CN101216066B - Hydrodynamic bearing device and spindle motor using the same - Google Patents
Hydrodynamic bearing device and spindle motor using the same Download PDFInfo
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- CN101216066B CN101216066B CN2008100033279A CN200810003327A CN101216066B CN 101216066 B CN101216066 B CN 101216066B CN 2008100033279 A CN2008100033279 A CN 2008100033279A CN 200810003327 A CN200810003327 A CN 200810003327A CN 101216066 B CN101216066 B CN 101216066B
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- Lubricants (AREA)
- Sliding-Contact Bearings (AREA)
- Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
Abstract
A hydrodynamic bearing device being low in torque, low in power consumption, high in reliability and best suited for miniaturization and a spindle motor using the same. The hydrodynamic bearing device in accordance with the present invention, dynamic pressure generation grooves being provided on at least one of a shaft or a sleeve, and a lubricant being present in a clearance where the above-mentioned shaft and the above-mentioned sleeve are opposed to each other, is characterized in that the above-mentioned lubricant contains diesters obtained from a divalent alcohol having 4 to 8 carbon atoms and having no alkyl side chain at the beta position and one or more kinds of saturated monovalent fatty acids having 9 to 13 carbon atoms.
Description
The application is to be March 31, application number in 2005 the dividing an application for the Chinese patent application of " Hydrodynamic bearing device and used the Spindle Motor of this device " that be 200510056240.4 title the applying date.
Technical field
The present invention relates to the fluid-dynamic bearing device and used the Spindle Motor of this device.
Background technology
Fluid bearing is made up of the sleeve of axle and bolster, has lubricant in both opposed gaps.By the dynamic pressure generation trough that forms in axle or sleeve, along with the rotation of axle, lubricant concentrates in together, and produces pressure, and axle is supported with contactless state by sleeve.Can realize high speed rotating by this, the noise in the time of can also weakening rotation.
Loaded the Spindle Motor of this Hydrodynamic bearing device, improve institute indispensable good running accuracy, shock-resistance and silence because have media recording density, thus just becoming with the disk set be the information of representative be provided with and the main flow of sound equipment video equipment usefulness motor.Therefore, in recent years from miniaturization, the energy-conservationization viewpoint of machine, the urgent current sinking of wishing to reduce Spindle Motor especially wishes to reduce the current sinking of motor is influenced the torque of bigger Hydrodynamic bearing device.
Because the torque of Hydrodynamic bearing device is directly proportional with the viscosity of the lubricant of institute filling, so the lower lubricant of use viscosity is effective to reducing torque.
Proposed to have used the Hydrodynamic bearing device of dioctyl sebacate (DOS), dioctyl azelate (DOZ), Octyl adipate (DOA) etc. as lubricant in the past; Used the Hydrodynamic bearing device (the Japanese Patent spy opens the 2000-336383 communique) of mixed ester of the sad and n-capric acid of neopentyl glycol; Used the Hydrodynamic bearing device (the Japanese Patent spy opens the 2001-316687 communique) of the unary fatty acid of neopentyl glycol and carbonatoms 6～12 and/or the ester that its derivative makes; Used by β position or β, the diol component that has alkyl group side chain on the β ' position is derived and the Hydrodynamic bearing device (the Japanese Patent spy opens the 2002-195252 communique) of the polyol ester that comes etc.
But, though these its torques of Hydrodynamic bearing device of example in the past may reduce because the thermotolerance of lubricant is low, so have that steam output increases, device shortens work-ing life, device reliability can not fully guarantee a problem.In addition, consider the steam output of this lubricant, filling under the situation of the above excessive lubricant of necessary amounts, exist corresponding torque increase, cost improves and be difficult to realize that miniaturization is to guarantee the spatial problem.
In view of above-mentioned problem, the object of the present invention is to provide the Spindle Motor that torque is little, current consumption is low, reliability is high and be suitable for the Hydrodynamic bearing device of miniaturization most and used this device, as the lubricant of this device, contain carbonatoms 4～8, do not have the diester that the saturated unary fatty acid of the dibasic alcohol of alkyl group side chain and the carbonatoms more than a kind 9～13 forms in the β position.
Summary of the invention
In order to address the above problem, the present invention has following formation.
The present invention 1 Hydrodynamic bearing device is that axle and at least one side of telescopic have the dynamic pressure generation trough, have the Hydrodynamic bearing device of lubricant in above-mentioned spool and the opposed gap of above-mentioned sleeve, above-mentioned lubricant contains carbonatoms 4～8, do not have the diester that the saturated unary fatty acid of the dibasic alcohol of alkyl group side chain and the carbonatoms more than a kind 9～13 forms in the β position, and above-mentioned gap is the radially radius clearance of 1～5 μ m.
The lubricant of Hydrodynamic bearing device contains carbonatoms 4～8, do not have the diester that the saturated unary fatty acid of the dibasic alcohol of alkyl group side chain and the carbonatoms more than a kind 9～13 forms in the β position.Therefore, compare with lubricant in the past, its viscosity is low, so can constitute the Hydrodynamic bearing device of low torque.In addition, because the thermotolerance height of lubricant can reduce steam output,, can reduce cost and the miniaturization of implement device so the fill-up of the lubricant of each table apparatus reduces.Above-mentioned formation of the present invention can realize that torque is low, current consumption is few, reliability is high and be suitable for the Hydrodynamic bearing device of miniaturization.
Utilize formation of the present invention, because can give full play to properties of lubricants, so can obtain radially radius clearance the best, low torque and high inflexible Hydrodynamic bearing device.
The present invention 2 Hydrodynamic bearing device further limits the present invention 1 Hydrodynamic bearing device, and the saturated unary fatty acid of above-mentioned carbonatoms 9～13 more than a kind is the saturated unary fatty acid of the carbonatoms 9～13 more than 2 kinds.
By use mixing diester that the carbonatoms saturated fatty acid different with molecular structure make as lubricant, compare when using single lubricant, more can improve low-temperature fluidity and evaporation characteristic etc.Utilize formation of the present invention, when the reliability of device improves, can also enlarge spendable temperature range.
