CN1321274C - Fluid bearing - Google Patents
Fluid bearing Download PDFInfo
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- CN1321274C CN1321274C CNB021493006A CN02149300A CN1321274C CN 1321274 C CN1321274 C CN 1321274C CN B021493006 A CNB021493006 A CN B021493006A CN 02149300 A CN02149300 A CN 02149300A CN 1321274 C CN1321274 C CN 1321274C
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- axle sleeve
- bearing
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Abstract
The present invention provides a fluid bearing device. An inner space of a housing (2) sealed with a seal member (5) as well as internal pores of a bearing member (3) (pores in a porous structure) are filled with a lubricating oil without the presence of air, so that the oil surface of the lubricating oil is within a seal space S1. Under a reduced pressure of 100 Torr, no lubricating oil leaks outside of the housing (2) even at any attitude of the fluid lubricated bearing device (1) such as normal, inverted, or horizontal attitude.
Description
Technical field
The present invention relates to a kind of hydrodynamic bearing device, the oil film of this hydrodynamic bearing device by producing in the radial bearing gap supports rotary component by the non-contact mode; This hydrodynamic bearing device is suitable as information equipment most, for example: disk devices such as HDD, FDD, optical disk unit such as CD-ROM, CD-R/RW, DVD-ROM/RAM, spindle drive motors such as light-disk set of MD, MO etc., scanning apparatus motor such as duplicating machine, laser beam printer (LBP), bar code scanner, or electrical equipment, for example: miniature motors such as axial flow fan.
Background technique
Above-mentioned various motor except that demanding running accuracy, also requires high-speed, low cost, low noise etc.In one of main composition factor that determines these performance requirements, the bearing that this motor main shaft is supported is arranged.In recent years, studying the use of fluid type bearing with excellent above-mentioned requirements performance requirement, or actual the use.This fluid type bearing is divided into substantially: have the so-called hydrodynamic pressure bearing that the dynamic pressure of making occurs in the dynamic pressure generating mechanism on the lubricant oil in the bearing play; The so-called fluid round bearing (bearing surface is circular bearing) that does not have the dynamic pressure generating mechanism.
Fig. 7 demonstrates the structure example that the information equipment that fluid dynamic-pressure bearing device 31 is installed is used spindle drive motor.This spindle drive motor is to be used to disk drives such as DVD-ROM, and this device contains:
Hydrodynamic bearing device 31:, and freely support with spindle unit 32 rotations;
Supporting part 34: be mounted and put on spindle unit 32, for example support: CD 33 (at rotating disk shown in the legend) as driven object;
Motor stator 35: the slit by on the radial direction is oppositely arranged;
Motor rotor 36:
Hydrodynamic bearing device 31, as its critical piece, by:
Axle sleeve 21: side at one end, contain opening portion; Distolateral at other, contain the bottom;
Bearing part 22: be fixed on the inner peripheral surface of axle sleeve 21, be cylindric;
Spindle unit 32: be inserted on the inner peripheral surface of bearing part 22;
Thrust plate 24: the bottom that is set at axle sleeve 21;
Sealed member 23: be installed on the opening portion of axle sleeve 21; Constitute.On the outer peripheral surface of the inner peripheral surface of bearing part 22 or spindle unit 32, dynamic pressure is set takes place with groove (dynamic pressure groove).And, in the inner space of axle sleeve 21, inject lubricant oil.
Stator 35 is mounted the excircle of the axle sleeve 21 of fluid means 31, and rotor 36 is installed on the supporting part 34, if to stator 35 energisings, and then owing to excitation power in stator 35 and 36 generations of rotor, rotor 36 rotations.Thus, supporting part 34 constitutes an integral body, rotation with spindle unit 32.
Because the rotation of spindle unit 32, the radial bearing gap generation between the outer peripheral surface of the inner peripheral surface of bearing part 22 and spindle unit 32 causes the dynamic pressure effect of lubricant oil because of the dynamic pressure groove, radially with the outer peripheral surface of contactless shaft member 32.In addition, thrust plate 23 is at the end face of other distolateral (being downside in Fig. 7) of radial support spindle unit 32.
In addition, the dynamic pressure effect that also has the both sides between radial bearing gap and thrust bearing gap to produce is radially reaching the structure of Hand of spiral with non-contact mode shaft member.In general, in this bearing, because the space that the end face of the bearing part that the thrust bearing surface that is formed in the bottom with axle sleeve is relative with it fences up is seal structure, so make this confined space as far as possible to atmosphere opening, cylindrical at bearing part, make at its both ends of the surface opening, form axial groove (circle groove).
The lubricant oil that injects to the inner space of axle sleeve 21 carries out under the state of spindle unit 32 not being installed when spindle drive motor is installed usually, after oiling, spindle unit 32 is installed.Therefore, also exist at the inevitable air in the inner space of axle sleeve 21, because the variation of environment temperature and the heating of motor, or when transporting in the use of plateau section and in the space etc., the air thermal expansion of pressure change and axle sleeve inner space, contraction etc., lubricant oil is squeezed out from the seal space between the outer peripheral surface of the inner peripheral surface of sealed member 24 and spindle unit 32, leaks into outside possibility.
(configuration under the opening portion side direction of axle sleeve 21) and the horizontal form (the opening portion side of axle sleeve 21 being pressed the form of substantially horizontal configuration) of placing were when using when especially the motor configurations form was upside-down, lubricant oil is stuck in the opening portion side easily because of flowing, so oil leak easily takes place.
By the above-mentioned fact, the motor that existing hydrodynamic bearing device 31 is installed is unsettled in the use of being inverted under the situations such as configuration and horizontal placement form, and is subjected to using the restriction of form.
In addition, in the hydrodynamic bearing device 31 of above-mentioned formation, thrust bearing portion is the structure that other distolateral end face of spindle unit 32 is supported with thrust plate 23, and spindle unit 32 is extruded on the thrust plate 23 by the magnetic force of 36 of stator 35 and rotors.Therefore, regulation subtend one distolateral (upside in Fig. 7) moves axially.Yet, when the impact load that surpasses above-mentioned magnetic force etc. is added on the motor, and with motor with inverted form or laterally place form when using, existing spindle unit 32 has pair axle sleeve 21, at one end side moves axially and breaks away from the possibility of axle sleeve 21.
In the manufacturing process of bearing part, bearing part is configured in the mould by the sintering metal with sleeve shape, is processed to form given size through pressure-sizing.Shaping produces along with the demoulding and to rebound, and the excircle of bearing part expands at outside diameter, but the form that the part of the circle groove in the axle sleeve does not contact with mould and internal side diameter is oppressed.So, to compare with other place, the quantitative change of rebounding behind the demoulding is little.For this reason, shaping, as shown in Figure 8, the excircle of bearing part 22 and inner circumference are not circular, and will dwindle into the section state of minor diameter near the circle groove 25.Up to now, 2 places (being 180 ° relative position) at the excircle of bearing part 22 often form circle groove 25.At this moment, the section configuration of shaping is until being with the part of the circle groove 25 oval state as minor axis.
Yet at this oval state, narrow (short-axis direction) on the radial bearing gap between the excircle of the inner circumference of bearing part 22 and spindle unit 32 and wide part (long axis direction) go up and form.At this moment, on the broad in radial bearing gap,, hydrodynamic descends because of causing the shelling effect of bearing.So, might descend as the bearing rigidity on oval-shaped long axis direction, and cause the bearing distortion.To generation harmful effects such as NRRO.
Summary of the invention
Problem of the present invention is to provide a kind of hydrodynamic bearing device and with the motor of this its installation, the motor of this hydrodynamic bearing device and installation thereof high temperature, low temperature environment, plateau section use and reduced pressure atmosphere during air transport under, not because of the residual air expansion in axle sleeve inner space, contraction, lubricant oil is to external leaks, can be under form arbitrarily stable operation, transportation etc.
Other problem of the present invention is to break away from from axle sleeve to prevent spindle unit with predetermined axis distolateral to the axle sleeve of the spindle unit that relatively moves.
Other problem of the present invention is to degenerate by remove the bearing rigidity that causes in the distortion because of the bearing part after rebounding on all directions, guarantees the highi degree of accuracy rotation.
