JPH08128440A - Dynamic pressure bearing, media driving motor using this dynamic pressure bearing, magnetic disk device using this motor - Google Patents

Abstract

PURPOSE: To provide a dynamic pressure bearing capable of easily performing the management of a clearance for generating pressure, and supporting a rotary shaft with the stable attitude. CONSTITUTION: A dynamic pressure bearing 50 is provided with an inner frame 12 provided with a bearing hole 15, a motor shaft 20 inserted through the bearing hole, and lubricating oil filled into a clearance 53 between the motor shaft and the bearing hole, and the motor shaft is supported into the floated state by oil pressure generated in the clearance by the rotation of the motor shaft. Recessed parts 54a to 54c are formed on the outer peripheral surface of the motor shaft, and bearing pads 55a to 55c provided with pressure receiving surfaces 56 facing the clearance are housed in the recessed parts so as to be moved in the radial direction of the motor shaft. These bearing pads are advanced to the inner peripheral surface of the bearing hole when they receive a centrifugal force generated with the rotation of the motor shaft, and a minute clearance for generating oil pressure is formed between the inner peripheral surface and the pressure receiving surfaces.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic pressure bearing for supporting a rotating shaft in a floating state by utilizing fluid pressure, and a medium driving type for rotatably supporting a motor shaft via the dynamic pressure bearing. The present invention relates to a motor and a magnetic disk device that rotates a magnetic recording medium at high speed using the motor.

[0002]

2. Description of the Related Art In a book-type portable computer, there is known a model equipped with a magnetic disk device having a storage capacity much higher than that of a floppy disk device and high-speed accessibility.

This magnetic disk device has a box-shaped housing. The inside of this housing forms a clean airtight space that is shielded from the outside air, and a disk-shaped magnetic recording medium, a motor that rotates the magnetic recording medium at high speed, and a data recording medium are stored in the airtight space. Various functional parts such as a magnetic head for recording / reproducing are housed.

A motor for rotating a magnetic recording medium at a high speed includes a rotor that supports the magnetic recording medium and that rotates integrally with the magnetic recording medium. The rotor is
A motor shaft is provided at the center of rotation, and the motor shaft is supported by the housing via a motor bracket. The motor bracket has a bearing hole, and the motor shaft is rotatably supported in the bearing hole via a bearing.

By the way, a ball bearing is conventionally used as a bearing for supporting the motor shaft.
Attempts have been made to use dynamic pressure bearings instead of the ball bearings. This dynamic pressure bearing is for supporting the motor shaft in a floating state by utilizing the oil pressure of the lubricating oil, and the clearance between the motor shaft and the bearing hole is filled with the lubricating oil. A herringbone-shaped groove is formed on one of the outer peripheral surface of the motor shaft and the inner peripheral surface of the bearing hole facing the gap, and when the motor shaft is rotated, the gap The motor shaft is supported in a floating state by the hydraulic pressure generated at.

[0006]

However, since the gap for generating the hydraulic pressure is required to be on the order of several μm, strict gap management is required. Therefore, not only the machining of the motor shaft and the bearing hole, but also the assembling of the motor requires a lot of labor, which causes a problem of high cost.

Moreover, since the hydraulic pressure is generated at the position where the clearance is the narrowest, the positional relationship between the outer peripheral surface of the motor shaft and the inner peripheral surface of the bearing hole is not constant along the circumferential direction, and the motor shaft It becomes difficult to evenly support the lubrication over the entire circumference. In particular, when the accuracy of the clearance is poor, the motor shaft may tilt or swing around its axis, causing a large vibration of the motor shaft, which makes it impossible to exhibit the expected lubrication performance.

When the motor shaft vibrates in this way, the magnetic recording medium and the magnetic head interfere with each other, the data recorded on the magnetic recording medium is destroyed, and the positioning accuracy of the magnetic head with respect to the magnetic recording medium is improved. There is a problem that it decreases.

The present invention has been made under such circumstances, and it is possible to easily perform the clearance control for generating the fluid pressure and to support the rotating shaft in a stable posture. The purpose is to provide a dynamic pressure bearing.

Another object of the present invention is to provide a media drive motor equipped with a dynamic pressure bearing for supporting the motor shaft, by which the clearance of the dynamic pressure bearing can be easily controlled, the processability and the assemblability can be improved, and the motor shaft can be improved. To obtain a structure capable of improving the rotation accuracy of the.

Still another object of the present invention is to provide a magnetic disk device having a motor for rotating a magnetic recording medium at a high speed, since the motor shaft of the motor can be accurately supported, and the magnetic recording medium and the magnetic head interfere with each other. Another object of the present invention is to obtain a structure capable of preventing the above-mentioned problem and improving the positioning accuracy of the magnetic head.

[0012]

In order to achieve the above object, the invention described in claim 1 includes a fixing member having a bearing hole, and a rotating shaft rotatably inserted in the bearing hole of the fixing member. And a fluid filled in a gap between the rotary shaft and the bearing hole, the fluid pressure generated in the gap as the rotary shaft rotates causes the rotary shaft to float in the radial direction. It is premised on a dynamic pressure bearing that is supported in a state.

The rotary shaft has an outer peripheral surface facing the inner peripheral surface of the bearing hole through the gap, and a concave portion is formed on the outer peripheral surface of the rotary shaft. A bearing pad having a pressure-receiving surface facing the inner surface of the bearing hole is movably accommodated in the radial direction of the rotary shaft, and the bearing pad is directed toward the inner peripheral surface of the bearing hole by a centrifugal force generated as the rotary shaft rotates. It is characterized in that a minute gap for generating the fluid pressure is formed between the inner peripheral surface and the pressure receiving surface.

