KR20040072577A - A fluid dynamic bearing motor - Google Patents

Abstract

PURPOSE: A fluid dynamic bearing motor is provided to increase the assembly area between a hub and a shaft by increasing the diameter of the top of the shaft, while achieving improved driving characteristics of motor. CONSTITUTION: A fluid dynamic bearing motor comprises a housing(110); a hollow sleeve(120) coupled to the center of the housing; a core(130) arranged along the circumference of the housing and the sleeve; a thrust cover coupled to the bottom of the sleeve; a shaft(140) coupled to the sleeve; and a hub(150) coupled to the shaft, and which has a magnet(160) arranged at the inner surface of the hub. The shaft has a large diameter portion coupled to the hub, and a small diameter portion smaller than the large diameter portion. The sleeve includes an inner surface for forming a first journal bearing; first and second grooves formed in vicinity of the top of the inner surface of the sleeve; and a third groove formed in the vicinity of the bottom of the inner surface of the sleeve. The fluid dynamic bearing motor further includes a thrust plate(170) coupled to the small diameter portion of the shaft and to the first groove of the sleeve, and which forms a first thrust bearing; and a dynamic cover(190) coupled to the second groove of the sleeve, and which forms a second journal bearing and a second thrust bearing.

Description

A fluid dynamic bearing motor

The present invention relates to a fluid dynamic bearing spindle motor, in particular, despite the reduced design due to miniaturization, to suppress the conical vibration to improve the driving characteristics of the motor and to prevent the leakage of oil due to external impact and The present invention relates to a hydrodynamic bearing motor capable of preventing disassembly of an assembly part.

In general, a hydrodynamic bearing in a spindle motor usually has herringbone or spiral grooves formed on the inner surface of the sleeve or on the counter surface of the thrust plate, respectively. The oil is filled into the bearing clearance formed between the shaft and the sleeve or the thrust plate and the sleeve, so that the non-contact state between the friction members is caused by the dynamic pressure in the bearing clearance. To reduce the frictional load.

An example of a motor employing such a hydrodynamic bearing is shown in FIG. 1.

It consists of a fixing member consisting of the housing 10, the sleeve 20 and the core 30, and a rotating member composed of the shaft 40, the hub 50 and the magnet 60.

The sleeve 20 is formed in a hollow shape so that the shaft 40 is rotatably inserted, and a groove (not shown) for generating dynamic pressure is formed on the inner diameter surface thereof so that the fluid dynamic pressure in the radial direction of the shaft 40 can be obtained. Generates.

In addition, an annular thrust plate 70 is fixedly coupled to the lower end of the shaft 40 so as to be rotatable with the shaft 40 at the inner diameter of the sleeve 20, and at the inner center of the housing 10. The core 30 on which the coil is wound is fixedly mounted.

The thrust plate 70 is formed so that the fluid dynamic pressure in the axial direction is formed by the groove (not shown) for generating the dynamic pressure on the upper surface and the lower surface.

On the other hand, the lower end of the sleeve 20, the inner diameter is shielded by the cover plate 80 is blocked from the outside, the thrust plate 70 is rotated relative to the upper side of the cover plate (80).

In addition, a hub 50 is integrally coupled to an upper end of the shaft 40 rotatably inserted into the inner diameter portion of the sleeve 20, and the hub 50 has an inner diameter of an extended end portion as a cap shape opened downward. The magnet 60 is installed on the surface to face the outer diameter surface of the core 30.

In such a structure, a fine oil gap is formed between the inner diameter surface of the sleeve 20 and the shaft 40 and the thrust 70, and the oil gap is filled with oil having a predetermined viscosity. .

The oil in the oil gap generates dynamic pressure between the fixing member and the rotating member which is rotated against the surface thereof so that the shaft 40 can be stably driven.

However, the motor employing the fluid dynamic bearing of the above structure has the following problems.

