KR20130051091A - Hydrodynamic bearing assembly and motor including the same - Google Patents

Abstract

The present invention relates to a fluid dynamic bearing assembly and a motor including the same, wherein the shaft is rotatably fitted in at least one of a sleeve having a shaft hole and an outer diameter of the shaft and an inner diameter of the sleeve when the shaft is rotated. First and second dynamic pressure generating grooves provided up and down in the axial direction so as to cause dynamic pressure in the lubricating fluid filled in the bearing gap formed between the shaft and the sleeve, and generating the first dynamic pressure provided on the upper side in the axial direction. The groove may be provided to pump the lubricating fluid downward in the axial direction.

Description

Hydrodynamic bearing assembly and motor including the same

The present invention relates to a fluid dynamic bearing assembly and a motor comprising the same.

A hard disk drive (HDD), which is one of information storage devices, is a device that reproduces data stored on a disk using a read / write head or records data on a disk.

Such a hard disk drive requires a disk drive capable of driving a disk, and a small spindle motor is used for the disk drive.

The compact spindle motor employs a fluid dynamic bearing assembly, and a shaft is formed by a fluid pressure generated by the oil through an oil in a bearing gap between a shaft, which is one of the rotating members of the fluid dynamic bearing assembly, and a sleeve, which is one of the fixing members. Will be supported.

In addition, the fluid dynamic bearing assembly is a journal bearing is formed by the dynamic pressure generation of the fluid, in order to form such a journal bearing by forming a dynamic pressure generating groove of various shapes on the outer peripheral surface of the shaft or the inner peripheral surface of the sleeve to concentrate the fluid To play a role. However, due to repeated use, the ridge forming the groove wears out, so that the dynamic pressure generating groove cannot be pumped in the originally intended direction.

In addition, according to the trend of more miniaturized electronic devices, the spindle motor used therein is also miniaturized. In the case of such a small motor, the bearing span is shortened, which makes it difficult to show the performance of the motor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fluid dynamic bearing assembly which allows the pumping of a fluid to be continuously made in a pumping direction originally intended even though wear of a ridge portion forming a dynamic pressure generating groove while forming a bearing span length as long as possible. It is an object to provide a motor.

A hydrodynamic bearing assembly according to an embodiment of the present invention includes a sleeve having a shaft hole so that the shaft is rotatably fitted; And an axial upward and downward direction provided at at least one of an outer diameter of the shaft and an inner diameter of the sleeve so as to cause dynamic pressure to a lubricating fluid filled in a bearing gap formed between the shaft and the sleeve when the shaft rotates. And first and second dynamic pressure generating grooves, and the first dynamic pressure generating grooves provided on the upper side in the axial direction may be provided to pump the lubricating fluid downward in the axial direction.

In the hydrodynamic bearing assembly according to an embodiment of the present invention, the first dynamic pressure generating groove may be spiral or spiral.

In the hydrodynamic bearing assembly according to an embodiment of the present invention, the second dynamic pressure generating groove may have a herringbone shape.

In the hydrodynamic bearing assembly according to an embodiment of the present invention, the shaft may include a stopper that is engaged with the lower end of the sleeve in the axial direction.

In the hydrodynamic bearing assembly according to an embodiment of the present invention, a thrust dynamic pressure groove may be provided on at least one of an upper surface of the stopper or a lower surface of the sleeve.

In the hydrodynamic bearing assembly according to an embodiment of the present invention, the lubricating fluid may be filled in a full-fill shape in a bearing gap formed between the shaft and the sleeve.

In the fluid dynamic bearing assembly according to an exemplary embodiment, a plain journal bearing may be provided between the first dynamic pressure generating groove and the second dynamic pressure generating groove.

In the fluid dynamic bearing assembly according to an embodiment of the present invention, the hub is fixed to the upper end of the shaft and extends radially outward; further comprising an oil interface is formed between the upper surface of the sleeve and the lower surface of the hub is oil It can be sealed.

In the hydrodynamic bearing assembly according to an embodiment of the present invention, at least one of the upper surface of the sleeve and the lower surface of the hub may include a pumping groove to pump the lubricating fluid in a direction opposite to the oil interface.

