JPH09329137A - Ball bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball bearing device which can lessen the deflection of nonsynchronous revolution speed component of a spindle motor by restraining the transmission of vibration to a member for fixing a ball bearing. SOLUTION: An outer ring 6 is fixed to a hub 4 being an outer ring fixing member, and an inner ring 7 is fixed to a shaft member 3 being an inner ring fixing member, and a section which is the same in an axial position as the outer ring track 11 of the outer diametral face of the outer ring 6 is composed so as to come into contact with fluid. Since the deflection of nonsynchronous revolution speed component clue to ball passing vibration generated in the case where a ball 8 rolls at high speed inside the outer ring track 11 is absorbed by the deformation of the outer ring 6, the above deflection is not transmitted to the hub 4 as it is.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device used for video, audio, information equipment and other precision rotating equipment such as a magnetic disk drive and an optical disk drive.
In particular, the present invention relates to a ball bearing device suitable for a disk driving spindle motor.

[0002]

2. Description of the Related Art As a conventional ball bearing device of this type, for example, there is one which is incorporated in a spindle motor of a magnetic disk device as shown in FIG. A shaft member 3 fixedly mounted on a motor base 2 and a hub 4 on which a magnetic disk (not shown) is mounted and which is driven to rotate by a rotation drive motor M are axially separated from each other by two members. Ball bearings 5 and 5 are provided. In each ball bearing 5, the outer ring 6 is closely fixed to the inner surface of the hub 4 by means such as press fitting or adhesion, and the inner ring 7 is closely fixed to the outer surface of the shaft member 3 by means such as press fitting or adhesion. The shaft member 3 is configured as an inner ring fixing member and the hub 4 is configured as an outer ring fixing member.

[0003] In a magnetic disk device or the like in which such a bearing device is incorporated, recently, the recording density has been further increased, and a demand for improving the positioning accuracy of a magnetic head and the like has been increasing. . Along with this, it is strongly required that the non-rotational speed synchronous component has a small fluctuation with respect to the spindle motor. Therefore, the ball bearing 5 incorporated in the spindle motor necessarily has a small non-rotational frequency synchronous component fluctuation. Is required. Therefore, each member that constitutes the ball bearing also needs high processing accuracy.

[0004]

However, the ball bearing is, in the first place, a passage vibration of a ball which is a rolling element in the bearing itself,
It has an essential vibration based on the spring characteristics of the bearing, and therefore it is difficult to reduce the runout of the non-rotational speed synchronous component to zero, no matter how much the machining accuracy is improved. However, in the conventional ball bearing device, the outer ring 6 is on the inner surface of the hub 4 which is the outer ring fixing member, and the inner ring 7 is the shaft member 3 which is the inner ring fixing member.
In addition, since all of them have a structure in which they are closely attached and fixed by means such as press-fitting or adhesion, the vibration of the non-rotation speed synchronizing component such as ball passing vibration is directly transmitted to the shaft member 3 and the hub 4, and the spindle motor 3 There was a problem that the rotation accuracy was reduced.

[0005] The vibration generated in the ball bearing 5 vibrates the magnetic disk mounted on the hub 4 of the spindle motor to make the rotation of the magnetic disk unstable, or from the shaft member 3 through the motor base 2. There is also a problem that the swing arm is vibrated by being transmitted to the base of the HDD drive device, thereby deteriorating the positioning accuracy of the magnetic head.

Therefore, the present invention has been made by paying attention to the problems of such a conventional ball bearing device, and suppresses the transmission of vibration to a member for fixing the ball bearing, and is applied to, for example, a spindle motor. It is an object of the present invention to provide a ball bearing device that can reduce the swing of the non-rotation speed synchronizing component.

[0007]

To achieve the above object, in a ball bearing device according to claim 1 of the present invention, in a ball bearing, an outer ring is fixed to an outer ring fixing member and an inner ring is fixed to an inner ring fixing member. Further, at least one of a portion having the same axial position as the outer ring raceway of the outer diameter surface of the outer ring and a portion having the same axial direction position as the inner ring raceway of the inner diameter surface of the inner ring is in contact with the fluid.