For above-mentioned problem is solved, the present invention aims to provide a kind of structure, and this structure is containing:
Axle sleeve: at one end side contains opening portion, in other distolateral bottom of containing;
Spindle unit: be stored in the axle sleeve;
Radial bearing portion: be arranged between the outer peripheral surface of the inner peripheral surface of bearing part and spindle unit, be used in the oil film of the lubricant oil that the radial bearing gap produces, spindle unit is supported diametrically in the non-contact mode;
Sealed member: be configured on the opening portion of axle sleeve, and form seal space between the above-mentioned spindle unit;
In the hydrodynamic bearing device that constitutes, above-mentioned seal space is cylindric or coniform, other of above-mentioned axle sleeve is distolateral to be airtight in above-mentioned bottom, even because of the inner residual air expansion of the axle sleeve under the reduced pressure atmosphere that is pressed onto 100Torr from atmosphere, lubricant oil does not leak into the outside yet, in the inner space of axle sleeve, fill up with lubricant oil, making in the above-mentioned seal space has pasta.
The hydrodynamic bearing device of above-mentioned formation, for example: the inner space of axle sleeve is evacuated behind the state, under atmospheric pressure open, by obtaining (vacuum oil immersion) with lubricant oil displacement (internal void of axle sleeve).Particularly, at the state of not oiling (for example: the state shown in Fig. 1～Fig. 4), after hydrodynamic bearing device installed, in vacuum tank with hydrodynamic bearing device all or one one (at least with hydrodynamic bearing device in the open part of outside) be immersed in the lubricant oil.Under this state, after the air of the inner space of axle sleeve vacuumized, under atmospheric pressure open, the inner space that makes lubricant oil be full of axle sleeve can obtain.
But because the degree of vacuum in the vacuum tank, after under atmospheric pressure opening, axle sleeve inside becomes only residual minim air.If residual air is many more,,, and the possibility that oil leak takes place is arranged so lubricant oil is extruded to the axle sleeve outside then because of expansion, the contraction of residual air with the variation of environment temperature environment.Particularly under with the motor reversion form or laterally placing when using under the form,, easily be detained because of the flowing of lubricant oil in the axle sleeve inner space in the opening portion side, therefore above-mentioned oil leakage easily takes place.For example: even residual air only is a trace, but also have in the reduced pressure atmosphere that high pressure region uses or air transport produced, residual air expands lubricant oil is expressed to the axle sleeve outside, and the oil leak of generation possibility is arranged.
As the main cause of air thermal expansion, though can enumerate temperature and air pressure, if calculate expansion, the contour projector of the temperature inferred as Environmental Conditions and air in air pressure range, the influence of then knowing air pressure is sizable.
Use, the storage condition of the small-sized spindle drive motor of fluid means of the present invention are installed, generally speaking, often are defined as following condition:
Temperature: 0～60 ℃ of serviceability temperature, storage temperature-40 ℃～90 ℃
Air pressure: barometric pressure～0.3atm during transportation (highly about 10000m)
If calculate the expansion ratio from the equation of gaseous state formula, then because of
PV＝nRT
P: pressure
V: volume
N: Mo Er constant
R: gas constant
T: kelvin temperature
So 1. certain at pressure, temperature is when changing for-40 ℃～90 ℃, then
V
90/ V
-40=363/233=1.56 doubly
2. certain in temperature, make pressure when atmosphere is pressed onto 0.3atm and changes, then
V90/V-40=1/0.3=3.33 doubly
In order to control the oil leak that produces by air expansion, under the environment in above-mentioned critical field, consider to have the pressure change of bigger influence, it is desirable making the structure that lubricant oil does not leak.
For example, be 10000m with the height setting that aloft transports, then because air pressure at that time is about 230Torr (0.3atm), therefore under the reduced pressure atmosphere of 230Torr (0.3atm),, need to inject lubricant oil in order not make oil leak.In the check when bearing is made, find to consider surplus with under the 100Torr, it is desirable that lubricant oil does not leak.
As mentioned above, hydrodynamic bearing device of the present invention and the motor that contains hydrodynamic bearing device of the present invention, even under reduced pressure atmosphere such as high temperature, low temperature environment, plateau section use and air transport, also not because of the expansion of the residual air in the axle sleeve, contraction lubricant oil to external leakage, be not subjected to the restriction of the configuration of motor, can stably transport and carry.
As mentioned above, owing to be the hydrodynamic bearing device that the axle sleeve inner space is full of by lubricant oil, make at the top and will form the such structure of embolism shape injector, so because of the transportation in bearing part such as vibration to moving axially, and, also have the effect that Control Shaft parts are in a way extracted from axle sleeve.
In addition, for solving above-mentioned problem, the present invention aims to provide a kind of structure, and this structure is containing:
Axle sleeve: at one end side contains opening portion, in other distolateral bottom of containing;
Bearing part and bearing part: be stored in the axle sleeve;
Radial bearing portion: be arranged between the outer peripheral surface of the inner peripheral surface of bearing part and spindle unit, be used in the lubricating oil oil film that the radial bearing gap produces, spindle unit is supported diametrically in the non-contact mode;
Thrust bearing portion: with other distolateral end face of bearing part in thrust direction upper support;
Sealed member: be configured in the hydrodynamic bearing device on the opening portion of axle sleeve, will stipulate to contact, axially be arranged on the spindle unit to the axle sleeve one distolateral protuberance that relatively moves to spindle unit with sealed member.
At this, " protuberance " can be by being set to integral body on spindle unit, or so-called spindle unit is fixed on sub-unit on the spindle unit and constitutes.In addition, the shape of " protuberance " is not particularly limited, and can adopt arbitrary shapes such as ring-type, part ring-type, point-like or needle-like.If spindle unit is subjected to external force or gravity, axially axle sleeve is being relatively moved one distolaterally, then protuberance contacts with sealed member, restrictive axes parts and abovely axially relatively moving.Therefore, spindle unit is maintained in the axle sleeve, can prevent extracting axle sleeve.
Said structure in addition, also can adopt lubricant oil to fill up the inner space of axle sleeve, even and by the expanding, shrink of the residual air in the axle sleeve inner space under the reduced pressure atmosphere from barometric pressure to 100Torr, also the structure of lubricant oil from the axle sleeve internal leakage can not take place.
In said structure, the axial clearance of 0.05mm～0.5mm can be set between protuberance and sealed member.The value of this axial clearance is the numerical value of other distolateral end face contact when thrust bearing portion of spindle unit.
For fear of in the protuberance of stable operation (when other distolateral end face of spindle unit turns round under the state of contact thrust bearing portion and support) and contacting of sealed member, therefore need between to set certain axial clearance.If the tolerance of size of each parts of balance and alignment error etc., then this axial clearance needs more than the 0.05mm.
On the other hand because the existence of above-mentioned axial clearance, if be in operation or transport in bearing means is added vibration or impact load etc. repeatedly, then spindle unit can axially relatively move to axle sleeve in the scope of above-mentioned axial clearance.Therefore, if above-mentioned axial clearance enlarges, axially relatively moving then because of spindle unit, air outside flow into axle sleeve inside by seal space (space between the inner peripheral surface of sealed member and the outer peripheral surface of spindle unit), or the lubricant oil that exists axle sleeve inside is extruded and leaks into outside possibility from above-mentioned seal space.In addition, above-mentioned axial clearance value becomes big more, the lubricants capacity that then is filled up to the axle sleeve inner space just becomes more, the variable quantity of the lubricant oil volume that thermal expansion, contraction produce is just big more, so,, do not make oil leak to the outside for by its volume change is absorbed, therefore, the volume of above-mentioned seal space appears needing to strengthen.Yet the axial dimension of increasing sealed member often exists difficulty from the angle that spatially limits; In addition, owing to strengthen the internal diameter size of sealed member, may be related to the decline (decline of siphon power) of sealing function, so be unfavorable.
If following machine test result, above-mentioned axial clearance is below the 0.5mm, then find to prevent lubricant oil from axle sleeve inside to external leaks, the OK range of above-mentioned axial clearance is 0.05mm～0.5mm, optimum range is 0.05mm～0.03mm.
In said structure, between the outer peripheral surface of the inner peripheral surface of the sealed member bearing part relative with it, can be at the conical seal space that enlarges gradually towards a distolateral setting.Because seal space is processed into above-mentioned taper shape, the lubricant oil in the seal space is being inhaled into because of siphon power to the direction that becomes narrow along with seal space (internal direction of axle sleeve).So, can prevent lubricant oil from the inside of axle sleeve to external leaks.
