KR20010010451A - A hydrodynamic bearing of the spindle motor - Google Patents

Abstract

PURPOSE: A hydrodynamic bearing of a spindle motor is provided to easily perform manufacturing work for forming a chamber by forming the chamber on a concentric circle with a shaft and a sleeve. CONSTITUTION: A hydrodynamic bearing of a spindle motor includes a shaft(10) in which grooves(11) for generating dynamic pressure are formed in the lower and upper parts of the outer diameter surface; a cylindrical sleeve(20) forcedly inserted into an inner diameter part of a cylindrical bearing holder, the shaft inserted into an inner diameter part, and minutely forming bearing gap(30) between the outer diameter surface of the inserted shaft; a chamber(40) equally outwardly expanding the inner diameter surface of the sleeve positioned between the grooves for generating dynamic pressure with forming a concentric circle with the shaft; a vent hole(50) having one end communicated with the chamber and the other end communicated with the outside in the inside of the sleeve for discharging only air flew into the chamber; and an oil induce groove(60) dividing the areas of oil and air in the chamber by indenting the part of the inner diameter surface of the sleeve in an axial direction.

Description

A hydrodynamic bearing of the spindle motor

The present invention relates to a hydrodynamic bearing of the spindle motor which is easy to process while maintaining the bearing stiffness while preventing oil from scattering by smooth discharge of air when the motor is driven. .

In general, devices requiring high capacity and speed, such as a hard disk drive of a computer, use a spindle motor in which a hydrodynamic bearing with less driving friction is applied than a ball bearing to achieve low noise and low non-repetitive runout (NRRO).

Hydrodynamic bearings in spindle motors usually have herringbone or spiral hydrodynamic pressure-generating grooves on the outer surface of the journal or on the upper and lower surfaces of the thrust plate, respectively. The oil is filled into the bearing clearance formed between the journal and the sleeve or the thrust plate and the sleeve, and the friction members are in contact with each other due to the dynamic pressure in the bearing clearance. It is a configuration to reduce the load.

On the other hand, a large amount of air bubbles exist in the oil supplied to the bearing gap, and these air particles are thermally expanded as the temperature increases due to frictional heat generated in the bearing gap at the beginning of driving. Since the oil is pushed out of the bearing gap, oil leaks to the outside.

Therefore, a journal bearing for supporting a current radial load or a thrust bearing for supporting an axial load, and a spindle motor in which these bearings are applied simultaneously are generally upper and lower as shown in FIG. A large amount of the bearing gap 3 between the outer diameter surface of the dynamic pressure generating groove journal 1 and the inner diameter surface of the sleeve 2 opposite thereto or the clearance gap 3 between the outer diameter surface of the thrust plate 4 and the sleeve 2. Air particles are collected, and these air is discharged through the vent hole 5 formed in the journal 1 or the thrust plate 4.

In other words, the vent hole 5 is formed in a member fixed to the rotating member so that air collected from the bearing gap 3 is smoothly discharged to the outside, thereby preventing oil leakage.

However, in such a configuration, when the motor is driven, the bearing gap 3 is not only induced with pure air, but also with oil, with the oil flowing out together with the air through the vent hole 5.

As such, when oil is leaked to the outside together with air, the inside of the motor is not only contaminated seriously, but also oil shortage in the bearing is promoted, and wear between friction members is accelerated, thereby shortening the service life.

Therefore, in recent years, the sleeve 2 facing the outer diameter surface between the dynamic pressure generating grooves 1a of the journal 1 as shown in FIG. A configuration in which the chamber 6 is formed to be eccentric to one side with respect to the axial center of the journal 1 by the inner diameter surface of has also been proposed.

That is, the journal 1 and the sleeve 2 are combined to have concentric circles, and at this time, the bearing gap 3 is formed at a minute interval between the outer diameter surface of the journal 1 and the inner diameter surface of the sleeve 2.

And the outer diameter surface of the journal 1 to form a herringbone or spiral-shaped dynamic pressure generating groove (1a) in the upper and lower portions to support the radial load by the dynamic pressure generated in the groove (1a), the upper and lower grooves ( On the inner diameter surface of the sleeve 2 which faces the outer diameter surface between 1a), a chamber 6 is formed to hold the oil supplied or recovered to the bearing clearance 3 axially eccentric with respect to the journal 1. It was made possible.

Therefore, the chamber 6 forms a space in which the gap is small on one side with respect to the outer diameter surface of the journal 1, and a gap is formed on the other side corresponding to the outer side of the journal 1, and the space-side sleeve 2 in which the gap is large is formed. In the inner diameter surface of the), the vent hole 5 is formed.

Such a configuration supports the radial load by dynamic pressure in the bearing gap 3 in which the dynamic pressure generating groove 1a is formed when the journal 1 is rotated by the motor drive as shown in FIG. At the same time, the oil derived from the bearing gap 3 is collected by the wedge effect into the narrow space of the main gap of the chamber 6, and the air generated in the bearing gap 3 is discharged from the chamber 6. As the gap is gathered into a wide space, the oil is supplied back to the bearing gap 3, and the air can be discharged to the outside through the vent hole 5 formed in the inner diameter surface of the sleeve 2.