According to a second aspect, the plurality of recesses according to the first aspect are arranged at intervals in the circumferential direction of the rotary shaft, and the bearing pads correspond to the respective recesses. The feature is that a plurality of them are arranged.

Further, in order to achieve the above-mentioned object, claim 3
The invention described in (1) is a fixing member having a bearing hole and a large-diameter pressure chamber continuous with the bearing hole, a rotary shaft rotatably inserted in the bearing hole of the fixing member, and a rotary shaft coaxial with the rotary shaft. While rotating integrally, it is provided with a thrust disk housed in the pressure chamber, and a fluid filled in the gap between the axially facing end surface of the thrust disk and the inner surface of the pressure chamber, It is premised on a dynamic pressure bearing in which the rotary shaft is supported in a floating state in the axial direction by the fluid pressure generated in the gap as the rotary shaft rotates.

A recess is formed on the end surface of the thrust disk, and the bottom surface of the recess is a guide surface inclined toward the end surface of the thrust disk as it goes radially outward from the center of rotation of the thrust disk. And a sliding surface that slidably contacts the guide surface in the recess,
A wedge-shaped bearing pad having a pressure receiving surface facing the gap is accommodated, and the bearing pad is moved toward the radially outer side of the thrust disk by a centrifugal force generated with the rotation of the rotating shaft, It is characterized in that it moves in the axial direction of the rotary shaft based on the inclination of the guide surface and forms a minute gap for generating the fluid pressure between the pressure receiving surface and the inner surface of the pressure chamber.

According to a fourth aspect, the plurality of recesses according to the third aspect are arranged at intervals in the circumferential direction of the thrust disk, and the bearing pads correspond to the respective recesses. The feature is that a plurality of them are arranged.

In order to achieve the above-mentioned other objects, a medium driving motor according to a fifth aspect of the present invention is such that a rotor supporting a disc-shaped medium, a motor shaft rotating integrally with the rotor, and the motor shaft are A frame having a bearing hole rotatably inserted therein and a large-diameter pressure chamber connected to the bearing hole, and a thrust disk housed in the pressure chamber while rotating integrally with the motor shaft coaxially, The motor has a first gap between the motor shaft and the bearing hole and a second gap between the axially facing end surface of the thrust disk and the inner surface of the pressure chamber, and the motor has the following characteristics. And a dynamic pressure bearing that supports the motor shaft in a floating state in the radial direction and the axial direction by the fluid pressure generated in each gap when the shaft rotates.

A first concave portion is formed on the outer peripheral surface of the motor shaft facing the inner peripheral surface of the bearing hole, and the first concave portion has a pressure receiving surface facing the first gap. A bearing pad is movably accommodated in the radial direction of the motor shaft, and the first bearing pad is advanced toward the inner peripheral surface of the bearing hole by a centrifugal force generated with the rotation of the motor shaft. Forming a minute gap for generating the fluid pressure between the inner peripheral surface and the pressure receiving surface, and forming a second concave portion on the end surface of the thrust disk facing the inner surface of the pressure chamber, The bottom surface of the second recess forms a guide surface that is inclined toward the end surface of the thrust disk as it goes radially outward from the center of rotation of the thrust disk. A sliding surface that slidably contacts the guide surface, A wedge-shaped second bearing pad having a pressure receiving surface facing the second gap is accommodated, and the second bearing pad is generated in a radial direction of the thrust disk by a centrifugal force generated as the motor shaft rotates. While moving toward the outside, it moves in the axial direction of the motor shaft based on the inclination of the guide surface, and a minute gap for generating the fluid pressure is formed between the pressure receiving surface and the inner surface of the pressure chamber. It is characterized by forming.

According to another aspect of the present invention, there is provided a magnetic disk device including a box-shaped housing and at least one disk-shaped magnetic recording medium housed in the housing. And a magnetic head that faces the surface of the magnetic recording medium and records / reproduces data, and a motor that is supported by the housing and rotates the magnetic recording medium at a high speed.

The motor has a rotor that supports the magnetic recording medium, a motor shaft that rotates integrally with the rotor, a bearing hole through which the motor shaft is rotatably inserted, and a large diameter that is continuous with the bearing hole. A frame having a pressure chamber, which rotates coaxially with the motor shaft and rotates integrally therewith, and a thrust disk housed in the pressure chamber, a first gap between the motor shaft and a bearing hole, and The second gap between the axially facing end surface of the thrust disk and the inner surface of the pressure chamber has fluid filled therein, and the fluid pressure generated in each of the gaps when the motor shaft rotates causes A dynamic pressure bearing for supporting the motor shaft in a floating state in the radial direction and the axial direction, and forming a first concave portion on the outer peripheral surface of the motor shaft facing the inner peripheral surface of the bearing hole.
A first bearing pad having a pressure receiving surface facing the first gap is movably accommodated in the concave portion of the motor shaft in a radial direction of the motor shaft, and the first bearing pad is rotated along with the rotation of the motor shaft. Due to the centrifugal force generated, it is advanced toward the inner peripheral surface of the bearing hole, while forming a minute gap for generating the fluid pressure between the inner peripheral surface and the pressure receiving surface,
A second recess is formed on the end surface of the thrust disk facing the inner surface of the pressure chamber, and the bottom surface of the second recess extends toward the outer side in the radial direction from the center of rotation of the thrust disk. Forming a wedge-shaped first surface having a sliding surface slidably contacting the guide surface and a pressure receiving surface facing the second gap. Accommodating two bearing pads, this second
The bearing pad of (1) moves in the radial direction of the thrust disk by the centrifugal force generated with the rotation of the motor shaft, and moves in the axial direction of the motor shaft based on the inclination of the guide surface. A minute gap for generating the fluid pressure is formed between the pressure receiving surface and the inner surface of the pressure chamber.