In the hydrodynamic bearing assembly according to an embodiment of the present invention, at least one of the upper surface of the sleeve and the lower surface of the hub may include a taper portion to widen the gap between the sleeve and the hub toward the radially outer side.

In the hydrodynamic bearing assembly according to an embodiment of the present invention, a pumping groove for pumping a lubricating fluid in an opposite direction of an oil interface to a tapered portion or a counterpart member provided on at least one of an upper surface of the sleeve and a lower surface of the hub is provided. It may be provided.

In the hydrodynamic bearing assembly according to an embodiment of the present invention, the pumping groove may have a spiral shape or a spiral shape.

In the hydrodynamic bearing assembly according to an embodiment of the present invention, the hub may include a circumferential wall portion extending downward in an axial direction so as to correspond to an upper outer portion of the sleeve.

Spindle motor according to an embodiment of the present invention is a base member; A stator core mounted on the base member, provided to correspond to a magnet provided on the rotating member, and having a coil wound to generate an electromagnetic force; And a hydrodynamic bearing assembly according to an embodiment of the present invention mounted to the base member.

According to the fluid dynamic bearing assembly and the motor including the same according to the present invention, the span length of the hydrodynamic bearing can be secured as long as possible, and even if the ridge portion forming the dynamic pressure generating groove is worn out, Pumping can be done continuously, thus improving the performance of the motor.

1 is a schematic cross-sectional view showing a motor including a fluid dynamic bearing assembly according to a first embodiment of the present invention,
FIG. 2 is an enlarged view of a portion A of FIG. 1 and is a sectional view showing the structure of a fluid dynamic bearing assembly according to a first embodiment of the present invention;
Figure 3 shows a cross-sectional view of a sleeve according to the first embodiment of the present invention,
4 is a perspective view showing a hub according to the first and second embodiments of the present invention;
5 is a schematic cross-sectional view showing a motor including a fluid dynamic bearing assembly according to a second embodiment of the present invention;
FIG. 6 is an enlarged view of a portion A ′ of FIG. 5, and is a cross-sectional view illustrating a structure of a fluid dynamic bearing assembly according to a second exemplary embodiment of the present invention.
7 shows a cross-sectional view of a sleeve according to a second embodiment of the invention.

Hereinafter, with reference to the drawings will be described in detail a specific embodiment of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventive concept. Other embodiments falling within the scope of the inventive concept may readily be suggested, but are also considered to be within the scope of the present invention.

The same reference numerals are used to designate the same components in the same reference numerals in the drawings of the embodiments.

1 is a schematic cross-sectional view showing a motor including a fluid dynamic bearing assembly according to a first embodiment of the present invention, and FIG. 2 is an enlarged view of a portion A of FIG. 1, and a fluid dynamic bearing according to a first embodiment of the present invention. 3 is a cross-sectional view showing the structure of the assembly, Figure 3 shows a cross-sectional view of a sleeve according to a first embodiment of the present invention, Figure 4 is a perspective view showing a hub according to the first and second embodiments of the present invention .

1 to 4, a motor 400 including a hydrodynamic bearing assembly 100 according to a first embodiment of the present invention may include a fluid hydrodynamic bearing assembly including a shaft 110 and a sleeve 120. 100), the rotor 200 including the hub 210 and the stator 300 including the core 310 to which the coil 320 is wound may be included.

The hydrodynamic bearing assembly 100 may include a shaft 110, a sleeve 120, and a hub 210, wherein the hub 210 constitutes the rotor 200, which will be described later. It may be a configuration constituting the assembly 100.

First, when defining a term for the direction, the axial direction refers to the up and down direction with respect to the shaft 110, as seen in Figure 1, the radially outer and inward direction relative to the shaft 110 relative to the hub It may mean the center direction of the shaft 110 with respect to the outer end direction of the 210 or the outer end of the hub (210).

In addition, when the terms are defined, an end portion (top, bottom, end, etc.) of a member, a hole, or a groove, etc. may refer to an end portion of the configuration or a portion adjacent to the end portion of the configuration.