First, in the case of a portable product such as a notebook, it is required to be lightweight and thin, and the motor employed therein is also required to be miniaturized. In this case, a journal formed between the inner diameter surface of the sleeve 20 and the outer diameter surface of the shaft 40. The length of the bearing is shortened, making it vulnerable to conical vibration.

Second, when the motor is required to be miniaturized, the area of the assembly part is also designed to be reduced. In this case, there is a problem that the assembly parts are separated even by a small external shock.

Third, when an abnormal external shock is applied to the motor having the above configuration, oil leaks from the journal bearing adjacent to the outside air and contaminates the motor.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a hydrodynamic bearing motor whose structure is improved to effectively prevent conical vibration while being able to design in a compact size.

Another object of the present invention is to provide a fluid dynamic bearing motor that can prevent the departure of the assembly by the external shock by securing the assembly area of the assembly even though the design is compact.

Still another object of the present invention is to provide a fluid hydrodynamic bearing motor capable of effectively preventing oil leakage from the hydrodynamic bearing portion even when an external impact is applied.

1 is a cross-sectional view showing a conventional hydrodynamic bearing motor,

2 is a cross-sectional view showing a hydrodynamic bearing motor of an embodiment of the present invention;

3 is an exploded view of the main part of FIG.

4 is a schematic view showing a shaft in which an oil groove is formed;

Figure 5 is an enlarged view of the main portion of Figure 2 showing an oil leak prevention structure,

6a and 6b are a plan view showing a thrust plate,

7 and 8 is a cross-sectional view of another embodiment of the fluid hydrodynamic bearing motor of the present invention;

9 to 11 are cross-sectional views of another embodiment of the hydrodynamic bearing motor of the present invention.

* Explanation of symbols for main parts of the drawings

110.Housing 120.Sleeve

121 ... 1st receiving groove (of the sleeve) 122 ... 2nd receiving groove of the (sleeve)

123 ... inside of the sleeve 124 ... inside of the sleeve

125 ... 3rd receiving groove 130

140 ... shaft 141 ...

150 ... hub 160 ... magnet

170 thrust plate 180 thrust cover

190 ... Dynamic pressure cover

The present invention to achieve the above object is a housing, a hollow sleeve fixedly coupled to the center of the housing, a core provided along the circumference of the housing or the sleeve, the thrust cover is fixed to the lower end of the sleeve In the fluid hydrodynamic bearing motor having a shaft rotatably coupled to the sleeve in fluid dynamic pressure, and a hub coupled to the shaft and rotated together and the magnet is provided on its inner peripheral surface facing the core,

The shaft is formed of a large diameter portion coupled to the hub and a small diameter portion smaller in diameter than the large diameter portion,

The sleeve is rotatably coupled to the small diameter portion of the shaft and the inner diameter surface is formed between the outer peripheral surface of the small diameter portion and the first journal bearing to form a first journal bearing, the first formed adjacent to the upper side of the inner diameter surface, A second accommodation groove and a third accommodation groove formed adjacent to the lower side of the inner diameter surface and to which the thrust cover is fixed is formed;

A thrust plate fixed to the small diameter portion of the shaft and rotatably coupled to the first accommodation groove, and having an oil interposed between the bottom surface of the first accommodation groove to form a first thrust bearing;

It is fixed to the second receiving groove and rotatably coupled to the large diameter portion of the shaft, the oil is interposed between the inner circumferential surface and the large diameter portion to form a second journal bearing, the bottom surface and the upper surface of the thrust plate It is characterized in that it is provided with a dynamic pressure cover to form a second thrust bearing with an oil interposed therebetween.

In the fluid hydrodynamic bearing motor of the present invention, an annular rib is formed on a bottom surface of the central portion of the hub, and a protruding jaw extending inwardly of the annular rib is formed at an upper end of the dynamic pressure cover, and an inner peripheral surface of the annular rib is formed on an outer peripheral surface of the protruding jaw. It characterized in that the inclined outer diameter surface is inclined at a predetermined angle to face the first space, the first space portion is formed between the inner peripheral surface of the annular rib and the inclined outer diameter surface.