[0022]

According to the structure described in claim 1, when the bearing pad receives a centrifugal force caused by the rotation of the rotary shaft, the bearing pad is pushed outward from the concave portion of the rotary shaft in the radial direction. Therefore, the bearing pad is pressed against the inner peripheral surface of the bearing hole that makes relative movement with the rotating shaft, and forms a minute gap sufficient to generate fluid pressure between the bearing pad and the inner peripheral surface of the bearing hole. And
The movement of the bearing pad is stopped when the centrifugal force acting on the bearing pad and the liquid pressure are balanced, and the fluid pressure supports the rotating shaft in a radially floating state.

Since the minute gap for generating the liquid pressure is formed only when the bearing pad is moved by receiving the centrifugal force, the minute gap is formed between the inner peripheral surface of the bearing hole and the outer peripheral surface of the rotary shaft. The gap can be made larger than the minute gap. For this reason, strict clearance management as in the conventional dynamic pressure bearing becomes unnecessary. At the same time, since the minute gap is determined by the balance with the centrifugal force, the dimension of the minute gap does not vary greatly, and it is possible to prevent the rotation shaft from tilting or whirling.

According to the second aspect of the invention, since the plurality of bearing pads are arranged side by side in the circumferential direction of the rotary shaft, when the rotary shaft is rotated, the bearing pads are arranged over substantially the entire circumference of the rotary shaft. Can form a minute gap. Therefore, the degree of eccentricity of the rotary shaft with respect to the bearing hole is reduced.

According to the third aspect of the invention, when the rotary shaft rotates, the bearing pad on the thrust disk, which rotates integrally with the rotary shaft, is subjected to centrifugal force and is directed outward in the radial direction of the thrust disk. While being pushed out, it also moves in the axial direction of the rotating shaft with the inclination of the contact surface between the bearing pad and the thrust disk. Therefore, the bearing pad is pressed toward the inner surface of the pressure chamber that makes relative movement with the rotating shaft,
A minute gap sufficient to generate a fluid pressure is formed between the pressure chamber and the inner surface thereof. The movement of the bearing pad in the axial direction is stopped when the centrifugal force acting on the bearing pad and the liquid pressure are balanced, and the fluid pressure supports the rotating shaft in a floating state in the axial direction.

Since the minute gap for generating the liquid pressure is formed only when the bearing pad receives the centrifugal force and moves in the axial direction of the rotating shaft, the inner surface of the pressure chamber and the end surface of the thrust disk are formed. The gap between and can be made larger than the minute gap. For this reason, strict clearance management as in the conventional dynamic pressure bearing becomes unnecessary. At the same time, since the minute gap is determined by the balance with the centrifugal force, the dimension of the minute gap does not vary greatly, and the inclination and whirling of the rotary shaft including the thrust disk can be prevented.

According to the structure described in claim 4, since the plurality of bearing pads are arranged side by side in the circumferential direction of the thrust disc, when the thrust disc is rotated together with the rotary shaft, the end face of the thrust disc It is possible to form a minute gap over the entire circumference between the inner surface of the pressure chamber and the inner surface. Therefore, pressure is applied to the end surface of the thrust disk over substantially the entire circumference, and the rotational posture of the rotary shaft is more stable.

According to the structure described in claim 5, when the motor shaft is rotated together with the rotor, the first bearing pad on the outer peripheral surface of the motor shaft is subjected to centrifugal force and is directed outward in the radial direction. Pushed out. Therefore, the first bearing pad is
It is pressed against the inner peripheral surface of the bearing hole that makes relative movement with the motor shaft, and forms a minute gap sufficient to generate fluid pressure between the inner peripheral surface of the bearing hole and the inner peripheral surface. Then, the radial movement of the first bearing pad is stopped when the centrifugal force acting on the first bearing pad and the liquid pressure are balanced, and the fluid pressure causes the motor shaft to float in the radial direction. Supported.

On the other hand, the second bearing pad on the thrust disk that rotates integrally with the motor shaft is pushed toward the outer side in the radial direction of the thrust disk by receiving the centrifugal force, and at the same time, the contact surface of the thrust disk is contacted. It moves in the axial direction of the motor shaft with the inclination. Therefore, the second bearing pad is pressed against the inner surface of the pressure chamber that makes relative motion with the motor shaft, and forms a minute gap sufficient to generate fluid pressure between the second bearing pad and the inner surface of the pressure chamber. The movement of the second bearing pad in the axial direction is stopped when the centrifugal force acting on the second bearing pad and the liquid pressure are balanced, and the fluid pressure causes the motor shaft to float in the axial direction. Supported.

Since the two minute gaps for generating the liquid pressure are formed only when the first and second bearing pads move by receiving the centrifugal force, the two gaps between the motor shaft and the bearing hole are formed. The first gap therebetween and the second gap between the inner surface of the pressure chamber and the end surface of the thrust disk can be made larger than the minute gap. Therefore, the clearance of the dynamic pressure bearing can be easily managed. At the same time, since the minute gap is determined by the balance with the centrifugal force, the variation in the dimension of the minute gap is eliminated, and the inclination and whirling of the motor shaft can be prevented.

