DE102013019911A1 - Fluid-dynamic bearing system for spindle motor to drive hard disk drive, has fixed and rotatable bearing components separated from each other, and sealants formed with air gap measured with flow constant for which preset value is applied - Google Patents

Abstract

The system has a fixed bearing component (12), and a rotatable bearing component (14) separated from each other by a bearing gap (20). The bearing gap is filled with bearing fluid and provided with two open ends, which are sealed by two sealants (32, 34). Fluid-dynamic radial bearings (22a, 22b) and a fluid-dynamic thrust bearing (26) or a conical fluid-dynamic bearing are arranged along the bearing gap. An air gap (48) is on each side of one of the sealants and measured with a flow constant for which a preset value is applied. Independent claims are also included for the following: (1) a spindle motor comprising a fixed motor component and a fluid-dynamic bearing system (2) a hard disk drive comprising a storage disk.

Description

Field of the invention

The invention relates to a fluid dynamic bearing system, as used for example for the rotary mounting of spindle motors. Such spindle motors with a fluid-dynamic bearing system are used inter alia for driving disk drives.

State of the art

Fluid dynamic bearing systems generally comprise at least two relatively rotatable bearing components, the bearing surfaces between one another with a bearing fluid, for. B. bearing oil, filled bearing gap form. In a known manner, bearing surfaces assigned to and acting on the bearing fluid bearing structures are provided. In fluid dynamic bearings, the bearing structures in the form of groove patterns as depressions or elevations are usually applied to individual or both opposing bearing surfaces. These bearing structures arranged on corresponding bearing surfaces of the bearing partners serve as bearing and / or pump structures which generate a hydrodynamic pressure with relative rotation of the bearing components within the bearing gap. For radial bearings, for example, sinusoidal, parabolic or herringbone bearing structures are used, which are arranged on a surface parallel to the axis of rotation of the bearing components distributed over the circumference of at least one bearing component. In axial bearings, for example, helical or herringbone bearing structures are used, which are arranged in a plane transverse to the axis of rotation.

Spindle motors with fluid-dynamic bearing system, as used for example for driving hard disk drives, can generally be divided into two different groups, ie types: motors with rotating shaft and usually only one-sided opened storage system (eg a so-called "single-plate bearing" or "single top thrust bearing") and motors with a stationary shaft and a bearing gap open on both sides. The open ends of the bearing gap must be sealed so that no bearing fluid escapes from the bearing gap and contaminates other components of the spindle motor. The sealing of the bearing gap is carried out by suitable sealing means, for example by static Kapillardichtungen or dynamic pump seals or a combination of these two types of seals.

The US 2010/0296190 A1 discloses a fluid dynamic bearing system with a standing shaft and sealing gaps for sealing the bearing gap. In order to reduce the escape of vaporized bearing fluid from the sealing gap, it is proposed to reduce the width of the sealing gap at its open end. As a result, the bearing fluid vapor is largely retained in the sealing gap.

For the filling of a fluid dynamic bearing with bearing fluid various methods are used, in particular depending on whether the bearing gap is open only at one end or at both ends to the environment.

The DE 10 2009 020 474 A1 discloses a method for filling a fluid bearing with a bearing gap open on both sides. Here, the bearing to be filled is introduced into a closed and evakuierbare working chamber and positioned within the working chamber on a holding device such that the first open end of the bearing gap opens into the working chamber and the second open end opens into a separate chamber from the working chamber cavity of the holding device. The pressure in the working chamber is set to a value P1, whereby a pressure P2 = P1 adjusts itself over the bearing gap of the bearing in the separate cavity. Now, a predetermined amount of the lubricant is introduced into the region of the first open end of the bearing gap by a filling device. Then, at least temporarily, a pressure difference between the working chamber and the separate cavity with P2 <P1 is generated, whereby the lubricant is distributed from the first open end in the entire bearing gap.

The pressure difference between the working chamber and the separate cavity can be generated via a ventilation opening which connects the separate cavity to the working chamber. When venting the working chamber results due to the ventilation opening between the working chamber and the cavity, a temporary pressure difference with P2 <P1, whereby the lubricant distributed starting from the first open end in the bearing gap, until a pressure equalization P1 = P2 is carried out via the ventilation opening. The ventilation opening can be formed for example by a narrow gap between parts of the bearing and parts of the holding device. But it can also be formed by a hole in parts of the holding device.

