the first embodiment, a more oil repellent agent is obtained. Can be easily applied (to the raised portion 78). Further, as shown in FIG. 5 (third embodiment), the raised portion 79 may be formed in an annular shape. In this case, since the raised portion 79 serves as an annular wall, it is more difficult for oil to run onto the hole 20 and leakage prevention is enhanced for a relatively large amount of oil that has dropped into the gap 73. Further, as shown in FIG. 6 (fourth embodiment), a ridge 82 is formed by a cylindrical member (cylindrical member) 81 having a hole 20.
May be formed. In this case, since the cylindrical member 81 is fitted and fixed to the sleeve 8, the labor of working and assembling the sleeve 8 can be saved, and the productivity can be improved.

Next, FIG. 7 shows a modified example of the spindle motor shown in FIGS. 1 and 2 as a fifth embodiment, and is an enlarged sectional view of the thrust plate 85 and thrust cover 86. Is. The parts other than those shown in the drawing are the same as the structures already shown, and therefore omitted. In FIG. 7, differently from FIG. 1 (FIG. 2), the outer peripheral portion of the thrust cover 86 has a shape bent to the inside of the motor (the lower side of the drawing). Therefore, in the embodiment shown in FIG. 7, the thrust cover 86 is fixed to the sleeve 94 side by the annular wall 90 forming the outer peripheral portion. For this reason, the gap 88 formed on the outer peripheral end side of the thrust plate 85 is formed in the lower end wall 8 of the thrust cover 86.
3, the inner peripheral wall 89 of the annular wall 90, and the bottom wall 84 of the sleeve base 87. An oil repellent agent that repels oil is applied to the inner wall of the gap 88. Further, the bottom wall 84 is provided with a hole portion 93 that communicates with the outside of the motor, and the hole portion 93 has the same configuration as that shown in FIG.
The cylindrical member 92 is fitted and fixed to the base 87.

The cylindrical member 92 is made of an aluminum alloy pipe and is fitted to the base portion 87. As a result, the raised portion 91 is provided in the gap 88 to prevent leakage of oil inside and eliminate the pressure difference. Other than that, it has the same effects as those of the embodiment already described. In the spindle motor shown in FIG. 7, the hole 93 is
It goes without saying that the configurations shown in FIGS. 3 to 5 can be adopted.

Next, FIG. 8 shows a spindle motor as still another embodiment (sixth embodiment), and shows enlarged portions of the thrust plate 95 and the thrust cover 96. 8A is a cross-sectional view of FIG.
(B) is a plan view. That is, xx ′ of (b) is (a)
Represents a cross section of. The embodiment shown in FIG. 8 has the same basic configuration as that of the first embodiment shown in FIGS. 1 and 2, but differs in the following points. That is, of the inner walls that form the gap 97, the inner peripheral wall 98 (of the sleeve 99) that faces the outer peripheral end side of the thrust plate 95 in the radial direction is provided with a large number of uneven portions 100 in the circumferential direction. Is. The uneven portion 100 is provided on the inner peripheral wall 98 over the entire circumference.

When the use posture of the motor is maintained in an unspecified direction of up, down, left and right, or when a shock load or a centrifugal force is applied from the outside of the motor, the dynamic pressure generating units 102 and 103 cannot hold the motor. The oil flows out into the void 97. However, the oil can be captured by the uneven portion 100 as the rotor rotates. As a result, the dynamic pressure generators 102 and 103 can easily collect the oil. The uneven portion 100 may be provided inside the gap 97, but as is apparent from the drawing, the thrust plate 9
5, it is most desirable to provide it on the outer peripheral end side, that is, on the centrifugal force acting direction of the rotor, since scattered oil can be captured efficiently and is collected in the dynamic pressure generating portion. The concave-convex portion 100 is formed in a substantially rectangular shape having a depth of about 1 mm in the radial direction and a width of about 3 mm in the circumferential direction, but the depth and width of the groove are arbitrary depending on the rotational speed of the rotor, the viscosity of oil, and the like. Can be set to. It should be noted that by applying an oil repellent agent that repels oil to each inner wall forming the gap 97, it is possible to further improve the collectability of oil.
Further, as shown in the figure, the void 97 is provided with a raised portion 104 and a hole portion 100 communicating with the outside.

Further, the uneven portion is shown in FIGS. 9 (a) and 9 (b).
It can also be configured in a shape as shown in. FIG.
9A is an enlarged plan view similar to FIG. 8B, and FIG.
Then, the concavo-convex portion 105 has a triangular shape (seventh embodiment),
Further, in FIG. 9B, the uneven portion 106 has an arc shape (eighth embodiment). All are formed intermittently or continuously in the circumferential direction over the entire circumference. Thus, the uneven portion 1
With 05 and 106, it is possible to easily collect the oil in the dynamic pressure generating portion, and it is possible to prevent the oil from being depleted due to leakage. In addition, the uneven portion 100 shown in FIGS.
105 and 106 can also be applied to the spindle motor configured as shown in FIG. 7.