The shaft 110 is a member rotatably inserted into the shaft hole of the sleeve 120 to be described below. An axial lower end of the shaft 110 may be provided with a stopper 111 having a diameter larger than that of the shaft 110. An upper surface of the stopper 111 may be caught by a lower end of the sleeve 120 to be described below to limit the injuries of the shaft 110. The stopper 111 may be integrally formed with the shaft 110 or provided as a separate member, and may be fixed to the shaft 110 in various ways, such as press-fitting or adhesive bonding.

The lower surface of the sleeve 120 corresponding to the upper surface of the stopper 111 may be provided with a thrust dynamic pressure groove 127 capable of generating a thrust dynamic pressure. Of course, the thrust dynamic pressure groove 127 may be provided on an upper surface of the stopper 111 corresponding to the lower surface of the sleeve 120. The thrust dynamic pressure groove 127 may be used as long as the thrust dynamic pressure groove 127 has a shape capable of generating dynamic pressure by pumping a fluid such as a herringbone, a screw thread, or a spiral.

The sleeve 120 may support the shaft 110 so that the upper end of the shaft 110 protrudes upward in the axial direction, and forge Cu or Al, or sinter Cu-Fe alloy powder or SUS powder. Can be formed.

Here, the shaft 110 is inserted to have a small gap with the shaft hole of the sleeve 120 serves as a bearing gap (C), the bearing gap is filled with oil (lubricating fluid) and the shaft 110 Is formed in at least one of an outer diameter of the sleeve 120 and an inner diameter of the sleeve 120 and includes a first dynamic pressure generating groove 123 and a first dynamic pressure generating groove 125 which are provided in an axial up and down direction. Rotation of the rotor 200 can be smoothly supported. In addition, the journal bearing 125 may be provided so that the lubricating fluid is pumped downward in the axial direction. That is, the force of the pumping force of the first dynamic pressure generating groove 123 and the first dynamic pressure generating groove 125 may be directed downward in the axial direction. The lubricating fluid may be filled in a full-fill shape in a bearing gap formed between the shaft 110 and the sleeve 120.

The journal bearing 125 may be formed on an inner surface of the sleeve 120 or an outer circumferential surface of the sleeve 120, which is inside the shaft hole of the sleeve 120, and the shaft 110 is the sleeve 120. When rotating in the shaft hole of the dynamic pressure is formed by the lubricating fluid filled in the bearing gap (C) to allow the shaft 110 to be smoothly rotated inside the shaft hole of the sleeve 120.

However, the journal bearing 125 is not limited to being provided on the inner side of the sleeve 120 as mentioned above, it is also possible to be provided on the outer diameter of the shaft 110, the number is not limited. Let's find out.

The journal bearing 125 may be any one of a herringbone shape, a spiral shape, and a thread shape, and may have any shape as long as it generates a radial dynamic pressure.

However, in the present invention, the first dynamic pressure generating groove 123 provided on the upper side in the axial direction may be provided in a spiral or threaded shape to allow the lubricating fluid to be pumped downward in the axial direction. This is to solve the disadvantage that the pumping force may be weakened or the pumping direction may be changed when the ridge portion forming the dynamic pressure generating groove is worn in the prior art, and in the present invention, the first and second dynamic pressure generating grooves are axially up and down. The first dynamic pressure generating groove 123 is configured to continuously pump the lubricating fluid downwardly in the axial direction irrespective of the wear of the ridge portion, thereby forming the journal bearing 125 having the 123 and 124. Will always be predictable.

On the other hand, the shape of the second dynamic pressure generating groove 124 may be any shape. That is, the second dynamic pressure generating groove 124 may be provided in any one of a herringbone shape, a spiral shape, and a threaded shape.

In addition, a reservoir 121 having an inner circumferential surface drawn in the radially outer side of the sleeve 120 may be provided between the first dynamic pressure generating groove 123 and the second dynamic pressure generating groove 124. The reservoir 121 may store the lubricating fluid so that the negative pressure does not occur even if the pumping of the fluid occurs by the dynamic pressure generating groove.