The present invention 3 Hydrodynamic bearing device further limits the present invention 2 Hydrodynamic bearing device, and at least a kind of the saturated unary fatty acid of above-mentioned carbonatoms 9～13 more than 2 kinds is the saturated unary fatty acid of straight chain type.
Contain the lubricant of the saturated unary fatty acid of straight chain type by use, compare, have high heat resistance, and can suppress the variation of viscosity with temperature with the situation that only contains branched chain type.Utilize formation of the present invention, can improve the reliability of Hydrodynamic bearing device, can also suppress torque with variation of temperature.
The present invention 4 Hydrodynamic bearing device further limits the present invention 3 Hydrodynamic bearing device, and the saturated unary fatty acid of above-mentioned carbonatoms 9～13 more than 2 kinds is the identical saturated unary fatty acid of carbonatoms.
The saturated unary fatty acid that carbonatoms is different is because wherein characteristic such as any thermotolerance and density is all made a world of difference, so the unstable properties of device.Utilize formation of the present invention,,, obtain the high Hydrodynamic bearing device of reliability so can make the stable performance of device because the carbonatoms of the saturated unary fatty acid more than 2 kinds is identical.
The present invention 5 Hydrodynamic bearing device further limits the present invention 1 Hydrodynamic bearing device, above-mentioned carbonatoms 4～8, the dibasic alcohol that does not have alkyl group side chain in the β position are the 3-methyl isophthalic acids, the 5-pentanediol, the saturated unary fatty acid of above-mentioned carbonatoms 9～13 is saturated unary fatty acids of carbonatoms 9 or 10.
Utilize formation of the present invention, the thermotolerance and the low-temperature fluidity of lubricant are more excellent.Therefore, even can obtain the high performance Hydrodynamic bearing device of device reliability raising in low temperature range also rotatable startup.
Utilize formation of the present invention,, therefore be suitable for most low torque, current consumption is few, reliability is high Hydrodynamic bearing device because carbonatoms 9 or 10 unary fatty acid are particularly useful for the performance balance of lubricant.
The present invention 6 Hydrodynamic bearing device further limits the present invention 1 Hydrodynamic bearing device, and the big inorganic system impurity of the minimum size in the above-mentioned gap of ratio that the above-mentioned lubricant in every Hydrodynamic bearing device is contained is below 1000.
Utilize formation of the present invention,,, can not cause the rapid torque increase and the vibrations of bearing so the torque variation is little because the impurity of sneaking in the lubricant is few.Therefore can obtain high-performance and the high Hydrodynamic bearing device of reliability.
The 1st Spindle Motor of the present invention possesses the present invention 1 Hydrodynamic bearing device.
Utilize formation of the present invention, the current sinking that can obtain motor is low, high-performance and the high Spindle Motor of reliability.
The present invention 7 Hydrodynamic bearing device is that axle and at least one side of telescopic have the dynamic pressure generation trough, have the Hydrodynamic bearing device of lubricant in above-mentioned spool and the opposed gap of above-mentioned sleeve, above-mentioned lubricant contains carbonatoms 4～8, do not have the ester that the saturated unary fatty acid of the monounsaturated dicarboxylic acid of the dibasic alcohol of alkyl group side chain and the carbonatoms more than a kind 6～10 and the carbonatoms more than a kind 5～13 forms in the β position, and above-mentioned gap is the radially radius clearance of 1～5 μ m.
The lubricant of Hydrodynamic bearing device contains carbonatoms 4～8, do not have the ester that the saturated unary fatty acid of the monounsaturated dicarboxylic acid of the dibasic alcohol of alkyl group side chain and the carbonatoms more than a kind 6～10 and the carbonatoms more than a kind 5～13 forms in the β position.Therefore, compare with lubricant in the past, its viscosity is low, can obtain the Hydrodynamic bearing device of low torque.In addition, because the thermotolerance height of lubricant can reduce steam output,, can reduce cost and the miniaturization of implement device so the fill-up of the lubricant of each table apparatus reduces.Utilize formation of the present invention, can obtain low torque, current consumption is low, reliability is high and is suitable for the Hydrodynamic bearing device of miniaturization.
Utilize formation of the present invention, because can give full play to properties of lubricants, so can obtain radially radius clearance the best, low torque and high inflexible Hydrodynamic bearing device.
The present invention 8 Hydrodynamic bearing device further limits the Hydrodynamic bearing device of the invention described above 7, and the saturated unary fatty acid of above-mentioned carbonatoms 5～13 more than a kind is the saturated unary fatty acid of the carbonatoms 5～13 more than 2 kinds.
Utilizing formation of the present invention,, comparing, more can improve low-temperature fluidity and evaporation characteristic etc. with using the single lubricant of composition by use mixing ester that the carbonatoms saturated fatty acid different with molecular structure make as lubricant.Utilize formation of the present invention, when the reliability of device improves, can also enlarge spendable temperature range.
The present invention 9 Hydrodynamic bearing device further limits the Hydrodynamic bearing device of the invention described above 8, and at least a kind of the saturated unary fatty acid of above-mentioned carbonatoms 5～13 more than 2 kinds is the saturated unary fatty acid of straight chain type.
Contain the lubricant of the saturated unary fatty acid of straight chain type by use, and compare under the situation that only has branched chain type, have more high heat resistance, and can suppress the variation of viscosity with temperature.Utilize formation of the present invention, can improve the reliability of Hydrodynamic bearing device, also can suppress torque with variation of temperature.
The present invention 10 Hydrodynamic bearing device further limits the Hydrodynamic bearing device of the invention described above 9, and the saturated unary fatty acid of above-mentioned carbonatoms 5～13 more than 2 kinds is the identical saturated unary fatty acid of carbonatoms.
The saturated unary fatty acid that carbonatoms is different is because wherein characteristic such as any thermotolerance and density is all made a world of difference, so the unstable properties of device.Utilize formation of the present invention,,, can obtain the high Hydrodynamic bearing device of reliability so can make the stable performance of device because the carbonatoms of the saturated unary fatty acid more than 2 kinds is identical.