In addition, the inclined surface extending in the upper direction is formed inside the upper end of the sleeve, characterized in that the second space portion is formed between the outer peripheral surface of the annular rib.

In addition, the large diameter portion of the hub and the shaft may be integrally formed, and the thrust plate and the shaft may be integrally formed.

On the other hand, the present invention to achieve the above object is a housing, a hollow sleeve fixedly coupled to the center of the housing, a core provided along the circumference of the housing or the sleeve, the coupling is fixed to the lower end of the sleeve In a fluid dynamic bearing motor having a thrust cover, a shaft rotatably coupled to the sleeve with fluid dynamic pressure, and a hub provided with a magnet coupled to the shaft to rotate together and opposed to the core on an inner circumferential surface thereof,

The shaft is formed of a large diameter portion coupled to the hub and a small diameter portion smaller in diameter than the large diameter portion,

The sleeve is rotatably coupled to the small diameter portion of the shaft and the inner diameter surface is formed between the outer peripheral surface of the small diameter portion and the first journal bearing to form a first journal bearing, the first formed adjacent to the upper side of the inner diameter surface, A second accommodation groove and a third accommodation groove formed adjacent to the lower side of the inner diameter surface and to which the thrust cover is fixed is formed;

A thrust plate fixed to the small diameter portion of the shaft and rotatably coupled to the first accommodation groove, and having an oil interposed between the bottom surface of the first accommodation groove to form a first thrust bearing;

It is fixed to the second receiving groove and rotatably coupled to the large diameter portion of the shaft, the oil is interposed between the inner circumferential surface and the large diameter portion to form a second journal bearing, the bottom surface and the upper surface of the thrust plate It has a dynamic pressure cover spaced apart at regular intervals,

The center of the magnet is relatively higher than the center of the core, characterized in that the hub is configured to receive the force by the electromagnetic force in the downward direction.

The present invention also provides a housing, a hollow sleeve fixedly coupled to a central portion of the housing, a core provided along a circumference of the housing or the sleeve, and fixedly coupled to a lower end of the sleeve. In a fluid dynamic bearing motor having a thrust cover, a shaft rotatably coupled to the sleeve with fluid dynamic pressure, and a hub provided with a magnet coupled to the shaft to rotate together and opposed to the core on an inner circumferential surface thereof,

The shaft is formed of a large diameter portion coupled to the hub and a small diameter portion smaller in diameter than the large diameter portion,

The sleeve is rotatably coupled to the small diameter portion of the shaft and the inner diameter surface to form a first journal bearing with an oil interposed between the outer peripheral surface of the small diameter portion, the first and second adjacent to the upper side of the inner diameter surface formed A receiving groove and a third receiving groove which is formed adjacent to the lower side of the inner diameter surface is fixed to the thrust cover is formed,

A thrust plate fixed to the small diameter portion of the shaft and rotatably coupled to the first accommodation groove, and having an oil interposed between the bottom surface of the first accommodation groove to form a first thrust bearing;

It is fixed to the second receiving groove and rotatably coupled to the large diameter portion of the shaft, the oil is interposed between the inner circumferential surface and the large diameter portion to form a second journal bearing, the bottom surface and the upper surface of the thrust plate It has a dynamic pressure cover spaced apart at regular intervals,

The magnetic body is attached and fixed to the housing facing the lower surface of the magnet,

The hub is characterized in that configured to receive the force by the magnetic force in the downward direction.