The disadvantage with this filling method is that a special device is necessary for each type of bearing and motor type. Whenever the bearing design changes, a change to the filling device is usually necessary.

Disclosure of the invention

It is the object of the invention to provide a fluid dynamic bearing system that facilitates and improves the filling process for filling the bearing fluid into the bearing, regardless of the filling device used.

This object is achieved by a fluid dynamic bearing system having the features of claim 1.

Preferred embodiments of the invention and further advantageous features emerge from the subclaims.

The fluid dynamic bearing comprises a first fixed bearing component and a second bearing component rotatably arranged about an axis of rotation, the first and the second bearing component being separated from one another during operation of the bearing by a bearing gap filled with a bearing fluid. The bearing gap has first and second open ends sealed by first and second sealing means. Along the bearing gap at least one fluid dynamic radial bearing and at least one fluid dynamic thrust bearing or alternatively at least one conical fluid dynamic bearing is arranged.

The invention is characterized in that, beyond the first sealing means, an air gap is arranged which is dimensioned such that it has a flow constant k which is between 0.06 × 10 ^-12 m ³ <= k <= 1.62 × 10 ^-12 m ³ or even between 0.06 × 10 ^-12 m ³ <= k <= 8 × 10 ^-12 m ³ .

In previous methods for filling the bearing gap of these fluid dynamic bearings has been shown that by uncontrolled ventilation of the bearing during the filling process, a relatively large amount of air can get into the camp, which then makes the camp unusable and requires a new filling process.

According to the invention, a controlled ventilation opening in the form of a precisely defined air gap is arranged at the end of the bearing gap at which the bearing fluid is not introduced.

This air gap is part of the bearing and is formed and limited directly by the bearing components.

The width and length of the air gap is dimensioned so that the optimum amount of air in the region of the bearing, ie in the region of the first sealant, flow, while the bearing is vented in the filling process and thereby the bearing fluid is introduced into the camp.

The precisely defined dimensions of this air gap prevent inadmissibly large amounts of air from entering the bearing gap.

If this air gap is too large, too much air gets into the bearing gap, which makes the bearing unusable or reduces its service life. If the air gap is too small, too little air enters the sealing area during the filling process, so that too much bearing fluid is forced into the sealing area. The lack thereof in the bearing gap bearing fluid can be replaced by air, which can limit the operating characteristics of the camp.

According to the invention, during the filling process and during the ventilation of the bearing for introducing the bearing fluid, the amount of air flowing through the bottleneck of the air gap, that is to say the volume flow Q, is of importance. The volume flow Q through a gap depends on a flow constant k determined by the geometry of the gap, the viscosity η (of air) and the driving pressure difference Δp: Q = k · 1 / η · Δp

The constant k multiplied by the reciprocal of the viscosity η is also referred to as so-called flow conductivity σ = k · 1 / η, so that applies Q = σ · Δp

In a fluid dynamic bearing according to the invention, this air gap is arranged annularly and concentrically to the axis of rotation of the bearing. This annular shape of the air gap must be taken into account in the calculation of the flow conductivity σ of the air gap.

In particular, it is provided that the air gap is arranged parallel to the axis of rotation of the rotatable bearing component, wherein the air gap is defined by a gap width d and a length L. This axially extending shape of the air gap can be used in particular in fluid dynamic bearings with sufficiently large height.

In another embodiment of the invention, the air gap is arranged perpendicular or oblique to the axis of rotation of the rotatable bearing component and also has a gap width d and length L. This arrangement or orientation of the air gap is particularly suitable for very flat fluid dynamic bearings in which an axial arrangement of the air gap due to lack of height is out of the question.

Of course, according to the invention, both embodiments of the invention can also be combined and create an air gap which has both an axially extending section and a radially extending section. Such mixed forms of the air gap are also conceivable.

