KR20130142343A - Hydrodynamic bearing assembly - Google Patents

Hydrodynamic bearing assembly Download PDF

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Publication number
KR20130142343A
KR20130142343A KR1020120065484A KR20120065484A KR20130142343A KR 20130142343 A KR20130142343 A KR 20130142343A KR 1020120065484 A KR1020120065484 A KR 1020120065484A KR 20120065484 A KR20120065484 A KR 20120065484A KR 20130142343 A KR20130142343 A KR 20130142343A
Authority
KR
South Korea
Prior art keywords
shaft
sleeve
bearing assembly
lubricating fluid
cover member
Prior art date
Application number
KR1020120065484A
Other languages
Korean (ko)
Inventor
김한별
Original Assignee
삼성전기주식회사
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 삼성전기주식회사 filed Critical 삼성전기주식회사
Priority to KR1020120065484A priority Critical patent/KR20130142343A/en
Publication of KR20130142343A publication Critical patent/KR20130142343A/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C32/00—Bearings not otherwise provided for
    • F16C32/06—Bearings not otherwise provided for with moving member supported by a fluid cushion formed, at least to a large extent, otherwise than by movement of the shaft, e.g. hydrostatic air-cushion bearings
    • F16C32/0629—Bearings not otherwise provided for with moving member supported by a fluid cushion formed, at least to a large extent, otherwise than by movement of the shaft, e.g. hydrostatic air-cushion bearings supported by a liquid cushion, e.g. oil cushion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/02—Parts of sliding-contact bearings
    • F16C33/04—Brasses; Bushes; Linings
    • F16C33/06—Sliding surface mainly made of metal
    • F16C33/10—Construction relative to lubrication
    • F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B19/00—Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
    • G11B19/20—Driving; Starting; Stopping; Control thereof
    • G11B19/2009—Turntables, hubs and motors for disk drives; Mounting of motors in the drive
    • G11B19/2036—Motors characterized by fluid-dynamic bearings
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
    • H02K7/08—Structural association with bearings

Abstract

A hydrodynamic bearing assembly which includes a shaft with a flange unit extended in a radial direction on the lower part; a sleeve which supports the shaft to be rotated; and a cover unit which is installed on the sleeve to face the bottom surface of the shaft and which includes a flow channel unit for providing a flow passage for lubricating fluid when injecting the lubricating fluid on the top surface of the cover member.

Description

Hydrodynamic bearing assembly

The present invention relates to a fluid dynamic bearing assembly.

In general, a compact spindle motor used in a hard disk drive (HDD) is provided with a hydrodynamic bearing assembly, and a bearing clearance is formed in the fluid dynamic bearing assembly so as to fill a lubricating fluid.

When the shaft is rotated, the lubricating oil filled in the gap between the bearings is pumped to form fluid dynamic pressure to support the shaft rotatably.

Meanwhile, the bearing gap may be formed by the shaft and the sleeve, the shaft and the cover member, the sleeve and the rotor hub, and the bearing gap may be connected.

In addition, the lubricating fluid filled in the bearing gap is generally injected at the assembly stage in which the shaft, the sleeve, the rotor hub, and the cover member are assembled. In addition, the assembly is disposed in an inverted state when the lubricating fluid is injected.

However, when the assembly is disposed in an inverted state, the cover member and the sleeve are moved to the lower side of the shaft by their own weight. Accordingly, as the cover member contacts the shaft, the gap between the bearing gap formed by the cover member and the shaft is narrowed or the bearing gap disappears.

When lubricating fluid is injected in this state, there is a problem that the lubricating fluid is not sufficiently injected into the space between the cover member and the shaft.

In this case, since sufficient lubricating fluid is not injected, there is a problem that the rotational characteristics of the shaft are eventually reduced.

In the following, a spindle motor having a shaft having an inclined portion at its bottom is disclosed.

Japanese Laid-Open Patent Publication 2005-331033

The filling of the lubricating fluid can be made smoothly, and provides a fluid dynamic bearing assembly that can reduce the generation of negative pressure.

A hydrodynamic bearing assembly according to an embodiment of the present invention includes a shaft having a flange portion extending in a radial direction at a lower end thereof, a sleeve rotatably supporting the shaft, and a sleeve disposed to face the bottom of the shaft. It includes a cover member is installed, the upper surface of the cover member may be formed with a flow channel portion for providing a flow path of the lubricating fluid when the lubricating fluid is injected.