However, such a configuration is not only applicable to the structure in which the journal 1 rotates, but also has a machining problem in that it is very difficult to eccentrically form the chamber 6 inside the sleeve 2.

The present invention is to compensate for the above-mentioned problems, the present invention has a main object to make the oil holding chamber formed on the shaft or the sleeve to be formed in a concentric configuration with the shaft to be easier processing .

In addition, the present invention is another object to prevent the unnecessary consumption of oil by allowing the oil induction groove is formed in the axial direction in the fixing member provided with the vent hole to be easily separated from the oil and air induced from the bearing gap.

In particular, it is another object of the present invention to maintain stable driveability with a smooth oil supply to the bearing clearance.

1 is a side cross-sectional view showing an example of a conventional hydrodynamic bearing in which a journal bearing and a thrust bearing are applied simultaneously;

Figure 2 is a side cross-sectional view of a hydrodynamic bearing showing another embodiment of the prior art,

3 is a cross-sectional view taken along the line A-A of FIG.

4 is a side sectional view showing a first embodiment according to the present invention;

5 and 6 are enlarged planar cross-sectional recessed parts according to a first embodiment of the present invention,

7 to 9 is a partial cross-sectional perspective view showing an embodiment of the oil induction groove according to the first embodiment of the present invention,

10 and 11 are planar cross-sectional views showing the distribution of oil and air according to the present invention;

12 is an oil distribution diagram in a chamber according to the first embodiment of the present invention;

13 is a side sectional view showing a second embodiment according to the present invention;

14 and 15 are enlarged planar cross-sectional views showing the oil distribution in the chamber according to the second embodiment of the present invention;

16 to 19 is a partial cross-sectional perspective view showing various shapes of the oil induction groove in the second embodiment of the present invention,

20 is a side sectional view showing a third embodiment according to the present invention;

21 and 22 are enlarged planar cross-sectional view showing the oil distribution according to the third embodiment of the present invention,

23 is a side sectional view showing a fourth embodiment according to the present invention;

24 and 25 are enlarged planar cross-sectional view showing the oil distribution according to the fourth embodiment of the present invention.

<Explanation of symbols for main parts of drawing>

10, 10a, 10b, 10c: shaft

20, 20a, 20b, 20c: sleeve

30, 30a, 30b, 30c: bearing clearance

40, 40a, 40b, 40c: chamber

50, 50a, 50b, 50c: Bant Hall

60, 60a, 60b, 60c: oil guide groove

70b, 70c: thrust plate

80b, 80c: bush

In order to achieve the above object, the present invention provides a space for retaining a certain amount of oil on the outer diameter surface of the shaft or the inner diameter surface of the sleeve, which is a fixing member located between the dynamic pressure generating grooves formed on the upper and lower outer diameter surfaces of the shaft. The in-chamber is formed, and the chamber-side fixing member has the most outstanding feature in that an oil-induced groove is formed so that oil and air are separated by a wedge effect in the chamber together with a vent hole for discharging air.

That is, the main surface of the fixing member having a minute bearing gap with respect to the rotating member is recessed in a uniform thickness, so that a chamber, which is an oil holding space, is formed so that the horizontal cross-sectional area is expanded more than the bearing gap. The main surface uniformly indented has a vent hole, which is a passage for discharging air to the outside, and a portion of the main surface is indented by the height of the chamber to form an oil-induced groove.

Hereinafter, described in detail with reference to the accompanying drawings a preferred embodiment of the present invention.

The present invention relates to a hydrodynamic bearing of a spindle motor applied to a hard disk driver and the like as described above, and is particularly applicable to both a type in which a shaft rotates and a type in which a shaft is fixed.

Figure 4 shows a first embodiment according to the present invention, in this embodiment is an improved structure of the bearing of the type of the shaft rotates in the structure consisting of only the journal bearing for supporting the load in the radial direction of the shaft.

That is, reference numeral 10 denotes a shaft, and the shaft 10 is a rotating member having dynamic pressure generating grooves 11 formed on the upper and lower portions of the outer diameter surface, respectively.

The sleeve 20 provided to the outside of the shaft 10 is a cylindrical fixing member that is integrally coupled to the inner diameter portion of the cylindrical bearing holder 90 and integrally coupled thereto, and the shaft 10 is rotatably inserted into the inner diameter portion. , Between the outer diameter surface of the inserted shaft 10 to form a fine bearing gap (30).

In addition, the main surface of the sleeve 20 located between the dynamic pressure generating grooves 11 formed on the upper and lower portions of the shaft 10 is recessed to have a uniform thickness in the inner diameter surface so as to form a concentric circle with the shaft 10. The chamber 40 having a larger horizontal cross-sectional area than the inner diameter of 20 is formed.