R_i

= Innerer Radius des Luftspalts

R_o

= Äußerer Radius des Luftspalts

Equation 1 shows the calculation of the volume flow Q for an axial air gap with the width d = R _o - R _i and a length L.

R _i

= Inner radius of the air gap

R _o

= Outer radius of the air gap

For the value of Q defined according to the invention, the required gap width d can be determined for a given length L or, for a given gap width d, the length L of the air gap can be determined.

R_i

= Innerer Radius des Luftspalts (Länge L)

R_o

= Äußerer Radius des Luftspalts (Länge L)

Equation 2 shows calculation of the volume flow Q for an air gap extending radially, ie perpendicular to the axis of rotation.

R _i

= Inner radius of the air gap (length L)

R _o

= Outer radius of the air gap (length L)

The length of the air gap L results from the value R _o - R _i and the gap width d of the air gap is determined by the distance between the fixed bearing component or its upper edge and a lower edge of the rotor component.

Preferred embodiments of the invention and further advantageous features are described in the following drawings.

Brief description of the drawings

1 shows a section through a spindle motor with a first preferred embodiment of a bearing according to the invention.

1A shows an enlarged section of the bearing of 1 in the area of the air gap.

2 shows a section through a spindle motor with a second preferred embodiment of a bearing according to the invention.

2A shows an enlarged section of the bearing of 2 in the area of the air gap.

3 shows a section through a spindle motor with a third preferred embodiment of a bearing according to the invention.

3A shows an enlarged section of the bearing of 3 in the area of the air gap.

3B shows an enlarged section of the bearing of 3 with a modified arrangement and shape of the air gap.

4 shows a device for filling a bearing according to the invention with bearing fluid.

Description of preferred embodiments of the invention

The 1 shows a spindle motor with a fluid dynamic bearing according to the invention. Such a spindle motor can be used to drive disks of a hard disk drive.

The spindle motor comprises a base plate 10 having a substantially central cylindrical opening in which a first bearing member 16 is included. The first bearing component 16 is about cup-shaped with a border 16a formed and includes a central opening, in which the shaft 12 is attached. At the free end of the fixed shaft 12 is a stopper component 18 arranged, preferably annular and integral with the shaft 12 is trained. The named components 10 . 12 . 16 and 18 form the fixed component of the spindle motor. The fluid dynamic bearing comprises a rotatable rotor component 14 , which has a bearing bore for receiving the shaft 12 and in one through the shaft 12 and the two components 16 . 18 formed intermediate space is rotatably arranged relative to these components. The stopper component 18 is in an annular recess of the rotor component 14 arranged. Adjacent surfaces of the shaft 12 , the rotor component 14 and the components 16 . 18 are by a bearing gap open on both sides 20 separated from each other, which is filled with a bearing fluid, such as a bearing oil.

The rotor component 14 has a cylindrical bearing bore, on whose inner circumference two cylindrical bearing surfaces are formed, which by a circulating separator gap between them 24 with opposite the bearing gap 20 enlarged gap width are separated. These storage areas enclose the standing wave 12 at a distance of a few microns to form an axially extending portion of the bearing gap 20 and are provided with suitable Lagerrillenstrukturen so that they with the respective opposite bearing surfaces of the shaft 12 two fluid dynamic radial bearings 22a and 22b form.

To the lower radial bearing 22b closes a radially extending portion of the bearing gap 20 on, by radially extending bearing surfaces of the rotor component 14 and corresponding opposite bearing surfaces of the fixed bearing component 16 is formed. These bearing surfaces form a fluid dynamic thrust bearing 26 with bearing surfaces in the form of to the axis of rotation 46 vertical circle rings. The fluid dynamic thrust bearing 26 is characterized in a known manner by spiral bearing groove structures, either on the front side of the rotor component 14 , the first bearing component 16 or both parts can be attached. The groove structures of the thrust bearing 26 preferably extend over the entire lower end face of the rotor component 14 that is, from the inner edge to the outer edge. This results in operation in a defined pressure distribution in the entire thrust bearing gap and vacuum zones are avoided because the fluid pressure increases continuously from a radially outer to a radially inner position of the thrust bearing. Advantageously, all are for the radial bearings 22a . 22b and the thrust bearing 26 necessary bearing groove structures on the rotor component 14 arranged what the production of the bearing, in particular the shaft 12 and the bearing component 16 simplified.