The present invention 11 Hydrodynamic bearing device further limits the Hydrodynamic bearing device of the invention described above 7, above-mentioned carbonatoms 4～8, the dibasic alcohol that does not have alkyl group side chain in the β position are the 3-methyl isophthalic acids, the 5-pentanediol, the saturated unary fatty acid of above-mentioned carbonatoms 5～13 is saturated unary fatty acids of carbonatoms 7～10.
Utilize formation of the present invention, the thermotolerance and the low-temperature fluidity of lubricant are very good.Therefore, the reliability height of device is even can obtain also can rotate in low temperature range the high performance Hydrodynamic bearing device of startup.
Utilize formation of the present invention,, therefore be suitable for most low torque, current consumption is few, reliability is high Hydrodynamic bearing device because the saturated unary fatty acid of carbonatoms 7～10 is particularly useful for the performance balance of lubricant.
The present invention 12 Hydrodynamic bearing device further limits the Hydrodynamic bearing device of the invention described above 7, and the big inorganic system impurity of the minimum size in the above-mentioned gap of ratio that the above-mentioned lubricant in every Hydrodynamic bearing device is contained is below 1000.
Utilize formation of the present invention,,, can not cause the rapid torque increase and the vibrations of bearing so the torque variation is little because the impurity of sneaking in the lubricant is few.Can obtain the Hydrodynamic bearing device of high-performance and high reliability by this.
In addition, the 2nd Spindle Motor of the present invention possesses the Hydrodynamic bearing device of the invention described above 7.
Utilize formation of the present invention, the current sinking that can obtain motor is low, the Spindle Motor of high-performance and high reliability.
Hydrodynamic bearing device of the present invention and the Spindle Motor that has used this device, by using the lubricant of low viscosity, excellent heat resistance, the Spindle Motor that can obtain low torque, current consumption is little, reliability is high, is suitable for the Hydrodynamic bearing device of miniaturization and has used this device.
The new feature of invention is the content of special record in claims, and the present invention describes understood in detail to relevant formation and content with other purpose and feature with reference to accompanying drawing, and hope can have better understanding to the present invention.
Description of drawings
Fig. 1 is a sectional view of the Spindle Motor of rotary fluid bearing assembly that has of embodiments of the present invention 3.
Fig. 2 is the sectional view of the shaft fixed Hydrodynamic bearing device of embodiments of the present invention 1.
Fig. 3 is the form of measurement result of each data of expression embodiment 1～10 and comparative example 1 and 2.
Part or all of accompanying drawing is the simple expression of doing for diagram, and the relative size and the position of the reality of key element shown in might not verily representing are so please refer to.
Embodiment
Below with regard to Hydrodynamic bearing device of the present invention and used the better embodiment 1～3 of the Spindle Motor of this device to describe.
" embodiment 1 "
Use Fig. 2 that embodiments of the present invention 1 are described.
Fig. 2 represents the section overview of shaft fixed Hydrodynamic bearing device.In Fig. 2, show pedestal 1a, axle 2, radial dynamic pressure generation trough 2a and 2b, thrust flange 3, thrust dynamic pressure generation trough 3a, sleeve 4, lubricant 8, thrust plate 9, radius clearance 10 radially.
The fixing thrust flange 3 of axle one end of lambdoid radial dynamic pressure generation trough 2a, 2b, formation axial region have been formed at periphery.The other end of axle 2 is pressed into and is fixed in the pedestal 1a.Axial region is inserted in the dead eye of sleeve 4, thrust plate 9 has been installed to stop up another dead eye in sleeve 4 and thrust flange 3 subtends.In addition, form spiral helicine thrust dynamic pressure generation trough 3a on surface with thrust plate 9 opposed thrust flange 3.Filling lubricant 8 between the gap of these dead eyes and axial region.Be accompanied by rotation, lubricant 8 is collected in together by the radial dynamic pressure generation trough 2a, the 2b that form at axle 2, produces pressure at the radially radius clearance 10 of axle 2 and sleeve 4, and therefore, sleeve 4 is radially with contactless state bolster 2.In addition, collect lubricant 8 and produce pressure by thrust dynamic pressure generation trough 3a in thrust direction, thus thrust plate 9 come-ups, with contactless state supporting thrust flange 3.
As lubricant 8, use carbonatoms 4～8, do not have the diester that the saturated unary fatty acid of the dibasic alcohol of alkyl group side chain and carbonatoms 9～13 forms in the β position.Consequently, compared than in the past, torque is little, can turn round over a long time.This diester can be in the presence of the catalyzer or under the catalyst-free condition, the pure composition of regulation and sour composition are reacted by known esterifying reaction method and synthesizes.
The alcohol composition is carbonatoms 4～8, do not have the dibasic alcohol of alkyl group side chain in the β position.As this dibasic alcohol, can exemplify straight chain type or in the β position beyond have the branched chain type of side chain, still, from good this reason of low-temperature fluidity, best is the branched chain type that has side chain in the β position in addition.In addition, the branched chain type that from this reason of good heat resistance, best is in the α position, γ position, δ position have an alkyl group side chain.Alkyl group side chain is good with low alkyl groups such as methyl, ethyl, propyl group, and is lower from viscosity, can reduce this reason of bearing torque, is good with methyl.Specifically can exemplify the 1-methyl isophthalic acid, ammediol, 1-methyl isophthalic acid, 4-butyleneglycol, 1-methyl isophthalic acid, 5-pentanediol, 1-methyl isophthalic acid, 6-hexylene glycol, 1-methyl isophthalic acid, 7-heptanediol, 3-methyl isophthalic acid, 5-pentanediol, 3-methyl isophthalic acid, 6-hexylene glycol, 3-methyl isophthalic acid, 7-heptanediol, 4-methyl isophthalic acid, 7-heptanediol etc., but from good heat resistance, improve the reason of bearing reliability, with the 3-methyl isophthalic acid, the 5-pentanediol is good.