Further, in the ball bearing device according to the second aspect of the present invention, in the ball bearing, the outer ring is fitted and fixed to the sleeve, the inner ring is fixed to the inner ring fixing member, and the sleeve is fixed to the outer ring fixing member. A portion of the outer diameter surface of the sleeve having the same axial position as the outer ring raceway is in contact with the fluid.

According to the ball bearing device of the first aspect of the present invention, either or both of the outer diameter surface of the outer ring and the inner diameter surface of the inner ring are entirely formed on the outer ring fixing member or the inner ring fixing member as in the conventional case. Since it is in close contact with the fluid and is in contact with the fluid at the axial position corresponding to the orbital position, it is possible to slightly deform the axial position corresponding to the orbital position.
The shake of the non-rotation speed synchronizing component such as the ball passing vibration is absorbed by the slight deformation of the outer ring or the inner ring due to the shake, and is not transmitted to the outer ring fixing member or the inner ring fixing member. Therefore, when the ball bearing device according to claim 1 of the present invention is used for a spindle motor, the swing of the non-rotation speed synchronizing component of the spindle motor is reduced, and as a result, the magnetic disk and the swing arm are not vibrated and the magnetic field is reduced. Improves head positioning accuracy.

Further, according to the ball bearing device of the second aspect of the present invention, the outer diameter surface of the outer ring is fixed to the outer ring fixing member via the sleeve, and the outer diameter surface of the sleeve corresponds to the raceway position of the outer ring. Since the axial position that contacts the fluid is in contact with the fluid, the sleeve can be slightly deformed in the axial position that corresponds to the raceway position of the outer ring. Also, it is absorbed by the slight deformation of the sleeve and is not transmitted to the outer ring fixing member. for that reason,
When the ball bearing device according to the second aspect of the present invention is used for a spindle motor, the non-rotation speed synchronizing component of the hub, which is the outer ring fixing member of the spindle motor, has less swing, and the rotation accuracy of the spindle motor is improved.

Here, the outer ring fixing member may be a hub of a spindle motor. Further, the inner ring fixing member may be a shaft member of a spindle motor. Further, at least one of the outer diameter surface of the outer ring and the inner diameter surface of the inner ring has an annular groove in a portion where the track and the axial position are the same,
The annular groove may be in contact with the fluid.

Further, a portion where the outer diameter surface of the sleeve has the same axial position as the outer ring raceway has an annular groove, and the sleeve may be in contact with the fluid in the annular groove.

Further, at least one of the inner diameter surface of the outer ring fixing member to which the outer ring is fixed and the outer diameter surface of the inner ring fixing member to which the inner ring is fixed has an annular groove in a portion where the axial position is the same as the track. At least one of the outer diameter surface of the outer ring and the inner diameter surface of the inner ring may be in contact with the fluid in the annular groove.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. In each figure, the same or corresponding parts as in the conventional case are designated by the same reference numerals.

FIG. 1 is a sectional view of a first embodiment of a ball bearing device of the present invention. In this embodiment, the ball bearing device according to the present invention is assembled on an actual HDD spindle motor in a shaft-fixed manner. First, the configuration will be described. The spindle motor shaft member 3 is fixed to the motor base 2 concentrically. The shaft 4 is erected upright, and the hub 4 is rotatably attached to the shaft member 3 at two upper and lower positions via deep groove ball bearings 5. Ball bearing 5
The outer ring 6 having the annular groove 14 on the outer diameter surface is fixed to the inner surface of the hub 4, and the inner ring 7 is fixed to the outer diameter surface of the shaft member 3, whereby the hub 4 constitutes an outer ring fixing member. At the same time, the shaft member 3 constitutes an inner ring fixing member. An outer ring raceway 11 is formed on the inner diameter surface of the outer ring 6 and an inner ring raceway 12 is formed on the outer diameter surface of the inner ring 7 at intermediate positions in the axial direction. A plurality of balls 8 are inserted. A shield or seal member 13 for preventing leakage of a lubricating fluid such as grease filled in the ball bearing 5 is attached to both end surfaces of the outer ring 6 or the inner ring 7.