At the radial portion of the bearing gap 20 in the area of the thrust bearing 26 closes a proportionately filled with bearing fluid first sealing gap 34 on, by opposing surfaces of the rotor component 14 and the edge 16a of the fixed bearing component 16 is limited and this side of the storage gap 20 seals. The first sealing gap 34 includes one opposite the bearing gap 20 widened radially extending portion that merges into a conically opening nearly axially extending portion of an inner peripheral surface of the rotor member 14 and an outer peripheral surface of the fixed bearing member 16 is limited. In addition to the function as a capillary seal, the sealing gap is used 34 as a fluid reservoir and provides the required for the life of the storage system fluid amount. Furthermore, filling tolerances and a possible thermal expansion of the bearing fluid can be compensated. The two of the conical section of the sealing gap 34 forming surfaces on the rotor component 14 and the fixed bearing component 16 can each relative to the axis of rotation 46 to be inclined inwards. As a result, the bearing fluid in a rotation of the bearing due to the centrifugal force inward in the direction of the bearing gap 20 pressed.

On the other side of the fluid bearing system is the rotor component 14 following the upper radial bearing 22a designed so that it forms a radial extending surface, which with a corresponding opposite surface of the stopper member 18 forms a radial gap. At the radial gap, an axially extending second sealing gap closes 32 on, by opposing surfaces of the rotor component 14 and the stopper member 18 is limited and the fluid bearing system terminates at this end. Along the second sealing gap 32 is preferably a pump seal characterized by corresponding groove structures 36 arranged, wherein the second sealing gap 32 widens at the outer end with preferably conical cross-section. The second sealing gap 32 is preferably of an annular cap 30 covered on the rotor component 14 is attached. The inner edge of the cap 30 forms together with the outer circumference of the shaft 12 a gap seal. This increases the safety against leakage of bearing fluid from the seal gap 32 ,

The electromagnetic drive system of the spindle motor is formed in a known manner by a on the base plate 10 arranged stator arrangement 42 and a ring-shaped permanent magnet surrounding the stator assembly at a distance 44 at an inner circumferential surface of an outer edge of the rotor component 14 is arranged.

Since the spindle motor only a fluid dynamic thrust bearing 26 having a force in the direction of the stopper member 18 generated, a corresponding counterforce or biasing force must be provided on the movable bearing part, which holds the bearing system axially in balance. For this, the base plate 10 a ferromagnetic ring 40 have, the rotor magnet 44 axially opposite and is magnetically attracted by this. This magnetic attraction acts against the force of the thrust bearing 26 and keeps the bearing axially stable. Alternatively or in addition to this solution, the stator assembly 42 and the rotor magnet 44 axially offset from each other, in such a way that the rotor magnet 44 axially further away from the base plate 10 is arranged as the stator assembly 42 , As a result, an axial force is built up by the magnet system of the motor, which also opposite to the thrust bearing 26 acts. Alternatively or additionally, between the stopper member 18 and the rotor component 14 along a radially extending portion of the bearing gap 20 a second thrust bearing 38 be provided with spiral bearing grooves, the thrust bearing 26 counteracts.

In order to ensure a continuous flushing of the storage system with bearing fluid, in a known manner, a recirculation channel 28 intended. The recirculation channel 28 is also filled with bearing fluid and connects remote section of the bearing gap 20 directly with each other.

According to the invention closes at the first sealing gap 34 immediately an air gap 48 on, by radially opposed surfaces 14a of the rotor component 14 and the edge 16a of the fixed bearing component 16 is formed. The rotor component 14 owns in the area of the air gap 48 at its outer diameter above the first sealing gap 34 an area 14a with increased outside diameter, which causes the width of the air gap 48 is significantly smaller than the width of the first sealing gap 34 , For example, the width of the first sealing gap 34 typically 0.08 to 0.15 mm at its narrowest point, expanding to about 0.18 to 0.25 mm over an axial length of about 2.5 to 3 mm. The width of the air gap 48 is significantly smaller than the smallest width of the sealing gap 34 ,

The optimal width d and length L of the air gap 48 can from the flow conductivity defined according to the invention σ and the applied pressure difference Ap between the two open ends of the bearing gap 20 be determined. This optimum value of the flow conductivity σ was determined by simulations and / or practical experiments.