According to the structure described in claim 6, similarly to the above-mentioned claim 5, the minute gap for generating the liquid pressure is moved by the first and second bearing pads receiving the centrifugal force. The first gap between the motor shaft and the bearing hole and the second gap between the inner surface of the pressure chamber and the end surface of the thrust disk can be made larger than the minute gap. . Therefore, the clearance of the dynamic pressure bearing can be easily managed.

At the same time, since the minute gap is determined by the balance with the centrifugal force, the variation in the dimension of the minute gap is eliminated, and the inclination and whirling of the motor shaft can be prevented. Therefore, the vibration of the magnetic recording medium can be prevented, the interference between the magnetic recording medium and the magnetic head can be avoided, and the positioning accuracy of the magnetic head with respect to the magnetic recording medium is improved.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings applied to a magnetic disk device. FIG. 1 shows a magnetic disk device 1 used as a storage device of a portable computer. This magnetic disk device 1 is
The housing 2 is made of metal and has a rectangular box shape.
The housing 2 has a housing body 3 whose upper surface is opened.
And a top cover 4 that hermetically covers the upper opening of the housing body 3. The inside of the housing 2 is a clean airtight space 5 that is shielded from the outside air.

The housing body 3 has a bottom wall 6 facing the top cover 4. A motor mounting hole 7 is opened in the bottom wall 6. A motor bracket 9 is fitted into the motor mounting hole 7 from the inside of the housing body 3. This motor bracket 9 has a motor mounting hole 7
Is airtightly closed.

As shown in FIG. 2, an outer rotor type motor 11 is supported on the motor bracket 9.
The motor 11 is housed in the airtight space 5 of the housing 2. The motor 11 has an inner frame 12 as a fixing member, and the inner frame 12 is connected to the motor bracket 9. Inner frame 12
Has a small-diameter portion 13 and a large-diameter portion 14 connected to the upper end of the small-diameter portion 13.

The small diameter portion 13 has a bearing hole 15 extending in the axial direction on the axis center line thereof. A herringbone-shaped groove (not shown) is formed on the inner peripheral surface of the bearing hole 15. The large-diameter portion 14 has a recess 16 opened on the upper surface of the large-diameter portion 14. This recess 16 is the bearing hole 1
The bearing hole 15 has a diameter larger than 5, and is coaxial with the bearing hole 15, and the bearing hole 15 is opened in the bottom surface of the recess 16. The open end of the recess 16 is liquid-tightly closed by a lid plate 17, and a pressure chamber 18 is formed between the lid plate 17 and the bottom surface of the recess 16. Then, on the bottom surface of the recess 16 facing the pressure chamber 18 and the bottom surface of the lid plate 17,
A herringbone-shaped groove (not shown) is formed.

A motor shaft 20 as a rotating shaft is inserted through the bearing hole 15 so as to be rotatable in the axial direction. The lower end of the motor shaft 20 is rotatably fitted to the motor bracket 9, and the upper end of the motor shaft 20 is
It penetrates through the cover plate 17 and projects above the inner frame 12.

A rotor 21 is coaxially arranged around the outer periphery of the inner frame 12. The rotor 21 has a hollow cylindrical shape, and its upper portion is rotatably fitted to the outer peripheral surface of the large diameter portion 14. A magnet 23 is attached to the inner peripheral surface of the rotor 21. The magnet 23 rotates integrally with the rotor 21, and faces the outer peripheral surface of the small diameter portion 13.

Between the magnet 23 and the small diameter portion 13,
The stator 25 is arranged. The stator 25 includes a laminated core 26 and a coil 27 wound around the laminated core 26.
The laminated core 26 is fixed to the outer peripheral surface of the small diameter portion 13.

A support wall 29 is formed on the outer peripheral surface of the lower portion of the rotor 21 so as to project radially outward. And FIG.
As shown in (3), three disk-shaped magnetic recording media 30a, 30b, 30c are coaxially fitted to the outer peripheral surface of the rotor 21. These magnetic recording media 30a, 30b,
The arrangement interval of 30c is determined by the spacer rings 31a and 31b.

A fixed disk 33 is fixed to the upper surface of the rotor 21 via screws 32. The fixed disk 33 has a pressing portion 34 that projects outward in the radial direction from the rotor 21 on the outer peripheral portion thereof, and the pressing portion 34 is the highest magnetic recording medium 3.
It is in contact with the center of rotation 0a. Therefore, the fixed disk 3
3 sandwiches the rotation centers of the three magnetic recording media 30a, 30b and 30c and the spacer rings 31a and 31b with the support wall 29 of the rotor 21. As a result, the magnetic recording media 30a, 30b, 30c are supported by the rotor 21 and rotate together with the rotor 21.

A fitting hole 35 is opened at the center of rotation of the fixed disk 33. The upper end portion of the motor shaft 20 is fitted and fixed in the fitting hole 35, and the motor shaft 20 rotates together with the fixed disk 33 and the rotor 21.

As shown in FIGS. 1 and 3, a carriage 37 is arranged in the airtight space 5 of the housing 2. The carriage 37 has a cylindrical boss portion 38, and the boss portion 38 is pivotally supported by the bottom wall 6 of the housing body 3 via a pivot shaft 39. Therefore, the carriage 37
3 approaches the magnetic recording media 30a, 30b, 30c with the pivot 39 as a fulcrum, as shown by an arrow in FIG.
On the contrary, the magnetic recording media 30a, 30b, and 30c can be rotated over a certain angle range in a direction away from the magnetic recording media 30a, 30b, and 30c.