Although various embodiments of the spindle motor of the present invention have been described above, any design changes or modifications can be made without departing from the spirit of the present invention. That is, the various partial structures shown in the present embodiment can be used in combination, and the form and quantity of the dynamic pressure groove of the dynamic pressure bearing can be freely selected.

[0034]

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 upper and lower end surfaces 38, 39 of the thrust plate 6 for axially regulating the rotor hub 3 to support the dynamic pressure bearing are separately filled with oil. There is. These communicate with the gap 73 formed on the thrust plate outer peripheral portion 32 side. A hole portion 20 having a raised portion 74 is formed in the space 73, and the hole portion 20 communicates with the outside. Therefore, the air pressure difference between the inside and outside of the motor is eliminated, the oil does not move by pushing out the oil due to the temperature rise of the motor, etc., and the bubbles are also defoamed,
Therefore, leakage of oil is prevented. If the oil drops in the gap 73, the hole 20 is raised,
The oil does not leak beyond the motor and leaks to the outside of the motor, and the oil retained in the gap 73 is easily recovered to the original dynamic pressure generating portion. Thus, a spindle motor having a highly accurate and stable dynamic pressure bearing can be obtained. The hole 20 is provided so as to communicate with the inside of the motor and to ventilate through the inside of the motor to the outside of the motor. For this reason, oil leakage is double-prevented, leakage to the outside of the motor is prevented, the disk chamber that is rotationally driven is not contaminated, and therefore a highly reliable spindle motor can be realized.

By fitting and fixing the above-mentioned raised portions 82 and 91 with the cylindrical (cylindrical) members 81 and 92, it is possible to easily provide the holes 20 and 93 for communicating the inside and outside of the motor. It is possible to improve the sex. And the gap 73,
By applying an oil repellent agent that repels oil to the inner walls forming 88 and 97, the frictional resistance of the oil to the inner walls is reduced, and it is easier to collect the oil in the dynamic pressure generating portion. Further, the uneven portions 100, 10 are formed on the inner peripheral wall 98 that faces the outer peripheral end side of the thrust plate 95 in the radial direction.
By forming 5, 106, the oil can be collected in the dynamic pressure generating portion regardless of the attitude of the motor and the acting force such as the centrifugal force, so that the oil can be prevented from being depleted and the reliability can be further improved. A spindle motor that can be achieved can be obtained.

[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 cross-sectional view of an essential part showing a part of the spindle motor in FIG.

3 is a partially enlarged perspective view of the spindle motor shown in FIG.

FIG. 4 is a partially enlarged perspective view of a spindle motor according to a second embodiment of the present invention.

FIG. 5 is a partially enlarged perspective view of a spindle motor according to a third embodiment of the present invention.

FIG. 6 is a partially enlarged perspective view of a spindle motor according to a fourth embodiment of the present invention.

FIG. 7 is an enlarged cross-sectional view of a main part of a spindle motor according to a fifth embodiment of the present invention.

FIG. 8 shows a spindle motor according to a sixth embodiment of the present invention, in which (a) is an enlarged cross-sectional view of a main part and (b) is a plan view thereof.

FIG. 9 is an enlarged plan view of the essential parts showing the seventh and eighth embodiments of the present invention.

[Explanation of symbols]

 1 Housing 2 Shaft 3 Rotor Hub 4 Stator 5 Rotor Magnet 6,85,95 Thrust Plate 7,86,96 Thrust Cover 10 Flexible Circuit Board 20,93,100 Hole

Claims (6)

[Claims] 1. A housing, a shaft member fixed to the housing, a rotor hub relatively rotatable with respect to the shaft member, and a hydrodynamic fluid interposed between the shaft member and the rotor hub. In the spindle motor including a bearing means, the shaft member is provided with a thrust plate that projects outward in the radial direction, and the rotor hub includes a sleeve rotatably supported by the shaft member and the thrust plate. A thrust cover that covers the plate, a radial bearing portion is provided between the sleeve and the shaft member, an end portion of the sleeve and the thrust plate, and a thrust cover and the thrust plate. Thrust bearing portions are provided on the outer peripheral side of the thrust plate and the sleeve and the thrust cover, respectively. Is provided in the annular space, and a communication hole for making the pressure in the annular space substantially equal to the pressure outside the motor is provided in the annular space, and the communication hole has an opening in the annular space. The spindle motor according to claim 1, wherein the opening projects inward from an inner surface defining the annular space. 2. The spindle motor according to claim 1, wherein the communication hole communicates with the inside of the motor. 3. The sleeve is fitted with a tubular member for communicating the annular space with the inside of the motor, and an end portion of the tubular member projects into the annular space. Spindle motor. 4. The spindle motor according to claim 1, wherein an oil repellent agent that repels the fluid lubricant of the thrust bearing portion is applied to the surfaces of the sleeve and the thrust cover that define the annular space. 5. The spindle motor according to claim 1, wherein the surface defining the outer peripheral surface of the annular space is provided with a plurality of uneven portions at intervals in the circumferential direction. 6. The spindle motor according to claim 5, wherein the plurality of uneven portions are provided on the sleeve.