Out 1A can be the required sizes of the air gap 48 and remove the bearing components more clearly.

The width d of the air gap is defined by an inner radius R _i passing through an outer peripheral surface of the rotor component 14 is determined, and an outer radius R _o , by an inner peripheral surface of the fixed bearing member 16 is determined. The length L of the air gap 48 is specified depending on space in the warehouse.

In the in the 1 and 1A Spindle motor shown is a spindle motor with fluid dynamic storage system for driving a 2.5 '' hard disk drive with a height of more than 10 mm. Since a relatively large overall height is present here, the length L of the gap can be chosen to be relatively large, for example L = 1.77 mm.

Using equation 1 and a flow constant k according to the invention, the viscosity η of air and a pressure difference Δp between the ends of the bearing gap which is typical during filling, the gap width d of the air gap is calculated 48 to 70 microns.

Is the diameter R _{i of} the rotor component 14 For example, 3.055 mm, so the diameter R _{o of} the bearing component 16 to R _o = 3.125 mm.

In the area of the air gap 48 for example, on the surface 14a of the rotor component 14 a circumferential groove or recess may be present, which serves, possibly from the sealing gap 34 in the air gap 48 Pick up leaking bearing fluid and hold in the camp. This groove or recess serves as an additional safeguard against leakage of bearing fluid from the camp.

The 2 and 2A show a spindle motor with fluid dynamic bearing in a similar design as 1 , wherein the same components or components with the same functions are provided with the same reference numerals.

Again, it is a spindle motor for driving a 2.5 '' hard disk drive with a height of 7 mm. The spindle motor includes, among other things, a base plate 110 , a wave 112 , a rotor component 114 , a bearing component 116 , a stopper component 118 , a thrust bearing 126 and a recirculation channel 128 ,

In contrast to 1 is the fluid dynamic bearing of 2 built much flatter and has only about half the height, but the length of the sealing gap 34 is maintained substantially, but the length L of the air gap 148 across from 1 is shortened.

Another difference is a T-shaped shaft 112 , which has at the lower end a vertical and flat flange, which in a sleeve-shaped fixed bearing component 116 is fixed, preferably by means of a welded connection. This connection of the wave 112 with the bearing component 116 increases the strength of the connection and the rigidity of the storage system. Furthermore, this design allows easier machining of the bearing surfaces on the shaft 112 or the thrust bearing surfaces passing through the T-shaped extension of the shaft 112 are formed, possible.

The length L of the axially extending air gap 148 is determined by the space available in the warehouse. So that a sufficiently large sealing gap 34 and sealing volume can be provided, for example, is selected as the length L = 1.14 mm.

Using equation 1 and a flow constant k according to the invention, the viscosity η of air and a pressure difference Δp between the ends of the bearing gap which is typical during filling, the gap width d of the air gap is calculated 48 to 60 microns.

For a given radius of the rotor component 114 of R _i = 3,225 mm must be for the radius R _{o of} the bearing component 116 a value of R _o = 3.285 mm can be selected.

The 3 and 3A show a further embodiment of the invention. This bearing system or the spindle motor corresponds in its construction to the spindle motor of 2 , but is reduced in height by another 2 mm to 5 mm. The spindle motor includes, among other things, a base plate 210 , a wave 212 , a rotor component 214 , a bearing component 216 , a stopper component 218 , a thrust bearing 226 and a recirculation channel 228 ,

Due to the small height of the spindle motor in particular, the axial length of the sealing gap 34 as well as to a large extent the axial length L of the air gap 248 reduced, which in this embodiment has a length of only 0.56 mm.

The inner radius R _{i of} this bearing is R _i = 3.235 mm and the outer radius R _o is R _o = 3.282 mm.

This results in a gap width of the air gap 248 of d = 47 microns. With these dimensions, using equation 1, the flow conductivity of this air gap required according to the invention is obtained 248 reached.