Above-mentioned conical seal space can be by in the outer peripheral surface of the inner peripheral surface of sealed member and bearing part, and the conical surface that is provided with in a direction constitutes at least.Outer peripheral surface at bearing part is provided with in the structure of conical surface, and when spindle unit rotated, the lubricant oil of seal space was subjected to centrifugal action, is inhaled into conical surface along spindle unit in the direction that narrows down to seal space (internal direction of axle sleeve).Therefore, add the suction effect of above-mentioned siphon power, because the suction effect that also has centrifugal force to produce, so can further improve the effect that prevents oil leak.
With the thrust bearing portion that is arranged on axle sleeve bottom with the bearing portion of spindle unit support in the thrust direction, in the hydrodynamic bearing device of contact structures, the surrounding space lubricating oil pressure that exists in thrust bearing portion raises, and the lubricant oil in the seal space between sealed member inner peripheral surface and spindle unit outer peripheral surface produces the situation of pressure difference.This pressure difference is except that axially forming the width of dynamic pressure groove with asymmetric in radial bearing portion, even it is symmetrical in design, but under situations such as machining error (taper shape of spindle unit and bearing part inner peripheral surface, the width dimensions precision of dynamic pressure groove etc.) is big, also can produce equally.
If this pressure difference of generation then exists and produces local decompression on the lubricant oil in the inner space of axle sleeve, in lubricant oil, generate bubble, become the reason that causes oil leakage and vibration generation etc. thus.And, because the pressure of the lubricant oil around the thrust bearing portion raises, the shelling of the spindle unit of generation, the perhaps opposite pressure step-down that also exists thrust bearing portion side, bearing part is extruded on the bearing part of thrust plate etc., and causes the situation of the unusual loss of bearing part.
This problem can be removed by the circle groove that setting makes thrust bearing portion be communicated with seal space.Even that is: produce under the situation of pressure difference, flow because lubricant oil produces between two spaces by circle groove, so the oil pressure in two spaces also can guarantee equipressure at lubricating oil between the surrounding space of thrust bearing portion and the seal space.
Above-mentioned circle groove is by having: for example:
The first radial direction groove: the bottom side in thrust bearing portion forms between the end face boss face on the other side of one side of bearing part;
The second radial direction groove:, between the end face sealed member on the other side of the opposite side of bearing part, form in the opening portion side of axle sleeve;
Axial groove: between the outer peripheral surface of bearing part and axle sleeve inside and outside circle side face, form and constitute.
In " hydrodynamic bearing device " of the present invention, though contain:
Hydrodynamic Hydrodynamic bearing apparatus: contain and make dynamic pressure occur in dynamic pressure generating mechanism on the lubricant oil in the bearing play;
Fluid round bearing device (bearing surface is circular bearing means): contain the dynamic pressure generating mechanism;
But the fluid dynamic pressure shaft apparatus for converting of stipulating more excellent axle support function is desirable.When being defined as the fluid dynamic pressure shaft apparatus for converting,, can pass through the radial bearing gap, in the outer peripheral surface of the inner peripheral surface of relative bearing part and spindle unit, the structure of dynamic pressure groove is set in an inner peripheral surface as above-mentioned " dynamic pressure generating mechanism "; Also can be: the formation (radial bearing surface of describing with several circular arcs also can be described as " arc bearing ") of an above-mentioned circumferential surface of describing with circular arcs such as several 2 circular arcs, 3 circular arcs, 4 circular arcs by non-circular, for example.Under the former instance,, can adopt also that (in radial bearing surface, the bearing that several axial grooves are set also can be called " step-by-step movement bearing " as man type, spirality, several axial flute profiles as the shape of dynamic pressure groove.) wait various well-known dynamic pressure groove shape.On the other hand, by the thrust bearing gap, at a face of opposing side by forming dynamic pressure grooves such as man type, spirality, also can constitute thrust hydraulic bearing portion, in addition, except that porous sintered metal, can also adopt Cuprum alloy, stainless steel, brass, aluminum alloy etc. as the material of bearing part.
In addition, for solving above-mentioned problem, the present invention's regulation has in its structure:
Spindle unit:
Bearing part: constitute by the oil-containing sintering metal, by the excircle and the radial bearing gap of spindle unit, relatively;
Axle sleeve: bearing part is fixed on the inner circumference;
In the relative running of spindle unit with bearing part, make hydrodynamic occur in the radial bearing gap, adopt contactless method shaft member, and excircle at bearing part, make at its both ends of the surface opening and form in the mobile bathtub construction of lubricating fluid, stipulate that above-mentioned groove is set at more than three, it would be desirable to be provided with three.
As mentioned above, by the groove more than three is set, owing to the bearing rigidity that can be increased on all directions, so just can improve the running accuracy of bearing.
A lip part that end face is relative with bearing part is set on spindle unit, by hydrodynamic is occurred in the thrust bearing gap that is formed between the end face of this end face of bearing part and lip part, even on the thrust direction, also can adopt contactless shaft member.At this moment, the lubricating fluid in thrust bearing gap can more flow in the groove because of the influence of centrifugal force, but if the circle groove more than three then also can absorb this lubricating fluid conscientiously.
During the asymmetrical shape of the dynamic pressure groove of bearing surface in lubricating fluid being expressed to above-mentioned thrust bearing gap, can further increase the influx of lubricating fluid, even but in this case, also have and to absorb unnecessary lubricating fluid to groove.
Description of drawings
Fig. 1 relates to the fluid dynamic-pressure bearing device sectional view of the present invention's the 1st example for expression.
Fig. 2 relates to the fluid dynamic-pressure bearing device sectional view of the present invention's the 2nd example for expression.
Fig. 3 relates to the fluid dynamic-pressure bearing device sectional view of the present invention's the 3rd example for expression.
Fig. 4 relates to the fluid dynamic-pressure bearing device sectional view of the present invention's the 4th example for expression.
The hydrodynamic bearing device sectional view of Fig. 5 for adopting in the machine test.
Fig. 6 is expression thermal cycling curve figure.
Fig. 7 is for installing the spindle drive motor sectional view of existing hydrodynamic bearing device.
Fig. 8 is 2 arc bearing device cross-section profiles.
Fig. 9 forms several axial flute profile dynamic pressure groove embodiments' sectional view at the inner peripheral surface of bearing part as the dynamic pressure generating mechanism for expression.
Figure 10 is made of embodiment's sectional view of bearing part inner peripheral surface several circular arcs as the dynamic pressure generating mechanism for expression.
Figure 11 is made of embodiment's sectional view of bearing part inner peripheral surface several circular arcs as the dynamic pressure generating mechanism for expression.
Figure 12 is made of embodiment's sectional view of bearing part inner peripheral surface several circular arcs as the dynamic pressure generating mechanism for expression.
Figure 13 is defined as the embodiment of the radial bearing portion sectional view of the round bearing that does not possess the dynamic pressure generating mechanism for expression.
Figure 14 has an example sectional view of circle groove hydrodynamic bearing device for expression.
Figure 15 has other example sectional view of circle groove hydrodynamic bearing device for expression.
Figure 16 is the test result figure of expression decompression test.
Figure 17 is the test result figure of expression installation test.
Figure 18 is the test result figure of expression oil leak test.
Figure 19 is the test result figure of expression oil leak test.
The profile diagram of the fluid dynamic-pressure bearing device that Figure 20 relates among the present invention for expression.
Figure 21 is the bearing part oblique drawing.
Figure 22 is no dimension rigidity figure in the various bearings of expression.
Figure 23 is 3 arc bearing cross-section profiles.
Figure 24 is 4 arc bearing cross-section profiles.
Figure 25 is the cross-section profile of explanation eccentricity.
Figure 26 is at the profile diagram that axially forms the dynamic pressure type bearing means of asymmetrical radial bearing surface.
Embodiment
Example of the present invention below is described.
Fig. 1 represents to relate to the fluid dynamic-pressure bearing device 1 of the invention process form.This hydrodynamic bearing device 1, for example: as shown in Figure 7, be to be mounted to the information equipment spindle drive motor, as its critical piece, by
Axle sleeve 2: at one end side (upside in Fig. 1) has opening portion 2a, has bottom 2c at other distolateral (downside in Fig. 1), and being has end shape cylindric;
Bearing part 3: be fixed on the inner peripheral surface of axle sleeve 2, be cylindric;
Spindle unit 4:
Sealed member 6: the opening portion 2a that is fixed on axle sleeve 2 goes up and constitutes.As described below, between the inner peripheral surface 3a of bearing part 3 and the outer peripheral surface 4a of spindle unit 4, the 1st R1 of radial bearing portion and the 2nd R2 of hydraulic bearing portion are set in axial isolation.In addition, between the downside end face 4b of the bottom of axle sleeve 2 2c and spindle unit 4, the T of thrust bearing portion is set.