As the saturated monovalence lipid acid of the carbonatoms 9～13 of sour composition because do not contain unsaturated link(age), so thermostability and oxidative stability height, even under hot environment He under the high speed rotating, also be difficult to cause deterioration.Therefore, consider, be more preferably unsaturated unary fatty acid from the reason that prolong device lifetime.In the case, the saturated unary fatty acid of carbonatoms 9～13 can only use a kind also can use more than 2 kinds.Use under the situation more than 2 kinds, can exemplify identical straight chain type of carbonatoms and branched chain type, carbonatoms is identical but branched chain type that the side chain position is different, the straight chain type that carbonatoms is different, straight chain type that carbonatoms is different and branched chain type, the combination of the branched chain type that carbonatoms is different etc.Be more preferably the straight chain type that uses good heat resistance more than a kind at least, can improve device reliability.By a kind of pure composition and 2 kinds of diester that sour composition forms, can obtain only combining in a part 2 kinds of the diester of the single structure of a kind of sour composition, and a kind of the diester that combines the mixed structure of 2 kinds of sour compositions in a part, add up to the mixture of 3 kinds of esters.In addition, carbonatoms is that bearing is opposite with the situation of little torque, has the thermotolerance step-down under the situation below 8, and the tendency that steam output increases must increase the fill-up of lubricant, thus to reduce cost and the miniaturization aspect unfavorable.On the other hand, carbonatoms is under the situation more than 14, and it is big that viscosity becomes, and except the effect that the torque that can not obtain bearing reduces, also has the tendency of low-temperature fluidity deterioration, can't start at the low temperature range internal rotation sometimes.Can exemplify pelargonic acid, n-capric acid, n-undecane acid, dodecanoic acid, n-tridecane acid, different n-nonanoic acid, 3,5,5 Trimethylhexanoic acid, isodecyl acid, different undecanoic acid, Permethyl 99A. acid, different tridecanoic acid etc. specifically.In the saturated unary fatty acid of carbonatoms 9～13, be preferably the saturated unary fatty acid of carbonatoms 9～10.The pelargonic acid of the straight chain type of carbonatoms 9～10, n-capric acid are because its thermotolerance and lowering viscousity are good, so effective to the raising and the low torqueization of bearing reliability.In addition, the different n-nonanoic acid of the branched chain type of carbonatoms 9～10,3,5,5 Trimethylhexanoic acid, isodecyl acid are because thermotolerance and low-temperature fluidity are good, so to the raising of bearing reliability with guarantee that the rotation of low temperature range starts effectively.
In addition, lubricant 8 of the present invention can also be at carbonatoms 4～8, not have in the diester that the saturated monovalence lipid acid of the dibasic alcohol of alkyl group side chain and carbonatoms 9～13 forms as adding the lubricant that oil has mixed the oil of other kind in the β position.Adding oil can be according to the reduction and the adjustment of viscosity, and stable on heating raising, auxiliary and improve purpose such as other performance, suitably selects.Specifically, can exemplify compound known such as mineral oil, poly-alpha olefins, alkyl aromatic, polyoxyethylene glycol, phenyl ether, polyol ester, diprotic acid diester, phosphoric acid ester.These add oil and can mix more than a kind or 2 kinds.Wherein, the thermotolerance height of polyol ester and diprotic acid diester, good fluidity at low temperatures is so start effectively reliability that improves bearing assembly and the rotation of guaranteeing low temperature range.As polyol ester, can exemplify the ester class of neopentyl glycol, TriMethylolPropane(TMP), tetramethylolmethane and lipid acid, as the diprotic acid diester, can exemplify dioctyl sebacate (DOS), dioctyl azelate (DOZ), Octyl adipate (DOA), diisononyl adipate, diisodecyl adipate etc.
In addition, can also be in lubricant 8 blast blending.Additive can and improve according to the raising of base oil performance and be purpose, selects known compound.Specifically, can mix depressant prescription, defoamer, conductive agent, detergent-dispersant additive etc. under oxidation inhibitor more than a kind or 2 kinds, rust-preventive agent, metal passivator, oiliness improver, extreme-pressure additive, friction regulator, anti-abrasion agent, viscosity index rising agent, the yield point.Additive makes the degradation of bearing and device, so the fusion total amount should be controlled in the minimum amount limit because of producing gas along with deterioration or causing and go bad.
In order to improve the long-term reliability of Hydrodynamic bearing device, oxidation inhibitor particularly must be obligato.Specifically, in the molecule not the phenol of sulfur-bearing and chlorine system or same amine to be that oxidation inhibitor is used for Hydrodynamic bearing device optimum.The additive that contains sulphur and chlorine in the molecule can produce corrosive gases after decomposition, may produce great effect to device performance.These oxidation inhibitors can use separately also and can and use.Wherein, best be use under the hot environment more than 80～100 ℃, this device also can be brought into play effect of sufficient and keep the higher stable on heating phenol that contains the phenolic group more than 2 is oxidation inhibitor.In addition, preferably select can not make fluidity at low temperature to reduce, can easily make the aqueous oxidation inhibitor of device rotation startup.
In addition, adopt low viscosity, surface protection adsorption film under the situation of thin lubricant of the present invention 8, the startup of Hydrodynamic bearing device and the axle that produces when stopping to contact with telescopic the friction wear followed sometimes than in the past greatly.For this reason, except above-mentioned oxidation inhibitor, preferably also be added on axle and telescopic metallic surface and easily form in protective membrane, the molecule at least a of the metal passivator of not sulfur-bearing and chlorine and oiliness improver as additive.Specifically,, recommend the benzotriazole based compound,, recommend the unary fatty acid of carbonatoms more than 15, for example n-teradecanoic acid, n-hexadecane acid, Octadecane acid etc. as oiliness improver as the metal passivator of sulfur-bearing and chlorine not in the molecule.
In addition, because the axle that produces when the startup of Hydrodynamic bearing device stops to contact friction and the abrasive heating of being followed with sleeve, so, the carboxylic acid that gets with the ester decomposition of lubricant sometimes as the known common metal salt of various additives reacts, form the carboxylate salt throw out, therefore had better not use.