The bottom surface of the shaft may be formed with an indentation groove to be indented so that the lubricating fluid can be stored.

One side of the flow channel portion may be disposed radially outward of the flange portion, and the other side may be disposed below the edge of the indentation groove.

The flow channel portion may be composed of a plurality of grooves spaced apart along the circumferential direction.

Thrust dynamic pressure grooves for generating thrust dynamic pressure may be formed on an upper surface of the flange portion and an opposite surface of the sleeve disposed to face the upper surface of the flange portion.

Filling of the lubricating fluid through the flow channel portion has an effect that can be performed more smoothly.

In addition, since the flow channel portion connects the space formed by the indentation groove of the shaft and the bearing gap formed by the flange portion and the sleeve of the shaft, there is an effect of reducing sound pressure generation and / or bubble generation during rotational start of the shaft. .

1 is a schematic cross-sectional view showing a spindle motor including a hydrodynamic bearing assembly according to an embodiment of the present invention.
2 is an enlarged view showing part A of Fig.
3 is a perspective view showing a cover member provided in the fluid dynamic bearing assembly according to an embodiment of the present invention.
4 is an explanatory view for explaining the operation of the hydrodynamic bearing assembly according to an embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. 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 which fall within the scope of the inventive concept may be easily suggested, but are also included within the scope of the present invention.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

1 is a schematic cross-sectional view showing a spindle motor including a hydrodynamic bearing assembly according to an embodiment of the present invention, Figure 2 is an enlarged view showing a part A of Figure 1, Figure 3 is an embodiment of the present invention 4 is a perspective view illustrating a cover member provided in the fluid dynamic bearing assembly according to an embodiment of the present invention, and FIG. 4 is an explanatory diagram for describing an operation of the fluid dynamic bearing assembly according to an embodiment of the present invention.

1 to 4, the fluid dynamic bearing assembly 100 according to an embodiment of the present invention may include a shaft 110, a sleeve 120, and a cover member 130.

On the other hand, the hydrodynamic bearing assembly 100 is a configuration included in the spindle motor 10, the spindle motor 10 may be a motor applied to the recording disk drive for rotating the recording disk.

First, the spindle motor 10 will be described briefly, and then the fluid dynamic bearing assembly 100 according to an embodiment of the present invention will be described.

The spindle motor 10 may include a base member 20, a hydrodynamic bearing assembly 100, a rotor hub 40, and a stator core 60.

Here, when defining the term for the direction, the axial direction refers to the up, down direction, that is, the direction from the bottom of the shaft 110 to the top or the direction from the top of the shaft 110 to the bottom as shown in FIG. 1, the radial direction refers to the left and right directions, that is, the direction toward the shaft 110 from the outer circumferential surface of the rotor hub 40 or the direction toward the outer circumferential surface of the rotor hub 40 from the shaft 110.

In addition, the circumferential direction means a direction that is rotated along the outer circumferential surfaces of the rotor hub 40 and the shaft 110.

The base member 20 may include a protrusion 22 in which the sleeve 120 provided in the hydrodynamic bearing assembly 100 is installed. The protrusion 22 is formed to protrude upward in the axial direction, and the sleeve 120 is inserted into the protrusion 22 and installed.

In addition, a stator core 60 around which the coil 62 is wound may be installed on the outer circumferential surface of the protrusion 22. That is, the stator core 60 may be fixedly installed by adhesive or / and welding in a state of being seated on the seating surface 22a formed on the outer circumferential surface of the protrusion 22.

In addition, the base member 20 may be formed with a drawing hole 24 disposed around the protrusion 22. Then, the lead portion 62a of the coil 62 wound on the stator core 60 may be drawn out from the upper side to the lower side of the base member 20 through the drawing hole 24.

In addition, a circuit board 70 to which the lead portion 62a of the coil 62 is joined may be installed on the bottom surface of the base member 20. The circuit board 70 may be a flexible circuit board.

The rotor hub 40 is fixedly installed at the upper end of the shaft 110 and rotates in conjunction with the shaft 110.

Meanwhile, the rotor hub 40 includes a body 42 having a mounting hole 42a into which an upper end of the shaft 110 is inserted, a magnet mounting portion 44 extending downward from an edge of the body 42 in an axial direction, and The disk mounting portion 46 may extend from the end of the magnet mounting portion 44 to extend radially outward.