Bearing part 3 is by for example: the porous body that sintering metal constitutes especially is that the sintering metal porous body of Main Ingredients and Appearance forms with copper.In addition, on the inner peripheral surface 3a of bearing part 3, in axial isolation, be arranged on two scopes up and down that are radial bearing surface (radial bearing surface of the 1st R1 of radial bearing portion and the 2nd R2 of radial bearing portion).In these scopes, form the dynamic pressure groove respectively, for example: man type dynamic pressure groove 3a1,3a2.
The outer peripheral surface 4a of spindle unit 4 is inserted in the inner peripheral surface 3a of bearing part 3, by holding the bearing part gap, in that to be the scope (scope at two places up and down) of radial bearing surface relative respectively with the inner peripheral surface 3a of bearing portion 3.In addition, the downside end face 4b of spindle unit 4 contacts with the top of thrust plate 6.
The inner peripheral surface 5a of sealed member 5 is by relative with the gap of the outer peripheral surface 4a defined of spindle unit 4.Between forms seal space S1 cylindraceous thus.Contain the internal porosity (pore of porous organization) of bearing part 3 with the inner space of the axle sleeve 2 of sealed member 5 sealing, air is not mingled with, filled up by lubricant oil, the pasta of its lubricant oil is positioned at seal space S1.The volume settings of seal space S1 is should be greater than the temperature variant variable quantity of the volume of lubricant oil in the serviceability temperature scope of the inner space that is filled in axle sleeve 2.According to this method, when volume changes even the volume of lubricant oil varies with temperature, usually the pasta of lubricant oil can be remained in the seal space S1.
For example under following form, lubricant oil is injected into the inner space of axle sleeve 2.At first, each parts (axle sleeve 2, bearing part 3, spindle unit 4, thrust plate 6, sealed member 5) are installed, the hydrodynamic bearing device 1 of not oiling are installed, with this not the hydrodynamic bearing device 1 of oiling in vacuum tank, be immersed in the lubricant oil.The air of axle sleeve 2 inner spaces is discharged through vacuumizing in vacuum tank.Be the not state of air entrainment in this inner space.Then, if in barometric pressure, open wide, fill up the inner space of axle sleeve 2 with lubricant oil.Lubricant oil injects and finishes, and then takes out hydrodynamic bearing device 1 from vacuum tank, and is warmed up to the upper limit working temperature of hydrodynamic bearing device 1.Along with this intensification, be filled in the lubricant oil generation thermal expansion of axle sleeve 2 inner spaces, remaining lubricant oil is discharged into the outside from seal space S1.By this method, even hydrodynamic bearing device 1 is when the work upper limiting temperature turns round, the pasta of lubricant oil also can maintain in the seal space S1.Then, stop if heating up, the pasta of lubricant oil descends along with temperature and reduces, and drops to the proper level in the seal space S1.
In above-mentioned oiling operation, according to the degree of vacuum in the vacuum tank, sometimes also residual the micro-air in axle sleeve 2 inner spaces, but this air quantity is when the defined level, promptly using as hydrodynamic bearing device 1 and the motor installed thereof in hypothesis, under the environmental conditions of transportation environment, also can stipulate because the residual air expansion in inner space of axle sleeve 2, squeeze out lubricant oil and do not leak into the level of the outside of axle sleeve 2 from seal space s1.In this example, even under the decompression of 100Torr, with hydrodynamic bearing device 1 with just put form (with the form on the opening portion 2a side direction of axle sleeve 2), reversion form (with the form under the opening portion 2a side direction of axle sleeve 2), when laterally placing form (with the form of the opening portion 2a side horizontal arrangement of axle sleeve 2), tilting form (form of the opening portion 2a lateral tilt direction configuration of axle sleeve 2), regulation lubricant oil should not leak into the outside.
In the hydrodynamic bearing device 1 of said structure, if spindle unit 4 rotations, then produce the lubricant oil dynamic pressure in above-mentioned radial bearing gap, the outer peripheral surface 4a of spindle unit 4 carries out contactless support because the oil film of the lubricant oil that forms radially can freely rotate in above-mentioned radial bearing gap.Thus, be formed in, at radially rotation freely, the 1st R1 of radial bearing portion of contactless support freely and the 2nd R2 of radial bearing portion spindle unit 4.Simultaneously, the downside end face 4b of spindle unit 4 is by thrust plate 6 contacts, support; Therefore, spindle unit 4 constitutes at the T of thrust bearing portion that the thrust direction is freely rotated, supported.
Even the hydrodynamic bearing device of this example 1 changes because of environment temperature and the heating of motor, or use in the plateau section and during air transport etc. the residual air in axle sleeve inner space under the reduced pressure atmosphere produce and expand, shrink, and be subjected to the form of motor, lubricant oil also not from the internal leakage of axle sleeve 2 to the outside, can stably move, transport.
Fig. 2 represents to relate to the hydrodynamic bearing device 1 ' of the 2nd example.The seal space S2 that forms between the outer peripheral surface of the spindle unit 4 ' that the hydrodynamic bearing device 1 ' of this example is relative with it with the inner peripheral surface that above-mentioned the 1st example difference is sealed member 5 ' forms the taper shape that enlarges gradually at one distolateral (outside direction) of axle sleeve 2.In this example, in order to form conical seal space S2, the inner peripheral surface of sealed member 5 ' to one distolateral, is arranged to the circumferential surface 5a ' of hole enlargement form gradually; And on the outer conical surface of the spindle unit 4 ' relative with circumferential surface 5a ' to a distolateral conical surface 4a1 ' who is arranged to be gradually the tube reducing shape; And can be set at barrel surface in any one side among conical surface 5a ' and the conical surface 4a1 '.
Shown in amplifying in the broken circle among Fig. 2, owing to exist the pasta of lubricant oil L in seal space S2, the lubricant oil L in the seal space S2 is because of siphon power, and (other is distolateral: the internal direction of axle sleeve 2) to the direction that narrows down to be inhaled into seal space S2.For this reason, can prevent effectively lubricant oil L from the inside of axle sleeve 2 to external leaks.On the other hand, because conical surface 4a1 ' is set on the outer peripheral surface of spindle unit 4 ', when spindle unit 4 ' running, the lubricant oil L in the seal space S2 is subjected to centrifugal force, is inhaled into seal space S2 along conical surface 4a1 ' and is narrow direction (internal direction of axle sleeve 2).Therefore, add the suction effect that above-mentioned siphon power produces,, therefore, compare, further improved the effect that prevents lubricant oil L leakage with the hydrodynamic bearing device 1 of above-mentioned the 1st example in addition also because the suction effect that centrifugal force produces.
Fig. 3 represents to relate to the fluid dynamic-pressure bearing device 1 of the 3rd example.This hydrodynamic bearing device 1 has been owing to installed for example information equipment spindle drive motor shown in Fig. 7, therefore, as its critical piece by
Axle sleeve 2: at one end side (upside in Fig. 3) has opening portion 2a, at other distolateral (downside among Fig. 3) bottom is arranged, and being has the round-ended cylinder shape;
Bearing part 3: be fixed in the inner peripheral surface of axle sleeve 2, be cylindric;
Spindle unit 4:
Sealed member 5: be fixed on the opening portion 2a of axle sleeve 2; Constitute.As described below, between the outer peripheral surface 4a of the inner peripheral surface 3a of bearing part 3 and spindle unit 4, the 1st R1 of radial bearing portion is set and the 2nd R2 of hydraulic bearing portion isolates at axle direction.In addition, between the downside end face 4b of the bottom of axle sleeve 2 2c and spindle unit 4, the T of thrust bearing portion is set.
Bearing part 3 is by for example: the porous body that sintering metal constitutes particularly is that the sintering metal porous body of Main Ingredients and Appearance forms with the steel.In addition, on the inner peripheral surface 3a of bearing part 3, two scopes up and down that are radial bearing surface (radial bearing surface of the 1st R1 of radial bearing portion and the 2nd R2 of radial bearing portion) are set on axle direction isolate.In these scopes, form the dynamic pressure groove respectively, for example: man type dynamic pressure groove 3a1,3a2.
The outer peripheral surface 4a of spindle unit 4 is inserted on the inner peripheral surface 3a of bearing part 3, is the scope (two scopes up and down) of radial bearing surface of the inner peripheral surface 3a of bearing part 3, and is relative by the radial bearing gap respectively.In addition, the downside end face 4b of spindle unit 4 contacts with the top of thrust plate 6.