The present invention also provides a housing, a hollow sleeve fixedly coupled to a central portion of the housing, a core provided along a circumference of the housing or the sleeve, and fixedly coupled to a lower end of the sleeve. In a fluid dynamic bearing motor having a thrust cover, a shaft rotatably coupled to the sleeve with fluid dynamic pressure, and a hub provided with a magnet coupled to the shaft to rotate together and opposed to the core on an inner circumferential surface thereof,

The shaft is formed of a large diameter portion coupled to the hub and a small diameter portion smaller in diameter than the large diameter portion,

The sleeve is rotatably coupled to the small diameter portion of the shaft and the inner diameter surface is formed between the outer peripheral surface of the small diameter portion and the first journal bearing to form a first journal bearing, the first formed adjacent to the upper side of the inner diameter surface, A second accommodation groove and a third accommodation groove formed adjacent to the lower side of the inner diameter surface and to which the thrust cover is fixed is formed;

A thrust plate fixed to the small diameter portion of the shaft and rotatably coupled to the first accommodation groove and spaced apart from the bottom surface of the first accommodation groove by a predetermined distance;

It is fixed to the second receiving groove and rotatably coupled to the large diameter portion of the shaft, the oil is interposed between the inner circumferential surface and the large diameter portion to form a second journal bearing, the bottom surface and the upper surface of the thrust plate It is provided with a dynamic pressure cover to form a second thrust bearing with an oil interposed therebetween,

The center of the magnet is relatively lower than the center of the core, characterized in that the hub is configured to receive the force by the electromagnetic force in the upward direction.

According to the characteristics of the present invention, the hydrodynamic bearing motor of the present invention by reducing the separation of the assembly by the external impact, despite the small design of the motor by increasing the assembly area by increasing the diameter of the upper end of the shaft coupled to the hub, The thrust bearing is formed in the middle part of the shaft, and the journal bearing is applied to the upper and lower parts to suppress the conical vibration, improving the driving characteristics of the motor, and forming a space for preventing leakage between the sleeve and the hub. To prevent oil from leaking from the old journal bearing.

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

The hydrodynamic bearing motor of the embodiment of the present invention is applied to, for example, a spindle motor for a hard disk driver that is employed in a portable product such as a notebook, and suppresses the occurrence of conical vibration despite the miniaturization of the notebook with the miniaturization of the notebook Prevents the assembly from coming off due to external shock and prevents oil leakage.

2 and 3 showing the hydrodynamic bearing motor of the present invention, it is a housing 110, a hollow sleeve 120 fixedly coupled to the center of the housing 110, and the sleeve Core 130 is provided along the outer periphery of the eve 120, the thrust cover 180 is coupled to the lower end of the sleeve 120 and rotatably coupled to the sleeve 120 in fluid dynamic pressure And a hub 150 coupled to the shaft 140 to rotate together with a magnet 160 opposite to the core 130 on an inner circumferential surface thereof.

The shaft 140 is formed of a large diameter portion 141 coupled to the hub 150 and a small diameter portion 142 having a smaller diameter than the large diameter portion 141.

The sleeve 120 has an inner diameter surface 123 to which the small diameter portion 142 of the shaft 140 is rotatably coupled, and an oil is interposed between the small diameter portion 142 and the outer circumferential surface of the small diameter portion 142 to form a first journal bearing. ), First and second receiving grooves 121 and 122 formed adjacent to the upper side of the inner diameter surface 123, and are formed adjacent to the lower side of the inner diameter surface 123 and the thrust cover 180 Has a structure in which the third receiving groove 125 is formed to be coupled and fixed.

In addition, the thrust plate 170 is fixed to the small diameter portion 142 of the shaft 140, the thrust plate 170 is rotatably coupled to the first receiving groove 121.

An oil is interposed between the bottom surface of the thrust plate 170 and the bottom surface 126 of the first accommodating groove 121 to form a first thrust bearing.

In addition, a hollow dynamic pressure cover 190 is fixedly coupled to the second accommodation groove 122, and the large diameter portion 141 of the shaft 140 is rotatably coupled to the dynamic pressure cover 190.

An oil is interposed between the inner circumferential surface 191 of the dynamic pressure cover 190 and the large diameter portion 141 to form a second journal bearing, and the bottom surface of the dynamic pressure cover 190 and the upper surface of the thrust plate 170 are separated from each other. An oil is interposed between them to form a second thrust bearing.