That is, the chamber 40 is a space in which a portion of the inner diameter surface of the sleeve 20 is uniformly inflated so that the gap with the shaft 10 is evenly extended. The chamber 40 maintains a predetermined amount of oil while maintaining an internal pressure. When the rising of the oil is supplied to the bearing gap 30 between the upper and lower shaft 10 and the sleeve 20.

In addition, one end of the sleeve 20 communicates with the chamber 40 and the other end of the sleeve 20 communicates with the outside so that the air flowing into the chamber 40 can be smoothly discharged to the outside. Make sure

The configuration as described above is substantially the same as the configuration of the conventional hydrodynamic bearing bar. However, in the present embodiment, the chamber 40 is formed in a concentric manner with the shaft 10, as described above. The main surface of the sleeve 20 is the most prominent feature is that the oil induction groove 60 is formed so that a portion of the inner diameter surface is concaved to the outside.

At this time, the oil induction groove 60 may be formed on a surface corresponding to the surface on which the vent hole 50 is formed, as shown in FIG. 5, and as shown in FIG. 6, the slits at which the tip of the vane hole 50 is formed. The inner diameter surface of the eve 20 may be concaved and formed.

In addition, the oil induction groove 60 may be formed in various shapes such as a "Ｕ" shape, a "자" shape, or a square as shown in FIGS. 7 to 9.

Looking at the operation according to the above embodiment as follows.

When electromagnetic force is generated by the interaction between the stator core and the magnet of the motor, the rotor hub 100 rotates, and at the same time, the shaft 10 integrally coupled with the rotor hub 100 rotates.

When the shaft 10 rotates, a strong dynamic pressure is generated in the bearing gap 30 between the shaft 10 and the sleeve 20 of the dynamic pressure generating groove 11 formed as the upper and lower outer peripheral surfaces of the shaft 10. The oil, which is filled in the chamber 40 between the dynamic pressure generating grooves 11, is supplied to the bearing gap 30 between the shaft 10 and the sleeve 20, and guided back to the center of the dynamic pressure generating grooves 11. The oil is thus circulated back to the chamber 40 due to the pressure rising above a certain level.

At this time, in the chamber 40, oil A is gathered to one side as shown in FIGS. 10 and 11 according to the position of the oil induction groove 60 formed on the inner diameter surface of the sleeve 20. Is formed eccentrically with respect to the shaft, and the wedge effect that separates the area where oil and air particles are located by the pressure difference in the chamber, that is, when the atmospheric pressure is 0, the air is collected at the place where the pressure in the chamber is 0 or less. This is made possible by the same effect that oil is collected.

Specifically, the oil in the front and rear portions of the oil induction groove 60 in the chamber 40 is filled with oil while exhibiting a pressure state higher than atmospheric pressure, and the portions other than the portion are filled with air particles at low pressure. This is clearly demonstrated by the experimental result showing the distribution of oil according to the pressure distribution in the chamber 40 as shown in FIG.

On the other hand, since the air particles filled in the chamber 40 are located at a portion where one end of the vent hole 50 is formed, these air particles can be smoothly discharged and removed to the outside through the vent hole 50.

In this way, the pressure is increased at the portion where the gap between the shaft 10 of the chamber 40 and the main surface of the sleeve 20 becomes narrow, and the oil to be filled again is between the upper and lower shafts 10 and the sleeve 20. It is fed back into the bearing clearance 30.

And the air particles collected in the chamber 40 is discharged to the outside through the vent hole 50, so that excessive pressure rise in the bearing clearance 30 is suppressed to prevent the oil from scattering.

In particular, in order to achieve the wedge effect in the past, since the chamber 40 is eccentrically formed to one side with respect to the inner diameter of the sleeve 20, it is very difficult to process the chamber 40. It is formed on the same center line as the inner diameter of the sleeve 20, and the oil-inducing groove 60 is simply formed on the inner diameter surface of the sleeve 20, so that the process required to manufacture the bearing while being very easy to process and Shortening of time is expected.

FIG. 13 is a view showing a second embodiment according to the present invention, in which a bearing is fixed in a structure in which only a journal bearing for supporting a radial load of the shaft is applied as in the first embodiment. The structure is improved.

Reference numeral 10a denotes a shaft, and the shaft 10a is a fixing member for forming dynamic pressure generating grooves 11a on the upper and lower portions of the outer diameter surface, respectively.

And the sleeve (20a) is forcibly fitted to the inner diameter surface of the rotor hub (100a) is rotatably coupled with the rotor hub (100a), the outer diameter surface of the shaft (10a) is inserted while the shaft (10a) is inserted into the inner diameter portion It is a cylindrical rotating member for finely forming a bearing gap (30a) between the.

In addition, the outer diameter surface between the dynamic pressure generating grooves 11a formed at the upper and lower portions of the shaft 10a forms a concentric circle with the shaft 10a so as to be indented in a uniform thickness so that the horizontal portion between the shaft 10a and the sleeve 20a is horizontal. The chamber 40a, which is a space in which the cross-sectional area is further expanded, is formed.