The packing ring 7 that is provided with on the spindle unit 4 is configured in the X of axially spaced-apart portion, the downside end face 4b of spindle unit 4 with state of contact above the thrust plate 6 under, between the downside end face 5b of the upside end face 7a of packing ring 7 and sealed member 5, axial clearance X1 is set, between the upside end face 3b of the downside end face 7b of packing ring 7 and bearing part 3, axial clearance X2 is set.The size of axial clearance X1 is 0.05mm～0.5mm, it would be desirable 0.05mm～0.3mm.Axial clearance X2 is when spindle unit 4 rotation, and the downside end face 7b of packing ring 7 can be set at the size that does not contact with the upper-end surface 3b of bearing part 3, but weighs the tolerance of size of each parts and alignment error etc., and it is desirable being defined as more than the 0.05mm.The size of this axial clearance X2 also can be defined as identical with axial clearance X1, and also comparable axial clearance X1 is big or little.
It is relative that the inner peripheral surface 5a of sealed member 5 and the outer peripheral surface 4a of spindle unit 4 separate predetermined gap.Therefore, between forms seal space S1 cylindraceous.Contain the internal porosity (pore of porous shape tissue) of bearing part 3 with the inner space of the axle sleeve 2 of sealed member 5 sealing, air entrainment does not fill up with lubricant oil, and the pasta of its lubricant oil is positioned at seal space S1.The variable quantity of volume settings in the seal space S1 for changing at serviceability temperature scope internal cause temperature change volume greater than the lubricant oil of the inner space of filling up axle sleeve 2.Thus, even when the volume of lubricant oil occurs changing with temperature, also the pasta of lubricant oil usually can be remained in the seal space S1.
Inner space to packing ring 2, become injection lubricant oil, even be pressed onto from atmosphere under the reduced pressure atmosphere of 100Torr, the air residual in the axle sleeve inner space expands, shrinks, and not limited by the form of motor, and form lubricant oil not from the structure of the internal leakage of axle sleeve 2.
In this example, spindle unit 4 is subjected to external force and gravity, and at one end side produces axle sleeve 2 and axially relatively moves, and the packing ring 7 that then is arranged on spindle unit 4 contacts with sealed member 5, therefore, to spindle unit 4 separate provision more than it, axially relatively move.Thus, spindle unit 4 can usually remain in the axle sleeve 2, prevents to skid off from axle sleeve 2.
On the other hand, because the bearing play X1 of 5 of packing ring 7 and sealed members is set in the scope of 0.05mm～0.5mm, so (when the lower end surface 4b of spindle unit 4 rotates under the state of contact thrust plate 6, support) packing ring 7 does not contact with sealed member 5 when steady running, can obtain running state stably.In addition, even when spindle unit 4 moves axially relatively in the scope of axial clearance X1, air also flow into the inside of axle sleeve 2, or the lubricant oil that does not fill up packing ring 2 inside does not take place to be extruded from seal space S1 and leaks into outside phenomenon.
Other item, because according to the 1st example, and the explanation that will repeat is omitted.
Fig. 4 represents to relate to the hydrodynamic bearing device 1 ' of the 4th example, the hydrodynamic bearing device 1 ' of this example is with the difference of above-mentioned the 3rd example, the seal space S2 that will form between the outer peripheral surface between the inner peripheral surface of sealed member 5 ' and relative spindle unit 4 ' thereof goes up at one distolateral (outside direction) of packing ring 2 and to form the taper shape that enlarges gradually.In this example,, on the inner peripheral surface with sealed member 5 ', the conical surface 5a ' to a distolateral hole enlargement shape gradually is set in order to form conical seal space S2; And, be provided with to a distolateral conical surface 4a1 ' of undergauge shape gradually that is at the outer peripheral surface of the relative spindle unit 4 of conical surface 5a '.In addition, can be in conical surface 5a ' and conical surface 4a1 ' one squarely become barrel surface.
Shown in the part that enlarges in the broken circle among Fig. 4, by in seal space S2, existing the pasta of lubricant oil L, the lubricant oil L in the seal space S2.Be narrow and small direction to seal space S2 (other is distolateral: the internal direction of axle sleeve 2) because of siphon power is drawn into.For this reason, can effectively prevent lubricant oil L from the inside of axle sleeve 2 to external leaks.On the other hand, by at the outer peripheral surface of spindle unit 4 ' by conical surface 4a1 ' is set, when spindle unit 4 ' rotation, the lubricant oil L in the seal space S2 is subjected to centrifugal force, is drawn into seal space S2 along coned face 4a1 ' and is narrow direction (internal direction of axle sleeve 2).Therefore, add the suction effect that above-mentioned siphon power produces, the also suction effect that produces owing to centrifugal force is so the hydrodynamic bearing device 1 than above-mentioned the 3rd example has further improved the effect that prevents that lubricant oil from leaking.
In the example of above explanation, on the inner peripheral surface 3a of the bearing part 3 that is radial bearing surface (radial bearing surface of the 1st R1 of radial bearing portion and the 2nd R2 of radial bearing portion), as the dynamic pressure generating mechanism, form man type dynamic pressure groove 3a1,3a2, but the replacement man type also can form spiral and start indent.Or as shown in Figure 9, on the 3a of the inner peripheral surface of the bearing part 3 that is radial bearing surface,, also can form the dynamic pressure groove 3a3 (so-called " step-by-step movement bearing ") of several axial groove shapes as the dynamic pressure generating mechanism.
Or as Figure 10～shown in Figure 12, as the dynamic pressure generating mechanism, also can be by non-circular, for example: several arc of circle constitute the inner peripheral surface 3a (what is called " arc bearing ") of the bearing part 3 that is radial bearing surface (radial bearing surface of the 1st R1 of radial bearing portion and the 2nd R2 of radial bearing portion).Example shown in Figure 10 is the structure that is made of the inner peripheral surface 3a of bearing part 3 two arc surfaces (3a4,3a5).The centre of curvature O2 of the centre of curvature O1 of arc surface 3a4 and arc surface 3a5 is the outer peripheral surface 4a (circle) of equidistant off-axis parts 4 respectively; Example shown in Figure 11 is the structure that is made of the inner peripheral surface 3a of bearing part 33 arc surfaces (3a6,3a7,3a8).The centre of curvature of arc surface 3a6 is O3, and the centre of curvature of arc surface 3a 7 is O4, and the centre of curvature of arc surface 3a 8 is O5, respectively the outer peripheral surface 4a (circle) of equidistant off-axis parts 4.Example shown in Figure 12 is the structure by the inner peripheral surface 3a of the bearing part 3 of 4 arc surfaces (3a9,3a10,3a11,3a12) formation.The centre of curvature of arc surface 3a9 is O6, and the centre of curvature of arc surface 3a10 is O7, and the centre of curvature of arc surface 3a11 is O8, and the centre of curvature of arc surface 3a12 is O9, respectively the outer peripheral surface 4a (circle) of equidistant off-axis parts 4.
Even above dynamic pressure generating mechanism also can be arranged on the outer peripheral surface 4a of spindle unit 4.
Or as shown in figure 13, also can be with the 1st R1 of radial bearing portion (the 2nd R2 of radial bearing portion) as not possessing the dynamic pressure generating mechanism.
Example shown in Figure 14, be in the fluid dynamic-pressure bearing device of the example shown in Fig. 1 and Fig. 2, be used in the place on configuration and the circumferencial direction or the circle groove 10 of number place (being two places in the illustrated example), make the structure of the seal space S1 UNICOM between the outer peripheral surface 4a of the inner peripheral surface 5a of T of radial bearing portion and sealed member 5 and spindle unit 4.
The inner peripheral surface 5a of sealed member 5 separates predetermined gap, relative with the outer peripheral surface 4a of spindle unit 4.Thus, form cylindric seal space S1 between the two.Contain the internal porosity (pore of cellular tissue) of bearing part 3 with the inner space of the axle sleeve 2 of sealed member 5 sealing, air is mingled with, filled up by lubricant oil, the pasta of its lubricant oil is positioned at seal space S1.Volume settings in the seal space S1 is for should be greater than the lubricant oil of the inner space that is filled in axle sleeve 2 in the serviceability temperature scope, the variable quantity that volume changes with the change of temperature.Thus, even when lubricant oil changes with temperature change, the pasta of lubricant oil usually can maintain in the seal space S1.