The carriage 37 has a plurality of arm portions 40 connected to the boss portion 38. Suspension arms 41 are connected to the distal ends of the arm portions 40, respectively. A magnetic head 42 is supported at the tip of these suspension arms 41. The magnetic head 42 is for recording / reproducing data, and faces the surfaces of the magnetic recording media 30a, 30b, 30c.

A voice coil motor 45 is housed in the airtight space 5 of the housing 2. The voice coil motor 45 changes the rotation angle and rotation direction of the carriage 37 by changing the magnitude and direction of the current supplied to the magnet (not shown). As a result, the magnetic head 42 causes the magnetic recording media 30a, 30
It is moved in the radial direction of b and 30c and positioned on desired tracks on these magnetic recording media 30a, 30b and 30c, and data writing and reading are performed.

By the way, such a magnetic disk drive 1
In the above, the dynamic pressure bearing 50 is interposed between the motor shaft 20 of the motor 11 and the inner frame 12. The dynamic pressure bearing 50 includes a first bearing portion 51 that supports the motor shaft 20 in a floating state in the radial direction, and the motor shaft 20.
And a second bearing portion 52 that supports the shaft in a floating state in the axial direction.

As shown in FIG. 4, the first bearing portion 51 is
Between the inner peripheral surface of the bearing hole 15 and the outer peripheral surface of the motor shaft 20,
It has a gap 53 continuous in the circumferential direction. This gap 53
Is filled with lubricating oil as a fluid. Bearing hole 1
The inner peripheral surface of 5 has three first recesses 54a, 54b, 5
4c are formed at intervals in the circumferential direction. The first recesses 54a, 54b, 54c have a rectangular shape extending in the axial direction of the bearing hole 15, and the first recesses 54a, 54b
54 b and 54 c are opened in the gap 53.

In the first recesses 54a, 54b, 54c,
First bearing pads 55a, 55b, 55c are housed, respectively. First bearing pads 55a, 55b, 55c
Each have a pressure receiving surface 56 facing the gap 53,
The pressure receiving surface 56 is curved in an arc shape along the inner peripheral surface of the bearing hole 15. Then, the first bearing pad 55
a, 55b, 55c are the first concave portions 54a, 54b, 54 with the pressure receiving surface 56 slightly projected into the gap 53.
is supported by the first bearing pad 55a,
55b and 55c are movable in the radial direction of the motor shaft 20.

Therefore, when the centrifugal force caused by the rotation of the motor shaft 20 acts on the first bearing pads 55a, 55b, 55c, the first bearing pads 55a, 55b, 55c.
Is advanced radially outward from the first recesses 54a, 54b, 54c, and its pressure receiving surface 56 is pressed toward the inner peripheral surface of the bearing hole 15. As a result of this pressing, as shown in FIG. 4B, a minute gap 57 that is small enough to generate hydraulic pressure is formed between the pressure receiving surface 56 and the inner peripheral surface of the bearing hole 15. 20 is supported in a floating state in the radial direction. Therefore, the motor shaft 20
The gap 53 between the bearing hole 15 and the bearing hole 15 is set to be larger than the minute gap 57.

As shown in FIG. 7, the second bearing portion 52 is
It has a thrust disk 60 that rotates integrally with the motor shaft 20. The thrust disk 60 is coaxial with the motor shaft 20 and is housed in the pressure chamber 18 of the inner frame 12. The thrust disk 60 has an upper surface 60a facing the bottom surface of the recess 16 and a lower surface 60b facing the lid plate 17, and the bottom surface and the lower surface 60b of the recess 16 and the lid plate 1 are provided.
A second gap 62 is formed between 7 and the upper surface 60a. The second gap 62 is filled with lubricating oil as a fluid.

On the upper surface 60a and the lower surface 60b of the thrust disk 60, there are three second recesses 63a, 63b, 6 respectively.
3c are formed at intervals in the circumferential direction. As shown in FIG. 8, these second recesses 63a, 63b, 63c are curved in an arc shape, and are arranged concentrically around the motor shaft 20. The second recess 63a,
As shown in FIG. 7, the bottom surfaces of 63b and 63c form guide surfaces 64 that are inclined in a direction approaching the upper surface 60a and the lower surface 60b of the thrust disk 60 as going radially outward from the rotation center side of the thrust disk 60. ing. And
These second recesses 63a, 63b, 63c are the same as the second
Is opened in the gap 62.

In the second recesses 63a, 63b, 63c,
The second bearing pads 66a, 66b, 66c are housed, respectively. Second bearing pads 66a, 66b, 66c
Has a pressure receiving surface 67 facing the second gap 62 and a sliding surface 68 slidably contacting the guide surface 64. The pressure receiving surface 67 is substantially parallel to the bottom surface of the recess 16 and the lid plate 17. Therefore, the second bearing pad 66
Each of a, 66b, and 66c has a wedge-shaped cross section.

Second bearing pads 66a, 66b, 66c
Are supported by the second recesses 63a, 63b, 63c with the pressure receiving surface 67 slightly protruding into the second gap 62, and these second bearing pads 66a, 66b, 66 are supported.
c is movable in the axial direction of the motor shaft 20.

