JP2014152872A - Bearing apparatus and hard disk apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve positioning accuracy of a head by performing vibration insulation of a rolling bearing and improving a control frequency in a state where a swing arm is highly accurately supported by the rolling bearing.SOLUTION: A bearing apparatus 2 includes a fixing member 8, a rotary member 10 to be rotated around the fixing member 8 and one or more rolling bearings 11 for rotatably supporting the rotary member 10 on the fixing member 8. The bearing apparatus 2 further includes a fluid chamber 18 demarcated so that internal volume is changed when the fixing member 8 and the rotary member 10 are relatively moved in an axial direction and filled with viscous fluid inside thereof and a passage 19 continued to the fluid chamber 18 and allowing the viscous fluid to flow in accordance with the change of an interval volume of the fluid chamber 18.

Description

  The present invention relates to a bearing device and a hard disk device.

Conventionally, a bearing device that swingably supports a swing arm of a hard disk device has two rolling bearings arranged adjacent to each other in the axial direction, and pressurizes in a direction to bring inner rings or outer rings close to each other. It is common to apply. In the bearing device having such a structure, it is necessary to keep the swing arm control frequency lower than the resonance frequency of the bearing in order to avoid the resonance of the bearing during the operation of the swing arm. There is an inconvenience that it cannot be improved.
2. Description of the Related Art A bearing device including a vibration isolating member for preventing vibration generated in a bearing from being transmitted to a swing arm is known (for example, see Patent Document 1).

JP 2006-242292 A

  However, the bearing device of Patent Document 1 is intended to prevent vibrations by interposing a vibration isolation member between the bearing and the swing arm, and therefore does not suppress vibrations of the bearing itself. In addition, if a deformable vibration isolating member is interposed between the rolling bearing and the swing arm, there is a disadvantage that the swing arm cannot be accurately supported by the rolling bearing.

  The present invention has been made in view of the above-described circumstances, and in a state where the swing arm is supported with high precision by the rolling bearing, the vibration of the rolling bearing is improved, the control frequency is improved, and the head positioning accuracy is improved. It is an object of the present invention to provide a bearing device and a hard disk device capable of improving the above.

In order to achieve the above object, the present invention provides the following means.
One aspect of the present invention includes a fixing member, a rotating member that rotates with respect to the fixing member, and one or more rolling bearings that rotatably support the rotating member with respect to the fixing member. And the rotating member are defined so that the internal volume changes when both move relative to each other in the axial direction, and a fluid chamber filled with a viscous fluid is connected to the fluid chamber. Provided is a bearing device provided with a flow path through which a viscous fluid flows according to a change in the internal volume of a fluid chamber.

  According to this aspect, the rotating member can be accurately rotated by rotating the rotating member that is rotatably supported by the one or more rolling bearings with respect to the fixed member. In this case, when the driving frequency of the rotating member is brought close to its natural frequency, vibration including a component that causes the rotating member and the fixed member to move relative to each other in the axial direction is generated.

  When relative axial movement occurs, the internal volume of the fluid chamber changes and the viscous fluid passes through the flow path. By forming the channel sufficiently narrow, a damper effect is generated in which vibration is attenuated by viscous resistance when the viscous fluid passes through the channel. Accordingly, the rotating member can be rotatably supported with respect to the fixed member, and the occurrence of resonance can be prevented even when the driving frequency is increased.

In the said aspect, you may provide the seal | sticker part which seals the said fixing member and the said rotation member so that relative rotation is possible.
By doing in this way, even when the internal volume of the fluid chamber fluctuates due to the relative movement of the fixed member and the rotating member in the axial direction and the viscous fluid flows through the flow path, the seal portion may leak to the outside. The vibration isolation effect can be maintained for a long time.

Moreover, in the said aspect, you may provide the preload means which provides a preload to the said rolling bearing.
By doing so, the play between the ball of the rolling bearing and the race surface can be eliminated by the preload applied by the preload means, positioning accuracy can be improved, and variation in load torque during rotation can be prevented. .

Moreover, in the said aspect, it is provided with the said single rolling bearing, and the said preload means is the magnet fixed to one side of the said fixing member or the said rotation member, and the said magnet on the other side of the said fixing member or the said rotation member And a magnetic body disposed so as to face each other in the axial direction.
In this way, the fixed member and the rotating member are urged in the axial direction by a magnetic attractive force or a magnetic repulsive force generated between the magnet and the magnetic body, so that a preload is applied to a single rolling bearing. can do. By applying the preload, it is possible to improve positioning accuracy and prevent variation in load torque during rotation. Further, as compared with the case where two rolling bearings are arranged in the axial direction, a preload can be applied to a single rolling bearing, and the axial direction can be reduced in thickness.