In the example shown in Figure 14, first and second radial direction groove 10a, 10c all form in both ends of the surface 3c, the 3b of bearing part 3, and axle direction groove 10b forms at the outer peripheral surface of bearing part 3.During spindle unit 4 rotations, for example: in the space (space around the shaft end of spindle unit 4) of the T of thrust bearing portion, if the pressure of lubricant oil raises, then by circle groove 10, lubricant oil produces around the T of thrust bearing portion and flows to seal space S1, thus, the T of thrust bearing portion around with seal space S1 around on lubricating oil pressure remain equipressure.Therefore, bubble generates along with the generation of local reduction in the lubricant oil, can prevent that the lubricating fluid that causes thus leaks with vibration etc.In addition, around the T of thrust bearing portion, because of the shelling that also can prevent spindle unit 4 of lubricating oil pressure rising.With above-mentioned opposite, the pressure of seal space S1 is when raising when identical, circle groove 10 guarantee the thrust bearing T of portion around with seal space S1 equipressure, also can prevent to be extruded to this disadvantage of inordinate wear that axle sleeve bottom 2C goes up the thrust plate 6 that produces with spindle unit 4 because the generation of bubble causes oil leak etc.
Figure 15 is formed on example on the parts (axle sleeve 2 and sealed member 5) relative with bearing part 3 with circle groove 10 '.That is: the first radial direction groove 10a ' is formed on the inner side surface 2c1 of axle sleeve bottom 2c; The second radial direction groove 10c ' is formed on the inner side surface 5b ' of sealed member 5; Axial groove 10b ' is formed on the inner peripheral surface of axle sleeve sidepiece 2b.Also can obtain the effect identical by this circle groove 10 ' with the example shown in Figure 14.
In Figure 14, represent cylindric seal space S1 in addition, in Figure 15, represent conical seal space S2, but the shape of seal space is not particularly limited.Opposite with it, in the example of Figure 14, also can use conical seal space S2; In the example of Figure 15, can use seal space S1 cylindraceous.
Embodiment
Illustrate at Fig. 1 on the hydrodynamic bearing device 1 of form and inject lubricant oil down in above-mentioned form (vacuum oil immersion), by changing the degree of vacuum in the vacuum tank at that time, made and made the residual air quantity in inner space of axle sleeve 2 produce different 5 kinds of test bearing devices (embodiment 1～2, comparative example 1～3) after under atmospheric pressure opening.Residual air amount in the axle sleeve inner space behind the mensuration vacuum oil immersion is very difficult, but for example if the degree of vacuum in the vacuum tank is depressured to 380Torr (atmospheric 1/2), then owing to the air that can calculate to the inner space volume of the inner residual 50vol% of having of axle sleeve after in barometric pressure, opening wide, so extrapolate the residual air amount in this way.
Adopt above-mentioned each bearing means, check lubricant oil has or not leakage (decompression test) when placing under reduced pressure atmosphere; And the motor that various bearing meanss is mounted to model machine; Under atmospheric pressure change the operation form, check has or not oil leak (installation test) when ON-OFF moves; Test result is shown in Figure 16 (decompression test), Figure 17 (installation test).In addition, test conditions is as described below:
The negative booster test
Degree of vacuum: 100Torr
The installation test
Use motor: CD-ROM model machine motor
Rotating speed: 8000rpm
Atmosphere temperature: 60 ℃
Motor configurations form: just put, laterally place, be inverted
Operating condition: ON-OFF (30 seconds one-periods)
Machine test period: 300,000 cycles
In the negative booster test, the air quantity residual owing to the axle sleeve volume inside is different and variant according to the degree of vacuum of vacuum tank, so even vacuum oil immersion, but the phenomenon (comparative example 1～3) that oil leak takes place is under reduced pressure also arranged.
In the installation test, oil leak in horizontal placement or reversion form, is taken place in 5 to 200,000 cycles in lubricant oil drop (comparative example 2, comparative example 3).Lubricant oil leaks under whole configuration of 300,000 cycles to carry out vacuum oil immersion (embodiment 1, embodiment 2, comparative example 1) on the other hand.
Therefore can provide a kind of hydrodynamic bearing device that oil leak does not take place, this device is as described in the embodiment, by under 100Torr, injecting the lubricant oil do not leak, even under any use form of inferring, environmental conditions, also can be stable move, transport.
In addition, produce in structure shown in Figure 3,, axial clearance X1 is set at three kinds of hydrodynamic bearing devices (embodiment 3～5) of 0.1mm, 0.3mm, 0.5mm 5 of packing ring 7 and sealed members.On the spindle unit 4 of various hydrodynamic bearing devices 1, install and the model machine lazy fast disk 9 (Fig. 5) of even load mutually, after carrying out the test of 1000G drop impact, check lubricant oil that the internal leakage of the packing ring 2 of having no way of is arranged.Impact value 1000G is the HDD device used with reference to notebook computer etc., and the shock-resistant load characteristic that the spindle drive motor of uses such as portable consumer in recent years requires is set.In addition, with condition same as described above existing hydrodynamic bearing device shown in Figure 7 has been carried out testing (comparative example 4).Figure 18 illustrates test result.
When Figure 18 illustrated test result and finds to add the load of 1000G again, in comparative example 4, spindle unit broke away from (bearing shelling) from axle sleeve, and the bearing disengaging does not take place in embodiment 3～embodiment 5.Do not find oil leak yet.
In addition, the hydrodynamic bearing device of the foregoing description 3～embodiment 5 and comparative example 4 is installed in respectively on the model machine motor (laser beam printer wide-angle scanner motor), after the operation, whether check lubricant oil is from the axle sleeve internal leakage under the following conditions.Test result is shown in Figure 19.
Operating conditions
Model machine motor: LBP wide-angle scanner motor
Rotating speed: 30000rpm
Thermal cycling curve: with reference to Fig. 6
Test period: 20 cycles
Motor configurations form: laterally place form, reversion form
From Figure 19, test found that when Heating Cyclic is moved, in comparative example 4, oil leak occurs, but in embodiment 3～5, even laterally placing any form configuration of form, reversion form, all do not find oil leak.
Demonstrate the following effect that illustrates from above the present invention.
(1) under reduced pressure atmosphere, particularly since from barometric pressure to the 100Torr environment, even the air residual in the axle sleeve inner space expands, shrink, lubricant oil does not leak into outside level but owing to filling up the axle sleeve inner space with lubricant oil, so at high temperature, low temperature environment, and the reduced pressure atmosphere when plateau section use and air transport is inferior, use with motor, under any environmental conditions that transportation environment is inferred, even just putting form in employing, reversion form, laterally place form etc. arbitrarily during form, also can make lubricant oil not from axle sleeve inside to external leaks, stably move, transportation.
(2), under the state of air entrainment not, can prevent because of the oil leak of sneaking into generation of air and the generation of cavitation erosion by filling up lubricant oil in the axle sleeve inner space.
(3) because of contacting with sealed member, by being defined in a distolateral protuberance of the spindle unit axle sleeve that axially relatively moves, spindle unit is usually remained in the axle sleeve, prevent to break away from from axle sleeve.
(4) by the axial clearance of 0.05mm～0.5mm is set between protuberance and sealed member, can avoid contacting of protuberance and sealed member, can obtain stable running state.Simultaneously, even when spindle unit axially relatively moving in above-mentioned axial clearance scope, also can prevent air flow into axle sleeve inner with prevent the leakage of lubricant oil from axle sleeve inside.
(5) between the outer peripheral surface of the circumferential surface of the sealed member spindle unit relative,,, can further prevent the leakage of lubricant oil effectively to improve sealing by being provided with to a distolateral conical seal space that enlarges gradually with it.
(6) circle groove that thrust bearing portion is communicated with by setting with seal space is even when the situation of thrust bearing portion and seal space generation lubricant oil pressure difference, also can make both equipressures.Therefore can prevent disadvantages such as abnormal wear by the bubble generation that causes of pressure difference, oil leak, bearing shelling, thrust plate.
Figure 20 is other example of expression fluid dynamic-pressure bearing device.Dynamic pressure type bearing means in this example, its main structure has:
Bearing part 3: cylindric;
Spindle unit 4:
Axle sleeve 2: end tubbiness is arranged
Parts constitute.