Therefore, the centrifugal force generated by the rotation of the motor shaft 20 is transmitted through the thrust disk 60 to the second bearing pad 66.
When acting on a, 66b, 66c, these second bearing pads 66a, 66b, 66c are, as shown in FIG. 7B, radially outward of the thrust disc 60 from the second recesses 63a, 63b, 63c. Is pushed towards. On this occasion,
Sliding surface 68 of second bearing pad 66a, 66b, 66c
The guide surface 64 in contact with the second bearing pad 66a, 66b, 66c is inclined in the direction approaching the upper surface 60a and the lower surface 60b of the thrust disk 60 as it goes radially outward from the center of rotation of the thrust disk 60. Moves in the axial direction of the motor shaft 20 as the guide surface 64 tilts, and its pressure receiving surface 67 is pressed toward the bottom surface of the recess 16 and the lid plate 17. By this pressing, as shown in FIG. 7B, the pressure receiving surface 67, the bottom surface of the recess 16 and the lid plate 17 are formed.
A minute gap 69 sufficient to generate a hydraulic pressure is formed between and, and the hydraulic pressure supports the motor shaft 20 in a floating state in the axial direction. Therefore, the second gap 62 between the thrust disc 60 and the bottom surface of the recess 16 and the lid plate 17 is set larger than the minute gap 69.

In the magnetic disk device 1 having the motor 11 having such a configuration, when the motor shaft 20 is rotated, the first bearing pads 55a, 55 are subjected to the centrifugal force thereof.
b and 55c move in the radial direction of the motor shaft 20, and the bearing hole 1
A minute gap 57 sufficient to generate hydraulic pressure is formed between the inner peripheral surface of the inner peripheral surface 5 and the inner peripheral surface of the inner peripheral surface 5. Similarly, the second bearing pads 66a, 66b, 66c on the thrust disk 60 move in the axial direction while moving in the radial direction of the motor shaft 20 to generate hydraulic pressure between the bottom surface of the recess 16 and the lid plate 17. Micro gap 69 sufficient to generate
To form. Then, the first bearing pads 55a, 55
b, 55c and second bearing pads 66a, 66b, 6
6c is stopped when the centrifugal force acting on them and the hydraulic pressure are balanced, and thereafter, the motor shaft 20 is supported in a floating state in the radial direction and the axial direction by the hydraulic pressure of the minute gaps 57 and 69.

The lubricating oil is used as the first concave portions 54a, 54a.
b, 54c and the first bearing pads 55a, 55b, 55c
And between the second recesses 63a, 63b, 63c and the second bearing pads 66a, 66b, 66c. In this case, the first recesses 54a, 54b, 54c
And first bearing pads 55a, 55b, 55c and second
Recesses 63a, 63b, 63c and the second bearing pad 66
Since the a, 66b, and 66c rotate integrally with each other, no relative movement occurs between them and, therefore, no hydraulic pressure occurs.

The minute gap 5 for generating the hydraulic pressure in this way
7, 69 are first bearing pads 55a, 55b, 55c
Since the second bearing pads 66a, 66b, 66c are formed only by moving by receiving the centrifugal force, the first gap 53 between the bearing hole 15 and the motor shaft 20 is formed.
And the bottom surface of the thrust disk 60 and the recess 16 and the lid plate 1
The second gap 62 between the fine gaps 57 and 69
Can be larger than

Therefore, compared to the conventional dynamic pressure bearing 50, stricter dimensional control of the gaps 53 and 62 is not required, and the workability of the motor shaft 20 and the bearing hole 15 is improved by that much, and the assembling work of the motor 11 is performed. Can be done easily.

Further, minute gaps 57, 6 for generating hydraulic pressure
Since 9 is determined based on the relationship with the magnitude of the centrifugal force acting on the first bearing pads 55a, 55b, 55c and the second bearing pads 66a, 66b, 66c, the dimensions of the minute gaps 57, 69, and thus the hydraulic pressure, are determined. It does not vary greatly.

Moreover, the first bearing pads 55a, 55
b, 55c and second bearing pads 66a, 66b, 6
Since 6c is arranged at intervals in the circumferential direction of the motor shaft 20 and the thrust disk 60, when the motor shaft 20 is rotated, it is substantially continuous in the circumferential direction of the motor shaft 20 and the thrust disk 60. The minute gaps 57 and 69 can be formed.

As a result, the degree of eccentricity of the motor shaft 20 with respect to the bearing hole 15 is reduced, and the inclination and whirling of the motor shaft 20 can be reliably prevented. As a result, the rotation accuracy of the motor shaft 20 and thus the rotor 21 is improved, and the motor 11 is used to drive the magnetic recording media 30a, 30b, 3
When the drive source of 0c is used, the magnetic recording medium 30
It is possible to prevent vibration of a, 30b, 30c.

Therefore, the magnetic recording media 30a, 30
It is of course possible to avoid interference between the magnetic heads b and 30c and the magnetic head 42, and it is also possible to easily perform clearance management between the magnetic heads 42 during rotation of the magnetic recording media 30a, 30b and 30c, and , Magnetic recording media 30a, 3
There is an advantage that the positioning accuracy of the magnetic head 42 with respect to 0b and 30c is also improved.

The numbers of the first and second bearing pads are not limited to those in the above embodiment, but can be increased or decreased as necessary. Further, the fluid for generating the pressure is not limited to the lubricating oil, and air, for example, may be used.

Further, the motor is not specified for the magnetic disk device, but can be similarly applied to devices such as a floppy disk device and a printer.