In addition, constitute under the identical situation at bearing, the viscosity of lubricant 8 is high more, and the motor current sinking is big more.Therefore.The viscosity of lubricant 8 is to hang down for good.But, under the low situation of the viscosity of lubricant 8,, must reduce radially radius clearance 10 for the rigidity of retainer shaft, impurity etc. causes that the possibility of the rotation vibrations of bearing increases like this, the reliability of device reduces.Therefore, the viscosity of lubricant 8 is 5～35mPas under 20 ℃, more preferably when 5～30mPas, the good especially 10～25mPas of being, the effect of lubricant of the present invention can use to greatest extent.In addition, the rotating speed of motor generally adopts 4200rpm, 5400rpm, 7200rpm, 10000rpm, 15000rpm etc.
In addition, the axle 2 and the radially radius clearance 10 of sleeve 4 are under the situation of 1～5 μ m, are preferably 1.5～4 μ m, more preferably under the situation of 1.5～3 μ m, and bearing can be given full play to the effect of the lowering viscousity of lubricant 8 of the present invention.Because torque is directly proportional with the inverse in gap, rigidity is directly proportional with the inverse of the n power in gap, so the gap corresponding to lubricant viscosity must be arranged.If in above-mentioned scope, then use under the situation of lubricant of the present invention, obtain the required rigidity of low torque and bearing easily.Lubricant of the present invention is because viscosity is low, thus at high temperature guarantee with the equal axle inflexible situation of in the past lubricant under, must be than dwindled a bit radially radius clearance a little in the past.But, if radially radius clearance is less than 1 μ m, even if then use lubricant 8 of the present invention, because the influence in gap is big, so reduce the poor effect of bearing torque.In addition, owing to sneak into impurity and the influence that starts the abrasion powder that produces when stopping, being very easy to cause the vibrations of bearing, so the reliability decrease of device.In addition, axle and sleeve must have high manufacturing accuracy and assembly precision, and this also becomes the reason that manufacturing cost increases.If radially radius clearance is greater than 5 μ m, then the lowering viscousity effect with the used lubricant 8 of the present invention is opposite, and it is big that the influence in gap becomes, and bearing rigidity descends, and cannot stand actual use.In addition, because it is big that the excentricity of axle becomes, so the vibrations as the plane of rotation of the disk of the recording medium that is installed in Spindle Motor etc. become big, cause the precise decreasing of record regenerating position and the problem that strength of signal produces deviation, can't satisfy the performance requriements of disk set.In addition,,, bearing life is shortened so the oxidative degradation of lubricant quickens because the contact area of lubricant and air increases, therefore improper.
In addition, the diameter of axle 2 is preferably 1～4mm.Under the situation of axle 2 diameters less than 1mm,, just must dwindle the gap greatly, strengthen axial length, the problems referred to above will occur if the gap dwindles in order to ensure the rigidity of bearing.For miniaturization, be very tight to the restriction of the length of axle, so do not satisfy necessary performance.Under the situation of axle 2 diameters greater than 4mm, rigidity increases, but because torque becomes big, so the effect of lubricant 8 can not be brought into play.From considering with 10 combinations of radius clearance radially, be good with diameter 1.5～3.5mm, be more preferably diameter 1.5～3mm, in this case, the effect of lubricant of the present invention can be utilized to greatest extent.
As the material of axle 2, optimum with stainless steel.Stainless steel and other metallographic phase ratio, the corrosion of the caused axles such as acid that produce when synthetic because of the ester of lubricant 8 is little, and the hardness height can suppress to wear away generating capacity, so be preferably low viscosity, lubricant of the present invention 8 that the surface protection adsorption film is thin.Be more preferably martensitic stainless steel.
Lubricant 8 of the present invention will be handled after filtration and refill in the bearing, being that the radially radius clearance 10 big inorganic system impurity numbers of axle 2 and sleeve 4 opposed minimum clearances are controlled at below 1000 with likening to of sneaking in every bearing assembly.This inorganic system impurity is with the micropartical that contains elements such as iron, chromium, copper, aluminium, silicon as the generation source such as mould that uses in the structured material of Spindle Motor and the technology and airborne seston.These inorganics impurity become not only that torque increases and the principal element of change, and be fixed on axle and the sleeve, may cause bearing and shake, so be preferably in the interior minimizing of possible limit.The filtration treatment of lubricant is carried out pressure filtration or filtration under diminished pressure with the filter paper in the following aperture of size of smallest radial radius clearance.The counting of impurity is by filtering the lubricant after the above-mentioned filtration treatment again with the filter paper of aperture below the size of smallest radial radius clearance, adopt optics or electron microscope that the specific diameter on the filter paper method such as is counted to radius clearance 10 big inorganics impurity then and carry out.From for the amount of the lubricant of filtration treatment and specific diameter to the big inorganics impurity number of radius clearance 10, be converted into number corresponding to the fill-up of the lubricant of each bearing assembly.Though also have organic systems such as fiber in the impurity, because organic system impurity is soft, so cause the possibility of bearing generation vibrations littler than inorganic system impurity.
In addition, sleeve 4 preferably uses copper alloy, iron alloy, stainless steel, pottery, resin etc. to be difficult to by the material of acid corrosion.Furthermore, from wear resistant, processibility, cost aspect, use copper alloy, iron alloy, stainless steel better.In addition, from the cost face, can be agglomerated material also, lubricant is contained when being dipped in agglomerated material can obtain identical effect.In addition, can be to a part of surface or the whole surface of bush material, carried out surface modification by electrochemical plating, physical vapor deposition, chemical vapor deposition method, diffusion by embrane method etc.
The radial dynamic pressure generation trough is formed at the periphery of axle, but telescopic dead eye face form also can, perhaps all form in periphery and two places of telescopic dead eye face of axle.In addition, the thrust dynamic pressure generation trough can only be formed at the surface with the opposed thrust flange of thrust plate, perhaps only is formed at the surface with the opposed thrust plate side of thrust flange, perhaps only form at the inner face of thrust flange, or two places in above-mentioned three places is above forms.
In addition, radially reaching the thrust dynamic pressure generation trough adopts any shape in chevron shaped, the spiral type can both obtain same effect.