3B shows an alternative embodiment of the bearing of 3 , at the air gap 348 is not arranged in the axial direction, but in the radial direction.

By this construction, the length of the sealing gap 34 be enlarged, since the air gap 348 now not in extension of the sealing gap 34 but is arranged perpendicular thereto.

In this case, the equation 2 applies to the calculation of the volume flow Q.

The radii R _i and R _o no longer determine the width d but the length L of the air gap 248 , while the distance d by the distance of the fixed bearing component 216 to the rotor component 214 is determined.

The inner radius R _i is R _i = 3.395 mm and the outer radius R _o = 3.690 mm.

For a given flow constant of k = 0.323 · 10 ^-12 m ³ , equation 2 yields the length L of the air gap 348 a value of L = 0.295 mm and an optimum gap width d of the air gap 348 of 37 microns.

In this case, it must be noted that the distance d when filling the bearing assumes the specified value. The bearing has an axial play, so that the distance d applies only to a certain axial position of the bearing. When filling the bearing so it must be ensured that a reproducible distance d is present.

The air gap 48 . 148 . 248 . 348 but offers other benefits. Due to its small width and the axial course arise in the air gap 48 . 148 . 248 . 348 only very low centrifugal forces acting on the first sealing gap 34 can act fluid vapor. This ensures that the evaporated bearing fluid only very slowly through the air gap 48 . 148 . 248 . 348 can escape (diffuse). Instead, the fluid vapor collects in the region of the first sealing gap 34 , Due to the high concentration of fluid vapor in the sealing gap 34 Above the surface of the bearing fluid, the evaporation rate is additionally slowed down by the incoming saturation effect. The reduced loss of bearing fluid has a beneficial effect on the life of the bearing.

4 shows a device for filling a fluid dynamic bearing according to the invention with a bearing fluid. The storage system to be filled is introduced into a working chamber, which is indicated by a rectangle surrounding the storage system, wherein the working chamber is hermetically sealed. In the working chamber is a holding device 350 arranged, which has a cylindrical portion. The diameter and width of the cylindrical section are just so great that the hub 216 with the cup-shaped edge 216a can be slipped over the cylindrical portion with its lower recess. The cylindrical section is dimensioned so that in the example between the opposite upper surfaces of the edge 216a and the top, or the inner circumference, of the cylindrical portion forms an annular gap in each case. These two columns 357 . 358 connect this at the first sealing gap 34 lying open end of the bearing gap with the working chamber. It is important that the capillary seal of the first sealing gap 34 is not hermetically sealed from the volume of the working chamber. Another connection between the volume of the working chamber and the cavity of the first sealing gap 34 exists over the bearing gap 20 of the camp.

In a next step, the working chamber via the vacuum pump 356 evacuated and brought to a pressure P1, for example, 10 millibars. In a next step, by means of a filling device, not shown, for example, a predetermined amount of bearing fluid as a circumferential fluid ring in the region of the second sealing gap 32 applied to the bearing, so that the fluid ring the open sealing gap 32 completely wetted and closed. Is the bearing fluid in the region of the second sealing gap 32 applied, the working chamber is suddenly vented and preferably brought to ambient pressure, wherein P1 then corresponds to the atmospheric pressure. This can be done by means of a valve 354 respectively. In the cavity in the region of the sealing gap 34 However, it does not immediately set the same pressure as in the working chamber, because it is over the gap 357 and 358 only a very small flow cross-section available to allow pressure equalization. As a result, vacuum P2 still prevails in this cavity, while in the working chamber a higher pressure P1 prevails. As a result, the bearing fluid becomes higher pressure over the first seal gap 32 in the storage gap 20 pushed in and distributed in the bearing gap evenly into the first sealing gap 34 , At the same time takes place over the narrow column 357 and 358 slowly a pressure equalization between the working chamber and the cavity in the region of the first sealing gap 34 , The filling process is completed as soon as the pressure P2 corresponds to the pressure P1. The duration of pressure equalization between the working chamber and the cavity 114 can by the dimensions of the column 357 and 358 be determined and varied. Depending on the gap width and the volume of the bearing gap to be filled with bearing fluid, the pressure equalization must be either faster or slower.