The state of fixing the outer ring 6 and the inner ring 7 will be described in more detail. With respect to the inner ring 7, the inner diameter surface of the inner ring 7 is completely adhered to the outer diameter surface of the shaft member 3 by means such as press fitting or adhesion. It is fixed. On the other hand, in the outer ring 6, the annular groove 14 is formed in a portion of the outer diameter surface of which the axial position is the same as that of the outer ring raceway 11 (in the figure, an intermediate position in the axial direction). Only the outer diameter surface of the outer ring excluding the groove 14 is fixed to the inner diameter surface of the hub 4 by press fitting or adhesion. The annular groove 14 may be previously filled with a lubricating fluid such as lubricating oil or grease. Further, it may be an empty state in which those fluids are not filled, and in that case, it can be said that air, which is a fluid, exists in the annular groove 14. In other words, in the case of this embodiment, the portion of the outer diameter surface of the outer ring 6 at the same axial position as the outer ring raceway 11 is the annular groove 14 and is in constant contact with the fluid (air, lubricating oil, grease, etc.). It is fixed to the inner surface of the hub 4.

In this way, a screw hole 16 is formed in the upper surface of the hub 4 rotatably supported by the shaft member 3 via the ball bearing 5, and a magnetic disk (not shown) is mounted and screwed. There is. An annular recess 17 is provided on the lower surface of the hub 4, and a rotor (magnet) 18 is fixed to the inner diameter surface of the annular recess 17 and is formed so as to project into the annular recess 17. The stator 1 is arranged on the outer peripheral surface of the annular protrusion 2a of the motor base 2 facing the rotor 18 in the radial direction with an air gap.
9 is fixed and the rotary drive motor M is comprised.

Next, the operation of this embodiment will be described. When the coil of the stator 19 of the rotary drive motor M is energized, the hub 4 is driven. The hub 4 rotates around the shaft member 3 through rolling of the balls 8 of the ball bearing 5, and a magnetic disk (not shown) mounted on the hub 4 is rotationally driven synchronously. In this case, the ball bearing 5 rolls along the outer ring raceway 11 while the balls 8 are pressed against the outer ring 6 by the centrifugal force. The outer ring 6 is shaken by a non-rotational speed synchronizing component such as ball passing vibration when the ball 8 rolls in the outer ring raceway 11 at high speed, and essential vibration caused by the spring characteristics of the ball bearing 5. However, since the outer ring 6 is in contact with the fluid in the annular groove 14 at the position equal to the axial position of the outer ring raceway 11, the outer ring 6 can be slightly deformed, and the vibration of the outer ring 6 is absorbed by the deformation of the outer ring 6. It is prevented from being transmitted to the hub 4 as it is. Therefore, the ball bearing 5
The spindle motor provided with is effective in improving the rotation accuracy.

Further, since the fluid is present in the annular groove 14 and the vibration is absorbed by the deformation of the outer ring 6, the ball passing vibration generated in the outer ring 6 is mounted on the outer ring 6 via the hub 4. It is possible to suppress the vibration of the magnetic disk and the vibration of the swing arm transmitted through the base of the HDD drive device, thereby ensuring the stable rotation of the magnetic disk and improving the positioning accuracy of the magnetic head. .

When the annular groove 14 functions as a sealed damper, the lubricating oil, grease, etc., as the fluid in the annular groove 14 is more effective than that in the case of air, and a more remarkable vibration damping effect is obtained.

