KR20010010450A - A spindle motor having hemi-spherical bearing - Google Patents

Abstract

PURPOSE: A spindle motor having a hemi-spherical bearing is provided to improve the stability by locating the center of gravity of the hemi-spherical bearing at a position lower than a load supporting position. CONSTITUTION: A holder(11) to which a lower end of a shaft(12) is fixed is press-fitted to a housing(10). A stator core(20) is positioned on a supporter(13) attached to the housing(10). The stator core(20) stacks a plurality of thin films. A magnet(31) is attached to a rotor hub(30) so as to be opposite to the outer end of the stator core(20). A bearing bush is fixed to the upper surface of the rotor hub(30). The bearing bush is located on the inner peripheral portion of the stator core(20) and on a same axis as the shaft(12). A hemi-spherical bearing is received in an upper groove(41) of the bearing bush.

Description

A spindle motor having hemi-spherical bearing

The present invention relates to a spindle motor to which a hemi-spherical bearing is applied, and more particularly to a hemispherical bearing which provides a more stable driveability by allowing the entire center of gravity of the hemisphere bearing to be located at the bottom than the load bearing position. It relates to a spindle motor having a.

Generally, spindle and thrust bearings are applied to spindle motors that are used in hard disk drivers or laser printers that require high-speed driving. I am trying to.

That is, the journal bearing supports the load in the radial direction of the shaft when the motor is driven by the dynamic pressure generating groove formed on the outer circumferential surface of the shaft, and the thrust bearing is formed by the dynamic pressure generating groove formed on the upper and lower surfaces of the thrust plate. By supporting the load in the axial direction during the driving of the vibration and noise is to maintain a stable driveability.

On the other hand, if the oil is used as a lubricant in the bearing, there is a problem that the contamination of the motor inside and the flow rate are reduced due to the oil scattering. Recently, the dynamic pressure in the bearing is generated by air instead of oil. Usage is increasing gradually.

In such a pneumatic bearing, in particular, in recent years, a motor applying a hemispherical bearing for supporting both the radial load of the shaft and the load in the axial direction has been proposed and used in some cases.

Fig. 1 shows a side cross-section of a spindle motor to which such a hemisphere bearing is applied, the motor being largely divided into a housing 1, a stator core 2, a rotor hub 3, a bearing bush 4, and a hemisphere 50. Is done.

The housing 1 is a support member of a flat plate, and the holder 1a is pressed into the housing 1 in a flange shape, and the lower end of the shaft 1b is firmly fitted to the inner diameter portion of the holder 1a by firm fit. Is fixed.

In addition, a supporter 1c having a seating surface provided as an upper end portion is attached to the housing 1, and a stator core 2 integrally formed by stacking a plurality of thin plates on the upper surface of the supporter 1c has a separate fastening means. Or it is firmly fixed by the joining means.

On the other hand, the outer side of the stator core (2) is provided with a rotor hub (3) to which the magnet (3a) is attached to have a predetermined gap with the outer end, the bearing bush (4) on the upper surface of the rotor hub (3) To be integrally coupled.

The bearing bush 4 has a central portion penetrated up and down, and the hemispherical grooves 4a and 4b of the same size, which are curved inwardly or in opposite directions, respectively, to the upper and lower surfaces of the penetrated central portion. To form.

In the upper groove 4a and the lower groove 4b of the bearing bush 4, a groove for generating pressure 5a is formed on the outer circumferential surface while having a small gap with the inner diameter surface of each groove 4a, 4b. Each hemisphere 5 is accommodated.

At this time, the hemisphere 5 is firmly fixed to the shaft 1b passing through the center of the bearing bush 4 by interference fit.

The spindle motor provided as such a structure causes mutual electromagnetic force to be generated between the stator core 2 and the magnet 3a by the power input to the stator core 2, and in this case, the driving force is caused to rotate the rotor hub 3. Let's do it.

At this time, as the bearing bush 4 integrally coupled with the rotor hub 3 rotates, outside air flows into the grooves 4a and 4b formed at the upper and lower portions of the bearing bush 4 by the rotational force. These outside air flows along the dynamic pressure generating grooves 5a of the hemispheres 5 respectively accommodated in the grooves 4a and 4b, thereby generating a strong dynamic pressure, and thus the inner diameters of the hemispheres 5 and the grooves 4a and 4b. The non-contact with the surface is maintained, and also the support of the radial and axial loads of the shaft of the bearing bush 4 at the same time to maintain a stable driveability.