That is, the chamber 40a is a space in which a portion of the inner diameter surface of the shaft 10a is uniformly inflated so that the gap with the sleeve 20a is further expanded. The chamber 40a has a predetermined amount of oil, and the upper and lower shafts ( The oil is supplied to the bearing gap 30a between 10a) and the sleeve 20a.

In addition, one end of the shaft 10a communicates with the chamber 40a and the other end of the vent hole 50a communicates with the outside so that the air flowing into the chamber 40a can be smoothly discharged to the outside. do.

The configuration as described above is substantially the same as the configuration of the conventional hydrodynamic bearing bar. However, in the present embodiment, as described above, the chamber 40a is formed in a concentric manner with the shaft 10a and the sleeve 20a. The most prominent feature is that a part of the outer diameter surface of the main surface of the shaft 10a positioned in the chamber 40a is recessed outward so that the oil induction groove 60a is formed.

At this time, the oil induction groove 60a may be formed on a surface corresponding to the surface on which the vent hole 50a is formed, as shown in FIGS. 14 and 15, and the shaft 10a on which the tip of the vane hole 50a is formed. It is also possible to form the inner surface of the inner side by concave.

In addition, the oil induction groove 60a may be formed in various shapes such as a “Ｕ” shape or a “Ｖ” shape or a quadrangular or an outer diameter surface cut perpendicular to the axial direction as shown in FIGS. 16 to 19. Do.

Looking at the operation according to the above embodiment as follows.

When electromagnetic force is generated by the interaction between the stator core and the magnet of the motor, the rotor hub 100a rotates while simultaneously rotating the sleeve 20a integrally coupled to the rotor hub 100a.

When the sleeve 20a is rotated, the dynamic pressure generating groove 11a formed as the upper and lower outer circumferential surfaces of the shaft 10a generates strong dynamic pressure and fills the oil filled in the chamber 40a between the dynamic pressure generating grooves 11a. It leads to the bearing gap 30a between the shaft 10a and the sleeve 20a, which is led back to the center of the dynamic pressure generating groove 11a, and the oil thus induced is partially flowed back into the chamber 40a. Do it.

At this time, in the chamber 40a, oils A are gathered at both sides of the oil induction groove 60a, as shown in FIGS. 14 and 15, depending on the position of the oil induction groove 60a formed on the inner diameter surface of the shaft 10a. This is made possible by the same effect as the wedge effect in which the chamber is previously formed eccentrically with respect to the shaft, and the area where oil and air particles are located is separated by the pressure difference in the chamber.

Specifically, the oil in the front and rear portions of the oil induction groove 60a in the chamber 40a is filled with oil while exhibiting a pressure state higher than atmospheric pressure, and the portions other than the portion are filled with air particles at low pressure. This is clearly demonstrated by the experimental result showing the distribution of oil according to the pressure distribution in the chamber 40a as shown in FIG.

On the other hand, since the air particles filled in the chamber 40a are located at a portion where one end of the vent hole 50a is formed, these air particles are removed while being smoothly discharged to the outside through the vent hole 50a.

As the pressure increases at the portion where the gap between the shaft 10a of the chamber 40a and the main surface of the sleeve 20a is narrowed, the oil to be filled again is between the upper and lower shafts 10a and the sleeve 20a. It is resupplied to the bearing clearance 30a.

And the air particles collected in the chamber 40a is discharged to the outside through the vent hole (50a) to suppress excessive pressure rise in the bearing clearance (30a), thereby preventing the oil from scattering.

In particular, since the chamber 40a in the present embodiment is formed in a concentric configuration with the shaft 10a and the sleeve 20a, the chamber 40a is not only easy to process but also shortens the process and time required to manufacture the bearing. To make it possible.

20 shows a third embodiment according to the present invention, in which the bearing in this embodiment is provided with a journal bearing for supporting the load in the radial direction of the shaft and a thrust bearing for supporting the load in the axial direction at the same time. It is a structure that improves the type of shaft rotation.

The shaft 10b is a rotating member having dynamic pressure generating grooves 11b formed at upper and lower portions of the outer diameter surface, and the sleeve 20b is a cylindrical fixing member that is forced into the inner diameter portion of the cylindrical bearing holder 20b. As a configuration, the shaft 10b is rotatably inserted in the inner diameter portion, and the configuration in which the bearing gap 30b is minutely formed between the outer diameter surface of the inserted shaft 10b is the same as the structure of the first embodiment. .

In this embodiment, however, the thrust plate 70b of the flat plate is inserted into one end of the shaft 10b so as to be integrally coupled to each other, and a dynamic pressure generating groove is formed on the upper and lower surfaces of the thrust plate 70b, respectively. The upper surface and the lower surface on which the dynamic pressure generating grooves are formed face the sleeve 20b and the bush 80b so that a bearing gap 30b is finely formed therebetween.