On the outer circumferential surfaces of the large diameter portion 141 and the small diameter portion 142 of the shaft 140, oil grooves 191a and 192a are formed to guide the interposed oil to form a fluid dynamic pressure. It is. The oil groove may be formed in the sleeve 120 and the dynamic pressure cover 190 which face the shaft 40.

In addition, as shown in FIGS. 6A and 6B, the thrust plate 170 has an inward spiral groove 171 or an herringbone shape oil groove 172. The oil groove may be formed on the bottom surface of the dynamic pressure cover 190 or the bottom surface 126 of the sleeve 120 facing the thrust plate 170.

Referring to FIGS. 2, 3, and 5 for explaining the prevention of oil leakage due to external impact, an annular rib 151 is formed on the bottom of the center of the hub 150, and the dynamic pressure cover 190 A protruding jaw 193 extending inwardly of the annular rib 151 is formed at an upper end thereof, and an outer circumferential surface of the protruding jaw 193 is inclined to a predetermined angle to face an inner circumferential surface of the annular rib 151. Face 192 is formed. The outer diameter of the protruding jaw 193 has a larger upper end than the lower end.

By the above configuration, the first space portion 201 is formed between the inner circumferential surface of the annular rib 151 and the inclined outer diameter surface 192.

In addition, an inclined surface 124 extending upwardly is formed inside the upper end of the sleeve 120, and a second space part 202 is formed between the outer circumferential surface of the annular rib 151.

In the fluid dynamic bearing motor of the above embodiment, the rotational force is generated by the electromagnetic force between the core 130 and the magnet 160 to rotate the rotating member consisting of the thrust plate 170, the shaft 140 and the hub 150. Drive it.

At this time, the rotating member is rotatably supported by the dynamic pressure of the oil interposed in the first and second journal bearing parts and the first and second thrust bearing parts.

The hydrodynamic bearing motor having the above-described configuration employs a thrust plate 170 in the middle portion of the shaft 140 having a small contribution to the conical vibration suppression force, and constitutes the first and second thrust bearings, and the first and second thrust bearings at the upper and lower portions thereof. By splitting the two journal bearings, the conical oscillation can be suppressed without reducing the length of the journal bearing despite the miniaturized design of the motor, and the load bearing capacity can be secured by the first and second thrust bearings to ensure stable driving of the motor. To make it possible.

In addition, by configuring the upper portion of the shaft 140 to be assembled with the hub 150 with a large diameter portion 141 having a larger diameter, the assembly area is increased to prevent the assembly portion from being separated despite an external impact.

In general, when the diameter of the shaft 140 is increased, the power consumption increases and the amount of heat generated also increases, and thus the diameter of the shaft 140 may not be large. Therefore, in the embodiment of the present invention, the upper end portion of the shaft 140, which is an assembly portion, is formed by the large diameter portion 141 and the lower portion is formed by the small diameter portion 142, thereby designing power consumption and heat generation within an appropriate range.

In addition, in the embodiment of the present invention, the gap between the second journal bearing is made larger than the gap between the first journal bearing and the change in power consumption and bearing stiffness due to the increase in diameter in the large diameter portion 141 of the shaft 140 is suppressed. In addition, in this case, the cumulative assembly tolerance due to the assembly of the sleeve 120 and the dynamic pressure cover 190 may be compensated.

On the other hand, when the oil is separated from the bearing portion due to the flow or external impact of the notebook when carrying, it is possible to prevent the oil leakage to the outside by forming the double space 201, 202 using the capillary phenomenon.

In addition, the surface tension is generated due to the microgap 203 between the upper surface of the dynamic pressure cover 190 and the bottom of the hub 150 and the microgap 204 between the top of the sleeve 120 and the bottom of the hub 150. The oil can be effectively prevented from leaking.