In addition, embodiments of the present invention are that axial region is single-ended fixing, under the fixed situation of two ends, also can obtain same effect during with telescopic dead eye both ends open.
" embodiment 2 "
Embodiments of the present invention 2 describe with Fig. 2 again.In the present embodiment, except the different this point of the composition of lubricant 8, all the other and embodiment 1 are same.
The alcohol composition is carbonatoms 4～8, do not have the dibasic alcohol of alkyl group side chain in the β position.As this dibasic alcohol, can exemplify straight chain type or in the β position beyond have the branched chain type of side chain, but consider preferably have the branched chain type of side chain beyond the β position from excellent this reason of low-temperature fluidity.In addition, consider preferably on α position, γ position, δ position, have the branched chain type of an alkyl group side chain from the reason of excellent heat resistance.As alkyl group side chain, be good with low alkyl groups such as methyl, ethyl, propyl group, lower from viscosity, can reduce this reason of bearing torque, better with methyl.Specifically, can exemplify the 1-methyl isophthalic acid, ammediol, 1-methyl isophthalic acid, 4-butyleneglycol, 1-methyl isophthalic acid, 5-pentanediol, 1-methyl isophthalic acid, 6-hexylene glycol, 1-methyl isophthalic acid, 7-heptanediol, 3-methyl isophthalic acid, 5-pentanediol, 3-methyl isophthalic acid, 6-hexylene glycol, 3-methyl isophthalic acid, 7-heptanediol, 4-methyl isophthalic acid, 7-heptanediol etc.But from the reason of good heat resistance, raising bearing reliability, with the 3-methyl isophthalic acid, the 5-pentanediol is good.
The acid composition is the monounsaturated dicarboxylic acid of carbonatoms 6～10 and the saturated unary fatty acid of carbonatoms 5～13.
As the monounsaturated dicarboxylic acid of carbonatoms 6～10, can exemplify hexanodioic acid, pimelic acid, suberic acid, nonane diacid, sebacic acid etc.Wherein, from the cost face, be good with hexanodioic acid, nonane diacid, sebacic acid, especially good is hexanodioic acid, its molecular weight is lower, and is effective to reducing the bearing torque.If carbonatoms is below 5, then with the bearing torque reduce opposite because thermotolerance is low, steam output increases, thus the fill-up of lubricant must increase, to reduce cost and miniaturization all unfavorable.Carbonatoms is under the situation more than 11, and it is big that viscosity becomes, and can't expect the effect that the bearing torque reduces.
The saturated unary fatty acid of carbonatoms 5～13 can only also can be with more than 2 kinds with a kind.Use under the situation more than 2 kinds, can exemplify identical straight chain type of carbonatoms and branched chain type, carbonatoms is identical but branched chain type that the side chain position is different, the straight chain type that carbonatoms is different, straight chain type that carbonatoms is different and branched chain type, the combination of the branched chain type that carbonatoms is different etc.Preferably use the good heat resistance more than at least a kind, the straight chain type that device reliability can improve.Carbonatoms is under the situation below 4, reduces on the contrary with the bearing torque, and the tendency that exists thermotolerance step-down, steam output to increase must increase the fill-up of lubricant, thus to reduce cost and the miniaturization aspect unfavorable.On the other hand, if carbonatoms more than 14, then viscosity becomes big, can't expect the effect that the bearing torque reduces, and the tendency of low-temperature fluidity deterioration is arranged, and appears at the situation that low temperature range can not be rotated startup sometimes.In the saturated unary fatty acid of carbonatoms 5～13, best is the saturated unary fatty acid of carbonatoms 7～10.The straight chain type of carbonatoms 7～10 is because thermotolerance and lowering viscousity excellence, so in the reliability that improves bearing with reduce aspect the torque effective.The branched chain type of carbonatoms 7～10, because thermotolerance and low-temperature fluidity excellence, so start effectively in reliability that improves bearing and the rotation of guaranteeing low temperature range.Object lesson can exemplify positive enanthic acid, n-caprylic acid, pelargonic acid, n-capric acid, isoamyl acetic acid, isocaprylic acid, 2 ethyl hexanoic acid, different n-nonanoic acid, 3,5,5 Trimethylhexanoic acid, isodecyl acid etc.
Though it is unqualified to usage ratio as the saturated unary fatty acid of the monounsaturated dicarboxylic acid of the carbonatoms 6～10 of sour composition and carbonatoms 5～13, but preferably allow the ratio of saturated unary fatty acid of carbonatoms 5～13 big, thermotolerance is higher like this, and can improve the reliability of bearing.It all is 100 o'clock mol ratio that ratio in the case is set at sour composition.For example, under the monounsaturated dicarboxylic acid of the carbonatoms 6～10 that uses as the sour composition situation identical with the mole number of the saturated unary fatty acid of carbonatoms 5～13, mol ratio is set at 50: 50.Wherein, the monounsaturated dicarboxylic acid of carbonatoms 6～10 is good below 20 with mol ratio, and mol ratio is better below 10.
In addition, lubricant 8 of the present invention can also be at carbonatoms 4～8, do not have the oil that mixes other kind in the ester that the saturated unary fatty acid of the monounsaturated dicarboxylic acid of the dibasic alcohol of alkyl group side chain and carbonatoms 6～10 and carbonatoms 5～13 forms in the β position and make as adding oil.Add reduction that oil can viscosity and adjustment and stable on heating raising, auxiliary and improve other performance etc. and be purpose, suitably select.Specifically, can exemplify compound known such as mineral oil, poly-alpha olefins, alkyl aromatic, polyoxyethylene glycol, phenyl ether, polyol ester, diprotic acid diester, phosphoric acid ester.These add oil and can mix more than a kind or 2 kinds.Wherein, the thermotolerance height of polyol ester and diprotic acid diester, fluidity at low temperature is good, so start all effective to reliability that improves bearing assembly and the rotation of guaranteeing low temperature range.As polyol ester, can exemplify the ester of neopentyl glycol, TriMethylolPropane(TMP), tetramethylolmethane and lipid acid, as the diprotic acid diester, can exemplify dioctyl sebacate (DOS), dioctyl azelate (DOZ), Octyl adipate (DOA), diisononyl adipate, diisodecyl adipate etc.