Furthermore, the stopper 111 may be provided at the lower end of the shaft 110 and may be engaged with the lower surface of the sleeve 120 to limit the injuries of the rotating member (shaft, rotor, etc.). Thus, in the present invention, the lower surface of the sleeve 120 may be provided with a thrust dynamic pressure groove 127 capable of generating thrust dynamic pressure. Of course, the thrust dynamic pressure groove 127 may be provided on an upper surface of the stopper corresponding to the lower surface of the sleeve 120. The thrust dynamic pressure groove 127 may be used as long as the thrust dynamic pressure groove 127 has a shape capable of generating dynamic pressure by pumping a fluid such as a herringbone, a screw thread, or a spiral.

In addition, the sleeve 120 has a stepped groove 128 in which the stopper 111 may be seated radially outward at a lower end portion of the sleeve 120 so that the stopper 111 may be caught at a lower end thereof. It can be provided.

In addition, the present invention may further include a hub 210 fixed to the upper end of the shaft 110 extending radially outward, the oil interface between the upper surface of the sleeve 120 and the lower surface of the hub 210. May be formed to seal the oil. Accordingly, in the present invention, at least one of the upper surface of the sleeve 120 and the lower surface of the hub 210 has a tapered portion 126 to widen the gap between the sleeve 120 and the hub 210 toward the radially outer side. It can be provided.

In addition, at least one of the upper surface of the sleeve 120 and the lower surface of the hub 210 may be provided with a pumping groove 215 to pump the lubricating fluid in a direction opposite to the oil interface to prevent leakage of the fluid. Further, the pumping groove 215 may be formed in the mating member (sleeve 120 or hub 210) corresponding to the position where the taper portion 126 or the taper portion 126 is provided. Here, the pumping groove 215 may be provided in a spiral or spiral shape.

The sleeve 120 may include a circulation hole (not shown) formed to communicate the upper and lower portions of the sleeve 120, which maintains an equilibrium by dispersing the pressure of oil in the fluid dynamic bearing assembly 100. It may be possible to, and to move the bubbles and the like existing in the fluid dynamic bearing assembly 100 to be discharged by the circulation.

In addition, the axial lower portion of the sleeve 120 may be coupled to the sleeve 120 while maintaining a gap, and the gap may include a base cover 130 for receiving oil.

The base cover 130 may function as a bearing for receiving oil in a gap between the sleeves 120 and supporting the lower surface of the shaft 110 as itself.

The hub 210 may be coupled to the shaft 110, and constitute the fluid dynamic bearing assembly 100 with a rotating member that rotates in association with the shaft 110, and at the same time, may configure the rotor 200. Hereinafter, the rotor 200 will be described in detail.

The rotor 200 is a rotating structure rotatably provided with respect to the stator 300, and the hub 210 having an annular magnet 220 having a ring-shaped magnet 220 corresponding to each other at a predetermined interval from the core 310 to be described later on the outer circumferential surface thereof. ) May be included.

In other words, the hub 210 may be a rotating member coupled to the shaft 110 to rotate in conjunction with the shaft 110.

Here, the magnet 220 may be provided as a permanent magnet in which the N pole and the S pole are alternately magnetized in the circumferential direction to generate a magnetic force of a predetermined intensity.

In addition, the hub 210 is a first cylindrical wall portion 212 to be fixed to the upper end of the shaft 110, a disc portion 214 extending radially outward from the end of the first cylindrical wall portion 212, The second cylindrical wall portion 216 may protrude downward from the radially outer end portion of the disc portion 214, and the magnet 220 may be coupled to an inner circumferential surface of the second cylindrical wall portion 216.

The hub 210 may include a main wall portion 230 extending downward in an axial direction so as to correspond to an upper outer portion of the sleeve 120.

In addition, in the present invention, an oil interface is formed between the upper surface of the sleeve 120 and the lower surface of the hub 210 to seal the oil. Accordingly, in the present invention, at least one of the upper surface of the sleeve 120 and the lower surface of the hub 210 has a tapered portion 126 to widen the gap between the sleeve 120 and the hub 210 toward the radially outer side. It can be provided.