FIG. 2 is a sectional view of a second embodiment of the ball bearing device of the present invention. In the ball bearing device of this embodiment, a sleeve 21 is interposed between the outer ring 6 of the deep groove ball bearings 5 and 5 mounted on the shaft member 3 at two positions above and below and the inner surface of the hub 4, and the outside of the sleeve. It is different from the first embodiment in that the annular groove 22 is provided on the radial surface. That is, the outer ring 6 of this embodiment is fitted and closely fixed to the inner surface of the sleeve 21, and the sleeve 21 has an outer diameter surface excluding the annular groove 22 formed on the outer diameter surface thereof. It is fixed in close contact with the above by means such as press fitting or adhesion.
In the same manner as described above, the annular groove 22 of the sleeve 21 is filled with a lubricating fluid such as lubricating oil or grease in advance, or air is allowed to exist. Also in this embodiment, the hub 4 constitutes the outer ring fixing member and the shaft member 3
Constitutes the inner ring fixing member.

In the figure, the annular groove 22 of the sleeve 21 extends from the deep groove ball bearing 5 arranged at the upper part of the shaft member 3 to the deep groove ball bearing 5 arranged at the lower part of the shaft member 3 and has a wide groove width. As a result, the portions of the outer diameter surface of the sleeve 21 at the same axial position as the outer ring raceway 11 are in contact with the fluid in the annular groove 22, respectively. However, the annular groove 22 of the sleeve 21 may be formed in two locations on the outer diameter surface of the sleeve 21 so as to correspond to the two deep groove ball bearings 5, 5, and in that case, the outer diameter of the sleeve 21 Portions having the same axial position as the outer ring raceway 11 on the surface come into contact with the fluid in the annular groove. Alternatively, the sleeve 21 having the annular groove 22 may be divided into two pieces, and the sleeve 21 may be provided for each ball bearing 5. The sleeve 21
If the number is one, the shaft member 3, the two ball bearings 5 and the sleeve 21 can be assembled in advance and unitized and transferred, and the motor can be easily assembled.

Other constitutions and effects are the same as those of the first embodiment.
It is similar to the embodiment. FIG. 3 is a sectional view of a third embodiment of the bearing device of the present invention. This embodiment is an example in which one of the two sets of bearing devices for rotatably supporting the hub 4 of the spindle motor is the ball bearing device 1C of the present invention and the other is the hydrodynamic bearing 25. The ball bearing device 1C is arranged below the shaft member 3 which is fixedly installed on the base 2 of the spindle motor, and the hydrodynamic bearing 25 is arranged above the shaft member 3.

The deep groove ball bearing 5 of this ball bearing device 1C is
The ball bearing device shown in each of the above embodiments is different in that annular grooves 14 are provided on both the outer diameter surface of the outer ring 6 and the inner diameter surface of the inner ring 7. And the outer ring 6 is
The outer diameter surface of the outer ring 6 excluding the annular groove 14 formed at the same axial position as the outer diameter raceway 11 of the outer diameter surface of the outer ring 6 is brought into close contact with the inner diameter surface of the hub 4 by means such as press fitting or adhesion. It is fixed. On the other hand, for the inner ring 7, the inner diameter surface of the inner ring 7 is pressed into the outer diameter surface of the shaft member 3 or the inner diameter surface of the inner ring 7 excluding the annular groove 14 formed at the same axial position as the inner ring raceway 12 of the inner ring 7. It is fixed by adhering it by means such as adhesion. Each annular groove 14 is filled with a fluid 15 such as lubricating oil, grease or air. Also in this embodiment, the hub 4 constitutes an outer race fixing member and the shaft member 3 constitutes an inner race fixing member.

In the hydrodynamic bearing 25, the shaft outer peripheral surface near the upper end of the shaft member 3 is a radial outer peripheral surface 26, and the sleeve member 2 opposed to the radial outer peripheral surface 26 with a radial bearing gap 27.
The inner peripheral surface of 8 serves as a radial bearing surface 29, and either or both of the radial bearing surface 29 and the radial outer peripheral surface 26 have, for example, a herringbone-shaped groove 3 for generating dynamic pressure.
0 is formed, and lubricating fluid such as lubricating oil, grease, magnetic fluid, etc. is present in the bearing gap 27 and is lubricated. The sleeve member 28 is integrally fixed to the inner surface of the hub 4.