[0065]

According to the first aspect of the present invention, since the minute gap for generating the liquid pressure is formed only when the bearing pad is moved by receiving the centrifugal force, the inner peripheral surface of the bearing hole and the rotary shaft are not formed. The gap with the outer peripheral surface of the can be made larger than the minute gap. Therefore, strict clearance management as in the conventional dynamic pressure bearing is not required, and the rotating shaft and the bearing hole can be easily processed and assembled. At the same time, since the size of the minute gap does not vary greatly, it is possible to prevent the rotation shaft from tilting or whirling.

According to the second aspect, when the rotary shaft is rotated, a minute gap can be formed over substantially the entire circumference of the rotary shaft. Therefore, the degree of eccentricity of the rotary shaft with respect to the bearing hole is reduced, and the rotation accuracy of the rotary shaft is improved.

According to the third aspect, since the minute gap for generating the liquid pressure is formed only when the bearing pad receives the centrifugal force and moves in the axial direction of the rotating shaft,
The clearance between the inner surface of the pressure chamber and the end surface of the thrust disk can be made larger than the minute clearance. For this reason,
There is no need for strict clearance control like the conventional dynamic pressure bearings,
The fixing member including the bearing hole and the pressure chamber and the thrust disk can be easily processed and assembled. At the same time, the size of the minute gap does not vary greatly,
It is possible to prevent tilting and whirling of the rotating shaft including the thrust disk.

According to the fourth aspect, when the thrust disk is rotated together with the rotary shaft, a minute gap can be formed between the end surface of the thrust disk and the inner surface of the pressure chamber over substantially the entire circumference. Therefore, pressure is applied to the end surface of the thrust disk over substantially the entire circumference, and the rotational posture of the rotary shaft is more stable.

According to the fifth aspect, since the minute gap for generating the liquid pressure is formed only when the first and second bearing pads move by receiving the centrifugal force,
The first clearance between the motor shaft and the bearing hole and the second clearance between the inner surface of the pressure chamber and the end surface of the thrust disk can be set larger than the above-mentioned minute clearance, and the clearance management of the dynamic pressure bearing is easy. Can be done At the same time, since the size of the minute gap does not greatly vary, the inclination and whirling of the motor shaft can be prevented, and the rotation accuracy of the motor shaft is improved.

According to the sixth aspect, the first gap between the motor shaft and the bearing hole and the second gap between the inner surface of the pressure chamber and the end surface of the thrust disk are set to be larger than the minute gap. Therefore, the clearance of the dynamic pressure bearing can be easily managed. Moreover, since the size of the minute gap does not greatly vary and the inclination and whirling of the motor shaft can be prevented, the rotation accuracy of the motor shaft is improved. Therefore, the vibration of the magnetic recording medium can be prevented, the interference between the magnetic recording medium and the magnetic head can be avoided, and the positioning accuracy of the magnetic head with respect to the magnetic recording medium can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a magnetic disk device.

FIG. 2 is a cross-sectional view of a motor that rotates a magnetic recording medium.

FIG. 3 is a plan view of a magnetic disk device.

FIG. 4A is a sectional view of a first bearing portion of a dynamic pressure bearing.
FIG. 6B is a cross-sectional view showing a state in which a minute gap is formed between the pressure receiving surface of the first bearing pad and the inner peripheral surface of the bearing hole.

5 is a cross-sectional view taken along the line XX of FIG.

FIG. 6 is a perspective view showing a state in which a first bearing pad is attached to a motor shaft.

FIG. 7A is a sectional view of a second bearing portion of the dynamic pressure bearing.
FIG. 6B is a cross-sectional view showing a state in which a minute gap is formed between the pressure receiving surface of the second bearing pad, the bottom surface of the recess, and the lid plate.

FIG. 8 is a perspective view showing a state in which a second bearing pad is mounted on the thrust disk.

[Explanation of symbols]

 2 ... Housing 11 ... Motor 12 ... Fixing member (inner frame) 15 ... Bearing hole 18 ... Pressure chamber 20 ... Motor shaft (rotating shaft) 21 ... Rotor 30a, 30b, 30c ... Magnetic recording medium 50 ... Dynamic pressure bearing 53 ... No. First clearance 54a, 54b, 54c ... First recess 55a, 55b, 55c ... First bearing pad 56, 67 ... Pressure receiving surface 57, 69 ... Minute clearance 60 ... Thrust disk 62 ... Second clearance 63a, 63b, 63c ... 2nd recessed part 64 ... Guide surface 66a, 66b, 66c ... 2nd bearing pad 68 ... Sliding surface

Claims (6)