Therefore, the dynamic pressure generating groove 11b of the shaft 10b supports the load in the radial direction of the shaft, and the dynamic pressure generating groove of the thrust plate 70b supports the load in the axial direction.

The chamber 40b is formed on the main surface of the sleeve 20b located between the dynamic pressure generating grooves 11b formed at the upper and lower portions of the shaft 10b, but the chamber 40b has a concentric circle with the shaft 10b. As a result, the inner diameter surface of the sleeve 20b is extended to the outside by a uniform thickness to form a larger space than the gap between the shaft 10b and the sleeve 20b.

On the other hand, the inside of the sleeve 20b communicates with the bearing gap 30b between the shaft 10b and the sleeve 20b and the bearing gap 30b between the thrust plate 70b, the sleeve 20b, and the bush 80b. A vent hole 50b is provided, and the vent hole 50b also discharges air that is collected on the outer diameter side of the chamber 40b and the thrust plate 70b to the outside while communicating with the outside.

The configuration as described above is substantially the same as the configuration of a fluid dynamic bearing in which a journal bearing and a thrust bearing are simultaneously provided. However, in the present embodiment, as described above, the chamber 40b is formed in a structure concentric with the shaft 10b. In particular, the main surface of the sleeve 20b facing the outer diameter surface of the chamber 40b and the thrust plate 70b has a portion of the inner diameter surface concaved to the outside so that the oil induction groove 60b is formed. It is characteristic.

At this time, the oil induction groove 60b of the chamber 40b has a surface corresponding to the vent hole 50b or the inner diameter surface of the tip side sleeve 20b of the vent hole 50b as shown in FIGS. 5 and 6. In the inner diameter surface of the sleeve 20b corresponding to the outer diameter surface of the thrust plate 70b, as shown in FIGS. 21 and 22, the end surface of the surface corresponding to the vent hole 50b or the tip hole 50b is formed. The inner diameter surface of the side sleeve 20b is recessed to be formed.

In addition, the oil induction groove 60b may be formed in various shapes such as a "Ｕ" shape, a "Ｖ" shape, or a quadrangle as illustrated in FIGS. 7 to 9.

Looking at the operation according to the above embodiment as follows.

When electromagnetic force is generated by the interaction between the stator core and the magnet of the motor, the rotor hub 100b rotates, and at the same time, the shaft 10b integrally coupled with the rotor hub 100b rotates, and the shaft 10b rotates. The dynamic pressure generating grooves 11b formed on the upper and lower outer peripheral surfaces of the shaft 10b and the dynamic pressure generating grooves formed on the upper and lower surfaces of the thrust plate 70b during the rotation of the shaft 10b generate strong dynamic pressure to the chamber 40b. The filled oil is supplied to the bearing gap 30b between the shaft 10b and the sleeve 20b and the bearing gap 30b between the thrust plate 70b, the sleeve 20b, and the bush 80b.

At this time, the outer side of the chamber 40b and the thrust plate 70b, as shown in Figs. 10, 11, 21, and 22 according to the formation position of the oil induction groove 60b formed on the inner diameter surface of the sleeve 20b. The oil (A) is collected on both sides of the oil induction groove (60b), which previously formed the chamber eccentrically with respect to the shaft, and the wedge effect that separates the area where the oil and air particles are located by the pressure difference in the chamber. It is possible by the same effect.

In detail, the front and rear portions of the oil induction groove 60b outside the chamber 40b and the thrust plate 70b are filled with oil while exhibiting a pressure state higher than atmospheric pressure. It is filled with air particles in the state, which is clearly proved by the experimental result showing the distribution of oil according to the pressure distribution in the chamber 40b as shown in FIG.

On the other hand, since the air particles filled outside the chamber 40b and the thrust plate 70b are located at the side of the vent hole 50b, these air particles can be smoothly discharged to the outside through the vent hole 50b. .

The oil to be filled in the portion where the gap between the main surface of the shaft 10b and the sleeve 20b of the chamber 40b is narrowed again is increased by the pressure, and the shaft 10b and the sleeve 20b are lower and upper. The upper and lower surfaces of the inter-bearing gap 30b and thrust plate 70b and the bearing gap 30b between the sleeve 20b and the bush 80b are resupplyed.

And since the air particles are discharged to the outside through the vent hole (50b) to suppress the excessive pressure rise in the bearing gap (30b) to prevent the scattering of oil.

In particular, in the past, the chamber was formed eccentrically to one side with respect to the inner diameter of the sleeve in order to achieve the wedge effect, but it was very difficult to process the chamber, but in this embodiment, the chamber 40b is concentric with the inner diameter of the sleeve 20b. Since the oil-inducing groove 60b is simply formed on the inner diameter surface of the sleeve 20b while being formed on the surface, the process is very easy and the process and time required to manufacture the bearing can be expected to be shortened.