In the case of this ball bearing device 1C, since the outer groove 6 of the deep groove ball bearing 5 and the inner diameter surface of the inner ring 7 are provided with the annular grooves 14, respectively, the outer ring raceway 11 and the inner ring raceway 12 are formed. The runout of the non-revolution speed synchronizing component of the outer ring 6 or the inner ring 7 due to the passing vibration of the rolling balls 8 causes the outer ring 6 or the inner ring 7 to swing.
Since it is absorbed by the slight deformation, the non-rotation speed synchronizing component of the deep groove ball bearing 5 is not transmitted to the hub 4 and the shaft member 3. On the other hand, the hydrodynamic bearing 25 arranged above the spindle motor does not have a non-rotation speed synchronizing component even if it is a non-contact type bearing. Therefore, it is possible to provide a spindle motor having high rotation accuracy and high positioning accuracy.

FIG. 4 is a sectional view of a fourth embodiment of the bearing device of the present invention. Also in this embodiment, as in the case of the third embodiment, the lower one of the two sets of bearing devices that support the hub 4 of the spindle motor is the ball bearing device 1D of the present invention, and the other is the hydrodynamic fluid. This is an example of the bearing 25.
However, this is different from the case of the third embodiment in that one end (upper end) side of the shaft member 3 is of a shaft rotation type integrally fixed to the hub 4.

A sleeve portion 32 through which the shaft member 3 is passed is integrally erected on the base 2 of the spindle motor. At the lower end of the inner surface of the sleeve portion 32 of the base, the bearing mounting recess 33
Is formed, and the annular groove 14 is formed on the inner peripheral surface thereof. The ball bearing device 1 is provided on the inner peripheral surface of the recess 33.
The outer diameter surface of the outer ring 6 of the deep groove ball bearing 5 constituting D is closely fixed by means such as press fitting or adhesion, and the recess 3
The annular groove 14 provided on the inner peripheral surface of No. 3 is at the same axial position as the outer ring raceway 11. Further, in this embodiment, the annular groove 14 is also formed on the outer diameter surface of the rotating shaft member 3 on the lower end side. Then, the inner diameter surface of the inner ring 7 of the deep groove ball bearing 5 is closely fixed to the outer diameter surface of the shaft member 3 by means such as press fitting or adhesion, and the annular groove 14 provided in the shaft member 3 is It is in the same axial position as track 12. In the case of this embodiment, the motor base 2 constitutes an outer ring fixing member, and the shaft member 3 constitutes an inner ring fixing member.

In the hydrodynamic bearing 25, the shaft outer peripheral surface in the vicinity of the hub mounting end of the shaft member 3 is a radial outer peripheral surface 26, and the sleeve portion 3 opposed to the radial outer peripheral surface 26 with a radial bearing gap 27.
The inner peripheral surface of 2 is a radial bearing surface 29, and a groove 30 for generating a dynamic pressure, such as a spiral shape, is formed on either or both of the radial bearing surface 29 and the radial outer peripheral surface 26, and lubrication is performed. Lubricating fluid such as oil, grease and magnetic fluid exists in the bearing gap 27 and is lubricated.

The stator 19 of the rotary drive motor M in this embodiment is fixed to the outer surface of the sleeve portion 32 of the base. The operation and effect of the ball bearing device 1D having the above configuration is the same as that of the third embodiment.

FIG. 5 is a sectional view of a fifth embodiment of the ball bearing device of the present invention. This embodiment is an example in which the ball bearing device 1F of the present invention is applied to a spindle motor that supports a hub 4 by providing a hydrodynamic bearing on the inner circumference of the ball bearing device. That is, the outer diameter surface of the sleeve 35 is closely adhered and fixed to the inner diameter surface of the inner ring 7 of the ball bearing device 1F to be integrated, and the inner diameter surface of the sleeve 35 serves as the radial bearing surface 29 and the groove 30 for generating dynamic pressure 30. And a flange portion 35f provided on the upper end of the sleeve is fixed to the hub 4 as a rotating member with a screw 36. The radial outer peripheral surface 26 of the shaft member 3, which is a fixing member erected on the motor base 2 through the radial bearing gap 27, faces the radial bearing surface 29 of the sleeve 35, and the hydrodynamic bearing 25 is secured. I am configuring.