" embodiment 3 "
With Fig. 1 embodiments of the present invention 3 are described.
Fig. 1 is the sectional view that has the Spindle Motor of the revolving Hydrodynamic bearing device of axle in the embodiment 3.In the present embodiment, following each point promptly changes Hydrodynamic bearing device into a spool rotation mode this point from the axle fixed form, replaces pedestal 1a this point with pedestal 1, and have lining 5, rotor magnet 6 and stator coil 7 this point, different with the Hydrodynamic bearing device of Fig. 2.All identical in addition with embodiment 1, give identical symbol to the parts that become identical or impartial formation, and omit detailed explanation it.
An axle end of 2 that has formed lambdoid radial dynamic pressure generation trough 2a, 2b at periphery is thrust flange 3 fixedly, is pressed into the lining 5 that usefulness such as disk are installed at the other end, the formation rotating part.On the other hand, the sleeve 4 of accepting rotating part is pressed in the pedestal 1, the one end has been installed thrust plate 9, forms fixed part.Inserting axial region at the dead eye of sleeve 4 makes thrust plate 9 and thrust flange 3 opposed.Form lambdoid thrust dynamic pressure generation trough 3a on surface with thrust plate 9 opposed thrust flange 3.At the clearance filled lubricant 8 of these dead eyes and axial region, form bearing assembly.In addition, stator coil 7 is set,, constitutes motor driving part at the inner peripheral surface and the stator coil 7 opposed installation rotor magnets 6 of lining 5 in the wall portion that is formed at pedestal 1.
In case drive rotating part by this motor driving part rotation, then same with embodiment 1, in radial direction and thrust direction lubricant 8 is produced dynamic pressure, rotating part and fixed part are rotated supporting with contactless state.
In addition, in Spindle Motor, the disk with aluminum more than 1 or glass is contained on the lining 5 usually.Wherein, the present invention is effective to the Spindle Motor that carries the minidisk below 2.5 inches.
Below, further specify the lubricant of Spindle Motor of the present invention and Hydrodynamic bearing device of the present invention by embodiment 1～10, comparative example 1 and comparative example 2.
In embodiment 1～10, comparative example 1 and comparative example 2, all mixed the phenol system compound that contains 2 phenolic group 4,4 '-methylene-bis-2,6 di t butyl phenol 0.5 weight % as oxidation inhibitor.In addition, the proportional quantity of additive shown in the present, promptly weight % is the ratio with respect to the gross weight of the lubricant that comprises base oil and additive.
In addition, no matter which kind of lubricant all carried out filtration under diminished pressure with the following filter paper of aperture 2.5 μ m in advance and handled to remove impurity.
(embodiment 1)
With the 3-methyl isophthalic acid, the diester that 5-pentanediol and pelargonic acid form is as lubricant.
(embodiment 2)
With the 3-methyl isophthalic acid, the diester that 5-pentanediol and n-capric acid form is as lubricant.
(embodiment 3)
With the 3-methyl isophthalic acid, the diester that 5-pentanediol and pelargonic acid/n-capric acid (mol ratio 50: 50) form is as lubricant.
(embodiment 4)
With the 3-methyl isophthalic acid, the diester that 5-pentanediol and 3,5,5 Trimethylhexanoic acid form is as lubricant.
(embodiment 5)
With the 3-methyl isophthalic acid, the diester that 5-pentanediol and pelargonic acid/3,5,5 Trimethylhexanoic acid (mol ratio 60: 40) form is as lubricant.
(embodiment 6)
With the 3-methyl isophthalic acid, the ester that 5-pentanediol and hexanodioic acid/pelargonic acid (mol ratio 5: 95) form is as lubricant.
(embodiment 7)
With the 3-methyl isophthalic acid, the ester that 5-pentanediol and sebacic acid/n-caprylic acid (mol ratio 11: 89) form is as lubricant.
(embodiment 8)
With the 3-methyl isophthalic acid, the ester that 5-pentanediol and hexanodioic acid/n-caprylic acid (mol ratio 11: 89) form is as lubricant.
(embodiment 9)
With the 3-methyl isophthalic acid, the ester that 5-pentanediol and hexanodioic acid/pelargonic acid/2 methyl caproic acid (mol ratio 12: 44: 44) forms is as lubricant.
(embodiment 10)
With the 3-methyl isophthalic acid, the ester that 5-pentanediol and hexanodioic acid/n-caprylic acid/n-capric acid (mol ratio 5: 57: 38) forms is as lubricant.
(comparative example 1)
The ester that forms with neopentyl glycol and pelargonic acid is as lubricant.
(comparative example 2)
To be used as lubricant as the dioctyl sebacate (DOS) of diester.
Lubricant same amount filling in accordance with regulations with the foregoing description 1～10, comparative example 1 and comparative example 2, constitute the Spindle Motor possess axle and the telescopic Hydrodynamic bearing device that radially radius clearance is that 2.5 μ m, a martensitic stainless steel by diameter 3mm form, sleeve is formed by copper alloy, under the environment of 0 ℃ and 20 ℃, measuring rotation number is the motor current sinking of 5400rpm.
In addition, be 100 with 20 ℃ motor current sinking value of comparative example 1, each routine motor current sinking is shown.Its measurement result is shown in the table of Fig. 3.Again above-mentioned Spindle Motor is placed following 5 hours of the environment of-20 ℃ and-40 ℃, confirm that afterwards each Spindle Motor could rotate startup under-20 ℃ and-40 ℃.
In addition, after 100 ℃ of following continuous operation 500 hours, pull down lining, to the gap of telescopic open end and axle, the liquid level of promptly lubricated dose filling is confirmed with microscope from top, is estimated having or not of liquid level.Under the situation of the liquid level that can not confirm lubricant, steam output is big, because the evaporation liquid level enters into bearing inside, it is not enough that judgement guarantees that performance is kept necessary amounts of lubrication, and reliability is not high.