In addition, a driving magnet 44a is provided on an inner surface of the magnet mounting unit 44, and the driving magnet 44a is disposed opposite to the tip of the stator core 60 on which the coil 62 is wound.

On the other hand, the driving magnet 44a may have a ring shape, and may be a permanent magnet in which N poles and S poles are alternately magnetized along the circumferential direction to generate a magnetic force of a predetermined intensity.

Here, when the rotation drive of the rotor hub 40 is briefly described, when the power is supplied to the coil 62 wound on the stator core 60, the stator core (a) in which the driving magnet 44a and the coil 62 are wound Electromagnetic interaction with 60 generates a driving force by which the rotor hub 40 can be rotated.

Accordingly, the rotor hub 40 is rotated. In addition, the shaft 110 to which the rotor hub 40 is fixed by the rotation of the rotor hub 40 may rotate in conjunction with the rotor hub 40.

On the other hand, the body 42 may be provided with an extension wall portion 42b extending downward in the axial direction so that the interface between the lubricating fluid and the air, that is, the gas-liquid interface, together with the outer circumferential surface of the sleeve 120 may be formed.

The inner surface of the extension wall portion 42b is disposed to face the outer circumferential surface of the sleeve 120, and at least one of the outer circumferential surface of the sleeve 120 and the inner surface of the extension wall portion 42b may be inclined to form a gas-liquid interface.

That is, at least one of the outer circumferential surface of the sleeve 120 and the inner surface of the extension wall portion 42b may be inclined to form a gas-liquid interface through a capillary phenomenon.

On the other hand, when both the inner surface of the extension wall portion 42b and the outer peripheral surface of the sleeve 120 are formed to be inclined, the two inclination angles may be formed differently.

Hereinafter will be described with respect to the hydrodynamic bearing assembly 100 according to an embodiment of the present invention.

The shaft 110 may be rotatably supported by the sleeve 120. In addition, the lower end of the shaft 110 may be provided with a flange portion 112 extending in the radial direction.

The flange portion 112 prevents the shaft 110 from being separated from the sleeve 120 during an external impact and at the same time prevents the shaft 110 from being injured. That is, the shaft 110 is floated to a predetermined height during the rotational drive of the shaft 110. However, when excessive floating force is provided to the shaft 110 or an external impact is applied during the rotational drive, the flange part 112 contacts the sleeve 120 to prevent the shaft 110 from being excessively injured.

In addition, the flange portion 112 serves as an assistant for the formation of the thrust fluid dynamic pressure. A detailed description thereof will be described later.

On the other hand, when the shaft 110 is installed in the sleeve 120, the upper end of the shaft 110 may be disposed to protrude to the upper portion of the sleeve 120. Then, the rotor hub 40 is coupled to the upper end of the shaft 110 disposed to protrude upward of the sleeve 120.

In addition, an indentation groove 114 may be formed in the bottom surface of the shaft 110 to store the lubricating fluid. That is, when the shaft 110 is stopped, the bottom of the shaft 110 is seated on the top surface of the cover member 130. At this time, the lubricating fluid is stored in the indentation groove 114.

Accordingly, by reducing the friction between the bottom surface of the shaft 110 and the top surface of the cover member 130 when the shaft 110 starts to rotate, the shaft 110 can be driven to rotate more easily.

The sleeve 120 rotatably supports the shaft 110. Meanwhile, the sleeve 120 may be inserted into and fixed to the protrusion 22 of the base member 20 as described above. That is, the outer circumferential surface of the sleeve 120 may be joined to the inner circumferential surface of the protrusion 22 by at least one method of adhesion, welding, and press fitting.

In addition, a shaft hole 121 into which the shaft 110 is inserted may be formed in the sleeve 120. When the shaft 110 is inserted into the shaft hole 121 of the sleeve 120, the inner circumferential surface of the sleeve 120 and the outer circumferential surface of the shaft 110 are spaced apart by a predetermined gap to form a bearing gap.

Here, the bearing gap will be described.

Lubricating fluid is filled in the bearing gap, and the lubricating fluid may be pumped when the shaft 110 is rotated to generate fluid dynamic pressure.

On the other hand, the bearing gap is formed by the gap formed by the shaft 110 and the sleeve 120, the gap formed by the shaft 110 and the cover member 130 and formed by the sleeve 120 and the rotor hub 40. Say the gap.