Bearing part 3 makes lubricant oil or lubricating grease oil immersion on sintering metal, make pore contain oil the oil-containing sintering metal on form.As sintering metal, for example can use: copper base or iron-based or both sides are the metal of main component, and the optimal cupric 20～95% that is to use is shaped.This bearing part 3 is with in the past identical, each operation through press-powder shaping → sintering → shaping → oil-containing is made, through the inner peripheral surface of the resulting bearing part 3 of this method and at the end face 3c of a direction, form following dynamic pressure by means such as punch process and take place with groove 3a1,3a2 (dynamic pressure groove).
At the inner circumference of bearing part 3, form the 12a, the 12b that have the radial bearing surface of several dynamic pressure grooves 3a1,3a2 as the dynamic pressure generating mechanism.In illustrated example, illustrate for example and make in axial isolation, form the situation of two radial bearing surface 12a, 12b, but the quantity of radial bearing surface 12a, 12b is not limited in two, also can be more than one or three. Radial bearing surface 12a, 12b, dynamic pressure groove 3a1,3a2, if be enough to axial one-tenth tilted shape.Except that circular array shown in figure, also can be arranged in spirality.In addition, also can use non-circular radial bearing surface with dynamic pressure grooves such as mediation waveforms.
Axle sleeve 2 is an end opening, and forming simultaneously has an end tubbiness with other end sealing.Bearing part 3 is at the inner circumference of axle sleeve 2, fixes by means such as being pressed into or bonding.At this moment, dispose the axial region 4c of spindle unit 4 at the inner circumference of bearing part 3.Spatial configuration lip part 4d between a square end face 3c of the bottom of axle sleeve 2 2c and bearing part 3.Axle sleeve bottom 2c, as shown in the figure, except that with the sidepiece 2b unitary moulding of tubbiness, also can on sub-unit, form, by with these parts interlocks, installation with sidepiece 2b.The opening portion of sidepiece 2b is owing to preventing that oil from flowing out as lubricating fluid, so, by sealed member 5 sealings, between the end face 3b of sealed member 5 bearing part 3 relative with it, in order to improve the oil storage effect, therefore form axially small gap, under this state, two end face 4d1, the 4d2 of lip part 4d, respectively with an end face 3c of bearing part 3, and the thrust bearing surface 9a1 of axle sleeve bottom 2c is relative.On the inner bottom surface 2c1 of the 3c of the bearing part 3 relative and axle sleeve bottom 2c, form thrust shaft bearing surface 11a, the 11b that has as several dynamic pressure grooves (omitting in the diagram) of dynamic pressure generating mechanism respectively with lip part 4d.The dynamic pressure groove shape of thrust shaft bearing surface 11a, 11b is arbitrarily, except that identical with radial bearing surface 12a, 12b, forms outside man type or the spirality dynamic pressure groove, also can form stepping type thrust shaft bearing surface.The dynamic pressure groove replaces bearing part end face 3c and inner bottom surface 2c1, can form on two end face 4d1, the 4d2 of lip part 4d.At this moment, on two end face 4d1, the 4d2 of lip part 4d, form above-mentioned thrust shaft bearing surface.
Micro-gap between the outer peripheral surface of radial bearing surface 12a, 12b and axial region 4c (radial bearing gap), and the micro-gap (thrust bearing gap) between thrust shaft bearing surface 11a, face (illustrated example is two end face 4d1, the 4d2 of lip part 4d) that 11b is relative with it fills up the oil as lubricating fluid respectively.(during 4 operations of this example axis parts) are because the effect of each bearing surface 12a, 12b, 11a, 11b when the 3 relative rotations of spindle unit 4 and bearing part, produce oily dynamic pressure in radial bearing gap and thrust bearing gap, spindle unit 4 radially and on the both direction of thrust direction is supporting in the non-contact mode bearing part 3.
On the excircle of bearing part 3, in the face of axially being formed on the groove of these both ends of the surface 3b, 3c upper shed, promptly circle groove 10.This circle groove 10 is to make the seal space between the end face 3c of the bottom of axle sleeve 2 2c and bearing part 3 and the structure of bearing external communications, is bringing into play as making oil in the axially path effect of circulation.Oil in the circle groove 10 is absorbed by bearing part 3, on the other hand, oozes out from the surface of bearing part 3 and to resupply each bearing play.In the present invention, because following reason stipulates that this circle groove 10 uniformly-spaced is provided with more than three in a circumferential direction, it would be desirable three (with reference to Figure 21).
So, when forming three circle grooves 10, part owing to circle groove 10 after the shaping is different with the amount of rebounding of other parts, so bearing part 3, as shown in figure 23, be deformed into the summary triangular section (following bearing part with this distortion is called " 3 arc bearing ") that constitutes by three large diameter circular arcs 13; In addition, when forming four circle grooves 10, because same reason, the bearing part of shaping as shown in figure 24, is deformed into four summary Quadrilateral cross-sections that are made of four large diameter circular arcs 13 (being also referred to as " 4 arc bearing "); Though omit in the diagram, when the circle groove of being arranged to more than 5 10, also be deformed into the section of polygon (" 5 arc bearing ", " 6 arc bearing " etc.) with large diameter circular arc identical with circle groove 10 quantity.In addition, Figure 23 and Figure 24, for popular understanding, thus the amplifying property of deformation rate of circle ground is described, but can not clearly recognize the distortion of this degree with eyes.
Figure 22 is the analysis result that the oil film in 2 arc bearings, 3 arc bearings and 4 arc bearings of the existing radial bearing of expression does not have the dimension rigidity.This is to represent hydrodynamic pressure in the bearing play with this second order differential equation formula of Reynolds differential equation, and by computer it is numerically solved the resulting result of evaluation.In pressure is the scope of decompression, use the Reynolds condition as the pressure limit condition.In this said Reynolds condition, be in oil film breakage portion, pressure gradient satisfies the flow condition for continuous when being zero.
At this, 2 arc bearings, 3 arc bearings and 4 arc bearings are on circumferencial direction separately, with 10 ° be width, 2,3,4 the uniformly-spaced bearings of circle groove 10 are set respectively.In addition, any one bearing all can be set at 0.5 with the ratio (L/D) of the axial length L of bearing part 3 and external diameter.In addition, the eccentricity epsilon of spindle unit 4, with ε=0.1 as standard.(eccentricity of 2 arc bearings is 0.0868).In addition, ε=0 expression bearing part 3 state consistent as shown in phantom in Figure 25 with the axle center of bearing part 4; ε=1 is connected on the state (amplifying property of the width ground of the radial bearing among Figure 25 is described) of bearing part 3 in the spindle unit 4 of expression shown in the two point dotted line of this figure.
Kxx among the figure, Kyy, Kxy, Kyx are the parameters of the flexible constant of expression oil film; The pressure portion cloth integration that will numerically solve respectively with bearing surface will be by obtaining by numerical differentiation in the load that x, y direction are obtained respectively on x direction, y direction.Represent these numerical value with no dimension,, then have dimension rigidity Kij to be expressed from the next if represent 4 no dimension rigidity with Kij:
Kij＝(W/Cp)Kij
In the formula, W represents bearing load, and Cp represents the bearing radius clearance.
Footnote xx is illustrated in the displacement at directions X that directions X (oval short-axis direction) produces power; Yy represents it is to be illustrated in the displacement in the Y direction that Y direction (oval short-axis direction) produces power; Xy is the displacement of expression directions X (oval short-axis direction) generation power in the Y direction; Yx is illustrated in the displacement that Y direction (oval short-axis direction) produces the directions X of power.Mark footnote xy, yx are that expression is subjected to not being own but is subjected to the continuous items of the power that the displacement from other motion produces.When continuous items are big, increased the unstability of the whirling motion of spindle unit 4.Be appreciated that in 2 arc bearings by Figure 22, Kxx and Kyy imbalance, the difference of the bearing rigidity that produces for load direction is big; In 3 arc bearings and 4 arc bearings, in order to make the balance that reaches of two values, and there is not this unmatched phenomenon.Found out that by above-mentioned the section configuration of the bearing part 3 after rebounding should be similar to 3 arc bearings and 4 arc bearings, the fixed amount of circle groove 10 is to be desirable more than 3.
On the other hand, during the management of the gap in the radial bearing gap when considering to produce in batches, in 4 arc bearings,, form big error (with reference to the arrow of Figure 24) for internal diameter size according to direction of measurement; And in 3 arc bearings, this error little (with reference to the arrow of Figure 23).Therefore, compare with 4 arc bearings, 3 arc bearings can reduce the scope of internal diameter size tolerance, can more low-cost manufacturing.In addition, if according to Figure 22, the absolute value of continuous items Kxy, Kyx then is because 3 arc bearings are little, so even also be that 3 arc bearings are better in this.On the other hand, in the bearing more than 5 arc bearings, approach round bearing, therefore be known as the possibility of the instability self-excitation motion of rotation, also increased the groove cost of processing in spindle unit 4 existing generations in order to make the section configuration of rebounding after being out of shape.Because above reason will be 3 arc bearings with the shape approximation after the distortion of rebounding, then 3 of circle groove formation are optimal.