LIST OF REFERENCE NUMBERS

10, 110, 210

baseplate

12, 112

wave

14, 114, 214

rotor component

14a, 114a, 214a

Area

16, 116, 216

bearing component

16a, 116a, 216a

edge

18, 118, 218

stop member

20

bearing gap

22a, 22b

radial bearings

24

separator gap

26, 126, 226

thrust

28, 128, 228

recirculation

30, 130, 230

cap

32

second sealing gap

34

first sealing gap

36, 136, 236

pump seal

38

second thrust bearing

40, 140

ferromagnetic ring

42, 142, 242

stator

44

permanent magnet

46

axis of rotation

48, 148

air gap

248, 348

air gap

350

holder

354

Valve

356

vacuum pump

357, 358

gap

d

Width of the air gap

R _i

Inner radius of the air gap

R _o

Outer radius of the air gap

L

Length of the air gap

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2010/0296190 A1 [0004]
• DE 102009020474 A1 [0006]

Claims (7)

Fluid dynamic bearing system, in particular for the rotary mounting of a spindle motor, with a stationary bearing component ( 12 . 112 ; 16 . 116 ; 18 ) and one about a rotation axis ( 46 ) rotatably arranged bearing component ( 14 ), wherein the fixed and rotatable bearing component during operation of the bearing by a bearing fluid filled with a bearing gap ( 20 ) are separated from each other, wherein the bearing gap ( 20 ) has a first and a second open end, which is defined by a first ( 34 ) and a second sealant ( 32 ) and along the storage gap ( 20 ) at least one fluid dynamic radial bearing ( 22a . 22b ) and at least one fluid dynamic thrust bearing ( 26 ) or alternatively at least one conical fluid-dynamic bearing is arranged, characterized in that beyond the first sealing means ( 34 ) an air gap ( 48 ; 148 ; 248 ; 348 ) which is dimensioned to have a flow constant k for which: 0.06 x 10 ^-12 m ³ <= k <= 1.62 x 10 ^-12 m ³ . Fluid dynamic bearing, in particular for the rotary mounting of a spindle motor, with a stationary bearing component ( 12 . 112 ; 16 . 116 ; 18 ) and one about a rotation axis ( 46 ) rotatably arranged bearing component ( 14 ), wherein the fixed and rotatable bearing component during operation of the bearing by a bearing fluid filled with a bearing gap ( 20 ) are separated from each other, wherein the bearing gap ( 20 ) has a first and a second open end, which is defined by a first ( 34 ) and a second sealant ( 32 ) and along the storage gap ( 20 ) at least one fluid dynamic radial bearing ( 22a . 22b ) and at least one fluid dynamic thrust bearing ( 26 ) or alternatively at least one conical fluid-dynamic bearing is arranged, characterized in that beyond the first sealing means ( 34 ) an air gap ( 48 ; 148 ; 248 ; 348 ), which is dimensioned to have a flow constant k, for which: 0.06 × 10 ^-12 m ³ <= k <= 8 × 10 ^-12 m ³ . Fluid dynamic bearing according to claim 1 or 2, characterized in that the air gap ( 48 ; 148 ; 248 ; 348 ) is annular and concentric with the axis of rotation ( 46 ) is arranged. Fluid dynamic bearing according to one of claims 1 to 3, characterized in that the air gap ( 48 ; 148 ; 248 ) parallel to the axis of rotation ( 46 ) of the bearing is arranged and has a gap width d and a length L. Fluid dynamic bearing according to one of claims 1 to 3, characterized in that the air gap ( 348 ) perpendicular or oblique to the axis of rotation ( 46 ) of the bearing is arranged and has a gap width d and a length L. Spindle motor with a fixed motor component ( 10 . 12 . 112 . 16 . 116 . 18 ) and a means of a fluid dynamic bearing system according to any one of claims 1 to 5 rotatably mounted engine component ( 14 ), and an electromagnetic drive system ( 42 ; 44 ) for driving the rotatable engine component. A hard disk drive driven by a spindle motor according to claim 6 and comprising at least one storage disk and at least one read-write device for reading and writing data from and to the storage disk.

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