FIG. 23 shows a fourth embodiment according to the present invention, in which the bearing in this embodiment has a journal bearing for supporting the load in the radial direction of the shaft and a thrust bearing for supporting the axial load as in the second embodiment. At the same time, in the configuration provided with the structure is improved structure that the shaft is fixed.

The shaft 10c is a fixing member which allows the dynamic pressure generating grooves 11c to be formed on the upper and lower portions of the outer diameter surface so as to be integrally coupled to the inner diameter portion of the bearing holder 90c, and the sleeve 20c is a rotor. A cylindrical rotating member that is forcibly fitted to the inner diameter surface of the hub 100c, the shaft 10c is inserted into the inner diameter portion, and a bearing gap 30c is minutely formed between the outer diameter surface of the inserted shaft 10c. The configuration to be the same is the same as that of the second embodiment.

However, in this embodiment, the thrust plate 70c of the flat plate is inserted into one end of the shaft 10c so as to be integrally coupled, and a dynamic pressure generating groove is formed on each of the upper and lower surfaces of the thrust plate 70c. The upper surface and the lower surface of the dynamic pressure generating groove is formed so as to face the sleeve 20c and the bush 80c so that the bearing gap 30c is formed finely therebetween.

Therefore, the dynamic pressure generating groove 11c of the shaft 10c supports the load in the radial direction of the shaft, and the dynamic pressure generating groove of the thrust plate 70c supports the load in the axial direction.

In addition, the outer diameter surface between the dynamic pressure generating grooves 11c formed at the upper and lower portions of the shaft 10c forms a concentric circle with the shaft 10c so as to be recessed in a uniform thickness so that the shaft 10c and the sleeve 20c are horizontal. The chamber 40c, which is a space in which the cross-sectional area is further expanded, is formed.

That is, the chamber 40c is a space in which a part of the inner diameter surface of the shaft 10c is uniformly infiltrated so that the gap with the sleeve 20c is further expanded. The chamber 40c has a predetermined amount of oil while the upper and lower shafts ( The oil is supplied to the bearing gap 30c between the 10c) and the sleeve 20c.

In addition, one end of the shaft 10c communicates with the outer space surface-side microcavity of the chamber 40c and the thrust plate 70c, and the other end thereof has a vent hole 50c that communicates with the outside, thereby forming the chamber 40c and the thrust. The air flowing into the microcavity on the outer diameter surface side of the plate 70c can be smoothly discharged to the outside.

The configuration as described above is substantially the same as the configuration of the hydrodynamic bearing which is simultaneously provided with the conventional journal bearing and the thrust bearing. However, in the present embodiment, as described above, the chamber 40c is formed concentrically with the shaft 10c. The most prominent feature is that the oil-inducing groove 60c is formed by injecting a part of the main surface into the indented outer diameter surface of the shaft 10c and the thrust plate 70c of the chamber 40c. to be.

At this time, the oil-inducing groove 60c of the chamber 40c side includes a surface corresponding to the vent hole 50c or a part of the outer diameter surface of the front end shaft 10c of the vent hole 50c, as shown in FIGS. 14 and 15. As shown in FIGS. 24 and 25, the outer surface of the thrust plate 70c or the outer diameter surface of the front end side shaft 10c of the vane hole 50c is partially formed as shown in FIGS. 24 and 25. It is formed by injecting.

In addition, the oil induction groove 60c may be formed in various shapes, such as a shape in which a "Ｕ" shape or a "Ｖ" shape or a square or an outer diameter surface is cut perpendicular to the axial direction as shown in FIGS. 16 to 19. It is possible.

Looking at the operation according to the above embodiment as follows.

When electromagnetic force is generated by the interaction between the stator core and the magnet of the motor, the rotor hub 100c rotates while simultaneously rotating the sleeve 20c integrally coupled to the rotor hub 100c.

When the sleeve 20c rotates, the dynamic pressure generating grooves 11c formed on the upper and lower outer peripheral surfaces of the shaft 10c and the dynamic pressure generating grooves formed on the upper and lower surfaces of the thrust plate 70c generate strong dynamic pressure. The oil filled in the chamber 40c is supplied to the bearing gap 30c between the shaft 10c and the sleeve 20c and the bearing gap 30c between the thrust plate 70c, the sleeve 20c, and the bush 80c. do.

At this time, according to the formation position of the oil induction groove 60c formed on the outer diameter surface of the shaft 10c and the thrust plate 70c in which the chamber 40c is formed, as shown in FIGS. 14, 15, 24 and 25 (A) is collected on both sides of the oil induction groove (60c), which previously formed the chamber eccentrically with respect to the shaft, the same as the wedge effect in which the area where the oil and air particles are located by the pressure difference in the chamber is separated. It is made possible by the effect.

In detail, the front and rear portions of the oil induction groove 60c outside the chamber 40c and the thrust plate 70c are filled with oil while exhibiting a pressure state higher than atmospheric pressure. It is filled with air particles in the state, which is clearly demonstrated by the experimental result showing the distribution of oil according to the pressure distribution in the chamber 40c as shown in FIG.