However, in the aforementioned structure, the bearing bush 4 and the hemisphere 5 have a disadvantage in that the height H1 is excessively increased, so that the center of gravity WC in the shaft 1b is forced to move downward, and this center of gravity WC ) Is in particular lower than the span S1 between the radial and axial load bearing positions of the shaft between the upper and lower grooves 4a, 4b and the hemisphere 5 of the bearing bush 4 When the rotation of the unstable rotation moment is generated by the centrifugal force causes a problem that the vibration increases or causes an imbalance.

The present invention is to compensate for the above problems, the present invention is to provide a more stable driveability by allowing the center of gravity is positioned between the span between the load bearing position of the upper and lower hemisphere while moving the installation height of the overall hemisphere bearing Its main purpose is to make it possible.

In addition, the present invention has another object to enable a thinner as the overall height of the bearing is lowered.

1 is a side cross-sectional view showing a spindle motor having a conventional hemisphere bearing;

2 is a side sectional view of a spindle motor according to the present invention;

<Explanation of symbols for main parts of drawing>

10 housing 12 shaft

20: stator core

30: rotor hub 40: bearing bush

41: upper groove 42: lower groove

50: upper hemisphere 60: lower hemisphere

In order to achieve the above object, the present invention includes a housing in which the holder is fixed to the lower end of the shaft;

A stator core laminated with a plurality of thin plates seated and fixed to a supporter attached to the housing;

A rotor hub having a magnet attached to face the outer end of the stator core;

Is fixedly coupled to the upper surface of the rotor hub, the upper surface and the lower surface of the central portion vertically penetrating inwardly so that the hemispherical grooves are provided while making the inner diameter of the lower side grooves smaller than the upper side grooves, but the lower A side groove having a bearing bush positioned on an inner diameter portion of the stator core and formed on the same axis as the shaft;

An upper hemisphere that is received in an upper groove of the bearing bush and forced to the shaft;

A lower hemisphere which is accommodated in the lower groove of the bearing bush and is provided with a smaller outer diameter than the upper hemisphere so as to be forced into the shaft;

Is coupled so that the center of gravity of the shaft is positioned between the upper and lower hemispheres.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a side cross-sectional view of a spindle motor according to the present invention, and includes a housing 10, a stator core 20, a rotor hub 30, a bush 40, an upper hemisphere 50, and a lower hemisphere 60. The configuration consisting of) is the same as before.

In other words, the housing 10 is a support portion which allows the spindle motor of the present invention to be firmly attached to and supported by the device. A flange-shaped holder 11 is fixed to the housing 10 by interference fitting, and the holder 11 Inner diameter portion of the shaft 12 is similarly to be firmly fixed by interference fit.

In addition, the housing 10 has a supporter 13 attached to the upper periphery of the outer periphery where the holder 11 is fitted to a predetermined height and a seating surface is provided on the upper end thereof, and a plurality of upper surfaces of the supporter 13 are attached to the housing 10. The stator core 20 integrally molded by laminating thin plates is seated to be firmly fixed by fastening or bonding.

On the other hand, the outer side of the stator core 20 to face the outer end to have a predetermined gap so that the rotor hub 30 to which the magnet 31 is attached.

The bearing bush 40 is firmly coupled to the upper surface extending to the top of the stator core 20 of the rotor hub 30 by caulking, etc. At this time, the center of the bearing bush 40 penetrates up and down. Hemispherical grooves 41 and 42 are formed in the upper and lower surfaces of the penetrated center, respectively, inwardly or in a direction opposite to each other.

At this time, the lower groove 42 forms a hemisphere with a smaller inner diameter than the upper groove 41, and in particular, the lower portion of the bearing bush 40 in which the lower groove 42 is formed is located at the inner diameter of the stator core 20. Be sure to

The upper groove 41 and the lower groove 42 of the bearing bush 40 have minute gaps with the inner diameter surfaces of the grooves 41 and 42, respectively, and have grooves for generating dynamic pressure on the outer circumferential surfaces 51 and 61. ) Is formed so that the upper hemisphere 50 and the lower hemisphere 60 are received.

At this time, the lower hemisphere 60 is smaller than the upper hemisphere 50 so as to be proportional to the inner diameter difference between the upper and lower grooves 41 and 42 in the bearing bush 40, these upper hemispheres 50 And the lower hemisphere 60 is to be firmly fixed to the shaft 12 penetrating through the center of the bearing bush (40).