[Claims] 1. A fixing member having a bearing hole, a rotating shaft rotatably inserted in the bearing hole of the fixing member, and a fluid filled in a gap between the rotating shaft and the bearing hole. In a dynamic pressure bearing, wherein the rotating shaft is supported in a floating state in the radial direction by a fluid pressure generated in the gap as the rotating shaft rotates, the rotating shaft has the bearing hole. The inner peripheral surface of the rotary shaft has an outer peripheral surface facing each other through the gap, and a concave portion is formed on the outer peripheral surface of the rotary shaft. A bearing pad having a pressure receiving surface facing the gap is formed in the concave shaft of the rotary shaft. The bearing pad is housed so as to be movable in the radial direction, and the bearing pad is advanced toward the inner peripheral surface of the bearing hole by the centrifugal force generated with the rotation of the rotating shaft, and the inner peripheral surface and the pressure receiving surface are Between the two to form a minute gap to generate the above fluid pressure. Dynamic bearing which is characterized in that. 2. The method according to claim 1, wherein the recess is
A plurality of bearings are arranged at intervals in the circumferential direction of the rotary shaft, and a plurality of the bearing pads are arranged in correspondence with the respective recesses. 3. A fixing member having a bearing hole and a large-diameter pressure chamber connected to the bearing hole, a rotary shaft rotatably inserted in the bearing hole of the fixing member, and a coaxial shape with the rotary shaft. While rotating together,
A thrust disk housed in the pressure chamber; and a fluid filled in a gap between the axially facing end surface of the thrust disk and the inner surface of the pressure chamber. In the dynamic pressure bearing in which the rotary shaft is supported in a floating state in the axial direction by the fluid pressure generated in the gap, a recess is formed in the end face of the thrust disk, and the bottom surface of the recess is the thrust. As it goes radially outward from the center of rotation of the disk, it forms a guide surface that is inclined toward the end surface of this thrust disk.In this recess, there is a sliding surface that slidably contacts the guide surface, and A wedge-shaped bearing pad having a pressure receiving surface facing the gap is accommodated, and the bearing pad is moved toward the radially outer side of the thrust disk by a centrifugal force generated with the rotation of the rotating shaft, A movement characterized by moving in the axial direction of the rotary shaft based on the inclination of the guide surface and forming a minute gap for generating the fluid pressure between the pressure receiving surface and the inner surface of the pressure chamber. Pressure bearing. 4. The method according to claim 3, wherein the recess is
A plurality of bearings are arranged at intervals in the circumferential direction of the thrust disk, and a plurality of the bearing pads are arranged corresponding to the recesses, respectively. 5. A rotor supporting a disk-shaped medium, a motor shaft rotating integrally with the rotor, a bearing hole through which the motor shaft is rotatably inserted, and a large-diameter pressure chamber continuous with the bearing hole. A frame, a thrust disc that is coaxial with the motor shaft and rotates together, and is housed in the pressure chamber; a first gap between the motor shaft and a bearing hole; and a shaft of the thrust disc. The second clearance between the end surface facing in the direction and the inner surface of the pressure chamber, and the diameter of the motor shaft is increased by the fluid pressure generated in each of the clearances when the motor shaft rotates. And a dynamic pressure bearing that supports the bearing in a floating direction in the axial direction and the axial direction. The first outer surface of the motor shaft faces the inner peripheral surface of the bearing hole.
And a first bearing pad having a pressure receiving surface facing the first gap is housed in the first recess so as to be movable in the radial direction of the motor shaft. , A minute gap for generating the fluid pressure between the inner peripheral surface and the pressure receiving surface by advancing toward the inner peripheral surface of the bearing hole by the centrifugal force generated with the rotation of the motor shaft. And a second recess is formed on the end surface of the thrust disk facing the inner surface of the pressure chamber, and the bottom surface of the second recess is radially outward from the center of rotation of the thrust disk. A guide surface is formed which is inclined in a direction approaching the end surface of the thrust disk, and a sliding surface slidably contacting the guide surface and a pressure receiving surface facing the second gap are provided in the second recess. Accommodating a wedge-shaped second bearing pad having The second bearing pads,
The centrifugal force generated by the rotation of the motor shaft moves radially outward of the thrust disk, and moves in the axial direction of the motor shaft based on the inclination of the guide surface. A medium driving motor characterized in that a minute gap for generating the fluid pressure is formed between the pressure chamber and the inner surface of the pressure chamber. 6. A box-shaped housing, at least one disk-shaped magnetic recording medium housed in the housing, and a surface of the magnetic recording medium facing each other to record / reproduce data. A magnetic disk device comprising: a magnetic head; and a motor supported by the housing for rotating the magnetic recording medium at a high speed, wherein the motor rotates a rotor supporting the magnetic recording medium and the rotor rotating integrally with the rotor. A motor shaft, a frame having a bearing hole through which the motor shaft is rotatably inserted and a large-diameter pressure chamber continuous with the bearing hole, and the motor shaft rotating coaxially with the motor shaft together with the pressure The thrust disc housed in the chamber, the first gap between the motor shaft and the bearing hole, the axially facing end face of the thrust disc, and the inside of the pressure chamber. The second clearance between the motor shaft and the surface has a fluid filled therein, and the motor shaft is supported in a floating state in the radial direction and the axial direction by the fluid pressure generated in each clearance when the motor shaft rotates. And a first bearing on the outer peripheral surface of the motor shaft facing the inner peripheral surface of the bearing hole.
And a first bearing pad having a pressure receiving surface facing the first gap is housed in the first recess so as to be movable in the radial direction of the motor shaft. , A minute gap for generating the fluid pressure between the inner peripheral surface and the pressure receiving surface by advancing toward the inner peripheral surface of the bearing hole by the centrifugal force generated with the rotation of the motor shaft. And a second recess is formed on the end surface of the thrust disk facing the inner surface of the pressure chamber, and the bottom surface of the second recess is radially outward from the center of rotation of the thrust disk. A guide surface is formed which is inclined in a direction approaching the end surface of the thrust disk, and a sliding surface slidably contacting the guide surface and a pressure receiving surface facing the second gap are provided in the second recess. Accommodating a wedge-shaped second bearing pad having The second bearing pads,
The centrifugal force generated by the rotation of the motor shaft moves radially outward of the thrust disk, and moves in the axial direction of the motor shaft based on the inclination of the guide surface. A magnetic disk device, characterized in that a minute gap for generating the fluid pressure is formed between the pressure chamber and the inner surface of the pressure chamber.