An annular groove 14 is provided in a portion of the outer diameter surface of the outer ring 6 of the ball bearing device 1F at the same axial position as the outer ring raceway 11. The outer ring outer diameter surface excluding the annular groove 14 is the motor base. The outer ring 6 is fixed to the motor base 2 by being brought into close contact with the inner peripheral surface of the base 2 by means such as press fitting or adhesion. In the case of this embodiment, the motor base 2 constitutes an outer ring fixing member, the hub 4 constitutes an inner ring fixing member, and the outer ring 6 is fixed to the shaft member 3 via the outer ring fixing member. A portion of the outer diameter surface of the outer ring 6 at the same axial position as the outer ring raceway 11 is an annular groove 14 that is in contact with a fluid (air in this case).

The preload of the ball bearing device 1F is a magnetic attraction acting between a preload applying magnet 37 attached to the inner surface of the hub 4 so as to face the end surface of the shaft member 3 and the shaft member 3 made of a ferromagnetic material. I try to give it by force.

A stator 19 of a rotary drive motor M for driving the hub 4 is fixed to the motor base 2, and a rotor (magnet) 18 arranged to face the motor base 2 in the radial direction with an air gap in between is provided with a back yoke 20 in between. It is fixed to the inner surface of the hub 4. A magnetic disk D is mounted on the outer surface of the hub 4 via a mounting member 38.

In this ball bearing device 1F, the shape of the outer ring 6 is not a simple cylindrical shape as in the case of the deep groove ball bearing 5, but is a sheet metal shape and has a complicated curved shape rich in elasticity. By making the outer ring 6 thin as described above, it is possible to freely set the spring constant for the slight deformation of the outer ring 6 due to the vibration of the non-rotation speed synchronizing component of the outer ring 6 due to the passing vibration when passing the ball, and the like. There is an advantage of exerting further vibration absorbing ability.

If a four-point contact ball bearing is used in the ball bearing device 1F, the moment rigidity can be obtained by the four-point contact ball bearing alone, which has the advantage of improving the moment rigidity of the entire bearing device. Further, when a four-point contact ball bearing is used, a preload is applied inside the bearing with the bearing clearance as a negative clearance, and therefore the magnet 3 for applying a preload to the ball bearing is used.
There is also an advantage that 7 can be omitted. Even if a four-point contact ball bearing having a negative clearance is used, the outer race 6 can be freely deformed according to the clearance because the annular groove 14 is provided on the outer diameter surface of the outer race. , Ball 8 and outer ring raceway 11
It is possible to eliminate the disadvantage that the surface pressure between the two becomes too large.

FIG. 6 is a sectional view of a sixth embodiment of the ball bearing device of the present invention. This embodiment is an example in which the ball bearing device 1G of the present invention is applied to a spindle motor (however, a shaft rotation type) in which a dynamic pressure bearing is arranged on the inner circumference of the ball bearing as in the fifth embodiment. . In this ball bearing device 1G, the inner ring 7 is made longer than the outer ring 6, and a portion of the inner diameter surface of the inner ring 7 having the same axial position as the inner ring raceway 12 is in contact with the fluid in the bearing clearance 27. The inner ring 7 has a structure in which one end (lower end) of the inner ring 7 is directly adhered and fixed to the motor base 2. The inner surface of the inner ring 7 is formed as a radial bearing surface 29 having a groove 30 for generating dynamic pressure.
The radial outer peripheral surface 26 of the shaft member 3 is opposed to the shaft member 3 via a shaft and constitutes a hydrodynamic bearing 25. The outer ring 6 is closely fixed to the inner diameter surface of the hub 4 by means such as press fitting or adhesion. In the case of this embodiment, the hub 4 constitutes an outer ring fixing member, and the motor base 2 constitutes an inner ring fixing member.