In addition, at least one of the upper surface of the sleeve 120 and the lower surface of the hub 210 may be provided with a pumping groove 215 to pump the lubricating fluid in a direction opposite to the oil interface to prevent leakage of the fluid. Further, the pumping groove 215 may be formed in the mating member (sleeve 120 or hub 210) corresponding to the position where the taper portion 126 or the taper portion 126 is provided. Here, the pumping groove 215 may be provided in a spiral or spiral shape.

In addition, a leakage preventing part 170 may be formed on at least a portion of the upper surface of the sleeve 120 and the lower surface of the hub 210 facing each other. The leakage preventing part 170 may minimize the gap to form a labyrinth seal on at least some of the portions where the upper surface of the sleeve 120 and the lower surface of the hub 210 face each other. The labyrinth seal may serve as a sealing that can prevent leakage by itself since the gap between members is minimized.

In addition, when the gas-liquid interface is formed at a portion where the upper surface of the sleeve 120 and the lower surface of the hub 210 face each other, as in the present invention, a horizontal seal is formed (sealing portion is formed in the outer diameter direction), thereby leaking fluid. It may be desirable to pay more attention to.

On the other hand, a thrust dynamic pressure groove (not shown) is formed in at least one of an upper surface of the sleeve 120 and a lower surface of the hub 210 in a portion where the water leakage preventing unit 170 in which the labyrinth seal is formed is formed and thrust. Dynamic pressure can be generated. In the present invention, since the force of the first and second dynamic pressure generating grooves 123 and 124 which are the journal bearings 125 may be provided to pump the lubricating fluid downward in the axial direction, the leak prevention may be performed to generate insufficient thrust dynamic pressure. A thrust dynamic pressure groove may be further provided in the unit 170.

The stator 300 may include a coil 320, a core 310, and a base member 330.

In other words, the stator 300 may be a fixed structure including a coil 320 generating a predetermined magnitude of electromagnetic force when power is applied and a plurality of cores 310 to which the coil 320 is wound.

The core 310 is fixedly disposed on an upper portion of the base member 330 provided with a printed circuit board (not shown) on which a pattern circuit is printed, and is disposed on an upper surface of the base member 330 corresponding to the winding coil 320. A plurality of coil holes having a predetermined size may be formed to expose the winding coil 320 downward, and the winding coil 320 may be electrically connected to the printed circuit board (not shown) to supply external power. .

The base member 330 may have an outer circumferential surface of the sleeve 120 fixed thereto, and a core 310 in which the coil 320 is wound may be inserted into an inner surface of the base member 330 or the sleeve 120. It can be assembled by applying an adhesive to the outer surface of the.

5 is a schematic cross-sectional view showing a motor including a fluid dynamic bearing assembly according to a second embodiment of the present invention, and FIG. 6 is an enlarged view of a portion A ′ of FIG. 5, and a fluid dynamic pressure according to a second embodiment of the present invention. FIG. 7 is a cross-sectional view showing the structure of a bearing assembly, and FIG. 7 shows a cross-sectional view of a sleeve according to a second embodiment of the present invention.

5 to 7, a motor 400 including a hydrodynamic bearing assembly 100 ′ according to a second embodiment of the present invention includes a fluid dynamic bearing assembly including a shaft 110 and a sleeve 120. 100, the stator 300 including the rotor 200 including the hub 210 and the core 310 to which the coil 320 is wound.

Meanwhile, the fluid dynamic bearing assembly 100 ′ according to the second embodiment of the present invention is a plain journal bearing 122 compared to the fluid dynamic bearing assembly 100 according to the first embodiment of the present invention. Since all are the same except for features that further include, for the clarity of understanding and to avoid confusion, the same configuration may be omitted, and the difference may be mainly described. In addition, the same reference numerals can be used for the same configuration.