On the other hand, referring to Figure 7 showing another embodiment of the fluid hydrodynamic bearing motor of the present invention, which is a large diameter portion 141 of the hub 150 and the shaft 140 is formed integrally, in this case the assembly of the motor Reduced number improves assembly

Figure 8 shows a hydrodynamic bearing motor of another embodiment, which is the thrust plate 170 and the shaft 140 is formed integrally, thereby reducing the number of assembly parts of the motor to improve the assembly.

Other components of FIGS. 7 and 8 are the same as in the above embodiment, and thus detailed descriptions thereof will be omitted.

On the other hand, referring to Figure 9 showing another embodiment of the present invention (the name and reference numerals for the same components are the same as the above embodiment, a detailed description thereof will be omitted) This is the small diameter portion 142 of the shaft 140 A thrust plate which is fixed to the first receiving groove 121 and rotatably coupled to the first receiving groove 121 and having an oil interposed between the bottom surface 126 of the first receiving groove 121 to form a first thrust bearing ( 170),

It is fixed to the second receiving groove 122 and the large diameter portion 141 of the shaft 140 is rotatably coupled, the oil is interposed between the inner circumferential surface 191 and the large diameter portion 141, the second Forming a journal bearing, and having a dynamic pressure cover 190 spaced apart a predetermined distance (b) between the bottom surface and the top surface of the thrust plate 170,

The center of the magnet 160 is relatively higher than the center of the core 130 by a height (a), so that the hub 150 is subjected to the force by the electromagnetic force in the downward direction is stable as one first thrust bearing It was configured to operate.

In addition, referring to Figure 10 showing another embodiment of the motor of the present invention, it is spaced apart a certain interval (b) between the dynamic pressure cover 190 and the upper surface of the thrust plate 170, the of the magnet 160 The magnetic body 115 is fixed to the housing facing the lower surface portion, and the hub 150 is configured to receive a force by the magnetic force in the downward direction.

Also in this case, it was comprised so that it might become stable operation also as one 1st thrust bearing.

Referring to FIG. 11 of another embodiment, it is fixed to the small diameter portion 142 of the shaft 140 and rotatably coupled to the first accommodation groove 121 and the bottom of the first accommodation groove 121 A thrust plate 170 spaced apart from the surface 126 by a predetermined distance (d),

It is fixed to the second receiving groove 122 and the large diameter portion 141 of the shaft 140 is rotatably coupled, the oil is interposed between the inner circumferential surface 191 and the large diameter portion 141, the second It has a dynamic pressure cover 190 to form a journal bearing, the oil is interposed between the bottom surface and the top surface of the thrust plate 170 to form a second thrust bearing,

The center of the magnet 160 is relatively lower than the center of the core 130 by a height (c), so that the hub 150 is configured to receive the force by the electromagnetic force in the upward direction as one second thrust bearing Ensure stable operation.

The present invention as described above is not limited to the above embodiments without departing from the spirit and scope of the present application can be practiced with a number of modifications.

The present invention as described above has the following advantages.

First, by increasing the diameter of the upper end of the shaft coupled to the hub to increase the assembly area prevents the separation of the assembly by the external shock despite the small motor design.

Second, thrust bearings are formed in the middle part of the shaft, and 1,2 journal bearings are used in the upper and lower parts to suppress the conical vibration, thereby improving the driving characteristics of the motor.

Third, by forming a space between the sleeve and the hub to prevent oil from leaking from the journal bearing adjacent to the outside due to external impacts.

Claims (9)