Meanwhile, since the air particles filled outside the chamber 40c and the thrust plate 70c are located at the side of the vant hole 50c, these air particles are formed in the shaft 10c and the thrust plate 70c. ) Can be removed by removing it to the outside smoothly.

The oil to be filled in the portion where the gap between the main surface of the shaft 10c and the sleeve 20c of the chamber 40c is narrowed again is increased by the pressure, and the upper shaft 10c and the sleeve 20c are lower. The upper and lower surfaces of the inter-bearing gap 30c and the thrust plate 70c and the bearing gap 30c between the sleeve 20c and the bush 80c are resupplyed.

And because the air particles are discharged to the outside through the vent hole (50c) to suppress the excessive pressure rise in the bearing gap (30c) to prevent the scattering of oil.

In particular, in the past, the chamber was formed eccentrically to one side with respect to the inner diameter of the sleeve in order to achieve the wedge effect, but the chamber was very difficult to process. Since the oil-inducing groove 60c is simply formed on the inner diameter surface of the sleeve 20c while being formed on the surface, the process and time required for manufacturing the bearing can be expected to be very easy, and the shortening of the process can be expected.

As described above, the present invention allows the chamber to be formed between the shafts and the sleeves to be concentrically formed between the dynamic pressure generating grooves of the shaft, thereby making it easier to perform the machining operations for forming the chamber, thereby improving product productivity. You can increase it.

In addition, by forming a vane hole, which is a passage through which air is discharged to the outside of the member and the thrust plate, which is fixed to the rotating member, a part of the main surface is recessed in the axial direction so that the oil-inducing groove 60 is formed. In particular, the oil and air particles which flow in the gap between the chamber and the thrust plate are separated from each other, and this prevents excessive pressure rise in the bearing due to the smooth discharge of air, thereby unnecessary oil consumption due to oil splashing. It is possible to economically control by suppressing, and in particular, by providing a stable lubrication to the bearing clearance to increase the bearing rigidity, there is a very useful effect of extending the service life.

Claims (26)