In the fluid dynamic bearing assembly 100 ′ according to the second embodiment of the present invention, a plain journal bearing 122 is provided between the first dynamic pressure generating groove 123 and the second dynamic pressure generating groove 124. Can be. The plain journal bearing 122 refers to a plain portion in which only a lubricating fluid is filled in the bearing gap C between the sleeve 120 and the shaft 110 and no groove is formed. Of course, the gap between the sleeve 120 and the shaft 110 is not wide like the reservoir 121 described above, and may be provided to minimize the gap so as to form a labyrinth seal. Of course, the plain journal bearing 122 may correspond to a portion that forms a relatively narrow gap between the sleeve 120 and the shaft 110 even without forming a labyrinth seal.

In the present invention, since the first dynamic pressure generating groove 123 is provided to pump the fluid only downward in the axial direction, the first dynamic pressure generating groove 123 and the second may be generated because excessive fluid pressure may be generated by the axial downward direction. A plain journal bearing 122 may be provided between the dynamic pressure generating grooves 124 to limit excessive pumping of the fluid to prevent an excessive increase in the axially lower fluid pressure.

Through the above embodiments, it may be possible to provide a bearing assembly in which the bearing rigidity of the rotating member is increased in the spindle motor and the pumping direction of the fluid does not change even after long-term use. In addition, since the bearing assembly structure according to the present invention can be easily manufactured by a simple change of the manufacturing method, it can also be provided with the advantage that the conventionally provided manufacturing line can be used as it is.

100: hydrodynamic bearing assembly
110: shaft
120: sleeve
130: Base cover
200: rotor
210: hub
220: magnet
300: stator
310: stator core
320: coil
330: base member

Claims (14)

A sleeve having a shaft hole for rotatably fitting the shaft; And
A first shaft disposed in at least one of an outer diameter of the shaft and an inner diameter of the sleeve and provided upward and downward in an axial direction so as to cause dynamic pressure to a lubricating fluid filled in a bearing gap formed between the shaft and the sleeve when the shaft rotates; And a second dynamic pressure generating groove;
The first dynamic pressure generating groove provided on the upper side in the axial direction is a fluid dynamic bearing assembly provided to pump the lubricating fluid downward in the axial direction.
The method of claim 1,
And the first dynamic pressure generating groove is spiral or threaded.
The method of claim 1,
And the second dynamic pressure generating groove has a herringbone shape.
The method of claim 1,
The shaft has a hydrodynamic bearing assembly having a stopper on the lower end in the axial direction of the sleeve.
5. The method of claim 4,
And at least one of a top surface of the stopper or a bottom surface of the sleeve is provided with a thrust dynamic groove.
The method of claim 1,
And the lubricating fluid is filled in a full-fill shape into a bearing gap formed between the shaft and the sleeve.
The method of claim 1,
And a plain journal bearing is provided between the first dynamic pressure generating groove and the second dynamic pressure generating groove.
The method of claim 1,
A hub fixed to the top of the shaft and extending radially outward;
An oil interface is formed between an upper surface of the sleeve and a lower surface of the hub such that oil is sealed.
9. The method of claim 8,
At least one of an upper surface of the sleeve and a lower surface of the hub is provided with a pumping groove to pump a lubricating fluid in an opposite direction of the oil interface.
9. The method of claim 8,
At least one of an upper surface of the sleeve and a lower surface of the hub has a tapered portion to widen the gap between the sleeve and the hub toward the radially outer side.
The method of claim 10,
And a pumping groove for pumping a lubricating fluid in an opposite direction of the oil interface to a tapered portion provided to at least one of an upper surface of the sleeve and a lower surface of the hub.
The method according to claim 9 or 11,
The pumping groove is a hydrodynamic bearing assembly of the spiral (spiral) or threaded shape.
9. The method of claim 8,
And the hub has a circumferential wall portion extending axially downward to correspond to an upper outer portion of the sleeve.
A base member;
A stator core mounted on the base member, provided to correspond to a magnet provided on the rotating member, and having a coil wound to generate an electromagnetic force; And
Spindle motor comprising a; hydrodynamic bearing assembly of any one of claims 1 to 13 mounted to the base member.

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