Moreover, in the said aspect, the said fixing member and the said rotation member may be provided with the magnetic body which comprises a magnetic circuit.
By doing in this way, it can prevent leaking outside by closing the magnetic flux of the magnet for giving preload by a magnetic circuit.

In the above aspect, two rolling bearings may be provided, and the preload means may apply preload to a position where the inner rings or outer rings of the rolling bearing are close to each other in the axial direction.
By doing so, the play between the ball of the rolling bearing and the race surface can be eliminated by the preload applied by the preload means, positioning accuracy can be improved, and variation in load torque during rotation can be prevented. .

Further, in the above aspect, the rolling bearing may be disposed in the fluid chamber, and the viscous fluid may be oil.
By doing in this way, the viscous fluid for vibration isolation can be used also for lubrication of a rolling bearing. Further, by using oil, it is possible to prevent torque fluctuations during rotation of the rolling bearing due to a thickener or the like.

Moreover, in the said aspect, the linear expansion coefficient of the material of the part which faces the said flow path of the said fixing member and the said rotation member may be larger than the linear expansion coefficient of another part.
By doing in this way, the flow cross-sectional area of a flow path can be changed according to the change of the viscosity of the viscous fluid by a temperature change, and a fixed anti-vibration effect can be maintained irrespective of a temperature change.

In the above aspect, the viscous fluid may be a fluid containing phosphoric acid ester or fluorine as a main component.
By doing so, these components are low outgas components, and even when used in a hard disk device, the adhesion of the outgas components to the storage medium can be prevented and the soundness of the storage medium can be maintained. .

Moreover, in the said aspect, the said rolling bearing may be arrange | positioned on the outer side of the said seal part.
By doing in this way, the quantity of the viscous fluid for vibration isolation can be suppressed to the minimum, and the whole bearing apparatus can be reduced in size.

According to another aspect of the present invention, there is provided a hard disk device including any one of the above-described bearing devices and a swing arm supported swingably by the bearing device and having a head at the tip.
According to this aspect, even when the swing arm is swung at a high control frequency, resonance of the rolling bearing can be prevented, and the positioning accuracy of the head at the tip of the swing arm can be improved.

  According to the present invention, while the swing arm is supported with high precision by the rolling bearing, the vibration of the rolling bearing can be prevented, the control frequency can be improved, and the head positioning accuracy can be improved.

1 is a longitudinal sectional view showing a hard disk device according to an embodiment of the present invention. It is a longitudinal section showing a bearing device concerning one embodiment of the present invention. FIG. 3 is a partial enlarged longitudinal sectional view showing a seal portion of the bearing device of FIG. 2. It is a longitudinal cross-sectional view which shows the 1st modification of the bearing apparatus of FIG. It is a longitudinal cross-sectional view which shows the 2nd modification of the bearing apparatus of FIG. It is a longitudinal cross-sectional view which shows the 3rd modification of the bearing apparatus of FIG.

A bearing device 2 and a hard disk device 1 according to an embodiment of the present invention will be described below with reference to the drawings.
The bearing device 2 according to the present embodiment is provided in the hard disk device 1 as shown in FIG.

  The hard disk device 1 according to this embodiment includes a disk-shaped magnetic storage medium 3, a head 4 that reads and writes information from and to the magnetic storage medium 3, a swing arm 5 that fixes the head 4 to the tip, A bearing device 2 according to the present embodiment that supports the swing arm 5 in a swingable manner and a voice coil motor 6 that drives the swing arm 5 are provided.

  As shown in FIG. 2, the bearing device 2 according to the present embodiment includes a fixing member 8 having a columnar portion 7 at the center, a rotating member 10 having a cylindrical sleeve portion 9 closed at one end, and a fixing member. A single rolling bearing 11 that is disposed between the columnar portion 7 of the shaft 8 and the sleeve portion 9 of the rotating member 10 and rotatably supports the rotating member 10 with respect to the fixed member 8, and a preload is applied to the rolling bearing 11. Preloading means 12 to be applied.

  The rolling bearing 11 is sandwiched between the inner ring 11a into which the columnar part 7 of the fixing member 8 is fitted, the outer ring 11b fitted into the sleeve part 9 of the rotating member 10, and the inner ring 11a and the outer ring 11b. And a plurality of balls 11c arranged at intervals. The inner ring 11a and the outer ring 11b are provided with a race surface 11d for rolling the ball 11c. By applying a force in a direction in which the inner ring 11a and the outer ring 11b are shifted in the axial direction, preload is applied and the ball 11c and the race 11b are raced. The backlash with the surface 11d can be eliminated.