Figure 26 is in two radial bearing surface 12a, 12b, is axially forming asymmetricly to other bearing surface 12a the bearing surface 12b of the bottom side of axle sleeve 2, adopts dynamic pressure groove 3a1,3a2 to strengthen the structure of oil to axle sleeve bottom side inhalation power.At this moment, because the formation scope of oil film departs from the axle sleeve bottom side,, in existing two circle grooves (25 :), exist the possibility of the flowing velocity that can not fully absorb oil with reference to Fig. 8 so increased the oil mass that in circle groove 10, flows into.But as described in appealing, by circle groove 10 being arranged to just can avoid this predicament more than 3.The quantity of circle groove can be by the mobile decision of oil, and as described above when considering running accuracy, it is optimal forming 3 circle grooves 10.
As according to the present invention,,, also can further improve the running accuracy of bearing so can prevent that the distortion of rebounding because of bearing part makes the bearing rigidity instability after shaping owing at the circle groove that forms on the excircle of bearing part more than 3.
Claims (4)
1, a kind of hydrodynamic bearing device, it contains:
Axle sleeve: at one end side has opening portion, other distolateral have the bottom;
Spindle unit and bearing part: be configured in the above-mentioned axle sleeve;
Radial bearing portion: be set between the inner circumference of above-mentioned bearing part and between the outer peripheral surface of above-mentioned spindle unit, be used in the oil film of the lubricant oil that the radial bearing gap produces, contactless above-mentioned spindle unit is supported radially adopting;
Sealed member: be configured in the opening portion of above-mentioned axle sleeve, and form seal space between the above-mentioned spindle unit;
Structure in, it is characterized in that:
Above-mentioned seal space is cylindric or coniform, other of above-mentioned axle sleeve is distolateral to be airtight in above-mentioned bottom, even expansion because of the residual air in the inner space of the above-mentioned axle sleeve the reduced pressure atmosphere that is pressed onto 100Torr from atmosphere, but lubricant oil does not leak into the outside yet, fill up the inner space of above-mentioned axle sleeve with lubricant oil, making in the above-mentioned seal space has pasta.
2, hydrodynamic bearing device as claimed in claim 1 is characterized in that: contain: the dynamic pressure generating mechanism: above-mentioned radial bearing portion occurs in the lubricant oil in the above-mentioned radial bearing gap dynamic pressure.
3, hydrodynamic bearing device as claimed in claim 1 is characterized in that: have between the outer peripheral surface of the inner peripheral surface of the above-mentioned sealed member above-mentioned spindle unit relative with it, to a distolateral conical seal space that enlarges gradually.
4, a kind of motor, it is characterized in that: it contains: accessory rights requires the hydrodynamic bearing device of any record in 1～3.
Applications Claiming Priority (9)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001347725 | 2001-11-13 | ||
| JP200134772 | 2001-11-13 | ||
| JP2001347725 | 2001-11-13 | ||
| JP200229520 | 2002-02-06 | ||
| JP2002029520A JP2003232353A (en) | 2002-02-06 | 2002-02-06 | Dynamic pressure type bearing device |
| JP2002035790 | 2002-02-13 | ||
| JP200235790 | 2002-02-13 | ||
| JP2002281599 | 2002-09-26 | ||
| JP200228159 | 2002-09-26 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN200810084707XA Division CN101469742B (en) | 2001-11-13 | 2002-11-11 | Fluid bearing |
| CN2008100847101A Division CN101255892B (en) | 2001-11-13 | 2002-11-11 | Fluid bearing device |
| CNB2005101243139A Division CN100427779C (en) | 2001-11-13 | 2002-11-11 | Fluid bearing device |
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| CN1419057A CN1419057A (en) | 2003-05-21 |
| CN1321274C true CN1321274C (en) | 2007-06-13 |
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| CNB021493006A Expired - Lifetime CN1321274C (en) | 2001-11-13 | 2002-11-11 | Fluid bearing |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2005042838A (en) * | 2003-07-23 | 2005-02-17 | Ntn Corp | Fluid bearing device |
| JP2005090653A (en) * | 2003-09-18 | 2005-04-07 | Ntn Corp | Fluid bearing device |
| CN100395459C (en) * | 2003-09-23 | 2008-06-18 | 财团法人工业技术研究院 | Liquid bearing module |
| JP2005155690A (en) * | 2003-11-21 | 2005-06-16 | Matsushita Electric Ind Co Ltd | Fluid bearing device |
| JP4874004B2 (en) * | 2006-06-07 | 2012-02-08 | Ｎｔｎ株式会社 | Hydrodynamic bearing device |
| KR20100094679A (en) * | 2009-02-19 | 2010-08-27 | 엘지전자 주식회사 | Idle pulley and dryer having the same |
| KR101101643B1 (en) * | 2010-04-15 | 2012-01-02 | 삼성전기주식회사 | Hydrodynamic bearing assembly, motor provided with hydrodynamic bearing assembly and recording disc driving device equipped with motor |
| CN102223007A (en) * | 2011-06-24 | 2011-10-19 | 罗立峰 | High-speed permanent magnet motor/generator |
| CN104149383A (en) * | 2014-07-17 | 2014-11-19 | 安徽和翔机械科技有限公司 | Discharging control mechanism for energy-saving stamping machine |
| WO2019112057A1 (en) * | 2017-12-08 | 2019-06-13 | Ntn株式会社 | Fluid dynamic bearing device |
| CN110985528B (en) * | 2019-12-30 | 2021-08-20 | 江苏毅合捷汽车科技股份有限公司 | Air journal bearing |
| CN114215843A (en) * | 2021-11-25 | 2022-03-22 | 邯郸钢铁集团有限责任公司 | Method for reducing TRT thrust bearing temperature |
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| US5403098A (en) * | 1992-09-18 | 1995-04-04 | Koyo Seiko Co., Ltd. | Hydrodynamic bearing device |
| US5516212A (en) * | 1995-09-18 | 1996-05-14 | Western Digital Corporation | Hydrodynamic bearing with controlled lubricant pressure distribution |
| JPH1073126A (en) * | 1996-08-29 | 1998-03-17 | Sankyo Seiki Mfg Co Ltd | Hydrodynamic bearing device |
| JPH1130229A (en) * | 1997-07-14 | 1999-02-02 | Sankyo Seiki Mfg Co Ltd | Dynamic pressure bearing device |
| JPH11201142A (en) * | 1998-01-12 | 1999-07-27 | Nippon Seiko Kk | Dynamic pressure bearing |
| JP2001271828A (en) * | 2000-03-28 | 2001-10-05 | Ntn Corp | Dynamic pressure type oil-impregnated sintered bearing unit |
| JP2002139041A (en) * | 2000-11-02 | 2002-05-17 | Tohoku Ricoh Co Ltd | Dynamic pressure bearing unit |
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- 2002-11-11 CN CNB021493006A patent/CN1321274C/en not_active Expired - Lifetime
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5403098A (en) * | 1992-09-18 | 1995-04-04 | Koyo Seiko Co., Ltd. | Hydrodynamic bearing device |
| US5516212A (en) * | 1995-09-18 | 1996-05-14 | Western Digital Corporation | Hydrodynamic bearing with controlled lubricant pressure distribution |
| JPH1073126A (en) * | 1996-08-29 | 1998-03-17 | Sankyo Seiki Mfg Co Ltd | Hydrodynamic bearing device |
| JPH1130229A (en) * | 1997-07-14 | 1999-02-02 | Sankyo Seiki Mfg Co Ltd | Dynamic pressure bearing device |
| JPH11201142A (en) * | 1998-01-12 | 1999-07-27 | Nippon Seiko Kk | Dynamic pressure bearing |
| JP2001271828A (en) * | 2000-03-28 | 2001-10-05 | Ntn Corp | Dynamic pressure type oil-impregnated sintered bearing unit |
| JP2002139041A (en) * | 2000-11-02 | 2002-05-17 | Tohoku Ricoh Co Ltd | Dynamic pressure bearing unit |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1419057A (en) | 2003-05-21 |
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