A housing, a hollow sleeve fixedly coupled to the center of the housing, a core provided along the circumference of the housing or the sleeve, a thrust cover fixedly coupled to a lower end of the sleeve, and a fluid dynamic pressure to the sleeve. In a fluid dynamic bearing motor having a shaft rotatably coupled to the shaft and a hub coupled to the shaft and rotated together and a magnet opposite the core is provided on an inner circumferential surface thereof. The shaft 140 is formed of a large diameter portion 141 coupled to the hub 150 and a small diameter portion 142 having a diameter smaller than that of the large diameter portion 141, The sleeve 120 has an inner diameter surface 123 to which the small diameter portion 142 of the shaft 140 is rotatably coupled, and an oil is interposed between the small diameter portion 142 and the outer circumferential surface of the small diameter portion 142 to form a first journal bearing. ), First and second receiving grooves 121 and 122 formed adjacent to the upper side of the inner diameter surface 123, and are formed adjacent to the lower side of the inner diameter surface 123 and the thrust cover 180 A third accommodation groove 125 is formed is coupled is fixed, Coupling is fixed to the small diameter portion 142 of the shaft 140 and rotatably coupled to the first receiving groove 121, the oil is interposed between the bottom surface 126 of the first receiving groove 121. Thrust plate 170 to form a first thrust bearing, It is fixed to the second receiving groove 122 and the large diameter portion 141 of the shaft 140 is rotatably coupled, the oil is interposed between the inner circumferential surface 191 and the large diameter portion 141, the second And a dynamic pressure cover (190) which forms a journal bearing, and an oil is interposed between the bottom surface and an upper surface of the thrust plate (170) to form a second thrust bearing. The method of claim 1, wherein the annular rib 151 is formed on the bottom of the central portion of the hub 150, A protruding jaw 193 extending inwardly of the annular rib 151 is formed at an upper end of the dynamic pressure cover 190, and an outer circumferential surface of the protruding jaw 193 is opposed to an inner circumferential surface of the annular rib 151. The inclined outer diameter surface 192 inclined at an angle is formed, Fluid hydrodynamic bearing motor, characterized in that the first space portion 201 is formed between the inner circumferential surface of the annular rib 151 and the inclined outer diameter surface (192). According to claim 2, wherein the inclined surface 124 extending upwardly in the upper end of the sleeve 120, the second space portion 202 is formed between the outer peripheral surface of the annular rib 151 Fluid hydrodynamic bearing motor, characterized in that. The hydrodynamic bearing motor according to any one of claims 1 to 3, wherein the large diameter portion (141) of the hub (150) and the shaft (140) are integrally formed. The hydrodynamic bearing motor according to any one of claims 1 to 3, wherein the thrust plate (170) and the shaft (140) are integrally formed. A housing, a hollow sleeve fixedly coupled to the center of the housing, a core provided along the circumference of the housing or the sleeve, a thrust cover fixedly coupled to a lower end of the sleeve, and a fluid dynamic pressure to the sleeve. In a fluid dynamic bearing motor having a shaft rotatably coupled to the shaft and a hub coupled to the shaft and rotated together and a magnet opposite the core is provided on an inner circumferential surface thereof. The shaft 140 is formed of a large diameter portion 141 coupled to the hub 150 and a small diameter portion 142 having a diameter smaller than that of the large diameter portion 141, The sleeve 120 has an inner diameter surface 123 to which the small diameter portion 142 of the shaft 140 is rotatably coupled, and an oil is interposed between the small diameter portion 142 and the outer circumferential surface of the small diameter portion 142 to form a first journal bearing. ), First and second receiving grooves 121 and 122 formed adjacent to the upper side of the inner diameter surface 123, and are formed adjacent to the lower side of the inner diameter surface 123 and the thrust cover 180 A third accommodation groove 125 is formed is coupled is fixed, Coupling is fixed to the small diameter portion 142 of the shaft 140 and rotatably coupled to the first receiving groove 121, the oil is interposed between the bottom surface 126 of the first receiving groove 121. Thrust plate 170 to form a first thrust bearing, It is fixed to the second receiving groove 122 and the large diameter portion 141 of the shaft 140 is rotatably coupled, the oil is interposed between the inner circumferential surface 191 and the large diameter portion 