A shaft which is a rotating member having a groove for generating dynamic pressure on upper and lower outer diameter surfaces thereof, respectively; A sleeve, which is a cylindrical fixing member, which is integrally coupled to the inner diameter of the cylindrical bearing holder and integrally coupled to the inner diameter, so that a bearing gap is formed between the outer diameter surface of the shaft into which the shaft is inserted; A chamber for uniformly extending outwardly the inner diameter surface of the sleeve, which is located between the upper and lower portions of the shaft for generating a dynamic pressure, with the concentric circle with the shaft; A vent hole in which one end of the sleeve communicates with the chamber and the other end of the sleeve communicates with the outside to discharge only the air introduced into the chamber; An oil-inducing groove which allows a portion of the inner diameter surface of the sleeve located in the chamber to be formed in the axial direction by indenting a region of oil and air in the chamber; Hydrodynamic bearing of a spindle motor. The method of claim 1, wherein the oil induction groove A hydrodynamic bearing of a spindle motor having a concave portion of the main surface in the axial direction from a surface corresponding to the surface where the vent hole of the sleeve is formed. The method of claim 1, wherein the oil induction groove A hydrodynamic bearing of the spindle motor having a concave portion of the main surface including the tip of the vane hole in the axial direction from the surface where the vent hole of the sleeve is formed. The method of claim 1, wherein the oil induction groove Hydrodynamic bearings of spindle motors that are recessed in a "Ｕ" shape. The method of claim 1, wherein the oil induction groove Hydrodynamic bearings of spindle motors that are recessed in a "Ｖ" shape. The method of claim 1, wherein the oil induction groove Hydrodynamic bearings for spindle motors that are rectangular in shape. A shaft that is a fixing member having dynamic pressure generating grooves formed on upper and lower outer diameter surfaces thereof, respectively; A sleeve, which is a cylindrical rotating member that is tightly fitted to the inner diameter surface of the rotor hub and is integrally coupled to the inner diameter portion so as to form a fine bearing gap between the outer diameter surface of the shaft being inserted into the shaft portion; A chamber that is a space extending from the outer diameter surface between the upper portion and the lower portion of the dynamic pressure generating groove of the shaft so as to have a concentric circle with the shaft and uniformly inwardly; A vent hole for discharging air introduced into the chamber by allowing one end of the shaft to communicate with the chamber and the other end of the shaft to communicate with the outside; An oil-induced groove in which a portion of the outer diameter surface of the shaft located in the chamber is recessed inward so as to be formed in the axial direction so that oil and air regions in the chamber are separated from each other; Hydrodynamic bearing of a spindle motor. The method of claim 7, wherein the oil induction groove A hydrodynamic bearing of the spindle motor having a concave portion of the main surface in the axial direction on a surface corresponding to the surface on which the vent hole is formed in the concave outer diameter surface of the shaft. The method of claim 7, wherein the oil induction groove A hydrodynamic bearing of the spindle motor having a concave portion of the main surface including the tip of the vane hole in the axial direction on the surface of the concave outer diameter surface of the shaft. The method of claim 7, wherein the oil induction groove Hydrodynamic bearings of spindle motors that are recessed in a "Ｕ" shape. The method of claim 7, wherein the oil induction groove Hydrodynamic bearings of spindle motors that are recessed in a "Ｖ" shape. The method of claim 7, wherein the oil induction groove Hydrodynamic bearings for spindle motors that are rectangular in shape. The method of claim 7, wherein the oil induction groove A hydrodynamic bearing of a spindle motor whose outer diameter is cut perpendicular to the axial direction. A shaft which is a rotating member having a groove for generating dynamic pressure on upper and lower outer diameter surfaces thereof, respectively; A sleeve, which is a cylindrical fixing member, which is integrally coupled to the inner diameter of the cylindrical bearing holder and integrally coupled to the inner diameter, so that a bearing gap is formed between the outer diameter surface of the shaft into which the shaft is inserted; A thrust plate fitted into one end of the shaft and having a groove for generating a dynamic pressure on an upper surface and a lower surface thereof, and having a minute gap between the sleeve and the bush; A chamber for uniformly extending outwardly the inner diameter surface of the sleeve, which is located between the upper and lower portions of the shaft for generating a dynamic pressure, with the concentric circle with the shaft; A vent hole in which one end of the sleeve communicates with a gap between the outer diameter surface side of the chamber and the thrust plate, and the other end communicates with the outside so as to discharge air introduced into the chamber and the gap; A portion of the inner diameter surface of the sleeve located at the outer diameter side gap of the chamber and the thrust plate is recessed outward so as to be formed in the axial direction so that an oil and air region in the gap between the outer diameter surface side of the chamber and the thrust plate is formed. Oil-induced grooves to be distinguished from each other; Hydrodynamic bearing of a spindle motor. 15. The method of claim 14, wherein the oil induction groove A hydrodynamic bearing of a spindle motor having a configuration in which an inner circumferential surface of the sleeve has an axial concave portion corresponding to a surface where a vent hole is formed. 15. The method of claim 14, wherein the oil induction groove A hydrodynamic bearing of a spindle motor, wherein a part of the main surface is concaved in the axial direction on the surface of the sleeve in which the vent hole is formed. 15. The method of claim 14, wherein the oil induction groove Hydrodynamic bearings of spindle motors that are recessed in a "Ｕ" shape. 15. The method of claim 14, wherein the oil induction groove Hydrodynamic bearings of spindle motors that are recessed in a "Ｖ" shape. 15. The method of claim 14, wherein the oil induction groove Hydrodynamic bearings for spindle motors that are rectangular in shape. A shaft that is a fixing member having dynamic pressure generating grooves formed on upper and lower outer diameter surfaces thereof, respectively; A sleeve, which is integrally coupled to the inner diameter surface of the rotor hub and integrally coupled to the inner diameter portion, the sleeve being a cylindrical rotating member having a fine bearing gap between the outer diameter surface of the shaft being inserted while the shaft is inserted; A thrust plate coupled to one end of the shaft and integrally coupled to each other, and having a groove for generating a dynamic pressure on an upper surface and a lower surface thereof, and having a bearing gap between the sleeve and the bush; A chamber that is a space in which an outer diameter surface between the upper and lower portions of the shaft for generating a dynamic pressure has a concentric circle with the shaft and is indented and expanded inwardly uniformly; A vent hole in one end of the shaft communicating with the gap between the outer diameter surface side of the thrust plate and the other end in communication with the outside to discharge air introduced into the chamber; An oil-inducing groove which allows a portion of the outer diameter surface of the shaft located in the chamber to be inwardly formed so as to be formed in the axial direction so that oil and air regions in the gap between the outer diameter surface side of the chamber and the thrust plate are separated from each other; Hydrodynamic bearing of a spindle motor. 21. The method of claim 20, wherein the oil induction groove A hydrodynamic bearing of a spindle motor having a concave convex portion of the main surface corresponding to the concave outer surface of the shaft and the outer surface of the thrust plate, the surface of which is formed a vent hole. 21. The method of claim 20, wherein the oil induction groove A fluid dynamic bearing of a spindle motor having a recessed outer diameter surface of the shaft and a major surface of the thrust plate including a tip of the vane hole on the main surface of the thrust plate. 21. The method of claim 20, wherein the oil induction groove Hydrodynamic bearings of spindle motors that are recessed in a "Ｕ" shape. 21. The method of claim 20, wherein the oil induction groove Hydrodynamic bearings of spindle motors that are recessed in a "Ｖ" shape. 21. The method of claim 20, wherein the oil induction groove Hydrodynamic bearings for spindle motors that are rectangular in shape. 21. The method of claim 20, wherein the oil induction groove A hydrodynamic bearing of a spindle motor whose outer diameter is cut perpendicular to the axial direction.