In addition, the fluid dynamic bearing assembly 100 according to the present embodiment employs a structure in which a lubricating fluid is filled in the entire bearing gap, and such a structure is also referred to as a full-fill structure.

In addition, the interface between the lubricating fluid and air filled in the bearing gap (ie, the gas-liquid interface) may be disposed in a space formed by the upper end of the outer circumferential surface of the sleeve 120 and the inner circumferential surface of the extension wall portion 42b.

In addition, an insertion groove 122 into which the flange portion 112 of the shaft 110 is inserted is formed at the lower end of the sleeve 120, and is formed to be stepped with the insertion groove 122 at the lower side of the insertion groove 122. A mounting groove 123 in which the member 130 is installed may be formed.

Meanwhile, upper and lower radial dynamic grooves 124 and 125 may be formed on the inner circumferential surface of the sleeve 120 to form a fluid dynamic pressure in a radial direction when the shaft 110 rotates. The upper and lower radial dynamic grooves 124 and 125 may be spaced apart from each other by a predetermined interval and may have a herringbone or spiral shape.

However, the upper and lower radial dynamic grooves 124 and 125 are not limited to the case formed on the inner circumferential surface of the sleeve 120, but may be formed on the outer circumferential surface of the shaft 110.

In addition, a thrust dynamic pressure groove 126 for forming a thrust fluid dynamic pressure may be formed on an opposite surface of the sleeve 120 that is disposed opposite the upper surface of the flange portion 112, that is, the ceiling surface forming the insertion groove 122. have.

That is, the flange portion 112 is disposed to face the thrust dynamic pressure groove 126 to serve as an assistant for generating thrust dynamic pressure by the thrust dynamic pressure groove 126.

Meanwhile, the upper and lower radial dynamic grooves 124 and 125 and the thrust dynamic grooves 126 are lubricated and flow into the space formed by the bottom surface of the shaft 110 and the upper surface of the cover member 130. That is, the lubricating fluid may be finally pumped down by the upper and lower radial dynamic grooves 124 and 125 and the thrust dynamic pressure groove 126 described above.

As such, the lubricating fluid flows into the space formed by the bottom surface of the shaft 110 and the top surface of the cover member 130 to generate the floating force to float the shaft 110.

The cover member 130 may be installed on the sleeve 120 so as to face the bottom surface of the shaft 110. That is, the cover member 130 may be installed in the mounting groove 123 of the sleeve 120. In addition, the cover member 130 may be installed in the mounting groove 123 of the sleeve 120 by adhesive or / and welding.

In addition, the cover member 130 serves to prevent the lubricating fluid filled in the bearing gap from leaking to the lower end side of the sleeve 120.

On the other hand, the upper surface of the cover member 130 may be formed with a flow channel portion 132 that provides a flow path of the lubricating fluid when the lubricating fluid is injected into the bearing gap. In addition, the flow channel part 132 may be formed such that one side thereof is disposed at the radially outer side of the flange portion 112 and the other side thereof is disposed below the edge of the indentation groove 114.

That is, the flow channel part 132 serves to communicate the gap formed by the side wall forming the insertion groove 122 of the sleeve 120 with the outer peripheral surface of the flange portion 1120 and the indentation groove 114.

Here, the operation of the flow channel part 132 providing a flow path of the lubricating fluid when the lubricating fluid is injected into the bearing gap will be described in more detail.

As shown in FIG. 4, when the lubricating fluid is injected, the coupling parts (hereinafter referred to as 'assemblies') of the shaft 110, the sleeve 120, the rotor hub 40, and the cover member 130 are kept in an inverted state. do.

That is, the assembly is positioned so that the cover member 130 is disposed above, and then lubricating fluid is injected.

However, when the assembly is reversed, the cover member 130 and the shaft 110 are contacted by their own weight. However, since the flow channel part 132 is formed in the cover member 130, the cover member 130 and the shaft 110 may not contact each other at the portion where the flow channel part 132 is formed.

Accordingly, when the lubricating fluid is injected, the lubricating fluid can be smoothly introduced into the indentation groove 114 of the shaft 110 through the flow channel part 132.

That is, when the flow channel part 132 is not provided in the cover member 130, the problem that the lubricating fluid is not smoothly injected by the contact between the shaft 110 and the cover member 150 can be solved.