The axial length of the portion of the inner diameter surface of the hub 4 to which the outer ring 6 is fixed is shorter than the axial length of the outer diameter surface of the outer ring 6, whereby the outer diameter surface of the outer ring 6 is A portion having the same axial position as that of the outer ring raceway 11 is configured to come into contact with a fluid (air in this case).

One end (upper end) of the shaft member 3 is concentrically and integrally fixed to the hub 4, so that the shaft member 3, the hub 4 and the outer ring 6 rotate integrally. The preload of the ball bearing device 1G is generated by the preload applying magnet 37 installed on the upper surface of the motor base 2 facing the end surface (lower end surface) of the outer ring 6 with a gap and the outer ring 6 made of a ferromagnetic material. It is given by the magnetic attraction force that acts between.

In the ball bearing device 1G according to this embodiment, the outer ring 6 or the inner ring 7 is caused by passing vibration or the like when passing the ball.
The shake of the non-rotation speed synchronizing component of is absorbed by the slight deformation of the outer ring 6 or the inner ring 7. The magnetic disk D and the motor base 2 mounted on the hub 4 are not vibrated via the hub 4.

FIG. 7 is a sectional view of a seventh embodiment of the ball bearing device of the present invention. This embodiment is an example in which the ball bearing device 1H of the present invention is applied to a spindle motor in which the rotary drive motor M is of a plane opposed type. This ball bearing device 1H
Is provided with an annular groove 14 at the same axial position as the outer ring raceway 11 on the outer diameter surface of the outer ring 6.
The outer ring 6 is fixed to the motor base 2 by bringing the outer diameter surface of the outer ring other than 4 into close contact with the inner peripheral surface of the motor base 2 by means such as press fitting or bonding. On the other hand, the inner ring 7 is longer than the outer ring 6, and one end (upper end) of the inner ring 7 is fixed to the inner diameter surface of the hub 4. Therefore, in the case of this embodiment, the hub 4 constitutes the inner ring fixing member, and
The motor base 2 constitutes an outer ring fixing member. And
The annular groove 14 on the outer diameter surface of the outer ring 6 is in contact with the fluid. Further, a portion of the inner diameter surface of the inner ring 7 having the same axial position as the inner ring raceway 12 is in contact with the fluid in the bearing clearance 27.

An inner diameter surface of the inner ring 7 is a radial bearing surface having a groove 30 for generating a dynamic pressure, and a radial outer peripheral surface 26 of the shaft member 3 faces the radial bearing surface 27 through a radial bearing clearance 27.
The hydrodynamic bearing 25 is configured.

Rotor of the rotary drive motor M (magnet)
18 is fixedly attached to the lower surface of the hub 4 via a back yoke 20, and the stator 19 is fixed to the motor base 2 and faces the rotor (magnet) 18 in a plane via an air gap. When the rotary drive motor M is of a plane-opposing type as described above, the attraction force of the motor can be used for preloading the ball bearing device 1H, so that it is not necessary to additionally provide the preloading magnet 37, and the cost can be reduced. There is.

The axial width of the portion of the outer diameter surface of the outer ring 6 in contact with the fluid is preferably larger than the axial width of the outer ring raceway 11 to absorb the vibration of the outer ring 6, but the vibration can be absorbed even in the following cases.

Further, it is preferable for the vibration absorption of the inner ring 7 that the axial width of the portion of the inner diameter surface of the inner ring 7 which is in contact with the fluid is larger than the axial width of the inner ring raceway 12, but it is also possible to absorb the vibration below.

Further, the axial width of the portion of the outer diameter surface of the sleeve 21 which is in contact with the fluid is preferably larger than the axial width of the outer ring raceway 11 for absorbing the vibration of the outer ring 6, but the following is also possible.