Therefore, the lower hemisphere 60 is located at the inner diameter of the stator core 20 similarly to the lower groove 42 of the bearing bush 40.

The operation of the present invention according to the configuration as described above is the electromagnetic force by the interaction between these magnetic fields while forming each magnetic field in the stator core 20 and the magnet 31 by the power input to the stator core 20 as in the prior art Is generated, and the electromagnetic force at this time causes the driving force to rotate the rotor hub 30 rotatably supported.

When the rotor hub 30 is rotated as described above, the bearing bush 40 integrally coupled with the rotor hub 30 rotates, and grooves are formed on the upper and lower portions of the bearing bush 40 by the rotational force at this time. Outside air flows into the 41 and 42.

These outside air flows along the dynamic pressure generating grooves 51 and 61 of the upper hemisphere 50 and the lower hemisphere 60 accommodated in the grooves 41 and 42 to generate a strong dynamic pressure, and by this dynamic pressure The inner diameter surfaces of the grooves 41 and 42 and the outer diameter surfaces of the upper hemisphere 50 and the lower hemisphere 60 smoothly rotate the bearing bush 40 in a non-contact state.

On the other hand, when the bearing bush 40 rotates, each of the upper hemisphere 50 and the lower hemisphere 60 has a point that simultaneously supports the radial and axial loads of the shaft, and the distance between these points, that is, span S2. In the center of gravity (WC) of the shaft 12 is located.

In more detail, the positions of the upper hemisphere 50 and the lower hemisphere 60 fitted to the shaft 12 are moved downward than before, and the size of the lower hemisphere 60 is reduced rather than the upper hemisphere 50. The center of gravity (WC) in the shaft 12 is moved upward compared to the previous time, the center of gravity (WC) at this time simultaneously the radial and axial load of the shaft in the upper half (50) and the lower half (60) It is to be located between the supporting point-to-point span (S2).

When the center of gravity WC in the shaft 12 is located between the point-to-point span S2 that simultaneously supports the radial and axial loads of the shaft in the upper hemisphere 50 and the lower hemisphere 60. Since the action of the rotation moment by the centrifugal force is not generated at all during the rotation of the bearing bush 40, it is possible to significantly reduce the vibration and noise when driving the motor.

In addition, the removal of the rotation moment can maintain the bearing load capacity more stably, which makes the driving performance more stable.

In particular, since the lower hemisphere 60 is positioned downward to the inner diameter of the stator core 20, the formation height H2 of the bearing bush 40 is lowered as a whole, thereby facilitating thinning of the motor.

Therefore, the present invention is reduced by the simple structure improvement of reducing the size of the lower groove 42 of the bearing bush 40 and the lower hemisphere 60 received therein so that they are located in the inner diameter of the stator core 20. When the motor is driven, the center of gravity WC of the shaft 12 is positioned between the point-to-point span S2 that simultaneously supports the radial and axial loads of the shaft in the upper hemisphere 50 and the lower hemisphere 60. As a result, the driving performance is improved while exhibiting more stable driving performance, and the thickness of the motor is made thinner, thereby providing a very useful effect of promoting the thinning of the device.

Claims (1)

A housing 10 into which the holder 11 to which the lower end of the shaft 12 is fixed is fitted; A stator core 20 having a plurality of thin plates stacked and fixed to the supporter 13 attached to the housing 10; A rotor hub (30) having a magnet (31) attached to face the outer end of the stator core (20); The inner diameter of the lower groove 42 is fixedly coupled to the upper surface of the rotor hub 30, and the hemispherical grooves curved inward are respectively formed on the upper surface and the lower surface of the central portion vertically penetrating. A bearing bush 40 to be provided while being made small, but having the lower groove 42 positioned on the inner diameter of the stator core 20 and being formed on the same axis as the shaft 12; An upper hemisphere 50 which is accommodated in the upper groove 41 of the bearing bush 40 and has a dynamic pressure generating groove 51 formed on the hemispherical outer circumferential surface and is forcibly fitted to the shaft 12; And a dynamic pressure generating groove 61 is formed on the hemispherical outer circumferential surface of the bearing bush 40 while being accommodated in the lower side groove 42 of the bearing bush 40, and has an outer diameter smaller than that of the upper hemisphere 42 to force the shaft 12. Since the lower hemisphere 60 to be fitted is coupled, the center of gravity WC of the shaft 12 is between the points that simultaneously support the radial and axial loads of the shafts of the upper hemisphere 50 and the lower hemisphere 60. Spindle motor with hemispherical bearing to be positioned at.