By the table of Fig. 3 as can be known, arbitrary situation of embodiment 1～embodiment 10 is compared with comparative example 2, and the current sinking of motor all reduces, and also can rotate startup under-20 ℃ extremely low temperature.In embodiment 1,4～10, under-40 ℃ extremely low temperature, also can rotate startup.On the other hand, though the motor current sinking of comparative example 1 is lower than embodiment 1～embodiment 10, can not rotate startup fully under-20 ℃, and not observe liquid level, it is big that steam output also becomes.
In addition, in the case, the yield point of the low-temperature fluidity of the lubricant of embodiment 1～10, comparative example 1 and comparative example 2 also may not be consistent with motor rotation start-up temperature.This is because the environment of the yield point of mensurations such as JIS-K2269 does not add definition storage period, with the solidification value of reality on an equal basis reason cause.
From as can be known above, the torque of Hydrodynamic bearing device of the present invention and Spindle Motor is little, long service life, and under-20 ℃, also can rotate startup.
Hydrodynamic bearing device of the present invention and the motor that has used the Spindle Motor of this device to can be used as disk set and optical disc apparatus use.
Though more than describe the present invention with regard to preferred forms with to a certain degree detailed description, but it is natural that the content that this preferred forms disclosed changes on the details that constitutes, and the variation of the combination of each key element and order only otherwise the claim scope and the technical purpose that break away from invention just can be achieved.
Claims (7)
1. Hydrodynamic bearing device, it is that axle and at least one side of telescopic have the dynamic pressure generation trough, have the Hydrodynamic bearing device of lubricant in above-mentioned spool and the opposed gap of above-mentioned sleeve, it is characterized in that, above-mentioned lubricant contains carbonatoms 4～8, do not have the ester that the saturated unary fatty acid of the big carbonatoms 5～13 of the monounsaturated dicarboxylic acid of the dibasic alcohol of alkyl group side chain and the carbonatoms more than a kind 6～10 and the above-mentioned monounsaturated dicarboxylic acid of the mole ratio more than a kind forms in the β position, and above-mentioned gap is the radially radius clearance of 1～5 μ m.
2. Hydrodynamic bearing device as claimed in claim 1, its feature are that also the saturated unary fatty acid of above-mentioned carbonatoms 5～13 more than a kind is the saturated unary fatty acid of the carbonatoms 5～13 more than 2 kinds.
3. Hydrodynamic bearing device as claimed in claim 2, its feature are that also at least a kind of the saturated unary fatty acid of above-mentioned carbonatoms 5～13 more than 2 kinds is the saturated unary fatty acid of straight chain type.
4. Hydrodynamic bearing device as claimed in claim 3, its feature are that also the saturated unary fatty acid of above-mentioned carbonatoms 5～13 more than 2 kinds is the identical saturated unary fatty acid of carbonatoms.
5. Hydrodynamic bearing device as claimed in claim 1, its feature also is, above-mentioned carbonatoms 4～8, the dibasic alcohol that does not have alkyl group side chain in the β position are the 3-methyl isophthalic acids, the 5-pentanediol, and the saturated unary fatty acid of above-mentioned carbonatoms 5～13 is saturated unary fatty acids of carbonatoms 7～10.
6. Hydrodynamic bearing device as claimed in claim 1, its feature also be, the big inorganic system impurity of the minimum size in the above-mentioned gap of ratio that the above-mentioned lubricant in every Hydrodynamic bearing device is contained is below 1000.
7. Spindle Motor is characterized in that, possesses the described Hydrodynamic bearing device of claim 1.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2004106272 | 2004-03-31 | ||
| JP2004106272A JP2005291332A (en) | 2004-03-31 | 2004-03-31 | Fluid bearing device and spindle motor using it |
| JP2004-106272 | 2004-03-31 | ||
| JP2004-109250 | 2004-04-01 | ||
| JP2004109250 | 2004-04-01 | ||
| JP2004109250A JP2005290256A (en) | 2004-04-01 | 2004-04-01 | Fluid bearing apparatus and spindle motor using the same |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2005100562404A Division CN100427781C (en) | 2004-03-31 | 2005-03-31 | Fluid bearing device and mainshaft motor using same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101216066A CN101216066A (en) | 2008-07-09 |
| CN101216066B true CN101216066B (en) | 2010-09-22 |
Family
ID=35324495
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2008100033279A Expired - Fee Related CN101216066B (en) | 2004-03-31 | 2005-03-31 | Hydrodynamic bearing device and spindle motor using the same |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP2005291332A (en) |
| CN (1) | CN101216066B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9663741B2 (en) * | 2012-06-07 | 2017-05-30 | New Japan Chemical Co., Ltd. | Lubricant base oil for fluid bearing |
| JP7043824B2 (en) * | 2017-12-15 | 2022-03-30 | 日本電産株式会社 | Spindle motor and disk drive equipped with it |
| WO2024150790A1 (en) * | 2023-01-13 | 2024-07-18 | Ｅｎｅｏｓ株式会社 | Complex ester, refrigerator oil, and working fluid composition |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4113642A (en) * | 1976-11-11 | 1978-09-12 | Henkel Kommanditgesellschaft Auf Aktien | High viscosity neutral polyester lubricants |
| CN1428407A (en) * | 2001-12-27 | 2003-07-09 | 新日铁化学株式会社 | Fluid bearing device and lubricating oil composition for bearing |
-
2004
- 2004-03-31 JP JP2004106272A patent/JP2005291332A/en active Pending
-
2005
- 2005-03-31 CN CN2008100033279A patent/CN101216066B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4113642A (en) * | 1976-11-11 | 1978-09-12 | Henkel Kommanditgesellschaft Auf Aktien | High viscosity neutral polyester lubricants |
| CN1428407A (en) * | 2001-12-27 | 2003-07-09 | 新日铁化学株式会社 | Fluid bearing device and lubricating oil composition for bearing |
Non-Patent Citations (2)
| Title |
|---|
| JP特开2001-316687A 2001.11.16 |
| JP特开2002-155944A 2002.05.31 |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2005291332A (en) | 2005-10-20 |
| CN101216066A (en) | 2008-07-09 |
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