The preloading means 12 is provided at a portion of the rotating member 10 that is disposed at a position facing the magnet 13 embedded at the tip of the columnar portion 7 of the fixing member 8 and at least facing the magnet 13 with an interval in the axial direction. And a magnetic body 14. As a result, the rotating member 10 is biased with respect to the fixed member 8 in a direction close to each other in the axial direction by a magnetic attractive force between the magnet 13 and the magnetic body 14.
That is, a preload is applied to the rolling bearing 11 by the magnetic attractive force between the magnet 13 and the magnetic body 14, and play between the ball 11c and the race surface 11d can be eliminated.

  On the proximal end side of the columnar portion 7 of the fixing member 8, a large-diameter portion 15 having a one-step outer diameter larger than that of the columnar portion 7 is provided. The open end of the sleeve portion 9 of the rotating member 10 extends to a position facing the large diameter portion 15 in the radial direction, and is arranged with an annular gap between the large diameter portion 15. A tapered inner surface 16 that extends toward the tip is provided at the open end of the sleeve portion 9 of the rotating member 10.

  As a result, the space in which the rolling bearing 11 is accommodated is a space that is closed by the rotating member 10 and the fixed member 8 except for the annular gap. The space is configured as a fluid chamber 18 filled with oil (viscous fluid: see FIG. 3) 17. As the oil 17, for example, it is preferable to use an oil mainly composed of a phosphate ester or an oil mainly composed of fluorine.

The annular gap constitutes a flow path 19 connected to the fluid chamber 18. The thickness of the gap constituting the flow path 19 is preferably 3 μm or more and 13 μm or less.
Further, as shown in FIG. 3, the portion that gradually expands toward the open end formed between the tapered inner surface 16 and the outer surface of the large-diameter portion 15 has its surface as a result of the liquid surface of the oil 17 being disposed. It functions as a seal portion 20 that holds the oil 17 in the fluid chamber 18 and the flow path 19 by tension.

The operation of the bearing device 2 and the hard disk device 1 according to the present embodiment configured as described above will be described below.
According to the bearing device 2 according to the present embodiment, the fixing member 8 and the rotating member 10 are axially moved by the magnetic attractive force between the magnet 13 provided on the fixing member 8 and the magnetic body 14 disposed on the rotating member 10. Are attracted to each other in a direction close to each other, and a preload is applied to reduce the backlash between the ball 11c and the race surface 11d. As a result, the swing arm 5 swings smoothly, and the head 4 provided at the tip can be accurately positioned.

  In this state, when the swing arm 5 is swung at a high control frequency by the operation of the voice coil motor 6, the rolling bearing 11 tries to generate vibration as the control frequency approaches the natural frequency. Since the oil 17 is filled in the oil 18, the oil 17 in the fluid chamber 18 flows through the flow path 19 when it vibrates in the direction in which the internal volume of the fluid chamber 18 varies. Since the flow path 19 is sufficiently thin and the oil 17 is a viscous fluid, the vibration is attenuated by the viscous resistance when the oil 17 flows through the flow path 19.

  That is, even if the swing arm 5 is driven at a control frequency close to the natural frequency, the occurrence of resonance can be suppressed and the head 4 can be positioned with high positioning accuracy. The oil 17 is filled up to the flow path 19 and the seal portion 20 communicating with the fluid chamber 18, and is held so as not to leak from the flow path 19 due to the surface tension of the liquid surface of the oil 17 in the seal portion 20. . Therefore, the damper effect can be exhibited for a long time.

  Further, since the rolling bearing 11 is disposed in the fluid chamber 18, the vibration isolating oil 17 can also be used for lubricating the rolling bearing 11. In addition, since the oil 17 is mainly composed of phosphate ester or fluorine as the main component, generation of outgas is suppressed and the soundness of the magnetic storage medium 3 is maintained. Can do. Furthermore, since it does not contain a potentiator like grease, there is also an advantage that it is possible to prevent fluctuations in load torque caused by the potentiator.

  In the present embodiment, since the preload is applied to the single rolling bearing 11 by the magnetic attractive force of the magnet 13 and the magnetic body 14, the two rolling bearings 11 are arranged in the axial direction to apply the preload. Compared to the conventional structure, there is an advantage that the axial dimension can be reduced and the structure can be made thin. Moreover, since the rolling bearing 11 is single, a hysteresis can be made small and the positioning accuracy of the head 4 can be improved. As a result, the read / write operation of the magnetic storage medium 3 can be stabilized. Moreover, since load torque also becomes small, the electric power for positioning can be reduced.