In the above third to seventh embodiments, the groove 30 for generating the dynamic pressure of the hydrodynamic bearing 25 is provided on the radial bearing surface 29. It may be provided on both the radial bearing surface 29 and the radial outer peripheral surface 26. Further, the groove pattern is not limited to that of the embodiment.

When the annular groove 14 is provided on the outer diameter surface of the outer ring 6 and the inner diameter surface of the inner ring 7, the outer ring 6 and the inner ring 7 are connected to the track 1.
Since the axial positions equal to the axial positions of 1 and 12 are thin, they are easily deformed slightly and vibrations of the outer ring 6 and the inner ring 7 are easily absorbed.

[0049]

As described above, according to the first aspect of the present invention.
In the ball bearing device according to the present invention, since at least one of the outer diameter surface of the outer ring and the inner diameter surface of the inner ring is in contact with the fluid at a portion where the axial position is the same as the raceway, the non-rotation speed synchronizing component such as ball passing vibration is shaken. Is absorbed by the slight deformation of the outer ring and the inner ring, and as a result, vibration transmission to the member for fixing the ball bearing can be suppressed as much as possible.

In the ball bearing device according to the second aspect of the present invention, the outer ring is fixed to the outer ring fixing member via the sleeve,
In addition, since the portion of the outer diameter surface of the sleeve that is in the same axial position as the outer ring raceway is in contact with the fluid, the non-rotation speed synchronization component such as ball passing vibration is absorbed by the slight deformation of the outer ring and the sleeve. It is possible to suppress the vibration transmission to the outer ring fixing member as much as possible.

Further, when the ball bearing device of the present invention is applied to the bearing of the disk drive spindle motor, the non-rotational speed synchronizing component generated in the ball bearing vibrates the magnetic disk mounted on the spindle motor hub. To make the rotation of the magnetic disk unstable, and from the shaft member to the motor base to HD
The swing arm attached to the base of the D drive device is vibrated to vibrate, and it is possible to prevent problems such as deterioration of the positioning accuracy of the magnetic head.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of a spindle motor provided with a ball bearing device of the present invention.

FIG. 2 is a sectional view of a second embodiment of a spindle motor equipped with the ball bearing device of the present invention.

FIG. 3 is a cross-sectional view of a third embodiment of a spindle motor equipped with the ball bearing device of the present invention.

FIG. 4 is a cross-sectional view of a fourth embodiment of a spindle motor equipped with the ball bearing device of the present invention.

FIG. 5 is a sectional view of a fifth embodiment of a spindle motor provided with the ball bearing device of the present invention.

FIG. 6 is a sectional view of a sixth embodiment of a spindle motor equipped with the ball bearing device of the present invention.

FIG. 7 is a sectional view of a seventh embodiment of a spindle motor provided with the ball bearing device of the present invention.

FIG. 8 is a sectional view of a spindle motor including a conventional ball bearing device.

[Explanation of symbols]

 1C, 1D, 1F, 1G, 1H Ball bearing device 2 Motor base (outer ring fixing member, inner ring fixing member) 3 Shaft member (inner ring fixing member) 4 Hub (outer ring fixing member, inner ring fixing member) 5 Ball bearing 6 Outer ring 7 Inner ring 11 Outer ring raceway (bearing raceway) 12 Inner ring raceway (bearing raceway) 21 Sleeve

Claims (2)

[Claims] 1. In a ball bearing, an outer ring is fixed to an outer ring fixing member, an inner ring is fixed to an inner ring fixing member, and a portion of the outer diameter surface of the outer ring having the same axial position as the outer ring raceway and an inner diameter surface of the inner ring are formed. A ball bearing device, wherein at least one of the portions having the same axial position as the inner ring raceway is in contact with the fluid. 2. In a ball bearing, an outer ring is fitted and fixed to a sleeve, an inner ring is fixed to an inner ring fixing member, the sleeve is fixed to an outer ring fixing member, and an outer ring raceway and a shaft of an outer diameter surface of the sleeve are provided. A ball bearing device characterized in that the parts in the same directional position are in contact with a fluid.