141, the second Forming a journal bearing, and having a dynamic pressure cover 190 spaced apart a predetermined distance (b) between the bottom surface and the top surface of the thrust plate 170, The center of the magnet 160 is relatively higher than the center of the core 130, the hydrodynamic bearing motor, characterized in that the hub is configured to receive a force by the electromagnetic force in the downward direction. A housing, a hollow sleeve fixedly coupled to the center of the housing, a core provided along the circumference of the housing or the sleeve, a thrust cover fixedly coupled to a lower end of the sleeve, and a fluid dynamic pressure to the sleeve. In a fluid dynamic bearing motor having a shaft rotatably coupled to the shaft and a hub coupled to the shaft and rotated together and a magnet opposite the core is provided on an inner circumferential surface thereof. The shaft 140 is formed of a large diameter portion 141 coupled to the hub 150 and a small diameter portion 142 having a diameter smaller than that of the large diameter portion 141, The sleeve 120 has an inner diameter surface 123 to which the small diameter portion 142 of the shaft 140 is rotatably coupled, and an oil is interposed between the small diameter portion 142 and the outer circumferential surface of the small diameter portion 142 to form a first journal bearing. ), First and second receiving grooves 121 and 122 formed adjacent to the upper side of the inner diameter surface 123, and are formed adjacent to the lower side of the inner diameter surface 123 and the thrust cover 180 A third accommodation groove 125 is formed is coupled is fixed, Coupling is fixed to the small diameter portion 142 of the shaft 140 and rotatably coupled to the first receiving groove 121, the oil is interposed between the bottom surface 126 of the first receiving groove 121. Thrust plate 170 to form a first thrust bearing, It is fixed to the second receiving groove 122 and the large diameter portion 141 of the shaft 140 is rotatably coupled, the oil is interposed between the inner circumferential surface 191 and the large diameter portion 141, the second Forming a journal bearing, and having a dynamic pressure cover 190 spaced apart a predetermined distance (b) between the bottom surface and the top surface of the thrust plate 170, The magnetic body 115 is fixed to the housing facing the lower surface of the magnet 160, The hydrodynamic bearing motor, characterized in that the hub is configured to receive a force by a magnetic force in the downward direction. A housing, a hollow sleeve fixedly coupled to the center of the housing, a core provided along the circumference of the housing or the sleeve, a thrust cover fixedly coupled to a lower end of the sleeve, and a fluid dynamic pressure to the sleeve. In a fluid dynamic bearing motor having a shaft rotatably coupled to the shaft and a hub coupled to the shaft and rotated together and a magnet opposite the core is provided on an inner circumferential surface thereof. The shaft 140 is formed of a large diameter portion 141 coupled to the hub 150 and a small diameter portion 142 having a diameter smaller than that of the large diameter portion 141, The sleeve 120 has an inner diameter surface 123 to which the small diameter portion 142 of the shaft 140 is rotatably coupled, and an oil is interposed between the small diameter portion 142 and the outer circumferential surface of the small diameter portion 142 to form a first journal bearing. ), First and second receiving grooves 121 and 122 formed adjacent to the upper side of the inner diameter surface 123, and are formed adjacent to the lower side of the inner diameter surface 123 and the thrust cover 180 A third accommodation groove 125 is formed is coupled is fixed, It is fixed to the small diameter portion 142 of the shaft 140 and rotatably coupled to the first receiving groove 121 and spaced apart from the bottom surface 126 of the first receiving groove 121 (d). Thrust plate 170 to be, It is fixed to the second receiving groove 122 and the large diameter portion 141 of the shaft 140 is rotatably coupled, the oil is interposed between the inner circumferential surface 191 and the large diameter portion 141, the second It has a dynamic pressure cover 190 to form a journal bearing, the oil is interposed between the bottom surface and the top surface of the thrust plate 170 to form a second thrust bearing, The center of the magnet (160) is relatively lower than the center of the core 130, the hydrodynamic bearing motor, characterized in that the hub is configured to receive the force by the electromagnetic force in the upward direction. 9. A fluid dynamic pressure according to any one of claims 1, 2, 3, 6, 7, and 8, wherein the second journal bearing gap is larger than the first journal bearing gap. Bearing motor.