  In the present embodiment, the magnet 13 is disposed on the fixed member 8 and the magnetic body 14 is disposed on the rotating member 10, but instead, the magnetic body 14 and the rotating member are disposed on the fixed member 8 as shown in FIG. A magnet 13 may be arranged at 10. Moreover, you may comprise both with the magnet 14. FIG. In addition, although the preload is applied to the rolling bearing 11 by the magnetic attractive force, the preload may be applied by a magnetic repulsion force instead.

  Further, in this embodiment, the preload is applied to the single rolling bearing 11 by the magnetic attractive force between the magnet 13 and the magnetic body 14, but instead of this, as shown in FIG. Similarly to the structure, the two rolling bearings 11 may be arranged in the axial direction, and the inner ring 11a or the outer ring 11b may be pressurized to apply preload by applying pressure. In the example shown in FIG. 5, the spacer 21 is disposed between the outer rings 11b, and the preload is applied by pressurizing the inner rings 11a in a direction in which they approach each other.

In addition, the rolling bearing 11 is disposed in the fluid chamber 18 and serves as both the lubricant and the vibration isolating oil 17. Instead, as shown in FIG. 6, the rolling bearing 11 is disposed outside the seal portion 20. 11 may be arranged.
By doing so, the vibration isolating oil 17 cannot be used as a lubricant, but the amount of the oil 17 can be reduced, and the seal portion 20 is configured to be compact and compact as a whole. There is an advantage that the bearing device 2 can be provided.

  Moreover, in this embodiment, you may comprise so that the material of the part which faces the flow path of the fixing member 8 and the rotation member 10 may have a larger linear expansion coefficient than the material of another part. By doing in this way, when the viscous fluid becomes high temperature and the viscosity is lowered, the portion with a large linear expansion coefficient is expanded more than the other portions, and the flow cross-sectional area of the flow path is reduced. Further, when the viscosity of the viscous fluid increases and the viscosity increases, the flow cross-sectional area of the flow path is increased. Accordingly, there is an advantage that a constant vibration resistance can be maintained while maintaining a constant flow resistance.

DESCRIPTION OF SYMBOLS 1 Hard disk device 2 Bearing device 4 Head 5 Swing arm 8 Fixed member 10 Rotating member 11 Rolling bearing 11a Inner ring 11b Outer ring 13 Magnet (preload means)
14 Magnetic body (Preloading means)
17 Oil (viscous fluid)
18 Fluid chamber 19 Flow path 20 Seal part

Claims (11)

A fixing member, a rotating member that rotates with respect to the fixing member, and one or more rolling bearings that rotatably support the rotating member with respect to the fixing member,
A fluid chamber is defined between the fixed member and the rotating member so that the internal volume changes when both of the fixed member and the rotating member move relative to each other in the axial direction. A bearing device provided with a flow path through which a viscous fluid flows in response to a change in the internal volume of the fluid chamber.   The bearing device according to claim 1, further comprising a seal portion that seals the fixing member and the rotating member so as to be relatively rotatable.   The bearing device according to claim 1, further comprising preloading means for applying a preload to the rolling bearing. Comprising a single said rolling bearing,
The said preload means is provided with the magnet fixed to one of the said fixing member or the said rotation member, and the magnetic body arrange | positioned on the other of the said fixing member or the said rotation member so as to oppose the said magnet to an axial direction. Item 4. The bearing device according to Item 3.   The bearing device according to claim 4, wherein the fixing member and the rotating member include a magnetic body constituting a magnetic circuit. With two rolling bearings,
The bearing device according to claim 3, wherein the preload means applies preload to a position where inner rings or outer rings of the rolling bearing are close to each other in the axial direction. The rolling bearing is disposed in the fluid chamber;
The bearing device according to claim 1, wherein the viscous fluid is oil.   The bearing device according to any one of claims 1 to 7, wherein the viscous fluid is a fluid mainly composed of phosphate ester or fluorine.   The bearing device according to claim 2, wherein the rolling bearing is disposed outside the seal portion.   The bearing device according to any one of claims 1 to 9, wherein a linear expansion coefficient of a material of a portion of the fixed member and the rotating member facing the flow path is larger than a linear expansion coefficient of another portion. A bearing device according to any one of claims 1 to 10,
A hard disk device comprising a swing arm supported swingably by the bearing device and having a head at a tip.

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