In addition, the flow channel portion 132 serves to reduce the generation of negative pressure (ie, pressure lower than atmospheric pressure) in the space formed by the indentation groove 114 of the shaft 110 and the upper surface of the cover member 130. Can be done.

That is, the flow channel portion 132 communicates the gap formed by the indentation groove 114, the outer circumferential surface of the flange portion 112, and the sidewall forming the insertion groove 122 of the sleeve 120. Accordingly, the lubricant fluid smoothly into the indentation groove 114 from the gap formed by the outer peripheral surface of the flange portion 112 and the side wall forming the insertion groove 122 of the sleeve 120 when the shaft 110 is rotated. It is possible to reduce the sound pressure generation by allowing the flow.

In other words, when the flow channel portion 132 is not formed, it is formed by the pressure in the indentation groove 114, the outer circumferential surface of the flange portion 112, and the sidewalls forming the insertion groove 122 of the sleeve 120. There is a difference in the pressure of the gap.

Then, the above-mentioned pressure difference is maintained until the shaft 110 rises a predetermined height so that the lubricating fluid flows into the indentation groove 114.

Due to this pressure difference, the negative pressure in the indentation groove 114 may be generated. In addition, even if no negative pressure is generated in the indentation groove 114, bubbles may be generated by the above-described pressure difference when the lubricating fluid enters the indentation groove 114, and such bubbles reduce the rotational characteristics of the shaft 110. Let's do it.

However, since the flow channel part 132 is formed in the cover member 130, the pressure difference can be quickly reduced, and thus, the occurrence of negative pressure can be reduced and the bubble can be suppressed at the same time.

On the other hand, the flow channel portion 132 may be composed of a plurality of grooves spaced apart in the circumferential direction. In this embodiment, the flow channel unit 132 is described as an example of four grooves, but is not limited thereto. The flow channel unit 132 may include four or less grooves or four or more grooves. .

On the other hand, the shape of the flow channel portion 132 is not limited to the shape shown in the figure, one side of the flow channel portion 132 is disposed on the radially outer side of the flange portion 112, the other side is the indentation groove 114 If placed below the edge of the, it may be changed to any shape.

As described above, the filling of the lubricating fluid when the lubricating fluid is injected through the flow channel part 132 may be performed more smoothly.

In addition, since the flow channel portion 132 connects the space formed by the indentation groove 114 of the shaft 110 and the bearing gap formed by the flange portion 112 and the sleeve 120 of the shaft 110, the shaft Sound pressure generation at the time of rotation start of 110 can be reduced, and bubble generation can be suppressed.

10: spindle motor
20: base member
40: rotor hub
60: Stator Core
100: hydrodynamic bearing assembly
110: the shaft
120: Sleeve
130: cover member
132: flow channel portion

Claims (5)

A shaft having a flange portion extending in a radial direction at a lower end thereof;
A sleeve rotatably supporting the shaft; And
A cover member installed on the sleeve so as to face the bottom surface of the shaft;
Including;
A fluid dynamic bearing assembly having an upper surface of the cover member to form a flow channel portion for providing a flow path of the lubricating fluid when the lubricating fluid is injected. The method of claim 1,
A fluid dynamic bearing assembly having a recessed groove formed in the bottom of the shaft so that the lubricating fluid can be stored. 3. The method of claim 2,
One side of the flow channel portion is disposed in the radially outer side of the flange portion, the other side is a hydrodynamic bearing assembly disposed below the edge of the indentation groove. The method of claim 3,
The fluid channel bearing assembly is composed of a plurality of grooves spaced apart along the circumferential direction. The method of claim 1,
And a thrust dynamic pressure groove for generating thrust dynamic pressure on an upper surface of the flange portion and an opposite surface of the sleeve disposed to face the upper surface of the flange portion.
KR1020120065484A 2012-06-19 2012-06-19 Hydrodynamic bearing assembly KR20130142343A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
KR1020120065484A KR20130142343A (en) 2012-06-19 2012-06-19 Hydrodynamic bearing assembly

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR1020120065484A KR20130142343A (en) 2012-06-19 2012-06-19 Hydrodynamic bearing assembly

Publications (1)

Publication Number Publication Date
KR20130142343A true KR20130142343A (en) 2013-12-30

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
KR1020120065484A KR20130142343A (en) 2012-06-19 2012-06-19 Hydrodynamic bearing assembly

Country Status (1)

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